A Permanent Magnet Motor (PMM) designed to break the 300°C barrier was previously presented that included many advancements to greatly improve the operating temperature and reliability beyond the ability of current equipment . A key design element is the inclusion of a squirrel cage in the PMM rotor that results in a hybrid construction. This paper will delve into the rationale for the hybrid configuration and will assess motor performance using electromagnetic simulations and validation testing.
PMMs are used in many industrial applications and have recently started to gain traction in oil and gas upstream production applications. A significant issue is the PMM compatibility with existing motor drive equipment and their need for special provisions to operate at the end of long cables without position sensors. A hybrid configuration help overcome these limitations and allows operation with conventional variable speed drives using a standard scalar controller as used with induction motors.
The design, development, and qualification of the hybrid PM rotor construction were undertaken using a rigorous analytical approach combined with extensive validation testing.
The motor is designed to maintain stability under the severe transient conditions in the SAGD environment, where the produced emulsion rich in gas and solids creates highly variable conditions for the motor and controller.
A detailed electromagnetic model of the motor for configurations with or without the squirrel cage was undertaken to demonstrate the effectiveness of the hybrid configuration to maintain speed control stability. A time stepped method was used to simulate the motor start with simulated loading conditions, reflecting the starting and operating conditions with breakaway torques up to full load torque condition and 50% transient loads.
The squirrel cage was successfully integrated within the rotor structure of a 150hp PM motor. Extensive design and thermal-structural analysis ensured the construction was acceptable for operation in the ranges −40°C to 350°C. Validation testing was then performed to demonstrate the hybrid PM motor construction functioned for use with conventional and legacy variable frequency drives.