Supplying low-voltage on-board electrical system of vehicle from high-voltage on-board electrical system of vehicle

Abstract

The invention relates to a method (S1-S8) for supplying an NV on-board network (NVN) of a vehicle from an HV on-board network (HVN) of the vehicle with an adjustable value (Iout, maxdef, Iout, maxred) of a current saturation (Iout, max) by means of at least one electrically isolated DC voltage converter (GSW1, GSW2, GSW3), in which an auxiliary voltage (Vin, th) is determined (S0) at the DC voltage converter (GSW1, GSW2, GSW3), said auxiliary voltage being between a nominal voltage (Vin, th) of the HV on-board network (HVN) and a nominal voltage (Vin, th) of the HV on-board network (HVN). Between a reference value (Iout, max) of the current saturation (Iout, max) and a specified minimum input voltage (Vin, min), an associated input power (Pin) is determined (S5) when the input voltage (Vin) measured at the DC voltage converter drops (S1) below a value of the auxiliary voltage (Vin, th), a power-adapted value (Iout, max) of the current saturation (Iout, max) is calculated from the previously determined input power (Pin), and this value is adjusted (S5) in place of the reference value (Iout, max) of the current saturation (Iout, max), in order to determine the current saturation (Iout, max) of the current saturation (Iout, max). And resetting (S3) the current saturation (Iout, max) to a standard value (Iout, maxdef) only when the input voltage (Vin) reaches (S2) the nominal voltage (Vin, nom) of the HV partial on-board electrical system (HVN) again.

Description

Technical Field

[0001] The invention relates to a method for supplying an NV (low voltage) partial onboard power supply system of a vehicle from an HV (high voltage) partial onboard power supply system of a vehicle via at least one electrically isolated DC voltage converter. The invention also relates to a vehicle having an energy onboard power supply system with an HV partial onboard power supply system and an NV partial onboard power supply system, between which at least one electrically isolated DC voltage converter is connected, wherein the vehicle is configured to carry out the method. The invention can be used in particular advantageously in electric vehicles. Background Art

[0002] M. Baumann, Yue Sun, Bert Haj Ali, C. Weissinger, H. Herzog: “Deadzone Compensated Double Integral Sliding Mode Control for Distributed Converters”, IEEE Transportation Electrification Conference & Expo (ITEC), June 21-25, 2021, discloses a design approach for a so-called “Double Integral Sliding Mode Control (DISMC)” applied to topologies derived from step-down transformers. A control strategy based on the so-called “Voltage Mode Control” (VMC) is augmented with dead-zone compensated current control in order to stabilize fault conditions such as short circuits. A control concept for distributed rectifiers is derived and verified by bench-based measurements. DISMC is validated at a prototype 1-kW converter and compared with the industry-standard PI-based control design. Settling time and overshoot Both can be reduced by up to 67% or 35%. Summary of the invention

[0003] The object of the present invention is to at least partially overcome the disadvantages of the prior art and to provide a reliable power supply of the NV partial onboard electrical system without supplying a chemical NV memory from the HV partial onboard electrical system of the vehicle.

[0004] This object is achieved according to the features of the independent claim. Preferred embodiments can be gathered in particular from the dependent claims.

[0005] The object is to provide a method for transmitting a current to a DC voltage converter with a current saturation I via at least one electrically isolated DC voltage converter. out,max The adjustable value of the vehicle is solved by a method of supplying power to the NV part of the vehicle from the HV part of the vehicle's onboard power grid, wherein at the DC voltage converter

[0006] - Determine the auxiliary voltage V in,th , the auxiliary voltage is between the rated voltage V in,nom and the specified minimum input voltage V in,min between,

[0007] - When the input voltage V measured at the DC voltage converter in Drop to the auxiliary voltage V in,th When the value is below, determine the input power P at the DC voltage converter in ,as well as

[0008] - Calculation of a "power-adapted" value I of the current saturation based on the previously determined input power out,max|red , and adjust this value, replacing the standard value of current saturation, and

[0009] - When the input voltage V in The rated voltage V of the HV onboard power supply is reached again in,nom When the current saturation I out,max Reset to default or standard values ​​I out,max|def .

