Showing papers in "IEEE Transactions on Industrial Electronics in 1997"
TL;DR: A low-power low-cost highly efficient maximum power point tracker (MPPT) to be integrated into a photovoltaic (PV) panel is proposed, which can result in a 25% energy enhancement compared to a standard photovolar panel, while performing functions like battery voltage regulation and matching of the PV array with the load.
Abstract: A low-power low-cost highly efficient maximum power point tracker (MPPT) to be integrated into a photovoltaic (PV) panel is proposed. This can result in a 25% energy enhancement compared to a standard photovoltaic panel, while performing functions like battery voltage regulation and matching of the PV array with the load. Instead of using an externally connected MPPT, it is proposed to use an integrated MPPT converter as part of the PV panel. It is proposed that this integrated MPPT uses a simple controller in order to be cost effective. Furthermore, the power converter has to be very efficient, in order to transfer more energy to the load than a directly-coupled system. This is achieved by using a simple soft-switched topology. A much higher conversion efficiency at lower cost will then result, making the MPPT an affordable solution for small PV energy systems.
632 citations
TL;DR: The algorithm described in this paper takes advantage of color thresholding to segment the image and shape analysis to detect the signs and uses a neural network for the classification.
Abstract: A vision-based vehicle guidance system for road vehicles can have three main roles: (1) road detection; (2) obstacle detection; and (3) sign recognition. The first two have been studied for many years and with many good results, but traffic sign recognition is a less-studied field. Traffic signs provide drivers with very valuable information about the road, in order to make driving safer and easier. The authors think that traffic signs most play the same role for autonomous vehicles. They are designed to be easily recognized by human drivers mainly because their color and shapes are very different from natural environments. The algorithm described in this paper takes advantage of these features. It has two main parts. The first one, for the detection, uses color thresholding to segment the image and shape analysis to detect the signs. The second one, for the classification, uses a neural network. Some results from natural scenes are shown.
552 citations
TL;DR: A new three-phase three-switch three-level pulsewidth modulated (PWM) rectifier system is developed that can be characterized by sinusoidal mains current consumption, controlled output voltage, and low-blocking voltage stress on the power transistors.
Abstract: Based on the combination of a three-phase diode bridge and a DC/DC boost converter, a new three-phase three-switch three-level pulsewidth modulated (PWM) rectifier system is developed. It can be characterized by sinusoidal mains current consumption, controlled output voltage, and low-blocking voltage stress on the power transistors. The application could be, e.g., for feeding the DC link of a telecommunications power supply module. The stationary operational behavior, the control of the mains currents, and the control of the output voltage are analyzed. Finally, the stresses on the system components are determined by digital simulation and compared to the stresses in a conventional six-switch two-level PWM rectifier system.
509 citations
TL;DR: This study reveals that the vehicles' operational constraints, such as initial acceleration and grade, can be met with minimum power rating if the power train can be operated mostly in the constant power region.
Abstract: There is a growing interest in electric and hybrid-electric vehicles due to environmental concerns. Efforts are directed toward developing an improved propulsion system for electric and hybrid-electric vehicles applications. This paper is aimed at developing the system design philosophies of electric and hybrid vehicle propulsion systems. The vehicles' dynamics are studied in an attempt to find an optimal torque-speed profile for the electric propulsion system. This study reveals that the vehicles' operational constraints, such as initial acceleration and grade, can be met with minimum power rating if the power train can be operated mostly in the constant power region. Several examples are presented to demonstrate the importance of the constant power operation. Operation of several candidate motors in the constant power region are also examined. Their behaviors are compared and conclusions are made.
451 citations
TL;DR: This paper reviews the current status of multidisciplinary technologies in EVs and various challenges of power electronics technology for EV propulsion, battery charging, and power accessories are explored.
Abstract: In response to concerns about energy cost, energy dependence, and environmental damage, a rekindling of interest in electric vehicles (EVs) has been obvious. Based on the "California rules" on zero emission vehicles in the United States, as well as similar tightened air pollution regulation in Europe, Asia, and much of the rest of the world, the market size of EVs will be enormous. Thus, the development of power electronics technology for EVs will take an accelerated pace to fulfil the market needs. This paper reviews the current status of multidisciplinary technologies in EVs. Various challenges of power electronics technology for EV propulsion, battery charging, and power accessories are explored.
