Mitsubishi Denki Kabushiki Kaisha

Diamond&zebra Electric Mfg.co., Ltd.

Hidehiko Sugimoto

Shinzo Tamai

Shunichi Wada

Yoshihiko Utsui

Yushin Yamamoto

Takao Kawabata

Osamu Takahashi

Yasuyuki Sohara

Hideki Tsuruse

Masahiro Tado

Takeshi Miyashita

Akira Saitou

Seigou Tsukada

Yoshimoto Tamura

An improved support apparatus such as a suspension apparatus for a vehicle is disclosed which has excellent response characteristics, can save power consumption and has excellent vibration-isolating capacity for isolating the transmission of high-frequency vibrations from a support member such as a road wheel to an object such as the body of a vehicle. To these end, in one embodiment, a linear motor is disposed between the object and the support member for telescopically supporting the object under magnetic effects. A position sensor senses the position of the object relative to a reference position. A low-pass filter filters high-frequency components of the output signal of the position sensor above a prescribed upper frequency limit. Based on the output signals of the position sensor and the low-pass filter, the current supply to the linear motor is controlled in such a manner as to offset a change in the output signal of the low-pass filter. In another embodiment, an elastic member is further disposed between the object and the support member in parallel with the linear motor for elastically supporting the object on the support member. A high-pass filter filters low-frequency components of the output signal of the position sensor below a prescribed lower frequency limit. Based on the output signal of the high-pass filter, a correction is calculated for offsetting a change in the operating force of the elastic member. The current supply to the linear motor is controlled based on a change in the output signal of the low-pass filter and the correction thus calculated.

Suspension apparatus for a vehicle

A controller for AC power converter having an LC filter connected to a load, can suppress fluctuation of the output bus voltage against disturbance, particularly against fluctuation of load current by calculating a capacitor current command from a voltage feed back value and then adding an interference component caused by a reactor and a capacitor to the voltage command of the AC power converter.

Controller for AC power converter

A DC-DC converter comprises a switching element having a rise time t.sub.on and a fall time t.sub.off ; a control device for controlling the switching operation of the switching element; a transformer having a primary winding and a secondary winding, the primary winding being connected to a DC power source through the switching element, and having an open inductance L.sub.M ; an inductance coil having an inductance L connected to the secondary winding of the transformer; and a rectifying device for rectifying the output from the secondary winding of the transformer; assuming that the voltage applied to the primary winding of the transformer is E, the load current flowing through the transformer is I.sub.D, and the sum of the stray capacitance of the switching element and the distributed capacity of the windings of the transformer is C1, the following relational expressions being established:

Low-switching loss DC-DC converter

A method of operating a three-phase converter to produce a signal at an output frequency by decoupling and digitally sampling inverter input signals and load voltage signals and feeding the resultant phase signals back into the inverter. The phase voltages activate switching elements in the inverter to switch signals a plurality of times within one cycle of the output frequency thus changing electrical power at a first frequency, including direct current, to A.C. power at the output frequency.

A method of decoupling a three-phase converter

In an induction motor controller, for the amount equivalent to the secondary interlinkage flux computed by use of a component of lag of first order based on the search coil voltage or the primary voltage of the induction motor, an error with respect to the actual secondary interlinkage flux is increased in a low-speed range. However, since an estimated amount equivalent to the secondary interlinkage flux computed based on the estimated amount of the secondary interlinkage flux is also attended with the same error with respect to the secondary interlinkage flux, when the former is substracted from the latter, there only remains a term concerning the speed estimation error, which enables an estimation of the speed to be conducted also in the low-speed range. Furthermore, since the time constant of the component associated with the lag of first order is varied depending on the primary angular frequency, dumping is fixedly developed for the amount equivalent to the secondary interlinkage flux, and as a result, the speed identification characteristic is fixed regardless of the high-speed and low-speed operations of the induction motor.

Induction motor controller

A 3-phase-to-3-phase power converter is intended to control the output voltage and current so as to provide a 3-phase sinusoidal wave which is controlled in compliance with the input voltage. The main circuit has a switching period shorter than 30.degree. of the power voltage waveform and it is controlled so that switching of lines takes place in alternate fashion, whereby the input power factor is improved.

Three-phase-to-three-phase power converter

The present invention consists in connecting an auxiliary D.C. voltage source to a series-connected assembly constructed of electronic switches, whereby even when the electronic switches in the series-connected assembly have unequal switching rates, any overvoltage is not applied to the electronic switches and any power loss ascribable to the overvoltage is prevented.

Series-connected assembly of electronic switches

A control circuit 3 for an induction motor 2 detects the voltage applied across the motor winding and the current flowing therethrough. The supply power and the feedback power are determined from the detected voltage and current and are supplied to a computing unit whose output controls a voltage regulator such that the voltage applied across the motor winding results in a fixed, predetermined ratio between the effective and apparent powers to maximize the motor efficiency and to minimize the motor's power consumption regardless of variations in the line voltage and fluctuations in the motor load.

Power control circuit for induction motor

An error amplifier is connected to both a tachometer generator for an induction motor and a command speed generator to produce an error signal corresponding to the difference between the actual motor speed and a command motor speed. A current limit generator connected to the tachometer generator generates a current limit signal which is subtracted from a motor current signal from a current sensor for the motor. A multiplier imparts to the resulting difference signal the polarity opposite to that of the error signal as determined by a polarity discriminator. The difference signal is added to the error and actual speed signals by an adder to form a command frequency signal. An inverter controls the motor in response to the command frequency signal.

Speed control system for induction motor

Economical thyristors are used instead of expensive transistors and a transistor is used for extinction of the thyristors to reduce cost in an inverter device having an inverter function for converting DC to AC or a current type inverter device having a chopper function for controlling DC power and an inverter function for converting DC to AC.

Inverter device

An inverter device for converting DC to AC by using thyristors as switching elements comprises a commutation circuit for turn-off of the thyristors which is formed by a serial connection of an auxiliary power source, a gate control thyristor and a thyristor which is commonly used and connected to a thyristor used as the switching element which is turned off by applying a reverse voltage by turning on the gate control thyristor and the thyristor of the commutation circuit.

Growing community of inventors

Amagasaki, Japan

Hidehiko Sugimoto