Hitachi, Ltd.

Tadashi Takaoka

Makoto Nohmi

Shoji Miyamoto

Eiichi Toyota

Shigetoshi Okamatsu

Eiji Kozu

Yoshio Nozaki

Kazuyoshi Kotake

Takeshi Kawazoe

Hiroyasu Oshima

A control apparatus for an electric rolling stock makes it possible to use a single associated train in a variety of transit services including an express transit service to an accommodation train service. The apparatus comprises an induction motor controlled by an inverter. For an express transit operation (over a long inter-station distance), the ratio of output voltage and the frequency of the inverter is decreased to thereby increase a command current in a variable voltage/variable frequency region. For the accommodation train operation (over short inter-station distance), a control pattern reverse to the above is adopted. The electric rolling stock can adapt itself to the running conditions. Besides, the problem of overheating of the induction motor can be solved successfuly.

Control apparatus for induction motor and electric rolling stock

A DC voltage on an electric car stringing is supplied to a variable voltage and variable frequency PWM inverter so as to be converted into a three-phase alternating current which is supplied to a plurality of three-phase induction motors. The motors are connected to different wheels to drive an electric car. The inverter is controlled on the basis of an operating frequency command determined by adding or subtracting a slip frequency command to or from a motor speed and a voltage command proportional to the operating frequency command. On the other hand, a motor current command is set and compared with a maximum current value of currents of the plurality of motors, and the slip frequency command is corrected in accordance with a difference therebetween. In a constant torque region of the electric car, a correction value increasing in proportion to the speed is then added to the motor current command, so that torque of motors other than a motor to which the maximum current flows compensates for a decrease in torque caused as the speed increases to improve constant torque characteristics.

Control system for induction motor driven electric car

A chopper control system for a vehicle driven by a shunt motor. The system is provided with an integrating circuit for generating a command value for the voltage which is to be supplied to an armature of the motor in accordance with the difference between the command value of current which is to be supplied to the armature and the detected value of current flowing through the armature, and with a voltage control circuit for generating a control signal the value of which is proportional to the above command voltage value and is inversely proportional to the power source voltage value. The gate of a chopper switch is on-off controlled by the above control signal, so that the power source voltage value is converted into a voltage value corresponding to the command voltage value and is then supplied to the armature of the motor. By virtue of this arrangement, the armature is supplied with voltage without influence from fluctuations in the power source voltage, and when any wheel slip occurs, the armature current is varied in the direction that causes reduction in the degree of wheel slip.

Chopper control system

A novel control system for the motor or the like is disclosed which operates basically on principle that the power flowing in during the conduction of a chopper gate of a chopper device is integrated, and when the integrated value reaches a target, the gate is turned off, thereby realizing the control of an instantaneous value and high response and stability without the conventional feedback control. The target value is also reduced against the excess of the source voltage under variations in load for the regenerated power. Further, a constant-voltage control limiter is added to improve the ability to prevent a slip and race.

A train operation control apparatus includes a memory for prestoring speed instructions in accordance with the travelled distances of a train and a counter which starts to operate upon train's passing through a predetermined point to count input signals representative of a travel speed of the train. A speed instruction is read out of the memory in response to a content of the counter so that the train follows the speed instruction. Before the operation of the counter is started, a maximum count of the counter is preset so that a minimum speed instruction is read out of the memory at the start of operation, and based on the content thereof a fault of the counter is detected so that a brake instruction is issued to the train.

Growing community of inventors

Ibaraki, Japan

Tadashi Takaoka