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Typical Stop Loss Case of Brushless Motor

2023-12-11 17:31

The brushless DC motor is composed of a motor body and a driver, which is a typical mechatronic product. Since the brushless DC motor is self-controlled operation, it will not add another starting winding on the rotor like a synchronous motor that starts under heavy load under variable frequency speed regulation, nor will it produce oscillation and out-of-step when the load changes abruptly. The permanent magnets of small and medium-sized brushless DC motors now use rare earth neodymium iron boron (Nd-Fe-B) materials with high magnetic energy product. Therefore, the volume of rare earth permanent magnet brushless motor than the same capacity three-phase asynchronous motor reduced a seat number.

Servo motors are widely used, but after long-term operation, various failures will occur. Timely judgment of the cause of the failure and corresponding treatment is an important task to prevent the expansion of the failure and ensure the normal operation of the equipment.

The main faults and analysis are as follows:

1. motor encoder alarm

1. Causes of failure

① Wrong wiring;

② Electromagnetic interference;

③ Damage of encoder hardware caused by mechanical vibration;

④ Pollution caused by site environment;

2. Troubleshooting

① Check the wiring and eliminate errors;

Check whether the shielding is in place, check whether the wiring is reasonable and solve, if necessary, increase the filter to improve;

③ Check the mechanical structure and improve it;

Check whether the internal encoder is contaminated, corrosion (dust, oil, etc.), strengthen protection;

3. Installation and wiring standards

① Try to use the original cable;

② Separate the cable as far as possible away from the contaminated wiring, especially the highly contaminated wiring;

③ Always use the internal power supply as much as possible. If a switching power supply is used, a filter should be used to ensure that the power supply reaches a clean level;

④ Always ground the common terminal;

⑤ Keep the encoder housing insulated from the machine structure and connected to the cable shielding layer;

⑥ If the encoder cannot be insulated, the cable shield can be connected to the ground (or dedicated terminal) on the encoder housing and drive frame.

Broken shaft of 2. motor

1. Causes of failure

① Unreasonable mechanical design leads to excessive radial load force;

② The load terminal is stuck or severely overloaded instantaneously;

The motor and reducer assembly is not concentric;

2. Troubleshooting

① Check the large radial load force that can be borne by the motor sample and improve the mechanical design;

Check the operation of the load end, confirm the actual process requirements and improve them;

Check whether the load operation is stable, whether there is vibration, and improve the mechanical assembly accuracy.

3. motor no-load current imbalance, three-phase difference is large

1. Causes of failure

① Wrong connection of winding head and tail end;

② Unbalance of power supply voltage;

③ Winding has inter-turn short circuit, coil reverse connection and other faults.

2. Troubleshooting

① Check and correct;

② Measure the power supply voltage and try to eliminate the imbalance;

③ Eliminate winding faults.

Abnormal noise during operation of the 4. motor

1. Causes of failure

① Bearing wear or oil in the sand and other foreign matter;

② Loose rotor core;

③ Lack of bearing oil;

The power supply voltage is too high or unbalanced.

2. Troubleshooting

① Replace the bearing or clean the bearing;

② Overhaul the rotor core;

③ Refueling;

Check and adjust the power supply voltage.

The 5. motor is difficult to start, and the motor speed is much lower than the rated speed at rated load.

1. Causes of failure

① The power supply voltage is too low;

② Misconnection of surface connection motor;

③ Open welding or fracture of rotor;

④ The local coils of the rotor are misconnected or reversed;

③ Increase the number of turns too much when repairing the motor winding;

⑤ Motor overload.

2. Troubleshooting

① Measure the power supply voltage and try to improve it;

② Correct connection;

③ Check the weld opening and breakpoint and repair;

④ Find out the wrong connection and correct it;

⑤ Restore the correct number of turns;

⑥ Load shedding.

After the 6. is energized, the motor cannot rotate, but there is no abnormal noise, odor and smoke.

1. Causes of failure

① The power supply is not connected (at least two phases are not connected);

② Fuse blowing (at least two-phase blowing);

③ Overcurrent relay is adjusted too small;

④ Control equipment wiring error.

