US 12,294,324 B2
Motor drive unit and refrigeration cycle apparatus
Masayuki Yoshimura, Fuji (JP); Masaya Nogi, Fuji (JP); Nariya Komazaki, Fuji (JP); and Ken Miura, Fuji (JP)
Assigned to Carrier Japan Corporation, Tokyo (JP)
Filed by Carrier Japan Corporation, Tokyo (JP)
Filed on Sep. 9, 2022, as Appl. No. 17/942,037.
Application 17/942,037 is a continuation of application No. PCT/JP2020/010958, filed on Mar. 12, 2020.
Prior Publication US 2023/0020906 A1, Jan. 19, 2023
Int. Cl. H02P 25/18 (2006.01); F25D 21/00 (2006.01); H02P 27/06 (2006.01)
CPC H02P 25/18 (2013.01) [F25D 21/002 (2013.01); H02P 27/06 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A motor drive unit comprising:
a motor including a plurality of phase windings in a mutually unconnected state;
a first inverter which controls application of electric power to one ends of the phase windings;
a second inverter which controls application of electric power to the other ends of the phase windings;
relays each of which includes a make/break contact connected between the other ends of the phase windings; and
a controller which switches, according to a value of a current flowing through the motor, between an open-windings mode in which the other ends of the phase windings are placed in the unconnected state by opening of the relays, and switching operations of the first and the second inverters are carried out in coordination with each other, and a star-connection mode in which the other ends of the phase windings are connected to each other by closing of the relays, and switching of the first inverter is thereby carried out;
wherein
the controller switches, at the time of the star-connection mode, when the current flowing through the motor rises to a second threshold less than or equal to a rated energizing current of the relay, the star-connection mode to the open-windings mode.
 
6. A refrigeration cycle apparatus comprising the motor drive unit of claim 1, wherein
when executing a defrosting operation of the refrigeration cycle apparatus, the controller sets, irrespective of the current flowing through the motor, the open-windings mode before starting of the defrosting operation, and continues to maintain the set state until the defrosting operation is completed.