Noise source estimation device

Abstract

The present invention provides a noise cause estimation device that can estimate whether the cause of noise generation is mechanical or electromagnetic. [Solution] When the output torque of the motor is changed, if the change in the peak frequency of the noise is less than or equal to a predetermined first predetermined change, and the change in the peak level of the noise is greater than or equal to a predetermined second predetermined change (Yes in step S12), it is estimated that the noise during motor operation is caused by electronic components (step S13). If the change in the peak frequency of the noise is greater than the first predetermined change, or the change in the peak level of the noise is less than the second predetermined change (No in step S12), it is estimated that the noise is caused by mechanical components (step S15).

Description

Technical Field

[0002] , , , ,

[0004] , , , , , , , ,

[0003] , , , ,

[0001] This invention relates to an apparatus for estimating the cause of noise generated by driving a motor.

Background Art

[0002] Patent Document 1 describes a sound source estimation system that identifies a component that causes abnormal noise among a plurality of components mounted on a vehicle. This sound source estimation system extracts sound at a frequency that the user perceives as abnormal noise from sound data generated by driving the vehicle, and is configured to identify a component that may generate a rotational speed based on the frequency of the extracted sound as the cause of the abnormal noise. Specifically, it is determined based on a user operation or the like whether the sound data generated by driving the vehicle contains abnormal noise, and analysis sound data excluding noise other than abnormal noise and analysis rotational speed data are generated from the sound data containing abnormal noise. Subsequently, based on the analysis sound data and the analysis rotational speed data, the maximum sound frequency, which is the frequency indicating the maximum sound pressure, is extracted every predetermined time, and the order of the maximum sound frequency data is calculated. Then, a component that is a candidate for the sound source of the abnormal noise is estimated based on the calculated order.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The sound source estimation system described in Patent Document 1 is configured to identify the component (mainly gears) causing the abnormal noise based on the order of a specific frequency contained in the detected sound data. However, the noise generated when a motor is driven has mechanical factors such as rotor imbalance and spline phase, and electromagnetic factors such as the current supplied to the coils in the stator. Specifically, the noise generated by mechanical factors included in the noise generated when a motor is driven consists of continuous integer rotational order components, while the noise generated by electromagnetic factors consists of rotational order components that are integer multiples of the number of pole pairs of magnets in the rotor. Therefore, the orders of the noise generated by mechanical factors and the noise generated by electromagnetic factors may coincide, and it may not be possible to identify the cause of the noise based on the rotational order of a specific frequency contained in the noise.

[0005] This invention was made in view of the above-mentioned technical problems, and aims to provide a noise cause estimation device that can estimate whether the cause of noise generation is mechanical or electromagnetic. [Means for solving the problem]

[0006] To achieve the above objective, this invention provides a noise cause estimation device comprising a motor having a plurality of mechanical parts that output torque when energized, and a power control unit having a plurality of electronic parts that control the power supplied to the motor, wherein the device comprises a measuring instrument for measuring noise when the motor is driven, and a controller for estimating, based on noise data measured by the measuring instrument, whether the noise generated by driving the motor is caused by the mechanical parts constituting the motor or by the electronic parts constituting the power control unit, wherein the controller estimates that the noise when the motor is driven is caused by the electronic parts when the amount of change in the peak frequency of the noise when the output torque of the motor is changed is less than or equal to a predetermined first predetermined amount of change, and the amount of change in the peak level of the noise is greater than or equal to a predetermined second predetermined amount of change, and estimates that the noise is caused by the mechanical parts when the amount of change in the peak frequency of the noise is greater than the first predetermined amount of change or the amount of change in the peak level of the noise is less than the second predetermined amount of change. [Effects of the Invention]

[0007] According to this invention, it is possible to determine whether the noise is caused by electromagnetic or mechanical factors based on the change in the peak frequency and peak level of the noise when the output torque of the motor is changed. Therefore, even when the order of the noise is the rotational order that is generated by both mechanical and electromagnetic factors, the cause of the noise can be estimated. [Brief explanation of the drawing]