[0010] This method has the advantage that even in the case of limited power supply (e.g. in the case of an aged high-voltage battery, increased impedance of the HV partial onboard power supply, etc.), a supply of the low-voltage energy onboard power supply can be provided. This is achieved by adapting the current saturation I according to a hysteresis that depends on the determined input power. out,max Thus, even if the HV side input voltage V in In smaller cases, it is also possible to power the NV part of the vehicle power grid with a smaller voltage.

[0011] The low voltage (“NV”) part of the onboard power supply has a rated onboard power supply voltage which is lower than the rated onboard power supply voltage V of the high voltage (“HV”) part of the onboard power supply in,nom .

[0012] An electrically isolated DC voltage converter is a DC voltage converter whose input side, which is connected to the HV onboard power supply, is electrically isolated from its output side, which is connected to the NV onboard power supply. The electrical isolation can be achieved in a manner known in principle by mutually opposing input-side and output-side coils with a corresponding number of turns. Thus, a turns ratio n is obtained for the DC voltage converter. The input voltage V applied to the input side is in It can be measured by the DC voltage converter itself.

[0013] For example, the vehicle can be a car with an internal combustion engine, a plug-in hybrid electric vehicle (PHEV) or a fully electric vehicle (BEV). The vehicle can be a car, a truck, a motorcycle, an aircraft (aircraft, helicopter, etc.), a watercraft (boat, ship, etc.) or a combination thereof.

[0014] Current saturation l out,max In particular, it corresponds to the current value that can be fed into the NV onboard power supply subsystem by a corresponding DC voltage converter on the output side. out,max The value of can be adjusted in particular by means of the DC voltage converter itself. The standard value can correspond, for example, to the maximum output current value determined by the design.

[0015] Especially suitable for V in,nom >V in,th >V in,min .

[0016] When the input voltage V in Drop to the auxiliary voltage V in,th When the value is below, determine the input power P at the DC voltage converter in , calculate the new "power-adapted" current saturation value I out,max|red , and adjust the current saturation value to replace the standard current saturation value I out,max|def , which includes the fact that in particular in such situations which usually occur when there are no transient processes, it is initially applicable and also applies to I out,max =I out,max|def For example, when transient behavior occurs, V in Drop to the auxiliary voltage V in,th When the value is below out,max Switch to I out,max|red , where I out,max|red Depending on the input voltage P present at the time the drop is detected in and is usually less than I out,max|def , that is, applicable out,max|red (P in ) out,max|def The DC voltage converter then results in a smaller load on the HV part of the onboard power grid. Input voltage V​in Drop to the auxiliary voltage V in,th Below the value, according to the design scheme, it can correspond to V in <V in,th Relationship or V in ≤V in,th relationship.

[0017] When the input voltage V in The rated voltage V of the HV onboard power supply is reached again in,nom When the current saturation I out,max Reset to standard value I out,max|def , which corresponds to the current saturation I out,max The value of V in,th With V in,nom Therefore, if the input voltage V in Between V in,th With V in,max Between, maintain I out,max The current value of the input voltage V in The rated voltage V of the HV onboard power supply is reached again in,nom , according to the design scheme, can correspond to V in ≥V in,nom Relationship or V in >V in,nom relationship.

[0018] One embodiment is to use the current I flowing through the DC voltage converter on the input side in Calculate the input power P in =V in I in Ignoring the power loss of the DC voltage converter, the input power corresponds to the output power V at the output side of the DC voltage converter. out I out Therefore, the input power P in It can also be based on the relationship V out I out The calculation is performed with or without taking into account the power loss of the DC voltage converter.

[0019] One design solution is to use a voltage V in drops to the minimum specified input voltage V in,min When the following (i.e., according to the implementation scheme, V in ≤V in,min or V in <V in,min ), the DC voltage converter is turned off, and when the input voltage V in The minimum input voltage V in,minWhen (that is, according to the implementation scheme, V in >V in,min or V in ≥V in,min ), the DC voltage converter is turned on again.

