Why Does My BLDC Motor Reach Higher RPM With Trapezoidal vs Sinusoidal Drive?

Hello All,
I have one motor which I am driving from trapozoudal drive which gives max RPM as 2600.The same motor whenever I am driveing from sinusoidal drive which gives 2150RPM Why such difference in the RPM is occuring.
Kindly help me with the same.

Hi Amit,Measure the voltage applied to the motors using both methods, it should give you an idea of why the speed is different. The output voltage will differ based on your control method.

Hello Alan Sir,Thanks for your comment. It is helping me to understand sinusoidal commutation will give less RPM than trapezoidal commutation.Now we have changed the motor to check both the commutation methods,The motors Max RPM with trapezoidal commutation is 3100 RPM without any fluctuations in the current.The motors Max RPM with sinusoidal commutation is 3010 RPM but with so many fluctuations in the current. Using sinusoidal commutation,motor is properly working till 2500 RPM without any fluctuations. But once we are going ahead of 2500 RPM the fluctuation in the currents are starting. I am not getting how to deal with this stage.

Hi Amit, Apologies, I am only seeing your comment now, I may be able to help you better if you send me some more information, such as schematics/ drawings or photographs with equipment used and or part numbers. If you would still like some help it may be easier to email me at alan_gallagher(_at_)hotmail.com. Otherwise good luck with your project.
RegardsAlan

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