TY - JOUR
T1 - Inductive Power Transfer Based on Variable Compensation Capacitance to Achieve an EV Charging Profile With Constant Optimum Load
AU - Grazian, Francesca
AU - Soeiro, Thiago Batista
AU - Bauer, Pavol
PY - 2023/2/1
Y1 - 2023/2/1
N2 - Wireless charging must be highly efficient throughout the entire battery charging profile to compete in the electric vehicle (EV) industry. Thus, optimum load matching is commonly used: it operates at the equivalent load that maximizes the efficiency, which depends on the coil's alignment. In this article, the optimum load is made independent of the coils' position by changing the system's resonant frequency through switch-controlled capacitors (SCCs). This eliminates the need for load-side voltage control. The output current follows the battery voltage rise during the battery charging cycle to always match the optimum load, which can be achieved by regulating the input voltage via the power factor correction (PFC) converter. This method is called here constant optimum load (COL). Two SCC topologies have been implemented in a 3.7-kW hardware demonstrator. The one implementing the half-wave modulation achieves higher efficiency than the one employing full-wave modulation, with 96.30% at 3.2 kW and aligned coils. When misalignment occurs, the half-wave modulation technique results in higher efficiency than the conventional-fixed compensation, where the efficiency is lower by up to 0.68% at partial load. Based on these results, the proposed COL method is proven suitable for 3.7-kW EV-static wireless charging achieving one of the highest peak efficiencies listed in today's literature for the same power class.
AB - Wireless charging must be highly efficient throughout the entire battery charging profile to compete in the electric vehicle (EV) industry. Thus, optimum load matching is commonly used: it operates at the equivalent load that maximizes the efficiency, which depends on the coil's alignment. In this article, the optimum load is made independent of the coils' position by changing the system's resonant frequency through switch-controlled capacitors (SCCs). This eliminates the need for load-side voltage control. The output current follows the battery voltage rise during the battery charging cycle to always match the optimum load, which can be achieved by regulating the input voltage via the power factor correction (PFC) converter. This method is called here constant optimum load (COL). Two SCC topologies have been implemented in a 3.7-kW hardware demonstrator. The one implementing the half-wave modulation achieves higher efficiency than the one employing full-wave modulation, with 96.30% at 3.2 kW and aligned coils. When misalignment occurs, the half-wave modulation technique results in higher efficiency than the conventional-fixed compensation, where the efficiency is lower by up to 0.68% at partial load. Based on these results, the proposed COL method is proven suitable for 3.7-kW EV-static wireless charging achieving one of the highest peak efficiencies listed in today's literature for the same power class.
KW - Compensation networks
KW - control
KW - inductive power transfer (IPT)
KW - magnetic resonant coupling
KW - optimum load matching
KW - soft switching
KW - switch-controlled capacitors (SCCs)
KW - wireless charging
KW - zero voltage switching (ZVS)
UR - http://www.scopus.com/inward/record.url?scp=85134220980&partnerID=8YFLogxK
U2 - 10.1109/JESTPE.2022.3188060
DO - 10.1109/JESTPE.2022.3188060
M3 - Article
AN - SCOPUS:85134220980
SN - 2168-6777
VL - 11
SP - 1230
EP - 1244
JO - IEEE Journal of Emerging and Selected Topics in Power Electronics
JF - IEEE Journal of Emerging and Selected Topics in Power Electronics
IS - 1
M1 - 9813693
ER -