I want to convert my Voltage Constant (Kv) of V/rad/s to V/Krpm, how do I do that?
A. Most motors are rated in V/Krpm, Volts per 1000 rpm, so some calculation is needed to arrive at these units when you are given V/rad/s, Volts per Radians per second. If for example, the motor has a 0.49V/rad/sec, we need to first convert the radians to degrees. So we know that there is approximately 6.28 radians per revolution, we can say the Kv is 0.49V/(1/6.28 revolutions)/sec, or 0.49V/0.159revs/sec. Converting to rpm, we multiply the denominator by 60 results in 0.49V/9.58rpm. To get Krpm, we take 1000 and divide it by 9.58 rpm, which will be 104.4, and multiply this result times the numerator and denominator to get 51.15V/Krpm. You can now compare the voltage constants with other motors that use the same units.