共查询到20条相似文献,搜索用时 31 毫秒
1.
Blaabjerg F. Freysson S. Hansen H.-H. Hansen S. 《Power Electronics, IEEE Transactions on》1997,12(4):704-714
This paper presents a new space-vector modulation strategy suitable for a low-cost pulse-width-modulation (PWM) voltage-source (VS) inverter employing only four switches, four diodes, and a split-capacitor bank in the DC link. The work is motivated by the need for an efficient and flexible modulation method, which is optimized with respect to minimum machine-torque ripple. The modulation strategy is named space-vector modulation for four-switch inverter (SVMFSI), and it is realized by planning the switching patterns between four active voltage vectors on the basis of a desired flux trajectory for the stator-flux vector in the AC machine. The strategy is implemented in a single 8-bit microcontroller as a double-sided modulation strategy. Simulations of the machine-torque ripple are performed at a switching frequency of 4 kHz and indicate a torque ripple of 14% at nominal load. Finally, selected results are verified experimentally on a 1.5-kVA prototype B4 inverter. The test results indicate high-quality output-voltage spectra with no low-order voltage harmonics and a harmonic-loss factor (HLF) of 1.12% at unity modulation index 相似文献
2.
A torque control method is described that can generate a motor torque larger than the rated torque over a wide speed range without a current regulator and a speed sensor, even if the induction motor is driven by a pulse-width-modulation (PWM) inverter with a high switching frequency. Control is performed by a magnetic flux compensation control loop. The first control loop suppresses the magnetic flux reduction generated when the load torque and the inverter angular frequency are varied. This reduction is calculated using both inverter angular frequency and slip angular frequency. The current distortion due to the dead time of the PWM signals is suppressed by correcting the signal pulse widths on the basis of errors generated between the PWM reference signals and the inverter output voltage. Experiments confirmed that an induction motor could generate motor torque of more than 150% of the rated torque. The current distortion factor was less than 10% over a wide frequency range 相似文献
3.
A sensor to measure the stator torsional vibration due to torque ripple produced by a surface mount permanent magnet machine is first described. The sensor is relatively inexpensive and is straight forward to incorporate into a drive system. Experiments are performed to validate that the voltage produced by the sensor is linearly related to torque ripple amplitude. Closed-loop controllers are then described that adjust the stator current harmonics applied to the machine to achieve a commanded average torque while mitigating measured torsional vibration. Simulation and experimental results are used to demonstrate the effectiveness of the control techniques. 相似文献
4.
Four-wire dynamic voltage restorer based on a three-dimensional voltage space vector PWM algorithm 总被引:3,自引:0,他引:3
Changjiang Zhan Arulampalam A. Jenkins N. 《Power Electronics, IEEE Transactions on》2003,18(4):1093-1102
A modified voltage space vector pulse-width modulated (PWM) algorithm for a four-wire dynamic voltage restorer (DVR) is described. The switching strategy based on a three-dimensional (3-D) /spl alpha//spl beta/O voltage space is applicable to the control of three-phase four-wire inverter systems such as the split-capacitor PWM inverter and the four-leg PWM inverter. In contrast to the conventional voltage space vector PWM method, it controls positive, negative and zero sequence components of the terminal voltages instantaneously. Three 3-D modulation schemes are analyzed with respect to total harmonic distortion (THD), weighted total harmonic distortion (WTHD), neutral line ripple and switching loss over the whole range of the modulation index when the DVR experiences both balanced and unbalanced sags with phase angle jumps. Experimental results from a 9 kW DVR system using a split-capacitor PWM inverter are presented to validate the simulation results. 相似文献
5.
《Power Electronics, IEEE Transactions on》2009,24(5):1330-1339
6.
