A new phase-controlled parallel resonant converter

A phase-controlled resonant converter was obtained by connecting in parallel the AC loads of two identical parallel resonant inverters. A phase shift between the drive signals of the two inverters controls the amplitude of the output voltage of the new inverter. A voltage-driven rectifier is used as an AC load of the inverter, which results in a phase-controlled parallel resonant DC-DC converter. A frequency-domain analysis is performed for the steady-state operation of the inverter, and two types of voltage-driven rectifiers and design equations are derived. The converter can be operated at a constant switching frequency, which reduces EMI problems. It is found that for switching frequencies higher than the resonant frequency by a factor of 1.07, the load of each switching leg is inductive. The converter is capable of regulating the output voltage in the range of load resistance from full-load to no-load. Experimental results are presented for a prototype of the phase-controlled parallel resonant converter with a center-taped rectifier tested at an output power of 50 W and a switching frequency of 116 kHz     

Analysis of phase-controlled resonant DC-AC inverters with class Eamplifier and frequency multipliers

This paper presents a minute analysis and experimental results of phase-controlled resonant DC-AC inverters with class E amplifiers and frequency multipliers. The circuit is composed of two identical class E amplifiers or frequency multipliers, which are used as DC-AC inverters and connected in parallel. The two inverters are driven at the same switching frequency, and the overall output power of the circuit can be controlled by varying the phase shift between the drive voltages of the two inverters. The circuit can regulate the output voltage at a constant switching frequency. The measured efficiency was over 93% at an output power of 0.98 W and a switching frequency of 0.5 MHz for both of the inverters with amplifier and frequency doubler     

Analysis, design, and resonant current control for a 1-MHzhigh-power-factor rectifier

Fundamental frequency analysis is used to examine the LCC series-parallel loaded resonant converter with a capacitive output filter when operating as a high-power-factor rectifier. Optimum values are identified for the Q factor and voltage conversion ratio such that zero-voltage switching is just maintained, while minimizing the resonant circuit conduction losses. A simple resonant current control loop is shown to provide an effective mechanism of active control, achieving a high-quality input current waveform over a wide load range. Results are presented from a 1 MHz 160 W prototype     

Fixed-frequency phase-controlled full-bridge resonant converterwith a series load

A fixed-frequency phase-controlled full-bridge parallel resonant converter (PCPRC) that consists of a phase-controlled parallel resonant inverter (PCPRI) and an input-inductor rectifier is analyzed. The input impedances of the resonant circuits represent inductive loads for both switching legs at f/f₀>1.24 and therefore zero-voltage-switching turn-on can be achieved for all the transistors. The fundamental frequency approximation is used to derive expressions for the voltage transfer function and the efficiency of the PCPRI. The behavior and performance characteristics of the PCPRI are then studied. Three types of input-inductor rectifiers are considered and a design procedure is developed. A 30 W PCPRC is designed and tested. The theoretical calculations were in good agreement with experimental results. The converter exhibits an excellent efficiency. The measured efficiency was 92% at full load. The converter is capable of regulating the DC output voltage from full load to no load and over a wide line voltage range     

串并联谐振变换器是电除尘器电源的最佳选择

文章从电除尘器机理和粉尘的比电阻的分析与节能减排的要求出发,指出高频高压直流开关电源和直流脉冲电源是ESP电源发展的两个方向。并进一步分析和比较了各种谐振变换器的特点,从而论证了串并联谐振变换器（SPRC）是电除尘器（ESP）电源的最佳选择。     

Soft switching resonant converter with duty-cycle control in DC micro-grid system

Resonant converter has been widely used for the benefits of low switching losses and high circuit efficiency. However, the wide frequency variation is the main drawback of resonant converter. This paper studies a new modular resonant converter with duty-cycle control to overcome this problem and realise the advantages of low switching losses, no reverse recovery current loss, balance input split voltages and constant frequency operation for medium voltage direct currentgrid or system network. Series full-bridge (FB) converters are used in the studied circuit in order to reduce the voltage stresses and power rating on power semiconductors. Flying capacitor is used between two FB converters to balance input split voltages. Two circuit modules are paralleled on the secondary side to lessen the current rating of rectifier diodes and the size of magnetic components. The resonant tank is operated at inductive load circuit to help power switches to be turned on at zero voltage with wide load range. The pulse-width modulation scheme is used to regulate output voltage. Experimental verifications are provided to show the performance of the proposed circuit.     

