Electric motor EMC noise test method for automobile and software for same

Abstract

The present invention addresses the technical problem of precisely associating precise control of an operation state of a device to be tested and change in an EMC noise value due to the change in the control state, when performing EMC noise measurement.　According to the present invention, an operation state of the device to be tested is continuously changed and tested on the basis of a control parameter in an actual operating state, the measured value is recorded in association with the operating state, and a continuous measured value in real time is obtained.　The device to be tested may be a plurality of motors or the like.

Description

EMC noise testing method for automotive electric motors and software for the same

[0001] The present invention relates to EMC (Electromagnetic Compatibility) noise measurement for automotive electric motors, and more particularly to an EMC noise test method for automotive electric motors that enables detailed and simple measurement of the relationship between EMC noise and operating parameters of automotive electric motors in accordance with the driving conditions of the vehicle, and software therefor.

[0002] Patent Document 1 discloses "a noise equivalent circuit necessary to complete EMC analysis in a practical amount of time and with low-cost calculation processing in the upstream stages of system design" (abstract), which states that "the noise equivalent circuit is characterized by having one or more energy sources and propagation paths for energy propagation from the energy source, including, in addition to conduction paths such as cables, electromagnetic field coupling paths resulting from coupling of electric and magnetic fields with other electronic devices, cables, etc., and GND ports connected to the system, and each port being expressed by a noise voltage source or noise current source and internal impedance. By using this noise equivalent circuit, it becomes possible to analyze noise in the entire system by determining external impedance which changes depending on factors such as an externally connected load or the distance from external devices and cables." However, to begin with, automotive electric motors are not the subject of EMC analysis, and this method does not measure the relationship between the operating parameters of the energy source and EMC noise through actual measurements, but merely utilizes an equivalent circuit in the design stage.

[0003] Although Patent Document 2 discloses a technology for generally measuring the effect of jamming waves on equipment, this technology measures the relationship between jamming waves and their effect, and is unrelated to the operating parameters in EMC measurements of automotive electric motors, and does not anticipate EMC measurements in the actual operating conditions of an automobile.

[0004] Patent Document 3 discloses a technology for performing a detailed inspection based on preliminary inspection information in a component inspection system.

[0005] International Publication No. 2013 / 031874 Japanese Patent Application Laid-Open No. 2006-203474 Japanese Patent Application Laid-Open No. 10-135288

[0006] While these prior art techniques may measure and / or test the interrelationships of current, voltage, generated power and torque, control response performance, etc., when controlling the drive motor alone in a vehicle powered by an electric motor, they do not measure and / or test in detail the changes in EMC noise resulting from the state and state changes of an electric vehicle actually running as a function of the drive motor's running state. In other words, while prior art EMC noise measurements have been performed while devices such as the electric motor and inverter used as the drive source of an electric vehicle are operating alone, there has been no attempt to precisely measure EMC noise actually generated as a function of various running states in an electric vehicle under actual running conditions, or as a function of the motor control state under actual running conditions.

[0007] In other words, in conventional EMC tests of devices such as electric motors and inverters, the control conditions of the dynamo system used to control the operating state of the device under test, such as current, voltage, rotational speed, and torque, were set appropriately for the EMC test, but detailed and precise correlations between the frequency and electromagnetic field strength of the unwanted electromagnetic waves generated and various parameters under the control conditions actually occurring during actual driving conditions were not recorded. In other words, the operating state of the device under test was simply measured by setting certain operating conditions of the dynamo system appropriately to obtain EMC noise measurements. However, there was no idea of ​​precisely grasping the operating state of the device under test under actual driving conditions of an electric vehicle and precisely simulating changes in those control conditions to perform EMC tests that precisely correlate changes in EMC noise values ​​with changes in actual driving conditions, and no device capable of doing so existed. In this application, the term "dynamo system" refers to a device that drives an electric motor to generate rotational force and measures and / or monitors the relationship between electrical parameters and mechanical parameters of rotational motion.

