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Please follow the links to view the publication.High-speed thermography of fast dynamic processes on electronic switching devices
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0707
Electro technical machines and systems have to provide a permanent operational safety in every phase of their lifecycle. An interruption or failure, e.g. of the DC24V energy supply, must not cause any dangerous situation for man or machine. A selective protective function is achieved by using electronic or mechanical circuit breakers mainly consisting of an integrated printed circuit board (pcb) with a number of conductive paths and components. PCBs and components respond to current variations respectively overcurrent with partly punctual thermal changes which can be tolerated up to a certain limit. A thermally and geometrically high-resolution real-time thermography system monitors fast electrical changes in loadings on electronic circuit breakers which immediately result in thermal effects on the electronic system. The infrared thermography visualises the thermal loadings occurring in conductive paths and electronic components. The data determined by this innovative medium will be put into relation to the electrical loadings. Conclusions to the component and pcb-layout efficiency are drawn from the temporally high-resolved heating processes in the millisecond range. Due to these data, the electronic circuit breaker will be miniaturised. The high-speed thermography compares variously dimensioned devices during electrical loads with regard to their thermal management. As proof of feasibility, the heating processes are displayed in quick movies depending on pcb dimensions and electrical loads.Study on digital controller of multi-task interleaving parallel BUCK modules
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0643
Take three parallel Buck modules for example. By adopting master-slave current sharing technology, a digital controller is designed on the basis of DSP56F807 and μC/OS II operating system. As the key parts of the research, interleaving parallel technology and current sharing strategy, as well as the scheduling and division of the task modules, is introduced in detail. The parallel power system and the design of real-time multi-task software play a significance role for the improvement of the reliability of the system.The numerical simulation and reliability analysis of through-hole solder joints
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0693
In this paper, numerical simulation was performed on the through-hole solder joints of a LED driver, and reliability analysis was carried out. Taking the simulation speed and time into account, firstly the thermal field of the LED driver was simulated, which was then verified by infrared thermograph. Then the thermal-stress simulation was conducted on the solder joints which were of the highest temperature. The results demonstrated that the failure of through-hole solder joints mainly occurred in the interface between solder and substrate, which is the crack initiation zone. Analyzing the stress and strain of solder joints under temperature cycling, this paper used the modified Coffin-Manson formula to predict the life expectancy, and provided an assessment methodology of reliability analysis for through-hole solder joints.Fault analysis of multi-DC converter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0691
Studied the components' affect to the high-capacity multi-DC converter system, through theoretical analysis and simulation, the author discussed the system's operation state when the inductance, capacitance, IGBT, freewheeling diode respectively went wrong. Then got the conclusion, when there is a fault in the parallel system, the output voltage and current will be lack phase, ripple excessive, current discontinuous and so on.Development of a novel 5kW/42V intelligent converter for automotive applications
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0313
Growing pressure on the automotive industry to produce cars with less exhaust emission, better fuel economy, and to save energy necessitated the introduction of higher voltage electrical power system to meet these requirements in short to mid-term. Already, various electric systems architectures have been proposed and investigated over the past ten years. To meet such growing demands, the automotive industry has to move to higher voltage and the 42V power-net system is the preferred option [8]. The 42V is further processed by the interleaved six-phase dc-todc buck converter system to supply power to the conventional automotive loads that are expected to remain at 14V level as well as to absorb the peak transients on the 42V bus voltage. A special DC/DC converter is therefore needed to interconnect the 14V and the 42V DC buses in the car of the future. Automotive electronics place severe demands on the performance and price of power electronic components and making the development of a suitable converter a challenging task. This paper will present the initial development of the 5kW/42V intelligent converter for automotive applications using Matlab/Simulink. (6 pages)The best of both worlds: Fibonacci and binary switched capacitor converters combined
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0211
A simple algebraic approach to synthesis Fibonacci Switched Capacitor Converters (SCC) is analyzed and the expected losses are estimated. The proposed approach reduces the power losses by increasing the number of target voltages. The synthesized Fibonacci SCC is compatible with the binary SCC and uses the same switch network. This feature is extremely beneficial since it provides the option to switch between the binary and Fibonacci target voltages, increasing thereby the resolution of attainable conversion ratios. The theoretical results were verified by experiments. (5 pages)Trans-Z-source neutral point clamped inverter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0236
