Drive device for railway vehicle and control method therefor

Abstract

The present invention provides a drive device for a railway vehicle and a control method therefor, the device enabling highly accurate correction of a wheel diameter difference even when the railway vehicle is driven without a speed sensor. The railway vehicle drive device comprises: an inverter 3 that outputs a voltage to a motor 4; and a control device 2 that, on the basis of an operation command from a higher-order controller 110, adjusts the torque of the motor 4 by adjusting the voltage output of the inverter 3. The control device 2 estimates, without a speed sensor, the rotation speed of a driving wheel shaft that is rotating under inertia during coasting control in which the torque output of the motor 4 is turned off while the voltage is outputted from the inverter 3 to the motor 4. The control device 2 corrects the wheel diameter difference of a drive shaft 102 relative to another shaft 103 on the basis of an estimated value of the rotational speed of the drive shaft 102 (22).

Description

Railway vehicle drive system and control method thereof

[0001] The present invention relates to a railway vehicle drive system and a control method thereof, and more particularly to a railway vehicle drive system and a control method thereof that are capable of controlling the drive of a railway vehicle without a speed sensor.

[0002] In railway vehicle drive systems, a technique for correcting the wheel diameter difference between multiple wheels (hereinafter referred to as wheel diameter difference correction) is known in order to prevent erroneous detection of axle slip and to detect slip earlier.

[0003] Wheel diameter difference correction is performed based on the relative rotational speed difference between the driving axle, which is driven by an inverter, and the other axle, which is a non-driving axle. Wheel diameter difference correction is performed assuming that the wheels and the rails are firmly in contact with each other. If the control system for a railway vehicle drive unit performs wheel diameter difference correction while the wheel is spinning, it will treat the speed difference caused by the spin as a speed difference caused by the wheel diameter difference. This will result in errors in the wheel diameter difference correction.

[0004] Regarding wheel diameter difference correction, for example, Patent Document 1 and Patent Document 2 exist. Patent Document 1 discloses a technology that includes a calculation means for calculating the difference in wheel diameter of an electric vehicle from the deviation in the rotation speed of an induction motor driven by an inverter and the rotation speed of an induction motor driven by another inverter while the electric vehicle is coasting, and that performs wheel diameter difference correction by correcting the rotation speed of the induction motor driven by the other inverter based on the wheel diameter difference calculated by the calculation means when it is determined that the electric vehicle is coasting and that no braking force is being applied to the wheels.

[0005] Patent Document 2 discloses an electric vehicle control device that uses speed sensorless vector control to control the torque of an electric motor without detecting the rotational speed of the electric motor, and that includes a VVVF inverter that converts direct current to alternating current, and wheel diameter difference correction means that corrects the wheel diameter difference of each wheel driven by the electric motor.

[0006] Japanese Patent Laid-Open No. 8-214404 Japanese Patent Laid-Open No. 2005-312126

[0007] Since Patent Document 1 assumes that speed is detected using a pulse generator, it can be applied to speed sensor-equipped control to correct wheel diameter difference. However, Patent Document 1 has the problem of not being applicable to speed sensorless control. On the other hand, Patent Document 2 describes performing wheel diameter difference correction during the torque rise period immediately after the inverter gate signal is output and during the torque fall period immediately before the inverter gate signal is stopped. However, during these periods, torque changes and vehicle acceleration changes, which can easily lead to errors in wheel diameter difference estimation due to fluctuations in motor rotation frequency caused by railway vehicle bogie vibration and delays in tracking in speed sensorless control. Thus, under conditions where fluctuations or errors in the speed estimate occur due to factors other than wheel diameter difference, sufficient accuracy cannot be achieved even if wheel diameter difference correction is performed.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a railway vehicle drive system and a control method thereof that can correct wheel diameter differences with high accuracy even when the railway vehicle is driven without a speed sensor.

[0009] To achieve this object, one representative aspect of the present invention is a railway vehicle drive system comprising an inverter that outputs a voltage to a motor, and a control device that adjusts the voltage output of the inverter to adjust the torque of the motor based on an operation command from a higher-level control device, wherein the control device estimates, without a speed sensor, the rotational speed of a driving wheel axle that is rotating by inertia during coasting control in which voltage is output from the inverter to the motor while the torque output of the motor is turned off, and corrects the wheel diameter difference of the driving axle relative to other axles based on the estimated rotational speed of the driving axle.

[0010] According to the present invention, the rotational speed of the driving wheel set can be estimated without a speed sensor when the wheels of the drive axle are securely adhering to the rail without spinning or sliding, and errors due to spinning or sliding are unlikely to occur in the estimated rotational speed, so the wheel diameter difference can be corrected with high precision.

[0011] 1 is a waveform diagram showing the operation of a first embodiment of a railway vehicle drive device of the present invention; FIG. 2 is an example of a block diagram of the first embodiment; FIG. 3 is an example of a block configuration diagram of an embodiment of a railway vehicle; FIG. 4 is an example of a functional block diagram showing an embodiment of a control circuit; FIG. 5 is an example of a functional block diagram showing an embodiment of a wheel diameter difference correction unit in the control circuit; FIG. 6 is an example of a functional block diagram showing an embodiment of a slip detection unit in the control circuit; FIG. 7 is a diagram showing an example of the operation of a readhesion control unit in the control circuit; FIG. 8 is a functional block diagram of a wheel diameter difference correction unit according to a second embodiment; FIG. 9 is an example of an operation waveform of wheel diameter difference correction in the fluctuation amount determination unit; FIG. 10 is a functional block diagram of a slip detection unit according to a third embodiment; FIG. 11 is a graph showing the characteristics of the slip detection set value in the slip detection unit; FIG. 12 is a functional block diagram of a control circuit in a fourth embodiment; FIG. 13 is a waveform diagram showing the operation of the fourth embodiment; FIG. 14 is a block diagram in which a higher-level control device for a railway vehicle is connected to a server.

