Search Results (19)

In the control system of a permanent magnet synchronous motor (PMSM) driven by an inverter, the conventional space vector pulse width modulation (SVPWM) strategy introduces high-frequency current harmonics at the switching frequency and its multiples, resulting in significant high-frequency vibrations during motor operation. To address this issue, a dual-random SVPWM strategy is proposed in this paper, which combines a random switching frequency and random zero-vector to spread the spectrum of high-frequency current harmonics. This approach effectively disperses the high-frequency harmonics concentrated at the switching frequency and its multiples, thereby significantly reducing the motor’s high-frequency vibrations. Furthermore, to overcome the limitations of the traditional linear congruential method in generating random numbers, the Beta distribution is introduced and improved in this study. The particle swarm optimization (PSO) algorithm is employed to optimize the shape parameters of the Beta distribution, to achieve the optimal random number performance. Finally, experimental validation is conducted under various speed conditions. Compared with the conventional SVPWM strategy, the results demonstrate that the proposed dual-random SVPWM strategy exhibits superior suppression of both high-frequency harmonics and high-frequency vibrations. Full article

The three-level simplified neutral point clamped (3L-SNPC) inverter has received increasing attention in recent years due to its potential applications in electrical drives and smart grids with renewable energy integration. However, most existing research has primarily focused on control development, with limited studies investigating modulation strategies or analyzing inverter losses under varying operating conditions. These aspects are critical for practical industrial applications. To address this gap, this paper proposes a novel carrier-based space vector pulse width modulation (CB-SVPWM) strategy for the 3L-SNPC inverter, aimed at simplifying PWM implementation and reducing cost. The proposed modulation strategy is experimentally evaluated by comparing inverter losses and total harmonic distortion with those of the conventional three-level neutral point clamped (3L-NPC) inverter under an equivalent carrier-based modulation scheme. A comprehensive comparative analysis is conducted across the full modulation range to demonstrate the effectiveness of the proposed approach, achieving a 13.2% reduction in total power loss, a 33.6% improvement in execution time, and maintaining a comparable weighted total harmonic distortion (WTHD) with a deviation within 0.04% of the conventional 3L-NPC inverter. Full article

This paper presents the establishment of an accurate loss model for high-power-density IGBT modules used in electric vehicles, leveraging the thermal simulation capabilities of the power electronics simulation software PLECS 4.1. The study aims to address the significant influence of IGBT losses on the energy efficiency and reliability of electric vehicles. A simulation model was built using the SVPWM modulation strategy to drive a three-phase inverter, and the average loss method was employed to determine both conduction and switching losses. The simulation results were compared with calculations based on the datasheet, showing a deviation of less than 4%. For instance, the actual conduction loss was found to be 7.988 W, compared to the theoretical calculation of 8.16 W, with a deviation of 2.15%. Similarly, the switching loss was 22.069 W, compared to the theoretical value of 22.447 W, with a deviation of 1.71%. These results confirm that the proposed model accurately predicts losses under specified conditions. Compared with traditional methods, the model presented in this paper offers higher precision and improved simulation speed, thus proving effective for accurate loss analysis of IGBT modules and supporting further energy efficiency improvement and system optimization in electric vehicles. Full article

Circulating current suppression can effectively improve the reliability and redundancy of parallel inverter systems. The mechanism and influencing factors of the low- and high-frequency zero-sequence circulating current (ZSCC) are analyzed in this study. Based on a mechanism analysis and the built mathematical model, the composite control strategy of zero-sequence voltage difference (ZSVD) compensation and virtual inductance is proposed to suppress the low- and high-frequency ZSCC. In the composite control strategy, the low-frequency ZCSS (LF-ZCSS) is suppressed by the ZSVD compensation method, and the HF-ZCSS is suppressed by the virtual inductance method. The ZSVD compensation is incorporated into the SVPWM as an input to regulate the modulation and suppress the LF-ZCSS, and virtual inductance is introduced into the current control loop to suppress the HF-ZCSS. A parallel system prototype composed of two 6 kW inverters is constructed. The experiments show that the ZSCC of the parallel system is reduced by 45%, which verifies the effectiveness of the proposed composite control strategy. Full article

