Motor driving device and air conditioner including the same

Patent metadata

Field	Value
Publication number	US-9732991-B2
Application number	US-201414582905-A
Country	US
Kind code	B2
Filing date	Dec 24, 2014
Priority date	Dec 24, 2013
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A motor driving device includes a rectifier to rectify inputted alternating current (AC) power, a boost converter to boost and to output the power rectified by the rectifier, and an inverter including a plurality of switching devices to output converted AC power to a motor using a voltage from the boost converter. Accordingly, a voltage utilization ratio of a voltage input to an inverter in the motor driving device using a low-capacitance capacitor is enhanced.

First claim

What is claimed is:

1. A motor driving device comprising:
a rectifier to rectify inputted alternating current (AC) power;
a boost converter to boost and to output the power rectified by the rectifier;
an inverter comprising a plurality of switching devices to output converted AC power to a motor using a voltage from the boost converter;
a capacitor disposed between the boost converter and the inverter to store a ripple voltage outputted from the boost converter; and
an inverter controller to control the inverter to operate in a first mode in which a peak value of three-phase current flowing in the motor is constant when inverter power for driving the motor is less than reference power, and to control the inverter to operate in a second mode in which a ripple frequency of the peak value of the three-phase current flowing in the motor is twice a frequency of the input AC power when the inverter power is the reference power or more,
wherein, in the first mode, the peak value of three-phase current flowing in the motor has a first level higher than zero value,
wherein, in the second mode, the peak value of three-phase current flowing in the motor is not constant.

2. The motor driving device according to claim 1 , further comprising:
a converter controller to control the boost converter to reduce a peak value of the ripple voltage using a higher harmonic compared with a fundamental wave of an input voltage, the higher harmonic corresponding to a phase of the input voltage.

3. The motor driving device according to claim 2 , wherein the converter controller comprises:
a current command generator to generate a higher harmonic generated to correspond to the phase of the input voltage and to generate a current command value using the generated higher harmonic;
a voltage command generator to generate a voltage command value based on input current corresponding to the input AC power and the current command value; and
a switching control signal output unit to output the converter switching control signal based on the voltage command value.

4. The motor driving device according to claim 3 , wherein the current command generator comprises:
a voltage controller to perform voltage control based on the ripple voltage; and
a higher harmonic generator to generate the higher harmonics corresponding to the phase of the input voltage.

5. The motor driving device according to claim 2 , wherein the converter controller generates a second order higher harmonic and a third order higher harmonic compared with the fundamental wave of the input voltage.

6. The motor driving device according to claim 5 , wherein the converter controller generates the second order higher harmonic and the third order higher harmonic so as to increase coefficients of the second order higher harmonic and the third order higher harmonic in order to reduce the peak value of the ripple value.

7. The motor driving device according to claim 4 , wherein the voltage controller generates the voltage command value based on a root mean square (RMS) of the ripple voltage and the ripple voltage command value.

8. The motor driving device according to claim 4 , wherein:
the converter controller further comprises a ripple voltage compensator to compensate for the ripple voltage to output a ripple voltage compensation value; and
the converter controller outputs the converter switching control signal based on the voltage command value and the ripple voltage compensation value.

9. The motor driving device according to claim 1 ,
wherein, in the second mode, the peak value of three-phase current flowing in the motor tracks the ripple voltage of the capacitor.

10. The motor driving device according to claim 1 , wherein:
the inverter controller controls the inverter based on an average power command value of the inverter power in a first mode period; and
the inverter controller controls the inverter based on an instantaneous power command value of the inverter power in a second mode period.

11. The motor driving device according to claim 10 , wherein:
the inverter controller calculates a size of the instantaneous power command value based on the average power command value and the reference power; and
the inverter controller calculates or detects a phase of the instantaneous power command value compared with a ripple voltage or input power based on the input AC power.

12. The motor driving device according to claim 11 , wherein the phase of the instantaneous power command value is reduced as an average power value of the inverter power or a size of the inverter power is increased.

13. The motor driving device according to claim 10 , wherein the inverter controller comprises:
a torque command generator to generate a torque command value based on a speed command value;
a current command generator to generate a current command value based on the torque command value;
a voltage command generator to generate a voltage command value based on the current command value;
a power command generator to generate the instantaneous power command value;
a power controller to generate a compensation voltage command value based on the instantaneous power command value; and
a switching control signal output unit to output a switching control signal based on the voltage command value and the compensation voltage command value.

14. An air conditioner comprising:
a compressor to compress refrigerant;
a heat exchanger to perform heat exchange using the compressed refrigerant; and a compressor motor driving device to drive a motor in the compressor,
wherein the compressor motor driving device comprises:
a rectifier to rectify inputted alternating current (AC) power;
a boost converter to boost and to output the power rectified by the rectifier;
an inverter comprising a plurality of switching devices to output converted AC power to the motor using a voltage from the boost converter;
a capacitor disposed between the boost converter and the inverter to store a ripple voltage outputted from the boost converter; and
an inverter controller to control the inverter to operate in a first mode in which a peak value of three-phase current flowing in the motor is constant when inverter power for driving the motor is less than reference power, and to control the inverter to operate in a second mode in which a ripple frequency of the peak value of the three-phase current flowing in the motor is twice a frequency of the input AC power when the inverter power is the reference power or more,
wherein, in the first mode, the peak value of three-phase current flowing in the motor has a first level higher than zero value,
wherein, in the second mode, the peak value of three-phase current flowing in the motor is not constant.

Assignees

• Lg Electronics Inc

Inventors

• An Joonsik
• Kim Sangyoung
• Park Taeyoung
• Kim Kyungmin

Classifications

• H02M1/4225 Primary

  using a non-isolated boost converter · CPC title

• H02P6/28

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

• F25B1/005 Primary

  of the single unit type (F25B1/10 takes precedence) · CPC title

• H02M5/44

  using discharge tubes or semiconductor devices to convert the intermediate DC into AC · CPC title

• Y02B70/126

  Cross-Sectional Technologies · mapped topic