| The energy regenerative semi-active suspension,whose energy consumption is low,has a simple structure, and is easy to implement.Which can not only improve the dynamic performance of the vehicle, but also transform vibration energy into electrical energy. So the energy regenerative semi-active suspension is one of the hottest research focus. The suspension system is constructed by connecting a linear motor to the traditional passive suspension in parallel. The semi-active suspension control circuit with DC_DC converter is designed, which can be switched between operation modes of Buck and Boost by adjusting the duty ratio of the switch signal in real time, to realize the tracking control from the motor winding current to the reference current, so that the output of the ideal motor electromagnetic damping force can be obtained,and the control of semi-active energy regenerative suspension is realized. The super capacitor, which is taken as the interim energy storage device, is connected to the output end of the semi-active control circuit. The electric energy in the super capacitor was finally stored into the car battery through the super capacitor mode switching circuit and the voltage stabilizing charging circuit. The main research contents of the paper are as follows:Firstly, the overall scheme of the system is designed. Single wheel model of the suspension was built based on the Ground-hook and sky-hook semi-active control strategy.The energy regenerative characteristics of the system was simulated and analyzed in MATLAB and the energy storage device is selected preliminary. Damping characteristics of the system and working characteristics of the semi-active control circuit are analyzed, and the switching law of the working modes of the semi-active control circuit for the energy regenerative suspension is obtained.Secondly,the structure of hardware circuit is analyzed, and the hardware configuration and software function of the data processing unit, i.e. dSPACE, for the control system are briefly described. The hardware circuit design of the semi-active control and energy storage system are completed, which mainly includes: the inductance and the main body of the circuit for the semi-active control circuit are designed, selection of the chip and design of the expanding circuit, design for the main body of the super capacitor mode switchingcircuit, type selection analysis of the switch tube, as well as design and principle analysis of voltage stabilized charging circuit.Thirdly, the DC_DC converter is applied to the suspension system. The effect of the initial terminal voltage of the super capacitor on the energy efficiency and the dynamic performance for the suspension system are analyzed by simulation. A control strategy is proposed for the super capacitor mode switching of the energy regenerative semi-active suspension. Simulation results show that the super capacitor mode switching control strategy has no effect on the dynamic performance of the suspension system, but the efficiency of the system energy recovery increased by 18% in average.Fourthly, the fuzzy-PI hybrid controller is designed for the control of the current in the semi-active control circuit, and the experiment was carried out based on dSPACE. The experimental results show that actual current can accurately track the reference current with the help of the controller.Lastly, on the single channel test platform, the passive energy regenerative characteristics of the system are studied with two kinds of inputs, i.e. sinusoidal excitation and random excitation. The DC_DC converter is applied to the suspension system, and the effect of the initial voltage of the super capacitor on the suspension system is analyzed.Results show that dynamic performance of the suspension has no obvious change with the increase of the initial terminal voltage of the super capacitor. Energy recovery of the super capacitor increases firstly and decreases subsequently. |
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