A New PWM-Controlled Quasi-Resonant Converter for a High Efficiency PDP Sustaining Power Module

A new pulsewidth modulation (PWM)-controlled quasi-resonant converter for a high-efficiency plasma display panel (PDP) sustaining power module is proposed in this paper. The load regulation of the proposed converter can be achieved by controlling the ripple of the resonant voltage across the primary resonant capacitor with a bidirectional auxiliary circuit, while the main switches are operating at a fixed duty ratio and fixed switching frequency. Hence, the waveforms of the currents can be expected to be optimized from the view-point of conduction loss. Furthermore, the proposed converter has good zero-voltage switching (ZVS) capability, simple control circuits, no hign-voltage ringing problem of rectifier diodes, no dc offset of the magnetizing current and low-voltage stresses of power switches. Thus, the proposed converter shows higher efficiency than that of a half-bridge LLC resonant converter under light load condition. Although it shows the lower efficiency at heavy load, because of the increased power loss in auxiliary circuit, it still shows the high efficiency around 94%. In this paper, operational principles, features of the proposed converter, and analysis and design considerations are presented. Experimental results demonstrate that the output voltage can be controlled well by the auxiliary circuit using the PWM method.      

New method of power control for series-parallel load-resonantconverters maintaining zero-current switching and unity power factoroperation

A power supply incorporating a series-parallel load-resonant converter capable of efficient operation over a wide range of output power is presented. The series-parallel resonant converter is shown to have three resonant frequencies. Operation of the circuit at each of these resonant frequencies maintains zero-current switching and high-frequency operation. The resonant circuit is designed to have different circuit resistances at each resonant frequency. The power delivered to the circuit, and hence the load, will therefore vary depending on which resonant frequency the circuit is excited at. This is the basis of a new method of power control for load-resonant converters disclosed in this paper. A welding power supply is designed and constructed which delivers pulsed output currents of 150 A while operating at 100 kHz and 60 A at 65 kHz. The power supply contains an active rectifier and draws near unity power factor     

A planar 4.5-GHz DC-DC power converter

In this paper, we present two DC-DC converters that operate at a microwave frequency. The first converter consists of a class-E switched-mode microwave amplifier, which performs the DC-AC conversion, and two half-wave diode rectifier outputs. The class-E MESFET amplifier has a minimum power-added efficiency of 86%, corresponding drain efficiency of 95%, and 120 mW of output power at 4.5 GHz. The diode rectifier has a maximum conversion efficiency of 98% and an overall efficiency of 83%. The second converter consists of a high-efficiency class-E oscillator and a diode rectifier. The class-E oscillator has a maximum efficiency of 57% and maximum output power of 725 mW. The DC-DC converter is planar and compact, with no magnetic components, and with a maximum overall DC-DC conversion efficiency of 64% for a DC input of 3 V, and the output voltage across a 87-Ω load of 2.15 V     

An isolated bridgeless AC-DC PFC converter using a LC resonant voltage doubler rectifier

This paper proposed an isolated bridgeless AC–DC power factor correction (PFC) converter using a LC resonant voltage doubler rectifier. The proposed converter is based on isolated conventional single-ended primary inductance converter (SEPIC) PFC converter. The conduction loss of rectification is reduced than a conventional one because the proposed converter is designed to eliminate a full-bridge rectifier at an input stage. Moreover, for zero-current switching (ZCS) operation and low voltage stresses of output diodes, the secondary of the proposed converter is designed as voltage doubler with a LC resonant tank. Additionally, an input–output electrical isolation is provided for safety standard. In conclusion, high power factor is achieved and efficiency is improved. The operational principles, steady-state analysis and design equations of the proposed converter are described in detail. Experimental results from a 60 W prototype at a constant switching frequency 100 kHz are presented to verify the performance of the proposed converter.     

