Hitachi, Ltd.

Takeshi Hanada

Masahiko Watanabe

Kenji Kubo

Masatsugu Kametani

Toshihiko Matsuda

Tsutomu Omae

Kengo Sugiyama

Takashi Kogawa

Hiroyuki Hanei

A control apparatus for controlling a controlled object including controlled elements comprises a host processor, a plurality of slave modules and a communication network for providing communication between the host processor and the slave modules. The host processor interprets a control program to generate commands for the controlled elements in response to demands send from the slave modules. These commands are sent via the communication network to the respective slave modules. Each slave module is allotted to a controlled element and has a processor which interprets and executes the commands for its allotted controlled element and generates a demand upon finishing the execution of a command. This demand is sent via the communication network to the host processor and causes the next command to be generated.

Decentralized master-slave control apparatus

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

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Chiba, Japan

Takeshi Hanada