| ABSTRACT:Compared to traditional trolleybus, dual-source trolleybus can be operated in two modes:the grid connection mode and the off-grid mode, whose run lines are more flexible. This thesis mainly studied on control strategies of dual-source trolleybus drive system and composite power system, a topology of dual-source trolleybus and control strategies of composite power system is proposed.Combining with control strategies of permanent magnet synchronous motor drive system, a wide speed range of PMSM drive system is achieved by MATLAB simulation, and power performance and operational safety performance of dual-source trolleybus is improved. First, development history and trend of trolleybus is outlined, application background of dual-source trolleybus and vector control technologies of PMSM is introduced. For Some issues existing in traditional dual-source trolleybus, a preliminary solution is presented, that is dual-source trolleybus adopts a new power system composed of PMSM drive system and composite power system.Second, vector control strategies and mathematical model of PMSM is introduced, the impact of flux-weakening rate and salient rate on PMSM flux-weakening control performance is analyzed, and id=O control, MTPA control, single current regulator with voltage angle flux-weakening control (VAC-SCR), single current regulator with variable q-axis voltage flux-weakening control (VQV-SCR) and current lead angle flux-weakening control is analyzed. Based on this, the complete control strategy of PMSM drive system is determined-MTPA control adopted in the constant torque area and current lead angle flux-weakening control adopted in the constant power area.Third, the topology of composite power system is analyzed, a system topology of novel dual-source trolleybus is proposed, parameters of dual-source trolleybus drive system is calculated, and parameters of composite power is designed. Considering their different characteristics of batteries and supercapacitors, Control strategies of composite power system in different operating modes is proposed.Finally, PMSM drive system simulation model based on the rotor flux-field oriented control is built up. According to their simulation results, firstly, differences of id=O control and MTPA control is analyzed;Secondly, differences of VAC_SCR flux-weakening control, VQV_SCR flux-weakening control and current lead angle flux-weakening control is analyzed; simulation results of traditional and novel dual-source trolleybus is analyzed,and the impact of composite power system on power performance of dual-source trolleybus and transient performance of the DC grid is analyzed;Finally, the applicability of PMSM drive system control strategy and the effectiveness of composite power system control strategy is verified by simulation. |
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