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Power Electronics, IEEE Transactions on

Issue 5 • Date Sep 2000

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Displaying Results 1 - 16 of 16
  • Robust speed control of an induction motor: an H control theory approach with field orientation and μ-analysis

    Page(s): 908 - 915
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    In this paper we present a robust speed control strategy for an induction motor under field orientation. The control framework employed properly represents the induction motor state-space model and its inherent variations, which are treated as structured uncertainties. Applying an H, optimization methodology on this framework we derive a stabilizing controller to meet design objectives and then robust stability and performance against such variations are checked by using μ-analysis. No on-line tuning is required for the parameters of the derived controller, which is the dynamic system responsible to keep the rotor flux orientation as well as the speed regulation at design levels, irrespective of the motor operating points. A general methodology arose from the usage of the proposed strategy and simulated experiments showed satisfactory results for the robust speed control of an induction motor. View full abstract»

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  • An analysis and experimental approach to MOS controlled diodes behavior

    Page(s): 916 - 922
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    The metal oxide semiconductor (MOS)-controlled diode (MCD) is a new class of power semiconductor diode that can achieve ideal diode performance. In this paper, experimental verification of the MCD key concept is presented for the first time by using commercially available power metal oxide semiconductor field effect transistors (MOSFETs) operating as MCDs. Measurements of the reverse recovery currents and reverse recovery charges of these “MCDs” are obtained and compared with the body diodes of the MOSFETs. These measurements suggest that MCDs can reduce the reverse recovery current, storage charge, and switching loss significantly. Optimized MCD performances at 1.2 kV, 2.4 kV, and 4.5 kV are also predicted based on numerical simulations. Ideal performance of the MCD close to that predicted by the device simulation should be obtained once an optimized MCD is developed View full abstract»

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  • Transformerless capacitive coupling of gate signals for series operation of power MOS devices

    Page(s): 923 - 930
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    A reliable configuration for triggering a series string of power metal oxide semiconductor (MOS) devices without the use of transformer coupling is presented. A capacitor is inserted between the gate and ground of each metal oxide semiconductor field effect transistor (MOSFET), except for the bottom MOSFET in the stack. Using a single input voltage signal to trigger the bottom MOSFET, a voltage division across the network of device capacitance and inserted capacitances triggers the entire series stack reliably. Design formulas are presented and simple circuit protection is discussed. Simulation shows reliable operation and experimental verification is presented, Application of the method is applied to series insulated gate bipolar transistors (IGBTs) View full abstract»

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  • A flying-capacitor ZVS PWM 1.5 kW DC-to-DC converter with half of the input voltage across the switches

    Page(s): 855 - 860
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    This paper introduces an isolated flying-capacitor DC-to-DC converter which features half of the input voltage across the switches, zero-voltage-switching, operation at constant frequency, regulation by pulse-width-modulation, and low RMS current stress upon power switches. The complete operating principle, theoretical analysis, relevant equations and design example are provided in this paper. The experimental results of a 1.5 kW converter with 60 V, 25 A output. 600 V input, operating at 50 kHz switching frequency are also presented and discussed in the paper. The proposed converter is an alternative to the full-bridge ZVS-PWM DC-to-DC converter in high-input voltage applications View full abstract»

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  • Average current mode control of series-switching post-regulators used in power factor correctors

    Page(s): 813 - 819
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    The application of the average current mode control (ACMC) to a new type of very efficient post-regulator is studied in this paper. This post-regulator, called series-switching post-regulator (SSR), has been proposed to improve the dynamic response series-switching of power factor correctors (PFC), The post-regulator exhibits very high efficiency due to the fact that only a part of the total power undergoes a power conversion process. Using ACMC, the bandwidth of the post-regulator increases in relation to the one obtained when a conventional voltage-mode control (with or without feedforward) is used. As a result, the attenuation of the input voltage ripple (100-120 Hz) increases and, a lower bulk capacitor can be used to obtain a low voltage ripple at the output, which is extremely important when a battery is connected at the output. This is rather common in distributed power supply systems View full abstract»

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  • A bidirectional AC-DC power converter with power factor correction

