{"id":13928,"date":"2016-05-26T21:31:35","date_gmt":"2016-05-26T21:31:35","guid":{"rendered":"http:\/\/www.iacdrive.com\/2016\/05\/26\/variable-frequency-drive-basics-working-principle\/"},"modified":"2016-05-26T21:31:35","modified_gmt":"2016-05-26T21:31:35","slug":"variable-frequency-drive-basics-working-principle","status":"publish","type":"post","link":"http:\/\/iacdrive.com\/?p=13928","title":{"rendered":"Variable Frequency Drive Basics (Working Principle)"},"content":{"rendered":"<p><strong>Variable Frequency Drive (VFD) Basic Configuration<\/strong><br \/>\nThe basic configuration of a variable frequency drive is as follows.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/vfd-basic-configuration.jpg\" title=\"VFD Basic Configuration\" alt=\"VFD Basic Configuration\" height=\"176\" width=\"640\" \/><br \/>\nFig. 1 Basic configuration of variable frequency drive<\/p>\n<p>Each part of a <a href=\"http:\/\/www.iacdrive.com\">variable frequency drive<\/a> has the following function.<\/p>\n<blockquote>\n<p>\n\t<strong>Converter:<\/strong> Circuit to change the commercial AC power supply to the DC<br \/>\n<strong>Smoothing circuit:<\/strong> Circuit to smooth the pulsation included in the DC<br \/>\n<strong>Inverter:<\/strong> Circuit to change the DC to the AC with variable frequency<br \/>\n<strong>Control circuit:<\/strong> Circuit to mainly control the inverter part\n<\/p>\n<\/blockquote>\n<p><strong>Principle of Converter Operation<\/strong><br \/>\nThe converter part consists of the following parts as following figure shows:<\/p>\n<ul>\n<li>\n\t\tConverter\n\t<\/li>\n<li>\n\t\tInrush current control circuit\n\t<\/li>\n<li>\n\t\tSmoothing circuit\n\t<\/li>\n<\/ul>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/converter-part.jpg\" title=\"Converter part\" alt=\"Converter part\" height=\"280\" width=\"550\" \/><br \/>\nFig. 2 Converter part<\/p>\n<p><em>Method to create DC from AC (commercial) power supply<\/em><br \/>\nA converter is a device to create the DC from the AC power supply. See the basic principle with the single-phase AC as the simplest example. Fig. 3 shows the example of the method to convert the AC to the DC by utilizing a resistor for the load in place of a smoothing capacitor.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/rectifying-circuit.jpg\" title=\"Rectifying circuit\" alt=\"Rectifying circuit\" height=\"196\" width=\"360\" \/><br \/>\nFig. 3 Rectifying circuit<\/p>\n<p>Diodes are used for the elements. These diodes let the current flow or not flow depending on the direction to which the voltage is applied as Fig. 4 shows.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/diode.jpg\" title=\"Diode\" alt=\"Diode\" height=\"77\" width=\"640\" \/><br \/>\nFig. 4 Diode<\/p>\n<p>This diode nature allows the following: When the AC voltage is applied between A and B of the circuit shown in Fig. 3, the voltage is always applied to the load in the same direction shown in Table 1.<\/p>\n<p>Table 1 Voltage applied to the load<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/voltage-applied-to-the-load.jpg\" title=\"Voltage applied to the load\" alt=\"Voltage applied to the load\" height=\"120\" width=\"495\" \/><\/p>\n<p>That is to say, the AC is converted to the DC. (To convert the AC to the DC is generally called rectification.)<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/continuous-waveforms.jpg\" title=\"Continuous waveforms\" alt=\"Continuous waveforms\" height=\"66\" width=\"622\" \/><br \/>\nFig. 5 (Continuous waveforms of the ones in Table 1)<\/p>\n<p>For the three-phase AC input, combining six diodes to rectify all the waves of the AC power supply allows the output voltage as shown in Fig. 6.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/converter-part-waveform.jpg\" title=\"Converter part waveform\" alt=\"Converter part waveform\" height=\"203\" width=\"436\" \/><br \/>\nFig. 6 Converter part waveform<\/p>\n<p><em>Input current waveform when capacitor is used as load <\/em><br \/>\nThe principle of rectification is explained with a resistor. However, a smoothing capacity or is actually used for the load. If a smoothing capacitor is used, the input current waveforms become not sine waveforms but distorted waveforms shown in Fig. 7 since the AC voltage flows only when it surpasses the DC voltage.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/principle-of-converter.jpg\" title=\"Principle of converter\" alt=\"Principle of converter\" height=\"226\" width=\"640\" \/><br \/>\nFig. 7 Principle of converter<\/p>\n<p><em> Inrush current control circuit<\/em><br \/>\nThe basic principle of rectification is explained with a resistor. However, a smoothing capacitor is actually used for the load. A capacitor has a nature to store electricity. At the moment when the voltage is applie<\/p>\n","protected":false},"excerpt":{"rendered":"<p><strong>Variable Frequency Drive (VFD) Basic Configuration<\/strong><br \/>\nThe basic configuration of a variable frequency drive is as follows.