I have a doubt regarding calculation of 3-phase power in EV charging. On the last page of the pdf in the link given below, the power calculation is done as 3 x 230V x 16A = 22kW.


However, I don't understand why is it not √3 x 230V x 16A or 400V x 16A instead. Can somebody explain the calculations with the reason for the same?

  • \$\begingroup\$ Have you read the Wikipedia page on 3-phase power: en.wikipedia.org/wiki/Three-phase_electric_power ? Note how there are the Y-configuration and the Delta configuration. The calculation would be valid for the Y-configuration as phase to neutral is 230 V. \$\endgroup\$ – Bimpelrekkie Jun 20 '18 at 6:41
  • \$\begingroup\$ Yes, I do know about three phase power. Something made me confused for a while and I managed to make a fool of myself by asking this rather stupid question. Btw, can you please tell about what type of (3-phase) rectifier is used in EVs? 6-pulse or a 12-pulse? \$\endgroup\$ – Pikachu Jun 20 '18 at 6:50
  • \$\begingroup\$ I expect the rectifier not to be in the vehicle itself but in the charging console. I could be wrong though. For a Y-configuration I would expect a 6-pulse rectifier, again I could be wrong. What is used isn't always like if this - then that as it can depend on circumstances and design choices. Understanding the why behind those choices is much more interesting and useful than just learning what is used when. \$\endgroup\$ – Bimpelrekkie Jun 20 '18 at 6:56
  • \$\begingroup\$ @Bimpelrekkie Well, the rectifier sits inside the car for AC charging (also called onboard charger). For DC fast charging, the rectification is done by the charger (at charging station) as the onboard charger's power electronics are not meant to deal with high power. While DC charging, the DC current is bypassed (I don't know how this actually works) directly to the battery. \$\endgroup\$ – Pikachu Jun 20 '18 at 7:01
  • \$\begingroup\$ You mentioned that for a Y-configuration, you expected a 6-pulse configuration. Why is it so? Am I missing something basic here or is it out of experience? \$\endgroup\$ – Pikachu Jun 20 '18 at 7:03

The phase to phase voltage is 400V, which gives 230V phase to neutral voltage. \$\dfrac{400}{\sqrt3} = 230\$.

So the formula is \$\dfrac{400}{\sqrt3}\cdot 3\cdot16 = \dfrac{\sqrt3}{\sqrt3\sqrt3}400 \cdot3\cdot16 =400 \sqrt3\cdot16\$. Or \$230 \cdot3\cdot16\$

  • \$\begingroup\$ Oh Yes! I don't know why I felt confused at seeing something very obvious. Thanks for the clarification though! \$\endgroup\$ – Pikachu Jun 20 '18 at 6:45
  • \$\begingroup\$ Btw, can you please tell about what type of (3-phase) rectifier is used in EVs? 6-pulse or a 12-pulse? \$\endgroup\$ – Pikachu Jun 20 '18 at 6:47
  • \$\begingroup\$ @PMD It doesn't matter what's behind, since you are measuring the three phase input. \$\endgroup\$ – Marko Buršič Jun 20 '18 at 6:50
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    \$\begingroup\$ @PMD You would need a transformer set for 12 pulse rectifier, which is heavy and big. There are other methods, like PFC corrector: LC with IGBT/MOSFET combined with EMI filter. \$\endgroup\$ – Marko Buršič Jun 20 '18 at 8:13
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    \$\begingroup\$ @PMD You can assume six-pulse but with PFC. \$\endgroup\$ – winny Jun 20 '18 at 8:19

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