423 citations
TL;DR: It is shown that a multilevel inverter leg, composed of p pairs of switches and p-1 capacitors, forms a multivariable nonlinear system that cannot be properly modeled by standard methods such as state-space averaging.
Abstract: In this paper, the imbricated cells multilevel converters are studied and modeled from a control viewpoint. These converters make use of several switches connected in a series, which allows using switches with reduced voltage ratings; these low voltage switches have lower conduction losses and can switch at higher frequency. In addition to this feature common to all converters using series connected switches, the control signals of multilevel converters can be phase shifted to increase the apparent switching frequency and improve the dynamic performances of the whole converter. It is shown that a multilevel inverter leg, composed of p pairs of switches and p-1 capacitors, forms a multivariable nonlinear system that cannot be properly modeled by standard methods such as state-space averaging. The transient behavior of this system depends on the current harmonics and their phase shift with the different control signals. A specific model is detailed, studied, and used to illustrate the properties of these converters. In particular, the natural balancing of the voltage across the switches is demonstrated and the time constants involved in this process are determined.
381 citations
TL;DR: This paper analyzes the operation of both power converters as DCM-PFP using a small-signal model to aid the control loop design and results are presented that are in agreement with the theoretical analysis and complement the work.
Abstract: Sepic and Cuk power converters working as power factor preregulators (PFP) in the discontinuous conduction mode (DCM) present the following desirable characteristics for a PFP: (1) the power converter works as a voltage follower (no current loop is needed); (2) the theoretical power factor is unity; and (3) the input current ripple is defined at the design stage. Besides, input-output galvanic isolation is easily obtained. This paper analyzes the operation of both power converters as DCM-PFP. Design equations are derived, as well as a small-signal model to aid the control loop design. Both simulation and experimental results are presented that are in agreement with the theoretical analysis and complement the work.
371 citations
TL;DR: In this article, the authors proposed a pulse-based dead-time compensator (PBDTC) for PWM voltage inverters, which is less hardware-and software-intensive than other low-cost solutions.
Abstract: The dead time necessary to prevent the short circuit of the power supply in pulsewidth-modulated (PWM) voltage inverters results in output voltage errors. Although individually small, when accumulated over an operating cycle, the voltage errors are sufficient to distort the applied PWM signal. This paper presents a method to correct for the dead-time errors. The pulse-based dead-time compensator (PBDTC) is less hardware- and software-intensive than other dead-time compensation methods providing a low-cost solution. The pulse-based technique is developed by analyzing the effects of dead time on a pulse-by-pulse basis and correcting each pulse accordingly. The technique is evaluated through simulation and experimental results. Other compensation methods are evaluated, and the results compared with the pulse-based technique. This comparison indicates previous methods can produce magnitude and phase errors in the applied terminal voltage, whereas the proposed method compensates for the dead time without significant magnitude and phase errors in the terminal voltage of PWM voltage source inverters.
283 citations
TL;DR: It is demonstrated here that stable responses can be obtained for both buck and boost power converters under these conditions and shows that a nonlinear controller such as fuzzy logic can be inexpensively implemented with microcontroller technology.
Abstract: This paper presents an implementation of a fuzzy controller for DC-DC power converters using an inexpensive 8-bit microcontroller. An "on-chip" analog-to-digital (A/D) converter and PWM generator eliminate the external components needed to perform these functions. Implementation issues include limited on-chip program memory of 2 kB, unsigned integer arithmetic and computational delay. The duty cycle for the DC-DC power converter can only be updated every eight switching cycles because of the time required for the A/D conversion and the control calculations. However, it is demonstrated here that stable responses can be obtained for both buck and boost power converters under these conditions. Another important result is that the same microcontroller code, without any modifications, can control both power converters because their behavior can be described by the same set of linguistic rules. The contribution shows that a nonlinear controller such as fuzzy logic can be inexpensively implemented with microcontroller technology.
262 citations
TL;DR: The relationship between regular-sampled pulse-width modulation (PWM) and space-vector modulation for inverter drives is defined, and it is shown that, under certain circumstances, the two approaches are equivalent.