    Page(s): 942 - 948
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    This paper presents new operation and performance of a thyristor-based AC-DC current-controlled boost-type converter that allows bidirectional power handling capability and provides input power factor correction and a near-sinusoidal input current waveform. The new converter can reduce harmonic pollution and disturbance on the supply mains. The feature of bidirectional power flow allows the stored energy in loads, such as motors, to regenerate back to the supply source, leading to an increase in overall energy efficiency and possibly a reduction in the size of the DC link capacitor. The operation is confirmed with the successful implementation of an experimental prototype View full abstract»

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  • Improved light-load efficiency for synchronous rectifier voltage regulator module

    Page(s): 826 - 834
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    DC/DC converter with high efficiency over a wide load range is necessary for many low voltage applications, such as battery supplied systems and micro-processor power supplies-voltage regulator module (VRM). In order to improve the efficiency of low voltage converters, synchronous rectifier technology is widely used. The disadvantage of this technology is low efficiency at light load. This paper proposes a new technology, which utilizes the duty cycle signal, to improve light load efficiency with simple implementation. Since current sensors are not required, high density and high efficiency can be achieved that makes the whole circuit suitable for integration. In the paper, two application examples are given. Experimental results verified that the proposed control schemes significantly improve the efficiency of synchronous rectifier buck converters at light load View full abstract»

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  • A novel control method for three-phase PWM rectifiers using a single current sensor

    Page(s): 861 - 870
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    This paper proposes a control method for three-phase voltage-source PWM rectifiers using only a single current sensor in the DC-link. A PWM modulation strategy for reconstructing three phase currents from the DC-link current is given. When 3φ input currents cannot be reconstructed, a method for modifying the switching state of the PWM rectifier and a method for the predictive state observer is proposed. Compensation of the 2 sampling delays is also included, and this method is combined with all of the experiments. Performance differences between the two methods in a typical voltage source PWM rectifier are investigated experimentally View full abstract»

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  • Implementation of a three-level rectifier for power factor correction

    Page(s): 891 - 900
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    In this paper, a new single-phase switching mode rectifier (SMR) for three-level pulse width modulation (PWM) is proposed to achieve high input power factor, low current harmonics, low total harmonic distortion (THD) and simple control scheme. The mains circuit of the proposed SMR consists of six power switches, one boost inductor, and two DC capacitors. The control algorithm is based on a look-up table. There are five control signals in the input of the look-up table. These control signals are used to control the power flow of the adopted rectifier, compensate the capacitor voltages for the balance problem, draw a sinusoidal line current with nearly unity power factor, and generate a three-level PWM pattern on the AC side of adopted rectifier. The advantages of using three-level PWM scheme compared with two-level PWM scheme are using low voltage stress of power switches, decreasing input current harmonics, and reducing the conduction losses. The performances of the proposed multilevel SMR are measured and shown in this paper. The high power factor and low harmonic currents at the input of the rectifier are verified by software simulations and experimental results from a laboratory prototype View full abstract»

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  • Analysis, design, and implementation of a random frequency PWM inverter

    Page(s): 843 - 854
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    Random pulse width modulation (RPWM) approaches can make the harmonic spectrum of inverter output voltage be continuously distributed without affecting the fundamental frequency component, and thus the acoustic noise and mechanical vibration of an inverter-fed AC motor drive are greatly reduced. However, the analysis and design of the RPWM mechanisms are generally not so trivial for practical engineers that their applications are limited. In this paper, a random frequency PWM (RFPWM) inverter and its practical design procedure are presented. First, the effects of the attributes of a random signal on the inverter output harmonic spectrum distribution characteristics are analyzed using an intuitive concept, then based on which, the quantitative design. Simulink simulation and implementation of the proposed RFPWM inverter are introduced. The proposed RFPWM inverter is employed to power an indirect field-oriented induction motor drive. The simulated and measured results indicate that the uniform random distribution of inverter output harmonic spectrum and thus smaller acoustic noise and mechanical vibration are obtained by the proposed RFPWM scheme View full abstract»

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  • Design and implementation of an adaptive controller for torque ripple minimization in PM synchronous motors