[0020] Switching off the DC voltage converter includes, in particular, that the DC voltage converter switches off its converter functionality and thus does not output a signal on the output side. Similarly, switching on the DC voltage converter includes, in particular, that the DC voltage converter switches on its converter functionality. Other functions and / or components of the DC voltage converter, such as the monitoring of the input voltage, the detection of reaching different threshold values ​​and the subsequent reactions (e.g. switching off and switching on the converter functionality) by the DC voltage converter, in particular remain unaffected.

[0021] One design is that the NV part of the vehicle power grid is powered by a plurality of DC voltage converters from the HV part of the vehicle power grid. This has the advantage that relatively simple and inexpensive DC voltage converters can be used, and in addition, a particularly high fault reliability and thus a power supply reliability for the NV part of the vehicle power grid is achieved. This method is particularly advantageous for this design because it prevents circulating currents between the distributed DC voltage converters or at least significantly reduces the influence of the circulating currents. Otherwise, these circulating currents cause losses and may also damage the DC voltage converters. Because during transient loads, the input voltage V at the nodes of the individual DC voltage converters in may be different, or the total power of the DC voltage converters distributed in the vehicle may exceed the power supply of the HV part of the on-board power supply. in Drop to V in,min When V in Reach V again in,min , the DC voltage converter is then switched on again. The switched-on DC voltage converter then supplies power to the NV part of the onboard power system again and exceeds the available system power of the HV part of the onboard power system. Then, without further measures, it will be switched off and on again, which with further repetitions leads to a huge load on the electronic devices of the DC voltage converter, which may even be damaged in the worst case. This load on the electronic devices is avoided by the adaptation of the current saturation value described above.

[0022] One embodiment is to carry out the above method independently for each of the DC voltage converters. This is advantageous because the input voltage V inmay be different, for example, when transient processes occur. One embodiment is to determine the input voltage V applied to the DC voltage converter individually for each of the DC voltage converters. in This also results in the DC voltage converters being switched on and off individually.

[0023] One design solution is to use V in,min =n·V out,ref To calculate the minimum input voltage V in,min , where n is the turns ratio of the DC voltage converter, and V out,ref is the control reference voltage. The (control) reference voltage corresponds in particular to a target control variable of the DC voltage converter at its output-side terminals. The target control variable can be adjusted on the vehicle side and thus adapted, for example, to different demand scenarios. The target control variable can generally be higher, lower or equal to the rated voltage of the NV part onboard power system.

[0024] One design solution is to use a reference voltage V on a data line, in particular on a CAN bus. out,ref This results in an easy adaptation of the reference voltage V through multiple converters. out,ref and can therefore also be implemented in practice, for example, since such an adaptation is not time-critical within the typical transmission times of the bus.

[0025] One design solution is to follow l out,max|red =P in n / V in,th To calculate the current saturation value I after power adaptation out,max|red .

[0026] One embodiment is that the DC voltage converter is a synchronous rectifier. This has the advantage that relatively low losses occur. In rectifiers of this type, components are usually not used that only allow current to flow in one direction; instead, MOSFETs are often used, which are controlled by the control electronics of the DC voltage converter in such a way that they act like semiconductor diodes with a very low forward voltage.

[0027] One embodiment is that the synchronous rectifier is a push-pull flow converter with full-bridge actuation. One embodiment is that the synchronous rectifier is a phase-shifted full-bridge DC voltage converter. Such a converter is particularly well suited even for higher power levels of up to several kilowatts.

[0028] The rectifier in particular can be similar to the one described in the article "Deadzone Compensated Double Integral Sliding Control for Distributed Converter" Figure 1 The rectifier described in (a) is constructed.

[0029] One design solution is that the rated voltage of the HV part of the vehicle power grid is V in,nom Between 48V and 1000V. One design option is that the rated voltage of the NV part of the vehicle power grid is V NV,nom Between 12 V and 60 V. In general, it applies that the rated voltage of the HV onboard power supply is greater than the rated voltage of the NV onboard power supply. Possible examples include V in,nom =48V, 60V or 120V, and V NV,nom =12V; V in,nom =120V, 400V or 800V, and V NV,nom =48V or 60V, etc.

