Jelena Loncarski

Analysis and Comparison of Peak-to-Peak Current Ripple in Two-Level and Multilevel PWM Inverters

Three-phase multilevel (ML) inverters are used in many medium- and high-power applications such as motor drives and grid-connected systems. Despite the fact that numerous pulsewidth modulation (PWM) techniques for ML inverters have been developed, the impact of these modulation schemes on the peak-to-peak output current ripple amplitude has not been addressed yet. In this paper, analysis and comparison of current ripple for two-level (2L) and three-level (3L) voltage source inverters are given. Reference is made to optimal and popular modulation, so-called centered PWM, easily obtained by both carrier-based modulation (phase disposition, with proper common-mode voltage injection) and space vector modulation (nearest three vectors). It is shown that the peak-to-peak current ripple amplitude in 3L inverters can be determined on the basis of the ripple in 2L inverters, obtaining the same results as by directly analyzing the output voltage waveforms of the 3L inverters. This procedure can be readily extended to higher level numbers. The proposed analytical developments are verified by both numerical simulations and experimental tests.

Evaluation of current ripple amplitude in three-phase PWM voltage source inverters

Determination of current ripple in three-phase PWM voltage source inverters (VSI) is important for both design and control purposes, since this is the most popular conversion topology for energy conversion systems. In this paper the complete analysis of the peak-to-peak current ripple distribution over a fundamental period is given for three-phase VSIs. In particular, peak-to-peak current ripple amplitude is analytically determined as a function of the modulation index. Minimum, maximum, and average values are also emphasized. Although the reference is made to continuous symmetric PWM, being the most simple and effective solution to minimize the current ripple, the analysis could be easily extended to either discontinuous or unsymmetrical modulation, both carrier-based and space vector PWM. The analytical developments for all the different subcases are verified by numerical simulations.

Comparison of peak-to-peak current ripple amplitude in multiphase PWM voltage source inverters

Multiphase systems are nowadays considered for various industrial applications. Numerous PWM schemes for multiphase voltage source inverters with sinusoidal outputs have been developed, but just recently the impact of these modulation schemes on the output peak-to-peak current ripple amplitude has been considered. Determination of current ripple in multiphase PWM voltage source inverters is important for both design and control purposes. This paper gives the comparison of the peak-to-peak current ripple distribution over a fundamental period for multiphase VSIs, starting from three-phase and extended to the multiphase inverters, with emphasis on five and seven phases. Simplified expressions to get maximum value of the ripple are carried out and compared among inverters with different phase number. Although reference is made to the centered symmetrical PWM, being the most simple and effective solution to maximize the dc bus utilization, leading to a nearly-optimal modulation to minimize the rms of the current ripple, the analysis can be readily extended to either discontinuous or asymmetrical modulations, both carrier-based and space vector PWM. The results obtained by the proposed analytical approach are backed with the numerical simulations of the peak-to-peak ripple for inverters with different phase numbers and in case of different modulation indexes to prove the effectiveness of mathematical developments.

A simple MPPT algorithm for novel PV power generation system by high output voltage DC-DC boost converter

This paper presents the novel topology of Photo Voltaic (PV) power generation system with simple Maximum Power Point Tracking (MPPT) algorithm in voltage operating mode. Power circuit consists of high output voltage DC-DC boost converter which maximizes the output of PV panel. Usually traditional DC-DC boost converters are used for such application, but they are not the most suitable solution due to output limitation, lower efficiency and require more sensors with complex control algorithm. Further on, the effects of parasitic elements are suppressed, as well as the power transfer efficiency of DC-DC converters for PV integration. Hence, to overcome these difficulties this paper investigates a DC-DC boost converter together with the additional parasitic component within the circuit to provide high output voltages for maximizing the PV power generation. The proposed power system circuit substantially improves the high output-voltage by a simple MPPT closed loop proportional-integral (P-I) controller, and requires only two sensor for feedback needs. The complete numerical model of the converter circuit along with PV MPPT algorithm is developed in numerical simulation (Matlab/Simulink) software. A detailed performance analysis is carried out under both PV panel irradiation (high/low) and load regulation conditions. Numerical results obtained in this paper are in the agreement with the theoretical developments, proving the effectiveness of the proposed topology.

