Charging device

Abstract

The invention relates to a charging device (1) comprising at least one grid connection (2) for an alternating voltage (3), a power factor correction circuit (5) for each grid connection (2), n DC / DC converters (6) connected in parallel, wherein n > 2, and a control device (7), wherein the control device (7) is configured to operate the DC / DC converters (6), wherein the control device (7) is further configured to distribute power non-uniformly to the DC / DC converters (6) depending on the power requirements and parameters of the switching elements (S) of the DC / DC converters (6).

Description

Technical Field

[0001] This invention relates to a charging device. Background Technology

[0002] Such charging equipment could be, for example, on-board chargers for electric vehicles or plug-in hybrid vehicles. Known on-board chargers with transformers for current isolation require specific development for different power categories. This is considered a reason for the current limited diversity in power categories. Charging powers of 3.6kW, 7.2kW, 11kW, and occasionally 22kW are common for higher-priced vehicles. Considering the existing charging infrastructure, where most charging stations offer Type 2 and CCS Combo 2 plugs, DC charging with power >50kW is possible. Type 2 / CCS Combo charging stations are connected via sufficient conductor cross-section, allowing for easy branching to 22kW and 43kW on the AC side as well. Currently, AC on-board charging (OBC) equipment for vehicles is a limiting factor; for higher charging power, these devices are both expensive and complex.

[0003] DE 10 2017 208 954 A1 discloses a charging device installed in a vehicle, wherein the charging device has at least two power modules connected in parallel for converting input power supplied from an external source into charging power for charging a high-voltage battery. Furthermore, the charging device has at least two slave control units that output information regarding whether each of the at least two power modules has entered a constant voltage charging mode based on the charging power output from the at least two power modules. A master unit is also provided, configured to determine whether the at least two power modules have entered the constant voltage charging mode, wherein when the at least two power modules have entered the constant voltage charging mode, one of the at least two power modules is operated.

[0004] DE 10 2018 213 611 A1 discloses a gate driver module for turning on and off power transistors. The gate driver module has a configuration unit. In this document, for example, a reference and / or unique identifier is assigned to existing gate driver modules during initial communication. This reference and / or unique identifier is necessary for subsequent regulation operation via the interface, so that both the central regulation device and each gate driver module are known corresponding to the converter topology. This enables the converter to be set up quickly, flexibly, and cost-effectively. Summary of the Invention

[0005] This invention is based on the technical problem of creating improved charging devices.

[0006] This technical problem is solved by the charging device according to the invention. Other advantageous designs of the invention are derived in different embodiments.

[0007] To this end, the charging equipment includes at least one grid connection for AC voltage, a power factor correction circuit for each grid connection, n parallel DC / DC converters, where n ≥ 2, and a control device. The control device is configured to operate the DC / DC converters, and is further configured to non-uniformly distribute power to the DC / DC converters according to the power requirements and parameters of their switching elements. This allows for the very simple provision of different power classes, enabling the DC / DC converters to operate optimally according to the required power. The load or health status of the switching elements can also be determined by considering their parameters. Correspondingly, the control device can redistribute power so that DC / DC converters with "healthier" (less aged) switching elements bear a greater load, thereby improving the overall lifespan of the charging equipment. These parameters may, in particular, be the temperature and output current of the switching elements. Preferably, each DC / DC converter is designed for 3.6 kW. Thus, depending on the vehicle size and desired charging power, the charging equipment can be modularly combined from a corresponding number of identical DC / DC converters. This reduces manufacturing costs because the same DC / DC converters can be used in different vehicles. More preferably, the number of DC / DC converters, n, is 6 or 12, thereby providing a total power of 22kW or 43kW. Furthermore, the number of secondary terminals is preferably 3. The DC / DC converter here preferably operates as a boost converter. Another advantage of the charging device is that the output voltage ripple can be reduced by phase-shifting the DC / DC converter.

[0008] In one embodiment, the charging device is disposed in a motor vehicle, wherein the DC / DC converter is connected to the traction battery of the motor vehicle. Therefore, the charging device is an on-board charger.

[0009] In an alternative embodiment, the charging device is arranged in a charging facility or charging station, wherein the DC / DC converter is capable of being connected to the DC voltage connection terminal of the motor vehicle.

