Patent Description:
The background description provided here is for the purpose of generally presenting the context of the disclosure.

A residential or light commercial HVAC (heating, ventilation, and/or air conditioning) system controls temperature and humidity of a building. Upper and lower temperature limits may be specified by an occupant or owner of the building, such as an employee working in the building or a homeowner.

A compressor of the HVAC system can be a two-stage or variable capacity compressor. While variable capacity compressors may provide high seasonal energy efficiency ratio (SEER) and energy efficiency ratio (EER) ratings, variable capacity compressors may be originally more costly for an owner. Two-stage compressors have a lower cost but are limited to two run capacities, which may decrease overall efficiency as well as SEER and EER ratings. Document <CIT> discloses a system for controlling a capacity of a compressor that may be used in an HVAC system, whereby the motor of the compressor is a permanent split capacitor (PSC) motor. A controller of the system is adapted to control the compressor capacity by adapting the rotational speed of the compressor motor. The motor is driven in two modes. In the first mode (drive mode), the motor is driven by an inverter by using pulse width modulation (PWM) to adapt the motor/ compressor speed according to the required compressor capacity. This mode is used for operating of the compressor at less than full load. In the second mode (full load mode), the motor windings are connected directly to the AC power supply line, thus bypassing the inverter, consequently eliminating power losses and EM interferences generated by the inverter.

In a feature, a system for controlling a capacity of a compressor is described. The system includes a motor of the compressor including a main winding connected at a connection point to an auxiliary winding and a drive configured to control a speed of the motor. The system includes a first switch configured to selectively connect the main winding to either (a) a first line voltage or (b) a first output of the drive, a second switch configured to selectively connect the connection point to either (a) a second line voltage or (b) a second output of the drive, and a third switch configured to selectively connect the auxiliary winding to either (a) a capacitor or (b) a third output of the drive. The system includes a solenoid valve configured to selectively either operate in (a) a first capacity or (b) a second capacity.

The system includes a control module configured to control the drive, the first switch, the second switch, and the third switch by, in response to receiving a demand in a first state: switching the first switch to connect the main winding to the first output of the drive, switching the second switch to connect the connection point to the second output of the drive, switching the third switch to connect the auxiliary winding to the third output of the drive, and switching the solenoid valve to the first capacity. The control module controls by, in response to receiving the demand in a second state: switching the first switch to connect the main winding to the first line voltage, switching the second switch to connect the connection point to the second line voltage, switching the third switch to connect the auxiliary winding to the capacitor, and switching the solenoid valve to the first capacity.

The control module controls by, in response to receiving the demand in a third state: switching the first switch to connect the main winding to the first line voltage, switching the second switch to connect the connection point to the second line voltage, switching the third switch to connect the auxiliary winding to the capacitor, and switching the solenoid valve to the second capacity.

In further features, the control module, the first switch, the second switch, and the third switch are integrated in a control board. In further features, when the solenoid valve is in the first capacity, the solenoid valve is configured to allow a flow of pressurized gas and, when the solenoid valve is in the second capacity, the solenoid valve is configured to selectively restrict the flow of the pressurized gas. In further features, the compressor is a two-stage compressor.

In further features, the main winding includes a first side and a second side, the auxiliary winding includes a first side and a second side, and the connection point connects the second side of the main winding and the first side of the auxiliary winding.

In further features, the demand is set to the second state in response to a first runtime of the first state exceeding a first runtime threshold and the third state in response to a second runtime of the second state exceeding a second runtime threshold.

In further features, the system includes a thermostat and an outside air temperature sensor. In further features, the thermostat is configured to set the demand based on at least one of (i) an inside air temperature and (ii) an outside air temperature and transmit the demand to the control module. The inside air temperature is determined by the thermostat, and the outside air temperature is received from the outside air temperature sensor.

In further features, the demand is set to, during cooling, the first state when the inside air temperature is above a first threshold and below a second threshold, the second state when the inside air temperature is above the second threshold and below a third threshold, and the third state when the inside air temperature is above the third threshold. In further features, the demand is set to, during heating, the first state when the inside air temperature is below the first threshold and above a fourth threshold, the second state when the inside air temperature is below the fourth threshold and above a fifth threshold, and the third state when the inside air temperature is below the fifth threshold.

In further features, the demand is set to, during cooling, the first state when the outside air temperature is above a first threshold and below a second threshold, the second state when the outside air temperature is above the second threshold and below a third threshold, and the third state when the outside air temperature is above the third threshold. In further features, the demand is set to, during heating, the first state when the outside air temperature is below the first threshold and above a fourth threshold, the second state when the outside air temperature is below the fourth threshold and above a fifth threshold, and the third state when the outside air temperature is below the fifth threshold.

In further features, the system includes a relative humidity sensor. In further features, the thermostat is configured to receive a relative humidity from the relative humidity sensor, set the demand further based on the relative humidity, and transmit the demand to the control module.

In further features, the first line voltage and the second line voltage are received from an incoming AC power line. In further features, the drive is configured to selectively adjust the speed of the motor using pulse width modulation control. In further features, the capacitor includes a first side and a second side. In further features, the first side of the capacitor is connected to the third switch. In further features, the second side of the capacitor is connected to the first line voltage.

In a further feature, a heating, ventilation, and/or air conditioning (HVAC) system includes the system for controlling the capacity of the compressor.