Transformer based Z-source (trans-Z-source) inverters are recently proposed by extending the traditional Z-source inverter with higher buck-boost capability as well as reducing the passive components at the same time. Multi-Level Z-source inverters are single-stage topological solutions used for buck-boost energy conversion with all the favourable advantages of multi-level switching retained. This paper presents three-level trans-Z-source Neutral Point Clamped (NPC) inverter topology, which achieves both the advantages of trans-Z-source and three-level NPC inverter configuration. With proper modulation scheme, the three-level trans-Z-source inverter can function with minimum of six device commutations per half carrier cycle (same as the traditional buck NPC inverter), while maintaining to produce the designed volt-sec average and inductive voltage boosting at ac output terminals. The designed topology and modulation control are tested by Matlab simulation and experimental laboratory prototype with captured results shown in the latter sections. (5 pages)Simulation and modelling of power passive components for EMI prediction
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0209
This paper presents methods to simulate and model the power passive components for EMI prediction. Analysis of the high frequency characteristics of passive components is firstly performed. Then for the prediction of EMI, high frequency performances of passive components are predicted using proposed method. Based on the predicted characteristic of passive components, their high frequency models can be built and used for EMI prediction. To illustrate and verify the proposed method, inductor examples and capacitor examples are simulated and measured. (6 pages)Analysis and design of coupled inductor for a new single phase transformerless photovoltaic inverter topology
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0195
The demand of photovoltaic (PV) converters with high efficiency and low cost has supported the investigations in new topologies in the last years. Especially transformerless topologies are able to achieve highest efficiency values and lowest specific costs [1]. In order to support these goals as well as to obtain a high power density [2] the functional integration of magnetic components is a known technique. Integrated magnetic components will lead to reduced number of magnetic components and are able to achieve application specific functions [8]. This paper will present the design of a coupled inductor for a new transformerless buck-boost inverter topology for photovoltaic applications. The coupled inductor will serve as energy storage as well as transformer in order to transfer the power to the grid. As basis for the inductor development the inverter topology will be briefly explained. The design procedure including an analysis of the magnetic components is presented as well as simulation and experimental results. (6 pages)New design approach for higher energy efficiency with parallel converter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0225
This paper proposes a new design approach for two non-identical converters connected in parallel to obtain higher efficiency across the load range. This is achieved by allowing one converter to be designed for efficiency, without being constrained by system requirements, such as the transient response and current ripple, which will be met by the second converter. The efficiency of the proposed parallel converter is compared to an interleaved converter, both in theory and in practice. (6 pages)Analysis of dead-time effects in multi-phase voltage source inverters
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0170
Inverter dead-time effects have been investigated in past for three-phase voltage source inverters. Also, there have been some studies about multi-phase (more than three phase) inverters with reference to multiphase drives. Recently, a great deal of research has concentrated on PWM methods suitable for multi-phase VSIs. All PWM methods theoretically produce sinusoidal output voltages without low-order harmonics. This paper analyzes the dead-time effects on output variables of voltages source inverters if no any compensation technique is applied. In particular, an overview of three-phase inverters is considered first. Then, a generalized extension to multi- phase inverters is proposed and investigated in details. Theoretical analysis has shown that particular low-order harmonics appear as result of dead-times, and simulation results confirm the proposed analytical approach. (6 pages)Analysis of failure rate prediction by using part stress method for printed circuit board assemblies in power electronics building block
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0335
In this paper, the reliability prediction of a power electronics building block (PEBB) printed circuit board assembly (PCBA) is performed using the Part Stress Method from the MIL-HDBK-217FN2 handbook. The breakdown of the predicted reliability with respect to circuit functional blocks is presented. Furthermore, different cases are shown, where the components with small or large failure rate dominate. Finally, the ANSI-VITA51.1 adjustments are applied and their influence on the reliability prediction results and their usage are discussed. (5 pages)Evaluation of perturb and observe MPPT algorithm implementation techniques
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0156
Because of its simplicity and ease of implementation, the perturb and observe (P&O) algorithm is the most commonly applied maximum power point tracking (MPPT) control scheme in photovoltaic (PV) applications. Two techniques are usually used for implementing the P&O algorithm: reference voltage perturbation where a reference value for the PV generator output voltage is used as the control parameter and direct duty ratio perturbation where the duty ratio of the MPPT converter is used directly as the control parameter. This paper presents an experimental comparison between these two techniques when used in a photovoltaic system feeding a resistive load. The influence of the step size and the speed at which the control parameter is perturbed is investigated. The various advantages and drawbacks of each technique are identified and energy utilization efficiency is calculated for different weather conditions. Practical results obtained using a 540Wp PV experimental setup show very good agreement with numerical simulations. (6 pages)Matrix converter clamp current reconstruction for fault detection
