Fuji Electric Fa Components & Systems Co., Ltd.

Fuji Electric Systems Co. Ltd.

Ikuya Sato

Akihiro Odaka

Yasuhiro Tamai

A power converter directly converting an AC voltage into an AC voltage of any desired magnitude and frequency by turning bidirectional switches ON and OFF without employing any energy buffer, where the peak values of output phase voltage command values are limited, to bring the amplitude of an output line voltage to, at most, 0.866 times the amplitude of the supply line voltages. By way of example, the peak-value limit of the output phase voltage command values is set so that the maximum value of the output phase voltage command values becomes, at most, 0.75 times the maximum value of supply phase voltages, while the minimum value thereof becomes, at least, 0.75 times the minimum value of the supply phase voltages. This control method for the direct power converter dispenses with an expensive dedicated motor, and permits a reduction in cost of the control apparatus as a whole.

Control method for direct power converter

A motor driving apparatus drives a motor by means of an AC/AC direct converter such as a matrix converter. The motor driving apparatus is provided with a current detecting section for detecting motor currents, a comparing section for detecting whether motor current detection values have exceeded a restriction level, an induction voltage calculating section for calculating induction voltages of the motor, a switching section, and a PWM pattern generating section. When the comparing section detects that the motor current detection values have exceeded the restriction level, the switching section supplies the induction voltages calculated by the induction voltage calculating section to the converter as output voltage instruction values.

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Hino, Japan

Ikuya Sato