Abstract

Designing electrical drives resistant to the failures of chosen sensors has recently become increasingly popular due to the possibility of their use in fault-tolerant control (FTC) systems including drives for electric vehicles. In this article, a virtual current sensor (VCS) based on an algorithmic method for the reconstruction of the induction motor (IM) phase currents after current sensor faults was proposed. This stator current estimator is based only on the measurements of the DC-bus voltage in the intermediate circuit of the voltage-source inverter (VSI) and a rotor speed. This proposal is dedicated to fault-tolerant vector controlled IM drives, where it is necessary to switch to scalar control as a result of damage to the current sensors. The proposed VCS allows further uninterrupted operation of the direct rotor-field oriented control (DRFOC) of the induction motor drive. The stator current estimator has been presented in the form of equations, enabling its practical implementation in a microprocessor system. Simulation studies of the proposed algorithm in an open and closed-loop DRFOC structure are presented under different operation conditions of the drive system. The experimental verification of the proposed method is also presented and the accuracy of the stator current estimation algorithm is analyzed under various operating conditions of the drive system.

Highlights

  • The growing interest in electric vehicles in passenger transport has resulted in research into new solutions to increase the efficiency and reliability of electric drives in these applications, while reducing the size and weight

  • Conclusions based on the DC bus voltage and rotor speed is effective in drive systems with induction motors

  • According to the presented research, the proposed method of the stator current reconstruction equipped with a speed sensor, where safety and reliability are more important than costs

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Summary

Introduction

The growing interest in electric vehicles in passenger transport (cars, trams, buses) has resulted in research into new solutions to increase the efficiency and reliability of electric drives in these applications, while reducing the size and weight. The studies in [24,25,26] presented the idea of placing a DC current sensor between a group of transistors in such a way that it is possible to measure the current in VSI zero states This method is effective in systems operating at low speed, where there is a low modulation rate. This paper presents a solution that in systems with angular velocity measurement will allow for further implementation of vector control in the event of failure of all phase current sensors. The algorithm of VSC uses a popular rotor flux estimator model, and speed measurement is required to implement it This method is dedicated to fault-tolerant systems, where as a result of damage to current sensors, it is necessary to switch to scalar control [9].

Mathematical Model of the Induction Motor
Stator Current Estimation Algorithm
Description of the Tested Structure and Test Scenarios
It can be seen that the proposed current
Transient
Transient of the measured and estimated current in phase
Description of the Experimental
Analysis of the Stator Current Estimation in Various Operating Condition
The next figure showsstudies a comparison of theoperation isd and isq
Reference and measured angular speed waveforms:
10. Waveforms
Conclusions

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