A Flexible and Fast Space Vector Pulse Width Modulation Technique for Multilevel Converters

This study presents a space vector pulse width modulation (PWM) method for a multilevel single-phase decentralized power converter (DPC) called MSPDPC. The proposed model is built by connecting half-bridge cells in series. The output voltage can be adjusted according to demand by adding or subtracting cells. Cells use communication protocols to transmit and receive information with two neighboring cells. The received data contains information for the decentralized space vector pulse width modulation (DSVPWM) method proposed in this paper. In the proposed DSVPWM method, cells set up links to exchange information such as cell position, total cells in a phase, reference voltage amplitude, and reference frequency. The PWM control signals of each cell are calculated based on the information received. The study also focuses on evaluating the ability to adjust the switching vector and the corresponding dwell time of the cells when the structure of the DPC changes. The ability to dynamically reconfigure the DPC is a crucial feature that ensures uninterrupted power supply in case of one or several cell failures. The system automatically establishes a new state with the active cells. The proposed configuration and communication method between cells provide very fast configuration times. The load voltage of the DPC is adjusted to 0.5 times the voltage per cell, which allows the modulation voltage amplitude to be adjusted best according to the load requirements. The study used Matlab/Simulink software to review the initial assessments. The proposed model and algorithms will be verified on the Digital Signal Processor (DSP) platform with a 220V/500W load.

Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, there are some problems in the conventional method, such as the error of amplitude, the shift of phase angle and the non-determinacy of initial oriented angle. In this paper, two one-order low-pass filters are adopted instead of the pure integrator in the virtual line-flux-linkage observer, which can steady the phase and amplitude. Furthermore, an original scheme of harmonics detection under the rotating coordinate is advanced based on the simplified space vector pulse width modulation (SVPWM) strategy. Meanwhile, by using the new SVPWM algorithm, the voltage space vector diagram of the three-level inverter can be simplified and applied into that of two-level inverter, and this makes the control for Neutral Point potential easier.

This paper investigates the effect of (voltage source) inverter's non-linearity on the space vector pulse width modulation (PWM) method and the discontinuous PWM methods, DPWM0, DPWM1, and DPWM2. The inverter's non-linearity of dead-time and minimum pulse-width are considered. These non-linearity's impose distortion regions where their effects cannot be properly compensated. The distortion regions are identified for the various PWM methods in space vector diagram format. A method to switch between DPWM methods to avoid the distortion regions while minimizing switching losses is proposed for the middle modulation indexes. At high modulation indexes, a method to modify the DPWM1 switching function is proposed which preserves the fundamental component while taking into consideration the inverter's non-linearity. The proposed methods are experimentally verified and shown to reduce the harmonics in the motor phase currents which would normally be induced due to the inverter non-linear effects. As a result, the proposed method allows for smoother torque production

With the development of power semiconductor and digital processor technology, the design and application of three-level inverter in electric multiple units(EMU) are more and more extensive. The traditional space vector pulse width modulation (SVPWM) method for the three-level inverter requires estimating the sectors and calculating a lot of trigonometric functions. As a result, the calculation of SVPWM method for microprocessor is very complicated and large. To reduce the calculation working of the PWM module, a SVPWM method based on 60° coordinate system for three-level inverter is focused and discussed in this paper. Finally, a vector control system of asynchronous motor based on DSP was built up to verify the feasibility of this SVPWM method in this paper. Experimental results show that the adopted method can omit a lot of trigonometric functions, and reduce the calculating burden of the control system.

In this paper, speed-sensorless input-output linearisation controller (IOLC) based direct torque control (DTC) of induction motor (IM) is implemented in simulation. The switching states of the inverter are determined by the space vector pulse width modulation (SVPWM) method to provide switching conditions with constant switching frequency instead of the lookup table-based conventional DTC method. Thus the torque and flux fluctuations, total current harmonic distortions and switching loss are decreased. In this drive system, IOLC is used instead of proportional-integral (PI) controller to obtain voltage reference vector of the SVPWM. In order to increase the control performance, an extended Kalman filter (EKF)-based estimator is used for the estimation of stator resistance in addition to stator current, stator flux, rotor mechanical angular velocity and load torque. According to the simulation results, it is understood that the sensitivity of the drive system to stator resistance is eliminated by EKF-based estimator and a very high dynamic control performance is achieved with the accurate estimations of EKF algorithm.

