Soft-switching Technology Research Articles

Pulse current stabilizer with digital control for the power supply system of the plasmatron

Purpose. Solution of theoretical and practical problems on providing digital control of a pulse converter using high-speed microprocessor tools in the output current stabilization mode with provision of a specified duration of transient processes caused by an increase in load voltage and output current astaticity, which allows to obtain significant advantages over analog versions. Methodology. Review of literary and patent sources on the subject, theory of pulse automatic control systems, mathematical modeling of processes in pulse current stabilizers in the MATLAB / Simulink software environment and physical prototyping. Findings. A simulation model of an autonomous power supply system based on a converter using soft switching technology of transistors and an arc load is presented. A control law is synthesized and a model of a pulse current stabilizer is developed. A method is proposed and ways are found to control a pulse current stabilizer that provide a given duration of transients and astatism of the output current. A model of a pulse stabilizer with digital control based on a single-crystal computing module is developed and manufactured. The results of the study confirm the achievement of a finite duration of transient processes caused by a step change in the load voltage, close to 3-4 periods of conversion and output current astaticism. It is shown that the use of a pulse stabilizer using a fully digital control circuit has undeniable advantages over analog systems. Originality. The problem of synthesizing a digital controller for a given control time by the method of desired transfer functions for a soft switching operating converter on an arc load is solved. In addition to the given control time, additional quality requirements in the steady state are provided. Practical value.The use of microprocessor technology makes it possible not only to implement complex and new highly efficient control algorithms for a converter operating in the pulse current stabilizer mode, but also to perform additional functions for overload protection, self-diagnostics and telemetry of pulse converters. The use of this same digital device simultaneously for the purpose of controlling a pulse converter will allow to abandon analog PWM controllers and thereby reduce its own energy consumption and weight and size characteristics, increase the reliability of the functioning of pulse converters in power supply systems as a whole.

Efficient power conversion with four switch soft-switching boost integrated half-bridge dual-output series resonant converter

Soft switching reduces voltage and current stress during transitions, smoothing and quieting operations and reducing electromagnetic interference while also increasing efficiency and equipment lifespan. Circuit design, component selection, and switching frequency optimization affect power electronics soft switching. This paper proposes boost integrated half-bridge dual-output series resonant (BIHBDOSR) converter, a novel converter design and control method to increase series resonant converter performance by reducing storage element size, switch count, and switching losses. This methodology relies on soft-switching technologies like zero-voltage switching (ZVS) and zero-current switching (ZCS). These methods use class-D, class-E, series, parallel, and series–parallel resonant converter circuits to increase efficiency and minimize component stress. The proposed converter is ideal for constant voltage, constant power, and current-controlled loads with the output voltage being regulated by a closed-loop PI controller. The output voltages for two loads in the simulation depart from reference values. V01 changes from 14 to 20 V and V02 from 18 to 15 V at 300 ms owing to switching variances. The proposed converter utilizes gate driver circuits, resonant tank circuit, current sensor, FPGA board for closed-loop control, and current sensor for stability, ensuring converter stability. The proposed converter closed-loop control method modifies PWM signals to regulate both loads independently and ensure steady output voltage. Additionally, to validate the effectiveness of proposed converter, a 50-W driver circuit is designed, delivering two independent outputs of 20 W and 30 W. Frequency modulation (FM) and duty cycle control methods are employed to obtain the desired outputs.

Research on strategy of load-side resonant soft-switching inverter based on interconnection and damping assignment-passivity based control

Soft-switching technologies can effectively solve the problem of switching losses caused by increasing switching frequency of grid-connected inverters. As a branch of soft-switching technologies, load-side resonant soft-switching is a hotspot for applications of high-frequency inverters, because it has the advantage of achieving soft-switching without using additional components. However, the traditional PI control strategy based on the linear model is prone to destabilization and non-robust dynamic performance when large signal perturbation occurs. In this paper, a novel Passivity-Based Control (PBC) method is proposed to improve the dynamic performance of load-side resonant soft-switching grid-connected inverter. Besides, the model based on the Port Controlled Hamiltonian (PCH) model of the soft switching inverter is carried out, and the passivity-based controller is designed based on the established model using the way of interconnection and damping assignmentpassivity based control (IDA-PBC). Both stable performance and dynamic performance of the load-side resonant soft-switching inverter can be improved over the whole operating range. Finally, a 750 W load-side resonant soft-switching inverter simulation model is built and the output performance is compared with the traditional PI control strategy under stable and dynamic conditions. The simulation results show that the proposed control strategy reduces the harmonic distortion rate and improves the quality of the output waveforms.

