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 v

Description

Title of Invention: DRIVE DEVICE FOR RAILWAY VEHICLE AND CONTROL METHOD THEREFOR Technical Field

[0001] The present invention relates to a railway vehicle driving device and a control method thereof, capable of controlling the driving of a railway vehicle without using a O '—- Kt- Vi k—> vt IIO tO -1— * Background Art

[0002] Railway vehicle driving devices use a known technology that corrects a wheel diameter difference between multiple wheels (hereinafter referred to as wheel diameter difference correction) to prevent false detection of axle slips and to detect slips earlier.

[0003] The wheel diameter difference correction is performed based on a relative rotational speed difference between the own shaft, which is a driving wheel shaft driven by an inverter, and the other shaft, which is a non-driving wheel shaft. The wheel diameter difference correction presupposes that the wheel firmly adheres to the rail. If the wheel diameter difference correction is performed while the own shaft slips, the control system of a railway vehicle driving device identifies the speed difference caused by the slip as the speed difference due to a wheel diameter difference. This causes an error in the wheel diameter difference correction. For example, Patent Literature 1 and Patent Literature 2 pertain to the wheel diameter difference correction. The technology disclosed in Patent Literature 1 includes a computing means that, during the coasting operation of an electric rolling stock, computes a wheel diameter difference in the electric rolling stock based on a deviation between the rotational speed of an induction motor driven by an inverter and the rotational speed of an induction motor driven by another inverter. During the determination of whether the coasting operation is in process and no braking force is applied to the wheels, the wheel diameter difference correction is performed by correcting the rotational speed of the induction motor driven by the other inverter based on the wheel diameter difference computed by the computing means.

[0005] Patent Literature 2 discloses the electric rolling stock control device for the speed sensorless vector control that controls the motor torque without detecting the rotational speed of the motor. The electric rolling stock control device includes a VVVF inverter for converting direct current to alternating current and a wheel diameter difference correction means for correcting a wheel diameter difference in each motor-driven wheel. Citation List Patent Literature

[0006] Patent Literature 1: Japanese Unexamined Patent Application Publication No. Hei 8-214404 Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2005-312126 Summary of Invention Technical Problem

[0007] Patent Literature 1 presupposes the use of a pulse generator to detect speeds and can be applied to speed sensor-equipped control to correct the wheel diameter difference. However, Patent Literature 1 cannot be applied to speed sensorless control. Patent Literature 2 describes that the wheel diameter difference correction is performed during the torque activation period immediately after an inverter gate signal is output or during the torque inactivation period immediately before an inverter gate signal stops. The wheel diameter difference correction cannot ensure sufficient accuracy under conditions where the estimated speed varies or is subject to errors due to factors other than the wheel diameter difference.

[0008] The present invention aims to provide a railway vehicle drive device and a control method thereof capable of accurately correcting a wheel diameter difference even when a railway vehicle is driven in a speed-sensorless manner. Solution to Problem

[0009] To achieve the above-described object, one aspect of the present invention provides a railway vehicle driving device, including an inverter that outputs a voltage to a motor; and a control device that adjusts the torque of the motor by adjusting voltage output of the inverter based on an operation command from a higher-order control device. The control device outputs a voltage from the inverter to the motor, and meanwhile, estimates, in a speed-sensorless manner, a rotational speed of a driving wheel shaft inertially rotating during coasting control that turns off torque from the motor, and corrects a wheel diameter difference of the drive shaft from the other shaft based on an estimated rotational speed of the drive shaft. Advantageous Effects of Invention

[0010] According to the present invention, it is possible to estimate the rotational speed of a driving wheel shaft in a speed-sensorless manner when the wheel of a driving shaft firmly adheres to the rail without slipping or skidding. A wheel diameter difference can be corrected highly accurately since errors due to slipping or skidding hardly occur in the estimated rotational speed. Brief Description of Drawings

[0011] Fig. 1 is a waveform diagram illustrating the operation of the railway vehicle driving device according to a first embodiment of the present invention. Fig. 2 is an example block diagram according to the first embodiment. Fig. 3 is an example block configuration diagram illustrating an embodiment of a railway vehicle. Fig. 4 is an example functional block diagram illustrating an embodiment of a control circuit. Fig. 5 is an example functional block diagram illustrating an embodiment of a wheel diameter difference correction portion of the control circuit. Fig. 6 is an example functional block diagram illustrating an embodiment of a slip detection portion of the control circuit. Fig. 7 is a diagram illustrating an example operation of a re-adhesion control portion of the control circuit. Fig. 8 is a functional block diagram of the wheel diameter difference correction portion according to a second embodiment. Fig. 9 illustrates example operation waveforms of the wheel diameter difference correction in a variation determination portion. Fig. 10 is a functional block diagram illustrating a slip detection portion according to a third embodiment. Fig. 11 is a graph illustrating slip detection set value characteristics in the slip detection portion. Fig. 12 is a functional block diagram illustrating a control circuit according to a fourth embodiment. Fig. 13 is a waveform diagram illustrating the operation of the fourth embodiment. Fig. 14 is a block diagram illustrating a higher-order control device of a railway vehicle connected to a server. Description of Embodiments

[0012] The following describes in detail the first through fifth embodiments of the present invention, referencing the drawings. In each embodiment, the same reference number indicates the same component or a component having a similar function. The description of the same or similar components as those in the preceding embodiments may be omitted from the subsequent embodiments. [First Embodiment] Fig. 2 is a hardware block diagram illustrating the first embodiment of the railway vehicle driving device according to the present invention. The railway vehicle driving device includes a drive system 1 that drives a motor 4. The drive system 1 includes an inverter (main circuit portion) 3 that applies a three-phase AC voltage to the motor 4, a gate drive circuit 6 that outputs a gate signal to drive the inverter 3, a control circuit 2 that outputs a PWM signal 6A to a gate drive circuit 6, and a current detector 5 that detects a current (iu, iv, iw) of each phase flowing through the motor 4 and outputs it to the control circuit 2.

