Transistor bridge inverter motor drive having reduced harmonics
US3967173A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 14, 1975 |
| Grant date | Jun 29, 1976 |
| Priority date | — |
| Expiry date | Mar 14, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P27/047
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A harmonic reduced pulse width modulation, variable speed transistor bridge inverter drive controls frequency and magnitude of stator voltage applied to an induction motor so as to maintain constant flux in the motor and permit maximum driving torque to be realized from the motor over a wide speed range. An oscillator generates a train of clock pulses whose frequency is proportional to an analog speed signal, and a three phase generator derives three phase reference waves having periods which include a predetermined number of clock pulses. A resettable volt/hertz integrator derives a train of ramp pulses which are synchronized to the clock pulses and vary in magnitude as a function of the integral of the output voltage from the bridge inverter with respect to time. The constant volt/hertz ramp signals are compared to first and second reference voltages to derive phase-displaced first and second control pulses. The fundamental output voltages of individual phases of the bridge are regulated in accordance with respective three phase reference waves, and pulse width modulating means switch the transistors in the phases of the bridge by two different width pulses whose leading edges ar…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.