EMC noise test method for automotive electric motors and software for that purpose

Abstract

To precisely associate the precise control of the operating state of a device to be tested with the change of an EMC noise value due to the change of the control state when measuring EMC noise.SOLUTION: The operation state of the device to be tested is continuously changed and tested based on the control parameter in the actual operation state, and the measured value is recorded in association with the operation state to obtain a real-time continuous measured value. The device to be tested may be a plurality of motors or the like.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses "a noise equivalent circuit necessary to complete EMC analysis in a practical amount of time and with low-cost computational processing in the upstream stages of system design" (abstract), which states that "the noise equivalent circuit has one or more energy sources and propagation paths for the energy 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 and cables, and GND ports connected to the system, and is characterized by a noise equivalent circuit in which each port is 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 that changes depending on factors such as the load connected to the outside 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 only 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. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2013 / 031874 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-203474 [Patent Document 3] Japanese Patent Application Publication No. 10-135288 Summary of the Invention [Problem to be solved by the invention]

[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 while actually running as a function of the drive motor's running state. In other words, in conventional EMC noise measurements, EMC noise was measured when devices such as electric motors and inverters used as drive sources for electric vehicles were operating independently, but there was no attempt to precisely measure the actual noise generated in electric vehicles under actual driving conditions as a function of the various driving conditions, or the EMC noise as a function of the motor control state under actual driving conditions.

[0007] In other words, in the past, in EMC testing of devices such as electric motors and inverters, the control states of the dynamo system used to control the operating state of the tested device, such as the current, voltage, rotational speed, and torque, were controlled using control states that were appropriately set when conducting the EMC test, and detailed and precise recordings were not made of the frequency and electromagnetic field strength of the unwanted electromagnetic waves generated under the control states that actually occur during actual driving conditions, and the various parameters under actual driving conditions. In other words, when measuring EMC noise, the operating state of the device under test was simply determined by setting certain operating conditions of the dynamo system as appropriate and obtaining EMC noise measurement values. There was no idea of ​​accurately grasping the operating state of the device under test under actual driving conditions of an electric vehicle and conducting EMC tests by precisely simulating changes in that control state, thereby precisely correlating changes in EMC noise values ​​with changes in the actual driving conditions, and no device existed that could achieve this. 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 that serves as the drive source of an electric vehicle while the vehicle is actually running, in close relation to the generation of EMC noise, will greatly contribute to the reduction of unwanted electromagnetic noise in motor-driven vehicles such as electric vehicles. In other words, we discovered that simply controlling and measuring the electric motor independently of the vehicle's actual driving conditions does not provide a complete understanding of the EMC noise generated by an electric vehicle under actual driving conditions, and that the EMC noise generated when an electric vehicle is actually driving, such as when stopped, starting on a flat road, starting on a slope, accelerating, decelerating, during 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 relationship between the control state and EMC noise of an electric motor, which is the drive source of an electric vehicle, in a detailed manner during actual driving conditions. [Means for solving the problem]

[0009] The present invention includes the following aspects. [1] 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 change period are recorded in real time in relation to the control parameters as the electrical driving conditions change, by controlling the dynamometer system and EMC measuring device. [2] The method according to [1], wherein the change in the control parameter is continuous, and the relationship between the EMC noise measurement value and the control parameter can be continuously recorded and / or displayed by continuously recording the EMC measurement value. [3] The method according to [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. [4] The method according to [1], wherein the vehicle has a plurality of motors and / or inverters. [5] The method described in [1], which is capable of displaying the control parameters of the equipment under test at the minimum values, maximum values, discontinuous change point values, and boundary values ​​of a specified region of noise accompanying changes in the operating parameters. [6] An EMC noise testing device for carrying out the method according to any one of [1] to [5]. [7] EMC noise testing software for carrying out the method according to any one of [1] to [5].

[0010] The present invention relates to a testing method that involves measuring the control state of an electric motor, which is a driving source for an electric vehicle or the like, in real time to determine how EMC noise changes in response to changes in current, voltage, generated torque, rotational speed, and, optionally, temperature and mechanical vibration amount (these amounts are referred to in this specification as electric motor control parameters), 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 real time; extracting and displaying the voltage, current, torque, and rotational speed values ​​that result in maximum values ​​of the recorded EMC noise; and displaying the voltage, current, torque, and rotational speed that give the selected EMC noise value. This method also relates to software that executes this method. [Effects of the Invention]

