Keysight Quickly Generate Power Transients for Testing Automotive Electronics Application Note
Introduction Electronic control units (ECUs) and other automotive electronic devices must be immune to the harsh power systems in which they operate. Power system surges, drop-outs, and other types of transients are common, so automotive ECUs and electronic devices need to be thoroughly validated to assure proper and reliable operation. To assist validation, standard ISO test specifications have been developed that replicate the power transients seen in automotive applications. These specifications are rigorous, and the test equipment required to generate these transients is specialized and expensive. A couple of issues arise as a result: This equipment typically remains in the quality control lab, limiting its availability. Most companies have their own adaption of the ISO standard, which usually evolves over time with the increasing electrification of automobiles. The specialized equipment may not keep up with, or provide the flexibility, to address these evolving needs of individual companies. The Keysight Technologies N7900A Advanced Power System, 14585A Control and Analysis software, and N6705B DC Power Analyzer are tools at your disposal that provide an easy way to quickly create and customize a variety of power transients that you can run at your own bench or test system. With this you can gain valuable insight about your device s operation without waiting for and tying up expensive, specialized equipment. This application note tells how you can make use of these products, especially the 14585A software, to quickly and easily generate power transients for performing this testing.
03 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note Tools for generating power transients Before discussing techniques for generating waveforms, let s first take a quick look at the tools available so we can then understand how they are applied for generating automotive power transients. N7900A Advanced Power System (APS) The N7900A APS, shown in Figure 1, is a family of advanced 1 and 2 kw single output DC power sources with up to 160 VDC out. They can be readily paralleled for even greater current and power when needed. The N7900A s output transitions from zero to full output voltage in under 0.5 ms. Fast-slewing together with built-in capabilities for running arbitrary waveforms (ARBs) enables it to generate most all of the dynamic power disturbances defined in ISO 16750-2 and other similar standards. Figure 1. N7900A Advanced Power System (APS) 14585A Control and Analysis software The 14585A, shown in Figure 2, is an intuitive-to-use graphical interface that runs on a PC. It lets you remotely set up and control, and then retrieve, display, and analyze measurement results from either the N7900A or N6705B. Most importantly it includes extensive capabilities for ARB creation and control that are very beneficial for quickly generating automotive power transients, including: A large library of pre-defined waveform components An extensive list of math expressions and editor for creating formula-based waveform components Tools for editing waveform component sequences for creating complex transients Utilities for importing and quickly modifying.csv (comma separated values) waveform files Ability to record, modify, and playback transients from either the N6705B or N7900A Utilities for saving and recalling transients as either.csv files or high-level constructs that can be easily edited and saved as new power transients Figure 2. 14585A Control and Analysis software
04 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note N6705B DC Power Analyzer The N6705B DC Power Analyzer, shown in Figure 3, is a mainframe that holds from one to four advanced DC power modules. Higher performance DC power modules suited for ARB generation are available having up to 500 W and 60 V out. While the N6705B is readily operated using the 14585A software, it also incorporates a full-featured front panel for directly configuring and running power transients as a stand-alone system. Details on this approach are provided in our application note Bench-Top Test and Debug of Power Transient Issues for Automotive and Aerospace/Defense Applications, part number 5990-4122EN. Figure 3. N6705B DC Power Analyzer and DC power module Quickly create a starting profile transient with pre-defined waveform components Let s explore how to generate a power transient for engine starting immunity testing. In the 14585A software waveforms are constructed using a sequence of components. The pre-defined waveform components allows us to quickly construct a common starting profile power transient, as shown in Figure 4. This starting profile is documented in the ISO 16750-2 specification. Parameter U S U S6 U A t f t 6 t 7 t 8 t r Value 12 V 4.5 V 6.5 V 5 ms 15 ms 50 ms 10 s 100 ms Figure 4. Starting profile power transient waveform
05 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note You can quickly create this waveform in four easy steps using the 14585A software 1. Define the waveform shape, including voltage levels, transition and dwell times and frequencies as shown in Figure 4. Count the number of individual sections for example, here we have a ramp down, a ramp up, a sine wave (it does not matter how many cycles) and a final ramp up. Thus this waveform has four sections. These become individual components in the waveform sequence. 2. Once the 14585A software is running, select the ARB tab on the top to display the ARB waveform operating screen, as shown in Figure 5. As these automotive disturbances are voltage transients, select CD ARB for the output voltage. For the N6705B you have the choice of using either sequence ARBs or constant dwell (CD) ARBs. For the N7900A only CD ARBs are available. a. The sequence ARBs have up to 512 points of magnitude and dwell time pairs. b. The CD ARBs have up to 64K points of magnitude values, all sharing a common dwell time setting. 3. Select Add to add the first component to the waveform sequence. Both the first, second, and forth components are ramps while the third component is a sine wave. As you add each component to the waveform sequence edit its parameters as shown in Figure 6. Press Done after editing each component to add it to the waveform sequence. 4. When you are finished with the ARB waveform sequence it should look as shown in Figure 7. You can name and save the ARB waveform sequence by selecting Save Waveform in the file pull-down menu located on the top of the screen. This will save it as a high-level construct having a.wfpk extension. These can be easily edited using the 14585A software for making modifications or creating new transients. An ARB can also be converted and saved as a.csv data file. These are not as easily edited but they use a basic data format that is compatible with most other programs. Figure 5. Creating an ARB waveform in 14585A software