Dong-Choon Lee Young-Sin Kim 《Industrial Electronics, IEEE Transactions on》2007,54(2):797-804
This paper proposes a novel control scheme of single-phase-to-three-phase pulsewidth-modulation (PWM) converters for low-power three-phase induction motor drives, where a single-phase half-bridge PWM rectifier and a two-leg inverter are used. With this converter topology, the number of switching devices is reduced to six from ten in the case of full-bridge rectifier and three-leg inverter systems. In addition, the source voltage sensor is eliminated with a state observer, which controls the deviation between the model current and the system current to be zero. A simple scalar voltage modulation method is used for a two-leg inverter, and a new technique to eliminate the effect of the dc-link voltage ripple on the inverter output current is proposed. Although the converter topology itself is of lower cost than the conventional one, it retains the same functions such as sinusoidal input current, unity power factor, dc-link voltage control, bidirectional power flow, and variable-voltage and variable-frequency output voltage. The experimental results for the V/f control of 3-hp induction motor drives controlled by a digital signal processor TMS320C31 chip have verified the effectiveness of the proposed scheme 相似文献
7.
Kouro S. Bernal R. Miranda H. Silva C.A. Rodriguez J. 《Power Electronics, IEEE Transactions on》2007,22(6):2116-2123
This paper presents a high-performance torque and flux control strategy for high-power induction motor drives. The control method uses the torque error to control the load angle, obtaining the appropriate flux vector trajectory from which the voltage vector is directly derived based on direct torque control principles. The voltage vector is then generated by an asymmetric cascaded multilevel inverter without need of modulation and filter. Due to the high output quality of the inverter, the torque response presents nearly no ripple. In addition, switching losses are greatly reduced since 80% of the power is delivered by the high-power cell of the asymmetric inverter, which commutates at fundamental frequency. Simulation and experimental results for 81-level inverter are presented. 相似文献
8.
A proposal for rejecting DC-link voltage ripple in inverters operating on programmed PWM waveforms is examined in detail. It is demonstrated how continuous elimination of harmonics is achieved at the inverter output while simultaneously rejecting the DC-link voltage ripple. Thus, with the proposed technique, high-quality voltage is guaranteed at the inverter output terminals even with a substantial low-frequency voltage ripple on the DC-link. A thorough modeling of this technique along with the tradeoffs involved in acquiring the immunity to DC-link ripple is illustrated in detail. Potential applications of the technique are in fixed and variable frequency inverters for power supplies and AC motor drives that experience voltage ripple in the DC link such as when fed from a weak AC system that is frequently unbalanced. A design procedure along with the digital implementation of the proposed technique is described. Selected results were verified experimentally on a laboratory inverter 相似文献
9.
In this paper, a novel technique for the direct torque control (DTC) of an induction motor is proposed, which overcomes the trouble of high torque ripple afflicting the conventional DTC technique. With the novel technique, the inverter voltage vector selected from the switching table is applied for the time interval needed by the torque to reach the upper (or the lower) limit of the band, where the time interval is calculated from a suitable modeling of the torque dynamics. By this approach, the control system emulates the operation of a torque hysteresis controller of analog type since the application time of the inverter voltage vector is dictated by the allowed torque excursion and not by the sampling period. It is shown by experimental results that the technique yields a considerable reduction of the torque ripple. A further and ultimate reduction is obtained by compensating for the delay inherent in the discrete-time operation of the control system. The outcome is that the torque ripple of the motor is constrained within the hysteresis band of the torque controller, for a band of customary value. An ancillary merit of the technique is the almost full elimination of the average torque error inherent in the conventional technique. If the hysteresis band is shrunk, the torque ripple is bound to swing out the band limits. Under this circumstance, an extension of the technique is developed, which helps keep the torque ripple at minimum. To assess the characteristics of the proposed DTC technique, the following quantities: average torque error, rms value of the torque ripple, and inverter switching frequency are measured for different stator flux angular speeds and hysteresis bands of the torque and flux controllers. As a comparison, the same quantities are given for the conventional DTC technique. 相似文献
10.