[0012] Hereinafter, as modes for carrying out the present invention, each of Embodiments 1 to 5 will be described in detail with reference to the drawings. In each embodiment, elements with the same reference numerals are the same components or components with similar functions. In later embodiments, descriptions of components that are the same or similar to those in previous embodiments may be omitted.

[0013] 2 is a hardware block diagram showing a first embodiment of a railway vehicle drive device of the present invention. The railway vehicle drive device includes a drive system 1 that drives a motor 4. The drive system 1 includes an inverter (main circuit) 3 that applies a three-phase AC voltage to the motor 4, a gate drive circuit 6 that outputs gate signals for driving the inverter 3, a control circuit 2 that outputs a PWM signal 6A to the gate drive circuit 6, and a control circuit 2 that controls the current (i ｕ , i ｖ , i ｗ and a current detector 5 for detecting the current saturation and outputting the detected current saturation to the control circuit 2.

[0014] The control circuit 2 implements a control program for driving and controlling the motor 4, which is a load. The control circuit 2 detects the current detected by the current detector 5 (i ｕ , i ｖ , i ｗThe inverter 3 calculates a voltage command value using vector control or the like so that the voltage command value 2A becomes a current value based on the operation command value 2A, and outputs a PWM signal 6A using pulse width modulation (PWM) control. The inverter 3 is composed of driving transistors such as IGBTs (Insulated Gate Bipolar Transistors) and power devices such as diodes.

[0015] 2, inverter 3 includes six switching elements Sup to Swn, and converts DC voltage E from smoothing capacitor 7 into a three-phase AC voltage based on a switching command from gate drive circuit 6, which is applied to motor 4. Gate drive circuit 6 outputs a gate signal to inverter 3 based on a PWM signal 6A from control circuit 2. A drive current flows in motor 4 due to the three-phase AC voltage output from inverter 3, generating rotational torque. Motor 4 may be an induction motor, a synchronous motor, or the like.

[0016] The current detector 5 is composed of a Hall CT (Current Transformer) and detects the three-phase current i of U-phase, V-phase, and W-phase flowing through the motor 4. ｕ , i ｖ and i ｗ It is not necessary for the current detector 5 to detect the currents of all three phases, and it may be configured to detect any two of the three phases, and then determine the remaining phase by calculation, assuming that the three-phase currents are in a balanced state.

[0017] FIG. 3 is a block diagram showing a portion 100 of a railway vehicle equipped with a railway vehicle drive system according to the first embodiment. In FIG. 3, a vehicle equipped with a motor 4 to output power is referred to as an M car, and a vehicle T is referred to as a T car pulled by the M car. Each vehicle is equipped with a bogie 101, and each of the M and T bogies 101 is equipped with drive wheels (M cars) connected to drive axles 102 and non-drive wheels (T cars) connected to non-drive axles 103. A motor 4 is connected to the drive axles 102 of the drive wheels (M cars) via gears. Because friction between the drive wheels and the track is greater than that of the non-drive wheels, the difference in wheel diameter between the drive wheels and the track (wheel diameter difference) is controlled to be within a predetermined control value.

[0018] The control circuit 2 mounted on the M car transmits and receives signals to and from a host control device 110 (a cab monitor device and a transmission device) mounted on the T car, and receives, for example, signals 2A of operation commands and other axle speed information from the host control device 110. The other axle speed information is obtained from an automatic train control device that automatically controls the railway vehicle, or a speedometer that detects the rotational speed of a non-driven wheel. The other axle rotational speed information may be received from any device as long as it is information equivalent to speed information of an axle other than the own axle (or vehicle speed).

[0019] Fig. 4 shows a functional block diagram of the control circuit 2. Fig. 4 shows only the minimum necessary functional blocks. The notation "*** unit" indicates a functional block. The functional block is realized by a controller, which is a control means of a computer, or a processor executing a control program. The "unit" may be replaced with other terms such as means, circuit, unit, or element.

[0020] The torque command calculation unit 11 calculates a torque command value τ in response to the operation command value 2A from the upper control device 110. ｍ ＊ and outputs the torque command value τ ｍ ＊ Based on this, the current command value i of the dq axes to obtain a predetermined torque is calculated. ｄ ＊ , i ｑ ＊ and outputs the calculated voltage command value to the voltage command value calculation unit 12.

[0021] The current detection coordinate conversion unit 8 converts the three-phase current (i ｕ , i ｖ , i ｗ ) is converted into dq coordinates in the rotating coordinate system using the phase information recognized by the control circuit 2, and the dq axis current detection value (i ｄｆ , i ｑｆ ) to the voltage command value calculation unit 12. The voltage command value calculation unit 12 calculates the dq voltage command value v by PI (Proportional-Integral) control or the like so that the current deviation between the dq axis current detection value output by the current detection coordinate conversion unit 8 and the dq axis current command value output by the current command calculation unit 10 becomes zero. ｄ＊ , v ｑ ＊ and outputs it to the voltage command coordinate conversion unit 13.

