Vector Selection Table Research Articles

TUNING OF PI SPEED CONTROLLER IN DIRECT TORQUE CONTROL OFDUAL STAR INDUCTION MOTOR BASED ON GENETIC ALGORITHMS AND NEURO-FUZZY SCHEMES

Thanks to the positive characteristics of the double stator machine (DSIM), its high reliability, and reduced rotor torque ripples, it has become among the most important multiphase machines included in industrial applications. This article aims to apply the two techniques of artificial intelligence represented by the adaptive neuro-fuzzy inference systems (ANFIS) and the genetic algorithm (GA) for direct torque control (DTC) of the DSIM to improve the performance of the machine. The ability to learn and the parallelism of operation characteristics made exploiting the GA to control the machine possible instead of using the proportional integral controller (PI). Fixed switching frequency obtained, given with the vector selection table and hysteresis, allowed the inclusion of the ANFIS technique in the DTC strategy. Two-level inverters are included to feed the DSIM. Several results prove that the two techniques applied, ANFIS and GA, improve the quality of the electromagnetic torque and flux and the dynamic responses of the DSIM.

Direct torque control of IM using PID controller

Direct torque control "DTC" technique is one of a high performance control system of an AC motor drive, which was proposed after the vector oriented control scheme during the resent 25 years. It has been developed rapidly for its concise system scheme, transient and dynamic performance. The DTC mechanism consists of voltage vector selection table, two hysteresis comparators and two estimators one for stator flux and another for electromagnetic torque. DTC is directly control torque and flux by using Voltage Source Inverter VSI, space vector and stator flux orientation and indirect speed regulated. A several control techniques can be used for improving the torque and flux performance.
 In this paper, the DTC with Proportional-Integral-Derivative (PID) controller used to improve the starting and dynamic performance of asynchronous motor AM, which gives good torque and flux response, best speed control and also minimize the unacceptable torque ripple. The mathematical model of DTC with PID controller of 3-phase induction motor IM are simulated under Matlab-Simulink. Therefore, the DTC based on PID controller has good performance of IM compared to classical DTC for starting, running state and also during change in load.

A Modified Double Vectors Model Predictive Torque Control of Permanent Magnet Synchronous Motor

Duty cycle model predictive torque control (Duty-MPTC) only uses zero vector as the second vector to form vector combinations, which restricts its torque control performance. This paper proposes a modified double vectors model predictive torque control (DVMPTC) by reasonably selecting active vector instead of zero vector. By analyzing the regulation of torque and flux of permanent magnet synchronous motor (PMSM), the torque and flux difference parameters are obtained, and then a second vector selection table is established to determine the best vector combination for torque ripple suppression. Based on the torque and flux difference parameters, the duty cycle calculation method is proposed to reduce the calculation burden of the control system. In order to verify the effectiveness of the proposed method, experiments with a 6-kW PMSM are carried out. Compared to the Duty-MPTC, the proposed DVMPTC method can significantly reduce the torque ripples with good dynamic performance and relatively low average switching frequency.

Study on the fuzzy proportional–integral–derivative direct torque control strategy without flux linkage observation for brushless direct current motors

Considering the difficulty in setting and observing the flux linkage in the existing direct torque control for the brushless direct current motor, which is the cumbersome torque calculation method in direct torque control systems without flux linkage observation, the torque observation, voltage vector selection, and speed loop were studied further in such systems. The fuzzy proportional–integral–derivative direct torque control strategy is presented without flux linkage observation. In terms of torque observation, the cumbersome counter electromotive force calculation method was abandoned, and observation was made combining the three-phase current and Hall signal. In terms of optimal choice of voltage vector, the voltage vector selection table was built using the voltage hysteresis output and Hall signal. In terms of rotation speed control, the adaptive fuzzy proportional–integral–derivative was used to replace the traditional proportional–integral–derivative for the proportional–integral–derivative parameter self-adjustment. A control system simulation model was set up in MATLAB/Simulink for simulation verification. A hardware experimental platform was set up using DSP2812 as the main control board for experimental verification. The research results show that the fuzzy proportional–integral–derivative direct torque control without flux linkage observation further increased the dynamic response rate of the motor speed and reduced the electromagnetic torque ripple amplitude; thus, it is more suitable for application in high-precision and high-stability systems.

