Zero-current-switching Pulsewidth-modulation Research Articles

Analysis of Strategy for Achieving Zero-Current Switching in Full-Bridge Converters

Conventional zero-voltage and zero-current-switching (ZVZCS) full-bridge converters are widely used because they can realize zero-voltage switching (ZVS) for the leading leg and zero-current switching (ZCS) for the lagging leg. However, the large turn-off loss of the leading leg is still unacceptable in high-voltage high-power applications where insulated-gate bipolar transistors (IGBTs) with current tailing are employed. Hence, it is preferable to achieve ZCS for all IGBTs of full-bridge converters. This paper analyzes the ZCS conditions for pulsewidth modulated (PWM) full-bridge converters and proposes a general strategy for achieving ZCS for main switches, including the control strategy and design method of the topology. Based on this theory, a novel ZCS PWM full-bridge converter with simple auxiliary circuit is derived and tested. It can achieve ZCS not only for the main switches of full-bridge converter, but for the auxiliary switch as well, and obtain high efficiency. The operation principle of the proposed ZCS PWM full-bridge converter and the design procedure are presented. The experimental results of a 600 V/2.5 kW prototype are also included to verify the theoretical analysis.

A Low-Stress Zero-Current Switching Technique for Power Converters

Huge voltage spikes on auxiliary switches is a common issue for most of the existing zero-current switching (ZCS) pulsewidth-modulated (PWM) converters. The reason for the spike lies in the parasitic resonance between the resonant inductance and the stray output capacitance C oss of the auxiliary switch, which does not have the negative impact in zero-voltage switching (ZVS) converters. This paper proposes a low-stress ZCS technique to eliminate the negative consequence of the C oss in ZCS PWM converters. All the power devices, including the auxiliary switch, show low voltage stresses and ZCS. The auxiliary cell of the low-stress ZCS technique introduced a clamping diode to realize the low-voltage stress for the power devices. The low-stress ZCS buck converter is taken as an example to explain both the low-stress and ZCS characteristics. A 2-kW hardware prototype is developed. The simulation and experiment results both validate the effectiveness of the proposed low-stress ZCS technique.

ZCS‐PWM interleaved boost converter using resonance‐clamp auxiliary circuit

The interleaving technique is a well-known technique applied in high power applications to share the output power between two modules while decreasing the input current and output current ripple. Moreover, zero current switching technique can be used in order to reduce the switching losses and increase the power density. Zero-current-switching (ZCS) condition as the soft-switching technique is usually applied for IGBT switches in order to eliminate tailing current losses. In this study, a new ZCS pulse-width-modulation (ZCS-PWM) interleaved boost converter is proposed which applies only one auxiliary switch. In the proposed converter ZCS condition is provided for main switches while the auxiliary switch is also soft switched. The principle of operation, performance analysis, and design method of the proposed converter are presented in details. Finally, the theoretical results are verified by experimental results.

Analysis, design and performance of a zero‐current‐switching pulse‐width‐modulation interleaved boost dc/dc converter

A novel interleaved boost dc/dc converter with zero-current-switching pulse-width-modulation (ZCS-PWM) characteristic using a simple ZCS-PWM auxiliary circuit is presented in this paper. The proposed converter combines the conventional PWM technique and ZCS technique to promote the circuit performance. The proposed converter uses dual boost converters which are operated at interleaved mode to increase the output power level. Thus, the proposed converter does not only decreases the current stress on main circuit devices but reduces the input ripple current and output capacitor size. Because the proposed converter establishes a common ZCS-PWM auxiliary circuit on used dual boost converters, it can greatly reduce the size and cost. And, it can provide the ZCS characteristic on main switches and auxiliary switches with a wide range of load to improve the problem of switching losses and EMI. Thus, its topology is simple and compact. Besides operating at constant frequency and reducing commutation losses, the proposed converter has no additional current stress and conduction loss in the main switch compared with the conventional interleaved boost dc/dc converter. The principle of operation, theoretical analysis and experimental results of the proposed boost converter, rated 1 kW and operating at 40 kHz, are provided in this paper to verify the performance of this new family of converters.

Analysis and Design of a Zero-Current Switching Forward Converter With Simple Auxiliary Circuit

In this paper, a new zero-current switching pulse width modulation forward converter is introduced using a new switching algorithm for the auxiliary circuit. In the proposed converter, transformer core is reset through a resonance, and thus, reset winding is not required which is the main advantage of this converter over existing zero-current switching forward converters. The simple auxiliary circuit of this converter is just composed of an auxiliary switch and a capacitor that provides zero-current switching for the main switch and also resets the transformer core. Furthermore, the proposed auxiliary circuit uses the leakage inductance of the transformer for the resonant inductor and does not require any additional inductor which is another advantage of the proposed converter over conventional zero-current switching forward converters. Also, the auxiliary switch is soft switched. The proposed converter is analyzed and design procedure of the auxiliary circuit is discussed. The presented experimental results confirm the theoretical analysis.

