JP6272215B2 - Power converter and control method of power converter - Google Patents

Description

  The present invention relates to a power converter that controls an induction motor to control wheel rotation, and a control method for the power converter.

  2. Description of the Related Art Conventionally, in a railway vehicle, a method of controlling a plurality of induction motors with a single power conversion device using a power conversion device capable of outputting a variable voltage and a variable frequency has become common. In particular, in a case where a control response is required, a vector control method is used in which the motor current is decomposed into an excitation component and a torque component and controlled independently. In the vector control method, the slip frequency command is calculated from the excitation component command and the torque component command, and the output frequency command of the power converter is calculated by adding / subtracting the slip frequency command to / from the rotation frequency of the induction motor.

  In addition, the wheel connected to the induction motor cannot secure the adhesive force between the road surface and the wheel due to changes in the friction coefficient of the road surface due to rain, road surface (rail) icing, falling objects, etc. It is widely known that a phenomenon of sliding occurs.

  Therefore, as a technique for detecting the sliding phenomenon of the wheel and suppressing the promotion, the speed difference of the induction motor rotation frequency is detected as the amount of sliding, and the time change rate is added to the output frequency component of the power converter to suppress the promotion of the sliding. A technique for promoting re-adhesion between a road surface (rail) and wheels has been introduced (see, for example, Patent Document 1).

  In addition, a technique for detecting that a driving wheel has slid based on the speed of an AC motor for driving a vehicle and detecting a temporal change in acceleration as a sliding amount is also introduced (for example, see Patent Document 2).

  Furthermore, a technique for suppressing and re-adhering the sliding by reducing the torque component command amount described above has been introduced (see, for example, Patent Document 3).

JP-A-9-308006 JP 2008-148445 A JP 2009-112132 A

  However, in actual fields, it has been confirmed that the wheels suddenly become stuck and run, or if they occur continuously, etc., sliding under various conditions has been confirmed, but it is controlled by one power converter. The wheels connected to the plurality of induction motors do not always slide in the same manner, and the degree of sliding varies depending on the difference in front wheels, rear wheels, and the like. For this reason, in the above-described prior art, the motor output unbalanced state in which the positive output motor and the negative output motor are mixed between the respective axles between the detection of the sliding of the wheel and the re-adhesion with the road surface (rail). May occur. Furthermore, if it takes time until the re-adhesion, there is a risk that the wheel and the road surface (rail) are likely to wear during this time.

  If the friction coefficient of the road surface is extremely close to zero, even if the torque output of the induction motor is brought close to zero as in Patent Document 3, the sliding of the wheel is not eliminated, and the re-adhesion takes time. Is required.

  The present invention has been made in view of such circumstances, and a positive output motor and a negative output motor are mixed in each motor that drives each axle, which can occur during re-adhesion control between a road surface (rail) and a wheel. An object of the present invention is to provide a power conversion device and a method for controlling the power conversion device that can detect with high accuracy that a motor output unbalanced state has occurred.

  To achieve this object, the present invention provides a plurality of electric motors for driving a vehicle, a plurality of axles that are driven by the respective electric motors to support wheels, and a rotation frequency detecting means for detecting a rotation frequency of each of the axles. And control means for controlling the current of each electric motor based on the rotation frequency output from the rotation frequency detection means, and the control means is an average of rotation frequencies input from the rotation frequency detection means An average value calculating means for calculating a value; a minimum value selecting means for selecting a minimum value of the rotational frequency input from the rotational frequency detecting means; an average value input from the average value calculating means; and the plurality of electric motors. Output frequency calculation means for calculating an output frequency based on the current value of the motor, and motor output imbalance detection means for detecting output imbalance of the plurality of motors. The motor output imbalance detection means includes a subtraction means for subtracting a minimum value input from the minimum value selection means from a calculation value input from the output frequency calculation means, and a subtraction value input from the subtraction means. A power converter is provided that includes a comparison unit that performs comparison with a preset reference value and outputs a motor output imbalance detection signal based on the comparison result.

