Kabushiki Kaisha Yaskawa Denki

Shigekazu Nakamura

Hideaki Iura

Yoichi Yamamoto

Masashiro Tanaka

Hiroshi Suetake

In a DC braking method for stopping an induction motor, torque shock generated by an abrupt change of an output current phase is reduced to a predetermined value or less when a switch-over from a normal control state to a DC braking state. When a switch-over from a normal control state to a DC control state is performed, the generated torque shock is reduced to a predetermined value or less is provided. In this case, an abrupt change of an output voltage phase is inhibited by predictably operating the output voltage phase during the DC braking to control the power converter on the basis of a setup DC braking initiation frequency or a phase advanced until the DC braking is initiated, which is predetermined by a deceleration rate and the setup DC braking initiation frequency and the output voltage phase of a normal control state at the instant that a switch-over to the DC braking state is performed.

Method of braking induction motor and control apparatus

A control method and a controller for an a.c. motor without using a speed sensor in which the speed estimated value or the magnetic flux estimated value of an all-dimensional magnetic flux speed observer can be made to correspond to that of an actual a.c. motor.

Method and device for sensorless vector control for AC motor

A simple and accurate dead time dispersion measurement method and a voltage source inverter control method that can prevent the occurrence of an unstable phenomenon are provided. The control method controls a voltage source inverter of a PWM system, which includes a power semiconductor device controlling a level of a voltage, a frequency and a phase. According to the control method, before operation, voltage error information for each polarity of respective phase currents of the inverter is stored. And during the operation, the voltage error information is read to compensate for a voltage instruction value or a pulse width of a PWM instruction signal, so that a voltage error can be corrected.

Growing community of inventors

Fukuoka, Japan

Shigekazu Nakamura