| The variable frequency power supply is an electric energy conversion device that converts the power frequency alternating current into the voltage and frequency required by the user.Its main feature is that the output voltage and frequency can be adjusted according to the user’s needs within a given range.This paper studies the working principle of variable frequency power supply,PFC control technology,SPWM modulation principle,PID control technology,etc.,and performs detailed calculations on the selection of components during the design process,and finally designs a single-phase high-performance digital The rated power is 1k VA,the rated input voltage is 220V/50 Hz,the output voltage range is 0V～300V,and the output frequency range is 45Hz～250Hz.This article first introduces the working principle and system structure of the variable frequency power supply,formulates the design goals of this article,and then designs the entire system circuit of the variable frequency power supply,including the power factor correction(PFC)circuit and the full-bridge inverter circuit.,RCD absorption control signal optocoupler isolation drive circuit and output voltage and current signal sampling and conditioning circuit and other parts have been calculated and designed in detail,and then the system program part has been designed.At the end of the article,an experiment was carried out on a single-phase variable frequency power supply.The SPWM pulse drive waveform,dead time,and output voltage waveform under different voltages and frequencies of the variable frequency power supply were tested,and then the output current waveform,output power,and total harmonic distortion of the output under different load conditions and various The performance indicators are tested and analyzed,and the results show that the output voltage waveform of the system is of good quality,high accuracy,small total harmonic distortion,and excellent performance indicators,which have reached the design goals of this article. |
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