A motor-driven compressor includes a compression portion, an electric motor, an inverter, and a metal housing. The inverter includes three-phase switching elements and a plastic holder that retains the three-phase switching elements. The housing includes a thermal radiation surface. The holder includes a metal spring. The holder is fixed to the housing using two fasteners. The three-phase switching elements are laid out between the two fasteners. The switching elements at opposite ends of the three-phase switching elements are pressed toward the thermal radiation surface by only the holder. The switching element at the middle of the three-phase switching elements is pressed toward the thermal radiation surface by the holder and the spring.

A control method, for a refrigerator, that includes driving a refrigerator compartment compressor that is configured to cool a refrigerator compartment; determining whether a temperature in the refrigerator compartment satisfies a first temperature; driving, based on the determination that a temperature in the refrigerator compartment satisfies the first temperature, a freezer compartment compressor that is configured to cool a freezer compartment; stopping the refrigerator compartment compressor; maintaining, after stopping the refrigerator compartment compressor, operation of the freezer compartment compressor; restarting the refrigerator compartment compressor; and varying a driving frequency of the refrigerator compartment compressor is disclosed.

Disclosed is a method for controlling a solar air conditioner, which includes: a detection step, detecting the change situation of a DC voltage outputted by an inverter of the solar air conditioner when it is detected that the solar air conditioner enters an energy-saving control mode; and a judging step, adjusting an operating frequency of a compressor of the solar air conditioner according to the change situation of the DC voltage, so that the solar air conditioner uses a solar cell to supply power. Thus, solar energy can be used to the maximum degree, the problem that there is a need to supply power by a mains power supply because the power supplied for the solar energy is insufficient is avoided, and the cost is saved. Further a device for controlling the solar air conditioner and the solar air conditioner are provided.

A power converting apparatus includes: a rectifying unit configured to rectify an input AC power, a buck converter that is configured to step down a voltage of the rectified power and that is configured to output DC power having the step down voltage, a first inverter that is connected to an output terminal of the buck converter and that is configured to convert the DC power into AC power to drive a first motor, a second inverter that is connected to the output terminal of the buck converter, that is disposed in parallel to the first inverter, and that is configured to convert the DC power into AC power to drive a second motor, and a converter controller configured to control an output voltage of the DC power of the buck converter.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

A compressor driving device includes a three-phase alternating current power supply input end, a relay module, a rectifier circuit, and a driving control circuit which are sequentially connected; the rectifier circuit is used for converting connected alternating current into direct current and then outputting the direct current to a direct current bus; the driving control circuit is used for converting the direct current output by the direct current bus into compressor driving power; a pressure switch is used for measuring the pressure value in a refrigerating system, and when the measured pressure value is larger than a preset pressure threshold, disconnecting the power supply circuit of the relay module; the driving control circuit is also used for detecting the on-off state of the pressure switch and controlling the compressor to stop working when the pressure switch is switched off.

A screw compressor includes a screw rotor, a gate rotor, and a speed adjuster. The screw rotor has an outer peripheral surface with a plurality of screw grooves. The screw rotor is configured to be rotated. The gate rotor has a plurality of teeth. A ratio T/S of a number T of the teeth to a total number S of the screw grooves is greater than or equal to 2.5. The gate rotor meshes with the screw rotor. The speed adjuster is configured to adjust a rotational speed of the screw rotor. Rotation of the screw rotor at an angle greater than 180 allows the screw compressor to perform a stroke from start of compression to completion of discharge.

A compressor for a heat transfer circuit includes a variable frequency drive (VFD), an electric motor that rotates a driveshaft, bearing(s) for supporting the driveshaft, a backup gas supply, and a power supply. During a utility power interruption, the backup gas supply operates utilizing DC electrical power generated by a back electromotive force of the electric motor. A method of operating an electric power supply system for a compressor includes operating in a utility power mode and operating in a backup power mode during a utility power interruption. In the utility power mode, AC electrical power is supplied from the VFD to the motor. In the backup power mode, DC electrical power generated in the VFD by a back electromotive force of the motor it used to operate a backup gas supply to supply compressed working fluid to gas bearing(s) of the compressor.

A power converter includes: a rectifying and boosting unit that rectifies first alternating-current power supplied from a commercial power supply and boosts a voltage of the first alternating-current power; a capacitor connected to an output end of the rectifying and boosting unit; an inverter to convert power output from the rectifying and boosting unit and the capacitor into second alternating-current power, and output the second alternating-current power to a device; and a control unit that reduces a current flowing through the capacitor by controlling the rectifying and boosting unit and by controlling the inverter such that the inverter outputs, to the device, the second alternating-current power containing a ripple dependent on a ripple of power flowing from the rectifying and boosting unit into the capacitor. The control unit controls in accordance with a load state.

A motor drive device includes a reactor, a converter circuit, a capacitor, an inverter circuit, and overcurrent determination units. The converter circuit converts a first AC voltage output from an AC power supply into a DC voltage. The capacitor smooths a second voltage on the DC side of the converter circuit. The inverter circuit converts DC power stored in the capacitor into AC power. One of the overcurrent determination units determines overcurrent based on a detected value of the first AC current, flowing between the AC power supply and the converter circuit. Another overcurrent determination unit determines overcurrent based on a detected value of the second DC current, flowing between the converter circuit and the capacitor. The converter and inverter circuits stop operating when the determination result of one of the overcurrent determination units indicates an overcurrent.