Lithium Battery Model and Its Application to Parallel Charging

Shieh, Yueh-Tsung; Wu, Chih‐Chiang; Liu, Ching-Yao; Chieng, Wei-Hua; Jeng, Shyr-Long; Chang, En-Chih

doi:10.3390/en15134767

Cited by 9 publications

(2 citation statements)

References 21 publications

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“…The efficiency drop is due to the on-resistance loss of the D-mode GaN HEMT. The corresponding result for the parallel battery charging application using the D-mode GaN synchronous rectifiers will be reported in [26].…”

Section: Discussionmentioning

confidence: 99%

Flyback Converter Using a D-Mode GaN HEMT Synchronous Rectifier

Shieh

Liu

et al. 2022

Energies

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The flyback converter with its active cell balancing topology for charging lithium-based batteries in Electrical Vehicles (EV) have been adopted recently into the industry. Electrical Vehicle battery charging requires high current operation in continuous current mode and hence, the power loss on the Schottky diode rectifier on the secondary side determines the power conversion efficiency. The depletion mode (D-mode) GaN HEMT synchronous rectifier proposed in this paper has been used to replace the Schottky diode on the secondary side of the flyback converter in order to improve the power conversion efficiency. This synchronous rectifier regulates the forward voltage drop of an external switch to about 100 mV per ampere of current flow with no concern to threshold voltage. The first challenge of converting the D-mode GaN HEMT as a synchronous rectifier is that the normally-on device must be off when the primary side inductor of the flyback converter is initially charging the magnetic energy. That is, the rectifier must behave as the normally-off device during its initialization stage. The second challenge is that the D-mode GaN HEMT must switch off as soon as the secondary current becomes zero. The third challenge is posing a fast recovery feature to reduce the drain-source voltage rise on the primary side switch, which suffices to be the main reason as to why the D-mode GaN HEMT is used instead of MOS devices. The proposed depletion mode GaN HEMT synchronous rectifier is verified to be able to overcome all challenges and in result becomes a candidate for the synchronous rectifier.

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Section: Discussionmentioning

confidence: 99%

Flyback Converter Using a D-Mode GaN HEMT Synchronous Rectifier

Shieh

Liu

et al. 2022

Energies

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“…However, the steady-state analysis of the nonlinear network using the harmonic balance method is still an area open to the authors in the future. The battery voltage varied during battery charging due to its SOC (state-of-charge)-VOC (voltage-of-open-circuit) characteristics [29]. The subharmonic oscillation that resulted from both the PRU nonlinear network and the battery characteristics could be analyzed using the harmonic balance method.…”

Section: Methodsmentioning

confidence: 99%

Power Receiving Unit for High-Power Resonant Wireless Power Transfer

Liu,

Tang,

Shieh

et al. 2023

Energies

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A new power receiving unit (PRU) is proposed in this paper for resonant wireless power transfer (WPT), which is characterized by the capability of attracting high power from the power transmitting unit (PTU). The resonant WPT is designed for delivering the electrical power to the PRU attached on an electrical vehicle (EV) chassis 50 cm away from a PTU installed on the ground. The proposed PRU uses only the passive elements such as inductors, diodes, and capacitors, which need no initial power from the EV. It is then applicable for charging a battery to several hundred volts for even a first-time charging battery. For a resonant WPT at a switching frequency of 4 MHz, the proposed PRU behaves as a negative impedance converter (NIC) itself in the subharmonics of 4 MHz. The NIC effect plus the subharmonic oscillation causes an instability current charging the battery connected to the PRU. In this paper, we simulated the PRU and performed the experiment. The experiment demonstrated a battery charging of 150 W from 50 cm away using three D-mode GaN HEMT transistors via the instability current ramp. The power transfer efficiency (PTE) improved as the power delivered to the load (PDL) increased. The peak PTE was 65% in the present findings. The simulation analysis showed that the circuit allowed itself be used to much higher power transfer when it is implemented with more GaN HEMT transistors connected in parallel. The theoretical derivation of the PRU circuit is also used to support both the experimental and simulation results.

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