Power electronics module for an electric drive train of a battery-electric vehicle

Abstract

The present invention relates to a power electronics module (1) for an electric drive train (20). Said module comprises a high-voltage battery (2) for supplying a high-voltage electrical system (22) of the electric drive train (20) with electrical energy. Furthermore, the power electronics module comprises at least one electrically energizable coil (3) for generating a magnetic field. Furthermore, the power electronics module (1) comprises an electrical circuit arrangement (4) electrically connecting the high-voltage battery (2) to the at least one coil (3). By means of this electrical circuit arrangement (4), electrical energy from the high-voltage battery (2) can be supplied to the at least one coil (3) for generating the magnetic field. Finally, the power electronics module (1) comprises an electrical bridge circuit (5) for adjusting and controlling the energy transfer from the high-voltage battery (2) to the coil (3).The bridge circuit (5) comprises at least two semiconductor switches, each of which can be switched between an open and a closed state. In this way, the magnetic field generated by the at least one coil (3) for the eddy current brake can also be adjusted and controlled.

Description

The present invention relates to a power electronics module for an electric drive train of a battery-electric vehicle and to a drive train having such a power electronics module.Battery-electric vehicles increasingly have a high-voltage on-board power supply system ("HV on-board power supply system") with a high-voltage battery for supplying the drive train with electrical energy. The output voltage provided by the high-voltage battery to the HV on-board power supply system can assume values of up to 800 V. This allows a comparatively low-loss operation of the drive train, in particular when the vehicle is to be accelerated. For braking, battery-electric vehicles, as well as motor vehicles with an internal combustion engine, are generally equipped with conventional drum brakes or disc brakes. However, such friction-based brake systems are subject to high wear and are therefore also maintenance-intensive. Accordingly, relatively high maintenance costs are also obtained.Against this background, it is an object of the present invention to provide solutions for battery-electric vehicles, by means of which solutions the above-explained disadvantages which occur when using conventional vehicle brakes are at least partially eliminated.This object is achieved by the subject matter of the independent claims. Preferred embodiments are the subject of the dependent claims.The basic idea of the invention is therefore to use power electronics provided for a drive train of a battery-electric vehicle with a high-voltage battery for a high-voltage on-board electrical system for the electrical energization of an eddy current brake which can be used in the vehicle. The use of an HV on-board power supply as an energy source offers the advantage that a particularly large amount of electrical power and a high dynamic range are available for activating the eddy current brake. Due to the high electrical voltage level, electrical currents through components of the power electronics including the eddy current brake can be kept small. This is associated advantageously with a low power loss. In addition, the power electronics can be constructed using cost-effective technologies, such as printed circuit board technology. This in turn proves to be helpful for fast control functions, such as are required for an anti-lock system implemented by means of the eddy current brake.Following the inventive idea explained above, an inventive power electronics module for an electric drive train comprises a high-voltage battery for supplying an on-board high-voltage electrical system of the electric drive train with electrical energy. Furthermore, the power electronics module comprises at least one electrically energizable coil for generating a magnetic field. By means of this magnetic coil, electric eddy currents can be induced in an eddy current brake of the drive train. The power electronics module further comprises an electrical circuit arrangement electrically connected to the high-voltage battery with the at least one coil. By means of this electrical circuit arrangement, electrical energy from the high-voltage battery can be supplied in a targeted manner to the at least one coil for generating the magnetic field. Finally, the power electronics module according to the invention comprises an electrical bridge circuit for adjusting and controlling the high-voltage battery of the amount of energy transmitted to the coil. The bridge circuit of the power module according to the invention comprises at least two semiconductor switches which are designed for transmitting high electrical powers or currents. Each semiconductor switch of the bridge circuit is switchable between an open and a closed state. In the open state, the electrical conductor path in which it is arranged is interrupted. In the closed state, this interruption is canceled, so that an electric current can flow through the semiconductor switch and thus also through the conduction path with the switch. In this way, the magnetic field generated by the at least one coil for the eddy current brake can also be adjusted and controlled. Finally, the entire eddy current brake can be set and controlled, in particular activated and deactivated.In a preferred embodiment of the power electronics module, the electrical bridge circuit comprises a semi-controlled full bridge having two controllable semiconductor switches, which can each be switched over between an open state and a closed state, and having two protective diodes, which are configured in a conventional manner, i.e. in an uncontrolled manner, electrically in series between the two semiconductor switches, the at least one coil is arranged. By means of the semiconductor switches, the electrical connection of the high-voltage battery to the coil present in the closed state