US 12,316,237 B2
Power conversion device, motor drive unit, and refrigeration cycle apparatus
Takaaki Takahara, Tokyo (JP); Koichi Arisawa, Tokyo (JP); Keisuke Uemura, Tokyo (JP); Haruka Matsuo, Tokyo (JP); and Koyo Matsuzaki, Tokyo (JP)
Assigned to Mitsubishi Electric Corporation, Tokyo (JP)
Appl. No. 18/043,132
Filed by Mitsubishi Electric Corporation, Tokyo (JP)
PCT Filed Oct. 26, 2020, PCT No. PCT/JP2020/040133
§ 371(c)(1), (2) Date Feb. 27, 2023,
PCT Pub. No. WO2022/091186, PCT Pub. Date May 5, 2022.
Prior Publication US 2023/0308025 A1, Sep. 28, 2023
Int. Cl. H02M 5/458 (2006.01); H02M 1/32 (2007.01); H02P 27/06 (2006.01)
CPC H02M 5/4585 (2013.01) [H02M 1/32 (2013.01); H02P 27/06 (2013.01); F25B 2600/021 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A power conversion device comprising:
a rectification unit that rectifies first alternating current 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 alternating current power, and outputs the second alternating current power, to a load including a motor, the inverter being connected to both ends of the capacitor; and
a control unit that controls operation of only the inverter to output the second alternating current power from the inverter to the load to reduce current flowing to the capacitor, the second alternating current power including a pulsation that depends on a pulsation of power flowing from the rectification unit to the capacitor, wherein
no discharge circuit and no overvoltage protection circuit are provided for the capacitor,
the capacitor has a capacitance greater than or equal to a capacitance of the capacitor that would be set when an overvoltage protection circuit is connected to the capacitor, and
the capacitance of the capacitor is determined by a value calculated using impedance of a reactor disposed in the power conversion device, system impedance, a maximum current value of the commercial power supply, an inductance component for one phase of the motor, a maximum current value of the motor, a withstand voltage of an element to which a voltage from the capacitor is applied, and a maximum voltage of the capacitor in a stationary state.