In a further feature, a method for controlling a capacity of a compressor is described. The method includes, in response to a demand indicating a first state: switching, via a control module, a first switch to connect a main winding to a first output of a drive, switching, via the control module, a second switch to connect a connection point to a second output of the drive, switching, via the control module, a third switch to connect an auxiliary winding to third output of the drive, and switching, via the control module, a solenoid valve to a first capacity. In further features, a motor of the compressor includes the main winding connected at the connection point to the auxiliary winding. The drive is configured to control a speed of the motor.

The method includes, in response to the demand indicating a second state: switching, via the control module, the first switch to connect the main winding to a first line voltage, switching, via the control module, the second switch to connect the connection point to a second line voltage, switching, via the control module, the third switch to connect the auxiliary winding to a capacitor, and maintaining, via the control module, the solenoid valve at the first capacity. The method includes, in response to the demand indicating a third state: switching, via the control module, the first switch to connect the main winding to the first line voltage, switching, via the control module, the second switch to connect the connection point to the second line voltage, switching, via the control module, the third switch to connect the auxiliary winding to the capacitor, and switching, via the control module, the solenoid valve to a second capacity.

In further features, the method includes setting, via a thermostat, the demand based on an inside air temperature and an outside air temperature and transmitting, via the thermostat, the demand to the control module. The thermostat determines the inside air temperature, and the thermostat receives the outside air temperature from an outside air temperature sensor.

Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.

According to the present disclosure, a control module is configured to control a two-stage compressor of a heating, ventilation, and air conditioning (HVAC) system at three capacities or stages instead of only two. The control module controls a set of switches or relays to connect a motor of the compressor to line voltage when operating in a high capacity mode and a mid capacity mode. To operate at different capacities, differentiating the high capacity mode or high stage from the mid capacity mode or mid stage, the control module operates a solenoid valve to turn on during high stage and turn off during mid stage. The solenoid valve is engaged and disengaged (on/off) for mechanical modulation of the two-stage compressor. To operate in a low capacity mode or low stage, the control module connects the motor of the compressor to a drive via the set of switches. The drive is configured to operate the motor of the compressor implementing motor speed control methods. The drive receives power from the same line voltage in order to operate the motor using motor speed control techniques, such as via pulse width modulation (PWM).

To realize high and mid stage operation of the two-stage compressor, the control module connects the motor of the compressor to alternating current (AC) line voltage and controls the solenoid valve of the compressor. For example, to operate in mid stage at partial system load (e.g., approximately <NUM>%) the solenoid valve is disengaged or off (at a first capacity) to allow the flow of pressurized gas return to suction. To operate in high stage at full system load (e.g., <NUM>%) the solenoid valve is engaged or on (at a second capacity) to restrict the flow of pressurized gas back to suction. As indicated, the two stages provide different capacities, the first capacity and the second capacity, at which to run the compressor, for example, based on an indoor setpoint, inside air temperature, an outside air temperature (OAT), a relative humidity, a region or location, a time of day or year, etc. For example, high stage operation, resulting in more cooling, may be more efficient than mid stage during peak heat and humidity, such as during late afternoon in the summer, or in particular regions of the world.

To realize low stage operation using the two-stage compressor, the control module disconnects the AC line voltage from the motor and instead connects the motor to the drive or drive circuit that is configured to operate variable speed control of the motor. The drive may be permanently connected to the AC line voltage for operation. The drive may include a filter, a power factor correction circuit, and an inverter. As is true with mid and high stages, operating at low stage or a lower capacity may be more efficient during a lower OAT and lower humidity time period.

The control module receives a demand signal from a thermostat including demand signals (Y1, Y2, and a solenoid signal S) that indicate which of the three stages of operation to implement the compressor or HVAC system. Additionally or alternatively, the demand signals may exclude the solenoid signal S and instead indicate operating one of the three stages using only two demand signals: Y1 and Y2. The thermostat may be located indoors and includes a temperature sensor. The thermostat may also include a relative humidity sensor. In various implementations, a communication message may be determined and generated by a separate control module included in the HVAC system and transmitted to the control module indicating a demanded stage of operation. For example, the thermostat may determine when to start the compressor based on a difference between a setpoint temperature of the thermostat and an indoor temperature. The thermostat or other control module determines the stage to operate the compressor (or overall HVAC system) based on the various parameters (e.g., inside air temperature, OAT, humidity, etc.). In various implementations, a lookup table may relate indoor air temperatures, OATs, relative humidities, etc. to amounts of time to operate the compressor at a particular stage or a set of stages to reach the setpoint temperature. Additionally or alternatively, the compressor may be controlled to operate at the determined stage until the setpoint temperature is reached, as indicated by a signal from the thermostat instructing the compressor to turn off.

For example, each stage may have an associated threshold at which the stage is engaged. In other words, a stage difference value between the OAT, as sensed by the OAT sensor, and the setpoint temperature may be beyond a high value, warranting the compressor to engage in high stage operation. In various implementations, the stage difference value being beyond the high value as well as the relative humidity being beyond threshold values may prompt the thermostat to generate and transmit a high stage demand to the control module.

If the stage difference value is less than the high value but higher than a mid value, mid stage is activated. If the stage difference value falls between the mid value and a low value, low stage is activated. As mentioned, the humidity in combination with the stage difference value may be used to determine which of the three stages of the compressor to operate. Additional information describing the determination of different run capacities of a compressor are described in <CIT>.

The control module controls a motor of a two-stage compressor in a manner that allows the two-stage compressor to operate in three separate stages, two stages operate with the motor directly connected to AC line voltage and a third stage operates with the motor connected to a drive implementing, for example, PWM control. Each stage of operation implements a different capacity of the compressor, providing energy efficiency benefits that not only comply with efficiency regulations but also result in a reduced operating cost. Implementing the two-stage compressor is more cost efficient than a variable capacity compressor but provides higher efficiency and efficacy than standard (only two-stage) operation of a two-stage compressor. The control module operates the two-stage compressor in a manner that provides three separate operating stages, providing a balance between higher efficiency and lower cost.