  Further, the present invention provides a plurality of electric motors, a plurality of axles driven by the respective electric motors, a rotation frequency detection means for detecting a rotation frequency of each of the axles, and a rotation output from the rotation frequency detection means. A control means for controlling the current of each electric motor based on a frequency, and a control method for a power converter, comprising: calculating an average value for calculating an average value of rotation frequencies input from the rotation frequency detection means A minimum value selection step for selecting the minimum value of the rotation frequency input from the rotation frequency detection means, the average value obtained in the average value calculation step, and the current values of the plurality of electric motors, An output frequency calculation step for calculating an output frequency; and a motor output imbalance detection step for detecting output imbalance of the plurality of motors, the motor output imbalance detection The step includes a subtraction step for subtracting the minimum value obtained in the minimum value selection step from the computation value obtained in the output frequency computation step, a subtraction value obtained in the subtraction step, and a preset reference value And a comparison step of outputting a motor output imbalance detection signal based on the comparison result, and a control method for a power converter.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the motor output imbalance state which can generate | occur | produce at the time of the re-adhesion control of a road surface (rail) and a wheel can be detected with high precision.

It is a front view showing an outline of a railcar carrying a power converter concerning Embodiment 1 of the present invention. It is a structure circuit diagram of the power converter device shown in FIG. It is a block diagram which shows the structure of the automatic control apparatus shown in FIG. It is a block diagram which shows the structure of the motor output imbalance detector shown in FIG. It is a flowchart which shows the process of the power converter device which concerns on Embodiment 1. FIG. (A) is the figure which shows the axle shaft rotation frequency signal Fr1-Fr4 at the time of sliding in Embodiment 1, the axle average frequency FrAVE, and the output frequency signal FINV of a power converter device, (b) is each electric motor in Embodiment 1. FIG. It is a figure which shows the operating characteristic figure of an output. It is a block diagram which shows the structure of the automatic control apparatus which concerns on Embodiment 2. FIG. It is a block diagram which shows the structure of the automatic control apparatus which concerns on Embodiment 3.

  Next, a power converter according to an embodiment of the present invention and a control method thereof will be described with reference to the drawings. In addition, embodiment described below is the illustration for demonstrating this invention, and this invention is not limited only to these embodiment. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

(Embodiment 1)
FIG. 1 is a front view schematically showing a railway vehicle equipped with the power conversion device according to the first embodiment, FIG. 2 is a circuit diagram of the power conversion device shown in FIG. 1, and FIG. 3 is an automatic control shown in FIG. FIG. 4 is a block diagram showing the configuration of the motor output imbalance detector shown in FIG. 3, and FIG. 5 is a flowchart showing the processing of the power conversion device according to the first embodiment.

  A railway vehicle 50 shown in FIG. 1 drives a vehicle body 10, an axle 12 disposed at a predetermined position of the vehicle body 10, wheels 12 a and 12 b disposed on both sides of the axle 12, and the axle 12. Induction motor 11, power conversion device 1 installed under the floor of vehicle body 10, speed detection sensor 3 disposed on axle 12, and pantograph installed on top of vehicle body 10 and collecting current from overhead line 13 14. Reference numerals 16a and 16b are rails on which the wheels 12a and 12b are respectively placed.

  Normally, two or four induction motors 11 are generally connected to one power converter 1, but in the first embodiment, for example, four axles 12 are respectively connected. A case where a total of four induction motors 11 are connected one by one will be described. Moreover, the speed detection sensor 3 is individually connected to each axle 12.

  The power converter 1 collects an alternating voltage via the overhead line 13 and the pantograph 14 and controls the power and frequency supplied to each induction motor 11 for driving the vehicle, thereby controlling the rotation speed of the plurality of induction motors 11. Collective control. An automatic control device 2 having a function of monitoring and comparing the rotational speed of each axle 12 using a signal received from each speed detection sensor 3 is disposed inside the power conversion device 1. This automatic control device 2 is connected to each speed detection sensor 3 by an electric wire or the like, and has a function of calculating an output frequency of the power conversion device 1 based on a signal from the speed detection sensor 3.

  As shown in FIG. 2, the power conversion apparatus 1 includes a converter unit 101 and an inverter unit 102. The AC voltage collected from the overhead line 13 via the pantograph 14 is transmitted to the converter unit 101 via the transformer 15. The converter unit 101 converts an AC voltage into a DC voltage and transmits the converted voltage to the inverter unit 102. The inverter unit 102 converts a DC voltage into an AC voltage, and performs drive control of each induction motor 11. The power converter 1 and each induction motor 11 are electrically connected by electric wires or the like, and a current flowing between them can be detected by a motor current detection sensor (not shown). And the output frequency from the power converter device 1 is controlled by the automatic controller 2.