[0014] The control circuit 2 is installed with a control program for providing drive control over the motor 4 as a load. The control circuit 2 calculates a voltage command value using vector control, for example, so that the detected current value (iu, iv, iw) from the current detector 5 conforms to a current value based on the operation command value 2A, and outputs a PWM signal 6A based on pulse width modulation control (PWM). The inverter 3 is composed of power devices such as driving transistors including IGBTs (Insulated Gate Bipolar Transistors) and diodes.

[0015] In Fig. 2, the inverter 3 includes six switching elements, Sup through Swn, and based on a switching command from the gate drive circuit 6, extracts DC voltage E of a smoothing capacitor 7 into a three-phase AC voltage, and applies it to the motor 4. The gate drive circuit 6 outputs a gate signal to the inverter 3 based on the PWM signal 6A from the control circuit 2. The inverter 3 outputs the three-phase AC voltage, causing a driving current to flow through the motor 4 that then generates rotational torque. The motor 4 represents an induction motor or a synchronous motor, for example .

[0016] The current detector 5 is composed of a Hall CT (Current Transformer), for example, and detects the waveforms of three-phase currents iu, iv and iw corresponding to U, V, and W phases, flowing through the motor 4. The current detector 5 does not necessarily detect all three phases of current. It may also be advantageous to detect any two of the three phases and calculate the remaining phase by assuming that the three-phase currents are balanced.

[0017] Fig. 3 is a block diagram illustrating part 100 of a railway vehicle equipped with the railway vehicle driving device according to the first embodiment. In Fig. 3, M vehicle denotes a vehicle equipped with the motor 4 to output power, and T vehicle denotes a vehicle towed by the M vehicle. Each vehicle includes a truck 101. The truck 101 for the M vehicle includes a drive wheel connected to a drive shaft 102. The truck 101 for the T vehicle includes a non-driving wheel connected to a non-drive shaft 103. The motor 4 is connected to the drive shaft 102 of the driving wheel (M vehicle) via a gear. Friction between the drive wheel and the track is greater than that of the non-driving wheel. The wheel diameter difference between the two is managed to remain within a predetermined management value.

[0018] The control circuit 2 mounted on the M vehicle transmits and receives signals from a higher-order control device 110 (cab monitor device and transmission device) mounted on the T vehicle. For example, it receives a signal 2A representing an operation command or other shaft speed information from the higher-order control device 110. The other shaft speed information is acquired from an automatic train control device that automatically controls the railway vehicle, or a speedometer that detects the rotational speed of the nondriving wheel. The other shaft rotational speed information may be received from any device as long as it is comparable to speed information (or vehicle speed) other than concerning the own shaft.

[0019] Fig. 4 illustrates a functional block diagram of the control circuit 2. Fig. 4 illustrates only the minimum necessary functional blocks. The description "**** portion" denotes the functional block. A controller or a processor, as a control means of a computer, executes a control program to embody the functional block. The "portion" may be replaced with other terms such as means, circuit, unit, or element, for example .

[0020] A torque command operation portion 11 calculates and outputs the torque command value im* to a current command operation portion 10, according to the operation command value 2A from the higher-order control device 110. The current command operation portion 10 calculates dq-axis current command values id* and iq* to acquire a specified torque based on torque command value im*, and outputs them to a voltage command value operation portion 12.

[0021] A current detection coordinate conversion portion 8 converts the three-phase current (iu, iv, iw) of the motor 4, detected by the current detector 5, into dq coordinates of the rotating coordinate system using the phase information identified by the control circuit 2 and outputs them, as dq-axis detected current values (idf, iqf) , to the voltage command value operation portion 12. The voltage command value operation portion 12 generates and outputs dq voltage command values Vd* and vq* based on PI (Proportional-Integral) control, for example, to a voltage command coordinate conversion portion 13 so as to zero the current deviation between the dq-axis detected current value, output by the current detection coordinate conversion portion 8, and the dq-axis current command value, output by the current command operation portion 10 .

[0022] The voltage command coordinate conversion portion 13 outputs the three-phase AC voltage command values (vu*, vv*, vw*) to a PWM control portion 14 by using the dq-axis voltage command value and the phase information output by the voltage command value operation portion 12. The PWM control portion 14 outputs a switching command 6A for PWM (Pulse Width Modulation) voltage to the inverter 3 via the gate drive circuit 6 based on the three-phase AC voltage command value (vu*, vv*, vw*) output by the voltage command coordinate conversion portion 13.

[0023] Suppose the drive system 1 operates under the speed sensorless control, and the inverter 3 stops outputting voltage to the motor 4. In such a case, the motor 4 generates no magnetic flux and the drive system 1 cannot identify the own shaft rotational frequency. While the inverter 3 outputs voltage, a frequency estimation portion 20 uses an induced voltage due to magnetic flux and applies estimation calculation to own shaft rotational frequency frm_est as the rotational speed of own shaft, namely, the driving wheel shaft driven by the inverter, through the use of the detected current value (iu, iv, iw) from the current detector 5, in a speed-sensorless manner.

