The operation of an inverter can be broken down into the following steps:
An oscillating circuit converts direct current (DC) into alternating current (AC).
The coil boosts the voltage, converting irregular alternating current into square wave alternating current.
Rectification transforms alternating current from a square wave into a sinusoidal alternating current.
The core component of an inverter is PWM (Pulse Width Modulation), which generates a stable AC voltage by controlling the on and off times of semiconductor switching devices. There are many types of inverters, including half-bridge, full-bridge, and three-phase bridge inverters. Their main structure is based on a half-bridge or full-bridge configuration using switching transistors (such as MOSFETs, IGBTs, and thyristors). 56
In addition, the inverter also has protection functions such as overvoltage protection, undervoltage protection, and short circuit protection to ensure the stable operation of the system.
Inverter working principle
Input interface section:
The input section has three signals: a 12V DC input VIN, an enable voltage ENB, and a panel current control signal DIM. VIN is provided by the adapter, and the ENB voltage is provided by the MCU on the motherboard. Its value is either 0 or 3V. When ENB=0, the inverter does not work, and when ENB=3V, the inverter is in normal working condition. The DIM voltage is provided by the motherboard, and its range is between 0 and 5V. Different DIM values are fed back to the PWM controller feedback terminal, and the current supplied by the inverter to the load will also be different. The smaller the DIM value, the larger the current output by the inverter.
Voltage start-up circuit:
When ENB is high, it outputs high voltage to light up the panel's backlight tubes.
PWM controller:
It consists of the following functions: internal reference voltage, error amplifier, oscillator and PWM, overvoltage protection, undervoltage protection, short circuit protection, and output transistor.
DC-DC conversion:
The voltage conversion circuit consists of a MOS switch and an energy storage inductor. The input pulse is amplified by a push-pull amplifier and drives the MOS switch to perform a switching action, so that the DC voltage charges and discharges the inductor, and the other end of the inductor can obtain the AC voltage.
LC oscillation and output circuit:
Ensure the lamp is powered by 1600V and then reduce the voltage to 800V after it starts.
Output voltage feedback:
When the load is working, the feedback sampling voltage plays a role in stabilizing the Inventor voltage output.
You can actually imagine it. Which electronic components need positive and negative terminals? Resistors and inductors generally don't. Diodes usually fail because they're broken down; as long as the voltage is normal, they're generally fine. Transistors won't conduct. Zener diodes will be damaged if the polarity is reversed, but some circuits have protection mechanisms that use the diode's unidirectional conduction. Then there are capacitors. Electrolytic capacitors have positive and negative terminals; if the polarity is severely reversed, their casing can burst.
Key components include diodes, switching transistors, an oscillator transformer, a sampling transistor, a pulse-width modulation (PWM) transistor, and the principles of the oscillation circuit, including resistors, capacitors, and other parametric switching circuits.
The selection of the main power components of an inverter is crucial. Currently, commonly used power components include Darlington power transistors (BJTs), power MOSFETs, insulated gate transistors (IGBTs), and turn-off thyristors (GTOs). MOSFETs are more commonly used in small-capacity, low-voltage systems because they have lower on-state voltage drop and higher switching frequency. IGBT modules are generally used in high-voltage, high-capacity systems because the on-state resistance of MOSFETs increases with voltage. IGBTs have a significant advantage in medium-capacity systems. In ultra-large capacity (above 100KVA) systems, GTOs are generally used as power components.
Major components include: MOSFETs or IGBTs, transformers, capacitors, diodes, comparators, and main control circuits such as the 3525. The system also includes AC/DC/AC inverters, rectifiers, and filters.
Power and accuracy are related to the complexity of the circuit.
IGBTs (Insulated Gate Bipolar Transistors), as a new type of power semiconductor field-controlled self-turn-off device, combine the high-speed performance of power MOSFETs with the low resistance of bipolar devices. They feature high input impedance, low power consumption under voltage control, simple control circuitry, high voltage resistance, and high current handling capacity, making them widely used in various power conversion applications. Meanwhile, major semiconductor manufacturers are continuously developing IGBT technologies with high voltage resistance, high current capacity, high speed, low saturation voltage drop, high reliability, and low cost, primarily using sub-1µm fabrication processes, and have made some new progress in research and development.
1. Working principle of fully controlled inverter
This is a commonly used single-phase output full-bridge inverter main circuit, with IGBT transistors Q11, Q12, Q13, and Q14 used for AC components. The conduction or cutoff of the IGBT transistors is controlled by PWM pulse width modulation.
