Single coil, direct current permanent magnet brushless motor with voltage boost

• US 6,940,238 B2
• Filed: 11/18/2004
• Issued: 09/06/2005
• Est. Priority Date: 06/12/2003
• Status: Expired due to Term

• Current Assignee: Mcmillan Electric Company
• Original Assignee: Mcmillan Electric Company
• Inventors: Gerfast, Sten R.
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US10/991,908
• Publication Number:
  US 20050122074A1
• Time in Patent Office: 292 Days
• Field of Search: 318/254, 318/138, 318/439, 318/700, 318/701, 318/724, 310/156, 310/156.48, 310/162, 310/165, 310/67.R, 310/68.B, 310/179, 310/180
• US Class Current: 318/400.29
• CPC Class Codes: H02P 6/085 in a bridge configuration

Abstract

A single coil, direct current permanent magnet brushless motor including a stator including six alternately-wound coils connected into a single coil having first and second ends, the oppositely-wound coils forming stator poles, and six magnets of alternating polarity coupled to a rotor and rotatably journaled in the stator. A sensor, such as a dual output Hall sensor, is used for sensing rotation of the rotor. A drive circuit, such as an H-bridge circuit, is coupled to the first and second ends of the single coil to drive the motor. The H-bridge circuit includes two high-side switches for alternately receiving signals from the Hall sensor, and two low-side switches alternately receiving signals from the Hall sensor. A high-side switching signal can be controlled by an inverted low-side switching signal. A voltage boost circuit is also provided, having capacitors to provide a boosted voltage to alternately turn on the high-side switches of the H-bridge. The capacitors can be charged by an unregulated bus voltage.

Claims

1. A single coil, direct current permanent magnet brushless motor, comprising:

an internal rotor including at least four alternate poles;

an external stator with a like number of salient poles, each including alternately wound coils coupled to form a single coil;

a commutated H-bridge including a voltage boost circuit having capacitors providing a boosted voltage to alternately turn on high-side switches of the H-bridge, wherein the capacitors are charged by a low-side switching signal flowing through low-side switches; and

a microcontroller to commutate the H-bridge.

2. The motor of claim 1, wherein the rotor further comprises at least four alternate-polarity magnets that form the at least four alternate poles.

3. The motor of claim 1, wherein the capacitors are charged by an unregulated bus voltage.

4. The motor of claim 1, wherein the rotor includes six alternate poles and the stator includes six coils connected into the single coil.

5. The motor of claim 4, wherein the rotor further comprises at least three magnets that form the six alternate poles.

6. The motor of claim 1, wherein the H-bridge further includes an alternating current conversion circuit including a bridge rectifier and smoothing capacitor coupled to a source of alternating current, the conversion circuit converting the alternating current to provide direct current to power the motor.

7. The motor of claim 1, wherein the motor is configured to be powered by either alternating current or direct current.

8. The motor of claim 1, wherein a uniform concentric air gap is defined between the stator and the rotor.

9. The motor of claim 1, further comprising a module configured to provide locked rotor protection.

10. A method of commutating a single coil, direct current permanent magnet brushless motor including a rotor with at least four poles, a stator with a like number of salient poles each having alternately wound coils coupled to form a single coil with two free ends, a commutated H-bridge including a voltage boost circuit having capacitors providing a boosted voltage, and a microcontroller, the method comprising:

charging the capacitors by a switching current flowing through low-side switches of the H-bridge;

controlling the high-side switches of the H-bridge using an inverted low-side switching signal from the low-side switches of the H-bridge;

turning on the high-side switches of the H-bridge using the charge stored in the capacitors; and

controlling commutation of the H-bridge using the microcontroller.

11. The method of claim 10, further comprising forming the at least four poles of the rotor using at least four alternate-polarity magnets.

12. The method of claim 10, wherein the rotor includes six alternate poles.

13. The method of claim 12, further comprising forming the six alternate poles using at least three magnets.