Three-phase four-switch active power filters (APFs) have attracted attention due to their low amount of semiconductors and low cost. The traditional control strategy of three-phase four-switch APFs usually includes phase-locked loops (PLLs) and rotating coordinate transformation for harmonic detection, resulting in complicated calculations and increased computation. In this paper, a modified control strategy for three-phase four-switch APFs based on fundamental positive sequence extraction is proposed, eliminating PLLs and rotating coordinate transformation with trigonometric calculations. Harmonic extraction is based on the fundamental positive sequence extraction method, while non-locked phase loop coordinate transformation is proposed to eliminate trigonometric calculations. Quasi-PR control is adopted for current tracking, and DC voltage control is designed to suppress voltage imbalance between the two split capacitors on the DC side. The space vector pulse width modulation (SVPWM) method is modified for a reduced-switch APF topology. The proposed control strategy guarantees excellent harmonic compensation: harmonic currents are significantly suppressed when the APFs are working, the THD of the source current decreases to 3.86%, the bus voltage fluctuation on the DC side is small, the voltage remains stable, and the computational complexity is reduced. Finally, a simulation and an experimental hardware platform are established to validate the feasibility and performance of the proposed control strategy. The experimental results show that it has good performance in suppressing harmonics and improving power quality. Full article

In response to the challenges posed by large-scale, uncoordinated electric vehicle charging on the power grid, Vehicle-to-Grid (V2G) technology has been developed. This technology seeks to synchronize electric vehicles with the power grid, improving the stability of their connections and fostering positive energy exchanges between them. The key component for implementing V2G technology is the bidirectional AC/DC converter. This study concentrates on the non-isolated bidirectional AC/DC converter, providing a detailed analysis of its two-stage operation and creating a mathematical model. A dual closed-loop control structure for voltage and current is designed based on nonlinear control theory, along with a constant current charge–discharge control strategy. Furthermore, midpoint potential balance is achieved through zero-sequence voltage injection control, and power signals for the switching devices are generated using Space Vector Pulse Width Modulation (SVPWM) technology. A simulation model of the V2G system is then constructed in MATLAB/Simulink for analysis and validation. The findings demonstrate that the control strategy proposed in this paper improves the system’s robustness, dynamic performance, and resistance to interference, thus reducing the effects of large-scale, uncoordinated electric vehicle charging on the power grid. Full article

PWM (pulse width modulation) is the most widely applied current conversion technology, but the high-frequency harmonics it causes have a significant negative impact on inverter system performance. This paper focuses on the three-phase T-type three-level inverter as the research object and addresses existing PWM voltage noise and midpoint potential imbalance issues by proposing an improved random SVPWM strategy, named Neutral Point Potential Balance Random Space Vector PWM (NPB–RSVPWM). The NPB–RSVPWM strategy includes three main steps: (1) introducing a midpoint potential balancing control loop to adjust the synthesis timing of the effective vectors to generate pulse signals, optimizing midpoint potential balance; (2) employing a randomly varying carrier frequency in place of the carrier used in the SVPWM strategy to generate the driving signals for switching devices; and (3) controlling the inverter through the driving pulse signals. This strategy optimizes the synthesis sequence of traditional SVPWM strategy vectors and incorporates random frequency modulation techniques. The mathematical model analyzes PWM harmonic expressions corresponding to fixed switching frequencies, and a random frequency carrier is chosen to suppress these PWM harmonics. The effective vector’s equivalent circuit is analyzed, proposing a technique for optimized vector synthesis timing. The simulation and experimental results verify that the NPB–RSVPWM technique can disperse PWM harmonic energy, reduce voltage noise, and optimize midpoint potential balance. Under the NPB–RSVPWM strategy, the line voltage spectrum becomes uniform, the maximum harmonic content is greatly reduced, and the fluctuation in the DC side midpoint potential is significantly improved. Compared with the traditional SVPWM strategy and random PWM strategy, the NPB–RSVPWM strategy has a lower voltage noise, smaller total harmonic distortion, and a more stable midpoint potential. The effectiveness and feasibility of the NPB–RSVPWM strategy are verified by simulation and experimental results. Full article