Three-level LLC series resonant DC/DC converter

Paper presents a three-level soft switching LLC series resonant dc/dc converter. Zero-voltage switching (ZVS) is achieved for each main switch without any auxiliary circuit. Voltage stress of each main switch is half of input voltage. Zero-current-switching (ZCS) is achieved for rectifier diodes. Wide input/output range can be achieved under low frequency range because of two-stage resonance. Only one magnetic component is required in this converter. Efficiency is higher in high line input, so this converter is a preferable candidate for power products with the requirement of hold up time. For design convenience, relationship between dc gain and switching frequency, load resistance is deduced. Its open load characteristic and short load characteristic are exposed to provide theory basis for no load operation and over current protection. Design consideration of four dead times is presented to assure that voltage stress for main switches is within half of input voltage and ZVS for each main switch is achieved. Finally the principle of operation and the characteristics of the presented converter are verified on a 500V-700V input 54V/10A output experimental prototype, whose efficiency reaches 94.7% under rating condition.     

New high power DC-DC converter with loss limited switching and lossless secondary clamp

A new isolated high frequency high power DC-DC converter full bridge topology employing one resonant "soft" switching pole that is zero voltage switched and one phase-shifted hard switching pole with loss limited switching for primary switching is presented. The devices in the loss limited pole do not have resonant capacitors across them, but exhibit significantly lower losses than conventional hard switching as the energy dissipation is limited by the finite energy stored in the leakage inductance. This unique combination of zero voltage switching and loss limited switching reduces the switching loss in all primary devices to lower levels. Isolation is achieved by a coaxially wound high frequency transformer with ultra low leakage which increases throughput and efficiency. A novel nondissipative secondary rectifier clamp allows excellent control of reverse recovery energy. Converters that produce 128 kW at 25 kHz have been developed and are commercially available. As this topology exhibits complete control of all parasitic loss mechanisms, it can be easily scaled to higher power levels.     

High static gain single-phase PFC based on a hybrid boost converter

In this paper, a single-phase unity power factor rectifier, based on a hybrid boost converter, resulting from the integration of a conventional dc–dc boost converter and a switched-capacitor voltage doubler is proposed, analysed, designed and tested. The high-power rectifier is controlled by two feedback loops with the same control strategy employed in the conventional boost-based rectifier. The main feature of the proposed rectifier is its ability to output a dc voltage larger than the double of the peak value of the input line voltage, while subjecting the power switches to half of the dc-link voltage, which contributes to reducing the cost and increasing the efficiency. Experimental data were obtained from a laboratory prototype with an input voltage of 220 Vrms, line frequency of 60 Hz, output voltage of 800 Vdc, load power of 1000 W and switching frequency of 50 kHz. The efficiency of the prototype, measured in the laboratory, was 96.5% for full load and 97% for half load.     

A Three-Level Resonant Single-Stage Power Factor Correction Converter: Analysis, Design, and Implementation

This paper presents a new single-stage power factor correction ac/dc converter based on a three-level half-bridge resonant converter topology. The proposed circuit integrates the operation of the boost power factor preregulator and the three-level resonant dc/dc converter. A variable-frequency asymmetrical pulsewidth modulation controller is proposed for this converter. This control technique is based on two integrated control loops: the output voltage is regulated by controlling the switching frequency of the resonant converter, whereas the dc-bus voltage and input current are regulated by means of duty cycle control of the boost part of the converter. This provides a regulated output voltage and a nearly constant dc-bus voltage regardless of the loading condition; this, in turn, allows using smaller switches and consequently having a lower on resistance helping to reduce conduction losses. Zero-voltage switching is also achieved for a wide range of loading and input voltage. The resulting circuit, therefore, has high conversion efficiency making it suitable for high-power wide-input-voltage-range applications. The effectiveness of this method is verified on a 2.3-kW 48-V converter with input voltage (90–265 Vrms).      

