## 2 DAB DC/DC Resonant Converter TPS Close Loop Control Scheme
### DAB LCC Resonant Converter Open Loop TPS Control Simulation Analysis
#### 2.6.3 DAB LCC Resonant Converter TPS PWM Modulation ZVS Switching Performance  
In the power switch ZVS performance study, the circuit simulation needs to be conducted using the circuit parameters and settings of the experimental setup. TPS PWM modulation ZVS switching performance is evaluated in PLECS circuit simulation for SiC MOSFET C3M0120090D with on-resistance Rds = 120 m\(\Omega\), output capacitance 40 pF, and SiC MOSFET body-diode forward voltage 4.8 V.  
In this study, the DAB DC output resistor is replaced with a DC voltage source from 20 V to 30 V to simulate the battery in different charging conditions. DAB DC input voltage is set to 30 V. The DC output voltage current feedback control is applied to regulate the inverter phase shift angle \(\beta\)p. Rectifier side R\({}_{\text{ac}}\) = 38 \(\Omega\) feedback control is applied to regulate the rectifier phase shift angle \(\beta\)s. The inverter-to-rectifier phase shift angle is manually set closer to \(\delta\) = 90\({}^{\circ}\). The PWM gating signal dead time is set to 200 ns. Figure 15 shows the simulation results when DC output voltage Vo = 20 V and DC output current Io = 0.4 A with \(\delta\) = 90\({}^{\circ}\). This simulation emulates the condition when R\({}_{\text{dc}}\) = 50 \(\Omega\) when the battery is working at the changing CC mode. The simulation results show that inverter/rectifier Leg 1 and Leg 2 are all working at ZVS switching. ZVS soft-switching is achieved when Sic MOSFET is switched on with the freewheeling current flows through its body-diode. In this operation condition, adding an extra inverter-to-rectifier  
Figure 14: Inverter/rectifier AC voltage/current and receiver winding voltage/current waveforms for same \(\beta\)p and \(\beta\)s and different \(\delta\) settings. phase with \(\delta=90+\Delta\delta\) (\(\Delta\delta>0\)) only causes extra reactive power to flow to/from the AC resonant circuit and reduces the power efficiency. Figure 16 shows the simulation results when DC output voltage Vo = 30 V and DC output current Io = 0.1 A with \(\delta=90^{\circ}\). This simulation case emulates \(\mathrm{R_{dc}}=300\ \Omega\) CV mode changing. The simulation results show that inverter Leg 2 and rectifier Leg 1 and Leg 2 work in ZVS switching. Inverter Leg 1 does not work in ZVS switching. Figure 17 shows the simulation results when DC output voltage Vo=30 V and DC output current Io = 0.1 A with \(\delta=120^{\circ}\). This simulation emulates \(\mathrm{R_{dc}}=300\ \Omega\) CV mode battery charging. The simulation results show that after setting \(\delta=90+\Delta\delta\) with \(\Delta\delta=30^{\circ}\)  
Figure 16: Inverter/rectifier voltage/current, MOSFET gating signals, diode currents PLECS circuit simulation results for Vo = 30 V, Io = 0.1 A (\(\mathrm{R_{dc}}=300\ \Omega\), emulate CV mode) with \(\beta\)p (\(\mathrm{deg}\)) = 48.3\({}^{\circ}\), \(\beta\)s (\(\mathrm{deg}\)) = 46.2\({}^{\circ}\), \(\delta\) (\(\mathrm{deg}\)) = 90\({}^{\circ}\). Figure 15: Inverter/rectifier voltage/current, MOSFET gating signals, diode currents PLECS circuit simulation results for Vo = 20 V, Io = 0.4 A (\(\mathrm{R_{dc}}=50\ \Omega\), emulate CC mode) with \(\beta\)p (\(\mathrm{deg}\)) = 82.3\({}^{\circ}\), \(\beta\)s (\(\mathrm{deg}\)) = 151, \(\delta\) (\(\mathrm{deg}\)) = 90\({}^{\circ}\). inverter Leg 2 and rectifier Leg 1 and Leg 2 are working in ZVS switching. Inverter Leg 2 is marginally working in ZVS switching. For the proposed TPS closed-loop control, the simulation study shows that when the inverter-to-rectifier phase shift angle is set to \(\delta=90^{\circ}\), both inverter and rectifier work at ZVS soft-switching mode with unity power factor in CC mode charging. However, in CV mode charging, the inverter-to-rectifier phase shift angle \(\delta\) needs to increase to meet the ZVS condition. The cost paid is that the inverter and rectifier will deviate from ZPA operation with extra reactive power to/from the resonant circuit, which may increase the loss of the LCC resonant circuit.