ADAPTIVE VARIABLE SPEED CONTROL METHOD, ADAPTIVE VARIABLE SPEED CONTROLLER AND METHOD FOR OPERATING THE SAME

Description

FIELD

The present disclosure relates to the technical field of temperature regulating, and in particular to a method and a device for operating a temperature regulating system at variable speed, to upgrade the existing temperature regulating system that operates at constant speed. The method uses recorded compressor run time data to adapt the variable speed HVAC system to the houses where it is installed.

BACKGROUND

Buildings and other enclosed spaces where people live and work are heated, cooled and ventilated by heating, ventilation and air conditioning devices. Air conditioning compressors and heat pumps are commonly driven by single speed motors. The single speed motor operates at constant speed and is switch on and off alternately under the control of a thermostat, to maintain the temperature inside the space. The single speed motor either operates at full speed or is shut down, and is terribly noisy.

In recent years, compressors as well as indoor and outdoor fans are driven by variable speed drives. The compressors and fans operate at variable speed under control of specialized thermostats, instead of being switched on and off alternately, to maintain the temperature at a setpoint. Since the compressors and fans generally operate at speed lower than the maximum speed, energy consumption is reduced, thereby improving overall efficiency. The upgrading from the single-speed motor to the variable-speed drive increases the efficiency and is less noisy. However, replacement of the single-speed motor by the variable-speed drive necessitates at least one of replacement of the thermostat and replacement of the wiring between the single-speed motor and the thermostat, resulting in high costs. Replacement of the single-speed motor by the variable-speed drive involving no replacement of the thermostat and no replacement of the wiring between the single-speed motor and the thermostat contributes a decrease in costs. Therefore, it is desired to solve the technical problem of how to adapt the indoor load to the variable speed without replacing the thermostat and the wiring.

The patent document U.S. Ser. No. 12/844,709 also records the state of the art.

SUMMARY

In view of this, a variable speed control method, a variable speed controller and a method for operating the variable speed controller are provided according to embodiments of the present application. Therefore, the existing temperature regulating system operating at constant speed can be upgraded to operate at variable speed at low costs.

The following technical solutions are provided according to the present disclosure, to realize the above objects.

The method for operating the variable speed controller is provided according to embodiments of the present disclosure. The variable speed controller is preset with a first preset period of time. The method includes:

• • receiving an on signal from a thermostat;
  • driving a compressor at an initial system operation speed;
  • monitoring a system operation time and an outdoor load;
  • determining whether the system operation time is greater than the first preset period of time;
  • increasing the system operation speed if the system operation speed is less than a maximum system operation speed and determined that the system operation time is greater than the first preset period of time;
  • detecting a change in the outdoor load in an operation and regulating the system operation speed based on at least the change in the outdoor load; and
  • determining whether an off signal from the thermostat is received, and turning off the compressor if the off signal is received.

In the method for operating the variable speed controller, the system operation speed applied to the compressor is regulated based on the monitoring result about the system operation time and the outdoor load in the operation. It is unnecessary to replace the thermostat and the wiring of the original single-speed unit or dual-speed unit, thereby reducing costs on replacement.

The variable speed controller is applied to a temperature regulating system. The temperature regulating system includes at least a thermostat, an outdoor load detection unit and a compressor. The variable speed controller includes an input unit, an inverter unit and a main control unit. An output end of the input unit is electrically connected to the inverter unit. The main control unit includes at least an on-off signal interface, an outdoor load interface, a processor and a memory. The on-off signal interface is configured to be electrically connected to the thermostat, to receive an on or off signal from the thermostat. The outdoor load interface is configured to be electrically connected to the outdoor load detection unit. The memory is for storing computer-readable instructions. The computer-readable instructions include a first preset period of time, a first preset condition and a second preset condition. The processor is configured to invoke the computer-readable instructions to instruct the variable speed controller to perform the method for operating the variable speed controller.

The variable speed controller is provided with the on-off signal interface, an outdoor load interface, a processor and a memory. The variable speed controller receives the on or off signal from thermostat through the on-off signal interface, and receives an outdoor load status through the outdoor load interface. The processor operates the variable speed controller by executing the computer-readable instructions in the memory. Therefore, the operating applied to the compressor can be variable. In this way, the constant-speed unit or dual-speed unit can be upgraded at low costs.

A method for controlling a temperature regulating system is provided according to embodiments of the present disclosure. The temperature regulating system includes at least a thermostat, a variable speed controller, an outdoor load detection unit, and a compressor. The thermostat is electrically connected to the variable speed controller to send an on or off signal to the variable speed controller. The variable speed controller is electrically connected to the compressor for applying a system operation speed to the compressor. The outdoor load detection unit is electrically connected to the variable speed controller to send the outdoor load status to the variable speed controller. The method for controlling the temperature regulating system includes:

• • sending an on signal to the variable speed controller by the thermostat;
  • receiving the on signal and driving the compressor at an initial system operation speed, by the variable speed controller;
  • monitoring a system operation time and an outdoor load, by the variable speed controller;
  • increasing the system operation speed applied to the compressor by the variable speed controller, if the system operation speed is less than a maximum system operation speed and the system operation time is greater than the first preset period of time;
  • detecting a change in the outdoor load in an operation and regulating the system operation speed based on at least the change in the outdoor load;
  • determining whether an indoor temperature reaches a set temperature by the thermostat and sending an off signal to the variable speed controller by the thermostat if determined that the indoor temperature has reached the set temperature; and
  • stopping applying the system operation speed to the compressor by the variable speed controller in receipt of the off signal.