A Novel ZCS-PWM Flyback Converter With a Simple ZCS-PWM Commutation Cell

This paper proposes a novel zero-current-switching pulsewidth-modulation (ZCS-PWM) flyback dc/dc converter using a simple ZCS-PWM commutation cell. The main switch and auxiliary switch operate at ZCS turn-on and turn-off conditions, and all uncontrolled devices in the proposed converter operate at zero-voltage-switching (ZVS) turn-on and turn-off. In addition, given constant frequency and decreasing commutation losses, the proposed converter has no additional current stress and conduction loss in the main switch compared to the conventional hard switching flyback converter. The averaging approach is used to estimate and examine the steady-state of the proposed converter. The principle of operation, theoretical analysis, and experimental results of the new ZCS-PWM flyback converter, rated 150 W and operating at 80 kHz, are provided in this paper to verify the performance of the proposed converter.

A Zero-Current-Transition Converter With Reduced Auxiliary Circuit Losses

A new zero-current-switching (ZCS) pulsewidth-modulated (PWM) boost converter is proposed in this paper. The converter's main power switch can operate with ZCS due to an active auxiliary circuit that diverts current away from the switch just before it is turned off. The circuit allows the converter to operate with ZCS without the disadvantages typically found in other, previously proposed ZCS PWM converters such as increased switch stresses and excessive circulating current. In this paper, the operation of the proposed converter is explained in detail and a procedure for the design of the converter is presented and demonstrated with an example. The feasibility of the new converter is confirmed with results obtained from a 50-kHz, 1-kW experimental prototype.

A new single-phase ZCS-PWM boost rectifier with high power factor and low conduction losses

This paper proposes a new single-phase high-power-factor rectifier, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the active switches and zero-voltage switching (ZVS) in the passive switches. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved because of the following reasons: 1) the circulating current for the soft switching flows only through the auxiliary circuit; 2) a minimum number of switching devices are involved in the circulating current path; and 3) the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM-switch model is used to predict the system performance. A prototype rated at 1 kW, operating at 60 kHz, with an input alternating current voltage of 220 V/sub rms/ and an output voltage of 400 V/sub dc/, has been implemented in laboratory. An efficiency of 98.3% and a power factor over 0.99 have been measured. Analysis, design, and the control circuitry are also presented in this paper.

Zero-current-transition PWM DC–DC converters using new zero-current-switching PWM switch cell

A new family of zero-current-switching (ZCS) pulsewidth-modulated (PWM) converters, which uses a new ZCS PWM switch cell, is presented. The main switch and auxiliary switch operate at zero-current-switching turn-on and turn-off, and the all passive semiconductor devices in the ZCS-PWM converter operate at zero-voltage-switching turn-on and turn-off. Besides operating at constant frequency and with reduced commutation losses, these new converters have no additional current stress in the main switch in comparison to the hard switching converter counterpart. The PWM switch model and state-space averaging approach is used to estimate and examine the steady-state and dynamic character of system. The new family of ZCS-PWM converters is suitable for high-power application using insulated gate bipolar transistors. The principle of operation, theoretical analysis and experimental results of the new ZCS-PWM boost converter, rated at 1 kW and operating at 30 kHz, are provided to verify the performance of this new family of converters.

A Novel ZCS-PWM Power-Factor Preregulator With Reduced Conduction Losses

This paper proposes a new single-phase high-power-factor rectifier, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the active switches and zero-voltage switching in the passive switches. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Nine transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 50 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage 400 V/sub dc/ has been implemented in laboratory. An efficiency of 97.3% and power factor over 0.99 has been measured. Analysis, design, and the control circuitry are also presented in this paper.

Novel zero-current-switching (ZCS) PWM converters

A new family of zero-current-switching (ZCS) pulse-width-modulated (PWM) converters which uses a new ZCS PWM switch cell is presented in this paper. The main switch and auxiliary switch operate at zero-current-switching turn on and turn off, and the all passive semiconductor devices in the ZCS-PWM converter operate at zero-voltage-switching (ZVS) turn-on and turn-off. Besides operating at constant frequency and with reduced commutation losses, the proposed ZCS-PWM switch cell uses only one resonant inductor and these new converters have no additional current stress in comparison to the hard switching converter counterpart. The new family of ZCS-PWM converters is suitable for high-power application using insulated gate bipolar transistor (IGBTs). The principle of operation, theoretical analysis, and experimental results of the new ZCS-PWM boost converter, rated 1 kW and operating at 30 kHz, are provided in this paper to verify the performance of this new family of converters.

