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Hi guy, I was wondering if there is anyway to reduce the rpm a a brush dc motor without the use of gears, and without loosing any rpm. Thanks in advance.
PWM will slow the motor but to keep the same torque you will need a feedback control loop.
In your case you need to measure the speed of the motor. The controller uses this measurement to vary the PWM to the motor to keep it running at the same speed. This setup will deliver the motors maximum torque when it meets a lot of resistance. It will also be able to run at full speed.
Its fairly easy to build your own motor controller using a microcontroller. A PID controller is the most common control algorithm. There have been a ton of posts on implementing PID controllers in the past - a search should turn up a bunch.
Well, gears might be the only way to transfer torque. Pulse Width Modulation PWM , that controls the speed through a Half Bridge, will control the speed of the motor but I don't understand how it will control the torque though! :!:
It controles how much power a motor gets and has an speed sensor.So wen the motor becomes loadad.The rpm will go down and the electronic will detect that and deliver more power the motor.
Its aculy regulatig the PWM whitn an ouput of an rpm sensor
Ok there is an rpm sensor on the motors shaft.If the motor gets more loaded i will thurn slower the rpm sensor detects that and the PWM gives more power to the motor to get it up to that rpm.
You need an rpm sesor ,an microcontroler and a motor driver
Ok, here is the thing that I know. When you buy a motor there are two different things you should put in mind, torque and speed. All motors have an internal torque, let’s call it the main torque. Motors speed usually measured in Round Per Second RPM, notice that all manufactures consider this as a “no load” speed. In physics, torque is considered as the angular force that is perpendicular to the distance. <What I said so far is just a review so everything after this makes some sense>
Why using gears? You use gears to transfer “the main torque” and to reduce the speed of the motor and transform this to an “additional torque” added to the main torque.
So the total torque according to this is total torque=additional torque + the main torque.
According to physics also, the number of gears is determined how much torque you want to transfer and get from the speed.
What does PWM do? Well, it controls the speed, but without gears the additional torque will not get formed. That’s why I was surprised from this.
Electro, your idea is to use a feedback circuit that tells the PWM source, the microcontroller, to pump up more pulses, Considering you are using an encoder for the brushed motors or hall effect sensor for the brushless motors, is a bad idea for one single reason. You are using only the main torque. That’s will be a disaster if you have a small motor without sufficient “main torque” to move the object.
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