The invention relates to an electric compressor control device comprising a low-voltage domain. The low-voltage domain comprises a first control unit set up to process control commands for the control of the electric compressor, and a first voltage supply set up to supply the first control unit and connected to a low-voltage source. The low-voltage domain comprises furthermore a high-voltage domain. The high-voltage domain comprises a second control unit set up to control a power output stage, wherein the power output state inverts a dc voltage from a high-voltage source into an ac voltage in order to supply a motor of the electric compressor with the ac voltage. The high-voltage domain comprises furthermore a second voltage supply set up to supply the second control unit and connected to the high-voltage source.

A drive circuit is provided and includes a rectification circuit, a buck converter, a first inverter, and a second inverter. The rectification circuit is configured to rectify a first AC voltage signal to generate a rectified voltage signal. The buck converter is configured to downconvert the rectified voltage signal to a DC voltage signal, wherein the DC voltage signal is supplied to a DC bus. The first inverter is configured to convert the DC voltage signal to a second AC voltage signal and supply the second AC voltage signal to a compressor motor. The second inverter is configured to convert the DC voltage signal to a third AC voltage signal and supply the third AC voltage signal to a condenser fan motor. Peak voltages of the second AC voltage signal and the third AC voltage signal are less than peak voltages of the first AC voltage signal.

A heat pump includes a compressor for compressing a refrigerant, a first heat exchanger, a main expansion mechanism and a second heat exchanger arranged in a refrigeration path, the compressor having a suction port, a compression port and an injection port; a gas injection valve connected on a first side to the refrigeration path between the first heat exchanger and the main expansion mechanism and on a second side to the injection port of the compressor; a liquid injection valve connected on a first side to the refrigeration path between the first heat exchanger and the main expansion mechanism and on a second side between the second heat exchanger and the suction port of the compressor; and a controller, the controller being configured to operate the gas injection valve to inject at least partly gaseous refrigerant into the compressor through the injection port of the compressor, and to operate the liquid injection valve to inject substantially liquid refrigerant into the compressor through the suction port of the compressor.

A photovoltaic air conditioner control method and apparatus and a photovoltaic air conditioner. The method includes: detecting in real time the grid-connected side inverter module temperature and the grid-connected side current of a photovoltaic air conditioner; determining the interval in which the grid-connected inverter module temperature is located and the interval in which the grid-connected side current is located; and, on the basis of the determining results, performing frequency-limiting and frequency-reduction control of the photovoltaic air conditioner.

A current estimating device that estimates a capacitor current of a high-voltage circuit for driving a motor, wherein the current estimating device calculates a voltage utilization rate using the input voltage of an inverter included in the high-voltage circuit and the speed of the motor, calculates a first constant by applying the voltage utilization rate to a predetermined first arithmetic expression, and calculates the capacitor current of an electrical condenser included in the high-voltage circuit by multiplying the first constant by a motor current effective value.

A refrigeration cycle apparatus includes a first flow switch valve including first to fourth ports, a second flow switch valve and a third flow switch valve each including fifth to seventh ports, a compressor, a discharge pipe connecting a discharge port of the compressor and the first port, a first high pressure pipe connecting between the discharge pipe and the fifth ports, a bypass expansion valve provided at a part of the first high pressure pipe, the part extending, a first outdoor heat exchanger connected to the seventh port of the second flow switch valve, a second outdoor heat exchanger connected to the seventh port of the third flow switch valve, and a controller. The controller is configured to perform a differential pressure ensuring process, when switching the second flow switch valve or the third flow switch valve. In the differential pressure ensuring process, the controller is configured to set operation frequency of the compressor to a first frequency and set opening degree of the bypass expansion valve to a first degree if a first condition is not met, and set the operation frequency of the compressor to a second frequency which is higher than the first frequency or set the opening degree of the bypass expansion valve to a second degree which is larger than the first degree if the first condition is met.

Provided is an air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit, the air-conditioning device including a heating means provided to the compressor, and configured to heat refrigerant in the compressor, and a controller configured to control the heating means. The controller includes a heat load learning unit configured to learn a heat load based on temperature data and air conditioning data, a stagnation prevention control start timing estimation unit configured to estimate a stagnation prevention control start timing based on the heat load obtained by learning, the stagnation prevention control start timing being a timing at which a stagnation prevention control of heating the compressor is started, and a device control unit configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing estimated.

A direct current power supply device includes: a reactor; a converter connected to an alternating current power supply via the reactor; a smoothing capacitor connected between output terminals of the converter; an inrush current preventing circuit disposed on a charging path from the alternating current power supply to the smoothing capacitor; a current detection unit detecting direct current representing an operating state on an output side of the converter; a current detection unit detecting power supply current representing an operating state on an input side of the converter; and a control unit receiving the direct current and the power supply current and controlling an operation of the converter. The control unit receives a detected value of saturated current from at least one of the direct current and the power supply current when the power supply voltage recovers from a state in which the power supply voltage is reduced.

The present disclosure relates to a motor driving apparatus and an air conditioner including the same. The motor driving apparatus and the air conditioner including the same according to an embodiment of the present disclosure include: a switching device disposed between an inverter and a motor; and a controller, which in response to windings of the motor being switched from a first connection to a second connection, controls an operating frequency of the motor to be less than or equal to a first frequency, and in response to the windings of the motor being switched from the second connection to the first connection, controls an operating frequency of the motor to be less than or equal to a second frequency which is less than the first frequency. Accordingly, burnout of the switching device for switching connection of the motor windings may be prevented.

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.