Electromagnetic noise analysis device, electromagnetic noise analysis method

Abstract

This invention provides an electromagnetic noise analysis apparatus and method that achieves both reduced analysis time and improved analysis accuracy. [Solution] The electromagnetic noise analysis device 1 includes: a noise spectrum analysis unit that performs frequency-axis noise analysis on any observation point of a power conversion circuit in which at least two switches are connected between power supplies, representing each switch as a voltage source or current source on the frequency axis; a voltage source / current source noise source parameter generation unit that generates a parameter table for representing switching operation as a voltage source or current source on the frequency axis according to operating conditions including power supply voltage, gate resistance of each switch, or current; a worst-case condition extraction unit that extracts phase relationships and current amounts in which the noise amount can become the worst-case condition in the time-axis operation of each switch based on control; and a worst-case condition noise source model generation unit that sets the worst-case condition noise source parameters using the extraction results by the worst-case condition extraction unit.

Description

Technical Field

[0001] The present invention relates to the configuration and method of an electromagnetic noise analysis device, and particularly relates to a technology effective for electromagnetic noise analysis on the frequency axis.

Background Art

[0002] In various industrial fields, social infrastructure, and in-vehicle fields, as the electrification of systems and devices expands, it is important to operate electronic systems and devices safely and securely and continuously provide value.

[0003] Therefore, in the design process of electronic systems and devices, by utilizing EMC simulation (EMC: Electromagnetic Compatibility), prevention of rework through pre-verification and shortening and efficiency improvement of the design period by narrowing down the verification target are carried out.

[0004] Also, even when product specifications or components are changed, analysis using EMC simulation is performed, and it is necessary to construct an EMC analysis process using highly accurate and highly efficient analysis techniques.

[0005] As background art in this technical field, for example, there is a technology such as Patent Document 1. Patent Document 1 discloses a noise analysis device capable of easily analyzing the noise of a device to be analyzed.

[0006] Also, Patent Document 2 discloses a noise analysis device capable of quickly and accurately deriving the calculation result of observed noise even when the on-period length and off-period length of a semiconductor element change.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

[0008] Incidentally, in EMC verification, noise prediction through analysis is possible by using a noise analysis model based on an equivalent circuit. This electromagnetic noise analysis using EMC simulation includes time-domain analysis, which operates the device model, and frequency-domain analysis.

[0009] While time-domain noise analysis can be accurate depending on the device model, it presents challenges for high-frequency analysis (50MHz and above) due to its extremely long analysis time and deteriorating convergence as the model size increases.

[0010] On the other hand, while frequency-axis noise analysis can be performed in a relatively short time, there are challenges in reproducing operating conditions associated with physical phenomena such as ringing caused by current dependence. Furthermore, since noise is often evaluated based on its peak value over a certain period of time, there are also challenges in setting the worst-case conditions for frequency-axis noise analysis.

[0011] The aforementioned Patent Document 1 does not adequately address the challenges in frequency-axis analysis described above, and there is room for improvement in terms of noise prediction accuracy.

[0012] Furthermore, since the above-mentioned Patent Document 2 is an analysis method that uses a noise transfer function, there is room for improvement in order to target arbitrary observation points on the circuit.

[0013] Therefore, the object of the present invention is to provide an electromagnetic noise analysis device and electromagnetic noise analysis method that enable electromagnetic noise analysis at any observation point on a circuit, in frequency-axis electromagnetic noise analysis that takes into account various operating conditions such as current dependence and control, which were previously difficult to express except on the time axis, and that can achieve both a reduction in analysis time and an improvement in analysis accuracy. [Means for solving the problem]

[0014] To solve the above problems, the present invention is characterized by comprising: a noise spectrum analysis unit that performs frequency-axis noise analysis on any observation point of a power conversion circuit in which at least two switches are connected between power supplies, representing each switch as a voltage source or current source on the frequency axis; a voltage source / current source noise source parameter generation unit that generates a parameter table for representing switching operation as a voltage source or current source on the frequency axis according to operating conditions including at least one of the power supply voltage, the gate resistance of each switch, and the current; a worst-case condition extraction unit that extracts phase relationships and current amounts in which the noise amount can become the worst-case condition in the time-axis operation of each switch based on control; and a worst-case condition noise source model generation unit that sets the worst-case condition noise source parameters using the extraction results by the worst-case condition extraction unit.

