Analysis and Design of <i>LLC</i> Converter Considering Output Voltage Regulation Under No-Load Condition

Kim, Jong-Woo; Park, Moo-Hyun; Lee, Byoung-Hee; Lai, Jih‐Sheng

doi:10.1109/tpel.2019.2914375

Cited by 27 publications

(11 citation statements)

References 23 publications

(30 reference statements)

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“…As shown in Figure 6, the WPC WPT coils can be regarded as a transformer and an inductive WPT system can be driven by a series LLC resonance operation. The operation of the proposed circuit is similar to that of the conventional LLC resonance DC/DC converter [17]. The proposed circuit has four modes in operation, as shown in Figure 7.…”

Section: Llc Resonance Operationmentioning

confidence: 81%

“…In addition, when the distance from the transmitter to the receiver is within 2 mm via an over coupling condition, a series LLC resonant operation is suitable to recover output power with high efficiency. When there is the over coupling condition, the coils can be modeled with a magnetized inductor, a leakage inductor, and an ideal transformer and the series LLC resonance operation can be obtained [17]. The output voltage gain is about one and is affected by the load change in the over coupling condition.…”

Section: Introductionmentioning

confidence: 99%

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Output Voltage Analysis of Inductive Wireless Power Ttransfer with Series LC and LLC Resonance Operations Depending on Coupling Condition

2020

Electronics

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This paper analyzes the output voltage of an inductive wireless power transfer (WPT) depending on coupling conditions. When the optimum efficiency and maximum output power are obtained, it is called critical coupling, so the receiving coil and the transmitting coil should be separated by a certain distance. When the distance between the transmitting coil and receiving coil is very short, it is called over coupling, and output power decreases with the optimal operating state of the critical coupling condition. To design the entire circuit system for the inductive WPT depending on the coupling condition, it is beneficial to analyze the output voltage according to a load variation, an input voltage, and an operating frequency. Therefore, the output voltage depending on the coupling condition in the inductive WPT is analyzed in this paper. The output voltage gain in critical coupling condition is greater than one and is not affected by a load variation by a series LC resonant operation. The reduced output power in an over coupling condition can be recovered by a series LLC resonant operation. In addition, the output voltage gain is almost one and is affected by the load variation in the over coupling condition. A 5W prototype is implemented with the wireless power consortium standard coils and experimental results are shown to verify theoretical analysis and operation.

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Section: Llc Resonance Operationmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Output Voltage Analysis of Inductive Wireless Power Ttransfer with Series LC and LLC Resonance Operations Depending on Coupling Condition

2020

Electronics

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“…(7) Based on (7), the voltage conversion ratio of the proposed converter at three resonant points can be obtained in the following paragraphs.…”

Section: A Operation At Three Resonant Pointsmentioning

confidence: 99%

Series Resonant Converter With Multiple Resonant Points Using Sequential PWM for Electrical Vehicle On-Board Charger

2023

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In electric vehicle (EV) charging applications, maintaining high efficiency over a wide output voltage range is considered the most challenging mission. Pulse width modulation (PWM) controlled resonant converter can be a nice candidate, because its output voltage boosting capability is independent to the resonant tank components. However, it reveals its limitation showing efficiency drop between two resonant points. This paper proposes a resonant converter with "sequential PWM" achieving multiple resonant points while doubling the output voltage. The proposed converter significantly reduces turnoff loss and maximum resonant current by having multiple resonant points while doubling the output voltage. Accordingly, proposed converter maintains competitive high efficiency over a wide output voltage range.INDEX TERMS EV charger, resonant converter, wide voltage range 0

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“…It should be noted that in this example, the full transition of C 1 and C 2 from the upper voltage rail (V in ) to the lower voltage rail (GND) happens before the secondary side starts to commutate because C 1 and C 2 are relatively small size capacitors, and the turn-off current is relatively high. However, in other cases, the voltage transition of C 1 and C 2 can also overlap the commutation of the secondary side rectifiers [26].…”

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confidence: 99%

On the Practical Evaluation of the Switching Loss in the Secondary Side Rectifiers of LLC Converters

et al. 2021

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The switching loss of the secondary side rectifiers in LLC resonant converters can have a noticeable impact on the overall efficiency of the complete power supply and constrain the upper limit of the optimum switching frequencies of the converter. Two are the main contributions to the switching loss in the secondary side rectifiers: on the one hand, the reverse recovery loss (Qrr), most noticeably while operating above the series resonant frequency; and on the other hand, the output capacitance (Coss) hysteresis loss, not previously reported elsewhere, but present in all the operating modes of the converter (under and above the series resonant frequency). In this paper, a new technique is proposed for the measurement of the switching losses in the rectifiers of the LLC and other isolated converters. Moreover, two new circuits are introduced for the isolation and measurement of the Coss hysteresis loss, which can be applied to both high-voltage and low-voltage semiconductor devices. Finally, the analysis is experimentally demonstrated, characterizing the switching loss of the rectifiers in a 3 kW LLC converter (410 V input to 50 V output). Furthermore, the Coss hysteresis loss of several high-voltage and low-voltage devices is experimentally verified in the newly proposed measurement circuits.

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Analysis and Design of LLC Converter Considering Output Voltage Regulation Under No-Load Condition

Cited by 27 publications

References 23 publications

Output Voltage Analysis of Inductive Wireless Power Ttransfer with Series LC and LLC Resonance Operations Depending on Coupling Condition

Output Voltage Analysis of Inductive Wireless Power Ttransfer with Series LC and LLC Resonance Operations Depending on Coupling Condition

Series Resonant Converter With Multiple Resonant Points Using Sequential PWM for Electrical Vehicle On-Board Charger

On the Practical Evaluation of the Switching Loss in the Secondary Side Rectifiers of LLC Converters

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