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0230
Matrix converters offer advantages over traditional AC-AC conversion technologies in high temperature environments; however in system critical applications were operation is paramount, it is desirable for the converter to continue operation under fault conditions, albeit with degraded performance. There have been several works in literature on the subject of fault tolerant matrix converters however all of these methods require a method of fault localisation for continued operation in the fault condition. It is also desirable for the fault detection and localisation scheme to use existing sensors to minimise cost. This paper describes a method of fault detection and localisation using only the existing sensors used in the operation of the converter and information know by the converters modulator. (6 pages)In-situ bond wire health monitoring circuit for IGBT power modules
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0239
IGBT power module field reliability prediction methods are continuously being developed to increase availability and reduce system downtime. This paper presents a precursor parameter in-situ monitoring methodology for health diagnosis and lifetime estimation with a focus on wire bond interconnections. The bond wire degradation is typically an end-of-life phenomenon and indicates an impending final breakdown. A novel in-situ health monitoring circuit capable of accurately detecting the wire bond interconnection degradation in IGBT modules is implemented. This circuit can be integrated as part of an electric drive allowing the assessment of the devices in a three phase inverter drive in real application. This can improve the understating of the wire bond's degradation behaviour in both lab environment and field applications. Experimental results are presented to demonstrate the capability of the proposed method. (6 pages)Advances in the dynamic active cooling of power electronic modules
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0241
This paper presents the design and demonstration of a regulation circuit for active cooled power modules: the power dissipation within heat generating elements is sensed and the bias voltage of a fan is continuously adapted to try and keep the temperature at a given assembly location constant, thus reducing thermal cycling in the assembly to extend its operational lifetime. This work enhances previous achievements in this area by implementing a non-linearized, non-approximated regulation circuit. The results indicate a dramatic improvement in the regulation capability and thermal cycle amplitude reduction, both in the steady-state and in the transient domain. (5 pages)Capacitor voltage balancing in modular multilevel converters
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0158
A universal capacitor voltage control method for converters built from series connected modules is presented. It fully exploits both the circulating currents and the common-mode voltage without affecting the phase current control. The controllability of the capacitor voltages in various such converters is investigated. It is found that the nonzero branch currents and terminal voltages are necessary for capacitor voltage balancing. (5 pages)Impedance characterization of high frequency power electronic circuits
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0240
Wide bandgap semiconductors as Silicon Carbide (SiC) lead to devices with smaller body capacitances and thereby support the continuous rise of operating frequency and switching speed of switch mode power supplies. However, parasitic elements coming from the real world setup gain more and more impact on system performance. In order to identify parasitic circuit components and corresponding resonances, this work is about small-signal impedance spectra measurements of power electronic circuits. Knowing the involved parasitics, destructive resonance phenomena can be avoided and electromagnetic radiation can be reduced. In order to include voltage drift effects of capacitive circuit elements, also impedance measurements with high voltage DC-bias were performed. For that, a broadband DC-blocker with 1 kV bias voltage rating was developed. Exemplary, two applications were investigated closer: a power semiconductor dynamic test circuit and an RF half-bridge inverter for the pulsed operation of dielectric barrier discharge (DBD) light sources. (6 pages)Optimal switching pattern for space vector modulated Z-source NPC inverter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0244
The Z-source inverter is a relatively recent power converter topology that has been demonstrated in the literature to exhibit voltage-buck and voltage-boost capability. The Z-source concept can be applied to two-level and multilevel inverters. However, multilevel inverters offer many benefits for higher power applications compared to two-level inverters. Previous publications have shown the control of a Z-source neutral point clamped inverter using the carrier-based modulation technique. This paper presents the optimal switching pattern for the control of a Z-source neutral point clamped inverter using the space vector modulation technique. This gives a number of benefits, in terms of implementation and harmonic performance. The adopted approach enables the operation of the Z-source arrangement to be optimised and implemented digitally without introducing any extra commutations. Simulation results are presented to verify the concepts. (6 pages)Algorithm for asymmetric source configuration in a newly constructed multistring multilevel inverter topology
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0231
This paper proposes an algorithm to configure asymmetric sources for a recently proposed topology for multilevel inverters. Since the topology proposed by Vi-Hung Liao et. al is incapable of synthesising all additive and subtractive combinations of input DC levels (as happens in cascaded H-bridge inverter), various popular asymmetric configurations cannot be employed for it. The proposed algorithm is described in detail and it is shown that it helps to synthesise multilevel waveform with equal sized steps. (6 pages)Dynamic analysis of a linearizing modulator for boost converter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0182