[0015] Furthermore, the present invention is characterized by including the steps of: (a) performing a frequency-axis noise analysis on any observation point of a power conversion circuit in which at least two switches are connected between power supplies, with each switch represented as a voltage source or current source on the frequency axis; (b) generating a parameter table for representing the switching operation as a voltage source or current source on the frequency axis, according to operating conditions including at least one of the power supply voltage, the gate resistance of each switch, and the current; (c) extracting phase relationships and current amounts in which the noise amount may be the worst condition in the time-axis operation of each switch based on control; and (d) setting the worst condition noise source parameters using the extraction results in step (c). [Effects of the Invention]

[0016] According to the present invention, in frequency-axis electromagnetic noise analysis that takes into account various operating conditions such as current dependence and control, which were previously difficult to express except in the time axis, it is possible to perform electromagnetic noise analysis at any observation point on the circuit, and moreover, it is possible to realize an electromagnetic noise analysis device and electromagnetic noise analysis method that can achieve both a reduction in analysis time and an improvement in analysis accuracy.

[0017] As a result, for example, for a power conversion device composed of multiple phases, it becomes possible to analyze the noise characteristics at any observation point on the circuit with high precision and in a short time for operating conditions using control signals such as PWM.

[0018] Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0019] [Figure 1] It is a diagram showing a schematic configuration of an electromagnetic noise analysis device according to an embodiment of the present invention. [Figure 2] It is a diagram schematically showing the function of the worst condition extraction unit 2 in FIG. 1. [Figure 3] It is a diagram schematically showing the functions of the worst condition extraction unit 2 and the worst condition noise source model generation unit 3 in FIG. 1. [Figure 4] It is a diagram schematically showing the functions of the worst condition extraction unit 2 and the worst condition noise source model generation unit 3 in FIG. 1. [Figure 5] It is a diagram schematically showing the functions of the worst condition extraction unit 2 and the worst condition noise source model generation unit 3 in FIG. 1. [Figure 6] It is a diagram schematically showing the function of the noise spectrum analysis unit 4 in FIG. 1. [Figure 7] It is a diagram schematically showing the function of the voltage source / current source noise source parameter generation unit 5 in FIG. 1. [Figure 8] It is a diagram schematically showing the function of the voltage source / current source noise source parameter generation unit 5 in FIG. 1. [Figure 9] It is a diagram schematically showing the function of the voltage source / current source noise source parameter generation unit 5 in FIG. 1. [Figure 10] It is a diagram schematically showing the electromagnetic noise analysis method by the electromagnetic noise analysis device in FIG. 1.

Modes for Carrying Out the Invention

[0020] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, identical components are denoted by the same reference numerals, and detailed descriptions of overlapping parts are omitted. [Examples]

[0021] Referring to Figures 1 to 10, an electromagnetic noise analysis apparatus and electromagnetic noise analysis method according to an embodiment of the present invention will be described.

[0022] Figure 1 shows a schematic configuration of the electromagnetic noise analysis device 1 according to this embodiment.

[0023] As shown in Figure 1, the electromagnetic noise analysis device 1 of this embodiment comprises, as its main components, a worst-case condition extraction unit (phase / current) 2, a worst-case condition noise source model generation unit 3, a noise spectrum analysis unit 4, a voltage source / current source noise source parameter generation unit 5, an equivalent circuit model generation unit 6, and an analysis result determination unit 7.

[0024] Figure 1 shows an example in which the electromagnetic noise analysis device 1 is configured to include memory devices 8a, 8b, and 8c. However, each memory device 8a, 8b, and 8c may be installed externally and connected to the electromagnetic noise analysis device 1 by wired or wireless communication. The same applies to memory devices 8d, 8e, and 8f, which will be described later.

[0025] The worst-case condition extraction unit (phase / current) 2 acquires control data for various electronic systems and devices stored in the memory 8a and extracts the phase relationship and current amount that can result in the worst-case noise condition in the time-axis operation of each switch in the electronic systems and devices (especially between power supplies) based on the control.

[0026] Furthermore, the worst-case condition extraction unit (phase / current) 2 acquires device data (measurement data, specifications, etc.) of various electronic systems and equipment stored in the memory 8b, and generates ideal waveform data based on the device data.

[0027] The worst-case noise source model generation unit 3 sets the noise source parameters for the worst-case conditions using the extraction results from the worst-case condition extraction unit (phase / current) 2 and the parameter table generated by the voltage source / current source noise source parameter generation unit 5.

[0028] The noise spectrum analysis unit 4 performs a frequency-axis noise analysis on any observation point in a power conversion circuit in which at least two switches are connected between the power supplies of various electronic systems and devices, based on the worst-case noise source parameters set by the worst-case noise source model generation unit 3 and the equivalent circuit model generated by the equivalent circuit model generation unit 6, representing each switch as a voltage source or current source on the frequency axis.

