Common Technical Issues And Applications of Brushless Gear Automatic Door Motors

（一）

Common Technical Issues with Brushless Automatic Door Motors (BLDC)

(一）The motor won't start / it shakes and buzzes when powered, can't open the door

1. Hall Sensor Failure (Most Common)  

• Symptoms: Vibrates or buzzes when powered on, needs a manual push to start turning; sometimes it starts, sometimes it doesn't.  

• Causes: Abnormal 5V supply to Hall sensor, loose connector due to vibration, damaged Hall element, incorrect Hall phase wiring. Brushless motors rely on Hall sensors for commutation, so any Hall issue directly causes phase loss.  

• Checks: Resistance between each pair of the three-phase power lines should be roughly the same; measure the three Hall signals while turning the shaft, all three should alternate between high and low.

2. Winding Phase Loss / Inter-turn Short / Disconnection  

   Symptoms: Buzzing with low power, high current, heats up quickly. Measure U/V/W three-phase resistances with a multimeter; if values are unbalanced, it’s a winding issue.

3. Mechanical Jam or Overload  

    Wheel jammed, track deformed, belt too tight, door too heavy, foreign objects stuck. First, manually push or pull the door to check mechanical resistance.

4. Power Supply and Wiring  

    Large voltage drop on 24V supply, insufficient wire gauge, reversed power and Hall signal lines, loose terminals.

5. Controller Drive Transistor Damage  

    Motor itself is fine, but the driver MOSFET failed, so there’s no output.

（二）. Lagging operation, intermittent shutdown, sudden stops

1. Hall harness loose connection / vibration signal break: The door shakes back and forth, connector pins make poor contact, Hall signal is lost during operation, the controller triggers protection and shuts down, and after power cycling it works briefly.  

2. Overcurrent protection: Door operation becomes harder, current exceeds the limit, controller shuts down to protect.  

3. Overtemperature protection: Frequent long-term door opening/closing, poor heat dissipation, motor temperature exceeds limit, automatically shuts down and recovers after cooling.  

4. Partial demagnetization of permanent magnets: Long use, high temperature impact, torque fluctuates a lot, low-speed section jumps.  

5. Encoder abnormality (for encoder models): Position feedback loses pulses, causing misalignment and incorrect positioning.

（三）. Strange Noise and Strong Vibration

1. Bearing Damage: Periodic clicking or rumbling friction sounds, dried-out grease, pitting. Most noticeable at low speed; a common mechanical issue.

2. Gearbox Problems: Worn gears, too much clearance (backlash), lack of oil, strong impact vibration when the door closes fully.

3. Poor Rotor Balance or Misaligned Axis: Vibration obvious at high speed.

4. Tuning Parameter Issues: PI parameters set improperly, causing start-stop oscillation, door shaking; not a hardware problem with the motor itself.

（四）. Motor Overheating Problems

• Overload: The door is too heavy, the track resistance is high, or the trolley wheel is stuck, causing continuous high current.

• Voltage deviates from the rated value, and the power supply is unstable.

• Slight short circuits between winding turns, increasing losses.

• High start-stop frequency (like in busy shopping areas), duty cycle exceeds limits.

• Normal temperature rise ≤60K; if the casing stays above 85℃ for a long time, it's abnormal and can speed up permanent magnet demagnetization and insulation aging.

（五）. Abnormal Speed: Door opening/closing speed is off, low-speed shaking, big impact when done

1. Controller parameter tuning problems (most common)  

  Acceleration, deceleration, and cushioning segment parameters are not suitable; deadband time or PWM frequency settings are wrong, causing low-speed shaking.  

2. Hall phase direction set incorrectly: opening and closing speeds are uneven, direction reverses. Just reset the Hall direction parameters to fix it; the motor itself is fine.  

3. Supply voltage drop: Voltage drops when current is high, preventing the top speed from being reached.  

4. Belt slipping or unstable load, making the speed seem fast and slow.  

（六）. Anti-pinch and torque problems, can’t push / reverses on touch

1. Torque threshold parameter set wrong: if torque is too low, even slight resistance triggers reversal; if torque is too high, anti-pinch fails, posing a safety risk.  

2. Current sensing abnormality (controller), can’t correctly detect stall current.  

3. Hall/encoder position feedback inaccurate, leading to wrong stall recognition.

(二）

Our brushless gearbox automatic door motors are widely used in various automatic door systems because they offer low noise, long life, no-brush maintenance, precise speed control, reverse protection when obstructed, and no carbon dust pollution, making them ideal for high-traffic, frequently used doors where cleanliness and quietness are important。

1. Commercial Buildings (Most Common)

Shopping malls, supermarkets, chain stores: glass sliding automatic doors  

Office buildings, hotel lobbies, convention centers: sliding doors, automatic swing doors, revolving doors  

Bank halls: anti-pinch automatic sensor doors, access-controlled automatic doors  

Features: high foot traffic, frequent daily operation, requires quiet, stable, and anti-pinch safety。

2. Healthcare and Clean Environments

Hospital operating rooms, ICUs, ward airtight doors, clean sliding doors

Laboratories, pharmaceutical workshops, dust-free food workshops clean doors

Advantages: no carbon dust, low noise, won’t contaminate clean environments, smooth opening and closing maintains room pressure differences, suitable for medical staff and patient areas

3. Transportation Infrastructure

Airports, high-speed rail stations, bus terminals: entrance/exit sensor doors, ticket gates, fast doors

Subways: platform screen doors / safety doors, automatic doors in station passages

Features: designed for continuous high-load operation around the clock, can be integrated with signal systems

4. Industry and Warehousing

Automatic sliding doors, high-speed rolling doors, and electric doors for cleanrooms in factory workshops

Automatic passage doors, heavy-duty industrial automatic doors for logistics warehouses

Heavy-duty brushless motors can drive very heavy door panels and support frequent opening and closing

5. Security and Access Control

Automatic doors for access control in enterprises and institutions, anti-tailgating speed gates, interlocking doors (airlock rooms)

High-security automatic doors for data centers, vaults, etc., can be linked with access control and fire alarms

Supports precise position control, fire mode unlocking, and anti-pinch safety reverse

6. Public Buildings

Automatic swing doors and accessible automatic doors for libraries, museums, government service halls, schools, and gyms, balancing quiet operation and accessibility.

7. Residential and Smart Homes

Automatic doors for high-end residential units, automatic swing/pocket doors for villa courtyards, and electric sliding doors for balconies.

8. Other Categories

Elevator cabin door motors, small automatic opening mechanisms for self-service equipment doors (ATMs, vending machines), etc.