[0022] The voltage command coordinate conversion unit 13 calculates a three-phase AC voltage command value (v ｕ ＊ , v ｖ ＊ , v ｗ ＊ ) outputted by the voltage command coordinate conversion unit 13 to the PWM control unit 14. The PWM control unit 14 converts the three-phase AC voltage command value (v ｕ ＊ , v ｖ ＊ , v ｗ ＊ ), a switching command 6 A of a PWM voltage (Pulse Width Modulation) is output to the gate drive circuit 6 for the inverter 3 .

[0023] When the drive system 1 operates under speed sensorless control, if the inverter 3 stops outputting voltage to the motor 4, no magnetic flux is generated in the motor 4, and the drive system 1 is therefore unable to grasp the rotational frequency of the motor itself. During the period when the inverter 3 is outputting voltage, the frequency estimation unit 20 uses the induced voltage due to the magnetic flux to estimate the rotational frequency f of the motor itself, which is the driving axle driven by the inverter, as the rotational speed of the motor itself. ｒｍ＿ｅｓｔ is the current detection value (i ｕ , i ｖ , i ｗ ) is used to estimate the speed without a speed sensor.

[0024] Although not shown in the figure, the dq voltage command value v ｄ ＊ , v ｑ ＊ and the current command value i ｄ ＊ , i ｑ ＊ In the case of an induction motor, the frequency estimator 20 realizes a calculation means that uses, for example, equation (1), and adjusts the speed estimate so as to make the deviation of the q-axis current zero, thereby estimating the rotor angular frequency estimate ω ｒｍ＿ｅｓｔCalculate K Ｐ is the proportional gain, K Ｉ is the integral gain, and s is the Laplace operator.

[0025] As another example, as shown in equations (2) and (3), the frequency may be estimated by correcting the axis shift from the d-axis induced voltage on the dq coordinate system. １ ＊ is the primary resistance, L １ ＊ is the primary self-inductance, ω １ ＊ is the primary angular frequency, σ is the leakage coefficient, ω ｓ ＊ is the slip angular frequency.

[0026] Various forms of estimation calculation are known depending on the type of motor 4, such as an induction motor or a synchronous motor, but any estimation method may be used as long as it is a sensorless estimation calculation without using a speed sensor or a position sensor.

[0027] The frequency conversion unit 21 converts other axis information 2B (other axis speed information: v ｔ ) is input, and other axle speed information (v ｔ ) to the other axis rotation frequency (before correction) f ｒｔ and output it.

[0028] Next, the wheel diameter difference correction unit 22 will be described. Fig. 5 shows a detailed functional block diagram of the wheel diameter difference correction unit 22. The wheel diameter difference correction unit 22 calculates the wheel diameter difference correction frequency (estimated value) f ｒｍ＿ｅｓｔ and other axis rotation frequency (before correction) f ｒｔ and outputs the wheel diameter difference correction coefficient K to the smoothing processing unit 30 from the ratio of the two (30A).

[0029] The smoothing processing unit 30 calculates the average value K of the accumulated wheel diameter difference correction coefficient K every time it receives the wheel diameter difference correction coefficient K while the calculation operation signal ST for wheel diameter difference correction is on (time width T in FIG. 1). ｒand output it to the holding unit 31. In this case, the processing does not necessarily have to be time averaging processing, but any processing that smooths the data, such as moving average processing or smoothing filter processing, may be used.

[0030] When the wheel diameter difference correction is completed and the calculation operation signal ST falls from ON to OFF, the holding unit 31 stores the average value K of the wheel diameter difference correction coefficient K. ｒ The wheel diameter difference correction coefficient K ｒ is the rotation frequency of the other axis (before correction) f ｒｔ (21a) is multiplied by the other axis rotation frequency (after correction): f ｒｔ ’ is obtained.

[0031] Next, the operation of wheel diameter difference correction will be described with reference to Fig. 1. The timing of the operation will be described using the waveform of t (time). Fig. 1 is a timing chart showing the process from the coasting state of the railway vehicle before wheel diameter difference correction is performed, to acceleration after the railway vehicle starts powering, and until the railway vehicle returns to the coasting state and wheel diameter difference correction is completed.

[0032] The driving command (2A in Figure 4) goes high at t1, turning on the torque output of the motor 4 (powering or regenerative state), and goes low at t3, turning off the torque of the motor 4 (coasting period). The operating signal (ST in Figure 5) for operating the wheel diameter difference correction calculation turns on at t4 and off at t5. The PWM signal (6A in Figure 2) for controlling the gate signal from the gate drive circuit 6 to the inverter 3 turns on at t1, remains on even after the driving command value 2A turns off, and then turns off at t6. While the PWM signal 6A is on, the inverter 3 continues to output voltage to the motor 4. Based on the output of the PWM signal 6A, the switching signal to the inverter 3 from the gate drive circuit 6 keeps the gate of the inverter 3 on. The period T from t4 to t5 is the time during which the voltage output 6A continues for wheel diameter difference correction.

[0033] Torque command value (FIG. 4, symbol 11: τ ｍ ＊ ) rises at t2, maintains a constant value, falls at t3, and turns off at t4.ｄ ＊ The q-axis current (reference numeral 10 in FIG. 4: i ｑ ＊ The torque current rises at t2, maintains a constant value until t3, then falls and turns off at t4. Ｒ indicates the effective current value, which is a value obtained by combining the d-axis current and the q-axis current.

