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A universal active filter design method is proposed for the shortcomings of multi-components, bulk mass, complex debugging, cumbersome design and bad filtering characteristics of the conventional active filter. The system which mainly contains MAX275, Surplus MCU SPCE061A and digital potentiometer can implement 2nd-, 4th-, 6th- and 8th-order band pass or low pass filter response, such as Butterworth, Bessel and Chebyshev. The parameters are setted by the keyboard and displayed by the LCD.

This paper presents a novel large capacity charger for aircraft battery, which can be used as maintainable equipment for lead-acid and cadmium-nickel batteries. The circuit scheme, control principle, software design, charger failure detection and protection circuit are also designed in detail. The main circuit of the proposed charger uses half-bridge DC-DC converter. The control circuit, which uses voltage and current double closed-loop control, takes the ADμC812 chip with A/D transformation as its core. It can control the charger in a state of constant current or trickle charge. Simultaneously, the battery charger’s soft start circuit, over-current protection circuit, over-temperature protection circuit as well as the polarity detection circuit are also designed. A prototype with ADμC812 is developed, which can control the current of the charger in the state of constant current and trickle charge. Its superiority performance such as electric separation, simple frame, high efficiency, small volume, light weight is verified by experimental results.

The output power of solar cells varies with variable temperature, light intensity and loads. In order to solve the shortcomings such as long time and high cost of using solar cells to experiment, this paper successfully uses a DC power supply and a variable resistor to simulate the solar cells output characteristic curve, its feasibility is analyzed theoretically. The basic principle of the maximum power point tracking (MPPT) is described in detail. An improved disturbance method with variable voltage step is introduced, it inherits the advantages of traditional disturbance voltage method, overcomes the shortcoming of slow response of traditional method, reduces the power loss caused by maximum power point due to continuous disturbance, and realizes the maximum power point tracking for solar cells. The proposed method improves the system's speed and efficiency. The experimental results show that the system can track the maximum power point accurately and quickly.

This paper suggests that the artificial immune algorithms can be used effectively on tuning of a PID control structures for PMLSM system. The controller's attribute behavior mechanism in PMLSM and the artificial immune system have certain similarities since both systems deal with various attribute inputs (antigens: input and noise) and output through interactions among multiple attribute modules (lymphocytes and/or antibodies: control function). Simulation results reveal that artificial immune algorithrn are effective use to search for optimal control against disturbance.