Described is a vector control system for a vapor compression circuit. The vector control system may monitor the vapor compression circuit and adjust the speed of one or more motors to increase efficiency by taking into account the torque forces placed on a compressor motor.

A heat transfer unit includes: an electrical component casing defining an internal space, the internal space housing a transformer together with a control board and a power supply board; and a cooling unit which cools an electronic component on the power supply board during operation of a compressor.

An air-conditioning apparatus includes a bypass pipe through which part of refrigerant discharged from a discharge port of a compressor flows. Heating components provided on a substrate of the controller include a first heating component and a second heating component that generates a smaller amount of heat than the first heating component. The first heating component is provided such that a longitudinal direction of the first heating component is parallel to a flow direction of the refrigerant in the bypass pipe, the longitudinal direction being a direction in which long sides of the first heating component extend. The second heating component is provided such that a widthwise direction of the second heating component is parallel to the flow direction of the refrigerant in the bypass pipe, the widthwise direction being a direction in which short sides of the second heating component extend.

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.

An air conditioning system includes a compressor including a motor, a condenser, and an evaporator; a drive including an inverter providing a multiphase, AC output voltage to the motor; a current sensor configured to sense an output current generated by the inverter; a controller configured to communicate with the current sensor and the inverter, the controller configured to provide a voltage command to the inverter, the controller configured to execute operations including: monitor the output current generated by the inverter; compare the output current to a threshold; determine the occurrence of an over current condition when the output current exceeds the threshold; when an over current condition is detected, reducing the voltage command to the inverter.

A heat pump apparatus includes: a compressor including a motor; an inverter that applies a desired voltage to the motor; a current detector that detects current flowing to the motor; a drive-signal generation unit that generates a drive signal for the inverter; a magnetic-pole position estimation unit that changes a voltage phase of a voltage command value for a high-frequency voltage, and estimates a maximum-heat-amount acquisition magnetic-pole position when the generation unit applies the high-frequency voltage to the motor to heat the compressor; a steady heating control unit that determines an amplitude and voltage phase of the voltage command value from the maximum-heat-amount acquisition magnetic-pole position and a defined necessary amount of heat when the generation unit applies the high-frequency voltage to the motor to heat the compressor; and a control switching determination unit that causes one of the estimation unit and the heating control unit to operate.

A direct-current power supply includes: a rectifier circuit in which switching elements are bridge-connected; a reactor; a gate circuitry that drives the switching elements; and a gate circuitry that drives the switching elements. A connection point between the switching element and the switching element is connected to an alternating-current power supply via the reactor, and a connection point between the switching element and the switching element is connected to the alternating-current power supply without via the reactor. A time during which the gate circuitry turns on the switching elements is longer than a time during which the gate circuitry turns on the switching elements.

A control method for an air conditioner comprising a compressor and an outdoor unit, wherein the control method includes: obtaining a suction temperature of the outdoor unit; and selectively adjusting the frequency of the compressor according to the suction temperature of the outdoor unit.

A refrigerating cycle device includes a compressor, a motor, and a wiring switch part. The compressor compresses a refrigerant. The motor generates power for compressing the refrigerant by rotating a rotor with voltage applied to a plurality of wirings. The motor is disposed in the compressor. The wiring switch part switches between a plurality of wiring states by changing connection between the plurality of wirings. When a rotational speed of the rotor exceeds a predetermined value, the wiring switch part switches to a first wiring state of the plurality of wiring states. The first wiring state differs from a second wiring state of the plurality of wiring state. Efficiency of the second wiring state is highest at the rotational speed.

A chiller includes an evaporator, a compressor including a prime mover, a first pressure sensor that detects a first pressure in the evaporator, a second pressure sensor that detects a second pressure in a condenser, and a controller. The controller determines a predicted energy level of the compressor based on the first pressure and the second pressure, the predicted energy level associated with liquid droplet flow into the compressor, compares the predicted energy level to an operating energy level, and modifies the at least one of the input power and the input current to the prime mover based on the comparison satisfying a modification condition.