Hybrid open-end multilevel six-phase machine drive system with reduced harmonic distortion

This paper provides a closed-form voltage harmonic analysis of Near-State Pulse Width Modulation (NSPWM) for a three-phase two-level voltage source inverter (VSI). NSPWM is a modulation technique that reduces common-mode voltage (CMV) magnitude up to 2/3 compared with conventional PWM. With the closed-form analysis, NSPWM’s impacts to CMV, common-mode current (CMI) and filter weight are compared with Space Vector PWM (SVPWM) and Discontinuous PWM (DPWM1[1]) in both the time and frequency domains. The comparison shows that NSPWM has lower CMV and CMI than SVPWM and DPWM1 over a wide frequency range. Experiments show that NSPWM reduces common-mode harmonics by up to 17 dB (7X), which leads to a 17% filter weight reduction. A system with 2-stage AC common-mode filter is tested with NSPWM and results meet DO-160G limit.

the Simulation model of DDPMSG 10KW grid Connected are developed using MATLAB 2013(a) and FAST Simulator. In addition to it SVPWM technique has been applied for 10KW grid connected model. Space vector pulse width modulation has been used for obtaining the output voltage with less distortion. An interface has also been developed between FAST and SIMULINK with MATLAB, enabling users to implement advanced turbine controls in SIMULINK convenient block diagram . The FAST subroutines have been linked with a MATLAB standard gateway subroutine in order to Generator torque control, nacelle yaw control, and pitch control modules can be designed in the SIMULINK environment. The fully controlled converter has been used to provide separate control for active and reactive powers. The simulation results in MATLAB SIMULINK 2013a showing the model have good dynamic and static performance. Index Terms: Direct drive permanent magnet synchronous generator, space vector pulse width modulation, fully controlled converters. I. Introduction The aim of this research is to model an autonomous control wind turbine driven permanent magnetic synchronous generator.(PMSG) which feeds alternating current (AC) power to the utility grid. Furthermore, this research also demonstrates the effects and the efficiency of PMSG wind turbine which is integrated by autonomous controllers. In order for well autonomous control, two voltage source inverters are used to control wind turbine connecting with the grid. The generator-side inverter is used to adjust the Synchronous generator as well as separating the generator from the grid when necessary. The grid-side inverter controls the power flow between the direct current (DC) bus and the AC side. Both of them are oriented control by space vector pulse width modulation (SVPWM) with back-to-back frequency inverter. Moreover, the proportional-integral (PI) controller is enhanced to control both of the of the converters and the pitch angle of the wind turbine. II. Inverters And The Pitch Angle Of The Wind Turbine According to the continuous development of wind power technology, the efficiency of inverter device is facing some tough issues and plays a vital role in the improvement of wind power generation system performance. They need to be enhanced by controller (3) to improve the efficiency and the reliability. Inside them, MPPT integrating with the back to back space vector Pulse width modulation (4) is the advantage of controller (3), which is used to measure the rotor speed and compare with the calculated optimal rotor speed. On the other hand, not only does the inverter take an advantage in efficiency control but also the pitch angle controller takes another important part of wind turbine. It is integrated to adjust the aerodynamic torque of the wind turbine when this study rates wind speed

Two-level three-phase voltage source inverter (VSI) with resistive-inductive load has been widely applied in the real life and production. Precise control and fast response are essential for the performance of two-level three-phase VSI with the resistive-inductive load. In this paper, a novel controller design which consists of discrete-time model predictive control (DMPC) based on Laguerre functions and space vector pulse width modulation (SVPWM) is proposed to satisfy these requirements. The inputs of the three-phase are transformed into stationary α-β coordinate for reducing calculation. In addition, the parameters of DMPC based on Laguerre functions are calculated during the offline period, which can reduce the burden of online calculation. With the voltage detection of resistive-inductive load and the current compensation, required reference voltage can be predicted. The required reference voltage is later applied to SVPWM to get the switch sequences. A modified DMPC based on Laguerre functions-SVPWM can achieve a very low total harmonic distortion of output current. Extensive simulation results demonstrate that the proposed approach has a fast dynamic response and perfect steady-state performance.

A modified space vector pulse width modulation (SVPWM) strategy based on vector space decomposition and its equivalent dual three-phase SVPWM realization are proposed in this paper, which is suitable for two-level six-phase voltage inverter fed asymmetrical dual stator induction machines (DSIMs). The DSIM is composed of two sets of symmetrical three-phase stator windings spatially shifted by 30 electrical degrees. The proposed SVPWM technique can reduce the torque ripple and suppress the harmonic currents flowing in stator windings. Above all, the equivalent relationship between the proposed SVPWM technique and the dual three-phase SVPWM technique has been demonstrated, which allows easy implementation for digital signal processor (DSP). Simulation and experimental results, carried out separately on a simulation system and a 3.0 kW DSIM prototype test bench, are presented and discussed.

