Development of a New Integrated Energy Exchanger for Electric Vehicle Charging Station

(1) Scheme design and hardware implementation of a 60-kW highly integrated energy exchanger for EV charging station (Milestone 1). The main topology of the highly integrated energy exchanger for EV charging station is a matrix converter-based dual outputs multi-directional power electronics system. The charging system has two output ports. Each output port can be configured for cable charging mode or wireless charging mode. First, when compared with conventional EV charging topologies, the proposed matrix converter-based topology can directly convert the AC power of the grid into the high-frequency AC power required by the high-frequency transformer. So, it can reduce the usage of bulky DC bus capacitors with relatively short lifespan, which improves the overall life and reliability of the charging station. Second, the energy flow among the grid and the two output ports is multi-directional to support the cable charging, wireless charging, V2G and V2V operations. Third, the cable charging mode and wireless charging mode share the same set of power electronic devices. Compared to the separate cable charging and the wireless charging approach, the proposed integrated charging system can save about 20%-30% power devices. Fourth, the materials used in this system such as Litz wire, GaN and SiC will be carefully considered to balance the cost and performance. When configured in the wired charging mode, each port can provide EVs with 30 kW power. While configured in wireless charging mode, each port can provide EVs 6.6 kW power. The charing voltage for the wired charging and wireless charging could be around 450V or/and 350V, which is according to the specific design of the energy exchanger. (2) Optimized component design of the integrated energy exchanger (Milestone 2). When the overall charging system is fully developed, the necessary optimizations will be carried out to make this system more practical and efficient. Design and simulation tools, such as MATLAB, JMAG and other design tools, will be conducted to support the optimizations. Also, the Nanocrystal material will be used to reduce the size of the grid-side filters, transformers and the coils. And the magnetic component sharing technology will be used to maximize the utilization of magnetic cores and further reduce the overall size of the charging system. Besides, the anti-misalignment ability of the wireless charging function can be improved with switching frequency technology. The efficiency, charging power, size of system, etc., can be further improved by at least 10%, respectively. (3) Development of control strategies to achieve multi-functions of proposed integrated energy exchanger (Milestone 3). The designed multi-functional energy exchanger can support the cable charging, wireless charging, V2G and V2V functions, which highly requires the grid synchronization and precise power flow control. First, the robust phase-locked loop will be used to track the amplitude and phase of the grid-side voltage even under the case of grid voltage distortion. Second, the voltage control with highly reliable commutation strategy will be implemented in matrix converter, which ensures the unit power factor and system reliability. Third, the well-tuned phase-shift control will be designed based on system model to regulate the power flow among the power grid and the two output ports. Both simulations and experiments will be conducted to verify the effectiveness and robustness of the control strategies. (4) Test reports of the integrated energy exchanger (Milestone 3). Based on the developed hardware and software, a series of tests will be carried out to verify the reliability and qualification of the charging station. For example, the aging test will be used to test the ability of the system to run continuously and stably. And the electric withstand test will be used to test the reliability of electrical isolation. Moreover, the EMI and EMC tests will be used to test the EMI and anti EMI characteristics. According to these testing results, modifications and optimizations will be conducted to make sure the proposed energy exchanger meet the standards, such as IEC 61980-1/ISO 19363 for EV wireless charging, IEC 61851/SAE J1772 for EV conductive charging, and IEC 61000 for EMC standard.