Methods and arrangements for suppressing the influence of periodic disturbances on parameters of a traction system

Abstract

A method for suppressing the influence of a first periodic disturbance (d) on a parameter (y) in a traction system on a railway vehicle includes the following steps: measuring the parameter; applying an adaptive algorithm (K) to the measurement results of the parameter to calculate a second periodic disturbance (u), which, when applied to the system, will minimize the total influence of the first and second periodic disturbances on the parameter; and applying the second periodic disturbance (u) to influence the parameter (y).

Description

Technical Field

[0001] The present invention relates to a method for suppressing the influence of a first periodic disturbance on parameters in a traction system on a railway vehicle, and an arrangement for such suppression.

[0002] The system can be of any type, although an electrical system is presented as an example.

[0003] "Periodic perturbation" is interpreted as a sinusoidal perturbation or a perturbation that can be approximated by the sum of a finite number of sinusoidal influences.

[0004] In traction systems with single-phase AC power, a first periodic disturbance will occur, manifested as a second harmonic component of the voltage in the DC intermediate link connected to the output of the rectifier on the railway vehicle. This means the frequency of the periodic disturbance is twice the frequency of the periodic single-phase AC power supply voltage. This second harmonic then directly affects the output voltage of the inverter on the railway vehicle, which supplies power to the traction motors and auxiliary loads such as fans, pumps, and compressors. This second harmonic must be suppressed to ensure that electrical pulsations do not lead to motor torque pulsations, which not only damage the mechanical system but also generate annoying noise and additional motor power losses. This problem is typically solved by installing physical second harmonic filters in the DC intermediate link. These filters are then tuned to effectively shunt the oscillating power component, thus keeping the voltage on the DC intermediate link constant. However, second harmonic filters increase the system's weight, space, and power loss. Therefore, it is desirable to provide a method that can remove these filters and, instead, suppress, for example, second harmonic torque oscillations through improved control of the converter that acts as an inverter when supplying power to the motor and / or auxiliary load and as a rectifier when supplying power in the opposite direction. Background Technology

[0005] Several types of methods have been proposed in the literature to suppress the effects of the first periodic disturbance in the form of second harmonic DC intermediate link voltage oscillation. These include feedback methods that rely on high-bandwidth closed-loop current or torque control, feedforward methods that adjust the inverter modulation index and are only applicable to the so-called voltage control range, and feedforward methods that adjust the inverter output frequency in principle, which operate in both the voltage control range and the field weakening range.

[0006] However, none of these methods can optimize suppression at all operation points. Summary of the Invention

[0007] The object of the present invention is to provide methods and arrangements that are improved upon compared with known methods and arrangements of this kind by solving the problems discussed above.

[0008] Therefore, by measuring the problematic parameter, applying an adaptive algorithm to the measurement result to calculate a second periodic disturbance that minimizes the total impact of the first and second periodic disturbances on the parameter when applied to the system, and applying the second periodic disturbance to affect the parameter, a type of adaptive feedforward compensation technique is provided, in which performance is optimized under all operating conditions. Moreover, since the proposed suppression algorithm automatically adjusts parameters to optimize disturbance suppression, it can be directly added to existing controls. That is, no modification is needed to other functions already designed for the same task. Thus, instead of removing the first periodic disturbance in any way, the second periodic disturbance is applied to suppress the effect of the first periodic disturbance on the problematic parameter.

[0009] According to one embodiment of the invention, the method includes another step d) performed prior to step b) to measure the first periodic disturbance, and in step b), the result of the measurement of the first periodic disturbance is used when applying the adaptive algorithm to the measurement result of the parameter. By measuring the first periodic disturbance, the suppression can be further improved to respond more quickly to changes in the operating conditions of the system.

[0010] According to another embodiment of the present invention, the second periodic disturbance with the same frequency as the first periodic disturbance is calculated in step b) and applied in step c) to affect the parameter, which will effectively suppress the influence of the first periodic disturbance on the parameter.

[0011] According to another embodiment of the invention, the method includes another step e), performed after step d), determining the phase shift between the first periodic perturbation and the parameter, and in step b), the determined value of the phase shift is used when applying the adaptive algorithm to the measurement results of the parameter. It can be seen that the phase shift between the first periodic perturbation and the parameter applied to the adaptive algorithm enables effective suppression of the influence of the first periodic perturbation on the parameter.