Abstract: The relationship between regular-sampled pulse-width modulation (PWM) and space-vector modulation for inverter drives is defined, and it is shown that, under certain circumstances, the two approaches are equivalent. The various possibilities of adding a zero-sequence component to the regular-sampled sinusoidal modulating wave are explored, and these effects are quantified. It is shown that this leads to "equal-null" pulse times, which extend the linear modulation range and simplify the microprocessor implementation.
244 citations
TL;DR: Progress in topology, control, and design aspects in three-phase power-factor correction (PFC) techniques are reviewed and Representative soft-switching schemes, including zero-voltage and zero-current switched pulsewidth modulated (PWM) techniques, are investigated.
Abstract: This paper reviews progress in topology, control, and design aspects in three-phase power-factor correction (PFC) techniques. Different switching rectifier topologies are presented for various applications. Representative soft-switching schemes, including zero-voltage and zero-current switched pulsewidth modulated (PWM) techniques, are investigated. Merits and limitations of these techniques are discussed and illustrated by experimental results obtained on prototype converters. Control and input filter design issues are also discussed.
TL;DR: The synthesis and performance of a shunt active power filter based on the three-phase pulsewidth modulation (PWM) voltage converter connected to the AC mains, which can also be implemented with a digital signal processor.
Abstract: This paper presents the synthesis and performance of a shunt active power filter based on the three-phase pulsewidth modulation (PWM) voltage converter connected to the AC mains. Current harmonics and asymmetries caused by nonlinear loads can be compensated. A decoupled system in Park's variables is achieved and so simple controllers with excellent performance can be used. The controllers are implemented directly in the Park's referential. Expressions for the controller's synthesis are derived. Experimental results from a 2 kVA IGBT prototype showing excellent dynamic and steady-state system's performances are presented. The control circuit is implemented with analog and digital electronic circuits. A considerable amount of electronic circuits are needed. The method presented in this paper can also be implemented with a digital signal processor.
TL;DR: It is shown that, if Gaussian radial basis function networks are used, uniformly stable adaptation is assured and asymptotically tracking is achieved and the controller thus obtained does not require the inverse of the Jacobian matrix.
Abstract: In this paper, the adaptive neural network control of robot manipulators in the task space is considered. The controller is developed based on a neural network modeling technique which neither requires the evaluation of inverse dynamical model nor the time-consuming training process. It is shown that, if Gaussian radial basis function networks are used, uniformly stable adaptation is assured and asymptotically tracking is achieved. The controller thus obtained does not require the inverse of the Jacobian matrix. In addition, robust control can be easily incorporated to suppress the neural network modeling errors and the bounded disturbances. Numerical simulations are provided to show the effectiveness of the approach.
TL;DR: This paper presents axial flux induction and synchronous machines as wheel motor applications and some considerations for each motor type are drawn by the authors.
Abstract: For electric car propulsion systems, the wheel motor is an application that requires the electrical machine has shape flexibility, compactness, robustness, high efficiency, and high torque. Axial flux machines are an interesting solution, where the motor is directly coupled to, or inside, the drive wheels. In this paper, axial flux induction and synchronous machines as wheel motor applications are presented and some considerations for each motor type are drawn by the authors. The structure with two rotors seems to be a very promising solution for both induction and synchronous machines. In the induction motor case, the two rotors can rotate at different speeds, thus the motor can act as a mechanical differential. The axial flux permanent magnet motor with two rotors is very compact and can be integrated inside the wheel.
TL;DR: A novel randomized control strategy for three-phase voltage source inverters, based on voltage space vectors, is described, which results in switching losses in the inverter being reduced by about half in comparison with those using the classic space vector pulsewidth PWM method.
Abstract: A novel randomized control strategy for three-phase voltage source inverters, based on voltage space vectors, is described. An implicit asymmetrical modulating function results in switching losses in the inverter being reduced by about half in comparison with those using the classic space vector pulsewidth PWM method. The pulse rate is varied within individual 60/spl deg/ sectors of the vector plane, so that the power spectra of the output voltage are spread over a wide frequency range and acquire a continuous part. Relevant theoretical analyses, computer simulations and experimental results are presented.
TL;DR: Compared with previous methods of control developed for series active filters, this method is simpler to implement because it is only required to generate a sinusoidal current, in-phase with the mains voltage, the amplitude of which is controlled through the error in the load voltage.
