Load Resonant Converter Research Articles

Control of Instabilities in Resonant Converters Using Half‐Period Time Delay Output Feedback

ABSTRACTBifurcation phenomena in power electronic converters lead to undesired instabilities. In this paper, different types of bifurcations are identified, which can occur in a series load resonant converter with the variation of the parameters for example, input voltage, load resistance, and so forth. These instabilities are associated mainly to three different bifurcations: (a) Neimark–Sacker, (b) saddle–node, and (c) symmetry breaking bifurcations. Due to the symmetry property of load resonant converters, a half‐period time delay output feedback control is used to avoid all of these instabilities. The ideal time delay is realized by a first‐order all‐pass‐filter. The stability analysis is performed and the values of the feedback gains are determined to identify the stable domain in the parameter space. By identifying the unstable orbits, the analytical stability analysis helps to understand as well as to control the mechanisms of these instabilities, which extends the stability domain of the system. This study can also be extended to other load resonant converters where the symmetry property naturally exists.

36-5-2] 24V 전원 기반의 60kV 고전압 커패시터 충전기의 설계

In this paper, a 60kV high voltage capacitor charger(HVCC) based on a 24V battery was described. The HVCC should satisfy not only the extreme voltage gain for 60kV output based on 24V input but also compact size and lightweight for portability despite the high current burden due to the low input voltage. In addition, there are other considerations such as the voltage stress of each component and insulation. Considering these matters, the HVCC was designed based on the parallel loaded resonant converter and symmetrical Cockcroft-Walton voltage multiplier(CWVM). The parallel load resonant converter enables high-frequency operation by reducing switching losses through the zero voltage switching turn-on and snubber capacitor for soft turn-off. With proper design followed by analysis, the HVCC is capable of ZVS turn-on from the start of charging to charging the target voltage. Two symmetrical CWVMs are connected in parallel to the center-tapped transformer to alleviate voltage stress and insulation design difficulty of high-voltage devices. Through PSpice simulation, it was verified that the HVCC satisfies the target specification and the soft switching operation, and the electric field analysis was performed.

Analysis and design of efficient SiC-based load-resonant converter with advanced features for arc welding applications

Analysis and design of efficient SiC-based load-resonant converter with advanced features for arc welding applications

High Frequency MOSFET Charging Circuit Using Series Parallel DC-DC Resonant Converter for Wireless Power Application

This paper proposes a new circuit topology of high frequency switching DC-DC Series Parallel Loaded Resonant Converter (SPLRC). The circuit is proposed to be used for a wireless power transmission application that required fast-charging operation. Most of the components used here are low-cost and commercially available in the market. Then, the purpose circuit is transformed into a different equivalent circuit that can efficiently analyze AC and DC modes. For each model, the operation for the converter is first described and explained. A full detailed circuit simulation is then carried out to find out the workability of the purpose converter. From the simulation, optimization is carried out. Here the components value is obtained. MATLAB R2018A is used for simulation purposes rather than being tested again using PSIM software to further prove the validity of the model. All the finding is explained and discussed, here, from the simulation result, it is confirmed that a high-frequency switching circuit is operated as expected.

Comparison of Control Techniques for Series Resonant Converter

There are many different derivatives of the variable and fixed frequency switching control techniques used in the control of load resonant converters. In this study; among these techniques frequency modulation (FM), phase shift modulation (PSM) and pulse density modulation (PDM) are applied separately to series resonant converter (SRC). The techniques are examined and compared in many respects. An experimental setup was built, which consists of a 400W converter (with the input voltage of 200 V and the output voltage of 36V), a control circuit and a resistive load to verify the theoretical studies. The converter is controlled by FM, PSM and PDM separately for 120 kHz basic operating frequency and different output currents. The experimental results are compared in terms of efficiency, output voltage ripple, soft switching, switch voltage and ease of application and hardware. The comparison results are presented. It is observed that FM has better performance than the other two techniques in many aspects.

