Figures (9)  Tables (2)

    • Figure 1. 

      The 3D EM modeling of the proposed concentric dual-band inductors.

    • Figure 2. 

      Combined wireless power transfer system block diagram with blocking filter.

    • Figure 3. 

      Qi sub-system analog automatic-tracking resonance lock loop.

    • Figure 4. 

      High-speed A4WP sub-system resonance lock loop.

    • Figure 5. 

      (a) The bode diagram of Q factor of parallel LC filter by varying internal resistance of the inductor. (b) The bode diagram of Q factor of parallel LC filter by varying inductance value and capacitance value according to the resonance condition at 6.78 MHz.

    • Figure 6. 

      Experimental prototype of the proposed combo system on a ferrite shield.

    • Figure 7. 

      The measured total RX power with respect to the position of receiver coil for all three types of transmitters.

    • Figure 8. 

      (a) The measured output voltage and transmitter coil currents without parallel LC resonant filter. (b) With the blocking resonant filter in place.

    • Figure 9. 

      Measurement results for output power versus 30-turn fixed coil radius.

    • Symbol Parameter values
      Ca4wp 76 pF
      La4wp 7.6 μH
      Cqi 7 nF
      Lqi 68 μH
      C6.78 MHz 95 pF
      L6.78 MHz 4.7 μH
      ESRL6.78 MHz 3 mOhm

      Table 1. 

      Optimized component values for the proposed combo system

    • Literature Operating frequency Rx coil size (mm) Output power (mW) Efficiency (%)
      [22] 8.3 MHz 13 28.3 50
      [23] 742 KHz 19 33 85
      [24] 13.56 MHz 10 NA 73.46
      [25] 13.56 MHz 10 NA 27.7
      [26] 3.5 MHz 12.5 1.05 30.97
      This work 230 KHz + 6.78 MHz 13 44.64 15

      Table 2. 

      Performance comparison with respect to various other studies in the literature