[0034] f ｒｍ＿ｅｓｔ is the waveform of the shaft rotation frequency (estimated value), and f ｒｔ ’ is the waveform of the other shaft rotation frequency (after correction). Wheel diameter difference correction coefficient K ｒ is generated after t5.

[0035] At t1, when the operation command 2A is turned on, the frequency estimation unit 20 performs speed sensorless control to calculate the rotational frequency (estimated value): f ｒｍ＿ｅｓｔ By speed sensorless control, before the start of power running (operation command: OFF, voltage output: OFF) before t1, the shaft rotation frequency f ｒｍ＿ｅｓｔ is indefinite, but immediately after startup (operation command: ON, voltage output: ON), the speed sensorless control function (20: frequency estimator) installed in the control circuit 2 starts estimating the frequency at t2, which is several tens to several hundreds of ms from t1, and the shaft rotation frequency f ｒｍ＿ｅｓｔ is settled.

[0036] After that, at t2, the torque command value τ ｍ ＊ When this occurs, the wheels are rotated by the motor 4, and the railway vehicle accelerates. At this time, if there is a difference in wheel diameter between the own axle and the other axle, the difference in wheel rotation speed increases in proportion to the increase in speed. Figure 1 shows a case where the wheel diameter of the own axle is smaller than the wheel diameter of the other axle, and the wheel rotation speed (rotation frequency) increases as the wheel diameter decreases.

[0037] At t3, after the vehicle speed increases, the driving command 2A from the upper control device 110 changes from ON to OFF, and the torque command value τ ｍ ＊After the torque command value falls, if the motor 4 is a permanent magnet synchronous motor, the field weakening control may be activated to continue voltage output (gate signal 6A: ON) in order to suppress the occurrence of a charging operation that occurs when the induced voltage generated by the magnetic flux of the magnet becomes higher than the DC voltage E of the smoothing capacitor 7. On the other hand, if the motor 4 is an induction motor, the excitation current (d-axis current command value) i ｄ ＊ If no current is applied, the secondary magnetic flux will also disappear in about several hundred milliseconds, so it is common to stop the voltage output (gate signal 6A: OFF) after the torque has fallen.

[0038] However, the control circuit 2 in Fig. 2 provides a control period (indicated by T in the figure) in which voltage output (6 A) continues for wheel diameter difference correction after t3, thereby realizing highly accurate wheel diameter difference correction even in speed sensorless control. During this period, the current command value calculation unit 10 calculates the torque current i ｑ ＊ is turned off, but the voltage output 6A is not turned off and continues after t3, so the excitation current i ｄ ＊ The output of the current detector 5 can be continued until t5 when the wheel diameter difference correction is completed. During this time, the frequency estimator 20 can estimate the rotation frequency of its own shaft based on the detected value from the current detector 5 (see FIG. 4).

[0039] Between t4 and t5, the calculation operation signal ST is turned on while continuing to output voltage and estimate the speed by speed sensorless control. ｍ ＊ When the operation command 2A is turned off, the torque command value τm* becomes approximately zero so that the wheels do not spin. It can be said that the torque command value τm* is set to a value that can be considered to be zero, considering that the operation command 2A from the upper control device 110 is turned off. As a result, the railway vehicle runs by inertia, and the wheels rotate by inertia. When the motor 4 is an induction motor, the current command value calculation unit 10 calculates the excitation current (d-axis current command value) i ｄ ＊ While generating the magnetic flux of the motor 4 by passing only the torque current (q-axis current) i ｑ＊ In the case of a permanent magnet synchronous motor, the current command value calculation unit 10 calculates at least the torque current (q-axis current) i ｑ ＊ The wheel diameter difference correcting unit 22 (FIG. 5) calculates the time average value of the ratio of the own shaft rotation frequency to the other shaft rotation frequency during the period T from t4 to t5.

[0040] As described above, the time average value of the ratio of the own-shaft rotational frequency to the other-shaft rotational frequency is calculated during the coasting control period when the torque is set to approximately zero. This calculation is primarily based on the following three reasons. First, there is a risk of the own-shaft spinning during torque output. Second, the calculation is intended to eliminate the effects of speed fluctuations that occur during the torque rise and fall periods. During the torque rise immediately after t2 and the torque fall period from t3 to t4, vehicle acceleration changes. This is intended to avoid estimation errors that are likely to occur due to fluctuations in the motor rotational frequency caused by longitudinal impulses between railway vehicles and bogie vibrations, as well as delays in tracking speed changes in speed sensorless control. Third, by performing the calculation during the coasting control period when the torque is set to approximately zero, errors due to transmission delays contained in the other-shaft rotational frequency are reduced. The transmission period for receiving the other-shaft rotational frequency is often several tens to several hundreds of milliseconds. Therefore, errors due to transmission delays occur when the calculation is performed under conditions where the speed change rate of the other-shaft rotational frequency is large, such as during acceleration and deceleration.

[0041] As described above, sufficient accuracy cannot be obtained even if wheel diameter difference correction is performed under conditions in which there are fluctuations or errors in the speed estimation value due to factors other than the wheel diameter difference. Therefore, in order to reliably prevent axle spin and minimize changes in acceleration due to the influence of the mechanical system, the control circuit 2 may perform wheel diameter difference correction by estimating the rotational speed of the driving axle rotating by inertia without a speed sensor, by transitioning to a coasting control state in which the inverter 3 outputs voltage to the motor 4 while turning off the torque output of the motor 4 after the operation command changes from on to off.

