HIGH-VOLTAGE CHARGING CIRCUIT IN A VEHICLE, AND ON-BOARD VEHICLE ELECTRICAL SYSTEM

Abstract

A vehicle-based high-voltage charging circuit is provided with an AC voltage terminal, at least two galvanically isolating DC-DC converters designed as step-up converters and a rectifier via which the DC-DC converters are connected to the AC voltage terminal, and a changeover switch. The charging circuit has a first and a second DC voltage terminal selectably connected to the first DC-DC converter via the changeover switch. The charging circuit has a third DC voltage terminal connected to the second DC-DC converter, wherein the charging circuit also has a controller which is set up, in a first mode, to drive the DC-DC converters according to a first target output voltage which is at least 750 V and at most 1000 V, and, in a second mode, to drive the DC-DC converters according to a second target output voltage which is at most 480 V or at most 450 V.

Claims

1. A vehicle-based high-voltage charging circuit comprising: an AC voltage terminal; at least two galvanically isolating DC-DC converters; a rectifier via which the at least two galvanically isolating DC-DC converters are connected to the AC voltage terminal; a changeover switch; a first DC voltage terminal; a second DC voltage terminal, the first DC voltage terminal and the second DC voltage terminal selectively connected to a first of the at least two galvanically isolating DC-DC converters via the changeover switch; a third DC voltage terminal connected to the second of the at least two galvanically isolating DC-DC converters; and a controller having a first mode and a second mode; wherein during the first mode, the controller drives the at least two galvanically isolating DC-DC converters according to a first target output voltage which is at least 750 V and at most 1000 V, and during the second mode, the controller drives the at least two galvanically isolating DC-DC converters according to a second target output voltage which is at most 480 V or at most 450 V.

2. The vehicle-based charging circuit of claim 1, further comprising: a configuration circuit having a first configuration and a second configuration, the at least two galvanically isolating DC-DC converters being connected to the rectifier via the configuration circuit; wherein in the first configuration, the sides of the at least two galvanically isolating DC-DC converters facing the rectifier are connected in parallel with one another and are connected to the rectifier, and in the second configuration, the sides of the at least two galvanically isolating DC-DC converters facing the rectifier are connected in series with one another and are connected to the rectifier.

3. The vehicle-based charging circuit of claim 2, further comprising: a low-voltage converter, which is connected to the rectifier via one of the at least two galvanically isolating DC-DC converters; and a plurality of capacitances, each of which is connected to at least one of the at least two galvanically isolating DC-DC converters; wherein the controller is set up, when there is a change between the first configuration and the second configuration, to drive the low-voltage converter to charge capacitances.

4. The vehicle-based charging circuit of claim 2, further comprising: a charge transfer circuit; wherein the controller is set up to drive the charge transfer circuit between capacitors on both sides of the configuration circuit, or between capacitors on both sides of the at least two galvanically isolating DC-DC converters, or between capacitors of different DC-DC converters, to transfer charge.

5. The vehicle-based charging circuit of claim 2, wherein the controller is set up to activate a discharge circuit of capacitors which is connected to the at least two galvanically isolating DC-DC converters.

6. The vehicle-based charging circuit of claim 1, wherein the at least two galvanically isolating DC-DC converters are of the same design.

7. The vehicle-based charging circuit of claim 1, the first of the at least two galvanically isolating DC-DC converters connected to the changeover switch further comprising a bidirectional design, wherein the controller is set up to drive the first of the at least two galvanically isolating DC-DC converters in the second mode to generate a voltage on the side of drive the first of the at least two galvanically isolating DC-DC converters which is connected to the rectifier, and an auxiliary consumer terminal is connected to the side of the rectifier which is connected to the at least two galvanically isolating DC-DC converters.

8. The vehicle-based charging circuit of claim 1, wherein, in the second mode, the changeover switch is set up to connect the first DC voltage terminal and the second DC voltage terminal alternately to the first of the at least two galvanically isolating DC-DC converters repeatedly, periodically, or according to a predetermined variable duty cycle.

9. The vehicle-based charging circuit of claim 1, further comprising a changeover switch device which connects the side of the first of the at least two galvanically isolating DC-DC converters facing away from the rectifier in a switchable manner to the side of the second of the at least two galvanically isolating DC-DC converters facing away from the rectifier.

