Drive Systems

Working group "drive systems"
Speaker: Dr. Pelz, Infineon

Task distribution within the working group:
Infineon : Definition and realization of the demonstrators, allocation of the measured data, modeling of the drive electronics
CADFEM : Modeling of the drive technique phenomena on physical level with ANSYS, model reduction, interface to the circuit level with VHDL-AMS
Dolphin Integration : Modeling of the demonstrators on circuit level, implementation in VHDL-AMS

Background

The usage of simulation methods during the product development process is grown to a standard method, since the complexity of the systems to develop constantly increases. With the advancement of simulation tools and modeling languages it is now possible to simulate microelectronic as well as attached periphery, i.e. complete mechatronic systems. The work group "drive systems" demonstrates among the example from the automobile industry, a window lifter, the simulation of a microcontroller with application program and attached electro-mechanics the domain-spreading simulation.

Microsystem

The Microsystem comprises a micro controller and power electronic. The behavior of all analogue and mixed-signal components of the system is modeled in VHDL-AMS. This hardware description language is ideal for the description of digital and analogue systems and supports language constructs, which supports a fast simulation without losing precision. The micro controller is modeled in SystemC for the cycle correct and extremely fast simulation.

Figure 1: Mikrosystem

Macrosystem

The window lifter consists of an electric motor with attached gearbox, load and hall sensor for the position feedback. The elements of the Macrosystem are modeled in VHDL-AMS because of the same reasons mentioned above. This permits to simulate the entire mechatronic system (the complete micro-system and the attached electro-mechanics inclusive its mutual influences).

Figure 2 : Macrosystem

Methodology

Concerning the modeling of electromagnetic mechanic components it showed up that it is not meaningful to model the whole subsystem and/or the individual components in one model. Fundamental physical effects, which occur in and between the components, e.g. coil inductance and the coil resistance of the electric motor, or the rotating mass inertia of the gear wheel were modeled as single models. With the developed models a multiplicity of applications and/or systems can be modeled, like with a model building set. The effects which appear in the subsystems become "plugged together". Because of their re-useability, the models are extremely universal.

Simulation

With the help of the simulation the whole functionality of the system can be virtually proved and weak points promptly recognized and eliminated. These simulations are milestones in the SiP verification, because they help to avoid complex re-designs. A restriction with this kind of simulation is obvious: only those effects can be considered, which were modeled. Like it is well known that e.g. self heating is an important topic, which is to be considered. If however a special effect, which affects the system performance, isn't included into the model, the system can fail although the simulation was successful.

Figure 3: Early system simulation

Conclusion

The shown system served as demonstrator for a complete system simulation and shows its possibilities. Thus most diverse scenarios before the tape out of a chip can be examined. Still more, with the help of the simulation possible problems can be examined and fixed fast. In summary it shows up that the represented procedure helps to attain a better understanding over the behavior of a complex SiP and its environment.

Further Information

The methodology, which was worked out in this project is the basis for further developments, which are available already now or in the near future or according they will be available commercially soon.
The models of the not purely electronic behavior for the simulation in an electronic simulatior were summarized in the EMBLEM libraries of Dolphin Integration.
Because of the usage of the IEEE standardized modeling language VHDL-AMS for the implementation, these models can be used in all simulators, which make a sufficient language support available. In this project the AMS-Designer from Cadence and the single kernel, mixed-signal simulator SMASH were used.
For the integration of microprocessors and the link to software in a circuit simulation SMASH offers an interface to SystemC and to Instruction Set Simulators (ISS).

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