SYSTEM AND METHODS FOR DYNAMICALLY ALLOCATING VOLTAGE IN A COMPRESSOR MOTOR

Description

FIELD

The field of the disclosure generally relates to heating, ventilation, and air conditioning (HVAC) systems, and in particular, an HVAC control system for biasing voltage between windings of a compressor motor.

BACKGROUND

Some motors may be driven with a variable speed motor controller to adapt motor speed or torque output to a load level. For example, a motor operating a compressor in a heating, ventilation, and air conditioning (HVAC) system may experience high load conditions during peak temperatures and low load conditions during milder temperatures. Some HVAC systems may experience difficulty maintaining performance sufficient to meet certain standards that require HVAC units to operate in a variable speed mode over a specific operating range. The compressor motor of HVAC systems may be required to operate at speeds higher than those that are typical during continuous operation for certain periods of time, for example, during an intermediate load interval. Further, for air conditioning systems, some compressor motors may experience slow subcool buildup due to insufficient speed at startup.

BRIEF DESCRIPTION

One aspect of the present disclosure includes a heating, ventilation, and air conditioning (HVAC) control system. The HVAC control system also includes a compressor which may include a motor, the motor having a first winding and a second winding. The HVAC control system also includes motor controller including a microcontroller programmed to: selectively allocate voltage between the first winding and the second winding according to a first operating mode of the HVAC control system; and in response to a command to transition the HVAC control system from the first operating mode to a second operating mode, bias the first winding over the second winding by selectively allocating voltage from the second winding to the first winding.

Another aspect includes an air conditioning control system. The air condition control system also includes a compressor which may include a motor, the motor having a first winding and a second winding. The system also includes a motor controller including a microcontroller programmed to: selectively allocate voltage between the first winding and the second winding according to a first operating mode of the air conditioning control system; and in response to a command to transition the air conditioning control system from the first operating mode to a second operating mode, bias the first winding over the second winding by selectively allocating voltage from the second winding to the first winding.

A further aspect includes a heating control system. Heating control system also includes a compressor which may include a motor, the motor having a first winding and a second winding. The system also includes a microcontroller programmed to: selectively allocate voltage between the first winding and the second winding according to a first operating mode of the heating control system; and in response to a command to transition the heating control system from the first operating mode to a second operating mode, bias the first winding over the second winding by selectively allocating voltage from the second winding to the first winding.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a heating, ventilation, and air conditioning (HVAC) control system;

FIG. 2A is a chart showing oscillations and harmonics of compressor motor currents without biasing voltage between start and main windings;

FIG. 2B is a chart showing oscillations and harmonics of compressor motor currents with voltage biased between the start and main windings;

FIG. 3A is a chart showing an example compressor rotor speed range, including an extended range based on the application of the methods of the present disclosure to the compressor motor;

FIG. 3B is another chart showing an example compressor rotor speed range including an extended range based on the application of the methods of the present disclosure to the compressor motor; and

FIG. 4 is a flowchart of a method for biasing windings of a compressor motor.

DETAILED DESCRIPTION

Heating, ventilation, and air conditioning (HVAC) systems are designed for continuous operation within a certain range of temperatures. Continuous operation involves running a compressor motor at a steady state, for example, running a compressor at 2400 rotations per minute (RPM) at 40 hertz (Hz). The frequency of the motor operation may be based on a voltage rating and a power rating of the motor. Stopping the compressor motor results in a time delay until the next restart, due to a high pressure differential, hence it is preferable to vary the speed of the compressor and maximize system on-time.

Changing industry standards may require HVAC units to operate in a variable speed mode over a specific operating range of temperatures. This operating range may result in higher load on the compressor than the previous threshold temperature required under previous standards. Therefore, compressors (and by extension, compressor motors) may be required to operate in variable speed mode at higher speeds than under previous standards.

Additionally, some existing HVAC systems experience a slow rate of subcool buildup during certain variable speed operation, in particular at start up. Slow subcool buildup may result in objectionable audible noise for extended periods of time.

