Chassis dynamometer

Abstract

The objective of the present invention is to provide a chassis dynamometer that suppresses resonance and vibration phenomena, without changing the mechanical structure of the chassis dynamometer. An inverter (4) of a chassis dynamometer (1) according to the present disclosure includes: a notch filter (40) that attenuates a signal in an attenuation target frequency band including the mechanical natural frequency of the chassis dynamometer 1, from a rotation command signal (S3), and outputs a rotation command signal (S3A); a secondary HPF (45) that passes signals in a high-frequency band including the mechanical natural frequency, among an encode signal (S7), to obtain an encode signal (S7A); a subtractor (47B) that subtracts the encode signal (S7A) from the rotation command signal (S3A) to obtain a rotation command signal (S3B); and a roller drive control unit (RC) that generates a drive control signal (S4) on the basis of the rotation command signal (S3B).

Description

Chassis dynamometer

[0001] The present disclosure relates to a chassis dynamometer used for various running tests of vehicles.

[0002] A conventional chassis dynamometer is used when conducting running tests of a vehicle (automobile), and includes a roller device as a main component.

[0003] A conventional chassis dynamometer is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-222999.

[0004] The conventional chassis dynamometer disclosed in Patent Document 1 simulates a state in which a four-wheel drive vehicle, which is a test vehicle, turns on a road at a preset steering angle and test speed.

[0005] Furthermore, as a conventional control device for a chassis dynamometer, for example, there is a control device for a chassis dynamometer disclosed in Patent Document 2.

[0006] The conventional chassis dynamometer control device disclosed in Patent Document 2 suppresses the natural vibration of the oscillator of the dynamometer itself by providing a natural vibration suppression control circuit equipped with a differential compensator.

[0007] Japanese Patent Application Laid-Open No. 63-148140 Patent No. 6369596

[0008] In conventional chassis dynamometers, such as the chassis dynamometer disclosed in Patent Document 1, there was a problem in that when the mechanical natural frequency of the chassis dynamometer and the control frequency of the control signal used by the chassis dynamometer's control device match, a resonance / vibration phenomenon occurs in which the chassis dynamometer resonates and vibrates.

[0009] When the above-described resonance / vibration phenomenon occurs, there is a limit to how much the control response of the control device can be improved during test adjustments in running tests, because there is a trade-off between the control response and the resonance / vibration phenomenon.

[0010] In conventional chassis dynamometers, when the above-mentioned resonance and vibration phenomenon occurs during test adjustment for a running test, the mechanical structure of the chassis dynamometer is modified to change the machine natural frequency.

[0011] During test adjustment, mechanical structural changes to the chassis dynamometer are generally undesirable because they would result in a significant increase in cost, since the chassis dynamometer is already in a completed stage at the time of test adjustment.

[0012] Furthermore, the conventional chassis dynamometer control device disclosed in Patent Document 2 is also insufficient in suppressing the above-mentioned resonance and vibration phenomena.

[0013] As described above, conventional chassis dynamometers have had the problem that they are unable to sufficiently suppress the above-mentioned resonance and vibration phenomena without modifying the mechanical structure of the chassis dynamometer.

[0014] The present disclosure aims to solve the above-mentioned problems and provide a chassis dynamometer that suppresses resonance and vibration phenomena without making any mechanical structural changes to the chassis dynamometer.

[0015] A chassis dynamometer according to the present disclosure is a chassis dynamometer having rollers on which vehicle tires are placed, the chassis dynamometer comprising: an inverter that has a machine natural frequency, receives a rotation command signal indicating a target rotation speed, and outputs a drive control signal based on the rotation command signal; a roller drive motor that rotationally drives the roller based on the drive control signal; and an encoder that detects the motor rotation speed of the roller drive motor and obtains an encode signal indicating the detected rotation speed, the inverter including a notch filter that attenuates signals in an attenuation target frequency band that includes the machine natural frequency from the rotation command signal to obtain a first filtered rotation command signal; a second-order HPF that passes signals in a high frequency band that includes the machine natural frequency from the encode signal to obtain a subtraction encode signal; a first subtractor that subtracts the subtraction encode signal from the first filtered rotation command signal to obtain a second filtered rotation command signal; and a roller drive control unit that generates the drive control signal based on the second filtered rotation command signal, using the encode signal as a feedback signal.

