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EP-4380039-B1 - ELECTRIC MOTOR DRIVE DEVICE, AND ELECTRIC MOTOR DRIVE METHOD

EP4380039B1EP 4380039 B1EP4380039 B1EP 4380039B1EP-4380039-B1

Inventors

  • HATSUSE, WATARU
  • KUNIHIRO, NAOKI
  • KANAZAWA, Tomomi

Dates

Publication Date
20260513
Application Date
20220623

Claims (9)

  1. An electric motor drive device comprising: an inverter (3) that drives an electric motor (1); a current detecting circuit (4) that detects a current of the electric motor (1); and a control device (2) that controls the inverter (3) based on a torque command value for the electric motor (1) and a current detected value from the current detecting circuit (4), wherein the control device (2) changes a torque command reduced speed for the electric motor (1) based on a wheel slip/skidding detection signal that has detected occurrence of wheel slip or skidding of the electric motor (1) and a change rate of the torque command value, and throttles torque of the electric motor (1).
  2. The electric motor drive device according to claim 1, wherein the torque command reduced speed is set to a value equal to or lower than a predetermined upper limit value.
  3. The electric motor drive device according to claim 1 or 2, wherein the control device (2) uses, for setting of the torque command reduced speed, one of a table and a function, the table storing a relationship between the torque command reduced speed and the change rate of the torque command value, the function representing the relationship.
  4. The electric motor drive device according to any one of claims 1, 2, and 3, wherein a change rate of an absolute value of the torque command value is used as the change rate of the torque command value.
  5. A railway vehicle comprising the electric motor drive device according to any one of claims 1, and 2 to 4.
  6. An electric motor drive method comprising: controlling an inverter (3) that drives an electric motor (1) based on a torque command value for the electric motor (1) and a current detected value of the electric motor (1); and changing, when wheel slip or skidding occurs in the electric motor (1), a torque command reduced speed for the electric motor (1) based on a detection signal that has detected occurrence of the wheel slip or skidding and a change rate of the torque command value, and throttling torque of the electric motor (1).
  7. The electric motor drive method according to claim 6, wherein the torque command reduced speed is set to a value equal to or lower than a predetermined upper limit value.
  8. The electric motor drive method according to claim 6 or 7, wherein the torque command reduced speed is set using one of a table and a function, the table storing a relationship between the torque command reduced speed and the change rate of the torque command value, the function representing the relationship.
  9. The electric motor drive method according to any one of claims 6, 7, and 8, wherein a change rate of an absolute value of the torque command value is used as the change rate of the torque command value.

Description

Technical Field The present invention relates to a drive device and a drive method for driving an electric motor, and is particularly suitable as a drive device and a drive method for driving an electric motor mounted on a railway vehicle. Background Art A railway vehicle rotates wheels, which are drive wheels, by torque of a rotary electric machine, and accelerates the vehicle by a tangential force generated on the wheels as a reaction force that a wheel tread surface receives from a rail. This tangential force varies depending on the tangential force coefficient µ representing the adhesion state between the wheels and the rails, and when the torque of the wheels becomes excessively larger than the tangential force, only the force for rotating the wheels increases while the force for accelerating the vehicle remains small. As a result, wheel slip or skidding of the wheels (hereinafter, also abbreviated as "wheel slip/skidding") occurs. In particular, when it rains or it snows, the coefficient of adhesion greatly decreases, so that wheel slip/skidding is likely to occur. When such wheel slip/skidding occurs, re-adhesion control is performed in which the torque generated by the electric motor is reduced to control to a re-adhesion state smaller than the tangential force (for example, PTLs 1, 2, and 3). Furthermore, PTL 4 discloses a traction control system for electric vehicles, such as locomotives. The system according to PTL 4 addresses wheel slip by limiting the rate at which the excitation frequency of the motor can change. This rate limit is applied when the measured wheel creep exceeds a predefined threshold, with the goal of preventing excessive slip and improving stability. PTL 5 also discloses a traction control system for railway vehicles, wherein its method involves switching between two distinct control modes. That is, the system moves from a standard set of slip-detection thresholds to a second set after detecting that torque has been throttled frequently, indicating rather poor rail conditions. Furthermore, PTL 6 discloses a control method for an electric vehicle to prevent motor and inverter overheating when held stationary on an incline. To mitigate a current concentration state caused by a prolonged hill-hold, the system intentionally reduces motor torque to induce a slight rollback. This rotation shifts the concentrated current to a different motor phase, wherein the rate of this torque reduction is controlled based on the accelerator pedal position. Citation List Patent Literatures PTL 1: JP 2000-358302 APTL 2: JP 2013-188009 APTL 3: JP 2019-201459 APTL 4: US 8 988 016 B2PTL 5: JP 6 730 057 B2PTL 6: JP 2008-167632 A Summary of Invention Technical Problem PTLs 1, 2, and 3 describe techniques related to re-adhesion control, but the techniques described in PTLs 1 and 2 mainly aim at re-adhesion configuration such as improvement of adhesion utilization and setting of throttle torque, and do not mention the speed of torque reduction after wheel slip/skidding detection. In addition, in the method described in PTL 3, a configuration in which the speed of torque reduction after the wheel slip/skidding detection is reduced with reference to the acceleration of the wheels is described, but the torque reduced speed is easily affected by noise of the rotation speed, and the use of a first order lag filter or the like causes a problem that the structure becomes complicated. An object of the present invention is to provide an electric motor drive device and an electric motor drive method capable of appropriately changing a torque reduced speed after wheel slip/skidding detection with a simple configuration. Solution to Problem The invention is set out in the appended set of claims. Preferable embodiments are defined in the dependent claims. Advantageous Effects of Invention According to the present invention, since the torque command reduced speed is changed with reference to the torque command value, the torque command reduced speed is less susceptible to noise, and re-adhesion control can be performed with a simple configuration without using a first order lag filter or the like. In addition, by appropriately reducing the torque, it is possible to suppress rotational speed fluctuation at the time of wheel slip/skidding. Problems, configurations, and effects other than those described above will become apparent by the following description of an embodiment. Brief Description of Drawings [FIG. 1] FIG. 1 is a block diagram illustrating an overall configuration of an electric motor drive device according to the present embodiment.[FIG. 2] FIG. 2 is a diagram illustrating an outline of operation waveforms at the time of general wheel slip detection and re-adhesion control when wheel slip occurs.[FIG. 3] FIG. 3 is a diagram illustrating a relationship between electric motor torque and a rotor frequency when wheel slip occurs.[FIG. 4] FIG. 4 is a block diagram illustrating a configuration of a torque reducti