The switching table works on the basis of the position of the rotor also. The voltage vector plane/space is divided into six sectors with an angle difference of 60 degrees. Each vector is spanned between two active vectors. The actual voltage space vector which rotates around the space may be present in any of the sectors. To **control** that actual voltage the closest voltage vectors are operated. The position of actual voltage vector can be sensed or can be estimated. There are some problems with this **conventional** DTC scheme like high **torque** ripple, current harmonics, drift in flux estimator, not working properly at very low speeds. To get rid of these problems and to achieve better performance different modification from the **conventional** DTC is applied, discrete space vector modulation is one of them. In space vector modulation technique, the switching period or the sampling time is divided into different sub-periods according to the expected voltage. The voltage vectors operate for a desired time period to obtain the voltage of inverter. The switching frequency is kept constant only the time for voltage vector operation is changed to get the desired voltage. In this case the **torque** response improved and also we get a high dynamic **control**.

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As an example, we can assume that V 1 is the VSI output voltage vector in a **conventional** DTC. From Figure 7 and table 2, it appears that voltage vectors (3, 5, 13, 15, 23 and 25) must be chosen. As it is illustrated in Figure.9, in each sector there are six voltage vectors. The two small vectors cannot be used for DTC method because of their change of sign in the middle of sector. If the input line-to-neutral lies in sector 1, the switching configurations which can be utilized are 3 and 5. The reason of not choosing the four other vector is that, vectors 15 and 23, are related to the small line to line voltage vectors in sector 1 ( V bc or V cb ) and cannot be used. Vectors 13 and 25 are in the opposite direction of V 1 and therefore cannot be used. Vector 3 and 5 impose two input current vectors with different directions, as shown in Figure 8. Thus, this degree of freedom can be used for controlling the input power factor. If the average value of sin( ) ψ needs to be decreased, voltage vector 5 should be chosen. On the contrary, if the average value of sin( ) ψ has to be increased, voltage vector 3 has to be applied.

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The PMSM drive system utilizing Field Oriented **Control** (FOC) has yielded satisfactory performance in both simulation and practical implementation, with minor variation in Speed and **Torque** as evident in the results. The DSP’s Instruction Set Architecture (ISA) and its integrated peripherals have simplified the development of software and hardware. The real time processing capability of the DSP allows for a highly reliable drive which is able to operate efficiently under a wide range of speeds, and also offers the potentiality of implementing more advanced or complex **control** schemes high-performance variable speed **drives**. Further improvements can be realized by incorporating Space Vector PWM (SVPWM) instead of the **conventional** Sinusoidal PWM (SPWM) [11]. It is also possible to implement soft computing techniques for the **control** algorithm although this would require sufficient knowledge to develop the hardware. It is up to the designer to choose the most optimal and viable **control** strategy to meet all his requirements.

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In this paper, the super-spiral sliding mode variable structure **control** is used to design the flux linkage and **torque** controller. The velocity controller is designed by using the sliding film **control** method based on the **approach** law. The system designed in this paper is compared with the traditional **direct** **torque** **control** system. It shows that the method adopted in this paper can effectively reduce the ripple of flux linkage and **torque**, and accelerate the speed response and an- ti-disturbance capability.

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Abstract: The main theme of this paper is to present novel controller, which is a genetic based fuzzy Logic controller, for interior **permanent** **magnet** **synchronous** **motor** **drives** with **direct** **torque** **control**. A radial basis function network has been used for online tuning of the genetic based fuzzy logic controller. Initially different operating conditions are obtained based on **motor** dynamics incorporating uncertainties. At each operating condition, a genetic algorithm is used to optimize fuzzy logic parameters in closed-loop **direct** **torque** **control** scheme. In other words, the genetic algorithm finds optimum input and output scaling factors and optimum number of membership functions. This optimization procedure is utilized to obtain the minimum speed deviation, minimum settling time, zero steady-state error. The **control** scheme has been verified by simulation tests with a prototype interior **permanent** **magnet** **synchronous** **motor**.

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In recent years PMSM have become a leading machine in the industrial applications because it has simple and rugged structure, high maintainability and economy, it is also robust and immune to heavy overloading, etc[1]. **Direct** **torque** **control** method is one of the newest **control** systems for PMSM based on vector **control** of electric motors [2]. This method was invented originally for induction **motor** (IM) by Takahashi[3] and Depenbrock [4] in 1986 and 1988 respectively, and then a lot of improvements over the proposed method have been made by other researchers for PMSM. The DTC of a PMSM **motor** involves the **direct** and independent **control** of the flux linkage and electromagnetic **torque**, by applying appropriate voltage switching vectors to the converter. **Direct** **Torque** **Control** describes the way to **control** **torque**, directly based on the electromagnetic state of the machine. DTC can be pertinent to asynchronous machines, **permanent** **magnet** machines etc. DTC is the first technology to **control** the **motor** variables of **torque** and flux [9]. Because **torque** and flux are **motor** parameters that are being directly controlled, there is no need for a modulator, as used in PWM **drives**, to **control** the frequency and voltage. A modified DTC scheme that utilizes space vector modulation (**SVM**)was reported in [10].

