Common Faults and Solutions of BLDC Motors

Introduction

Although BLDC motors are highly efficient and increasingly widely used, some neglected issues can also cause motor failures, thereby resulting in downtime and maintenance costs. Which motor faults troubles you the most? Below are methods for how to diagnose and repair these common motor faults.

Fault 1: Motor Overheating

Symptoms: Housing temperature >80°C, abnormal odor, performance degradation

Common causes:

(1) Overload operation (current exceeding the rated value)

(2) Poor heat dissipation (dust blockage/fan failure)

(3) Damage to internal components

(4) Improper controller settings

Solutions:

1. Load inspection: Use a clamp meter to measure the actual current, and ensure the motor's load is within its rated range. If the load is too heavy, it can be solved by reducing the load or replacing it with a higher-power motor.

2. Optimize heat dissipation: Remove dust from cooling devices and ensure proper operation of cooling fans, radiators, and other equipment. If the motor is in a closed environment, consider adding vents or improving air circulation.

3. Inspect the motor's internal components, check and replace worn parts.

4. Check and adjust the controller settings according to the technical manuals of the motor and controller. Ensure that parameters such as PWM frequency, speed limit and current limit meet the motor's rated requirements. If the controller supports firmware updates, try updating the firmware to obtain more optimized control algorithms.

Fault 2：Abnormal Noise/Vibration

Symptoms: high-frequency whistling, mechanical impact noise, resonance

Common causes:

1. Bearing wear (accounting for 70% of failures)  

2. Mechanical unbalance  

3. Electromagnetic unbalance  

4. PWM frequency interference  

5. Installation issues

Solutions:

1. Regular inspection and maintenance of motor bearings, including lubrication and replacement of worn components, to ensure the bearings are in good condition.

2. Dynamic balance correction: Check the mass distribution of the motor rotor and related components, and perform necessary adjustments or balancing treatments to ensure their symmetry.

3. Electromagnetic adjustment: Regularly maintain and inspect the winding status, and conduct current balancing adjustments.

4. Detect PWM harmonic frequencies and identify mechanical resonance points. If immediate shutdown for maintenance is not feasible, emergency measures can be taken such as temporarily reducing the motor load to 70% of the rated value, attaching copper foil tape to the controller housing (temporary shielding), and connecting magnetic beads in series on PWM output lines. In the later stage, the problem can be solved through methods like hardware optimization (cutting off interference paths), software parameter adjustment (eliminating excitation sources), and mechanical damping (suppressing vibration propagation).

5. Regularly inspect the motor's installation status to ensure the mounting base is flat and fasteners are secure.

Fault 3：Start-up failure/jitter

Symptoms:

The motor jitters and then shuts down, with a surge in starting current.

Common causes:

1. Hall sensor failure (incorrect position signals)

2. Mechanical resistance abnormality

3. Control parameter mismatch

Solutions:

1. Replace the Hall sensor, reset the installation position, and align the center of the sensor with the magnetic pole boundary (with an error of ±0.5mm).  

2. Conduct regular bearing maintenance: inject high-temperature grease after cleaning, or replace with ceramic bearings. Reduce starting load: install an additional soft starter (with a slow start time of 0.5-2s), or switch to closed-loop vector starting (FOC algorithm).  

3. Parameter adjustment

Conclusion

Regular motor inspections can help identify and resolve potential issues early, ensuring efficient motor operation and reducing maintenance costs and productivity. If you have any further questions or brushless DC motor needs, please contact us via email or WhatsApp. We offer professional support to help you resolve technical issues.