Method for controlling current output of a battery

Abstract

The present invention relates to a method for controlling the current output of a battery, wherein the battery is used as a traction battery for driving a rail vehicle. bat,ist Via a rectifier STR (DCDCW, ZWK, DCACW), the current is converted as a neutral three-phase AC current to an asynchronous motor (ASM) used as a drive for the rail vehicle. asm ‑Regler, U zk ‑Regler, I bat ‑Regler) according to the pre-control torque M ff and the preset torque M tf To set the actual battery current I bat,ist With the help of transfer function H sys (z) Calculate the pre-control torque M ff , the transfer function converts the torque rating M soll The actual battery current I is mapped as follows: bat,ist According to the present invention, the transfer function H sys (z) determines the zero point z=znmp outside the unit circle. The pre-control torque M ff The calculation is performed as follows: where and for all n>0, so that z=znmp in the ideal battery current I bat,ideal Pole-zero cancellation is achieved when .

Description

Technical Field

[0001] The invention relates to a method for controlling the current output of a battery, wherein the battery is used as a traction battery for driving a rail vehicle. Background Art

[0002] Battery-operated rail vehicles are known, in which electrical energy is drawn from a battery and used to drive an electric motor.

[0003] Figure 3 A controlled drive of such a rail vehicle according to the prior art is shown in a simplified schematic diagram.

[0004] The converter STR is connected to the battery BAT on the input side and to the asynchronous motor ASM on the output side.

[0005] The asynchronous motor ASM is used as a traction motor of a traction vehicle or rail vehicle, and the battery BAT is used as a traction battery.

[0006] The converter STR comprises a series circuit consisting of a DC / DC converter DCDCW, a (direct current) intermediate circuit ZWK and a DC / AC converter DCACW which follow one another.

[0007] The DC / DC converter DCDCW is connected to the battery BAT as an input element of the converter STR, and the DC / AC converter DCACW is connected to the asynchronous motor ASM as an output element of the converter STR.

[0008] Therefore, the actual battery current I from the battery BAT is bat,ist The DC / DC converter DCDCW of the converter STR converts the actual battery current into an intermediate circuit direct current I dcdc .

[0009] Intermediate circuit DC current I dcdc via the intermediate circuit ZWK as motor current I mot Arrives at the DC / AC converter DCACW.

[0010] A capacitor is arranged in the intermediate circuit ZWK, across which a differential actual voltage U d,ist .

[0011] Motor current I mot The three-phase current reaches the asynchronous motor ASM via the DC / AC converter DCACW to drive the asynchronous motor.

[0012] The DC / DC converter DCDCW is connected to the battery current regulator I bat -Regulator adjustment to adjust the intermediate circuit DC current Idcdc To this end, the battery current regulator I bat -Regler delivers a battery nominal current I bat,soll and an actual current I bat,ist as input signals.

[0013] The intermediate circuit ZWK is connected with the intermediate circuit voltage regulator U zk -Regler. To the intermediate circuit voltage regulator U zk -Regler, a differential nominal voltage U d,soll and a differential actual voltage U d,ist are delivered as input signals. From this, a battery nominal current I bat,soll is formed.

[0014] The DC / AC converter DCACW and the asynchronous motor ASM are regulated by means of the asynchronous motor torque regulator M asm -Regler. To this end, the asynchronous motor torque regulator M asm -Regler is delivered with a torque nominal value M soll as input signal.

[0015] The torque nominal value M soll is formed from a pre-control torque M ff and from a pre-given torque M tf , which are delivered as respective input signals to the minimum formation unit MIN.

[0016] Here, the pre-control torque M ff is calculated by means of the pre-control torque calculation unit VMB, while the pre-given torque M tf is requested or released by the traction vehicle driver or the rail vehicle driver at a certain point in time.

