CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) to DE Application 10 2019 204 923.0 filed Apr. 5, 2019, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The disclosure relates to a motor vehicle cooling system and control for cooling a traction battery.

BACKGROUND

A traction battery (also referred to as a traction accumulator, drive battery or deep cycle battery) is an energy store which is used for driving electric vehicles or hybrid electric vehicles and consists of a number of interconnected elements. It consists of a small number to thousands of accumulator cells or cell blocks interconnected in parallel and in series.

During the charging of the traction battery with electrical energy, thermal energy is generated. Thermal energy is also generated when drawing electrical energy, for example while driving. Therefore, such motor vehicles have a cooling system for cooling the traction battery. An energy exchange takes place by way of coolants, air or refrigerants. However, the maximum possible heat exchange is restricted by structural conditions. Such cooling systems are known for example from DE 10 2014 204 260 A1, DE 10 2012 204 410 A1 and DE 10 2009 046 568 A1.

The efficiency of drawing energy from the traction battery depends on several parameters, such as the charging state, temperature level or electrical power taken. Generally, the efficiency is around 85% to 95%; in the case of rapid charging (the trend in the industry is toward values of over 150 kW) and in the case of high-load driving conditions (for example heavy vehicles driving uphill, maximum speed, racetrack driving), a particularly great amount of thermal energy is generated in the traction battery. In this case, the amount of thermal energy exceeds the capability of the cooling system.

The capability of the cooling system is limited by the capacity of a heat exchanger and also by a heat transfer surface and heat transfer coefficient between the traction battery and a cooling system. As soon as the battery temperature has reached a predetermined temperature limit, a battery management system (BMS) correspondingly reduces the permissible amount of energy that can be taken or supplied.

Even after a short time, this leads to a reduced charging rate and reduced capacity. In particular in the case of heavy vehicles with a high air resistance (for example a truck with a loading area of a large frontal area) and/or a high total weight, the limitation of the battery may already be reached after a few minutes of driving uphill.

There is therefore a need to show ways in which the operation of a motor vehicle with a cooling system for cooling a traction battery can be improved.

SUMMARY

Embodiments according to the present disclosure may include a method for operating a motor vehicle with a cooling system for cooling a traction battery, comprising a controller receiving trip data associated with a planned route and operating parameters of the traction battery, evaluating the trip data and the operating parameters to determine a set of data representative of a forecast temperature profile of the traction battery temperature, evaluating the set of data for the forecast temperature profile of the traction battery temperature to determine a phase of cooling demand output exceeding an associated threshold while completing the route, and buffer-storing cold energy while traveling the planned route by utilizing heat storage capacities of the traction battery before the phase of cooling output demand exceeding the threshold for providing the required battery power during the phase of high load demand, if a phase of particularly high cooling output demand while completing the route has been determined.

As such, according to one or more embodiments, before the beginning of the actual journey, it is determined on the basis of a forecast temperature profile whether the possibility of exceeding a predetermined temperature limit for the battery temperature exists or is likely. If this is the case, a cooling strategy for operating the cooling system is determined to provide cooling energy that can be buffer-stored to reduce the anticipated peak cooling demand to a value below the cooling capacity of the system at the anticipated peak power demand from the battery. In this way, the operation of a motor vehicle with a cooling system for cooling a traction battery can be improved.

According to one embodiment, a battery temperature profile associated with the phase of particularly high cooling output demand is determined, and a starting time for activating the cooling system is determined by evaluating at least the anticipated peak battery temperature and duration. The battery temperature profile and associated cooling system activation is analysed on the basis of reliably preventing exceeding of a predetermined temperature limit for the battery temperature. Then the time from which the cooling system is activated is determined. In this way, the cooling system can be operated in a particularly simple manner.

According to a further embodiment, a required battery temperature to which the traction battery is cooled down before the phase of particular demand is determined. Also in this way, the cooling system can be operated in a particularly simple manner.

According to a further embodiment, a vehicle weight is determined while traveling a section of the planned route, by evaluating vehicle operating parameters. In this way, the current vehicle weight in dependence on loading of the motor vehicle can be taken into account. In this way, the control of the cooling system of a motor vehicle for cooling a traction battery can be further improved.

Various embodiments may include a motor vehicle having a traction battery and cooling system control, a method for controlling a cooling system of an electrified vehicle, a computer program product having stored data including instructions for controlling such a system, and, a control unit or controller configured to control a cooling system as described with respect to any one or more embodiments disclosed herein.