[0024] Although not shown in the drawing, information such as dq voltage command value Vd*, vq* or current command value id*, iq* is used appropriately depending on the estimation methods. In the case of an induction motor, for example, the frequency estimation portion 20 calculates estimated rotor angular frequency armrest by adjusting the estimated speed so as to provide a computing means using equation (1) and zero the deviation of a q-axis current. In the equation, Kp denotes the proportional gain, Ki denotes the integral gain, and s denotes the Laplace operator.

[0025] [Equation 1] (1,--1,).......( 1 ) As another example, expressed in equations (2) and (3), the frequency may be estimated by correcting the axis misalignment from the d-axis induced voltage on the dq coordinate. In the equations, Ri* denotes the primary resistance, Li* denotes the primary self-inductance, mi* denotes the primary angular frequency, o denotes the leakage coefficient, and cos* denotes the slip angular frequency. [Equation 2] Mi^est = ^p'-'^ + R j rL:i ^q) ■ --(2) [Equation 3] ^rm... est ... est ( 3 )

[0026] Various forms of estimation calculation are known depending on the types of the motor 4, such as induction motor and synchronous motor, for example. Any estimation method may be used as long as it performs estimation calculation in a sensorless manner without using a speed sensor or position sensor .

[0027] A frequency conversion portion 21 receives, as input, other shaft information 2B (other shaft speed information: vt) from the higher-order control device 110, converts the other shaft speed information (vt) into other shaft rotational frequency (before correction) frt and outputs it, using information such as a gear ratio and a standard wheel diameter .

[0028] The following describes a wheel diameter difference correction portion 22. Fig. 5 illustrates a detailed functional block diagram of the wheel diameter difference correction portion 22. The wheel diameter difference correction portion 22 receives input of own shaft rotational frequency (estimate value) frm_est and other shaft rotational frequency (before correction) frt and outputs wheel diameter difference correction coefficient K to a smoothing processing portion 30 based on the ratio (30A) between the two.

[0029] The calculation operation signal ST for the wheel diameter difference correction is active during a duration of several hundred milliseconds to several seconds (Fig. 1: T). During the duration T, the smoothing processing portion 30 receives the wheel diameter difference correction coefficient K and, each time it receives the same value, calculates the average value Kr of the accumulated values. It then outputs the calculated value to a holding portion 31. In this case, it may be advantageous to use any processes to smooth data, such as moving average or smoothing filter processes, not limited to the time-average process.

[0030] The holding portion 31 holds the average value Kr of the wheel diameter difference correction coefficient K and outputs the hold value at the time when the wheel diameter difference correction is completed and the calculation operation signal ST falls from on-state to off-state. This wheel diameter difference correction coefficient Kr is multiplied (21a) by the other shaft rotational frequency (before correction) frt to acquire the other shaft rotational frequency (after correction) frt' .

[0031] The following describes the operation of the wheel diameter difference correction based on Fig. 1. The operation timing will be explained using the waveform of t (time). Fig. 1 is a timing chart illustrating the time-course changes in the railway vehicle states from the coasting before the wheel diameter difference correction, the acceleration after the railway vehicle starts power running, the state causing the railway vehicle to coast again, and to completion of the wheel diameter difference correction.

[0032] The operation command (Fig. 4: 2A) goes high at tl to turn on the torque output of the motor 4 (power running or regeneration state), and goes low at t3 to turn off the torque of the motor 4 (coasting period). The operation signal (Fig. 5: ST) for operating the wheel diameter difference correction calculation turns on at t4 and off at t5. The PWM signal (Fig. 2: 6A) for controlling the gate signal from the gate drive circuit 6 to the inverter 3 turns on at tl, remains on even when the operation command value 2A turns off, and then turns off at t6. The inverter 3 continues to output voltage to the motor 4 while the PWM signal 6A is on. Based on the output of PWM signal 6A, the switching signal from the gate drive circuit 6 to the inverter 3 keeps the inverter 3 in the gate-on state. The period T from t4 through t5 keeps the voltage output 6A to continue for the wheel diameter difference correction.

[0033] The torque command value (11 in Fig. 4: Tm*) rises at t2, maintains a constant value, then falls at t3, and turns off at t4. The d-axis current (10 in Fig. 4: id* (excitation current)) turns on at tl, maintains a constant value, and then turns off at t6. The q-axis current (10 in Fig. 4: iq* (torque current)) rises at t2, maintains a constant value until t3, and then turns off at t4. 1r denotes an effective current value and represents a resultant value from the d-axis current and the q-axis current.

[0034] frm_est represents the waveform of the own shaft rotational frequency (estimate value). frt' represents the waveform of the other shaft rotational frequency (after correction). The wheel diameter difference correction coefficient Kr is generated at and after t5.

[0035] The operation command 2A turns on at tl. Then, the frequency estimation portion 20 performs estimation calculation on the own shaft rotational frequency (estimate value) frm_est under speed sensorless control based on the detected current value from the current detector 5. Under the speed sensorless control, the own shaft rotational frequency frm_est is inconstant before tl, before the power running (operation command: off, voltage output: off) . However, immediately after the power running starts (operation command: on, voltage output: on), the speed sensorless control function (20: frequency estimation portion) installed in the control circuit 2 starts estimating the frequency at t2, which is several tens to hundreds of milliseconds lather than tl, to settle the own shaft rotational frequency fI'm est •

[0036] At t2, the torque command value im* rises. The motor 4 rotates the wheel. The railway vehicle accelerates. If there is a wheel diameter difference between the own shaft and the other shaft, the rotational speed difference between the wheels increases in proportion to the increase in speed. Fig. 1 illustrates the case where the wheel diameter of the own shaft is smaller than that of the other shaft. The smaller the wheel diameter, the higher the wheel rotational speed (rotational frequency).

