The Rotrex C15-60 is a nice fit for the GM 2.8L V-6 that is my target engine. Conveniently the Rotrex datasheet give a moment of inertia for electric applications. The Rotrex C-15 has an internal planetary gear drive with a 12.67:1 ratio. The current concept is to run a direct drive and control the boost to 10 psi by varying the motor speed from 5000-10000 rpm. At 5000 motor rpm the impeller speed would be 63,350 rpm. The following equation applies:
torque (Nm) = moment of inertia (kg-m^2) * radians/second^2
63350 rpm is 6634 radians/second. To reach 63350 rpms in 1 second requires an acceleration of 6634 radians/sec^2
The moment of inertia for the Rotrex is 0.002057 kg-m^2. Therefore the required torque is:
Nm =0 .002057 * 6634 = 13.6 Nm which equates to 10.1 ft-lbs
I have looked at a NeuMotor outrunner model 8057/238. It produces 5.86 in-oz of torque per amp. This equates to 0.0305 ft-lbs/amp. Therefore the amps required to accelerate the compressor wheel to 63350 rpm in 1 second is 10.1 / 0.0305 = 331 amps. But we also have to consider the amps required by the compressor to compress air. At 5000 rpm and 10 psi 5.3 kW is required. If the motor is 90% efficient then 5.9 kW input is required. With a 50 volt supply this is 118 amps. So the total is 331 + 118 = 449 amps. To keep with a reasonable size ESC I'm thinking the motor needs to be ramped up in 2 seconds giving 283 total amps.
I'm a ChE faking it as an EE so it may be more complicated than this.
torque (Nm) = moment of inertia (kg-m^2) * radians/second^2
63350 rpm is 6634 radians/second. To reach 63350 rpms in 1 second requires an acceleration of 6634 radians/sec^2
The moment of inertia for the Rotrex is 0.002057 kg-m^2. Therefore the required torque is:
Nm =0 .002057 * 6634 = 13.6 Nm which equates to 10.1 ft-lbs
I have looked at a NeuMotor outrunner model 8057/238. It produces 5.86 in-oz of torque per amp. This equates to 0.0305 ft-lbs/amp. Therefore the amps required to accelerate the compressor wheel to 63350 rpm in 1 second is 10.1 / 0.0305 = 331 amps. But we also have to consider the amps required by the compressor to compress air. At 5000 rpm and 10 psi 5.3 kW is required. If the motor is 90% efficient then 5.9 kW input is required. With a 50 volt supply this is 118 amps. So the total is 331 + 118 = 449 amps. To keep with a reasonable size ESC I'm thinking the motor needs to be ramped up in 2 seconds giving 283 total amps.
I'm a ChE faking it as an EE so it may be more complicated than this.