| The control methods of a 150W inverter and a 5000VA parallel inverter are investigated in this thesis. The modeling and stability analysis are used to design the control loop, and the experiment results are given to show the control performance.Firstly, The circuit structure and digital SPWM control method of the 150W inverter, which is applied to the car, are introduced. The inverter consists of a push-pull step up converter and a full bridge inverter which are controlled by the UC3525A PWM controller and the PIC microchip respectively.Secondly, the voltage mode control of parallel inverter is designed which integrates three loops. An inner inductor current loop is used to improve the stability and transient performance, and a middle capacitor voltage loop is used to regulate the output voltage. The outer average current sharing control loop is used to balance the load currents in the system and has no influence on the load voltage. The average value of load current is used as the reference of output current, and the current error is treated as a compensation component of the voltage reference.Thirdly, a prototype of two inverters in parallel operation is made according to the design, and the experiment results are given to prove the correctness of analysis.Finally, the differences in structure and control method between this two inverters are compared as a conclusion. And some ideas are presented for further research. |
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