[0037] At t3, after the vehicle speed increases, the operation command 2A from the higher-order control device 110 changes from on to off, and the torque command value Tm* falls. After the torque command value falls, the motor 4, as a permanent magnet synchronous motor, triggers a charging operation due to the fact that an induced voltage caused by the magnetic flux of the magnet becomes higher than the DC voltage E of the smoothing capacitor 7. To inhibit the occurrence of the charging operation, the field weakening control may be provided to continue the voltage output (gate signal 6A: on) If the motor 4 is an induction motor, the voltage output generally stops (gate signal 6A: OFF) after the torque drops. This is because the secondary magnetic flux will disappear in a few hundred milliseconds if the excitation current (d-axis current command value) id* is not applied.

[0038] However, the control circuit 2 in Fig. 2 provides a control period (T in the drawing) to continue the voltage output (6A) for the wheel diameter difference correction after t3, thereby achieving highly accurate wheel diameter difference correction even under the speed sensorless control. During this period, the current command value operation portion 10 turns off the torque current iq* when the operation command turns off at t3. However, the voltage output 6A does not turn off and remains on after t3. The output of the excitation current id* can continue until t5 when the wheel diameter difference correction ends. During this period, the frequency estimation portion 20 can estimate the own shaft rotational frequency based on the detection value from the current detector 5 (see Fig. 4) .

[0039] During t4 to t5, the calculation operation signal ST remains on while continuing the speed estimation based on the voltage output and the speed sensorless control. During this on-state, the torque command value Tm* becomes approximately zero so as not to cause a wheel slip due to the off-state of the operation command 2A. In other words, the torque command value im* can be assumed to be approximately zero under the condition that the operation command 2A from the higher-order control device 110 turns off. Consequently, the railway vehicle moves inertially, and the wheels rotate inertially. When the motor 4 is an induction motor, the current command value operation portion 10 approximately zeros the torque current (q-axis current) iq* to approximately zero the torque while applying only the excitation current (d-axis current command value) id* to generate a magnetic flux of the motor 4. When a permanent magnet synchronous motor is used, the current command value operation portion 10 approximately zeros the torque by approximately zeroing at least the torque current (q-axis current) iq*. During the period T from t4 to t5, the wheel diameter difference correction portion 22 (Fig. 5) calculates a time-course average value for the ratio between the own shaft rotational frequency and the other shaft rotational frequency.

[0040] The calculation of the time-course average value for the ratio between the own shaft rotational frequency and the other shaft rotational frequency is performed during a coasting control period when the torque is almost zero. There are three main reasons for this. The first reason is that the own shaft may cause a slip during torque output. The second reason is to eliminate the effects of speed fluctuations that may occur while the torque rises or falls. The vehicle acceleration varies while the torque rises immediately after t2 or falls during the period from t3 to t4 . Estimation errors are likely to occur due to fluctuations in the motor's rotational frequency caused by longitudinal impulses between railway vehicles or truck vibrations, as well as delays in following speed changes under speed sensorless control. This must be avoided. The third reason is to reduce errors due to the effects of transmission delays contained in the other shaft rotational frequency by performing the calculation during the coasting control period when the torque is almost zero. The other shaft rotational frequency is often received at a transmission cycle of tens to hundreds of milliseconds. Errors due to transmission delays occur in the process of acceleration or deceleration, which increases the rate of change of speed in the other shaft rotational frequency.

[0041] As above, sufficient accuracy cannot be acquired even if the wheel diameter difference correction is performed under the condition where the estimated speed contains fluctuations or errors due to factors other than the wheel diameter difference. To reliably prevent axle slip and decrease changes in acceleration due to the mechanical influence, the control circuit 2 just needs to output voltage from the inverter 3 to the motor 4 after the operation command changes from on to off, and meanwhile, perform the wheel diameter difference correction by estimating, in a speed-sensorless manner, the rotational speed of the driving wheel shaft that inertially rotates after transition to the coasting control state in which the torque output of the motor 4 turns off.

[0042] At t5, the control circuit 2 changes the calculation operation signal (ST), for the wheel diameter difference correction, from on to off to complete the wheel diameter difference correction. At this time, the wheel diameter difference correction portion 22 illustrated in Fig. 5 allows the holding portion 31 to hold the wheel diameter difference correction coefficient Kr at the time the wheel diameter difference correction is completed. The wheel diameter difference correction coefficient Kr is updated from 1.0 before correction to an appropriate value of 500 (Fig. 1). At t5, the own shaft rotational frequency frm^est coincides with the other shaft rotational frequency frt' -

[0043] At t6, the wheel diameter difference correction is completed. The PWM control portion 14 stops the voltage output 6A. Consequently, the speed sensorless control causes the estimated own shaft frequency to be inconstant. Meanwhile, the holding portion 31 (Fig. 5) holds the wheel diameter difference correction coefficient Kr even during coasting. The subsequent power running can start under the condition of the completed wheel diameter difference correction. Demagnetization control can be appropriately performed immediately before the gate stop (t6).

[0044] It may be advantageous to correct the wheel diameter difference when the vehicle travels at a specified speed or higher (such as 30% or higher of the maximum speed). A frequency difference due to the wheel diameter difference between the own shaft and the other shaft is proportional to the railway vehicle's traveling speed. Sufficient accuracy cannot be acquired when the wheel diameter difference correction is performed at low speeds. The wheel diameter difference correction coefficient Kr contains an error. It may be advantageous to set the specified speed so that a frequency difference results from the wheel diameters of the own shaft and the other shaft.