In this paper, the review of a dynamic linearizing modulator (DLM) for the boost converter is presented, which transforms the open-loop converter into a linear amplifier with an operating frequency as high as one-fifth the switching frequency. Small signal dynamic analysis of DLM is performed. The effect of inductor size over the system dynamics is discussed. The theoretical predictions of dynamic response are validated using an experimental prototype. (5 pages)Advance high power semiconductors devices in drives and power conversion
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0167
This Paper focuses on Westcode Semiconductors' advanced high power devices; Diodes, Thyristors and Press-Pack IGBTs. Westcode, a division of IXYS Corporation, manufacture devices for use on many power sub-assemblies and have been meeting the strenuous demands of various applications within traction and energy markets. Electrical system performance is calculated using conventional methodology together with a computer thermal model. This modelling program uses an iterative approach to optimise various aspects of the design. The calculation, design, testing and operation of these power sub-systems are also presented and validated by experimental results. (4 pages)Design and control of a novel power electronics interface for fuel cell hybrid electric vehicle applications
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0310
Power Electronics Interfaces (PEIs) play an increasingly important role in the future automotive technology. This paper proposes a novel power electronics interface (PEI) to interface multiple energy sources such as Fuel Cells (FC), Batteries and Supercapacitors to the powertrain of fuel cell hybrid electric vehicles (FCHEV). The proposed PEI is responsible for the power-flow management on-board the vehicle for each operating mode. In this research, a Multi- Device Interleaved Multiple-Input Converter (MDI-MIC) is proposed to reduce the input / output ripples and to reduce the size of passive components with high efficiency. In addition, low electromagnetic interference (EMI) and low stress in the switches are expected. Moreover, a small-signal model of the PEI is derived to design the appropriate controllers. The proposed power electronics interface (PEI) and its controller are designed and analyzed by using Matlab/Simulink. The analytical and simulation results related to this research are presented and discussed. (5 pages)Extended soft switching operation of the triple active bridge convereter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0226
Generalised analytical expressions are derived to calculate the current levels and soft switching boundaries for the triple active bridge DC-DC converter for all operating modes including the option of duty-ratio control as well as phase shift control. (6 pages)Modelling of a resonant converter with a synchronous current doubler rectifier for DC magnet power supplies
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0215
This paper presents the modelling of a resonant converter with a synchronous current doubler rectifier (SCDR) for DC magnet power supplies. The concepts and principles behind the modelling approach are described. A dynamic model of the converter suitable for control design is presented. The modelling is based on a DQ approach and is verified through simulation and through experiment. (5 pages)Control scheme evaluation for class-D amplifiers in a power-ultrasonic system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0237
Power-converters or amplifiers are required to drive high-power piezoelectric transducers and attached processing equipment, at the optimum resonance mode for best processing efficacy, while under varying loading conditions. The driving power converter must synthesize relatively low-distortion sinusoidal output current to prevent harmonic- current excitation of neighbouring, less-productive or desirable resonant modes. Continuously-variable output-voltage capability is required to maintain output power at a level which optimises processing. Three output synthesis methods have been reviewed in this paper for the Class-D amplifier constituting the transducer driver. Typical output-waveform quality is assessed, and PSPICE simulation and laboratory results are presented to illustrate performance. (6 pages)Optimization methodology for efficient LLC resonant converter with power factor correction circuit
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0218
High efficiency is required in power conversion circuits. A systematic optimization procedure is presented in this paper to optimize LLC series resonant converter efficiency where the effect of LLC input voltage variation cased by power factor correction circuit is considered. A mode solver technique is proposed to handle LLC converter steady-state solutions under different input voltage conditions. Loss models are provided to calculate total component losses using the current and voltage information derived from the mode solver. A prototype 300W 12V output LLC converter is built using the optimization results. Experimental results are presented. (6 pages)Star connection of grid connected single phase VSIs to supply unbalanced or nonlinear loads under normal and fault condition considering the transmission line impedances
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0178
This paper presents a proposed circuit topology and control system to supply both linear and nonlinear loads under unbalanced conditions of the grid voltage and fault conditions by using three, single phase, star connected VSIs and a proposed load current controller. The main contribution is the capability of the proposed controller to supply unbalanced and nonlinear loads and reduce the grid voltages and currents ripple using simple PI controller. Moreover, the proposed topology of connection of three singlephase inverters gains the advantage of parallel connection of VSIs. (6 pages)New hybrid pulse-width modulation technique to reduce current distortion and extend current reconstruction range for three-phase inverter using only DC-link sensor