  As shown in FIG. 3, the automatic control device 2 includes a frequency converter 20, an average value calculator 21, an output frequency calculator 22, a minimum value selector 23, and a motor output imbalance detector 30. Yes.

  The frequency converter 20 receives the pulse signals PFr1 to PFr4 output from the respective speed detection sensors 3 as input signals (FIG. 5, S101), and converts these pulse signals PFr1 to PFr4 into rotational frequency signals Fr1 to Fr4. (FIG. 5, S102). Then, these rotational frequency signals Fr <b> 1 to Fr <b> 4 are output to the average value calculator 21 and the minimum value selector 23.

  The average value calculator 21 uses the rotation frequency signals Fr1 to Fr4 of the four axles 12 output from the frequency converter 20 as input values, and based on the rotation frequency signals Fr1 to Fr4, the average value of the rotation frequency And the average frequency signal FrAVE is output (S103 in FIG. 5). This average frequency signal FrAVE is input to the output frequency calculator 22.

  Based on the input average frequency signal FrAVE and a motor current detection value input from a motor current detection sensor (not shown), the output frequency calculator 22 decomposes the motor current into a torque component and an excitation component independently. The output frequency signal FINV is calculated and output according to the vector control to be controlled (S104 in FIG. 5). This output frequency signal FINV is input to the motor output unbalance detector 30.

  The minimum value selector 23 receives the rotation frequency signals Fr1 to Fr4 output from the frequency converter 20, detects the minimum value of the rotation frequency signals Fr1 to Fr4, and outputs the rotation frequency minimum value FrMIN (FIG. 5). , S105). The rotation frequency minimum value FrMIN is input to the motor output unbalance detector 30.

  As shown in FIG. 4, the motor output imbalance detector 30 includes a subtractor 31 and a comparator 32.

  The subtractor 31 uses the output frequency signal FINV output from the output frequency calculator 22 and the rotation frequency minimum value FrMIN output from the minimum value selector 23 as input values, and the rotation frequency minimum value from the input output frequency signal FINV. FrMIN is subtracted, and this subtraction result (subtraction value) is output as a slip frequency calculation value Fs (S106 in FIG. 5).

  The comparator 32 receives the slip frequency calculation value Fs output from the subtractor 31 and the preset motor output unbalance detection reference value KFs as input signals (S107 in FIG. 5), and calculates the slip frequency calculation value Fs and the motor output. The unbalance detection reference value KFs is compared. When the slip frequency calculation value Fs exceeds the motivation output imbalance detection reference value KFs (Fs> KFs) (FIG. 5, S108: YES), the motor output unbalance detection signal OUBD is output (FIG. 5, S109). ) That is, by inputting the output frequency signal FINV and the minimum rotation frequency value FrMIN to the motor output unbalance detector 30, the motor output unbalance state is detected. When the motor output unbalance state is detected, the motor output unbalance detector 30 outputs a detection signal OUBD. On the other hand, when the slip frequency calculation value Fs is equal to or less than the motivation output imbalance detection reference value KFs (Fs ≦ KFs) (FIG. 5, S108: NO), the process returns to step S101 shown in FIG.

  When the motor output unbalance detection signal OUBD is output (FIG. 5, S109), known wheel rotation control is performed to promote re-adhesion between the rail 16a and the wheel 12a and the rail 16b and the wheel 12b.

  Next, the principle by which the motor output imbalance can be detected in the first embodiment will be described.

  According to the vector control based on the average rotation frequency value of the axle, the relationship between the output frequency of the power conversion device during braking and the average rotation frequency value of the axle is “output frequency of power conversion device <average rotation frequency value of axle” It becomes. The slip frequency of the induction motor is obtained by subtracting the average rotational frequency of the axle from the output frequency of the power converter, and the slip frequency is always a negative value when the wheel is not sliding. Further, the absolute value of the slip frequency increases as the motor output increases.