<FIG> is a block diagram of an example heating, ventilation, and air conditioning (HVAC) system. In this particular example, a forced air system with a gas furnace is shown. Return air is pulled from a building through a filter <NUM> by a circulator blower <NUM>. The circulator blower <NUM>, also referred to as a fan, is controlled by a control module <NUM>. The control module <NUM> receives signals from a thermostat <NUM>. For example, the thermostat <NUM> may include one or more setpoint temperatures specified by the user. As mentioned previously, the thermostat <NUM> may include a temperature sensor and a humidity sensor.

The thermostat <NUM> may direct that the circulator blower <NUM> be turned on at all times or only when a heat request or cool request is present (automatic fan mode). In various implementations, the circulator blower <NUM> can operate at one or more discrete speeds or at any speed within a predetermined range. For example, the control module <NUM> may switch one or more switching relays (not shown) to control the circulator blower <NUM> and/or to select a speed of the circulator blower <NUM>.

The thermostat <NUM> provides the heat and/or cool requests to the control module <NUM>. When a heat request is made, the control module <NUM> causes a burner <NUM> to ignite. Heat from combustion is introduced to the return air provided by the circulator blower <NUM> in a heat exchanger <NUM>. The heated air is supplied to the building and is referred to as supply air.

The burner <NUM> may include a pilot light, which is a small constant flame for igniting the primary flame in the burner <NUM>. Alternatively, an intermittent pilot may be used in which a small flame is first lit prior to igniting the primary flame in the burner <NUM>. A sparker may be used for an intermittent pilot implementation or for direct burner ignition. Another ignition option includes a hot surface igniter, which heats a surface to a high enough temperature that, when gas is introduced, the heated surface initiates combustion of the gas. Fuel for combustion, such as natural gas, may be provided by a gas valve <NUM>.

The products of combustion are exhausted outside of the building, and an inducer blower <NUM> may be turned on prior to ignition of the burner <NUM>. In a high efficiency furnace, the products of combustion may not be hot enough to have sufficient buoyancy to exhaust via conduction. Therefore, the inducer blower <NUM> creates a draft to exhaust the products of combustion. The inducer blower <NUM> may remain running while the burner <NUM> is operating. In addition, the inducer blower <NUM> may continue running for a set period of time after the burner <NUM> turns off.

A single enclosure, which will be referred to as an air handler unit <NUM>, may include the filter <NUM>, the circulator blower <NUM>, the control module <NUM>, the burner <NUM>, the heat exchanger <NUM>, the inducer blower <NUM>, an expansion valve <NUM>, an evaporator <NUM>, and a condensate pan <NUM>. In various implementations, the air handler unit <NUM> includes an electrical heating device (not shown) instead of or in addition to the burner <NUM>. When used in addition to the burner <NUM>, the electrical heating device may provide backup or secondary (extra) heat to the burner <NUM>.

As shown in <FIG>, the HVAC system includes a split air conditioning system. Refrigerant is circulated through a compressor <NUM>, a condenser <NUM>, the expansion valve <NUM>, and the evaporator <NUM>. The evaporator <NUM> is placed in series with the supply air so that when cooling is desired, the evaporator <NUM> removes heat from the supply air, thereby cooling the supply air. During cooling, the evaporator <NUM> is cold (e.g., below the dew point of the air within the building), which causes water vapor to condense. This water vapor is collected in the condensate pan <NUM>, which is drained or is pumped out.

A control module <NUM> receives a cool request from the control module <NUM> and controls the compressor <NUM> accordingly. As is described in more detail in <FIG> and <FIG>, the control module <NUM> controls a motor and a solenoid valve of the compressor <NUM> to operate in one of three stages. The control module <NUM> may also control a condenser fan <NUM>, which increases heat exchange between the condenser <NUM> and outside air. In such a split system, the compressor <NUM>, the condenser <NUM>, the control module <NUM>, and the condenser fan <NUM> are generally located outside of the building, often in a single condensing unit <NUM>. As discussed previously, the compressor <NUM> is a two-stage mechanically modulated scroll compressor. In various implementations, each of the three stages includes corresponding operating stage speeds of the condenser fan <NUM>.

The electrical lines provided to the condensing unit <NUM> may include a <NUM> volt mains power line and a <NUM> volt switched control line. The <NUM> volt control line may correspond to the cool request shown in <FIG>. The <NUM> volt control line controls operation of the control module <NUM> and solenoid valve (shown in <FIG> and <FIG>). When the control line indicates that the compressor <NUM> should be on, the control module <NUM> operates a set of switches to connect the <NUM> volt power supply to a motor of the compressor <NUM> or to connect the motor of the compressor <NUM> to a drive to operate the compressor <NUM>. In addition, the control module <NUM> may connect the <NUM> volt power supply to the condenser fan <NUM>.

In various implementations, such as when the condensing unit <NUM> is located in the ground as part of a geothermal system, the condenser fan <NUM> may be omitted. The <NUM> volt mains power supply arrives in two legs, as is common in the U. , both of the legs connect to the motor of the compressor <NUM>. In various implementations, the control module <NUM> may be configured to selectively control a motor of the condenser fan <NUM> at variable speeds.

