A New Quick-Response and High-Efficiency Control Strategy of an Induction Motor
TL;DR: In this article, the authors proposed a limit cycle control of both flux and torque using optimum PWM output voltage; a switching table is employed for selecting the optimum inverter output voltage vectors so as to attain as fast a torque response, as low an inverter switching frequency, and as low harmonic losses as possible.
Abstract: New quick-response and high-efficiency control of an induction motor, which is quite different from that of the field-oriented control is proposed. The most obvious differences between the two are as follows. 1) The proposed scheme is based on limit cycle control of both flux and torque using optimum PWM output voltage; a switching table is employed for selecting the optimum inverter output voltage vectors so as to attain as fast a torque response, as low an inverter switching frequency, and as low harmonic losses as possible. 2) The efficiency optimization in the steady-state operation is also considered; it can be achieved by controlling the amplitude of the flux in accordance with the torque command. To verify the feasibility of this scheme, experimentation, simulation, and comparison with field-oriented control are carried out. The results prove the excellent characteristics for torque response and efficiency, which confirm the validity of this control scheme.
Citations
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TL;DR: This paper covers the high-power voltage-source inverter and the most used multilevel-inverter topologies, including the neutral-point-clamped, cascaded H-bridge, and flying-capacitor converters.
Abstract: This paper presents a technology review of voltage-source-converter topologies for industrial medium-voltage drives. In this highly active area, different converter topologies and circuits have found their application in the market. This paper covers the high-power voltage-source inverter and the most used multilevel-inverter topologies, including the neutral-point-clamped, cascaded H-bridge, and flying-capacitor converters. This paper presents the operating principle of each topology and a review of the most relevant modulation methods, focused mainly on those used by industry. In addition, the latest advances and future trends of the technology are discussed. It is concluded that the topology and modulation-method selection are closely related to each particular application, leaving a space on the market for all the different solutions, depending on their unique features and limitations like power or voltage level, dynamic performance, reliability, costs, and other technical specifications.
2,254 citations
TL;DR: Direct self-control (DSC) as discussed by the authors is a simple method of signal processing that gives converter-fed three-phase machines an excellent dynamic performance, and it is sufficient to process the measured signals of the stator currents and the total flux linkages only.
Abstract: The new direct self-control (DSC) is a simple method of signal processing that gives converter-fed three-phase machines an excellent dynamic performance. To control the torque of, say, an induction motor, it is sufficient to process the measured signals of the stator currents and the total flux linkages only. In the basic version of DSC, the power semiconductors of a three-phase voltage source inverter are directly switched on and off via three Schmitt triggers, comparing the time integrals of line-to-line voltages to a reference value of desired flux, if the torque has not yet reached an upper-limit value of a two-limit torque control. Optimal performance of drive systems is accomplished in steady state as well as under transient conditions by combination of several two-limit controls. >
1,730 citations
28 Sep 1991
TL;DR: In this article, a control scheme for parallel-connected inverters in a standalone AC supply system is presented, which uses feedback of only those variables that can be measured locally at the inverter and does not need communication of control signals between the inverters.
Abstract: A scheme for controlling parallel-connected inverters in a standalone AC supply system is presented. This scheme is suitable for control of inverters in distributed source environments such as in isolated AC systems, large and distributed uninterruptible power supply (UPS) systems, photovoltaic systems connected to AC grids, and low-voltage DC power transmission meshes. A key feature of the control scheme is that it uses feedback of only those variables that can be measured locally at the inverter and does not need communication of control signals between the inverters. This is essential for the operation of large AC systems, where distances between inverters make communication impractical. It is also important in high-reliability UPS systems where system operation can be maintained in the face of a communication breakdown. Real and reactive power sharing between inverters can be achieved by controlling two independent quantities: the power angle and the fundamental inverter voltage magnitude. Simulation results are presented. >
1,550 citations
TL;DR: A simple classification of the most important types of predictive control is introduced, and each one of them is explained including some application examples.
Abstract: Predictive control is a very wide class of controllers that have found rather recent application in the control of power converters. Research on this topic has been increased in the last years due to the possibilities of today's microprocessors used for the control. This paper presents the application of different predictive control methods to power electronics and drives. A simple classification of the most important types of predictive control is introduced, and each one of them is explained including some application examples. Predictive control presents several advantages that make it suitable for the control of power converters and drives. The different control schemes and applications presented in this paper illustrate the effectiveness and flexibility of predictive control.