can be interrupted by switching into the open state in each case. This means that when at least one of the two semiconductor switches is switched over into the open state, the transmission of electrical energy to the coil is interrupted, so that no eddy currents are generated either.In another preferred embodiment, the above-presented electrical bridge circuit may even comprise a full-controlled full bridge with four semiconductor switches instead of a half-controlled full bridge. The structure and the electrical circuit of such a full bridge are known to the relevant person skilled in the art, so that a more detailed explanation in this respect can be omitted at this point. By means of the two semiconductor switches which are additional in relation to the half-controlled full bridge--these two additional semiconductor switches can replace diodes which are present in the half-controlled full bridge and are each arranged electrically in series with the two semiconductor switches--electrical power losses when supplying the at least one coil with electrical energy from the high-voltage battery and in particular when interrupting the electrical connection between the high-voltage battery and the at least one coil are reduced by a not inconsiderable amount in relation to the half-controlled full bridge.According to an advantageous development, the power electronics module comprises an electronic control unit, which can be designed in particular as a microcontroller or can comprise such a microcontroller. By means of the control unit, the individual semiconductor switches of the electrical circuit arrangement can be switched between the open and the closed state. In this case, an electrical connection is established between the high-voltage battery and the at least one coil in the closed state via the respective semiconductor switch when the coil is in the closed state. In contrast, said electrical connection is interrupted when the respective semiconductor switch is in the open state.Particularly preferably, the control unit for supplying electrical energy can be electrically connected to the high-voltage battery. This means that the electrical control unit draws electrical energy directly from the high-voltage battery of the power electronics module. This construction is particularly simple to implement electrically and is thus cost-effective.Alternatively, however, it can also be provided in a likewise advantageous manner that the control unit for supplying electrical energy is electrically connected to a low-voltage battery which provides a lower electrical output voltage than the high-voltage battery. Typically, the low voltage battery may provide an output voltage in the range between 12V and 20V. The low-voltage battery can be provided for supplying an on-board low-voltage system with electrical energy and for this purpose can be electrically connected to this on-board low-voltage system. Electrical consumers can in turn be connected to the low-voltage on-board power supply system.Particularly preferably, the low-voltage battery for the purpose of obtaining electrical energy can be electrically connected to the high-voltage battery via a DC-to-DC converter. Such a DC-DC converter is also known to the person skilled in the art under the designation DC-DC converter. It can be electrically connected to the high-voltage battery with a high-voltage side and to the low-voltage battery with a low-voltage side. The high-voltage side of the DC-DC converter can preferably be inductively coupled to the low-voltage side, which implies that the high-voltage side is galvanically isolated from the low-voltage side.According to a further advantageous refinement of the power electronics module according to the invention, the latter can have at least two coils, preferably a plurality of coils, which are arranged in an electrical series circuit. In this way, a high-voltage battery with a comparatively high electrical output voltage, in particular between 200 V or 800 V, can be used to electrically current the existing electrical coils of the series circuit.According to another advantageous refinement of the power electronics module according to the invention, the latter can have at least two coils, preferably a plurality of coils, which are arranged in an electrical parallel circuit. In this way, a high-voltage battery with a comparatively low electrical output voltage, in particular between 40 and 200 V, can be used to electrically supply current to the existing electrical coils of the parallel circuit. Alternatively, when using a high-voltage battery with a comparatively high electrical output voltage, in particular between 200 V or 800 V, a high dynamic may be realized.Particularly preferably, the power electronics module can have a plurality of coils which form a coil network. This coil network in turn comprises-analogously to a resistor network with ohmic resistors-at least one, preferably a plurality of, electrical series circuit(s) with at least two coils and at least one, preferably a plurality of, parallel circuit(s) with at least two coils. In this way, the aforementioned advantages of series and parallel electrical connections can be combined.Particularly expediently, at least one semiconductor switch, preferably each of the semiconductor switches, can be formed by a bipolar transistor, in particular by an IGBT, or by a unipolar transistor, preferably by a field effect transistor, in particular by a MOSFET. The aforementioned semiconductor switch is suitable for controlling the electrical currents required for supplying electric current to the at least one coil with low electrical power loss.The invention also relates to an electric drive train for a battery electric vehicle. The drive train comprises at least one electric drive for driving the vehicle and at least one electric eddy current brake for braking the vehicle. Furthermore, the electric drive train comprises a high-voltage on-board power supply system for supplying the drive with electrical energy. Finally, the drive train comprises a power electronics module according to the invention presented above, the high-voltage battery of which is electrically connected to the high-voltage on-board power supply system. The high-voltage battery thus functions as an electrical energy source of the high-voltage on-board power supply system, and the at least one coil thereof forms part of the eddy current brake.Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the description which follows.They show, in each case schematically: FIG. 1 shows, by way of example, the structure of a power electronics module according to the invention with a semicontrolled full bridge in a circuit diagram-like illustration, FIG. 2 shows a variant of the power electronics module of FIG. 1, in which the electrical bridge circuit with a semi-controlled full bridge shown in FIG. 1 is replaced by a fully controlled full bridge, FIGS. 3 to 5 are greatly simplified schematic diagrams illustrating the arrangement of a plurality of electrical coils in an electrical series connection or in an electrical parallel connection or at least one combination of both types of circuit.FIG. 1 shows, in a schematic diagram-like illustration, by way of example, the structure and the electrical wiring of a power electronics module 1 according to the invention for an electrical drive train 20 according to the invention, which is not illustrated in any more detail in the figures. According to FIG. 1, the power electronics module 1 comprises a high-voltage battery 2 for supplying a high-voltage on-board power supply 22 of the electric drive train 20 with electrical energy.The drive train 20 comprises an electric drive 21 for driving the vehicle and an electric eddy current brake 23 for braking the vehicle (indicated only roughly schematically in FIG. 1 ). Furthermore, the electric drive train 20 comprises a high-voltage on-board power supply system 22 for supplying the drive 21 with electrical energy. Finally, the drive train 20 comprises the power electronics module 1, the high-voltage battery 2 of which is electrically connected to the high-voltage on-board power supply system 22, with the result that the high-voltage battery 2 functions as an electrical energy source of the high-voltage on-board power supply system 22. The high-voltage battery 2 can provide an electrical output voltage U-DC between 40 V and 800 V between an electrical positive output 25 or positive terminal 26 and an electrical negative output 27 or negative terminal 28. Electrical output voltages of 40 V, 400 V or 800 V are preferred.If the high-voltage battery 2 is connected to a high-voltage on-board power supply system 22 of the drive train 20, as indicated schematically in FIG. 1, the on-board power supply system voltage of the high-voltage on-board power supply system 22 is equal to the electrical output voltage U-DC of the high-voltage battery.Furthermore, the power electronics module 1 comprises an electrically energizable coil 3, indicated only schematically in the circuit diagram of FIG. 1 in the form of an inductance L in combination with an ohmic resistor R L for generating a magnetic field. By means of the magnetic field generated by the coil 3, electric eddy currents can be induced in the eddy current brake 23 of the drive train 20 in a known manner. The coil 3 can thus be part of the eddy current brake 23. Following the Lenz rule, these eddy currents generate a magnetic counter-field which is directed opposite the magnetic field generated by the coil 3 in the eddy current brake 23 and which brings about the desired braking torque.Furthermore, the drive train comprises an electrical circuit arrangement 4 electrically connecting the high-voltage battery 2 to the coil 3. Electrical energy can be supplied from the high-voltage battery 2 in a targeted manner to the coil 3 in order to generate the magnetic field by means of the electrical circuit arrangement 4. Finally, the power electronics module 1 comprises an electrical bridge circuit 5 for adjusting and controlling the amount of energy transmitted from the high-voltage battery 2 to the coil 3. In this way, the magnetic field generated by the coil 3 for the eddy current brake 23 can also be adjusted and controlled. In this way, the eddy current brake 23 can be controlled and in this case in particular activated and deactivated.In the example of FIG. 1, the electrical bridge circuit 5 comprises a semi-controlled full bridge 6 having two semiconductor switches 7 a, 7 bwhich are each switchable between an open state and a closed state. Arranged between the two semiconductor switches 7 a, 7 b, electrically connected in series, is the electrically energizable coil 3 of the eddy current brake 23. For the electric current to the coil 3, the two semiconductor switches 7 a, 7 bmust both be in the closed state. By means of the two semiconductor switches 7 a, 7 b, the electrical connection of the high-voltage battery 2 to the coil 3 present in the closed state can be interrupted by switching into the open state in each case. In this case, it is already sufficient if one of the two semiconductor switches 7 a, 7 bis switched to the open state in order to end the electrical energization of the coil 3. In the event of a malfunction in one of the two semiconductor switches 7 a, 7 b, the respective other semiconductor switch 7 b, 7 acan ensure termination of the electrical energization 3 of the coil by switching over into the open state.As can also be seen from FIG. 1, the half bridge 6 also comprises a first protective diode 16 aconnected electrically in series with the first semiconductor switch 7 aand a second protective diode 16 bconnected electrically in series with the second semiconductor switch 7 b. The first semiconductor switch 7 aand the first protection diode 16 aform a first half-controlled half bridge 29 a, since the first semiconductor switch 7 ais designed to be controllable and the first protection diode 16 ais designed to be non-controllable. The second semiconductor switch 7 band the second protection diode 16 aform a second half-controlled half bridge 29 b, since the second semiconductor switch 7 bis designed to be controllable