[0016] The roller drive control section of the inverter in the chassis dynamometer of the present disclosure uses the second filtered rotation command signal as a control input signal for generating a drive control signal.

[0017] The first filtered rotation command signal is a signal in which machine natural frequency components are suppressed compared to the rotation command signal due to filtering by the notch filter, and the second filtered rotation command signal is a signal in which machine natural frequency components are further suppressed from the first filtered rotation command signal due to subtraction by the first subtractor.

[0018] In other words, the second filtered rotation command signal is a signal in which the machine natural frequency components are suppressed in two stages from the rotation command signal, and therefore the machine natural frequency components contained in the second filtered rotation command signal, which is the control input signal, can be effectively suppressed.

[0019] As a result, the chassis dynamometer of the present disclosure can suppress resonance and vibration phenomena and control the drive of the roller drive motor by using the second filtered rotation command signal as a control input signal for the roller drive control unit without making any mechanical structural changes to the chassis dynamometer. Note that resonance and vibration phenomena occur when the mechanical natural frequency of the chassis dynamometer matches the frequency of the control input signal.

[0020] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0021] The present invention relates to a chassis dynamometer, and is a perspective view showing a configuration after a vehicle is placed on the chassis dynamometer. The present invention also relates to a chassis dynamometer, and is an explanatory diagram showing a control system for the chassis dynamometer.

[0022] <Embodiment> (Overall Configuration) Fig. 1 is a perspective view of a chassis dynamometer 1 according to this embodiment, showing a schematic configuration after a vehicle 60 is placed on it. Fig. 1 shows an XYZ Cartesian coordinate system.

[0023] 1, four tires 6 of a vehicle 60 are placed on the roller pairs 20 of four roller devices 2. Each roller device 2 has a roller pair 20 on which the tire 6 of the vehicle 60 is placed. Furthermore, when testing the vehicle 60, the vehicle 60 is fixed in place on the roller pairs 20 of the four roller devices 2 by a vehicle fixing means (not shown).

[0024] A rectangular image simulator 62, whose longitudinal direction is in the X direction and whose lateral direction is in the Z direction, is provided on the floor surface 50 in front of the vehicle 60 (+Y direction). The image simulator 62, which is a simulation auxiliary member, has a display function for displaying the entire scenery that can be visually recognized from the vehicle 60.

[0025] The vehicle 60 may also have an external sensor (not shown). Possible external sensors include radar and lidar (LiDAR) used as corner sensors, side cameras (side electronic mirrors), and the like.

[0026] The chassis dynamometer 1 uses steering angle information of the tires 6 of the vehicle 60, an image simulator 62, etc. as needed, and receives information from the external sensors of the vehicle 60 as needed, and performs a running test on the vehicle 60. The running test includes a test involving a tire turning operation in which the tires 6 of the vehicle 60 are turned, and a roller turning operation in which the roller pairs 20 are turned in accordance with the tire turning operation.

[0027] The four rollers are classified into a first-class left roller for placing the front left tire, a first-class right roller for placing the front right tire, a second-class left roller for placing the rear left tire, and a second-class right roller for placing the rear right tire. In Figure 1, four roller pairs 20 are shown as the four rollers.

[0028] (Rotational Drive System) FIG. 2 is an explanatory diagram that schematically shows the rotational drive system of the rollers in the chassis dynamometer 1 of this embodiment.

[0029] As shown in the figure, the chassis dynamometer 1 includes, as its main components, a dynamo control device 2, a motor drive device 4X, a roller drive motor 5, and an encoder 7. The dynamo control device 2 includes, as its main component, a rotation controller 3X.