Abstract: A series active power filter working as a sinusoidal current source, in-phase with the mains voltage, has been developed and tested. The amplitude of the fundamental current in the series filter is controlled through the error signal generated between the load voltage and a pre-established reference. The control allows an effective correction of power factor, harmonic distortion and load voltage regulation. Compared with previous methods of control developed for series active filters, this method is simpler to implement because it is only required to generate a sinusoidal current, in-phase with the mains voltage, the amplitude of which is controlled through the error in the load voltage. The proposed system has been studied analytically and tested using computer simulations and experiments. In the experiments, it has been verified that the filter keeps the line current almost sinusoidal and in-phase with the line voltage supply. It also responds very quickly under sudden changes in load conditions, reaching its steady-state in about two cycles of the fundamental.
TL;DR: In this article, a new topology for a PWM rectifier which achieves unity power factor on the AC supply side and ripple reduction on the DC output side is presented. But it does not require a large DC capacitor or a passive LC resonant circuit.
Abstract: This paper presents a new topology for a pulsewidth modulation (PWM) rectifier which achieves unity power factor on the AC supply side and ripple reduction on the DC output side. The main circuit of this rectifier consists of a conventional PWM rectifier and a pair of additional switches. The switches and PWM rectifier are controlled such that the ripple current on the DC line is reduced, and unity power factor is achieved on the AC line. As a result, this circuit does not require a large DC capacitor or a passive LC resonant circuit. Furthermore, control of the additional switches and PWM rectifier requires only a simple control circuit. The effectiveness of this circuit was confirmed by experiments and analysis. The rectifier is useful for uninterruptible power systems (UPSs) and DC power supplies, especially for cases in which batteries are connected to the DC line.
TL;DR: By introducing the direct field-oriented (DFO) control, which is insensitive to the variation of machine parameters in the field-weakening region, the drive system can obtain robustness to parameter variations.
Abstract: In this paper, a novel field-weakening scheme for the induction machine is presented. The proposed algorithm, based on the voltage control strategy, ensures the maximum torque operation over the entire field-weakening region without using the machine parameters. Also, by introducing the direct field-oriented (DFO) control, which is insensitive to the variation of machine parameters in the field-weakening region, the drive system can obtain robustness to parameter variations. Moreover, the speed sensorless control can be achieved in the very-high-speed range, where the utilization of the speed sensor is limited. Experimental results for the laboratory induction motor drive system confirm the validity of the proposed control algorithm.
TL;DR: It is shown that the switching frequency reduction is achieved with no penalty in the line current harmonic distortion and a significant reduction of AC line current distortion is obtained with the modified dead-band technique for modulation indexes greater than 0.4.
Abstract: On-line pulsewidth modulation (PWM) pattern generators for current-source rectifiers and inverters offer a number of control advantages over off-line optimized patterns. However, when implemented using the principles which apply to voltage-source inverter PWM pattern generators, the switching frequency is equal to: (1) the carrier frequency in standard carrier-based implementations and (2) a function of the cycle frequency, sequence of space vectors, and selection of the zero space vector in space vector implementations. This paper shows that this frequency can be reduced to one-half of the respective frequencies. Two pattern generators are investigated: (1) an analog on-line carrier-based technique, namely, the modified dead-band technique and (2) a digital on-line space vector-based technique, where advantage is taken of the extra zero state available in current-source converters. It is shown that the switching frequency reduction is achieved with no penalty in the line current harmonic distortion. Moreover, a significant reduction of AC line current distortion is obtained with the modified dead-band technique for modulation indexes greater than 0.4. The principles of operation of the proposed schemes are explained, Experimental results on a 5 kVA current-source rectifier and a 5 kVA current-source inverter confirm the feasibility and features of the proposed pattern generators.
TL;DR: In this article, an active power filter based on a digital signal processing (DSP) controller with enhanced current control performance is presented, where a novel predictive current control method is introduced to compensate the phase error of harmonic components caused by discrete sampling and finite nonnegligible execution time delay.
Abstract: This paper presents an active power filter based on a digital signal processing (DSP) controller with enhanced current control performance. A novel predictive current control method is introduced to compensate the phase error of harmonic components caused by discrete sampling and finite nonnegligible execution time delay. The concept of average current control is also introduced that is adequate for digital current control. With a close coordination between the reference current prediction, PWM pattern generation, and control timing, a high performance control is achieved. Experimental results show that the developed system gives satisfactory performance in harmonic and reactive power compensation.