[0017] The following condition is ensured by means of the minimum formation unit MIN:

[0018] M soll ≤ M tf

[0019] To calculate the pre-control torque M ff , the battery ideal current I bat,ideal is delivered to the pre-control torque calculation unit VMB.

[0020] The pre-control torque M ff is calculated here such that the battery actual current I bat,ist corresponds as exactly as possible to the pre-given battery ideal current I bat,ideal :

[0021] I bat,ist = I bat,ideal

[0022] Ideal battery current I bat,ideal Here, it is set or defined so that the predetermined maximum battery current is not exceeded during the driving process of the traction vehicle. This is necessary to avoid the battery BAT from being shut down safely due to excessive current or excessive power consumption.

[0023] In addition, the ideal battery current I bat,ideal Defined as the ideal battery current, this allows the required traction torque of the asynchronous motor ASM to be quickly built up. This is necessary to minimize restrictions when traction is applied to the vehicle.

[0024] Pre-control torque M ff The calculation is done in the classic way with the aid of the torque rating M soll Actual current to battery I bat,ist The dynamic (transformed) transfer function H sys (z) proceed.

[0025] The transfer function H sys (z) Invert to obtain the inverse transfer function H sys -1 (z).

[0026] Inverse transfer function H sys -1 (z) multiplied by the (transformed) ideal battery current I bat,ideal (z), to obtain the pre-control torque M ff (z). This will be explained further below.

[0027] The schematic diagram shown here ensures that the battery BAT is used in an electrically ideal manner during driving without violating a predefined current limit value of the battery BAT.

[0028] This makes it possible for the corresponding drive components of the tractor vehicle to be operated in an energy-optimized manner under the driving pre-set values ​​of the tractor vehicle driver. As a result, the planned tractive force of the tractor vehicle is available to the tractor vehicle driver at any time with the greatest possible range.

[0029] Figure 4 refer to Figure 3 The towing vehicle driver's set torque M is shown tf The desired ideal battery current I bat,ideal comparison.

[0030] At time t=3.008, for example, a predetermined torque M is requested or released by the towing vehicle. tf .

[0031] Then at time t=3.016, the ideal battery current Ibat,ideal The ideal and desired current output is generated from the battery BAT in the form of. bat,ideal The expected course of is linear and has no oscillations.

[0032] In this example, the following relationship applies exemplarily to the ideal battery current I bat,ideal Transformation of (z): I bat,ideal (z)=850z / (z 2 -1,15z+0,15)

[0033] This is a mathematical description of the changes shown.

[0034] Figure 5 Shown from Figure 3 Signal flow diagram of the controlled system of the battery drive system.

[0035] As mentioned above Figure 3 Described in the torque rating M soll By the pre-control torque M ff and the towing vehicle driver's pre-set torque M tf The torque setpoint value is formed and reaches the asynchronous motor torque regulator M as an input signal asm -Regler.

[0036] Asynchronous motor torque regulator M asm -Regulator regulates the torque of the asynchronous motor ASM via the DC / AC converter DCACW. This generates the motor current I mot .

[0037] Motor current I mot Arrives at a first input terminal of the first difference forming unit DIF1.

[0038] Intermediate circuit DC current I dcdc Arrives at a second input terminal of the first difference forming unit DIF1.

[0039] The difference forming unit DIF1 forms a differential current I from these currents. d :

[0040] I d =I mot -I dcdc .

[0041] Differential current I d As input signal to the intermediate circuit voltage regulator U zk -Regler and is converted into a differential actual voltage U d,ist .

[0042] Differential actual voltage Ud,ist Arrives at a first input terminal of the second difference forming unit DIF2.

[0043] Differential actual voltage U d,ist The setpoint value generator SWB receives as input signal the setpoint value generator which is based on the differential actual voltage U d,ist Predetermined differential rated voltage U d,soll .

[0044] Differential rated voltage U d,soll The output signal of the setpoint value generator SWB arrives at a second input of the second difference forming unit DIF2.

