Method for operating an electrical system

Abstract

The invention relates to a method for operating an electrical system with a plurality of electrical machines of a vehicle. According to the invention, it is provided that - a remaining current availability (VSV) is calculated as the difference between a maximum current availability (MSV) and a sum (SIS) of actual currents (IS1 to ISn) of all electrical machines, - for the respective electrical machine, a current availability (SV1 to SVn) is calculated as the sum of the calculated remaining current availability (VSV) and the actual current (IS1 to ISn) of the respective electrical machine, and - the calculated current availability (SV1 to SVn) of the respective electrical machine is provided.

Description

[0001] The invention relates to a method for operating an electrical system according to the features of the preamble of claim 1.

[0002] A method for optimizing the transfer behavior of a power electronic system is known from the prior art, as described in DE 10 2007 050 228 A1. A state observer simulates the state of the power electronic system. A deviation detection unit detects deviations of a simulated state variable of the state observer from the corresponding state variable of the power electronic system. An optimization unit sets a parameter for optimizing the transfer behavior depending on the deviation of state variables of the state observer from the corresponding state variable of the power electronic system. The optimization unit sets a control-independent parameter for optimizing the transfer behavior depending on the deviation of the simulated state variable of the state observer from the corresponding state variable of the power electronic system.

[0003] The invention is based on the object of providing a method for operating an electrical system which is improved compared to the prior art.

[0004] The object is achieved according to the invention by a method for operating an electrical system having the features of claim 1.

[0005] Advantageous embodiments of the invention are the subject of the subclaims.

[0006] In a method according to the invention for operating an electrical system of a vehicle, wherein the electrical system comprises a plurality of electrical machines, also referred to as electric prime movers, each of which is configured, in particular, as an electric drive motor for driving the vehicle, a remaining power availability is calculated in a first step. This remaining power availability is the difference between a maximum power availability and a sum of the actual currents of all electrical machines.

[0007] The actual currents are, in particular, the currents currently present in the electrical machines. In the first step, these actual currents are added together, and the resulting sum of the actual currents is subtracted from the maximum current availability.

[0008] The maximum power availability is, in particular, the current provided by a power source or the current provided by the power source less the actual currents of all other electrical consumers of the vehicle, i.e., all electrical consumers except the electrical machines, or the current provided by the power source less a predetermined power availability for all other electrical consumers of the vehicle, i.e., for all electrical consumers except the electrical machines. The power source is, in particular, at least one drive battery of the vehicle, i.e., in particular, a battery intended to supply electrical energy to the electrical machines.

[0009] The remaining power availability calculated in the first step in the manner described can optionally be multiplied by a factor between 0 and 1, in particular in order to adjust and / or calibrate the control quality of the entire system.

[0010] In a second step of the method, a power availability is calculated for the respective electrical machine. This power availability is the sum of the result of the first step and the actual current of the respective electrical machine, i.e., the sum of the calculated remaining power availability and the actual current of the respective electrical machine, or optionally, if the calculated remaining power availability was multiplied by a factor between 0 and 1, the sum of the calculated remaining power availability and the actual current of the respective electrical machine multiplied by a factor between 0 and 1.

[0011] This means that in this second step, the power availability for the respective electrical machine is calculated by adding the actual current of the respective electrical machine to the remaining power availability calculated in the first step or to the remaining power availability calculated in the first step and multiplied by a factor between 0 and 1.

[0012] In a third step of the method, the power availability of the respective electrical machine calculated in the second step is provided.

[0013] In particular, it is intended that this process cycle, in particular comprising the described three steps of the process, is repeated in a time-discrete manner.

[0014] In particular, a time interval between the start of one process cycle and the start of a subsequent process cycle is shorter than a rise time of a predetermined current rise ramp for the current rise of the electrical machines.

[0015] The rise time of the specified current rise ramp for the current rise of the electrical machines is, for example, 100 milliseconds.