When in a heating (heat) mode, the thermostat <NUM> generates a heat request when the temperature measured by the temperature sensor is less than a lower temperature limit. When in a cooling (cool) mode, the thermostat <NUM> generates a cool request when the temperature measured by the temperature sensor is greater than an upper temperature limit. The upper and lower temperature limits may be set to a setpoint temperature + and - a threshold amount (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM> degrees Fahrenheit), respectively. The setpoint temperature may be set to a temperature by default and may be adjusted via receipt of user input. The threshold amount may be set by default and may be adjusted via receipt of user input.

In various implementations, the control module <NUM> or thermostat <NUM>, may receive signals from an OAT sensor <NUM>. To determine a stage (high, mid, or low) at which to operate the compressor <NUM>, as dictated by operation stage of the motor and the solenoid valve, the indoor temperature and setpoint temperature of the thermostat <NUM> may be compared to determine a stage difference value. For example, the stage difference may be set based on or equal to a difference between the indoor temperature and the setpoint temperature. In various implementations, based on where the stage difference value falls within a set of thresholds (a low value, mid value, and high value corresponding to stages), along with the OAT, relative humidity, region/location, and/or time of day/year, the thermostat <NUM> may determine which of the three stages to operate the compressor <NUM>. In various implementations, the control module <NUM> may receive the various parameters to determine the stage of the compressor <NUM> and include a low stage, mid stage, or high stage demand with the cool request.

In various implementations, if the thermostat <NUM> is determining the stage, the thermostat <NUM> may optionally forward (e.g., discrete) demand signals Y1, Y2, and S (indicating solenoid valve position) to the control module <NUM>. The combination of the demand signals Y1, Y2, and S correspond to one of the three stages. Based on the demand signals Y1, Y2, and S, the control module <NUM> controls the operation of the compressor <NUM>. The thermostat <NUM> may be a WiFi thermostat having networking capability.

In various implementations, the air handler unit <NUM> may include a transformer (not shown) connected to an incoming AC power line in order to provide AC power to the control module <NUM> and the thermostat <NUM>. For example, the transformer may be a <NUM>-to-<NUM> transformer and therefore provide either a 12V or 24V AC supply depending on whether the air handler unit <NUM> is operating on nominal <NUM> volt or nominal <NUM> volt power. Additionally or alternatively, the transformer may be a <NUM>-to-<NUM> transformer to provide 24V AC supply if the air handler is operating on nominal <NUM> volt power.

The control module <NUM> controls operation in response to signals from the thermostat <NUM> received over control lines. The control lines may include a call for cool (cool request), a call for heat (heat request), and a call for fan (fan request). The cool and heat requests are sent to the condensing unit <NUM> and include a stage request identifying one of the three stages for compressor operation. The control lines may include a line corresponding to a state of a reversing valve in heat pump systems.

The control lines may further carry calls for secondary heat and/or secondary cooling, which may be activated when the primary heating or primary cooling is insufficient. In dual fuel systems, such as systems operating from either electricity or natural gas, control signals related to the selection of the fuel may be monitored. Further, additional status and error signals may be monitored, such as a defrost status signal, which may be asserted when the compressor is shut off and a defrost heater operates to melt frost from an evaporator.

In various implementations, the OAT sensor <NUM> may be located within an enclosure, shielded from direct sunlight, and/or exposed to an air cavity that is not directly heated by sunlight. Alternatively or additionally, online (including Internet-based via the thermostat <NUM>) weather data based on the geographical location of the building may be used to determine sun load, OAT, relative humidity, particulate, VOCs, carbon dioxide, etc..

<FIG> is a functional block diagram of an example condensing unit <NUM> of an example HVAC system. The condensing unit <NUM> may be configured similarly to the condensing unit <NUM> of <FIG>. Although referred to as the condensing unit <NUM>, the mode of a heat pump determines whether the condenser <NUM> of the condensing unit <NUM> is actually operating as a condenser or as an evaporator. A reversing valve <NUM> is controlled by the control module <NUM> and determines whether the compressor <NUM> discharges compressed refrigerant toward the condenser <NUM> (cooling mode) or away from the condenser <NUM> (heating mode). The control module <NUM> controls the reversing valve <NUM> and the compressor <NUM> based on the control signals. The control module <NUM> may receive power, for example, from a transformer (not shown) of the air handler unit <NUM> or via the incoming AC power line.

The compressor <NUM> includes motor control circuit <NUM>, a motor <NUM>, and a solenoid valve <NUM>. The motor control circuit <NUM> includes elements, such as a set of switches or relays and a drive (shown in <FIG>). The motor <NUM> may operate at, for example, approximately <NUM> hertz (Hz) in low stage and approximately <NUM>-<NUM> in mid and high stage. The control module <NUM> receives control signals from, for example, the thermostat <NUM> or the control module <NUM> of the air handler unit <NUM>. The control signals include demand signals indicating a stage for operation of the compressor <NUM>. As described previously, the control signals may include demand signals Y1, Y2, and S from the thermostat <NUM>. The control module <NUM> controls the elements of the motor control circuit <NUM> according to the control signals. For example, if the control signals indicate that the compressor <NUM> should operate in a low stage, the control module <NUM> controls switches of the motor control circuit <NUM> to connect the motor <NUM> to a drive <NUM>, using the motor speed control to operate the motor <NUM>. While depicted as separate, the control module <NUM>, including the stage control module <NUM> and the drive control module <NUM>, is integrated into a single controller including the motor circuit <NUM> as well as the drive <NUM>.

