Motor control apparatus and motor control method

• US 8,111,030 B2
• Filed: 09/30/2008
• Issued: 02/07/2012
• Est. Priority Date: 05/23/2008
• Status: Active Grant

• Current Assignee: Delta Electronics Incorporated
• Original Assignee: Delta Electronics Incorporated
• Inventors: Chiu, Chun-Lung, Tsai, Ming-Shi, Kuo, Po-Tsun, Tang, Chung-Hung
• Primary Examiner(s): Benson, Walter
• Assistant Examiner(s): Paul, Antony M
• Application Number:
  US12/241,982
• Publication Number:
  US 20090289585A1
• Time in Patent Office: 1,225 Days
• Field of Search: 318/727, 318/599, 318/811, 318/799, 318/779, 318/400.01, 318/721, 417/22, 417/42, 417/44.1
• US Class Current: 318/599
• CPC Class Codes: H02P 23/02 specially adapted for optimising the efficiency at low load

Abstract

A motor control apparatus and a motor control method determine whether the motor is in a back-pressure area so as to provide different rotation-speed control signals. When the fan is in the low duty cycle, a first circuit loop is switched on, so that the fan has more accurate rotation speed. When the fan is in the high duty cycle, a second circuit loop is switched on, so that the rotation speed of fan does not be limited to a constant rotation-speed as the fan enters the back-pressure area. Thus, the fan has larger airflow quantity and higher airflow pressure.

Claims

1. A motor control apparatus, electrically connected to a motor and receiving a first rotation-speed control signal, comprising:

a phase switching unit electrically connected to the motor for controlling a coil set of the motor to generate magnetization so as to drive a rotor of the motor to rotate;

a sensing unit detecting the coil set of the motor to retrieve a rotation-speed sensing signal and outputting the rotation-speed sensing signal;

a judging unit electrically connected to the sensing unit and having a preset duty cycle value, wherein the judging unit receives the first rotation-speed control signal and the rotation-speed sensing signal, and the judging unit compares the first rotation-speed control signal and the preset duty cycle value so as to decide to switch on a first circuit loop or a second circuit loop;

a rotation-speed weighting unit electrically connected to the judging unit and operating when the second circuit loop is switched on, wherein the rotation-speed weighting unit operates to retrieve the first rotation-speed control signal and the rotation-speed sensing signal from the judging unit and generates a second rotation-speed control signal after calculation; and

a rotation-speed control unit electrically connected to the judging unit, the sensing unit, the rotation-speed weighting unit and the phase switching unit, wherein when the first circuit loop is switched on, the rotation-speed control unit retrieves the first rotation-speed control signal from the judging unit and controls the phase switching unit according to the first rotation-speed control signal to drive the motor to generate magnetization so as to rotate the rotor, and when the second circuit loop is switched on, the rotation-speed control unit retrieves the second rotation-speed control signal from the rotation-speed weighting unit and controls the phase switching unit according to the second rotation-speed control signal to drive the motor to generate magnetization so as to rotate the rotor;

wherein the first circuit loop includes the judging unit, the rotation-speed control unit and the phase switching unit, and the second circuit loop includes the judging unit, the rotation-speed weighting unit, the rotation-speed control unit, the phase switching unit, and the sensing unit.

2. The motor control apparatus according to claim 1, wherein when the first rotation-speed control signal is lower than the preset duty cycle value, the first circuit loop is switched on, and when the first rotation-speed control signal is higher than the preset duty cycle value, the second circuit loop is switched on.

3. The motor control apparatus according to claim 1, wherein the preset duty cycle value is a duty cycle threshold value of a fan entering a back-pressure area.

4. The motor control apparatus according to claim 1, wherein the first rotation-speed control signal and the second rotation-speed control signal are both duty cycle signals.

5. The motor control apparatus according to claim 4, wherein when the first rotation-speed control signal is lower than the preset duty cycle value, the first circuit loop is switched on, and when the first rotation-speed control signal is higher than the preset duty cycle value, the second circuit loop is switched on.

6. The motor control apparatus according to claim 1, wherein the rotation-speed control unit, the rotation-speed weighting unit and the judging unit are integrated as a speed control unit.

7. The motor control apparatus according to claim 1, wherein the rotation-speed control unit is a micro control unit (MCU).

8. The motor control apparatus according to claim 1, wherein the first rotation-speed control signal is inputted from the outside of the motor control apparatus.

9. The motor control apparatus according to claim 1, wherein the phase switching unit is a full-bridge circuit or a half-bridge circuit, the judging unit is comparator, or the rotation-speed control unit is a driver IC.

10. The motor control apparatus according to claim 1, wherein the second rotation-speed control signal is a rotation speed signal of the rotor entering a back-pressure area, or the rotation-speed weighting unit generates the second rotation-speed control signal according to equations of:

T₂=T₁+S

S=(S₁/S_Full)*k

wherein

S_Full is a full speed of the motor;

S₁ represents the rotation-speed sensing signal;

S is a weighted rotation speed;

T₁ represents the first rotation-speed control signal;

T₂ represents the second rotation-speed control signal; and

k is a constant.