[0029] The voltage source / current source noise source parameter generation unit 5 acquires device data (measurement data, specifications, etc.) of various electronic systems and equipment stored in the memory 8b, and design and structural data of various electronic systems and equipment stored in the memory 8c. Based on the ideal waveform data generated by the worst condition extraction unit (phase / current) 2, the device data, and the design and structural data, it generates a parameter table for representing the switching operation as a voltage source or current source on the frequency axis, according to the operating conditions including at least one of the power supply voltage of various electronic systems and equipment, the gate resistance of each switch, and the current.

[0030] The equivalent circuit model generation unit 6 acquires design and structural data of various electronic systems and devices stored in the memory 8c and generates an equivalent circuit model. By using the equivalent circuit model generated by the equivalent circuit model generation unit 6 for frequency-axis noise analysis in the noise spectrum analysis unit 4, the analysis accuracy can be further improved.

[0031] The analysis result determination unit 7 determines the result of the frequency-axis noise analysis performed by the noise spectrum analysis unit 4 by comparing it with a predetermined threshold value set in advance. In addition to peak detection, quasi-peak detection and average values ​​may also be used as threshold values, in which case the offset is reflected in the execution result and the converted value is compared. Furthermore, depending on the resolution bandwidth of the spectrum analyzer, the offset is reflected as necessary and the converted value is compared.

[0032] The determination result from the analysis result determination unit 7 is stored in the memory 8c. The analysis result determination unit 7 compares the results of the frequency axis noise analysis performed by the noise spectrum analysis unit 4 with a predetermined threshold and makes a determination. If the threshold (regulation value) is exceeded, the result is fed back into the design and structure data. For example, the noise filter configuration is changed and the analysis is re-analyzed so that it falls below the threshold (regulation value).

[0033] Figure 2 schematically shows the function of the worst-case condition extraction unit 2 in Figure 1. (1) and (2) in Figure 2 indicate the timing of the recovery switching of the maximum current and the timing of the simultaneous switching of two phases (three phases simultaneously if the condition is 0A), respectively.

[0034] As shown in Figure 2, the worst-case condition extraction unit 2 generates an ideal analysis model (without parasitic parameters) based on the control data of various electronic systems and devices stored in memory 8a and the design and structural data of various electronic systems and devices stored in memory 8c, and acquires ideal waveform data (voltage and current) corresponding to the control data (PWM). The ideal waveform data (voltage and current) is stored in memory 8d.

[0035] Figure 3 is a schematic diagram illustrating the functions of the worst-case condition extraction unit 2 and the worst-case condition noise source model generation unit 3 shown in Figure 1.

[0036] As shown in Figure 3, the worst condition extraction unit 2 extracts the recovery switching of the maximum current on the upper and lower arms of each phase at the timing of the recovery switching of the maximum current in (1). Also, at the timing of the simultaneous switching of two phases (three phases simultaneously if the condition is 0A) in (2), it extracts the total current and the time difference below the threshold for simultaneous switching of two or more phases. Then, it extracts the combination of the switching pattern with the largest total current (recovery priority) and the smallest time difference as the worst condition. In other words, the worst condition is extracted using control data and ideal waveform data (voltage and current).

[0037] Figure 4 schematically shows the functions of the worst-case condition extraction unit 2 and the worst-case condition noise source model generation unit 3 in Figure 1, and illustrates an example of switching at the timing of the recovery switching of the maximum current in (1).

[0038] As shown in Figure 4, a voltage source is set for the turn-on transistor and a current source is set for the recovery transistor.

[0039] Figure 5 schematically shows the functions of the worst-case condition extraction unit 2 and the worst-case condition noise source model generation unit 3 in Figure 1, and shows an example of switching at the timing of simultaneous two-phase switching (three-phase simultaneous switching under the 0A condition) in (2).

[0040] As shown in Figure 5, similar to the timing of the recovery switching of the maximum current in (1), the difference in the switching timing of each phase is reflected in the phase difference. Also, a voltage source is set for the turn-on transistor and a current source for the recovery transistor.

[0041] Figure 6 is a schematic diagram illustrating the function of the noise spectrum analysis unit 4 in Figure 1.

[0042] As shown in Figure 6, we analyze one of the worst-case conditions.

[0043] Alternatively, the peak noise level on the frequency axis can be obtained as an output by taking the peak value envelope of multiple worst-case conditions. In this case, identifying the worst-case conditions for each frequency can also shorten the time required for reanalysis.

[0044] Furthermore, depending on the design changes, it may be beneficial to reanalyze the worst-case scenarios for anticipated impacts. Reanalyzing the worst-case scenarios for anticipated impacts due to design changes improves accuracy.