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ABSTRACT: The principle of vector **control** of electrical **drives** is based on the **control** of both the magnitude and the phase of each phase current and voltage. For as long as this type of **control** considers the three phase system as three independent systems, the **control** will remain analog and thus present several drawbacks. With high computational power silicon devices, it has been possible to realize precise digital vector **control** algorithms. The most common is the Field Orientated **Control**, which demonstrates the capability of performing **direct** **torque** **control** of handling system limitations and of achieving higher power conversion efficiency. The new families of DSPs enable cost-effective design of intelligent controllers for brushless motors which can fulfill enhanced operations, consisting of fewer system components, lower system cost and increased performances. This algorithm maintains efficiency over a wide range of speeds for a 24V, 4000 rpm **Permanent** **Magnet** **Synchronous** **Motor** and takes into consideration **torque** changes with transient phases by controlling the flux directly from the rotor coordinates.

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In DTC, the optimum voltage space vector for the entire switching period controls the **torque** and flux independently and the hysteresis band maintains the errors. Only one vector is applied for the entire sampling period, in the **conventional** method. So, for small errors, the upper or lower **torque** limit may be exceeded by the **motor** **torque**. Instead, the **torque** ripple can be reduced by using more than one vector within the sampling period. The insertion of zero vector precisely controls the slip frequency [8]. For a smaller hysteresis band, the frequency of operation of the PWM inverter could be very high. The width of the hysteresis band causes variation in the switching frequency. **Direct** **torque** **control** based on space vector modulation preserve DTC transient merits, furthermore, produce better quality steady state performance in a wide speed range. At each cycle period, **SVM** technique is used to obtain the reference voltage space vector to exactly compensate the flux and **torque** errors. The **torque** ripple of DTC-**SVM** in low speed can be significantly improved.

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This paper presents a feedback linearization **Direct** **Torque** **Control** (DTC) based on space vector modulation (**SVM**) which can be noticeably reduce electromagnetic **torque** and stator flux ripples that affect Induction **Motor** (IM) drive. In this paper IM drive that utilizes feedback linearization, Sliding-Mode **Control** (SMC) and a Fuzzy logic speed controller is discussed. A modern feedback linearization **approach** is proposed, which gives a decoupled **direct** IM model with two state variables: **torque** and stator flux magnitude. This obtained linear model is utilized to implement a DTC type controller that maintains all DTC advantages and suppresses its main drawback, the flux and **torque** ripple. Robust, quick, and ripple free **control** is accomplished by utilizing SMC with proportional component in the region surrounded by the sliding surface. SMC ensures robustness as in DTC, while the proportional component wipes out the **torque** and flux ripple. The **torque** time response is similar to traditional DTC and the proposed solution is able to adjust, profoundly tunable because of the P component. The sliding controller is compared with linear DTC scheme with and without feedback linearization. The **conventional** scheme uses proportional integral controller to achieve speed **control**. The fuzzy logic controller replaces the PI speed controller in the proposed scheme to ensure fast speed response in the drive. The extensive simulation results are presented and compared with the **conventional** scheme.

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The **conventional** DTC of PMSM has received considerable investigation for its advantage of quick change of **torque**, robustness and simplicity [1]. However, only six valid voltage vectors are available in **conventional** DTC which induce such problems as large **torque** ripple and variable switching frequency [2]. Hence the space vector modulation -**direct** **torque** **control** (**SVM**-DTC) was presented in which the along with hysteresis **control** of **torque** and stator flux hysteresis controller in **conventional** DTC, reference voltage calculator and space vector modulation unit are used. The **SVM**-DTC can provide constant switching frequency and more accurate Stator flux and **torque** **control**[1][3][5][6].

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full-order model, and the sliding mode flux observer with stator current observation error as feedback correction is constructed, which improves the robustness of the drive system. By introducing “active flux”, the structure of the observer is simplified, and the dependence on **motor** parameters is reduced. In addition, the drive system adopts a DTC strategy based on space vector modulation (**SVM**), which can effectively reduce the **torque** ripple while maintaining the characteristics of rapid dynamic response of **direct** **torque** **control**[8]. Simulation results are presented to validate that the proposed observer can obtain accurate stator flux and **torque** observations at full speed range, and the **motor** drive system has excellent **control** performance.