Both the above issues of higher industry standards and slow subcool buildup are addressed through extension of the compressor speed and frequency operation range to allow for higher operating speed of the compressor during operation. This improvement is achieved by selectively allocating voltage between a first winding and a second winding of the compressor motor. The allocation of voltage is, for example, biased to focus current (and thereby torque production) towards the main winding, and away from the start winding. In one example embodiment, selective voltage allocation is achieved using a motor controller employing a vector modulation technique, such as dynamic Space Vector Pulse Width Modulation (SVPWM) saturation.

Referring now to FIG. 1, an HVAC control system 100 includes a compressor 102 including a compressor motor 106. Compressor 102 compresses a refrigerant to produce a pressure within HVAC control system 100 and a resulting flow of refrigerant. HVAC control system 100 also includes a motor controller 104. Compressor motor 106 is communicatively coupled to motor controller 104, and motor controller 104 controls the flow of current to motor 106.

In the illustrated embodiment, HVAC control system 100 includes an outdoor heat exchanger 110, an indoor heat exchanger 112, and an expansion valve 114. Compressor 102 generates the flow of refrigerant through outdoor heat exchanger 110, indoor heat exchanger 112, and expansion valve 114 to cool an interior space (not specifically shown). Heat from the interior space is carried by refrigerant and transferred to an exterior space (not specifically shown). The interior space and the exterior space combine to define a cooling load for HVAC control system 100 as a function of a temperature set point for the interior space and an ambient temperature of the exterior space. When operating as a heat pump, HVAC control system 100 operates in reverse, carrying heat from the exterior space into the interior space. Accordingly, reference may be made herein to HVAC control system cooling or heating an interior space, and such descriptions should be considered non-limiting.

During operation, as cool low-pressure refrigerant moves through indoor heat exchanger 112, a blower generates an interior airflow through indoor heat exchanger 112. The interior airflow carries warm air from the interior space through indoor heat exchanger 112, thereby cooling the interior airflow and heating refrigerant. Low-pressure refrigerant flows from indoor heat exchanger 112 into compressor 102 and is compressed, raising the temperature and pressure of refrigerant before it flows into outdoor heat exchanger 110. HVAC control system 100 includes a fan that generates an exterior airflow through outdoor heat exchanger 110. As hot high-pressure refrigerant moves through outdoor heat exchanger 110, the exterior airflow carries ambient air from the exterior space through outdoor heat exchanger 110, thereby cooling refrigerant and heating the exterior airflow. High-pressure refrigerant flows from outdoor heat exchanger 110 into expansion valve 114, where refrigerant is decompressed and cooled before flowing back into indoor heat exchanger 112.

In the example embodiment, HVAC control system 100 is electrically coupled to a power source 124 and is configured to receive power from power source 124. In some embodiments, motor controller 104 includes an inverter 136 coupled to compressor 102. Inverter 136 provides power to compressor 102 and regulates an output voltage and frequency to control the speed at which compressor 102 operates, thereby affecting the overall cooling capacity of the associated HVAC system. At lower speeds, the associated HVAC system operates at a lower cooling capacity. At higher speeds, the associated HVAC system operates at a higher cooling capacity. When operating compressor 102 at AC line voltage (for example, directly from power source 124), inverter 136 is bypassed, thereby eliminating the operating losses introduced by inverter 136.

Compressor motor 106 includes a stator and a rotor (not shown) configured to rotate in response to current applied to windings 120, 122 of the stator. In certain embodiments, the rotor is coupled to and configured to turn, for example, compressor 102. In some embodiments, compressor motor 106 is an induction motor, such as a permanent split capacitor (PSC) motor that includes a first winding 120 and a second winding 122. Current may be supplied to first winding 120 and second winding 122 by motor controller 104, using inverter 136, and/or directly from power source 124. The current signal provided to second winding 122 may have a phase offset from that provided to first winding 120, for example, by 90 degrees, which ensures the rotor rotates in a particular, desired direction upon a startup of compressor motor 106. In some embodiments, first winding 120 may be a main winding, and second winding 122 may be a start winding.

