# How to find BLDC motor power and torque rating with torque constants and other given parameters

I am currently working on simulating a solar pv fed bldc motor in simulink software. I have the datasheet values of bldc motor from a iet journal as Number of poles, P = 6; rated speed, Nrated = 3000 rpm; stator resistance, Rs = 0.41 Ω; stator inductance, Ls = 2.13 mH; voltage constant, Ke = 78 VL-L/krpm.

But in Simulink I took the PMSM motor with trapezoidal back emf but I have option only to input the a) pole pairs b) Rs & Ls (phase to phase values), c) Voltage constant or torque constant or flux linkage as given in matlab documentation. Kindly check the link. I have no option to enter the rated power and speed of the bldc motor in simulation model.

1) In this case, if I enter the parameters that can be inputted to the model, then how we can find that motor with that given voltage constant (say 78 VL-L/krpm), Rs, Ls, pole pairs is a machine with rated speed of 3000 rpm?

2) Also, how to find the rated torque for this machine if the frequency of the input voltage to bldc motor from inverter is changed periodically based on gate pulses from hysteresis current controller?

I don't know much about the bldc motor & simulink so please go easy on me. If there is any specific relation that connects these terms kindly let me know.

• From the voltage constant and the speed, you can work out the rated voltage. Or from the constant and the voltage, you can work out the speed. From Power = V * I = Torque * Speed you can find a very simple relationship between the voltage constant and the torque constant : from the latter and the current you can derive the torque ( or from that and the torque, you can derive the current).
– user16324
Jan 20, 2022 at 14:52