1 00:00:17,090 --> 00:00:22,170 Good morning to all of you, in this video capsule we shall see a bird's eye view of 2 00:00:22,170 --> 00:00:25,570 the DC-DC converter system. 3 00:00:25,570 --> 00:00:26,570 . 4 00:00:26,570 --> 00:00:28,740 Consider a load such as this. 5 00:00:28,740 --> 00:00:33,890 This load is supposed to get only a DC voltage. 6 00:00:33,890 --> 00:00:39,280 The DC voltage can be given by a DC source such as this. 7 00:00:39,280 --> 00:00:47,090 The DC source that we have used is a battery, however the battery and the load maybe incompatible. 8 00:00:47,090 --> 00:00:56,219 For example, the battery maybe a 12 volt battery or 24 volt battery or 48 volt battery and 9 00:00:56,219 --> 00:01:00,870 the load maybe a 5 volt load. 10 00:01:00,870 --> 00:01:08,200 In such a case the battery cannot be directly connected to the load which expects of high 11 00:01:08,200 --> 00:01:09,200 volt. 12 00:01:09,200 --> 00:01:15,220 We need to have a power interface between chord and DC-DC converter and this was the 13 00:01:15,220 --> 00:01:19,060 focus of optic and this is what we are supposed to do and design. 14 00:01:19,060 --> 00:01:31,170 However, in most cases the input may not be a battery, the input maybe the AC grid itself. 15 00:01:31,170 --> 00:01:39,030 If it is the AC grid, then the input wave shape will be an alternating bidirectional 16 00:01:39,030 --> 00:01:41,890 voltage wave shape 230 volts rms. 17 00:01:41,890 --> 00:01:48,060 Now, this is not directly compatible to the DC-DC converter input. 18 00:01:48,060 --> 00:01:55,429 Therefore, we need to do a further power conversion for this particular wave shape, that is we 19 00:01:55,429 --> 00:02:00,940 rectify it using a rectifier and make the wave shape into a unidirectional wave shape. 20 00:02:00,940 --> 00:02:06,370 This unidirectional wave shape is highly varying and the system further not compatible directly 21 00:02:06,370 --> 00:02:10,180 to be given to the input of the DC-DC converter. 22 00:02:10,180 --> 00:02:16,240 So, we use another interface called the filter. 23 00:02:16,240 --> 00:02:24,270 The job of the filter is to transform this highly varying unidirectional voltage into 24 00:02:24,270 --> 00:02:27,799 a low ripple unregulated voltage. 25 00:02:27,799 --> 00:02:34,750 This low ripple unregulated voltage is fed to the input of DC-DC converter. 26 00:02:34,750 --> 00:02:44,159 This gets transformed into a high quality DC output which can be fed to the particular 27 00:02:44,159 --> 00:02:47,349 application of the load which expects a pure DC. 28 00:02:47,349 --> 00:02:48,349 (Refer Time.. 29 00:02:48,349 --> 00:02:54,900 If you look at the rectifier, rectifier is nothing but a simple diode. 30 00:02:54,900 --> 00:03:03,689 It may be a half bridge rectifier or a full bridge rectifier, but we shall discuss the 31 00:03:03,689 --> 00:03:08,980 most popular rectifier which is used in most of the products today which is the full bridge 32 00:03:08,980 --> 00:03:10,690 rectifier. 33 00:03:10,690 --> 00:03:17,870 This would be followed by a filter which could be LC filter or inductor capacitor filter 34 00:03:17,870 --> 00:03:20,719 or just C filter. 35 00:03:20,719 --> 00:03:27,620 Here again we shall discuss the C filter which is the one which is most widely used in most 36 00:03:27,620 --> 00:03:29,310 of the products. 37 00:03:29,310 --> 00:03:36,590 In the case of the DC-DC converters the main components in it are the MOSFET or IGBT or 38 00:03:36,590 --> 00:03:37,590 (Refer Time. 39 00:03:37,590 --> 00:03:44,359 some power semiconductor switch there will be capacitors and there will be inductors. 40 00:03:44,359 --> 00:03:52,579 So, all these major components will be together in specific topologies to achieve specific 41 00:03:52,579 --> 00:03:57,569 outputs which we will discuss later on in this course. 42 00:03:57,569 --> 00:04:04,909 The objective of this particular course is the DC-DC converter design. 43 00:04:04,909 --> 00:04:10,750 However, in the initial stages or initial process we shall discuss the rectifier and 44 00:04:10,750 --> 00:04:13,920 filter because we need to obtain DC output. 45 00:04:13,920 --> 00:04:20,519 The DC output at this point so that can be fed to the input of the DC-DC converter from 46 00:04:20,519 --> 00:04:30,630 the source, the wall outlet source which is a 230 volt AC voltage. 47 00:04:30,630 --> 00:04:39,050 So, the initial discussion this week will focus on the rectifier and filter design.