Inverters are often used in life, especially in the car of the vehicular inverter application, here introduces the working principle of the inverter, the inverter is a voltage converter, what is the working principle of this electrical equipment, together to understand.
The inverter is a DC to AC transformer, and it is a voltage inverter process with the converter.
Function: inverter is the direct current energy (battery, storage battery) into alternating current (generally 220v 50HZ sine or square wave). Inverter is a device that converts direct current (DC) into alternating current (AC). It is composed of inverter bridge, control logic and filter circuit.
The converter converts the AC voltage of the power grid into stable 12V DC output, while the inverter converts the OUTPUT 12V DC voltage into high frequency AC. Both parts also use the widely used pulse width modulation (PWM) technology. The core part is a PWM integrated controller, the converter is UC3842, the inverter is TL5001 chip.
TL5001 has a working voltage range of 3.6 ~ 40V. It is equipped with an error amplifier, a regulator, oscillator, PWM generator with dead zone control, low voltage protection circuit and short circuit protection circuit.
Working Principle of Each Part
1. Input Interface
The input part has 3 signals, 12V DC input VIN, working enable voltage ENB and Panel current control signal DIM. VIN is provided by Adapter, ENB voltage is provided by MCU on the motherboard, and its value is 0 or 3V. When ENB=0, the inverter does not work, but when ENB=3V, the inverter is in normal working state. The DIM voltage is provided by the motherboard, and its variation range is between 0 and 5V. When the different DIM value is fed back to the feedback end of the PWM controller, the current provided by the inverter to the load will be different. The smaller the DIM value is, the larger the output current of the inverter will be.
2. Voltage Start Loop
ENB is high voltage, output high voltage to light the Panel backlight lamp tube.
3. PWM Controller
Internal reference voltage, error amplifier, oscillator and PWM, over voltage protection, under voltage protection, short circuit protection, output transistor.
4. DC Conversion
The voltage conversion circuit is composed of MOS switch tube and energy storage inductor. After the input pulse is amplified by the push-pull amplifier, the MOS tube is driven to switch, so that the DC voltage can charge and discharge the inductor, so that the other end of the inductor can get the AC voltage.
5. LC Oscillation and Output Loop
Ensure the 1600V voltage required for the lamp starting, and reduce the voltage to 800V after the lamp starting.
6. Output Voltage Feedback
When the load is working, feedback sampling voltage, play the role of stabilizing I inverter voltage output.