Control apparatus for controlling transistor chopper for use in current supply for electric motor
AssigneeHitachi, Ltd.
InventorsKatsuji Marumoto, Tsutcmu Ohmae
Life of this patent
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Abstract
A control apparatus for controlling the supply of current for an electric motor, having a transistor chopper circuit which includes a plurality of power transistors connected in parallel, and a duty controlling oscillator circuit for controlling the ON-OFF operation of the transistor chopper circuit, by which the duty factor of current supplied for the motor through the transistor chopper circuit is controlled depending on a command signal, and wherein the operation of the duty controlling oscillator circuit is controlled depending on the amplitude of current flowing through one of the plurality of power transistors of the transistor chopper circuit.
Claims21
A control apparatus for controlling the supply of current for an electric motor, comprising a source for supplying direct current to the motor;
- transistor chopper circuit means, including a plurality of power switching transistors connected in parallel, which is series connected with said direct current source for controlling the current to be supplied to the electric motor;
- means for producing a command signal representing the desired speed of said motor;
- duty controlling oscillator circuit means for generating an output signal on the basis of the command signal from said command signal producing means, by which the duty factor of the current supplied for the electric motor via said transistor chopper circuit means is determined by controlling the ON-OFF operation of said transistor chopper circuit means on the basis of said output signal;
- means connected to a preselected one of said plurality of power transistors for detecting the amplitude of current flowing therethrough;
- and limiter circuit means for controlling said duty controlling oscillator circuit means in response to the output from said current detecting means, whereby the duty factor of the current supplied for the electric motor is regulated in dependence on the amplitude of the current flowing through said preselected one of said plurality of power transistors of said chopper circuit means.
In a control apparatus for controlling the supply of current from a direct current source to an electric motor by means of a chopper circuit including a plurality of power switching transistors connected in parallel and a duty controlling oscillator circuit means responsive to a command signal representing the desired speed of said motor for generating an output signal by which the duty factor of said chopper circuit is controlled, the improvement comprising detecting means connected to a preselected one of said plurality of power transistors for detecting the amplitude of current flowing therethrough, and control circuit means responsive to said detecting means for regulating said command signal which is supplied to said duty controlling oscillator circuit means.
Dependencies are inferred from the claim text.