600W Sine Wave Inverter Construction in Detail – Including All PCB Materials(1)

600W Pure Sine Wave Inverter Construction in Detail

Dedicated to inverter beginners like myself

Since I shared the process of making a 1KW pure sine wave inverter, many friends have sent me messages, asking various questions. Many of them are beginners like me. In order to help everyone understand the inverter construction process more clearly and intuitively, I spent nearly a month creating this 600W pure sine wave inverter.

The inverter has the following features:

1.The SPWM driving core adopts a single-chip SPWM chip TDS2285, so the SPWM driving part is relatively simple compared to pure hardware. After completion, there are few things to debug, making it relatively easy to succeed.

2.All PCBs are single-sided, making it convenient for everyone to make. Because many enthusiasts make their own single-sided PCBs, some use photosensitive methods, some use heat transfer methods, etc., so you don’t have to bother with PCB manufacturers; you can make them at home. Of course, the main purpose is to save money. Nowadays, PCB manufacturers are too advanced, and I can’t afford them a bit (I only go to PCB manufacturers as a last resort).

3.All components and materials for this machine can be purchased on Taobao. With online shopping, it’s really convenient. The delivery comes to your doorstep, and you can get whatever you need. If the PCB is not wrong, if there are no issues with the components, and if you have a certain foundation in inverters, I guarantee you will succeed in making it. Of course, there are many things inside that you have to do yourself, and you can enjoy the pleasure of doing it yourself.

4.The power is only 600W. Generally speaking, a smaller power makes it easier to succeed. It can be used for experiments and has some practicality.

Below are photos of the prototype and its working waveform :

Ⅰ. Circuit Principles

The inverter is divided into four major parts. Each part has its own PCB board, namely the Power Mainboard, SPWM Drive Board, DC-DC Drive Board, and Protection Board.

1.Power Mainboard

The Power Mainboard consists of two major sections: DC-DC push-pull boost and H-bridge inverter.

The BT voltage of this machine is 12V. At full power, the working current of the front stage can reach over 55A. The DC-DC boost section uses a pair of 190N08, a type of MOSFET with a 247 package. With proper heat dissipation, a single pair can output 600W. Alternatively, the DC-DC boost section can also use IRFP2907Z. Compared to 190N08, it has similar output capacity and a comparable price.

The main transformer uses an EE55 core. In fact, for a 600W inverter, an EE42 core would be sufficient. I chose EE55 for convenience in winding, and also because I had EE55 cores available.

Further details on the winding of the main transformer will be explained below.

The power supply for the front-stage push-pull section adopts a symmetrical balanced approach. This has two advantages: first, it ensures the symmetry of the working states of the two power transistors under high current, preventing unilateral heating phenomena; second, it reduces the current density on the back side of the PCB solder layer. Of course, it also significantly reduces interference caused by current imbalance.

For the high-voltage rectification, fast-recovery diodes RHRP8120 in TO220 packaging are used. These diodes are reliable, and I obtained them secondhand for only 1 RMB each.

I use a 470uF/450V high-voltage filtering capacitor. In my opinion, using a larger-capacity capacitor is better when possible, as it has benefits for improving the load characteristics of the high-voltage section and reducing interference.

The H-bridge section uses 4 IRFP460 transistors with a voltage tolerance of 500V and a maximum current of 20A. Similar transistors with comparable performance can also be used as replacements. Using transistors with low internal resistance can improve the overall inverter efficiency. The circuit for the H-bridge section follows a conventional design.

The following are the schematic diagram and PCB screenshot of the power mainboard.

2.SPWM Drive Board

Similar to my 1KW machine, the core of the SPWM section utilizes Zhang Gong’s TDS2285 microcontroller chip.

U3 and U4 form the timing and dead-time circuit. The final stage output uses 4 250 optocouplers. The two upper transistors of the H-bridge are powered in a bootstrap fashion, aiming to simplify the circuit and eliminate the need for an isolated power supply. As the BT voltage varies between 10-15V, the totem-pole output stage working voltage of the 250 optocouplers must be between 12V-15V, not lower than 12V, to reliably drive the H-bridge. Therefore, an MC34063 (U9) is used here to boost the BT voltage to 15V (this boost circuit is provided by Zhong Gong), and experimentation has shown that this approach is very effective.

The entire SPWM Drive Board is connected to the Power Board through J1 and J2 interfaces. The pin descriptions for each interface are as follows:

J2: 2P-4P; 7P-9P; 13P-15P; 18P-20P are the drive pins for the four power transistors of the H-bridge.

23P-24P are the input terminals for the sampled AC voltage stabilization.

J1: 1P connects to the protection signal output of 2285 to the 10th pin of the preceding 3525. Once the protection circuit is triggered, the 12th pin of 2285 outputs a high level, closing the output of the preceding stage through this interface.

6P-7P-8P are ground (GND).

9P connects to the output of the protection circuit, used to disable the SPWM output of the subsequent stage.

10P-11P connect to the BT power supply.

Below are the schematic and PCB screenshots for the SPWM Drive Board:

3.DC-DC Drive Board

For the DC-DC boost drive board, I employed a very common circuit. PWM output is achieved using an SG3525 chip, and the subsequent stage uses two sets of totem pole outputs. Through experimentation, if I use a pair of 190N08, the totem pole section can be omitted, and direct drive with SG3525 is sufficient. Since this DC-DC drive board shares a common interface with my 1000W machine, it has dual outputs, but only one set is utilized in this machine. There are two small toggle switches on the board: S1 and S2. S1 is the power-on switch, and S2 is the power-off switch, allowing control over the start and stop of the inverter.

This drive board is connected to the power board through J3 and J4 interfaces, where the 1st pin of J3 serves as the input for voltage limiting feedback.

Below are the schematic and PCB screenshots for the DC-DC boost drive board:

4.Protection Board

This time, I didn’t create a protection board. Firstly, because the inverter can operate without it, and secondly, I’ve been quite busy recently, so I didn’t make a protection board. Another reason is that the power mainboard I published this time has been modified, and the interfaces on the protection board have been altered. The prototype I used has an unmodified PCB, so even if I made a protection board, it wouldn’t fit. I do hope that if someone uses my PCB documents to manufacture samples at a factory, they won’t forget to make an extra set for me. If they send it to me, I can then design a protection board based on the new power mainboard.

Below is the circuit diagram for the protection section, which is derived from the protection circuit used in Zhong Gong’s 3000W inverter.

Below is the full PROTEL99 packet for the 600W inverter.