Bus-Clamping-Based Direct Torque Control Strategy Dedicated to B6-Inverter Fed Symmetrical Two-Phase IM Drive

The paper deals with a novel DTC strategy dedicated to B6-inverter fed two-phase induction motor (2PIM) drives. It considers a bus-clamping-based approach in the synthesis of the vector selection table, leading to the “bus-clamping DTC” (BC-DTC). The study is initiated by a presentation of the B6-inverter fed 2PIM drive and a recall of the DTC background. Then, a special attention is paid to the design of the BC-DTC vector selection tables. For the sake of comparison, a conventional DTC strategy, inspired from the Takahashi one, is also considered. A simulation-based comparison of selected steady-state features is carried out. Then, a validation of the simulation results allied to an extension of the investigation is experimentally treated. The comparison is achieved by an investigation of the drive dynamic behavior under step- and ramp-shaped reversals of the reference speed. It is shown that the BC-DTC enables reductions of the switching frequency and of the torque ripple.

FPGA Implementation of a New DTC Strategy Dedicated to Delta Inverter-Fed BLDC Motor Drives

This paper presents the field programmable gate array (FPGA) implementation of an ameliorated direct torque control strategy (DTC-2) for a brushless DC motor (BLDCM) fed by a reduced delta inverter, called also three-switch three-phase inverter (TSTPI). In this work, a DTC-fed BLDCM drive is treated by considering two strategies. The first strategy (DTC-1) emulates the operation of the conventional inverter where the original DTC control is applied. Based on the DTC-1 strategy, high ripples of the electromagnetic torque are registered during the sector-to-sector commutations. These ripples are due to the application of unbalanced voltage vectors. To overcome these drawbacks, an ameliorated strategy (DTC-2) is proposed. This second strategy consists in decreasing the sudden transition between lower and upper voltage vectors by the synthesis of an appropriate vector selection table. The particularity of this table is based on the application of switching voltage vectors during a defined period of each commutation sector operation. In this paper, the two DTC strategies are developed, simulated and checked under the Xilinx system generator environment. Both strategies are translated into a hardware implementation using an FPGA device (Virtex 5). The hardware co-simulation results clearly validate the performances of the association BLDCM-TSTPI under the second ameliorated control strategy DTC-2.

A Torque Control Strategy for Torque Ripple Reduction of Brushless DC Motor With Nonideal Back Electromotive Force

This paper proposes a new torque control strategy to reduce torque ripple of brushless dc motor. All possible combinations of terminal voltages are obtained from different switching states of the inverter during normal conduction period and commutation period. Moreover, the expressions of torque variation rates, corresponding to different terminal voltages, are derived to analyze the sign and the magnitude of the torque variation rates. Based on this analysis, two switching tables with main vector (MV) and subsidiary vector (SV) in these two periods are established, respectively. Through the combined effect of MV and SV in each control cycle, the torque ripple caused by both nonideal back electromotive force and current commutation can be reduced effectively. Meanwhile, dynamic performance of torque and switching times are taken into account. Especially in the commutation period, a unified vector selection table is applied over the entire speed range without distinguishing high speed and low speed. Finally, the effectiveness of the proposed strategy is verified by experimental results.