[0045] The second difference forming unit DIF2 forms a differential voltage U from the supplied voltage d,delta :

[0046] U d,delta =U d,soll -U d,ist .

[0047] For the differential voltage U d,delta , determine the associated intermediate circuit battery rated current I bat,soll,zk .

[0048] Intermediate circuit battery rated current I bat,soll,zk As input signal to the battery current regulator I bat -Regler, based on which the battery current regulator predetermines the actual battery current I bat,ist and the intermediate circuit DC current I dcdc .

[0049] As shown above:

[0050] I bat,ist =I bat,ideal

[0051] as well as

[0052] I bat (z)=H svs (z)M soll (z)

[0053] The submodel used to model the shown signal flow graph is designed to be linear.

[0054] The pilot control torque M required for this ff Now the calculation is as follows:

[0055] M ff (z)=H sys -1 (z)I bat,ideal (z) / z

[0056] Figure 3 The transfer function H of a typical system model sys (z) is not minimum phase, so the transfer function cannot be stably inverted. This is evident from the presence of the zero znmp outside the unit circle.

[0057] The precontrol torque thus calculated would therefore become infinite and therefore cannot be used.

[0058] from Figure 3 Let’s look at the transfer function H. sys An exemplary actual numerical example of (z) may be as follows:

[0059] H sys (z)=(0.030226(z+1.017)(z+0.4928)) / ((z-0.2636)(z 2 +1.761z+0.7783))

[0060] The zero point znmp = -1.017.

[0061] This zero point znmp lies outside the unit circle, so that oscillations are to be expected in the battery current and the pilot control torque must increase beyond all limits.

[0062] In order to avoid this problem, in practice the dynamic transfer function H is not set by the traction vehicle manufacturers. sys (z) is inverted as a whole, but only its static part is inverted. This is done by the following approximation:

[0063] H sys praxis (z)=H sys (z=1)

[0064] H sys (z=1) is a scalar that can be inverted without any problem.

[0065] Figure 6 refer to Figures 3 to 5 The towing vehicle driver's set torque M is shown tf , pre-control torque M ff And in practice the battery current I bat Comparison of the changing process.

[0066] At time t=3, for example, the towing vehicle driver requests or releases a predetermined torque M tf .

[0067] At the time point t=3.017, a delayed pre-control torque M is formed in practice. ff , the pre-control torque has steps.

[0068] At time t=3.017, the battery current I bat The desired (ideal) battery nominal current I is shown for this purpose. bat,soll , its variation process is linear and without oscillation.

[0069] At time t=3.017, the battery current I bat The actual battery current I corresponding to practice is shown bat,praxis , its variation process is linear but contains oscillations.

[0070] These oscillations are disruptive since, as mentioned above, the battery system may shut down due to these oscillations.

[0071] The above-described actual process predetermines a slow increase in the battery current, but at the expense of traction and the consequences for the design of the driving cycle, driving plan, and drive components. Summary of the Invention

[0072] The object of the present invention is therefore to specify a method for presetting a torque pilot control M for a traction vehicle having a traction battery. ff A method is provided by which the current consumption of a battery is optimally utilized during a starting process without a predefined current limit value of the battery being violated in the process.

[0073] This object is achieved by the method according to the invention for controlling the current output of a battery. Advantageous developments are described in various embodiments.

[0074] In summary, the method according to the invention is based on the fact that H sys The unstable system part of the inverse transfer function of (z) is processed so as to prevent oscillations and unstable behavior in the battery current.

[0075] To this end, the ideal battery current is manipulated as follows to calculate the pre-control torque M ff :

[0076] M ff (z)=H sys -1 (z)I bat,neu (z) / z

[0077] M ff (z)=I bat,neu (z) / (H sys (z)z)

[0078] in

[0079] I bat,neu (z)=I bat,ideal (z)-Ibat,ideal (znmp)

[0080] From this we can conclude that:

[0081] M ff (z)=(I bat,ideal (z)-I bat,ideal (znmp)) / (H sys (z)z)

[0082] By the ideal battery current I bat,ideal When z=znmp is selected to achieve pole / zero cancellation.

