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The circuit principle and harmonic characteristics of peak current mode Boost converter are analyzed, the voltage loop and the current loop are adopted to keep the input current in the same phase with the input voltage. A novel harmonic suppression technology with quasi-square wave compensation is presented in this paper, The input current harmonic components and harmonic contents are reduced by compensating the input reference current to quasi-square wave, Quasi-square wave compensation circuit is designed, and circuit simulation is carried on with Saber software, and harmonic spectrums of the input current are analyzed also. The result indicates that harmonic components of the input current in the compensated circuit are within the harmonic components limitation for IEC 61000-3-2, and the ideal harmonic suppression effect is achieved. The compensation circuit is easy to be realized, it have the advantages of high performance and low cost and is suitable for small-wattage switching power supply.

There are more chaos phenomena in Boost circuit, which make the system working in the unsteady state frequently. As the final control signal, the change of duty cycle reflects the stable operating characteristics of Boost circuit. Based on the continuous conduction mode (CCM) of Boost circuit, the duty cycle criterion of circuit stability is deduced, and the change characteristics of duty cycle are studied, the basic principle of resonant parameter perturbation control is analyzed in this paper. With the mathematical model of Boost circuit, the characteristics of resonant linear parameter perturbation modulation and sinusoidal parameter perturbation modulation are analyzed while the stability criterion is satisfied and dissatisfied, and it provides the feasible strategy and the method for Boost circuit stability design and control.

Adding-weight one-rank local-region method makes too many computations and cumulative errors while carrying out multi-step predictions, an improved adding-weight one-rank local-region forecasting model is presented in this paper. According to the prediction effectiveness of Euclid distance between two points away from prediction point in phase space, and synthetically taking into account the effect of distance and degree of incidence between nearest neighbor points and prediction point, an improved prediction is maken with weighted evolution of the neighbor points historically and the evolution of the center reference point to forecast next point directly. The results show that the improved model for short-term load not only reduce forecasting error, but also improve calculation speed. It is a novel prediction method for chaotic time series, and worth to be studied deeply.