Adaptive Variable Speed Control Method, Adaptive Variable Speed Controller and Method for Operating the Same

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

As shown in, the method for operating the variable speed controller includes the following steps Sto S.

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

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

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

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

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

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

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

In step S, the compressor is stopped being driven.

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

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

As shown in, the method for operating the variable speed controller includes the following steps Sto S.

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

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

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

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

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

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

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

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

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

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

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

In step S, it is determined whether the change in the outdoor load in the interval meets the second preset condition and whether Sis greater than a minimum non-zero system operation speed Smin. If determined that the change in the outdoor load already meets the second preset condition and Sis greater than Smin, the initial system operation speed Sfor the present operation is set to be smaller than S.

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

The method proceeds to step Sif it is determined in step Sthat the system operation speed does not change during the previous operation (i.e., the nth operation). In step S, it is determined whether the previous operation has lasted less than the second preset period of time T. The method proceeds to step Sif determined that the previous operation has lasted less than T. In step S, the initial system operation speed Sfor the present operation is set to be less than S. Sis greater than the minimum non-zero system operation speed Smin. The method proceeds to step Sif determined that the previous operation has lasted for at least T. In step S, the initial system operation speed Sfor the present operation is set to S.

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

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

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

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

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

The initial system operation speed is determined from the table shown inas follows.

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

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

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