When the inverter circuit is connected to a DC power supply, Q11 and Q14 are turned on first, while Q1 and Q13 are turned off. Current flows from the positive terminal of the DC power supply, through Q11, the inductor (or L), the primary coil of the transformer (Figure 1-2), and back to the negative terminal of the power supply via Q14. When Q11 and Q14 are turned off, Q12 and Q13 are turned on, and current flows from the positive terminal of the power supply through Q13, the primary coil of the transformer (Figure 2-1), and the inductor (Q12) back to the negative terminal. At this time, an alternating positive and negative square wave is formed on the primary coil of the transformer. Using high-frequency PWM control, the two pairs of IGBTs alternately generate an AC voltage on the transformer. Due to the effect of the LC AC filter, a sinusoidal AC voltage is generated at the output terminal.
When Q11 and Q14 are turned off, in order to release the stored energy, diodes D11 and D12 are connected in parallel at the IGBT so that the energy returns to the DC power supply.
2. Working principle of semi-controlled inverter
Semi-controlled inverters use thyristor elements. Th1 and Th2 are thyristors that operate alternately. If Th1 is triggered first, current flows through the transformer and onto Th1. Simultaneously, due to the transformer's induction, the commutation capacitor C is charged to twice the power supply voltage. Then, if Th2 is triggered, because its anode is reverse-biased, Th1 is cut off and returns to the blocking state. In this way, Th1 and Th2 commutate, and then capacitor C is charged in the opposite polarity. This alternating triggering of the thyristors causes current to flow alternately to the primary winding of the transformer, where alternating current is obtained at the secondary winding.
In the circuit, the inductor L limits the discharge current of the commutation capacitor C, prolonging the discharge time and ensuring that the circuit turn-off time is greater than the thyristor turn-off time, without requiring a large capacitor. D1 and D2 are two feedback diodes that release the energy in the inductor L and send the remaining commutation energy back to the power supply, completing the energy feedback function.
The working principle of an inverter is as follows:
1. An inverter is a DC-AC transformer. In fact, like a converter, it is a voltage inversion process. A converter transforms the AC voltage from the power grid into a regulated 12V DC voltage, while an inverter transforms the 12V DC voltage from the adapter into high-frequency AC voltage. Both use the more common PWM technology.
2. An inverter is a conversion device that converts direct current (DC) energy (from batteries or storage devices) into constant voltage or frequency-modulated alternating current (AC) voltage. The system includes an inverter bridge, control logic, filters, etc.
3. The core components are PWM, UC3842 is the adapter, and TL5001 is the TL5001. The TL5001 has an operating voltage of 3.6~40V and internally includes an error amplifier, regulator, oscillator, dead-time PWM generator, low-voltage protection circuit, and short-circuit protection circuit.
In short, an inverter is a device that converts low-voltage (12V, 24V, 48V) AC power into 220V AC power. Since 220V AC power is generally rectified into DC power, while an inverter does the opposite, it is named as such. We live in a mobile age, with mobile phones used in offices, for communication, and for leisure and entertainment. During these activities, we need both high-voltage DC power from batteries or rechargeable batteries and 220V AC power, making it indispensable in daily life.
Structure of a solar photovoltaic water pump system (photovoltaic water lifting system)
The solar photovoltaic water pump system (photovoltaic water lifting system) mainly consists of three parts: solar panels, solar photovoltaic water pump inverter, and water pump.
Solar panels: solar energy collection and photoelectric conversion devices
Solar photovoltaic water pump inverter/controller: Converts electricity generated by solar panels to drive the water pump; controls and adjusts the water pump system to maximize power.
Water pump: for transporting liquids
Other components:
Installation components: Placing and securing solar panels
Combiner box: Integrates solar panel input and protects the components.
Outdoor mounting box: IP54 rating, convenient for outdoor installation.
Working principle of solar photovoltaic water pump system
Solar panels absorb solar radiation and convert it into electrical energy; the solar photovoltaic water pump inverter adjusts its output power in real time according to changes in solar irradiance and drives the water pump to work.
Advantages of solar photovoltaic water pump systems
Fully automatic operation, no manual supervision required.
It is compatible with a wide range of water pump types, such as three-phase, single-phase, and DC water pumps.
Wide input voltage range, compatible with various photovoltaic modules
Modular design for easy maintenance
Using imported components, safe and reliable.
With a hybrid input of solar and mains power, it can operate around the clock.
Wireless remote control
Personalized solutions
Application Cases of Solar Photovoltaic Water Pump Systems
*Irrigation of orchards, gardens, and greenhouses in remote areas
*Water supply for suburban parks and farms
Aeration equipment for fish ponds and other aquaculture farms
*Swimming pool water circulation system
Livestock drinking water system
