| As the basic equipment of smart grid, smart meter plays an important role in the intelligence and informatization of smart grid. Before they leave the factory, it is necessary to calibrate thier accuracy. And as the standard power supply for calibration, the single phase inverter with adjustable frequency and amplitude directly influences the calibration accuracy of smart meter. But there are little literatures on it. Based on this background, to supply the need of developing ‘the single phase SPWM program controlled power supply system’, the control stategies of the single phase inverter with adjustable frequency and amplitude are studied in this paper.Aiming at the stablility problem caused by resonance peak of output filter, analysis on existence necessity and harm of filter resonance peak is given. Four basic passive damping methods are compared in detail, which the method of L series connected with R has the best effect. To reduce the damping loss, the active damping method based on the inductor current feedback is selected to suppress the resonance peak. The inverter model is established and the control parameters of the system are designed. The rationality of the parameters design is verified by MATLAB simulation. The frequency and amplitude modulation functions of the inverter are verified by Simulink simulation analysis.Aiming at the problem of large load regulation rate of output voltage, a detailed analysis on the effect of load current on the output voltage is given. A full feedforward strategy of load current is proposed. And the applicable scope of the strategy and the classical proportional strategy are analyzed and discussed. Through Simulink simulation, the load regulation rate of the system in the condition of no feed forward, proportional feedforward and full feedforward is analyzed. The proposed strategy is verified.Aiming at the problem of the DC component in the output voltage, the reasons of DC component in the system are analyzed. The equivalent model of DC component in single phase inverter is established. According to the characteristics of the model, the mechanism analysis of the DC component suppression is carried out. A method to increase the damping of DC component by using the feedback inductor current is proposed. The proposed strategy is verified through Simulink simulation analysis.On the basis of theoretical and simulation analysis, a 1.5k VA experimental prototype based on DSP was designed, which has the functions of continuous regulation of frequency and amplitude. And the related experiments are carried out. The experimental results show that with the proposed control strategy, the experimental prototype meets the requirements of the target. And the correctness of theoretical analysis is verified. |
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