Digital pulse-width-modulation generator for current control
US5079498A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 26, 1991 |
| Grant date | Jan 7, 1992 |
| Priority date | — |
| Expiry date | Mar 26, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M3/157
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The circuit provides digital control of current in an inductive load. A switching circuit generates a square wave PWM voltage drive to the load, and the current is sensed by sensor. This current is fed back as signal, which is compared with two zone boundary signals. The switching state is changed between ON and OFF accordingly. The boundary signals are generated by adding and subtracting (by adder/subtractor) a half-zone-width signal (stored as digital data) in a zone width store with the signal. The zone position may be moved slightly up and down, under control of a counter driven by the ON/OFF signal, to produce dither. The zone width may be selected in dependence on the input signal to reduce ripple at low signal, and to adjust the frequency. The switching circuitry may have multiple power supplies, and/or means for changing the connection of the load to the power supply to modify the rate of change of current and the direction of current in the load. A separate analogue input may be summed with the feedback signal or the D/A output to modify the current magnitude or replace the input signal as the main input signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.