# 3 phase low voltage signal generator

I want to create my own 3 phase signal. However, instead of it peaking at 230V AC it must peak at 5V AC.

This generator will be used to feed a secondary unit that uses this signal to perform its own set of operations. This secondary unit is off the shelf so I cannot give much info on this.

I hook-up a scope on the three input pins of the secondary device and found out that it is been feed by a 3 phase 5V peak AC signal. One pin for each of the phases. I want to know feed in my own 3 phase 5V phase signal to trick the system.

How do I go about making a 5V peak 3 phase signal? Either through a micro or analogue components.

• Why not use three transformers from regular 3 phase? Commented Mar 22, 2022 at 15:02
• @Andyaka 3 phase will not be present at all. Basically what I want to do is take use a digital signal or constant voltage to generate a 3 phase 5V AC signal Commented Mar 22, 2022 at 16:36
• @JoeyB Why not use three DACs? Commented Mar 29, 2022 at 21:37
• @VoltageSpike I am trying to use a I2C 4 channel DAC. If I2C is to slow, then I will get a SPI DAC. Commented Mar 30, 2022 at 6:58

The obvious approach with a micro or FPGA is to have a one quadrant lookup table and 3 DACs.

You can set up a periodic interrupt or use double buffer DMA to calculate and send the data to the DACs.

You may need some level shifting and gain adjustment to get your required output level. Maybe a bit of filtering depending on your requirements.

TBD: How many bits you need, (related) how fast to update the DACs, accuracy of clock, voltage, zero balance.

• what is a double buffer DMA? Commented Mar 22, 2022 at 20:04
• DMA = Direct Memory Access, a hardware feature built into many micros. Double buffering alternates between two buffers, one is being filled while the other is used. Commented Mar 22, 2022 at 20:06
• First thing is to evaluate whether you can get the data to the DAC fast enough through the I2C interface. Commented Mar 23, 2022 at 18:58
• Determine how fast you need to update the DAC to get the required quality of sine waves. Then see if you can use I2C high speed mode with ESP32 or you have to use 400kHz or 100kHz. This is basic design work you need to do. Commented Mar 23, 2022 at 19:11
• Yes, that’s the first step. Also see my brief list of TBD. Commented Mar 23, 2022 at 20:01