Motor controller 104 further includes a microcontroller 138, the microcontroller 138 including a memory storing computer executable instructions and a processor coupled to the memory. The processor 132, upon execution of the computer executable instructions, is programmed to perform one or more of the functions described herein. Microcontroller 138 may, for example, include a processor 132 and a memory device 134. In some embodiments, processor 132 is implemented in one or more processing devices, such as a microprocessor, a programmable gate array, a reduced instruction set circuit (RISC), an application specific integrated circuit (ASIC), etc. Accordingly, in this example embodiment, processor 132 is constructed of software and/or firmware embedded in one or more processing devices. In this manner, processor 132 is programmable, such that instructions, intervals, thresholds, and/or ranges, etc. may be programmed for a particular motor 106 and/or an operator of motor 106. Processor 132 may be wholly or partially provided by discrete components, external to one or more processing devices.

Processor 132 is configured to communicate with memory device 134 and inverter 136. Processor 132 provides control signals to inverter 136, and inverter 136, in response, supplies current to windings of motor 106. Accordingly, processor 132 commands a motor output, i.e., a speed or torque output, at which motor 106 operates. In some embodiments, processor 132 is configured to communicate with a user device, for example, through a wired or wireless communication channel, such as a serial interface or a Wi-Fi or Bluetooth connection. In such embodiments, users may view status data and control motor 106 via, for example, a mobile or web application. Similarly, processor 132 may be configured to communicate with a system controller or other remote device through a wired or wireless communication channel. Such communication may include transmission of a system control signal from, e.g., the system controller, to processor 132, including a commanded motor output, such as a commanded speed or a commanded torque. Alternatively, the system control signal may include an operating mode (described below), from which processor 132 can determine an appropriate commanded motor output, which may be stored in memory device 134 as a discrete value, as a table of values, or as algorithm or formula, each of which representing an operating profile for motor 106.

In particular, motor controller 104 selectively allocates voltage between first winding 120 and second winding 122 of compressor motor 106. In the context of the present disclosure, a winding is “biased” by allocating more voltage, resulting in more current to the selected winding compared to the other winding. In some embodiments, a winding is biased by favoring the winding, specifically by applying a vector modulation technique, such as dynamic SVPWM saturation, which includes dynamic saturation of the vector modulation pattern. Using SVPWM saturation techniques, motor controller 104 may determine a load point of the system and selectively allocates voltage depending on the load point and an angle of the applied voltage. Load point includes a desired motor operating point. Motor controller 104 selectively allocates voltage by swapping voltage from one winding to another winding (e.g., from second winding 122 to first winding 120). The biasing allows the compressor 102 to run at variable speeds at higher rotational speeds without necessitating a cumbersome transition between power inputs, accelerating the rate of subcool buildup during cooling. SVPWM saturation ensures one winding gets the full voltage needed, while the remaining voltage is allocated to the remaining winding. Use of SVPWM to bias the windings reduces harmonics and results in more efficient usage of available resources, such as the input voltage.

Commanding too much voltage may result in clipping of the duty cycles. By biasing the windings selectively, in accordance with the present disclosure, voltage is clipped in a uniform fashion to bias one winding and avoid inconsistent clipping that compromises performance. For example, motor controller 104 may be configured to bias first winding 120 during an intermediate load period, to allow compressor motor 106 to achieve higher rotations per minute (RPM) and frequency. Therefore, in some embodiments, motor controller 104 reduces voltage to second winding 122 and allocates voltage to first winding 120. The selective allocation may be dynamic (e.g., responsive to particular conditions, as described further herein), and may vary each compressor cycle depending on the load point and applied voltage, such that the allocated voltage does not exceeds a threshold voltage that would result in clipping of the main winding. Clipping is avoided, which results in increased stability and consistency by reducing harmonics and oscillations within currents of compressor motor 106.