06 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note (a) (b) (c) (d) Figure 6. Parameter settings of waveform components Figure 7. Completed ARB waveform sequence for the starting profile
07 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note Running your new power transient waveform From the ARB operation screen you have the choice of running the ARB waveform either once, a specified number of cycles, or continuously. Most automotive transients are run on a one cycle basis. When connected to an N6705B or N7900A the ARB waveform can be initiated by pressing the ARB run button located on the lower right hand side of any of the 14585A s operating screens. As one example we ran the ARB in conjunction with capturing it from the 14585A s scope operating screen so that we could easily verify our starting profile s wave shape is indeed correct. This result is shown in Figure 8. Figure 8. Verifying the starting profile with the 14585A s scope mode
08 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note Quickly modifying your power transient waveform A key advantage of using the14585a software is the ease and speed of making modifications to ARB waveforms you have already created. They can then be re-saved, or given another name to serve as a new ARB waveform to address evolving or new standards and requirements. An area of evolving requirements is newer starting profiles resulting from higher-power starting systems supporting things like engine start-stop operation. To show how an ARB sequence can be easily modified we will replace the pre-defined sine wave sequence component with a formula-based rectified sine wave component in the starting profile transient we previously created. You can modify this waveform in three easy steps using the 14585A software: 1. From the 14585A software s ARB operation screen, navigate to the third ARB waveform component block of the ARB waveform sequence displayed in the middle of the screen. Navigate using the right or left block arrows on either side of the sequence. Click on Modify when the desired waveform sequence component is highlighted. 2. Select the Formula tab in the lower left area that incorporates the various types of components available for constructing ARB waveform sequences. In this way you can replace the existing pre-defined built-in sine wave component with a formula-based one. This is shown in Figure 9. 3. Enter the formula to create the new ARB waveform component as shown and press Done. The component in the ARB waveform sequence will be modified accordingly 4. The new ARB waveform can be saved under the existing name or assigned a new name, leaving the original ARB waveform unchanged. Figure 9. Entering an ARB waveform sequence component as a function
09 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note Figure 10: Verifying the modified starting profile with the 14585A s scope mode Importing, modifying, running, and saving externally furnished transients Often there is the need to run complex power transients that were captured directly with an oscilloscope on an automobile or externally created from another software package. Data files of these transients will likely be in a.csv format with a common dwell time value for all the points. A useful characteristic of this solution platform is that its constant dwell (CD) ARB capability can run complex, non-repetitive transient waveforms of up to 64K points deep. While the complex starting profiles are examples of this, they were created within the 14585A software using built-in waveform sequence components. The 14585A also provides the ability to easily import, modify, run, and save externally created.csv ARB data files as well. In this example we will import a.csv file for an unsuppressed load-dump profile into the 14585A software, to be run on an N7900A APS. The load-dump profile had been externally created and saved as a.csv file of amplitude values. The unsuppressed load-dump peaks at 79 volts with an overall duration of approximately 500 ms. However, we will first use the 14585A s waveform editing tools to clip the load-dump at 34 volts, turning it into a suppressed load-dump profile, before running it. The 14585A s editing tools make it a simple matter to make a large number of modifications to.csv waveform files. You can import, modify, and save this waveform in three easy steps using the 14585A software: 1. Import the new.csv file by choosing to create a new ARB sequence and selecting Import and then New from the ARB sequence component section. When the file is first brought in the 14585A will ask you to specify the dwell time. This can be changed later as well, to change the duration of this ARB sequence component. This step is illustrated in Figure 11. 2. To clip the waveform select Modify. This will bring the waveform up in the graphical editor shown in Figure 12. This lets you quickly make a number of different edits to the waveform. For our example we selected Clip and set the upper level to 34 V and lower level to zero. We then pressed Execute to make the edits to the waveform. 3. We then selected SAVE RESULT which adds the suppressed waveform file to the collection of existing imported sequence components. The 14585A adds a numerical increment to the file name to distinguish it from the original file. We went ahead and renamed it with a b suffix, consistent with how ISO documents the suppressed load-dump profile.
