{"id":2226,"date":"2026-08-04T02:18:34","date_gmt":"2026-08-04T02:18:34","guid":{"rendered":"https:\/\/ovartech.com\/?p=2226"},"modified":"2026-08-04T02:19:33","modified_gmt":"2026-08-04T02:19:33","slug":"what-roles-do-the-pfc-play-inside-obc","status":"publish","type":"post","link":"https:\/\/ovartech.com\/ja\/what-roles-do-the-pfc-play-inside-obc\/","title":{"rendered":"What Roles Do the PFC and Resonant Two-Stage Circuits Play Inside an OBC?"},"content":{"rendered":"<h1 style=\"text-align: center;\"><span style=\"font-size: 18pt;\">What Roles Do the PFC and Resonant Two-Stage Circuits Play Inside an OBC?<\/span><\/h1>\n<p><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\"><strong>Inside a modern On-Board Charger (OBC), the Power Factor Correction (PFC) stage and the resonant DC-DC converter stage form a classic two-stage architecture that together convert grid AC power into controlled DC power for the high-voltage battery.<\/strong> The PFC stage is responsible for shaping the input current, achieving near-unity power factor, and generating a stable intermediate DC bus. The resonant stage then provides galvanic isolation, high-frequency energy transfer, and precise regulation of the battery charging voltage and current. This division of labor enables high efficiency, low harmonic distortion, and compliance with grid and automotive safety standards.<\/span><\/p>\n<table style=\"border-collapse: collapse; width: 100%;\">\n<tbody>\n<tr>\n<td style=\"width: 100%;\"><a href=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz.jpg\"><img decoding=\"async\" class=\"lazyload aligncenter wp-image-2230 size-fusion-800\" src=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-800x537.jpg\" data-orig-src=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-800x537.jpg\" alt=\"PFC\" width=\"800\" height=\"537\" srcset=\"data:image\/svg+xml,%3Csvg%20xmlns%3D%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20width%3D%27800%27%20height%3D%27537%27%20viewBox%3D%270%200%20800%20537%27%3E%3Crect%20width%3D%27800%27%20height%3D%27537%27%20fill-opacity%3D%220%22%2F%3E%3C%2Fsvg%3E\" data-srcset=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-18x12.jpg 18w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-200x134.jpg 200w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-300x201.jpg 300w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-400x268.jpg 400w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-500x336.jpg 500w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-600x403.jpg 600w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-700x470.jpg 700w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-768x516.jpg 768w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-800x537.jpg 800w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz-1024x687.jpg 1024w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/wiOBz.jpg 1168w\" data-sizes=\"auto\" data-orig-sizes=\"(max-width: 800px) 100vw, 800px\" \/><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">1. The Role of the PFC Stage<\/span><\/strong><\/h2>\n<p><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">The front-end Power Factor Correction (PFC) stage is the first conversion block in the OBC. Its primary functions are:<\/span><\/p>\n<ul>\n<li><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\"><strong>Power Factor Correction<\/strong><\/span><br \/>\n<span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">It forces the input current to follow the shape of the AC voltage waveform, achieving a power factor typically greater than 0.99. This minimizes reactive power drawn from the grid and reduces harmonic pollution.<\/span><\/li>\n<li><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\"><strong>AC-to-DC Conversion<\/strong><\/span><br \/>\n<span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">The PFC converts single-phase or three-phase AC input (usually 85\u2013265 V or higher) into a relatively stable high-voltage DC bus, commonly around 400 V.<\/span><\/li>\n<li><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\"><strong>Harmonic Suppression<\/strong><\/span><br \/>\n<span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">By shaping the current, the PFC ensures compliance with international standards such as IEC 61000-3-2, limiting total harmonic distortion (THD).<\/span><\/li>\n<\/ul>\n<p><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Common topologies for this stage include boost PFC, interleaved boost, and bridgeless totem-pole PFC. In higher-power or bidirectional designs, active switches replace passive diode bridges to improve efficiency and enable reverse power flow.<\/span><\/p>\n<p><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Ovar Tech\u2019s OBC modules, including the 6.6 kW and 11 kW integrated solutions, employ advanced PFC designs that maintain high power factor across a wide input voltage range while supporting both unidirectional and bidirectional operation.