A Zero-Voltage-Transition H5-Type Transformerless Photovoltaic Grid-Connected Inverter

Efficiency and leakage current are two major issues for transformerless grid-connected inverters (TLI). Soft-switching technologies can reduce switching losses and be applied in TLIs. Herein, a zero-voltage-transition H5 type (ZVT-H5) inverter with soft turn-on and turn-off transitions of high-frequency main switches is derived from basic resonant tanks. Compared with the hard-switching H5 (HS-H5) inverter, the conversion efficiency of ZVT-H5 is significantly improved. Moreover, the reverse recovery problem of freewheeling diodes is alleviated under the operation of the auxiliary resonant network. Meanwhile, a diode clamping branch is employed to achieve constant common-mode characteristic for the ZVT-H5. The construction process of the proposed topology is described, and the operation principle of the auxiliary resonant network is analyzed. Moreover, the resonant parameter design of ZVT-H5 and its circuit performance are discussed in detail. Finally, the experimental results of a 3-kW prototype at 100 kHz switching frequency are provided to verify the effectiveness of the ZVT-H5.

Real-Time Frequency Adaptive Tracking Control of the WPT System Based on Apparent Power Detection

In wireless power transfer (WPT) systems, inverters are used to achieve high-frequency conversion of DC/AC, and their conversion efficiency and working frequency are key factors affecting the system’s power transfer efficiency. In practical applications, many hardware issues, such as power transistor shutdown and loss, are the main reasons that affect the inverter conversion efficiency. On the other hand, the working frequency of WPT systems ranges from hundreds of kHz to a few MHz, and traditional voltage and current phasor estimation requires a very high sampling rate which is difficult to achieve. To overcome these limitations, this paper introduces a phase-shifting full bridge inverter using a zero-voltage switching (ZVS) soft switching technology to optimize the conversion efficiency of the inverter. Meanwhile, apparent power is introduced to detect the operating frequency and phase angle. Combined with an FPGA soft switching control strategy, this approach allows for the quick adjustment of the driving pulse of MOS transistors, as well as the voltage and current at the transmitting end, to a completely symmetrical state in real-time, effectively suppressing frequency offset and achieving efficient frequency tracking control and maximum efficiency tracking (MET) control of the WPT system. Through simulation and experiments, the ZVS soft switching technology has been achieved with the inverter control strategy, leading to improved conversion efficiency. The frequency offset that can be corrected can reach 0.1 Hz using the apparent power detection method, and the maximum transfer efficiency of the WPT system can reach 91%.

Design and simulation analysis of physical heat dissipation structure for welding robot controller

In order to understand the physical heat dissipation structure of welding robot controllers, the author proposes a research based on the design and simulation analysis of the physical heat dissipation structure of welding robot controllers. The author first analyzed that the design of welding heating system is the key to the research of welding robot heating technology, which is divided into the design of induction heating system temperature control circuit and temperature control program. The induction heating system is closely related to power electronics technology, with inverter design and soft switching technology being the focus and difficulty of this chapter. Secondly, using modular design methods, an induction heating system with a frequency of 450KHz and a power of 100 W is designed. This part is connected through an optocoupler and an induction heating system for power regulation and temperature control. Starting from designing the minimum system of a microcontroller, through keyboard input, temperature signal processing, analog-to-digital conversion, and finally to digital tube display output, the design of each module of the temperature control circuit was completed. Finally, in order to verify the effectiveness of the design, actual heat dissipation testing is required. By establishing an appropriate testing environment in the laboratory, the temperature changes and heat dissipation efficiency of the controller under different working conditions can be measured. Based on the actual test results, further adjustments and improvements can be made to the design to meet the heat dissipation needs of the welding robot.

