DC Signal Injection-Based Thermal Protection for Stator Winding of AC Machines

Abstract

Abstract: AC motors are the main workhorses in process industries. Their malfunction may not only lead to repair or replacement of the motor, but also cause significant financial losses due to unexpected process downtime. Reliable thermal protection of AC motors is crucial for reducing the motor failure rate and prolonging a motor’s lifetime. In this paper, conventional thermal protection devices and state-of-the-art thermal protection techniques are reviewed with their advantages and limitations discussed. The general trend is to develop a series of active motor thermal protection methods as a low-cost alternative approach to the traditional passive and sensor-based methods. These active thermal protection methods monitor the average stator and rotor temperature via motor parameter estimation. In this paper, an overview of the active thermal protection techniques for line-started, soft-starter-connected and inverter-fed AC motors is presented and advantages and drawbacks discussed. The active thermal protection techniques are capable of providing accurate, and non-invasive thermal protection of AC motors.

Key words: AC motor, inverter, starter, stator resistance, stator temperature, temperature estimation, thermal protection

Pinjia Zhang, Thomas G. Habetler. DC Signal Injection-Based Thermal Protection for Stator Winding of AC Machines[J]. Chinese Journal of Electrical Engineering, 2016, 2(2): 58-66.

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