<\/span><\/p>\n<h3><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">2. The Role of the Resonant DC-DC Stage<\/span><\/strong><\/h3>\n<p><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">After the PFC creates the intermediate DC bus, the resonant converter stage performs the second conversion. Its key responsibilities are:<\/span><\/p>\n<ul>\n<li><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Galvanic Isolation<\/span><\/strong><br \/>\n<span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">A high-frequency transformer provides electrical isolation between the grid side and the high-voltage battery, satisfying automotive safety requirements (typically reinforced insulation rated for several kilovolts).<\/span><\/li>\n<li><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Voltage Matching and Regulation<\/span><\/strong><br \/>\n<span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">The resonant stage steps the intermediate DC bus voltage up or down to match the battery voltage range (commonly 200\u2013450 V for 400 V platforms or 400\u2013850 V for 800 V platforms). It also regulates charging current according to Battery Management System (BMS) commands.<\/span><\/li>\n<li><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">High Efficiency through Soft Switching<\/span><\/strong><br \/>\n<span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Resonant topologies such as LLC or CLLC achieve Zero-Voltage Switching (ZVS) or Zero-Current Switching (ZCS). This dramatically reduces switching losses, allowing high-frequency operation (100\u2013500 kHz) and smaller magnetic components.<\/span><\/li>\n<li><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Bidirectional Capability (in advanced designs)<\/span><\/strong><br \/>\n<span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">When a CLLC or Dual Active Bridge topology is used, the resonant stage can reverse power flow, enabling Vehicle-to-Grid (V2G) and Vehicle-to-Load (V2L) functions.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Ovar Tech\u2019s bi-directional 11 kW OBC + 3 kW DC-DC modules utilize CLLC resonant converters, achieving peak efficiencies of up to 95.5 % while supporting both charging and energy export.<\/span><\/p>\n<table style=\"border-collapse: collapse; width: 100%;\">\n<tbody>\n<tr>\n<td style=\"width: 1377px;\"><a href=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ.jpg\"><img decoding=\"async\" class=\"lazyload wp-image-2232 size-fusion-800 aligncenter\" src=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-800x537.jpg\" data-orig-src=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-800x537.jpg\" alt=\"\" width=\"800\" height=\"537\" srcset=\"data:image\/svg+xml,%3Csvg%20xmlns%3D%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20width%3D%27800%27%20height%3D%27537%27%20viewBox%3D%270%200%20800%20537%27%3E%3Crect%20width%3D%27800%27%20height%3D%27537%27%20fill-opacity%3D%220%22%2F%3E%3C%2Fsvg%3E\" data-srcset=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-18x12.jpg 18w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-200x134.jpg 200w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-300x201.jpg 300w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-400x268.jpg 400w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-500x336.jpg 500w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-600x403.jpg 600w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-700x470.jpg 700w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-768x516.jpg 768w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-800x537.jpg 800w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ-1024x687.jpg 1024w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/VTXeQ.jpg 1168w\" data-sizes=\"auto\" data-orig-sizes=\"(max-width: 800px) 100vw, 800px\" \/><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">3. Why the Two-Stage Architecture Is Preferred<\/span><\/strong><\/h4>\n<p><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Separating the functions into PFC and resonant stages offers several advantages:<\/span><\/p>\n<ul>\n<li><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Each stage can be optimized independently for its specific task.<\/span><\/li>\n<li><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">The intermediate DC bus acts as an energy buffer, improving transient response and system stability.<\/span><\/li>\n<li><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Isolation is confined to the high-frequency resonant stage, reducing the size and cost of the isolation transformer.<\/span><\/li>\n<li><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Soft-switching in the resonant stage allows higher switching frequencies, resulting in higher power density.