The Research And Design Of Low Input Voltage Inverter

This subject comes from xi ’an XX company’s research and development projects of AC regulated power supply, it’s for the control system of digital oilfield. In the oil field digital control system, Some equipment need stable AC 220 V voltage power supply, because of the conditional limitation, the provided AC voltage is unstable, so it cannot be directly used for power supply. Now we should solve this problem.Considering direct AC variable AC circuit efficiency is low, the harmonic pollution is serious, the working stability is bad, so we use an indirect way of current transformer voltage, the voltage stabilizing means mature, reliable, and stability, it is very accord with the objective of the index requirements. the whole process can be expressed as AC- DC-AC, in order to make AC- DC be used as a separate 24 V DC regulated power supply, so in the part of DC-AC, DC is 24 V, this article mainly research and design of the second half part of low input voltage of inverter.In this paper, the structure and principle of the inverter are analyzed at first. Then a low input voltage inverter is designed.First, The input voltage 24 VDC boost to 380 V DC using two BOOST circuit; Then the high voltage DC is turned into220V/50 Hz AC using a full bridge circuit and a LPF. No transformer circuit largely reduces the inverter weight.Second, The method of the full bridge control circuit is the SPWM(sinusoidal pulse width modulation) method. The frequency of the SPWM wave is two times of the carrier frequency so that the modulation circuit is simply and the output filter circuit design become easier.Third, the control system of inverter is the dual closed loop control scheme, because it is better than single loop control scheme in the stability and dynamics. And to improve the digital PID control method, the improved digital PID control mode control effect is better.Fourth, the SPWM signal, AD sampling, digital PID arithmetic are implemented by the software of C8051F020, And use the software to solve the minimum pulse width and digital filter function. This is largely improve the reliability and greatly simplify the hardware circuit system.Take the simulation platform for the system designed in this paper so that the parameters can be as close as possible to the experimental platform, do simulation studies, demonstrate the rationality of hard ware design and network control strategy.Use simulation results to optimize theoretical design and reduces the work load during the experiment. after debugging the inverter, eventually get the experimental results and waveform which confirmed the feasibility of the design.experiments verify the feasibility of the design and the correct of theoretical analysis.