Overview

The inverter converts a 400V DC to an 8 level single-phase AC-signal.

It has a rated power of 3.33 kW and is a scaled down version targeting automotive drivetrains.

Inputs:

• DC-voltage for inverting
• Auxiliary power
• Optical signals to determine the switching state

Outputs:

• AC-voltage
• Measured voltage and current

Basic idea

Multi-level inverter provide many advantages such as low power components and higher output signal resolution.

However, this also comes at a drawback of complicated control and bulky DC-link capacitors which are needed to ensure that the output voltage levels stay balanced.

This project overcomes this issue by using magnetic fields to balance the voltage levels through a multi-active bridge. To ease the control and allow scaling up to many voltage levels, the multi-active bridge is using a specifically designed auxiliary power supply.

The inverter is an assembly consisting of three parts:

1. The auxiliary supply board
2. A multi-active bridge consisting of two mirrored boards, each of which has two transformer windings, one for the supply of the switches and one for power transfer
3. An inverter which has a simplified structure assuming that it always stays balanced. The structure is a special case of a P2 multilevel inverter omitting all redundant states

A special 3D-assembly is necessary to make the inverter operating.

This inverter with integrated balancer was part of my PhD.

A detailed description can be found in Chapter 6 here:

The other chapters give an overview over the system model, modulation, ...

https://discovery.ucl.ac.uk/id/eprint/10178459/

Please write me a PM if you are interested in the full BOM.