In the method for controlling the temperature regulating system, the compressor speed is regulated based on the on or off signal from the thermostat and the change in the outdoor load. No communication line is added between the variable speed controller and the thermostat (since only the digital signal is transmitted) during the upgrade from the constant-speed unit or dual-speed unit to the temperature regulating system that operates at variable speed.

BRIEF DESCRIPTION OF THE DRAWINGS

For more clearly illustrating the technical solutions in embodiments of the present disclosure or in the conventional technology, drawings referred to describe the embodiments or the conventional technology will be briefly described hereinafter. Apparently, the drawings in the following description show only several embodiments of the present disclosure. those skilled in the art can obtain other drawings based on these drawings without any creative efforts.

FIG. 1 shows a flowchart illustrating a method for operating a variable speed controller according to an embodiment of the present disclosure;

FIG. 2 shows a flowchart illustrating the method for operating the variable speed controller according to another embodiment of the present disclosure;

FIG. 3 shows a flowchart illustrating the method for operating the variable speed controller according to another embodiment of the present disclosure;

FIG. 4 shows a structural block diagram of the variable speed controller according to an embodiment of the present disclosure;

FIG. 5 shows a schematic diagram illustrating regulation of the compressor speed based on the outdoor temperature in a cooling mode;

FIG. 6 shows a table illustrating the initial speed according to an embodiment; and

FIG. 7 shows a table illustrating the variable speed according to an embodiment;

FIG. 8 shows multiple compressor speed control using a single stage thermostat;

FIG. 9 shows multiple compressor speed control using a two-stage thermostat in low stage; and

FIG. 10 shows multiple compressor speed control using a two-stage thermostat in high stage.

DETAILED DESCRIPTION

The present application relates to a temperature regulating system. The existing constant-speed temperature regulating system is upgraded to a variable-speed temperature regulating system.

The existing constant-speed temperature regulating system includes a single-speed unit and a dual-speed unit that send an on or off signal through a thermostat to a controller of a compressor or a fan, to operate the compressor or the fan at constant speed. Therefore, the temperature in the space maintains at a setpoint. The dual-speed unit, when turned on for the first time, operates at the grade 1 under control of the thermostat if the measured temperature in the space approximates the setpoint. The dual-speed unit operates at the grade 2 if the measured temperature in the space considerably deviates from the setpoint. In such configuration, if the unit or system is on and the setpoint remains constant, the thermostat instructs the unit to operate at the grade 1 preferably and instructs the unit to operate at the grade 2 only when the grade 1 is insufficient to regulate the measured temperature in the space approximates the setpoint. That is, the unit generally operates at the grade 1, which is more efficient and quieter. The unit operates at the grade 2 only when the cooling or heating demand increases, in order to maintain the temperature inside the space approximately at the setpoint. When the unit is turned on for the first time or when the setpoint is different, that is, the initial temperature measured inside the space considerably deviates from the setpoint, the thermostat instructs the unit to operate at the grade 2 directly. A tri-speed unit with an additional thermostat operates similarly to the dual-speed unit. In addition, cooperation between a multi-speed compressor and a thermostat is necessary. For example, the thermostat is equipped with multiple single-speed compressors or a multi-speed compressor at the request of a multi-speed unit. At least one of the indoor fan and the outdoor fan operate at variable speed, depending on the number or capacity of the compressor. The dual-speed (dual-grade) unit or multi-speed unit performs better than the single-speed unit and inferior to the variable-speed unit in terms of efficiency and noise. The replacement of the single-speed, dual-speed or another multi-speed unit by a variable-speed unit generally necessitates the replacement of the thermostat and the wiring, and also the replacement of one or more of the indoor fan (blower), the compressor, the compressor controller, the expansion valve or the like. The replacement of all the indoor devices is generally inevitable during the upgrade of the variable speed system, resulting in high costs.

In view of this, a method for controlling a temperature regulating system is provided in a first aspect of embodiments of the present application. A thermostat applied to a discrete speed (for example, single speed or dual speed) unit is configured to control a variable speed temperature regulating system or a variable speed unit, without replacing at least one of the thermostat and the corresponding wiring. A method for operating a variable speed controller is provided according to embodiments of the present application. The variable speed controller is for replacing a constant speed controller of an original single speed unit or a dual speed unit. The variable speed controller is preset with a first preset period of time Tsmax, which is the longest time to be spent on the operation at a set constant speed. The excessively long first preset period of time indicates a longer time spent on regulating the measured temperature inside the space to the setpoint, resulting in poor user experience. Accordingly, an acceleration is performed in order to regulate the measured temperature inside the space to the setpoint quickly. Correspondingly, a second preset period of time Tsmin is set in other embodiments. The second preset period of time is the shortest time to be spent on the operation at the set constant speed. With an excessively short second preset period of time, the system is frequently started, resulting in low efficiency and terrible noise. In the cooling mode, the longer the first preset period of time, the better the energy efficiency of the system. However, the evaporating temperature approximates the temperature measured at the return air vent, resulting in poor dehumidification. Therefore, the first preset period of time is customized by user, for example, by a jumper or a dip switch. The variable first preset period of time is set for the variable speed controller, so that the user can choose between the energy efficiency and the dehumidification. In this case, the state of the jumper or the dip switch indicates at least one of the energy efficiency and the dehumidification.

As shown in FIG. 1, the method for operating the variable speed controller includes the following steps S1 to S8.

In step S1, an on signal from a thermostat is received. The thermostat is located in the space where the temperature regulating system is located. The thermostat sends an on signal or an off signal to the variable speed controller based on a set temperature and a measured temperature inside the space.

In step S2, a compressor is driven at an initial system operation speed. The initial system operation speed is preset, is related to an outdoor load, or is determined form the table as shown in FIG. 7 when the compressor operates for the first time. The correspondence between the initial system operation speed for the first operation and the outdoor load is stored in the variable speed controller, so that the initial system operation speed for the first operation can be determined based on the outdoor load. The initial system operation speed for the subsequent operation depending on the operating state in the previous operation or the interval between the previous and current operations, or is determined from the table as shown in FIG. 7.

In step S3, the system operation time and the outdoor load are monitored.

In step S4, it is determined whether the operation has lasted longer than the first preset period of time. That is, it is determined whether the operation in one cycle has lasted longer than the first preset period of time. The method proceeds to step S5 if determined that the operation has lasted longer than the first preset period of time.

In step S5, the system operation speed is increased if determined that the operation has lasted longer than the first preset period of time and the system operation speed is less than a maximum system operation speed.

In step S6, it is determined whether there is a change in the outdoor load during the operation. The system operation speed of the compressor is controlled based on at least the change in the outdoor load.

In step S7, it is determined whether an off signal from the thermostat is received. The method proceeds to step S8 if determined that the off signal is received.

In step S8, the compressor is stopped being driven.

In the above embodiment, the system operation time is recorded and the change in the outdoor load is monitored in each cycle. The speed-up or slowdown is performed based on the system operation time and the change in the outdoor load. Therefore, the compressor can operate at variable speed, thereby balancing the comfort and the energy efficiency.

In an embodiment, the system operation speed of the compressor is controlled based on the change in the outdoor load. A first preset condition and a second preset condition are set for the variable speed controller. The system operation speed is increased by the variable speed controller when the first preset condition is met, and is decreased by the variable speed controller when the second preset condition is met. The first and second preset conditions are related to the change in the outdoor load.

As shown in FIG. 2, the method for operating the variable speed controller includes the following steps S101 to S110.

In step S101, an on signal is received from the thermostat.

In step S102, the compressor is driven at an initial system operation speed.

In step S103, the system operation time and the outdoor load are monitored. The system operation time is recorded and the change in the outdoor load is monitored in each cycle. The speed-up or slowdown is performed based on the system operation time and the change in the outdoor load.

In step S104, it is determined whether the recorded system operation time is longer than the first preset period of time. The method proceeds to step S107 if determined that the operation has lasted longer than the first preset period of time and the system operation speed is less than the maximum system operation speed. In step S107, the system operation speed is increased to enhance the regulation. Therefore, the temperature measured inside the space can reach the set temperature quickly.

In step S105, it is determined whether the change in the outdoor load during the operation meets the first preset condition. The method proceeds to step S107 if determined that the change in the outdoor load already meets the first preset condition. In step S107, the system operation speed is increased. In step S106, it is determined whether the change in the outdoor load during the operation meets the second preset condition. The method proceeds to step S108 if determined that the change in the outdoor load already meets the second preset condition. In step S108, the system operation speed is decreased. The change in the outdoor load meeting the first preset condition indicates that the outdoor load becomes harsh and therefore the temperature regulation is enhanced. The change in the outdoor load meeting the second preset condition indicates that the outdoor load becomes gentle, and therefore the set temperature can be reached easily. The change in the outdoor load is measured as the outdoor temperature, coil temperature or condensing pressure and other parameters that represent the outdoor load status.

To further improve the efficiency by regulating the speed multiple times or frequently, the method returns to step S103 in which the system operation time is recorded and the change in the outdoor load is monitored, and thence to steps S104-S108 to determine to increase or decrease the system operation speed. Further, step S109 is performed, that is, it is determined whether an off signal from the thermostat is received. The method proceeds to step S8 if determined that the off signal is received. In step S110, the compressor is stopped being driven.