    Page(s): 871 - 880
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    This paper addresses the problem of torque ripple minimization in permanent magnet synchronous motors (PMSMs) and proposes an adaptive feedback structure as a solution. A model of PMSM that includes a torque ripple phenomenon is first developed and tested. While slightly different from the conventional one, our model is still compact and suitable for control. All parameters of the model have physical interpretation, and can either be measured directly or estimated in a numerically reliable procedure. An adaptive control algorithm is then described, enabling speed tracking while minimizing the torque ripple. Finally, the proposed algorithm is verified in simulations and implemented in a hardware setup. Experimental results show significant reduction of torque ripple (by 27 dB). Extensive analysis and simulations of hardware imposed limitations were performed as well, revealing and quantifying the issues that might affect practical ripple minimization performance View full abstract»

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  • Time delay compensation of digital control for DC switchmode power supplies using prediction techniques

    Page(s): 835 - 842
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    One of the major disadvantages of digital control is the limited control loop bandwidth due to the inherent time delay introduced by the zero-order-hold effect and the computational time delay. To alleviate this problem, two practical and straightforward predictive schemes based on linear extrapolation are proposed. With the proposed schemes, the computational time delay of the control loop is compensated and the control loop bandwidth is increased. It is shown that, using the proposed techniques, the control loop bandwidth can be increased up to two times that of the conventional digital control loop. Also, the computational overhead needed to implement these techniques is kept to the minimum. A lab prototype system of a 1 kV full bridge DC power supply was set up for the proof of concept. The prototype system operated at 10 kHz and was controlled by a TI TMS320F240 DSP (20-MHz 16-bit fixed-point). Simulation and experimental results prove the validity of the proposed techniques View full abstract»

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  • Application of parallel connected NPC-PWM inverters with multilevel modulation for AC motor drive

    Page(s): 901 - 907
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    The neutral point clamped (NPC)-PWM inverters have been put into practical use for large capacity AC motor drives, because of their many advantages. With the increase in use, still larger capacity inverters are also expected. In this paper, a parallel connected NPC-PWM inverter is applied for AC motor drive. The conventional modulation techniques are extended to improve the inverter characteristics. To determine an optimum modulation for controlling the parallel connected NPC-PWM inverter, various modulation techniques are devised and discussed, whose results are verified by experiment View full abstract»

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  • Automatic flux-weakening control of permanent magnet synchronous motors using a reduced-order controller

    Page(s): 881 - 890
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    This study presents a novel means of designing a simple and effective position and velocity controller for permanent magnet synchronous motors (PMSM). In contrast to the conventional two-loop control methods with full-state feedback, the proposed controller does not need current information of the motor for feedback purposes. However, under normal operation the steady-state d-axis current can still be controlled to zero to minimize power dissipation. In addition, implementing a simple overmodulation strategy allows the controller to automatically generate a flux-weakening control to expand the range of operating speed when voltage saturation occurs. In addition to not depending on system parameters used by the controller, the automatically generated demagnetizing current is also optimal in the sense of minimum power dissipation that differs from the maximum output torque design or the constant power design of the general flux-weakening control methods. Simulation and experimental results show that the controller can achieve an effective speed and position control with near-minimum power dissipation, even when voltage saturation occurs View full abstract»

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  • Coreless planar printed-circuit-board (PCB) transformers-a fundamental concept for signal and energy transfer

    Page(s): 931 - 941
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    Magnetic cores have been used in transformers for over a century. In this paper, the authors present a fundamental concept of using “coreless” printed-circuit-board (PCB) transformers. With the aid of a high-frequency equivalent circuit, the use and basic characteristics of coreless PCB transformers are described. Optimal operating conditions for minimum input power requirement and maximum efficiency operations are identified. Coreless PCB transformers have the advantages of low costs, very high power density, no limitation due to magnetic cores, no magnetic loss and ease of manufacturing. They have the potential to be developed in microcircuits. A printed planar PCB transformer with a diameter of about 1.0 cm and power capability of 19 W has been successfully tested. The power density of the PCB transformer demonstrated in this paper is 24 W/cm2. The maximum efficiency can be greater than 90%. The analysis has been confirmed with experiments. Coreless printed transformers have great potential in applications in which stringent height and space requirements have to be met View full abstract»

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  • Measurement of noise source impedance of off-line converters

    Page(s): 820 - 825
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    The insertion loss method is proposed to measure the noise source impedance of off-line power supplies. The information obtained through the proposed method enables the prediction of EMI filter performance and the design of a suitable filter for a switch mode power supply View full abstract»

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Aims & Scope

IEEE Transactions on Power Electronics covers fundamental technologies used in the control and conversion of electric power.

Full Aims & Scope