EMA Global Engineering develops electronic control units and control logics for HVAC applications in the automotive field, with the aim of achieving the best performance in terms of air conditioning and comfort for vehicle users. We offer multi-physics modelling and analysis services in Matlab/Simulink for Automotive customers: car-makers or TIER1 suppliers of HVAC systems and subsystems who need to improve their products.

Models are designed in a hierarchical and modular way, with emphasis on configurability, maintainability and testability. The models are validated by comparing their behaviour with the real system one, assisting the customer during tests on his system.

Thanks to our HW/SW development skills, the control logics defined and validated on the model are developed in the HVAC electronic control unit software.

The use of tools for automatic code generation also limits errors in the integration phase. Specific test procedures make it possible to verify that the behaviour of the logics on the target adheres to those of the original model.

Finally, all the functional tests performed in simulation are replicated in a specially prepared test plan for climate tests on the vehicle, certifying the correct behaviour specified by the customer.

In the past, evaluating and fine-tuning the performance of HVAC system relied on engineers’ experience and required long test sessions in the car, repeating continuous cycles of testing and recalibration until the desired result was achieved. A calibration defined for a particular environmental condition outside the vehicle could be unsuitable in other conditions, requiring constant re-evaluation of the work done or accepting comfort compromises.

Testing an HVAC system implies several complications: firstly, the difficulty of keeping under control the initial conditions of the system and the external environmental conditions, such as temperature and heat sources used, as well as checking the correct timing of the various system controls. Furthermore, even for small vehicles, the thermal inertia of the air requires a lot of time to bring the system to the required temperature; also, the heating of the car components themselves (such as the engine) affects the boundary conditions and the repeatability of the tests. Finally, the impossibility of assessing the effectiveness of some architectural and calibration solutions requires repeating the same tests many times until the optimum result for the system is obtained.

Time and costs for this workflow were therefore very high.

The thermal modelling of a vehicle helps to anticipate the analysis of the correct functioning of the system already at the design stage, because it allows to simulate the behaviour of all its components: heating and cooling system, engine, radiator, recirculation and distribution flaps and, finally, the control software and its calibrations.