[0083] In view of the above figures, oscillations are reduced or prevented through pole / zero cancellation.

[0084] In the present invention, the desired battery current ideal value I bat,ideal The z-transform of (z) adds a constant that depends on the zero point.

[0085] The value of the constant is expressed as I bat,ideal (znmp), where z = znmp represents the transfer function H sys (z) is the zero position outside the unit circle.

[0086] Add a constant I in the z domain bat,ideal (znmp) affects only the first value of the associated sequence in the time domain.

[0087] The original ideal signal of battery current I bat,ideal (z) only needs to be changed first, otherwise the following relationship applies:

[0088] For all n>0, I bat,neu [n]=I bat,ideal [n] BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 The towing vehicle driver's set torque M is shown tf and battery current I bat,neu comparison.

[0090] Figure 2 The following figure shows the predefined torque M of the towing vehicle driver based on the present invention. tf , pre-control torque M ff and battery current I bat Comparison of the changing process.

[0091] Figure 3 A controlled drive of such a rail vehicle according to the prior art is shown in a simplified schematic diagram.

[0092] Figure 4 refer to Figure 3 The pre-given torque M tf of the traction vehicle driver is shown in comparison with the desired battery ideal current I bat,ideal .

[0093] Figure 5 The signal flow diagram of the controlled system from the battery drive system Figure 3 is shown.

[0094] Figure 6 Reference is made to Figures 3 to 5 The pre-given torque M tf of the traction vehicle driver, the pre-control torque M ff and the course of the battery current I bat in practice are shown in comparison. DETAILED DESCRIPTION

[0095] Figure 1 Reference is made to Figure 3 The pre-given torque M tf of the traction vehicle driver is shown in comparison with the battery current I bat,neu , which is manipulated by means of the invention to be drawn from the battery bat,neu .

[0096] At the time point t = 3.008, the pre-given torque M tf is requested or released by the traction vehicle driver, exemplarily.

[0097] Reference is made to Figure 2 , at the time point t = 3.008, a current output is generated from the battery BAT in the form of the battery current I bat,neu .

[0098] The desired course of the battery current I bat,neu no longer has oscillations and overshoots.

[0099] Reference is made to Figure 4 , at the time point t = 3.016, the first value of the ideal battery current is initially I bat,ideal [n] = 0.

[0100] After the manipulation according to the invention has been completed, at the time point t = 3.016 s, the value of the new ideal battery current I bat,ideal [n] = 367.3 A.

[0101] Thus, taking into account the principle according to the invention, the z-transform of the new course of the new battery current I bat，neu (z) is multiplied by the inverse transfer function H sys -1 (z) of the transfer function:

[0102] M ff(z) = H sys -1 (z) = H bat,neu (z) = H

[0103] from which a torque pre-given value pre-control M ff (z) is generated, whose value no longer oscillates or whose value remains within a pre-given range.

[0104] Figure 2 The comparison of the change processes of the pre-given torque M tf , the pre-control torque M ff and the battery current I bat of a towing vehicle driver based on the application is shown.

[0105] At the time point t = 3, the pre-given torque M tf is requested or released by the towing vehicle driver, exemplarily.

[0106] At the time point t = 3.008, a pre-control torque M ff is formed with a delay, which has a step.

[0107] At the time point t = 3.017, the desired (ideal) battery current I bat,soll is shown when the battery current I bat is displayed, whose change process is linear and without oscillations.

[0108] At the time point t = 3.008, the battery current I bat,neu is shown when the battery current I bat is displayed, which is formed according to the application, whose change process is linear and without oscillations.

[0109] The change process of the battery current I bat,neu is very close to the desired battery current I bat,soll .

