Testing with Hardware-in-the-Loop Simulation

Advantages of HIL Simulation
After the ECU functions have been developed and implemented on the production ECU, they have to be tested thoroughly. With hardware-in-the-loop (HIL) simulation, you can easily cover all the different motor varieties and their ECUs.
The ECU’s environment (interacting components or even a whole system), is simulated.
This has several advantages:

  • Function tests are possible at an early development stage, even before all parts are available in reality.
  • Laboratory tests reduce time and cost and take place under controlled conditions.
  • Failures, and the ECU’s behavior in what are normally dangerous situations, can be tested with no risk for the driver or the controlled machine.
  • The tests are reproducible and can be automated.


Challenges of Testing ECUs for Electrical Motors
Electrical motors have been getting more and more powerful in a wide range of applications. The conventional brushed direct current (BDC) motors were replaced by brushless direct current (BLDC) motors. The ECUs controlling the electric motors provide the actuation power directly. This is unlike other applications, where thermodynamic or hydraulic power is controlled by means of low auxiliary power coming from the ECU.
ECUs for controlling electric motors are often incorporated into complex and distributed vehicle functions, so it is essential to test their interaction with other ECUs.

Special solutions are needed for interfacing the ECU.

  • High power level
  • High dynamics
  • Special I/O, for example for encoders and resolvers



HIL Interfaces
An ECU or other system for controlling electrical motors can be accessed by the HIL simulator at different levels. Which interface to use depends on the testing purpose and project conditions.

  • Signal level: Simulation of the power electronics, the electric motor, and the mechanical environment

    • Very scalable, as parameters can be set flexibly regardless of power level
    • Full access to the model
    • ECU must be opened
  • Electric power level: Simulation of the electric motor and the mechanical environment

    • Production ECU can be used
    • Full access to the model
    • Motor parameters can be set flexibly within a certain power range
       
  • Mechanical power level: Simulation of the mechanical environment
    • Using the real motor on a test bench for motor loads
    • Effects of the real motor and additional mechanical parts on the controller can be taken into account
    • No detailed knowledge of the motor necessary
    • Less flexible with regard to changing motor parameters


Battery Simulation
dSPACE offers special hardware and software for battery simulation:

  • Real-time hardware for HIL tests with high voltage accuracy and galvanic separation
  • Simulation models for lithium-ion batteries and nickel metal hydride batteries for realistic battery management tests


Simulation Models
For real-time simulation of an electrical system, dSPACE provides the ASM – Electric Components Library.
Applications can range from electric drives and inverters for closed-loop simulation with an electric drive controller, to a complete automotive electrical system including battery, starter, alternator, and loads. Typical use cases are the simulation of realistic battery behavior during starter activation, electric drives that are integrated into a hybrid electrical vehicle powertrain, etc.