A Variable-Speed, Sensorless, Induction Motor Drive Using DC Link Measurements

A Variable-Speed, Sensorless, Induction Motor Drive

Using DC Link Measurements

ABSTRACT:

This paper presents a new control strategy for three-phase induction motor which includes independent speed & torque control loops and the current regulation thereby overcoming the limitation (i.e. sluggish response) of volts per hertz controlled industrial drives. For close-loop control, the feedback signals including the rotor speed, flux and torque are not measured directly but are estimated by means of an algorithm. The inputs to this algorithm are the reconstructed waveforms of stator currents and voltages obtained from the dc link and not measured directly on stator side. The proposed drive thus requires only one sensor in the dc link to implement the close-loop speed and torque control of a three-phase induction motor. The simulation results on a 2.2 kW induction motor drive in Matlab/Simulink software show fast dynamic response and good agreement between the actual values and the estimated values of torque and speed. Replacement of the open-loop control strategy of existing v/f drive by the proposed close-loop strategy appears to be possible without requiring any additional power components and sensors.

KEYWORDS:

1. Speed-sensorless

2. Estimation

3. Dc link

4. Band-pass filter

5. Reconstruction

6.Three-phase induction motor

7.Space-vector.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

                                              Figure 1. Block diagram of the proposed scheme.

CONCLUSION:

In this paper, a new control strategy for induction motor drive is proposed. The drive is operated under torque control with an outer speed loop and is very similar to open-loop v/f drive in terms of power components and sensors required. Due to the inclusion of torque control loop, the drive response is fast and stable. Simulation results confirm the effectiveness of the proposed scheme. The technique uses only dc link voltage and dc link current measurements to generate the estimates of the dc link voltage is assumed as constant, only one current sensor in the dc link is sufficient to give the estimates of all required feedback variables. Moreover, the same current sensor that is already available in the dc link of an open-loop v/f drive for protection purpose can be used. Thus the open loop control strategy in an existing v/f drive can be replaced by the proposed close-loop control strategy without requiring any additional power components or the physical sensors. The proposed strategy appears to be a good compromise between the high-cost, high-performance field-oriented drives and the low-cost, low-performance v/f drives. Practical implementation of the proposed scheme on a 16 bits floating point arithmetic Texas Instrument TMS320C31 processor are the subject of future follow-up research work.

REFERENCES:

[1] B. K. Bose, Power Electronics and Motor Drives, Delhi, India, Pearson Education, Inc., 2003.

[2] M. Rodic and K. Jezernik, “Speed-sensorless sliding-mode torque control of induction motor,” IEEE Trans. Ind. Electron., vol. 49, no. 1, pp. 87-95, Feb. 2002.

[3] L. Harnefors, M. Jansson, R. Ottersten, and K. Pietilainen, “Unified sensorless vector control of synchronous and induction motors,” IEEE Trans. Ind. Electron., vol. 50, no. 1, pp. 153-160, Feb. 2003.

A 24-Pulse AC–DC Converter Employing a Pulse Doubling Technique for Vector-Controlled Induction Motor Drives

A 24-Pulse AC–DC Converter Employing a Pulse Doubling Technique for Vector-Controlled Induction Motor Drives

ABSTRACT:

This paper dealswith various multipulse AC–DC converters for improving the power quality in vector-controlled induc-tion motor drives (VCIMDs) at the point of common coupling. These multipulse AC–DC converters are realized using a reduced rating autotransformer. Moreover, DC ripple reinjection is used to double the rectification pulses resulting in an effective harmonic mitigation. The proposed AC–DC converter is able to eliminate up to 21st harmonics in the supply current. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed AC–DC converter. A set of power quality indices on input AC mains and on the DC bus for a VCIMD fed from different AC–DC converters is also given to compare their performance.

KEYWORDS:

1. Autotransformer

2. Multipulse AC–DC converter

3. DC ripple reinjection

4. Pulse doubling

5. VCIMD.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1: MATLAB block diagram of proposed ac-dc converter fed VCIMD (Topology ‘D’).

Figure 2: The proposed 24-pulse ac-dc converter fed VCIMD (Topology C).

