{"id":108,"date":"2010-01-21T12:35:34","date_gmt":"2010-01-21T17:35:34","guid":{"rendered":"http:\/\/ammonsengineering.com\/blog\/2010\/01\/current-spikes\/"},"modified":"2010-01-26T12:10:26","modified_gmt":"2010-01-26T17:10:26","slug":"current-spikes","status":"publish","type":"post","link":"https:\/\/ammonsengineering.com\/blog\/2010\/01\/current-spikes\/","title":{"rendered":"Current spikes"},"content":{"rendered":"<p>I modified the software to sample the current at different offsets\u00a0from the start of the duty cycle.\u00a0 After 2000 duty cycles, I get a complete picture of the current waveform over a single duty cycle.\u00a0 As long as the system is in a steady state, the waveform is quite repeatable.\u00a0 I used this program to examine the current waveform at different duty cycles and found out why the current measurements are way off during short duty cycles.\u00a0 Take a look at this graph of the current waveform at 25% duty cycle and no load.<\/p>\n<div id=\"attachment_107\" style=\"width: 576px\" class=\"wp-caption alignnone\"><a href=\"http:\/\/ammonsengineering.com\/blog\/wp-content\/uploads\/2010\/01\/Current-waveform-25-percent-duty-cycle.png\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-107\" class=\"size-full wp-image-107 \" title=\"Current waveform, 25% duty cycle, no load\" src=\"http:\/\/ammonsengineering.com\/blog\/wp-content\/uploads\/2010\/01\/Current-waveform-25-percent-duty-cycle.png\" alt=\"Current waveform, 25% duty cycle, no load\" width=\"566\" height=\"308\" srcset=\"https:\/\/ammonsengineering.com\/blog\/wp-content\/uploads\/2010\/01\/Current-waveform-25-percent-duty-cycle.png 944w, https:\/\/ammonsengineering.com\/blog\/wp-content\/uploads\/2010\/01\/Current-waveform-25-percent-duty-cycle-150x81.png 150w, https:\/\/ammonsengineering.com\/blog\/wp-content\/uploads\/2010\/01\/Current-waveform-25-percent-duty-cycle-300x163.png 300w\" sizes=\"auto, (max-width: 566px) 100vw, 566px\" \/><\/a><p id=\"caption-attachment-107\" class=\"wp-caption-text\">Current waveform, 25% duty cycle, no load<\/p><\/div>\n<p>From the graph, I realized there is a large positive current spike when the voltage turns on, and a large negative spike when the voltage turns off.\u00a0 When the duty cycle is short, the two spikes run together and make it impossible to measure the current during the on cycle.\u00a0 After studying it for a while, I decided the filtering capacitors I put on the motor terminals are most likely causing the spikes.\u00a0 There is a large current flow each time a capacitor is charged or discharged.\u00a0 I am going to try removing the capacitors to see if that improves the current waveform.\u00a0 It will\u00a0be a challenge to remove them, though, because when I put them on I wound the wires around the terminals and put a huge blob of solder on them.\u00a0 I could cut them off easily, but then I wouldn&#8217;t be able to put them on again.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I modified the software to sample the current at different offsets\u00a0from the start of the duty cycle.\u00a0 After 2000 duty cycles, I get a complete picture of the current waveform over a single duty cycle.\u00a0 As long as the system is in a steady state, the waveform is quite repeatable.\u00a0 I used this program to [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-108","post","type-post","status-publish","format-standard","hentry","category-software"],"_links":{"self":[{"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/posts\/108","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/comments?post=108"}],"version-history":[{"count":3,"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/posts\/108\/revisions"}],"predecessor-version":[{"id":109,"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/posts\/108\/revisions\/109"}],"wp:attachment":[{"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/media?parent=108"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/categories?post=108"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ammonsengineering.com\/blog\/wp-json\/wp\/v2\/tags?post=108"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}