In some embodiments, motor controller 104 allocates voltage between first winding 120 and second winding 122 of compressor motor 106 based on one or more operating modes of compressor 102. Operating modes include, for example, transient operation, steady state operation, startup operation, heating operation, cooling operation, variable speed operation, or any combination thereof. Compressor 102 may run in more than one operating mode at once—for example, steady state heating or variable speed cooling. Variable speed operation includes an operation of any varying compressor speeds and/or frequencies. Steady state operation occurs when the system has passed any initial transient behavior and reaches a stable pattern. Steady state operation may include operating the compressor 102 at a non-variable or variable speed and frequency (e.g., powering compressor 102 using AC line voltage). Startup operation is the operating mode of compressor 102 for a relatively short period of time after compressor 102 is started. Transient operation includes operation of compressor 102 for a limited amount of time, such as until one or more threshold values is reached, like time values or values associated with received sensor data. Operating modes may include operation of compressor 102 at speeds and frequencies between, for example, 0 RPM and 0 Hz to 3000 RPM and 50 Hz. In some embodiments, motor controller 104 may perform biasing based on a commanded speed and frequency or a load point. For example, motor controller 104 may bias the main winding over the start winding when the compressor is in a heating operating mode with a commanded speed at or above 2400 RPM at 40 Hz, to operate the motor at or above 2400 RPM at 40 Hz. Motor controller 104 may perform biasing when a commanded speed or load point exceeds an achievable speed, where the achievable speed is calculated based on optimal biasing between the first winding 120 and the second winding 122. Optimal biasing occurs when low harmonic content is achievable on both windings, such as when both windings can be fed with the required voltage for torque production. Other ranges and commanded speeds during which motor controller 104 performs biasing are contemplated, including commanded speeds below 2400 RPM at 40 Hz. The biasing employed by motor controller 104, as described herein, facilitates an expanded range of compressor operation, including higher achieved speeds. For instance, operation of a compressor that would otherwise be limited to lower compressor speeds may achieve higher compressor speeds—for example, a system normally limited to 2400 RPM and 40 Hz due to power constraints may reach compressor speeds of 3000 RPM and 50 Hz through biasing, though other ranges of extended operation are contemplated.

Each operating mode may be associated with a discrete bias proportion and bias time. For example, when HVAC control system 100 is in a variable-speed cooling operating mode, motor controller 104 selectively allocates the voltage to bias the first winding 120 over the second winding 122 transiently (for a limited period of time), as extended operation of biasing may not be possible due to high ambient temperature. Additionally, when HVAC control system 100 is in a steady-state heating operating mode, motor controller 104 selectively allocates voltage to bias the first winding 120 over the second winding 122 while HVAC control system 100 remains in the steady-state operation in the heating mode, as the lower ambient temperatures associated with heating permit continuous biasing.

In some embodiments, motor controller 104 may selectively allocate voltage according to a load interval of HVAC control system 100. For example, the load interval may include a full load interval, an intermediate load interval, a minimum load interval, or a transition period between load intervals. A load interval may be associated with a unique voltage allocation, in which motor controller 104 biases windings 120, 122 according to an initial load interval selected when the compressor begins a cycle of operation. In some embodiments, motor controller 104 may be configured to apply no bias between windings 120, 122 in response to the initial load interval, and may apply a selective bias only upon transition between load intervals. Motor controller 104 may selectively allocate voltage by employing dynamic SVPWM saturation, under which the magnitude, time, pattern, or other attributes of the voltage allocation are determined according to the load interval. Selective allocation may be performed for a limited amount of time—for example, until the compressor 102 switches to a subsequent load interval, or until some threshold value is reached, such as a value received from sensors 130, described further herein.

In some embodiments, load interval may align with Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Standard 210/240-2024, further defined below, in terms of outdoor dry-bulb temperatures. However, it should be readily understood that different standards and temperature ranges may be applied.

For cooling systems, in terms of outdoor dry-bulb temperatures, full load interval refers to a temperature of 95.0° F. (35° C.). The first transition period refers to the interval between the full load interval and the intermediate load interval temperatures, which is between 95° F. (35° C.). at the high end and between 79° F. (26.11° C.) and 85° F. (29.44° C.) at the low end. Intermediate load interval includes temperatures between 79° F. (26.11° C.) and 85° F. (29.44° C.). The second transition period includes temperatures between 67° F. (19.44° C.) and 79° F. (26.11° C.). The minimum load interval includes temperatures at or below 67° F. (19.44° C.).

For heating systems, in terms of entering outdoor dry-bulb temperatures, full load interval refers to a temperature of 17.0° F. (−8.33° C.). The first transition period refers to the interval between the full load interval and the intermediate load interval temperatures, which is between 17° F. (−8.33° C.) at the low end and between 33° F. (0.55° C.) and 39° F. (3.89° C.) at the high end. The intermediate load interval includes temperatures between 33° F. (0.55° C.) and 39° F. (3.89° C.). The second transition period includes temperatures between 39° F. (3.89° C.) and 47° F. (8.33° C.). The minimum load interval includes temperatures at or above 47° F. (8.33° C.).

