A power semiconductor device includes trenches disposed in a first base layer of a first conductivity type at intervals to partition main and dummy cells, at a position remote from a collector layer of a second conductivity type. In the main cell, a second base layer of the second conductivity type, and an emitter layer of the first conductivity type are disposed. In the dummy cell, a buffer layer of the second conductivity type is disposed. A gate electrode is disposed, through a gate insulating film, in a trench adjacent to the main cell. A buffer resistor having an infinitely large resistance value is inserted between the buffer layer and emitter electrode. The dummy cell is provided with an inhibiting structure to reduce carriers of the second conductivity type to flow to and accumulate in the buffer layer from the collector layer.

Power semiconductor device

A power converter system advantageously employs a modular, bi-directionally symmetrical power converter assembly in a readily customizable configuration to interconnect a direct current power source to a three-phase alternating power grid. Connections external to the power converter assembly are selected to optimize the power converter system for a specific application, such as interconnecting a photovoltaic array to the three-phase electrical power grid. The electrical interconnections of various elements including isolation transformers, voltage sensors, and control switches are optimized to improve efficiency and reliability.

Power converter system

The authors discuss a number of issues involved in designing a current source inverter system for a large induction motor drive. Using two modulation techniques-selected harmonic elimination in the upper frequency range and trapezoidal modulation in the lower frequency range-control of voltage, current, and torque harmonics is achieved while limiting the GTO switching frequency to 180 Hz. Each modulation range is divided into a number of subranges to exploit the available switching capacity and to avoid harmonic resonances involving the capacitor and the motor inductance. In addition to the development of basic principles, the authors include simulation waveforms and test results from a laboratory experimental system. >

PWM-CSI inverter for induction motor drives

An elevator controller which uses an acceleration command signal that has as its initial value a start shock compensation torque which will offset the unbalance torque caused at the time of starting. From the completion of elevator car acceleration to the start of deceleration, the acceleration command is gradually increased or decreased to control the motor (7, 8) so as to provide a smoother motion of the car (1). After the inception of the car deceleration a velocity command is issued which increases with the reducing distance between the car (1) and the destination floor.

Controller for elevator

A motor driving apparatus capable of drivingly controlling a plurality of inverter units (IV1-IV4) with a single motor driving command S from a motor control unit (1), to thereby control a large-capacity motor or the like. The motor control unit (1) sends out a single motor driving command (torque command) S. An intermediary unit (3) obtains motor driving commands SxA1 to SxA4 for the inverter units (IV1-IV4) by multiplying the motor driving command S by each of coefficients A1 to A4 set in advance. The inverter units (3) are fed with the motor driving commands SxA1 to SxA4 individually and drive a single motor (2). Since the motor (2) is driven by the total current supplied by the inverter units (IV1-IV4), the motor can generate a large torque. The motor control unit (1) only needs to generate a single motor driving command S, and hence only needs to operate a single processing part. Alternatively, the single motor (2) may be replaced by a plurality of motors, each associated with a respective one of the inverter units (IV1 to IV4). Also, the intermediary unit (3) may generate the individual motor driving commands in the form of parallel or serial data.

Motor driving apparatus

A control system for an AC elevator system in which an actual speed of an elevator car is compared with a speed command and control is made so that deviation between the actual speed and the commanded speed becomes zero. The speed command is so composed that deceleration of the elevator car is gradually decreased as the car approaches to a target landing position in the stopping operation of the elevator. A motoring torque or a braking torque is additionally generated in dependence on a load on the car in a region close to the target landing position.

AC Elevator control system

A pulse generator (including a microcomputer) for supplying a pulse pattern to semiconductor devices of a power converter (such as an inverter or a converter) using the pulse width control scheme is provided with function of dropping pulses so that the pulse pattern may form a predetermined function provided that the pulse width is shorter than a limit value (Limit). As a result, the input and output waveforms of the power converter can be made sinusoidal and can be released from the constraint of the minimum pulse width of power conversion semiconductor devices.

PWM control for power converter system utilizing pulse dropping at minimum pulse widths

PROBLEM TO BE SOLVED: To provide a power converter that seldom produces trouble in a main circuit, wherein deterioration in a main circuit element, a smoothing capacitor, and a smoothing reactor due to thermal stress is determined from accumulated information on the state of inverter operation. SOLUTION: A device is for controlling the power converter 1 that drives an induction motor by an inverter having a main circuit element. This device includes means 14 for detecting the temperature of the main circuit element of the inverter; means 20 for computing a first coefficient normalized from a switching frequency; means 21 for computing a second coefficient normalized from an output voltage command; means 22 for multiplying the first coefficient, second coefficient, and detected temperature to compute an amount of thermal stress; means 23 for determining the states of gate start and stop of the inverter; means 25 for adding and storing the amounts of thermal stress during the operating time of the inverter; means 26 for accumulating added values to compute an accumulated value; and means 27 that, when the computed accumulated value becomes equal to or higher than a predetermined value, determines that the main circuit element has been deteriorated. COPYRIGHT: (C)2007,JPO&INPIT

Controller for power converter

A control apparatus for an elevator car having an alternating current motor system comprising a high speed motor mechanically coupled with a low speed motor, wherein the high speed motor is used in accelerating and normal running and the low speed motor is excited by a direct current voltage upon separation of the high speed motor from its alternating current source to effect deceleration.

Control apparatus for an elevator car

An electric motor controlling system comprising an induction motor system consisting of at least one induction motor having motoring torque generating means and braking torque generating means, antiparallel connection of thyristors connected between an Ac source and the motoring torque generating means, means for controlling the thyristors such that the motoring torque generating means generates, when the speed deviation is positive, a motoring torque corresponding to the value of the speed deviation, a controllable rectifying circuit connected between the AC source and the braking torque generating means, means for controlling the controllable rectifying circuit such that the breaking torque generating means generates, when the speed deviation is negative, a braking torque corresponding to the value of the speed deviation, and means for giving the torques of the motor system a push-pull characteristic depending upon the speed deviation by biassing the two control means.

Electric motor controlling system

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