<\/span><\/li>\n<\/ul>\n<p dir=\"auto\"><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">In contrast, single-stage topologies exist but generally struggle to simultaneously achieve high power factor, isolation, and wide voltage regulation while maintaining efficiency.<\/span><\/p>\n<h5><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">4. Interaction Between the Two Stages<\/span><\/strong><\/h5>\n<p><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">The PFC stage regulates the intermediate DC bus voltage (typically fixed or with a limited range), while the resonant stage handles the wide output voltage variation required by the battery. Communication between the stages and with the vehicle BMS ensures coordinated control of power, voltage, and current. Protection functions such as over-voltage, over-current, and short-circuit detection are implemented at both stages for comprehensive system safety.<\/span><\/p>\n<h6><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">5. Summary of Functional Division<\/span><\/strong><\/h6>\n<table style=\"border-collapse: collapse; width: 100%;\">\n<tbody>\n<tr>\n<td style=\"width: 100%;\"><a href=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu.jpg\"><img decoding=\"async\" class=\"lazyload wp-image-2237 size-fusion-800 aligncenter\" src=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-800x365.jpg\" data-orig-src=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-800x365.jpg\" alt=\"\" width=\"800\" height=\"365\" srcset=\"data:image\/svg+xml,%3Csvg%20xmlns%3D%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20width%3D%27800%27%20height%3D%27365%27%20viewBox%3D%270%200%20800%20365%27%3E%3Crect%20width%3D%27800%27%20height%3D%27365%27%20fill-opacity%3D%220%22%2F%3E%3C%2Fsvg%3E\" data-srcset=\"https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-18x8.jpg 18w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-200x91.jpg 200w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-300x137.jpg 300w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-400x182.jpg 400w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-500x228.jpg 500w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-600x274.jpg 600w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-700x319.jpg 700w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-768x350.jpg 768w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-800x365.jpg 800w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-1024x467.jpg 1024w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu-1200x547.jpg 1200w, https:\/\/ovartech.com\/wp-content\/uploads\/2026\/08\/iY8Hu.jpg 1408w\" data-sizes=\"auto\" data-orig-sizes=\"(max-width: 800px) 100vw, 800px\" \/><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&nbsp;<\/p>\n<p><strong><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">Conclusion<\/span><\/strong><\/p>\n<p><span style=\"font-family: arial, helvetica, sans-serif; font-size: 14pt;\">In an On-Board Charger, the PFC stage and the resonant DC-DC stage work as complementary partners. The PFC ensures clean, efficient power draw from the AC grid and creates a stable intermediate bus, while the resonant stage delivers isolated, precisely regulated power to the high-voltage battery with minimal losses. This two-stage architecture remains the industry standard for high-performance OBCs. Ovar Tech\u2019s product portfolio, spanning 6.6 kW to 11 kW integrated and bi-directional solutions, demonstrates how carefully engineered PFC and resonant stages can deliver high efficiency, compact size, and robust reliability for commercial vehicles, passenger cars, and marine applications.<\/span><\/p>","protected":false},"excerpt":{"rendered":"<p>What Roles Do the PFC and Resonant Two-Stage Circuits Play  [&#8230;]<\/p>","protected":false},"author":2,"featured_media":2232,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"content-type":"","footnotes":""},"categories":[126],"tags":[],"class_list":["post-2226","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tips-tricks"],"acf":[],"_links":{"self":[{"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/posts\/2226","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/comments?post=2226"}],"version-history":[{"count":13,"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/posts\/2226\/revisions"}],"predecessor-version":[{"id":2242,"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/posts\/2226\/revisions\/2242"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/media\/2232"}],"wp:attachment":[{"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/media?parent=2226"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/categories?post=2226"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ovartech.com\/ja\/wp-json\/wp\/v2\/tags?post=2226"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}