Safety and Best Practices for Operating a BLDC Motor*
Operating a BLDC (Brushless DC) motor using an electronic controller requires particular attention to safety and reliability.
Between high currents, thermal phenomena, and electromagnetic interference, rigorous implementation is essential to avoid failures and ensure the system's longevity.
Here are the main best practices to follow, from installation to commissioning.
1. Protective Equipment and Basic Precautions
Before any electrical or mechanical handling:
Wear PPE (insulating gloves, goggles, safety shoes).
Avoid any short circuit: always disconnect the power before connecting or disconnecting.
Respect the recommended torque settings for terminals and lugs to ensure good contact without crushing the conductor.
Check that the protection rating (IP) of the motor and controller matches the environment (dust, humidity, splashes).
These simple precautions prevent the majority of incidents during interventions.
2. Thermal Management of the Controller
The BLDC controller dissipates significant power, especially at high current or during continuous operation.
Ensure effective thermal contact between the controller casing and the machine chassis. Use thermal paste or a heat-conducting pad if necessary.
Avoid enclosed areas without ventilation: accumulated heat reduces performance and can trigger thermal protection.
Consider derating: current or power capacity decreases as ambient temperature rises. Always check the manufacturer's curves.
A well-cooled controller ensures stable operation and extends the lifespan of power components (MOSFET, IGBT…).
3. Power Cabling
The cabling between battery, controller, and motor is a critical element: it must minimise losses and limit electromagnetic disturbances.
Use cable lengths as short as possible between source, controller, and motor.
Choose suitable cross-sections for the maximum continuous and peak current, according to the standard or manufacturer's guide.
Provide a robust and well-secured ground return, common to all power points.
Physically separate power cables (motor phases, DC supply) from logic cables (signals, communication) to limit inductive coupling and interference.
4. Signal Cabling
Position or control return cables (Hall sensors, encoders, analogue/CAN controls) require special attention:
Twist the wire pairs (signal + return) for each sensor channel.
Shield the signal bundles, with a braid connected to the ground on one side only to avoid current loops.
Have a clean reference ground, separate from the power ground.
Avoid ground loops and prolonged parallel runs with power cables.
Care for the connections of Hall sensors or encoders: poor grounding or noise on the power supply can cause synchronisation losses or motor jerks.
The quality of signal cabling directly influences the control precision and system stability.
5. Regeneration and Energy Management
In regenerative braking mode, the motor acts as a generator and returns energy to the DC bus. This energy must be managed correctly:
If the power source is a battery, ensure it can absorb the regeneration (otherwise risk of overvoltage).
Provide a discharge resistor (braking resistor) connected via a braking chopper or a module integrated into the controller.
Implement a software strategy to limit or disable regeneration when the battery voltage approaches the maximum threshold.
On test benches or fixed supply systems, an energy absorber or dynamic load is often necessary.
Conclusion
The safety and reliability of a BLDC system rely on the combination of protective measures, rigorous cabling, and appropriate thermal and energy management.
By applying these best practices — PPE, ventilated controller, careful cabling, signal shielding, and regeneration management —, stable, quiet, and durable operation is ensured, while minimising the risk of incidents or failures.
*: The technical information presented in this article is provided for guidance only. It does not replace the official manuals of the manufacturers. Before any installation, handling, or use, please consult the product documentation and adhere to safety instructions. Torque.works cannot be held responsible for inappropriate use or incorrect interpretation of the information provided.