[0045] As above, the wheel diameter difference correction portion 22 calculates the wheel diameter difference correction coefficient based on the frequency ratio. Alternatively, the coefficient may be calculated based on the rotational speed ratio. The wear of the wheel diameter does not change substantially after the railway vehicle travels for about a day. After the railway vehicle starts commercial operation, the wheel diameter difference correction portion 22 once completes the wheel diameter difference correction. The wheel diameter difference correction portion 22 holds the wheel diameter difference correction coefficient until the power supply to the control circuit 2 turns off. After that, the control circuit 2 may omit steps t4 to t6 and not need to perform the wheel diameter difference correction.

[0046] The operation command 2A may turn off at t3 and then turn on during the period T from t4 to t5. In such a case, the wheel diameter difference correction portion 22 suspends the wheel diameter difference correction. The control circuit 2 transitions to the normal operation of power running or regeneration. The estimated speed is known (Fig. 5: frequency estimation portion 20) during the period from t4 to t5. The period from tl to t2 does not need a period to converge the estimate value. The control circuit 2 quickly transitions to power running or regeneration.

[0047] The railway vehicle driving device in Fig. 2 is configured to drive one motor 4 using one inverter (1C1M). If the motor 4 is an induction motor, it may be advantageous to drive multiple motors 4 using one inverter (such as 1C2M or 1C4M). When the present invention is applied to a system that drives multiple motors, the wheel diameter difference correction can be performed by comparing an average estimated frequency (own shaft rotational frequency) of multiple motors 4 with the other shaft rotational frequency.

[0048] The control circuit 2 highly accurately achieves the wheel diameter difference correction even under the speed sensorless control by utilizing the coasting period with a focus on the railway vehicle's driving pattern that repeats acceleration, coasting, and deceleration at a predetermined frequency .

[0049] The explanation of Fig. 4 continues. A slip detection portion 23 in Fig. 4, also illustrated in Fig. 6 as its detailed block diagram, calculates a difference between the own shaft rotational frequency (estimate value) frm_est and the other shaft rotational frequency (after correction) frt' and compares absolute value XI, found by processing the result using the abs function, with the detection set value X2 . The absolute value XI of the difference between the own shaft rotational frequency frm_est and the other shaft rotational frequency (after correction) frt' may be greater than or equal to the detection set value X2. In such a case, the slip detection portion 23 determines that the drive wheel of the own shaft slips, and outputs a slip detection signal DI.

[0050] The detection set value is set so as not to accidentally detect a slip. This value will be large if the wheel diameter difference correction is less accurate. An increase in the detection set value delays the slip detection. It may be advantageous to set the detection set value as small as possible within a scope that does not cause a false detection.

[0051] The other shaft rotational frequency used for the slip detection portion 23 is favorably based on the speed of the non-driving wheel shaft (T shaft). When driving wheel shafts (M shafts) are used together, both M shafts may slip simultaneously. The method of detecting slips based on a speed difference between the own shaft (M shaft) and the other shaft (T shaft) is effective for slips that occur slowly and continuously. The slip detection portion 23 is not limited to this method. To detect a rapidly increasing slip, the slip detection portion 23 may calculate the wheel acceleration based on frequency differential values of the own shaft (M shaft) and detect the slip when the acceleration reaches a predetermined value or more. It may be advantageous to use multiple detection methods, including other detection methods.

[0052] The following describes the re-adhesion operation after the axle slips (slip re-adhesion portion 24 in Fig. 4) by referencing Fig. 7. Fig. 7 illustrates the own shaft rotational frequency (estimate value) frm_est and the other shaft rotational frequency (after correction) frt', which are input to the slip detection portion 23. When the adhesion coefficient of the road surface decreases due to rain, for example, the driving wheel shaft (M shaft) slips due to torque exceeding the maximum adhesive force. The slip detection portion 23 outputs the slip detection signal DI (OFF -+ ON) at the timing when a frequency difference between the own shaft and the other shaft exceeds the detection set value S.

[0053] At the timing when the slip detection signal ST is input, the slip re-adhesion control portion 24 outputs a torque operation quantity signal Aim* to the torque command value operation portion 11 illustrated in Fig. 4 so that the torque command value im* narrows down as illustrated in Fig. 7. This makes it possible to decrease the slip occurring between the wheel and the rail, thereby re-adhering the drive shaft to the rail.

[0054] The wheel diameter difference correction and the slip readhesion control have been explained in terms of the slip occurring during power running. The same applies to the skid occurring during regeneration. According to the above configuration, the control circuit 2 can highly accurately correct the wheel diameter difference, even under speed sensorless control, and prevent false slip detection as early as possible.

[0055] [Second Embodiment] As illustrated in the block diagram of Fig. 8, the second embodiment of the present invention differs from the first embodiment in that the wheel diameter difference correction portion 22 includes a variation determination portion 32. The variation determination portion 32 receives input of a wheel diameter difference correction coefficient (intermediate value) signal K and the calculation operation signal ST, and outputs a normal variation signal K2 to the holding portion 31.

[0056] During the period when the wheel diameter difference correction portion 22 corrects the wheel diameter, the own shaft rotational frequency or the other shaft rotational frequency may fluctuate due to a shock caused by rail joints or pushing between the vehicles. In such a case, the wheel diameter difference correction value may contain an error. Fig. 9 is a waveform diagram for explaining the operation of the variation determination portion 32. The wheel diameter difference correction portion 22 determines whether the wheel diameter difference correction coefficient (intermediate value) K is normal, namely, whether it is included in a predetermined threshold range RI. Fig. 9 illustrates that K exceeds the threshold range RI downward at t4a between t4 and t5 .

