Modern testing of traction inverters is typically carried out using advanced inverter test systems, which include motor emulation among other components. Despite the high technical standard of these systems, gaps remain in the test coverage – particularly regarding the realistic representation of the HV-DC network of electric vehicles. This work begins by systematically identifying this lack of test coverage and a representative HV-DC network will be shown.

To address the identified shortcomings, a concept for DC network emulation is introduced, enabling inverter testing in a vehicle-like environment. This emulation allows for a detailed assessment of inverter behavior under dynamic load conditions and under the influence of a voltage ripple, as encountered in real-world vehicle operations. Additionally, the impact of ripples generated by the inverter on other components within the HV network can be investigated.

The implementation combines motor emulation with full onboard network emulation, as shown in Attachment 1. The DC terminal voltage of the inverter is determined via real-time simulation and precisely regulated by power electronics, taking into account all ripple and harmonics. Both calculated and measured signals from the motor emulation are incorporated into the process. A subsequent analysis highlights the key advantages of this approach.

Simulations and measurements conducted on the AVL inverter test system demonstrate that DC onboard network emulation enables profound insights into the operational behavior and robustness of traction inverters. Selected results are presented, showing that the proposed method makes a valuable contribution to the advancement of testing procedures for electric drive systems. An example of the voltage ripple at the DC terminals of a 2-level traction inverter is given in Attachment 2.
The interaction of all components within the high-voltage (HV) network can, according to the current state of the art, only be fully tested at the vehicle level. To enable early-stage testing of the individual component „traction inverter“ in a vehicle-like environment, a DC network emulation approach can be applied. This method allows the inverter to be integrated into a simulated vehicle context, enabling analysis of its behavior under typical onboard network conditions.

By emulating additional HV components such as motors, DC/DC converters, onboard chargers, and multiple inverters, testing can be conducted much earlier in the development process. This enables flexible evaluation of various vehicle architectures and onboard topologies without the need for physical prototypes.

The proposed approach contributes to significantly reducing the overall development time of the electric powertrain while increasing test coverage. Potential weaknesses can be identified at an early stage, and system integration can be carried out more efficiently.