The above steps S101 to S110 form one cycle. The system operation speed of the compressor driven by the variable speed controller is regulated based on the system operation time and the outdoor load in the cycle. Therefore, the compressor operates at variable speed. Only the digital signal indicating the ON or OFF state is transmitted between the variable speed controller and the thermostat, and therefore no communication line is arranged between the variable speed controller and the thermostat. The thermostat and corresponding wiring applied to the single-speed or dual-speed unit is unnecessarily replaced, thereby reducing the costs for upgrading the single-speed or dual-speed unit to the variable-speed controller. In addition, on receipt of the on signal, the evaporator fan motor is operated at the blower speed to drive the evaporator fan so that the indoor air passes through the evaporator and the space, and the condenser fan motor is operated at the condenser fan speed to move the outdoor air through the condenser fan, therefore the temperature inside the space is regulated. The present application focuses on regulation on the speed of the compressor. For the regulation on the speed of other motors, reference can be made to the method herein or other approaches, which is not limited herein. The indoor and outdoor fans may also operate at speed varying with the compressor speed during the operation.

The compressor is started and stopped multiples times in the operation (that is, one cycle). As shown in FIG. 3, the method for operating the variable speed controller further includes the following steps S211 to S212 for determining the initial system operation speed for other operations than the first operation.

In S211, the on signal from the thermostat is received again. The compressor is driven at the initial system operation speed on receipt of the on signal. The initial system operation speed here is determined based on the operating status in the previous operation or the interval between the previous operation and the current operation. The initial system operation speed here is determined in step S212 including sub-steps S2121 to S2127.

In step S2121, it is determined whether the system operation speed changes in the previous operation. The variable speed controller knows the system operation speed and the system operation time. The method proceeds to steps S2122 and S2123 if determined that the system operation speed has changed in the previous operation.

In step S2122, it is determined whether the change in the outdoor load in the interval (from the instant when the compressor stops previously to the instant when the compressor is started currently) meets the first preset condition and whether the final system operation speed S_(n-1)final in the previous operation is less than the maximum system operation speed Smax. The method proceeds to step S2124 if determined that the change in the outdoor load already meets the first preset condition and the S_(n-1)final is less than the Smax. In step S2124, the initial system operation speed S_(n)start for the present operation is set to be larger than S_(n-1)final. The change in the outdoor load meeting the first preset condition indicates that the outdoor load becomes harsh, and therefore the system operation speed is increased to reach the set temperature.

In step S2123, it is determined whether the change in the outdoor load in the interval meets the second preset condition and whether S_(n-1)final is greater than a minimum non-zero system operation speed Smin. If determined that the change in the outdoor load already meets the second preset condition and S_(n-1)final is greater than Smin, the initial system operation speed S_(n)start for the present operation is set to be smaller than S_(n-1)final.

In the present embodiment, if the change in the outdoor load over the interval between two operations (for example, an nth operation and an [n−1]th operation) meets neither the first preset condition nor the second preset condition, the initial system operation speed S_(n)start for the present operation is set to S_(n-1)final. The maximum system operation speed Smax and the minimum non-zero system operation speed Smin described above depend on parameters of the variable speed controller.

The method proceeds to step S2127 if it is determined in step S2121 that the system operation speed does not change during the previous operation (i.e., the nth operation). In step S2127, it is determined whether the previous operation has lasted less than the second preset period of time T_smin. The method proceeds to step S2125 if determined that the previous operation has lasted less than T_smin. In step S2125, the initial system operation speed S_(n)start for the present operation is set to be less than S_(n-1)final. S_(n-1)final is greater than the minimum non-zero system operation speed Smin. The method proceeds to step S2126 if determined that the previous operation has lasted for at least T_smin. In step S216, the initial system operation speed S_(n)start for the present operation is set to S_(n-1)final.

In the above embodiment when the temperature regulating system in which the variable speed controller is located operates in the cooling mode, the first preset condition is that the change in the outdoor load is greater than a first preset value, and the second preset condition is that the change in the outdoor load is less than a second preset value. When the temperature regulating system in which the variable speed controller is located operates in the heating mode, the first preset condition is that the change in the outdoor load is less than a third preset value, and the second preset condition is that the change in the outdoor load is greater than a fourth preset value. The first preset value, the second preset value, the third preset value, and the fourth preset value each may be a constant, depending on the outdoor load parameter and implementations. The outdoor load parameter includes one or more of the outdoor coil temperature, the outdoor ambient temperature, condensing pressure and so on, which are equivalent to each other and positively correlated with each other.

In an embodiment, the outdoor load parameter is the outdoor ambient temperature. The first preset value is set to +n, the second preset value is set to −n, the third preset value is set to −m, and the fourth preset value is set to +m. m and n are positive numbers. For example, m and n are equal. The change in the outdoor load is acquired as follows. An initial outdoor ambient temperature Toutstart at the instant when the variable speed controller is shut down or when the system operation speed is changed is recorded. The outdoor ambient temperature Tout when the variable speed controller operates is monitored. The change in the outdoor load is acquired from dT=(Tout−Toutstart).

