BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a device, to a system and to a method for charging an electrochemical energy store, in particular a vehicle battery, and to a vehicle having such a system.

To supply electrically driven vehicles, in particular automobiles, with the required energy, electrochemical energy stores are generally provided in the vehicles. Various charging standards exist for recharging the energy stores. The vehicles may usually be connected to the public electricity grid or use special power charging points that provide AC, three-phase or DC current for charging purposes depending on the standard. As alternatives to wired energy transfer systems, wireless energy transfer systems are also being developed, these allowing particularly convenient and simple charging of the energy stores.

To allow efficient and considerate recharging of the energy stores, charge is usually drawn from the energy stores and this charge is used to heat the energy stores during the charging procedure. For this purpose, a resistive heating element may for example be integrated into the energy store or arranged in the region of the energy store, by virtue of which the energy store is able to be heated to a predefined or required temperature.

One object of the invention is to further improve the charging procedure of an electrochemical energy store, in particular to allow a high power consumption by the energy store with at the same time increased service life of the energy store.

A device according to the invention for charging an electrochemical energy store, in particular a vehicle battery, has a charging apparatus and a heating apparatus. The charging apparatus is configured so as to charge the electrochemical energy store and has a first current circuit that is electrically coupled or is able to be electrically coupled to the electrochemical energy store. The heating apparatus is configured so as to heat the electrochemical energy store and has a second current circuit, separate from the first current circuit, having an induction heating element able to be heated inductively by an external magnetic alternating field, wherein the induction heating element is thermally coupled or is able to be thermally coupled to the electrochemical energy store.

A system according to the invention for charging an electrochemical energy store has an electrochemical energy store, in particular a vehicle battery, and a device according to the invention for charging the electrochemical energy store.

A vehicle according to the invention, in particular a motor vehicle, has a system according to the invention for charging an electrochemical energy store.

A method according to the invention for charging an electrochemical energy store, in particular a vehicle battery, has the following steps: generating an external magnetic alternating field; heating the electrochemical energy store by way of an induction heating element thermally coupled to the electrochemical energy store, which induction heating element is heated inductively by the external magnetic alternating field; and charging the electrochemical energy store by electrically coupling a first current circuit, which is separate from a second current circuit having the induction heating element, to the electrochemical energy store.

One aspect of the invention is based on the approach of heating an electrochemical energy store prior to charging and/or during charging by way of an induction heating element, wherein a first current circuit is provided for charging purposes and a second current circuit that is in particular spatially and/or electrically separate from the first current circuit and is thus able to be controlled independently is provided for heating purposes. As a result, the heating process is able to be controlled independently from the charging process and adjusted for example to the state of charge and/or a temperature of the energy store or to an ambient temperature.

Since the induction heating element is heated inductively by the external magnetic alternating field, the procedure of heating the energy store may be controlled or influenced externally, that is to say from outside a vehicle in which the energy store is situated. The heating power is in this case in particular provided externally and does not have to be drawn from the energy store itself, as a result of which this is able to be subjected to less load and its service life is able to be increased.

Overall, the invention allows improved, in particular efficient, charging of an energy store that preserves the energy store.

The inductive heating of the induction heating element or of the energy store is preferably started as soon as the vehicle is positioned, in particular parked, in the region of a power charging point or in a parking space, for instance in a garage. As a result, the energy store may already be brought to a temperature, in particular above a melting point of an electrolyte contained in the energy store, before the actual charging process start, for example by connecting a charging cable to the charging apparatus.

In one preferred configuration, the first current circuit has an induction element in which a current for charging the electrochemical energy store is able to be induced by the external magnetic alternating field. The induction element is preferably designed as a coil that is able to be penetrated by the magnetic flux of the external magnetic alternating field. As a result, the energy of the external magnetic alternating field may advantageously be used both to heat the electrochemical energy store prior to the charging process or during the charging process and to charge the electrochemical energy store.

In a further preferred configuration, the induction element has a first coil that is configured so as to absorb energy of the external magnetic alternating field at the first harmonic (fundamental frequency) of the external magnetic alternating field. In this case, the absorption at the first harmonic of the magnetic alternating field allows a particularly efficient transfer of the energy in order to charge the energy store.

