moro
Member level 3
Hello,
i am working on a school project. I want to control a 3 phase BLDC motor.... the software will be managed by a stm32f103 arm device via a 3 phase mosfet bridge with ir2110 drivers
The motor which i have is a 24dc 3 phase star connection motor, with 6 poles and 3 hall sensors
The hall sensors timings are shown here
As i can see for 1 mechanical rotation, on a 3 pole machine i would require acording to the formula "electrical degrees" = 3 x "mechanical degrees", thus for 360 mech degrees i would require a 1080 electrical degrees.
Since every hall event happens at 60e.degrees that means for a complete mechanical rotation i need 18 steps, is this correct?
I said to my self to try this "by hand", so i hooked the 3 hall sensors to a logic analyzer, and try to rotate by hand the motor shaft... indeed it takes 18 hall events to reach a complete mechanical rotation
Now my question is regarding the determination of rpm value.
So suposing every hall event happens at 1ms ( 1000hz), that means my comutation would have a (1/6)/(transition time between 2 hall events), in my case (1/6)/(0.001 second)
Normaly in my case for 1000hz hall event and 18 steps/mech revolution that would yeld 1 rotation every 18ms, that means in a 60second period i would have 60000ms/18ms = 3333 rpm. Is my presumption correct?
What is the formula for determining the rpm value?
Thank you
i am working on a school project. I want to control a 3 phase BLDC motor.... the software will be managed by a stm32f103 arm device via a 3 phase mosfet bridge with ir2110 drivers
The motor which i have is a 24dc 3 phase star connection motor, with 6 poles and 3 hall sensors
The hall sensors timings are shown here
As i can see for 1 mechanical rotation, on a 3 pole machine i would require acording to the formula "electrical degrees" = 3 x "mechanical degrees", thus for 360 mech degrees i would require a 1080 electrical degrees.
Since every hall event happens at 60e.degrees that means for a complete mechanical rotation i need 18 steps, is this correct?
I said to my self to try this "by hand", so i hooked the 3 hall sensors to a logic analyzer, and try to rotate by hand the motor shaft... indeed it takes 18 hall events to reach a complete mechanical rotation
Now my question is regarding the determination of rpm value.
So suposing every hall event happens at 1ms ( 1000hz), that means my comutation would have a (1/6)/(transition time between 2 hall events), in my case (1/6)/(0.001 second)
Normaly in my case for 1000hz hall event and 18 steps/mech revolution that would yeld 1 rotation every 18ms, that means in a 60second period i would have 60000ms/18ms = 3333 rpm. Is my presumption correct?
What is the formula for determining the rpm value?
Thank you
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