  Here, considering the case where different degrees of gliding occur due to differences in road surface (rail) conditions for all four axles, the rotational frequencies of all four axles vary, and the rotational frequency and rotation of each axle are different. A difference occurs between the frequency average value. At this time, even if “the output frequency of the power conversion device <the average rotation frequency of the axle” is established in the vector control, depending on the degree of sliding, “the output frequency of the power conversion device ≧ the minimum in all four axles” "Rotational frequency" is established. This shows a state where the induction converter that performs brake output and the induction motor that outputs power running are mixed in each induction machine, although the power converter performs the brake operation batch control for the induction motor. Yes. In addition, when the all induction motor outputs a brake even during sliding, “output frequency of power conversion device <minimum rotation frequency among all four axes” is established.

  In the processing in the motor output unbalance detector 30, during the regenerative operation in the normal state, the slip frequency calculation value Fs is always a negative value, but in the current unbalance abnormality occurrence state, a positive value is output. In order to monitor the state where the slip frequency calculation value Fs is a positive value, for example, a value near “0 (zero)” is selected as the motor output unbalance detection reference value KFs. However, it is not necessary to limit to a value in the vicinity of “0 (zero)” in order to provide a detection margin.

  From the above, by constantly monitoring the relationship between the output frequency of the power converter and the minimum rotation frequency in all four axles, it is possible to detect the motor output imbalance between the axles.

  The signal input to the output frequency calculator 22 may be, for example, the maximum value or the minimum value of the frequency signals Fr1 to Fr4 other than the average frequency signal FrAVE.

  Next, FIG. 6A shows the axle rotation frequency signals Fr1 to Fr4, the axle average frequency FrAVE, and the output frequency signal FINV of the power converter at the time of sliding in the first embodiment, and the operating characteristics of each motor output are shown in FIG. Shown in b). This operating characteristic diagram assumes a case where different degrees of sliding occur between the first to third axles and the fourth axle during braking operation among the four axles. Further, because of the braking operation, the motor output is a negative value in all the first to fourth axles.

  As shown in FIG. 7, when the sliding of each axle occurs at time 100, the axle rotation frequency signals Fr1 to Fr4 rapidly decrease. At this time, FrAVE calculated from Fr1 to Fr4 and FINV calculated based on FrAVE similarly start to change. At this time, the axle rotation frequency selected as FMIN is Fr4.

  Referring to FIG. 7, when the sliding is further promoted and time 100A is reached, the magnitude relationship between FINV and Fr4 (ie, FrMIN) is reversed. For this reason, only the induction motor connected to the fourth axle has the same behavior as that in the power running operation, and the motor output is reversed from the negative side to the positive side. On the other hand, the induction motor connected to the first to third axles outputs a larger value on the negative side because the difference between the rotational frequency signals Fr1 to Fr3 of each axle and the output frequency signal FINV of the power converter increases. Become. Thereafter, when sliding is suppressed and time 100B is reached, the magnitude relationship between FINV and Fr4 (ie, FrMIN) is reversed again, and the induction motor connected to the fourth axle is connected to the first to third axles. Return to the regenerative operation in the same way. When the time 100C is reached and the sliding is completely eliminated, the speeds of all four axles coincide with each other, so that the outputs of the induction motors connected to the first to fourth axles have the same value.

  In the first embodiment, the case where the frequency converter 20 is disposed and the rotational frequency detection means according to the present invention is configured by the speed detection sensor 3 and the frequency converter 20 has been described. For example, when the speed detection sensor 3 outputs rotation frequency information, the frequency converter 20 is not necessarily provided. In this case, the speed detection sensor 3 corresponds to the rotational frequency detection means according to the present invention.

(Embodiment 2)
Next, Embodiment 2 according to the present invention will be described with reference to the drawings. FIG. 7 is a block diagram illustrating a configuration of the automatic control device according to the second embodiment. The main difference between the automatic control device 2 according to the second embodiment and the automatic control device 2 according to the first embodiment is that a wheel diameter difference corrector 40 is provided between the frequency converter 20 and the minimum value selector 23. In addition, the motor output imbalance detector 30 is provided with a detection reference value calculator 33. In the second embodiment, detailed description of the same configuration and the same process as in the first embodiment is omitted.

