A power conversion device includes a rectification unit that rectifies first alternating current (AC) power supplied from a commercial power supply, a capacitor connected to an output end of the rectification unit, an inverter that converts power output from the rectification unit and from the capacitor into second AC power, and outputs the second AC power to a load including a motor, which inverter is connected to both ends of the capacitor, and a control unit that controls operation of the inverter to output the second AC power from the inverter to the load to reduce current flowing to the capacitor, which second AC power includes a pulsation that depends on a pulsation of power flowing from the rectification unit to the capacitor. No discharge circuit and no overvoltage protection circuit are provided for the capacitor.

A power conversion device supplies power to a load. The power conversion device includes a power conversion unit, a control unit, a noise suppression unit, and an error detection unit. The power conversion unit receives power from a first power source. The control unit controls the power conversion unit. The noise suppression unit is connected between the first power source and the power conversion unit and outputs a noise suppression signal to suppress noise generated from the power conversion unit. When an error condition is established, the error detection unit detects an error. The error condition indicates that the error has occurred in the power conversion device or the load. The error condition includes a condition that an amount of noise generated from the power conversion unit is larger than a reference value.

A motor-driven compressor and a housing for the motor-driven compressor are provided. A power line connector and a communication line connector are arranged on an external surface of a housing. A first terminal of an interlocking communication line is located in the power line connector. A second terminal of the interlocking communication line is located in the communication line connector. The interlocking communication line is routed on the external surface from the first terminal to the second terminal.

A motor drive device performs a feedback control of a motor based on a motor current that is a current flowing in the motor. The motor drive device includes: an index value calculation unit configured to calculate power or a work rate of the motor as an index value for use in determining whether an abnormality occurs in the motor or not based on the motor current and a control parameter used in the feedback control; a filter unit configured to perform a filtering process to extract an abnormal component by removing a component that is in a normal operating state, from the index value calculated by the index value calculation unit; and a diagnosis unit configured to conduct a diagnosis of the motor regarding an abnormality or degradation thereof based on the abnormal component of the index value.

A power converting apparatus includes: a rectifier unit rectifying first alternating-current power supplied from a commercial power supply; a capacitor connected to an output end of the rectifier unit; an inverter connected across the capacitor, the inverter generating second alternating-current power and outputting the second alternating-current power to a motor; a voltage detecting unit detecting a first direct-current bus voltage, the first direct-current bus voltage being a voltage across the capacitor; and a control unit including a specific frequency bandpass unit passing a defined frequency band among power-supply pulsatile components contained in the first direct-current bus voltage, the control unit controlling an operation of the inverter and the motor by using a second direct-current bus voltage, the second direct-current bus voltage being the first direct-current bus voltage after passing through the specific frequency bandpass unit.

A heat source unit constitutes a refrigeration apparatus by being connected to a utilization-side unit. The heat source unit includes a low-stage compression element, a high-stage compression element, and a heat exchanger. The low-stage compression element has a discharge pipe provided with a pressure switchgear. The high-stage compression element compresses a refrigerant discharged from the low-stage compression element. When the low-stage compression element is paused in response to activation of the pressure switchgear, the high-stage compression element operates while the low-stage compression element is kept paused.

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 device management system for an inverter compressor is a device management system for an inverter compressor provided with a motor to be driven by an inverter, and includes: a partial discharge detector that detects a voltage of the motor to detect a partial discharge that occurs in the motor; and a determination module that determines whether there is a risk of occurrence of the partial discharge or whether the partial discharge occurs based on a result of detection by the partial discharge detector. When the voltage detected by the partial discharge detector is higher than a first threshold, the determination module determines that there is a risk of the occurrence of the partial discharge or the partial discharge occurs, and performs a protective operation to reduce the risk of the occurrence of the partial discharge in the motor or the occurrence of the partial discharge in the motor.

A compressor unit of a cryocooler includes: a compressor motor; an inverter that converts, into drive power of the compressor motor, AC power input to the compressor unit from an external power source; a transformer that converts the AC power into drive power of a cold head of the cryocooler of which a voltage is different from a voltage of the AC power, and a control panel on which the inverter and the transformer are mounted.

A power converter includes: a rectifier that rectifies a first alternating-current power supplied from an alternating-current power supply; a smoother connected to an output end of the rectifier; an inverter that is connected across the smoother, converts a first direct-current power output from the rectifier and the smoother into a second alternating-current power, and outputs the second alternating-current power to a motor; a controller that controls an operation of the inverter such that the second alternating-current power containing pulsation according to pulsation of power flowing into the smoother from the rectifier is output from the inverter to the motor; a DC-DC converter that includes at least one switching element, is connected across the smoother, and converts the first direct-current power into a second direct-current power by causing the switching element to perform switching; and a DC-DC converter controller that causes the switching element to perform switching.