Considering that the defects of traditional nearest–two–vector SVPWM (NTV–SVPWM) have a low voltage transfer ratio (VTR) and those of nearest–four–vector SVPWM (NFV–SVPWM) have a high output current harmonic, two improved space–voltage pulse–width–modulation (SVPWM) strategies are proposed in this paper, based on analyzing the harmonic characteristics of traditional NTV–SVPWM and NFV–SVPWM. The first strategy is to synthesize the referenced voltage vector according to the different weight factors by NTV–SVPWM and NFV–SVPWM. The second strategy is to synthesize the referenced voltage vector according to the different weight factors of NFV–SVPWM and the large vector. Compared to NTV–SVPWM, the simulation results show that the two proposed SVPWM strategies have lower output voltage errors and THDs. Compared to NFV–SVPWM, the simulation results show that the two proposed SVPWM strategies have higher VTRs and THDs. Compared to the two proposed SVPWM strategies, proposed SVPWM strategy one has a lower output voltage error and THD. The experimental results verify that the proposed modulation strategy is correct and feasible. Full article

The phase circulating current (PCC) of the parallel three-phase inverter systems dramatically affects the power quality and conversion efficiency of the power grid. In this paper, a composite suppression strategy is proposed to solve the PCC issue by using the sliding mode control (SMC) approach and improved virtual impedance droop control. Taking the commonly used 2-group parallel three-phase inverter as an example, an inter- and intra-classification model is established by analyzing the sources of PCC. In order to suppress the inter-PCC, the traditional virtual impedance droop control is given, following the improved substitute by combining SMC. And the variables of the bus voltage, Q-U loop, P-f loop, and the virtual-induced reactance are also introduced for the robust control of the impedance droop. On the other side, a SMC-based suppression approach is designed to solve the issue of the intra-PCC. Its idea is to introduce a regulation factor for the space vector pulse width modulation (SVPWM) so that the zero-sequence voltage can be eliminated and the influence of the intra-PCC can be relieved. Comparative simulations and experiments validate the effectiveness of the methods proposed in this paper. Full article

Three-level NPC inverters have been widely used in grid-connected systems due to their superior performance compared with two-level inverters, but more switches lead to high fault probability. Meanwhile, the neutral point potential (NPP) fluctuation of the DC link is an inherent problem of three-level NPC inverters. To keep the three-level NPC inverter running stably after single-arm failure, a fault-tolerant control strategy based on an optimised space vector pulse width modulation (SVPWM) is proposed in this paper. Firstly, the common-mode voltage (CMV) of the postfault three-level NPC inverter is analysed and then the preliminary synthesis principles of the reference voltage vector are determined. Then, in order to ensure the NPP balance and the quality of the grid-connected currents, the reference voltage vector synthesis rules are optimised, a low-pass filter (LPF) and a hysteresis comparator are designed, respectively, to ensure the quality of grid-connected currents and effectively decrease the DC link NPP deviation. Finally, the simulation results show that the proposed fault-tolerant control strategy can realize the stable and reliable operation of the grid-connected three-level NPC inverter after single-arm failure, and the CMV can be reduced significantly, the quality of grid-connected currents is also improved. The proposed fault-tolerant strategy also shows good performance when the grid-connected currents change. Full article

An improved segment reduction-based space vector pulse width modulation (SVPWM) for an F-type three-level inverter (FT²LI) is presented in this article. The proposed SVPWM algorithm decreases the additional switching state transition of each triangle with the application of an improved nine- and three-segment reduction switching strategy. The main feature of the segment reduction technique is that it eliminates second-order harmonics in the inverter output side with good total harmonic distortion (THD), low switching losses, and minimum filter requirements when compared with carrier-based PWM (CBPWM) techniques such as multi-carrier sine PWM (MC-SPWM), sixty-degree PWM (60° PWM), and switching frequency optimal PWM (SFO PWM). The proposed modulation algorithm for FT²LI is implemented on the MATLAB/Simulink platform. The performance of the proposed segment reduction-based SVPWM algorithm is tested experimentally on an FT²LI at various amplitude and frequency modulation indices, and the experimental results are verified with the simulation results. Additionally, a comparative analysis carried out to study the relationship between the segment reduction-based SVPWM and CBPWM techniques inferred that the suggested segment reduction-based SVPWM algorithms can optimize high-order harmonic distributions and have a minimum computational burden. Full article