In some embodiments, HVAC control system 100 may further include one or more sensors 130. Sensors 130 may be communicatively coupled to motor controller 104 (e.g. to the processor thereof) and may be configured to detect one or more parameters of the system or environmental parameters. Sensors 130 may be positioned on the motor controller 104, on compressor 102 or compressor motor 106, on individual components of HVAC control system 100 to measure component or system temperatures of HVAC control system 100, in the environment that compressor 102 is servicing (e.g., a building being cooled by HVAC control system 100), or in any combination of these positions. Sensors 130 may include a temperature sensor configured to detect an ambient temperature of one or more HVAC system components or the environment, a pressure sensor configured to detect a system pressure of one or more HVAC system components, or a time sensor configured to detect an amount of time since the compressor 102 or another component—for example, compressor 102—was last in an active operating mode.

Motor controller 104 may selectively allocate voltage and thus bias windings 120, 122 based on one or more parameters obtained as sensor output from sensor(s) 130, including the sensed value(s) as sensed by sensor(s) 130. Motor controller 104 may bias first winding 120 over second winding 122, based on at least one of the following: the operating temperature of one or more electronics of the HVAC system or system components, an ambient temperature of the environment, a system pressure of the HVAC system, a component pressure of a component of the HVAC system, the amount of time since the compressor 102 or another component was last in an active operating mode. Motor controller 104 may include a clock, timer, or other time-sensing device configured to keep track of various time-based parameters, intervals, and time frames upon which biasing may be based, for example, the amount of time since the compressor or another component was last in an active operating mode, the elapsed time since biasing began, the time since biasing stopped, or any other relevant timing data which may be used as a parameter for determining biasing initiation, ceasing or curtailing biasing, and/or determining biasing magnitude.

For example, when sensors 130 detect a high ambient temperature in a cooling system that results in a higher demanded load, motor controller 104 may bias the first winding 120 over the second winding 122. Motor controller 104 may identify and select the amount of bias (e.g., the amount of voltage restricted from second winding 122 and preferentially supplied to first winding 120) based on the received sensor output. In some embodiments, motor controller 104 is configured to selectively bias windings 120, 122 during intermediate loads under certain conditions. For example, motor controller 104 may bias first winding 120 over second winding 122 when HVAC control system 100 is transitioning into a cooling mode and the ambient temperature is between 79° F. (26.11° C.) and 85° F. (29.44° C.). As another example, motor controller 104 may bias first winding 120 over second winding 122 when HVAC control system 100 is transitioning to or operating in a heating mode and the ambient temperature is between 33° F. (0.55° C.) and 39° F. (3.89° C.).

In some embodiments, motor controller 104 may start, increase, curtail, or stop biasing based on the detected operating temperature of one or more system components or the ambient temperature. For example, if motor controller 104 detects that a temperature of one or more system components or one or more electronics exceeds a first threshold value, motor controller 104 may stop or curtail the biasing of the windings. When the system component temperature drops below a second threshold value, motor controller 104 may resume, increase, or begin biasing of the windings. The above may also be applied based on other threshold values, sensor values, or parameters instead of system component temperature, for example, system pressure, system temperature, component pressure, or time.

In some embodiments, motor controller 104 may selectively allocate voltage and bias windings 120, 122 in response to a command to transition HVAC control system 100 from an first operating mode to a second operating mode. For example, motor controller 104 employ voltage biasing when HVAC control system 100 transitions from a startup operating mode to a variable speed operating mode. Motor controller 104 may be configured to maintain the biasing throughout the duration of HVAC control system 100 operating in the second operating mode, may continue until another command to transition to a different operating mode is received, or may continue until some threshold value is reached, such as a detected sensor value for temperature, pressure, time, or other parameter has reached a threshold value, or some other criteria. For example, in response to a command to transition between operating modes, motor controller 104 may selectively allocate voltage from second winding 122 to first winding 120.

