This is a circuit topology developed in recent years. It mainly consists of three parts: input transformer, power unit and control unit. The modular design, due to the power unit connected to each other in series to solve the problem of high voltage named, can be directly driven AC motor, without the need for output transformers, but does not require any form of filter.
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A total of 18 sets of inverter power unit, each phase by the 6 power units in series, and the formation of Y-shaped connection, direct drive motor. Each power unit circuit, the structure is exactly the same, can be interchangeable, can also be mutually alternate. The company is located in:
Inverter input part is a phase-shifting transformer, the primary side of the Y-shaped connection, the secondary side of the triangular connection along the edge, a total of 18 three-phase windings, respectively, for each power supply unit. They are divided equally into three parts, I, II, III, each with six small three-phase windings, with a uniform phase shift of 10 degrees. The company is located in:
The inverter features are as follows:
① using multiple PWM control, the output voltage waveform close to the sine wave. The company is located in:
② rectifier circuit multiplexing, the number of pulses up to 36, high power factor, the input harmonic small. The company is located in:
③ modular design, compact structure, easy maintenance, enhanced product interchangeability. The company is located in:
④ direct high-pressure output, no output transformer. The company is located in:
⑤ extremely low dv / dt output, without any form of filter. The company is located in:
⑥ optical fiber communication technology to improve the anti-interference ability and reliability of the product. The company is located in:
⑦ automatic bypass circuit power unit, to achieve failure without stopping function. The company is located in:
With the rapid development of modern power electronic technology and computer control technology, the technical revolution of electric transmission has been promoted. AC speed control instead of DC speed control, computer numerical control to replace analog control has become a trend. AC motor speed control is today’s energy conservation, improve production processes, improve product quality, and improve the operating environment as a major means. Frequency control with its high efficiency, high power factor, as well as excellent speed control and start braking performance and many other advantages of the domestic and international are recognized as the most promising speed control mode. The company is located in:
Previous high-voltage inverter, controlled by the SCR rectifier, SCR inverter and other components, a lot of shortcomings, large harmonics, have an impact on the power grid and motor. In recent years, some new devices developed will change this status quo, such as IGBT, IGCT, SGCT and so on. By their high-voltage inverter, high performance, PWM inverter can achieve, or even PWM rectifier. Not only has a small harmonic, the power factor is also greatly improved.
According to the transformation of the classification
(1) AC – DC – AC inverter, it is the first frequency AC through the rectifier into a DC, and then convert the DC to AC voltage frequency adjustable, also known as indirect inverter, is currently widely used in general Inverter. The company is located in:
(2) It can be divided into AC-AC inverter, which will convert AC power directly into AC voltage frequency adjustable, also known as direct frequency converter;
According to the nature of DC power classification
(1) Voltage-type inverter Voltage-type inverter is characterized in that the energy storage component of the intermediate DC link adopts a large capacitance, and the reactive power of the load will be buffered by it. The DC voltage is relatively stable, the internal resistance of the DC power supply is relatively small, It is called voltage-frequency inverter, often used for load voltage changes in the larger occasions. The company is located in:
(2) current type inverter current type inverter is characterized by the middle of the DC link with large inductance as energy storage link, buffer reactive power, that is, to curb the current changes, the voltage close to the sine wave, the DC resistance larger, so Said current source converter (current type). Current-mode inverters offer the advantage (advantage) of limiting frequent and drastic changes in load current. Commonly used for load current larger changes in the occasion.
Press the main circuit working method
Voltage type inverter, current type inverter
According to the principle of classification
Can be divided into V / f control inverter, slip frequency control inverter and vector control inverter;
According to switch classification
Can be divided into PAM control inverter, PWM control inverter and high carrier frequency PWM control inverter;
Classified according to usage
Can be divided into general-purpose inverter, high-performance dedicated inverter, high-frequency converter, single-phase inverter and three-phase inverter. In addition, the inverter can also be classified according to the output voltage regulation, according to the control classification, according to the main switch components classification, according to the input voltage level classification.
Press the inverter voltage regulator method
PAM frequency converter is a by changing the voltage source Ud or current source Id for output control. The way of PWM inverter is to generate a pulse pulse in one cycle of inverter output waveform. The equivalent voltage is sine wave and the waveform is smoother.
According to the principle of work
U / f Control Inverter (VVVF Control), SF Control Inverter (Slip Frequency Control), VC Control Inverter (Vectory Control Vector Control)
Classified by voltage level
High-voltage inverter, medium voltage inverter, low-voltage inverter