Optimized thermal management systems for electric vehicles contribute to energy-efficient, economical and comfortable mobility. Turbine flow measurement systems made by DDM are a tailor-made measurement technology for on vehicle thermal management testing.
Most vehicles will be powered by electric motors in the future. The coming years will show whether the necessary energy will be stored in batteries or as hydrogen.
Both systems, BEV (Battery Electric Vehicle) and FCEV (Fuel Cell Electric Vehicle), require a sophisticated thermal management. These systems have batteries of different sizes that need perfect temperature control to achieve the highest possible capacity and service life. The powerful electric motors and their power electronics must be cooled. The interior should be air-conditioned to comfortable temperatures for the passengers. All these different temperature levels have to be conditioned according to the situation.
The flow rate and temperature of the coolant must be measured to read and tune the system components. DDM turbine meters are highly miniaturized to measure flow rate and medium temperature simultaneously at high accuracy in real time.
DDM have further developed the turbine flow meter (VCT) for testing and evaluation of the complex thermal management in electric vehicles with development goals as below.
The turbine flow meters (VCT) are particularly small and lightweight. They can be fitted where space is very limited, not to say where no space is available. Thanks to the weight reduction, no additional brackets are required. The coolant hose is able to safely support the turbine weight.
The turbine flow meters (VCT) are high dynamic flow meters and detect flow changes very quickly. Since temperature can fluctuate within the thermal management circuit a media exposed fast response thermocouple is integrated in the VCT housing. This provides faster and thus more accurate viscosity correction of the turbine flow meter.
Electric vehicles operate at high voltage and current levels. They could interfere with low level RF carrier frequencies used on traditional flow turbine meters. To overcome that potential risk the communication between turbine (VCT) and flow computer (VCA) is digitalized and raised to a new level in terms of EMC Interference immunity.
Linearization and viscosity correction
Valves in thermal management circuits may operate very quickly to control the different temperature levels. Therefore, a flow rate averaging, predefined by the manufacturer, may not perfectly match the measurement task. The flow computer (VCA) is user adjustable. It is possible to operate the flow computer in a “live mode” where the actual linearized and viscosity-corrected flow rate is available virtually without delay. Of course any other averaging between1ms to 5sec can be set.
By nature all turbine flow meters are affected by fluid viscosity changes. Each medium or mixtures of those have different viscosity characteristics. So it is quite common to change the fluid in the thermal management to evaluate a different water/glycol ratio. The adaption of the flow measurement system to the media in service is quick and very simple. Up to 10 media characteristics are stored in the flow computer (VCA), which can be toolless selected by means of an RFID tag.