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4. High voltage transformer design guide for a central inverter
For new energy, the warranty is only applied to high-voltage transformers installed in accordance
with the guideline provided with the application note.
The photovoltaic inverter is classified into two types: transformer and non-transformer types.
Since a non-transformer type inverter has no transformer in the inside in contrast with transformer-type
inverter, a medium voltage (MV) transformer should be designed in accordance with the guideline when
it is connected to the external high-voltage transformer.
4.1 Technical properties
The MV transformer that is connected to the photovoltaic inverter without transformer shall comply with
the following technical specifications.
1. The transformer shall be suitable for the pulse width modulation (PWM) inverter. The transformer
shall be designed to prevent magnetic flux from saturating even if 1% of the direct current (DC) flows
in the low-voltage winding. The transformer shall be designed and tested in accordance with the ANSI
/ IEEE, NEMA, IEC and Department of Energy standards.
2. The transformer shall be designed considering voltage generated during the inverter's pulse operation.
The voltages can reach a magnitude of maximum ± 1400 V reference to the ground. The effective
value of voltage reference with regard to grounding is up to 700V.