[0012] According to another embodiment of the invention, when the adaptive algorithm is applied to the measurement results of the parameter in step b), the value of the amplitude of the first periodic perturbation measured in step d) is also used. This is preferred because, for a linear system, the required suppression effect should be proportional to the amplitude of the perturbation.

[0013] According to another embodiment of the invention, what is suppressed is precisely the effect of a first periodic disturbance, in the form of an AC component in the electrical system, on the parameters of the system. According to another embodiment of the invention, the method can then be applied to a system having a single-phase AC power supply that causes the first periodic disturbance, preferably in the form of a second harmonic of the voltage on the DC intermediate link of the electrical system, preferably having a frequency twice the frequency of the single-phase AC power supply. Such a method would make it possible to eliminate second harmonic filters in the traction system of railway vehicles, and thus save cost, weight, space, and power losses. The method can also be used to improve second harmonic torque suppression, for example, using poorly tuned physical filters, or to ensure good torque disturbance suppression even with aged filter components.

[0014] According to another embodiment of the invention, the parameter measured in step a) is a mechanical parameter, such as the torque generated by an electric motor powered by an inverter connected to the DC intermediate link for propelling the vehicle. The method will then remove torque pulsations applied to the axles and motor components.

[0015] According to another embodiment of the invention, the parameter measured in step a) is an electrical parameter, such as the output current of the inverter connected to the DC intermediate link for supplying power to an electric motor used for vehicle propulsion or auxiliary loads in the vehicle (such as fans, pumps, compressors, etc.).

[0016] The object of this invention relates to providing an arrangement obtained according to the arrangement described in the appended independent arrangement claims. The advantages of such an arrangement, and the embodiments defined in the dependent arrangement claims, are clearly apparent from the above discussion of the method according to the invention.

[0017] The present invention also relates to computer programs, computer program products, electronic control units, and railway vehicles as described in the appended claims thereto.

[0018] Other advantages and advantageous features of the invention will become apparent from the following description. Attached Figure Description

[0019] The following is a detailed description of embodiments of the invention cited by way of example, with reference to the accompanying drawings.

[0020] In the attached diagram:

[0021] Figure 1 The diagram schematically illustrates a system for supplying power from a single-phase AC power source to motors and auxiliary loads on a rail vehicle. The figure is used to explain a method according to an embodiment of the invention.

[0022] Figure 2 The principles upon which this invention is based are illustrated.

[0023] Figure 3 The illustration schematically shows a portion of a method according to an embodiment of the present invention.

[0024] Figure 4 and 5 The graph shows the simulation results of the application of the method according to the invention to the DC intermediate link voltage and the torque generated by the electric motor of the railway vehicle, and

[0025] Figure 6 This is a schematic diagram illustrating an electronic control unit for implementing the method according to the present invention. Detailed Implementation

[0026] As described in the introduction, an interesting embodiment of the invention is the use of a method and its arrangement to suppress the effects of periodic disturbances in a traction system with a single-phase AC power supply, and reference will now be made first to... Figure 1 This embodiment will now be disclosed. Figure 1 The diagram schematically illustrates how a railway vehicle 1 is connected to a single-phase AC power supply line 2, which can, for example, deliver alternating voltages of 15 kV and 16 2 / 3 Hz (Sweden) and 25 kV and 50 Hz (Denmark). Other voltage and frequency levels from such a single-phase alternating AC power supply are, of course, conceivable. The vehicle has a transformer 3 for converting the voltage from the power supply line 2 to a suitable level. The secondary winding of the transformer is connected to a converter 4, thereby rectifying the voltage and enabling control of the power flow between the power supply line and the power consumers on the vehicle. The electrical power P(t) converted from the AC side to the DC side of the converter is thus calculated using the following formula.

[0027]

[0028] As can be seen from the formula, the converted power contains an AC component with a frequency (2ω) up to twice the frequency of the AC side of converter 4, and therefore has a second harmonic. If no measures are taken to suppress the effect of such a second harmonic on this power, it could cause severe power ripples in the motors used for vehicle propulsion and in auxiliary loads on the vehicle. This shows how the DC intermediate link 5 is connected to converter 6, which acts as an inverter when supplying power to the vehicle from AC power line 2, and as a rectifier when supplying power in the opposite direction (such as during vehicle braking). The output of converter 6 is connected to motors 7 and 8 for vehicle propulsion. Another converter 6' is connected in parallel with converter 6 and is configured to provide electrical power from AC power line 2 to auxiliary loads 9 (such as fans, pumps, compressors, etc.).

