Phase-shift interleaving control of variable-phase switched-capacitor converters

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A study of high-frequency-fed AC-DC converter with different DC-DC topologies

In this paper, the operation of high-frequency-fed AC-DC converters with different types of DC-DC topologies is presented. Based on the commonly used DC-DC converter topologies, the possibilities of new converter structure are investigated. Using buck and ZETA topologies as examples, the output voltage gain, output load range and switch stress of the converters are analytically studied. Both converter implementation examples will be given and experimentally demonstrated. © IEEE.published_or_final_versio

A tunable common mode inductor with an auxiliary winding network

Paper 1593Track no. 5 - Devices and ComponentsIn conventional switching converter, the parasitic capacitance between switching circuit and ground introduces common mode (CM) noise problem. A CM inductor is inserted in the power feeding paths to produce a high impedance to attenuate the CM noise. However, this parasitic capacitance and the CM inductor create low-frequency resonance near the switching frequency and its harmonics. Thus, the filtering performance is diminished. Increasing the CM inductance to shift the resonant frequency to low-frequency range is one of the methods to tackle this problem. However, this approach leads to increase the power losses (both core and winding losses) of the CM inductor reducing the efficiency of the converter. In this paper, a tunable CM inductor with a small-space auxiliary winding is proposed. The auxiliary winding can be connected to a passive network to alter the frequency response of the CM inductor without affecting the original inductance. As a result, the influence of the low-frequency resonance can be mitigated. A proof-of-concept protytpe is constructed and its performance is experimentally measured. Results show that the proposed tunable CM inductor operates as theoretically anticipated. © IEEE.published_or_final_versio

Switched-capacitor converters with multiphase interleaving control

This paper proposes a configuration of switched-capacitor converters with multiphase interleaving control that can perform conventional switched-capacitor voltage conversions with little electromagnetic interference over a wide range of operating condition. This is achieved by having multiple units of switched-capacitor converter connected in parallel and a unit selection control scheme which works along the interleaving control to vary the number of converters in operation. By having the capacitors of inactive units connected to the output and the converters operating with output interleaving operation, the output capacitor that is typically required in switched-capacitor converters for maintaining a small voltage ripple is made redundant in this configuration. © 2011 IEEE.link_to_subscribed_fulltex

High-Frequency-Fed Unity Power-Factor AC-DC Power Converter with One Switching Per Cycle

This paper presents a power converter and its control circuit for high-frequency-fed AC to DC conversion. Based on the resonant technique, the input current is shaped to be sinusoidal and is forced to follow the high-frequency sinusoidal input voltage so as to achieve unity power factor. With the proper selection of the characteristic impedance of the resonant tank, the converter is able to perform the function of a buck, boost or buck-boost converter. The initial condition of the resonant tank is used to control the output voltage gain of the converter. Since all the switches are operated at the fundamental frequency of the input AC source, the switching loss of the converter is small. A control scheme is also proposed for the converter. A proof-of-concept prototype operating at 400 kHz is constructed and its performance is experimentally measured. Results show that the proposed converter operates as theoretically anticipate

Design a high-frequency-fed unity power-factor AC-DC power converter for wireless power transfer application

This paper presents the design procedures of an unity-power-factor AC-DC power converter for wireless power transfer application. This newly proposed AC-DC converter consists of two stages: the PFC front stage uses LC series resonant circuit to perform power factor conditioning and the second stage uses a DC-DC converter to regulate the output voltage. New equations to describe the input impedance and power transfer characteristics of the converter have been developed. These new equations are used to formulated the design procedures of the converter. To verify, a proof-of-concept prototype is built and incorporated into a two coils wireless power transfer system. The system operates at 100 kHz to deliver 20 W to a remote load with a separation distance of 7.5 cm between the transmitter and receiver. The measured results are well agreed with the design specifications and theoretical anticipation. © 2015 IEEE.Link_to_subscribed_fulltex

Dynamic improvement of series-series compensated wireless power transfer systems using discrete sliding mode control

This paper presents a discrete sliding mode control (DSMC) scheme for a series-series compensated wireless power transfer (WPT) system to achieve fast maximum energy efficiency (MEE) tracking and output voltage regulation. The power transmitter of the adopted WPT system comprises a dc/ac converter, which incorporates the hill-climbing-search-based phase angle control in achieving minimum input current injection from its dc source, thereby attaining minimum input power operation. The power receiver comprises a buck-boost converter that emulates an optimal load value, following the MEE point determined by the DSMC scheme. With this WPT system, no direct communication means is required between the transmitter and the receiver. Therefore, the implementation cost of this system is potentially lower and annoying communication delays, which deteriorate control performance, are absent. Both the simulation and experiment results show that this WPT system displays better dynamic regulation of the output voltage during MEE tracking when it is controlled by DSMC, as compared to that controlled by the conventional discrete proportional-integral (PI) control. Such an improvement prevents the load from sustaining undesirable overshoot/undershoot during transient states

Interleaved switched-capacitor converters with adaptive control

The switched-capacitor converters are ideal switching-mode power supplies for consumers portable electronic devices due to their light weight, small size, and high power density. However, they suffer from a discontinuous input current waveform with large di/dt, which leads to significant electromagnetic interference (EMI) emission. This paper proposes a configuration of switched-capacitor converters connected in parallel, with their inputs and outputs interleaved and adaptively controlled. The interleaving operation is performed by using an original type of control in which both the capacitors' charging time T on and switching frequency are adjusted to get the line and load regulation. It is shown that, for a given range of variation of the supply voltage and load, there always exists a solution [T on, T S] assuring both output voltage regulation and a perfect interleaving. Experimental results are provided to validate the feasibility of the proposed scheme. Precise interleaving and good line and load regulation are maintained for all the designated range, including the transient times. © 2010 IEEE.link_to_subscribed_fulltex

Adaptive mixed on-time and switching frequency control of a system of interleaved switched-capacitor converters

The switched-capacitor (SC) converters are ideal switching-mode power supplies for consumer portable electronic devices due to their nature of being light weight, small size, and high-power density. However, they suffer from a discontinuous input-current waveform with large di/dt, which leads to significant electromagnetic interference emission. This paper proposes a configuration of SC converters connected in parallel, with their inputs and outputs interleaved and adaptively controlled. The interleaving operation is performed by using an original type of control in which both the capacitors charging time T ON and switching frequency are adjusted to get the line and load regulation. It is shown that, for a given range of variation of the supply voltage and load, there always exists a solution [T ON, T S] that assures both output-voltage regulation and perfect interleaving. Experimental results are provided to validate the feasibility of the proposed scheme. Precise interleaving, and good line and load regulation are maintained for all the designated range, including the transient periods. © 2006 IEEE.link_to_subscribed_fulltex

Switched-capacitor converter configuration with low EMI emission obtained by interleaving and its large-signal modeling

The switched-capacitor converters are ideal switching-mode power supplies for portable electronic consumers due to their light weight, small size, and high power density. However, they suffer from a discontinuous input current waveform with large di/dt, what leads to significant electromagnetic interference (EMI) emission. This paper proposes a configuration of switched-capacitor converters connected in parallel with their inputs and outputs interleaved. The interleaving times are calculated by taking into account the fast capacitor-charging characteristic, and the need to have the nominal operating point on its linear part for increasing the regulation range at changes in the input voltage and load. To improve control performance and avoid the use of small-signal linearization in the control design, a large-signal approach is adopted for modeling the converter, allowing for a design of a sliding mode control. ©2009 IEEE.link_to_subscribed_fulltex