In an example, m and n each are equal to 2. In the cooling mode, as shown in FIG. 5, dT>2 indicates that the outdoor ambient temperature increases by more than 2° F. over one cycle (e.g., the S_n-1th cycle), and accordingly the system operation speed is increased from S_(n-1)start to S″_(n-1). dT<−2 indicates that the outdoor ambient temperature decreases by more than 2° F., and accordingly the system operation speed is decreased from S_(n-1)start to S′_(n-1). −2≤dT≤2 indicates that the change in the outdoor load meets neither the first preset condition nor the second preset condition. That is, the change in the outdoor load is insignificant, and the system operation speed remains unchanged. For the determination of the initial system operation speed, reference can also be made to FIG. 5. dT_n-1> indicates that the outdoor ambient temperature increases by more than 2° F. over the interval, and therefore the initial system operation speed S_(n)start for the present cycle is increased. S_(n)start is greater than S_(n-1)final and is equal to S″_(n-1). In an embodiment, the system operation speed is regulated in real time. That is, dT is compared with the first, second, third and fourth preset values multiple times, and accordingly the system operation speed is regulated multiple times. The updating cycle may be set randomly. The updating cycle is also called the speed change cycle. Generally, a minimum value is set for the speed change cycle to ensure system stability. In the heating mode, dT<−2 indicates that the outdoor temperature decreases by more than 2° F., and accordingly the system operation speed is increased. dT>2 indicates that the outdoor temperature increases by more than 2° F., and accordingly the system operation speed is decreased. −2≤dT≤2 indicates that the change in the outdoor load meets neither the first preset condition nor the second preset condition. That is, the change in the outdoor load is insignificant, the system operation speed remains unchanged. The determination of the initial system operation speed is similar to that in the cooling mode, except that the first and second preset conditions are different.

In the above embodiments, the initial system operation speed generally indicates the first initial system operation speed when the temperature regulating system starts operating from a sleep mode (in which the system is not powered off) or the initial system operation speed in different cycles in operation. Further, in order to determine the system operation speed at the instant when the temperature regulating system is powered up, the initial system operation speed or the table as shown in FIG. 6 is preset for the variable speed controller according to the present application. Each time when the variable speed controller is powered up, the initial system operation speed is preset or is determined from the table as shown in FIG. 6. It should be noted the initial system operation speed is preset to be relatively high in order to speed up the heating or colling. For example, the initial system operation speed is preset to the maximum system operation speed or the speed corresponding to the highest gear.

Reference is made to FIG. 6. The table shows the correspondence between the operating mode (Heating or Cooling), the outdoor load range (e.g., the outdoor ambient temperature Outdoor Temp.) and the system operation speed (Initial Compressor Speed). After the variable speed controller is powered on, the initial system operation speed is determined based on the set operating mode, and the outdoor load range in which the outdoor load is currently located. For example, the operating mode is set to the cooling mode, and the outdoor ambient temperature is currently 75° F., the initial system operation speed determined as 2C which corresponds to a grade 2 when the temperature regulating system is in the cooling mode. As shown in FIG. 6, the compressor is provided with five gears (1C, 2C, 3C, 4C and 5C) in the cooling mode and five gears (1H, 2H, 3H, 4H and 5H) in the heating mode.

The initial system operation speed is determined from the table shown in FIG. 7 as follows.

The table illustrating the variable speed and the third preset period of time are preset for the variable speed controller. The third preset period of time is shorter than the first preset period of time (i.e., the maximum desired system operation time). The third preset period of time improves the balance between comfort and the energy efficiency. The third preset period of time is set, or is obtained by subtracting a preset difference Δt from the first preset period of time. In the cooling mode, the balance between the energy efficiency and the dehumidification is improved by modifying the first preset period of time or the preset difference Δt. In an embodiment, the first preset period of time or the preset difference value Δt depend a state of a jumper or a dip switch. In the embodiments, the state of the jumper or the dip switch indicates the energy efficiency and/or the dehumidification, so that the variable speed controller is provided with the variable first preset period of time or the variable preset difference. Therefore, the user can choose between the energy efficiency and the dehumidification.

In the embodiments, the variable speed controller is provided with X gears. The table in FIG. 7 shows M outdoor load ranges each provided with X gears. N system operation times are set for each gear in the outdoor load range. The variable speed controller calculates an average system operation time or a median system operation time or a weighted average system operation time corresponding to the gear based on the N system operation times.

The initial system operation speed is determined as follows. The outdoor load range is determined based on the outdoor load. The third preset period of time is compared with the X average system operation times or median system operation times or weighted average system operation times in the determined outdoor load range. A speed corresponding to one of the X average system operation times or median system operation times or weighted average system operation times that is system operation time closest to the third preset period of time is determined as the initial system operation speed. Preferably, the rotation speed corresponding to the average system operation time/median system operation time/weighted average system operation time that is closest to the third preset period of time and smaller than the third preset period of time is set as the initial system operation speed.

