Control apparatus for electric motor
US5811948A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 2, 1996 |
| Grant date | Sep 22, 1998 |
| Priority date | — |
| Expiry date | Aug 2, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M3/1555
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electric motor has first and second power feed terminals. A power feed line connects a dc power supply and the electric motor. A switching element provided in the power feed line includes a MOS-FET having a gate subjected to a pulse width modulation signal with a controllable duty cycle. The switching element changes between its on state and its off state in response to the pulse width modulation signal. The first power feed terminal of the electric motor is connected to the switching element. A flywheel diode connected in parallel with the electric motor operates to absorb a voltage which appears across the electric motor and returning a current when the switching element changes to its off state. A capacitor connected between the gate of the switching element and the second power feed terminal of the electric motor operates to suppress radio-frequency noise occurring upon every change of the switching element between its on state and its off state.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.