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The **direct** **torque** **control** theory has achieved great success in the **control** of **permanent** **magnet** **synchronous** **motor**. A **Direct** **Torque** **Control** (DTC) scheme of **Permanent** **Magnet** **Synchronous** **Motor** (PMSM) is presented. Based on in-depth analysis of PMSM mathematical model in abc frame and αβ frame are established and the operation principle of DTC-SVPWM system, the relationships between the **torque** and fundamental components. A novel space vector pulse width modulation (SVPWM) method which has a feature of low harmonic is proposed. The proposed method is adopted to implement the **direct** **torque** **control** (DTC) of a three-phase PMSM. A large number of simulation results show that the DTC System of PMSM has fast response and good dynamic performance. To aim at the **direct** **torque** **control** in PMSM **Drives**, this paper explained the theoretical basis of the **direct** **torque** **control** (DTC) for PMSM firstly, and then explained the difference between the applications of DTC-SVPWM and PMSM. Finally, the MATLAB/Simulink models were developed to examine the DTC- SVPWM for PMSM. The simulation results are presented in this paper.

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In this study, DTC process of the **permanent** **magnet** **synchronous** **motor** is explained and a simulation is constituted. It is concluded that DTC can be applied for the **permanent** **magnet** **synchronous** **motor** and is reliable in a wide speed range. Especially in applications where high dynamic performance is demanded DTC has a great advantage over other **control** methods due to its property of fast **torque** response. In order to increase the performance, **control** period should be selected as short as possible. When the sampling interval is selected smaller, it is possible to keep the bandwidth smaller and to **control** the stator magnetic flux more accurately. Also it is important for the sensitivity to keep the DC voltage in certain limits. As a improvement **approach**, a LP filter can be added to the simulation in order to eliminate the harmonics.

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The **Direct** **Torque** **Control** (DTC) strategy is a kind of high performance driving technology for AC motors, due to its simple structure and ability to achieve fast response of flux and **torque** has attracted growing interest in recent years. DTC-**SVM** with PI controller **Direct** **torque** **control** without hysteresis band can effectively reduce **torque** and flux ripple, DTC-**SVM** method can improve the system robustness and effectively improve the system dynamical performance. The DC-DC converter is used with wide range in electric vehicles to ensure the energy required for the propulsion system. The objective of this paper is to understand the lithium-ion battery compartment controlled by DC-DC converter, each of the wheels is controlled independently by using **direct** **torque** **control** based space vector modulation under several topology and Speed variations.

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now, there are many **control** methods have been studied to **control** the speed of PMSM such as adaptive **control**, PID **control**, intelligent **control** etc. Many **conventional** controls use Digital Signal Processor (DSP) in most studies. Unfortunately, DSP suffers from long time of development and exhaust resources of CPU . The novel technology of FPGA with great advantages of programmable hard-wired feature, fast computation ability, shorter design cycle, embedded processor and low power consumption and higher density on the other hand can provide an alternative solution for these issues and is more suitable for the implementation of Digital System than **conventional** DSPs. Vector **control** techniques have made possible the application of PMSM motors for high performance applications where traditionally only dc **drives** were applied. The vector **control** scheme enables the **control** of the PMSM in the same way as a separately excited DC **motor** operated with a current-regulated armature supply where then the **torque** is proportional to the product of armature current and the excitation flux. Similarly, **torque** **control** of the PMSM is achieved by controlling the **torque** current component and flux current component independently.

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B. Constant Frequency **Torque** Controller-Based of DTC A constant frequency **torque** controller for DTC of an induction **motor** drive has been proposed as in reference [3]- [5] to overcome the same problem described previously. The controller is capable of producing constant switching frequency in the drive operating condition and at the same time reduced for high **torque** ripples. In advance, the implementation of the controller is simple and the basic drive **control** structure is retained as in hysteresis DTC drive. A simple structure of **torque** controller has been introduced to replace the **conventional** three-level **torque** hysteresis comparator that used in **conventional** DTC scheme. A constant switching frequency is obtained by comparing a fixed frequency of triangular carrier signals with the compensated **torque** error signals from the PI controller. ‘Figure 6’ shows the structure of the constant frequency **torque** controller used in this strategy.

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In this paper, **direct** **torque** **control** (DTC) algorithms for double star **permanent** **magnet** **synchronous** machine alimented by two inverters is described. The double star **permanent** **magnet** **synchronous** machine has two sets of three-phase stator windings spatially shifted up by an angle 0 . The double star **permanent** **magnet** **synchronous** is used in areas of high power industrial applications such as traction and naval propulsion. Because constitute an advantageous choice compared to classical **synchronous** machine, because of the relatively low **torque** produced. This machine is controlled by tree level **direct** **torque** with speed regulator PI, replaced by the sliding mode regulator to improve the results obtained. The implementation of the DTC multi-level applied to a double star **permanent** **magnet** **synchronous** machine is validated with simulated results. In this paper a method for modeling and simulation of double star **permanent** **magnet** **synchronous** **motor** drive MATLAB/Simulink.

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The hysteresis band has to be set large enough to limit the inverter switching frequency below a certain level that is usually determined by thermal restriction of power devices. Since the hysteresis bands are set to cope with the worst case, the system performance is inevitably degraded in a certain operating range, especially in a low speed region. In **torque** hysteresis controller, an elapsing time to move from lower to upper limit, and vice versa can be changed according to operating condition.