Suppression of Chattering in the Real-Time Simulation of the Power Converter

The achievement of the time-step below 500-ns in the field-programmable-gate-arrays (FPGAs)-based real-time simulation is of importance for the power converters having high switching frequencies. However, most of the existing focus on addressing the power converter modeling under the continuous conduction mode (CCM). Nevertheless, toward practical applications, the modeling of discontinuous conduction mode (DCM) with a light-load is of a greater challenge due to the “chattering” around zero point. In order to solve the chattering problem under the light-load, this article proposes a zero-regulation (ZR) method for FPGA-based real-time simulation. The proposed ZR method can not only represent CCM and DCM with a unified formula but also solve the chattering problem and improve accuracy and stability. In addition, results using different switch models are also given to demonstrate the feasibility and the generality of the proposed method. Finally, a case study of the series load resonant converter is presented. Simulation results are validated against a reference model at a 100-ns time step and a 10-kHz switching frequency.

Analysis and Design of a New Current-Source Output Load Resonant Converter With High Capability in Line and Load Regulation

In this paper a fourth-order Passive Resonant Tank (PRT) is introduced using a topological modification in LLC tank for current-source output applications of Load Resonant Converters (LRCs). The design procedure is based on the output current/input voltage ratio decoupling from the load coefficient. Therefore, output current can be independent of load variation topologically. In this condition, new criterions are applied on the operational frequency and PRT components ratio. Moreover, kVA/kW ratio of the LRC is considered as a comparing index, to optimize the converter size as well as reduction of voltage/current stresses on the PRT components. To reduce the discrete components number, transformer parasitic inductances and bridge capacitors are used as the PRT components. Also, a simple and accurate PWM-based Quasi-Proportional Controller (QPC) is designed to maintain the output current constant against input voltage variations. Minimum reactive power, low circulating and turn-off current, and ZVS of the inverter switches in a wide loads range are obtained as the advantages of the designed LLCC-LRC. Moreover, sinusoidal shape of the PRT input current and minimum switching losses on the rectifier are maintained. Finally, an experimental prototype with 3.5A output current and 93.9% efficiency is presented for results verification.

Fifth‐order Π‐type load resonant converters analysis based‐on immittance property for constant output current applications

SummaryPassive resonant tanks (PRTs) with immittance property are suitable candidates to achieve constant output current in load resonant converters (LRCs). In this paper, fifth‐order Π‐type LC networks are investigated to accede this target. At the first step, fifth‐order Π‐type passive LC networks that can be applied as a PRT are specified based on source and sink natures. Also, their structural advantages are described in detail to give a suitable perspective for the topology selection. At the second step, immittance property is verified for the proposed topologies and immittance PRTs (IPRTs), with their immittance operation conditions, are derived. To confirm the effectiveness, a 150‐W LRC is implemented leveraging new Π‐type IPRTs. A deep investigation is devoted to analyze the current/voltage stress in the components of the designed LRC. Moreover, kVA/kW ratio is considered as a key parameter for the reactive component size minimization. The proposed constant current LRC presents high load regulation capability in addition to the minimum reactive power and zero‐voltage switching (ZVS) on the inverter MOSFETs under the various loads. A significant robustness against load variations, less sensitivity versus parameters variation, and relatively higher efficiency are the main superiorities of the fifth‐order IPRTs to the lower order counterparts.

New Parallel Loaded Resonant Converter With Wide Output Voltage Range

This paper proposes a new parallel loaded resonant converter operating in a narrow switching frequency under wide output voltage range. The proposed converter is capable of operating under zero-voltage switching turn-on of switches and zero-current switching turn-off of diodes. Also, the resonant capacitor with feasible capacitance and current rating can be selected by adjusting the turn ratio of the transformer, making the proposed converter more realizable in high power application. Further, the proposed converter has zero voltage gain at notch resonant frequency, and therefore there are no current and voltage stress in the resonant tank during start-up. Experimental results from a 3-kW prototype are provided to validate the proposed concept.

