Charger, in particular for a vehicle, and method for operating a charger

Abstract

A charger (200), in particular for a vehicle, has a conversion circuit (250) and a DC voltage output (220), which, for each phase (L1, L2, L3) of an input connection unit (210), comprises an AC voltage input (330, 430, 530) on the input side, and is connected on the output side to the DC voltage output (220). The charger (200) comprises a switching switch element (520), which is connected on the one hand to a third AC voltage input (530) of the conversion circuit (250) and is designed to connect the third AC voltage input (530) of the conversion circuit (250) either to a third phase (L3) of the input connection unit (210) associated therewith or to a buffer capacitor (540), wherein the charger (200) comprises the buffer capacitor (540) on the input side of the conversion circuit (250), which is connected on the one hand to a switchable contact of the switching switch element (520) and on the other hand to a ground potential (N).

Description

Technical Field

[0001] This invention relates to a charger, particularly for vehicles, and a method for operating the charger. Furthermore, this invention relates to a drive system having a charger, a vehicle having a drive system, a computer program, and a computer-readable medium. Background Technology

[0002] A preferred charger for vehicles with a multi-phase input connector includes a voltage converter that converts a single-phase or multi-phase input AC voltage into an output DC voltage for charging the vehicle's connected traction battery. This is achieved, for example, by means of a conversion circuit, such as a multi-phase PFC, intermediate circuit capacitors, and an electrically isolated DC voltage converter. Alternatively, for this purpose, a converter with the same structure is used for each phase, each converter generating an output DC voltage from a single-phase input AC voltage, wherein the converters are connected in parallel on the output side.

[0003] Ideally, the energy flow on the DC voltage side should be free of power ripple. This is achieved by implementing a two-stage topology for the power electronics with a large intermediate circuit capacitor between the two stages. The first stage operates as a rectifier / inverter stage (depending on the power direction) and provides a constant voltage at its output. This module is also known as a PFC (power factor correction) stage. The second stage then converts this voltage to the desired voltage (e.g., the charging voltage of a battery) and provides additional electrical isolation. If the power electronics operate on a three-phase grid, no power buffer is needed because a constant power can be drawn from the three-phase grid. However, it is possible that the same power electronics must also operate on a single-phase or two-phase grid. In this case, the intermediate circuit capacitor, typically implemented as an electrolyte-capacitor between the two stages, acts as a power buffer. Due to the variability of the grid voltage and the operational limitations of the power electronics, the voltage fluctuation of the intermediate circuit capacitor used for energy storage is limited to approximately ±5%, necessitating a large capacity. This results in significant disadvantages in terms of cost and structural space. Because power grids or supply grids vary around the world (e.g., single-phase grids are commonly used in North American homes, while three-phase grids are common in Europe), chargers are typically constructed "modularly by phase." This means that the charger can connect to and operate with single-phase, two-phase, or three-phase power grids independently of the grid configuration. This results in the need for intermediate circuit capacitors to buffer power, depending on the number of phases and the power to be transmitted in each phase, as each individual phase draws pulsed power from the grid. If, for example, only one or two grid phases are provided, the individual grid phases can be connected in parallel to the input phase via switching units or connection modules consisting of, for example, relays. This necessary modularity leads to redundant power electronics topologies in terms of functionality and discrete component or component design (e.g., intermediate circuit capacitors), which impacts not only the required structural space but also the number of resources or components required. There is a need to reduce the number of required components while still maintaining the required functionality. Summary of the Invention

[0004] A charger, particularly for vehicles, is provided, comprising a single-phase to at least three-phase input connector unit, a conversion circuit, and a DC voltage output terminal. Furthermore, the conversion circuit includes an AC voltage input terminal on the input side for each phase of the input connector unit. The conversion circuit is connected to the DC voltage output terminal on the output side. The charger includes a switching element that is connected to a third AC voltage input terminal of the conversion circuit on one hand, and is configured to connect the third AC voltage input terminal of the conversion circuit to the associated third phase of the input connector unit or to a buffer capacitor. The charger includes a buffer capacitor on the input side of the conversion circuit that is connected to a switchable contact of the switching element on one hand and to ground potential on the other.

