Showing papers in "IEEE Transactions on Power Electronics in 1994"
TL;DR: In this article, the authors present trends in active power line conditioners using PWM inverters, paying attention to practical applications, and present the largest one is 20 MVA, which was developed for flicker compensation for an arc furnace with the help of a shunt passive filter of 20 mVA.
Abstract: Active power line conditioners, which are classified into shunt and series ones, have been studied with the focus on their practical installation in industrial power systems. In 1986, a combined system of a shunt active conditioner of rating 900 kVA and a shunt passive filter of rating 6600 kVA was practically installed to suppress the harmonics produced by a large capacity cycloconverter for steel mill drives. More than one hundred shunt active conditioners have been operating properly in Japan. The largest one is 20 MVA, which was developed for flicker compensation for an arc furnace with the help of a shunt passive filter of 20 MVA. In this paper, the term of "active power line conditioners" is used instead of that of "active power filters" because active power line conditioners would cover a wider sense than active power filters. The primary intent of this paper is to present trends in active power line conditioners using PWM inverters, paying attention to practical applications. >
621 citations
TL;DR: In this paper, the authors propose an orthogonality between skin effect and proximity effect to calculate the AC resistance of round conductor windings, which gives more accurate answers than the basic one-dimensional method because the exact analytical equations for round conductors can be used.
Abstract: The one well-known one-dimensional method for calculating the AC resistance of multilayer transformer windings contains a built-in orthogonality which has not been reported previously. Orthogonality between skin effect and proximity effect makes a more generalized approach for the analytical solution of AC resistance in windings possible. This includes a method to calculate the AC resistance of round conductor windings which is not only convenient to use, but gives more accurate answers than the basic one-dimensional method because the exact analytical equations for round conductors can be used. >
546 citations
TL;DR: In this article, a novel vector PWM method for three-phase voltage-controlled inverters is described, which is characterized by the minimum amount of switching losses incurred in the inverter switches.
Abstract: A novel vector PWM method for three-phase voltage-controlled inverters is described. The so-called minimum-loss vector PWM (MLVPWM) strategy is characterized by the minimum amount of switching losses incurred in the inverter switches. Comparative analysis proving superiority of the MLVPWM technique over the existing regular-sampling PWM methods, and results of experimental investigation of a prototype modulator are presented. >
240 citations
TL;DR: In this paper, the losses in a Class-D RF switching power amplifier and their frequency dependence are described and a new low inductance half-bridge package is introduced to solve this problem.
Abstract: In this paper, the losses in a Class-D RF switching power amplifier and their frequency dependence are described. The losses analyzed are the switching, conduction, and gate drive losses. A 300 W, 13.56 MHz, Class-D circuit is designed in the traditional manner to illustrate the magnitude of the different types of loss. A circuit using the ZVS equations developed in this paper is designed. An experimental circuit is built using standard IRF540 devices in TO220 packages. That circuit does not meet its performance goals because of the package inductance. A new low inductance half-bridge package is introduced to solve this problem. Techniques for circuit layout and power measurements for RF applications are also presented in the experimental section. A low loss gate drive circuit is also presented using a Class-E circuit to provide the drive power. The experimental results confirm the accuracy of the design equations derived in this paper. >
235 citations
TL;DR: In this article, generalized half-bridge and full-bridge resonant converter topologies with two, three and four energy storage elements are presented and compared with typical second-and third-order series resonant converters, whereas the fourth-order topology is based on the approximate analysis.
Abstract: Generalized half-bridge and full-bridge resonant converter topologies with two, three and four energy storage elements are presented. All possible circuit topologies for such converters under voltage/current driven and voltage/current sinks are discussed. Many of these topologies have not been investigated in open literature. Based on their circuit element connections and source and load excitation types, these topologies are classified into resonant and nonresonant topologies and on their physical realizability. Comparison based on exact steady state analysis are given for typical second- and third-order series resonant converters whereas the fourth-order topology is based on the approximate analysis. >
229 citations
TL;DR: A method for fast time-domain simulation of piecewise-linear networks with switches based on a discrete-time switch model that consists of a constant conductance in parallel with a current source is described.