Zero-current-switching PWM power-factor-correction converter

A novel single-phase zero-current-switching pulse-width modulation (ZCS-PWM) power-factor-correction (PFC) converter is presented, which features regulation by conventional PWM, soft commutation, low conduction loss and instantaneous average line current control. Two resonant cells are configured in the presented ZCS-PWM PFC converter to perform soft-switching in the semiconductor devices and the soft commutation of the main switches is achieved without additional current stress. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path, and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behaviour of the ZCS-PWM PFC converter in one switching period are described. A prototype rated at 2.5 kW, operating at 60 kHz, with an input AC voltage of 220 V RMS and an output voltage 400 V DC has been implemented in the laboratory. An efficiency of 97.8% and a power factor over 0.99 has been measured. Analysis, design and the control circuitry are also presented.

Improved ZCS-PWM commutation cell for IGBTs application

An improved zero-current-switching pulsewidth-modulated (ZCS-PWM) commutation cell is presented, which is suitable for high-power applications using insulated gate bipolar transistors (IGBTs) as the power switches. It provides ZCS operation for active switches and zero-voltage-switching (ZVS) operation for passive switches. Besides operating at constant frequency and reducing commutation losses, the proposed ZCS-PWM switch cell has no additional current stress and conduction loss in the main switch. To demonstrate the feasibility of the proposed ZCS-PWM commutation cell, it was applied to a boost converter. Operating principle, theoretical analysis, design guidelines, and a design example are described and verified by experiment results obtained from a prototype rated 1 kW and operating at 40 kHz. The PWM switch model and state-space averaging approach is also used to estimate and examine the steady-state and dynamic character of ZCS-PWM boost converter system. Finally, the application of the proposed soft-switching technique in the dc-dc nonisolated converters is presented.

ZCS-PWM boost rectifier with highpower factor andlow conduction losses

A new single-phase high power factor rectifier is proposed, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the switches and zero-voltage-switching (ZVS) in the diodes. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 60 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage 400 V/sub dc/ has been implemented in laboratory. An efficiency of 97.2% and power factor near 0.99 has been measured. The analysis and design of the control circuitry are also presented.

Novel zero-current-switching (ZCS) PWM switch cell minimizing additional conduction loss

This paper proposes a new zero-current-switching (ZCS) pulsewidth modulation (PWM) switch cell that has no additional conduction loss of the main switch. In this cell, the main switch and the auxiliary switch turn on and turn off under zero-current condition. The diodes commutate softly and the reverse-recovery problems are alleviated. The conduction loss and the current stress of the main switch are minimized, since the resonating current for the soft switching does not flow through the main switch. Based on the proposed ZCS PWM switch cell, a new family of DC-to-DC PWM converters is derived. The new family of ZCS PWM converters is suitable for the high-power applications employing insulated gate bipolar transistors. Among the new family of DC-to-DC PWM converters, a boost converter was taken as an example and has been analyzed. Design guidelines with a design example are described and verified by experimental results from the 2.5 kW prototype boost converter operating at 40 kHz.

An improved ZCS-PWM commutation cell for IGBT's application

An improved zero-current-switching pulsewidth-modulation (ZCS-PWM) commutation cell is proposed, which is suitable for high-power applications using insulated gate bipolar transistors (IGBTs) as the power switches. It provides ZCS operation for active switches with low-current stress without voltage stress and PWM operating at constant frequency. The main advantage of this cell is a substantial reduction of the resonant current peak through the main switch during the commutation process. Therefore, the RMS current through it is very close to that observed in the hard-switching PWM converters. Also, small ratings auxiliary components can be used. To demonstrate the feasibility of the proposed ZCS-PWM commutation cell, it was applied to a boost converter. Operating principles, theoretical analysis, design guidelines and a design example are described and verified by experimental results obtained from a prototype operating at 40 kHz, with an input voltage rated at 155 V and 1 kW output power. The measured efficiency of the improved ZCS-PWM boost converter is presented and compared with that of hard-switching boost converter and with some ZCS-PWM boost converters presented in the literature. Finally, this paper presents the application of the proposed soft-switching technique in DC-DC nonisolated power converters.

ZCS-PWM full-wave boost rectifier with unity power factor and low conduction losses

A full-wave boost rectifier (FWBR) realized by zero-current-switching pulsewidth-modulation (ZCS-PWM) control to achieve unity power factor is presented. Two resonant cells are configured in the presented FWBR to perform ZCS in the power switches and to preregulate the input current to follow up the input voltage. Only one diode and one power switch loss are included in the proposed FWBR during the rectification. Four transition states for describing the behavior of the ZCS-PWM FWBR in one switching period are described. A small-signal model is built for the system analysis, and an average-current-mode control is employed to formulate the input current waveform with low harmonics. The control strategy and design consideration are programmed to realize a 600-W ZCS-PWM FWBR, which provides high power efficiency of 95% and high power factor over 0.99.