If the control signals indicate the compressor <NUM> should operate in mid stage or high stage, the control module <NUM> first operates the motor <NUM> in low stage, connecting the motor <NUM> to the drive <NUM> using the set of switches and switches the motor <NUM>, via the set of switches, to connect directly to the incoming AC power or the AC line voltage. In various implementations, the compressor <NUM> may be configured to directly operate in mid stage or high stage. Additionally, if the control signals indicate the compressor <NUM> should operate in mid stage, the control module <NUM> disengages the solenoid valve <NUM> so the compressor <NUM> operates at partial or <NUM>% capacity. The solenoid valve <NUM> is disengaged when the solenoid valve <NUM> is off and de-energized. In an example implementation, when the solenoid valve <NUM> is off, pressurized gas passes through the solenoid valve <NUM> allowing an amount of the pressurized gas to return to suction of the compressor <NUM>; however, any two-stage compressor can implement the present motor control system and method. In various implementations, the control module <NUM> may directly connect the motor <NUM> to the incoming AC power based on the control signals.

If the control signals indicate the compressor <NUM> should operate in high stage, the control module <NUM> engages the solenoid valve <NUM> so the compressor <NUM> operates at approximately full or <NUM>% capacity. The solenoid valve <NUM> is engaged when the solenoid valve <NUM> is on and energized. When the solenoid valve <NUM> is on, the pressurized gas is restricted and the solenoid valve <NUM> prevents the gas from passing, thereby preventing the gas back to suction. As an example, due to the pressurized gas being trapped in high stage, a modulation ring of the compressor <NUM> is moved onto the stationary scroll of the compressor <NUM> to engage the compressor <NUM> into full capacity operation by blocking any bypass ports.

In various implementations, the solenoid valve <NUM> may operate using different or reversed logic. For example, the solenoid valve <NUM> may be designed such that when the solenoid valve <NUM> is on or engaged, the on indicates operating at partial capacity. Therefore, the solenoid valve <NUM> may be on during low stage and mid stage, operating at partial or low capacity.

<FIG> is a functional block diagram of example motor control circuit <NUM> of an example compressor <NUM> of an HVAC system. The control module <NUM> includes a stage control module <NUM> and a drive control module <NUM>. In various implementations, the stage control module <NUM> and the drive control module <NUM> may be incorporated into a signal control module (the control module <NUM>).

The stage control module <NUM> receives control signals or demand signals from the thermostat or control module of the air handler unit. The control signals indicate at which stage to operate the compressor <NUM> and, in turn, how to operate the motor <NUM>. As previously discussed, the control signals may be in discrete form as shown in <FIG>, where demand signals (Y1, Y2, and S) are received from the thermostat indicating how to operate the compressor <NUM>. In various implementations, the thermostat or the control module of the air handler unit may determine the stage at which to run to compressor <NUM> based on the setpoint temperature of the thermostat, the present indoor temperature, the OAT, the relative humidity, the location/region, the time of day/year, or any combination thereof.

The control module of the air handler unit and the control module <NUM> may communicate, for example, using RS485 MODBUS or another suitable type of communication including, but not limited to, controller area network (CAN) bus or analog signaling (e.g., <NUM>-<NUM> V signals). If the control signals are in the form of discrete demand signals Y1 and Y2, the signals may be in the range of <NUM> volt alternating current/direct current (VAC/DC)-<NUM> VAC/DC.

In various implementations, the control module <NUM> also operates the condenser fan <NUM> at varying stages corresponding to the stage of the compressor <NUM>. Similarly, the control module <NUM> of the air handler unit <NUM> may control various elements of the air handler unit <NUM> based on the stage of the compressor <NUM>. The stage control module <NUM> actuates the solenoid valve <NUM> (shown in <FIG>) based on the received control signals. For example, the stage control module <NUM> turns the solenoid valve <NUM> on if the received control signals request high stage operation. Otherwise, the stage control module <NUM> may turn the solenoid valve <NUM> off. More specifically, the stage control module <NUM>, in response to receiving control signals indicating mid stage or high stage operation, will start the motor <NUM> in low stage. If the motor <NUM> is already in low stage and the control signals indicate mid stage or high stage operation the stage control module <NUM> will first instruct the drive control module <NUM> to connect the motor <NUM> directly to the incoming AC power (via the set of switches discussed below). Once connected to the incoming AC power, the solenoid valve <NUM> is turned on.

The drive control module <NUM> receives the control signals via the stage control module <NUM>. In various implementations, the drive control module <NUM> may receive the control signals independently. The drive control module <NUM> controls switching of a set of switches or relays included in the motor control circuit <NUM>. The set of switches includes a first switch <NUM>, a second switch <NUM>, and a third switch <NUM>. The first switch <NUM> selectively connects a first end of a main winding <NUM> of the motor <NUM> to a first line voltage L1 of the incoming AC power or a first output U of the drive <NUM>.

A second end of the main winding <NUM> connects to a first end of an auxiliary winding <NUM> of the motor <NUM> and the second switch <NUM> at a connection point <NUM>. The second switch <NUM> selectively connects the connection point <NUM> to a second line voltage L2 of the incoming AC power or a second output V of the drive <NUM>. The third switch <NUM> selectively connects a second end of the auxiliary winding <NUM> to a start capacitor <NUM> or a third output W of the drive <NUM>. The drive control module <NUM> controls the first switch <NUM>, the second switch <NUM>, and the third switch <NUM> based on the received control signals indicating low stage, mid stage, or high stage operation. The drive <NUM> may be always connected to the incoming AC power lines L1 and L2.