10. The vehicle-based charging circuit of claim 9, wherein the changeover switch device connects the side of the first of the at least two galvanically isolating DC-DC converters facing away from the rectifier to the first DC voltage terminal or the second DC voltage terminal in a selectable manner.

11. The vehicle-based charging circuit of claim 1, each of the at least two galvanically isolating DC-DC converters further comprising step-up converters.

12. A vehicle electrical system comprising: a vehicle-based charging circuit, further comprising: an AC voltage terminal; at least two galvanically isolating DC-DC converters; a rectifier via which the at least two galvanically isolating DC-DC converters are connected to the AC voltage terminal; a changeover switch; a first DC voltage terminal; a second DC voltage terminal, the first DC voltage terminal and the second DC voltage terminal selectively connected to a first of the at least two galvanically isolating DC-DC converters via the changeover switch; a third DC voltage terminal connected to the second of the at least two galvanically isolating DC-DC converters; a controller having a first mode and a second mode; wherein during the first mode, the controller drives the at least two galvanically isolating DC-DC converters according to a first target output voltage which is at least 750 V and at most 1000 V, and during the second mode, the controller drives the at least two galvanically isolating DC-DC converters according to a second target output voltage which is at most 480 V or at most 450 V; a rechargeable battery connected to the first DC voltage terminal; a consumer with a standard operating voltage of essentially 400 V or 420 V connected to the second DC voltage terminal; and an electrical system branch with a standard operating voltage of at least 750 V or at least 950 V connected to the third DC voltage terminal.

13. The vehicle electrical system of claim 12, the consumer connected to the second DC voltage terminal further comprising one selected from the group consisting of an electrical heating element of an exhaust-gas aftertreatment device, a cooling circuit of a power electronics system, and an interior heater or a window heater.

14. The vehicle electrical system of claim 13, the electrical system branch connected to the third DC voltage terminal further comprising a low-voltage voltage converter with downstream low-voltage components which are connected to the third DC voltage terminal via the low-voltage voltage converter.

15. The vehicle electrical system of claim 12, wherein the controller is set up to drive the changeover switch according to a target charging power for the rechargeable battery and according to a target power for the second consumer.

16. The vehicle electrical system of claim 12, wherein the controller is set up to set a weighting of the target charging power for the rechargeable battery and a weighting of the target power for the second consumer according to a priority specification and to set a duty cycle, according to which the changeover switch is switched over, depending on at least one of the weightings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention will be explained in detail below with reference to an exemplary embodiment in conjunction with the drawing, in which:

[0028] FIG. 1 is used to provide an explanation of the vehicle electrical system described here and the vehicle-based charging circuit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0029] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0030] FIG. 1 shows a charging circuit with connected components K1, K2, K3 which is able to be connected to an external AC voltage source via an AC voltage terminal. The AC voltage terminal may be designed as a standardized charging socket, for example. The charging circuit connected thereto has a rectifier whose AC voltage side is connected to the AC voltage terminal. The DC voltage side is connected to two DC-DC converters W1, W2 via a configuration circuit KS. The rectifier is connected to the two DC-DC converters W1, W2 via the configuration circuit KS.

[0031] The configuration circuit has two switches which, in the closed state, connect the two first sides of the DC-DC converters W1, W2, that is to say the sides facing the rectifier G, in parallel with one another. Furthermore, a diode circuit made up of two series diodes D is part of the configuration circuit, the diodes making it possible to connect the first sides of the DC-DC converters W1, W2 to one another in series when the switches are open. A first capacitor C1 is connected to the first side of the first DC-DC converter W1. A second capacitor C2 is connected to the first side of the second DC-DC converter W2. These capacitors are used to smooth the voltage on the first sides of the DC-DC converters W1, W2.

[0032] The DC-DC converters W1, W2 also have second sides which face away from the rectifier G. Further capacitors C1, C2 are connected to these second sides in order to smooth the voltage on the second sides of the DC-DC converters. These capacitors are also referred to as link circuit capacitors. The same also applies to the capacitors C1, C2. A changeover switch US is connected to the second side of the first DC-DC converter W1, via which changeover switch a first DC voltage terminal A1 or a second DC voltage terminal A2 is selectably connected. A third DC voltage terminal A3 is connected to the second side of the second DC-DC converter W2.

[0033] An auxiliary consumer terminal is connected directly to the DC voltage side of the rectifier.