[0045] However, if the design and structural data are changed during the reanalysis, the worst-case scenario may differ, so it may be advisable to re-analyze all conditions.

[0046] Figure 7 is a schematic diagram illustrating the function of the voltage source / current source noise source parameter generation unit 5 shown in Figure 1.

[0047] The parasitic parameter / passive element extraction unit (including gate resistor) 13 acquires design and structural data of various electronic systems and devices stored in the memory 8c, and extracts parasitic parameters and passive elements of various electronic systems and devices based on the design and structural data.

[0048] The device model generation unit 14 acquires device data (such as measurement data and specifications) of various electronic systems and equipment stored in the memory 8b, and generates a device model based on the device data.

[0049] The switching characteristic analysis model generation unit 15 generates a switching characteristic analysis model based on the parasitic parameters and passive elements extracted by the parasitic parameter / passive element extraction unit (including gate resistance) 13 and the device model generated by the device model generation unit 14. The switching characteristic analysis model generation unit 15 generates a circuit (e.g., a double pulse test) that can evaluate the switching characteristics of the device according to the operating conditions (current, voltage, gate resistance, etc.).

[0050] The noise source parameter extraction unit 16 extracts voltage source noise source parameters and current source noise source parameters based on the switching characteristic analysis model generated by the switching characteristic analysis model generation unit 15 and the ideal waveform data (voltage and current) stored in the memory 8d, and stores them in the memory 8e and memory 8f, respectively.

[0051] Furthermore, some or all of the above processes may be replaced by actual testing. Alternatively, the overall parameter table may be generated by supplementing the results of tests and analyses conducted under certain conditions.

[0052] Figure 8 schematically illustrates the function of the voltage source / current source noise source parameter generation unit 5 in Figure 1, and shows the definition of each parameter in the time-domain waveform.

[0053] As shown in Figure 8, the ringing component is decoupled to generate an ideal trapezoidal wave. For the voltage waveform, the ringing component is decoupled to generate an ideal trapezoidal wave. For the current waveform, it is generated only from the recovery component.

[0054] Figure 9 schematically illustrates the function of the voltage source / current source noise source parameter generation unit 5 in Figure 1, and shows an example of spectral characteristics.

[0055] As shown in Figure 9, the current / voltage source noise source parameters are approximated by the Fourier transform of an ideal trapezoidal wave signal. The graph on the right of Figure 9 shows an example where the rise and fall times are constant. Alternatively, the envelope of the Fast Fourier Transform (FFT) of the trapezoidal wave may be used.

[0056] Figure 10 is a schematic diagram illustrating the electromagnetic noise analysis method using the electromagnetic noise analysis device 1 shown in Figure 1.

[0057] As shown in Figure 10, first, the worst-case condition extraction unit (phase and current) extracts the phase relationships and current amounts that can result in the worst-case noise levels during the time-axis operation of each switch in an electronic system / device (especially between power supplies) based on control.

[0058] Furthermore, the noise source model generation unit 12 sets the voltage source / current source noise source parameters generated by the voltage source / current source noise source parameter generation unit 5 into a voltage source / current source model according to the worst-case conditions.

[0059] Next, the noise spectrum analysis unit performs frequency-axis noise analysis.

[0060] As a result, more accurate LISN voltage AC analysis results (LISN: Pseudo-Power Network) can be obtained, as shown in Figure 10.

[0061] As shown in Figure 10, when comparing the analysis results for two conditions, with a maximum current of 20A and 400A, the method of the present invention, based on both a voltage source and a current source, expresses the difference in noise levels due to the current dependence between 20A and 400A (particularly noticeable in ringing above 10MHz), compared to the conventional method based on a voltage source, demonstrating improved analytical accuracy.

[0062] As described above, the electromagnetic noise analysis device 1 of this embodiment includes a noise spectrum analysis unit 4 that performs frequency-axis noise analysis on any observation point of a power conversion circuit in which at least two switches are connected between power supplies, representing each switch as a voltage source or current source on the frequency axis; a voltage source / current source noise source parameter generation unit 5 that generates a parameter table for representing switching operation as a voltage source or current source on the frequency axis according to operating conditions including at least one of the power supply voltage, gate resistance of each switch, and current; a worst-case condition extraction unit (phase / current) 2 that extracts phase relationships and current amounts in which the noise amount may be the worst-case condition in the time-axis operation of each switch based on control; and a worst-case condition noise source model generation unit 3 that sets the worst-case condition noise source parameters using the extraction results from the worst-case condition extraction unit (phase / current) 2.

