PESC Record - IEEE Annual Power Electronics Specialists Conference

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  • ISSN
    0275-9306

Publications in this journal

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    ABSTRACT: While supercapacitors offer high power density, high cycling capability and mechanical robustness, voltage and current ripple from downstream PWM converters can result in their overcharging or heating resulting in their lifetime reduction. This paper discusses how a simple novel design scheme of using a very low value series inductance significantly increases capacitor lifetime.
    Power Electronics and Applications, 2009. EPE '09. 13th European Conference on; 10/2009
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    ABSTRACT: Industrial drives, like many other power electronics applications are experiencing an ever increasing demand for high power densities. Only through a system integration approach which involves an integrated thermal and spatial design and using integration technologies can this goal be achieved. Hybrid integration in the form of integrated power electronics modules (IPEMs) is one of the key elements of this approach. Advanced thermal management with optimised air flow and a special heat sink structure is the other key element. In this paper a thermal management concept for high power density drives is investigated and a novel method, i.e. the integrated I-Housing, is utilized to implement the heat removal system. The complex thermal management structure consisting of an impingement cooled pin fin heatsink and heat exhaust paths, which significantly reduce the amount of air required for cooling, are modelled. The model presented in this paper is experimentally verified with a thermal dummy. The model is ultimately to be used to design the thermal management for a fully functional 2.2 kW inverter with a total volume of 500 cm<sup>3</sup> - four times smaller than the current state of the art.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: In order to pave the way to a sustainable energy future based on a large share of distributed generation (DG), there is a clear need to prepare the European electricity system for the large-scale integration of both renewable and other distributed energy sources. Advanced power electronic converters for DG will be needed in order to control the power flow and to ensure proper and secure operation of this future grid with an increased level of the renewable power. These power converters must be able to provide intelligent power management as well as ancillary services. This paper presents an analysis of the natural reference frame controller, based on proportional-resonant (PR) technique, for a multi-level H-bridge power converter for universal and flexible power management in future electricity network. The proposed method is tested in terms of harmonic content in the point of common coupling (PCC), voltage amplitude and frequency excursions as well as system response for bidirectional power flow. The presented results confirm the effectiveness of the proposed control strategy.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: A novel semiconductor circuit breaker based on SiC (silicon carbide) is introduced in this paper. It integrates an electronic power circuit breaker consisting of two anti-serial cascodes, a control unit with current, voltage and temperature measurement as well as a power supply, making the switch fully self-sufficient. Each cascode is composed of a high-voltage SiC-JFET (junction field effect transistor) or a SiC-SIT (static induction transistor) and a low-voltage Si (silicon) - MOSFET (metal oxide semiconductor field effect transistor), resulting in a normally-off configuration. This new circuit breaker has further advantages over well-known alternatives such as noiseless switches without electric arcs. Highest selectivity minimizes short-circuit currents and thus the stresses on electrical equipment. The integrated current and voltage measurement function allows the effective and apparent power to be determined. The switch can therefore actively influence inrush currents, resulting in better net exploitation. The benefits of using silicon carbide power semiconductors include a significant reduction of forward losses, which are the biggest drawback of electronic switches compared to mechanical ones, and the high ruggedness achieved by their intrinsic short-circuit capability for a period of time sufficient for the control unit to switch the devices off electronically. Its current and temperature measurement capability additionally assures overload protection by tracking the junction temperature within a digital model calculated by the control unit. Measurements at different operating points and in fault cases have been performed on prototypes of this novel semiconductor circuit breaker. The results show conclusively that this approach represents the next step forward to a perfect electronic circuit breaker.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: The cross section of foil windings used in ungapped, low-permeability cores can be modified to reduce total winding loss. The optimal cross-section shape is determined to have a linear cut out and a loss model is developed to calculate the winding loss in foil windings with this cross-section. The loss model shows excellent accuracy when compared to the loss determined by finite-element analysis. The loss model has been used to implement an optimization that determines the lowest loss cross-section for a particular application.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: This paper investigates the loss characteristics of several commercial rf magnetic materials forpower conversion applications in the 10 MHz to 100 MHz range. A measurement method is proposed that provides a direct measurement of inductor quality factor Q<sub>L</sub> as a function of inductor current at rf frequencies, and enables indirect calculation of core loss as a function of flux density. Possible sources of error in measurement and calculation are evaluated and addressed. The proposed method is used to identify loss characteristics of different commercial rf magnetic core materials. The loss characteristics of these materials, which have not previously been available, are illustrated and compared in tables and figures. The results of this paper are thus useful for design of magnetic components for very high frequency applications.