The motor driving apparatus includes a switch that is a mechanical switch for changing coil connection states of a motor; an inverter that generates alternating voltage from direct voltage and outputs the alternating voltage to the motor; and a control device that controls the switch and the inverter. The control device causes the switch to change the coil connection states while the alternating voltage output from the inverter is zero.

A motor driving device that drives a motor and is capable of switching a connection state of stator windings of the motor, includes: relays to switch the connection state of the stator windings by switching positions of contact plates; and a contact control unit to control each of the positions of the contact plates by outputting, to the relays, signals for actuating the contact plates. The contact control unit switches the connection state by sequentially switching output values of the signals such that the output values of the signals are switched at different timings from each other in the relays, and changes a switching order every time the connection state is switched, the switching order being an order in which the output values of the signals are switched.

The control method and system for the variable-frequency compressor includes: acquiring an operation current and an operation frequency of the variable-frequency compressor; determining that the operation current is greater than or equal to a preset frequency-limited current, and reducing the operation frequency to a preset frequency-limited frequency so as to enable the variable-frequency compressor to enter a frequency-limited mode; detecting an operation current at the moment of the variable-frequency compressor every preset duration; determining that the operation current at the moment meets a preset up-conversion condition, and increasing an operation frequency at the moment of the variable-frequency compressor by a preset up-conversion frequency step size until the variable-frequency compressor retreating from the frequency-limited mode; and determining that the operation current at the moment does not meet the preset up-conversion condition, and controlling the variable-frequency compressor to maintain the operation frequency at the moment.

Systems and methods for monitoring an HVAC&R system employ a monitoring agent that uses observations of evaporator and condenser intake temperatures, evaporator discharge temperature, and a compressor input power parameter to learn operating characteristics of the HVAC&R system in newly maintained condition. Thereafter, the agent continuously or regularly computes a relative coefficient of performance (COP) for the system under subsequent observed ambient conditions, and relates the present instantaneous efficiency of the HVAC&R system under the observed ambient conditions to the instantaneous efficiency when the system was in newly maintained condition. The relative COP can be used to detect system degradation and quantify the energy usage and cost attributable to the degradation. The agent can take appropriate actions to prevent/minimize damage based on the degree of degradation detected, including shutting off power to the HVAC&R system. The monitoring agent can also be extended to other types of systems besides HVAC&R system.

An electric control assembly for an air conditioner is provided. The assembly has an electric control board, a fan driving circuit and a compressor driving circuit. A ground end of the fan driving circuit and a ground end of the compressor driving circuit are connected with two reference grounds of the electric control board in one-to-one correspondence. The assembly also has a switch isolation driving circuit, a first input end of which is connected with a control end of the compressor driving circuit. A first output end of the switch isolation driving circuit is connected with a controlled end of the fan driving circuit. A second input end of the switch isolation driving circuit is connected with a control end of the fan driving circuit. A second output end of the switch isolation driving circuit is connected with a feedback end of the compressor driving circuit.

The auxiliary AC system includes a temperature measurement device configured to generate a variable output based on an air temperature in an environment proximate to the AC system and a compressor control circuit communicably coupled to a variable speed motor. The compressor control circuit is configured to receive the variable output from the temperature measurement device, determine that the output indicates a change in the air temperature, and generate a control signal for the variable speed motor, the control signal including a current having a magnitude depending on the extent of the change to vary a rate at which a compressor pressurizes a refrigerant vapor.

A system includes an electronic power converter and a controller. The electronic power converter supplies power to one or more motor drives of an HVAC system. The controller obtains a plurality of pulse width modulation (PWM) algorithms. Each PWM algorithm has an associated spectrum of frequencies. The controller further determines one or more resonance frequencies associated with the HVAC system. The controller also selects a first PWM algorithm from the plurality of PWM algorithms wherein the spectrum of frequencies of the first PWM algorithm lacks frequency peaks that overlap with the one or more resonance frequencies associated with the HVAC system. The controller further operates the electronic power converter according to the first PWM algorithm.

A method for increasing working gas flow rate through gas bearings of a free piston, gamma configured Stirling heat pump to avoid failure of the gas bearings while maintaining thermal cooling power. The Stirling heat pump lifts heat from a storage chamber and has pistons that are driven in reciprocation at an operating frequency by linear electric motors. A temperature control maintains a steady state storage chamber temperature by sensing storage chamber temperature and modulating piston amplitude. The invention comprises (a) driving the pistons with linear electric motors that are driven by a variable frequency, AC power source; (b) sensing the pistons' amplitude of reciprocation; and (c) if the sensed piston amplitude is less than a selected piston activation amplitude, increasing the frequency of the AC power source to increase the Stirling heat pump's operating frequency. That decreases thermal cooling power which causes the temperature control to increase piston amplitude.

A method for operating an appliance motor includes receiving a target speed for the motor, obtaining a power limit for the motor, determining an inverter current limit based at least in part on the target speed and the power limit, determining an inverter output current to achieve the target speed, wherein the inverter output current is limited to the inverter current limit, and supplying the motor with the inverter output current.

A refrigerant leak management system includes a return inlet assembly and a purge exhaust outlet assembly. The system also includes a sensor configured to detect refrigerant proximate an air handling enclosure of a HVAC unit. The system further includes a controller configured to control the system to drive air from a conditioned interior space of a building into an external environment via the purge exhaust outlet assembly when the sensor detects the refrigerant proximate the air handling enclosure by: actuating the return inlet assembly to close the return inlet assembly, actuating the purge exhaust outlet assembly to open the purge exhaust outlet assembly, and activating a reversible supply fan of the HVAC unit in a reverse direction.