PWM, Single-ended, separately driven d.c.-d.c. converter

US4439820A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Willi Kuhn · Markgröningen, DE
• Eberhard Mausner · Ludwigsburg, DE

Key dates

• Filing date: Jan 28, 1982
• Grant date: Mar 27, 1984
• Expiry date: Jan 28, 2002

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02M3/33507
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

The rectified output voltage of the transformer of a d.c. to d.c. converter, as represented by a voltage divider output, is compared with a reference voltage in a voltage regulator (15), the output of which is compared in a comparator (29) with a sawtooth wave to produce a sequence of pulses the duration of which depends upon the output voltage of the regulator. These pulses are provided to the transformer through a driver circuit capable of operating at a very low input voltage. One flank of the square wave produced by a component of the sawtooth wave generator is differentiated by a capacitor (39) to provide transient pulses to the transformer to keep it operating in the event the input voltage to the converter exceeds the output voltage. Another comparator (59) is provided to shut down comparator operation when there is a short circuit at the output and also for a brief start-up interval during which capacitors are charged up.