In this paper, a novel approach to realize the carrier-based pulse width modulation (CBPWM) method for indirect matrix converter (IMC) is presented. The advantage of the proposed CBPWM method is that only one triangular carrier signal with constant gradient falling and rising edges is used to generate the PWM to the power switches in both the rectifier and the inverter stages of IMC. The analysis of the proposed CBPWM method is based on the space vector approach and the relationship between CBPWM and space vector pulse width modulation (SVPWM) methods is provided. In this paper, four CBPWM methods called: sinusoidal PWM, third harmonic injection PWM, symmetrical PWM and discontinuous PWM are presented. These different CBPWM schemes are established according to the distribution of zero vectors and the switching pattern of the SVPWM method. The comparison of output voltage performance with different CBPWM schemes are investigated. Compared to the conventional method the calculation time of the proposed method is reduced around 50%. Concretely, the calculation time of the SVPWM method is 45 μs, while the calculation time of the proposed method is 22 μs. The experiments have been carried out to show the effectiveness of the proposed method.

Electric drive on an electric bike, consist of electric motor, power converter and electronic controller. These are the mover of electric vehicle system. This paper discussed the three-phase inverter with Space Vector Pulse Width Modulation (SVPWM) method as a three-phase induction motor drive in electric bike application. The discussed that are modeled by using MATLAB/SIMULINK. The purpose of this paper is to get the analysis of the three-phase inverter SVPWM as a three-phase induction motor drive with specification 500 W, 50 V, 50 Hz and 8 poles. Converter using a battery with a voltage 48 V. Before the battery voltage is converted by an inverter, battery voltage was increased through a boost converter up to 70.62 V. Through simulation with MATLAB software was obtained curve of sinusoidal voltage, current, and speed of the motor by SVPWM controlled system. In this paper also tested against changes in the value of the fundamental frequency inverter. Test results show that the inverter can be set the speed of the motor at a frequency of 20 Hz to 50 Hz. Electric drive on an electric bikes, consist of electric motor, power converter and electronic controller. These are the mover of electric vehicle systems. This paper discussed the three-phase induction motor supplied by Space Vector Pulse Width Modulation (SVPWM) inverter. They discussed that are modeled by using MATLAB/SIMULINK. The purpose of this paper is to get the analysis of the three-phase inverter SVPWM as a three-phase induction motor drive with specification 500 W, 50 V, 50 Hz and 8 poles. Converter using a battery with a voltage 48 V .

The articles introduces the basic principle of space-vector pulse width modulation(SVPWM), and its arithmetic and fixed parameter is presented in detail, present a space-voltage vector pulse width modulation(SVPWM) method based on the 2-phased hybrid stepper motor driven by H bridge. The experiment is simulated by Matlab/Simulink in at last, the simulation result proved that the arithmetic used SVPWM to control the 2-phase hybrid stepper motor is feasible.

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.

Phase current is crucial for closed-loop control and system monitoring of a T-type three-level inverter (TThLI). However, the traditional space vector pulse width modulation (SVPWM) method cannot fully meet the minimum sampling time, which leads to the emergence of unobservable areas (UAs) in the neutral current sensor (NCS) phase current reconstruction system of TThLI. Moreover, the current zeropoint drift (ZPD) caused by temperature drift, aging, and noise affects the accuracy of NCS sampling. Regarding the issues above, this paper investigates the impact of UAs and ZPD on the NCS phase current reconstruction system and proposes an asymmetric SVPWM and error suppression (APES) phase current reconstruction method. The proposed method comprises two links: asymmetric SVPWM (ASVPWM) and ZPD error suppression. Firstly, the ASVPWM regulates the PWM waveforms according to composite zero vector and volt-second balancing principles and then generates three observable vectors whose dwell time is greater than the minimum sampling time to eliminate the UAs. Secondly, the ZPD errors are obtained and suppressed through the dynamic current triple sampling mechanism to improve reconstruction accuracy. Finally, experimental results show that the proposed APES method achieves an accuracy of 3.51% at the expense of a slight increase in total harmonic distortion.

