Linearized large signal modeling, analysis, and control design of phase-controlled series-parallel resonant converters using state feedback

This paper proposes a linearized large signal state-space model for the fixed-frequency phase-controlled series-parallel resonant converter. The proposed model utilizes state feedback of the output filter inductor current to perform linearization. The model combines multiple-frequency and average state-space modeling techniques to generate an aggregate model with dc state variables that are relatively easier to control and slower than the fast resonant tank dynamics. The main objective of the linearized model is to provide a linear representation of the converter behavior under large signal variation which is suitable for faster simulation and large signal estimation/calculation of the converter state variables. The model also provides insight into converter dynamics as well as a simplified reduced order transfer function for PI closed-loop design. Experimental and simulation results from a detailed switched converter model are compared with the proposed state-space model output to verify its accuracy and robustness

Analysis of CLL voltage-output resonant converters using describing functions

A new ac equivalent circuit for the CLL voltage output resonant converter is presented, that offers improved accuracy compared with traditional FMA-based techniques. By employing describing function techniques, the nonlinear interaction of the parallel inductor, rectifier and load is replaced by a complex impedance, thereby facilitating the use of ac equivalent circuit analysis methodologies. Moreover, both continuous and discontinuous rectifier-current operating conditions are addressed. A generic normalized analysis of the converter is also presented. To further aid the designer, error maps are used to demonstrate the boundaries for providing accurate behavioral predictions. A comparison of theoretical results with those from simulation studies and experimental measurements from a prototype converter, are also included as a means of clarifying the benefits of the proposed techniques

Study of switching transients in high frequency converters

As the semiconductor technologies progress rapidly, the power densities and switching frequencies of many power devices are improved. With the existing technology, high frequency power systems become possible. Use of such a system is advantageous in many aspects. A high frequency ac source is used as the direct input to an ac/ac pulse-density-modulation (PDM) converter. This converter is a new concept which employs zero voltage switching techniques. However, the development of this converter is still in its infancy stage. There are problems associated with this converter such as a high on-voltage drop, switching transients, and zero-crossing detecting. Considering these problems, the switching speed and power handling capabilities of the MOS-Controlled Thyristor (MCT) makes the device the most promising candidate for this application. A complete insight of component considerations for building an ac/ac PDM converter for a high frequency power system is addressed. A power device review is first presented. The ac/ac PDM converter requires switches that can conduct bi-directional current and block bi-directional voltage. These bi-directional switches can be constructed using existing power devices. Different bi-directional switches for the converter are investigated. Detailed experimental studies of the characteristics of the MCT under hard switching and zero-voltage switching are also presented. One disadvantage of an ac/ac converter is that turn-on and turn-off of the switches has to be completed instantaneously when the ac source is at zero voltage. Otherwise shoot-through current or voltage spikes can occur which can be hazardous to the devices. In order for the devices to switch softly in the safe operating area even under non-ideal cases, a unique snubber circuit is used in each bi-directional switch. Detailed theory and experimental results for circuits using these snubbers are presented. A current regulated ac/ac PDM converter built using MCT's and IGBT's is evaluated

Study of the generator/motor operation of induction machines in a high frequency link space power system

Static power conversion systems have traditionally utilized dc current or voltage source links for converting power from one ac or dc form to another since it readily achieves the temporary energy storage required to decouple the input from the output. Such links, however, result in bulky dc capacitors and/or inductors and lead to relatively high losses in the converters due to stresses on the semiconductor switches. The feasibility of utilizing a high frequency sinusoidal voltage link to accomplish the energy storage and decoupling function is examined. In particular, a type of resonant six pulse bridge interface converter is proposed which utilizes zero voltage switching principles to minimize switching losses and uses an easy to implement technique for pulse density modulation to control the amplitude, frequency, and the waveshape of the synthesized low frequency voltage or current. Adaptation of the proposed topology for power conversion to single-phase ac and dc voltage or current outputs is shown to be straight forward. The feasibility of the proposed power circuit and control technique for both active and passive loads are verified by means of simulation and experiment

A comparative study of different optimization methods for resonance half-bridge converter

The LLC resonance half-bridge converter is one of the most popular DC-DC converters and could easily inspire researchers to design a high-efficiency and high-power-density converter. LLC resonance converters have diverse operation modes based on switching frequency and load that cause designing and optimizing procedure to vary in different modes. In this paper, different operation modes of the LLC half-bridge converter that investigate different optimization procedures are introduced. The results of applying some usual optimization methods implies that for each operation mode some specific methods are more appropriate to achieve high efficiency. To verify the results of each optimization, numerous simulations are done by Pspice and MATLAB and the efficiencies are calculated to compare them. Finally, to verify the result of optimization, the experimental results of a laboratory prototype are provided.Peer ReviewedPostprint (published version