[0030] The roller drive mechanism RD is composed of a combination of the motor drive device 4X, the roller drive motor 5, and the encoder 7. The roller drive motor 5 is rotatably connected to a corresponding one of the four rollers. Although one set of roller drive mechanisms RD is shown in Figure 2, in reality, four sets of roller drive mechanisms RD are provided corresponding to the four rollers.

[0031] As shown in FIG. 2, the rotation controller 3X receives a set rotation speed signal S1 indicating a target rotation speed from the outside, and outputs a rotation command signal S3 to the motor drive device 4X to rotate the roller drive motor 5 at the target rotation speed indicated by the set rotation speed signal S1.

[0032] The encoder 7 detects the motor rotation speed of the roller drive motor 5 and obtains an encode signal S7 indicating the detected rotation speed, which is output to the motor drive device 4X.

[0033] The motor drive device 4X outputs a drive control signal S4 based on the rotation command signal S3 and using the encode signal S7 as a feedback signal, and the roller drive motor 5 is rotated by this drive control signal S4.

[0034] Therefore, when the roller drive motor 5 performs a rotational operation in response to the drive control signal S4 from the motor drive device 4X, the roller drive motor 5 can drive the corresponding roller to rotate.

[0035] (Control System) Figure 3 is an explanatory diagram that schematically shows the control system of the chassis dynamometer 1 of this embodiment. In the control system shown in Figure 3, a PLC (Programmable Logic Controller) 3 is used as the rotation controller 3X shown in Figure 2, and an inverter 4 is used as the motor drive device 4X.

[0036] As shown in the figure, the control system of the chassis dynamometer 1 mainly comprises a PLC 3, an inverter 4, and a current sensor 8. The current sensor 8 may be provided within the inverter 4.

[0037] The PLC 3 receives the set rotation speed signal S1 and outputs a rotation command signal S3 indicating a target rotation speed based on the set rotation speed signal S1. The rotation command signal S3 may be the set rotation speed signal S1 itself or a signal obtained by performing control processing on the set rotation speed signal S1. The control processing signal may be, for example, a signal obtained by performing PI control or the like on the set rotation speed signal S1 using the encode signal S7 as a feedback signal. Note that PI control or the like includes an ATR (Automatic Torque Regulator) and an ASR (Automatic Speed ​​Regulator).

[0038] The inverter 4 includes, as its main components, a notch filter 40, a subtractor 47B, a roller drive control unit RC, and a second-order HPF (High-pass filter) 45. The roller drive control unit RC is composed of a current control unit 42, a PWM unit 43 (pulse modulation unit), and an inverter converter 44.

[0039] The notch filter 40 outputs a rotation command signal S3A, which is a first filtered rotation command signal that attenuates signals in a frequency band to be attenuated, including the mechanical natural frequency of the chassis dynamometer 1, from the rotation command signal S3.

[0040] The second-order HPF 45 passes a high-frequency band signal of the encoded signal S7 that includes the mechanical natural frequency of the chassis dynamometer 1, to obtain an encoded signal S7A that is a subtraction encoded signal. Note that the "second-order HPF" corresponds to two "first-order HPFs" connected in series. The high-frequency band that the second-order HPF 45 passes is set, for example, using the anti-machine natural frequency as a parameter.

[0041] Subtractor 47B, which is a first subtractor, subtracts encode signal S7A, which is a subtraction encode signal, from rotation command signal S3A, which is a first filtered rotation command signal, to obtain rotation command signal S3B, which is a second filtered rotation command signal. The process of subtracting encode signal S7A from encode signal S7 by subtractor 47B is filtering using second-order HPF 45.

[0042] The notch filter 40 includes a band-pass filter 41 and a subtractor 47A as main components.

[0043] The band-pass filter 41 passes signals in a frequency band to be attenuated, including the machine's natural frequency, from the rotation command signal S3 indicating the target rotation speed, to obtain a band-pass passed rotation command signal S41, which is a rotation command signal for subtraction. The frequency band to be attenuated by the band-pass filter 41 is set, for example, using the machine's natural frequency as a parameter.