  The wheel diameter difference corrector 40 takes the rotational frequency signals Fr1 to Fr4 output from the frequency converter 20 as input values, and removes the influence of the rotational frequency deviation of each axle generated by the wheel diameter difference on these input values. Then, each signal obtained after the removal is output to the minimum value selector 23. The minimum value selector 23 detects the minimum value of each signal output from the wheel diameter difference corrector 40, and outputs the rotation frequency minimum value FrMIN as in the first embodiment. That is, the wheel diameter difference corrector 40 is installed in order to remove the influence of the rotational frequency deviation of each axle caused by the wheel diameter difference and to detect the minimum frequency at the time of sliding with higher accuracy.

  The detection reference value calculator 33 uses the output frequency signal FINV output from the output frequency calculator 22 as an input value, and the motor output unbalance detection reference value KFs is a more appropriate value based on the input output frequency signal FINV. Change to be. That is, the detection reference value calculator 33 pays attention to the fact that the slip frequency Fs changes depending on the speed (that is, the axle rotation frequency), and the motor output unbalance detection reference value KFs becomes a more appropriate value according to the speed. By changing (calculating) in this way, the speed dependence of the motor output unbalance detection reference value KFs is eliminated, and the motor output unbalance detection signal OUBD is output with higher accuracy.

  In the second embodiment, the case where both the wheel diameter difference corrector 40 and the detection reference value calculator 33 are provided is described. However, the present invention is not limited to this, and the wheel diameter difference corrector 40 or the detection reference value calculator 33 is provided. Any one of 33 may be arranged.

(Embodiment 3)
Next, Embodiment 3 according to the present invention will be described with reference to the drawings. FIG. 8 is a block diagram illustrating a configuration of the automatic control apparatus according to the third embodiment. The main difference between the automatic control device 2 according to the third embodiment and the automatic control device 2 according to the first embodiment is the configuration of the motor output imbalance detector 30. In the third embodiment, detailed description of the same configuration and the same processing as in the first embodiment is omitted.

  The motor output imbalance detector 30 according to the third embodiment is further provided with a second subtractor 34, a positive / negative determiner 35, and a logical product calculator 36 in addition to the motor output imbalance detector 30 according to the first embodiment. It is installed.

  The second subtractor 34 receives the average frequency signal FrAVE output from the average value calculator 21 and the output frequency signal FINV output from the output frequency calculator 22 as input values, and calculates the average frequency of the axle from the output frequency signal FINV. FrAVE is subtracted to output a control slip frequency Fs ′.

  The positive / negative determination unit 35 uses the slip frequency Fs ′ output from the second subtractor 34 as an input value, and performs positive / negative determination of the slip frequency Fs ′. The positive / negative determination unit 35 outputs a brake operation signal B when the slip frequency Fs ′ is a negative value, that is, when the operation mode of the power conversion device 1 is in the brake state. The brake operation signal B is a Boolean signal or a digital signal having only a binary value of “1” or “0”.

  The logical product calculator 36 takes the brake operation signal B output from the positive / negative determiner 35 and the motor output unbalance detection signal OUBD output from the comparator 32 as input values, and calculates the logical product of these input values. Then, the calculation result is output as OUBD ′. Thus, by calculating the logical product of the brake operation signal B and the motor output unbalance detection signal OUBD, it becomes possible to detect the motor output unbalance state only in the brake state.

  The configuration examples shown in the first to third embodiments can be easily realized by software processing by a microcomputer, for example.

  As described above, according to the present invention, by indirectly monitoring the motor output from the slip frequency, it is possible to detect the motor output imbalance at the time of sliding, which cannot be confirmed only by the speed information, with high accuracy. It is possible to suppress the torque output imbalance of each axle and to suppress the occurrence of wheel and road surface (rail) wear.