M, X, and N are positive integers. X is greater than or equal to 2. M, X, and N depend on the temperature regulating system and the outdoor environment.

In FIG. 7, for example, in the cooling mode, and X is equal to 4, M is equal to 4, and N is equal to 10. Assuming that the outdoor ambient temperature is 86° F. currently, and accordingly the outdoor load range is determined as the range of (85-87° F.). The average system operation times or median system operation times or weighted average system operation times corresponding to the four gears within this outdoor load range is found, and the average system operation time or median system operation time or weighted average system operation time closest to the third preset period of time is determined as the initial system operation speed. Assuming that the third preset period of time is 40, and accordingly the speed corresponding to the third gear is selected to control the compressor.

In some embodiments, the system operation speed in the cycle is determined from the table showing the variable speed as follows. If the outdoor load changes to another outdoor load range in the cycle, the system operation speed is regulated by: comparing the third preset period of time with the X average system operation times or median system operation times or weighted average system operation times in the outdoor load range in which the changed outdoor load is located; and determining the speed corresponding to the average operation closest to the third preset period of time as the latest system operation speed.

Reference is made to FIG. 7. If the outdoor ambient temperature changes from 86° F. to 88° F. in the cycle, the system operation speed is determined from an outdoor load range of (87-89° F.). That is, the average system operation times or median system operation times or weighted average system operation times corresponding to the different gears in the outdoor load range are compared with the third preset period of time, and the latest system operation speed depends on the gear corresponding to the average operation closest to the third preset period of time. It should be understood that, for the operation rather than the first operation, the present temperature range is compared with the temperature range when the compressor is previously shut down. In the cooling mode, the gear is determined from the table as shown in FIG. 7 if the temperature decreases to a smaller range. If the temperature remains in the same range or rises to a greater range, the gear determined from the table as shown in FIG. 7 theoretically is not lower than the gear in which the compressor previously shut down. If the actually determined gear is lower than the gear in which the compressor previously shut down, the compressor is operated in the gear in which the compressor previously shut down or in a higher gear that the determined gear instead of the determined gear, for the cooling effects. In the heating mode, the gear is determined from the table as shown in FIG. 7 if the temperature rises to a smaller range. If the temperature remains in the same range or decreases to a greater range, the gear determined from the table as shown in FIG. 7 theoretically is not lower than the gear in which the compressor previously shut down. If the actually determined gear is lower than the gear in which the compressor previously shut down, the compressor is operated in the gear in which the compressor previously shut down or in a higher gear that the determined gear instead of the determined gear, for the heating effects.

In some embodiments, the table as shown in FIG. 7 is preset. In other embodiments, an initial table is set before first use and is subsequently updated depending on the operating condition of the system. The table is updated as follows. If the system operation speed of the compressor remains unchanged in the operation, that is, the compressor operates at a single speed throughout the operation, it is further determined whether the system operation time exceeds a median or average or weighted average of the N system operation times corresponding to the gear within the corresponding outdoor load range. If yes, the minimum among the N system operation times is replaced with the system operation time. If no, the maximum among the N system operation times is replaced with the system operation time. Further, the minimum system operation time and the maximum system operation time in each gear are set to limit the range in order to avoid an abnormal system operation time of the compressor resulted from a sudden change in the set temperature, for example, due to a touch on the screen by a child out of curiosity. The minimum system operation time and the maximum system operation time are set in each gear for all the ranges. The system operation time is compared with the minimum system operation time and the maximum system operation time. The above replacement is performed only when the system operation time is between the minimum system operation time and the maximum system operation time. In the same range, the minimum system operation time in a lower gear is greater than the minimum system operation time in a higher gear, and the maximum system operation time in the lower gear is greater than the maximum system operation time in the higher gear.

In the embodiments, the N system operation times corresponding to the same gear and the N same outdoor load in the operation previous to the present operation. If the system operation speed remains unchanged throughout the present operation, the table is updated based on the comparison about the system operation time, so that the determination of the system operation speed is in line with the actual use of the temperature regulating system.

A variable speed controller 11 is provided according to a second aspect of the embodiments of the present application, as shown in FIG. 4. The variable speed controller 11 is arranged in the temperature regulating system. The temperature regulating system also includes at least a thermostat 12, an outdoor load detection unit 13 and a compressor 14. The temperature regulating system may further include an evaporator, a condenser, a blower, and so on. Since the present application is centered on regulation of the compressor speed, and therefore only the relevant devices are detailed. The variable speed controller 11 includes an input unit 111, an inverter unit 112 and a main control unit 113. An output end of the input unit 111 is electrically connected to the inverter unit 112. The input unit 111 is electrically connected to the utility power system, and converts utility power into high-voltage direct current power and outputs the high-voltage direct current power to the inverter unit 112. The inverter unit 112, under the control of the main control unit 113, converts the high-voltage direct current power into three-phase alternating current power and outputs the three-phase alternating current power to the compressor 14 to drive the compressor. The main control unit 113 includes at least an on-off signal interface 1131, an outdoor load interface 1132, a processor 1133 and a memory 1134.