[0008] The inventors have realized that measuring the control state of the electric motor as the drive source during actual driving conditions of an electric vehicle in a manner that closely correlates it with the generation of EMC noise will greatly contribute to improving unwanted electromagnetic noise in motor-driven vehicles such as electric vehicles. Specifically, they have discovered that simply measuring EMC noise while controlling the electric motor independently of the vehicle's actual driving conditions is far from providing a complete understanding of the EMC noise generated by an electric vehicle during actual driving conditions, and that EMC noise generated during actual driving conditions of an electric vehicle, such as when stopped, starting on a flat road, starting on a slope, accelerating, decelerating, regenerative braking, etc., is generated by the complex interaction of many factors. Therefore, an object of the present invention is to easily measure and / or test the EMC noise generated by the electric motor as the drive source of an electric vehicle by closely correlating the control state and EMC noise during actual driving conditions.

[0009] The present invention includes the following aspects. [1] An EMC noise testing method for a vehicle motor and / or inverter, in which a dynamo system and an EMC measurement device are controlled so that control parameters, which are the driving conditions of the motor and / or inverter under test, are changed based on actual measurements during actual driving, and EMC noise measurements during the course of the change are recorded in real time in relation to the control parameters as the electrical driving conditions change. [2] The method of [1], in which the control parameters change continuously and the relationship between the EMC noise measurements and the control parameters can be continuously recorded and / or displayed by continuously recording the EMC measurements. [3] The method of [2], in which the operating parameters of the dynamo system are rotation speed, torque, voltage, and current, and optionally, in addition to these, the temperature and / or vibration state of the equipment under test. [4] The method of [1], in which the vehicle has a plurality of motors and / or inverters. [5] The method according to [1], which is capable of displaying control parameters of a device under test at minimum values, maximum values, discontinuous change point values, and boundary values ​​of a predetermined region of noise that accompanies changes in operating parameters. [6] An EMC noise testing device for executing the method according to any one of [1] to [5]. [7] EMC noise testing software for executing the method according to any one of [1] to [5].

[0010] The present invention relates to a testing method and software for executing the method, which includes measuring the control state of an electric motor that serves as a drive source for an electric vehicle or the like in terms of current, voltage, generated torque, rotational speed, and, optionally, temperature and mechanical vibration amount (these amounts are referred to herein as electric motor control parameters) in real time, while performing control based on the measured control state of the electric vehicle under actual driving conditions to determine how EMC noise changes in response to changes in the control state of the electric motor. The method also includes measuring the electric motor control parameters, i.e., voltage, current, torque, and rotational speed, in real time, while performing control based on the measured control state of the electric vehicle under actual driving conditions, and recording the measured EMC noise values ​​in response to the changes in real time. The method also relates to software for executing the method.

[0011] By measuring the control parameters of the electric motor in advance during the actual driving conditions of the electric vehicle, operating the electric motor using an EMC measuring device according to the measured control conditions, and measuring EMC noise in real time, it becomes possible to accurately and easily grasp the state of EMC noise generation during the actual driving conditions.

[0012] The EMC noise testing method of the present invention enables more accurate and simple measurement and understanding of the control status of electric motors used to drive vehicles, such as electric vehicles, and the resulting EMC noise. This allows for more accurate and simple measurement and display of the relationship between the actual electric motor operating conditions and EMC noise during actual driving conditions of an electric vehicle. For example, when accelerating a hybrid vehicle, both the internal combustion engine and the motor are used. To perform EMC measurements under these conditions, the control parameters of the EMC test target device under actual driving conditions must be set to those for the engine and motor during acceleration. The present invention enables such parameter setting, allowing accurate EMC testing under such actual driving conditions. The control parameters of the test target device can be set to reproduce various driving modes, such as steady-state driving, regenerative braking, and low-speed motor driving, enabling detailed EMC testing. In this specification, the object of measurement is described as an electric vehicle, but it goes without saying that any vehicle that uses a large current motor and can be the subject of EMC testing can also be the subject of the present invention.

