Motor Data Collection and Performance Validation

I assisted in the construction of a two-motor dynamometer to test electric motors under a load of up to ~20 kW, and I analyzed data from this dyno as well as full-vehicle field tests to characterize and validate the powertrain system.

This work, together with my related powertrain simulation and mechanical design, won third place in the MIT DeFlorez Award program in May 2019.

The base dynamometer setup and data acquisition pipeline was done by MITERS, and I designed and manufactured a base plate and a shaft coupling to mount our motor to the system.

Data analysis performed (on dyno and/or from full-vehicle tests)

• Torque speed curve

• Voltage vs no-load speed

• Stall torque and dynamic torque vs q-axis current (Iq)

• Efficiency as a function of torque and speed

• Modulation index, d-axis current (Id), and field weakening

• Sag in DC battery voltage vs torque

Motor torque (before 3.47:1 gear ratio) plotted against wheel speed (after gear ratio) and calculated efficiency (T_mot_Nm * w_wheel_rad * GR) / (V_dc * I_dc) for a practice endurance run

Time series data during a successful field weakening trial. The d-axis current rises once the modulation index exceeds 110%, enabling higher motor speeds.

An investigation into the field weakening of our inverter. Nonzero regulator outputs to the left of the red line are due to transients.

Examining the internal resistance of the battery by showing the bus voltage sag as a function of torque. The right graph shows that peak torque is independent of no-load voltage, as expected.

Dynamometer graphs verifying the torque constant and saturation characteristics of the motor.

A look at how the inverter reported modulation index differs from our calculated value. The reason this occurs is unknown, but potentially indicates overmodulation.

Custom dynamometer setup. I designed and manufactured the mounting and shaft coupling for the motor on the right. The load motor is a Hyundai Sonata and the two are coupled through a torque sensor.