TL;DR: An improved ramp comparator is proposed in which the current error signals are compared to three 120/spl deg/ phase-shifted triangular waveforms and this eliminates the zero voltage vector applied to the inverter and reduces the inherent amplitude and phase errors.
Abstract: Current-controlled pulsewidth modulated (PWM) inverters are widely used in high-performance AC drives because they give high dynamic responses in such systems. This paper presents a comparative study of several current controllers. Particular attention is paid to the hysteresis controller and the ramp-comparator controller, due to their simplicity and widespread use. An improved ramp comparator is proposed in which the current error signals are compared to three 120/spl deg/ phase-shifted triangular waveforms. This eliminates the zero voltage vector applied to the inverter and reduces the inherent amplitude and phase errors. Computer simulations are used to compare the performances. Fast Fourier transform technique is used to show the power spectrum of the current waveforms. Experimental results validate the simulated performances.
TL;DR: A digital signal processor (DSP)-based permanent magnet (PM) synchronous motor drive with a proposed recursive least-square (RLS) estimator and real-time integral-proportional (IP) position controller is introduced in this study.
Abstract: A digital signal processor (DSP)-based permanent magnet (PM) synchronous motor (SM) drive with a proposed recursive least-square (RLS) estimator and real-time integral-proportional (IP) position controller is introduced in this study. First, the rotor inertia constant, the damping constant, and the disturbed load torque of the synchronous motor are estimated by the proposed RLS estimator, which is composed of an RLS estimator and a torque observer. Next, the IP position controller is real-time designed according to the estimated rotor parameters, to match the time-domain command tracking specifications. Then, the observed disturbance torque is fed forward, to increase the robustness of the synchronous motor drive.
TL;DR: The design concepts, configuration, and performance of the motor, controller, and drive system developed for this high-performance electric vehicle, designated as the IZA, are described.
Abstract: We have, in accordance with new concepts, undertaken the development of a high-performance electric motor vehicle, designated as the IZA. The main performance features of the IZA are a maximum speed of 176 km/h, a range of 548 km per charge at a constant speed of 30 km/h, and acceleration from 0 to 400 m in 18 s. We have developed a direct driving in-wheel motor and controller in order to achieve high performance characteristics. The in-wheel motor is composed of an outer rotor with a rare earth permanent magnet (Sm-Co) and an inner stator. The motor drive controller consists of a three-phase inverter and a microprocessor-based controller. The maximum output and maximum torque of each total drive system, including motor and inverter, are 25 kW and 42.5 kg/spl middot/m, respectively, and the total efficiency of the drive system is over 90% at the rated speed. The performance of the motor, controller, and drive system have been confirmed by numerous simplex and vehicle transit tests. This paper describes the design concepts, configuration, and performance of the motor, controller, and drive system developed for this high-performance electric vehicle.
TL;DR: The fundamental drawback of conventional linear power amplifiers-the high loss-is avoided and the low-frequency distortions of switching amplifiers caused by the interlock delay of their power transistors are avoided with the presented switched-mode assisted linear amplifier system.
Abstract: This paper presents a combined power amplifier system consisting of a linear amplifier unit with a switched-mode (class D) current dumping stage arranged in parallel. With this topology, the fundamental drawback of conventional linear power amplifiers-the high loss-is avoided. Compared to a pure class D (switching) amplifier, the presented system needs no output filter to reduce the switching frequency harmonics. This filter (usually of multistage type) generally deteriorates the transient response of the system and impairs the feedback loop design. Furthermore, the low-frequency distortions of switching amplifiers caused by the interlock delay of their power transistors are avoided with the presented switched-mode assisted linear amplifier system. This can be considered as a master-slave system with a guiding linear amplifier and a supporting class D slave unit. The paper describes the operating principle of the system, analyzes the fundamental relationships for the circuit design, and presents simulation results. Finally, various further topologies of switched-mode assisted linear amplifiers are given.
TL;DR: It was verified that the flux estimation works well at zero speed finite torque start-up mode and low- and high-speed field weakening regions, thus completely eliminating the need of a speed sensor.