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0246
The paper proposes a new modulation technique which can reduce the current distortion and extend the current reconstruction range for three-phase inverter using only DC-link sensor. The proposed PWM technique is a hybrid method which consists of space vector modulation method and the PWM method without using null switching states. The former provides low current distortion, however it is with narrower current reconstruction range. In contrast, the later extends the current reconstruction range at the cost of higher current distortion. For the proposed method, in the measurable region of space vector modulation method, space vector modulation is used to reduce the current distortion. Moreover, as the modulation range is out of that measurable region, the PWM method without using null switching states is applied to extend the current re-construction range. Furthermore, the current reconstruction limitation using only DC-link sensor is analyzed. The analysis shows that reduction of PWM switching frequency and acquisition time can extend the current re-construction range. Comparison of experimental results derived from an FPGA-based controlled inverter is included. It will be demonstrated that using the proposed hybrid PWM technique the three-phase current signals of inverter can be reconstructed even under very low modulation index range while providing low current harmonic distortion of inverter output. (6 pages)Elimination of reverse recovery effects associated with CoolMos devices employing current source inverter topology
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0151
MOSFET transistors are continuously being an essential part of power electronic converters due to their low switching losses at high switching frequencies. However, the traditional power MOSFET suffers from a relatively low breakdown voltage. In the late 1990's, the CoolMOS transistor was launched by Infineon Technologies based on the super junction technology. This device is capable of blocking a considerably higher source to drain voltage and virtually combines the low on-state resistance of the IGBT with the low switching losses of the MOSFET. The main problem associated with this device is that the reverse characteristics of its internal body diode are found to be snappier than that of the conventional MOSFET. This makes it difficult to use this device in hard switched inverters employing Voltage Source Inverter (VSI) topology. In this paper different factors affecting the reverse recovery behaviour of the internal body diode of CoolMOS power switch are studied. Moreover, a technique to eliminate high reverse recovery peak currents in CoolMOS-based inverters is proposed based on Current Source Inverter (CSI) topology accompanied with silicon carbide Schottky diode. Simulation and experimental tests are carried out to compare between the peak current and the switching losses of CoolMOS employed in both VSI and CSI topologies. The experimental results confirm the improvement achieved using CSI. (6 pages)Predictive PID controller for DC-DC converters using an adaptive prediction error filter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0213
This paper presents a predictive PID controller for DC-DC converters using an adaptive prediction error filter (PEF) in the controller feedback loop. The concept of using an adaptive PEF is clearly described, and mathematical analysis of central concepts, such as the Auto-Regressive (AR) process generator and Moving Average (MA) identifier are explained in detail. The direct relationship between an adaptive PEF and a digital Proportional-Derivative (PD) controller is also presented. This leads to the development of an adaptive Proportional-Derivative + Integral (PD+I) control structure which is an effective substitute to a conventional PID controller. Experimental validation shows that the approach results in a fast adaptive controller with self-loop compensation. (6 pages)IGBT gate voltage profiling as a means of realising an improved trade-off between EMI generation and turn-on switching losses
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0207
A gate drive circuit which applies a programmed voltage profile to the gate of an IGBT is used to demonstrate that an improvement of approximately 20 dB can be made to the trade-off realised between turn-on switching losses and EMI generation, compared to conventional gate drive techniques. The measurement and analysis techniques employed to quantify and improve this trade-off are presented, and the EMI-critical aspects of IGBT switching behaviour are identified using these techniques. (6 pages)Active match load circuit intended for testing piezoelectric transformers
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0169
An adjustable high voltage active load circuit for voltage amplitudes above 100 volts, especially intended for resistive matching the output impedance of a piezoelectric transformer (PT) is proposed in this paper. PTs have been around for over 50 years, were C. A. Rosen is common known for his famous Rosen type design back in the 1950s. After the discovered of new piezoelectric materials and new PT designs have been invented, the PT based power converters are in the area where they can outperform tradition electromagnetic based converters in certain applications. The performance of PTs can be measured and compared on its zero voltage switching (ZVS) factor, power density, and efficiency. Common for these three parameters are that they need to be measured with a match load connected at the output of the PT. (4 pages)High step-up DC-DC converter based on the switched-coupled-inductor boost converter and diode-capacitor multiplier
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0147
The new schemes of a step-up converter with very high voltage gain are proposed in this paper. The schemes are based on a natural combination of the switched-coupled-inductor boost converter and the diode-capacitor multiplier. Their mutual use allows getting very high voltage gain. An important advantage of the proposed circuits is the fact that leakage inductance of the coupled inductors avoids current spikes through the transistor and the diodes. The schemes provide a soft commutation of the transistor and the diodes. The paper analyzes the modes of operation and obtained the basic fundamental relations. Modeling of the proposed structure and the experimental results confirm its efficiency and correctness of the theoretical analysis. (5 pages)A versatile control modulator for optimal bidirectional battery charging
