This time it is a single-phase sine wave off-grid control board, followed by a single-phase sine wave off-grid control board, then a three-phase sine wave off-grid control board, and finally a three-phase sine wave off-grid control board. We hope that everyone will support it. All solutions use PIC microcontrollers.

Let me talk about my purpose in making a grid-connected inverter. I want to achieve the function of "feedback electronic load". Because aging inverters or aging switching power supplies, everyone uses resistors as loads and wastes power. I think to collect this electrical energy and feed it to the input end of our power supply equipment in the form of an inverter grid connection. This forms a cyclic aging product. Theoretically, full-power aging products do not consume electricity. Actually, the loss of machinery and equipment needs to be supplemented, so the feedback electronic load can collect 90% of the electrical energy. This is my goal, and we also need your strong support! If you want to make a grid-connected inverter, you must do a good off-grid inverter. Not much to say, first look at the schematic diagram of the single-phase off-grid sine wave control board.

Step 1: The Schematic Diagram of the Single-phase Off-grid Sine Wave Control Board.

This control board is specifically designed to drive high-power IGBTs. It has a negative voltage shutdown function and is the best choice for IGBTs. The left is the H-bridge drive power supply, the upper middle is the core of the microcontroller, the lower middle is the H-bridge inductive output current comparator, which controls the output power, and the right is the high-speed IGBT drive optocoupler, which specifically drives the IGBT and provides negative voltage shutdown Features. Everyone knows that FETs can be turned off and turned off at zero volts, and IGBTs are not the same. A negative voltage is required to reliably turn off.

Step 2: Back-end Circuit of the Inverter

Next, draw the PCB. I believe that everyone is familiar with the sine wave off-grid. I do n’t explain too much. I will give you a detailed explanation on the grid connection. I also use this chip PIC16F716 to grid Sine wave control board

Step 3: PCB Design

Step 4: PCB Prototype and Assembly

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Step 5: Test Steps

First, 14 pins and 15 pins input 24V DC power. Test 6 and 8 pins of each optocoupler with a voltage of 24V. Then input 5V at 16 pins, and oscilloscope test 5 and 8 pins. 10 feet and 12 feet, the output is 16KHz complementary SPWM wave, you're done!

Besides, why should I write a carrier frequency of 16KHz, because the carrier frequency of 16KHz can adapt to the common high-power IGBT of the module type, only the module IGBT can make a high-power sine wave inverter. I want to use this solution when I have time. Make a 20KW single-phase sine wave inverter.

This test was successful, the output frequency is accurate, the output voltage stability is very good, and the load and no-load output voltage remain unchanged.

This sample software voltage stabilization mode adopts the structure of peak voltage stabilization, voltage instantaneous value feedback and effective value feedback, and double closed-loop control mode. The outer loop voltage rms feedback makes the system as steady as possible without any static output. The inner loop uses instantaneous feedback to ensure the system obtains excellent dynamic performance. Both perform their duties and work together.