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DC Braking of an Induction Motor

IP.com Disclosure Number: IPCOM000049235D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

ONeill, PJ: AUTHOR [+2]

Abstract

A single-phase induction motor is driven in a conventional half bridge configuration with its run winding connected between the junction of two alternately operated power switching transistors in series and the junction of two series capacitors. The run winding is split into two halves connectible in parallel across the bridge for normal running and connectible in series to provide a direct current path for braking current, bypassing the capacitors. A switch is provided to control the connection of the two half windings.

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DC Braking of an Induction Motor

A single-phase induction motor is driven in a conventional half bridge configuration with its run winding connected between the junction of two alternately operated power switching transistors in series and the junction of two series capacitors. The run winding is split into two halves connectible in parallel across the bridge for normal running and connectible in series to provide a direct current path for braking current, bypassing the capacitors. A switch is provided to control the connection of the two half windings.

A specific half bridge circuit is shown in the drawing. The run winding of the motor is constituted by the two windings W1 and W2. For normal running these are connected in parallel across a half bridge circuit by relay contacts comprising switch S1. The half bridge comprises capacitors C1 and C2, on one side, and switching power transistors Q1 and Q2, on the other side. The bridge is supplied with DC from rectified mains. Q1 and Q2 are operated alternately in response to input signals by respective base drive circuits. The base drive circuits are current limiting and sense the current through their respective power transistors by means of resistors R1 and R2. The switch S1 is held closed during normal running of the motor by the full motor drive alternating current flowing through coil W3 of the relay which is a single pole Start Relay.

To brake the motor, Q1 and Q2 are momentarily turned off which removes the cu...