| Due to the advantages of high power density,high efficiency and reliability,permanent magnet synchronous generators(PMSG)have been widely used in various industrial applications.Because of the full controllability and excellent performance,PWM rectifier is always linked to a PMSG,converting the AC power and providing DC power supply.For a generator system consisting of PMSG and PWM rectifier,a proper control strategy can realize rectifying and DC-link voltage stabilization as well as AC voltage stabilization between the machine winding terminals.Compared with other loads,battery load has its own particularity.During charging,the battery voltage varies with the state of charge(SOC)of the battery.The key point of this thesis is to study the PWM rectification control strategy of a wide-speed-range PMSG for a wide SOC range battery load.In this thesis,operation principle of the PMSG system with PWM rectifier and its vector control strategy are presented.Furthermore,using this generator system,the charging process of the lead-acid battery is analyzed.In order to realize constant-current charging of a battery with varying SOC by a wide-speed-range PMSG,a PWM rectifier control strategy is introduced,which is based on the traditional vector control and uses the DC charging current as the control variable of the outer control loop.Influence of the PMSG speed and the battery features is also investigated.To solve the problem of unstable DC charging current caused by the low SOC of battery or the over speed of PMSG,it is proposed to apply field-weakening control on the PWM rectifier,realizing stable operation over a wide speed range of the PMSG and a wide SOC range of the battery.In this thesis,simulation model of the PMSG system is built.The simulation results verify the effectiveness of the control strategy.The simulation results also show that the field-weakening control can solve the problem of unstable charging current of the low SOC battery.Finally,a scheme for charging of a battery with a varying SOC by a wide-speed-range PMSG is proposed,and verified with simulation. |
