Hi everyone,
I'm Lisa from Italy, I'm new to this forum, I hope I can find help.
I have a problem in driving a brush DC motor I'm using to make a drill.
The motor I'm using is a Portescap 23GST2R82-216P: **broken link removed**.
I'm driving it using Intersil HIP4086 driver (I need this driver because on the same machine I need to optionally plug in a brushless motor), and STD20NF06 ST mosfets with embedded diodes. My micro is a PIC 24FJ256GA110, which provide PWM peripherals.
I'm using sign-magnitude drive, with high side mosfet closed and pwm on the low side mosfet.
I need to give to the motor an overvoltage (32V) for short usage periods to reach higher rpms.
Anyway my problem at the moment is with low speeds: if I drive the motor with VM=24V and PWM Duty cycle 1% I would expect to see it running slowly, but I see it still.
I also tried to start it with a higher duty cycle and to reduce it gradually once the motor is in movement, but it stops as soon as it reaches 1% duty cycle.
Moreover the speeds I measure with higher PWMs (with >2% duty cycle the motor starts) are significatively higher than the ones I would expect. In example, with VM=24V, duty cycle 10% I measure no load speed of 9020 rpm, more than 12VDC nominal value reported on the datasheet!
I'm using 15.6kHz PWM frequency, but the problem is exactly the same even if I slow down the pwm frequency to 244Hz.
I provided the circuit for current and back emf measurements, but I still didn't embed speed and torque regulation in firmware, this was the first "rough" attempt to see the motor running, and I would have expected a speed proportional to the values reported on the datasheet (like 8700rpm with VM=24V, 50%duty).
It's my first attempt in working with motors, I studied a bit of theory, but really I can't understand what I'm wrong in practice.
Can anyone help me?
Thank you very much
I'm Lisa from Italy, I'm new to this forum, I hope I can find help.
I have a problem in driving a brush DC motor I'm using to make a drill.
The motor I'm using is a Portescap 23GST2R82-216P: **broken link removed**.
I'm driving it using Intersil HIP4086 driver (I need this driver because on the same machine I need to optionally plug in a brushless motor), and STD20NF06 ST mosfets with embedded diodes. My micro is a PIC 24FJ256GA110, which provide PWM peripherals.
I'm using sign-magnitude drive, with high side mosfet closed and pwm on the low side mosfet.
I need to give to the motor an overvoltage (32V) for short usage periods to reach higher rpms.
Anyway my problem at the moment is with low speeds: if I drive the motor with VM=24V and PWM Duty cycle 1% I would expect to see it running slowly, but I see it still.
I also tried to start it with a higher duty cycle and to reduce it gradually once the motor is in movement, but it stops as soon as it reaches 1% duty cycle.
Moreover the speeds I measure with higher PWMs (with >2% duty cycle the motor starts) are significatively higher than the ones I would expect. In example, with VM=24V, duty cycle 10% I measure no load speed of 9020 rpm, more than 12VDC nominal value reported on the datasheet!
I'm using 15.6kHz PWM frequency, but the problem is exactly the same even if I slow down the pwm frequency to 244Hz.
I provided the circuit for current and back emf measurements, but I still didn't embed speed and torque regulation in firmware, this was the first "rough" attempt to see the motor running, and I would have expected a speed proportional to the values reported on the datasheet (like 8700rpm with VM=24V, 50%duty).
It's my first attempt in working with motors, I studied a bit of theory, but really I can't understand what I'm wrong in practice.
Can anyone help me?
Thank you very much
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