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Multi-phase motors are nowadays considered for high-power variable-speed drive applications due to numerous advantages that they offer when compared to their three-phase counterparts. Multi-phase voltage source inverters are invariably used to provide multi-phase variable voltage and variable frequency with appropriate pulse width modulation (PWM) control. In this paper, a novel PWM algorithm for...
Theoretically analysis of Fourier series is used to predict the different inverter circuit's different SPWM signals' harmonic contents are already existed. This paper presents the theoretical results are verified by orCAD/Pspice simulation and the spectrum analysis of output current indicated the fact that SPWM technique has effective reduction of the harmonic contents. The proposed technique has...
This paper studied the real solution number of the switch angles for the inverters which are based on the Selective Harmonic Eliminated PWM (SHEPWM) technology. By the method of variable substitution, the nonlinear transcendental equations can be transformed to a Semi-Algebraic system. Then, with the help of the latest progress in the mechanical proving software for the Semi-Algebraic systems, an...
A Multilevel shunt active filter is proposed to reduce the harmonic contents in source currents of a harmonic polluted three phase system supplying a non-linear load. The shunt active filter is designed with a seven level cascaded H-bridge inverter. To generate the required compensation currents Multicarrier PWM Current control method is used. The reference compensating currents are extracted from...
A scheme for spreading the harmonic spectrum of Three-level Voltage Source Inverters is proposed in this paper. Space Vector based Sigma Delta Modulation is employed in the proposed scheme. The principle of Vector Quantization is applied for quantizing the reference Space Vector in the Sigma Delta Modulator. For the spatial quantization, the inverter voltage vector space is divided into different...
Grid voltage rise problems occur, especially at light loads, due to the proliferation of distributed generation. Two techniques are proposed for regulating the voltage in low voltage radial networks when inverter based distributed generation is employed. The first technique, voltage regulated power control regulates the voltage by controlling the active power level delivered by the inverter to be...
Loss estimation is a critical aspect of inverter design. The present work investigates the losses occurring in the DC-link capacitors of the three-phase three-level Neutral Point Clamped and Cascaded H-Bridge inverter topologies, by performing a harmonic analysis of the capacitor currents. Results are verified by simulations. Their analysis reveals the advantage of the NPC inverter.
In this paper, a control technique is proposed for parallel connected inverters to share linear and nonlinear loads in proportional to their capacities. Using locally measurable feedback voltages and currents without an external communication mechanism, this technique considerably reduces the sharing error of reactive power, output voltage drop and output voltage distortion, which are inherent drawbacks...
Large Current Source PWM AC Drives needs either, a phase controlled rectifier or an Active Front End (AFE). Choosing the AFE implies to use optimized switching patterns in both, rectifiers and inverters. Several authors propose modular current source based AC-Drives (MCSC) as a practical way to handle currents larger than the devices capabilities. Standard SHE was extended to Multilevel Selective...
This paper proposes the development of dodecagonal (12-sided) space vector diagrams from cascaded H-Bridge inverters. As already reported in literatures, dodecagonal space vector diagrams have many advantages over conventional hexagonal ones. Some of them include the absence of 6n±1, (n=odd) harmonics from the phase voltage, and the extension of the linear modulation range. In this paper, a new power...
A number of PWM techniques have been developed in recent times for five-phase voltage source inverters (VSIs), which enable sinusoidal output voltage generation. Relatively little attention has been however paid to the current ripple caused by these PWM methods. This paper investigates stator current ripple (THD), caused by the switching harmonics, for two space vector PWM (SVPWM) techniques that...
Parallel operation of PWM rectifiers and inverters has been used in UPS, motor drives, telecom power supply, and other applications to reduce system development cost and to provide easy power scalability as well as redundancy. Conventional symmetric interleaving can eliminate certain harmonics and their sideband components but is not necessarily optimal for EMI filter design if the filter attenuation...
Three-level PWM rectifier is suitable for medium voltage and high power with unity power factor, bidirectional power applications. This paper put forward a power accumulator battery charge/discharge system based on the three-level inverter and a AC filter design method differ from the traditional way. Because the voltage source PWM converter is rooted from the boost circuit, the topology of both its...
Based on the analysis of SHPWM method, we proposed an improved modulation method suited for cascaded multilevel inverter of three-phase systems, which is called carrier overlapping - switch frequency optional - pulse width modulation (CO-SFO-PWM). The method combines the advantages of carrier overlapping and switch frequency optional, which enables it to increase the fundamental amplitude of the output...
The switching loss minimized PWM method for flying capacitor three-level inverter is presented based on the study of PSPWM and SVPWM for flying capacitor multilevel inverter in the paper. In comparison with conventional carrier-shifted PWM method, each phase of the flying capacitor multilevel inverter can have the 120° no switching zone in one period by the proposed method; according to power factor...
A direct torque control strategy for dual three-phase permanent magnet synchronous motors is presented in this paper. The motor has two sets of three-phase stator windings spatially phase shifted by 30 electrical degrees. In order to reduce the harmonic current in stator windings which has no contribution to torque production, torque and flux are controlled based on regulators and three-phase decomposition...
In this paper, cascade H-bridge converter with Variable-Frequency Carrier Bands PWM method (VFCB-PWM) has been proposed, which is the combination of cascade structure and CPS-SPWM method. High equivalent switching frequency can be obtained with low switching frequency devices. Such advantages as simple structure, wide bandwidth and good transient response can be obtained in large power equipment....
Based on the sinusoidal pulse width modulation technology and regular sampling method, the switching time points calculation formulas of tangent method and secant method are established. This paper analyses the precision of switching turn-on and turn-off time point, and compare these switching time points. Calculation results show that SPWM pulses generated by tangent method and secant method are...
Four kinds of compound carrier disposition PWM schemes are discussed, two of which are proposed for the first time in the paper. Methods for analyzing the amplitudes and harmonics of the output voltage of single-phase multi-level cascaded inverter are introduced for these PWM schemes, whose carrier waves could be equivalent to the ones of phase-shifted-PWM. Features of these PWM schemes are summarized...
This paper deals with a design method of LCL filter for grid-connected three-phase PWM voltage source inverters (VSI). By analyzing the total harmonic distortion of the current (THDi) in the inverter-side inductor and the ripple attenuation factor of the current (RAF) injected to the grid through the LCL network, the parameter of LCL can be clearly designed. The described LCL filter design method...
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