General troubleshooting of brushless DC motor controller

1. The following controller is for PIC16F72 microcontroller

The static current of the controller should be within 50MA. The current of the motor at the highest speed without load is generally around 1.4A, and some motors are around 1.8A. When the control panel does not work, first check the signal light on the panel flashing every second. If the signal light does not flash without the turn signal, check:

1. Check whether the 5V voltage is normal. If it is abnormal, check whether there is a short circuit in the external connector, whether there is a tinned short circuit on the board, etc.;

2. Is the voltage of the second pin of the microcontroller 5V?

3. Is the quartz crystal working?

4. Check whether the signal light is damaged.

2. Controller current and voltage adjustment

1. Current adjustment: adjust the constantan length (the new program can adjust the resistance (R6) of the LM358's 6th pin to ground, the value range is 2K to 3.3K, and adjust to the required operating current. (The old program of 500W has a better operating effect at 26A to 35A, and the new program has a better effect at 22A to 28A.)

2. Voltage adjustment: The undervoltage sampling circuit is composed of two voltage-dividing resistors between a 48V or 36V power supply and ground. Usually, the undervoltage point can be adjusted by adjusting the resistance (Ra) connected to the power supply. Since the resistance connected to the ground is usually 1.2K, the undervoltage value and the resistance value can be calculated according to the following formula: Ra=(1.2xv-1.2x3)/3

Example: When using a 48V battery voltage and the undervoltage V value is 40.5:

Ra=(1.2x40.5-1.2x3)/3------→Ra=15K

Note: 1.2 is the resistance connected to the ground. 3 is the AD value of the undervoltage processed by the microcontroller.

When the undervoltage value needs to be adjusted between 40.5V and 42V, when the full load 1.2K resistor is connected in parallel with 82K, 39K, 36K, 33K, and 30K, the undervoltage corresponds to: 41.04V, 41.65V, 41.75V, 41.86V, and 42V respectively.

3. When the single-chip microcomputer on the control board can work (the signal light should flash without turning the handle), but it cannot work normally, please pay attention to the flashing state of the signal. The common flashing states are listed below:

1. The weak signal control part works normally about once per second;

2. Slow flash twice, the circuit is in braking state;

3. Slow flash 3 times from Constantan to LM358 indicates incorrect parameters or open circuit;

4. Slow flash 4 times. There is a fault in the upper bridge, driver and output MOS.

5. If the lower bridge, driver, and output MOS flashes slowly for 5 times, there is a fault;

6. Slow flash 6 times, 60 degrees, 120 degrees, the selection and motor Hall phase sequence connection are incorrect;

7. During the slow flash 7 times operation, the current is too large for protection, the reference level of the constantan is too long or short circuit detection is too low (the normal value is 20K to 1.2K voltage division):

8. Slow flash 8 times under voltage status

9. Flash twice quickly to wait for the handle to return to zero (power-on anti-runaway function)

10. Flashes quickly 3 times, the motor stops rotating;

11. The signal light flashes when the motor is rotating, the Hall wire is broken or the phase is missing, or the motor is not matched.

The other three faults can be repaired by combining the above conditions:

1: The motor does not rotate:

a: Insufficient voltage, test whether the voltage of the MCU's third pin is greater than 3.2V;

b: Check whether the brake level connection is normal, check the 7th pin of MCU, high level brake as long as the voltage is higher than 2.5V; low level brake voltage is lower than 2.0V;

c. Whether the speed regulating voltage is added to the 5th pin of MCU;

d: The connector is not properly installed, and the output cannot be output due to phase loss;

e: When all the above conditions are met, the output and driving circuits are faulty. When the motor is forcibly rotated by external force and there is obvious uneven resistance inside, it is mostly the MOS power tube that is damaged, but some of them are the front-stage driving transistors that are damaged.

2: The motor rotates, but not normally:

a: Whether the controller's 60-degree or 120-degree working mode selection corresponds to:

b: The motor relies on external force, and there is a loud and unstable sound when it rotates; the output is missing phase, check the connection line, and the components on the circuit board have leaking solder, cold soldering, short circuit, wrong soldering, etc.:

c: The Hall signal is incorrect. Some motors need to adjust the controller output line or Hall signal line;

d: The motor is not stable at low speed, which is mostly due to large differences in the parameters of the drive circuit components. Test the three-phase drive components for wrong welding and poor performance;

3: The motor is easy to stop and has poor load capacity:

a: Are the controller short-circuit comparison resistors R9 and R10 20K or 1.2K?

b: The capacity of capacitor C7 (1000Pf) and dead zone adjustment capacitor C24 (100PF) deviates too much;

c: The constantan wire is too long (*When the capacity of the controller capacitors C7 and C24 is incorrect, the working current will be abnormal, which is generally reflected in the fact that the working current is large and the constantan is adjusted too long);

d: Some components of the driving circuit are leaking electricity and have poor performance.

4: The current limiting resistor heats up and the static current is too large;

a: There is a short circuit in the detection circuit:

b: Check if there is any wrong soldering of components in the drive output;

c: Whether the connection in the plug-in corresponds.

5: It is easy to burn the MOS tube or the motor runs normally at a low speed. It is easy to burn the MOS tube when the handle rises quickly:

a: Is the HC27 circuit (U3) normal?

b. The voltage on pin 21 of the MCU is not at a logically high or low level, and its pull-up resistor is open or poorly soldered;

c: The MOS drive signal cannot follow the microcontroller output signal normally and presents a normal level, which is most likely to cause MOS damage.

6: After the turn signal is applied, the signal light goes out, but the motor does not rotate:

a: Is the motor output in good condition?

b: Motor Hall is not connected;

c: There are open circuits, cold solder joints, or leaking solder joints in the drive circuit.