[0057] Fig. 9 also illustrates the waveforms of the calculation operation signal ST and the normal variation signal K2 for the wheel diameter difference correction. The calculation operation signal ST turns on at t4, and then turns off at t5. The wheel diameter difference correction portion 22 turns on the normal variation signal K2 based on the on-state of the calculation operation signal ST. While the calculation operation signal ST is on, the wheel diameter difference correction portion 22 changes the normal variation signal K2 from on to off at the time (t4a) when the wheel diameter difference correction coefficient (intermediate value) K exceeds the threshold range RI.

[0058] When correcting the wheel diameter difference, the wheel diameter difference correction portion 22 stores the wheel diameter difference correction coefficient Kr from the smoothing processing portion 30 in the holding portion 31. If the normal variation signal K2 is on, the correction coefficient Kr is enabled and stored. If the normal variation signal K2 is off, the correction coefficient Kr is disabled and not stored. Based on this configuration, the wheel diameter difference correction portion 22 excludes the wheel diameter difference correction coefficients during a period in which the acceleration varies significantly due to a steep gate gradient or activated mechanical braking. It is possible to exclude conditions of unstable frequency values and achieve a highly accurate wheel diameter difference correction.

[0059] [Third Embodiment] The following describes the third embodiment of the present invention. This embodiment differs from the previously described embodiments in that, as illustrated in Fig. 10, the slip detection portion 23 includes a slip detection set value setting portion 25. Fig. 10 is a functional block diagram illustrating the details of the slip detection portion 23. The wheel diameter difference correction portion 22 outputs a wheel diameter difference correction completion flag Fl upon completion of the wheel diameter difference correction.

[0060] The slip detection set value setting portion 25 accepts input of the absolute value ( | frm_estI ) of the own shaft rotational frequency (estimate value) by using the abs function and the wheel diameter difference correction completion flag Fl, and outputs the slip detection set value (reference value) X2 . When the wheel diameter difference correction completion flag Fl is 0 (before completion of the wheel diameter difference correction), the slip detection set value setting portion 25 outputs the slip detection set value X2 corresponding to the absolute value ( I frm_est I ) of the own shaft rotational frequency (estimate value) according to the characteristic (a) in Fig. 11. When the wheel diameter difference correction completion flag Fl is 1 (after completion of the wheel diameter difference correction), the slip detection set value setting portion 25 outputs the slip detection set value X2 corresponding to the absolute value ( Ifrm_est I ) of the own shaft rotational frequency (estimate value) according to the characteristic (b) in Fig. 11.

[0061] The characteristic (a) corresponds to the case of the maximum wheel diameter difference between the own shaft and the other shaft according to the wheel specifications. For example, suppose the maximum wheel diameter is 860 mm and the minimum is 780 mm. Then, X2 denotes a frequency difference caused by the maximum wheel diameter difference of 80 mm.

[0062] The characteristic (b) considers the accuracy of the wheel diameter difference correction. For example, if the wheel diameter difference correction can be performed to an accuracy of within X mm, X2 denotes a frequency difference caused by the wheel diameter difference (X mm). The other shaft rotational frequency signal includes a transmission delay from the higher-order control device 110 (Fig. 2). Then, the slip detection set value setting portion 25 settles the slip detection set value X2, considering the effect of the above-described transmission delay under the condition of varying frequencies during acceleration or deceleration of the vehicle, as well as frequency differences caused by the resolution (quantization) of the other shaft rotational frequency signal. It is possible to prevent false detection of slips due to delay by providing both characteristics (a) and (b) with lower limits in consideration of the above.

[0063] The above-described configuration can settle appropriate slip detection set values for each speed range before and after completion of the wheel diameter difference correction. It is possible to prevent false slip detection and detect slips early according to the speed range.

[0064] The following describes the fourth embodiment of the present invention. Fig. 12 is a detailed block diagram of the control circuit 2 according to the present embodiment. The difference from the block diagram (Fig. 4) of the previously described embodiment is that the other shaft rotational frequency (after correction) frt' is input to the frequency estimation portion 20. When the coasting railway vehicle restarts power running or regeneration, the frequency estimation portion 20 uses the other shaft rotational frequency (after correction) frt', as an initial value for the own shaft rotational frequency (estimate value).

[0065] The following describes the operation of the fourth embodiment based on the waveform diagram illustrated in Fig. 13. Fig. 13 is a timing chart of waveforms when the power running is restarted to accelerate the vehicle from its coasting state after completion of the wheel diameter difference correction. Comparison with the waveform diagram in Fig. 1 helps understand the characteristics in Fig. 13. When the wheel diameter difference correction is completed at time t5 as illustrated in Fig. 1, the own shaft rotational frequency and the other shaft rotational frequency (after correction) can coincide while the vehicle is coasting. As indicated by Kr corresponding to frm^est and frt' in Fig. 13, the wheel diameter difference correction portion 22 can allow the own shaft rotational frequency (estimate value) frm_est and the other shaft rotational frequency (after correction) frt' to coincide from tn immediately after the start of power running. It is possible to achieve the effect of shortening the time required to converge an estimated speed immediately after the restart from coasting, as well as reducing a torque shock.

[0066] The other shaft rotational frequency (after correction) is not always used as an alternative to speed sensorless control, but is used only as an estimated initial value. This is because the other shaft rotational frequency is received during transmission, for example, causing communication delays or quantization errors, as described in the third embodiment. The control of the motor 4 for railway vehicle use is required to be able to estimate speeds even in situations where the rotor frequency varies steeply due to slips, for example. It is effective to use the other shaft rotational frequency (after correction) only as an estimated initial value.