Abstract: A method for fast time-domain simulation of piecewise-linear networks with switches is described in this paper. The method is based on a discrete-time switch model that consists of a constant conductance in parallel with a current source. In each simulation step, the value of the current source is updated as a function of known network signals. The function takes one of two forms, depending on the state (on or off) of the switch. Since the system matrix is constant, regardless of the states of the switches, simulation time is essentially the same as for a linear, time-invariant network of the same complexity. The paper discusses selection of the model and simulation parameters. The simulation algorithm is described and an example is included. It is shown that the method is not only efficient but also quite general and void of convergence problems. Its primary application is for long-term transient simulation of power electronic systems such as switching power converters. >
160 citations
TL;DR: In this paper, an improved invertor hysteresis current controller is proposed to coordinate the switching of the three-phase switches in the d-q phase plane, where information of the current error derivative is further employed so that one can take more advantage of adding the zero voltage vector for reducing the switching frequency.
Abstract: In this paper, an improved invertor hysteresis current controller is proposed. It coordinates the switching of the three-phase switches in the d-q phase plane. In addition to the current error, information of the current error derivative is further employed so that one can take more advantage of adding the zero voltage vector for reducing the switching frequency. A simple hardware implementation of the improved hysteresis current controller is also proposed such that merits of the conventional hysteresis current controller can still be kept. Theoretical basis and some simulation and experimental results are presented to demonstrate the validity of the improved hysteresis current controller. >
159 citations
TL;DR: In this paper, the authors compared two compensation strategies for control of shunt active filters and showed that the strategy based on unity-power factor control is appropriate when the supply voltage waveform of the plant where the active filter is connected shows significant distortion.
Abstract: Compensation strategies for control of shunt active filters are compared in the paper. It is shown that the strategy based on unity-power factor control is appropriate when the supply voltage waveform of the plant where the active filter is connected shows significant distortion. As voltage distortion increases, this strategy provides compensated line current having lower harmonic distortion and RMS value with respect to the strategy generally used. This contributes to diminish the current and voltage distortion in networks. The unity-power factor compensation strategy conditions the current flowing in the plant where compensation is realized to fit the voltage waveform, thus reaching a unity power factor. Hence, the line current RMS value is minimum. The comparison of the strategies is performed by both Monte Carlo and ATP simulation. >
153 citations
TL;DR: In this paper, an active power filter for nonlinear AC loads with the power part carried out in the bridge connection is described, and a theoretical approach to the implementation of the current reference is given for this original solution of the serial active filter.
Abstract: This paper describes an active power filter for nonlinear AC loads with the power part carried out in the bridge connection A theoretical approach to the implementation of the current reference is given for this original solution of the serial active filter The paper also provides experimental results of the filter application on two specific nonlinear loads, ie, on the ohmic load, fed over a pair of antiparallel thyristors, and on the accumulator feeder >
148 citations
TL;DR: In this article, the authors presented a formula to calculate mutual impedance between transformer windings on ferromagnetic cores, which is based on the solution of Maxwell's equations for coils.
Abstract: A formula is presented to calculate mutual impedance between transformer windings on ferromagnetic cores. The formula is based on the solution of Maxwell's equations for coils on ferromagnetic cores and as such offers the ultimate in accuracy. The formula is frequency dependent, taking into account the effect of eddy currents in the core on the flux distribution as well as representing the eddy current core loss as an equivalent resistance. Experimental results are presented for leakage inductance and an illustrative example is presented showing how leakage inductance affects the operation of a typical switching mode power supply. Approximations for the formula are also presented to simplify the calculations under certain operating conditions. >
137 citations
TL;DR: In this article, a position-detecting algorithm based on electrical measurements is presented, well-suited to low velocity (INFORM model) and high velocity (EMF model), respectively.