[0034] A first component K1 is connected to the first DC voltage terminal A1. The first component K1 may be a rechargeable battery, for example a high-voltage rechargeable battery, such as a rechargeable battery with a rated voltage of approximately 800 volts or 850 volts. A second component K2 is connected to the second terminal A2. This is a 400-volt component that is designed for a maximum operating voltage of 450 volts (also only temporarily). This may be a heating element or else an electric air conditioning compressor. The component K1 generally has a higher rated voltage than the component K2, such as a rated voltage which is approximately twice as great, or even corresponds to only 180% or 190% of the rated voltage of the second component K2.

[0035] The changeover switch is designed with two poles and provides a selectable connection of both potentials of the first DC voltage terminal or both potentials of the second DC voltage terminal A2. The changeover switch may also have a third switching state or mode in which neither the first DC voltage terminal nor the second DC voltage terminal is connected to the first DC-DC converter W1.

[0036] A third component K3 is connected to the third DC voltage terminal. This is a low-voltage voltage converter, for example a converter on whose second side (facing away from the second DC-DC converter) a rated voltage of 12 volts (or else 24 volts or 48 volts) is provided. The low-voltage DC-DC converter has a first side which faces the second DC-DC converter W2 and which is provided for a rated voltage of at least 800 volts or 950 volts. It is possible to provide a low-voltage electrical system branch which has a low-voltage DC-DC converter of this type that is connected directly to the third DC voltage terminal A3. The component K3 may thus be a place holder for a low-voltage electrical system branch. While in this low-voltage electrical system branch there are components for which a low-voltage converter is provided in order to provide a suitable operating voltage according to the rated voltage of the components, the component K1 is also designed for (temporary) operating voltages above the relevant rated voltage. A rechargeable battery, such as an 800-volt rechargeable battery, is connected to the first DC voltage terminal. A component which is designed for an operating voltage of approximately 400 V and which is designed for a maximum operating voltage of approximately 420 V or 450 V, for example a heating element, is connected to the second DC voltage terminal. A rechargeable battery would possibly be damaged when operated with a voltage above the rated voltage, with the result that no rechargeable battery is connected to the second DC voltage terminal.

[0037] The first rectifier is designed to output voltage on the side of the changeover switch at the level of 800 V (as the upper voltage range) and also at the level of 450 V (as the lower voltage range).

[0038] An electric drive is connected to the auxiliary consumer terminal (via an isolating switch device), such as an inverter of an electric drive and possibly an electric machine connected thereto, 800-volt components such as heating elements or air conditioning compressors designed for this purpose and/or also a high-voltage rechargeable battery with a rated voltage of 800 volts. This may be the same rechargeable battery that is also connected (via isolating switches) to the first DC voltage terminal. In addition, a direct DC voltage charging terminal (possibly via the isolating switch device) is connected to the auxiliary consumer terminal (possibly via the isolating switch device). This is connected to the rechargeable battery (via its own isolating switch) in order to allow direct charging. Since the first DC voltage terminal is also connected to the rechargeable battery (also in a switchable manner, such as in a switchable manner via the changeover switch), the rechargeable battery is charged via the first DC-DC converter W1, the changeover switch U and the first DC voltage terminal (for example for pre-charging if the state of charge is below a limit), and may be equally charged via the direct DC voltage charging terminal, such as when the state of charge is not below the limit.

[0039] As mentioned, the changeover switch is provided between the first and second DC voltage terminal A1, A2 on the one hand and the second side of the first DC-DC converter W1. Alternatively or in combination with this, a changeover switch device may be provided at the point marked with a cross, that is to say in the parallel connection of the second sides of the DC-DC converters W1, W2.

[0040] The changeover switch may have two or three switching positions, namely a first state in which the first DC voltage terminal A1 is connected to the converter W1, a second state in which the second DC voltage terminal A1 is connected to the converter, and a third state in which neither of the two DC voltage terminals mentioned is connected to the first converter. The changeover switch device also has two states in which the first or the second DC voltage terminal is connected to the second side of the DC-DC converters, may have a further state in which neither of the two named DC voltage terminals is connected to the DC-DC converters W1, W2, and also has a fourth state in which the second side of the first DC-DC converter W1 is disconnected from the second side of the second DC-DC converter W2. Otherwise, the second sides of the two DC-DC converters W1, W2 are connected to one another in parallel (in two-pole fashion).

[0041] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.