[0016] For example, the time interval between the start of one process cycle and the start of a subsequent process cycle is 10 milliseconds.

[0017] The described solution ensures that the current provided in the electrical system, i.e. the maximum current availability of the entire system, is not exceeded, as this must not happen. To ensure this, all electrical machines in the electrical system are each assigned their own current availability using the described method, which the respective electrical machine must not exceed. To do this, the described method first calculates the remaining current availability, which results from subtracting the sum of the actual currents of all electrical machines, in particular all relevant electrical machines, from the maximum current availability. This remaining current availability can, as described above, optionally be multiplied by a factor between 0 and 1 in order to adjust and / or calibrate the control quality of the entire system.The power availability for the respective electrical machine is then calculated from the sum of the remaining power availability, optionally multiplied by a factor between 0 and 1, and the actual current of the respective electrical machine.

[0018] The method can be used for electrical systems with any number of electrical machines.

[0019] The described solution makes it possible to correctly divide the current based on the power demand without requiring the division a priori.

[0020] The described solution thus enables, in particular, an intelligent distribution of power availability in electrical nodes with several electrical machines, ie in particular in an electrical system with several electrical machines.

[0021] The solution described solves, for example, the problem that in an electrical system with, for example, an electrical power source and two electrical machines, the power has to be divided because the supplied power, i.e. the power availability, must not be exceeded. This is particularly disadvantageous with previously known approaches if the distribution cannot be easily predetermined, for example if the vehicle is designed as an all-wheel drive vehicle with two driven axles, i.e. each electrical machine drives one axle of the vehicle, and the power distribution can change dynamically, for example due to driving dynamics interventions. The solution described now makes it possible to correctly divide the power based on the power requirements of the electrical machines, without the distribution requiring a priori.

[0022] The solution described ensures that all components of the electrical system, in particular all electrical machines in the electrical system, are always provided with the entire available current. In an ideal and therefore infinitely fast electrical system, this would lead to an immediate overload of the electrical power source. However, real electrical systems are not infinitely fast and are not ideal. The build-up of a current flow takes time and is usually shaped by other boundary conditions of the system. As described above, for example, a current rise ramp is provided for the current rise of the electrical machines so that the speed and / or torque of the respective electrical machine and thus its current consumption does not increase suddenly, but rather in a ramp-like manner, in particular to ensure the driving stability and ride comfort of the vehicle.

[0023] The process operates discretely and quickly enough so that the electrical system is not overloaded. In the next computation step, i.e., the next process cycle, a portion of the available power is consumed and is not divided again. The entire power output of the electrical system can be accessed again. The process cycle begins again, and the electrical system stabilizes itself in this way.

[0024] The described method enables control of electrical limitations in the vehicle's electrical system, particularly the drive system, independently of strategic torque specifications. This solution gives the operating strategy complete freedom to utilize and distribute power without having to consider electrical limitations.

[0025] An additional advantage is that recuperated electrical power is immediately available elsewhere, as it forms part of the maximum power availability in the next process cycle. This is particularly advantageous in torque vectoring, also known as torque distribution.

[0026] The described method can be applied in drive configurations with any number of electrical machines without the need for complex software adaptations.

[0027] Embodiments of the invention are explained in more detail below with reference to a drawing.

[0028] It shows: Fig. 1 schematically shows a sequence of a method for operating an electrical system.

[0029] Fig. 1 shows a schematic representation of a process sequence of a method for operating an electrical system of a vehicle, wherein the electrical system comprises a plurality of electrical machines, each of which is designed in particular as an electric drive machine for driving the vehicle. Fig. 1, in particular, a process cycle of the process. The process is, in particular, carried out in a time-discrete manner, ie, the process cycle shown is repeated in a time-discrete manner.

[0030] In the electrical system, the available current, i.e., the maximum current availability MSV of the entire electrical system, must not be exceeded. To ensure this, all electrical machines are assigned their own current availability SV1 to SVn, which the respective electrical machine may not exceed.