[0063] This makes it possible to achieve both reduced analysis time and improved analysis accuracy in frequency-axis electromagnetic noise analysis that takes into account various operating conditions such as current dependence and control, which were previously difficult to represent except on the time axis.

[0064] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. [Explanation of Symbols]

[0065] 1…Electromagnetic noise analysis device 2…Worst condition extraction section (phase and current) 3…Worst-condition noise source model generation unit 4…Noise Spectrum Analysis Unit 5…Voltage source / current source noise source parameter generation unit 6...Equivalent circuit model generation unit 7…Analysis result judgment section 8, 8a, 8b, 8c, 8d, 8e, 8f... Memory devices 9…AC motor 10…Smoothing Capacitor 11...Equivalent circuit model generation unit 12... Noise source model generation unit 13…Parasitic parameter / passive element extraction section (including gate resistance) 14…Device model generation unit 15…Switching characteristic analysis model generation unit 16...Noise source parameter extraction unit.

Claims

1. A noise spectrum analysis unit performs frequency-axis noise analysis on any observation point of a power conversion circuit in which at least two switches are connected between power sources, with each switch represented as a voltage source or current source on the frequency axis. A voltage source / current source noise source parameter generation unit generates a parameter table for representing switching operation as a voltage source or current source on the frequency axis, according to operating conditions including at least one of the power supply voltage, the gate resistance of each switch, and the current. A worst-case condition extraction unit extracts the phase relationship and current amount that can result in the worst-case noise condition during the time-axis operation of each of the switches based on the control, A worst-case noise source model generation unit sets the noise source parameters of the worst-case condition using the extraction results from the worst-case condition extraction unit, An electromagnetic noise analysis device characterized by having the following features.

2. An electromagnetic noise analysis device according to claim 1, The system further includes an equivalent circuit model generation unit that acquires design and structural data stored in a memory device and generates an equivalent circuit model. The electromagnetic noise analysis apparatus is characterized in that the noise spectrum analysis unit performs the frequency axis noise analysis based on the worst-case noise source parameters set by the worst-case noise source model generation unit and the equivalent circuit model generated by the equivalent circuit model generation unit.

3. An electromagnetic noise analysis device according to claim 2, An electromagnetic noise analysis device characterized by analyzing one of the worst-case conditions.

4. An electromagnetic noise analysis device according to claim 2, An electromagnetic noise analysis device characterized by taking the envelope of the peak values ​​of the analysis results for multiple worst-case conditions.

5. An electromagnetic noise analysis device according to claim 1, An electromagnetic noise analysis device further comprising an analysis result determination unit that determines the results of frequency-axis noise analysis performed by the noise spectrum analysis unit by comparing them with a predetermined threshold value set in advance.

6. An electromagnetic noise analysis device according to claim 5, An electromagnetic noise analysis device characterized in that, if the results of the frequency axis noise analysis performed by the noise spectrum analysis unit exceed the predetermined threshold, the results are fed back into the design and re-analyzed.

7. Electromagnetic noise analysis method including the following steps: (a) A step of performing a frequency-axis noise analysis on any observation point of a power conversion circuit in which at least two switches are connected between power sources, with each switch represented as a voltage source or current source on the frequency axis. (b) A step of generating a parameter table for representing the switching operation as a voltage source or current source on the frequency axis, depending on the operating conditions, which include at least one of the power supply voltage, the gate resistance of each switch, and the current. (c) A step of extracting the phase relationship and current amount that would result in the worst-case noise level during the time-axis operation of each of the switches based on the control, (d) A step of setting the noise source parameters for the worst condition using the extraction results from step (c).

8. The electromagnetic noise analysis method according to claim 7, (e) The method further includes the step of acquiring design and structural data stored in a memory device and generating an equivalent circuit model, An electromagnetic noise analysis method characterized in that, in step (a), the frequency axis noise analysis is performed based on the worst-case noise source parameters set in step (d) and the equivalent circuit model generated in step (e).

9. The electromagnetic noise analysis method according to claim 8, An electromagnetic noise analysis method characterized by analyzing one of the worst-case conditions.

10. The electromagnetic noise analysis method according to claim 8, An electromagnetic noise analysis method characterized by taking the envelope of the peak values ​​of the analysis results for multiple worst-case conditions.

11. The electromagnetic noise analysis method according to claim 7, (f) An electromagnetic noise analysis method characterized by further comprising the step of determining the result of the frequency axis noise analysis performed in step (a) by comparing it with a predetermined threshold that has been set in advance.

12. The electromagnetic noise analysis method according to claim 11, An electromagnetic noise analysis method characterized in that, if the result of the frequency axis noise analysis performed in step (a) exceeds the predetermined threshold, the result is fed back into the design and re-analyzed.

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