Circuit and method for motor control

• US 6,531,839 B1
• Filed: 03/22/2000
• Issued: 03/11/2003
• Est. Priority Date: 03/22/1999
• Status: Expired due to Fees

• Current Assignee: Fairchild Korea Semiconductor Limited (ON Semiconductor Corporation)
• Original Assignee: Fairchild Korea Semiconductor Limited (ON Semiconductor Corporation)
• Inventors: Joo, Sung-Jun, Shin, Yong-Sang, Kim, Dong-Gyu
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US09/533,645
• Time in Patent Office: 1,084 Days
• Field of Search: 318/362, 318/371, 318/372, 318/373, 318/375
• US Class Current: 318/371
• CPC Class Codes: H02P 3/04 Means for stopping or slowing by a separate brake, e.g. friction brake or eddy-current brake
• CPC Class Codes: H02P 6/24 Arrangements for stopping

Abstract

Disclosed is an optimized brake method for braking a motor rotating at a high speed. When the motor rotates at the high speed, the present invention reduces the rotation speed of the motor using a mechanical brake method which has a relatively high rate of energy exhaustion, and when the rotation speed of the motor reduces below a predetermined speed, the present invention stops the motor using an electrical brake method. Therefore, since the mechanical brake method is used during the high speed rotation interval, heat occurrence can be prevented, and the electrical brake method is used during the relatively low speed interval so that the motor can be stopped within a short time.

Claims

1. A method for controlling a motor control circuit comprising an inverter, including a first switch unit comprising a plurality of switches coupled between each voltage source and phase of the motor and a second switch unit comprising a plurality of switches coupled between each motor and the ground, and a switching controller controlling on/off operations of each switch of the inverter, the method comprising the steps of:

(a) adjusting switching sequences of the switches of the inverter and adjusting direction of the current flowing to the motor in order for the motor to rotate in the forward direction;

(b) turning off all the switches of the inverter in order for the rotation speed of the motor to reduce by mechanical frictions; and

(c) making, when the reduced speed of the motor is slower than a first speed, the energy supplied to the motor be exhausted through the switches of the inverter whereby all the switches of the first switch unit are turned off and all the switches of the second switch unit are turned on in order to reduce the speed of the motor.

2. The method of claim 1, wherein the step (b) comprises the steps of:

determining whether a brake start control signal is received from the outside; and

turning off all the switches of the inverter when the brake start control signal is received.

3. The method of claim 1, wherein the step (c) comprises the steps of:

computing the rotation speed of the motor;

comparing the computed rotation speed of the motor with a first rotation speed

outputting an electrical brake start signal to the switching controller when the rotation speed of the motor is slower than the first rotation speed; and

controlling the on/off operations of the switches of the inverter responsive to the electrical brake start signal.

4. The method of claim 3, wherein the step of computing the rotation speed of the motor comprises the steps of:

comparing a hall signal from a hall sensor with a reference signal and outputting pulse type signals;

measuring the number of the pulse type signals for a predetermined time; and

computing the rotation speed of the motor using the predetermined time and the number of the pulse type signals.

5. The method of claim 3, wherein the rotation speed of the motor is obtained from information stored in a storage media driven by the motor.

6. A method for controlling a motor control circuit comprising an inverter including a first switch unit comprising a plurality of switches coupled between each voltage source and phase of the motor and a second switch unit comprising a plurality of switches coupled between each motor and the ground, and a switching controller controlling on/off operations of each switch of the inverter, the method comprising the steps of:

(a) adjusting switching sequences of the switches of the inverter and adjusting direction of the current flowing to the motor in order for the motor to rotate in the forward direction;

(b) turning off all the switches of the inverter in order for the rotation speed of the motor to reduce by mechanical frictions; and

(c) making, when a first time is passed after all the switches of the inverter are turned off, the energy supplied to the motor be exhausted through the switches of the inverter whereby all the switches of the first switch unit are turned off and all the switches of the second switch unit are turned on in order to reduce the speed of the motor.

7. The method of claim 6, wherein the step (b) comprises the steps of:

determining whether a brake start control signal is received from the outside; and

turning off all the switches of the inverter when the brake start control signal is received.

