PXID analyzes the principle and maintenance of common motors for folding electric bicycles
PXID takes you to analyze the principle and maintenance of common motors for folding electric bicycles
1. There are windings and magnetic steel in the motor. When current is passed through the winding, a magnetic field will be generated. This magnetic field interacts with the magnetic field of the magnetic rigidity, causing the rotor to rotate.
2. Generally speaking, the speed of the motor is related to the structure of the motor and the external voltage. The more the coil turns, the slower the speed, and the fewer the turns, the faster the speed. The weaker the magnetic field strength of the magnet, the larger the air gap between the stator and the rotor, the faster the speed, but the smaller the torque. The higher the voltage applied to the motor, the faster the speed.
3. Maintenance procedures for brushed low-speed motors
1. Turn off the power
2. Rotate the motor by hand, under normal circumstances, there is no jamming when rotating forward, and there is even electromagnetic resistance when rotating backward.
3. How to judge the brush fault: Reverse the motor. If the electromagnetic resistance changes significantly (sometimes tight, sometimes loose), it means that the brush is in poor contact. You can use the resistance gear to detect the on-off condition of the coil for further testing.
4. Magnet failure judgment method: reversing the motor, if the electromagnetic resistance is obviously too small, it means that the magnet is demagnetized (or the magnet is arranged incorrectly). If necessary, further check whether the idling current is too large.
5. Coil short-circuit fault phenomenon: (disconnect the connection between the motor and the controller)
(1) Separate the motor wires, there are obvious electromagnetic resistance for forward, reverse and motor
(2) Short circuit between the motor wire and the motor shell (excluding wire breakage and grounding)
(3) Short-circuit the motor line, forward and reverse, the electromagnetic resistance increases less than that when the circuit is open.
(4) The motor wire is short-circuited, forward and reverse, no electromagnetic resistance or extremely weak electromagnetic resistance and high idling current
(5) Use a multimeter to detect the power generation of the motor at the 20V voltage range. If the motor has no voltage or the voltage is extremely low, it is judged as a short circuit.
4. Repair method of brushed motor
(1) Standards for changing brushes and brush holders:
A. The brush must be completely consistent with the brush holder: flexible, no jamming, no excessive shaking
B. The lead wire of the brush should be long enough, so that the brush can completely emerge from the brush holder.
C. The elastic force of the brush spring should be large enough and the two elastic forces should be even
D. The brush holder should be aligned. Follow the five-point-one-line principle
(2) Cleaning of commutator
A. Polish the commutator surface with sandpaper first, and polish the uneven commutator more
B. Use a hacksaw blade to remove the carbon deposits in the commutator's small groove, and polish the commutator again
C. Clean the dust and impurities inside the motor.
(3) Maintenance of magnets
A. Use magnets to detect whether the magnetic field strength and polarity direction of each magnet are normal and record
B. If the magnetic field of the magnet is weak, the magnet with the same polarity and size must be replaced
C. If there is a mistake in the order of the magnetic steel, rearrange and stick it firmly
(4) Inspection and repair method for magnetic steel falling off
A. Collect all the fallen magnets and place them on the iron frame to prevent the magnets from being crushed by gravity
B. Test the bonding strength of the magnetic steel that has not fallen off
C. The ones with insufficient strength should be removed, and the impurities on the surface of the stator and the surface of the magnetic steel sheet should be cleaned up. Until the surface is bright and free of impurities, it cannot be polished with a grinder. Check whether the order of the magnets is correct, number the magnets, and use spacers to determine the size of the interval between the magnets
D. Evenly blend AB glue and spread it on the magnetic steel sheet. Install the magnet to the corresponding position. After the glue is basically shaped, the next piece of magnetic steel should be bonded. In principle, the principle of diagonal priority should be adopted
E. After all the magnets are bonded, add glue at the space between the magnets, and wipe off the excess glue in time
F. After the glue is completely shaped (30-60 minutes), confirm that there is no glue, dirt, iron filings, etc. on the outer surface of the magnet. Assemble the motor and check the idling current. Those who do not meet the standards should be overhauled again
(5) Overhaul of coil
A. When a partial short circuit of the coil is detected, it should be observed whether the iron core is deformed and restored
B. If the coil has a slight electric leakage, it can be repaired by the redo insulation method
(1) Drying coil
(2) Immerse in lightweight insulating paint
(3) Drying, assembling, and detecting idling current
(4) If a short circuit is caused by the displacement of the commutator, you can try to change the position of the commutator and check at the same time. When the short circuit is eliminated, you can use the redo insulation method for reprocessing
Five, brushed high-speed motor detection program
1. Detection of clutch and deceleration system:
A. The forward-rotating motor should be easy and free from jamming.
B. Reversing motor should have great resistance (larger than brushed low-speed motor) and no jamming phenomenon
2. Electric brush detection:
Use a multimeter to test whether the motor line is connected
3. Coil detection:
A. Reverse the motor to measure the power generation of the motor: low voltage and short circuit, high voltage is normal
B. Measure the idling current: the current is large and the short circuit is small, and the current is small.