Development of an Airborne Three-Phase AC Stabilized Power Supply

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Development of an Airborne Three-Phase AC Stabilized Power Supply [Copy link]

Abstract: The development of an airborne three-phase AC stabilized power supply is introduced. The power supply circuit is analyzed, calculated and simulated by computer. High-frequency pulse width modulation chopping inductance modulation technology is applied, MOS field effect tubes replace traditional bidirectional thyristors, and pulse width modulation replaces phase control technology. Through the optimization design of the circuit, the input harmonic current is reduced.

Keywords: resonance; AC voltage regulation; computer simulation

The main function of the airborne AC regulated power supply introduced in this article is to provide AC excitation signals for numerous sensors in avionics systems, which requires stable performance, small size, light weight, high efficiency, and high reliability. Around the 1970s, the AC regulated power supply used on advanced foreign combat aircraft adopted transformer compensation voltage stabilization technology. Its principle is to use a combination of multiple compensation transformers, and through the control circuit, switch the compensation transformer for compensation. The compensation is graded. Moreover, the required compensation transformers and switching switches are more, the circuit is more complicated, and the compensation accuracy is low. Due to the large number of intermediate frequency compensation transformers used, the AC regulated power supply is large in size and weight.

In recent years, the research on AC stabilized power supply in China has been relatively active. The main contents of the research are linear resonant technology and its improvement; the other is switching AC stabilized power supply. Linear resonant type (also known as sinusoidal energy distributor) adjusts the AC output voltage by changing the LC resonance parameters to obtain superior voltage stabilization performance in a continuously adjustable manner. The main circuit does not contain power semiconductor devices, the circuit is simple and the reliability is high. However, due to the shortcomings of insufficient input voltage range, large no-load reactive current and harmonic current at the source end, and easy oscillation, its development and application are limited, especially in high-power occasions. The switching AC stabilized power supply adopts advanced high-frequency switching power supply technology, which can reduce volume and weight, save copper and iron materials, and has the advantages of high efficiency and fast response speed. It first rectifies the AC into pulsating DC, and then inverts the pulsating DC into AC through high-frequency pulse width modulation (PWM) technology. Then, a compensation voltage with the same frequency and phase as the input side is obtained through phase tracking and conversion circuit, and added between the input and output to stabilize the output voltage. This technology has become the development direction of AC stabilized power supply technology today. However, due to the complexity of the control circuit of the switching AC regulated power supply, the slow development of domestic microelectronics technology and its process technology, it is currently impossible to provide dedicated control chips, so it is difficult to promote.

In this paper, combined with the development of model tasks, the linear resonant AC voltage-stabilized power supply is studied, and the traditional bidirectional thyristor is replaced by advanced high-frequency switching MOS field effect tube, and the phase control technology is replaced by high-frequency PWM. Through the optimization design of the circuit, the harmonic current is reduced. Debugging and testing show that the control circuit of this product is simple, the waveform distortion is small, and the performance is stable. It has been used in a certain model task.