[0030] The object is also achieved by a vehicle having an onboard energy system with an HV onboard power system component and an NV onboard power system component, between which at least one electrically isolating DC voltage converter is connected, wherein the vehicle is configured to carry out the method as described above. The vehicle can be constructed similarly to the method and vice versa and has the same advantages.

[0031] Thus, in one embodiment, the vehicle may be an electric vehicle that is partially or fully electrically driven, for example a plug-in hybrid vehicle or a battery electric vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The characteristics, features and advantages of the present invention described above and the ways and methods of achieving these characteristics, features and advantages will become clearer and more understandable in conjunction with the following schematic description of an embodiment, which is explained in more detail in conjunction with the accompanying drawings.

[0033] Figure 1 A schematic diagram showing a detail of an onboard energy system of a vehicle; and

[0034] Figure 2 A possible sequence of the method according to the invention is shown. DETAILED DESCRIPTION

[0035] Figure 1The schematic diagram shows a section of an energy onboard power supply system EBN of a vehicle F. The energy onboard power supply system EBN has an NV onboard power supply subsystem NVN which can be supplied with power from an HV onboard power supply subsystem HVN via a plurality of electrically isolated DC voltage converters GSW1, GSW2, GSW3. The DC voltage converters GSW1, GSW2, GSW3 convert the higher voltage V of the HV onboard power supply subsystem HVN to in Convert to a lower voltage V out,ref The output voltages V of the DC voltage converters GSW1, GSW2, and GSW3 are out Optionally, they are connected to the cable harness KB of the NV partial onboard power supply NVN via respective resistors Z, which can be identical or different.

[0036] The DC voltage converters GSW1, GSW2, GSW3 are connected to a communication channel (here, for example, a CAN bus CAN) of the vehicle F and can communicate with one another via the communication channel. The DC voltage converters GSW1, GSW2, GSW3 can be present in a master-slave configuration, for example, the DC voltage converter GSW1 being used as a master and the DC voltage converters GSW2, GSW3 being used as slaves.

[0037] NV part of the vehicle power grid reference voltage V out,ref The desired value can be communicated to the DC voltage converters GSW1, GSW2, GSW3 via the CAN bus CAN, for example.

[0038] Figure 2 A possible sequence of steps of a method for supplying an NV onboard electrical system subsystem NVN with power from an HV onboard electrical system subsystem HVN by means of adapting one of the DC voltage converters GSW1 , GSW2 or GSW3 is shown.

[0039] -Rated voltage V of the HV part of the onboard power supply HVN in,nom Greater than the rated voltage of the NV part of the on-board power grid NVN;

[0040] - specifies the auxiliary voltage V in,th , which is between the rated voltage V of the HV part of the vehicle power grid HVN in,nom The minimum input voltage V of the HV onboard power supply HVN is specified in,min between,

[0041] - Current saturation I out,max The standard or default value is I out,max|def .

[0042] Herein, for further description of the method, the following values ​​are assumed purely by way of example: V in,nom =48V, V in,th=40V, V NV,nom and V out,ref =12V, and n=3. It follows that V in,min =n·V NV,nom =12V=36V. Also applicable to V in,nom >V in,th >V in,min It is further assumed that at the beginning of the method in step S0 there are no transient processes or other disturbances and that the DC voltage converters GSW1 , GSW2 , GSW3 are open, which is described by their state “ON”. in Initially the auxiliary voltage V is higher than 40V in,th .

[0043] After the method is started in step S0, it is checked in step S1 whether the input voltage V in Is it less than the auxiliary voltage V in,th This is usually not the case in a healthy HV partial onboard power supply system HVN without transient processes (“No”), wherein it is then queried in step S2 whether the input voltage V in Is it less than the rated voltage V of 48V of the HV part of the vehicle power grid HVN? in,nom If this is the case ("yes"), return to step S1.

