A BATTERY JUNCTION BOX AND A BATTERY PACK FOR A VEHICLE

Abstract

A battery junction box, comprising: a first input connected to a first output via a switch circuit, which switch circuit is configured to connect the first input to the first output upon receiving a control signal from a controller; the battery junction box further comprises a second input connected to a second output, via a fuse and a main switch arranged in series. The switch circuit further comprises at least a first branch with a semiconductor switch between the first input and the first output, which semiconductor switch has a control line connected to the controller; and the switch circuit further comprises a second branch with a snubber circuit, which second branch is parallel with the first branch between the first input and the first output; and a flywheel diode with a first terminal connected to the first output, and a second terminal connected to the second output.

Claims

1. A battery junction box comprising: a first input connected to a first output via a switch circuit, which switch circuit is configured to connect the first input to the first output upon receiving a control signal from a controller; a second input connected to a second output, via a fuse and a main switch arranged in series; and a flywheel diode with a first terminal connected to the first output, and a second terminal connected to the second output, wherein the switch circuit comprises: at least a first branch with a semiconductor switch between the first input and the first output, which semiconductor switch has a control line connected to the controller; and a second branch with a snubber circuit, which second branch is parallel with the first branch between the first input and the first output.

2. A battery junction box according to claim 1, wherein the snubber circuit of the second branch comprises a capacitor in series with a diode, and wherein a resistor is arranged in parallel with the diode.

3. A battery junction box according to claim 1, wherein the semiconductor switch is a transistor.

4. A battery junction box according to claim 3, wherein the transistor is made of a wide bandgap material.

5. A battery junction box according to claim 4, wherein the wide bandgap material is one of SiC (silicon carbide) or GaN (gallium nitride).

6. A battery junction box according to claim 3, wherein the transistor is a MOSFET (metaloxide semiconductor field effect transistor).

7. A battery pack for supplying a load with electric power, wherein the battery pack comprises: at least one battery module; and a battery junction box comprising: a first input connected to a first output via a switch circuit, which switch circuit is configured to connect the first input to the first output upon receiving a control signal from a controller: a second input connected to a second output, via a fuse and a main switch arranged in series; and a flywheel diode with a first terminal connected to the first output, and a second terminal connected to the second output, wherein the switch circuit comprises: at least a first branch with a semiconductor switch between the first input and the first output, which semiconductor switch has a control line connected to the controller; and a second branch with a snubber circuit, which second branch is parallel with the first branch between the first input and the first output, wherein the first input and the second input of the battery junction box is connected to the at least one battery module, and wherein the first output and the second output of the battery junction box is configured to be connected to the load.

8. A vehicle comprising an electric motor, and a battery pack according to claim 7, wherein the load comprises the electric motor for propulsion of the vehicle, and the electric motor is connected to the first output and the second output of the battery junction box of the battery pack via an inverter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a schematic circuit drawing of a battery junction box according to an embodiment,

[0020] FIG. 2 is a schematic block drawing of the battery pack according to an embodiment, and

[0021] FIG. 3 is a schematic drawing of a vehicle with a battery pack according to an embodiment.

DETAILED DESCRIPTION

[0022] FIG. 1 shows a schematic circuit drawing of a battery junction box, generally designated 100, according to an embodiment. The battery junction box comprises a first input 101 connected to a first output 102 via a switch circuit 103. The switch circuit is configured to connect the first input to the first output upon receiving a control signal from a controller 104. The battery junction box further comprises a second input 109 connected to a second output 108, via a fuse (F1) and a main switch (SW0) arranged in series. The control signal may be an electric pulse or a voltage level that indicates the desired state of the switch circuit 103, for example 0 V for “OFF”-state and 5 V for “ON”-state.

[0023] The switch circuit 103 comprises at least a first branch 105 with a semiconductor switch S1-S3 between the first input and the first output, which semiconductor switch has a control line 106 connected to the controller.

[0024] The switch circuit further comprises a second branch 107 with a snubber circuit, which second branch is parallel with the first branch between the first input and the first output. A flywheel diode D1 with a first terminal connected to the first output, and a second terminal connected to the second output is also provided.

[0025] The snubber circuit of the second branch 107 comprises a capacitor C1 in series with a diode D2, and a resistor R0is arranged in paralell with the diode D2. Other configurations of snubber circuits comprising these elements are of course possible.

[0026] The snubber circuit and the flywheel diode provides safety measures against overvoltages due to switching of inductive loads, which may cause severe overvoltages over the switch without these safety measures. These severe overvoltages may easily destroy the semiconductor switch.

[0027] The semiconductor switches of FIG. 1 are preferably transistors of MOSFET (metaloxide semiconductor field effect transistor) type. Since these transistors provide low switch losses and low resistance in the on-state they are preferred. Furthermore, if increasead maximum electrical field and increased temperature for operation are of interest MOSFET devices of wide bandgap materials such as SiC (silicon carbide), or GaN (gallium nitride) may be preferred.

[0028] Another beneficial feature of the battery junction box according to the present invention is that if a MOSFET is used for switches (S1-S3), charging in the reverse direction is possible due to the body diode in the MOSFET. However, in order to interrupt charging the main switch SW0 may be used, since the controller 104 is not controlling the MOSFET in the reverse direction. This means that the switches S1-S3 may be used for disconnection due to short-circuits on the output side of the battery junction box, and interrupt of charging may be performed by means of the main switch SW0.

[0029] Other types of transistors may also be employed such as for example IGBT devices, the selection of transistor type is to a large degree dependent on the voltage of the DC link as well as supplied current. By arranging semiconductor switches in parallel as showed in FIG. 1 the current drive performance may be scaled. Furthemore, each semiconductor switch may be provided a dedicated drive circuit as well as a snubber circuit.

[0030] Additionally, in FIG. 1 the controller 104 is shared by all switches S1-S3. However, each switch S1 to S3 may be provided with a dedicated controller 104 in other embodiments.

[0031] Now with reference made to FIG. 2 a battery pack, generally designated 200, is schematically illustrated. The battery pack is provided for supplying a load (ZL) with electric power via a so called DC link 205. The battery pack comprises at least one battery module 201-204), The battery pack comprises a battery junction box 100 according to the present invention, wherein the first input and the second input of the battery junction box is connected to the at least one battery module, and wherein the first output and the second output of the battery junction box is configured to be connected to the load (ZL). The load may comprise an inverter and an electrical motor connected to the DC link.

[0032] FIG. 3 shows schematically a vehicle, generally designated 300, The vehicle comprises a battery pack according to the present invention with a battery junction box 100 that is connected to an inverter 301 for supplying electric power to an electrical motor of the vehicle, which electrical motor and inverter constitutes the load. The electric motor may be provided for propulsion of the vehicle, and the inverter 301 is connected to the first output and the second output of the battery junction box of the battery pack. Furthermore, the vehicle may comprise a plurality of battery packs according to the present invention connected to the DC link of the vehicle, and each of the battery packs is provided a battery junction box according to the present invention. This allows remote control of connection of each battery pack to the DC link, which may be useful if for example one battery module is failing.

[0033] The battery junction box and the battery pack of the invention provides a number of advantageous features, for example by employing semiconductor switches a battery management system (BMS) may be configured to disconnect the batterys upon detection of anomalies. This solution provides additional safety to the battery pack of the vehicle, such as for example disconnection of the battery module to the DC link by means of the battery junction box upon collision detection.