Alireza Dayerizadeh Principle Investigator: Dr. Srdjan Lukić

Transcription

1 Dynamic Wireless Charging for Electric Vehicles: Approaches for Reflexive Field Containment Using Reactive Components NCSU Invention Disclosure: Alireza Dayerizadeh Principle Investigator: Dr. Srdjan Lukić 1

2 Dynamic Wireless Power Transfer Wireless Power Transfer: An Alternative to Conductive Charging. Source to load efficiencies of over 90% are possible at coupling coefficients of 0.2. Why Dynamic Wireless Power Transfer? Increased range and reduced charging times. Reduced vehicle energy storage requirements Electric-vehiclenews.com. (2018). UK To Test Dynamic Wireless Charging For Electric Cars. [online] Available at: 2

3 Dynamic Wireless Power Transfer Dynamic WPT may be accomplished through an array of segmented transmitting coils that sequentially couple to a passing receiving coil, thus isolating the field emissions to the coupled coil. Challenges include: Precise Receiver Position Feedback is required. Efficient and fast methodology to selectively energize coupled coil. 3

4 Dynamic Approach One Position sensor and relays for power flow control to coupled coils. 4

5 Dynamic Approach Two Power each coil with a dedicated inverter (cost prohibitive in large applications). 5

6 Dynamic Approach Two Exploit reflected impedance of receiving coil to control emitted field reflexively 6

7 Reflexive Field Containment Approach Series-Parallel-LCC M C 1 ( wm) M R wm wm Zreflected = = n - n j = ( QTotal - n j) Z L L L eq 2 2 s s s s C p When Uncoupled L p L s C 2 R eq Large uncompensated reactance ln uncoupled TX coils C pn When Coupled Inverter L F C F C comp C p1 L p1 C p2 L p2 L pn Reflected reactance brings TX coil into resonance Current flow is boosted Allows for Segmented TX Coils 7

8 Transmitter Design I S Uncoupled Coupled L F C F V s ΔX R r C comp ICcomp It,uncoupled It,coupled I tuncoupled, Vs = j D X I t, coupled = V R s r 8

9 Improving Field Containment Transmitter M Receiver C p L max C 1 Lp C2 V in Saturable Inductor increases reactance in TX coil. L s R eq The Saturable inductor: Maximizes the difference between coupled and uncoupled currents in the TX coil. Saturates as the system becomes coupled. Improves system current gain (and field attenuation performance). L Max 9

10 Saturable Inductor Characteristics AC current means that inductor is not continuously saturated. Inductance must be modelled to account for AC saturation behavior. L eff 2L I I I = + - p I I I max -1 2 [ sin ( sat ) sat 1 ( sat ) ] peak peak peak L eff 4L = p I I max -1 sat [ sin ( )] peak 10

11 Simulation Comparison to Reference System ReferenceSystem System With Saturable Inductor Currentgain11 Currentgain 3 11

12 Hardware Validation Inverter Output Voltage and Current- Uncoupled Transmitter (TX)* L p C p L max L eff C sat 190uH 22.65nF 180uH 23uH 143nF Receiver System L s C 1 C 2 237uH 16.56nF 82.81nF n 6 R Load 7.5 Inverter Output Voltage and Current- Coupled Input Voltage V Input Current 8.65 A Input Power 1480 W Output Power W (95.2^2/7.5) Efficiency 81.6% Current Gain

13 Conclusion Entirely passive field containment approach for the dynamic charging of electric vehicles. Builds upon previously published work. Impacts Aid in the proliferation of electric vehicles. Aids in the meeting of field emissions standards. Technology may be used in: autonomous vehicles and consumer electronics. 13