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US 4,345,190 AGranted
Chopper control system
AssigneeHitachi, Ltd.
InventorsMichimasa Horiuchi, Masahiko Ibamoto, Hideaki Rokutan
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AssigneeHitachi, Ltd.
InventorsMichimasa Horiuchi, Masahiko Ibamoto, Hideaki Rokutan
Estimating the term…
A thyristor chopper whose gate signal is controlled by a magnetic phase shifter is connected between a battery and a series motor of an electric vehicle and is short-circuited by a bypass contactor as soon as the duty factor of the chopper attains 100%. In the short-circuited condition of the chopper, the magnetic phase shifter remains idle and does not participate in the control operation although the instruction current and the actual motor current are kept applied to its control windings. Therefore, the level of the output from the magnetic phase shifter is indicative of the value of the actual motor current when the instruction current value is fixed, so that the actual motor current value can be detected by detecting the output level from the magnetic phase shifter. When the actual motor current value is detected to be excessively large, the bypass contactor short-circuiting the chopper is released to decrease the value of the motor current, while when the actual motor current value is detected to be excessively small, a field-weakening contactor is closed to connect a field-weakening resistor in parallel with the field winding of the series motor so as to accelerate the motor by the field-weakening control.
A chopper control system including a battery, a DC series motor for driving an electric vehicle, a shunt resistor, a thyristor chopper, said DC series motor, said shunt resistor and said thyristor chopper being connected in series with said battery, a magnetic phase shifter including a first control winding receiving a current instruction signal instructing the motor current of said motor and a second control winding connected across said shunt resistor for carrying out the gate control of said thyristor chopper, and a first contactor acting to short-circuit said thyristor chopper in response to the attainment of the duty factor of said thyristor chopper at a predetermined setting, said chopper control system comprising means for fixing said current instruction signal at a predetermined level while said thyristor chopper is short-circuited by said first contactor, means for releasing said first contactor in response to the detection of the fact that the value of the motor current represented by the level of the output from said magnetic phase shifter exceeds a first predetermined setting while said fixing means is in operation, and a second contactor for connecting a resistor in parallel with the field winding of said DC series motor in response to the detection of the fact that the value of the motor current represented by the level of the output from said magnetic phase shifter decreases to less than a second predetermined setting while said fixing means is in operation.
A chopper control system for use with a DC motor having a series field winding and connected in series with a shunt resistor, a thyristor chopper and a DC power source;
Dependencies are inferred from the claim text.