This study presents a bridge arm attached to the FESS motor’s neutral point and reconstructs the mathematical model after a phase-loss fault to assure the safe and dependable functioning of the FESS motor after such fault. To increase the fault tolerance in FESS motors with phase-loss faults, 3D-SVPWM technology was utilized to operate the motor. The parameters of the zero-axis current compensation control were modified based on the dual-closed-loop control strategy for the speed and current. The simulation experiments conducted in this study demonstrate that the fault-tolerant control strategy adopted can significantly reduce excessive torque pulsation after the phase failure of the FESS motor, stabilize the motor output torque, and improve the fault-tolerance performance of the FESS motor’s control system for the FESS motor. Full article

Open-end winding five-phase induction motor (OeW-5PIM) configuration is used in industrial applications, where minimization in the total harmonic currents and high reliability are needed. The majority of the literature on OeW-5PIM topology discusses field-oriented control and direct torque control in addition to other robust control techniques such as the backstepping approach. This paper focuses on the mathematical and experimental approaches of backstepping control (BSC) and rotor-flux-oriented control (RFOC) for an OeW-5PIM topology. The space vector pulse width modulation (SVPWM) strategy is associated with the suggested control techniques to improve the dynamic performance (i.e., reducing ripple, fixed switching frequency, etc.) of the studied motor. Furthermore, the RFOC-SVPWM and BSC-SVPWM are comprehensively compared using experimental implementation under various situations such as load torque, open-phase fault, and high/low-speed operation. Full article

A novel cross−series connection of two five−phase permanent magnet synchronous motors (FPMSM) supplied by single inverter can halve the number of required power units and current sensors. This, along with a decoupling control strategy for FPMSMs in series based on an improved dual−frequency vector modulation (DFV−SVPWM) and a flux−linkage torque ripple suppression method with current compensation are proposed in this paper, each of which have great significance for multi−unit industrial equipment. The third harmonic flux−linkage will produce torque ripple in the FPMSM in series, which has an adverse effect on accuracy. In this paper, a synchronous decoupling mathematical model of dual−series FPMSM with harmonic flux−linkage is established to analyze the decoupling relationship between torque and current. In addition, an enhanced DFV−SVPWM with higher modulation ratio is proposed for the decoupling control of double motors in series. Furthermore, based on the torque influence of two series−connected motors by harmonic flux−linkage and the decoupling control with improved DFV−SVPWM, a torque ripple compensation method with current compensation is proposed, which can effectively suppress the torque ripple of FPMSM with harmonic flux−linkage and not affect the other. The correctness and superiority of the scheme are verified by simulation and experiment in this paper. Full article

The low-voltage and high-current permanent magnet synchronous generator (PMSG), which has characteristics of high power density, small size, and excellent energy saving, is representative of the generators. As a key module of the integrated DC output system of PMSG, the low-voltage and high-current rectifier module is also a nonlinear time-varying system that is readily influenced by parametric changes and external disturbances. Aiming at the shortcomings of traditional control strategies, this paper proposes a novel low-voltage and high-power rectifier module control strategy based on nonlinear feed-forward PID control. The controller has a wide range of environmental applications because of its greater robustness. At the same time, the introduction of feed-forward control shortens regulation time of the system. Therefore, the combination of the two control methods can improve the dynamic performance of the system without influencing the steady-state performance. The simulation model of an integrated rectifier system based on SVPWM control was constructed by Simulink, which can achieve a rated output of 5 V/300 A. At the same time, the simulation model of the controller is constructed and applied to the rectifier output system of a 5 V/300 A synchronous generator to complete the nonlinear feed-forward PID control. Through the comparison between simulation and experiment, it has been proven that the control method can effectively resist the load disturbances and improve the response speed of the system. Full article