Design of LLC resonant converter with silicon carbide MOSFET switches and nonlinear adaptive sliding controller for brushless DC motor system

Introduction. The high voltage gain DC-DC converters are increasingly used in many power electronics application systems, due to their benefits of increased voltage output, reduced noise contents, uninterrupted power supply, and ensured system reliability. Most of the existing works are highly concentrated on developing the high voltage DC-DC converter and controller topologies for goal improving the steady state response of brushless DC motor driving system and also obtain the regulated voltage with increased power density and reduced harmonics, the LLC resonant DC-DC converter is implemented with the silicon carbide MOSFET switching devices Problem. Yet, it facing the major problems of increased switching loss, conduction loss, error outputs, time consumption, and reduced efficiency. Also the existing works are mainly concentrating on improving the voltage gain, regulation, and operating performance of the power system with reduced loss of factors by using the different types of converters and controlling techniques. The goal of this work is to obtain the improved voltage gain output with reduced loss factors and harmonic distortions. Method. Because, this type of converter has the ability to generate the high gain DC output voltage fed to the brushless DC motor with reduced harmonics and loss factors. Also, the nonlinear adaptive sliding controller is implemented to generate the controlling pulses for triggering the switching components properly. For this operation, the best gain parameters are selected based on the duty cycle, feedback DC voltage and current, and gain of silicon carbide MOSFET. By using this, the controlling signals are generated and given to the converter, which helps to control the brushless DC motor with steady state error. Practical value. The simulation results of the proposed LLC silicon carbide MOSFET incorporated with nonlinear adaptive sliding controller controlling scheme are validated and compared by using various evaluation indicators. Вступ. Високовольтні перетворювачі постійного струму з високим коефіцієнтом посилення напруги все частіше використовуються в багатьох прикладних системах силової електроніки через їх переваги, пов'язані з підвищеною вихідною напругою, зниженим рівнем шуму, безперебійним живленням і гарантованою надійністю системи. Більшість існуючих робіт значною мірою зосереджені на розробці топологій високовольтного перетворювача постійного струму і контролера з метою поліпшення усталеного відгуку системи приводу безщіткового двигуна постійного струму, а також отримання регульованої напруги з підвищеною щільністю потужності і зменшеними гармоніками; резонансний LLC-перетворювач постійного струму, реалізований на перемикаючих пристроях на основі польових МОП-транзисторах з карбіду кремнію. Проблема. Тим не менш, це стикається з основними проблемами, пов'язаними зі збільшенням втрат при перемиканні, втратами провідності, помилками на виході, витратами часу та зниженням ефективності. Крім того, існуючі роботи в основному зосереджені на покращенні коефіцієнта посилення напруги, регулювання та робочих характеристик енергосистеми із зменшенням факторів втрат за рахунок використання різних типів перетворювачів та методів управління. Метою роботи є отримання покращеного коефіцієнта посилення напруги зі зниженими коефіцієнтами втрат і гармонійних спотворень. Метод. Таким чином, цей тип перетворювача здатний генерувати вихідну постійну напругу з високим коефіцієнтом посилення, що подається на безщітковий двигун постійного струму, зі зменшеними коефіцієнтами гармонік та втрат. Крім того, реалізований нелінійний адаптивний ковзний регулятор для генерування керуючих імпульсів для належного спрацьовування перемикаючих компонентів. Для цієї операції вибираються найкращі параметри посилення на основі робочого циклу, постійної напруги та струму зворотного зв'язку, а також коефіцієнта посилення польового МОП-транзистора з карбіду кремнію. При цьому керуючі сигнали генеруються і передаються на перетворювач, який допомагає керувати безщітковим двигуном постійного струму з помилкою, що встановилася. Практична цінність. Результати моделювання запропонованого LLC-перетворювача на основі польових МОП-транзисторів з карбіду кремнію зі схемою управління нелінійним адаптивним ковзним регулятором перевіряються та порівнюються з використанням різних показників оцінки.&nbsp

Implementation of standalone dynamic solar array fed permanent magnet synchronous motor drive using zero voltage switching resonant converter for the reduction of switching losses and oscillations