The space vector pulsewidth modulation (SVPWM) techniques enhance the performance of multilevel multiphase inverters. With multilevel (three-phase) inverters and with (two-level) multiphase inverters, it is widely accepted that the typical SVPWM strategies have an equivalent carrier-based pulsewidth modulation (CBPWM) counterpart, which produces identical results. However, the conclusions reached in the articles that show these cannot be applied, nor even extended, to SVPWM techniques with more than two levels and three phases. This article shows that the most widely accepted multilevel multiphase SVPWM techniques have a fully equivalent CBPWM counterpart, which consists of a phase disposition pulsewidth modulation with an appropriate zero-sequence injection scheme. Closed-form expressions to calculate the zero sequences are provided. The proposed modulation techniques are simulated and then implemented in a field-programmable gate array, showing that the equivalent CBPWM techniques produce identical results as the original SVPWM ones, but with a significant reduction of hardware requirements. The proposed methodology can be generalized to other multilevel multiphase SVPWM techniques.

The sideband current harmonic components would inhere in permanent-magnet (PM) synchronous machine systems driven by a voltage-source inverter with space vector pulsewidth modulation (SVPWM). However, these harmonics could potentially deteriorate the overall performance of the drive system by increasing the resultant losses, torque ripple, and electromagnetic and acoustic noises. The main sideband harmonic voltages and currents in PM synchronous machine driven by voltage-source inverter with SVPWM technique, are analytically derived and expressed in both stator and rotor frame. The experimental results are carried out to underpin the validity of the analytical model. The analytical model could be employed to assess the influencing factors of current harmonics. In addition, it offers insightful guidance to the effective reductions of harmonic losses, torque ripples, and electromagnetic noises.

A review of the sinusoidal pulse-width-modulation (SPWM) and the space vector PWM (SVPWM) techniques for AC motor drives is reported, taking into account secondary effects such as the digital quantization, the dead time, and the dwell time. Simulation results show close agreement with the measured harmonics caused by an experimental digital-signal-processor (DSP)-controlled inverter operating in the same conditions. The SPWM waveforms have cleaner spectra than the SVPWM, but the quality factors are higher with respect to the SVPWM, having the same peak value of the voltage reference. As a consequence, if the switching frequency is high enough, the losses due to the harmonics can be almost neglected, and the SVPWM seems to be the best solution in terms of output voltage, harmonic losses, and number of switchings per cycle.

This paper evaluates several important pulse-width modulation (PWM) methods developed to reduce the common-mode voltage (CMV) or DC-link capacitor current (DCC) of two-level three-phase voltage source inverter (VSI) in motor drive applications. In addition, a PWM selection criterion is introduced to properly utilize these advanced PWM methods in the VSI system. In the motor drive systems, the high CMV generates the large common-mode current, which may cause electromagnetic emissions and motor damages. Also, the large DCC may have an adverse effect on the life expectancy and increase the volume of DC-link capacitor. Therefore, reducing the CMV and DCC is required in modern VSI systems. So far, various PWM methods have been studied to reduce these CMV and DCC. However, they need to be fairly compared and evaluated together under the same condition to provide information so that power electronics engineers can select the appropriate PWM method when designing their motor drive systems. In this paper, the principle of these PWM methods is reviewed and their performance is analytically evaluated. Then, the PWM selection criterion is described based on the comprehensive evaluation studies. Lastly, the simulation and experimental results with an interior permanent magnet synchronous motor (IPMSM) drive system are presented to validate the presented PWM selection criterion.

Four-dimensional 24-sector space vector pulse width modulation (SVPWM) techniques result in good harmonic performance in split-phase induction motor (SPIM) drives, but have high computational burden. Per-phase analysis of two such SVPWM techniques is reported in this paper. Though the switching sequences used and the harmonic spectra are different for the two techniques, the waveshape of average pole voltage is identical for both PWM techniques at a given operating point. Consequently, common mode voltage (CMV) of a given inverter is also identical for the two methods. Analysis of CMV gives a method to derive the zero-sequence signal for each inverter from its three-phase sinusoidal modulating signals. Addition of the zero-sequence signal, thus derived, to the sinusoidal modulating signals results in a computationally-efficient method for generating the equivalent modulating signal. Equivalent carrier waves are derived for the two PWM techniques based on the corresponding switching sequences employed. The resulting carrier-based implementation reduces the computation time from $52.9\mu \mathrm{s}$ to $26.7\mu \mathrm{s}$ on a TMS320F28377S DSP platform. Simulation and experimental results of stator current waveform and total harmonic distortion (THD) in stator current from a 6-kW, 200-V, 50-Hz SPIM drive are presented for the two proposed methods and an existing carrier-based PWM.

This article presents an enhanced space vector pulse width modulation (SVPWM) strategy based on vector space decomposition (VSD) for the dual three-phase machines fed by two dc-source voltage source inverters (VSIs). Compared with existing methods that only account for balanced dc-link voltages, the proposed method considers unbalanced dc-link voltages in both the α-β and z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> -z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> planes. Two categories of medium voltage vectors are first defined in this article. An enhanced 12-sector SVPWM strategy that toggles two categories of medium voltage vectors in each fixed 30° sector is proposed. Moreover, the performance of the proposed method, including the modulation depth, the range of the dc-link voltage ratio, and the toggling point of the medium vector is analyzed. The proposed method can reduce the computational burden of the complicated sector classifications and it easily chooses suitable vectors to track the reference voltage with changes in the dc-link voltage ratio. The experimental results of the proposed SVPWM techniques are verified in a dual three-phase permanent magnet synchronous machine (PMSM) fed by two dc-source VSIs.