The on-off signal interface 1131 is configured to be electrically connected to the thermostat 12, to receive an on signal or an off signal sent by the thermostat 12.

The outdoor load interface 1132 is configured to be electrically connected to the outdoor load detection unit 13. The outdoor load detection unit 13 sends the detected outdoor load status to the main control unit.

The main control unit includes a microcontroller (MCU). The on-off signal interface 1131 sends the received on or off signal to the MCU, and the outdoor load interface 1132 sends the received outdoor load status to the MCU. The MCU controls, based on the on or off signal and the outdoor load status, the frequency of the three-phase alternating current power outputted from the inverter unit, to regulate the compressor speed.

The memory is configured to store computer-readable instructions which include the first preset period of time, a software program, the first preset condition, the second preset condition, the first preset value, the second preset value, the third preset value, the fourth preset value, the initial compressor speed and the variable compressor speed as described in the above embodiments. The processor is configured to invoke the computer-readable instructions to operate the variable-speed controller 11 to perform the method according to any one of the embodiments described in the first aspect.

In an embodiment, the outdoor load detection unit 13 is a temperature sensing unit. The temperature sensing unit is configured to sense a coil temperature or outdoor ambient temperature for the temperature regulating system, or sense both the coil temperature and the outdoor ambient temperature. In another embodiment, the outdoor load detection unit is a pressure measuring unit configured to measure the condensing side pressure of the outdoor condenser. In other embodiments, the outdoor load detection unit 13 includes a pressure measuring unit and a temperature sensing unit, to acquire the outdoor load status more accurately, thereby acquiring parameters for regulating the compressor speed more accurately.

The temperature regulating system to which the variable speed controller is applicable includes at least the thermostat, the variable speed controller, the outdoor load detection unit and the compressor. As shown in FIG. 4, the thermostat 12 is electrically connected to the variable speed controller 11, and sends an on or off signal to the variable speed controller 11. The variable speed controller 11 is electrically connected to the compressor 14, and drives the compressor 14. The outdoor load detection unit 13 is electrically connected to the variable speed controller 11, and sends the detected outdoor load status to the variable speed controller 11. For operation of the temperature regulating system, reference can be made to the method for operating the variable speed controller disclosed in the first aspect. The temperature regulating system operates as follows. The thermostat 12 sends an on signal to the variable speed controller 11. The variable speed controller 11 drives the compressor 14 at an initial system operation speed on receipt of the on signal. The variable speed controller 11 times the operation and monitors a change in the outdoor load. The change in the outdoor load depends on the outdoor load status detected by the outdoor load detection unit 13. If the operation lasted longer than the first preset period of time and the variable speed controller 11 is operating at a speed less than a maximum system operation speed, the variable speed controller 11 increases the system operation speed to drive the compressor 14. The variable speed controller 11 determines whether the change in the outdoor load is different and drives the compressor based on at least the change in the outdoor load.

The compressor speed is regulated after it is determined whether the change in the outdoor load in the operation meets the first preset condition or the second preset condition. If the change in the outdoor load in the operation already meets the first preset condition, the compressor speed is increased. If the change in the outdoor load in the operation already meets the second preset condition, the compressor speed is decreased. Alternatively, the compressor speed is regulated based on the table as shown in FIG. 7. Reference can be made to the embodiments of the method for operating the variable speed controller disclosed in the first aspect for further details.

The thermostat 12 determines whether the indoor temperature reaches the set temperature, and sends an off signal to the variable speed controller 11 if determined that the indoor temperature has reached the set temperature. The variable speed controller 11 stops driving the compressor 14 on receipt of the off signal, and the compressor stops operating. It should be noted that, in the cooling mode, the indoor temperature reaching the set temperature generally indicates that the indoor temperature is less than or equal to a difference between the set temperature and a hysteresis error. In the heating mode, the indoor temperature reaching the set temperature generally indicates that the indoor temperature is greater than or equal to a sum of the set temperature and the hysteresis error. The hysteresis error is preset.

The thermostat and the outdoor load detection unit in the temperature regulating system cooperate with the variable speed controller in the regulation of the compressor speed. Therefore, the temperature regulating system is highly efficient and comfortable. The thermostat receives the set temperature and measures the space temperature, and sends the on or off signal to the variable speed controller base on the set temperature and the measure temperature. The variable speed controller determines the output based on its own operating conditions and the change in the outdoor load, to regulate the compressor speed. Reference is made to the above embodiments for details about the regulation of the compressor speed and the determination of the initial compressor speed of each cycle.