[0013] FIG. 1 is a diagram illustrating the basic principle of the method of the present invention using an example of an apparatus. FIG. 2 is a diagram illustrating the situation in which operation control parameters are obtained during actual operation. FIG. 3 is a graph illustrating the assumed changes in the values ​​of the operation control parameters in accordance with the actual operation of FIG. 2. The vertical axis represents torque, horsepower, voltage, and current values, and the horizontal axis represents rotational speed. In actual driving, the changes shown in this diagram occur as the rotational speed changes. FIG. 4 is a diagram illustrating an example of the display of operation control parameters and EMC noise values ​​obtained by the method of the present invention. FIG. 5 is a diagram explaining the implementation of the present invention when multiple motors are used.

[0014] Figure 1 shows the basic principle of the method of the present invention using an example of an apparatus. The dynamo system block at the bottom left of Figure 1 houses equipment for controlling the electric motor and inverter under test, and the dynamo system is controlled based on operational control parameters defined by control signals sent from the measurement room to the dynamo system control equipment, thereby driving the electric motor and inverter under test. The operational control parameters controlled by the dynamo system are voltage, current, rotation speed, and torque, but other control parameters such as the temperature and mechanical vibration state of the electric motor and inverter under test can also be used as optional control parameters.

[0015] The driving control parameters used are the control parameter values ​​when the vehicle is in an actual driving state. They do not necessarily have to be the actual measured values, but rather, the control parameters in the vehicle's actual driving state can be acquired and the parameter values ​​can be based on the acquired values. However, the driving control is performed by measuring each parameter value in the actual driving state and changing the reproduced parameter values ​​based on the changes in those values.

[0016] The lower right corner of Figure 1 shows an anechoic chamber for EMC testing. The chamber houses an electric motor and inverter under test, and EMC testing is performed on the electric motor and inverter driven by a dynamo system based on control parameters. The chamber is also equipped with the necessary equipment for EMC testing, such as antennas and preamplifiers installed in the chamber, as well as devices required for measurements in standard EMC tests. It also contains an EMC test control unit and EMC measurement equipment. The EMC test measurement results, along with dynamo system control data driven based on the control parameters, are input to an information processing block, which is an information processing device that executes the method of the present invention and processes both the control parameters and EMC noise values ​​obtained by EMC measurement. Although the dynamo system control and EMC test signal processing units are depicted as separate functions, a single information processing unit may process information for both the dynamo system and the EMC test unit, or they may be provided separately.

[0017] When controlling a dynamo system, it is necessary to control it so that EMC tests are performed under operating conditions that simulate the actual driving conditions of an electric vehicle, and by operating the electric motor and inverter under test with control parameters that correspond to these driving conditions and measuring and recording the EMC noise during this process in real time, precise information can be obtained, such as under what conditions the EMC noise will be maximized, and under what control parameters the conditions for obtaining a desirable minimum noise level.To achieve this, one of the features of the present invention is to estimate in advance control parameters that simulate actual driving conditions, such as acceleration, deceleration, powering, regeneration, etc., and then perform the EMC test while controlling according to these parameters, thereby making it possible to measure the precise correspondence between the EMC test results and the driving conditions.

[0018] The control parameters are actually measured, or the operating conditions are continuously reproduced over time using assumed parameters as shown in Figure 2 using a dynamometer system, and EMC noise measurements are made in real time, with the measurement results being stored and accumulated.

[0019] Assuming that the values ​​of the driving control parameters change in accordance with the actual driving conditions in Figure 2, a combination of control parameters is obtained corresponding to the driving conditions, as shown in Figure 3. This combination of control parameters is determined according to the driving conditions, and the combination of parameters corresponding to the driving conditions is found, and EMC noise measurement is carried out accordingly.

[0020] Figure 4 shows an example of the display results of changing control parameters over time and recording EMC noise measurements in real time in response to those changes. In Figure 4, a graph (4) of the actual measured values ​​of real-time changes in EMC noise is displayed on the screen in the upper row, and a graph (5) of the change in control parameters is displayed on the screen in the lower row. In this figure, by positioning the cursor over a specific EMC noise state shown in the upper row, the corresponding values ​​of the control parameters at the corresponding position in the lower row can be displayed on the bottom screen (6). It is also easy to determine the values ​​of control parameters that fall within a specified range of real-time measured values ​​of EMC noise.

