FPGA Implementation of a General Space Vector Approach on a 6-Leg Voltage Source Inverter

A general algorithm of a Space Vector approach is implemented on a 6-leg VSI controlling a PM synchronous machine with three independent phases. In this last case, the necessity of controlling the zero-sequence current motivates the choice of a special family of vectors, different of this one used in Pulse Width Modulation (PWM) intersective strategy and in common Space Vector PWM (SVPWM). To preserve the parallelism of the algorithm and fulfill the execution time constraints, the implementation is made on a Field Programmable Gate Array (FPGA). Comparisons with more classical 2-level and 3-level PWM are provided.Fui8 within the SOFRACI projec

Influx of pwm-modulation upon torque harmonics of induction machines

Influx of pwm-modulation upon torque harmonics of induction machines

Rearranged SVPWM Algorithm for Neutral Point Clamped 3-Level Inverter Encouraged DTC-IM Drive

In this paper, an improved space vector beat width tweak (SVPWM) strategy has been created for three stage three-level voltage source inverter bolstered to direct torque controlled (DTC) actuation engine drive. The space vector outline of three-level inverter is streamlined into two-level inverter. So the choice of exchanging arrangements is done as traditional two-level SVPWM system. Where in ordinary direct torque control (CDTC), the stator flux and torque are straightforwardly controlled by the determination of ideal exchanging modes. The choice is made to limit the flux and torque slips in comparing hysteresis groups. Notwithstanding its quick torque reaction, it has more flux, torque and current swells in consistent state. To beat the swells in relentless state, a space vector based heartbeat width tweak (SVPWM) technique is proposed in this paper. The proposed SVPWM system lessens the computational weight and decreases the aggregate consonant contortion contrasted and 2-level one and the ordinary one too. To fortify the voice reproduction is completed and the relating results are presented. Keywords: SVPWM, DT

A new closed loop speed control strategy for a vector controlled three- phase induction motor drive

This paper presents a completely mathematical equations based model on control of torque and speed of a three-phase indirect vector controlled VSI fed cage induction motor drive that is controlled through the space vector modulated method. This enables a wide range of acceptability of the model for various values of load and for various types and ratings of induction motors. The uniqueness of the model lies in the fact that the deviations in the torque and speed on sudden application of reference step change in speed values are minimum i.e. when any sudden change in the speed reference is desired, the speed and torque waveforms reveal that the time taken in coming back to their final steady state values is very less and the motor overcomes the perturbation with negligible transients. The same is verified through the simulated results

A discussion about a start-up procedure of a doubly-fed induction generator system

The present work proposes a start-up procedure for a doubly-fed induction generator (DFIG) driven by a wind turbine. In the DFIG topology the stator is connected direct to the grid while the rotor is connected to a back-to-back converter. This structure requires some care during grid synchronization to avoid undesired overloads. The main goal of a start-up procedure is to reduce the stresses on the electrical and mechanical components during synchronization. In this work, it is achieved by equalization among the induced stator voltage, the voltage over the filter capacitor and the grid voltage. A phase-locked-loop (PLL) computes the grid voltage phase displacement required for the system control orientation and synchronization procedures. Previous to the starting-up, the output currents set-points of the grid-side converter and rotor-side converter are computed in order to produce the same grid voltage over the filter capacitors and on the stator terminals. The whole procedure is summarized in seven different steps: turbine acceleration by the pitch control, DC-link pre-charge; initialization of the filter current controllers; filter synchronization; DC-Link voltage adjust; rotor current controllers' initialization and stator synchronization. The proposed start-up procedure was tested in a 4 kW test bench and the description of each step as well as simulation and experimental results are presented throughout the paper.reviewe

Vectorial formalism for analysis and design of polyphase synchronous machines

A vectorial formalism for analysis and design of polyphase synchronous machines without reluctance and saturation effects is described. We prove the equivalence of such a machine with a set of magnetically independent machines, which are electrically and mechanically coupled. Specific problems of polyphase machines can thus be favorably analyzed with this concept. Rules of conception and constraints on electric supply can be deduced. Moreover the vectorial approach, which generalizes the complex phasor method, can also be used to control n-leg Voltage Source Inverters. This methodology is applied to 3-phase and 6- phase synchronous machines

Space Vector Based Dual Zero-Vector Random Centered Distribution Pwm Algorithm for Direct Torque Control of Induction Motor Drive For Reduced Acoustical Noise

The direct torque control (DTC) technique has been recognized as the viable solution to achieve precise and quick torque response but it suffers from few drawbacks such as high ripple in torque, flux and stator current resulting in increased vibrations and acoustic noise. The conventional SVPWM algorithm gives good performance for control of induction motor drive, but it also produces considerable acoustical noise resulting in increased total harmonics distortion. The deterministic pulse width-modulation (PWM) method adopted in induction-motor drives causes Acoustical noise due to the switching frequency. This paper presents a novel dual zero-vector random centered distribution PWM algorithm for direct torque controlled induction motor drive. The proposed PWM algorithm uses two zero voltage vectors. When the operating modulation index is less than the critical modulation index, the proposed PWM algorithm uses V0 (000) as zero voltage vector. Otherwise, when the operating modulation index is greater than the critical modulation index, the proposed PWM algorithm uses V7 (111) as zero voltage vector. To verify the proposed PWM algorithm, a numerical simulation studies have been carried out and results are presented and compared with classical SVPWM algorithm. The simulation results confirm the effectiveness of the proposed DZRCDPWM algorithm for the considered drive. Key words: DTC, DZRCDPWM, RPWM, SVPWM, Acoustic noise

Park Vector Based Sliding Mode Control of UPS With Unbalanced and Nonlinear Load

In this paper an inverter is taken as a member of Variable Structure System (VSS). A new Park vector based variable structure control (VSC) method is proposed. A modified definition of the Park vector is introduced to handle the effect of zero phase-sequence component caused by an asymmetrical load. The design of a sliding mode controller consists of two main steps. Firstly, the design of the sliding surface, secondly, the design of the control which holds the system trajectory on the sliding surface. A complex sliding surface is proposed. The inverter is switched in such a way that the system trajectory gets as close to the sliding surface as possible. This paper focuses on the switching rule. Experimental results of a 100 KVA inverter are presented

The Essential Role and the Continuous Evolution of Modulation Techniques for Voltage-Source Inverters in the Past, Present, and Future Power Electronics

The cost reduction of power-electronic devices, the increase in their reliability, efficiency, and power capability, and lower development times, together with more demanding application requirements, has driven the development of several new inverter topologies recently introduced in the industry, particularly medium-voltage converters. New more complex inverter topologies and new application fields come along with additional control challenges, such as voltage imbalances, power-quality issues, higher efficiency needs, and fault-tolerant operation, which necessarily requires the parallel development of modulation schemes. Therefore, recently, there have been significant advances in the field of modulation of dc/ac converters, which conceptually has been dominated during the last several decades almost exclusively by classic pulse-width modulation (PWM) methods. This paper aims to concentrate and discuss the latest developments on this exciting technology, to provide insight on where the state-of-the-art stands today, and analyze the trends and challenges driving its future