Research on protection and control technology of power electronic transformers

As the key equipment in the modern power system, the power electronic transformer's performance and reliability play a vital role in the stable operation of the power system. This paper studies the soft switching technology, control technology and fault protection method of power electronic transformer. First, the soft switching technology of power electronic transformers is introduced, including zero voltage switching, zero current switching and so on. These soft switching technologies can effectively reduce the switching loss of the transformer, improve efficiency, and reduce electromagnetic interference and harmonic generation. Secondly, the control technology of power electronic transformer is introduced, including traditional proportional, integral, and derivative control (PID) control, model predictive control and direct power control. These control technologies can realize the precise control of the output voltage and current of the power electronic transformer, to meet the requirements of the power system for power quality and stability. In addition, this paper also introduces the fault protection methods of power electronic transformers, including short-circuit protection, over-voltage protection and over-medium current protection. These fault protection methods can effectively protect power electronic transformers from various faults and ensure their normal operation and safety.

Application of phase-shifted full-bridge soft-switch technology in suspension chopper

Suspension chopper is a high-power electrical equipment which controls the suspension state of maglev train. Its performance directly determines the stability and safety of maglev train. However, the traditional suspension chopper has the problem of high voltage spikes of IGBT and load, which poses a threat to the safe operation of high-speed maglev train. In order to solve this problem, this paper designs a phase-shifted full-bridge suspension chopper, which only adds an auxiliary circuit and four parallel capacitors. The soft-switch is realized by using the phase-shifted control signals, so as to reduce the voltage spikes. Compared with other voltage spike suppression methods, the method has the advantages of good suppression of voltage spikes, simple circuit structure, less use of components, and insensitive to component parameters. The performance of the designed circuit is simulated by ANSYS Simplorer, and verified by experimental test platform. The simulation and experimental results show that the phase-shifted full-bridge suspension chopper can greatly reduce voltage spikes of the load and IGBT.

Fixed Switching Frequency Hybrid Modulation With ZVS for Single-Phase Inverter

Soft switching technology is an effective way to reduce the switching loss of the single-phase inverter to improve efficiency. Because of the ease of implementing soft switching, inverter works in boundary conduction mode (BCM) is widely used. On the contrary, BCM causes wide variation in switching frequency and large inductor current ripple. In this article, a fixed switching frequency hybrid modulation method for the inverter is proposed, which can achieve zero-voltage switching without changing the switching frequency and reduce the peak value of inductor current. The modulation achieves good tracking of the output current with different loads by switching mode between the triangular mode and the trapezoidal mode accurately. For implementing modulation, the operation states of the inverter with different conditions are analyzed in detail, the number of operation states is deduced and the state machine about mode switching is summarized. In addition, a single-phase inverter prototype is designed to verify the feasibility and effectiveness of the proposed modulation. Compared with BCM, the efficiency of the inverter at both light load and full load is increased.

On modeling and real-time simulation of a robust adaptive controller applied to a multicellular power converter

Introduction. This paper describes the simulation and the robustness assessment of a DC-DC power converter designed to interface a dual-battery conversion system. The adopted converter is a Buck unidirectional and non-isolated converter, composed of three cells interconnected in parallel and operating in continuous conduction mode. Purpose. In order to address the growing challenges of high switching frequencies, a more stable, efficient, and fixed-frequency-operating power system is desired. Originality. Conventional sliding mode controller suffers from high-frequency oscillation caused by practical limitations of system components and switching frequency variation. So, we have explored a soft-switching technology to deal with interface problems and switching losses, and we developed a procedure to choose the high-pass filter parameters in a sliding mode-controlled multicell converter. Methods. We suggest that the sliding mode is controlled by hysteresis bands as the excesses of the band. This delay in state exchanges gives a signal to control the switching frequency of the converter, which, in turn, produces a controlled trajectory. We are seeking an adaptive current control solution to address this issue and adapt a variable-bandwidth of the hysteresis modulation to mitigate nonlinearity in conventional sliding mode control, which struggles to set the switching frequency. Chatter problems are therefore avoided. A boundary layer-based control scheme allows multicell converters to operate with a fixed-switching-frequency. Practical value. Simulation studies in the MATLAB / Simulink environment are performed to analyze system performance and assess its robustness and stability. Thus, our converter is more efficient and able to cope with parametric variation.

