Space Vector PWM Method Research Articles

Control and modulation methods of voltage source converter

Control and modulation methods of voltage source converterControl and modulation methods of Voltage Source Converter (VSC) have been presented in the paper. Model of VSC with three value transistor branch state function is introduced to describe operation of VSC. Predictive-corrective control method of VSC system is presented. Two variants of Space Vector PWM methods for VSC system are developed. Algorithm of cancelation of negative influence of dead time on the AC voltages is implemented in the proposed modulation methods. Correctness of introduced method is validated by simulation and experiment investigations.

HAI 제어기반 SV PWM 방식을 이용하나 IPMSM의 고성능 제어

본 논문에서는 HAI(Hybrid Artificial Intelligent) 제어기반의 SV PWM 방식을 이용한 IPMSM의 고성능 제어를 제시한다. HAI 제어기는 적응 퍼지제어 및 신경회로망의 장점을 혼합 적용한다. SV PWM 방식은 지금까지 산업용 전동기 제어분야에 적용되고 있고 출력전류의 고조파 비율, 스위칭 주파수 및 응답특성을 향상시키는 수 있는 기법이다. HAI 제어기는 지령전압을 계산할 때 발생되는 문제점을 해결하기 위하여 종래의 PI 제어기를 대체하여 사용한다. HAI 제어기는 지령모델 기반의 적응제어, 퍼지제어 및 신경회로망으로 구성되어 속도 성능을 개선한다. 본 논문에서는 제시한 HAI 제어기를 적용하여 파라미터 변동, 정상상태 및 과도상태 등의 응답특성을 분석하고 종래의 FNN 제어기 및 PI 제어기의 응답특성과 비교한다. 따라서 본 논문에서는 HAI 제어기의 타당성을 입증한다.

Modulating Functions of Space Vector PWM for Three-Leg VSI-Fed Unbalanced Two-Phase Induction Motors

Modulating functions or space-vector-equivalent references of a carrier-based unbalanced two-phase output space vector pulsewidth modulation (SVPWM) strategy applied to a three-leg voltage source inverter are proposed in this letter. These functions are derived from a conventional balanced two-phase SVPWM method. The proposed SVPWM method is implemented using a DS1104 dSPACE controller board. With the proposed method, the appropriate voltages for both windings of an asymmetrical-parameter-type two-phase induction motor can be achieved for improving the motor performance. Experimental and calculated results confirm the validity of the proposed method.

Carrier-based unbalanced phase voltage space vector PWM strategy for asymmetrical parameter type two-phase induction motor drives

This paper proposes a space vector pulse width modulation (SVPWM) method based on a carrier providing unbalanced phase voltages for asymmetrical parameter type two-phase induction motor drives using a three-leg voltage source inverter (VSI). The principle is fully described. The proposed space vector equivalent phase leg reference voltages are derived from conventional ones. With the proposed SVPWM method, the output voltages are displaced at 90° with controllable amplitudes. The validity of the proposed method is verified by both calculated and experimental results.

PWM methods for two-phase inverters

This article focuses on simple space-vector PWM (SPWM) methods for two-leg, three-leg, and four-leg inverters that can be applied to three phase induction motor drives (TPIM). First, a carrier-based PWM method for a two-leg inverter was proposed on the basis of the conventional SPWM method. Second, a carrier-based PWM method for a four leg inverter that used a double triangular carrier wave was proposed. Third, a carrier-based PWM method for a three-leg inverter was proposed as a replacement for a conventional SVPWM method. Digital calculations using the PSIM software package are performed to investigate the effectiveness of the proposed PWM method

Carrier-Based Modulation Technique for Matrix Converter

This paper presents a carrier-based modulation method for a matrix converter. By using the offset voltage and changing the slope of carrier, it is possible to synthesize the sinusoidal input currents with the unity power factor and desired output voltages. The proposed method is equivalent to the so called space vector pulsewidth modulation method. The proposed method uses a new point of view to understand the matrix converter modulation method such as the voltage source inverter (VSI) modulation method. Using the proposed method, this paper presents the two-phase/three-phase modulation method and dynamic/steady-state overmodulation method for the matrix converter. These methods are well developed in the study of a VSI. By the proposed steady-state overmodulation method, it is possible to synthesize the fundamental component of output voltage to be equal to that of input voltage at the cost of some distortion of input current. The feasibility of the proposed modulation method has been verified by a computer simulation and experimental results. These results show that the proposed carrier-based modulation method can be implemented easily without any tables. It can be used for the application where a higher voltage transfer ratio is essential

A Space Vector PWM Scheme for Multilevel Inverters Based on Two-Level Space Vector PWM

Multilevel inverters are increasingly being used in high-power medium voltage applications due to their superior performance compared to two-level inverters. Among various modulation techniques for a multilevel inverter, the space vector pulsewidth modulation (SVPWM) is widely used. However, the implementation of the SVPWM for a multilevel inverter is complicated. The complexity is due to the difficulty in determining the location of the reference vector, the calculation of on-times, and the determination and selection of switching states. This paper proposes a general SVPWM algorithm for multilevel inverters based on standard two-level SVPWM. Since the proposed multilevel SVPWM method uses two-level modulation to calculate the on-times, the computation of on-times for an n-level inverter becomes easier. The proposed method uses a simple mapping to achieve the SVPWM for a multilevel inverter. A general n-level implementation is explained, and experimental results are given for three-level and five-level inverters