The drive control module <NUM> controls the set of switches based on the stage indicated by the control signals from the thermostat. If the thermostat transmits a low stage demand signal to the stage control module <NUM>, then the stage control module <NUM> turns the solenoid valve <NUM> off/disengages the solenoid valve <NUM>. The drive control module <NUM> actuates the drive switch <NUM> to connect the incoming AC power to the drive <NUM>. The drive control module <NUM> actuates the first switch <NUM> to connect the first end of the main winding <NUM> of the motor <NUM> to the first output U of the drive <NUM>. The drive control module <NUM> also actuates the second switch <NUM> to connect the connection point <NUM> to the second output V of the drive <NUM>. The drive control module <NUM> also actuates the third switch <NUM> to connect the second end of the auxiliary winding <NUM> to the third output W of the drive <NUM>. In various implementations, the drive control module <NUM> actuates the first switch <NUM>, the second switch <NUM>, and the third switch <NUM> according to predetermined times at which to actuate each switch. Additionally, while the first switch <NUM>, the second switch <NUM>, and the third switch <NUM> are depicted as single pole double throw (SPDT) relays, each switch may be implemented as two separate single pole, single throw (SPST) relays.

In this configuration, during low stage, the motor control circuit <NUM> operates as a motor speed controller. The drive <NUM> controls application of the incoming AC power to the motor <NUM> based on signals from the drive control module <NUM>. For example, the drive <NUM> may control application of the incoming AC power to the motor <NUM> based on a compressor speed command from the drive control module <NUM>. Based on the speed command, the drive <NUM> may generate AC power to three-phase outputs from the incoming AC power and apply the three-phase outputs to the motor <NUM>.

The drive <NUM> may set one or more characteristics of the three-phase AC power based on the compressor speed command, such as frequency, voltage, and/or current. For example, the drive <NUM> may be a variable frequency drive (VFD). The drive control module <NUM> may determine a PWM duty cycle to apply to switches (not shown) of the drive <NUM> to generate AC power having corresponding characteristics. In various implementations, one or more electromagnetic interference (EMI) filters may be implemented inside the drive <NUM>. The drive control module <NUM> may set the compressor speed command to a plurality of different possible speeds for variable speed low stage operation of the motor <NUM> and the compressor <NUM>.

For mid stage, the stage control module <NUM> actuates the solenoid valve <NUM> to turn or remain off. For example, if the stage control module <NUM> receives control signals indicating mid stage operation and the motor <NUM> of the compressor is off, the stage control module <NUM> will begin motor operation in low stage and switch to mid stage, maintaining the solenoid valve <NUM> in the off position. However, if the stage control module <NUM> is changing from high stage to mid stage operation, the stage control module <NUM> will actuate the solenoid valve <NUM> to turn off. The drive control module <NUM> actuates the first switch <NUM> to connect the first end of the main winding <NUM> of the motor <NUM> to the first line voltage L1. The drive control module <NUM> actuates the second switch <NUM> to connect the connection point <NUM> to the second line voltage L2. The drive control module <NUM> actuates the third switch <NUM> to connect the second end of the auxiliary winding <NUM> to the start capacitor <NUM>. In this way, the motor <NUM> is configured to operate directly on the incoming AC power.

For high stage, the motor <NUM> is connected as described for the mid stage, operating directly on the incoming AC power. However, in response to receiving the high stage demand, the stage control module <NUM> actuates the solenoid valve <NUM> to turn on and engage, restricting the flow of pressurized gas to force the compressor <NUM> to operate at full capacity. The motor <NUM> is shown as having the main winding <NUM> and the auxiliary winding <NUM> and is a single phase, three wire, permanent split capacitor (PSC) motor.

In various implementations, the control module <NUM> may control a two speed PSC condensing fan motor or full variable speed BLDC or PSC condensing fan motor being driven by a motor control circuit similar to the motor control circuit <NUM> based on the signal from the drive control module <NUM> or the stage control module <NUM>. That is, the presently disclosed motor control implementation can operate both a compressor <NUM> and a condensing fan motor, providing an improved efficiency of the HVAC system. For example, the condensing fan <NUM> will operate low speed for low stage, low or high speed for mid stage, and high speed for high stage in case of <NUM> stage condensing fan motor. In case of variable speed BLDC or PSC condensing fan motor, the condensing fan <NUM> can operate at varying speeds based on the demand stages to realize best overall performance of the HVAC system-specifically, to perform most efficiency.

<FIG> is a table including multiple stages and corresponding demand inputs from a thermostat. The table of <FIG> summarizes the stage options. In various implementations, the same stage options may be implemented in demand for a condenser fan. The first row is when the demand signal directs that the compressor <NUM> operate at the low stage, connecting the motor <NUM> to the drive <NUM>. For the low stage, the Y1 demand signal is on, the Y2 demand signal is off, and the solenoid valve signal S is off.

The second row is when the demand signal directs that the compressor <NUM> operate at the mid stage, connecting the motor <NUM> to the incoming AC line power. For the mid stage, the Y1 demand signal is on, the Y2 demand signal is on, and the solenoid valve signal S is off.

The third row is when the demand signal directs that the compressor <NUM> operate at the high stage, connecting the motor <NUM> to the incoming AC line power. For the high stage, the Y1 demand signal is on, the Y2 demand signal is on, and the solenoid valve signal S is on.

The fourth and fifth rows are when the demand signal directs that the compressor <NUM> turn or remain off. In an off state, the motor <NUM> is connected to the AC power line but the drive <NUM> will maintain the motor <NUM> in an off state. When off, the Y1 demand signal is always off, the Y2 demand signal may be on or off, and the solenoid valve signal S is irrelevant. As mentioned previously, while control of the motor <NUM> using the first switch <NUM>, the second switch <NUM>, and the third switch <NUM> is described using SPDT relays, pairs of SPST relays may also be implemented.