[0008] [Figure 1] This figure schematically shows an example of a vehicle equipped with a noise source estimation device according to an embodiment of this invention. [Figure 2] This is a flowchart illustrating an example of the control performed by the noise source estimation device in this embodiment of the invention. [Figure 3] This is a flowchart illustrating an example of a motor noise source isolation mode performed by the noise source estimation device in this embodiment of the invention. [Modes for carrying out the invention]

[0009] This invention will be described based on the embodiments shown in the figures. The embodiments described below are merely examples of how this invention can be implemented and do not limit it.

[0010] Figure 1 schematically shows an example of a vehicle Ve equipped with a noise source estimation device according to an embodiment of this invention. The vehicle Ve shown in Figure 1 is equipped with a motor (MG) 1 as a driving force source. This motor 1 can be configured as a three-phase AC type permanent magnet synchronous motor, similar to motors provided as driving force sources in conventional electric vehicles and hybrid vehicles. That is, it is composed of a rotor to which the output shaft 2 is spline engaged, a cylindrical stator arranged to surround the outer circumference of the rotor, a plurality of permanent magnets provided at predetermined intervals in the circumferential direction of the rotor, and a plurality of coils provided at predetermined intervals in the circumferential direction of the stator. Each of these components constituting the motor 1 corresponds to a "mechanical part" in the embodiment of this invention. The rotor is formed by laminating a plurality of annularly formed steel plates.

[0011] The coil is connected to a power control unit (hereinafter referred to as PCU) 3, which includes an inverter that converts DC power output from a power storage device (not shown) into AC power for energization, and also converts the AC power generated in the coil by the rotation of the rotor into DC power for supply to the power storage device. This PCU 3 can be configured in the same way as power control units provided in conventional electric vehicles and hybrid vehicles, and is composed of multiple electronic components such as diodes and transistors.

[0012] Furthermore, an ammeter 4 is provided between the motor 1 and the PCU 3 to measure the current flowing through the motor 1 (coil). At least two ammeters 4 are provided to measure the current flowing through the U-phase, V-phase, and W-phase, respectively.

[0013] This motor 1 is driven by controlling the voltage applied to each phase according to the rotation angle. For this reason, a resolver 5 is provided to detect the rotation angle of the motor 1. This resolver 5 consists of an irregularly shaped rotor that rotates integrally with the output shaft 2 of the motor 1, a stator that surrounds the rotor, and a plurality of coils that are spaced apart at predetermined intervals in the circumferential direction of the stator. It is configured to detect the rotation angle of the rotor based on the change in reactance caused by a change in the gap between the rotor and the coils.

[0014] Furthermore, the motor 1 is connected to the drive wheels 9 via a transmission 6, which increases or decreases the torque output from the motor 1, and a differential gear unit 8, which divides and transmits the torque to the left and right drive shafts 7.

[0015] Furthermore, the vehicle Ve is equipped with a microphone 10 for detecting sound in a predetermined space such as the interior of the vehicle, and a G-sensor 11 for detecting vibration (acceleration) at a predetermined location on the vehicle Ve. These microphone 10 and G-sensor 11 correspond to the "measuring instruments" in this embodiment of the invention.

[0016] Furthermore, the vehicle Ve is equipped with a controller (ECU) 12 for estimating the cause of vibrations and abnormal noises (hereinafter collectively referred to as noise). This controller 12 is mainly composed of a microcomputer and receives signals from the ammeter 4, resolver 5, microphone 10, and G sensor 11, and is configured to estimate the cause of noise based on the input signals and pre-stored calculation formulas and maps.

[0017] Figure 2 shows a flowchart illustrating an example of the control performed by the controller 12. In the control example shown in Figure 2, first, noise data D0, motor torque T0, and motor rotation speed N0 are acquired (step S1). In step S1, the noise data D0 is read from the signals detected by the microphone 10 and the G sensor 11. The motor torque T0 is obtained by reading the signal detected by a torque sensor installed on the output shaft 2 of the motor 1, or by calculating it based on the current value detected by the ammeter 4. The motor rotation speed N0 is read from the signal detected by the resolver 5.