Hybrid Full-Bridge Three-Level LLC Resonant Converter—A Novel DC–DC Converter Suitable for Fuel-Cell Power System

This paper proposes a novel hybrid full-bridge (H-FB) three-level (TL) LLC resonant converter. It integrates the advantages of the H-FB TL converter and the LLC resonant converter. It can operate under both three-level mode and two-level mode, so it is very suitable for wide-input-voltage-range applications, such as fuel-cell power systems. Compared with the traditional full-bridge converter, the input current ripple and output filter can be reduced. In addition, all the switches can realize zero-voltage switching from nearly zero to full load, and the switches of the TL leg sustain only half of the input voltage. Moreover, the rectifier diodes can achieve zero-current switching, and the voltage stress across them can be minimized to the output voltage. A prototype of 200-400-V input and 360-V/4-A output is built in our laboratory to verify the operation principle of the proposed converter     

A rugged soft commutated PWM inverter for AC drives

A novel DC-DC power converter for variable-speed AC power drives using the zero-voltage switching technique is described. This converter combines the advantages of soft commutated inverters and those of conventional pulsewidth modulated (PWM) inverters. In the proposed scheme, the soft commutation reduces the constraints on the switches, and the PWM enables simple and efficient regulation of the power flow. Furthermore, the zero-voltage switching technique makes operation safe, and the switching of bipolar transistors at 20 kHz is easily achieved without compromising the efficiency of the system     

Module-type switching rectifier for cathodic protection of underground and maritime metallic structures

Cathodic protection is widely used to prevent corrosion of steel materials buried underground and in seawater. As a rectifier for cathodic protection, the conventional phase-controlled rectifiers with 50- or 60-Hz isolation transformers have been used so far in spite of such shortcomings as large volume, heavy weight, and poor power factor. In order to overcome such disadvantages, this paper proposes a new module-type switching rectifier for cathodic protection, which is composed of two parts, namely, ac/dc converter and module-type dc/dc converter. The ac/dc converter is a single-phase insulated gate bipolar transistor pulsewidth-modulation rectifier, thus resulting in almost unity power factor and controlled dc output voltage. The module-type dc/dc converter operates under zero-voltage switching/zero-current switching condition to permit high-frequency switching operation. It enables the use of a high-frequency transformer for electrical isolation, thus reducing volume and weight of the overall system and improving system efficiency. It is anticipated that the proposed rectifier techniques will apply to the similar technical areas such as multiple-module power supply systems and modular converter-fed dc motor drives.     

Energy based closed form solution of ZCS multiresonantseries-parallel converters

Under-resonant operation of an ideal multi-resonant series-parallel power converter (MRSPC) with a capacitive output filter is modeled in this paper. This operation allows zero current switching (ZCS), which is convenient for bipolar devices. The capacitive output filtering reduces the recovery effect of the rectifier diodes and is suitable for high output voltage applications. A closed-form solution is found for this power converter, based on state space analysis using energy concepts. This approach simplifies the mathematical operations and gives better physical insight of the system variables. Based on the model, the steady-state characteristics of this power converter are derived by a simulation program, which are discussed and compared with the series resonant half-bridge power converter (SRHC). The optimum power converter parameters are found for given design requirements using computerized optimization routines. Several design examples are presented and compared with SRHC. The validity of the model is verified by SPICE simulations     

Analysis and design of class E isolated DC/DC converter using classE low dv/dt PWM synchronous rectifier

A class E isolated DC/DC power converter for regulating the output voltage at a fixed switching frequency is presented, analyzed and experimentally verified. It consists of class E series-resonant inverter, high-frequency transformer and class E low dv/dt pulse width modulation (PWM) synchronous rectifier. By controlling the conduction time of the controlled switch in the rectifier, high-frequency AC current is rectified and the output voltage can be controlled at the same time. The zero voltage switching (ZVS) condition of all switches can be maintained from full-loaded to open-loaded. The theoretical predictions were in good agreement with the experimental measurements and the maximum efficiency measured at a switching frequency of 1 MHz was 91.2%     

Analysis,design and implementation of an interleaved three-level PWM DC/DC ZVS converter

This paper presents a new parallel three-level soft switching pulse-width modulation (PWM) converter. The proposed converter has two circuit cells operated by the interleaved PWM modulation. Thus, the ripple currents at input and output sides are reduced. Each circuit cell has two three-level zero voltage switching circuits sharing the same power switches. Therefore, the current and power rating of the secondary side components are reduced. Current double rectifier topology is selected on the secondary side to decrease output ripple current. The main advantages of the proposed converter are soft switching of power switches, low ripple current on the output side and low-voltage rating of power switches for medium-power applications. Finally, the performance of the proposed converter is verified by experiments with 1 kW prototype circuit.