Motor driving device and laundry treatment apparatus including the same

Patent metadata

Field	Value
Publication number	US-9973131-B2
Application number	US-201615013817-A
Country	US
Kind code	B2
Filing date	Feb 2, 2016
Priority date	Feb 2, 2015
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

The present disclosure relates to a motor driving device and a laundry treatment apparatus. The motor driving device may include an inverter to convert DC power into AC power according to a switching operation and to output the converted AC power to a motor, an output current detector to detect an output current flowing through the motor, and a controller to control the inverter based on the detected output current. The controller changes a carrier frequency, changes a voltage command based on the changed carrier frequency and outputs an inverter switching control signal to the inverter based on the changed carrier frequency and the changed voltage command. Accordingly, noise may be reduced during operation of the motor.

First claim

What is claimed is:

1. A motor driving device, comprising:
an inverter to convert DC power into AC power according to a switching operation and to output the converted AC power to a motor;
an output current detector to detect an output current flowing through the motor; and
a controller configured to control the inverter based on the detected output current, wherein the controller changes a carrier frequency, changes a voltage command based on the changed carrier frequency and outputs an inverter switching control signal to the inverter based on the changed carrier frequency and the changed voltage command,
wherein the inverter includes upper switching elements and lower switching elements that are respectively paired, and pairs of switching elements are connected in parallel,
wherein during a start-up period of an operation period of the motor, one of the upper switching elements of the inverter is switched on and two lower switching elements, which are not paired with the switched-on upper switching element, are switched on for aligning the motor,
wherein the controller is configured to control a current of a first level and a current of a second level to be sequentially applied to the motor during the start-up period, and wherein the controller changes the carrier frequency during the start-up period, changes the voltage command based on the changed carrier frequency and outputs the inverter switching control signal to the inverter based on the changed carrier frequency and the changed voltage command.

2. The motor driving device of claim 1 , wherein the controller changes a carrier frequency of a triangular waveform, changes a peak level of the triangular waveform and the voltage command based on the changed carrier frequency of the triangular waveform and outputs the inverter switching control signal to the inverter based on the changed carrier frequency and the changed voltage command.

3. The motor driving device of claim 1 , wherein the controller gradually changes the carrier frequency in the range of a first frequency to a second frequency.

4. The motor driving device of claim 1 , wherein the controller comprises:
a carrier frequency converter to change a carrier frequency;
a voltage command generator to generate a voltage command based on the changed carrier frequency; and
a switching control signal output unit to output an inverter switching control signal to the inverter based on the changed carrier frequency and the changed voltage command.

5. The motor driving device of claim 4 , wherein the controller further comprises:
an estimator to estimate a rotor position of the motor based on the detected output current and to calculate a rotor speed; and
a current reference generator to generate a current command based on the calculated rotor speed and a speed command,
wherein the voltage command generator generates the voltage command based on the changed carrier frequency, the current command and the detected output current,
wherein the switching control signal output unit outputs the inverter switching control signal for driving the inverter based on the voltage command.

6. The motor driving device of claim 4 , wherein the switching control signal output unit includes a duty generator to generate a duty based on the changed carrier frequency and the changed voltage command.

7. The motor driving device of claim 1 , further comprising a microphone to collect sound around the motor,
wherein the controller includes:
a frequency extractor to receive collected sound signals from the microphone and to extract frequencies of the received sound signals;
a carrier frequency converter to change a carrier frequency based on a peak level of the extracted frequencies;
a voltage command generator to generate a voltage command based on the changed carrier frequency; and
a switching control signal output unit to output an inverter switching control signal to the inverter based on the changed carrier frequency and the changed voltage command.

8. The motor driving device of claim 7 , wherein the carrier frequency converter changes the carrier frequency based on a frequency at a first level or higher from among the extracted frequencies.

9. A motor driving device, comprising:
an inverter to convert DC power into AC power according to a switching operation and to output the converted AC power to a motor;
an output current detector to detect an output current flowing through the motor; and
a controller is configured to control the inverter based on the detected output current, wherein the controller gradually changes a carrier frequency in a range of a first frequency to a second frequency and outputs an inverter switching control signal to the inverter based on the changed carrier frequency,
wherein the inverter includes upper switching elements and lower switching elements that are respectively paired, and pairs of switching elements are connected in parallel,
wherein during a start-up period of an operation period of the motor, one of the upper switching elements of the inverter is switched on and two lower switching elements, which are not paired with the switched-on upper switching element, are switched on for aligning the motor,
wherein the controller is configured to control a current of a first level and a current of a second level to be sequentially applied to the motor during the start-up period, and
wherein the controller is configured to gradually changes the carrier frequency in the range of the first frequency to the second frequency during the start-up period, changes a voltage command based on the changed carrier frequency and outputs the inverter switching control signal to the inverter based on the changed carrier frequency and the changed voltage command.

10. A laundry treatment apparatus, comprising:
a washing tub;
a motor to rotate the washing tub; and
a motor driver to drive the motor,
wherein the motor driver includes:
an inverter to convert DC power into AC power according to a switching operation and to output the converted AC power to the motor,
an output current detector to detect an output current flowing through the motor, and
a controller is configured to control the inverter based on the detected output current, wherein the controller changes a carrier frequency, changes a voltage command based on the changed carrier frequency and outputs an inverter switching control signal to the inverter based on the changed carrier frequency and the changed voltage command,
wherein the inverter includes upper switching elements and lower switching elements that are respectively paired, and pairs of switching elements are connected in parallel,
wherein during a start-up period of an operation period of the motor, one of the upper switching elements of the inverter is switched on and two lower switching elements, which are not paired with the switched-on upper switching element, are switched on for aligning the motor,
wherein the controller is configured to control a current of a first level and a current of a second level to be sequentially applied to the motor during the start-up period, and
wherein the controller is configured to change the carrier frequency during the start-up period, changes the voltage command based on the changed carrier frequency and outputs the inverter switching control signal to the inverter based on the changed carrier frequency and the changed voltage command.

11. The laundry treatment apparatus of claim 10 , wherein the controller changes a carrier frequency of a triangular waveform, changes a peak level of the triangular waveform and the voltage command based on the changed carrier frequency of the triangular waveform

Assignees

• Lg Electronics Inc

Inventors

• Lee Junho
• Lee Chungill
• Je Jungmoon

Classifications

• H02P21/18

  Estimation of position or speed · CPC title

• H02P27/06 Primary

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• D06F37/304

  Arrangements or adaptations of electric motors · CPC title

• H02P27/085

  wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency · CPC title

• H02P6/28

  Arrangements for controlling current (H02P6/10 takes precedence) · CPC title