[0029] The figure illustrates how an LC filter 10 in the form of a so-called second harmonic link can be applied to an electrical system to suppress second harmonics. However, such a filter increases the cost, weight, space, and power consumption of the system. The purpose of this invention is to make such a filter redundant.

[0030] Figure 2 This illustrates how this objective can be achieved by applying the method according to the invention. The figure shows how a first periodic disturbance d, in the form of the second harmonic, affects the traction system G. A parameter y affected by the first periodic disturbance (e.g., torque generated by motors 7 and 8, or current at the output of converter 6) is measured by component 11, and an adaptive algorithm K is applied by control unit 12 to the measurement result of parameter y to calculate a second periodic disturbance u, which, when applied to the system, minimizes the total impact of the first periodic disturbance d and the second periodic disturbance u on parameter y. This calculated second periodic disturbance is then applied to affect parameter y. This effectively suppresses the influence of the first periodic disturbance d (here, the second harmonic) on parameter y. Furthermore, by measuring the first periodic disturbance d by component 20 and using the result of this measurement when applying the adaptive algorithm to the measurement result of parameter y, the response to rapid changes in d is improved; however, this method also performs well in some applications without measuring the first periodic disturbance.

[0031] The perturbation d will result in a periodic (sine) component y on the parameter y. d (t), which is represented as follows: The subscript d is added to indicate that it is generated by the perturbation d(t). Therefore, u(t), which will be applied to the system to eliminate the oscillations yd(t) caused by the perturbation d, must be calculated by applying an adaptive algorithm to the measurement of y(t). The second periodic perturbation used to achieve this can be written as...

[0032]

[0033] Where amplitude a u and phase Therefore, it is a design variable that needs to be updated with the operating point. If the disturbance d is measured, it can be used.

[0034] a u =k u a d (4)

[0035]

[0036] Where a d and It represents the amplitude and phase of the disturbance, and k u and These are new design variables. The task of the adaptive algorithm is to adjust the magnitude a of the added input component u(t) in equation (3). u and phase This is to eliminate the total output component of y caused by u(t) and d(t) applied to the system. The algorithm's inputs are the phase angles of the (sinusoidal) perturbation y and the (sinusoidal) perturbation d on the output y. and The difference was calculated, and three design parameters α and K were added. i and K i2 The latter two design parameters control the convergence rate; however, parameter α has been added to maximize the attraction domain.

[0037] Figure 3 This demonstrates how to implement the compensation parameter k. u and The adjustment. Note that only the arguments of the disturbance and the total output, not the amplitude, are used. Figure 3 The input to the adaptive algorithm in [the context].

[0038] Simulations of traction systems without second harmonic filters have been performed both with and without using the arrangement of the invention to apply the method according to the invention. The results of these simulations are shown in... Figure 4 and Figure 5 middle. Figure 4 The oscillation amplitude of the second harmonic component (100Hz) of the intermediate DC link voltage U is shown in relation to the stator frequency of the railway vehicle's motor. Figure 5 The oscillation amplitude and frequency of the second harmonic component (100Hz) of the torque M generated by the motor are shown. wo does not use the present invention, while wi uses the adaptive algorithm of the present invention. It can be seen that the method according to the present invention is very effective in eliminating the second harmonic of the motor torque. From Figure 4 It can be seen that the method according to the present invention does indeed affect the oscillation amplitude of the DC voltage, which means that the oscillation of torque contributes to further increasing the oscillation of voltage without the method according to the present invention.

[0039] Computer program code for implementing the method according to the invention is advantageously contained in a computer program that can be read into the memory of a computer, such as the memory of an electronic control unit of a rail vehicle. Such a computer program is advantageously configured as a computer program product comprising a data storage medium readable by a computer and having the computer program stored thereon. Figure 6An electronic control unit 12 is shown schematically, comprising an execution device 13, such as a central processing unit (CPU) for executing computer software. The execution device 13 communicates with a memory 14, such as RAM, via a data bus 15. The control unit 12 also includes a non-volatile data storage medium 16, such as flash memory or a memory of the ROM, PROM, EPROM, or EEPROM type. The execution device 13 communicates with the data storage medium 16 via the data bus 15. The computer program contains computer program code for implementing the method according to the invention.

[0040] Of course, the present invention is by no means limited to the embodiments described above, because it will be apparent to those skilled in the art that many possibilities may be made to modify the embodiments without departing from the scope of the invention as defined by the appended claims.

