PWM Full-bridge Converter Research Articles

An Improved Zero-Voltage and Zero-Current- Switching Phase-Shift Full-Bridge PWM Converter With Low Output Current Ripple

In order to improve the performance of traditional phase-shifted full-bridge converters and reduce the output current ripple, an improved zero voltage and zero current switching phase-shifted full-bridge PWM converter is proposed in this article. By adding a simple auxiliary circuit, the leading-leg switches realize zero voltage switching and the lagging-leg switches realize zero current switching. The primary current is reset during the freewheeling period, so the efficiency of the converter is improved. What is more, the improved converter can effectively reduce the output current ripple. The added auxiliary circuit does not include any lossy components or saturable reactors. The improved phase-shifted full-bridge converter has many advantages, including simple circuit topology, easy implementation of soft switching, high efficiency, and low output current ripple. The operational principle and analysis of the proposed converter are presented in this article. An 800 W experimental prototype is built for experimental verification.

Analysis of a Wide Voltage Hybrid Soft Switching Converter

A hybrid PWM converter is proposed and investigated to realize the benefits of wide zero-voltage switching (ZVS) operation, wide voltage input operation, and low circulating current for direct current (DC) wind power conversion and solar PV power conversion applications. Compared to the drawbacks of high freewheeling current and hard switching operation of active devices at the lagging-leg of conventional full bridge PWM converter, a three-leg PWM converter is studied to have wide input-voltage operation (120–600 V). For low input-voltage condition (120–270 V), two-leg full bridge converter with lower transformer turns ratio is activated to control load voltage. For high input-voltage case (270–600 V), PWM converter with higher transformer turns ratio is operated to regulate load voltage. The LLC resonant converter is connecting to the lagging-leg switches in order to achieve wide load range of soft switching turn-on operation. The high conduction losses at the freewheeling state on conventional full bridge converter are overcome by connecting the output voltage of resonant converter to the output rectified terminal of full bridge converter. Hence, a 5:1 (600–120 V) hybrid converter is realized to have less circulating current loss, wide input-voltage operation and wide soft switching characteristics. An 800 W prototype is set up and tested to validate the converter effectiveness.

Hybrid Resonant ZVZCS PWM Full-Bridge Converter for Large Photovoltaic Parks Connecting to MVDC Grids

A novel hybrid resonant zero-voltage zero-current switching pulsewidth modulation full-bridge converter with capacitive output filter is proposed in this paper, which is suitable for large photovoltaic parks connecting to medium-voltage dc (MVDC) grids. The hybrid resonant converter, with two full-bridge cells sharing a bridge leg and connecting the secondary windings of two transformers in series, operates in discontinuous current mode and can achieve zero-current switching for main power switches and rectifier diodes over the whole load range. Meanwhile, the auxiliary switches with small current rating can realize zero-voltage switching naturally. Hence, the switching loss is reduced, which is vital in MVDC applications. By the trajectory formulas of the resonant current and voltage, the trajectory paths can be achieved, which is helpful to compare the peak and turn-off currents of switches. The design rules of main parameters can be deduced with the trajectory formulas and paths. The influence of the turns ratio of auxiliary transformer and the resonant capacitance on the peak and turn-off currents is discussed in detail. A simulation model is established in the software PLECS and the operation principles of the converter are verified. A 150 V–1500 V/2 kW prototype was built to validate the operation principles and parameters optimization.

Fuzzy Controlled ZVS Asymmetrical PWM Full-bridge DC-DC Converter for Constant load High Power Applications

This paper proposes a fuzzy logic controlled new topology of high voltage gain zero voltage switching (ZVS) asymmetrical PWM full-bridge DC-DC boost converter for constant load and high power applications. The APWM full-bridge stage provides high voltage gain and soft-switching characteristics increase the efficiency and reduce the switching losses. Fuzzy logic controller (FLC) improves the performance and dynamic characteristics of the proposed converter. A comparison with a classical proportional-integral (PI) controller demonstrates the high performances of the proposed technique in terms of effective output voltage regulation under different operating conditions. Simulation is done by integrating two different simulation platforms <TEX>$PSIM^{(R)}$</TEX> and <TEX>$Matlab^{(R)}/Simulink^{(R)}$</TEX> by using SimCoupler tool of <TEX>$PSIM^{(R)}$</TEX>. Experimental results using 120W load have been provided to validate the results.

