Modern-Day Multi-Phase Multi-Level DC-AC Inverter for Advanced Electric Drives

Abstract

Electric drives are advanced by multi-phase, multi- level DC-AC inverters, which provide enhanced power quality, fault tolerance, and efficiency. By adding multi-level topologies andextendingconventionalthree-phasesystemstohigherphases, these inverters improve voltage control, minimize total harmonic distortion (THD), and lessen torque ripple. They are extremely relevant because they are used in high-power systems like renewableenergygrids,electriccars,andaircraft.Thebenefitsof various inverter topologies in terms of harmonic reduction, fault resilience, and effective energy conversion are reviewed in this paperalongwithperformanceanalysesusingMATLAB/Simulink simulations and advanced control techniques.

Introduction

1. Introduction

As the demand for efficient and high-performance electric drive systems grows—especially in electric vehicles, aerospace, and industrial automation—there is a need to improve upon the limitations of conventional three-phase inverters, such as:

• High harmonic distortion

• Poor fault tolerance

• High switching losses

Multi-phase (5, 7, or more phases) and multi-level DC-AC inverters have emerged as competitive alternatives, offering:

• Improved torque performance

• Better fault tolerance

• Smoother operation

• Reduced current per phase

2. Multi-Level Inverter Topologies

To improve the approximation of sinusoidal output and reduce switching losses, multi-level inverters use step-like voltage generation. Common topologies include:

• Diode-Clamped (DCMLI): Uses diodes to limit voltage stress on switches

• Flying Capacitor (FCMLI): Balances voltage with capacitors for smoother operation

• Cascaded H-Bridge (CHBMLI): Modular design; offers fault tolerance and scalability

Combining multi-phase with multi-level designs results in:

• Reduced Total Harmonic Distortion (THD)

• Increased efficiency

• Enhanced system reliability

3. Control Strategies for Inverter Performance

Various advanced control methods are used to improve inverter performance:

• Field-Oriented Control (FOC):

  • Separately controls torque and flux

  • Uses Park transformation and PI controllers

  • Offers precise and smooth torque control

• Direct Torque Control (DTC):

  • Fast torque response without coordinate transformations

  • Uses hysteresis controllers and switching tables

  • Higher ripple than FOC

• Space Vector PWM (SVPWM):

  • Reduces harmonics

  • Optimizes switching using space vector calculations

• Fuzzy Logic Control (FLC):

  • Rule-based, adaptive method

  • Handles non-linearities and improves fault tolerance

4. Multi-Phase Inverter Topologies

Topologies for systems requiring more than three phases include:

• Two-Level Voltage Source Inverter (VSI): Simple and efficient

• Three-Level Neutral Point Clamped (NPC): Reduces harmonic distortion and voltage stress

• Cascaded H-Bridge (CHB): Offers scalability and better waveform quality

• Flying Capacitor (FC): Achieves voltage balancing using capacitors

5. Simulation and Results

Simulations were conducted using MATLAB/Simulink to evaluate the performance of different topologies and control methods.

Simulation Setup:

• DC Bus Voltage: 400V

• Switching Frequency: 10kHz

• Motor Load: 5-phase, 2.2kW induction motor

• Control Techniques Tested: FOC, DTC, SVPWM, FLC

Performance Analysis:

• Voltage and Current Waveforms: Show balanced operation and reduced harmonics

• Torque and Speed Response:

  • FOC: Smooth, accurate control

  • DTC: Faster response, but more ripple

• THD Analysis and Switching Losses: Multilevel inverters reduce THD and lower switching losses compared to conventional designs

Conclusion

By lowering harmonic distortion, torque ripple, and overall efficiency,multi-phaseinvertersgreatlyimproveelectricdrive performance when paired with multi-level techniques. Power rating, efficiency, fault tolerance, and control complexity are important considerations when choosing an inverter topology. Multi-levelinvertersprovidebetterperformanceinhigh-power applications by lowering voltage stress and enhancing wave- form quality, whereas two-level inverters are appropriate for low-power applications because of their simplicity.

References

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Copyright

Copyright © 2025 Mukesh Kumar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.