DC motor speed controller having protection
US4851743A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 27, 1987 |
| Grant date | Jul 25, 1989 |
| Priority date | — |
| Expiry date | Oct 27, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S388/937
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A controller for a battery-driven DC motor controls the average motor current by switching a series-connected FET on and off with a pulse-width-modulated gate signal. Motor speed is changed by changing the duty cycle of the signal, which is generated by an oscillator. An undervoltage protection circuit senses the battery voltage and compares it with a reference system that has hysteresis. An overload protection circuit senses the motor current, integrates the sensed signal, and compares the result with a Zener reference diode that is connected in an amplifier circuit for positive feedback. The oscillator's pulse-width-modulated output, the undervoltage protection circuit's output, and the overload protection circuit's output are input to a "NOR" logic gate, whose output drives the gate of the FET.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.