Currently, hybrid and electric drive control systems are being developed for many types of platforms in the aerospace, automotive, and commercial vehicle industries. These systems also entail the use of Battery Management Systems (BMS) to handle their demanding power needs. However, the development of these technologies brings increased system complexity, evident in the platform variants and even more so in the control algorithms of various electronic control units (ECUs). There is also a greater need to handle system-level control strategies, via communication networks and command software. This increased system complexity poses new challenges for software design and ECU system validation, mandating the need for simulation tools that can easily handle the inherent system complexity, while providing cost-effective, industry-proven verification tools and processes. These simulation and testing tools and processes must be capable of providing support for model-based design (MBD) at various stages in the process, from control concept simulation through final target system acceptance. The processes for MBD using Model-in-the-loop (MIL), Software-in-the-loop (SIL), and Hardware-in-the-loop (HIL) must take advantage of synergies in tools used throughout the process.This paper will describe the use of simulation tools for the validation of electric-drive and BMS control systems on HIL systems. This validation process involves specific implementation techniques for model processing and interfaces in real-time, along with critical power interface and electrical hardware functionality. Examples shown will include models for electric machines and battery cell stacks, all geared to optimize testing using efficient HIL simulation and test hardware and software. Key techniques for software design and testing using MBD will also be shown, with a focus on the tools and interfaces necessary to optimize these processes. This will include an overview of design processes for handling both real-time and offline simulation models and software, using standard COTS interfaces within the MBD environment.