# US 2014/0197772 A1 · Motor control device for switching pwm frequency to use the same

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2014/0197772 A1
- Document ID: US20140197772A1
- Status: Published application
- Kind: A1
- Application number: 14/045,586
- Filed: 2013-10-03
- Published: 2014-07-17
- Earliest claimed: 2012-10-04
- Assignees: Fanuc Corporation
- Applicants: Fanuc Corporation
- Inventors: Yuuki Morita; Daisuke Tajima
- Web page: https://patentgrep.com/patent/US20140197772A1

## CPC

- H02P 27/08: with pulse width modulation
- H02P 29/60: Controlling or determining the temperature of the motor or of the drive (H02P29/02 takes precedence)
- H02P 29/68: based on the temperature of a drive component or a semiconductor component
- H02P 2209/13: Different type of waveforms depending on the mode of operation
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## Abstract

A motor control device includes an inverter, a power device temperature obtaining unit, a motor temperature obtaining unit, a power device temperature determination level storage unit, a motor temperature determination level storage unit, a PWM frequency storage unit that stores at least two PWM frequencies including a high PWM frequency a low PWM frequency, a power device temperature determining unit that determines whether or not a temperature of a power device is equal to or higher than a power device temperature determination level, a motor temperature determining unit that determines whether or not a temperature of a motor is equal to or higher than the motor temperature determination level, and a PWM frequency selecting unit that selects a PWM frequency to be given as a command to the inverter.

## Claims

### Claim 1

A motor control device comprising:
an inverter that inverts DC voltage into AC voltage at a specified PWM frequency by PWM control using a power device to apply the AC voltage to a motor;
a power device temperature obtaining unit that obtains a temperature of the power device of the inverter;
a motor temperature obtaining unit that obtains a temperature of the motor;
a power device temperature determination level storage unit that stores a power device temperature determination level;
a motor temperature determination level storage unit that stores a motor temperature determination level;
a PWM frequency storage unit that stores at least two PWM frequencies including a high PWM frequency higher than the specified PWM frequency, and a low PWM frequency lower than the specified PWM frequency;
a power device temperature determining unit that determines whether or not the temperature of the power device is equal to or higher than the power device temperature determination level;
a motor temperature determining unit that determines whether or not the temperature of the motor is equal to or higher than the motor temperature determination level; and
a PWM frequency selecting unit that selects a PWM frequency to be given as a command to the inverter, from the specified PWM frequency and the at least two frequencies on the basis of determination results of the power device temperature determining unit and the motor temperature determining unit.

### Claim 2 (depends on 1)

The motor control device according to claim 1, wherein when the temperature of the power device is lower than the power device temperature determination level, and the temperature of the motor is lower than the motor temperature determination level, the PWM frequency selecting unit selects the specified PWM frequency as the PWM frequency to be given as the command to the inverter.

### Claim 3 (depends on 1)

The motor control device according to claim 1, wherein when the temperature of the power device is lower than the power device temperature determination level, and the temperature of the motor is equal to or higher than the motor temperature determination level, the PWM frequency selecting unit selects the high PWM frequency as the PWM frequency to be given as the command to the inverter.

### Claim 4 (depends on 1)

The motor control device according to claim 1, wherein when the temperature of the power device is equal to or higher than the power device temperature determination level, and the temperature of the motor is lower than the motor temperature determination level, the PWM frequency selecting unit selects the low PWM frequency as the PWM frequency to be given as the command to the inverter.

### Claim 5 (depends on 1)

The motor control device according to claim 1, wherein when the temperature of the power device is equal to or higher than the power device temperature determination level, and the temperature of the motor is equal to or higher than the motor temperature determination level, the PWM frequency selecting unit selects the specified PWM frequency as the PWM frequency to be given as the command to the inverter, and creates a signal for generating a warning.

### Claim 6 (depends on 1)

The motor control device according to claim 1, further comprising:
a power device temperature overheat determination level storage unit that stores a power device temperature overheat determination level;
a motor temperature overheat determination level storage unit that stores a motor temperature overheat determination level;
a power device temperature overheat determining unit that determines whether or not the temperature of the power device is equal to or higher than the power device temperature overheat determination level; and
a motor temperature overheat determining unit that determines whether or not the temperature of the motor is equal to or higher than the motor temperature overheat determination level,
wherein on the basis of determination results of the power device temperature overheat determining unit and the motor temperature overheat determining unit, the PWM frequency selecting unit stops giving, to the inverter, the command for PWM frequency setting when the temperature of the power device is equal to or higher than the power device temperature overheat determination level, or when the temperature of the motor temperature is equal to or higher than the motor temperature overheat determination level.

### Claim 7 (depends on 5)

The motor control device according to claim 5, further comprising:
a first difference calculating unit that calculates a power device temperature difference that is a difference between the temperature of the power device and the power device temperature determination level; and
a second difference calculating unit that calculates a motor temperature difference that is a difference between the temperature of the motor and the motor temperature determination level,
wherein when the power device temperature difference is equal to or higher than the motor temperature difference, the PWM frequency selecting unit selects the low PWM frequency, and when the power device temperature difference is lower than the motor temperature difference, the PWM frequency selecting unit selects the high PWM frequency.