Circuit for on-off reluctance motor

Abstract

A switched reluctance machine is energized by phase circuits with four active switches, for example MOSFETs, arranged in a bridge configuration. The switches are capable of conducting current in both a first direction and a second direction and are capable of operating as a diode. The direction of current flow through the phase winding is reversed when changing from motoring to generating and from generating to motoring. The ratings of the switches are set in accordance with the energy supply and energy return currents.

Description

technical field [0001] The present invention relates to circuits for efficient operation of switched reluctance motors, particularly those motors required to operate in a monitoring mode and a generating mode. Background technique [0002] In general, a reluctance motor is one that produces torque by the tendency of its movable parts to move to a position where the reluctance of the magnetic circuit is minimized (ie, the inductance of the excitation winding is maximized). In some forms, circuitry is provided to detect the angular position of the rotor and to energize the phase windings as a function of the position of the rotor. This type of reluctance machine is often called a switched reluctance machine, and it can operate as a motor or a generator. The characteristics of such switched reluctance motors are also well known and described, for example, in "The Characteristics, Design and Application of Switched Reluctance Motors and Drives" by Stephenson and Blake (PCIM '93...

AI Technical Summary

Problems solved by technology

First, the switching timing of the thyristor element is absolutely strict, because the thyristor element needs to be activated at the moment when the corresponding main switch is turned off

Because of the finite switching times associated with the device (typically on the order of 10-20 microseconds, depending on its size), it is very difficult to ensure correct firing all the time

Second, even if the first defect is overcome, the voltage drop across the thyristor element will be greater than the diode it replaces, resulting in greater rather than less device losses

While this achieves the high torque output the authors were after, it is a very expensive solution and requires 8 devices per phase

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