Automotive LC-4 DC Brushless Motor Controller Debugging and Fault Diagnosis Guide

If the actual speed is lower than the expected value, increase the speed gain clockwise; Conversely, decrease.

5.3 Current Limit Set Point

Set the maximum allowable motor current (usually 50-150% of the controller's rated current).

Attention: The rated current of the motor should not be exceeded, otherwise the motor may overheat. If a larger starting torque is required, it can be temporarily increased, but the temperature rise needs to be monitored.

5.4 Closed Loop Speed Control Gain

This adjustment affects the response speed and stability of the speed loop.

Low gain: slow response, insufficient compensation for load changes, and large speed drop.

Excessive gain: System oscillation, unstable speed, and even whistling sound.

Debugging method:

Gradually increase the gain from small to large until the motor can quickly recover speed without overshoot oscillation during loading. If oscillation occurs, reduce the gain or increase the soft start time.

5.5 Velocity Set Point 1/2

These two potentiometers respectively set two internal speed values (percentage of maximum speed). Switch through external digital input 'Dual Speed Select'.

Application scenarios: For example, high-speed conveying and low-speed positioning of conveyor belts, or dual speed mixing of mixers.

Common troubleshooting table

Possible causes and solutions for the fault phenomenon

After power on, the POWER LED does not light up, there is no AC input, the fuse is blown, and the internal power supply is damaged. Check the AC input voltage (115V); Visually inspect the fuse; If the fuse is intact but still does not light up, repair it

The motor does not rotate, and the RUN LED is off without giving a START signal; ENABLE not connected; Short circuit the START/STOP terminal to+5V when the speed command is 0; check the speed command voltage (>0V); Confirm the status of the ENABLE terminal

The motor does not rotate, the FAULT LED is constantly on. Over temperature, over/under voltage, and locked rotor protection are triggered to check the heat dissipation conditions, whether the input voltage is stable, and whether the motor is mechanically stuck

The motor can rotate but the speed is unstable and the speed gain is inappropriate; Speed feedback interference; Adjust the speed closed-loop gain again due to excessive load fluctuations; Check the wiring and shielding of the speed generator; Increase the current limit amplitude

Immediately triggering current limiting (yellow light on) during startup, the soft start time is too short; Large load inertia; If the current limit is set too low, increase the soft start time; Appropriately increase the current limit setting point; Check mechanical resistance

The motor can only rotate in one direction. The FORWARD/REVERSE signal is not wired or has a logic error; Incorrect configuration of commutation coding measurement direction input terminal voltage; Check if the commutation coding switch matches the motor Hall sequence

Check the fan or heat dissipation for overheating protection during operation or intermittent shutdown; Reduce load or improve heat dissipation capacity; Clean the ventilation holes of the controller

The problem of high noise during motor operation and PWM frequency setting (adjustable for some models) or motor bearing issues. Try changing the PWM frequency (if any); Check the mechanical part of the motor

Dynamic braking is ineffective. The braking signal is not connected or the level is incorrect; If the brake transistor is damaged, connect the Dynamic BRAKE terminal to+24V (or+5V) to test the braking effect; If ineffective, maintenance is required

Key points for on-site installation and wiring

7.1 Power Wiring

Connect the L (live wire) and N (neutral wire) directly to the 115V AC terminal.

Ensure that the ground wire (PE) is reliably connected to the chassis grounding bolt.

Fuse specification: Select according to the rated current of the controller (usually 2-5A, slow melting type).

7.2 Motor wiring

LC-4 is suitable for three-phase DC brushless motors (usually equipped with Hall sensors). Wiring includes:

Motor phase lines: U, V, W (pay attention to phase sequence, incorrect phase sequence can cause the motor to not rotate or shake)

Hall sensor signals: H1, H2, H3,+5V, GND. The Hall signal must match the logic of the controller (adjustable through commutation coding selection switch)

7.3 Control signal wiring

Use shielded cables, with the shielding layer grounded at one end (controller end).

The simulated speed command line should be routed separately from the power line to avoid interference.

For long distances (>10m), it is recommended to use a 4-20mA current signal instead of a voltage signal.

7.4 Heat dissipation requirements

The controller should be installed vertically on the metal panel to utilize heat conduction.

Leave at least 50mm of ventilation space around.

If installed in a closed cabinet, a cabinet fan or heat exchanger needs to be configured.

Maintenance and spare parts recommendations

8.1 Regular inspection items (every 6 months)

Clean the dust on the heat sink and fan (if any).

Check all wiring terminals for looseness (vibration may cause poor contact).