[0044] However, if it is determined in step S1 that the input voltage V in Less than the auxiliary voltage V in,th (“Yes”), that is, V in <V in,th , then in step S4, the current saturation I out,max Is it set to the power-adapted value I out,max|red If this is not the case (“No”) and the current saturation I out,max Therefore, it is still at the standard value I out,max|def , then branch to step S5.

[0045] In step S5, the input power P currently present at the input side of the DC voltage converters GSW1, GSW2, GSW3 is calculated. in =V in I in , and the power-adapted current saturation value I is calculated accordingly out,max =I out,max|red :=(n·P in ) / V in,th , the power-adapted current saturation value is now adjusted to replace the standard value I at the DC voltage converters GSW1, GSW2, GSW3 out,max|def . This usually applies to I out,max|redout,max|def , so that the maximum power transfer from the HV onboard power subsystem HVN to the NV onboard power subsystem NVN via the DC voltage converter GSW1 , GSW2 or GSW3 is reduced and thus also reduced overall. Then, the process proceeds to step S6 .

[0046] However, if step S4 is answered affirmatively ("yes"), the current saturation I out,max has been adjusted to the power-adapted value I out,max|red , then directly branch to step S6. Therefore, this process includes, the current saturation value I out,max|red After it has been adjusted, it remains unchanged until it is reset to the standard value I out,max|def .

[0047] Then, in step S6, it is checked whether the input voltage V in Is it even less than the minimum input voltage V in,min , that is, whether V in <V in,min .

[0048] If this is the case (“yes”), in step S7 the DC voltage converter GSW1 , GSW2 or GSW3 in question is individually switched off, which is indicated by the switch state “OFF”.

[0049] After the shutdown, the process returns to step S6 and thus the relevant query is performed again. Thus, the DC voltage converter GSW1, GSW2 or GSW3 in question remains switched off for such a long time that the input voltage V in Again greater than or equal to the minimum input voltage V in,min (“No”). In this case, or when the input voltage V is determined for the first time in step S6 in Greater than or equal to the minimum input voltage V in,min When , branch to step S8.

[0050] In step S8, the DC voltage converter GSW1, GSW2 or GSW3 in question remains switched on or is switched on, and the process returns to step S1. in The value is still less than the auxiliary voltage V in,th (“Yes”), then branch to step S4 again. out,max|red Still, it is always regulated that a branch is taken directly (“Yes”) from step S4 to step S6 .

[0051] However, if the input voltage V in The value is now greater than or equal to the auxiliary voltage V in,th ​(“No”), then query again in step S2, the input voltage V in Is it less than the rated voltage V of the HV part of the vehicle power grid HVN? in,nom If this is the case (“yes”), the current power-adapted current saturation value I out,max|red Remain unchanged and return to step S1.

[0052] Only when the input voltage V in The value reaches the rated voltage V again in,nom When (“No”), the current saturation I out,max Reset or reset to standard value I out,max|def .

[0053] Of course, the invention is not limited to the embodiments shown.

[0054] Thus, there may also be only one DC voltage converter GSW1 , only two DC voltage converters GSW1 , GSW2 , or more than three DC voltage converters GSW1 , GSW2 , GSW3 .

[0055] Furthermore, generally, and in this embodiment, for example in steps S1 , S2 and / or S6 , the condition of “less than or equal to” or “greater than” may be queried instead of the condition of “less than” or “greater than or equal to”.

[0056] Generally, “a”, “an” etc. can be understood as singular or plural, especially in the sense of “at least one” or “one or more” etc., as long as this is not explicitly excluded, for example by the expression “exactly one” etc.

[0057] Numerical specifications may also include exactly the stated numbers but also include the usual tolerance ranges, unless this is explicitly excluded.

