Active deceleration circuit for a brushless DC motor
US5793168A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 23, 1996 |
| Grant date | Aug 11, 1998 |
| Priority date | — |
| Expiry date | Aug 23, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P6/24
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A circuit for driving a brushless dc motor includes an active deceleration circuit for rapidly slowing the motor. A phase locked loop senses a position of the rotor for commutating from a drive state to a next drive state in a sequence of drive states at an appropriate time for maintaining torque on the rotor in the direction of rotation. Thus, the rotor "chases" the energized windings. A speed control loop controls current in the windings and, thus, motor speed. When the speed of the motor exceeds a desired speed by more than a threshold amount, rather than commutating to a next drive state in the sequence, the circuit skips a commutation. By skipping one commutation, the current drive state is maintained while the rotor continues to turn, due to its own inertia, such that the rotor "passes up" the current drive state. This results in a torque on the rotor in a direction opposite rotation. When the phase locked loop indicates an appropriate time for commutating to a next drive state, the circuit transitions to the next drive state in the sequence. Therefore, the current drive state continues to remain one commutation behind the normally appropriate drive state, maintaining the rev…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.