I am using a 12V,600 rpm PMDC motor. When I start the motor, it takes a little bit of time to reach its max speed due its inertia. My requirement for a specific task is that the motor should reach the max speed as early as possible. I am using 11.1V,30C ,8000 mAh Li-Po battery. Is there any way to achieve it without changing the motor. Can I use capacitor bank to supply the transient currents for overcoming inertia quickly. Please don't downvote.
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3\$\begingroup\$ You want to maximize the acceleration. Acceleration is proportional to the torque, which is proportional to the current. So you want to maximize the current. To do so you will need a current controlling loop, providing as much voltage as needed to maintain the maximum allowed current. this is not a simple solution. \$\endgroup\$– Eugene Sh.Feb 3, 2017 at 18:03
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1\$\begingroup\$ You could also reduce the inertia by reducing the mass the motor has to drive. \$\endgroup\$– user16324Feb 3, 2017 at 18:20
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\$\begingroup\$ Start by specifying What you need Rpm(t), what you have and then it can be determined if it possible without compromising the rated input power or Amp-seconds or thermal rise. A 10kuF cap will help a 10 Ohm motor for a few hundred milliseconds and any useful cap will be 10x bigger and more expensive than the battery. \$\endgroup\$– Tony Stewart EE75Feb 3, 2017 at 19:42
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\$\begingroup\$ How are you controlling the motor? Which motor do you have, and how long is the 'little bit of time"? \$\endgroup\$– Bruce AbbottJul 7, 2017 at 3:02
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1\$\begingroup\$ "My requirement for a specific task is that the motor should reach the max speed as early as possible." - How quickly does it need to reach maximum speed? \$\endgroup\$– Bruce AbbottJul 7, 2017 at 3:07
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1 Answer
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If the battery is not delivering as much initial current as the motor can tolerate, a capacitor will help. A different battery might also help. If the motor only needs to overcome its own inertia, changing the motor will only help if you can find a motor with a higher ratio of torque to inertia. With a speed of 600 RPM, I suspect the motor includes a speed reduction gear. A gear that is more efficient would help.
To get the maximum rate of acceleration from a given motor, the only answer is the one given by Eugene Sh. "...you will need a controller that has a current controlling loop, providing as much voltage as needed to maintain the maximum allowed current."
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\$\begingroup\$ You could initially go to a much higher current than specified as running/load current. All motors of this type will have a stall rating maximum current which can be tolerated for at least a short while. You could for example use a capacitor, diode and FET switch to bump to double the voltage for a very short time. Size the capacitor to give the motor a good bump to overcome initial inertia. \$\endgroup\$ Feb 4, 2017 at 4:46