<FIG> is a state diagram depicting a method and control algorithm of a thermostat and an example controller according to discrete inputs. The controller integrates a variety of features, preventing the combination of a variety of different controllers, the features including, but not limited to: reading temperature, humidity, etc.; determine the demand (as low, mid, or high); and controlling the actuation of the switches (first, second, and third). Additionally, the implementation of a single controller allows three stage operation on a main control board obviating multiple contacts and connections of high current lines.

The control algorithm shown in <FIG> may be executed by a combination of the thermostat <NUM> and the control module <NUM>. In various implementations, the control module <NUM> of the air handler unit <NUM> may perform the functionality of the thermostat <NUM>. The algorithm indicates operation of the compressor <NUM> described in <FIG> and switches the compressor <NUM> between the low stage, the mid stage, and the high stage based on the demands.

In an initial state <NUM>, the compressor <NUM> may be off. The thermostat may send a demand signal including Y1, Y2, and S for the compressor <NUM> to be off to the control module <NUM>, for example, in response to determining a demand after an air temperature in the space to be heated or cooled by the HVAC system dropping below (in the cooling mode) or rising above (in the heating mode) a selected setpoint temperature. That is, once the indoor temperature exceeds (or falls below) the setpoint temperature, the thermostat <NUM> determines the demand needed to reach the setpoint temperature at state <NUM>. As previously discussed, the demand (which stage) is determined based on OAT, humidity, and various additional parameters.

In response to determining to operate in low stage operation, the thermostat <NUM> transmits the demand signal to the control module <NUM> as Y1 on and Y2 off. In various implementations, the thermostat may also send an S off signal even though the solenoid will be in the off position if the motor is switching from off to low stage or mid stage to low stage. This combination of Y1, Y2, and S may demand low stage operation. In response to receiving the low stage demand, the control module <NUM> may initiate operation of the compressor <NUM> in the low stage at state <NUM>. During low stage operation, the solenoid remains in the off position. Since the motor <NUM> is operated using PWM control signals in low stage operation, solenoid control to restrict pressurized gas is not necessary or desirable as the restriction of pressurized gas is implemented to operate the compressor <NUM> in full capacity.

In low stage operation at state <NUM>, the control module <NUM> actuates the switches (discussed in <FIG>) to connect the motor <NUM> to the drive <NUM>. The drive <NUM> operates the motor <NUM> by implementing motor speed control of the motor <NUM> using, for example, PWM control. In low stage operation, the control module <NUM> turns or maintains the solenoid valve <NUM> off according to the S signal or simply by virtue of being in low stage. In various implementations, upon receiving the demand signal, the control module <NUM> may obtain a runtime (period) of the compressor <NUM> in each stage.

For example, as described in <CIT>, if the OAT is above a threshold temperature (<NUM> degrees Fahrenheit) and a previous mid stage or high stage capacity runtime is greater than a threshold (five minutes), the compressor may operate in low stage for a start threshold (five seconds) and then switch to mid stage or high stage. Otherwise, the compressor <NUM> may operate for a preset time (<NUM> minutes) at the demanded stage until the demand is no longer being received (that is, the demand has been met by the setpoint temperature being reached and the compressor <NUM> is to be turned off).

Once in low stage operation at state <NUM>, the compressor <NUM> remains in low stage operation as long as the demand signal including Y1 being on and Y2 being off is being received. If the received demand signal changes, control returns to state <NUM> to determine the demand. For example, if after being in state <NUM> in low stage operation, the setpoint temperature is reached, the thermostat <NUM> ends signal transmission to the control module <NUM>. Therefore, the demand signal to the control module <NUM> ends and operation switches from state <NUM> to state <NUM> to determine demand. If the demand signal being received includes Y1 being off, then the thermostat <NUM> is directing the control module <NUM> to turn the compressor <NUM> off and operation returns to the initial state <NUM> where the compressor <NUM> is off. In the initial state <NUM>, the control module <NUM> disconnects the set of switches described in <FIG> from L1 and L2 and connects to the drive <NUM> while the drive <NUM> maintains the motor <NUM> in an off state.

If at state <NUM> the thermostat <NUM> determines the demand to be mid stage operation, the thermostat <NUM> transmits the demand signal including Y1 being on, Y2 being on, and S being off. In response to receiving the mid stage operation demand, the control module <NUM> switches to low stage operation at <NUM> and then switches to mid stage operation shown at state <NUM>. In mid stage operation, the control module <NUM> actuates the switches such that the motor <NUM> is directly connected to the incoming AC line voltage and actuates the solenoid valve <NUM> to off. Mid stage operation continues at state <NUM> until the demand signal no longer includes Y1 on, Y2 on, and S off. While example combinations of Y1, Y2, and S are provided, other combinations of Y1, Y2, and S may be used to indicate different demands.

If at state <NUM> and the thermostat <NUM> determines the demand to be high stage operation, the thermostat <NUM> transmits the demand signal including Y1 being on, Y2 being on, and S being on. In response to receiving the high stage operation demand, the control module <NUM> switches to low stage operation <NUM>, then to mid stage operation at <NUM>, and then to high stage operation shown at state <NUM>. In high stage operation, the control module <NUM> actuates the switches such that the motor <NUM> is directly connected to the incoming AC line voltage (performed when switching to mid stage operation at <NUM>) and actuates the solenoid valve <NUM> to on when switching from mid stage operation <NUM> to high stage operation <NUM>. High stage operation continues at state <NUM> until the demand signal no longer includes Y1 on, Y2 on, and S on.

