MOTOR DRIVING DEVICE AND ELECTRIC EQUIPMENT USING THE SAME

• US 20110279070A1
• Filed: 01/13/2010
• Published: 11/17/2011
• Est. Priority Date: 01/14/2009
• Status: Abandoned Application

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Takeoka, Yoshinori, Tanaka, Hidehisa
• Application Number:
  US13/140,983
• Publication Number:
  US 20110279070A1
• Time in Patent Office: Days
• US Class Current: 318/400.1
• CPC Class Codes: H02P 2203/05 Determination of the rotor position by using two different methods and/or motor models
• CPC Class Codes: H02P 6/181 using different methods depending on the speed
• CPC Class Codes: H02P 6/182 using back-emf in windings
• CPC Class Codes: H02P 6/188 using the voltage difference between the windings H02P6/182 takes precedence

Abstract

Brushless DC motor (4) is driven based on a first or second waveform signal output from operation switching unit (11), which switches output so that a first waveform signal by first waveform generation unit (6) is output when the speed of rotor (4a) is determined to be lower than a predetermined speed, and a second waveform signal by second waveform generation unit (10) is output when the speed of rotor (4a) is determined to be higher than the predetermined speed. Thus, there is provided a motor driving device in which drive is stable even at high speed/under high load, and a driving range is extended.

Claims

1. A motor driving device for driving a brushless DC motor comprising a rotor and a stator having three-phase windings, the motor driving device comprising:

an inverter for supplying electric power to the three-phase windings;

a first waveform generation unit for outputting a first waveform signal that is a waveform having a conduction angle of 120°

or more and 150°

or less;

a current phase detection unit for detecting a phase of a current flowing in the brushless DC motor;

a frequency setting unit for setting a frequency by changing only the frequency while keeping a duty constant;

a second waveform generation unit for outputting a second waveform signal that is a waveform having a predetermined phase relation with respect to the phase of the current flowing in the brushless DC motor, having a frequency set by the frequency setting unit, and having a conduction angle of 120°

or more and less than 180′

;

an operation switching unit for switching output so that the first waveform signal is output when a speed of the rotor is determined to be lower than a predetermined speed, and the second waveform signal is output when the speed of the rotor is determined to be higher than the predetermined speed; and

a drive unit for outputting a drive signal to the inverter indicating a supplying timing of electric power supplied to the three-phase windings based on one of the first and the second waveform signals output from the operation switching unit.

2. The motor driving device of claim 1,

wherein the supplying timing of electric power supplied to the three-phase windings is temporarily corrected for maintaining a predetermined phase relation between the phase of the current and a phase of a terminal voltage of the brushless DC motor.

3. The motor driving device of claim 1,

wherein switching of a winding in the three-phase windings to which the electric power is supplied is carried out at a predetermined timing with reference to the phase of the current of the brushless DC motor.

4. The motor driving device of claim 1,

further comprising a position detection unit for detecting a rotation position of the rotor, wherein the first waveform generation unit outputs a first waveform signal that is a waveform being generated based on position information from the position detection unit.

12. The motor driving device of claim 1,

wherein the rotor of the brushless DC motor comprises a permanent magnet embedded in an iron core, and has saliency.

13. The motor driving device of claim 1,

wherein the brushless DC motor drives a compressor.

14. Electric equipment comprising a brushless DC motor driven by a motor driving device of claim 1.

5. A motor driving device for driving a brushless DC motor comprising a rotor and a stator having three-phase windings, the motor driving device comprising:

an inverter for supplying electric power to the three-phase windings;

a position detection unit for detecting a rotation position of the rotor;

a first waveform generation unit for outputting a first waveform signal that is a waveform having a conduction angle of 120°

or more and 150°

or less based on an output of the position detection unit;

a frequency setting unit for setting a frequency by changing only the frequency while keeping a duty constant;

a second waveform generation unit for outputting a second waveform signal that is a waveform having a conduction angle of 120°

or more and less than 180° and

a frequency set by the frequency setting unit;

a current-voltage state detection unit for detecting a state of a current phase and the second waveform signal output by the second waveform generation unit;

a waveform correction unit for outputting a correction waveform signal that is the second waveform signal corrected so that the state detected by the current-voltage state detection unit is made to agree with a target state;

an operation switching unit for switching output so that the first waveform signal is output when a speed of the rotor is determined to be lower than a predetermined speed, and the correction waveform signal is output when the speed of the rotor is determined to be higher than the predetermined speed;

a drive unit for outputting a drive signal to the inverter indicating a supplying timing of electric power supplied to the three-phase windings based on one of the first waveform signal and the correction waveform signal output from the operation switching unit; and

a protection unit for carrying out the protective control according to the state detected by the current-voltage state detection unit.

6. The motor driving device of claim 5,

wherein the state detected by the current-voltage state detection unit is a time difference or a time ratio per cycle between the current phase and the second waveform signal, and the protection unit has a threshold value and carries out the protective control so that the state detected by the current-voltage state detection unit becomes larger than the threshold value.

7. The motor driving device of claim 5,

wherein the position detection unit detects a position based on a voltage induced by the brushless DC motor, and a timing when a terminal voltage of the brushless DC motor generated due to a return current flowing in the inverter is turned off as being a zero current phase, thereby detecting both the position and the current phase.

8. The motor driving device of claim 5,

wherein operation of the protective control carried out by the protection unit is to reduce a drive speed of the brushless DC motor.

9. The motor driving device of claim 5,

wherein operation of the protective control carried out by the protection unit is to stop the brushless DC motor and to restart driving after a predetermined time.

10. The motor driving device of claim 5,

further comprising an informing unit for informing that the protection unit has carried out operation of the protective control of the brushless DC motor.

11. The motor driving device of claim 5 having function of determining the speed of the rotor to be higher than a predetermined speed when a duty of the first waveform signal output by the first waveform generation unit exceeds a predetermined reference value, and the speed of the rotor to be lower than the predetermined speed when the position of the rotor is detectable by the position detection unit.

15. The motor driving device of claim 5,

wherein the rotor of the brushless DC motor comprises a permanent magnet embedded in an iron core, and has saliency.

16. The motor driving device of claim 5,

wherein the brushless DC motor drives a compressor.