electric forklift schematic

Power Supply Circuit

Battery: Serves as the power source for the electric forklift, with common voltages such as 36V and 48V, supplying electrical energy to the entire electrical system.
Voltage Stabilization Circuit: Typically composed of voltage stabilization chips (e.g., TL431) and other components. It converts the battery voltage into a stable 12V voltage to power components like the control circuit and sensors, ensuring these components operate under a stable voltage.

Controller: With a microcontroller or a dedicated motor control chip as its core, it receives signals from the operating handle, pedals, etc., and controls the motor operation according to the operator’s instructions.
Driver Chip or Power Tube: Devices such as MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or IGBT (Insulated Gate Bipolar Transistor). They amplify the weak electrical signals output by the controller into strong electrical signals capable of driving the motor, thereby controlling the motor’s speed and direction.

Speed Control Handle or Pedal: The operator adjusts the signal input to the controller by operating the speed control handle or pedal, thereby controlling the forklift’s speed.
PWM (Pulse Width Modulation) Circuit: With the TL494 pulse width modulator as its core, it controls the average voltage of the motor by changing the duty cycle of the output pulses, further achieving precise control of the motor speed. The larger the pulse duty cycle, the higher the motor speed.

Direction Switch: Usually a 2-position or 3-position switch, used to ｓｅｌｅｃｔ the forklift’s forward, reverse, or stop state. When the direction switch is toggled, the controller changes the direction of the current in the motor drive circuit, thereby realizing the forward and reverse rotation of the motor and controlling the forklift’s travel direction.

Brake Pedal: When the operator depresses the brake pedal, the brake switch closes and sends a braking signal to the controller.
Brake Resistor or Brake Unit: In some electric forklifts, during braking, the regenerative electric energy generated by the motor is consumed through the brake resistor (converting electrical energy into heat for dissipation) to achieve rapid braking; alternatively, the regenerative electric energy is fed back to the power supply through the brake unit.

Battery Level Display Circuit: Uses chips such as LM339. It detects and compares the battery voltage through a comparator, and controls the on/off state of the LED lights according to different voltage ranges to intuitively display the battery’s charge status.
Over-Discharge Protection Circuit: When the battery voltage drops below the set lower limit (e.g., 31.5V), the output pin of chips like LM324 outputs a low-level signal, turning on the triode and forcing the internal pulse-width modulation output tube of TL494 to cut off. This stops the motor operation and prevents damage to the battery due to over-discharge.
Over-Current Protection Circuit: A sampling resistor is connected in series in the motor circuit. When the motor current exceeds the set value, the voltage ｄｒｏｐ across the sampling resistor exceeds the threshold, and the internal operational amplifier of TL494 outputs a high-level signal to stop the motor operation, protecting the motor and circuit components from damage caused by over-current.

Temperature Sensor: Used to detect the temperature of components such as the motor and controller. When the temperature is too high, it promptly sends a signal to the controller, which then takes measures such as reducing speed or stopping operation to prevent component damage due to overheating.
Pressure Sensor: Installed in the hydraulic system, it detects the pressure of the hydraulic oil to ensure the normal operation of the hydraulic system. At the same time, it can also provide a basis for the forklift’s load control.