and the second protection diode 16 bis designed to be non-controllable.The coil 3 is arranged in an electrical conduction path 17 whose first end 18 ais connected to a first electrical branch 19 aarranged between the first protection diode 16 aand the first semiconductor switch 7 a. A second end 18 bof the electrical conduction path 17 with the coil 3 is connected to a second electrical branch 19 barranged between the second protection diode 16 band the second semiconductor switch 7 b.FIG. 2 illustrates a variant of the example of FIG. 1. the variant of FIG. 2 differs from the example of FIG. 1 in that the electrical bridge circuit 5 explained with reference to FIG. 1 in FIG. 2 has a fully controlled full bridge 8 with four semiconductor switches 9 a- 9 d, instead of a semi-controlled full bridge 6. The two controllable semiconductor switches 9 c, 9 dadditively to the half-controlled full bridge 6 replace the two protective diodes 16 a, 16 bprovided in the half-controlled full bridge 6 of FIG. 1 and each arranged electrically in series with the two semiconductor switches 7 a, 7 bin accordance with FIG. 2. A third semiconductor switch 9 cof the full bridge 8 is thus electrically connected in series with the first semiconductor switch 7 a. A fourth semiconductor switch 9 bis electrically connected in series with the second semiconductor switch 7 b. In comparison with the semi-controlled full bridge 6 according to FIG. 1, when using a fully controlled full bridge 8 with two additional controllable semiconductor switches 9 c, 9 d, electrical power losses during the electrical energization of the coil 3 and in particular during the termination of the energization are reduced by interrupting the electrical connection between the high-voltage battery 2 and the coil 3. Moreover, the electric coil 3 can be magnetically discharged particularly quickly, if desired.Both in the example of FIG. 1 and in the example of FIG. 2, the power electronics module 1 comprises an electronic control unit 10, which can be formed, for example, by a microcontroller. By means of the control unit 10, the individual controllable semiconductor switches 7 a, 7 band 9 a- 9 dof the bridge circuit 5 can be switched between an open and a closed state. In the closed state, an electrical connection is established between the high-voltage battery 2 and the coil 3 via the relevant semiconductor switch 7 a, 7 b; 9 a- 9 dwhen the latter is in the closed state. On the other hand, said electrical connection through the respective semiconductor switch 7a, 7b; 9a-9d is interrupted when the respective semiconductor switch 7a, 7b; 9a-9d is in the open state.In the example of FIG. 1, the two semiconductor switches 7 a, 7 bare each formed by a bipolar transistor, for example an IGBT.In the example of FIG. 2, the semiconductor switches 9 a- 9 dare each formed by a unipolar transistor, in particular a field effect transistor, for example a MOSFET.In the example scenario, it is provided that the control unit 10 for supplying electrical energy is electrically connected to a low-voltage battery 11 which provides a lower electrical output voltage than the high-voltage battery 2. The low-voltage battery 11 serves to supply an on-board low-voltage system 24 with electrical energy and is electrically connected to this on-board low-voltage system 24 for this purpose. Electrical consumers (not shown) can in turn be connected to the low-voltage on-board power supply 24.For the purpose of obtaining electrical energy from the high-voltage battery 2, the latter can be electrically connected to the high-voltage battery 2 via a DC-to-DC converter 12. Such a DC-DC converter 12 is known under the designation "DC-DC converter" and can have a high-voltage side 29 and a low-voltage side 30. The high-voltage side 29 of the DC-DC converter 12 is then coupled-for example inductively-to the low-voltage side 30, which means that the high-voltage side 29 is galvanically isolated from the low-voltage side 30. The high-voltage side 29 is in turn electrically connected to the high-voltage battery 2 and the low-voltage side 30 is electrically connected to the low-voltage battery 11, as illustrated.Alternatively, the electric power supply control unit 10 may be electrically connected to the high-voltage battery 2 (not shown). This means that the electrical control unit 10 draws electrical energy directly from the high-voltage battery 2 of the power electronics module 1. This construction is particularly simple to implement electrically and is thus cost-effective.FIGS. 3 to 5 show greatly simplified, circuit-diagram-like representations, which illustrate possible electrical connections of two or more electrically energizable coils 3 of the eddy current brake 23.In the example of FIG. 3, N electrically energizable coils 3 are exemplarily arranged in an electrical series circuit in the electrical conduction path 17, wherein N is a natural number >1. In this way, a high-voltage battery 2 with a comparatively high electrical output voltage, in particular between 200 V or 800 V, can be used to electrically current the existing electrical coils of the series circuit.In the example of FIG. 4, N electrically energizable coils 3 are exemplarily arranged in an electrical parallel circuit in the electrical conduction path 17, wherein here too N is a natural number >1. In this way, a high-voltage battery 2 with a comparatively low electrical output voltage U-DC, in particular between 40 and 200 V, can be used to electrically current the existing electrical coils of the parallel circuit. Alternatively, when using a high-voltage battery with a comparatively high electrical output voltage U-DC, for example between 200 V or 800 V, a high dynamic range can be realized.FIG. 5 shows a combination of the examples of FIGS. 3 and 4 in the form of a coil network 15 comprising a plurality of coils 3. In the coil network 15, the individual coils 3 are electrically connected in series and electrically in parallel with other coils 3. In this way, the aforementioned advantages of series and parallel electrical circuits can be combined.