[0005] A charger with at least three phases is provided. The charger includes a conversion circuit that includes an AC voltage input terminal on the input side for each phase and a preferably common DC voltage output terminal on the output side. Furthermore, the charger includes a switching element that allows either connecting the third AC voltage input terminal of the conversion circuit to the third phase of the input connector unit or connecting the third AC voltage input terminal of the conversion circuit to a buffer capacitor, wherein the buffer capacitor is connected between a ground wire, ground potential, neutral wire connector, or housing potential and a switchable contact of the switching element.

[0006] Advantageously, a charger is provided that replaces the intermediate circuit capacitors designed for all phases or the snubber capacitors on the AC voltage side of each phase. This charger includes a switching element combined with the snubber capacitors distributed on the input side of the switching circuit. Advantageously, this topology achieves uniform power delivery at the DC voltage output of the charger on the one hand, and on the other hand, allows for a reduction in the capacity of the snubber capacitors relative to the typically required capacity, or an increase in the voltage ripple on the snubber capacitors on the other hand. Preferably, this saves cost and structural space.

[0007] Within the framework of this specification, the terms “connection” or “link” are used synonymously with “conductive connection”.

[0008] In one design of the present invention, when the charger is powered by a three-phase power grid during operation, a switching element connects the third AC voltage input terminal of the conversion circuit to the corresponding third phase of the input connector unit.

[0009] To operate the charger on a three-phase or multi-phase power grid, a switching element connects the third AC voltage input terminal of the conversion circuit to the corresponding third phase of the input connector unit. Thus, the conversion circuit converts the input AC voltage applied to the three phases into an output DC voltage. Preferably, pulsed power is directed from the input terminal to the output terminal for each phase. Because the input AC voltage and input AC current are phase-shifted by 120° in a three-phase power grid, a constant, non-pulsed output power is generated at the DC voltage output terminal. Advantageously, this provides the charger with a constant output power operation.

[0010] In other design embodiments of the present invention, when the charger is powered by a single-phase or two-phase power grid during operation, the switching element connects the third AC voltage input terminal of the conversion circuit to the buffer capacitor.

[0011] To operate the charger on a single-phase or two-phase power grid, a switching element connects the third AC voltage input terminal of the switching circuit to a buffer capacitor. Preferably, the power electronics controlling the switching circuit connected to the third AC voltage input terminal compensate for any power ripples by means of the connected buffer capacitor. Advantageously, a charger with a switching element is provided that allows the charger to operate with uniform output power on a single-phase or two-phase power grid.

[0012] In one design of the present invention, the conversion circuit is configured to compensate for power pulsations generated at the preferred DC voltage output terminal when the charger is powered by a single-phase or two-phase power grid during operation.

[0013] To operate the charger on a single-phase or two-phase power grid, a switching element connects the third AC voltage input terminal of the switching circuit to a buffer capacitor. In the case of a single-phase or two-phase power grid and during corresponding operation of the switching circuit, pulsed power is generated at the DC voltage intermediate circuit or DC voltage output terminal depending on the circuit topology. To avoid this pulsed power, the power electronics connected to the third AC voltage input terminal of the switching circuit are operated such that they transfer energy towards the buffer capacitor with a 180° phase shift relative to the pulsed power of the first and second phases, and vice versa, thereby providing uniform, non-pulsated power at the DC voltage intermediate circuit or DC voltage output terminal of the charger, or compensating for any power ripples that would otherwise occur. For this purpose, it is preferable that at least the power electronics connected to the third AC voltage input terminal be designed bidirectionally. Advantageously, this provides operation of the charger with a switching element that offers uniform output power.

[0014] In other design embodiments of the present invention, the conversion circuit includes a multiphase PFC stage connected to the AC voltage input terminal and a DC voltage converter connected to the PFC stage for converting a single-phase DC voltage into an output DC voltage, wherein the DC voltage converter is connected to the DC voltage output terminal on the output side.

