Device for controlling rotational speed of electric motor
First Claim
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1. A device for controlling the speed of an electric motor, comprising a chopper connected between a power source and an electric motor;
- an accelerator;
means for detecting the current through said motor;
a controller for controlling the duty ratio of said chopper in accordance with the degree of actuation of said accelerator and said current through said motor and for controlling said current through said motor within a restricted range;
a bypass contacor for connecting said motor directly with said power source by short-circuiting said chopper; and
a bypass contactor control means for opening and closing said bypass contactor so that the contactor will be open whenever the duty ratio of the chopper is below a predetermined maximum value, wherein said bypass contactor control means includes therein a first means for detecting full actuation of said accelerator and a second means for continuously monitoring the duty cycle of the chopper for detecting every time the duty ratio of said chopper equals or exceeds a predetermined maximum value continuously throughout the operation of the motor by detecting every time when the value of the motor current reaches a predetermined value corresponding to the predetermined duty ratio so that said bypass contactor will be closed when said accelerator is actuated to the full extent and when said duty ratio approximately equals said predetermined maximum value, and said bypass contactor will be open whenever said duty ratio of the chopper is below the predetermined maximum value.
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Abstract
A device for controlling the rotational speed of an electric motor, provided with a bypass contactor for short-circuiting a chopper, wherein the bypass contactor is turned on when the accelerator is actuated to the full extent and when the duty ratio of the chopper exceeds a predetermined value, so that the shock due to the turn-on of the bypass contactor is eliminated.
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Citations
8 Claims
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1. A device for controlling the speed of an electric motor, comprising a chopper connected between a power source and an electric motor;
- an accelerator;
means for detecting the current through said motor;
a controller for controlling the duty ratio of said chopper in accordance with the degree of actuation of said accelerator and said current through said motor and for controlling said current through said motor within a restricted range;
a bypass contacor for connecting said motor directly with said power source by short-circuiting said chopper; and
a bypass contactor control means for opening and closing said bypass contactor so that the contactor will be open whenever the duty ratio of the chopper is below a predetermined maximum value, wherein said bypass contactor control means includes therein a first means for detecting full actuation of said accelerator and a second means for continuously monitoring the duty cycle of the chopper for detecting every time the duty ratio of said chopper equals or exceeds a predetermined maximum value continuously throughout the operation of the motor by detecting every time when the value of the motor current reaches a predetermined value corresponding to the predetermined duty ratio so that said bypass contactor will be closed when said accelerator is actuated to the full extent and when said duty ratio approximately equals said predetermined maximum value, and said bypass contactor will be open whenever said duty ratio of the chopper is below the predetermined maximum value. - View Dependent Claims (2, 3, 4)
- an accelerator;
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5. A device for controlling the speed of an electric motor, comprising a chopper connected between a power source and an electric motor;
- an accelerator;
means for detecting the current through said motor;
a controller for controlling the duty ratio of said chopper in accordance with the degree of actuation of said accelerator and said current through said motor and for controlling said current through said motor within a restricted range;
a bypass contactor for connecting said motor directly with said power source by short-circuiting said chopper; and
a bypass contactor control means for opening and closing said bypass contactor, wherein said bypass contactor control means includes therein a first means for detecting the full actuation of said accelerator and a second means for detecting the approximate arrival of the duty ratio of said chopper at a predetermined maximum value by measuring means coupled directly to the motor rotor for detecting a predetermined r.p.m. of the motor corresponding to the predetermined duty ratio and said bypass contactor control means is so constructed that said bypass contactor may be closed when said accelerator is actuated to the full extent and when said duty ratio approximately equals said predetermined maximum value. - View Dependent Claims (6, 7, 8)
- an accelerator;
Specification