Evaluation of current ripple amplitude in five-phase PWM voltage source inverters

Multiphase systems are nowadays considered for various industrial applications. Numerous PWM schemes for multiphase voltage source inverters with sinusoidal outputs have been developed, but no detailed analysis of the impact of these modulation schemes on the output peak-to-peak current ripple amplitude has been reported. Determination of current ripple in five-phase PWM voltage source inverters is important for both design and control purposes. This paper gives the complete analysis of the peak-to-peak current ripple distribution over a fundamental period. In particular, peak-to-peak current ripple amplitude is analytically determined as a function of the modulation index, and a simplified expression to get its maximum value is carried out. Reference is made to centered symmetrical PWM, being the most simple and effective solution to maximize the dc bus utilization, leading to a nearly-optimal modulation to minimize the rms of current ripple. However, the analysis can be easily extended to either discontinuous or asymmetrical modulation, both carrier-based and space vector PWM. The analytical developments for all the different sub-cases are verified by numerical simulations.

Experimental verification of current ripple amplitude in five-phase PWM VSIs

Multiphase systems are nowadays considered a viable solution for various industrial applications. Numerous PWM schemes for multiphase voltage source inverters with sinusoidal outputs have been developed, but no detailed analysis of the impact of these modulation schemes on the output peak-to-peak current ripple amplitude has been reported. Determination of the current ripple in multiphase PWM voltage source inverters is interesting from the theoretical point of view and, in some cases, is useful for both design and control purposes. This paper gives the complete analysis of the peak-to-peak current ripple distribution over a fundamental period with experimental verification in the case of five-phase voltage source inverters. In particular, peak-to-peak current ripple amplitude is analytically determined as a function of the modulation index with a symmetrical centered PWM, being the most simple and effective solution to maximize the dc bus utilization, leading to a nearly-optimal modulation to minimize the rms of the current ripple. However, the analysis could be easily extended to either discontinuous or asymmetrical modulation, both carrier-based and space vector PWM.

Space vector analysis of dead-time voltage distortion in multiphase inverters

Inverter dead-time effects have been widely investigated in past for three-phase voltage source inverters (VSIs). Recently, a great deal of research has concentrated on PWM methods suitable for multi-phase VSIs (with more than three phases). All PWM methods theoretically produce sinusoidal output voltages without low-order harmonics. This paper analyzes the dead-time effects on output variables of multi-phase VSIs in the case of carrier-based PWM techniques if no any compensation technique is applied. In particular, a generalized analysis for n-phase inverters is introduced first, and numerical verification for three-, five- and seven-phase inverters are performed to verify the analytical developments. The dead-time effect on load voltage is also represented in terms of multiple space vectors, and analysis of harmonics content for each α-β plane is given.

Development of Power Electronics Based Test Platform for Characterization and Testing of Magnetocaloric Materials

Magnetocaloric effects of various materials are getting more and more interesting for the future, as they can significantly contribute towards improving the efficiency of many energy intensive appl ...

Current ripple evaluation in dual three-phase inverters for open-end winding EV drives

Ac motor current ripple in electric vehicles is source of electromagnetic interferences and audio noise, from the inverter-motor power connection cables and from the motor itself. By increasing the inverter switching frequency the ripple amplitude is reduced, but the drive efficiency decreases due to the proportionally increased switching losses. A viable solution to reduce the current ripple amplitude is to introduce a multilevel inverter instead of a standard two-level (2L) three-phase inverter. A simple and effective way to achieve a three-level (3L) inverter in battery-supplied electric vehicles consists of using two standard three-phase 2L inverters with the open-end winding motor connection. In this paper the peak-to-peak ripple amplitude of the dual-2L inverter is evaluated and compared with the corresponding ripple of the single 2L inverter, considering the same voltage and power motor ratings. The ripple analysis is carried out as a function of the modulation index to cover the whole inverter modulation range.

Cyber Physical Systems for Industry 4.0: Towards Real Time Virtual Reality in Smart Manufacturing

Cyber Physical System (CPS) together with Internet of Things, Big Data, Cloud Computing and Industrial Wireless Networks are the core technologies allowing the introduction of the fourth industrial revolution, Industry 4.0. Along with the advances in new generation information technologies, smart manufacturing is becoming the focus of global manufacturing transformation. Considering the competitive nature of industry, it requires manufacturers to implement new methodologies. Realistic virtual models mirroring the real world are becoming essential to bridge the gap between design and manufacturing. In this paper model conceptualization, representation, and implementation of the digital twin is presented, on the real use case of manufacturing industry and in the cyber physical environment. A novel CPS architecture for real time visualization of complex industrial process is proposed. It essentially considers the Simulation technological pillar of Industry 4.0. The results from a real industrial environment show good performances in terms of real time behaviour, virtual reality and WebGL CPS visualization features, usability and readability.