A refrigeration system includes a first refrigerant circuit having a first compressor, and a second refrigerant circuit having a second compressor, the second refrigerant circuit separate from the first refrigeration circuit. A variable frequency drive (VFD) is in signal communication with the first compressor and the second compressor and is configured to enable a variable speed operation of the first and second compressors. A controller is in signal communication with the VFD. The controller is programmed to selectively switch the first and second compressors between a variable speed operation using the VFD and a fixed speed operation such that in a first mode the first compressor is operated in the fixed speed operation and the second compressor is operated in the variable speed operation, and in a second mode the second compressor is operated in the fixed speed operation and the first compressor is operated in the variable speed operation.

A heat exchanger includes fins that are arranged in a direction orthogonal to a direction in which air flows and a heat transfer pipe that extends through the fins and that is bonded and fixed to the fins when the heat transfer pipe is radially expanded by a pipe-expanding method. Tall projections and short projections are provided on an inner surface of the heat transfer pipe. The tall projections are arranged in a circumferential direction and extend in an axial direction of the heat transfer pipe. The short projections are arranged between the tall projections and extend in the axial direction. Opposing side surfaces of the tall and short projections after the expansion of the heat transfer pipe are so inclined that when extensions are drawn from the side surfaces, the extensions cross each other in an inner region of the heat transfer pipe.

A compressor crankcase heating control method for a heat pump system includes selectively actuating a first switching device to connect and disconnect first and second power lines to and from second and third switching devices, respectively, the first and second power lines receive a first voltage. The compressor crankcase heating control method further includes, when the first and second power lines are disconnected from the second and third switching devices via the first switching device, actuating the second and third switching devices thereby connecting third and fourth power lines to ends, respectively, of at least one winding of a stator of an electric motor of a compressor. The at least one winding of the stator of the electric motor heats the crankcase of the compressor. The third and fourth power lines receive a second voltage that is less than the first voltage.

An air conditioner for a vehicle has a compressor, a radiator, a first pressure reducer, a gas-liquid separator, a second pressure reducer, an exterior heat exchanger, an intermediate pressure refrigerant passage, a switching device, and a controller. The controller operates the switching device to switch from a refrigerant circuit of a two-stage compression mode to a refrigerant circuit of a single-stage compression mode when a compressor stop signal is output in the two-stage compression mode. The single-stage compression mode is a mode that blocks at least a flow of an intermediate-pressure refrigerant into the intermediate pressure refrigerant passage and makes refrigerant remained in the intermediate pressure refrigerant passage to flow out of the intermediate pressure refrigerant passage. The controller stops the compressor after controls the compressor to continue operating for a specified time in the single-stage compression mode. The controller restarts the compressor when the compressor stop signal is canceled.

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.

Inverter for an electric compressor comprising an auxiliary voltage supply that supplies a control electronics of the inverter with a DC voltage. The auxiliary voltage supply comprises a series circuit of a linear voltage regulator and a linear pre-regulator. The linear pre-regulator comprises a transistor and is connected to the input terminal of the linear voltage regulator. The linear pre-regulator and/or the linear voltage regulator are advantageously actively cooled by a refrigerant utilized in the electric compressor.

A refrigerator includes a compressor, a cold storage medium, a power supply to convert AC power supplied from an outside of the refrigerator, and to receive DC power during interruption of electric power, and a controller to perform a control operation to supply a cooling capacity to an interior of the refrigerator by driving the compressor based on the supplied AC power when no interruption of electric power occurs, and to perform a control operation to supply a cooling capacity to the interior of the refrigerator based on the supplied DC power and the cold storage medium during the interruption of electric power. Accordingly, consumption of electric power during interruption of electric power is reduced.

A refrigerating and air-conditioning apparatus performs a defrosting operation. The refrigerating and air-conditioning apparatus includes a refrigerant circuit, a temperature sensor, and a heat generation control unit. In the refrigerant circuit, a compressor, a first heat exchanger, an expansion device, a second heat exchanger, and a four-way valve are connected to each other by pipes to allow refrigerant to circulate through the refrigerant circuit. The temperature sensor measures a temperature of the compressor. The heat generation control unit increases a temperature of the compressor when the heat generation control unit detects a decrease in a value measured by the temperature sensor in a defrosting operation performed on the first heat exchanger.

A control device controls a heating capacity during a heating operation and a defrosting capacity during a defrosting operation. The defrosting capacity of the first refrigeration cycle unit is determined to fall within a range satisfying a first determination condition and within a range satisfying a second determination condition. The first determination condition is a condition that a sum of a load capacity of a load device when the first defrosting start condition is satisfied, and the defrosting capacity of the first refrigeration cycle unit does not exceed the heating capacity of a second refrigeration cycle unit. The second determination condition is a condition that a sum of an inter-unit defrosting interval and a defrosting period of the first refrigeration cycle unit does not exceed a shortest defrosting interval of the second refrigeration cycle unit.

A motor driving device includes an inverter that supplies alternating-current voltage to a motor whose speed is variable due to a load variation caused by a compressor, and a control device. The control device includes a frequency estimation unit estimating a frequency estimation value indicating a rotation of the motor, a speed controlling unit generating a first torque current command value based on a deviation between the frequency estimation value and a frequency command value, a load torque estimation unit estimating a load torque applied to the motor, a compensation value calculation unit calculating a torque current compensation value based on the load torque, where the torque current compensation value causes the motor to accelerate in a period including timing of the maximum load torque, and an adding unit generating a second torque current command value based on the first torque current command and torque current compensation values.