[0067] As above, the railway vehicle driving device according to the fourth embodiment uses the other shaft rotational frequency (after correction) as the estimated initial value for the speed sensorless control. Compared to the third embodiment, it is possible to more effectively reduce a torque shock caused by restarting the motor from the coasting control state and shorten the restart time.

[0068] [Fifth Embodiment] The following describes the fifth embodiment. According to the fifth embodiment, as illustrated in the block diagram of Fig. 14, the higher-order control device 110 of the railway vehicle 100 transmits and receives data from a communication server 120. In Fig. 14, the control circuit 2 transmits wheel diameter information 2A-1, acquired by the wheel diameter difference correction, to the higher-order control device 110. The higher-order control device 110 transmits slip information to the communication server 120 by using a wireless communication means such as Wi-Fi.

[0069] The wheel diameter information of each shaft is transmitted to the communication server 120 to store data. The communication server 120 can analyze whether the wheel diameter difference in the truck or vehicle falls within a specified value, based on the daily variations in the wheel diameter. The changing pattern of wheel diameter wear volume can also be used to predict the optimal time for wheel turning, making it possible to provide efficient maintenance on wheels. The drive system 1 may include a wireless device that transmits data to the communication server 120.

[0070] As above, the railway vehicle driving device according to the fifth embodiment transmits wheel diameter information acquired by the wheel diameter difference correction to the communication server 120. The communication server 120 can thereby confirm the likelihood of a wheel diameter difference in the truck or vehicle, referring to a specified value, and predict the time when the specified value will be exceeded.

[0071] While the preferred embodiments of the present invention have been described, it is to be distinctly understood that the technical scope of the present invention is not limited to the scope of the embodiments described above. It would have been obvious to one of ordinary skill in this art to be able to variously modify or improve the above-described embodiments. As is clear from the description of the appended claims, the technical scope of the present invention can also include the modified or improved embodiments. List of Reference Signs

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

Claims

1. A railway vehicle driving device comprising:an inverter that outputs a voltage to a motor; anda control device that adjusts the torque of the motor by adjusting voltage output of the inverter based on an operation command from a higher-level control device,wherein the control device outputs a voltage from the inverter to the motor, and meanwhile, estimates, in a speedsensorless manner, a rotational speed of a driving wheel shaft inertially rotating during coasting control that turns off torque from the motor, and corrects a wheel diameter difference of the drive shaft from another shaft based on an estimated rotational speed of the drive shaft.

2. The railway vehicle driving device according to Claim 1, wherein the control device corrects a wheel diameter difference between the drive shaft and the other shaft based on an estimated rotational speed of the drive shaft and a rotational speed of the other shafts, including a non-drive shaft.

3. The railway vehicle driving device of Claim 1 or 2, wherein the control device continues to output voltage from the inverter to the motor and transitions to the coasting control after the operation command changes from on to off.

4. The railway vehicle driving device according to any one of Claims 1 through 3, further comprising:a gate drive circuit that outputs a gate signal for driving the motor based on a command value for voltage output from the inverter to the motor,wherein the control device causes the gate drive circuit to output the gate signal after the operation command changes from on to off, and transitions to the coasting control while maintaining a gate-on state of the inverter.

5. The railway vehicle driving device according to any one of claims 1 through 4, wherein the control device calculates an estimated rotational speed of the drive shaft from the detection value of a current flowing through the motor, based on the continuation of voltage output from the inverter to the motor, and corrects a wheel diameter difference between the drive shaft and the other shaft.

6. The railway vehicle driving device according to any one of Claims 1 through 5, wherein the control device calculates a torque current and an excitation current based on a torque command value of the operation command, approximately zeros the torque current after the operation command changes from on to off, maintains the excitation current until correction of the wheel diameter difference, and allows the inverter to output a voltage based on the excitation current to the motor.

7. The railway vehicle driving device according to any one of Claims 1 through 6, wherein the control device corrects the wheel diameterdifference when a railway vehicle travels at a speed higher than or equal to a predetermined speed; andwherein the predetermined speed is set to cause a difference between the drive shaft and the other shaft in rotational frequencies based on wheel diameters.

8. The railway vehicle driving device according to any one of Claims 1 through 7, wherein, when the ratio between an estimated rotational speed of the drive shaft and a rotational speed of the other shaft falls outside a threshold range during a time-course variation, the control device does not use the ratio, falling outside the threshold range, for correction of the wheel diameter difference.

9. The railway vehicle driving device according to any one of Claims 1 through 8, wherein the control device determines whether the drive wheel slips, according to the comparison with a reference value, based on an estimated rotational speed of the drive shaft and a rotational speed of the other shaft and changes the reference value before and after correction of the wheel diameter difference.

10. The railway vehicle driving device according to any one of Claims 1 through 9, wherein, when a railway vehicle restarts powered running from coasting, the control device uses the rotational speed of the other shaft after correction of the wheel diameter difference, as the initial value for an estimated rotationalspeed of the drive shaft.

11. The railway vehicle driving device according to any one of Claims 1 through 10, wherein the higher-level control device is coupled to a server .

12. A control method for a railway vehicle driving device, which adjusts voltage output from an inverter to adjust the torque of a motor, based on an operation command from a higher-level control device, comprising:outputting a voltage from the inverter to the motor, and meanwhile, estimating, in a speed-sensorless manner, a rotational speed of a driving wheel shaft inertially rotating during coasting control that turns off torque from the motor, andcorrecting a wheel diameter difference of the drive shaft from another shaft based on an estimated rotational speed of the drive shaft.