In some embodiments, motor controller 104 may allocate and bias voltage in response to a command to transition HVAC control system 100 from an initial load interval to a subsequent load interval. For example, motor controller 104 may selectively allocate voltage and bias the windings when HVAC control system 100 transitions from a full load interval to an intermediate load interval. Motor controller 104 may continue biasing for the duration of HVAC control system 100 operating at the intermediate load interval, may bias only during a transition period, may bias until another command to transition to a different load interval is received, or may continue biasing until some threshold value is reached, such as a detected sensor value for temperature, pressure, time, or other parameter has reached a threshold value. For example, in response to a command to transition between load intervals, motor controller 104 may selectively allocate voltage from second winding 122 to first winding 120.

In some embodiments, HVAC control system 100 is an air conditioning control system for controlling the compressor 102 of an air conditioning system. In other embodiments, HVAC control system 100 is a heating control system for controlling the compressor 102 of a heating system. In yet another embodiment, HVAC control system 100 is both an air conditioning and heating control system, selectively usable for either heating or cooling.

FIGS. 2A and 2B show graphs 202, 204, respectively, which depict example oscillations and harmonics of a start winding as curve 208, (e.g., second winding 122), a main winding as curve 206, (e.g., first winding 120, both shown in FIG. 1), and common current as curve 210 during operation of an example compressor motor (e.g., motor 106, also shown in FIG. 1). Specifically, FIG. 2A depicts the main winding (see curve 206) experiencing notable oscillations and harmonics when no biasing is applied between the main winding and the start winding, demonstrating reduced performance of the compressor. In contrast, FIG. 2B shows the same example system with biasing applied in accordance with the present disclosure. With biasing, the sine curve of the main winding (see curve 206) is much smoother, showing reduced harmonics and oscillations, resulting in improved performance of the compressor.

FIGS. 3A and 3B show graphs 302, 304, respectively, depicting operational ranges of an example compressor system (which may include HVAC control system 100). Conventionally, for example, a compressor may be capable of operation of up to about 2400 RPM at 40 Hz, on drive power. Graphs 302, 304 illustrate an extended operational range of between 2400-3000 RPM by incorporating the biasing of the main winding, as described herein, before the transition to line power. Specifically, graph 302 in FIG. 3A shows the conventional and extended operational ranges in terms of commanded speed, rotor speed, and input power. Graph 304 in FIG. 3B shows the conventional and extended operational range in terms of commanded speed and current (amp root mean square).

FIG. 4 shows a flowchart of a method 400 of controlling an HVAC system. Method 400 may be implemented using one or more components of HVAC control system 100, such as motor controller 104. Method 400 includes selectively allocating 402 voltage between a first winding and second winding of a compressor motor according to an first operating mode of HVAC control system. Method further includes, in response to a command to transition the HVAC control system from the first operating mode to a second operating mode, biasing 404 the first winding over the second winding by selectively allocating voltage from the second winding to the first winding. Method may further include receiving sensor data from one or more sensors. Method may further include biasing 404 the first winding over the second winding based on the received sensor data.

Biasing may include biasing based on an first operating mode of the HVAC system. Biasing may include biasing based on the operating mode of the compressor motor. Biasing may include determining the magnitude or timing of biasing based on the compressor speed and frequency. Biasing 404 may be performed in response to receiving a command to transition the HVAC control system from the first operating mode to the second operating mode, or may be performed in response to receiving data from one or more sensors.

Receiving data from one or more sensors may include receiving data from sensors communicatively coupled to an HVAC system and configured to detect one or more system or environmental parameters. Example sensors may be sensors 130 as described herein. Biasing 404 based on sensor data may further include determining the magnitude or timing of the biasing based on the sensor data after receiving sensor data from one or more sensors. The received data may include at least one of the following: the temperature of one or more electronics of the HVAC system or system components, an ambient temperature of the environment, a system pressure of the HVAC system, a component pressure of a component of the HVAC system, the amount of time since the compressor or another component was last in an active operating mode. In some embodiments, biasing based on the sensor data includes biasing the first winding over the second winding based on the sensed value received from the sensor of at least one of the following: the temperature of one or more electronics of the HVAC system or system components, an ambient temperature of the environment, a system pressure of the HVAC system, a component pressure of a component of the HVAC system, the amount of time since the compressor or another component was last in an active operating mode, or an ambient pressure of the environment.