[0058] Reference numerals list

[0059] CAN CAN bus

[0060] EBN Energy Onboard Grid

[0061] F Vehicle

[0062] KB Cable Harness

[0063] GSW1 DC Voltage Converter

[0064] GSW2 DC Voltage Converter

[0065] GSW3 DC Voltage Converter

[0066] I in The input current through the DC voltage converter

[0067] HVN HV Part of the vehicle power grid HVN

[0068] I out,max Current saturation

[0069] I out,max|def Standard value of current saturation

[0070] I out,max|red Power-adapted value of current saturation

[0071] n Turns ratio

[0072] NVN NV part of the vehicle power grid

[0073] OFF Off state

[0074] ON state

[0075] P Input power

[0076] S0-S8 Method Steps

[0077] V in Measured input voltage

[0078] V in,min Minimum input voltage

[0079] V in,nom Rated voltage of the HV part of the onboard power supply

[0080] V out,ref Reference voltage

[0081] V in,th Auxiliary voltage

Claims

1. For providing a DC voltage converter (GSW1, GSW2, GSW3) with a current saturation (I out,max ) adjustable value (I out,max|def ,I out,max|red ) A method (S1-S8) for supplying power to a NV part onboard power grid (NVN) of a vehicle from a HV part onboard power grid (HVN) of a vehicle, wherein: At the DC voltage converter (GSW1, GSW2, GSW3) - Determine (S0) auxiliary voltage (V in,th ), which is between the rated voltage (V in,nom ) and the specified minimum input voltage (V in,min )between, -When the input voltage (V in ) drops (S1) to the auxiliary voltage (V in,th ) is less than the value, determine (S5) the input power (P in ), - Based on the previously determined input power (P in ) to calculate the current saturation (I out,max ) of the power-adapted value (I out,max|red ), and adjust (S5) the power-adapted value, replacing the current saturation (I out,max ) standard value (I out,max|def ),as well as -When the input voltage (V in ) reaches (S2) the rated voltage (V in,nom ) will cause the current saturation (I out,max ) reset (S3) to the standard value (I out,max|def ).

2. The method (S1-S8) according to claim 1, wherein: When the input voltage (V in ) drops (S6) to the minimum input voltage (V in,min ) is below, the DC voltage converter (GSW1, GSW2, GSW3) is turned off (S7), and when the input voltage (V in ) reaches (S6) the minimum input voltage (V in,min ), the DC voltage converters (GSW1, GSW2, GSW3) are turned on again (S8).

3. The method (S1-S8) according to any of the preceding claims, wherein: The NV onboard power supply part (NVN) is supplied from an HV onboard power supply part (HVN) by means of a plurality of DC voltage converters (GSW1, GSW2, GSW3).

4. The method (S1-S8) according to any of the preceding claims, wherein: According to V in,min =n·V out,ref To calculate the minimum input voltage (V in,min ), where n is the turns ratio of the DC voltage converter (GSW1, GSW2, GSW3), and V out,ref It is the regulation reference voltage of the DC voltage converter (GSW1, GSW2, GSW3) at the output side.

5. The method (S1-S8) according to any one of claims 3 to 4, wherein: The reference voltage (V out,ref ) are exchanged between the DC voltage converters (GSW1, GSW2, GSW3).

6. The method (S1-S8) according to any of the preceding claims, wherein: According to I out,max =P in / V in,th ·n to calculate the current saturation value (I out,max ), where P in is the input power (P in ) value, and V in,th is the auxiliary voltage (V in,th ) value.

7. The method (S1-S8) according to any of the preceding claims, wherein: The at least one DC voltage converter (GSW1, GSW2, GSW3) is a synchronous rectifier.

8. The method (S1-S8) according to claim 7, wherein: The synchronous rectifier is a phase-shifted full-bridge DC voltage converter.

9. The method (S1-S8) according to any of the preceding claims, wherein: Rated voltage of the first HV part onboard power supply (HVN) (V in,nom ) is between 48V and 1000V.

10. The method (S1-S8) according to any of the preceding claims, wherein: The rated voltage of the NV part vehicle power grid (NVN) is between 12V and 60V.

11. A vehicle (F) having an onboard energy system (EBN) with an HV onboard power system component (HVN) and an NV onboard power system component (NVN), between which at least one electrically isolating DC voltage converter (GSW1, GSW2, GSW3) is connected, wherein: The vehicle (F) is configured to carry out a method (S1-S8) according to one of the preceding claims.

12. The vehicle (F) according to claim 11, wherein The vehicle (F) is an electric vehicle.

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