[0110] The application makes it possible to generate a torque rating M soll , in which the desired battery current is taken from the battery according to the power requirement of the towing vehicle driver without violating the limiting pre-given value.

[0111] The application makes it possible to ideally adjust the battery current without causing overshoots or oscillations of the battery current in the process.

[0112] The method according to the application is based on the fact that unstable system parts are not excited by new rating signal change processes.

[0113] As described above:

[0114] M ff (z) = H sys-1 (z)I bat,neu (z) / z

[0115] M ff (z)=I bat,ideal (z)-I bat,ideal (znmp) / (z H sys (z))

[0116] For z->znmp, pole / zero cancellation is observed. This ensures that I bat,neu The calculation sequence no longer oscillates beyond predefined limits.

[0117] This can also be understood from a specific numerical example based on the above sys (z) Statement:

[0118]

[0119] It can be seen that the pole zp=-1.017 that originally existed outside the unit circle no longer exists after the transformation.

Claims

1. A method for controlling the current output of a battery, wherein the battery is used as a traction battery for driving a rail vehicle, -The actual battery current I bat,ist Through the rectifier as the intermediate circuit DC current I dcdc Reaching the intermediate circuit, - wherein a differential actual voltage U is applied to the intermediate circuit d,ist , - wherein the intermediate circuit DC current I dcdc As the motor current I mot From the intermediate circuit to the DC / AC converter, the DC / AC converter converts the motor current I mot Converted into three-phase AC current, wherein the three-phase alternating current is supplied to an asynchronous electric motor serving as a drive for the rail vehicle, - wherein the asynchronous motor and the DC / AC converter are regulated by a torque regulator, - The torque regulator is used to adjust the torque setpoint value M soll , the motor current I is adjusted by the torque setpoint mot , - where the intermediate circuit voltage regulator is based on the differential rated voltage U d,soll and based on the differential actual voltage U d,ist To determine the battery rated current I bat,soll , based on the intermediate circuit DC current I dcdc To adjust to the battery rated current, wherein the DC / DC converter is regulated by a battery current regulator, wherein the battery current regulator is based on the battery rated current I bat,soll And based on the actual battery current I bat,ist To adjust the intermediate circuit DC current I dcdc , - Among them, considering the relationship M tf >max(M ff ) under the condition of pre-control torque M ff and the preset torque M tf Forming the torque rating M soll , - Based on the actual battery current I bat,ist The pre-control torque M is formed ff , until the actual battery current I bat,ist Corresponding to the ideal battery current I bat,ideal until, -where by means of the transfer function H sys (z) Calculate the pre-control torque M ff , the transfer function converts the torque rating M soll The actual battery current I is mapped as follows: bat,ist : I bat (z)=H sys (z)M soll (z), It is characterized in that - Given the transfer function H sys (z) Determine the zero point z=znmp outside the unit circle, - the pre-control torque M ff The calculation is performed as follows: M ff (z)=I bat,neu (z) / (H sys (z)z) in: I bat,neu (z)=I bat,ideal (z)-I bat,ideal (z=znmp) as well as: For all n>0, I bat，neu [n]=I bat，ideal [n], Thus, z=znmp is the ideal current I of the battery. bat,ideal Pole-zero cancellation is achieved when .

2. The method according to claim 1, wherein An inverter is used as a DC / AC converter.

3. The method according to claim 1, wherein The actual voltage U of the intermediate circuit d,ist applied to the capacitor.

4. The method according to claim 1, wherein The predetermined torque M tf Requested or released by the towing vehicle driver.

5. The method according to claim 1, wherein The ideal battery current I bat,ideal is set or defined such that a predefined maximum battery current is not exceeded during travel of the rail vehicle.

6. The method according to claim 1, wherein The ideal battery current I bat,ideal is set or defined such that the required traction torque of the asynchronous motor can be built up more quickly.

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