Energy Efficiency Implement Soft Switching at Zero Voltage of Transistors in Push-Pull Converter, with a Throttle at the Input

According to the poor stability of the output constant current and the control complexity of the existing Inductive Coupled Wireless Power Transmission System, a seriesparallel compensation network is applied to push-pull converter. And the soft switch is realized by configuring the parameters of compensation network, and the constant-current output of the wireless power is realized without additional complex control system. Firstly, analysis of the push-pull converter to achieve the conditions of soft-switching. Secondly, based on the leakage inductance model of the transformer, combined with the Thevenin equivalent theorem, the parameters of the string-and-compensation are designed. Lastly, the push-pull soft-switching inductive coupled power transfer converter is designed and built.The feasibility of theoretical analysis and parameter design method are verified by the experimental results.

Autonomous voltage inverters with PWM, which are used in electric drive systems with brushless motors, occupy an important place in the complex of electrical equipment of modern traction rolling stock of railways. The article presents the results of the research of the traction three-phase bridge voltage inverter with soft switching of power switches. Using the soft switching mode allows you to reduce the switching losses in the power transistors of the keys, increase the PWM frequency and improve other performance indicators of the converter. It is advisable to implement soft switching in the key transistors of the three-phase voltage inverter using soft switching nodes with fast-acting four-quadrant switches based on IGBT. It is proposed to consider the possibility of using transistor switches of a voltage inverter with capacitive non-dissipative snubbers at high PWM frequencies. For this purpose, a synthesis of the scheme and algorithm for the implementation of soft switching in a three-phase bridge voltage inverter with bipolar sinusoidal PWM with soft switching nodes with high-speed four-quadrant switches based on IGBT was performed. An analysis of the characteristics of the three-phase voltage inverter was carried out when using high-speed switches in the soft switching nodes to implement soft switching in the power transistors of the inverter switches.On the basis of the study, it is proposed to modernize the scheme of the soft switching unit in order to provide better preparation for the switching of the power transistors of the keys at large load currents. The improved soft switching unit includes low-voltage sources of constant voltage, which will compensate for energy losses in the recharging circuit of the snubber capacitors and contribute to the soft switching on of the power transistors of the voltage inverter keys. The performance test was carried out and the characteristics of the converter were analyzed when using a modernized soft switching node using simulation modeling in the MATLAB package.

Dual Active Bridge (DAB) Converter and PushPull Converters are mainly used for Conversion of power with large cycles per second. Dual active bridge converter consists of couple of full bridge converters linked through a transformer. Two way power flow capacity, high power density, high proficiency, soft switching, less number of passive elements and galvanic separation are the important characteristics of DAB pulling in industry. The push-pull converter is utilized as DC-DC converters are reasonable for low and medium power application. High efficiency, low switching loss and high power density are the important characteristics of this converter. By increasing the switching frequency, it results in the reduction of complexity of the circuit. However the switching loss increases as the switching frequency is increased. In this paper, the study is focused on a comparative analysis of DAB converter and Push-Pull converter.

In this paper, a novel soft switching push-pull LC resonant DC-DC converter for energy sources is presented. In a high step-up converter, the input of primary side possesses low voltage and high current, so the losses caused by the current account for most of the total power loss. At the same time, the high-voltage stress of the high-voltage output components on the secondary side is also a major problem. Therefore, a high-gain isolated push-pull converter with a secondary-side resonant circuit is proposed, so that the primary-side switches have zero voltage switching (ZVS) and the secondary-side diodes have zero current switching (ZCS). The push-pull structure can reduce the number of active switches, so that the total power loss on the primary side can be reduced. The converter has a resonant tank circuit arranged between the secondary side of isolation transformer and the high-voltage output rectification module. The high-voltage output rectifier module adopts a full-bridge architecture suitable for high-voltage coupling connection. The low-side power switching module adopts a push-pull architecture suitable for low-voltage and high-current applications. The resonant tank circuit uses an inductor–capacitor (LC) structure to improve the resonant tank circuit, which achieves soft switching during power transfer, increasing the efficiency of the converter and improving the electromagnetic compatibility. The main advantage of this technology is that the secondary-side leakage inductance of transformer and the resonant capacitance are connected in series to achieve ZVS for switches and ZCS for diodes. Finally, a prototype of a high-gain push-pull resonant converter was established. The converter was operated at a fixed switching frequency of 135 kHz and a duty cycle of approximately 0.5. The efficiency of the converter can reach 97.1% under experimental tests at an output voltage of 400 V and a rated output power of 500 W.

