This paper proposes a new capacitive coupling wireless power transfer method for charging electric vehicles. Capacitive coupling wireless power transfer can replace conventional inductive coupling wireless power transfer because it has negligible eddy-current loss, relatively low cost and weight, and good misalignment performance. However, capacitive coupling wireless power transfer has a limitation in charging electric vehicles due to too small coupling capacitance via air with a very high frequency operation. The new capacitive wireless power transfer uses glass as a dielectric layer in a vehicle. The area and dielectric permittivity of a vehicle’s glass is large; hence, a high capacity coupling capacitor can be obtained. In addition, switching losses of a power conversion circuit are reduced by quasi-LLC resonant operation with two transformers. As a result, the proposed system can transfer large power and has high efficiency. A 1.6 kW prototype was designed to verify the operation and features of the proposed system, and it has a high efficiency of 96%.
A new high efficiency zero-voltage and zero-current switching (ZVZCS) bidirectional DC/DC converter is proposed in this paper. The proposed converter consists of two half-bridge cells as the input and output stages, symmetrically. MOSFETs of input stage are turned-on in ZVS condition, and those of output stage are turned-off in ZCS condition. In addition, MOSFETs of input and output stages have low voltage stresses clamped to input and output voltage, respectively. Therefore, the proposed converter has high efficiency and high power density. The operational principles are analyzed and the advantages of the proposed converter are described. The 300W prototype of the proposed converter is implemented for 42V hybrid electric vehicle (HEV) application in order to verify the operational principles and advantages.
Commercial home appliances using remotely controlled systems consume electric power while in standby mode to prepare for receiving a remote turn-on signal. The proposed power system can significantly reduce standby power consumption without increasing cost. Furthermore, since a Electronic Double Layer Capacitor (EDLC) is used as an auxiliary power storage element, the life cycle is longer and system reliability can be better than with existing approaches. When the energy of the EDLC is not sufficient for turning on the appliance, the power system charges the EDLC without affecting the main system. The proposed power system is verified with a commercial LCD TV and a 3.93mW standby consumption is obtained. This standby consumption can be regarded as zero standby equipment according to the IEC-62031 standard.
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.
Fig. 4. Output current for a reference step.valve is much lower. Simulations and experimental measurements show a mean switching frequency of the semiconductors lower than 2 kHz for the sampling rate previously mentioned. This switching frequency is suitable for modern converters with IGBTs and a rated output on the order of hundred kilovolt-amperes.
VI. CONCLUSIONIn this paper, a predictive control strategy has been presented which permits simple but effective control of a CSR. This control scheme uses a discrete-time model of the converter and a quality function. The main idea relies on predicting the best suited switching state which has to be applied in the next sampling period. Both dynamic and stationary behaviors have been experimentally analyzed. The measured output current follows the reference current very closely, even under transient conditions, which corroborates the good dynamics provided with the proposal. Furthermore, the condition of unity displacement power factor has also been achieved.
APPENDIXThe parameters of the rectifier are the following:
Mains FilterLoad
REFERENCES[1] S. Rees, "New cascaded control system for current-source rectifiers,"Abstract-An LLC series-resonant converter has many unique characteristics and improvements over pulsewidth-modulation topologies. However, many output capacitors are needed in parallel to satisfy an output voltage ripple and a rated ripple current of the capacitors. This paper deals with a novel two-phase interleaved LLC resonant converter using a phase of the resonant capacitor. The proposed converter satisfies low output-voltage ripple requirement and meets the rated ripple of output capacitor's current with few output capacitors. The operation and features are considered in detail, and a prototype with a 12-V-100-A output is investigated.Index Terms-Interleaving operation, LLC series-resonant converter (LLC-SRC), phase of the resonant capacitor.
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