The Circuit Design of the DC/DC Stage of Aviation Static Converter

This paper reviews the state of development of aviation power and aviation static converter. Considering the urgent need of planes to aviation static converter of high voltage, large current and high power output, this paper mainly studied the DC/DC stage of high voltage dc aviation static converter, and designed the phase shifted ZVS PWM full-bridge converter with two clamping diodes as the basic topological cell of the first stage of the two-stage static converter. Meanwhile the paper analyzed the working principle of the phase shifted ZVS PWM full-bridge converter with two clamping diodes, and then a simulation was run by using the software Saber, which proved theoretical analysis right.

DCM Analysis of ZVS PWM Full-Bridge Converter with Current Doubler Rectifier

The operation principle and the external characteristics in discontinuing current mode (DCM) are discussed for ZVS PWM Full-bridge Converter with current doubler rectifier (CDR ZVS PWM FB converter) .The converter operated in DCM remains the performances of the converter in CCM. This makes the converter achieve ZVS for the switches in a wide load range with the use of the energy stored in the output filter inductances, and the rectifier diodes commute naturally, therefore no oscillation occurs. Features of ZVS achievement for the switches in DCM are also included in this paper.

Zero-Voltage and Zero-Current-Switching PWM Combined Three-Level DC/DC Converter

This paper proposes a zero-voltage and zero-current-switching (ZVZCS) PWM combined three-level (TL) dc/dc converter, which is a combination of a ZVZCS PWM TL converter with a ZVZCS PWM full-bridge converter. The proposed converter has the following advantages: all power switches suffer only half of the input voltage; the voltage across the output filter is very close to the output voltage, which can reduce the output filter inductance significantly; and the voltage stress of the rectifier diodes is reduced too, so that the converter is very suitable for high input voltage and wide input voltage range applications. The converter also can achieve zero-voltage-switching for the leading switches and ZCS for the lagging switches in a wide load range to achieve higher efficiency. The design considerations and procedures are presented in this paper. The operation principle and characteristics of the proposed converter are analyzed and verified on a 400-800-V input and 54-V/20-A output prototype.

ANALYSIS AND MODELING OF A NOVEL ZVZCS FB PWM CONVERTER

A novel zero-voltage and zero-current-switch (ZVZCS) full-bridge PWM converter is presented. There are neither additional active switches nor lossy components in the proposed converter to achieve ZVZCS conditions. Moreover, the ZVZCS conditions are achieved by changing the traditional configuration of ZVS-full-bridge without added control: a simple auxiliary circuit is added in the secondary and the center tap of the transformer's secondary is linked to the auxiliary circuit. The secondary rectifier voltage of the converter is clamped to a relative low level, so additional clamp circuit for the secondary rectifier is not necessary. Using a new improved approach, which concerns the energy input into the secondary rather than the voltage in secondary, a complete small-signal model for the converter is developed through simple calculation. The operation of the proposed converter is analyzed, some important formulas are deduced. The experimental results of a 1.2-KW prototype prove that the novel converter is successful.

A new ZCZVT commutation cell for PWM DC-AC converters

This paper proposes a new auxiliary commutation cell for PWM inverters that allows the main switches to be turned on and off at zero voltage and zero current. The main switches zero current turn-on reduces the undesired effects of parasitic inductances related to the circuit layout. The main diodes reverse recovery losses are minimized since di/dt and dv/dt are controlled. The ZCZVT commutation cell is located out of the main power path of the converters and is activated only during switching transitions. Additionally, the auxiliary switches are turned on and off at ZCS and use the same ground signals of the upper main switches. The commutation losses are practically reduced to zero. Soft switching operation is guaranteed for full load range without changes in command strategy. The operation of the ZCZVT PWM full-bridge DC-AC Converter is analyzed and an auxiliary commutation cell design procedure based on the analysis is proposed. Experimental results are presented to demonstrate the feasibility of the proposed commutation cell.

Pwm Full-bridge converter with natural input power factor correction

A pulsewidth modulated (PWM) full-bridge converter that simultaneously performs input power factor correction (PFC) and DC-DC conversion is proposed. The converter is the same as the standard voltage-fed PWM full-bridge converter with a diode-bridge low-pass filter front end, but with a slight modification that results in an improvement in power factor that is sufficient to satisfy the EN61000-3-2 requirements for electrical equipment. The operation of the converter is explained and analyzed, and the results of the analysis are used to determine the converter's steady-state characteristics, which are discussed in detail. A design procedure for the selection of components is then derived and demonstrated with an example. The feasibility of the converter and its ability to satisfy EN61000-3-2 requirements on electrical equipment is shown with results obtained from an experimental prototype.

