Advantages and Tuning of Zero Voltage Switching in a Wireless Power Transfer System

2020 IEEE 29th International Symposium on Industrial Electronics (ISIE)

Duijsen

Roodenburg

et al. 2020

Self Cite

In inductive power transfer applications that use resonant compensation networks, the commonly employed Hbridge inverter should be kept operating in soft-switching to ensure high power efficiency and low irradiated electromagnetic noise. To achieve so, the zero-crossing detection circuit for the resonant current or voltage must be fast and accurate in any operating condition. This paper researches the concept of an auto-resonant control for the typical H-bridge resonant converter used in wireless charging systems. In the method proposed here, the reference levels for the zero-crossing detection of the inverter's current are automatically adapted depending on the slope of the current itself at the zero-crossing. In this way, it is possible to compensate for the circuit delay even in the presence of parameters' variation and to ensure that the soft-switching is always maintained. The functionality of this control method is proven first mathematically, and then with circuit simulations. The core steps for the implementation are described with the support of functional blocks. Finally, the system start-up strategy is explained, which uses an auxiliary timed oscillator to modulate the inverter with a fixed 50% duty cycle at a higher frequency than the nominal. This guarantees that the start-up is in the inductive region and, thus, the zero-voltage switching turn-on. Once the detection circuits sense the current flow, the oscillator is automatically disabled, and the nominal power transfer starts. Index Terms-Control, inductive power transfer, inverter, softswitching, wireless charging, zero voltage switching.

Section: (Ground Reference Voltage) An Example Of Inverter Zcs Opementioning

confidence: 99%

Section: (Ground Reference Voltage) An Example Of Inverter Zcs Opementioning

confidence: 99%

Section: Creation Of the Control Signals To The Gate Driver Blockmentioning

confidence: 99%

“…8. The simulation has been executed with the main coils used in [6] connected to a S-S compensation network tuned at 85 kHz. Additionally, referring to Fig.…”

Section: Start-up Strategymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Auto-resonant Control of the H-Bridge Resonant Converter for Inductive Power Transfer Applications

2020 IEEE 29th International Symposium on Industrial Electronics (ISIE)

Duijsen

Roodenburg

et al. 2020

Self Cite

Compensation Network for a 7.7 kW Wireless Charging System that Uses Standardized Coils

2020 IEEE International Symposium on Circuits and Systems (ISCAS)

Shi

Soeiro

et al. 2020

Self Cite

Industrial wireless charging systems use standardized coils to guarantee interoperability between different manufacturers. In combination with these coils, the compensation network can still be designed and optimized. This paper explains the step-by-step design of the compensation network for a 7.7 kW wireless charging system (power class WPT2), which is composed of standardized coils. The compensation network must satisfy the output power and voltage requirements, the soft-switching of the inverter, and the limit of voltage and current stress on the components. The S-S compensation network is found to be unfeasible for those coils, and an optimized double-sided LCC compensation network is designed. The 3-phase grid connection is selected despite the 1-phase one because it gives the lowest total conduction losses. Finally, two parallel SiC MOSFETs C3M0075120K are chosen as inverter's switch because of their low conduction losses. This solution can achieve a payback time within a year with respect to the cheapest one.Index Terms-Compensation networks, electric vehicles (EVs), inductive power transfer, standardized coils, wireless charging.

Inductive Power Transfer Based on Variable Compensation Capacitance to Achieve an EV Charging Profile With Constant Optimum Load

IEEE J. Emerg. Sel. Topics Power Electron.

Soeiro

Bauer

2023

Self Cite

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.