Torque Ripple Suppression Method for BLDCM Drive Based on Four-Switch Three-Phase Inverter

A novel inverter fault-tolerant control scheme is proposed to drive brushless DC motor. A fault-tolerant inverter and its three fault-tolerant schemes (i.e., phase A fault-tolerant, phase B fault-tolerant, and phase C fault-tolerant) are analyzed. Eight voltage vectors are summarized and a voltage vector selection table is used in the control scheme to improve the midpoint current of the split capacitors. A stator flux observer is proposed. The observer can improve flux estimation, which does not require any speed adaptation mechanism and is immune to speed estimation error. Global stability of the flux observer is guaranteed by the Lyapunov stability analysis. A novel stator resistance estimator is incorporated into the sensorless drive to compensate for the effects of stator resistance variation. DC offset effects are mitigated by introducing an integral component in the observer gains. Finally, a control system based on the control scheme is established. Simulation and experiment results show that the method is correct and feasible.

DTC Scheme for a Four-Switch Inverter-Fed Induction Motor Emulating the Six-Switch Inverter Operation

This paper proposes a novel direct torque control (DTC) strategy for induction motor (IM) drives fed by a four-switch three-phase inverter (FSTPI). The introduced strategy is based on the emulation of the operation of the conventional six-switch three-phase inverter (SSTPI). This has been achieved thanks to a suitable combination of the four unbalanced voltage vectors intrinsically generated by the FSTPI, leading to the synthesis of the six balanced voltage vectors of the SSTPI. This approach has been adopted in the design of the vector selection table of the proposed DTC strategy which considers a subdivision of the Clarke plane into six sectors. Simulation results have revealed that, thanks to the proposed DTC strategy, FSTPI-fed IM drives exhibit interesting performance. These have been experimentally validated and compared to the ones yielded by the Takahashi and the basic DTC strategies dedicated to the SSTPI and to the FSTPI, respectively.

The Implementation of Permanent Magnet Synchronous Motor Direct Torque Control

In order to deeply understand the characteristics of the permanent magnet synchronous motor direct torque control method, its mathematical models were established in the two-phase stationary coordinate system, the two-phase synchronous rotating coordinate system, and x-y stator synchronous rotating coordinate system. The implementation process of direct torque control method in varied stator winding connection was analyzed in detail. In order to improve the speed and torque performance of the permanent magnet synchronous motor, the direct torque control block diagram and the space voltage vector selection table were given. Finally, the summary and outlook of reducing torque ripple in the permanent magnet synchronous motor direct torque control methods.

Six‐switch inverter emulation based DTC strategy dedicated to three‐switch inverter‐fed induction motor drives

Purpose – The aim of this paper is to propose a novel direct torque control (DTC) strategy for induction motor (IM) drives fed by three‐switch three‐phase inverter (TSTPI). The introduced strategy is based on the emulation of the operation of the conventional six‐switch three‐phase inverter (SSTPI).Design/methodology/approach – The proposed strategy has been achieved thanks to suitable combinations of the six unbalanced voltage vectors intrinsically generated by the TSTPI, leading to the synthesis of the six balanced voltage vectors of the SSTPI. This approach has been adopted in the design of the vector selection table of the proposed DTC strategy which considers a subdivision of the Clarke plane into six sectors.Findings – Simulation results have revealed that, thanks to the proposed DTC strategy, TSTPI fed IM drives exhibit interesting performance.Research limitations/implications – The results obtained by simulation should be validated by experiments.Originality/value – The drawbacks associated with t...

Investigation of the performance of a DTC strategy dedicated to the control of B4 fed induction motor drives

Purpose – This paper seeks to investigate the performance of a DTC strategy dedicated to the control of four‐switch three‐phase (B4) inverter fed induction motor drives. The major advantage of the B4 inverter is the reduced number of the involved power switches which opens up crucial cost benefits.Design/methodology/approach – The principle of operation of the B4 inverter fed induction motor drive is recalled in a first step. Then, the basis of the proposed DTC strategy is presented. Following this, the synthesis of the corresponding vector selection table is carried out considering a subdivision of the space vector plan into sixteen sectors.Findings – It has been found experimentally that the B4 inverter fed induction motor drive offers, under the proposed control strategy, interesting performance.Research limitations/implications – This work should be extended considering a comparison between the performance of B4 inverter fed induction motor drive under the proposed DTC strategy and those of the B6 inv...