A zero‐current‐transition soft‐switching technique for T‐type NPC three‐level inverter

Based on the commutation property of the T-type neutral point clamped (T-NPC) three-level inverter, a novel zero-current-transition (ZCT) soft-switching topology is proposed. The proposed topology employs only two auxiliary switches and one inductor and capacitor (LC) resonant tank on each phase leg. The commutation process of the soft-switching technique is analyzed. The results show that all switches on main leg and auxiliary leg can achieve soft commutation without changing pulse width modulation (PWM) strategy. The control family of T-NPC three-level ZCT soft-switching topology are analyzed respectively, and then the resonant tank and timing schemes of different modes are given. Using two auxiliary switches in resonance can produce greater resonance current due to the combination of external excitation sources, which is more conducive to realize the soft-switching commutation of the main switch. At last, a half bridge prototype of T-NPC three-level inverter is built. The influence of equivalent internal resistance of power switches, diode reverse recovery and stray inductance for soft commutation is analyzed. The advantages of ZCT soft-switching technology is verified.

A Nonisolated Multiport Converter Based on LLC and Bidirectional Buck/Boost for Low Power EH-Battery Systems

Concerning about integration and high efficiency of topology, nonisolated multiport converters are widely researched in low power Energy-Harvesting-battery (EH-battery) systems. However, the pulse width modulation (PWM) based nonisolated multiport converters usually have the shortages of larger number of switches, ports’ voltage restrictions, hard switching, time-sharing transmission of energy and poor compatibility of MPPT algorithms. Therefore, in this article, a transformer-less multiport converter based on LLC and bidirectional buck/boost converter is proposed, which has the ability to step up and down voltage and well compatibility of MPPT. Meanwhile, soft switching technology is applied so that the converter can work in higher frequency and has smaller size. In addition, the energy can be transmitted simultaneously with the control of PWM and pulse frequency modulation (PFM). Finally, the experimental results of the proposed topology and its comparison with several topologies are given to prove the characteristics of the proposed converter

Research on Efficient Soft Switching Based on MPPT of PV Power Generation System

In this paper, basic soft-switching technology is proposed based on hard switching, and then the basic soft-switching technology is optimized, and an improved soft-switching technology is proposed to improve the conversion efficiency by reducing the switching loss. The simulation results show that the conversion efficiency of hard and basic soft switching is 94.3 and 96.1%, but the conversion efficiency of improved soft switching optimized on the basis of basic soft switching is only 95.8%. To solve this problem, an innovative soft-switching technology is put forward in this paper, and its conversion efficiency is as high as 96.3%, which is superior to the basic soft-switching technology.

Design and Implementation of Distributed Call-Center Based on Soft-Switch

Traditional PSTN-based Call-Center fail to meet agent distribution deployments and lower operating costs. With the development of NGN technology, Soft-Switch-based Call-Center has solved the pain points of enterprises. This paper analyzes the special needs of distributed Call-Center system, and on the basis of analyzing and studying Soft-Switch technology, the platform architecture of distributed Call-Center system based on VoIP is given. This paper focuses on the support process of SIP protocol for call control function of Call-Center system, as well as the key equipment in Soft-Switch system. Finally, a practical Soft-Switch system implementation scheme is introduced in conjunction with the project.