In an open-end winding drive topology two voltage source inverters (VSIs) are connected to the two separate sets of terminals of the stator winding. The most frequently investigated topology uses two two-level VSIs that require two isolated dc-bus supplies. The other alternative is to use a single dc-bus voltage source, which then requires elimination of the common-mode voltage to avoid the zero-sequence current flow. This paper investigates a seven-phase open-end winding topology, with the two two-level VSIs fed from a single dc supply. Hence, in addition to zeroing on average voltages in all non-flux/torque producing planes, it is necessary to restrict the zero-sequence current flow, which would be caused by the common-mode part of the phase voltages. The switching states providing zero common-mode voltage (CMV) are indentified and the corresponding space vectors determined. A correlation between these space vectors and the space vectors that are used in standard seven-phase two-level VSI modulation is investigated and a simple carrier-based PWM is proposed, based on this correlation. The method is implemented in simulations and experiments and the results are presented to verify the concept.

Switching common-mode voltage (CMV) generated by the pulse width modulation (PWM) of the inverter causes common-mode currents, which lead to motor bearing failures and electromagnetic interference problems in multiphase drives. Such switching CMV can be reduced by taking advantage of the switching states of multilevel multiphase inverters that produce zero CMV. Specific space-vector PWM (SVPWM) techniques with CMV elimination, which only use zero CMV states, have been proposed for three-level five-phase drives, and for open-end winding five-, six-, and seven-phase drives, but such methods cannot be extended to a higher number of levels or phases. This paper presents a general (for any number of levels and phases) SVPMW with CMV elimination. The proposed technique can be applied to most multilevel topologies, has low computational complexity and is suitable for low-cost hardware implementations. The new algorithm is implemented in a low-cost field-programmable gate array and it is successfully tested in the laboratory using a five-level five-phase motor drive.

PWM inverters used in motor drives produce high frequency Common Mode Voltages (CMV) which results in Common Mode (CM) currents and bearing currents due to parasitic capacitances. These currents cause abominable effects in electronics devices and develop voltage at motor shaft. When voltage exceeds dielectric breakdown voltage of lubricant film, it develops a huge bearing current which can damage bearings in very short interval. This paper emphasis on mitigation of CM currents and bearing currents by minimizing CMV produced by inverter-motor system based on selection and refinement of PWM algorithm without any additional hardware change. Multilevel inverters are apt for industrial applications due to low voltage distortion and less stress on switching devices than conventional two level inverter. To Investigate the effects on CMV, CM currents, bearing currents and motor shaft voltage, a high frequency Induction Motor (IM) model was chosen and analysis was done with different PWM techniques. The present work focused on three level Diode Clamped MultiLevel Inverter (DCMLI) and proposed new Space vector Pulse width Modulation (SVPWM) by choosing reductant CMV vectors in combination with sequence of changing one state in phase during switching transition. The proposed SVPWM technique shows the effectiness to reduce CMV as well as Electro-Magnetic Interference (EMI) and validated using MATLAB simulations.

Because of the increasing demand for non-conventional energy sources, photovoltaic system integration into the electrical grid is becoming more crucial. It is advised to employ a double-stage grid-connected PV system. This can be employed with the main parts boost converter, which helps to boost the DC output from the PV channels. And next one is the space vector pulse width modulation (SVPWM) inverter which can provide better harmonic performance and higher efficiency compared to traditional PWM methods. The SVPWM technique is employed to modulate the inverter output, generating a sinusoidal AC waveform that matches the grid frequency and voltage. By adjusting the pulse width to achieve effective and trustworthy grid integration. To maximize power extraction takes place by using maximum power point tracking (MPPT). The SVPWM inverter is crucial in converting DC power to AC power and enabling grid connection. Utilizing SVPWM allows exact control of voltage magnitude, frequency, and phase angle to provide high-quality sinusoidal AC output voltage. The power quality of the electricity pumped into the grid is improved by this precise management, which also ensures adherence to grid standards and reduces harmonic interference.

This paper presents the scalar control as well as direct torque control for speed control of induction motor. The scalar control is an easy to implement but it gives poor dynamic response. In addition to the scalar control the space vector pulse width modulation (SVPWM) is used for effective utilization of the dc-link voltage i.e. SVPWM is having the good voltage regulation and reduces the considerable harmonics in voltage as well as current of the inverter. The dynamic response of the induction motor is improved using direct torque control with SVPWM technique. The performance of induction motor with scalar control and direct torque control is simulated in the Matlab environment and compared their response under similar operating conditions. The dynamic performance, the speed regulation, THD in the current, and the torque distortion of induction motor are effectively improved with direct torque control (i.e. lesser transient time) even while applying the load in comparison to scalar control.