🚀 Motor Selection Calculator & Simulator
- Input Driving Load Variables: Set the drum diameter (radius R) and object mass (M) to determine the moment of inertia.
- Set Dynamic Target Values: Input the target speed (RPM) to be reached and the acceleration time (sec) from standstill to target speed.
- Define Friction & Efficiency: Input the friction coefficient (μ) of the mechanical transmission and the transmission efficiency (%) of the gear reducer/motor.
- Observe Real-Time Load Rotation Animation: Monitor the motor overload heating (glowing) in the acceleration phase and the real-time torque-speed state graph curve to select the recommended motor specification.
📚 Check Detailed Mechanical & Electrical Engineering Motor Capacity Calculation Formulas ▼
1. Key Engineering Elements of Motor Selection
The most frequent design error when selecting industrial motors (induction motors, servo motors, etc.) is the underestimation of the moment of inertia and acceleration torque. The total load torque that the motor must drive is determined by the sum of the static torque required for constant-speed driving and the dynamic acceleration torque required during acceleration.
- Moment of Inertia (J): A measure of resistance to rotation based on the mass distribution of the rotating object. For a cylindrical drum shape, it is defined as J = 0.5 * M * R^2.
- Static Friction Torque (T_static): The basic torque required to overcome mechanical friction and external forces of the transmission part and maintain a constant speed.
- Acceleration Torque (T_accel): The torque required to accelerate the inertial mass to the target speed according to Newton's second law of rotation (T = J * α). The shorter the acceleration time, the exponentially larger the required torque becomes.
2. Governing Equations for Moment of Inertia, Torque, and Required Power (kW)
The official design steps to analyze load dynamics and obtain the motor output specification are as follows:
① Calculation of Load Moment of Inertia (J):
J = 1/2 × M × R^2 [kg·m^2] (Based on cylindrical drum shape)
② Calculation of Angular Acceleration (α) and Acceleration Torque (Ta): The average torque required to reach the target angular velocity ω during the acceleration time t_accel.
ω = 2 π × N / 60 [rad/s] | α = ω / t_accel [rad/s^2]
T_accel = J × α [N·m]
③ Calculation of Power Consumption and Required Motor Power (P): The required motor power considering the efficiency (η) and a safety factor (SF, typically 1.2 times).
P_req = (T_total × ω) / (η × 1000) × SF [kW]
3. Standard Power Ratings for Electric Motors (IEC/KS)
Based on the calculated required power (kW), the rated power of commercially available standard motors must be selected during actual mechanical design. The standard rated outputs of typical three-phase induction motors according to IEC standards are as follows:
- Low Power: 0.2 kW, 0.4 kW, 0.75 kW, 1.5 kW, 2.2 kW, 3.7 kW
- Medium Power: 5.5 kW, 7.5 kW, 11 kW, 15 kW, 18.5 kW, 22 kW, 30 kW, 37 kW
During selection, cross-verification must be performed to ensure that the peak torque of the load (maximum torque at startup) falls within the motor's starting torque and breakdown torque limits to prevent overheating and burnout during long-term operation.