The Proposed research deals implementation of standalone dynamic solar array fed permanent magnet synchronous motor drive using zero voltage resonant switch converter for the reduction of switching losses and oscillations. The closed loop control voltage strategy has been proposed for power flow management between solar photovoltaic (PV), battery, motor load and to maintain constant load voltage to perform continuous MPPT operation of solar PV. For improving the efficiency and to reduce vibration across the load SPV array fed Zero Voltage Switching (DISOZVS) Resonant Converter with permanent magnet synchronous motor (PMSM) drive is proposed. The DISOZVS resonant converter with suitable switching operation accomplishes for the purpose of reducing the Switching losses. The ZVS converter is constructed by a buck-boost circuit, which is operated as a buck circuit when charging and a boost circuit when discharging. So, we can use many power related systems, which improves efficiency, lower losses and higher performance. The various dynamics and oscillations of standalone SPV array is analysed in the proposed research. The performance of the proposed system is simulated in MATLAB/Simulink atmosphere and various parameters outputs are carried. A hardware prototype of the proposed system has been fabricated for the proposed converter and various analysis were incorporated. The working of the proposed scheme for the different levels of input solar insolation and Load power demand has been satisfactorily demonstrated for both simulation and experimental compared to conventional it results more efficient with reduced losses and oscillations

Industrial and Technological Applications of Power Electronics Systems

The Special Issue "Industrial and Technological Applications of Power Electronics Systems" focuses on: - new strategies of control for electric machines, including sensorless control and fault diagnosis; - existing and emerging industrial applications of GaN and SiC-based converters; - modern methods for electromagnetic compatibility. The book covers topics such as control systems, fault diagnosis, converters, inverters, and electromagnetic interference in power electronics systems. The Special Issue includes 19 scientific papers by industry experts and worldwide professors in the area of electrical engineering

Simulation of speed tracking for brushless DC motor using fuzzy logic controller

Brushless DC motors are normally used in an automotive application, robotics, medical, industrial automation equipment and machine tools due to its advantages. The advantages are long life operation, easy to construct, noiseless operation and has a better speed performance. This project presents a simulation model for BLDC motor using MATLAB/Simulink. Usually, the speed control is achieved by using PI controller. Then, the dynamic response of the BLDC motor such as speed, torque as well as current and voltage are observed and been analyzed using the MATLAB model. It is quite hard and difficult to tune the conventional PI controller parameters. Therefore, a suitable speed controller is been developed by using MATLAB Fuzzy Logic tool box. The objectives of this project are to minimize the maximum overshoot (%OS), settling time (Ts) and also peak time (Tp). Besides, the purpose is to improve the speed performance of the motor drive system. In order to verify the effectiveness of the controller, both control algorithms (Fuzzy logic control and PID) are compared. The simulation results show that the FLC controller has better performance which has reduced and minimized the percentage of maximum overshoot, settling time, peak time and rise time compared with the used of conventional PI controller

Energy-efficient and Power-dense DC-DC Converters in Data Center and Electric Vehicle Applications Using Wide Bandgap Devices

The ever increasing demands in the energy conversion market propel power converters towards high efficiency and high power density. With fast development of data processing capability in the data center, the server will include more processors, memories, chipsets and hard drives than ever, which requires more efficient and compact power converters. Meanwhile, the energy-efficient and power-dense converters for the electric vehicle also result in longer driving range as well as more passengers and cargo capacities. DC-DC converters are indispensable power stages for both applications. In order to address the efficiency and density requirements of the DC-DC converters in these applications, several related research topics are discussed in this dissertation. For the DC-DC converter in the data center application, a LLC resonant converter based on the newly emerged GaN devices is developed to improve the efficiency over the traditional Si-based converter. The relationship between the critical device parameters and converter loss is established. A new perspective of extra winding loss due to the asymmetrical primary and secondary side current in LLC resonant converter is proposed. The extra winding loss is related to the critical device parameters as well. The GaN device benefits on device loss and transformer winding loss is analyzed. An improved LLC resonant converter design method considering the device loss and transformer winding loss is proposed. For the DC-DC converter in the electric vehicle application, an integrated DC-DC converter that combines the on-board charger DC-DC converter and drivetrain DC-DC converter is developed. The integrated DC-DC converter is considered to operate in different modes. The existing dual active bridge (DAB) DC-DC converter originally designed for the charger is proposed to operate in the drivetrain mode to improve the efficiency at the light load and high voltage step-up ratio conditions of the traditional drivetrain DC-DC converter. Design method and loss model are proposed for the integrated converter in the drivetrain mode. A scaled-down integrated DC-DC converter prototype is developed to verify the design and loss model