[0042] At t5, the control circuit 2 changes the calculation operation signal (ST) for wheel diameter difference correction from ON to OFF, completing the wheel diameter difference correction. At this time, the wheel diameter difference correction unit 22 shown in FIG. 5 uses the holding unit 31 to store the wheel diameter difference correction coefficient K ｒ Wheel diameter difference correction coefficient K ｒ is updated from 1.0 before correction to an appropriate value of 500 (FIG. 1), and at t5, the shaft rotation frequency f ｒｍ＿ｅｓｔ and other axis rotation frequency f ｒｔ ’ will be consistent with

[0043] At t6, when the wheel diameter difference correction is completed, the PWM control unit 14 stops the voltage output 6A. As a result, the frequency estimate value of the own shaft by the speed sensorless control becomes indefinite, but the holding unit 31 (FIG. 5) keeps the wheel diameter difference correction coefficient K ｒ This is maintained even during coasting. As a result, the next powering can be started with the wheel diameter difference correction completed. If demagnetization control is to be performed, it may be performed as appropriate just before the gate stop (t6).

[0044] Correction of wheel diameter difference is preferably performed when the vehicle is traveling at a predetermined speed or higher (for example, 30% or higher of the maximum speed). Since the frequency difference due to the wheel diameter difference between the own axle and the other axle is proportional to the running speed of the railway vehicle, sufficient accuracy cannot be obtained when wheel diameter difference correction is performed in the low speed range, and the wheel diameter difference correction coefficient K ｒ This is because the predetermined speed includes an error. In other words, it is preferable to set the predetermined speed so that a frequency difference occurs depending on the wheel diameters of the own axle and the other axles.

[0045] Although the wheel diameter difference correction unit 22 has been described as calculating the wheel diameter difference correction coefficient from the frequency ratio, it may also be calculated from the ratio of rotational speeds. Since the wear of the wheel diameter does not substantially change over the course of about one day of running of the railway vehicle, once the wheel diameter difference correction unit 22 completes the wheel diameter difference correction after the start of commercial operation of the railway vehicle, the wheel diameter difference correction unit 22 holds the wheel diameter difference correction coefficient until the power of the control circuit 2 is turned off, and thereafter the control circuit 2 may omit steps t4 to t6 and not perform wheel diameter difference correction.

[0046] If the driving command 2A is turned off at t3 and then turned on during the period T from t4 to t5, the wheel diameter difference correction unit 22 suspends wheel diameter difference correction, and the control circuit 2 transitions to normal powering / regenerative operation. Since the estimated speed value is known during the period from t4 to t5 (FIG. 5: frequency estimator 20), the period from t1 to t2 for converging the estimated value is not required, and the control circuit 2 quickly transitions to powering / regenerative operation.

[0047] The railway vehicle drive system in Figure 2 shows a configuration (1C1M) in which one inverter drives one motor 4. However, if the motor 4 is an induction motor, a configuration (1C2M, 1C4M, etc.) in which one inverter drives multiple motors 4 may also be used. When the present invention is applied to a system in which multiple motors 4 are driven, wheel diameter difference correction can be performed by comparing the average frequency estimate (self-shaft rotational frequency) of the multiple motors 4 with the rotational frequency of the other shaft.

[0048] The control circuit 2 focuses on the fact that the running pattern of a railway vehicle involves repeating acceleration, coasting, and deceleration at a predetermined frequency, and by utilizing the coasting period, achieves high-precision wheel diameter difference correction even with speed sensorless control.

[0049] Continuing with the explanation of Fig. 4, the slip detection unit 23 in Fig. 4 is a detailed block diagram thereof, and as also shown in Fig. 6, the rotation frequency (estimated value) f ｒｍ＿ｅｓｔ and other axis rotation frequency (after correction) f ｒｔ ’ The difference between the rotation frequency f and the rotation frequency f is calculated, and the result is processed by an abs function to obtain an absolute value X1, which is then compared with the detection set value X2. ｒｍ＿ｅｓｔ and other axis rotation frequency (after correction) f ｒｔ ’ If the absolute value X1 of the difference between these values ​​is equal to or greater than the detection set value X2, it is determined that a spin has occurred in the drive wheel of the own axle, and a spin detection signal D1 is output.

[0050] The detection set value is set so as not to erroneously detect wheel spin. If the accuracy of wheel diameter difference correction is low, the value will be large. If the detection set value is large, wheel spin detection will be delayed, so it is desirable to set the detection set value as small as possible within the range that does not cause erroneous detection.

[0051] Furthermore, it is desirable that the rotation frequency of the other axle used by the wheel spin detection unit 23 be based on the speed of the non-driving wheel axle (T axle). When two driving wheel axles (M axles) are used, both M axles may spin simultaneously. A method of detecting wheel spin from the speed difference between the own axle (M axle) and the other axle (T axle) is effective for wheel spin that occurs gradually and continuously. The wheel spin detection unit 23 is not limited to this method. In order to detect wheel spin that rapidly increases, the wheel spin detection unit 23 may calculate the wheel acceleration from the frequency differential value of the own axle (M axle) and detect wheel spin when the acceleration exceeds a predetermined value. Multiple detection methods, including other detection methods, may be used in combination.