[0010] In another embodiment, the DC / DC converter is configured as a multi-level DC / DC converter, wherein the DC / DC converter preferably has three levels. This allows commercially available switching elements to be used for ultra-high output voltages of 800V and above. This increases the switching frequency, which in turn reduces current and voltage ripple.

[0011] In another embodiment, the DC / DC converter is configured as a bidirectional DC / DC converter.

[0012] In another embodiment, an active fault current compensation circuit is arranged at the power grid connection terminal.

[0013] In another embodiment, gate driver modules are assigned to the switching elements of the DC / DC converter, wherein the gate driver modules are configured to detect parameters of the switching elements, and the gate driver modules of the DC / DC converter are interconnected in a daisy-chain manner, including the control device. This greatly reduces wiring costs, where a slightly longer operating time is not a significant issue.

[0014] In another embodiment, each gate driver module has a configuration unit that stores or can detect the configuration of its upper-level circuitry. The gate driver module also has a logic unit configured to receive a PWM signal from the control device and store the PWM signal for at least one clock cycle. This allows the switching elements to be turned off in the correct sequence in case of a fault—for example, when communication with the control device is interrupted—without causing a negative impact on other switching elements.

[0015] In another embodiment, each gate driver module has at least one fault unit, wherein the fault unit is configured to forward at least one internal fault of the gate driver module to at least one adjacent gate driver module and the control device, and to receive fault messages from at least one adjacent gate driver module and the control device. The logic unit is further configured to generate a PWM signal based on the fault message from the fault unit, a stored or detected circuit configuration, and a stored PWM signal to turn off connected switching elements. This also allows the switching elements to be turned off in the correct sequence in the event of an internal fault, thus preventing any adverse effect on other switching elements.

[0016] In another embodiment, the gate driver module has at least two switchable voltage sources and at least two output terminals, with on and off resistors connected to the output terminals. The gate driver module also has at least one third switchable output terminal, with at least one current source connected in parallel with the on and off resistors to the output terminal. This accelerates on and off operations, where the quiescent state is maintained by the voltage sources. Attached Figure Description

[0017] The invention will now be explained in more detail based on preferred embodiments.

[0018] Figure 1 A schematic block diagram of the charging device is shown.

[0019] Figure 2A schematic diagram of the input terminals of a charging device with three mains connection points is shown.

[0020] Figure 3 A schematic circuit layout for a three-stage multilevel DC / DC converter is shown.

[0021] Figure 4 A schematic circuit arrangement of the gate driver module is shown, and

[0022] Figure 5 A schematic diagram of a daisy-chain connection of the gate driver module of a DC / DC converter with control devices is shown. Detailed Implementation

[0023] Figure 1 The diagram schematically illustrates a charging device 1, which has a mains connection 2 for AC voltage 3. The charging device 1 also includes an active fault current compensation circuit 4 and a power factor correction circuit 5, also known as a PFC circuit. The power factor correction circuit 5 can be configured as a standard PFC circuit or a Vienna PFC circuit. The charging device 1 also has a number of DC / DC converters 6 connected in parallel. Preferably, six or twelve DC / DC converters 6 are connected in parallel. However, more or fewer DC / DC converters 6 can also be connected. Two capacitors C are arranged on the output side. dcThe center taps of these capacitors form a neutral point. The output terminal AK can then be connected to the high-voltage battery of an electric vehicle or plug-in hybrid vehicle, or to a plug that can be connected to the charging cable of the electric vehicle or plug-in hybrid vehicle. Finally, the charging device 1 has a control device 7. The control device 7 is configured to operate the DC / DC converters 6. The DC / DC converters 6 are preferably all constructed in the same manner and preferably provide a power of 3.6 kW. The DC / DC converters 6 are preferably configured as bidirectional multilevel DC / DC converters 6, which will be explained in more detail later. The control device 7 is also configured to distribute power unevenly among the DC / DC converters according to the power requirements and parameters of the switching elements of the DC / DC converters 6. This should now be briefly explained, assuming there are twelve DC / DC converters 6, each with a power of 3.6 kW. Correspondingly, the charging device 1 can provide a charging power between 43 kW and zero. Here, each of the DC / DC converters 6 has an optimal operating point in terms of efficiency. The control device 7 can then calculate how many DC / DC converters 6 are needed at the optimal operating point for the required power and accordingly operate these DC / DC converters, conversely turning off other DC / DC converters 6. Based on the parameters of the switching elements of the DC / DC converters 6, the control device 7 also determines which DC / DC converters 6 are turned on and which are turned off. Based on parameters such as temperature and output current, aging or load conditions can be inferred. Other parameters may be, for example, the frequency of the switching process and / or the total operating time. Now, in order to delay the complete failure of the DC / DC converters in time, the control device 7 attempts to distribute the load evenly among all DC / DC converters 6, where the weakest switching element of the DC / DC converter 6 is always decisive. Therefore, the advantage is the flexible delivery of a wide range of power, where the additional cost of the resulting increased switching elements contributes to increasing the overall lifespan of the charging device 1.

