Im currently working in an office environment developing a system to communicate over rs485 Modbus with an 3 phase EV charger. Due to the location it is not possible to get three phase power. However I won't be charging cars and will be using a tester(mostly to simulate car type, charge times etc) is it possible/save to hook up an 1-3 phase 1.5kW frequency regular to do this kind of testing?

Thanks in advanced

  • \$\begingroup\$ Probably not (due to sine quality). Test at location a few times, simulate the other communications. But this is more of a usage question, not design.... \$\endgroup\$
    – Jeroen3
    Sep 3, 2020 at 9:50
  • \$\begingroup\$ I just searched at a known seller of lab equipment. A 1,5kW AC source suited to replace a real grid is about 10.000 $/€. Think about emulating the 3 phase EV charger's communication. Thats cheeper and less risky \$\endgroup\$
    – schnedan
    Sep 9, 2020 at 9:30

1 Answer 1


It might be possible with a single phase using a transformer.

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Figure 1. A VFD outline schematic. (Image source: EE.SE unattributed.)

The charger probably has an input stage similar to the variable frequency drive above. A three-phase bridge rectifier charges up the DC-link capacitor to √2 times the peak mains voltage. In Europe this would be a 400 V supply so about 560 V. Since you're not charging you might be able to run it from one 400 V supply generated by a 230 to 400 V step up transformer and connected to two of the input terminals.

I suspect that this will generate some internal "lost phase" errors which may make the exercise unusable but it might work and give you a useful error message to help debug your system.

Either way the manufacturer would be the right people to ask. A "frequency regular" will may not give out a sine wave and may have difficulty with the capacitive load.


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