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: An improved model for the calculation of high frequency resistance of windings that show an arbitrary conductor distribution within the available window space is presented. The new formula, which is extracted after an extensive process of Finite Element Analysis simulations, followed by statistical treatment of the results, is verified by experimental measurements on windings wound over cores with circular as well as rectangular center pole. In this way an easily applicable tool is offered to help the optimization of magnetic components when non-layered coils are used.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: Conventional cascade buck-boost PFC (CBB-PFC) converter suffers from the high conduction loss in the input rectifier bridge. To resolve the above problem, a novel bridgeless buck-boost PFC topology is proposed in this paper. The proposed PFC converter which removes the input rectifier bridge has three conduction semiconductors at every moment. Comparing with CBB-PFC topology, the proposed topology reduces the conduction semiconductors, reduces conduction losses effectively, improves the efficiency of converter and is suitable for use in the wide input voltage range. In this paper, the average current mode control was implemented with UC3854, the theoretical analysis and design of detection circuits was presented. The experimental prototype with 400 V/600 W output and line input voltage range from 220 VAC to 380 VAC was built. Experimental results show that the proposed converter can improve 0.8% efficiency comparing CBB-PFC converter.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: A hybrid pulsewidth modulation (PWM) scheme that hybridizes the advantages of unipolar switching scheme (USS) and bipolar switching scheme (BSS) for grid-connected current source inverter (CSI) is presented. The former switching scheme has the advantage of low switching losses while the latter one has the advantage of generating output with low total harmonic distortion (THD). The inverter bridge is dominantly operated under USS over a line cycle, within which only one switch is switched at high frequency. It is momentarily operated under BSS around the zero-crossing points of the line voltage, within which two switches are switched at high frequency. To further reduce switching losses, two passive resonant snubbers are used for the high-frequency switches. The modes of operations, criteria of ensuring soft-switching and design procedures will be discussed. The proposed switching scheme and snubber structures have been successfully applied to a 900 W, 220 V, 50 Hz prototype. The controller has been implemented with DSP TMS320F2808. The steady-state characteristics of the CSI operating from half load to full load conditions will be given.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: The objective of this paper is to investigate and improve the high frequency noise reduction performance of common mode (CM) noise reduction techniques. Balance technique is chosen as the research object. High frequency model of balanced boost PFC converter is derived and important parasitics and parameters in the model are studied. Effects of coupling coefficient, turns ratio and inductor impedance on high frequency CM noise are discussed in detail. According to the model, high frequency resonance due to serial LC network causes high CM noise peak. Turns ratio has significant impact on the noise peak level. Core and winding structure of boost inductors is another important aspect for high frequency CM noise. Design guidelines for implementing balance are summarized to achieve best high frequency CM noise reduction. Boost PFC prototype with CM EMI filter was built to verify the proposed CM noise model and noise reduction methods. Finally, the effect of grounding point on CM EMI filter performance is also studied.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: Suitable model for the analysis and control of the shunt active power filter (APF) was quite difficult to obtain, which prohibited not only the industrial applications, as no generalized method to design the control loop, also the analysis and comparison between existing control methods. In this paper, a simplified shunt APF model, including the steady state model and small signal model, based on the instantaneous energy equilibrium is proposed. Subsequently, the newly built model is used to analyze two popular control methods in detail, as the shunt APF control with or without the reactive and harmonic current detection, in the DC voltage control loop responses to different load current disturbances. The obtained results are compared with the time domain simulation results for the control method with the reactive and harmonic current detection, the differences for them are found as the time delay caused by the low path filter (LPF) in the detection, the control and the whole system model is improved by considering this effect, and the comparisons on the responses to different current disturbances are evaluated for these two control methods accordingly. Finally, an example of the shunt APF control loop design is done based on the new model in the control method without reactive and harmonic current detection, the computer simulation and the prototype experiment are done to verify the validity of this newly designed compensator accordingly.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: Digitally group-asymmetrical PWM (DGAPWM) ballast for a dimmable fluorescent lamp is explored. The proposed DGAPWM can adaptively provide suitable duty-ratio in group pulse train for generating proper odd as well as even harmonics over whole spectrum of the lamp current so as to eliminate striation and thermostat effect. The DGAPWM activates during low luminance under 3,000 Cd/m<sup>2</sup> and operates the ballast working in continuous conduction mode (CCM), which achieves zero-voltage-switching (ZVS) to gain high efficiency over 90%. The proposed DGAPWM for the fluorescent lamp can increase lighting efficiency better over 20% than traditional one and provide wide dimmable range between 100% and 0%.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: 3-phase AC-drives for HVAC applications (heating, ventilation & air-conditioning) typically employ a passive diode rectifier and an electrolytic DC-link capacitor to filter the rectified line voltage. The DC capacitor may be accompanied by AC or DC-chokes for harmonic line- current reduction. Recently, commercial HVAC drives, where all traditional passive rectifier components are replaced with a "small" DC-link film capacitor, have emerged. These are referred to as slim DC-link AC-drives. This AC-drive is compared to traditional types below.