[0044] Subtractor 47A as a second subtractor subtracts band-pass passing rotation command signal S41 as a subtraction rotation command signal from rotation command signal S3 to output rotation command signal S3A as a first filtered rotation command signal. The process of subtracting band-pass passing rotation command signal S41 from rotation command signal S3 by subtractor 47A corresponds to the filtering process by notch filter 40.

[0045] The current sensor 8 is provided on the signal output path of the drive control signal S4 (the signal input path of the roller drive motor 5), detects the current supplied to the roller drive motor 5, and outputs a current sense signal S8 indicating the amount of detected current. The current sense signal S8 is used as a feedback signal for the roller drive control unit RC.

[0046] The roller drive control unit RC will now be described. The current control unit 42 outputs a current control signal S42 to the roller drive motor 5 based on the rotation command signal S3B, the encode signal S7, and the current sense signal S8. The current control signal S42 is a signal that controls the motor current supplied to the roller drive motor 5 so that the detected rotation speed indicated by the encode signal S7 becomes the target rotation speed indicated by the rotation command signal S3B.

[0047] A PWM unit 43, which is a pulse width modulation unit, obtains an inverter control signal S43, which is a pulse signal, based on the current control signal S42. The duty ratio of the inverter control signal S43 is determined by the current control signal S42.

[0048] The inverter converter 44, which has a plurality of internal switching elements, outputs a drive control signal S4 based on the inverter control signal S43. The drive control signal S4 becomes a control signal suitable for driving the roller drive motor 5, as the internal switching elements are turned on and off by the current control signal S42.

[0049] The roller drive control unit RC, which includes the above-mentioned current control unit 42, PWM unit 43, and inverter converter 44, uses the encoded signal S7 as a feedback signal and generates a drive control signal S4 based on the rotation command signal S3B, which is the second filtered rotation command signal.

[0050] This drive control signal S4 is output to the roller drive motor 5. The roller drive motor 5 performs a rotational operation based on the drive control signal S4, and as a result, the roller drive motor 5 can drive the corresponding roller to rotate.

[0051] (Effect) Rotation command signal S3A, which is the first filtered rotation command signal, is a signal in which machine natural frequency components are suppressed compared to rotation command signal S3 due to filtering by notch filter 40. Rotation command signal S3B, which is the second filtered rotation command signal, is a signal in which machine natural frequency components are further suppressed from rotation command signal S3A due to subtraction processing by subtractor 47B, which is the first subtractor (filtering processing using second-order HPF 45).

[0052] In other words, the rotation command signal S3B is a signal in which the machine natural frequency components are suppressed in two stages from the rotation command signal S3, and therefore the machine natural frequency components contained in the rotation command signal S3B, which serves as a control input signal for the roller drive control unit RC, are effectively suppressed.

[0053] As a result, the chassis dynamometer 1 of this embodiment uses the rotation command signal S3B, which is the second filtered rotation command signal, as the control input signal for the roller drive controller RC, thereby suppressing resonance and vibration phenomena and controlling the drive of the roller drive motor 5. Note that resonance and vibration phenomena are phenomena that occur when the mechanical natural frequency of the chassis dynamometer 1 matches the frequency of the control input signal.

[0054] Additionally, the chassis dynamometer 1 of this embodiment suppresses resonance and vibration phenomena by modifying only the control system, that is, by inserting the notch filter 40, the second-order HPF 45, and the subtractor 47B in the inverter 4.

[0055] Therefore, the chassis dynamometer 1 of this embodiment can suppress resonance and vibration phenomena without making any mechanical structural changes to the chassis dynamometer 1 .

[0056] The following describes changes to the mechanical structure of the chassis dynamometer 1. The mechanical structure of the chassis dynamometer 1 includes the structure of the roller drive motor 5 and the motor peripheral components related to the roller drive motor 5. The motor peripheral components include a motor mounting member on which the roller drive motor 5 is mounted, a motor bearing for the roller drive motor 5, a floor surface 50, etc.