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0200
This paper presents a versatile control modulator (VCM) for optimal bi-directional battery charging. The VCM is capable of adapting to all the existing optimum battery charging techniques, i.e., Constant Current (CC)-Constant Voltage (CV) charging (two- mode charging), Pulse charging, and Reflex charging. The VCM is capable of testing the chargeability of a deeply discharged battery as well. The proposed VCM enables the converter to work as a current source with a controlled output current, when the battery state-of-charge (SOC) is below a predefined reference level and automatically reverts to a voltage source with the controlled output voltage, when the battery SOC exceeds a predefined reference level. Current feed-back clamping, used in the VCM ensures that the error amplifier never gets saturated and the transition between CC to CV mode is smooth and fast. Experimental and simulation results verify the operation of the proposed VCM on a 250 W bi-directional buck/boost converter with coupled inductor. (5 pages)A comparison of the power electronic drive requirements for high bandwidth piezo-electric and electro-magnetic linear actuators
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0238
When designing high-bandwidth embedded linear actuation systems, engineers often face the choice between using a piezo-electric or electro-magnetic actuator. Often, actuator performance characteristics such as energy density, stiffness, frequency response and loss are used to specify the system configuration, whilst the power electronic drive requirement is overlooked. This paper demonstrates the challenges involved in developing an amplifier for a high-voltage piezo-electric actuator. An amplifier designed to drive an electro-magnetic actuator with comparable output capability to the piezo-electric actuator is also presented; this amplifier is significantly smaller and lighter and has higher output signal quality. This suggests that in terms of overall system performance, the power electronic drive requirements of candidate actuators should not be overlooked. (6 pages)Analysis and design of a mixed-mode controlled push-pull boost power factor corrector
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0192
A novel mixed-mode controlled push-pull power factor corrector (PFC) composed of two boost-type PFCs with a coupled inductor is proposed in this paper. Besides possessing the capability of sharing the input current and output current equally, integrating two boost inductors into one magnetic core makes the operating frequency of the core double the switching frequency. The circuit volume and the current ripple can be thus reduced under the same inductance. Therefore, both the power factor (PF) value and the power density are increased. In addition, a cut-in-half duty cycle can reduce the conduction losses of the switches and both the turns and diameters of the inductor windings. Both the continuous conduction mode (CCM) and the transition mode (TM) controls are fulfilled in the proposed PFC during one line frequency cycle. The durations of these two modes depend on both the line voltage and the output load due to the pre-set fixed off-time (FOT). Under CCM operations, the smaller inductor current ripple reduces both the core loss of the coupled inductor and the conduction losses of the switches, which not only promotes the heavy-load efficiencies, but also alleviates the current stresses of the switches and the output diodes. Under TM operations, quasi-resonant (QR) valley-switching on the switches and zero-current-switching (ZCS) of the output diodes can reduce the switching losses. The light-load conversion efficiencies are thus improved. Detailed analysis and design procedures of the proposed topology are given. Simulations and experiments are conducted on a prototype with a universal line voltage, a 380 V output DC voltage, and a 300-W output power to verify its feasibility. (6 pages)Empiric analysis of zero voltage switching in piezoelectric transformer based resonant converters
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0217
Research and development within piezoelectric transformer (PT) based converters are rapidly increasing, as the technology is maturing and starts to prove its capabilities. High power density and high efficiencies are reported and recently several inductor-less converters have emerged [1][2][7][10][13], which demonstrates soft switching capabilities. The elimination of a bulky inductor, reduces size and price of the converter, but demands a soft switching optimised PT. Several attempts of expressing the soft switching capability have been made [5][12], with some shortcomings. The goal of this paper is to derive a simple expression of the maximal obtainable soft switching capability (ZVS factor), for a specific PT design, assuming a matched load. The expression has been derived through series of parametric sweep simulations of the inductor-less half- bridge topology, which revealed that a linearization of the maximal soft switching capability can be performed, in the area of interest. This expression is intended to form a basic tool for development of soft switching optimised PT's, which enables the utilisation of inductor-less topologies. (6 pages)Design and implementation of a high-efficiency 240-W power supply for PC applications
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0193