10 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note Figure 11. Importing a.csv waveform file into the 14585A software Figure 12. Clipping the waveform using the 14585A graphical waveform file editor
11 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note The imported load-dump waveform file started and ended at 13.5 volts. In this case there was no need to add other components at either end of the sequence, but it would be a simple matter to do so as we had previously shown. With the N7900A APS connected, turned on, and set to 13.5 V output, we ran our suppressed loaddump transient. The result was verified using the 14585A s scope operation mode, as shown in Figure 13. Figure 13. Verifying the suppressed load-dump transient using the 14585A s scope mode Conclusion Electronic control units (ECUs) and other electronic devices used in automotive applications must be immune to the harsh power systems in which they operate. To successfully design for these environments and meet performance goals, product development engineers must incorporate thorough electrical power transient disturbance testing as an iterative part of their process. Test equipment for performing power transient disturbance testing to ISO and other industry standards is specialized and expensive, often limiting its availability being assigned to a central QC lab. The Keysight N7900A Advanced Power System, 14585A Control and Analysis software, and N6705B DC Power Analyzer are affordable tools that allow you to quickly generate automotive power transients for performing disturbance testing at the convenience of your engineering bench. You can now quickly gain valuable insights about your device s performance without tying up the expensive and often unavailable QC lab test equipment.
12 Keysight Quickly Generate Power Transients for Testing Automotive Electronics - Application Note Evolving Since 1939 Our unique combination of hardware, software, services, and people can help you reach your next breakthrough. We are unlocking the future of technology. From Hewlett-Packard to Agilent to Keysight. For more information on Keysight Technologies products, applications or services, please contact your local Keysight office. The complete list is available at: www.keysight.com/find/contactus Americas Canada (877) 894 4414 Brazil 55 11 3351 7010 Mexico 001 800 254 2440 United States (800) 829 4444 mykeysight www.keysight.com/find/mykeysight A personalized view into the information most relevant to you. http://www.keysight.com/find/emt_product_registration Register your products to get up-to-date product information and find warranty information. Keysight Services www.keysight.com/find/service Keysight Services can help from acquisition to renewal across your instrument s lifecycle. Our comprehensive service offerings onestop calibration, repair, asset management, technology refresh, consulting, training and more helps you improve product quality and lower costs. Keysight Assurance Plans www.keysight.com/find/assuranceplans Up to ten years of protection and no budgetary surprises to ensure your instruments are operating to specification, so you can rely on accurate measurements. Keysight Channel Partners www.keysight.com/find/channelpartners Get the best of both worlds: Keysight s measurement expertise and product breadth, combined with channel partner convenience. Asia Pacific Australia 1 800 629 485 China 800 810 0189 Hong Kong 800 938 693 India 1 800 11 2626 Japan 0120 (421) 345 Korea 080 769 0800 Malaysia 1 800 888 848 Singapore 1 800 375 8100 Taiwan 0800 047 866 Other AP Countries (65) 6375 8100 Europe & Middle East Austria 0800 001122 Belgium 0800 58580 Finland 0800 523252 France 0805 980333 Germany 0800 6270999 Ireland 1800 832700 Israel 1 809 343051 Italy 800 599100 Luxembourg +32 800 58580 Netherlands 0800 0233200 Russia 8800 5009286 Spain 800 000154 Sweden 0200 882255 Switzerland 0800 805353 Opt. 1 (DE) Opt. 2 (FR) Opt. 3 (IT) United Kingdom 0800 0260637 For other unlisted countries: www.keysight.com/find/contactus (BP-9-7-17) www.keysight.com/find/n7900 www.keysight.com/find/14585 www.keysight.com/find/n6705 DEKRA Certified ISO9001 Quality Management System www.keysight.com/go/quality Keysight Technologies, Inc. DEKRA Certified ISO 9001:2015 Quality Management System This information is subject to change without notice. Keysight Technologies, 2017 Published in USA, December 1, 2017 5992-0469EN www.keysight.com