[0018] Step S2 involves determining the noise order through order analysis using the motor rotation speed N0 obtained in step S1. Specifically, for example, the noise level for each frequency is obtained by performing an FFT analysis on the noise data D0 obtained in step S1, and the frequency component with the largest noise level is extracted. Subsequently, the noise order is determined by dividing the extracted frequency by the motor rotation speed N0.

[0019] Step S3 determines whether the order identified in step S2 (hereinafter referred to as the noise order) is the order (rotational order) generated by both mechanical and electromagnetic factors. The rotational order of mechanical factors is a continuous integer such as 1st, 2nd, or 3rd order. On the other hand, the rotational order of electromagnetic factors is an integer multiple of the number of pole pairs of magnets provided on the rotor. That is, for example, if there are four magnets on the rotor and the number of pole pairs is four, the rotational order of electromagnetic factors will be an order such as 8th, 16th, or 24th order. Therefore, if the noise order is, for example, 8th order, it matches both the rotational order of mechanical factors and the rotational order of electromagnetic factors. In such cases, a positive determination is made in step S3. Conversely, if the noise order is, for example, less than 4th order or an order other than a multiple of 4, it is presumed not to be the rotational order of electromagnetic factors and not noise generated by electromagnetic factors, so a negative determination is made in step S3.

[0020] When it is negatively determined in step S3 because the noise order is not the rotational order generated by both mechanical factors and electromagnetic factors as described above, the specific result by order analysis is output (step S4), and this routine is terminated once. That is, it is estimated that the noise generated during motor drive is noise due to mechanical factors.

[0021] On the contrary, when it is affirmatively determined in step S3 because the noise order is the rotational order generated by both mechanical factors and electromagnetic factors, the noise level of the motor rotation primary component is referred to from the noise data D0 acquired in step S1 (step S5), and it is determined whether or not the noise level is equal to or higher than a predetermined level (step S6). The predetermined level in this step S6 is for determining whether there is a concern that the rotational order of mechanical factors occurs, and is determined in advance by experiments or the like.

[0022] When it is negatively determined in step S6 because the noise level of the motor rotation primary component is lower than the predetermined level, it is estimated that the noise during the drive of motor 1 is due to electromagnetic factors (step S7), and this routine is terminated once.

[0023] On the contrary, when it is affirmatively determined in step S6 because the noise level of the motor rotation primary component is equal to or higher than the predetermined level, the motor noise factor separation mode is entered. A flowchart for explaining an example of the control executed as the motor noise factor separation mode is shown in FIG. 3.

[0024] In the example shown in Figure 3, first, the user is prompted to drive at multiple accelerator openings by displaying this information on a monitor installed in the vehicle, and noise is measured (step S8). Next, motor torque T1 and noise data D1, such as in-cabin noise, unit vibration, or unit radiated sound data, are acquired during low-torque driving (i.e., low accelerator opening) (step S9), and motor torque T2 and noise data D2, such as in-cabin noise, unit vibration, or unit radiated sound data, are acquired during high-torque driving (i.e., high accelerator opening) (step S10).

[0025] Then, it is determined whether the torque difference obtained by subtracting the motor torque T1 obtained in step S8 from the motor torque T2 obtained in step S9 is greater than or equal to a predetermined torque difference ΔT (step S11). The predetermined torque difference ΔT in step S11 is set to a torque difference that will allow for the determination of noise due to mechanical factors and noise due to electromagnetic factors in step S12, which will be described later. Note that in step S11, one of the motor torques being compared may be the motor torque T0 obtained in step S1.

[0026] If the torque difference is less than the predetermined torque difference ΔT due to a small change in the user's accelerator operation, or if the user does not change the amount of accelerator operation, and this is negatively determined in step S11, then it is not possible to estimate whether the noise during motor operation is due to mechanical or electromagnetic factors, and therefore this routine is terminated. Alternatively, the process may return to step S8 and prompt the user to drive again with multiple accelerator openings.

