BLDC Motor Torque Calculation Formula

BLDC Motor Torque Equation:

\[ T = \frac{P \times 9550}{N} \]

Torque (T):

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1. What is the BLDC Motor Torque Equation?

The BLDC (Brushless DC) motor torque equation relates the motor's power, speed, and torque. It's fundamental for motor selection and performance analysis in electromechanical systems.

2. How Does the Calculator Work?

The calculator uses the BLDC motor torque equation:

\[ T = \frac{P \times 9550}{N} \]

Where:

\( T \) — Torque in Newton-meters (Nm)
\( P \) — Power in kilowatts (kW)
\( N \) — Speed in revolutions per minute (RPM)
9550 — Conversion factor combining unit conversions and constants

Explanation: The equation shows that torque is directly proportional to power and inversely proportional to speed. The 9550 factor comes from unit conversions (1 kW = 1000 W, 1 minute = 60 seconds) and the relationship between angular velocity and RPM.

3. Importance of Torque Calculation

Details: Accurate torque calculation is essential for motor sizing, ensuring adequate starting torque, preventing overload conditions, and matching motor performance to application requirements.

4. Using the Calculator

Tips: Enter power in kW and speed in RPM. Both values must be positive numbers. For best results, use manufacturer-specified values under operating conditions.

5. Frequently Asked Questions (FAQ)

Q1: Why is 9550 used in the formula?
A: It's a conversion factor derived from: (60 seconds/minute) × (1000 watts/kW) / (2π radians/revolution) ≈ 9549.3, typically rounded to 9550.

Q2: What's the difference between stall torque and running torque?
A: Stall torque is the torque at zero speed (startup), while running torque is during operation. BLDC motors typically have high stall torque.

Q3: How does voltage affect BLDC motor torque?
A: Torque is directly proportional to current. Higher voltage allows more current (within limits), thus increasing potential torque output.

Q4: What are typical torque values for BLDC motors?
A: Small BLDC motors might produce 0.01-0.1 Nm, while industrial motors can reach hundreds of Nm, depending on size and design.

Q5: How accurate is this calculation?
A: It provides theoretical maximum torque. Actual torque may be lower due to efficiency losses, temperature effects, and controller limitations.