Space Vector PWM Techniques for Sinusoidal Output Voltage Generation with a Five-Phase Voltage Source Inverter

Five-phase variable-speed drives currently are considered for numerous applications, including electric and hybrid-electric vehicles, traction, and ship propulsion. If the machine is designed with a concentrated stator winding, the third stator current harmonic injection can be used to enhance the torque production and the machine needs to be supplied with the fundamental and the third harmonic of the voltage. On the other hand, if the machine is with a sinusoidally distributed winding, the supply should consist of the fundamental harmonic only. Since five-phase drives are invariably supplied from five-phase voltage source inverters (VSIs), adequate methods for VSI pulse width modulation (PWM) are required. This article analyzes different space vector PWM (SVPWM) schemes for a five-phase VSI, which can be used for five-phase motor drives with sinusoidal distribution of windings. A detailed model of a five-phase VSI is presented first in terms of space vectors and the existing technique of utilizing only large space vectors is elaborated. It is shown that this SVPWM method leads to generation of high amounts of low-order output voltage harmonics. Next, a novel SVPWM method is introduced, which enables operation with pure sinusoidal output voltages up to a certain reference voltage value, which is smaller than the maximum achievable with the given DC link voltage. To enable full utilization of the DC bus voltage, two different SVPWM schemes are further developed that can be used to extend the operation so that full utilization of the DC bus is achieved. This unavoidably leads to the generation of some low-order harmonics. These harmonics are however of significantly lower values than when only large vectors are used. A detailed performance evaluation of the existing and newly developed schemes is performed, based on the low-order harmonic content in the output voltages. Simulation results are included throughout the article to illustrate and verify the theoretical considerations.

A carrier-based PWM method for three-phase four-leg voltage source converters

In this paper a voltage modulation method based on a triangular carrier wave for the three-phase four-leg voltage source converter is described. The four-leg converter can produce three output voltages independently with one additional leg. The proposed modulation method for the four-leg converter can be implemented with a single carrier by a simple but useful "offset voltage" concept. The method is equivalent to the so called three-dimensional space vector PWM method, but its implementation is much easier. The maximum magnitude of the balanced three-phase voltage and the maximum magnitude of zero sequence voltage, which can be synthesized simultaneously, are derived. The feasibility of the proposed modulation technique is verified by computer simulation and experimental results. These results show that a proposed carrier-based pulsewidth modulation (PWM) technique can be easily implemented without conventional computational burden.

An improved carrier-based SVPWM method using leg voltage redundancies in generalized cascaded multilevel inverter topology

The carrier-based space vector pulse width modulation (SVPWM), which is considered as simple and efficient PWM technology, can be also used in multilevel inverters. The method was originally designed for the two-level inverter and developed to the diode-clamped multilevel inverter structure. However it may be noted that it also causes bad switch utilization in cascaded multilevel inverters. This paper introduces an improved carrier-based SVPWM scheme, which is fully suitable for cascaded multilevel inverter topologies because it can achieve the optimized switch utilization through the redistribution of the triangular carrier waves considering leg voltage redundancies while having the advantages of the conventional carrier-based SVPWM. Using experimental results, the superior performance of new PWM method is shown.

Problems of Exact Generation of Inverter Output Voltage

In this work, a new voltage space vector PWM method is developed. The problem of exact generation of small voltage vectors is discussed. Two methods for generating small inverter output voltage vectors are proposed. The influence of dead time is explained and its effect on the motor current is compensated. A squirrel cage induction motor with reduced supply voltage is used for testing the developed algorithm. Simulation and experimental results are carried out using fixed-point (DSP) and (FPGA). In addition, the practical realization of the proposed algorithm is discussed.

New feedforward space-vector PWM method to obtain balanced AC output voltages in a three-level neutral-point-clamped converter

In three-level neutral-point-clamped voltage-source inverters, proper modulation allows the average voltages of the DC-link capacitors to be kept at one-half the level of the DC-link voltage. However, in some operating conditions, a low-frequency ripple appears in the neutral-point potential and its frequency is three times that of the output voltages. As a result, the output voltages also have low-frequency distortion, which includes even and odd multiples of the fundamental. In this paper, a new space-vector pulsewidth-modulation strategy is presented to avoid that low-frequency output voltage distortion. This modulation method tries to balance the voltages of the capacitors by using only three vectors per modulation cycle. The duty ratios are directly calculated from the space-vector diagram, even when balance is not achieved. For all cases, the result is a balanced set of three AC output voltages. Some simulated and experimental results are given to validate the method.

