Motor drive apparatus and refrigeration cycle apparatus

Patent metadata

Field	Value
Publication number	US-10833617-B2
Application number	US-201515545352-A
Country	US
Kind code	B2
Filing date	Apr 13, 2015
Priority date	Apr 13, 2015
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

A motor drive apparatus includes a power converter including an inverter having an upper arm and a lower arm, the inverter being configured to control an operation of an electric motor, and a drive controller configured to apply a dead time for preventing a short circuit between the upper arm and the lower arm, and to control the power converter. The drive controller is configured to control the power converter by switching a first mode in which a first correction value representing a time used to correct a voltage drop due to the dead time is employed to control the power converter, and a second mode in which a second correction value smaller than the first correction value is employed to control the power converter.

First claim

The invention claimed is:

1. A motor drive apparatus comprising:
a power converter including an inverter having an upper arm and a lower arm, the inverter being configured to control an operation of an electric motor;
a drive controller configured to apply a dead time for preventing a short circuit between the upper arm and the lower arm and to control the power converter; and
a voltage detector provided in the power converter and configured to detect a voltage of the power converter,
the drive controller being configured to control the power converter by switching
a first mode in which a first correction value representing a time used to correct a voltage drop due to the dead time is employed to control the power converter, and
a second mode in which a second correction value smaller than the first correction value is employed to control the power converter,

the drive controller being further configured to
enter the first mode,
set an operational frequency of the electric motor,
determine whether the operational frequency of the electric motor is lower than a threshold frequency,
maintain the first mode when the operational frequency of the electric motor is not lower than the threshold frequency, and
switch from the first mode to the second mode when the operation frequency of the electric motor is lower than the threshold frequency,

wherein the dead time is a time period during which the upper arm and the lower arm are both turned off.

2. The motor drive apparatus of claim 1 , wherein the second correction value is set to zero.

3. A refrigeration cycle apparatus comprising:
a refrigerant circuit including a compressor driven by the electric motor, a first heat exchanger, and a second heat exchanger that are connected via a pipe to allow refrigerant to circulate, wherein refrigerant pressure is reduced between the first heat exchanger and the second heat exchanger; and
the motor drive apparatus of claim 1 .

4. The refrigeration cycle apparatus of claim 3 ,
wherein the refrigeration cycle apparatus is configured to perform a defrosting operation for removing frost from the first heat exchanger, and
wherein the drive controller is further configured to
determine whether the refrigeration cycle apparatus is performing the defrost operation, and

switch from the first mode to the second mode, when at least one of conditions that the voltage detected by the voltage detector is equal to or higher than the threshold voltage, that the operation frequency of the electric motor is lower than the threshold frequency, or that the defrosting operation is being performed, is satisfied.

5. The refrigeration cycle apparatus of claim 4 , further comprising:
a suction pressure detector configured to detect a suction pressure of the refrigerant being sucked into the compressor; and
a discharge pressure detector configured to detect a discharge pressure of the refrigerant discharged from the compressor,
wherein the drive controller is further configured to
determine whether the suction pressure of the electric motor is lower than a threshold suction pressure,
determine whether the discharge pressure of the electric motor is lower than a threshold discharge pressure, and
switch from the first mode to the second mode, when at least one of conditions that the voltage detected by the voltage detector is equal to or higher than the threshold voltage, that the operation frequency of the electric motor is lower than the threshold frequency, that the defrosting operation is being performed, that the suction pressure detected by the suction pressure detector is lower than the threshold suction pressure, or that the discharge pressure detected by the discharge pressure detector is lower than the threshold discharge pressure, is satisfied.

Assignees

• Mitsubishi Electric Corp

Inventors

• Nakase Shusaku
• Takata Shigeo

Classifications

• F25B13/00 Primary

  Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02) · CPC title

• H02P23/14 Primary

  Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage · CPC title

• F25B47/025

  by reversing the cycle · CPC title

• F25B2313/006

  two pipes connecting the outdoor side to the indoor side with multiple indoor units · CPC title

• Y02B30/70

  Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating · CPC title