8. A motor control circuit comprising:

an inverter including a first switch unit comprising a plurality of switches coupled between each voltage source and phase of the motor and a second switch unit comprising a plurality of switches coupled between each motor and the ground;

a switching controller, when receiving an acceleration signal from the outside, controlling the switching sequences of the switches of the inverter in order for the motor to rotate in the forward direction, and when receiving a brake start control signal from the outside, turning off all the switches of the inverter so that the rotation speed of the motor is reduced by the mechanical frictions; and

an electrical brake determiner outputting an electrical brake start signal to the switching controller when the rotation speed of the motor is slower than a first speed because of the mechanical frictions of the motor,

wherein the switching controller, when receiving the electrical brake start signal from the electrical brake determiner, turns off all the switches of the first switch unit and turns on all the switches of the;

second switch unit whereby the energy supplied to the motor be exhausted through the switches of the inverter so that the speed of the motor is reduced.

9. The circuit of claim 8, the electrical brake determiner comprises:

a speed detector detecting the rotation speed of the motor; and

a speed comparator comparing the detected rotation speed of the motor with the first speed, and when the rotation speed of the motor is slower than the first speed, outputting the electrical brake start signal to the switching controller.

10. The circuit of claim 9, wherein the speed detector comprises:

a comparator comparing a hall signal from a hall sensor with a reference voltage and outputting pulse type signals; and

a counter receiving the output signals of the comparator and counting the number of the pulse type signals, and computing the rotation speed of the motor from the counted pulse type signals and counting time.

11. The circuit of claim 9, wherein the speed detector obtains..the rotation speed of the motor through information stored in a storage media driven by the motor.

12. A motor control circuit comprising:

an inverter including a first switch unit comprising a plurality of switches coupled between each voltage source and phase of the motor and a second switch unit comprising a plurality of switches coupled between each motor and the ground;

switching controller, when receiving an acceleration signal from the outside, controlling the switching sequences of the switches of the inverter in order for the motor to rotate in the forward direction, and when receiving a brake start control signal from the outside, turning off all the switches of the inverter so that the rotation speed of the motor is reduced by the mechanical frictions; and

a timer outputting an electrical brake start signal to the switching controller after a first reference time is passed from a time when the brake start control signal is received,

wherein the switching controller, when receiving the electrical brake start signal from the timer, turns off all the switches of the first switch unit and turns on all the switches of the second switch unit whereby the energy supplied to the motor is exhausted through the switches of the inverter so that the speed of the motor is reduced.

13. A method for controlling a motor control circuit comprising an inverter including a first switch unit comprising a plurality of switches coupled between each voltage source and phase of the motor and a second switch unit comprising a plurality of switches coupled between each motor and the ground, and a switching controller controlling on/off operations of each switch of the inverter, the method comprising the steps of:

(a) adjusting switching sequences of the transistors of the inverter and adjusting direction of the current flowing to the motor in order for the motor to rotate in the forward direction;

(b) adjusting a base current supplied to the transistors of the inverter, and thereby reducing the current flowing to the motor in order for the rotation speed of the motor to reduce by mechanical frictions; and

(c) making, when the reduced speed of the motor is slower than a first speed, the energy supplied to the motor be exhausted through the transistors of the inverter in order to reduce the speed of the motor.

14. The method of claim 13, wherein step (c) is characterized in that all the transistors of the first switch unit are turned off and all the transistors of the second switch unit are turned on so as to reduce the speed of the motor.

15. A method for controlling a motor control circuit comprising an inverter including a first switch unit comprising a plurality of switches coupled between each voltage source and phase of the motor and a second switch unit comprising a plurality of switches coupled between each motor and the ground, and a switching controller controlling on/off operations of each switch of the inverter, the method comprising the steps of:

(a) adjusting switching sequences of the transistors of the inverter and adjusting direction of the current flowing to the motor in order for the motor to rotate in the forward direction;

(b) adjusting a base current supplied to the transistors of the inverter and thereby, reducing the current flowing to the motor in order for the rotation speed of the motor to reduce by mechanical frictions; and

(c) making the energy supplied to the motor be exhausted at the transistors of the inverter after a first time is passed from a time when all the transistors of the inverter are turned off whereby all the transistors of the first switch unit are turned off and all the transistors of the second switch unit are turned on so as to reduce the speed of the motor.