Abstract: The concept of a programmable cascaded low-pass filter method of flux vector synthesis has been introduced in the literature. In this paper, the idea is expanded, analyzed, improved, and then applied to a stator flux oriented 100-kW electric vehicle drive. It was verified that the flux estimation works well at zero speed finite torque start-up mode and low- and high-speed field weakening regions, thus completely eliminating the need of a speed sensor.
TL;DR: A fast controller is presented for single-phase boost-type power factor correction circuits, where the twice-line-frequency ripple component is removed from the measured output voltage with an adaptive estimator to reduce the closed-loop time constants and overshoots.
Abstract: A fast controller is presented for single-phase boost-type power factor correction circuits. The twice-line-frequency ripple component is removed from the measured output voltage with an adaptive estimator. This enables the closed-loop time constants and overshoots to be reduced by two orders of magnitude compared to traditional designs. The controller copes with considerable uncertainty in input voltage magnitude, line frequency and output capacitance. All sections of the control system are shown to be asymptotically stable. Experimental results are presented to verify the excellent dynamics and robust behavior of the design.
TL;DR: The analysis results indicate that the required size of the condenser filter can be smaller with battery power supplies than with other power supplies, such as bridge-type AC source DC power supplies.
Abstract: In designing interface circuits to a battery, often the battery is assumed to be a simple voltage source. However, the battery itself has internal parameters. This means that the internal parameters of the battery models need to be considered for the interface design. Several electrical battery models are presented. Then, using these electrical battery models, the analysis and the design of the interface circuit are described. Analysis and experimental results show that an electrical battery model which reflects battery characteristics has to be used for the optimal design of the interface circuit. Finally, the analysis results indicate that the required size of the condenser filter can be smaller with battery power supplies than with other power supplies, such as bridge-type AC source DC power supplies.
TL;DR: In this paper, a three-phase rectifier employing three single-phase boost power-factor-correction circuits is analyzed, and the zero-voltage transition technique is successfully applied to each converter, in order to obtain zero turn on losses and soft turnoff of the freewheeling diodes.
Abstract: A three-phase rectifier employing three single-phase boost power-factor-correction circuits is analyzed. Each converter operates in the continuous conduction mode (CCM), which allows a high power factor and a small EMI filter. Current sharing is ensured by a common voltage loop driving the individual current loops of the three converters. A suitable circuit arrangement is devised to limit phase interaction. The zero-voltage-transition technique (ZVT) is successfully applied to each converter, in order to obtain zero turn on losses and soft turnoff of the freewheeling diodes. Results of a 1800-W 100-kHz experimental prototype are reported, which confirm the theoretical forecasts.
TL;DR: A real-time condition-monitoring algorithm for pulsewidth modulation (PWM) inverter induction-motor drives designed to detect the intermittent loss of firing pulses of an individual switching device within the inverter.
Abstract: This paper develops a real-time condition-monitoring algorithm for pulsewidth modulation (PWM) inverter induction-motor drives. It is designed to detect the intermittent loss of firing pulses of an individual switching device within the inverter. The mathematical model of the induction machine is linearized in the field-torque coordinates, and the misfiring of the inverter is represented by pulse functions, which have effects in both the field and torque directions. Since the fault considered is of an intermittent nature, the time-domain response of the magnetizing and the torque-producing components of the motor stator current is used to form the condition-monitoring signal. The method is adaptive to changes in the operating point during variable-speed operation. Digital simulation and laboratory experiment are utilized to illustrate the method and to evaluate the computational effort required.
TL;DR: It is concluded that a combination of a random modulation strategy and feedforward/feedback techniques gives an almost ideal AC motor drive system.
Abstract: PWM-VSI based AC motor drives have two main problems. The inverter is nonlinear which causes instability problems in some specific working points of the AC machine and it emits acoustic noise due to the switching frequency. Nonlinearities like dead-time in the inverter, load dependent DC-link voltage ripple and the voltage drop across the switches are modeled and compensated by improved modulation techniques in order to obtain an almost ideal inverter. Different feedback and feedforward techniques are proposed. The acoustic noise is reduced by using a random modulation strategy. Measurements show a significant improvement by using feedforward and feedback techniques for linearizing the inverter. An improvement in reduction of the acoustic noise emission is also achieved by using random modulation. It is concluded that a combination of a random modulation strategy and feedforward/feedback techniques gives an almost ideal AC motor drive system.