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| Cascaded inverter is introduced |
| This is a kind of circuit topology structure developed in recent years, which is mainly composed of an input transformer, power unit and a control unit is composed of three parts. The use of modular design, because of the power unit are connected in series to solve the problem of high pressure of the name, can be directly driven by AC motor, without output transformer, even without any form of filter.
The whole converter consists of 18 power unit, each phase consists of 6 sets of power units are connected in series, and the composition of Y connection, direct drive motor. Each power unit circuit, structure identical, interchangeable, can also be mutual standby.
The input part of inverter is a phase-shifting transformer, the primary Y connection, side by side triangle connection, a total of 18 pair of three-phase windings, respectively for the power supply of each power unit. They are divided into three parts I, II, III, each part has 6 pairs of three-phase winding between small, uniform phase offset 10 degrees.
The following characteristics of the inverter:
Using multiple PWM control mode, the output voltage waveform similar to the sine wave.
Multiple of the rectifier circuit, pulse number up to 36, high power factor, small harmonic input.
The modular design, compact structure, convenient maintenance, enhance product interchangeability.
The direct voltage output, without output transformer.
The very low dv/dt output, without any form of filter.
Using optical fiber communication technology, improves the anti-interference ability and reliability.
The power unit automatic bypass circuit, can realize the fault does not stop function.
With the rapid development of modern power electronic technology and computer control technology, promote the technological revolution of electric drive. AC speed regulation system replaces DC speed control, digital control machine to replace the analog control has become a development trend. AC motor variable frequency speed control is the saving electric energy, improve the production process, improve product quality, and improve the operating environment of a main method. Frequency of its high efficiency, high power factor, and excellent speed and start-stop performance and many other advantages, is recognized as the most promising way to speed at home and abroad.
High-voltage inverter before, by the silicon controlled rectifier, thyristor inverter devices, many faults, harmonic, have the effect on the power grid and the motor. In recent years, some new device developed will change this situation, such as IGBT, IGCT, SGCT etc.. High voltage frequency converter, composed of them excellent performance, can realize the PWM inverter, and even PWM rectifier. Not only has the low harmonics, power factor is also improved to a great extent. | | | author: Published at: 2013/4/28 15:53:51 |  |
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