[0015] In the case of a single-phase or two-phase power grid, and when one or two phases of the power grid are operating in conjunction with a PFC stage, pulsed power is generated at the output side of the PFC stage. To further avoid pulsed power at the preferred DC voltage output, the third phase of the PFC stage is operated such that it is 180° out of phase with the pulsed power of the first and second phases of the PFC stage, transferring energy from the output side of the PFC stage towards the buffer capacitor and vice versa. This re-provides uniform, non-pulsated power at the output side of the PFC stage and thus at the DC voltage output of the charger, or compensates for power ripples that would otherwise occur at the DC voltage output. Accordingly, at least the third phase of the PFC stage is operated bidirectionally for this purpose. Advantageously, a topology for the switching circuit of a charger with switching elements is provided for operation with uniform output power.

[0016] Advantageously, it provides a topology for the conversion circuitry used in chargers.

[0017] In other designs of the invention, the conversion circuit includes at least one converter for each phase of the input connector unit for converting a single-phase AC voltage to a DC voltage, wherein the converter is connected in parallel with the DC voltage output terminal on the output side, and each converter is connected to the AC voltage input terminal of the conversion circuit on the input side.

[0018] In the case of a single-phase or two-phase power grid and when one or two converters in the conversion circuit are operating, pulsed output power is generated at the DC voltage output terminals of the first and second converters connected in parallel. To avoid this pulsed output power at the DC voltage output terminals, a third converter is operated. This third converter transfers energy from the DC voltage output terminals toward the buffer capacitor with a 180° phase shift from the pulsed output power of the first and second converters, and vice versa. This re-provides a uniform, non-pulsated output power at the DC voltage output terminals of the charger, or compensates for any power ripples that would otherwise occur at the DC voltage output terminals. For this purpose, it is preferable that at least the third converter is designed as a bidirectional third converter. Advantageously, a topology for the conversion circuit of a charger with switching elements is provided for operation with uniform output power.

[0019] Advantageously, it provides a topology for the conversion circuitry used in chargers.

[0020] Preferably, when the charger operates on a single-phase or two-phase power grid, the first and / or second phases of the multi-phase PFC stage transfer pulsed power from the input to the DC-DC voltage converter, or the first and / or second converters transfer pulsed power from the input to the DC voltage output of the charger for each phase. These pulsed powers are superimposed but do not cancel each other out. Therefore, it is preferable to actively compensate for power ripples at the input of the DC-DC voltage converter, or to actively compensate for power ripples at the DC voltage output, by means of the third phase of the multi-phase PFC stage, which transfers and stores excess power in a buffer capacitor. The third phase of the PFC stage or the third converter thus operates in reverse and draws from the buffer capacitor to provide the difference when power is insufficient. Advantageously, since only two-thirds of the maximum power is buffered, the overall intermediate circuit capacitance required for the phase-modular charger is reduced. Furthermore, in common three-phase operation, the intermediate circuit capacitance is unloaded, thus reducing the operating load on the intermediate circuit capacitance. This increases the expected lifespan of the intermediate circuit capacitor or makes it easier and cheaper to construct the intermediate circuit capacitor while maintaining the same predetermined lifespan. Furthermore, since the PFC module is designed to operate under drastically fluctuating voltages or AC voltages, it is preferable to significantly increase the voltage ripple on the capacitor. This higher voltage ripple allows for a reduction in the capacitance of the intermediate circuit capacitor, resulting in additional advantages in terms of cost and structural space.

[0021] Furthermore, the present invention relates to a drive system for a vehicle having an inverter, a motor, and / or a traction battery, wherein the drive system includes at least one described charger.

[0022] The vehicle's drive system converts fossil fuel energy or electrical energy from an energy source into mechanical energy, which propels the vehicle. In an electric drive system, electrical energy from the energy source is converted into alternating current (AC) voltage, for example, by means of an inverter, which is used to operate the motor. Advantageously, the energy source can be recharged using energy from the power grid, as described in the charger.