Method 400 may further include selectively allocating voltage based on an operating mode. Operating modes include, for example, transient operation, steady state operation, startup operation, heating operation, cooling operation, variable speed operation. A compressor may run in more than one operating mode at once - for example, steady state heating or variable speed cooling. Variable speed operation includes any varying compressor speeds and frequencies. Steady state operation may include operating the compressor at either a variable or non-variable speed and frequency, and occurs when the system has passed any initial transient behavior and reaches a stable pattern. Startup operation encompasses compressor operation for a short after the compressor is started. Transient operation includes operating the compressor for a limited period of time. Operating states may include operation of the compressor at speeds and frequencies between, for example, 0 RPM and 0 Hz to 3000 RPM and 50 Hz. In some embodiments, method 400 may including biasing based on a commanded speed and frequency. For example, method 400 may include biasing the first winding over the second winding when the compressor is in a heating operating mode with a commanded speed at or above 2400 RPM at 40 Hz, to operate the motor at or above 2400 RPM at 40 Hz. Other ranges and commanded speeds during which biasing is performed are contemplated, including commanded speeds below 2400 RPM at 40 Hz. The biasing permits a system that would otherwise be limited to lower compressor speeds to achieve higher compressor speeds, for example, a system normally limited to 2400 RPM and 40 Hz due to power constraints may reach compressor speeds of 3000 RPM and 50 Hz through biasing to reach higher commanded speeds, though other ranges of extended operation are contemplated.

Method 400 may include determining the magnitude and timing of biasing 404 based on an operating state of the HVAC control system. For example, when HVAC control system is in cooling mode at a variable speed operating mode, method includes selectively allocating the voltage to bias the first winding over the second winding transiently (for a limited period of time), as extended operation of biasing may not be possible due to high ambient temperature in cooling mode. However, when HVAC control system is in heating mode in steady state operation, method 400 includes selectively allocates voltage to bias the first winding over the second winding while HVAC control system remains in steady state operation in heating mode, as the lower ambient temperatures associated with heating permit continuous biasing.

An example technical effect of the methods, systems, and apparatus described herein includes at least one of: (a) increasing operating range of an HVAC compressor by optimizing incoming voltage between motor windings of a compressor, (b) reducing time to achieve appropriate subcool buildup in air conditioning systems by improving compressor startup performance through optimized voltage allocation to compressor motor windings, (c) improving steady state heating performance and operating range for heating systems by optimizing voltage allocation to compressor motor windings.

Some embodiments involve the use of one or more electronic or computing devices (e.g., for controlling operation of a drive circuit and/or individual components thereof). Such devices typically include a processor, processing device, or controller, such as a general purpose central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, a reduced instruction set computer (RISC) processor, an application specific integrated circuit (ASIC), a programmable logic circuit (PLC), a field programmable gate array (FPGA), a digital signal processing (DSP) device, and/or any other circuit or processing device capable of executing the functions described herein. The methods described herein may be encoded as executable instructions embodied in a computer readable medium, including, without limitation, a storage device and/or a memory device. Such instructions, when executed by a processing device, cause the processing device to perform at least a portion of the methods described herein. The above examples are exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the terms: processor, processing device, and controller.

In the embodiments described herein, memory may include, but is not limited to, a computer-readable medium, such as a random-access memory (RAM), and a computer-readable non-volatile medium, such as flash memory. Alternatively, a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), and/or a digital versatile disc (DVD) may also be used. Also, in the embodiments described herein, additional input channels may be, but are not limited to, computer peripherals associated with an operator interface such as a mouse and a keyboard. Alternatively, other computer peripherals may also be used that may include, for example, but not be limited to, a scanner. Furthermore, in the exemplary embodiment, additional output channels may include, but not be limited to, an operator interface monitor.

As used herein, the terms “software” and “firmware” are interchangeable and include any computer program stored in memory for execution by a processor, including RAM memory, ROM memory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM) memory. The above memory types are examples only and are thus not limiting as to the types of memory usable for storage of a computer program.

As used herein, an element or step recited in the singular and preceded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “example implementation” or “one implementation” of the present disclosure are not intended to be interpreted as excluding the existence of additional implementations that also incorporate the recited features.

The systems and methods described herein are not limited to the specific embodiments described herein, but rather, components of the systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein.

This written description uses examples to provide details on the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.