DESCRIPTION OF SYMBOLS 1 ... Power converter device, 2 ... Automatic control device, 3 ... Speed detection sensor, 10 ... Vehicle main body, 11 ... Induction motor, 12 ... Axle, 20 ... Frequency converter, 21 ... Average value calculator, 22 ... Output frequency calculation , 23 ... minimum value selector, 30 ... motor output imbalance detector, 31 ... subtractor, 32 ... comparator, 33 ... detection reference value calculator, 34 ... subtractor, 35 ... positive / negative determiner, 36 ... logic Product calculator 40 ... Wheel diameter difference corrector 50 ... Railway vehicle

Claims (10)

A plurality of electric motors for driving the vehicle;
A plurality of axles driven by each of the motors and supporting the wheels;
Rotation frequency detection means for detecting the rotation frequency of each axle;
Control means for controlling the current of each electric motor based on the rotation frequency output from the rotation frequency detection means;
With
The control means includes
An average value calculating means for calculating an average value of the rotational frequencies input from the rotational frequency detecting means;
Minimum value selection means for selecting the minimum value of the rotation frequency input from the rotation frequency detection means;
An output frequency calculating means for calculating an output frequency based on the average value input from the average value calculating means and the current values of the plurality of electric motors;
Motor output imbalance detection means for detecting output imbalance of the plurality of motors;
With
The motor output imbalance detection means is
Subtracting means for subtracting the minimum value input from the minimum value selecting means from the calculated value input from the output frequency calculating means;
Comparison means for comparing the subtraction value input from the subtraction means with a preset reference value and outputting a motor output imbalance detection signal based on the comparison result;
A power conversion device comprising:   The power converter according to claim 1, wherein the comparison unit outputs the motor output imbalance detection signal when the subtraction value exceeds the reference value.   The control means removes the influence of the rotational frequency deviation of each axle caused by the wheel diameter difference on the rotational frequency input from the rotational frequency detecting means, and selects the rotational frequency obtained after the removal as the minimum value. The power converter according to claim 1, further comprising a wheel diameter difference correcting means for outputting to the means.   2. The electric motor output imbalance detection means further comprises detection reference value calculation means for calculating the calculation value input from the output frequency calculation means so as to be changed according to the rotational frequency of the axle. Power converter. The motor output imbalance detection means is
Second subtracting means for subtracting the average value input from the average value calculating means from the calculated value input from the output frequency calculating means;
Positive / negative determining means for performing positive / negative determination of the second subtraction value input from the second subtracting means;
AND operation means for calculating a logical product of the determination value input from the positive / negative determination means and the motor output imbalance detection signal input from the comparison means;
The power converter according to claim 1, further comprising: Based on a plurality of electric motors, a plurality of axles driven by the respective electric motors, a rotational frequency detecting means for detecting a rotational frequency of each of the axles, and a rotational frequency output from the rotational frequency detecting means, A control means for controlling the current of the electric motor, and a method for controlling the power converter comprising:
An average value calculating step of calculating an average value of the rotation frequency input from the rotation frequency detecting means;
A minimum value selection step of selecting the minimum value of the rotation frequency input from the rotation frequency detection means;
An output frequency calculating step of calculating an output frequency based on the average value obtained in the average value calculating step and the current values of the plurality of electric motors;
A motor output imbalance detection step of detecting an output imbalance of the plurality of motors;
Have
The motor output imbalance detection step includes
A subtraction step of subtracting the minimum value obtained in the minimum value selection step from the computation value obtained in the output frequency calculation step;
A comparison step of comparing the subtraction value obtained in the subtraction step with a preset reference value and outputting a motor output imbalance detection signal based on the comparison result;
A control method for a power conversion device having   The method according to claim 6, wherein the comparison step outputs the electric motor output imbalance detection signal when the subtraction value exceeds the reference value.   A wheel for removing the influence of the rotational frequency deviation of each axle generated by the wheel diameter difference with respect to the rotational frequency input from the rotational frequency detecting means, and providing the rotational frequency obtained after the removal to the minimum value selecting step The method of controlling a power converter according to claim 6, further comprising a diameter difference correcting step.   The electric power according to claim 6, wherein the electric motor output imbalance detection step further includes a detection reference value calculation step of calculating so that the calculation value obtained in the output frequency calculation step is changed according to a rotation frequency of the axle. Control method of conversion device. The motor output imbalance detection step includes
A second subtraction step of subtracting the average value obtained in the average value calculation step from the calculation value obtained in the output frequency calculation step;
A positive / negative determination step of performing positive / negative determination of the subtraction value obtained in the second subtraction step;
A logical product operation step of calculating a logical product of the determination value obtained in the positive / negative judgment step and the motor output imbalance detection signal obtained in the comparison step;
The method for controlling the power conversion device according to claim 6, further comprising:

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