Design of Electromagnetic Interference Circuit of Matrix Converter
Overview:
The matrix converter is AC/AC direct conversion, the grid and load will directly affect each other, and the fluctuation of the grid will directly interfere with the load (such as asynchronous motor). These sources of interference affect the output and input currents and voltages by means of conduction and radiation, and must be tried to suppress or reduce them to an acceptable range.
The matrix converter is a forced-commutated AC-AC converter. It consists of 9 controllable bidirectional switches. It uses PWM control to directly convert the AC power supply into the variable voltage variable frequency power supply required by the load. 1 is shown. The bidirectional switch uses two IGBT common collectors in reverse series, using a freewheeling diode inside the device to block the reverse voltage, which is compact, convenient, and low in switching loss. The input side L-C filter effectively reduces the switching frequency harmonics of the input current. 
Figure 1: Schematic diagram of the matrix converter
EMI analysis matrix converter is AC/AC direct conversion, the grid and load will directly affect each other, the fluctuation of the grid will directly interfere with the load (such as asynchronous motor); the bidirectional switch composed of IGBT and anti-parallel diode, and their High-speed integrated circuits such as control circuits DSP and CPLD have high di/dt, which cause transient electromagnetic noise through the lead inductance of the line or component, and its frequency is several thousand Hz, which becomes a non-negligible noise source; PWM modulation The wide application of technology in various power electronic devices, in their main power circuit, usually through a series of PWM power pulses, the repetition frequency can be several thousand Hz depending on the application, so these pulse currents are included The harmonics can reach a range of several MHz or even tens of MHz, and they generate a large amount of electromagnetic noise; while surrounding equipment and devices radiate electromagnetic waves, they also become a source of interference that cannot be ignored. These sources of interference affect the output and input currents and voltages by means of conduction and radiation, and must be tried to suppress or reduce them to an acceptable range.
Countries around the world have established corresponding standards for electromagnetic compatibility of electrical equipment, especially in Western Europe. Since January 1996, they have been strictly enforced. China has corresponding standards and regulations. Therefore, input filters must be used to reduce the matrix. The switching frequency harmonics generated by the converter, this paper focuses on the design of the input filter.
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