| With the development of technology and the improvement of human life, the electric car industry has been vigorous development. And there are so much automotive electronic products in the car, these electronic products are mostly powered by a 12V DC, and this requires that the vehicle must be equipped with DC/DC converter for Electric Vehicles Auxiliary Power. Currently, because of the special environment of the car, usually we have very demanding requirements on DC/DC converter for Electric Vehicles Auxiliary Power. For example:high efficiency, high power density, earthquake resistance, wide voltage input, good EMC performance and so on.In view of the above problems, in order to realize the high efficiency of the vehicle auxiliary power DC/DC converter, In this paper, the LLC resonant converter is used as the main topology.LLC resonant soft switching technology has a wide range of input, full load range of the primary side of the ZVS and ZCS, low switching loss, good EMC performance and high efficiency, it’s very suitable for being a on-board vehicle DC/DC converter.Based on the working principle of LLC resonant converter, We found the mathematical model of LLC converter by using the fundamental wave analysis method (FHA),We understood the influence of circuit quality factor and inductance coefficient on voltage gain by using the software MATHCAD. We design the three resonant elements and transformer turn ratio by the conditions of achieving the original ZVS of LLC converter, the entire converter low cost, high efficiency and miniaturization.The selecting switching frequency is slightly less than the resonant frequency, so we must ensure the other side has been working at the zero current turn off. After that, the LLC converter is simulated by SABER software, which verifies the rationality of the parameter calculation.In order to achieve the high steady-state and dynamic performance of the whole converter, Firstly, the small signal model of the LLC converter circuit is built by using the equivalent circuit method, because of this we obtained the transfer function of converter control system. Then we use the software MATLAB to simulate the converter to verify the correctness of the theoretical analysis. Then we use the SISOTOOL to design the PID compensation network,which are meeting the requirements of the standard. Finally, we simulate the LLC circuit with the software MATLAB.Because the traditional PID parameter setting method has certain limitation, In this paper, the chaotic search mechanism is introduced into the standard particle swarm algorithm. We make two kinds of search mechanisms complement each other, forming a chaotic particle swarm optimization algorithm. Chaotic particle swarm optimization algorithm is used to optimize the parameters of PID controller, which greatly improves the performance of the controller. We take the digital control into account, due to simplify the circuit, programmable, high reliability, has become the development trend of power control technology, In this paper, we use the digital control scheme and build the hardware platform of LLC converter. the on-board computer (ECU) can acquire the working process of real-time monitoring and feedback on the vehicle auxiliary power DC/DC converter. Then we add CAN communication module Finally, we introduce the workflow of the whole converter system. |
PDF Full Text Request