[0024] Figure 2 The diagram schematically illustrates the input stage of a charging device 1 with three grid connection terminals 2, wherein each grid connection terminal 2 is assigned its own power correction factor circuit 5, the output terminals of which are connected in parallel.

[0025] Figure 3The diagram illustrates a schematic circuit arrangement of a three-stage bidirectional multilevel DC / DC converter 6. The DC / DC converter 6 has a central input inductor L and six switching elements S in the form of MOSFETs. Freewheeling diodes are shown connected in parallel with the switching elements S. The first two switching elements S and capacitor C2 form the first stage of the DC / DC converter 6. The middle two switching elements S and capacitor C1 form the second stage of the multilevel DC / DC converter 6, and the last two switching elements S and capacitor C0 form the third stage of the multilevel DC / DC converter 6. Through these three stages, blocking voltages can be distributed across them, allowing blocking voltages of 800V and above to be achieved using transistors designed for, for example, 600V. Due to the reduced blocking voltage on each switching element S, these switching elements can be switched more quickly.

[0026] Another advantage of the mass-produced DC / DC converter 6 is that the corresponding central input inductor L can be smaller, allowing for a more compact structure. The switching elements are controlled by a gate driver module 10, wherein such a gate driver module 10... Figure 4 As shown in the image.

[0027] Figure 4 The diagram shows a schematic block diagram of a gate driver module 10 for turning on and off a power transistor LT, which acts as a switching element S. Here, the gate driver module 10 has a first output terminal A1, at which a capacitor C is arranged. dy and the on-resistance R G1 A series circuit is formed, which is connected to the gate G of the power transistor LT. This series circuit is connected to the turn-off resistor R at the second output terminal A2. G2 Parallel connection. A current source I0 exists at the third output terminal A3. Furthermore, the gate driver module 10 also includes a configuration unit 12, a logic unit 13, a fault unit 14, and an isolated voltage supply source 15, which supplies two switchable voltage sources V. p V s It also provides power supply voltage to units 12-14. The gate driver module 10 also includes a switch module 16 with four switches S1-S4 and an amplifier 17. Configuration unit 12 obtains control device 7 (see...). Figure 1 The configuration signal SPI is used to obtain the configuration of the upper-level circuit and the position of the gate driver module 1 in the configuration of the upper-level circuit.

[0028] Alternatively or additionally, this information is encoded via a discrete interconnect that can be detected at input D. Logic unit 13 obtains a PWM signal from control device 7, which is actuated by logic unit 13 through switching elements S1-S4. Furthermore, logic unit 13 can access data from configuration unit 12 and store the PWM signal. Based on the temperature T of power transistor LT... jct and the output current I of the power transistor LT out Fault unit 14 generates a fault signal, which appears at the output terminal Fault_out. The temperature T of the power transistor... jct For example, a temperature sensor 18 determines the fault and transmits it to the fault unit 14 via an amplifier 17. Furthermore, the fault unit 14 receives the fault message Fault_in from the adjacent gate driver module and / or control device 7. Here, the fault unit 14 is connected to the logic unit 13 via a connection not shown. If the power transistor LT should now be turned on very quickly, switch S3 closes (S1, S2, and S4 remain open). After turning on, S3 opens and S1 closes. To turn off, S4 closes and the other switches S1 through S3 open. Then S4 can be opened and S2 closed. Therefore, only one switch S1-S4 is always closed at any given time, with switches S1 and S3 used for turning on, and switches S2 and S4 used for turning off. It should be noted that the order can also be reversed, i.e., for example, S3 can be closed first and then S1, or S2 can be closed first and then S4.