Abstract: Reluctance machines with three-phase stator windings and damperless rotors are usually operated in a closed-loop rotor-oriented control. The necessary position encoder reduces robustness considerably. In order to replace this sensor by a position-detecting algorithm based on electrical measurements, two methods are presented, well-suited to low velocity (INFORM model) and high velocity (EMF model), respectively. Based on this information, a Kalman filter yields estimates of the machine state. A rotor-oriented controller enables highly dynamic operation even at standstill. Measurements verify the good static and dynamic properties of the drive in speed-controlled mode. >
TL;DR: In this paper, a new approach for digital feedback control of a PWM inverter is proposed, in which an output DB (deadbeat) control is achieved combined with a disturbance observer.
Abstract: A new approach for digital feedback control of a PWM inverter is proposed, in which an output DB (deadbeat) control is achieved combined with a disturbance observer. In the proposed scheme, the pole placements of the state observer and the disturbance observer are chosen separately. When the two observers employed the same pole placements, the experimental setup had a tendency to become unstable due to the detection error. By selection of the different pole placements, the disturbance observer quickly estimates the disturbance and feedforward disturbance cancellation is achieved. Then the state observer estimates the state variables at the next sampling instant, and the deadbeat controller is applied to the nominal system. This scheme has advantages in robustness in the practical application. From the view point of UPS applications, the advantages and disadvantages are discussed through simulations and experiments. Compared with other digital control laws, the superiority of the proposed control law is verified. >
TL;DR: In this article, an analytical method for calculating the harmonic currents for both the continuous and discontinuous current conductions was proposed, taking into account the effects of the DC and AC side impedances.
Abstract: Commonly, three-phase diode bridge rectifiers with an LC filter at the DC side are often used to convert AC input into a DC voltage. It is well known that they generate large amounts of harmonic currents. This paper proposes an analytical method for calculating the harmonic currents for both the continuous and discontinuous current conductions. The equations for the harmonic currents are derived, taking into account the effects of the DC and AC side impedances. All the calculations are conducted only by algebraic calculation with high accuracy. The validity of the proposed method is demonstrated by comparison to the results of time simulation. >
TL;DR: In this paper, a three-phase controlled-current PWM rectifier is analyzed and the DC operating point and AC transfer functions are completely determined, and most features of the power converter are clearly interpreted.
Abstract: A recently proposed circuit P-Q transformation is used to analyze a three-phase controlled-current PWM rectifier. The DC operating point and AC transfer functions are completely determined. Most features of the power converter are clearly interpreted. They are: (1) the output voltage can be controlled from zero to maximum; (2) the system is equivalently an ideal current source in the steady state; (3) the system can be described as linear circuits; and (4) the input power factor can be arbitrarily controlled within a certain control range. >
TL;DR: In this paper, the application of active circuitry to increase the performance per size and cost of utility-side EMI filters is considered and the major problems are power line frequency (60 Hz) rejection and the compensation of the feedback loop, which is influenced by the wide-ranging utility impedance.
Abstract: The application of active circuitry to increase the performance per size and cost of utility-side EMI filters is considered. The major problems are power line frequency (60 Hz) rejection and the compensation of the feedback loop, which is influenced by the wide-ranging utility impedance. While analysis and simulations show that these problems prevent the practical application of active filtering to power supplies switching at around 75 kHz, results at 450 kHz demonstrate potential for substantial improvement of EMI filters for switching frequencies of a few hundred kHz, although with the cost of a complex compensation. >
TL;DR: In this article, a general and unified large signal averaged circuit model for current programmed DC-to-DC converters is proposed, from which the large signal characteristics can be derived.