In this paper, an improved Zero-Voltage-Transition (ZVT) two-cell interleaved boost Power Factor Correction (PFC) converter is proposed and investigated. A new auxiliary circuit is designed and added to two-cell interleaved boost converter to reduce the switching losses. Only one auxiliary switch is used in the active soft switching auxiliary circuit. The main advantage of this auxiliary circuit is that it not only provides ZVT in the boost switches but also provides soft switching in the auxiliary switch and passive diodes. Therefore, the switching losses of the converter can be reduced. Compared to the previous published soft switching interleaved boost converters, only one auxiliary switch is needed in the auxiliary unit, so the auxiliary unit and control circuit are simple. A 1kW, 50 kHz two-cell interleaved boost PFC converter with an improved ZVT auxiliary circuit has been simulated using average current control method and the results are presented. Simulation results show that the main switches, the auxiliary switch and passive diodes are operating under soft switching mode.

The article describes a method for determining static and dynamic power losses in power transistors, taking into account the influence of the module temperature. The results of a three-dimensional approximation of the energy characteristics of an IGBT module with a reverse diode of the type 2MBI150U2A-060, namely, the voltage drop between the collector and the emitter depending on the collector current and temperature, as well as the dependence of the turn-on energy, the turn-off energy and the return energy on the flowing current and temperature. The above expressions make it possible, by means of computer modeling in the Matlab / Simulink software environment, to determine the static and dynamic losses in the power switches of semiconductor converters of various topologies with different control systems, taking into account the influence of the temperature regime.

The DC/DC converter needs the inductor to get the desirable increased voltage, which means it is impossible to avoid the power loss. Thus, minimising the inductor current may be a way to suppress the loss. In this study, to achieve higher efficiency of DC/DC converters, the control method to minimise peak current in boundary conduction mode (BCM) of the DC/DC converter is proposed when implementing soft switching of the converter switches. The comprehensive principle to minimise peak current in BCM is studied and the precise conduction time and conduction sequence of four switches of the buck–boost circuit are deduced. On comparing with the bipolar BCM and unipolar BCM, the proposed BCM could effectively reduce the inductor current in the DC/DC converter. Furthermore, low‐voltage and high‐voltage DC experiments were independently designed to verify the proposed control. The experimental results from a prototype of 1 kW DC/DC converter proved that this novel control method could realise the soft switching with the minimising peak current of the buck–boost converter switches and reduce the loss of the whole DC/DC converter.

The versatility of switched mode DC/DC Converters plays a vital role in power electronic converters technology by the virtue of its high conversion efficiency and reliable output voltage, moreover the design aspects of these converters are able to maintain the regulated output voltage even though input side voltage and output side current varies. In this paper a soft-switched, AC link DC to DC Converter proposed and closed loop voltage control is furnished to maintain the output voltage against the changes in input voltage and output current. However special features like zero voltage turn-on and capacitor restrained turn off can be realized by operating the resonant AC link of this converter in soft switching mode, these special features minimizes the switching losses developed on switches. In the proposed converter, the soft switching is realized through inductor current control. Concurrent ON and OFF time control based pulse technique is employed to achieve both closed loop voltage control and inductor current control. Simulations were performed in PSIM to evaluate the proposed converter in a illustrative manner.

Switching power converters cause electromagnetic interference (EMI), which can disturb the normal operation of the converter itself and other adjacent systems. Power converters must comply with electromagnetic compatibility (EMC) standards to guarantee proper operation of converters and nearby systems. Soft switching methods can be employed as EMI mitigation techniques in power converters. Although, soft switching converters are commonly addressed to have lower EMI than hard switching counterparts, they may not satisfy EMC regulations. In this study, spread spectrum by the means of pseudorandom modulation is applied to a zero-current transition (ZCT) flyback converter. By extracting the converter EMI model, the effect of using ZCT soft switching method is simulated and compared to its hard switching counterpart. The reduced amount of conducted electromagnetic emission is demonstrated via the proposed simulation method. To justify the theoretical analysis, the experimental results are presented.

The aim of the work is to develop algorithm for determining the optimal switching frequency of a transistor pulse-width converter (PWM) to minimize the total electrical losses in a DC drive. Electrical losses in the armature winding and in PWM transistors are divided into two components: static from the direct current component and dynamic. The latter include losses in the armature winding from the harmonic components of the current and losses in transistors from transient switching currents. Since the dynamic losses in transistors increase with increasing frequency, and in the armature winding from current harmonics they decrease, there is an optimal switching frequency value at which the total dynamic losses in the PWM drive will be minimal. This aim is achieved by solving the problem of determining the analytical dependence of dynamic electrical losses in the armature winding on the PWM switching frequency and computer simulation of a transistor DC drive. As a result of the research, an analytical expression was obtained for calculating the relative dynamic electrical losses in the armature winding with polyharmonic power supply. An algorithm is proposed for determining the optimal switching frequency of the PWM: 1) on computer models of the DC motor and PWM, the dependences of dynamic electrical losses on the switching frequency are determined; 2) build a graph of the dependence of the total dynamic electrical losses, on the which determine the point of minimum losses, which corresponds to the optimal value of the switching frequency. The novelty of the work lies in the fact that the theory of electrical losses in the armature windings with polyharmonic power has been further developed.