[0041] The parameter affected by the first periodic disturbance can be, but does not have to be, an electrical parameter. For example, it can be torque as described above. Furthermore, it can be unrelated to the system's power supply. For instance, the parameter could be the speed of a railway vehicle. The speed value can be obtained by measuring the number of rotations of the vehicle's axles using a mechanically flawed component. By adding a second periodic disturbance, the correct speed value can be obtained.

Claims

1. A method for performing in a traction system on a railway vehicle (1) to suppress the influence of a first periodic disturbance d on a parameter y in the traction system on the railway vehicle (1), wherein the influence of the first periodic disturbance d, which is of the form of an AC component in the electrical system of the traction system, on the parameter y in the electrical system is to be suppressed. Its features are, The method is applied to a system having a single-phase AC power supply (2) that causes the first periodic disturbance d, and the method includes the following steps: a) Measure the parameter y, wherein the parameter y is a mechanical parameter and the mechanical parameter includes the torque generated by an electric motor (7, 8) for propulsion of the vehicle, powered by an inverter (6) connected to a DC intermediate link (5); b) Applying the adaptive algorithm K to the measurement results of the parameter y to calculate a second periodic disturbance u, which, when applied to the traction system, minimizes the total impact of the first and second periodic disturbances on the parameter. c) Apply the second periodic perturbation u to affect the parameter y.

2. The method according to claim 1, characterized in that, The method includes another step d), which is performed before step b), for measuring the first periodic perturbation d, and in step b), the result of the measurement of the first periodic perturbation is used when the adaptive algorithm K is applied to the result of the measurement of the parameter y.

3. The method according to claim 1 or 2, characterized in that, In step b), the second periodic perturbation u is calculated, and in step c), the second periodic perturbation u is applied to affect the parameter y, wherein the frequency of the second periodic perturbation u is the same as the frequency of the first periodic perturbation d.

4. The method according to claim 2, characterized in that, The method includes another step e), which is performed after step d), for determining the phase shift between the first periodic perturbation d and the parameter y, and the value of the determined phase shift is used when the adaptive algorithm K is applied to the result of the measurement of the parameter in step b).

5. The method according to claim 4, characterized in that, When the adaptive algorithm K is applied to the measurement result of the parameter y in step b), the amplitude a of the first periodic perturbation d measured in step d) is also used. d The value of .

6. The method according to claim 1, characterized in that, The first periodic disturbance d takes the form of the second harmonic of the voltage on the DC intermediate link (5) of the electrical system.

7. The method according to claim 1, characterized in that, The frequency of the first periodic disturbance d is twice the frequency of the single-phase AC power supply.

8. A device in a traction system of a railway vehicle (1) for suppressing the influence of a first periodic disturbance d on a parameter y in the traction system of the railway vehicle (1), wherein the disturbance d is of the form of an AC component in an electrical system of the traction system on the parameter y in the electrical system. Its features are, The device is applied to a system having a single-phase AC power supply (2) that causes the first periodic disturbance d, and the device includes • Configure a component (11) for measuring the parameter y, wherein the parameter y is a mechanical parameter, and the mechanical parameter includes the torque generated by an electric motor (7, 8) for propulsion of the vehicle, powered by an inverter (6) connected to a DC intermediate link (5), and • Configure a control unit (12) for receiving information about the parameters from the component. The control unit is configured to apply an adaptive algorithm K to the measurement result of the parameter y in order to calculate a second periodic disturbance u, and to apply the second periodic disturbance u to affect the parameter y, wherein the second periodic disturbance u, when applied to the traction system, minimizes the total impact of the first periodic disturbance and the second periodic disturbance on the parameter.

9. The apparatus according to claim 8, characterized in that, The apparatus further includes a component (20) configured to measure the first periodic disturbance d, and the control unit (12) is configured to use the result of the measurement of the first periodic disturbance d when applying the adaptive algorithm K to the result of the measurement of the parameter y.

10. A computer program product comprising a computer program that, when executed by a computer, causes the computer to perform the method according to any one of claims 1-7.

11. A non-volatile data storage medium, the non-volatile data storage medium being readable by a computer and storing a computer program thereon, the computer program being configured to cause the computer to perform the method according to any one of claims 1-7 when the computer executes the computer program.

12. An electronic control unit comprising an actuation device (13), a memory (14) connected to the actuation device, and a non-volatile data storage medium (16) according to claim 11 connected to the actuation device (13).

13. A railway vehicle, characterized in that, The railway vehicle is equipped with the device according to any one of claims 8 or 9 or the electronic control unit according to claim 12.

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