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Measured electrical angle from hall sensors is inconsistent at higher speeds

DHopk
Associate

Hi,

I'm using the the P-NUCLEO-IHM001 pack and have added a custom PCB with three SS360ST hall effect sensors (with 120 deg spacing) to the motor. I have also followed the instructions in UM1052 for determining the electrical placement angle parameter for the hall sensors and have managed to run the motor at speeds between +- 4,000 rpm.

My issue is that the motor stops (without error) at speeds above 4,000 rpm, even though the motor can reach 13,000 rpm through sensorless control.

What I have found so far is that the measured electrical angle (measured through the DAC) of the rotor from the hall sensors is not consistent relative to the hall sensor signal, and rapidly oscillates up to +- 90 deg from its expected value (based on observed electrical angle). The attached videos demonstrate this, where the green trace in both videos is the hall sensor input H1, the blue trace in 'measured_angle' is the measured electrical angle, and the blue trace in 'observed_angle' is the observed electrical angle (PLL).

I assume this inconsistency is the reason the motor cannot reach higher speeds, so is there an issue in the firmware that causes this to happen? If not, is there any way I could improve the measurement of the electrical angle through the firmware? I have no experience with programming for the STM32, so I'm not quite sure how to accomplish this myself.

Many thanks,

David

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