Patent ID: 11874020
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC F  H | IPC F  H

Claim 0:
1. A motor drive apparatus comprising:
a reactor;
a converter including four unidirectional elements that are bridge-connected, the converter being connected to an alternating current power supply via the reactor;
a smoothing capacitor connected between output terminals of the converter;
an inverter converting a direct current voltage output from the smoothing capacitor into an alternating current voltage to be applied to a motor, and outputting the alternating current voltage; and
a physical quantity detection unit detecting a physical quantity representing an operating state on an output side of the converter, wherein
in the converter, two of the four unidirectional elements are connected in series and form a first leg, and remaining two of the unidirectional elements are connected in series and form a second leg,
a switching element is connected in parallel to at least each of two unidirectional elements in the first and second legs connected to a positive side of the smoothing capacitor, two unidirectional elements in the first and second legs connected to a negative side of the smoothing capacitor, the two unidirectional elements in the first leg, or the two unidirectional elements in the second leg,
a plurality of operation modes are included in which conduction of the switching element is controlled such that the converter is operated in different modes of operation,
a synchronous rectification mode of causing, at a timing when a current is caused to flow through the unidirectional element, the current to flow through a channel of a corresponding switching element is included as the operation mode,
at least one of a first switching mode and a second switching mode is included as the operation mode, the first switching mode short-circuiting a power supply voltage, which is a voltage of the alternating current power supply, via the reactor at least once in a half cycle of the power supply voltage, and the second switching mode short-circuiting the power supply voltage a plurality of times via the reactor across one cycle of the power supply voltage,
the operation mode is changed to the synchronous rectification mode when the physical quantity indicates an excessive value during operation in the first switching mode or the second switching mode, and
the operation of the inverter is stopped when a state in which the physical quantity is excessive is not resolved even by changing the operation mode to the synchronous rectification mode.