This paper is concerned with the design, construction and testing of a 3-phase to 3-phase soft switching matrix converter. Two auxiliary soft switching circuits are added to each output phase in order to achieve soft switching without significantly increasing the conduction losses. The converter operation is discussed with reference to theoretical waveforms. The distribution of the switching losses with respect to load current and commutation voltage is investigated. Using the proposed topology it is possible to disable the auxiliary switch when the current and/or voltage is low. This simplifies the design of the auxiliary circuit as the range of operating conditions is reduced, allowing better optimisation in terms of switching losses and commutation speed. We present results from a 3-phase to 3-phase prototype matrix converter showing switching waveforms for all commutation scenarios. Measurements of the overall power circuit losses are presented and comparisons are made with conventional hard switching matrix converters. The distribution of losses between the different loss mechanisms will be investigated for both converters. It is shown that the switching losses for the main switches is reduced by about 50% but this is compensated for by the losses in the auxiliary switches resulting in no significant increase in efficiency. Further research will be required to develop viable soft switching matrix converter structures.

Soft switching has the potential of reducing switch stresses and of lowering the switching losses as compared to hard switching. For this reason, several soft switching topologies have been presented in the literature. Each topology has some advantages. Their operation, however, requires additional active and/or passive elements. This introduces additional cost and complexity. To understand the effectiveness of the soft switching technique, when applied to electric vehicle (EV) and hybrid electric vehicle (HEV) systems, it may be necessary to first evaluate their system requirements and performances. This evaluation process would require knowledge of the vehicle dynamics. The vehicle load requires a special torque-speed profile from the drive train for minimum power ratings to meet the vehicle's operational constraints such as, initial acceleration and gradability. The selection of a motor and its control for EV and HEV applications is dictated mainly by this special torque-speed requirement. As a consequence, this requirement will have a strong influence on the converter operation. This paper makes an attempt to evaluate EV and HEV running in both standard FTP75 city driving cycle and highway driving cycle. The analysis is carried out for several most commonly used electric motors operating on the optimal torque-speed profile. Special attention is given to the converter losses. Features of the soft switching are evaluated in the context of the dynamic vehicle power flow and the system losses, as well as the power converter requirements. The relative significance of soft switching for EV and HEV systems is then established.

This paper presents an average inductor current sensor with enhanced accuracy in DCM operation for buck converters. The proposed sensor employs sample-and-hold (S/H) techniques instead of continuous-time techniques to sense the peak and valley of the current profile in the high-side and low-side power switches, respectively. Using these values, the average inductor current is estimated with high accuracy, since the S/H operation eliminates sensing errors due to the finite bandwidth of the sense amplifiers. To enhance sensing accuracy in DCM, the proposed sensor measures the conduction time and the switching period of the converter, and uses an analog nonlinear function generator to scale the sensed peak current of the high-side power switch. This DCM-scaling produces a more accurate estimation of the average inductor current compared to other S/H techniques. The proposed sensor is implemented within a 2-MHz buck converter in $0.5-{\mu } \mathrm {m}$ CMOS, where simulation results show the error in the sensed average inductor current is only 2% in both CCM and DCM. In DCM, a corresponding continuous-time sensor has over 42% error, while a S/H sensor without DCM-scaling has over 110% error.

This paper presents the results of an in-depth investigation into the operation, modulation, control, and performance assessment of a DC-DC converter, which is based upon a hybrid combination of the conventional dual-active-bridge topology and the modular multi-level converter (MMC) configuration. The proposed converter is a potential candidate topology for interconnection of medium- and low-voltage DC grids. The paper first introduces the circuit topology and presents the basics of operation and governing steady-state equations for the converter. Then, based on the developed mathematical model, it identifies a suitable modulation strategy for the converter bridges and submodules, as well as strategies for the regulation of the MMC submodule capacitor voltages and soft switching of the constituent semiconductor devices. The validity of the mathematical model, effectiveness of the proposed modulation and control strategies, and realization of soft switching are verified through simulation and experiments on an experimental setup.

The oscillation voltage (Ebm) is an important parameter of the characteristic constant of a high power microwave generator. When Ebm could be made high, it serves so as to improve the power conversion efficiency of a magnetron. Thus, the newly developed magnetron with 7% higher oscillation cut-off voltage than the present conventional one is manufactured by Matsushita Electric Industrial Co.Ltd, In addition to this, the utility AC power line current reduced harmonic type direct inverter AC-DC power converter suitable and acceptable for driving this magnetron is proposed in this paper. This direct high frequency inverter type soft switching PWM AC-DC converter has the voltage-boost function based on active clamp scheme with soft switching pulse modulation strategy topology. This paper describes a novel type active clamp AC-DC power converter circuit defined as direct high frequency inverter and the switching operation of this power converter is described and discussed on the basis of simulation and experimental results. The operating characteristics of this soft switching direct high frequency inverter type AC-DC power converter using IGBTs that incorporates the harmonic current improvement as well as power factor correction are evaluated and discussed from a practical point of view as compared with the conventional AC-DC power converter.