[0052] Next, the readhesion operation after the occurrence of a slip of the axle (the slip readhesion section 24 in FIG. 4) will be described with reference to FIG. 7. FIG. 7 shows the axle rotation frequency (estimated value) f ｒｍ＿ｅｓｔ and other axis rotation frequency (after correction) f ｒｔ ’ When the road surface adhesion coefficient decreases due to rain or other reasons, the driving wheel axle (M axle) will spin due to torque exceeding the maximum adhesion. The spin detection unit 23 outputs a spin detection signal D1 (OFF → ON) when the frequency difference between the own axle and the other axle exceeds the detection set value S.

[0053] The slip re-adhesion unit (re-adhesion control unit) 24 adjusts the torque command value τ ｍ ＊ The torque control signal Δτ for narrowing down the ｍ ＊ is output to the torque command value calculation unit 11 shown in Fig. 4. As a result, the slip occurring between the wheel and the rail is resolved, and the drive shaft and the rail are re-adhered.

[0054] While the wheel diameter difference correction and slip readhesion control have been described in relation to slip that occurs during power running, the same applies to skid that occurs during regeneration. With the above configuration, the control circuit 2 can correct the wheel diameter difference with high precision even in speed sensorless control, and can prevent erroneous detection of slip and realize its early detection.

[0055] 8, a second embodiment according to the present invention differs from the first embodiment in that the wheel diameter difference correction unit 22 includes a fluctuation amount determination unit 32. The fluctuation amount determination unit 32 receives a wheel diameter difference correction coefficient (intermediate value) signal K and a calculation operation signal ST, and outputs a fluctuation amount normal signal K2 to a holding unit 31.

[0056] If the wheel diameter difference correction unit 22 corrects the wheel diameter and the own axle rotation frequency or the other axle rotation frequency fluctuates due to impulses caused by rail joints or vehicles pushing against each other during the period in which the wheel diameter difference correction unit 22 corrects the wheel diameter, an error may be included in the wheel diameter difference correction value. Fig. 9 is a waveform diagram for explaining the operation of the fluctuation amount determination unit 32. The wheel diameter difference correction unit 22 determines whether the wheel diameter difference correction coefficient (intermediate value) K is normal, i.e., whether it is included in a predetermined threshold range R1. Fig. 9 shows that K exceeds the threshold range R1 downward at t4a between t4 and t5.

[0057] 9 further shows the waveforms of the calculation operation signal ST and the fluctuation normal signal K2 for wheel diameter difference correction. The calculation operation signal ST turns ON at t4, and then changes from ON to OFF at t5. The wheel diameter difference correction unit 22 raises the fluctuation normal signal K2 to ON based on the ON state of the calculation operation signal ST. While the calculation operation signal ST is ON, the wheel diameter difference correction unit 22 changes the fluctuation normal signal K2 from ON to OFF at the time (t4a) when the wheel diameter difference correction coefficient (intermediate value) K falls outside the threshold range R1.

[0058] When correcting the wheel diameter difference, the wheel diameter difference correction unit 22 stores the wheel diameter difference correction coefficient K ｒ However, if the fluctuation normal signal K2 is ON, the correction coefficient K ｒ is enabled and saved, and conversely, if the fluctuation normal signal K2 is OFF, the correction coefficient Kr is disabled and not saved. With this configuration, the wheel diameter difference correction unit 22 excludes the wheel diameter difference correction coefficient for periods when acceleration changed significantly due to a steep gate gradient or application of the mechanical brake. Therefore, conditions when the frequency value is unstable can be excluded, and the wheel diameter difference correction can be made more accurate.

[0059] [Embodiment 3] Next, a third embodiment of the present invention will be described. This embodiment differs from the previously described embodiments in that, as shown in Fig. 10, the slip detection unit 23 includes a slip detection set value setting unit 25. Fig. 10 is a functional block diagram illustrating the details of the slip detection unit 23. The wheel diameter difference correction unit 22 is configured to output a wheel diameter difference correction completion flag F1 when wheel diameter difference correction is completed.

[0060] The slip detection set value setting unit 25 calculates the absolute value of the shaft rotation frequency (estimated value) (|f ｒｍ＿ｅｓｔ In other words, when the wheel diameter difference correction completion flag F1 is 0 (before the wheel diameter difference correction is completed), the wheel diameter difference correction set value setting unit 25 outputs the absolute value (|f ｒｍ＿ｅｓｔ When the wheel diameter difference correction completion flag F1 is 1 (after the wheel diameter difference correction is completed), the wheel spin detection set value setting unit 25 outputs the wheel spin detection set value X2 for the absolute value (|frm_est|) of the own shaft rotation frequency (estimated value) in accordance with the characteristic (b).

[0061] (a) is for the case where the difference in wheel diameter between the axle and the other axle is the maximum in the wheel specifications. For example, if the maximum wheel diameter is 860 mm and the minimum is 780 mm, X2 is the frequency difference caused by a wheel diameter difference of up to 80 mm.

[0062] (b) takes into consideration the accuracy of wheel diameter difference correction. For example, if wheel diameter difference correction can be performed with an accuracy of within X mm, X2 will be the frequency difference caused by the wheel diameter difference (X mm). The signal of the other shaft rotation frequency is subject to a transmission delay from the upper control device 110 (FIG. 2). Therefore, the slip detection set value setting unit 25 determines the slip detection set value X2 taking into consideration the influence of the transmission delay when the frequency is changing, such as during vehicle acceleration or deceleration, and the frequency difference caused by the resolution (quantization) of the other shaft rotation frequency signal. By setting lower limits for both characteristics (a) and (b) that take the above into consideration, it is possible to prevent erroneous detection of slip due to delay.

