I want to make a Brush-less DC motor that goes 1720 Rotations Per Minute while carrying a 70 kilograms load on it. The motor must be 50mm in diameter and about 15mm in width.How do I go about making that and what kind of specifications must a battery have, to be able to run this for 1-2 hours?Thank you in advance! :)
your question is unclear, it has no mention of work or energy. you can have motor of that size running at that speed and moving 70kg load if the motion is sufficiently slow, say 1meter per minute. this can easily run on batteries for couple of hours. but if you are looking for a motor to power electric bike for example, you will notice that this is hopelessly undersized. better way is to ask questions in terms of real work, for example pump x volume of water per hour to elevation of y meters or provide power for electric bike where total weight is 90kg, travel speed is 40km/h and expected one charge commute distance is 70km.
A brushless DC motor is really an AC motor with a circuit, called an inverter or controller, to convert the DC into AC for the motor. The converter and number of poles on the motor determine the shaft speed(converter-output-frequency/number-... The amount of torque the motor can handle will be determined by the motors size and construcion. Larger motor, more torque. Neodymium more torque. Smaller motor, steel instead of neodymium, less torque. Trying to squeeze lots of torque from a small motor usually means lots of heat generated and loss of efficiency. I'm not sure what 70 kilograms means. Any motor can be made to lift 70 killograms with gearing. You must determine the required torque of the motor to determine if a motor of the size you're talking about can do the job. Torque is measured in newton-meters or foot pounds. If you're looking for the motor to lift 70 kilos from a small lever without any gearing, forget it. A motor of that size won't come close. But if you're just talking about lifting, it's more feasible with gearing.