<FIG> is a flowchart depicting example operation of an example compressor <NUM> at multiple stages using a thermostat and an example controller. Control begins <NUM> to determine if an indoor difference (difference between an indoor temperature and a setpoint temperature) exceeds a threshold value. During heating, <NUM> may include determining whether the indoor temperature is less than the setpoint temperature by at least the threshold value. During cooling, <NUM> may include determining whether the indoor temperature is greater than the setpoint temperature by at least the threshold value. As described previously, the threshold value may be adjusted in response to user input. If no, control continues to <NUM> to transmit a control signal to turn the compressor <NUM> off. In this way, for example, the thermostat is transmitting a control signal to keep the compressor <NUM> off at all times since the compressor <NUM> is not used to adjust the indoor temperature.

In various implementations, the thermostat may only turn the compressor <NUM> off once and wait for the indoor difference to exceed a threshold and turn the compressor <NUM> on. Then, control returns to <NUM> to determine if the indoor difference has exceeded the threshold. Otherwise, control continues to <NUM> to determine a demand based on the indoor difference, OAT, humidity, and runtime. As described previously, the demand may be determined based on one or more additional parameters. In various implementations, control may adjust the operating stage based on a present runtime. For example, if low stage operation has exceeded a threshold period and the setpoint has not been reached, control may adjust the stage to mid stage or high stage operation as low stage operation did not provide effective temperature adjustment within the threshold period.

Control continues to <NUM> to determine if the demand is set to low stage. If yes, control proceeds to <NUM> to transmit a control signal to turn the solenoid valve <NUM> off and control the switches to connect the motor <NUM> to the drive <NUM>. Then, control continues to <NUM> to determine if a setpoint temperature is reached. If yes, control returns to <NUM>. In various implementations, control may instead operate the compressor <NUM> at the determined stage for a set amount of time. At <NUM>, if the setpoint temperature is not reached, control returns to <NUM> to determine demand (for example, to adjust the demand based on the runtime of a particular stage).

Returning to <NUM>, if the demand is not set to low stage, control proceeds to <NUM> to determine if the demand is set to mid stage. If yes, control continues to <NUM> to transmit a control signal to turn the solenoid valve <NUM> off and control the switches to connect the motor <NUM> to the line voltage (e.g., the incoming AC power). Then, control returns to <NUM> to determine if the setpoint temperature is reached.

Returning to <NUM>, if the demand is not set to mid stage, control proceeds to <NUM> to determine if the demand is set to high stage. If yes, control continues to <NUM> to transmit a control signal to control the switches to connect the motor <NUM> to the line voltage and turn the solenoid valve <NUM> on. Then, control returns to <NUM> to determine if the setpoint temperature is reached. Returning to <NUM>, if the demand is not set to high stage, control proceeds to <NUM> to select a default stage if the demand does not indicate one of the three stages and continues to <NUM>. The default stage may be any of the low, mid, or high stages. Alternatively, at <NUM>, control may generate and transmit an error or fault message as the demand is not indicated or not compatible with the stages and returns to <NUM>.

The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure, as long as they fall within the scope of the appended claims.

Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed. " Unless explicitly described as being "direct," when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean "at least one of A, at least one of B, and at least one of C.

In the figures, the direction of an arrow, as indicated by the arrowhead, generally demonstrates the flow of information (such as data or instructions) that is of interest to the illustration. For example, when element A and element B exchange a variety of information but information transmitted from element A to element B is relevant to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is transmitted from element B to element A. Further, for information sent from element A to element B, element B may send requests for, or receipt acknowledgements of, the information to element A.

In this application, including the definitions below, the term "module" or the term "controller" may be replaced with the term "circuit. " The term "module" may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.

The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks, flowchart components, and other elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc..

Claim 1:
A system for controlling a capacity of a compressor (<NUM>), comprising:
a motor (<NUM>) of the compressor (<NUM>) including a main winding (<NUM>) connected at a connection point (<NUM>) to an auxiliary winding (<NUM>);
a drive (<NUM>) configured to control a speed of the motor (<NUM>);
a first switch (<NUM>) configured to selectively connect the main winding (<NUM>) to either (a) a first line voltage (L1) or (b) a first output of the drive (<NUM>)
a second switch (<NUM>) configured to selectively connect the connection point (<NUM>) to either (a) a second line voltage (L2) or (b) a second output of the drive (<NUM>);
a third switch (<NUM>) configured to selectively connect the auxiliary winding (<NUM>) to either (a) a capacitor (<NUM>) or (b) a third output of the drive (<NUM>);
a solenoid valve (<NUM>) configured to selectively either operate in (a) a first capacity or (b) a second capacity; and
a control module (<NUM>) configured to control the drive (<NUM>), the first switch (<NUM>), the second switch (<NUM>), and the third switch (<NUM>) by:
in response to receiving a demand in a first state:
switching the first switch to connect the main winding to the first output of the drive;
switching the second switch to connect the connection point to the second output of the drive;
switching the third switch to connect the auxiliary winding to the third output of the drive; and
switching the solenoid valve to the first capacity;
in response to receiving the demand in a second state:
switching the first switch to connect the main winding to the first line voltage;
switching the second switch to connect the connection point to the second line voltage;
switching the third switch to connect the auxiliary winding to the capacitor; and
maintaining the solenoid valve at the first capacity; and
in response to receiving the demand in a third state:
switching the first switch to connect the main winding to the first line voltage;
switching the second switch to connect the connection point to the second line voltage;
switching the third switch to connect the auxiliary winding to the capacitor; and
switching the solenoid valve to the second capacity.