The Research Of Z Source Inverter Applicated In Micro-electric Vehicle

The key technologies of the new energy vehicles include electric vehicle battery power management technology, motor control technology and vehicle control technology. Electric power integrate system includes the battery management system,motor control system and related accessories.In the design of electric vehicle electric power integrate system, the stability of power supply system has an important impact on the motor drive system. Battery voltage of ordinary electric vehicle is varying when the electric vehicle is running.The fluctuation range of battery voltage even can reach 20% of the nominal voltage.Especially when the electric vehicle is acclerated suddenly,the fluctuation of battery voltage will suddenly drop a lot. Meanwhile the electric vehicle need a large power output from the power system.Therefore the power system control and dynamic performance of electric vehicles will become worse. In practice, less capacity of the battery remains, less stable battery supply voltage is.Z-source inverter is a new kind of inverter which is different from the traditional voltage source or current source inverter。the output AC voltage of Z-source inverter can be higher or lower than the input voltage as needed. Traditional voltage source inverter is Buck inverter, However Z-source inverter is Buck-Boost inverter. The DC voltage input range is wider than traditional voltage source inverter. There is no additional middle-class boost circuit in Z-source inverter but a Z-source network which is constituded of two inductor and capacitor elements.It is easy to modify the traditional inverter to Z-source inverter. The new inverter is low costs and improved efficiency of the new curcuit. These control systems which use traditional inverter can be upgraded to new systems which use Z-source inverter in low cost.The paper analyzes the shortage of traditional motor drive system, and the influence of the power supply fluctuation for mechanical characteristics of the electric motor. The paper introduces Z-source inverter instead of the traditional inverter. Z-source inverter power supply system consists of a DC power supply, Z-source network and the three-phase inverter bridge, which is increased of a Z-source network compared to traditional inverters.The control method of shoot through control is also introduced for Z-source inverter. The hardware and softwarw of traditional inverter are changed. By the introduction of Z-source inverter, the power supply of micro-electric vehicle motor drive system is changed. Z-source inverter closed-loop control is achieved by using fuzzy adaptive PID control algorithm. The stability of battery voltage is enhanced and the Z-source inverter has the ability of anti-distubance.Even if the battery voltage is varying, the motor drive system can get a stable power supply and the electirc vehicle can get a good dynamic performance.A simulation of the DC power supply voltage fluctuations carried out to verify the control method in Simulink. An experimental platform is builded to experiment the Z-source inverter closed-loop control algorithm.The results of simulation and experiment verifie the correct theory of Z-source inverter closed-loop control algorithm.By comparing the two systems of not using Z-source inverter motor vector control system and the system introduced Z source inverter, simulation results verify the improvement of introducing Z-source inverter to motor control system.