[MUSIC PLAYING] What we heard already before is that the input voltage isn't constant. It's, in most cases, a certain input voltage range. And if your output voltage is within this input voltage range, you might need or you will need a topology that is able to step up and step down in voltage.
Here, we got this first topology, the buck boost converter. The buck boost converter basically is a mix of a buck stage and a boost stage. Due to this mix, if the input voltage is smaller than the output voltage, it works in boost mode. And if the input voltage is bigger than the output voltage, it works in buck mode.
Within the transfer region, there are two modes possible. Could be that all switches are chopping the same time. This is a bit less efficient due to increased switching current. Or we got a very fast alternation between buck and boost mode. This could cause some jitter and some subharmonic noise.
A big benefit is a very wide input range with only a signal magnetic element. And if you are dealing with high power, or bigger than 100 watts, the two diodes could be also replaced by synchronous rectifiers, but now the controller needs internally four very strong drivers resulting in a big silicon area. So means silicon is money. So we are talking here on a pod that has typically higher cost.
And think about you've got four drivers in a single package. And there is no lossless driving of MOSFETs. There will be a certain amount of driver losses using bigger MOSFETs, maybe 100, 200, 300 milliwatt per FET for drivers. So typically the power losses in silicon could be 500 milliwatt to 1 watt that must be provided a certain terminal interface.
The two buck boost typically handles 50 watts to 150 watts. And a four switch buck boost is able to deliver up to 400 watts. For smaller output power, might be SEPAC better choice because of boom cost.
In all, what we need is a saw and some glue to build the buck boost power stage. We take the buck power stage, and we make a cut at the inductor. Same for the boost power stage. And we glue them together.
And here we see the buck boost power stage itself. Means if we are in buck mode, the boost switch on the right side is not chopping. It's open. And only the high sides which is providing the buck function. And on the other hand, if the input voltage is lowered than the output voltage, we need to boost mode. Means the high side switch on the left side is continuously on. And only tended right hand to low side switch is chopping to provide the boost function. [音乐播放] 我们以前听说过， 输入电压并不是 恒定不变的。 在大多数情况下， 它是一定的输入电压范围。 如果输出电压 介于此输入电压 范围内，您可能 需要或将会 需要一个能够 升高或降低电压的 拓扑。 此处是我们的第一种 拓扑，即降压-升压 转换器。 降压-升压 转换器基本上 是降压级和 升压级的混合。 由于这种混合， 如果输入电压 小于输出 电压， 它会以升压模式工作。 如果输入电压 大于输出电压， 则它会以降压模式工作。 在传输区域内， 有两种可能的模式。 所有开关都可能 同时斩波。 由于开关电流增加， 其效率稍低一些。 或者我们 会在降压 和升压模式之间快速交替。 这可能会导致一定的抖动 和一定的次谐波噪声。 一个重要优势是具有 非常宽的输入范围，只使用 一个信号磁性元件。 如果您要 处理高功率 或大于 100 瓦的 功率，则也可以 将两个二极管替换 为同步整流器， 但现在，控制器 在内部需要 四个非常强大的 驱动器，导致很大的器件 面积。 器件意味着资金。 因此，我们此处将谈一谈通常 具有较高成本的 Pod。 并考虑您已在单一封装内 得到四个驱动器。 而且 MOSFET 没有 无损驱动。 使用较大的 MOSFET 时 将有一定量的驱动器损失， 对于驱动器， 每个 FET 的损失或许为 100、200、 300 毫瓦。 因此一般来说， 器件内的功率损失 可能为 500 毫瓦 至 1 瓦，必须提供 特定的终端接口。 两个降压-升压转换器一般 可处理 50 瓦至 150 瓦。 四开关的降压-升压 能够传输高达 400 瓦。 对于较小的输出功率， 由于成本的原因，SEPAC 可能是 更好的选择。 总之，我们所需的 就是一把锯和 一些胶水来构建 降压-升压功率级。 我们采用 降压功率级， 并对电感器进行削减。 升压功率级也是如此。 然后我们把它们粘在一起。 我们可以在此处看到 降压-升压功率级本身。 这意味着如果我们 处于降压模式， 位于右侧的升压开关 将不会斩波。 它将开路。 只有高侧 提供降压功能。 另一方面， 如果输入电压 低于输出电压，则我们 需要使用升压模式。 这意味着左侧的 高侧开关 持续接通。 而且只有右侧的 低侧开关将会 斩波以提供 升压功能。 This website is under heavy load (queue full) We're sorry, too many people are accessing this website at the same time. We're working on this problem. Please try again later.