13. The control method for a railway vehicle driving device according to Claim 12, comprising:correcting a wheel diameter difference between the drive shaft and other shafts based on an estimated rotational speed of the drive shaft and a rotational speed of other shafts including a non-drive shaft.

14. The control method for a railway vehicle driving device according to Claim 12 or 13, comprising: continuing to output voltage from the inverter to themotor and transitioning to the coasting control, after the operation command changes from on to off.

15. The control method for a railway vehicle driving device according to any one of Claims 12 through 14, comprising:outputting a gate signal for driving the motor based on a command value for voltage output from the inverter to the motor; andafter the operation command changes from on to off, allowing a gate drive circuit to output a gate signal to transition to the coasting control while maintaining a gate-on state of the inverter.

16. The method for controlling a railway vehicle driving device according to any one of Claims 12 through 15, comprising :finding an estimated rotational speed of the drive shaft from the detection value of a current flowing through the motor, based on the continuation of voltage output from the inverter to the motor, and correcting a wheel diameter difference between the drive shaft and the other shaft.

17. The method for controlling a railway vehicle driving device according to any one of Claims 12 through 16, comprising :calculating a torque current and an excitation current based on a torque command value of the operation command, approximately zeroing the torque current after the operation command changes from on to off, maintaining the excitation current until correction of the wheel diameter difference, andallowing the inverter to output a voltage based on the excitation current to the motor.

18. The method for controlling a railway vehicle driving device according to any one of Claims 12 through 17, comprising :correcting the wheel diameter difference when a railway vehicle travels at a speed higher than or equal to a predetermined speed; andqp t t i n n t~ Fi o nrpdptprrninpH q yp p* p* H c a i i q p* ,a diffprprir’PCj C- I— l— —1— X X C' X X K-z -X- CX C- C. C. _X_ X LI —X_ X X C- CX kJ) JC-* C- C- tX v—< CX CX Cj CX CX —I— _X_ _X_ X- X X v-z VCbetween the drive shaft and the other shaft in rotational frequencies based on wheel diameters.

19. The method for controlling a railway vehicle driving device according to any one of Claims 12 through 18, comprising :when the ratio between an estimated rotational speed of the drive shaft and a rotational speed of the other shaft falls outside a threshold range during a time-course variation, not using the ratio, falling outside the threshold range, for correction of the wheel diameter difference. [Claim 2 0]The method for controlling a railway vehicle driving device according to any one of Claims 12 through 19, comprising :determining whether the drive wheel slips, according to the comparison with a reference value, based on an estimated rotational speed of the drive shaft and a rotational speed of the other shaft, andchanging the reference value before and after correctionof the wheel diameter difference.

21. The method for controlling a railway vehicle driving device according to any one of Claims 12 through 20, comprising :when a railway vehicle restarts powered running from coasting, using the rotational speed of the other shaft after correction of the wheel diameter difference, as the initial value for an estimated rotational speed of the drive shaft.INTERNATIONAL SEARCH REPORT International application No. PCT / JP2024 / 031281A. CLASSIFICATION OF SUBJECT MATTER B60L 3 / 08(2006.01)1; B60L 9 / 18(2006.01)1; B61C 17 / 12(2006.01)1 FI: B60L3 / 08 G; B60L9 / 18 A; B61C17 / 12 According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) B60L3 / 08; B60L9 / 18: B61C17 / 12 Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Published examined utility model applications of Japan 1922-1996 Published unexamined utility model applications of Japan 1971-2024 Registered utility model specifications of Japan 1996-2024 Published registered utility model applications of Japan 1994-2024 Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. Y JP 2001-145207 A (HITACHI, LTD.) 25 May 2001 (2001-05-25) paragraphs [0012]-[0020], fig. 1-3 1-21 Y WO 2020 / 250742 Al (HITACHI, LTD.) 17 December 2020 (2020-12-17) paragraphs [0004], [0061] 1-21 Y JP 2017-135790 A (HITACHI, LTD.) 03 August 2017 (2017-08-03) abstract, paragraphs [0012]-[0014], fig. 1 5-11, 16-21 A JP 2008-79418 A (KABUSHIKI KAISHA TOSHIBA) 03 April 2008 (2008-04-03) entire text 1-21 A WO 2016 / 135858 Al (MITSUBISHI ELECTRIC CORPORATION) 01 September 2016 (2016-09-01) entire text 1-21 | - / | Further documents are listed in the continuation of Box C. | V | See patent family annex. * Special categories of cited documents: “A” document defining the general state of the art which is not considered to be of particular relevance “D” document cited by the applicant in the international application ,4E” earlier application or patent but published on or after the international filing date •4L” document which may throw doubts on priority claim(s) or which is cited to establish the publication date of another citation or other special reason (as specified) “O” document referring to an oral disclosure, use, exhibition or other means “P” document published prior to the international filing date but later than the priority date claimed “T” later document published after the international filing date or priority date and not in conflict with the application but cited to understand the principle or theory underlying the invention “X” document of particular' relevance; the claimed invention cannot be considered novel or cannot be considered to involve an inventive step when the document is taken alone “Y” document of particular relevance; the claimed invention cannot be considered to involve an inventive step when the document is combined with one or more other such documents, such combination being obvious to a person skilled in the art document member of the same patent family Date of the actual completion of the international search Date of mailing of the international search report 08 November 2024 19 November 2024 Name and mailing address of the ISA / JP Authorized officer Japan Patent Office (ISA / JP) 3-4-3 Kasumigaseki, Chiyoda-ku, Tokyo 100-8915 Japan Telephone No.

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