ENERGY SYSTEM FOR AN ELECTRIC VEHICLE

Abstract

A system for the electrical power supply of a vehicle and a method for the electrical power supply of a vehicle are described.

Claims

1. A system for the electrical power supply of an electric vehicle, comprising at least one HV onboard network and at least one LV onboard network, wherein the system comprises a HV battery, which is connected across circuit breaker elements to the at least one HV onboard network, and wherein the HV battery comprises a first sub-branch and a second sub-branch, which are switched in series, and wherein a first input of a multistage cascading DC/DC converter is connected to the first sub-branch, and a second input of the multistage cascading DC/DC converter is connected to the second sub-branch, and an output of the multistage cascading DC/DC converter is connected to the at least one LV onboard network, wherein the multistage cascading DC/DC converter comprises a pole selection module, a non-galvanically isolated step-down and/or step-up converter stage, and a galvanically isolated main converter stage.

2. The system according to claim 1, in which the galvanically non-isolated step-down and/or step-up converter stage is a step-down converter.

3. The system according to claim 1, in which the galvanically non-isolated step-down and/or step-up converter stage is a step-up converter.

4. The system according to claim 1, in which the galvanically non-isolated step-down and/or step-up converter stage is step-down/step-up converter.

5. The system according to claim 1, in which the DC/DC converter comprises an active or passive rectifier on the secondary side of the transformer.

6. The system according to claim 1, in which the DC/DC converter comprises an active full-bridge on the secondary side of the transformer.

7. The system according to claim 1, in which the DC/DC converter comprises a current doubler on the secondary side of the transformer.

8. The system according to claim 1, in which the main converter stage comprises a transformer, the secondary winding of which has a center tap, which is utilized by the DC/DC converter at the secondary side of the transformer.

9. The system according to claim 1, in which the pole selection module is adapted to provide at its output optionally the voltage tapped from the poles of the HV battery, the voltage tapped from the poles of the first sub-branch, or the voltage tapped from the poles of the second sub-branch.

10. A method for the electrical power supply of an electric vehicle, comprising at least one HV onboard network and at least one LV onboard network, and a HV battery, which comprises a first sub-branch and a second sub-branch, which are switched in series, wherein the at least one HV onboard network is connected to the poles of the HV battery and supplied with electrical energy, and the at least one LV onboard network is connected to the output of a multistage cascading DC/DC converter, which comprises a pole selection module, a galvanically non-isolated step-down and/or step-up converter stage and a galvanically isolated main converter stage, and in which a first input is connected to the first sub-branch, and a second input is connected to the second sub-branch, and supplied with electrical energy.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0029] Embodiments of the invention are represented schematically with the aid of the drawing and shall be described schematically and at length with reference to the drawing.

[0030] FIG. 1 shows in schematic representation a cutout view of one embodiment of a system to carry out one embodiment of a method.

DETAILED DESCRIPTION

[0031] FIG. 1 shows schematically a cutout view of one embodiment of the energy system 100. Not shown are the connection of the HV battery 10 to the HV onboard network, the HV onboard network, or the LV onboard network of the vehicle.

[0032] The HV battery 10 comprises a first sub-branch 11 and a second sub-branch 12. To the first sub-branch 11 is connected a first input of a pole selection module 21 of a cascading multistage DC/DC converter 20, to the second sub-branch 12 is connected a second input of the pole selection module 21 of the DC/DC converter 20. Hence, a center tap of the HV battery 10 is realized. The pole selection module 21 allows the selection between three different voltage taps on the HV battery 10: HV+ versus HV−, HV.sub.mean versus HV−; HV+ versus HV.sub.mean. At the output of the pole selection module 21 there is arranged a galvanically non-isolated step-down converter (buck stage) 22. This serves for assuring a stable intermediate circuit voltage. To the intermediate circuit is connected a galvanically isolated main converter 23, which is operated at the stabilized intermediate circuit voltage. The main converter 23 comprises a transformer 24 having a center tap. The center tap is utilized at the secondary side of the transformer 24 (center tap technology). The output of the DC/DC converter 20 is connected to the LV onboard network of the vehicle.

[0033] In normal operation at full system voltage (e.g., 800 V), Q2 is permanently conductive, Q3-Q6 are non-conductive. Q1 forms together with L1 and Q7 a step-down converter (buck topology) in order to regulate the voltage at the intermediate circuit (C_ZK) to a stable level (e.g., 400 V). The main converter 23 works with a stable input voltage in resonance mode.

[0034] In event of a fault in the first sub-branch 11, this is isolated from the rest of the system by a fuse. Then, only the second sub-branch 12 is still available with half the system voltage. In this case, Q1 is opened, while Q2, Q5 and Q6 remain closed. Q3 and Q4 are closed, Q7 remains opened. In this way, half the system voltage is applied hard to the intermediate circuit. The main converter continues to work unchanged.

[0035] In event of a fault in the second sub-branch 12, this is isolated from the DC/DC converter 20 by opening of Q2, Q3 and Q4. Q1, Q5 and Q6 now take the voltage of the first sub-branch 11 to the intermediate circuit.

[0036] German patent application no. 10 2021 128140.7, filed Oct. 28, 2021, to which this application claims priority, is hereby incorporated herein by reference, in its entirety.

[0037] Aspects of the various embodiments described above can be combined to provide further embodiments. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.