[0023] Furthermore, the present invention relates to a vehicle having the drive system described above. Advantageously, a vehicle having the described charger is provided.

[0024] Furthermore, the present invention relates to a method for operating the described charger, the method comprising the steps of: operating a switching element when the charger is powered by a three-phase power grid or a single-phase or two-phase power grid, wherein, particularly when the charger is powered by a three-phase power grid, the switching element connects the third AC voltage input terminal of the switching circuit to the associated third phase of the input connector unit; and particularly when the charger is powered by a single-phase or two-phase power grid, the switching element connects the AC voltage input terminal of the switching circuit to a buffer capacitor.

[0025] A method for operating a charger is provided. A switching element is operated according to the power grid configuration. When the power grid configuration enables three-phase power supply to the charger, the switching element is operated such that the third AC voltage input terminal of the switching circuit is connected to the corresponding third phase of the input connector unit. When the power grid configuration enables only single-phase or two-phase power supply to the charger, the switching element is operated such that the third AC voltage input terminal of the switching circuit is connected to a buffer capacitor. Advantageously, a control strategy is provided for the operation of the charger, which enables uniform, non-pulsating output power at the DC voltage output terminal of the charger.

[0026] In one embodiment of the present invention, the method includes the additional step of operating a conversion circuit when the charger is powered by a single-phase or two-phase power grid, thereby compensating for power ripples generated at the preferred DC voltage output terminal.

[0027] In situations where the power grid is configured to supply only single-phase or two-phase power to the charger, the switching element is operated such that the third AC voltage input of the switching circuit is connected to a buffer capacitor. Furthermore, to avoid pulsed power, the switching circuit is operated such that it transmits energy towards the buffer capacitor with a 180° phase shift relative to the pulsed power transmitted through the first and second phases, and vice versa, thereby providing uniform, non-pulsated power at the charger's DC voltage output, or compensating for any power ripples that might otherwise occur. Advantageously, a method for operating a charger with a switching element that provides uniform output power is provided.

[0028] Furthermore, the present invention relates to a computer program comprising instructions that cause a charger to perform the method steps.

[0029] Furthermore, the present invention relates to a computer-readable storage medium having the described computer program stored thereon.

[0030] It goes without saying that the features, performance, and advantages of the charger are correspondingly applicable to or can be applied to the method, drive system, and vehicle, and vice versa. Attached Figure Description

[0031] Further features and advantages of embodiments of the present invention will become apparent from the following description with reference to the accompanying drawings. Wherein: Figure 1 A schematic diagram of a charger from the prior art is shown. Figure 2 A schematic diagram of a charger with a switching element is shown. Figure 3 Another schematic diagram of a charger with a switching element is shown. Figure 4 A schematic illustration of a vehicle with a drive system including a charger is shown. Figure 5 A schematic illustration of a method for operating a charger is shown. Detailed Implementation

[0032] Figure 1 A preferred charger 200 for a vehicle from the prior art is shown. The charger 200 includes a single-phase to at least three-phase input connector unit 210. This means that the input connector unit 210 can be connected to a different AC voltage power grid 230 or a power grid 230 with a different grid configuration, for example, to a power grid 230 that provides single-phase, two-phase, or three-phase AC voltage as an energy source for charging, for example, the vehicle's traction battery 240 using the charger 200. Preferably, the input connector unit 210 includes an additional neutral connector N for connecting the neutral wire of the power grid 230 to be connected. Furthermore, the charger 200 includes a conversion circuit 250 and a DC voltage output terminal 220, to which the vehicle's traction battery 240 to be charged can be connected, for example, to the DC voltage output terminal. For each phase L1, L2, L3 of the input connector unit 210, the conversion circuit 250 includes at least one AC voltage input terminal 330, 430, 530, which are preferably connected to one of phases L1, L2, L3 respectively, and are preferably switchably connected to one of phases L1, L2, L3 respectively via the switching unit 211.