The common-mode voltage in three-phase inverter may harm the motor drive system. If only non-zero space vector is used, it can be suppressed by appropriate Space Vector Pulse Width Modulation (SVPWM) method. In this paper, a Nonzero Vector Pulse Width Modulation (NZPWM) technique is proposed to suppress common-mode voltage for three-phase inverter. In sectors I, III and V, instead of the real zero voltage vectors, two opposite voltage vectors near to the active voltage vectors are utilized. In sectors II, IV and VI, the first active voltage vector and the voltage vector opposite to the first active voltage vector are utilized. Therefore, the amplitude of common-mode voltage can be reduced to one sixth of DC bus voltage. Simulation and experimental results show that the proposed NZPWM is effective for common-mode voltage suppression.

Three-phase three-level transformer-less inverters are widely used in photovoltaic (PV) generation systems because of their low cost and high efficiency. However, common-mode (CM) currents in these inverters are so large that they threaten security and aggravate EMI problems. Some space vector pulse width modulation (SVM) methods have been developed to reduce CM current through reducing CM voltage, but they would also sacrifice the modulation index or efficiency. This paper proposes a new SVM method that suppresses the CM current without reducing the efficiency or the modulation index. Moreover, simultaneous switching during dead time is analyzed thoroughly and a compensation method is proposed to eliminate the influence of dead time. Experiments verify that compared with other methods, proposed method shows the best CM current suppression performance as well as the best efficiency characteristic.

Variable frequency and variable voltage are increasingly supplied by a three-level voltage source inverter for variable speed applications. The appropriate output voltage at the line side of the inverter is obtained using a suitable pulse width modulation technique. This chapter investigates the three-level Diode Clamped or Neutral Point Clamped topology, which is a popular multi-level topology. The modulation wave is generated using two Sine-triangle methods and two Space Vector Pulse Width Modulation methods. To produce the PWM signals for the three phases, these modulation waves are compared to a triangular carrier. Instead of the three phase modulating waves used in SPWM, a rotating reference voltage vector is used as a voltage reference in SVPWM methods. The magnitude and frequency of the line side's fundamental variable are controlled by the magnitude and frequency of the reference vector, respectively. Because of its higher dc bus utilization and lower harmonic distortion than SPWM, Space Vector Modulation has become a common PWM technique for three-phase Voltage Source Inverters. In MATLAB/SIMULINK software, the four PWM methods are simulated and compared for THD and Capacitor Balance. Embedded Editor and Matlab Editor Functions are used to build the programs. As compared to Sine PWM, simulation results show that Space vector PWM better utilizes dc bus voltage, produces less THD, and improves capacitor balance.

This paper proposes an optimized control strategy for any modular multilevel converter (MMC), based on a generalized space vector modulation (SVM) method. By fully utilizing the flexibility of the SVM method, i.e., the redundant switching sequences and adjustable duty cycles, this optimized control strategy enables optimal capacitor-voltage and circulating-current control of the MMC. The proposed control strategy can also be implemented with other pulse width modulation methods, e.g., the carrier-based modulation and the nearest-level modulation, though sophisticated selection of the common-mode voltage injection may be required. This paper therefore also demonstrates that for the MMC, the SVM is more flexible than other modulation methods. Typical case studies are given to validate the analysis.

Brushless doubly-fed machine (BDFM) is a new type of AC induction motor.It has a good applicable prospect as the variable frequency motors or the variable speed constant frequency generators. Although the advantage of the three-level inverter, there are also some problems of neutral point voltage balance in this method such as the unbalance of neutral point voltage. And the traditional principle of Three-level inverter space vector pulse width modulation method is to estimate the sectors and calculating a lot of trigonometric functions. To solve these problems, a novel method for the virtual space vector concept in G-H coordinate system is presented in this paper. The method proposed can omit the judging process of the sectors, reduce the calculating burden, and maintain the balance of neutral-point voltage between capacitances within a certain index modulation. The results of simulation are given to validate the improved virtual space vector modulation.