An adaptive space vector modulation (SVM) approach to compensate the DC-link voltage ripple in a B4 inverter is proposed and examined in detail. The theory, design, and performance of this pulsewidth modulation (PWM) method are presented, and the method effectiveness is demonstrated by extensive simulations and experiments. High-quality output currents are guaranteed by this approach even with substantial DC-voltage variations that might be caused by an unbalanced AC supply system, the diode rectification of the line voltages, and circulation of one output phase current through the split capacitor bank. The application of this approach to induction machine drives is also discussed. It is concluded that the DC-voltage ripple effect on the B4 inverter output can be minimized by an adaptive SVM algorithm with the advantage of improving the response of the DC-link filter and the output quality of the inverter becoming high 相似文献
11.
Martins C.A. Roboam X. Meynard T.A. Carvalho A.S. 《Power Electronics, IEEE Transactions on》2002,17(2):286-297
A new strategy for direct torque control with imposed switching frequency (DiCoIF) is proposed. This strategy was specially designed to operate with a multicell (flying capacitors) inverter with any number of levels, which means it can also be used for standard two-level inverters. This approach combines the well known advantages of the multicell. inverter with those of a direct torque controlled (DTC) based strategy. It is shown that the multicell topology presents enough degrees of freedom to control both torque and flux with very low ripple and high dynamics on one hand, and to impose the switching frequency and the capacitors voltage balance on the other hand. Experimental and simulation results, obtained with a standard two-level inverter and with a four-level multicell inverter, are presented and discussed. Finally, a comparative analysis either with the classical DTC and field oriented techniques is carried out 相似文献
12.
A highly dynamic control scheme with very low torque ripple-direct self control (DSC) with torque hysteresis control-for very high-power medium-voltage induction motor drives fed by a double three-level inverter (D3LI) is presented. In this arrangement, two three-level inverters that are connected in parallel at their DC sides are feeding the open motor windings. The DSC, well known from two- and three-level inverters, is adapted to the D3LI and optimized for a minimum torque ripple. An 18-corner trajectory is chosen for the stator flux of the induction machine since it is approaching the ideal circle much better than the hexagon known from DSC for two-level inverters, without any detriment to the torque ripple. The machine and inverter control are explained and the proposed torque quality and dynamics are verified by measurements on a 180-kW laboratory drive. 相似文献
13.
In this paper, the use of a piezoelectric polymer material to measure the harmonics of electromagnetic torque produced by a permanent magnet synchronous machine is described. The advantages of the polymer include low cost, durability, and flexibility. In addition, wide-bandwidth sensors are relatively easy to design and couple to drive system hardware for harmonic evaluation or to use in feedback-based control. To illustrate the use of the polymer, the electrical and mechanical properties of three sensors are described. The results of time-domain simulation and hardware experiments are used to validate that the voltage obtained from the sensors is linearly related to the torque ripple produced by the machine. 相似文献
14.
The basic concept of direct torque control of induction machines is investigated in order to emphasize the effects produced by a given voltage vector on stator flux and torque variations. The low number of voltage vectors which can be applied to the machine using the basic DTC scheme may cause undesired torque and current ripple. An improvement of the drive performance can be obtained using a new DTC algorithm based on the application of the space vector modulation (SVM) for prefixed time intervals. In this way a sort of discrete space vector modulation (DSVM) is introduced. Numerical simulations and experimental tests have been carried out to validate the proposed method 相似文献
15.
Kuo-Kai Shyu Hsin-Jang Shieh 《Industrial Electronics, IEEE Transactions on》1995,42(6):572-578
In this paper, a variable structure current controller based on a space voltage vector PWM scheme is presented for induction motor drives. In this current controller design, only the current sensors are employed and we attempt to force the stator currents to be exactly equal to the reference currents rapidly. This proposed current controller, which is based on the space voltage vector PWM drive, exhibits several advantages in terms of reduced switching frequency, robustness to parameter variations, elimination of current/torque ripple, and improved performance in induction motor drive. It shows that the current control laws can be demonstrated in theory. Finally, simulation and experimentation results verify the proposed control scheme 相似文献
16.