CONCLUSION:

Reducedratingautotransformer-based12-and24-pulse AC–DC converters have been designed, modelled and compared with a six-pulse AC–DC converter feeding VCIMD. DC ripple reinjection technique for pulse dou-bling has been used for harmonic reduction in VCIMD. The pulse doubling technique needs only two additional diodes along with a suitably tapped inductor. The pro-posed AC–DC converter has resulted in a reduction in the rating of the magnetics, leading to the saving in the overall cost of the drive. The proposed AC–DC converter is able to achieve close to unity PF along with a good DC link voltage regulation in the wide operating range of the drive. The proposed AC–DC converter has demonstrated its capability in improving various power quality indices at the AC mains in terms of THD of the supply current, THD of the supply voltage, PF and CF. It can easily replace the existing six-pulse converters without much alteration in the existing system layout and equipments.

REFERENCES:

1. B.K. Bose, ‘Recent advances in power electronics’,IEEETrans.onPower Electronics, Vol. 7, No. 1, Jan. 1992, pp. 2-16.

2. P. Vas, Sensorless vector and direct torque control, Oxford University Press, 1998.

3. IEEE Guide for harmonic control and reactive compensation of Static Power Converters, IEEE Std. 519-1992.

4. Hahn Jaehong, Kang Moonshik, P.N. Enjeti & I.J. Pitel, ‘Analysis and design of harmonic subtracters for three phase rectifier equipment to meet harmonic compliance’, Proc.IEEE, APEC’00, Feb. 2000, Vol. 1, pp. 211-217.

5. D.A.Paice, Power Electronic Converter Harmonics: Multipulse Methods for Clean Power, New York, IEEE Press 1996.

Single-Stage Power-Factor-Correction Circuit with Flyback Converter to Drive LEDs for Lighting Applications

Single-Stage Power-Factor-Correction Circuit with Flyback

Converter to Drive LEDs for Lighting Applications

ABSTRACT:

White light emitting diode (LED) with high brightness has attracted a lot of attention from both industry and academia for its high efficiency, ease to drive, environmental friendliness, and long lifespan. They become possible applications to replace the incandescent bulbs and fluorescent lamps in residential, industrial and commercial lighting. The realization of this new lighting source requires both tight LED voltage regulation and high power factor as well. This paper proposed a single-stage flyback converter for the LED lighting applications and input power factor correction. A type-II compensator has been inserted in the voltage loop providing sufficient bandwidth and stable phase margin. The flyback converter is controlled with voltage mode pulse width modulation (PWM) and run in discontinuous conduction mode (DCM) so that the inductor current follows the rectified input voltage, resulting in high power factor. A prototype topology of closed-loop, single stage flyback converter for LED driver circuit designed for an 18W LED lighting source is constructed and tested to verify the theoretical predictions. The measured performance of the LED lighting fixture can achieve a high power factor greater than 0.998 and a low total harmonic distortion less than 5.0%. Experimental results show the functionality of the overall system and prove it to be an effective solution for the new lighting applications.

KEYWORDS:

1. Light emitting diode

2. Flyback converter

3. Power factor

4. Total harmonic distortion.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of closed-loop driver circuit for LEDs lighting applications

CIRCUIT DIAGRAM:

Fig. 2. Single-stage power-factor-correction circuit with flyback converter for LEDs driver circuit

CONCLUSION:

A single-stage power-factor-correction circuit with flyback converter to drive LEDs for lighting applications has been presented in this paper. The flyback converter is operated in discontinuous conduction mode and at constant frequency providing an input power factor high enough to satisfy present standard requirements. The operation of the proposed feedback controller for PFC circuit has also been investigated in detail in this paper. In comparison with the other driver topology for high-power-factor LEDs lighting applications, the proposed topology presents a significant reduction of cost. A prototype of the proposed PFC circuit using type-II compensator for a LED lighting system has been successfully implemented. Experimental results have shown that fast dynamic response, good output voltage regulation, low harmonic distortion, and almost unity PF as well as very low THD can be achieved with the proposed single-stage flyback converter and control scheme. The proposed topology works as a good solution to implement low-cost, single-stage, high power- factor driver circuit with flyback converter using type- II compensator to drive LEDs for lighting applications.

