| Vehiclemotorization is a main stream for energy conservation and environmentprotection.The development of the micro-electric vehicle has special and practical significance for the transportation system in China.Different from ordinary vehicles, micro-electric vehicle mainly drive at a low speed on complex urbanroads, which requires the vehicle to restart and slow down frequently. Therefore, the design ofsynergic electric power supply in the micro-electric vehicle is much different from that in ordinary vehicles, which is manifested not only in power level, voltage and current level, cost and volume, but in the requirement for adaptive capacity in the condition of frequent acceleration and deceleration and also in speed and efficiency of dynamic response.Based on the requirement and conditions where the micro-electric vehicle is used, the structure of synergic electric power supply constituted with lead-acid battery and super capacitor is determined. The following are the accomplished researches.The analysis is made on the performance requirements of components in synergic electric power supply basing on the road driving cycles. Bi-directional full-bridge DC-DC structure is perfected, its working pattern is analyzed and each parameter is made match calculation.Logic threshold control strategy basing on speed is implemented after the analysis of existing control strategy of power allocation.Under the condition of Matlab/simulink, simulation of synergic electric power supply system is established. By conducting the simulation test, function of synergic electric power supply system and its components are verified, and feasibility of the design is analyzed. The result shows that the synergic electric power supply system has high capacity to output voltage and current steadily; The system is quick in dynamic response and good in regulation because of PID control.Controller of bi-directional DC-DC converter is accomplished and also compiling and debugging of the software is finished.Synergic electric power supply system composed of lead-acid battery, super capacitor and bi-directional DC-DC converter is constructed. And static test and dynamic joint test is conducted for synergic electric power supply system.The result of static test indicates that bi-directional DC-DC converter not onlyhas the ordinary function to stabilize voltage but also has the function to stabilize current as required. And the efficiency of DC-DC converter is 80%-90% unless its working power is too small. The dynamic joint test manifests that the synergic electric power supply system can effectively allocate power and enable super capacitor to shift peak load. High current charge-discharge of battery can be avoided when operation is started, and discharge current of battery is enabled to change steadily, which gives the battery great protection. Super capacitor achieves great effect on motor in the level of regenerative braking by using super capacitor. |
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