[0027] Conversely, if the above torque difference is determined to be greater than or equal to a predetermined torque difference ΔT in step S11, the noise data D1 obtained in step S8 and the noise data D2 obtained in step S9 are compared to determine whether the peak frequency change amount in the noise order is less than or equal to a predetermined frequency B, and whether the change in the peak level of the noise is greater than or equal to a predetermined change amount A2 (step S12). Step S12 is a step to determine whether the cause of the noise is a mechanical factor or an electromagnetic factor. Specifically, if the noise is generated by a mechanical factor, the noise level will not change in accordance with the motor torque, and the peak frequency of the noise will change, so it is determined whether the peak frequency has changed and whether the peak level of the noise has changed. The predetermined frequency B corresponds to the "first predetermined change amount" in this embodiment of the invention, and the predetermined change amount A2 corresponds to the "second predetermined change amount" in this embodiment of the invention.

[0028] Therefore, if the peak frequency change range is less than or equal to a predetermined frequency B, and the change in peak level is greater than or equal to a predetermined change A2, and thus a positive determination is made in step S12, the cause of noise generation during motor operation is estimated to be an electromagnetic factor (step S13), and the result is output (step S14). Conversely, if the peak frequency change range is greater than the predetermined frequency B, or the change in peak level is less than the predetermined change A2, and thus a negative determination is made in step S12, the cause of noise generation during motor operation is estimated to be a mechanical factor (step S15), and the result is output (step S16).

[0029] As described above, by changing the output torque of motor 1, and determining the change in peak frequency and peak level from the noise data acquired at that time, and by determining whether the noise is due to electromagnetic or mechanical factors based on the determined change in peak frequency and peak level, it is possible to estimate the cause of the noise even when the noise order is the rotational order that occurs due to both mechanical and electromagnetic factors.

[0030] Furthermore, the noise source estimation device in this embodiment of the invention is not limited to one mounted on the vehicle Ve, but may also be a tablet terminal or the like. Also, the vehicle Ve is not limited to driving on public roads such as in urban areas, but may be driven in a simulated manner on a chassis dynamometer or the like to change the motor torque. In that case, measuring instruments such as microphones and G sensors do not have to be permanently installed in the vehicle, but may be attached to the vehicle Ve when estimating the source of noise generation, and the noise source estimation device does not have to be installed in the vehicle Ve.

[0031] Furthermore, the noise source estimation device described above is not limited to one that estimates the source of noise while the motor 1 and PCU 3 are mounted on the vehicle Ve. For example, the device may be configured to estimate the source of noise by attaching the motor and PCU, which have been removed from the vehicle Ve, to a measuring instrument or the like, and changing the motor torque in that state. [Explanation of Symbols]

[0032] 1 motor 3. Power Control Unit (PCU) 4 Ammeter 5 resolvers 10 Microphones 11G sensor 12 controllers Vehicle

Claims

[Claim 1] A noise source estimation device comprising a motor having multiple mechanical parts that output torque when energized, and a power control unit having multiple electronic parts that control the power supplied to the motor, A measuring instrument for measuring noise during the operation of the motor, The system includes a controller that estimates, based on noise data measured by the measuring instrument, whether the noise generated by driving the motor is caused by the mechanical components constituting the motor or by the electronic components constituting the power control unit. The aforementioned controller, When the output torque of the motor is changed, if the change in the peak frequency of the noise is less than or equal to a predetermined first predetermined change, and the change in the peak level of the noise is greater than or equal to a predetermined second predetermined change, it is estimated that the noise during motor operation is caused by the electronic components. If the change in the peak frequency of the noise is greater than the first predetermined change, or the change in the peak level of the noise is less than the second predetermined change, it is estimated that the noise is caused by mechanical components. A noise source estimation device characterized by the following features.

Images