[0057] For example, the mechanical structure of the chassis dynamometer 1 can be modified by increasing the rigidity of the floor surface 50 or the motor bearings, reducing the mass, etc. Modifying the mechanical structure can change the machine's natural frequency. However, as mentioned above, modifying the mechanical structure of a chassis dynamometer is generally undesirable because it results in a significant increase in cost.

[0058] On the other hand, the chassis dynamometer 1 of this embodiment does not require any mechanical structural changes, and therefore does not result in an increase in costs.

[0059] In this way, the control system of the chassis dynamometer 1 can suppress resonance and vibration phenomena without changing the mechanical structure, thereby improving control response. Therefore, the chassis dynamometer 1 of this embodiment can achieve improved performance by improving control response.

[0060] Furthermore, notch filter 40 in inverter 4 has a relatively simple configuration using band-pass filter 41, and can obtain rotation command signal S3A, which becomes the first filtered rotation command signal, from rotation command signal S3.

[0061] The roller drive control unit RC included in the inverter 4 is configured to include a current control unit 42, a PWM unit 43, and an inverter converter 44, and can output a drive control signal S4 based on a rotation command signal S3B in which the machine natural frequency components are sufficiently suppressed.

[0062] <Others> Although the present disclosure has been described in detail, the above description is merely illustrative in all respects and does not limit the present disclosure. It is understood that countless variations not illustrated can be envisioned without departing from the scope of the present disclosure.

[0063] Therefore, the present disclosure allows modifications or omissions to be made to the embodiments as appropriate within the scope of the disclosure.

[0064] REFERENCE SIGNS LIST 1 chassis dynamometer 3 PLC 3X rotation controller 4 inverter 4X motor drive device 5 roller drive motor 6 tire 7 encoder 8 current sensor 20 roller pair 40 notch filter 41 band pass filter 42 current control section 43 PWM section 44 inverter converter 45 second-order HPF 47A, 47B subtractor

Claims

1. A chassis dynamometer having rollers on which vehicle tires are placed, the chassis dynamometer having a machine natural frequency, and comprising: an inverter that receives a rotation command signal indicating a target rotation speed and outputs a drive control signal based on the rotation command signal; a roller drive motor that rotates the roller based on the drive control signal; and an encoder that detects the motor rotation speed of the roller drive motor and obtains an encode signal that indicates the detected rotation speed, the inverter comprising: a notch filter that attenuates signals in a frequency band to be attenuated that includes the machine natural frequency from the rotation command signal to obtain a first filtered rotation command signal; a second-order HPF that passes signals in a high frequency band that includes the machine natural frequency from the encode signal to obtain a subtraction encode signal; a first subtractor that subtracts the subtraction encode signal from the first filtered rotation command signal to obtain a second filtered rotation command signal; and a roller drive control unit that generates the drive control signal based on the second filtered rotation command signal, using the encode signal as a feedback signal.

2. A chassis dynamometer according to claim 1, wherein the notch filter includes: a bandpass filter that passes signals in the frequency band to be attenuated from the rotation command signal to obtain a rotation command signal for subtraction; and a second subtractor that subtracts the rotation command signal for subtraction from the rotation command signal to obtain the first filtered rotation command signal.

3. A chassis dynamometer as claimed in claim 1 or claim 2, further comprising a current sensor that detects the current supplied to the roller drive motor and obtains a current sense signal indicating the amount of detected current, wherein the roller drive control section comprises: a current control section that obtains a current control signal for the roller drive motor based on the second filtered rotation command signal, the encoded signal and the current sense signal; a pulse width modulation section that obtains an inverter control signal, which is a pulse signal, based on the current control signal; and an inverter converter that outputs the drive control signal based on the inverter control signal, wherein the duty ratio of the inverter control signal is determined by the current control signal.

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