Abstract:
By outputting a compensation current in segments other than those during which leakage current is not prominent, this power conversion circuit reduces loss due to providing a compensation current. A converter (11) inputs an alternating current from an AC source (3), and rectifies and outputs the same to a DC link (15). An inverter (14) is connected with a converter (11) through the DC link (15), converts the direct current to an alternating current, and outputs this alternating current to the load (4). A leakage current detector (21) outputs a detected current (Ib) corresponding to the leakage current (Ia) leaked from the load (4). A compensation current output terminal (223) connects to a position (41) where the leakage current (Ia) leaks, and, in response to the detection current (Ib), outputs a compensation voltage (Ic) which compensates for the leakage voltage (Ia). A switch (8) sets whether or not the detection voltage (Ib) can be inputted to the compensation current output unit (22).
Abstract:
PROBLEM TO BE SOLVED: To provide a power factor correction device that is suitable for a variable speed drive unit to which single phase electric power is supplied, and has a simple construction and a high cost-effectiveness. SOLUTION: A variable speed drive unit for use in three-phase electric motor includes a rectifier module (10) for supplying rectified voltages (15) from a single phase AC network, a voltage step-up module (40) for supplying adjusted bus voltages (45), and an inverter module (50) for supplying control voltages to a three-phase electric motor (M). The variable speed drive unit includes a hybrid type power factor correction device that drives the voltage step-up module, and further includes a digital circuit (30) provided with a voltage regulator module for supplying corrected signals based on measured signals of the bus voltage, and an analog circuit (20) for supplying driver signals (25) to the step-up module. COPYRIGHT: (C)2007,JPO&INPIT
Abstract:
PURPOSE:To efficiently control an induction motor (IM) inexpensively by detecting a current between a power reactor and a smoothing capacitor and a current between the capacitor and an inverter, and detecting the exciting current component of the motor and the torque current component by the calculations. CONSTITUTION:Current detectors 7, 8 respectively detect currents ID, IA. A subtractor 9 subtracts a current I2' at no load time by the current ID. A calculator 10 calculates the ratio of the current ID' to the current IA, and generates a control signal (c) only when lower than a power factor set value cosphi*. A voltage controller 11 outputs a voltage command (v) output from a controller 6 to an inverter 4 while the signal (c) is not input as it is as v', and when the signal (c) is input, the predetermined value Vc is output as v' instead of a voltage command (v). Thus, the IM5 is always operated in such a manner that the power factor of the set value cosphi* or higher is held, thereby preventing the IM5 from generating an overexcitation.
Abstract:
모터 제어 시스템은 제어 모듈, 스위칭 모듈, 및 필터링 모듈을 포함한다. 제어 모듈은 토크 요구에 기초하여 모터를 동작시키기 위한 출력 전압을 결정한다. 스위칭 모듈은 모터를 구동시키는 인버터용 스위칭 신호를 생성한다. 스위칭 모듈은 출력 전압에 기초하여 스위칭 신호를 생성한다. 스위칭 모듈은 출력 전압, 최대 듀티 사이클, 및 인버터에 전력을 공급하는 직류(DC) 버스의 전압에 기초한 비교에 따라 OOV(out-of-volts) 신호를 생성한다. 필터링 모듈은 OOV 신호를 필터링함으로써 OOV 양을 생성한다. 제어 모듈은 선택적으로 OOV 양에 기초하여 토크 요구를 제한한다.
Abstract:
Adjustment accuracy of reactive power is improved. A predetermined reactive power instruction value at an interconnection (A) is compensated using a reactive power compensation quantity set for each of wind mills, thereby determining the reactive power instruction value corresponding to each wind mill.