Hitachi, Ltd.

Eiji Kozu

Makoto Nohmi

Hiroshi Narita

Hiroshi Yamaguchi

Masahiko Ibamoto

Kiyoshi Nakamura

Takashi Tsuboi

Shigetoshi Okamatsu

Tadashi Takaoka

Syoji Kasai

Tetsuji Hirotsu

Yoshiji Jinbo

The magnitude of current change for the change of input voltage or for the change of speed of rotation of the shunt motor is utilized, i.e., the shunt characteristics are utilized, and the voltage applied to the motor is limited so that the armature current decreases by an amount that corresponds to the increase in the armature voltage when slipping and to the decrease in the armature voltage when sliding have taken place, thereby to obtain improved adhesion characteristics. For this purpose according to the invention, an electromotive force of the motor is calculated from a motor speed detected by a detector and from a field current of the motor, a voltage drop caused by the motor resistance and the motor current is calculated, a motor voltage is calculated by adding the thus calculated voltage drop to the electromotive force of the motor, and the voltage applied to the motor is limited depending upon the calculated motor voltage.

Method and system for controlling chopper

The commencement of a developing period of slip is detected by the fact that a time-differential value v.sub.s of a creep velocity v.sub.s (a relative velocity between a peripheral velocity v.sub.m of a driving wheel and a vehicle velocity v.sub.t) exceeds a predetermined reference .delta..sub.1. The termination of the developing period is detected by the fact that a time-differential value v.sub.m of the peripheral velocity v.sub.m becomes equal to zero. During the developing period, a torque command Tp to a main motor controller is decreased by a re-adhesion control signal Tfa which is formed by the combination of a time-dependent component e.sub.1 and a slip-dependent component e.sub.2. After termination of the developing period, the torque command Tp is decreased with time at an appropriate time constant. According to the present invention, the arithmetic logic operation for control can be much simplified without any deterioration of a adhesion performance of an electric vehicle.

Control apparatus for maintaining traction in electric rolling stock

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 control apparatus is disclosed for an electric car having an induction motor supplied with polyphase AC power of variable frequency from a power converter so as to drive a driving wheel. This control apparatus comprises a detector for detecting the actual running speed of the electric car irrespective of whether the driving wheel causes adhesion or non-adhesion, a device for establishing a slip frequency of the induction motor, and a device for generating a frequency command based upon a signal of the actual running speed and the slip frequency, this frequency command being used to control the output frequency of the power converter.

Control apparatus for electric car

A chopper and a series circuit of a dynamic braking resistor and a thyristor are connected in parallel with a d.c. motor which is operated as a generator during braking operation. A series circuit of a diode and an inductance element is connected in series with the d.c. motor. A condenser connected between the ground and the junction of the inductance element and the diode forms a filter circuit together with the inductance element. Current generated by the d.c. motor flows into a d.c. source through the diode and the inductance element during regenerative braking operation. An over-voltage detector fires the braking thyristor when the voltage across the condenser becomes greater than a predetermined limit value, as a result the dynamic braking operation is performed. A chopper controller varies the interval between an ON pulse to turn the chopper into ON state and an OFF pulse to turn the chopper into OFF state for adjusting ON time and OFF time of the chopper in response to the current through the d.c. motor. An operation changer provides a signal to an automatic phase shifter to extend the interval between the ON and OFF pulses to a predetermined period of time enough to quench the braking thyristor when the braking operation of said d.c. motor is changed from the dynamic braking operation to the regenerative braking operation.

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Katsuta, Japan

Eiji Kozu