2. Troubleshooting

① Check whether there is a breakpoint at the power circuit switch, fuse and junction box, and repair it;

② Check the type of fuse and the cause of fusing, and replace the fuse with a new one;

③ Adjust the relay setting value to match with the motor;

④ Correct the wiring.

Large motor vibration during 7. operation

1. Causes of failure

① The bearing clearance is too large due to wear;

② Uneven air gap;

③ Unbalance of rotor;

④ The shaft is bent;

⑤ The coupling (pulley) is too low coaxially.

2. Troubleshooting

① Check and repair the bearing and replace it if necessary;

② Adjust the air gap to make it uniform;

③ Correct rotor dynamic balance;

④ Straighten the rotating shaft;

⑤ Recalibrate to make it conform to the regulations.

After the 8. is energized, the motor does not turn and there is a buzzing sound.

1. Causes of failure

① The rotor winding is open (one phase is broken) or one phase of the power supply is lost;

② Wrong connection at the beginning and end of the lead wire of the winding or reverse connection inside the winding;

③ Loose contacts of power circuit and large contact resistance;

④ The motor is overloaded or the rotor is stuck;

⑤ The power supply voltage is too low;

The small motor assembly is too tight or bearing grease is too hard;

⑦ The bearing is stuck.

2. Troubleshooting

① Find out the breakpoint and fix it;

Check the polarity of the winding; judge whether the end of the winding is correct;

③ Tighten the loose wiring screws, use a multimeter to determine whether each joint is false, and repair it;

④ Load shedding or detecting and eliminating mechanical faults,

⑤ Check whether the specified surface connection method is misconnected; If the voltage drop is too large due to the thin power supply wire, correct it,

⑥ Reassemble to make it flexible; replace qualified grease;

⑦ Repair the bearing.

9. bearing overheating

1. Causes of failure

① Too much or too little grease;

The oil quality is not good and contains impurities;

The bearing and journal or end cover with improper (too loose or too tight);

④ The inner hole of the bearing is eccentric and rubs against the shaft;

⑤ The motor end cover or bearing cover is not installed flat;

The coupling between the motor and the load is not calibrated, or the belt is too tight;

⑦ The bearing clearance is too large or too small;

⑧ The motor shaft is bent.

2. Troubleshooting

① Add grease as required (1/3-2/3 of the volume);

② Replace the clean lubricating grease;

③ If it is too loose, it can be repaired with adhesive. If it is too tight, it should be used to grind the journal or the inner hole of the end cover to make it suitable;

④ Repair the bearing cover and eliminate the rubbing point; For more exciting content, please pay attention to the micro-signal technical training.

⑤ Reassembly;

⑥ Recalibrate and adjust the belt tension;

⑦ Replace the new bearing;

⑧ Correct the motor shaft or replace the rotor.

10. motor overheating and even smoke

1. Causes of failure

① The power supply voltage is too high;

② The power supply voltage is too low, the motor runs with rated load, and the current is too high to cause the winding to heat up;

③ When repairing and dismantling the winding, the hot dismantling method is improper and the iron core is burned;

④ Motor overload or frequent starting;

⑤ Motor phase loss, two-phase operation;

⑥ Insufficient dipping paint for winding after rewinding;

⑦ high ambient temperature motor surface dirt, or air duct blockage.

2. Troubleshooting

① Reduce the power supply voltage (such as adjusting the tap of the power supply transformer);

② Increase the power supply voltage or replace the thick power supply wire;

③ Repair the iron core and eliminate the fault;

④ Load shedding; control starting according to the specified times;

⑤ Restore three-phase operation;

Adopt secondary dipping and vacuum dipping process;

⑦ Clean the motor, improve the ambient temperature, and adopt cooling measures.

Shaoxing Hengli Motor Co., Ltd.

Telephone:86-575-84382698 ;

Address: Beigong Road, Hutang Industrial Zone, Keqiao District, Shaoxing City, Zhejiang Province

Address: Building D, Lian Shang Zhizao Industrial Park, Gaocheng Town, Dongguan City, Guangdong Province

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