Claims

Power electronics module (1) for an electric drive train (20) of a battery-electric vehicle, - having a high-voltage battery (2) for supplying a high-voltage on-board power supply system (22) of the electric drive train (20) with electrical energy, - having at least one electrically energizable coil (3) for generating a magnetic field, by means of which electrical eddy currents can be induced in an eddy current brake (23) of the drive train (20), - having an electrical circuit arrangement (4) which electrically connects the high-voltage battery (2) to the at least one coil (3) and by means of which electrical energy can be supplied from the high-voltage battery (2) to the coil (3) for generating the magnetic field, - wherein the electrical circuit arrangement (4) comprises an electrical bridge circuit (5) for setting and controlling an electrical energy transmission from the high-voltage battery (2) to the coil (3).Power electronics module according to Claim 1, characterized in that the electrical bridge circuit (5) comprises a semicontrolled full bridge (6) having two controllable or switchable semiconductor switches (7a, 7b), each for interrupting the electrical connection of the high-voltage battery (2) to the coil (3), between which the at least one coil (3) is arranged, likewise connected in series, so that, when at least one of the two semiconductor switches (7a, 7b) is switched into an open state, the transmission of electrical energy to the coil (3) is interrupted.Power electronics module according to Claim 1, characterized in that the bridge circuit (5) comprises a full bridge (8) having four controllable or switchable semiconductor switches (9a-9d).Power electronics module according to one of Claims 1 to 3, characterized in that the power electronics module (1) comprises an electronic control unit (10), in particular a microcontroller (11), for switching the semiconductor switches (7a, 7b; 9a-9d) between an open and a closed state, wherein an electrical connection between the high-voltage battery (2) and the at least one coil (3) is produced in the closed state and is interrupted in the open state via the relevant semiconductor switch (7a, 7b; 9a-9d).Power electronics module according to Claim 4, characterized in that the control unit (10) is electrically connected to the high-voltage battery (2) for supplying electrical energy.Power electronics module according to Claim 4, characterized in that the control unit (10) for supplying electrical energy is electrically connected to a low-voltage battery (11).Power electronics module according to Claim 6, characterized in that the low-voltage battery (11) for obtaining electrical energy is electrically connected to the high-voltage battery (2) via a DC-to-DC converter (12).Power electronics module according to one of the preceding claims, characterized in that at least two coils (3), preferably a plurality of coils (3), are provided, which are arranged in an electrical series circuit (13).Power electronics module according to one of the preceding claims, characterized in that at least two coils (3), preferably a plurality of coils (3), are provided, which are arranged in an electrical parallel circuit (14).Power electronics module according to one of the preceding claims, characterized in that a plurality of coils (3) is provided, which form a coil network (15), which has at least one, preferably a plurality of, series circuit(s) (13) and at least one, preferably a plurality of, parallel circuit(s) (14).Power electronics module according to one of the preceding claims, characterized in that at least one semiconductor switch (7a, 7b; 9a-9d) is formed by a bipolar transistor, preferably a field effect transistor, particularly preferably by a MOSFET, or by a unipolar transistor, in particular by an IGBT.An electric drive train (20) for a battery-electric vehicle, - with an electric drive (21) for driving the vehicle, - with an electric eddy current brake (23) for braking the vehicle, - with a high-voltage on-board power supply system (22) for supplying the drive with electric energy, - with a power electronics module (1) according to one of the preceding claims, the high-voltage battery (3) of which is electrically connected to the high-voltage on-board power supply system (22), so that the high-voltage battery (2) functions as an electric energy source of the high-voltage on-board power supply system (22), and the at least one coil (3) of which forms part of the eddy current brake (23).

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