Dual current-limiting circuit for DC brushless motor

• US 20040000883A1
• Filed: 06/28/2002
• Published: 01/01/2004
• Est. Priority Date: 06/28/2002
• Status: Active Grant

• Current Assignee: Sunonwealth Electric Machine Industry Company Limited
• Original Assignee: Sunonwealth Electric Machine Industry Company Limited
• Inventors: Ko, Ta-Lun, Hung, Yin-Rong, Alex, Horng, Lu, Ying-Ya
• Granted Patent: US 6,741,047 B2
• Time in Patent Office: Days
• US Class Current: 318/400.22
• CPC Class Codes: H02P 25/03 with brushless excitation
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36

Abstract

The dual current-limiting circuit for dc brushless motor includes an over-current detective circuit, an operation detective circuit, and a current-limiting circuit. The over-current detective circuit produces a voltage signal being used to determine whether the motor has been input over current. The operation detective circuit also produces a voltage signal being used to determine whether the motor is operated in normal. The current-limiting circuit decides to turn on a first switch of a first current-limiting circuit and to subsequently turn on a second switch of a second current-limiting circuit depending upon the two voltage signals. The current-limiting circuit is capable of suppressing current passing through a coil at low voltage level, which is inadequate to damage a driver circuit and still adequate to restart the motor if the great abnormal input current is eliminated.

Claims

1. A dual current-limiting circuit for a dc brushless motor comprising:

an over-current detective circuit being adapted to produce a first voltage signal which used to determine whether the motor is input over current or not;

an operation detective circuit being adapted to produce a second voltage signal which used to determine whether the motor is operated normal or not; and

a current-limiting circuit being adapted to decide turning on a first limit stage for initially limiting current and subsequently turning on a second limit stage for successively limiting current depending upon the first and second voltage signals, thereby limiting current passing through a coil of the motor at low voltage level which is inadequate to damage a driver circuit of the motor.

2. The dual current-limiting circuit for a dc brushless motor as defined in claim 1, wherein the driver circuit comprises a Hall voltage amplifier circuit, a phase inverter circuit, and a motor coil driver circuit.

3. The dual current-limiting circuit for a dc brushless motor as defined in claim 2, wherein the over-current detective circuit retrieves voltage of the motor coil driver circuit and then outputs a reference voltage level.

4. The dual current-limiting circuit for a dc brushless motor as defined in claim 2, wherein the operation detective circuit retrieves alternative signal of the Hall voltage amplifier circuit and then outputs a reference voltage level.

5. The dual current-limiting circuit for a dc brushless motor as defined in claim 2, wherein the circuit-limiting circuit outputs signal to the phase inverter circuit via an electronic switch element, thereby controlling the phase inverter circuit outputting to the motor coil driver circuit.

6. The dual current-limiting circuit for a dc brushless motor as defined in claim 2, wherein the motor coil driver circuit comprises four complementary bridge transistors.

7. The dual current-limiting circuit for a dc brushless motor as defined in claim 6, wherein the motor coil driver circuit is applied to a single phase motor.

8. The dual current-limiting circuit for a dc brushless motor as defined in claim 2, wherein during abnormal operation the over-current detective circuit operates in the first limit stage and outputs terminating signal to the current-limiting circuit, so as to changing to the second limit stage for successively limiting current at low voltage level which is inadequate to damage the driver circuit and still adequate to restart the motor until abnormal conditions is eliminated.