Abstract: A general and unified large signal averaged circuit model for current programmed DC-to-DC converters is proposed. In the averaged circuit model, the active switch is modeled by a current source, with its value equal to the averaged current flowing through it, and the diode is modeled hy the voltage source, with its value equal to the averaged voltage across it. The averaged circuit model has the same topology as the switching converter. The large signal averaged circuit model for current programmed buck, boost, buck-boost and Cuk converters are proposed, from which the large signal characteristics can be obtained. The steady-state and small signal transfer functions of the current programmed DC-to-DC converters can all be derived from their large signal averaged circuit models. The large signal characteristics of the current programmed buck converter are studied by both the phase plane trajectory and the time domain analysis. Experimental prototypes for a current programmed buck converter, with and without an input filter, are breadboarded to verify the analysis. >
TL;DR: In this article, a new control design procedure for PWM DC-DC converters is described, which has two components: a linear feedback, designed via the LQ approach, and a nonlinear feedforward.
Abstract: This paper describes a new control design procedure for PWM DC-DC converters. The control action has two components: a linear feedback, designed via the LQ approach, and a nonlinear feedforward. The proposed control scheme guarantees excellent regulation of the output voltage, even in the presence of large variations of the input reference signal, as pointed out by numerous simulations carried out on different converter topologies. Good performances are also achievable when a suitably designed estimator is inserted into the control loop to reconstruct internal variables and input voltage disturbances from output voltage measurements. >
TL;DR: In this article, a PWM rectifier including an uncontrolled rectifier and a Cuk converter stage driven by a sliding mode controller is described, which allows low-distorted and in-phase line current.
Abstract: A PWM rectifier including an uncontrolled rectifier and a Cuk converter stage driven by a sliding mode controller is described. Like other high-quality rectifiers, this solution allows low-distorted and in-phase line current. Moreover, due to the sliding mode control, fast and stable response is achieved, in spite of the large output filter. Control complexity is the same as that of standard current-mode controls. Converter analysis, design criteria, and experimental results are reported. >
TL;DR: In this article, the authors proposed macromodels to simulate three-phase power converters on such packages, which are suited for steady state and large signal transient analysis at system level.
Abstract: Static power converters can be analyzed by means of widely available circuit simulation software packages such as PSPICE. However, they are usually modeled as a set of real switches, which results in long execution times and possible convergence problems in the case of complex circuits. This paper proposes macromodels to simulate three-phase power converters on such packages. The proposed macromodels are based on converter switching functions rather than actual circuit configuration, and they are suited for steady state and large signal transient analysis at system level. In this approach, voltage source inverters (VSI), current source inverters (CSI), and controlled rectifiers (CR) are simulated as multiport networks avoiding the physical nonlinear micromodels of the power switches. Computer memory and the run-times required for the simulation are thereby minimized. Complete examples of VSI, CSI and CR, with different PWM techniques, are given with specific reference to the PSPICE software to illustrate the effectiveness of the proposed models. >
TL;DR: In this article, the authors explored the origin of the DC current-sharing problem of parallel-converter systems and the dual problem of voltage sharing in series-convex converters.
Abstract: This paper explores the origin of the DC current-sharing problem of parallel-converter systems and the dual problem of voltage sharing in series-converter systems. Both problems may be studied by examining the output plane (output current versus output voltage) of a particular converter. It is shown that strict current source behavior is unnecessary for good current sharing in parallel-converter systems. Furthermore, a broad class of converters whose output voltage is load-dependent, i.e., those that have a moderate value of output resistance, all exhibit good voltage- and current-sharing characteristics. Such converters are often suitable for a/spl times/b arrays of converters that can meet a large range of power-conversion requirements. The output planes of discontinuous mode PWM converters as well as conventional and clamped series resonant converters are examined in detail. A simple small-signal model of the modular converter system is developed. Experimental confirmation of load sharing and the small-signal model is given for the clamped series resonant converter and the series resonant converter for various configurations of four converters. >
TL;DR: In this article, a three-phase single-switch AC-DC flyback converter system is presented, which operates in the discontinuous mode, and the simple structure of its power and control circuit, low mains current distortion, and resistive fundamental behavior, as well as the high-frequency isolation of the controlled output voltage, have been pointed out.