1,389 citations
TL;DR: The author provides a guideline and quick reference for the practicing engineer to decide which methods should be considered for an application of a given power level, switching frequency, and dynamic response.
Abstract: The author evaluates the state of the art in pulsewidth modulation for AC drives fed from three-phase voltage source inverters. Feedforward and feedback pulsewidth modulation schemes with relevance for industrial application are described and their respective merits and shortcomings are explained. Secondary effects such as the influence of load-current dependent switching time delay and transients in synchronized pulsewidth modulation schemes are discussed, and adequate compensation methods are presented. Recorded oscillograms illustrate the performance of the respective pulsewidth modulation principles. The author provides a guideline and quick reference for the practicing engineer to decide which methods should be considered for an application of a given power level, switching frequency, and dynamic response. >
1,250 citations
References
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TL;DR: In this paper, the rotor resistance is the most essential changing parameter and a method of automatic adaption of the control to the changes in this parameter is presented, based on the measurement of only motor voltages and currents and is implemented by analog means.
Abstract: The performance of speed-controlled induction motor drives, without a direct sensing of the flux, depends heavily on the accuracy with which the motor parameters are known. They change widely with the temperature, frequency, and current amplitude. With a control based on rotor position measurement and inner current control loops, the rotor resistance is the most essential changing parameter. A method of automatic adaption of the control to the changes in this parameter is presented. The proposed strategy is based on the measurement of only motor voltages and currents and is implemented by analog means. It does not make use of transducers or probes to measure the temperature or the flux in the motor.
308 citations
TL;DR: In this article, a rotor parameter identification technique for the purpose of updating the control gains of an induction motor vector controller is described, which utilizes the current source nature of a current-regulated PWM inverter by injecting a prescribed negative sequence current perturbation signal.
Abstract: A rotor parameter identification technique for the purpose of updating the control gains of an induction motor vector controller is described. The approach utilizes the current source nature of a current-regulated PWM inverter by injecting a prescribed negative sequence current perturbation signal. The corresponding negative sequence voltage is sensed and decomposed into its d and q components. By injecting the signal at two widely separated frequencies (one perhaps dc), it is shown that the rotor resistance can be uniquely derived. Verification of the validity of the technique is obtained by a full-scale simulation of a vector controlled induction motor drive.
291 citations
TL;DR: In this paper, it was shown that the amount of performance degradation is strongly dependent on machine parameters and the large magnetizing inductance and low rotor resistance typically associated with larger, more efficient machines tend to amplify the effects of detuning compared to the relative insensitivity of small low-efficiency machines.
Abstract: If the value of the time constant used in the slip calculator of a feedforward field orientation drive system deviates from the correct value, the decoupling of flux and torque is lost, and both steady-state and transient response is degraded. An analysis of detuned operation shows that the amount of performance degradation is strongly dependent on machine parameters. The large magnetizing inductance and low rotor resistance typically associated with larger, more efficient machines is shown to tend to amplify the effects of detuning compared to the relative insensitivity of small low-efficiency machines. It is also shown that for many applications the transient response effects of detuning can be handled by the outer control loops and that the major problem is maintaining the steady-state operating flux and current at reasonable levels.
211 citations
TL;DR: In this article, a new speed control system for induction motors has been developed which is capable of controlling with quick field weakening and superior response and stability, which is to control the stator current as a vector quantity on the basis of slip frequency control.
Abstract: A new speed control system for induction motors has been developed which is capable of controlling with quick field weakening and superior response and stability. This method is to control the stator current as a vector quantity on the basis of slip frequency control. More specifically, it is designed to calculate the commanded stator current of the induction motor by corresponding to flux and torque commands on the basis of motor constants and use the calculated commands to control the stator current.
115 citations
TL;DR: In this article, Park vectors are used to predict the waveforms of inverter quantities under various load conditions, such as passive R-L and R-C loads, and the current distribution of the inverter can be obtained from the current vector.
Abstract: A method of analysis for three-phase inverters is described. The method is based on Park vectors [1], [2] and predicts the waveforms of inverter quantities under various load conditions. The procedure discussed can be used to determine the commutation sequence of a pulsewidth modulated inverter. The current distribution of the inverter can be obtained from the current vector. The vectors of the inverter voltage and currents are determined for passive R-L and R-C loads. Oscillograms of the current vectors are shown for different loads.
54 citations