Novel Design of LLC Resonant Converter with Peak Gain Adjustment

The main advantages of a half-bridge LLC resonant DC/DC converter having two inductors (LL) and a single capacitor (C) compared to the other load resonant converters are its less amount of circulating currents and large bandwidth for Zero Voltage Switching (ZVS). It also has the advantage of limited tuning of operating frequency to get the regulated output when variable frequency control method is implemented on the converter. This DC/DC converter is widely used in server and telecom applications due its higher efficiency and reliability. In this paper, a novel design using peak gain adjustment is proposed for a LLC resonant DC/DC converter with a design example of 400V/12V-5A used in server based applications. For the specifications of the converter mentioned, an experimental set up is built and evaluated with the Texas instruments power switch FSFR 2100 IC in closed loop configuration. The experimental results proved an improved efficiency of 94% for the converter with the novel design proposed.

Non‐linear modelling and stability analysis of resonant DC–DC converters

Resonant dc–dc converters have found increasing application in industry in recent times. Yet, the methods of dynamical analysis and parameter design for this kind of system are not well developed. The averaging method cannot be used in such converters as the small-ripple assumption does not hold. The sampled-data model, which seeks to obtain a closed form expression of the state at a clock instant in terms of that at the previous clock instant, also becomes unwieldy for converters with many topological modes – a condition prevailing in all resonant converters. In this study the authors show that the Filippov method can be effectively applied for accurate s-domain small signal analysis as well as time domain stability analysis by locating the stability boundaries in the paramater space for such systems. The authors apply this method to three classes of resonant converters – the switch resonant converter, the resonant transition converter and the load resonant converter – and present the mechanisms by which these converters may lose stability as the parameters are varied. The theoretical results corresponding to the resonant transition converter are validated experimentally.

Simulation of Pulse Amplitude Modulation based Voltage Control Technique for the Speed Control of BLDC Motor using Class-E Load Resonant Converter

Simulation of Pulse Amplitude Modulation based Voltage Control Technique for the Speed Control of BLDC Motor using Class-E Load Resonant Converter

Design of Plasma Generator Driven by High-frequency High-voltage Power Supply

In this research, a high-frequency high-voltage power supply designed for plasma generator is presented. The powersupply mainly consists of a series resonant converter with a high-frequency high-voltage boost transformer. Due to theindispensable high-voltage inheritance in the operation of plasma generator, the analysis of transformer needconsidering not only winding resistance, leakage inductance, magnetizing inductance, and core-loss resistance, butalso parasitic capacitance resulted from the insulation wrappings on the high-voltage side. This research exhibits asimple approach to measuring equivalent circuit parameters of the high-frequency, high-voltage transformer with straycapacitance being introduced into the conventional modeling. The proposed modeling scheme provides not only aprecise measurement procedure but also effective design information for series-load resonant converter. The plasmadischarging plate is designed as part of the electric circuit in the series load-resonant converter and the circuit modelof the plasma discharging plate is also conducted as well. Thus, the overall model of the high-voltage plasmagenerator is built and the designing procedures for appropriate selections of the corresponding resonant-circuitparameters can be established. Finally, a high-voltage plasma generator with 220V, 60Hz, and 1kW input, along witha 22 kHz and over 8kV output, is realized and implemented.

Investigation of Plasma Generator Driving by High-Frequency High-Voltage Electric Source

In this paper, a series resonant converter with high-frequency high-voltage transformer for plasma generator is presented. The high-frequency, high-voltage electric source is designed by employing a series load-resonant converter with the plasma generator as part of the electric circuit. The equivalent circuit of this high-frequency transformer modeled by the introduction of the stray capacitance is proposed and the circuit model of the high-voltage plasma generator is conducted as well. Thus, the overall model of the high-voltage plasma generator is built and the designing procedures for appropriate selections of the corresponding resonant-circuit parameters can be established. Finally, a high-voltage plasma generator with 220V, 60Hz, and 1kW input, plus a 22 kHz and over 8kV power converter output, is realized and implemented.