REFERENCES:

[1] J. J. Sammarco. M. A. Reyes, J. R. Bartels, and Sean Gallagher, "Evaluation of Peripheral Visual Performance When Using Incandescent and LED Miner Cap Lamps," IEEE Transactions on Industry Applications, vol. 45, no. 6, pp. 1923-1929, November/December 2009.

[2] John L. Giuliani, George M. Petrov, Robert E. Pechacek, and Robert A. Meger, "Plasma Study of a Moly–Oxide–Argon Discharge Bulb," IEEE Transactions on Plasma Science, vol. 31, no. 4, pp. 564-571, August 2003.

[3] J. Cunill-Solà, and M.l Salichs, "Study and Characterization of Waveforms From Low-Watt (<25 W) Compact Fluorescent Lamps With Electronic Ballasts," IEEE Transactions on Power Delivery, vol. 22, no. 4, pp. 2305-2311, October 2007.

[4] Y. C. Chuang, C. S. Moo, H. W. Chen, and T. F. Lin, "A Novel Single- Stage High-Power-Factor Electronic Ballast with Boost Topology for Multiple Fluorescent Lamps," IEEE Transactions on Industry Applications, vol. 45, no. 1, pp. 323-331, January/February 2009.

Design of a Hybrid PID plus Fuzzy Controller for Speed Control of Induction Motors

ABSTRACT:

In this paper, a Ziegler-Nichols (Z-N) based PID plus fuzzy logic control (FLC) scheme is proposed for speed control of a direct field-oriented induction motor (DFOIM). The Z-N PID is adopted because its parameter values can be chosen using a simple and useful rule of thumb. The FLC is connected to the PID controller for enhancing robust performance in both dynamic transient and steady-state periods. The FLC is developed based on the output of the PID controller, and the output of the FLC is the torque command of the DFCIM. The complete closed-loop speed control scheme is implemented for the laboratory 0.14-hp squirrel-cage induction motor. Simulation results demonstrate that the proposed Z-N PID+FLC scheme can lead to desirable robust speed tracking performance under load torque disturbances.

KEYWORDS:

1.      Speed control

2.       Hybrid PID plus fuzzy controller

3.      Induction motor

4.       Ziegler-Nichols method

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1.The block diagram of speed control of a DFOIM

CONCLUSION:

In this paper, a novel hybrid modified Z-N PID+FLC-based speed control of a DFOIM has been presented. The proposed controller has exhibited the combined advantages of a PID controller and a FLC. Specifically, it can improve the stability, the transient response and load disturbance rejection of speed control of a DFOIM. The complete DFOIM drive incorporating the proposed controller has been implemented in real time using a MRC-6810 AD/DA servo control card for the Nikki Denso NA21-3F 0.14Hp induction motor. The fuzzy logic and only with three membership functions are used for each input and output for low computational burden, which can achieve satisfactory results. Simulation and experiment results have illustrated that the proposed controller scheme has a good and robust tracking performance. As suggested in [15] that a modified Z-N PID can perform better than a Z-N PID, our future effort will focus on how to further improve the performance of the proposed controller herein by incorporating a modified Z-N PID.

REFERENCES:

[1]F. Blaschke, “The principle of field orientation as applied to the new transvektor closed-loop control system for rotating-field machines,” Siemens Review, Vol. 39, No. 5, pp.217-220, 1972.

[2]Y. F. Tang and L. Xu, “Fuzzy logic application for intelligent control of a variable speed drive,” IEEE Trans. Energy Conversion, Vol. 9, No. 4, Dec. 1994.

[3]Z. Zhang, et al., ‘‘Sensorless direct field-oriented control of three-phase induction motors based on ‘‘sliding mode’’ for washing- machine drive applications,’’ IEEE Trans. Industry Applications, Vol. 42, No. 3, May/June. 2006.

[4]I. Miki, et al. “Vector control of induction motor with fuzzy PI controller,” IEEE Conf., IAS Annu. Meeting 1991, Vol. 1, pp.341-346