Figures (7)  Tables (3)

    • Figure 1. 

      GUI of the standalone version of the real-time estimator of the parameters for coupled coils in an 11-kW wireless charging system.

    • Figure 2. 

      Equivalent circuit of the electromagnetic section of the IPT system.

    • Figure 3. 

      3D FEM model of the IPT system under consideration.

    • Figure 4. 

      Flowchart of the simulation and estimation processes.

    • Figure 5. 

      Relationships among the crucial parameters: (a) relationship between the self-inductance of individual coils and the number of turns, (b) relationship between mutual inductance and the number of turns, and (c) relationship between the coupling coefficient and the air gap.

    • Figure 6. 

      Power transfer efficiency $ {(\eta }_{\mathrm{t}\mathrm{r}}) $ as a function of the geometric mean of the Q-factors $ \text{(}{Q}_{\mathrm{g}\mathrm{m}}) $ and the coupling coefficient $ \text{(}k) $ of the coupled coils of an 11-kW IPT system for EVs obtained with the proposed real-time estimator.

    • Figure 7. 

      (a) Photograph of the laboratory prototype of an 11- kW IPT system for EVs. (b) Schematic diagram of the experimental setup. (c) Measured and estimated dependence of the coupling coefficient as a function of the air gap between the transmitting and receiving sides of the 11-kW IPT system.

    • Initial data Value
      Dimensions (metal screen) 450 mm × 690 mm × 5 mm
      Dimensions (coil) 380 mm × 380 mm × 5 mm
      Dimensions (ferrite) 126 mm × 28 mm × 20 mm (25 pieces)
      No. of turns 9.5, 10.5, ... 15.5
      Air gap (mm) 160, 180, ... 300
      Metal screen material Aluminum
      Coil material Copper (Litz wire, 0.1 mm × 2,500 strands)
      Ferrite material Manganese–zinc (N87)
      Frequency 85 kHz
      Boundary conditions Tangential fields (50% padding on all sides)
      Solver type Eddy current solver (low frequency)
      Output Discrete data table

      Table 1. 

      Initial data provided for 3D FEM simulation of the IPT system.

    • x (mm) Z11 L1 (μH) Z22 L2 (μH) Z21 M (μH)
      160 0.019 + 38.61i 72.3 0.032 + 38.19i 71.5 0.51 + 7.77i 14.56
      220 0.021 + 38.18i 71.4 0.028 + 37.43i 70.1 0.37 + 4.62i 8.65
      280 0.027 + 37.46i 70.1 0.026 + 37.26i 69.9 0.14 + 2.81i 5.26

      Table 2. 

      Measured Z-parameters and the calculated values of L1, L2 and M for different air gaps.

    • x (mm) k (estimated) k (measured) Error (%)
      160 0.2085 0.2025 2.9%
      180 0.1707 − −
      200 0.1465 − −
      220 0.1248 0.1222 2.1%
      240 0.1054 − −
      260 0.091 − −
      280 0.0763 0.0752 1.4%
      300 0.0653 − −

      Table 3. 

      Estimated and measured values of the coupling coefficient for different air gaps between the primary and secondary coils.