This paper presents a high-efficiency power supply topology. The front stage is a power factor corrector (PFC) utilizing the single-ended primary inductor converter (SEPIC) topology. The presented SEPIC PFC is operated under continuous conduction mode (CCM) with a transition-mode (TM) PFC controller and coupled inductors. The input current waveform remains continuous to reduce the size of the EMI filter and increase the power density. Due to the inherent voltage step- up/down features of the SEPIC PFC, the input voltage of the post-stage half-bridge series resonant converter (HB-SRC) can be decreased to reduce the voltage stresses on the power switches. High efficiency and low cost can be achieved. Circuit topologies and design considerations for the studied high-performance power supply are analyzed and discussed in detail. High-efficiency requirements for the Energy Star standards can be satisfied. (6 pages)Digital synthetic ripple modulator for point-of-load converters
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0220
Hysteretic modulators exhibit superior dynamic performance and without sacrificing the transient response they help to reduce the number of output capacitors. Due to tight regulation requirements modern point-of-load converters have very small output ripple. This small output ripple fails to generate a suitable piece-wise linear modulation waveform for the hysteretic comparator. This paper presents a fully digital Synthetic Ripple Modulator (SRM) comprising of a hysteretic comparator, a ripple synthesizer, and a voltage error amplifier for tight output voltage regulation. The ripple synthesizer realizes a high-quality low-cost current sensors by creating a piece-wise linear synthetic ripple using sensed converter voltages. This artificial ripple is then added to the output voltage and fed as a carrier to the hysteretic comparator. This improves the large signal dynamics of the converter, especially in low voltage application. Analysis and experimental results on a 2 V/10 A, 20 W single phase prototype are presented to verify the operation of the proposed digital SRM. (6 pages)A power electronic transformer based on indirect matrix converter for PWM AC drive with lossless commutation of leakage energy
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0227
High frequency ac link three phase ac to three phase adjustable speed and magnitude PWM ac converters with single stage power conversion and bidirectional power flow are important in the generation of power from renewable energy sources or where isolation is necessary. Due to the use of high frequency these type of converters achieve high power density. Open loop power factor correction, higher efficiency and reliability are important features of these type of converters. One major problem in this type of converter is the commutation of leakage energy which results in power loss, reduction in switching frequency, distortion and loss of output voltage. The topology based on the indirect modulation of matrix converters uses minimum amount of copper and has relatively less number of semiconductor switches. This paper presents a lossless source based commutation strategy along with a modulation technique that minimizes the frequency of leakage inductance commutation. It also results in the soft switching of the output converter (Zero current switching : ZCS). The topology along with the proposed control has been analysed and simulated. Simulation results confirm the operation. (5 pages)Modelling of losses in load harmonic networks of high efficiency class E power amplifiers
http://dl-live.theiet.org/content/conferences/10.1049/ic.2011.0216
To obtain high efficiency of dc to ac power conversion in an amplifier, it is necessary to decrease the power dissipation in the active device by ensuring that, the overlap of the voltage and current waveforms at the output terminals of the active device is minimized. This reduction of overlap is obtained by using load harmonic networks to shape the above waveforms at the output terminals of the active device. In the three common classes of high efficiency power amplifiers (PAs) (F. F<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">-1</sup> and E), this shaping is obtained by attenuating different harmonics of the waveforms by using load harmonic networks. For the class E amplifier a capacitance is placed across at the output terminals of the active device. This is to ensure that the output voltage is delayed until the active device is turned `off' and the output voltage reaches its minimum value with a slow turn `on'. If this device is driven hard 'on' and 'off' to obtain high efficiency it is shown that the input impedance must be very high at the harmonic frequencies. At the design frequency the required input impedance depends on the value of the above capacitance. Ideal lossless transmission lines (Tlines) are used in the initial design of harmonic networks for high efficiency power amplifiers and then practically realised using microstrip lines (Mlines). As the metal and substrate losses in Mlines are normally expressed in terms of attenuation constants, these losses are difficult determine as they require solutions of complex mathematical equations. In this paper to reduce such complex analysis the losses in an Mlines are modelled as a Tlines in series a resistance. A novel method is proposed to determine this resistance as a function of the length of the Mlines which is realised using inexpensive PCB FR4 substrate. Then for the above two line models, harmonic networks were designed up to the second harmonic and third harmonics and the obtained losses at the design frequency compared. Finally the effect of the losses by different harmonic networks on the class E amplifier is investigated.Sustainable traction drives
http://dl-live.theiet.org/content/conferences/10.1049/ic.2011.0188
This paper presents an overview of railway traction systems. Railway vehicles are characterised by low rolling resistance, and high inertia, therefore the traction drives must have suitable capabilities to deliver the required vehicle performance. Both AC and DC motors are in common use in the railway sector, but have very different power delivery requirements, and there are a multitude of power conversion stages that are necessary to transfer the power from the network to the wheels of the vehicle in a smooth manner. These power converters have evolved from simple camshaft controlled mechanical switches, through to compact power electronic converters. State-of-the-art systems are able to regenerate high quality power back into both DC and AC power systems. For those routes which are un-economic to electrify, the use of on board energy storage offers a means to improve energy efficiency, by providing a store for braking energy which can then be released during acceleration. These types of systems are currently in the development phase, but are expected to enter regular passenger service in the future. Energy storage on the wayside is also being implemented to improve the power performance of existing systems, and to improve the overall energy efficiency by improving the receptivity of the line to regenerated power.Efficacy of symmetrical multipulse modulation in the single-phase matrix converter topology