Potentialities of DTC strategies in position regulation: application to robotics

Purpose – This paper is devoted to the investigation of the potentialities of induction motor DTC strategies in position control applications.Design/methodology/approach – A comparison study is carried out between two DTC strategies dedicated to position control applications such as robotic: the Takahashi DTC strategy where the induction motor is fed by a two‐level inverter and a new DTC strategy where the induction motor is fed by a three‐level inverter. Special attention is paid to the synthesis of the vector selection table of the second strategy in an attempt to guarantee a high dynamic with reduced ripple of the torque. The comparison study is achieved considering four performance criteria: phase current total harmonic distortion; inverter switching loss factor; quality factor; and inverter commutation frequency.Findings – It has been found that the introduced DTC strategy offers higher performance than the Takahashi one. Of particular interest are: the reduction of both torque ripple and commutation...

A DTC strategy dedicated to three‐switch three‐phase inverter‐fed induction motor drives

PurposeThe purpose of this paper is to describe the implementation of a direct torque control strategy dedicated to three‐switch three‐phase delta‐shaped inverter (TSTPI) fed induction motor drives as well as the comparison of its performance with those yielded by six‐switch three‐phase inverter (SSTPI) fed induction motor drives under the Takahashi DTC strategy.Design/methodology/approachReferring to the asymmetrical stator voltage vectors and in order to reach high dynamic with low ripple of the electromagnetic torque response, the design of the vector selection table should include virtual voltage vectors by the subdivision of each sector into two equal sub‐sectors.FindingsIt has been shown that the implementation of the proposed DTC strategy in TSTPI‐fed induction motor drives leads to higher transient behaviour and better steady‐state features than those exhibited by the Takahashi DTC strategy implemented in SSTPI‐fed induction motor drives.Research limitations/implicationsThe research should be extended to a comparison of the obtained simulation results with experimental measurements.Practical implicationsA 50 per cent reduction of cost and compactness associated with a 50 per cent increase of reliability makes the TSTPI an interesting candidate, especially in large‐scale production applications such as the automotive industry.Originality/valueThe paper proposes an approach to improve the cost‐effectiveness, the compactness and the reliability of TSTPI‐fed induction motor drives, which represents a crucial benefit in electric and hybrid propulsion systems.

DTC of an FSTPI‐fed induction motor drive with extended speed range

PurposeThe purpose of this paper is to analyze the performance of a new direct torque control (DTC) strategy dedicated to four‐switch three‐phase inverter (FSTPI)‐fed induction motor drives with extended speed range.Design/methodology/approachThe approach is based on the synthesis of a suitable vector selection table in order to reduce torque ripple. The performance analysis is carried out based on three criteria: the total harmonic distortion; the switching loss factor; and the quality factor.FindingsIt has been clearly shown that the introduced DTC strategy offers high performance during both transient and steady‐state operations of the FSTPI‐fed induction motor drive, which are almost the same as those yielded by the Takahashi DTC strategy implemented in the same motor fed by a conventional six‐switch three‐phase inverter (SSTPI).Research limitations/implicationsThe work should be extended by an experimental validation of the simulation results.Practical implicationsThe established results open up crucial benefits from the point of view of cost‐effectiveness and volume‐compactness of induction motor drives especially in large‐scale industries such as the automotive, where electric and hybrid propulsion systems are currently regarded as an interesting alternative to substitute or to assist the thermal propulsion systems.Originality/valueThe paper presents the implementation of a dedicated DTC strategy in FSTPI‐fed induction motor drives with extended speed range. The proposed DTC strategy offers interesting performance compared with that yielded by the Takahashi DTC strategy implemented in the same motor fed by an SSTPI.