The bidirectional onboard charger (BOBC) sits at the heart of an electric vehicle's (EV) energy architecture. BOBCs not only charge the EV battery, but also enable a bidirectional flow of energy between the battery and the utility grid or other connected loads. Through power conversion modes like Vehicle-to-Grid (V2G) and Vehicle-to-Load (V2L), an EV gains dual value as both a means of transportation and a mobile energy storage system. In particular, V2L technology makes it possible to power household appliances, tools, or outdoor equipment directly from the vehicle, greatly expanding its range of everyday use cases. When combined with renewable energy systems, V2L substantially improves energy flexibility and serves as a key enabler for the low-carbon transition.

During V2L development and validation, engineers often rely on load testing with a wide variety of real appliances to simulate different usage scenarios. This type of testing faces significant hurdles. First, real loads vary widely by type, specification, and region and are difficult to standardize, resulting in smaller test volumes and less generalizable results. Second, different loads have distinct power profiles and startup characteristics, making it hard to assemble a complete and representative set of test conditions. Third, the physical testing process involves a high degree of randomness, making repeatability difficult to achieve. As a result, V2L testing may become costly in terms of time, space, and budget, with test scopes remaining difficult to narrow down and efficiency gains hard to realize.

To address these V2L testing challenges, Chroma offers an efficient and comprehensive solution based on the optional AC load capability of the Chroma 61815 Regenerative Grid Simulator (3U/15kVA, high power density). Two key technologies enable realistic, repeatable load simulation: User-Defined Waveforms (UDW) and advanced programming via List Mode.

User-Defined Waveform

The UDW feature allows users to reproduce actual load current behavior with high fidelity. Engineers can capture the current waveform of real loads like household appliances through an oscilloscope, or create custom waveforms in Excel. Using Chroma’s dedicated SoftPanel software, the waveform is stored as a single-cycle profile and then imported into the Chroma 61815 to replicate the defined load current. This solves standardization and repeatability issues in V2L testing. With the ability to build up to 200 UDW load profiles, users no longer need large quantities of physical appliances, reducing setup effort and space requirements while streamlining the overall test workflow.

▲Simulating actual load current waveforms using UDW

List Mode Advanced Programming

List Mode enables users to build a continuous load program by configuring up to 100 load sequences. Each sequence can be configured independently, including the waveform shape, so complex current profiles can be assembled into a coherent test routine. For example, to reproduce continuous and irregular waveforms like appliance inrush current, users can edit multiple sequences in List Mode, with each sequence using UDW to capture an actual waveform. This makes it possible to faithfully replicate the entire transient load curve of any appliance. This approach fully utilizes the advantages of electronic AC loads, enabling users to freely combine and arrange all desired load stages into a straightforward yet complete V2L testing solution.

▲List Mode settings page	▲Example of List Mode load waveform

To learn more about the functions and specifications of the Chroma 61815 Regenerative Grid Simulator, please visit our official website: