A Seamless Transition Scheme of Position Sensorless Control in Industrial Permanent Magnet Motor Drives With Output Filter and Transformer for Oil Pump Applications

This article proposes a position sensorless control scheme for the induction and permanent magnetic low-voltage (LV) motor drives with an output filter and transformer for an electric submersible pump (ESP) and progressive cavity pump (PCP). The proposed sensorless strategy covers the full-speed range for ESP drives. An open velocity loop, current regulated sensorless controller is utilized to drive induction and permanent magnet motors (PMMs) during starting and at low speeds. A field-oriented controller (FOC) that utilizes an estimated rotor position based upon motor back electromotive force (EMF) is utilized to drive the motor at higher speeds. A seamless transition between controllers for the two operational modes, i.e., low-speed control and high-speed control, is proposed in this article. With velocity mode control over the full-speed range and mode control hysteresis, a smooth transition between open loop and EMF-based observer control can be achieved. The sensorless control scheme presented in this article has been implemented in a commercial drive for an ESP (deep well) application.