A new simplified space-vector PWM method for three-level inverters

In this paper, a new simplified space-vector pulse width modulation (SVPWM) method for a three-level inverter is proposed. This method is based on the simplification of the space-vector diagram of a three-level inverter into that of a two-level inverter. If simplified by the proposed method, all the remaining procedures necessary for the three-level SVPWM are done like conventional two-level inverter and the execution time is greatly reduced. The DC-link neutral-point potential control algorithms are implemented more easily. The proposed method can be applied to the multi-level inverters above three-level. The validity of the new SVPWM method is verified by experiment with a 1000 kVA three-level insulated gate bipolar transistor (IGBT) inverter.

A high-performance generalized discontinuous PWM algorithm

In this paper, a generalized discontinuous pulsewidth modulation (GDPWM) method with superior high modulation operating range performance characteristics is developed. An algorithm which employs the conventional space-vector PWM method in the low modulation range, and the GDPWM method in the high modulation range, is established. As a result, the current waveform quality, switching losses, voltage linearity range, and the overmodulation region performance of a PWM voltage-source inverter (PWM-VSI) drive are optimized online, as opposed to conventional modulators with fixed characteristics. Due to its compactness, simplicity and superior performance, the algorithm is suitable for most high-performance PWM-VSI drive applications. This paper provides detailed performance analysis of the method and compares it to the other methods. The experimental results verify the superiority of this algorithm to the conventional PWM methods.

Switching loss minimised space vector PWM method for IGBT three-level inverter

In an inverter-fed motor drive system, inverter output-current distortion is reduced by enhancing the switching frequency and the motor torque ripple; magnetic noise is also reduced as a consequence. However, the system efficiency is also reduced due to the switching loss; this, in turn, sets a limit on any further enhancement of the switching frequency. This is particularly the case for the IGBT three-level inverter, since it is used in high switching frequency applications: the number of switching devices is twice that of the two-level inverter, thus the switching loss problem is more serious. The authors describe a new PWM strategy for the three-level inverter with an ability to reduce switching loss. In comparison with conventional sinusoidal PWM methods generating almost the same distorted load current, every phase of the inverter can have its switching stopped for 120/spl deg/ in one period by this new method. According to the load power factor angle /spl beta/, if /spl beta//spl les/30/spl deg/ the no switching duration can be set just in the centre of the peak value region of the load current, hence the switching loss can be greatly reduced. The reduction of switching loss is not dependent on /spl beta/.

Low-loss quasi-parallel resonant DC link inverter with advanced PWM capability

A low-loss quasi-parallel resonant DC link (L2QPRDCL) circuit with advanced PWM capability is proposed for soft switching a three-phase PWM inverter. This L2QPRDCL has minimum voltage stress for the devices, and an advanced PWM capability due to the variable zero voltage duration of the DC-link over a wide range. Owing to there being scarcely any freewheeling current in the L2QPRDCL during the zero voltage period, low-loss operation in the resonant circuit can be obtained. As a result, the proposed L2QPRDCL inverter is applicable to the highpower range. Operational principles and detailed analyses are presented. By adopting the non-nearest four vectors (N2FV) selection law in the space vector PWM technique, the narrow pulse problem originating from the link operation, which should be considered in those inverters having resonant DC-links, can be eliminated. Experimental results are also presented to verify the link operation and the performance of the selected space vector PWM method.

A Novel Voltage Modulation Technique of the Space Vector PWM.

In this paper, a novel voltage modulation scheme is described. With the effective voltage concept, the actual switching times for each inverter arm are deduced directly as a simple form. With the help of the presented zero sequence voltage allocation algorithm, the proposed PWM method has the high performance voltage generation capability exactly same as the conventional space vector PWM method with reduced effort. As well as giving a detailed explanation of the new PWM algorithm, the paper presents the comparison results with the conventional method such as space vector PWM and sinusoidal PWM method. In the proposed PWM method, the execution time can be reduced more than 25% as compared with the conventional space vector PWM method, and memory size will be minimized to 15% of the conventional PWM method.

Optimal PWM design for high power three-level inverter through comparative studies

Comparative studies between harmonic elimination and optimal PWM strategies are given for high power three-level inverter feeding an induction motor. An effective PWM map construction method based on the valid region on the frequency modulation index plane is suggested. Thereby, an optimal map including asynchronous space vector PWM, harmonic elimination and optimal PWM method is generated covering all of the low, middle and high modulation index regions. The PWM map was designed for 1 MVA rated general purpose GTO inverter and implemented with a digital signal processor. Experimental results are presented for 10 kVA prototype.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Harmonic analysis of space vector modulated PWM waveforms

While most traditional PWM inverters use the asymmetrical regularly sampled triangulation technique to generate waveforms, a recently reported space vector PWM method is rapidly gaining favour in the industrial drives arena as an alternative technique. The paper presents an analysis of the space vector PWM waveform to obtain its spectrum. The analysis is based on a novel decomposition technique, illustrated by considering the harmonics of a regularly sampled asymmetrical sinusoidal PWM waveform, which is in fact a partial solution to the space vector harmonics. The calculated harmonics show close agreement with measured harmonics from an experimental microprocessor-controlled inverter operating with the same waveform parameters.