[0063] With the above configuration, an appropriate spin detection set value can be set for each speed range both before and after completion of wheel diameter difference correction, and early detection of spin according to the speed range can be achieved while preventing erroneous detection of spin.

[0064] Next, a fourth embodiment of the present invention will be described. Fig. 12 is a detailed block diagram of the control circuit 2 according to this embodiment. The difference from the block diagram (Fig. 4) of the embodiment described above is that the frequency estimator 20 does not include the other-axis rotation frequency (after correction) f ｒｔ When the railcar is coasted and powered / regenerated again, the frequency estimation unit 20 estimates the other shaft rotation frequency (after correction) f ｒｔ ' is used as the initial value of the axis rotation frequency (estimated value).

[0065] Next, the operation of the fourth embodiment will be described based on the waveform diagram shown in Fig. 13. Fig. 13 is a timing chart of waveforms when the vehicle is accelerated by restarting power running from a coasting state after wheel diameter difference correction is completed. The characteristics of Fig. 13 can be understood by comparing it with the waveform diagram of Fig. 1. As shown at time t5 in Fig. 1, when wheel diameter difference correction is completed, the own shaft rotation frequency and the other shaft rotation frequency (after correction) can be made to match while the vehicle is coasting. In contrast, the wheel diameter difference correction unit 22 uses the f in Fig. 14 ｒｍ＿ｅｓｔ , f ｒｔ 'K' ｒ As shown in Fig. 1, immediately after the start of power running, ｎ From this, the shaft rotation frequency (estimated value) f ｒｍ＿ｅｓｔ and other axis rotation frequency (after correction) f ｒｔ Therefore, it is possible to obtain the effect of shortening the time required for the speed estimate to converge immediately after restarting from coasting and reducing torque shock.

[0066] The reason why the other shaft rotation frequency (after correction) is not always used as an alternative to speed sensorless control but is used only as an estimated initial value is that, as described in embodiment 3, the other shaft rotation frequency is received by transmission or the like, which causes communication delays and quantization errors. In controlling the motor 4 in railway vehicle applications, it is required to be able to estimate the speed even in situations where the rotor frequency changes suddenly, such as when the rotor is spinning, and so it is effective to use the other shaft rotation frequency (after correction) only as an estimated initial value.

[0067] As described above, the railway vehicle drive device according to the fourth embodiment uses the other shaft rotation frequency (after correction) as the estimated initial value for the speed sensorless control, thereby enabling a reduction in the restart time while reducing the torque shock when restarting the motor from the coasting control state more than in the third embodiment.

[0068] [Fifth Embodiment] Next, a fifth embodiment will be described. In the fifth embodiment, as shown in the block diagram of Fig. 14, a host control device 110 of a railway vehicle 100 transmits and receives data to a communication server 120. In Fig. 14, a control circuit 2 transmits wheel diameter information 2A-1 acquired by wheel diameter difference correction to the host control device 110. The host control device 110 transmits slip information to the communication server 120 by wireless communication means such as Wi-Fi.

[0069] Wheel diameter information for each axle is sent to the communication server 120 and data is stored. Based on the daily changes in wheel diameter, the communication server 120 can analyze whether the wheel diameter difference within the bogie or vehicle is within a specified value. The trend in changes in wheel diameter wear can also be used to predict when wheel turning work is necessary, making wheel maintenance more efficient. A wireless device may be installed in the drive system 1, and data may be sent from this wireless device to the communication server 120.

[0070] As described above, the railway vehicle drive device according to the fifth embodiment transmits the wheel diameter information obtained by the wheel diameter difference correction to the communication server 120, and the communication server 120 can thereby confirm the likelihood of the wheel diameter difference within the bogie or vehicle relative to the specified value and predict when it will be exceeded.

[0071] Although the present invention has been described above using embodiments, it goes without saying that the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. Furthermore, it is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0072] 1... drive system, 2... control device, 3... inverter, 4... motor, 5... current detector, 6... gate drive circuit, 7... smoothing capacitor, 8... current detection value coordinate conversion unit, 10... current command value calculation unit, 11... torque command value calculation unit, 12... voltage command value calculation unit, 13... voltage command value coordinate conversion unit, 14... PWM control unit, 20... frequency estimation unit, 21... frequency conversion unit, 22... wheel diameter difference correction unit, 23... slip detection unit, 24... re-adhesion control unit, 25... slip detection set value setting unit, 30... smoothing processing unit, 31... holding unit, 100... railway vehicle, 101... bogie, 102... drive axle (M car), 103... non-drive axle (T car), 110... upper control device, 120... communication server.

Claims

1. A railway vehicle drive device comprising: an inverter which outputs a voltage to a motor; and a control device which adjusts the voltage output of the inverter to adjust the torque of the motor based on an operation command from a higher-level control device, wherein the control device estimates, without a speed sensor, the rotational speed of a driving axle which is rotating by inertia during coasting control in which the inverter outputs a voltage to the motor while the torque output of the motor is turned off, and corrects the wheel diameter difference of the driving axle relative to other axles based on the estimated rotational speed of the driving axle.

2. The railway vehicle drive device according to claim 1, characterized in that the control device corrects the wheel diameter difference between the drive axle and the other axles, including a non-drive axle, based on an estimated value of the rotational speed of the drive axle and the rotational speeds of the other axles.