Abstract: In this paper, a new three-phase single-switch AC-DC flyback converter system is presented. The system operates in the discontinuous mode. The simple structure of its power and control circuit, low mains current distortion, and resistive fundamental behavior, as well as the high-frequency isolation of the controlled output voltage, have to be pointed out. Besides the analysis of the stationary operating behavior, the dependencies of the peak values, average values, and rms values of the device currents, and of the maximum blocking voltages across the power electronic devices on the circuit parameters, are given as analytic approximations. The theoretical analysis is verified by digital simulation. >
TL;DR: In this article, an improved version of PWM AC line conditioners is proposed, which uses fewer standard switch modules, in combination with less stringent gating requirements, improves the overall operating reliability of the system.
Abstract: In this paper, an improved version of PWM AC line conditioners is proposed. As compared to previously reported structures, it uses fewer standard switch modules. This, in combination with less stringent gating requirements, improves the overall operating reliability of the system. In addition, it retains the same advantages of a regular force-commutated AC line conditioner, including sinusoidal input-output waveforms, fast dynamic response, and small input-output filters. The operating principle of the proposed structure is discussed, and the voltage feedback loop design is analyzed. Results from a 25 kVA experimental setup are provided for verification. >
TL;DR: In this article, a new method for time-domain analysis of power electronics circuits is developed based on the following principles: (a) the switching topology is a linear time-invariant circuit; (b) at each instant, the voltage across a capacitor and the current through an inductor have a certain value, like an independent voltage- or current source, respectively; (c) generally, no switching relationship between the externally and internally controlled switches may be assumed; (d) prior knowledge of the internally controlled switch' operation is not available; and (e) the
Abstract: A new method for time-domain analysis of power electronics circuits is developed based on the following principles: (a) at each instant, the switching topology is a linear time-invariant circuit; (b) at each instant, the voltage across a capacitor and the current through an inductor have a certain value, like an independent voltage- or current source, respectively; (c) generally, no switching relationship between the externally and internally controlled switches may be assumed; (d) prior knowledge of the internally controlled switches' operation is not available; and (e) the switching action may change the response of the circuit immediately after the switching moment, implying that some constraints may be in violation of the presumed switches' states. The algorithm is based on solving a system of algebraical modified nodal equations at each integration step. The number of systems to be solved equals the number of topologies the converter goes through in a cycle. This feature, and the fact that no solutions of time-differential equations or Laplace transform inverses are required, cause the algorithm to be a fast one. At each step, the presumed state of all the switches is checked, and if some constraints are violated, the program looks for another valid topology. An example, with parasitic effects taken into account, is presented; the experimental results, as well as the simulation results obtained by using other available algorithms, confirmed the accuracy of the results achieved with the presented approach. >
TL;DR: In this article, the Cockcroft-Walton voltage multiplier with an arbitrary number of cells is described and the expressions of cut-off frequency, gain and output impedance are given, and module and phase frequency responses are plotted.
Abstract: The description of the small-signal dynamics of the Cockcroft-Walton voltage multiplier is obtained through state-space modeling in discrete time. Its small-signal equivalent circuit is a two-port linear network whose four transfer functions are given in the Z-transform. The main characteristics and general formulae of the multiplier with an arbitrary number of cells are derived. The expressions of cut-off frequency, gain and output impedance are given, and module and phase frequency responses are plotted. >
TL;DR: In this article, the feasibility of the state variable modeling approach for the power PIN diode was demonstrated, and a simple model of three state variables that has only six parameters, most of which are technological, represented a major improvement in describing circuit/device waveforms during reverse recovery.
Abstract: The concepts of state variable modeling have been applied to obtain a general circuit like model for the power PIN diode. The main aim of this paper is to demonstrate the feasibility of the state variable modeling approach for the PIN diode. From simplified semiconductor device differential equations, the model is built with the corresponding variational equation using an internal approximation. With a special choice of the decomposition functional basis of such internal approximation, it was possible to get efficient and reliable models for the reverse recovery. A simple model of three state variables that has only six parameters, most of which are technological, represented a major improvement in describing circuit/device waveforms during reverse recovery. >
TL;DR: In this paper, a phase difference angle (PDA) controlled pulsewidth-modulated (PWM) inverter is proposed for a two-phase induction motor adjustable speed drive Output waveforms are fixed over the whole operating range of the motor, and motor torque is controlled not by the modulation of the phase voltage, but by the PDA based on the selected harmonic elimination (SHE) PWM technique, the commutation angles of the output voltage are calculated.
