Hitachi, Ltd.

Hitachi Automotive Engineering Co., Ltd.

Tsutomu Omae

Katsuji Marumoto

Toshihiko Matsuda

Shotaro Naito

Hiroshi Kimura

Toshiaki Okuyama

Kazuo Tahara

Sanshiro Obara

Masahiko Watanabe

Kenji Kubo

Toshimi Abukawa

Mitsuyuki Hombu

Hisatugu Ishikura

Toshiyuki Koterazawa

Toru Tatsuzaki

Shuichi Takamatsu

Takaichi Koyama

Keiziro Sakai

Ryoso Masaki

Takanori Shibata

Nobuyoshi Mutoh

Hirohisa Yamamura

Taro Iwamoto

Masahiro Tobise

Tomio Iizuka

Sho Kusumoto

Makoto Tachikawa

Shimon Ando

Kazuhiro Yoshida

Toshitaka Suzuki

Kenzo Kamiyama

Hiroyuki Hanei

Takeshi Hanada

Takashi Sukegawa

Hiroshisa Yamamura

Schigeru Kuriyama

Tosihiko Matuta

Masatake Takidera

Kunio Hamada

Youjirou Miyahara

An object of the present invention is to secure safe driving of electric vehicles by enabling torque control regardless of sensor disorder. In the present invention, the mode of current sensor disorder is detected by a sensor disorder detection means. If it is found as a result that only 1 out of 3 current sensors is failing, the current of the failing current sensor is estimated by 2 normal current sensors and the torque control of the motor is continued by the ordinary torque control system. If 2 or more current sensors are found to be failing, a torque control system based on an AC current reference operation means is formed to control the motor torque based on the AC current reference. If a sensor failure detection means determines that only 1 phase is failing in the speed sensor, the motor torque is controlled by using the remaining 1 phase to detect the rotating angular speed of the motor. If all speed sensors are failing but the current sensors are normal, the motor torque is controlled by estimating the motor torque from the 3 phase AC current. If both the current sensors and the speed sensors are found to be failing, the motor torque is controlled based on the estimated torque control and rotating angular speed to continue the driving that is needed to avoid dangerous situations.

Failure detection method for electric vehicles and fail-safe control

A generator generates two voltage outputs which have different voltage levels. One voltage output from the generator is used for operating a power steering apparatus. Another voltage output from the generator is used for charging a battery which supplies current to other loads.

Motor-driven power steering apparatus

In a speed detecting apparatus for detecting the rotational speed of a rotating body mechanically coupled thereto, an encoder generates one cycle of a sine-wave signal each time its angular position of rotation changes by a predetermined unit amount. A zero-crossing pulse is generated at each zero-crossing point of the sine-wave signal generated from the encoder, and the phase angle of the sine-wave signal is detected on the basis of the zero-crossing point of the sine-wave signal generated from the encoder. In a high speed range, the rotational speed is detected on the basis of the ratio between the number of zero-crossing pulses and the time interval between a first one and a last one of the plural zero-crossing pulses. On the other hand, in a low speed range, the rotational speed is detected on the basis of the combination of the number of the zero-crossing pulses appearing within a predetermined period of time and the phase angle of the sine-wave signal.

Speed detecting apparatus

A speed control apparatus for a motor comprising a motor model formed of a motor current model and a motor speed model connected in cascade, a basic torque instruction signal being applied to the motor model, and first and second control loops comparing output signals from the motor current model and the motor speed model with an instantaneous actual motor current signal and an instantaneous actual motor speed signal respectively and generating first and second correction signal to be added to the basic torque instruction signal to form a corrected torque instruction signal which is applied to a motor current control circuit, whereby a speed oscillation is suppressed even when the motor is driving an oscillatory load.

Speed control apparatus for motor

A PWM inverter includes a plurality of arms connected in parallel with a d.c. power source. Each arm is constituted by an upper arm and a lower arm each having a switching element. A plurality of switching control signals are continuously and alternately applied to one and the other of the two switching elements constituting the same arm respectively. In the PWM inverter, shunt resistors are connected between a minus terminal of the d.c. power source and the lower arms respectively. The PWM inverter further comprises a waveform command generating circuit generating commands representative of current waveforms to be supplied to a load, a carrier wave generating circuit and sample-hold circuits. Each of the sample-hold circuits samples and holds a terminal voltage of the associated shunt resistor in synchronism with the period of the carrier wave generated from the carrier wave generating circuit and at specific timing in a conduction period of the associated switching element.

Load current detecting device for pulse width modulation inverter

An electric power assistance steering apparatus provides a differential compensating circuit (54) in which a command current signal is added with a derivative of the command signal to provide a compensated current signal to a control circuit for varying the current to an electric motor (11) arranged to provide power assistance to a steering rack (6). The apparatus preferbly provides signals representative of torque and vehicle speed to a function generator to provide a first command signal which is added with a self-centering command current and the output is provided to give a second command current which is effectively the first command current limited in dependence upon the vehicle speed. The second command current is operated upon by the differential compensating circuit (54) to the compensated current signal.