[0033] according to Figure 2 Charger 200 and according to Figure 1The difference from existing technology lies in that the charger 200 includes a switching element 520, which is connected to the third AC voltage input terminal 530 of the conversion circuit 250 on one hand and configured to connect the third AC voltage input terminal 530 of the conversion circuit 250 to the associated third phase L3 of the input connector unit 210 (switch position 1) or to connect the third AC voltage input terminal 530 of the conversion circuit to a buffer capacitor 540 (switch position 2). The charger 200 includes a buffer capacitor 540 on the input side of the conversion circuit 250, which is connected to the switchable contacts of the switching element 520 on one hand and to the ground potential N on the other. Depending on the design and, if necessary, the ground potential N can be connected to, for example, the housing of the charger 200, the ground potential of the charger or vehicle, or the neutral wire connector of the input connector unit 210. Furthermore, according to… Figure 2 The conversion circuit 250 includes at least a three-phase PFC stage 252, the inputs of which are connected to the AC voltage inputs 330, 430, and 530 of the conversion circuit 250. The PFC stage 252 is configured to act as a rectifier / inverter stage (depending on the power direction) to convert the multiphase AC voltage on the input side and to provide a preferably constant DC voltage at its output. The conversion circuit 250 further includes a DC voltage converter 254 that converts the DC voltage provided by the PFC stage 252 into an output DC voltage. On the output side, the DC voltage converter 254 is connected to the DC voltage connector 220 of the charger 220. Figure 2 The reference numerals in the accompanying drawings, which are not explained in more detail, correspond in terms of content to the use of Figure 1 The accompanying figure labels are explained.

[0034] according to Figure 3 Charger 200 and according to Figure 1 and Figure 2 The charger differs in that the conversion circuit 250 includes at least one converter 300, 400, or 500 for each phase L1, L2, L3 of the input connector unit 210. These converters are preferably connected to one of phases L1, L2, and L3, respectively, and are preferably switchably connected to one of phases L1, L2, and L3 via a switching unit 211. Preferably, converters 300, 400, and 500 include PFC stages 315, 415, and 515 on the input side. These PFC stages are preferably connected to DC voltage converters 310, 410, and 510 via intermediate circuitry. Preferably, DC voltage converters 310, 410, and 510 include electrical isolation. Preferably, converters 300, 400, and 500 convert the single-phase AC voltage applied to the input side of the converter into a DC voltage at the output side of the converter. The converter outputs of converters 300, 400, and 500 are connected in parallel with the DC voltage output 220 of the charger. Figure 3 The reference numerals in the accompanying drawings, which are not explained in more detail, correspond in terms of content to the use of Figure 1 and Figure 2 The accompanying figure labels are explained.

[0035] Figure 4 A vehicle 700, schematically illustrated, is shown, having four wheels and a drive system 600 with a charger 200. The vehicle 700 is shown here only exemplarily with four wheels, but the invention can also be used in any vehicle with any number of wheels, whether on land, water, or in the air. The exemplarily illustrated drive system 600 includes at least a charger 200 with a switching element 520. Furthermore, the drive system 600 includes, in particular, a traction battery 240 or an electrical energy source, especially a high-voltage battery, which uses electrical energy to power an electric drive unit. The energy from the DC voltage source 240 is converted, for example, into a three-phase AC voltage by means of an inverter 610 for operating a motor 620, which serves as the drive unit of the vehicle 200.

[0036] Figure 5 A schematic flowchart illustrating a method 100 for operating charger 200 is shown. Method 100 begins at step 105. In step 110, a switching element 520 is operated depending on whether charger 200 is powered by a three-phase power grid 230 or a single-phase or two-phase power grid 230. Therefore, preferably when charger 200 is powered by a three-phase power grid 230, the switching element 520 connects the third AC voltage input terminal 530 of the conversion circuit 250 to the associated third phase L3 of the input connector unit 210. Preferably, when charger 200 is powered by a single-phase or two-phase power grid 230, the switching element 520 connects the third AC voltage input terminal 530 of the conversion circuit to a buffer capacitor 540. In step 120, the conversion circuit is operated when charger 200 is powered by a single-phase or two-phase power grid 230, such that power ripples generated at the preferred DC voltage output terminal 220 are preferably at least partially compensated. The method 100 ends at step 125.