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/vfd-basic-configuration.jpg\" title=\"VFD Basic Configuration\" alt=\"VFD Basic Configuration\" height=\"176\" width=\"640\" \/><br \/>\nFig. 1 Basic configuration of variable frequency drive<\/p>\n<p>Each part of a <a href=\"http:\/\/www.iacdrive.com\">variable frequency drive<\/a> has the following function.<\/p>\n<blockquote><p>\n\t<strong>Converter:<\/strong> Circuit to change the commercial AC power supply to the DC<br \/>\n<strong>Smoothing circuit:<\/strong> Circuit to smooth the pulsation included in the DC<br \/>\n<strong>Inverter:<\/strong> Circuit to change the DC to the AC with variable frequency<br \/>\n<strong>Control circuit:<\/strong> Circuit to mainly control the inverter part\n<\/p><\/blockquote>\n<p><strong>Principle of Converter Operation<\/strong><br \/>\nThe converter part consists of the following parts as following figure shows:<\/p>\n<ul>\n<li>\n\t\tConverter\n\t<\/li>\n<li>\n\t\tInrush current control circuit\n\t<\/li>\n<li>\n\t\tSmoothing circuit\n\t<\/li>\n<\/ul>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/converter-part.jpg\" title=\"Converter part\" alt=\"Converter part\" height=\"280\" width=\"550\" \/><br \/>\nFig. 2 Converter part<\/p>\n<p><em>Method to create DC from AC (commercial) power supply<\/em><br \/>\nA converter is a device to create the DC from the AC power supply. See the basic principle with the single-phase AC as the simplest example. Fig. 3 shows the example of the method to convert the AC to the DC by utilizing a resistor for the load in place of a smoothing capacitor.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/rectifying-circuit.jpg\" title=\"Rectifying circuit\" alt=\"Rectifying circuit\" height=\"196\" width=\"360\" \/><br \/>\nFig. 3 Rectifying circuit<\/p>\n<p>Diodes are used for the elements. These diodes let the current flow or not flow depending on the direction to which the voltage is applied as Fig. 4 shows.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/diode.jpg\" title=\"Diode\" alt=\"Diode\" height=\"77\" width=\"640\" \/><br \/>\nFig. 4 Diode<\/p>\n<p>This diode nature allows the following: When the AC voltage is applied between A and B of the circuit shown in Fig. 3, the voltage is always applied to the load in the same direction shown in Table 1.<\/p>\n<p>Table 1 Voltage applied to the load<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/voltage-applied-to-the-load.jpg\" title=\"Voltage applied to the load\" alt=\"Voltage applied to the load\" height=\"120\" width=\"495\" \/><\/p>\n<p>That is to say, the AC is converted to the DC. (To convert the AC to the DC is generally called rectification.)<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/continuous-waveforms.jpg\" title=\"Continuous waveforms\" alt=\"Continuous waveforms\" height=\"66\" width=\"622\" \/><br \/>\nFig. 5 (Continuous waveforms of the ones in Table 1)<\/p>\n<p>For the three-phase AC input, combining six diodes to rectify all the waves of the AC power supply allows the output voltage as shown in Fig. 6.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/converter-part-waveform.jpg\" title=\"Converter part waveform\" alt=\"Converter part waveform\" height=\"203\" width=\"436\" \/><br \/>\nFig. 6 Converter part waveform<\/p>\n<p><em>Input current waveform when capacitor is used as load <\/em><br \/>\nThe principle of rectification is explained with a resistor. However, a smoothing capacity or is actually used for the load. If a smoothing capacitor is used, the input current waveforms become not sine waveforms but distorted waveforms shown in Fig. 7 since the AC voltage flows only when it surpasses the DC voltage.<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/www.iacdrive.com\/iacdrive_image_1\/principle-of-converter.jpg\" title=\"Principle of converter\" alt=\"Principle of converter\" height=\"226\" width=\"640\" \/><br \/>\nFig. 7 Principle of converter<\/p>\n<p><em> Inrush current control circuit<\/em><br \/>\nThe basic principle of rectification is explained with a resistor. However, a smoothing capacitor is actually used for the load. A capacitor has a nature to store electricity. At the moment when the voltage is applie<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[67],"tags":[],"class_list":["post-13928","post","type-post","status-publish","format-standard","hentry","category-iacdrive_blog"],"_links":{"self":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/posts\/13928","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=13928"}],"version-history":[{"count":0,"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/posts\/13928\/revisions"}],"wp:attachment":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13928"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13928"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13928"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}