Electric power steering apparatus

A digital servo-control system used for driving a machine with a plurality of drive shafts having a digital type multi-axis position control unit, provided in common to all of the drive shafts, for computing a torque command value for each drive shaft on the basis of a position detection value detected by a position detector provided for each drive shaft and a position command value for each drive shaft, and torque control units, respectively provided in correspondence to a plurality of motors adapted to drive the respective drive shafts, for controlling output torque of a corresponding motor in accordance with the computed torque command value.

Digital servo-control system

A chopper controller for a D.C. motor controls currents flowing in an armature winding and a field winding of the D.C. motor by controlling an armature chopper and a field chopper in accordance with a command from a command generator such as an accelerator pedal. The armature chopper and the field chopper are controlled by chopper control signals from an armature chopper control circuit and a field chopper control circuit, respectively. Those chopper control signals are in a predetermined phase relationship and an interruption request signal is issued in phase-synchronism with one of the chopper control signals. In response to the interruption request signal, computing means computes an armature chopper duty factor and a field chopper duty factor in accordance with the command from the command generator and supplies them to the chopper control circuits.

Chopper controller for a D.C. motor

A load DC motor is supplied with a DC current through a converter principally consisting of thyristors controlled by an ON-state control signal. The load current is detected both as to the mean value and the variation in time thereof. The mean value of the load current is calculated based on the load current values detected at the time of the present On-signal and the preceding ON-signal. The difference between the reference value and the mean value of the load current is calculated, and the difference between this differential signal and the variation of the load current is further calculated, so that the timing for providing the ON-signal is calculated based on the resultant differential signal.

Method and apparatus for controlling load current

A control device for an electromobile provided with a shunt motor includes a pattern generating means for storing, as patterns, armature and field currents capable of generating an output torque with a minimum loss in the driving system of the electromobile to deliver an armature current command and a field current command for generating a specified output torque on the basis of the patterns, an armature control circuit for supplying the shunt motor with an armature current corresponding to the armature current command, and a field control circuit for supplying the shunt motor with a field current corresponding to the field current command. Thus, the torque control of the shunt motor is conducted on the basis of the patterns, and a computer control is applicable to the above control device.

Electromobile control device

A digital control system for controlling firing pulses supplied to thyristors for power conversion to desired phases, wherein data necessary for obtaining desired phase control signals is set in a counter which normally counts clock pulses having a predetermined period and the firing pulses are generated in synchronism with the generation of overflow pulses from the counter. The data setting to the counter, which is repeated at a period shorter than that of the source voltage, is performed by reading out the actual count value of the counter by a digital arithmetic processor circuit, by correcting the read value by the use of the value corresponding to a desired phase and by setting the corrected value again in the counter.

Method and apparatus for controlling firing phases of thyristors

In a method and a system for inspection of the inside of a nuclear reactor vessel in which an inspection device for inspecting a defect in a nuclear reactor vessel is so moved by a drive/control device as to permit inspection of a part to be inspected in the reactor vessel, and the presence or absence of defect in the reactor vessel is judged based upon information from the inspection device in the course of the above-mentioned movement of the inspection device; the movement of the inspection device is pursued and monitored by monitor means, and the movement of the inspection device is suppressed when an abnormality in the movement of the inspection device is judged based upon information from the monitor means, to avoid the abnormal movement.

Method and system for inspection of inside of nuclear reactor vessel

The firing phase of the power converter which can change power to be supplied to a load is determined by the firing angle instruction produced from the current control circuit in accordance with the magnitude of the current difference between the current target value and the current actual value flowing through the load. The nonlinear compensating circuit produces a correction angle instruction predetermined in accordance with the magnitude of the current actual value in the current intermittent region in which the load current becomes intermittent. In the current intermittent region, the sum of the firing angle instruction from the current control circuit and the correction angle instruction is used to determine the firing phase of the power converter and thereby to compensate for nonlinear response. The nonlinear compensation in the current intermittent region is made only in the transient state when the difference between the current target value and the current actual value exceeds a preset value. Thus, the stability at the steady state condition in the current intermittent region can be increased.

Controller for power converter

A control circuit for controlling supply of current for electric motor has a chopper circuit connected with a battery in series. The chopper circuit is constructed with such as power transistors or power thyristors, and the ON-OFF operation thereof is controlled by a driving pulse. A command signal is produced at a movable tap of a potentiometer, across which a D-C control voltage from the battery is applied. In order to determine the duty and the control frequency of the chopper circuit, a duty controlling oscillator circuit is provided, which generates an output signal on the basis of the command signal from the potentiometer. The duty controlling oscillator circuit includes an integrator composed of an operational amplifier having a negative feedback of a condenser, to the -input terminal of which the command signal is applied. Another operational amplifier having a positive feedback of a resistor operates as a hysteresis comparator, to the +input terminal of which is applied the output from the integrator and to the -one of which a divided reference of the D-C control voltage. In response to the output signal from the hysteresis comparator, a driving pulse generator produces a driving pulse to the chopper circuit.

Control circuit for use in control of current supply for electric motor

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Hitachi, Japan

Tsutomu Omae