Drive circuit for a brushless motor
US4135120A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 12, 1978 |
| Grant date | Jan 16, 1979 |
| Priority date | — |
| Expiry date | Jan 12, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P6/06
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A drive circuit for a brushless motor of the type having a rotor magnet and energizable stator windings. The drive circuit includes position sensors for sensing the rotary position of the rotor magnet and for generating varying position signals corresponding to the sensed rotary position. A plurality of amplifier stages is coupled to the position sensors, the amplifier stages being responsive to the position signals to produce drive currents which are supplied to the stator windings. In one embodiment, each amplifier stage includes a voltage amplifier having a linear gain characteristic for amplifying the position signal applied thereto, a current amplifier connected in cascade with the voltage amplifier and responsive to the amplified position signal to produce a drive current, and a feedback circuit interconnected between the output of the current amplifier and the input to the voltage amplifier, the feedback circuit including a resistor and a capacitor connected in parallel and operative as a low pass filter circuit to prevent harmonics of the drive current frequency from being transmitted to the stator winding, thereby preventing notching in the drive current. In another embodi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.