[0021] Surprisingly, EMC noise behavior can be unexpected depending on the history of changes in driving control parameters. Specific behavior differs depending on the equipment being measured, but for example, even if a parameter value is the same as that during acceleration, the EMC noise may be different when decelerating using regenerative braking. Also, the EMC noise may differ even for the same combination of parameter values ​​depending on how the actual driving situation progresses.

[0022] Furthermore, an increasing number of vehicles are using multiple high-power motors, as shown in Figure 5. When multiple motors are used, the behavior of EMC noise differs due to differences in how the devices are combined and how they affect each other. In addition, the state of EMC noise itself, which is caused by the behavior of control parameters when multiple motors are actually operating, varies in complex ways depending on the actual operating conditions. By conducting EMC testing that reproduces these conditions, it becomes possible to test, detect, and / or record, with unprecedented precision, how changes in EMC noise actually occur and under what conditions.

[0023] When multiple motors are present, the state of each device will differ depending on how they are installed in the actual vehicle, and when multiple motors are present, the installation mode will result in a variety of different driving loads and power generation conditions for each motor. According to the present invention, the EMC noise state in actual operating conditions, which cannot be grasped by a simple test of a single device, can be reproduced by controlling the operating parameters based on the actual operating conditions, making it possible to obtain and / or record accurate EMC test results, and making it possible to grasp which devices contribute more significantly to EMC noise under what operating conditions.

[0024] The method of the present invention allows the operating control state of the electric motor and inverter under test, for which noise is measured by EMC testing, to be freely set by precisely controlling the changes in control parameters over time, and also allows the EMC test results to be measured and recorded in real time, including the control of the control parameters and the resulting EMC noise generation state, and further allows the control parameters and noise measurement results to be displayed in association with each other, thereby enabling the simple acquisition and display of precise measurement results of EMC testing.

[0025] Furthermore, the present invention enables testing to be performed using software that combines the functions of controlling the operating state of the equipment under test for EMC testing and recording and displaying EMC test results in association with the operating state, thereby enabling automatic reproduction of operating states and real-time acquisition of EMC test results associated with those states, resulting in the excellent effect of easily obtaining much more accurate EMC test results than before.The present invention also relates to the above-mentioned EMC noise testing software and an EMC noise testing device equipped with the software.The software invention is software that executes the above-mentioned method when installed in an EMC noise testing device for executing the above-mentioned method, and the EMC noise testing device invention is the device shown in the various figures that executes the above-mentioned method.

[0026] 1: EMC anechoic chamber 2: Dynamo system 3: Information processing block 4: Measured noise value screen 5: Control parameter screen 6: Screen displaying values ​​at cursor position 310: Torque 320: Output 330: Terminal voltage 340: Current 501: Engine 502: Motor 503: Battery 504: Inverter 505: Fuel tank 506: Differential gear 507: Flow of rotational force 508: Flow of electricity 509: Flow of fuel

Claims

In EMC noise testing of a vehicle motor and / or inverter, the control parameters, which are the driving conditions of the motor and / or inverter under test, are changed based on actual measured values ​​during actual driving, and the EMC noise measurement values ​​during the period of change are controlled so as to be recorded in real time in relation to the control parameters as the electrical driving conditions change.

2. The method of claim 1, wherein the change in the control parameter is continuous and the EMC measurement values ​​are continuously recorded, thereby enabling the relationship between the EMC noise measurement values ​​and the control parameter to be continuously recorded and / or displayed.

3. The method of claim 2, wherein the operating parameters of the dynamo system are rotation speed, torque, voltage and current, and optionally also the temperature and / or vibration state of the equipment under test. 　 The method of claim 1 , wherein the vehicle has a plurality of motors and / or inverters.

2. The method according to claim 1, wherein the control parameters of the device under test at minimum values, maximum values, discontinuous change point values, and / or boundary values ​​of a predetermined region of noise accompanying changes in the operating parameters can be displayed. 　 An EMC noise testing device for carrying out the method according to any one of claims 1 to 5. 　 EMC noise testing software for carrying out the method according to any one of claims 1 to 5.

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