[MUSIC PLAYING] The Cuk converter itself is named by Slobodan Cuk. It's an inverting SEPIC. It's also a flyback typology. Means energy is transferred to the coupling cap once the switch is open. The benefit here is the LC filter is located at the input. And the other LC filter is located at the output. Means we have continuous currents at the input and the output, so ripple on both sides of the converter is very low.
On the other hand, we got two double poles in our power stage that are reducing dynamic a bit. You need high gain in your [INAUDIBLE] amplifier to get a reasonable dynamic performance. And same for all those topologies, if the inductors are coupled, the windings ratio 1 by 1 is mandatory. A boost controller with a single driver, as well, low cost for your design. And also, you can do this with only one switch and only one rectifier, compared to the non-isolated inverting flyback.
Again, clean waveforms, no ringing means low EMI, low radiated emissions. Multiple windings are possible because the output windings are well-coupled on the core. And, well, there is another small drawback. You got a negative output voltage, but your controller, in most cases, needs a positive feedback voltage. So you need an additional small, but cheap operational amplifier to turn the negative feedback voltage into a positive one.
Now, we change the topology a bit from the SEPIC converter to the Cuk Converter, so an inverting SEPIC. Again, it's pretty close to a two-stage approach here. If the switch is open, steady state, you notice that across the winding of L1, C1 is charged left-handed by the input voltage, but right-handed by L2, also on the negative output voltage. So the major difference here is that the coupling capacitor C1 sees input voltage plus output voltage. That's your voltage stress at C1.
At SEPIC, if you regard it the same, you will see that at C1 is only present the input voltage. And what we learned before is when Q1, the switch is closed, we got the magnetizing currents, the sum of the magnetizing currents of L1 and L2 across the switch. And if we opened a switch, we got the sum of the demagnetizing currents across the rectifier. Here we are.
If we close the switch, the input voltage is present across L1, and output plus input voltage is present across L2. And if we open now the switch, the demagnetizing current is driven by L1 across C1, across the rectifier, back to the input capacitor. Same for the output, we got the demagnetizing current driven by L2 across the rectifier D1 to the output.
The interesting thing here is if we look on the right side, the inductor current L1 and the inductor current L2 is continuous, so neither a pulse current at the input nor the output. This typology is well-suited for sensitive applications. [音乐播放] Cuk 转换器本身 以 Slobodan Cuk 的姓名命名。 它是一个反向 SEPIC。 它也是一种反激式拓扑。 这意味着开关开路后， 会将能量传输到耦合 电容器。 此处的优势是 LC 滤波器位于输入端。 而且另一个 LC 滤波器 位于输出端。 这意味着 输入和输出端 具有连续电流， 因此转换器两侧的 纹波非常低。 另一方面，我们的 功率级中有两个双极， 会在一定程度上降低动态性能。 您的 [听不清] 放大器中需要 高增益才能获得 合理的动态性能。 而且所有这些 拓扑都是如此， 如果耦合了电感器， 则绕组比必须 为 1 比 1。 升压控制器 也带有单个驱动器， 成本低廉， 适合您的设计。 另外，与非隔离式 反相反激相比， 您也可以仅使用一个开关和 一个整流器实现这一目的。 同样，干净波形、 无振铃意味着低 EMI、 低辐射发射。 可以使用多个绕组， 因为输出绕组完美地 耦合在内核上。 另外，还有 一个小缺点。 您会得到负的 输出电压， 但您的控制器 在大多数情况下 需要正的 反馈电压。 因此，您另外需要 一个小巧、便宜但可运行的 放大器，将负的 反馈电压变成正的 反馈电压。 现在，我们 稍微更改一下拓扑， 从 SEPIC 转换器 更改为 Cuk 转换器， 也就是反向 SEPIC。 同样，它非常接近于 此处的双级方法。 如果开关处于 开路稳态， 您会注意到 在 L1 的绕组两侧， C1 在左侧由 输入电压充电， 但在右侧由 L2 充电， 也是负的输出电压。 因此，此处的主要区别是， 耦合电容器 C1 看到的 是输入电压加上 输出电压。 这是 C1 上的 电压应力。 在 SEPIC 上，如果您 关注同样的事情， 您会看到，C1 上 仅存在输入电压。 我们以前学过， 当开关 Q1 闭合时， 我们可获得 磁化电流， 即 L1 和 L2 跨该开关的 磁化电流之和。 如果我们断开某个开关， 我们会在整流器 两侧得到磁化 电流的总和。 就是这样。 如果我们闭合该开关， 则跨 L1 存在 输入电压， 跨 L2 存在输出 电压加上输入电压。 现在，如果我们断开该开关， 则 L1 会驱动 消磁电流通过 C1、 整流器，然后 返回到输入电容器。 输出也是如此， L2 将驱动消磁电流 通过整流器 D1 到达输出端。 此处的有趣 之处在于， 如果我们查看右侧， 电感器电流 L1 和电感器电流 L2 是连续的， 因此，输入或输出处 均不是脉冲电流。 此拓扑非常适 用于敏感型应用。 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.