[0029] In the event of a fault, logic unit 13 now receives a fault message. Logic unit 13 is aware of the upper-level circuit configuration here, and can then, in the next step, coordinate with other gate driver modules of the circuit configuration to turn off its associated power transistor LT using the stored PWM signal, without causing a damaging reaction to other power transistors.

[0030] Figure 5 The diagram shows that the six gate driver modules 10 of the DC / DC converter 6 are daisy-chained with the control device 7, so that the control device 7 obtains the parameters of the transmitted switching element S.

[0031] List of reference numerals

[0032] 1. Charging equipment

[0033] 2. Power grid connection terminal

[0034] 3. AC voltage

[0035] 4. Fault Current Compensation Circuit

[0036] 5 Power Factor Correction Circuit

[0037] 6 DC / DC converters

[0038] 7. Control equipment

[0039] 10 Gate Driver Module

[0040] 12 Configuration Units

[0041] 13 Logic Units

[0042] 14 Fault Unit

[0043] 15. Voltage supply source

[0044] 16 Switch Modules

[0045] 17 Amplifier

[0046] 18 Temperature Sensor

[0047] S-Switching element

[0048] A1-A3 output terminals

[0049] AK output terminals

Claims

1. Charging device (1) comprising at least one grid connection (2) for an alternating voltage (3), a power factor correction circuit (5) for each grid connection (2), n DC / DC converters (6) connected in parallel, with n > 2, and a control device (7), wherein the control device (7) is configured to operate the DC / DC converters (6), wherein the control device (7) is further configured to distribute power non-uniformly to the DC / DC converters (6) depending on the power requirements and parameters of the switching elements (S) of the DC / DC converters (6).

2. The charging device according to claim 1, characterized in that, The charging device (1) is arranged in a motor vehicle, wherein the DC / DC converters (6) are connected to a traction battery of the motor vehicle.

3. The charging apparatus according to claim 1, characterized by, The charging device (1) is arranged in a charging station, wherein the DC / DC converters (6) are connectable to a DC voltage connection of a motor vehicle.

4. The charging device according to any one of the preceding claims, characterized in that, The DC / DC converters (6) are configured as multi-level DC / DC converters (6).

5. The charging device according to any one of the preceding claims, characterized in that, The DC / DC converters (6) are configured as bidirectional DC / DC converters (6).

6. The charging device according to any one of the preceding claims, characterized in that, An active fault current compensation circuit (4) is arranged at the grid connection (2).

7. The charging device according to any one of the preceding claims, characterized in that, A gate driver module (10) is assigned to a switching element (S) of the DC / DC converters (6), wherein the gate driver module (10) is configured to detect parameters of the switching element (S), wherein the gate driver modules (10) of the DC / DC converters (6) are connected to each other in a daisy chain with the control device (7).

8. The charging device according to any one of the preceding claims, characterized in that, The gate driver modules (10) each have a configuration unit (12) in which a superior circuit configuration of the gate driver module (10) to other gate driver modules (10) is stored or detectable, wherein the gate driver modules (10) further have a logic unit (13) configured to receive a PWM signal from the control device (7) and store the PWM signal for at least one clock cycle.

9. The charging apparatus according to claim 8, characterized by, The gate driver modules (10) each have at least one fault unit (14), wherein the fault unit (14) is configured to forward at least one internal fault of the gate driver module (10) to at least one adjacent gate driver module (10) and the control device (7) and to receive fault messages of at least one adjacent gate driver module (10) and the control device (7), wherein the logic unit (13) is further configured to generate a PWM signal to switch off the connected switching element (S) depending on the fault messages of the fault unit (14), the stored or detected circuit configuration and the stored PWM signal.

10. The charging device according to any one of claims 7 to 9, characterized in that, The gate driver module (10) has at least two switchable voltage sources (V p , V s ) and at least two outputs (A1, A2), to which the on and off resistors (R G1 , R G2 ) are connectable, wherein the gate driver module (10) has at least one third switchable output (A3), to which at least one current source (I0) is connected in parallel to the on and off resistors (R G1 , R G2 ).

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