A Novel Loaded-Resonant Converter for the Application of DC-to-DC Energy Conversions

Among the many advantages that resonant power conversion has over conventionally adopted pulse-width modulation include a low electromagnetic interference, low switching losses, small volume, and light weight of components due to a high switching frequency, high efficiency, and low reverse-recovery losses in diodes owing to a low di/dt at switching instant. This work presents a novel loaded-resonant converter for direct current (dc)-to-dc energy conversion applications. The proposed topology comprises a half-bridge inductor-capacitor-inductor (L-C-L) resonant inverter and a bridge rectifier. Output stage of the proposed loaded-resonant converter is filtered by a low-pass filter. A prototype dc-to-dc energy converter circuit with the novel loaded-resonant converter designed for a load is developed and tested to verify its analytical predictions. The measured energy conversion efficiency of the proposed novel loaded-resonant topology reaches up to 88.3%. Moreover, test results demonstrate a satisfactory performance of the proposed topology. Furthermore, the proposed topology is highly promising for applications of power electronic productions such as switching power supplies, battery chargers, uninterruptible power systems, renewable energy generation systems, and telecom power supplies.

High-frequency load-resonant DC-DC converters

This tutorial is concerned with one type of resonant DC-DC converter in which the load forms part of a continuously oscillating resonant circuit. The operating principle and device switching waveforms are first examined; a common analysis method is then used to derive and compare the characteristics of the two principal converter topologies: parallel loaded converter and series loaded converter.

Optimisation of a power 4H–SiC SIT device for RF heating applications

In this paper, the optimisation procedure for a static induction transistor (SIT) in silicon carbide is described and its application in a typical RF heating circuit is presented. A field plate edge termination is optimised for a 10 μm thick epitaxial layer with doping in the range 10 15 cm −3 to 10 16 cm −3. Results show a breakdown voltage of 1280 V, corresponding to 68% of the theoretical value. For the chosen application an epitaxial layer doping level of 5×10 15 cm −3 is revealed to offer the best compromise. This allows pinch off of drain voltages exceeding 600 V from a 20 V gate drive whilst achieving a current density of 250 A cm −2 at an on-state voltage of less than 1 V. Transient simulations are performed for a series load resonant converter with a switching frequency of 27.12 MHz. The results emphasise the suitability of the device for RF heating applications.

Load-resonant converter design modification usingcircuit-scaling laws

Previous work of the authors and their colleagues described the development of an easily-understood design technique for load-resonant converters. Unfortunately, although the technique has been used successfully in practice, it requires some tedious trial and error calculation schemes. In the Letter it is shown how the original design can be modified using circuit scaling laws. These laws require very simple calculations to implement thereby avoiding the tedious calculation required for each design alteration in the prototype circuit.

Constant frequency, constant current load-resonant capacitor charging power supply

A capacitor charging power supply incorporating a series–parallel load-resonant converter, operating at resonance at a fixed frequency and providing a constant load current, is presented. A series–parallel load-resonant converter containing three resonant components is shown to have three resonant frequencies. It is shown that one of the resonant frequencies can be independent of the load value. Furthermore such a converter can be designed to supply constant current to a load. The circuit characteristics enable the power converter to efficiently charge a capacitor bank with minimum control circuitry. The resonant converter can be operated at a single frequency throughout the whole capacitor charging cycle from 0 V to 640 V. A power supply is constructed which delivers up to 2.6 kW to a large capacitor bank, charging the bank from 0 to 640 V at a constant switching frequency of 83 kHz. The power supply draws 0.9 power factor with no power factor correction circuitry.

Load-resonant converter with zero current switchingand variable output power

The authors present a half-bridge series-parallel load-resonant converter in which the resonant circuit has been designed so that the circuit can operate near to resonance over a wide frequency range. The output power of the circuit varies continuously over this frequency range, resulting in a load-resonant converter with zero current soft-switching over a range of output power. The prototype constructed shows a power variation of 2:1 over a frequency range of 30 kHz.