17.
Output harmonic minimization in standard pulse width modulation (PWM) pattern generators is based on the assumption that the input DC bus voltage is ripple-free. However, in a practical converter system, a nonideal DC bus deteriorates the quality of the inverter output voltage by introducing undesirable low-order harmonics that may be difficult to filter. The existing compensation techniques often use additional and complex circuitry to eliminate the effect of this ripple on the output voltage. This paper presents an online PWM pattern generator that inherently takes into account the DC bus ripple and generates gating signals required to produce high-quality sinusoidal output voltages. The technique is based on integrating the output voltage at a constant frequency on a pulse-by-pulse basis to ensure a sinusoidal volt-sec (V/s) distribution, irrespective of the input DC bus. The principles of operation are explained, and design equations are derived. The features of the proposed PWM pattern generator are illustrated. Comparison of the output voltage waveforms of those standard sinusoidal PWM (SPWM) techniques illustrate, in particular, the effectiveness of the ripple-rejection mechanism. Experimental results obtained on a 3-kVA laboratory prototype confirm the feasibility and features of the proposed pattern generator 相似文献
18.
Enhanced inverter switching for fast response direct torque control[of induction motor drives] 总被引:1,自引:0,他引:1
In classical direct torque control (DTC), an inverter switching event can occur once in each control update period. Because the nature of the inverter switching event is unconstrained, it is essential to limit the inverter switching frequency, and hence the control update period, to ensure that under no circumstances is the allowable switching frequency of any individual power device exceeded. Consequently the switching capability of individual power devices is generally under-utilized, and the control scheme produces high levels of ripple in the motor current and torque. This paper describes a new strategy for device switching and voltage vector selection in DTC. The basis of the strategy is an increase in the control update frequency, while limiting the switching rate of each inverter leg. Although the rate at which device switching events may occur is unchanged, the higher control update frequency leads to higher resolution timing of switching events. The advantages of the strategy, demonstrated by experimental results on a 3 kW induction motor drive, are a significant reduction in the steady-state torque ripple as well as a faster transient response 相似文献
19.
Chih-Yi Huang Chao-Peng Wei Jung-Tai Yu Yeu-Jent Hu 《Industrial Electronics, IEEE Transactions on》2005,52(5):1364-1371
In this paper, an indirect field-oriented control (FOC) induction motor (IM) drive with instantaneous current and torque control is presented. This proposed control scheme employs hysteresis current and torque controllers to regulate the stator currents. The torque controller is proposed to serve the current controller so that full advantage of the zero voltage vector can be taken to reduce the switching frequency of the inverter. As a result, the actual stator currents can follow the current references as closely as possible, and the current ripple and torque ripple can be greatly decreased compared with the conventional adaptive pulsewidth modulation control method. To verify the feasibility of the proposed scheme, computer simulations and experiment results demonstrate that the proposed method can obtain a high-performance IM drive system. 相似文献
20.
Commutation torque ripple reduction in brushless DC motor drives using a single DC current sensor 总被引:17,自引:0,他引:17
Joong-Ho Song Ick Choy 《Power Electronics, IEEE Transactions on》2004,19(2):312-319
This paper presents a comprehensive study on reducing commutation torque ripples generated in brushless DC motor drives with only a single DC-link current sensor provided. In such drives, commutation torque ripple suppression techniques that are practically effective in low speed as well as high speed regions are scarcely found. The commutation compensation technique proposed here is based on a strategy that the current slopes of the incoming and the outgoing phases during the commutation interval can be equalized by a proper duty-ratio control. Being directly linked with deadbeat current control scheme, the proposed control method accomplishes suppression of the spikes and dips superimposed on the current and torque responses during the commutation intervals of the inverter. Effectiveness of the proposed control method is verified through simulations and experiments. 相似文献