Redline

Motor Speed Loop Fails at High RPM Debug

Symptom

At 3,000 RPM the hoist drive holds speed. At 15,000 RPM the shaft never turns forward, and the load runs it backwards.

Measured trace of the starter on one run: commanded to 3,000 RPM the shaft rises to about 3,346 RPM and settles at 3,000; commanded to 15,000 RPM it never turns forward and the load runs it backwards to about 1,776 RPM, where it stays to the end of the run

Circuit

Plant registers are listed in the figure.

Circuit: the bench writes the speed command into SRAM at 0x2000FF00 and applies a load torque to the motor, U1 STM32F4 drives the motor plant at 0x50061000 over the bus and prints on USART1 TX, and the plant registers DUTY, DIR, CTRL and SPEED are listed with offset, access and units

Pass condition

Within 300 RPM of every command, a new one mid-run included, from 85 ms after it is set to the end of the run, with no fault latched.

Notes

The hoist controller sets the command while the loop runs 250 ms. The load, none to heavy, differs every run and cannot be read.

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