Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.

[Tech] Motor Inductance, Resistance and Maximum RPM: Estimated vs Actual

It will likely be a long time before anyone can actually measure these parameters to verify, but i'll take a shot at calculating them.

Why is this important or of any interest? Because these electrical characteristics are used in the calculations made by the inverter to drive the motor using a Direct Torque Control (DTC) scheme, described in patents and discussed in another thread.

For a 3-phase, 4-pole wye motor with the poles wired 2s2p, and with 4 Turns per pole using 16 AWG copper wire 12-in-hand:

phase inductance ~ 493 nH
phase resistance ~ 5.3 mR

This gives an L/R time constant of 93 usec. If we use 3 tc to reach full current, then the motor max speed ~ 26,858 rpm. With a 9.7:1 gearbox the theoretical max speed would be 228 mph.

For a P85D to reach 155 mph the motor(s) will need to spin at 18,200 rpm and make at least 50 kW each. The inverter would need to be generating a current waveform of 606 Hz, and the per phase L/R time constant would have to be less than 138 usec.

Send data when you get some...
Last edited:

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.