In a further preferred configuration, the induction heating element has a high-resistance second coil that is configured so as to absorb energy of the external magnetic alternating field at the first harmonic (fundamental frequency) and/or a higher harmonic of the external magnetic alternating field. The second coil is in this case preferably made from a material having a high electrical resistance, in particular a specific resistance of 0.1 Ωmm2/m or higher, preferably of 0.4 Ωmm2/m or higher, in particular of 1 Ωmm2/m or higher. The second coil is in this case preferably made from one or more alloys that contain nickel, manganese, copper and/or chromium and/or transition metal compounds. A situation is thereby able to be achieved whereby the second coil heats up to a great extent upon absorbing the energy of the external magnetic alternating field. This allows efficient and reliable heating of the energy store.

Since the second coil is configured so as to absorb energy of the external magnetic alternating field at a higher harmonic of the external magnetic alternating field, the amount of energy absorbed by the second coil is able to be adjusted independently of the energy coupled into the first coil of the first current circuit at the first harmonic. A majority, in particular more than half, of the energy of the external magnetic alternating field may in particular be used to charge the energy store and a smaller proportion, in particular less than half, of the energy of the external magnetic alternating field may be used to heat the energy store. As a result, excessive heating of the energy store is able to be avoided and the energy store is able to be charged efficiently.

In a further preferred configuration, the heating apparatus has a line arranged in the region of the induction heating element, which line is configured so as to transport a medium able to be heated by the heated induction heating element to the electrochemical energy store. As a result, reliable thermal coupling of the induction heating element to the electrochemical energy store may be made possible. It is in particular in this case not absolutely necessary to arrange the energy store in the region of the second current circuit or induction heating element, as a result of which it is made significantly easier to integrate the device according to the invention in a vehicle. In this configuration, the energy store may preferably be heated without the energy store being put into operation, as a result of which power losses due to what is known as a standing voltage are able to be avoided during heating.

The line is in this case preferably arranged, in particular wound, around the induction heating element, in particular in a spiral shape. As an alternative, however, the induction heating element may also be arranged, in particular wound, around the line, in particular in a spiral shape. In both cases, the heatable medium is heated efficiently and/or the emission of non-useful heat losses is reduced.

In a further preferred configuration, the line is integrated, in particular cut, into the induction heating element, as a result of which the gravimetric power of the system is able to be increased significantly.

It is furthermore preferable to use a coolant of an energy store cooling system as heatable medium, which coolant is designed to cool the energy store during operation, that is to say when drawing electrical energy from the energy store. The line arranged in the region of the induction heating element is preferably part of the energy store cooling system.

In a further preferred configuration, the device according to the invention has a control apparatus that is configured so as to control a first switching element of the first current circuit for interrupting or closing the first current circuit and/or a second switching element for interrupting or closing the second current circuit such that the electrochemical energy store heats up, in particular only heats up, in a first control mode, the electrochemical energy store is charged, in particular is only charged, in a second control mode, and the electrochemical energy store heats up and is charged at the same time in a third control mode. As a result, the energy of the external magnetic alternating field is able to be used in a targeted and efficient manner to heat and/or charge the energy store. The heating of the electrochemical energy store may furthermore be adjusted and controlled dynamically, for example with respect to the state of charge of the energy store.

In a further preferred configuration, the device according to the invention has a temperature sensor unit that is configured so as to record a temperature of the electrochemical energy store. The control apparatus is in this case preferably configured so as to change from the first control mode to the second control mode when the determined temperature reaches or exceeds a predefined temperature threshold value. As an alternative or in addition, the control apparatus is configured so as to change from the second control mode to the first control mode when the determined temperature falls below a predefined temperature threshold value. By virtue of both configurations, a situation whereby the energy store is charged at a low temperature, in particular below the melting point of an electrolyte of the energy store, is able to be reliably avoided. Considerate and efficient charging of the energy store is thus made possible.

In a further preferred configuration, the second current circuit has a temperature-dependent electrical resistance that regulates, in particular limits, the heating of the induction heating element or of the second current circuit upon reaching or exceeding the predefined temperature threshold value.

In a further preferred embodiment, the system according to the invention has an exciter coil apparatus for generating the external magnetic alternating field. The exciter coil apparatus is in this case preferably configured so as to generate the external magnetic alternating field at a stable predefined fundamental frequency, what is known as the first harmonic. As a result, the first and/or second coil of the first or second current circuit is easily able to be introduced into the external magnetic alternating field, such that an electric current for charging the energy store is able to be induced reliably or inductive heating of the induction heating element is able to be brought about.

Further features, advantages and application possibilities of the invention become apparent from the following description in connection with the figures, throughout which the same reference signs are used for the same or mutually corresponding elements of the invention. In the figures, at least partly schematically:

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.

