Loading... Please wait...
Power Supply Selection
- Determine Motor Current Requirements • Check the motor datasheet for its rated current per phase (e.g., 1.5 A/phase). • Multiply by the number of phases (typically 2 for bipolar steppers) to get the total motor current (e.g., 1.5 A × 2 = 3 A). • Add a 20–30% safety margin to ensure the power supply can handle peak demand. • Note: Modern stepper drivers regulate current and use a higher supply voltage than the motor’s rated voltage. The driver effectively steps the voltage down to the motor’s voltage, which means the current drawn from the power supply is lower than the sum of the motor phase currents. • A good rule of thumb is to size the power supply current rating at about 50% of the total motor current (after adding the safety margin). This typically provides enough headroom while avoiding an oversized supply.
- Select the Correct Voltage • Stepper drivers regulate current, so the supply voltage can be much higher than the motor’s rated voltage for improved performance. • Higher voltage helps the motor maintain torque at higher speeds because it allows current to rise faster in the windings. • Always stay within the driver’s maximum voltage rating (e.g., 24–48 V). • Rule of thumb: Choose a supply voltage that is 10–20× the motor’s rated voltage (within driver limits).
- Calculate Power Rating (Wattage) • Power (W) = Supply Voltage × Estimated Supply Current (from Step 1). • Add 30% margin for startup, acceleration, and transient loads. • Example: o Motor: 3 V, 2 A/phase (total = 4 A) o Estimated supply current ≈ 4 A × 0.5 = 2 A o At 24 V supply → Power ≈ 24 V × 2 A = 48 W o Add 30% margin → choose a 60–70 W power supply.
- Choose the Right Type of Power Supply • Switching Power Supply (SMPS): Compact, efficient, and cost-effective — the most common choice for CNC, robotics, and 3D printing applications. • Linear Power Supply: Bulkier but produces very low electrical noise and can handle current surges more gracefully. Best for sensitive analog applications.
- Other Considerations • Cooling: Ensure proper airflow or heat sinking for long-term reliability. • Headroom: For longer life, operate the power supply at about 70–80% of its maximum rating. • Multiple Motors: When powering multiple motors, sum their estimated supply currents (using the 50% rule) before adding margin to size the supply correctly.