[0031] In the method, in a first step S1, a remaining power availability VSV is calculated, which results from a subtraction S of a sum SIS of actual currents IS1 to ISn of all electrical machines, in particular all relevant electrical machines, from the maximum power availability MSV.

[0032] The remaining power availability VSV can optionally be multiplied by a factor K between 0 and 1, as in Fig. 1 to adjust and / or calibrate the control performance of the entire system.

[0033] In a second step S2 of the method, the current availability SV1 to SVn is calculated for the respective electrical machine. This current availability SV1 to SVn for the respective electrical machine results from a sum of the remaining current availability VSV and the actual current IS1 to ISn of the respective electrical machine or, as in the example according to Fig. 1, from the sum of the remaining power availability VSV multiplied by the factor K between 0 and 1 and the actual current IS1 to ISn of the respective electrical machine.

[0034] In this second step S2, in order to calculate the current availability SV1 to SVn for the respective electrical machine, an addition A1 to An of the remaining current availability VSV and the actual current IS1 to ISn of the respective electrical machine is carried out, or in this second step S2, as in the example according to Fig. 1, to calculate the current availability SV1 to SVn for the respective electrical machine, an addition A1 to An of the remaining current availability VSV multiplied by the factor K between 0 and 1 and the actual current IS1 to ISn of the respective electrical machine is carried out.

[0035] In a third step S3 of the method, the power availability SV1 to SVn calculated for the respective electrical machine in the second step S2 is provided to the respective electrical machine.

[0036] The process can be extended to include any number of electrical machines.

[0037] The described solution makes it possible to correctly divide the current based on the power demand without requiring the division a priori. List of reference symbols A1 to An Addition IS1 to ISn actual current K factor MSV maximum power availability S Subtraction S1 first step S2 second step S3 third step SIS sum of actual currents of all electrical machines SV1 to SVn Power availability of electrical machine VSV remaining power availability QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2007 050 228 A1

[0002]

Claims

[1] Method for operating an electrical system with a plurality of electrical machines of a vehicle, characterized by , that - a remaining power availability (VSV) is calculated as the difference between a maximum power availability (MSV) and a sum (SIS) of actual currents (IS1 to ISn) of all electrical machines, - for the respective electrical machine, a current availability (SV1 to SVn) is calculated as the sum of the calculated remaining current availability (VSV) and the actual current (IS1 to ISn) of the respective electrical machine, and - the power availability (SV1 to SVn) calculated for the respective electrical machine is provided to the respective electrical machine. [2] Method according to claim 1, characterized bythat the calculated remaining power availability (VSV) is multiplied by a factor (K) between 0 and 1 and the power availability (SV1 to SVn) for the respective electrical machine is calculated as the sum of the calculated remaining power availability (VSV) multiplied by the factor (K) between 0 and 1 and the actual current (IS1 to ISn) of the respective electrical machine. [3] Method according to one of the preceding claims, characterized by that the process cycle is repeated discretely in time. [4] Method according to claim 3, characterized by that a time interval between the start of one process cycle and the start of a subsequent process cycle is less than a rise time of a predetermined current rise ramp for the current rise of the electrical machines. [5] Method according to claim 4, characterized bythat the rise time of the specified current rise ramp for the current rise of the electrical machines is 100 milliseconds. [6] Method according to claim 4 or 5, characterized by that the time interval between the start of one process cycle and the start of a subsequent process cycle is 10 milliseconds. [7] Method according to one of the preceding claims, characterized by that the maximum power availability (MSV) - is a current supplied by a power source, or - the current supplied by the power source less the actual currents of all other electrical consumers of the vehicle, or - the power provided by the power source less a predetermined power availability for all other electrical consumers of the vehicle. [8] Method according to claim 7, characterized by that the power source is at least one of the vehicle's traction batteries.

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