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: This paper presents a hybrid digital adaptive (HDA) controller for synchronous buck DC-DC converters. The proposed controller is a combination of a standard constant-frequency PWM control in the vicinity of steady state and a bank of linear switching surface controllers (SSC) with slopes adaptively selected by a supervisor away from the reference. The supervisor selects the appropriate switching surface slope based on the capacitor current estimate and the quantized output error. A stability analysis using Lyapunov functions is presented. Experimental results for a 1.3 V, 10 A synchronous buck converter demonstrate near time optimal responses for a wide range of step load transients.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: High power current source converters (CSC) are usually implemented with GTOs which present a maximum switching frequency of a few kHz. Space vector modulation (SVM) offers a very elegant way of generating CSC gating signals on-line with increased gain and reduced switching frequency. However, for very low frequency, as required by GTOs, SVM results in non-characteristics low order (5<sup>th</sup> and 7<sup>th</sup> ) harmonics. The reduction of the magnitude of these harmonics has been sought mostly through new sequences of space vectors (states), which present better performance for different ranges of modulation index and power factor. Moderate improvement can be obtained by calculating the states on times at once in the middle of a cycle. This paper shows that larger reductions can be achieved by calculating the states on times at different moments, as the states are used. The effectiveness of the proposed technique for different states sequences is demonstrated by means of simulations.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: In this paper, the closed-loop control of a 4-leg voltage source converter-based dynamic voltage restorer has been described. A low-voltage, laboratory model of the dynamic voltage restorer has been constructed. The controller functions have been implemented in a DSP-based digital controller. A program for resolving the 3-phase variables into the sequence components has also been included among the controller functions. The DVR is able to protect the load from voltage sags due to various types of faults.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: The output current of contemporary AC-DC front-end converters is steadily increasing due to higher power density requirements. The use of shunt resistors to sense the output current is becoming unacceptable due to high power losses and new techniques for current sensing need to be investigated. In this paper, we investigate the possible use of the voltage drop across the trace resistance to sense the output current. This approach promises very low cost since no dedicated shunt resistor is required, no additional power losses occur and no extra space on the printed-circuit-board (PCB) is necessary. To overcome the problems associated with the temperature drift of the copper, and variability in the trace resistance of the copper track, a digital controller can be used to calibrate the trace resistance and implement a temperature drift compensation. This form of microcontroller is readily available on todaypsilas AC-DC front-end converters. However, theoretical and practical investigations revealed that the parasitic inductance and skin effect may limit the bandwidth of this measurement principle down to several hundred Hz. To overcome this limitation, we proposed a compensation technique that has the potential to increase the bandwidth beyond ten kilohertz. Experiments with output currents of up to 240 A demonstrated that the measurement uncertainty for DC currents is less than plusmn1 A for temperatures between 25 to 60 degrees, and that the effective bandwidth can be enhanced using a compensation technique.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: A ratio buck-boost (RBB) converter with feed-forward (FF) technique is proposed for regulating output voltage with fast line response. Owing to the ratio control technique, RBB converter can achieve high conversion efficiency due to only two turn-on switches within a switching period for all operation modes, which contains buck, boost, and buck-boost modes. Besides, feed-forward technique minimizes the voltage variations at the output of error amplifier. Thus, a fast line transient response can be achieved with small dropout voltage at the output. The proposed RBB converter with FF-technique is designed by TSMC 0.35 um 2P4M process. Simulation results demonstrate the correction and performance of RBB converter with FF-technique. The transient dropout voltage can be decreased from 80 mV to 3 mV.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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    ABSTRACT: For mechanical sensor-less control of inverter fed induction machines, a satisfactory performance at low speed down to zero fundamental frequency can so far only be achieved by using signal injection methods and exploiting non-fundamental wave effects. The voltage pulse excitation technique is applied in this paper. The main problem in signal injection based sensorless control a round zero fundamental frequency is the separation of the different signal components related to the saliencies. The focus of this paper is using fast Fourier transform (FFT) to determine the amplitude and angle of the signal components induced by saturation and trained artificial neural network (ANN) for on-line compensation of these components at all loads. In addition a reduction of the remaining amplitude modulation (AM) is proposed. The output after the disturbance elimination is thus the extracted slotting signal that is used as control signal for calculating the rotor position using phase locked loop (PLL). This position is then used for calculating the rotor flux position in combination with the current model (rotor-equation) for field oriented control (FOC). The performance of the proposed structure is verified on a standard induction machine with un-skewed rotor.
    Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008