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Spray Cooling for the 2010 Prius

Motors & Generators with MotorSolve

Motor design requirements often require some form of cooling. The thermal simulation capability in MotorSolve allows designers to explore the behavior of their motors with cooling, and in particular Spray Cooling. The Prius revolutionized the Electric Vehicle in 2004, and the latest revisions to the motor in 2010 continue to show the need for Spray Cooling in order to keep the components of the motor in safe operating conditions.

Spray Cooling for the 2010 Prius

METHODS and RESULTS

2010 Prius IPM with 8-poles

The 2010 Prius uses an IPM motor with an 8-pole rotor and a 48-pole 3-phase Winding. The geometry is unique and requires the use of MotorSolve's DXF file import for both the Rotor and the Stator components.

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AXIAL CROSS SECTION

The MotorSolve interface allows the designer to quickly configure the stack length, the size of the bearings and nature of the remaining components along the shaft.

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THERMAL MATERIALS

It is imperative that we fully describe the motor and its components from a material perspective. This includes both the magnetic and thermal properties. MotorSolve allows for simply pull-down assignments for all materials.

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DUTY CYCLE SETUP

Set the interval in the Duty Cycle to reflect rated 3,000 rpm and 25 kW power in a steady state condition for a 40 minute duration. This test was performed by the Oakridge National Lab. The user can set both the time-step and the number of coupled iterations which will occur.

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SPRAY COOLING SETUP

A variety of parameters exist to define the nature of spray cooling on the motor end-windings. Number of nozzles, size of nozzle, coolant temperature and coolant material allow the user to clearly define this cooling configuration.

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BACK EMF

The Back EMF is a figure of merit for the performance of the magnetics within a motor. The 2010 Prius produces 53.0 mV per rpm [37.5 mV rms per rpm]. At 4,000 rpm this is 212. 1 V [150 V rms]. MotorSolve predicts the Back EMF within 2% of the measured values. This is an EMF constant of 0.87 V-sec/radian.

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LOCKED-ROTOR TORQUE RESPONSE of the MOTOR

The peak torque at locked rotor can be determined by MotorSolve by setting the speed of the motor very low in the D-Q Analysis.

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TORQUE vs CURRENT

The motor is moved to a variety of rotor positions and then the peak torque is computed as each position.

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TRANSIENT TEMPERATURE RESPONSE

MotorSolve provides the time-transient temperature result for each component.

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COMPARING MEASURED vs SIMULATED TEMPERATURE

MotorSolve matches the measured results to within +/- 5% throughout the entire time interval.

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