Abstract: A phase-difference angle (PDA) controlled pulsewidth-modulated (PWM) inverter is proposed for a two-phase induction motor adjustable speed drive Output waveforms are fixed over the whole operating range of the motor The motor torque is controlled not by the modulation of the phase voltage, but by the PDA Based on the selected harmonic elimination (SHE) PWM technique, the commutation angles of the output voltage are calculated Several characteristics of the two-phase induction motor driven by the PDA inverter are analyzed A hybrid PWM inverter is also proposed to compensate for the degradation of the efficiency at small PDA Not only the PDA but also the voltage amplitude and frequency are used as the parameters for controlling the torque of the motor in the hybrid inverter The speed characteristics of the two-phase induction motor driven by the hybrid PWM inverter are more flexible than when the motor is driven by the conventional PWM inverter, which requires adjustable communication angles >
TL;DR: Theoretical analysis of the proposed so-called sparse neural network is provided, and experimental results that confirm the high performance and technical advantages of the developed modulator are presented.
Abstract: A novel concept of application of neural networks for generation of optimal switching patterns in voltage-controlled inverters is described. The pulsewidth modulator (PWM), based on hardware analog neural networks, responds with high accuracy to any desired value of the modulation index. No microprocessor or large memory typical for the existing optimal PWM schemes is required. Theoretical analysis of the proposed so-called sparse neural network is provided, and experimental results that confirm the high performance and technical advantages of the developed modulator are presented. >
TL;DR: In this article, the authors proposed a method to sense and add appropriately the currents in the transistor, rectifier and capacitors of a PWM converter using current transformers, which can reconstruct the waveforms of inductor and DC output currents accurately while maintaining isolation.
Abstract: The design, analysis and trade-offs of a novel method to sense the inductor and DC output currents of PWM converters are presented. By sensing and adding appropriately the currents in the transistor, rectifier and capacitors of a converter using current transformers, the waveforms of inductor and DC output currents can be reconstructed accurately while maintaining isolation. This method offers high bandwidth, clean waveform, practically zero power dissipation and simple circuit. The technique is applicable to all PWM converters in both continuous and discontinuous modes, and is most suitable for the implementation of current mode control schemes like hysteretic, PWM conductance control, and output current feedforward. This approach has been experimentally verified at a wide range of current levels, duty cycles, and switching frequencies up to 1.4 MHz. >
TL;DR: In this paper, a new discrete position sensor elimination technique for a sinusoidally wound synchronous reluctance motor drive is presented, which determines the rotor position at zero crossing of the phase currents.
Abstract: A new discrete position sensor elimination technique for a sinusoidally wound synchronous reluctance motor drive is presented. The proposed technique determines the rotor position at zero crossing of the phase currents. The rotor position between the zero crossings is determined by applying extrapolation. The proposed technique works well at all speeds, including zero speed. This technique can be used in both vector controlled and conventional constant volts/Hertz type of motor controllers. >
TL;DR: The TLM links enable the circuits connected by the links to be decoupled and simulated as individual circuits, resulting in smaller system matrices, possibility of parallel computation and reduction in computing time.
Abstract: This paper describes the application of the transmission-line modeling (TLM) method to the decoupled simulation of DC linked power electronic systems. Stiff capacitively or inductively smoothed DC links in power electronic systems can be modeled as two-port transmission-line links using the TLM method. The TLM links enable the circuits connected by the links to be decoupled and simulated as individual circuits, resulting in smaller system matrices, possibility of parallel computation and reduction in computing time. Interaction between these linked circuits can be realised by exchanging the incident pulses at both ends of the transmission-line links. Computer simulations of an AC to DC converter used in a laboratory confirms the simplicity of the TLM decoupled simulation approach. >