User Guide

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2021-01-29

System and functional description

User guide for REF-22K-GPD-INV-EASY3B

A reference design for a general purpose drive

In order to simplify the supply scheme for the multiple external user interfaces, the SELV board is supplied via a

safety-isolated, low-voltage power supply. The connection to the high voltage logic board (UART, direct

connection lines) is therefore established via digital isolator devices featuring reinforced isolation capability.

2.2.2

Isolation coordination

The inverter design provides three major main voltage domains:

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A mains-connected domain

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A low-voltage domain with functional isolation

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A safety-isolation domain

In Figure 11 you will find a drawing of the basic isolation coordination scheme.

Figure 11

Basic isolation coordination scheme, the low- voltage interface board is referenced to PE

and the high- voltage logic board is referenced to DC-

All power components (EMI filter, rectifier, IGBT inverter, brake switch) are directly connected to the mains

supply domain. The main controller is based on a functional isolated scheme, which is connected to the DC-

potential of the power domain. Thanks to this isolation scheme, all interfaces between the power domain and

the main control domain only provide functional isolation. This applies in particular for the gate drivers, their

power supply, the output current sensors and the voltage measurement circuits. All user interface connections

are implemented on a safety-insulated domain. In order to establish a communication link between the safety-

isolation domain and the functional isolation domain, a digital interface using a safety isolated data coupler is