Claims

1. A charger (200) specifically for use in vehicles. It has a single-phase to at least three-phase input connector unit (210), a conversion circuit (250), and a DC voltage output terminal (220). For each phase (L1, L2, L3) of the input connector unit (210), the conversion circuit (250) includes an AC voltage input terminal (330, 430, 530) on the input side. The conversion circuit (250) is connected to the DC voltage output terminal (220) on the output side. Its features are, The charger (200) includes a switching element (520) which is connected to the third AC voltage input terminal (530) of the conversion circuit (250) and configured to connect the third AC voltage input terminal (530) of the conversion circuit (250) to the associated third phase (L3) of the input connector unit (210) or to connect the third AC voltage input terminal (530) of the conversion circuit (250) to a buffer capacitor (540). The charger (200) includes the buffer capacitor (540) on the input side of the conversion circuit (250), which is connected to the switchable contact of the switching element (520) and to ground potential (N).

2. The charger (200) according to claim 1. in, When the charger (200) is operating and is powered by a three-phase power grid (230), the switching element (520) connects the third AC voltage input terminal (530) of the switching circuit (250) to the associated third phase of the input connector unit (L3).

3. The charger (200) according to any one of the preceding claims. in, When the charger (200) is powered by a single-phase or two-phase power grid (230) during operation, the switching element (520) connects the third AC voltage input terminal (530) of the conversion circuit (250) to the buffer capacitor (540).

4. The charger (200) according to claim 3. in, The conversion circuit (250) is configured to compensate for power ripples (220) that occur when the charger (200) is powered by a single-phase or two-phase power grid (230) during operation.

5. The charger according to any one of claims 1 to 4, in, The conversion circuit (250) includes a multiphase PFC stage (252) connected to the AC voltage input terminals (330, 430, 530) and a DC voltage converter (254) connected to the PFC stage (252). The DC voltage converter is used to convert the single-phase DC voltage at the output terminal of the PFC stage (252) into an output DC voltage. The DC voltage converter (254) is connected to the DC voltage output terminal (220) on the output side.

6. The charger according to any one of claims 1 to 4, in, The conversion circuit (250) includes at least one converter (300, 400, 500) for each phase (L1, L2, L3) of the input connector unit (210) for converting a single-phase AC voltage to a DC voltage, wherein the converter (300, 400, 500) is connected in parallel with the DC voltage output terminal (220) on the output side, and wherein each of the converters (300, 400, 500) is connected to the AC voltage input terminal (330, 430, 530) of the conversion circuit (250) on the input side.

7. A drive system (600) for a vehicle (700) comprising an inverter (610), a motor (620), and / or a traction battery (240), wherein, The drive system includes at least one charger (200) according to any one of claims 1 to 6.

8. A vehicle (700) having a drive system (600) according to claim 7.

9. A method (100) for operating a charger (200) according to any one of claims 1 to 6. It has the following steps: When the charger (200) is powered by a three-phase power grid (230) or a single-phase or two-phase power grid (230), the switching element (520) is operated (110), wherein, When the charger (200) is operating and is powered by a three-phase power grid (230), the switching element (520) specifically connects the third AC voltage input terminal (530) of the conversion circuit (250) to the associated third phase (L3) of the input connector unit (210), wherein when the charger (200) is operating and is powered by a single-phase or two-phase power grid (230), the switching element (520) specifically connects the AC voltage input terminal (530) of the conversion circuit (250) to the buffer capacitor (540).

10. The method (100) for operating a charger (200) according to claim 9. It has additional steps: When the charger (200) is powered by a single-phase or two-phase power grid (230), the conversion circuit (250) is operated (120) to compensate for the power pulsation.

11. A computer program comprising instructions that cause a charger (200) according to any one of claims 1 to 6 to perform the steps of the method according to claims 9 to 10.

12. A computer-readable medium comprising instructions that, when implemented by a charger (200), cause the charger to perform the steps of the method (100) according to claims 9 to 10.

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