- The Sanqiang Electric Tricycle Doesn’t Start When Turning the Throttle Grip After Turning on the Key, While the Lights Are Normal
Fault Phenomenon: After turning on the key and turning the throttle grip, the vehicle doesn’t start, but the lights can be controlled.
Analysis and Maintenance: Suspect that the part in the vehicle that controls the motor is abnormal. Measure the B + 36V, U2 and U4 outputs in the control box and find them to be normal. However, there is no potential difference between the two ends of the motor M + and M?. This indicates that the controller is abnormal. After replacing the controller, the electric tricycle operates normally.
- The Motor of the Freight Electric Tricycle Doesn’t Rotate
Fault Phenomenon: The motor doesn’t rotate.
Analysis and Maintenance: Check that the 24V power supply is normal. Open the controller and measure that the 15V voltage is very low. Remove the voltage stabilizing diode VS1 in the controller and measure its forward and reverse resistances, which are found to be very small, indicating that VS1 is damaged. Observe that the appearance of VS1 is very small, indicating that the power of VS1 is small. Replace it with a voltage stabilizing diode with parameters of 15V / 1W, and the 15V power supply returns to normal. Turn the throttle grip, and the output voltage is very low and remains unchanged. Upon inspection, it is found that there is an open circuit in the output lead of the throttle grip. Reconnect it properly and the fault is eliminated.
- The Motor of the Freight Electric Tricycle Doesn’t Rotate
Fault Phenomenon: The motor doesn’t rotate.
Analysis and Maintenance: Detect that the voltages of 24V, 15V and 5V are normal under no-load conditions. When turning the throttle grip, measure that the gate voltages of V1 and V2 in the controller are very low. Solder off the gate leads of V2 and V2, and measure the output voltage of the operational amplifier block, which is 14V and normal. Suspect that V1 and V2 are damaged. However, after removing and testing them, V1 and V2 are found to be normal. Connect the 24V power line directly to the two ends of the motor, and the motor still doesn’t rotate. At this time, measure that the voltage at both ends of the power supply is very low. Finally, check the leads and find that the battery wire clips are oxidized, resulting in a large contact resistance. When the motor doesn’t rotate, because the output current is small, the voltage drop caused by the contact resistance is small, so the voltages of all circuits are measured to be normal. However, when loaded, the motor current increases, and the voltage drop formed by the contact resistance increases, causing the voltage at the power supply end to decrease and not enough to make the motor rotate. After removing the oxides on the wire clips, the fault is eliminated. It can be seen that when checking voltages, attention should also be paid to different load conditions to avoid taking detours.
- The Motor of the Freight Electric Tricycle Doesn’t Rotate
Fault Phenomenon: The motor doesn’t rotate.
Analysis and Maintenance: Measure that the 24V, 15V and 5V power supplies are normal. When turning the throttle grip, the output voltage changes normally between 1.2 and 4.0V. However, measure that the output voltages of the operational amplifier blocks A1, A3 and A4 remain unchanged. After testing, it is found that the operational amplifier LM324 is broken. After replacing it, the output voltages of pins ①, ⑧ and ⑩ change normally, while the motor still doesn’t rotate. Remove and test V1 and V2 and find that they are damaged. After replacing them, the fault is eliminated.
- Fault of the Motor of the Freight Electric Tricycle That Keeps Rotating
Fault Phenomenon: The motor keeps rotating.
Analysis and Maintenance: When the power is connected, the controller gets out of control and the motor keeps rotating. Disconnect the power supply, open the controller and conduct separate inspections. V1 and V2 are normal, but the lower diode VD1 is broken down and short-circuited. At this time, the power supply directly reaches the motor through VD1, causing the motor to keep rotating. After replacing the diode VD1, the motor operates normally.
- Fault of the Motor of the Freight Electric Tricycle That Rotates with Small Output Torque and Big Sparks
Fault Phenomenon: The motor rotates, but the output torque is small and there are big sparks.
Analysis and Maintenance: After measuring the power supply and control circuit and finding them to be normal, it is judged to be a motor fault. When the motor is disassembled for inspection, it is found that the carbon brushes are seriously worn. When the rotor is pulled out, it is found that the commutator is unevenly worn, with the difference between the highest and the lowest points being more than 1 mm. The uneven wear of the commutator makes the sparking more serious and results in a small output torque. This kind of fault is most commonly seen in motors with two sets of carbon brushes, while it is rare in motors with one set of carbon brushes. Remove the bearings, clamp the end of the rotor shaft in the rotor, commutator and electroplating machine for processing. After the surface of the rotor commutator is processed, grooves are cut, and nickel-tungsten alloy is brush-plated to obtain a wear-resistant protective layer, making the surface of the commutator smooth and greatly reducing the wear of carbon brushes. Finally, remove debris such as carbon powder and dust, assemble the motor properly, and the fault is eliminated.