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

[0012] By using the EMC noise testing method of the present invention, it is possible to more accurately and simply measure and understand the control status of an electric motor for driving a vehicle such as an electric vehicle and the resulting EMC noise status. As a result, it is possible to more accurately and simply measure and display the relationship between the actual electric motor operating status and EMC noise when the electric vehicle is actually running. For example, when accelerating a hybrid vehicle, a real-world driving condition occurs in which both the internal combustion engine and the motor are used. To measure EMC under these conditions, the control parameters of the EMC test target device under actual driving conditions must be set to the parameters for the state when the vehicle is accelerating using the engine and motor before the EMC test can be performed. The present invention makes it possible to set such parameters, enabling accurate EMC testing under such real-world driving conditions. This makes it possible to set the control parameters of the test target device to reproduce various driving modes, such as steady-state driving, when using regenerative braking, and when driving using the low-speed motor, 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 is also subject to the present invention. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating the basic principle of the method of the present invention using an example of an apparatus. [Figure 2] FIG. 2 is a diagram showing the situation in which the operational control parameters are obtained during actual operation. [Figure 3] Figure 3 is a graph that shows the expected changes in the values ​​of the driving control parameters that correspond to the actual driving conditions shown in Figure 2. The vertical axis represents torque, horsepower, voltage, and current, and the horizontal axis represents rotational speed. In actual driving, the changes shown in this graph occur as the rotational speed changes. [Figure 4] FIG. 4 is a diagram showing an example of the display of the operational control parameters and EMC noise values ​​obtained by the method of the present invention. [Figure 5] FIG. 5 is a diagram for explaining an embodiment of the present invention when the embodiment uses a plurality of motors. DETAILED DESCRIPTION OF THE INVENTION

[0014] FIG. 1 illustrates the basic principle of the method of the present invention using an example of an apparatus. The dynamo system block in the lower left of Figure 1 houses the equipment that controls the electric motor and inverter under test. The dynamo system is controlled based on the operating control parameters determined by the control signal sent from the measurement room to the dynamo system control equipment, and the electric motor and inverter under test are driven. The operational control parameters controlled by the dynamo system are voltage, current, rotational speed and torque, but optionally the temperature of the electric motor and inverter under test and the mechanical vibration state can also be used as 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 of Figure 1 shows an anechoic chamber for EMC testing. The electric motor and inverter under test are housed in the chamber, and EMC testing is performed on the 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 EMC test control equipment and EMC measurement equipment. The measurement results of the EMC test, together with the dynamo system control data that drives the system 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 the EMC noise values ​​obtained by the EMC measurement. Although the signal processing devices for the dynamo system control and the EMC test are expressed as separate functions, a single information processing device as a whole may process information for both the dynamo system and the EMC test device, or they may be provided separately.

[0017] When controlling the dynamo system, it is necessary to control it so that EMC tests are conducted under operating conditions that simulate the actual driving conditions of an electric vehicle. By operating the electric motor and inverter under test using control parameters that correspond to these driving conditions and measuring and recording the EMC noise in real time, precise information can be obtained, such as under what conditions the EMC noise will be at its maximum, and under what control parameters the desired minimum noise level will be obtained. To achieve this, one of the features of the present invention is that it is possible to measure a precise correspondence between the EMC test results and the running state by estimating control parameters in advance that simulate actual running states, such as acceleration, deceleration, powering, and regeneration, and then performing EMC tests while controlling in accordance with those parameters.

[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 performed 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 can be 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 measurements are performed accordingly.

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

[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, differences in the progression of actual driving conditions can result in different EMC noise even when the same combination of parameter values ​​is used.

[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 how the control parameters behave 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 driving load and power generation state of each motor will vary depending on how they are installed in the vehicle. According to the present invention, the EMC noise conditions under actual operating conditions, which cannot be grasped by simple testing of a single piece of equipment, can be reproduced by controlling the operating parameters based on the actual operating conditions, and accurate EMC test results can be obtained and / or recorded, making it possible to grasp which equipment contributes 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 from EMC testing.

[0025] Furthermore, the present invention enables testing to be performed using software that has both the function of controlling the operating state of the equipment under test for EMC testing and the function of recording and displaying EMC test results in association with the operating state, making it possible to automatically reproduce the operating state and obtain EMC test results in association with that state in real time, resulting in the excellent effect of easily obtaining EMC test results that are significantly more precise than ever 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, when installed in an EMC noise testing device for executing the above-mentioned method, executes the above-mentioned method, and the EMC noise testing device invention is the device shown in each figure, which executes the above-mentioned method. [Explanation of symbols]

[0026] 1: EMC anechoic chamber 2: Dynamo System 3: Information Processing Block 4: Measured noise value screen 5: Control parameter screen 6: Display screen of the value at the 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: Rotational Force Flow 508: Electrical Flow 509: Fuel flow

Claims

1. 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. 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. 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.

4. The method of claim 1 , wherein the vehicle has a plurality of motors and / or inverters.

5. 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.

6. An EMC noise testing device for carrying out the method according to any one of claims 1 to 5.

7. EMC noise testing software for carrying out the method according to any one of claims 1 to 5.

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