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0360
The matrix converter topology is a versatile one that is capable of functioning as an ac regulator and as a cycloconverter. The matrix converter topology has been used for ac-ac conversion for various applications that involve variable voltage and variable frequency. Various pulse width modulation techniques have been implemented in the converter topology to reduce the harmonic distortion and obtain better power quality parameters at the output In this paper the symmetrical multipulse modulation technique (SMM) has been implemented in the single-phase matrix converter and the ability of the converter to deliver variable voltage at a specific fundamental (source) frequency and variable voltage at variable fundamental frequency with the technique has been assessed. The SMM is a simple method that involves two key parameters the number of equal width pulses per half cycle (M) of the supply and the duty cycle of the pulses (δ). The performance of the single-phase matrix converter is assessed for control strategies that involve a fixed value ofM and variable δ; and vice-versa.Simplified structure - a mapped space vector pulse width modulation for three level neutral point diode clamped multilevel inverter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0372
In this paper, the space vector modulation technique for an ordinary two level inverter is described. Based on the two level inverter, the paper further deals with space vector PWM technique for a three level inverter. A new algorithm is adopted which ensures reduced computational complexity and the same methodology can be used with higher levels as well. Further a performance comparison of both two and three level inverter is done and this proves superiority of multilevel inverters over an ordinary inverter.A new multilevel space vector modulation (SVM) technique, termed mapped hybrid SVM, is presented. The SVM technique enables the use of three level SVM with multilevel inverters without introducing any carrier level modulation or phase shifts. The proposed technique is theoretically analyzed for five-, seven- and nine-level inverters and then generalized for the m-level inverter, validated by simulation using Matlab/Simulink and confirmed practically for a five-level, shunt, active power filter.Inner-outer preconditioning strategy for 3D inductance extraction coupling with fast multipole method
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0026
This paper presents an efficient preconditioning technique in order to couple Partial Element Equivalent Circuit (PEEC) method with Fast Multipole algorithm (FMM).The driver design and implementation of NAND flash based on memory technology device
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0797
With the rapid development of digital technology, the application of embedded system is more and more extensive. The demand for NAND Flash storage device is growing rapidly, but the different types of embedded equipment provided by different manufacturers do not have consistent standard. So it is very important to develop the driver of NAND Flash of specific manufacturer. In this paper, the Samsung's K9G8G08U0M chip is used as an example. The fundamental structure and operational principle of NAND Flash are introduced. And then the development process of NAND Flash driver based on Memory Technology Device (MTD) is discussed in detail. The driver development process and method are very valuable for NAND flash driver of embedded equipment.Super stack technique to reduce leakage power for sub 0.5-V supply voltage in VLSI circuits
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0428
Leakage current of CMOS circuits has become a major factor in very deep submicron regime. ITRS reports that leakage power dissipation is rapidly becoming a substantial contributor to the total power dissipation as threshold voltage becomes small. In this paper a leakage reduction technique named "Super stack"for sub 0.5-V supply voltage has been proposed. Super Stack technique comes in handy where Multithreshold techniques fail to apply for 0.5-V or lower supply voltages. The proposed method can be used in sub 0.5 V supply voltage for reducing the leakage power in active mode and standby mode while reducing the delay.Closed loop control of hybrid switching scheme for LLC series-resonant half-bridge DC-DC converter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0377
This paper presents LLC series-resonant half-bridge DC DC converter. This circuit is characterized by zero voltage-switching (ZVS) that results in higher efficiency. Possibility to incorporate higher switching frequency and has some potency to reduce switching losses. Power factor improvement and high efficiency is achieved with a constant output voltage and DC output voltage is regulated by using closed loop control and the simulation results for the converter is presented.Design of the high frequency electromagnetic behavior of planar inductor for resonant circuits in switching power converters
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0030
In this paper a planar inductor based resonant circuit is designed for zero-current switching (ZCS) buck converter. The electromagnetic behavior of the design is analyzed by finite element (FE) methods for EMI interactions. A high frequency model for conducted EMI in the resonant circuit is obtained. To suppress the conducted EMI in the circuit, a method based on the resonant circuit impedance control is proposed. All the results are compared to conventional circuits and improvement in responses were observed and verified through simulation and laboratory experimentation.