The method for operating the variable speed controller in the outdoor unit is detailed above. The control of the indoor unit is also essential to the temperature regulating system. The temperature regulating system further includes an indoor control unit. The thermostat is electrically connected to the indoor control unit. The indoor control unit is electrically connected to the variable speed controller. The thermostat sends the on or off signal to the variable speed controller through at least the indoor control unit. In an embodiment, the indoor control unit includes an indoor fan controllable switch transistor, at least 2 temperature sensors and a processing unit. One of the temperature sensors measures a temperature at an air outlet of the heat exchanger. The other temperature sensor measures a surface temperature of the heat exchanger. The surface temperature represents the evaporation temperature. Alternatively, the surface temperature is obtained through conversion based on the saturation temperature and pressure measured by a pressure sensor. For a given indoor dry bulb temperature DB/wet bulb temperature WB and cooling demand (compressor speed), there is an optimal indoor airflow that maximizes indoor dehumidification. For a given indoor/outdoor condition, the evaporative temperature in prone to rise due to excessive airflow and consequently the latent heat is decreased. Insufficient airflow results in a decrease in the total cooling capacity and the potential cooling capacity. Under the same compressor speed and the same fan speed, the total cooling capacity and the sensible heat ratio (SHR) of the temperature regulating system (refrigeration air conditioner/heat pump) are constant. Increasing the indoor fan speed leads to an increase in the total cooling capacity and the sensible cooling capacity, and decreasing the indoor fan speed leads to a decrease in the total cooling capacity and the sensible cooling capacity. Conventionally, the compressor speed is variable, which is sufficient for controlling the indoor DB temperature. However, the compressor speed that matches the DB fails to match the DB and the WB simultaneously. The existing temperature regulating system is incapable of communications between the indoor and outdoor units, the compressor speed depends on only the outdoor unit, and the dehumidification depends on only the indoor fan.

Conventionally, the indoor fan speed is controlled based on the duct static pressure, the capacity and the energy efficiency. The fan speed is variable for dehumidification. The indoor fan speed and the compressor speed are both regulated to match the sensible cooling capacity with the sensible cooling load. The comfort can be maximized by balancing the evaporation temperature and the outlet temperature.

For the temperature regulating system incapable of communications between the indoor and outdoor units, the indoor fan is controlled as follows. When the system operation time exceeds the preset time Time1, the indoor fan speed is decreased by one gear at Time2 intervals or the indoor fan airflow is decreased by a preset airflow CFM1, thereby controlling the indoor fan at a lower speed. Therefore, the surface temperature of the evaporator is decreased for better dehumidification effects.

After that, when the system operating time exceeds the preset time Time3, the indoor fan speed returns to the original gear or airflow, for air circulation.

When the system operating time exceeds the preset time Time4, and the measured evaporator surface temperature is lower than the preset temperature Temp1 (where Temp1 is generally preset approximately equal to or slightly higher than 0° F.), the indoor fan speed is increased by one gear at Time5 intervals or the indoor fan airflow is increased by a preset airflow CFM2, to increase the indoor fan speed, thereby preventing the indoor heat exchanger coil from freezing. Otherwise, the heat exchanger may operate improperly.

Time1, Time2, Time3, Time4, Time5, CFM1, and CFM2 are specific to the system and are determined experimentally. Paragraphs to describe only one way how the indoor blower airflow rate may be controlled by the indoor section control without knowledge about the compressor speed. Many such indoor airflow rate control methods exist and will not be described in this document.

On the basis of the above variable speed control method, variable speed controller and the method for operating the variable speed controller, FIG. 8 shows multiple compressor speed control using a single stage thermostat. In this embodiment, the system has cooling mode and heating mode. FIG. 9 shows multiple compressor speed control using a two-stage thermostat in low stage. FIG. 10 shows multiple compressor speed control using a two-stage thermostat in high stage. In this embodiment, the system has cooling mode and heating mode.

The same or similar parts between the various embodiments in the specification can be referred to each other, and each of the embodiments focuses on differences from other embodiments. In particular, the system or the system embodiments are similar to the method embodiments, and are described in brief relatively, and reference may be made to the description of the method embodiments for relevant matters. The system and the embodiments of the system are only illustrative, units described as discrete components may or may not be physically separated. Components shown as units may or may not be physical units, that is, may be located in one place or may be distributed among multiple network units. Some or all of the modules may be selected to implement the solution in the embodiments, depending on actual demands. Those skilled in the art can understand and implement the present disclosure without any creative effort.

Those skilled in the art should further understand that, units and steps described in conjunction with the embodiments disclosed herein may be implemented by electronic hardware, computer software or a combination thereof. In order to clearly describe interchangeability of the hardware and the software, the units and steps in the embodiments are generally described above inters of functions. Whether these functions are implemented by hardware or software depends on the specific application and design constraints for the technical solution. Those skilled in the art can implement the described functions for each particular application in various manners. Such implementation should not be considered as beyond the scope of the present disclosure.

Based on the above description of the disclosed embodiments, features described in the embodiments in the specification may be replaced or combined with each other, so that those skilled in the art can implement or use the present disclosure. Those skilled in the art can readily conceived various modifications to the embodiments, and the general principle herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application should not be limited to the embodiments disclosed herein, but has the widest scope in accordance to the principle and the novel features disclosed herein.