High-voltage sine wave inverter inverter power supply circuit design

Probe high frequency needle 10445 with line high frequency needle with 1 high frequency core can pass 3A

Summary:

1 Introduction

At present, in the fields of ozone generator, sewage treatment, flue gas desulfurization, high power laser, plasma discharge, etc., high voltage inverter power supplies are getting more and more applications. The traditional high-voltage inverter power supply is generally obtained by direct voltage boosting or LC series resonance of a power frequency or intermediate frequency transformer, and inevitably has the disadvantages of large volume and low efficiency. In many occasions where high-voltage power supplies are required, the use of high-frequency high-voltage power supplies far above the power frequency is better, and the high-frequency power supply is small in size and light in weight, which is the future development direction. This paper introduces a high-voltage sine wave inverter power supply for a dielectric barrier discharge generator. The dielectric barrier discharge generator is composed of an insulating material and a discharge electrode which is etched at both ends of the insulating material, as shown in FIG. The addition of the dielectric layer in the gap of the discharge electrode can effectively suppress the increase of the discharge current and contribute to the formation of a stable plasma layer at both ends of the medium. The equivalent circuit can be approximated as a capacitor and a resistor in parallel. This capacitive load must consider its influence on the filter characteristics when designing the power supply. In order to study the characteristics of the discharge device at different voltages and frequencies, it is necessary to have a large range of output voltage and frequency variation of the power supply. For the device, the requirements for the power supply are: the output voltage can reach 20kV, the output current can reach 1A, the frequency varies from 5 to 20kHz, and the waveform is pure sinusoid. The design points of the power supply are described below.

2 Design of high voltage sine wave inverter inverter power supply

The schematic diagram of the high voltage sine wave inverter power supply designed in this paper is shown in Figure 2. The input power is three-phase 380V, and after being rectified by the three-phase bridge, a DC voltage of about 540V can be obtained (fluctuating with changes in the grid voltage). The DC voltage is passed through a DC/DC converter to obtain a DC voltage with a variable output amplitude, and the variation range is designed to be 0 to 500V. This conversion can be realized by a common Buck step-down conversion circuit. The variable DC voltage is obtained by a square wave output via a DC/AC full bridge inverter circuit. The square wave is filtered by LC to obtain a sine wave output. The filter inductor consists of an external inductor and the transformer's own leakage inductance. The filter capacitor consists of the transformer's own stray capacitance and the load's own capacitance. The low voltage sine wave is finally boosted by a high voltage high frequency transformer to obtain the required high voltage sine wave. The general inverter can realize the functions of frequency conversion and voltage transformation only by DC/AC one-stage transformation, but this example has higher requirements on the output waveform, and the output frequency is higher, which is not good for high-frequency modulation. Therefore, The two-stage transformation is adopted to realize the functions of frequency conversion and voltage transformation respectively.

The DC/DC section is controlled by the SG3525, which changes the DC output voltage by changing the duty cycle of its output. The function of the DC/AC part is only to convert DC into AC. Therefore, the control chip of this part also adopts SG3525, and its duty ratio remains basically unchanged during the operation, only the frequency changes within the set range. The 80C196KC MCU mainly functions as a human-machine interface in the whole circuit. It is responsible for accepting control commands and displaying some parameters and statuses during the work process. The keyboard and display interface circuit communicate with the CPU through the 8255 chip. The parameter adjustment interface is mainly responsible for transmitting the output command of the 80C196KC to the SG3525 power control chip to realize the adjustment of the output voltage and frequency of the power supply. All the power switch tubes adopt IGBT. All power tube drives adopt special IGBT drive control chip M57959L. The chip has optical isolator and overcurrent protection circuit inside, which is convenient to use.

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