Research on anode power supply of low-power Hall thruster

Based on the small power, small size, and high-efficiency micro-thrust requirements of micro-satellites, this paper mainly studies the anode power supply topology suitable for micro-satellites. The flyback converter and the secondary volta ge doubler structure are used to achieve high gain. At the same time, in order to improve the efficiency, the resonant soft switching technology is used to achieve valley opening through the resonance of the transformer leakage inductance and the capacitor to realize the soft switching of the switch tube and the diode. This article developed a 250W experimental prototype, and conducted a series of no-load and full-load tests under closed-loop steady-state operation, which can realize the zero-voltage turn-on of the switch tube and the zero-current turn-off of the diode. The efficiency is up to 93.7% under full load conditions, while the output ripple is small and there is no oscillation, and the device stress is small, which proves to be suitable for use in the anode power supply of micro satellites.

State-of-the-Art Review on Soft-Switching Technologies for Non-Isolated DC-DC Converters

The soft-switching technology is widely used in DC-DC converters, DC-AC inverters, and AC-DC rectifiers. Soft-switching non-isolated DC/DC converters (Buck, Boost, and Buck-Boost) are the most active research area of the soft-switching technology, and fruitful results are achieved. However, there is currently no comprehensive review for the soft-switching technology of non-isolated DC/DC converters. This paper introduces soft-switching topologies for non-isolated DC/DC converters, and presents classification and characteristic of all kinds of soft-switching technologies. Some soft-switching technologies of derivative converters (non-inverting Buck-Boost converters and multiphase converters) are also presented. Finally future trends and generalized constitution methods of the soft-switching topology for non-isolated DC/DC converters are concluded. The soft-switching theory and constitution methods summarized in this article are expected to be able to guide the proposing of new soft-switching technologies for DC-DC converters.

Soft-Switching Technology of Three-Phase Six-Switch PFC Rectifier

An active clamp, three-phase, six-switch power factor correction rectifier with a one-cycle controller is proposed, which can effectively suppress the reverse recovery of the reverse parallel diode of the bridge arm switch and reduce the reverse recovery loss. The main switches and auxiliary switch are both zero-voltage switches. It works in a fixed switching frequency and low power stress during the switching period. The specific working process and control circuit are analyzed in detail, and the model simulation is carried out. The experimental platform of a 2.5 KW prototype, with a complete test and verification of the soft switch technology proposed in this paper, was set up in the laboratory.

A Back Propagation Neural Network with Double Learning Rate for PID Controller in Phase-Shifted Full-Bridge Soft-switching Power Supply

This paper mainly focuses on the control strategy for phase-shifting full-bridge soft switching electrolytic silver power supply based on Zero Voltage Switching (ZVS) soft switching technology. Taking into consideration the low performance of traditional PID control for phase-shifting full-bridge soft-switching, this paper introduce a PID improved by Back Propagation (BP) neural network with one single learning rate which is used to calculate weights from the input layer to the hidden layer and weights from the hidden layer to the output layer. After testing, it is found that setting independent learning rate for calculation of weights from the input layer to the hidden layer and weights from the hidden layer to the output layer which will not have an adverse effect on the design of the controller. Instead, the learning rate can be set according to the respective characteristics of the weights between the two layers, which is called double learning rate BP neural network PID. The simulation results indicate that compared with the single learning rate BP neural network PID control, the double learning rate BP neural network control has higher response speed, less over-shoot, short time to enter the steady state and strong immunity.

Application of high frequency chain transformer in aviation power supply

This paper introduces the application of the high frequency chain transformer in the aviation power supply. The soft switch technology is used to reduce the electromagnetic interference of the converter, solve the power supply problem of the rotating circuit which has no physical contact with the static power supply, and extend the service life and reliability of the aviation power supply. Experiments show that the non-contact rotary high frequency chain transformer can completely replace the brush and slip ring in the power supply situation of the rotating mechanism, which has high application value.

Research and Application of Soft Switching Technology in Power Dispatching Communication Network

Softswitch is the development direction of next-generation networks, which can better achieve network convergence and service convergence. Soft switching technology has gradually replaced circuit switching technology has become an inevitable trend. This paper analyzes the meaning of softswitch technology and the problems existing in China’s electric power dispatching network, and elaborates the specific application of softswitch in the electric power dispatching communication private network, and hopes to provide some inspiration for the research in this field.