3. The railway vehicle drive device according to claim 1 or 2, characterized in that, after the operation command changes from on to off, the control device continues to output voltage from the inverter to the motor and transitions to the coasting control.

4. A railway vehicle drive device as claimed in any one of claims 1 to 3, further comprising a gate drive circuit that outputs a gate signal for driving the motor based on a command value for a voltage output from the inverter to the motor, and wherein, after the operation command changes from on to off, the control device causes the gate drive circuit to output the gate signal to maintain the gate on state of the inverter and transition to the coasting control.

5. The railway vehicle drive device according to any one of claims 1 to 4, characterized in that the control device obtains an estimate of the rotational speed of the drive shaft from the detected value of the current flowing through the motor based on the continuation of the voltage output from the inverter to the motor, and corrects the wheel diameter difference between the drive shaft and the other axle.

6. A railway vehicle drive device as claimed in any one of claims 1 to 5, characterized in that the control device calculates a torque current and an excitation current based on the torque command value of the operation command, and after the operation command changes from on to off, makes the torque current substantially zero and maintains the excitation current until the wheel diameter difference is corrected, and the inverter outputs a voltage based on the excitation current to the motor.

7. A railway vehicle drive device as claimed in any one of claims 1 to 6, characterized in that the control device performs the correction of the wheel diameter difference when the railway vehicle is traveling at or above a predetermined speed, and the predetermined speed is set so that a difference occurs in rotational frequency based on the wheel diameter between the drive axle and the other axle.

8. A railway vehicle drive device as claimed in any one of claims 1 to 7, characterized in that, when the ratio between the estimated value of the rotational speed of the drive axle and the rotational speed of the other axle falls outside a threshold region during the process of time fluctuation, the control device does not use the ratio that falls outside the threshold region to correct the wheel diameter difference.

9. The railway vehicle drive device according to any one of claims 1 to 8, characterized in that the control device determines whether or not the drive wheels are spinning by comparing the estimated value of the rotational speed of the drive axle and the rotational speed of the other axle with a reference value, and changes the reference value before and after correcting the wheel diameter difference.

10. A railway vehicle drive device as described in any one of claims 1 to 9, characterized in that, when the railway vehicle restarts from coasting to powering, the control device uses the rotational speed of the other axle, with the wheel diameter difference corrected, as an initial value for an estimated rotational speed of the drive axle.

11. The railway vehicle drive device according to any one of claims 1 to 10, characterized in that the host control device is connected to a server.

12. A control method for a railway vehicle drive device that adjusts the voltage output of an inverter to adjust the torque of a motor based on an operation command from a higher-level control device, the control method for a railway vehicle drive device comprising: estimating, without a speed sensor, the rotational speed of a driving axle rotating by inertia during coasting control in which a voltage is output from the inverter to the motor while the torque output of the motor is turned off; and correcting the wheel diameter difference of the driving axle relative to other axles based on the estimated rotational speed of the driving axle.

13. The control method for a railway vehicle drive device as claimed in claim 12, further comprising correcting the wheel diameter difference between the drive axle and other axles based on the estimated rotational speed of the drive axle and the rotational speeds of other axles including non-drive axles.

14. The method for controlling a railway vehicle drive device according to claim 12 or 13, characterized in that after the operation command changes from on to off, voltage output from the inverter to the motor is continued and the coasting control is started.

15. A control method for a railway vehicle drive device as claimed in any one of claims 12 to 14, characterized in that a gate signal for driving the motor is output based on a command value of a voltage output from the inverter to the motor, and after the operation command changes from on to off, a gate signal is output to a gate drive circuit to maintain the gate on state of the inverter and transition to the coasting control.

16. A control method for a railway vehicle drive device as claimed in any one of claims 12 to 15, characterized in that an estimated rotational speed of the drive shaft is calculated from a detected value of a current flowing through the motor based on the continuation of a voltage output from the inverter to the motor, and a difference in wheel diameter between the drive shaft and the other axle is corrected.

17. A control method for a railway vehicle drive device as claimed in any one of claims 12 to 16, characterized in that a torque current and an excitation current are calculated based on the torque command value of the operation command, and after the operation command changes from on to off, the torque current is made substantially zero and the excitation current is maintained until the wheel diameter difference is corrected, and the inverter outputs a voltage based on the excitation current to the motor.

18. A method for controlling a railway vehicle drive device as claimed in any one of claims 12 to 17, characterized in that the wheel diameter difference is corrected when the railway vehicle is traveling at or above a predetermined speed, and the predetermined speed is set so that a difference occurs in rotational frequency based on the wheel diameter between the drive axle and the other axle.

19. A control method for a railway vehicle drive device as claimed in any one of claims 12 to 18, characterized in that, when the ratio between the estimated value of the rotational speed of the drive axle and the rotational speed of the other axle falls outside a threshold region during the process of time fluctuation, the ratio that falls outside the threshold region is not used to correct the wheel diameter difference.

20. A control method for a railway vehicle drive device as claimed in any one of claims 12 to 19, comprising: determining whether or not the drive wheels are spinning by comparing the estimated value of the rotational speed of the drive axle and the rotational speed of the other axle with a reference value; and varying the reference value before and after correcting the wheel diameter difference.

21. A control method for a railway vehicle drive device as described in any one of claims 12 to 20, characterized in that when a railway vehicle restarts from coasting to powering, the rotational speed of the other axle, with the wheel diameter difference corrected, is used as an initial value for an estimated rotational speed of the drive axle.

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