A simple ac-dc pwm full-bridge converter with integrated power-factor correction

A simple ac-dc pulsewidth-modulation (PWM) converter that can perform isolated dc-dc conversion while shaping the input current to improve power factor is proposed in this paper. The converter is almost the same as a standard PWM full-bridge converter with a diode rectifier/LC low-pass filter input except for some slight modifications. The converter topology is, therefore, very simple, as is the method of control used to achieve both power-factor correction and dc-dc conversion. In the paper, the operation of the converter is explained and analyzed, and the converter's steady-state characteristics are discussed. A design procedure for the selection of components is presented, and then demonstrated with an example. The feasibility of the converter, and its ability to meet EN61000-3-2 Class D standards for electrical equipment is shown with results obtained from an experimental prototype.

A novel zero-voltage and zero-current-switching PWM full-bridge converter using two diodes in series with the lagging leg

This paper proposes a novel phase-shifted zero-voltage and zero-current-switching (ZVZCS) pulsewidth modulation full-bridge converter, which realizes ZVS for the leading leg and ZCS for the lagging leg. A blocking capacitor is added in series with the primary winding of the transformer to make the primary current decay to zero during zero state to ensure ZCS for the lagging leg. In order to prevent the primary current from reversing during zero state, two diodes in series with the lagging leg are added. The principle of operation, steady-state analysis, and design procedures are presented. The experimental results are also included to verify the theoretical analysis.

Full-bridge soft switching PWM converter with saturable inductors at the secondary side

An improved full-bridge (FB) soft switching DC-to-DC converter with saturable inductors at the secondary side is presented and analysed. The main devices are switched on under zero-voltage conditions using the energy stored in the secondary saturable inductors. On the other hand, the secondary diodes are switched off under zero-current conditions due to the large inductance of the saturable inductors when it is not saturated. The advantages of this converter include a wide load range with zero-voltage-switching (ZVS) and zero-current-switching (ZCS), a large effective duty ratio, and no secondary voltages spikes, in addition to high power density and high efficiency. Experimental results obtained on a 6 kW prototype are discussed.

Zero-voltage and zero-current-switching full-bridge PWM converter using secondary active clamp

A new zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter is proposed to improve the performance of the previously presented ZVZCS-FB-PWM converters. By adding a secondary active clamp and controlling the clamp switch moderately, ZVS (for leading leg switches) and ZCS (for lagging leg switches) are achieved without any lossy components, the reverse avalanche break down of leading-leg IGBTs or the saturable reactor in the primary. Many advantages including simple circuit topology, high efficiency, and low cost make the new converter attractive for high voltage and high power (>10 kW) applications. The principle of operation is explained and analyzed. The features and design considerations of the new converter are also illustrated and verified on a 1.8 kW, 100 kHz IGBT based experimental circuit.

IGBT based zero voltage transition full bridge PWM converter for high power applications

A novel zero-voltage-transition (ZVT) full-bridge (FB) PWM converter for high power applications is proposed. An auxiliary resonant network which consists of two small switches (10-20% of main switches) and one small inductor provides zero-voltage-switching (ZVS) for wide line and load ranges. This allows addition of external capacitors to the switches maintaining reasonable ZVS range, and IGBTs can be used instead of MOSFETs for the main switches. In addition, the proposed converter has advantages over the ZVS-FB-PWM converters such as minimum device voltage and current stresses, negligible duty cycle loss, and no severe parasitic ringing on the secondary, which enables the proposed converter to handle higher voltage and power with lower cost. Operation, features and design considerations are presented and verified experimentally on a 2 kW, 85 kHz IGBT based prototype.

A Saturable Reactor Assisted Soft-Switching PWM DC-DC Converter.

In the demand for increasing power density of switched mode power converters, resonant topologies have attracted much attention because of their low switching losses and low EMI. However, they require relatively large resonant components, and high current or high voltage ratings for semiconductor devices.This paper presents a new soft-switching PWM full-bridge DC-DC converter which can overcome these drawbacks by utilizing a small saturable reactor. The principle of operation and steady-state characteristics are illustrated. The role of the saturable reactor is also discussed. Moreover, the voltage and current stresses for active and passive components are presented.To verify the results, key experiments were implemented with a 350W, 500kHz prototype converter. It is proved that the converter achieves soft-switching in a wide load range with no substantial increase in voltage and current stresses for active and passive components.