Matsushita Electric Industrial Co., Ltd.

Other

Kazuhiko Tamesue

Masahiro Takada

Yuji Igata

Kunio Kanamaru

Michinori Kishimoto

Masahiro Maki

Satoshi Hasako

Shoichi Koga

Yuji Torii

Koichi Nagano

Satoshi Shinozaki

Masuo Nakamura

To use high noise transmission lines, such as an electric wire, as the lines to transmit signals, it is imperative to reduce the level of signals. The present invention is provided with a sending signal generating means , which outputs converted data after converting an input signal into a plurality of carrier signals assuming values at such intervals on the axis of frequency that the frequencies may not interfere with each other. If an interfering noise with any one of the plurality of frequencies arises on the transmission line, removal of only a carrier of the noise frequency would leave the communication in a good condition. Furthermore, better results can be hoped for if the respective carrier signals are so arranged as not to interfere with each other or so arranged to intersect orthogonally with each other not only on the axis of frequency but also on the axis of time

Communication systems, sender and receiver

A battery power source device is composed of a plurality of battery modules, in which each battery module includes a number of serially connected cells. A voltage detection circuit is associated with each battery module. Each voltage detection circuit includes a differential amplifier that detects a voltage across end terminals of the associated battery module, and the detected voltage is digitized and output through a photo-coupler to a controller. The differential amplifier is connected to the battery module through photo-relays, which are closed in response to an open/close control signal only during a voltage detection operation, so that leak currents are eliminated. The differential amplifier and an associated A/D converter are provided with operating power obtained by transforming the voltage of the battery module with regulators, whereby noise effects are eliminated.

Battery voltage detector

An electric leak detecting apparatus used for an electric motorcar includes a source for generating an AC signal, which supplies a sine wave detecting signal S,of a single frequency fl Hz to between a vehicle body and a low potential side or a high potential side of a battery pack, a condenser having capacitance Cd for insulating the AC source from the low potential side or high potential side of the battery pack with respect to direct currents and for connecting the AC source to the low or high potential side of the battery pack with respect to alternating currents. Also included are a voltage detecting circuit for detecting an AC signal voltage of the detecting signal S,at either side of the condenser, a current detecting circuit for detecting an AC signal current of the detecting signal S,, an admittance detecting circuit for computing an electric leak admittance &verbar;Y&verbar; from the AC signal voltage and AC signal current of the detecting signal S,a phase discriminating circuit for finding a phase difference between the AC signal voltage and AC signal current of the detecting signal S,, a resistance component detector for detecting a resistance component by computing a real part of the admittance &verbar;Y&verbar; from the admittance and phase difference. Also included is a comparison device for comparing the resistance component to a threshold value.

Electric leak detecting apparatus for electric motorcars

A variable gain amplifying circuit is controlled by a control voltage Vc from which a high-frequency component has been removed. To provide the control voltage Vc, a holding circuit smoothes the higher one of an output voltage of the variable gain amplifying circuit, which has been rectified by a rectifying circuit, and a voltage detected by a minute voltage detecting circuit, so that the control voltage Vc is obtained via a direct-current amplifying circuit. Since the clamping circuit varies the control voltage Vc based on a reference voltage Vref on receiving a minute input signal, even when an AGC characteristic is changed by varying the reference voltage Vref, the minimum gain is always corrected to be constant.

Automatic gain control device for producing constant amplitude output

Growing community of inventors

Fukuoka-ken, Japan

Kazuhiko Tamesue