Creating a motor and housing in MotorSolve

Thermal Analysis of a Brushless Permanent Magnet Motor

Motors & Generators with MotorSolve

Design specifications for electric machines are requiring more than ever that the optimum design consider multiple disciplines of physics. The thermal behavior for instance can significantly impact the magnetic response of a machine especially with extended operation. How long will the insulation last? Will the permanent magnets demagnetize? Will the current density require additional cooling? What cooling configuration[s] will work? MotoSolve capabilities allow the designer to couple magnetic and thermal responses to determine the optimum machine.

MotorSolve brushless dc PM motor

METHODS and RESULTS

CREATING the MOTOR MODEL

A brushless Permanent Magnet motor must provide 12 N-m of torque at rated speed, current and temperature. This 4-pole rotor and 12 slot stator combination successfully meet the challenge.

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DUTY CYCLE SETUP

Set the interval in the Duty Cycle to reflect the rated power and torque in a steady state condition and then extend it for operation throughout a 1 hour duration.

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COUPLED ELECTROMAGNETIC-THERMAL

Utilize the coupled magnetic - thermal simulation with 2 full iterations so that the losses within each component of the machine can be best represented through the entire operating duration.

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INITIATING the TRANSIENT MAGNETIC EXPERIMENT

Selecting the Analysis Charts | Motion Analysis experiment will initiate an Ambient Temperature simulation. The results from this simulation will provide a baseline of motor performance which can be used for comparison with the rated operation.

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MOTOR PERFORMANCE at AMBIENT TEMPERATURE

A summary table showcases the Time-Averaged responses of the motor. User's can select their key performance criteria from each experiment, and readily review the result. Solution results can be easily recorded in a laboratory notebook utility or exported for use in other tools.

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OUTPUT POWER RESULTS

User's can also review the time transient performance for a variety of motor responses. Here the Input and Output Power responses are shown in the graphic.

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TRANSIENT VOLTAGE & CURRENT RESULTS

The Voltage applied to the stator winding and the resulting Current are shown in the graphic; these quantities are expressed as either a function of rotor angle or source phase angle.

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TRANSIENT TORQUE RESULTS

The Torque response of the motor is shown in this graphic. Precise data assessment is possible as the user can easily review the motor's response and document in the simulation's report structure.

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TRANSIENT THERMAL EXPERIMENT

Selecting the Thermal Charts - Temperature experiment will yield the time transient thermal response for all the components of the motor. Losses defined by the Duty Cycle definitions are used for the thermal excitations.

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RESULTS for EACH MOTOR COMPONENT

The solution chart will represent either the minimum, average or maximum temperatures within each component of the motor. The solution data is shown as a function of time within the entire operating range.

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RATED OPERATION TEMPERATURE of the BLDC Motor

After the final coupled simulation iteration, the rated response of the machine can be reviewed. A summary table showcases the time-averaged co-simulation responses of the motor.

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RATED TEMPERATURE OUTPUT POWER RESULTS

The Input and Output Power responses at rated operation are shown in the graphic. The Output Power reflects the increase in conductor losses due to the increased temperature.

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RATED TEMPERATURE VOLTAGE & CURRENT RESULTS

The Voltage applied to the stator winding and the resulting Current are shown in the graphic.

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RATED TEMPERATURE TORQUE RESULTS

The Torque response of the motor is shown in this graphic. Comparison of the motor response at ambient versus rated operation temperatures allows the user to adjust the motor's character in order to successfully meet the requirements.

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