# TAB Series-Resonant DC-DC Converter and Multi-Phase-Shift Based Global Optimization Modulation
## 4 Experimental Results and Analysis
Since \(k_{1}\) and \(k_{2}\) are both greater than 1 in this state, the RMS value of the transformer current is minimized when the RMS value of \(v_{\rm{AB}}\) and \(v_{\rm{CD}}\) is the maximum. Hence, the optimized modulation is simplified into SPS modulation. The above experimental results show that the RMS value of the transformer current under the optimized modulation is effectively reduced compared with the SPS modulation in the entire power range. Hence, the power loss of the converter is reduced. Figure 11: Experimental results with k1 > 1 of state 2 in the forward mode. (**a**) Optimized modulation, (**b**) SPS modulation. Figure 10: Experimental results with k1 < 1 of state 2 in the forward mode. (**a**) Optimized modulation, (**b**) SPS modulation. Then, the effectiveness of the power decoupling and the optimized modulation of both port 1 and port 2 operating at the backward mode are tested. Figure 13a shows the experimental results when the desired \(i_{2}\) remains constant while \(i_{1}\) is suddenly stepped. From Figure 13a, when \(i_{1}\) is suddenly stepped, the actual \(i_{2}\) remains constant. It means the proposed converter realizes the power decoupling in this case. Figure 13b shows the experimental results of the conventional TAB converter under the same conditions. From Figure 13b, \(i_{2}\) varies when \(i_{1}\) is stepped. Next, take state 1 as an example to test the optimized modulation. The steady-state waveforms are shown in Figure 7:0 Both port 1 and port 2 operate at the minimum transformer current and the RMS value of the transformer current is effectively reduced compared with the SPS modulation. Similarly, the dynamic waveforms of port 1 operate in the forward mode and port 2 operating in the backward mode are shown in Figure 7:1 The corresponding steady-state waveforms under the optimized modulation are shown in Figure 7:2 These experimental results verify the converter eliminates the power coupling between port 1 and port 2 and reduces the RMS value of the transformer current under the hybrid mode. Figure 7:3 Experimental results of proposed converter in the backward mode. (**a**) Optimized modulation, (**b**) SPS modulation. Figure 7:4 Experimental results of state 4 in the forward mode. Figure 7:5 Experimental results in the backward mode. (**a**) Proposed converter, (**b**) TAB resonant converter without decoupling tank. From the above experimental results, the proposed topology realizes the power decoupling, and the proposed modulation also significantly reduces the transformer current, in the entire power range and various operation modes. Finally, take both port 1 and port 2 operating at the forward mode as an example to test the efficiency of the proposed converter under the proposed modulation and SPS modulation. The efficiency is tested and compared in the different states. The efficiency curves in the state of \(k_{1}<1\) and \(k_{2}<1\) are shown in Figure 17a. The efficiency curves in the state of \(k_{1}>1\) and \(k_{2}<1\) are shown in Figure 17b. It can be seen that the efficiency is all over 88% in the different states. Compared with the SPS modulation, the efficiency of the optimized modulation is effectively increased in a wide range of the transfer power and the voltage gain.