So finally, we end up at the highest power levels. We are now dealing with our full bridge converter. Full bridge converter could be either hard switched or could be phase shifted. We're talking about both.
The power range is 400 watts, typically, to multiple kilowatts here, and I think it's one of the well-known topology we have for those higher power ranges.
Unfortunately, we need four FETs here. So we have some silicon cost. Similar to the half bridge, the voltage stress at the FETs is only input voltage. But now we have the full bridge full input voltage across the transformer windings, so we get bigger output power here.
Now we have two high side FETs. Compared to the half bridge, we need two floating drivers. We have to use two half bridge drivers here.
And our controller itself needs four outputs to control these driver stages. So we have here also bigger silicon costs. It itself, the full bridge, offers the best core utilization and offers the best utilization of winding space.
The transformer core itself for the full bridge needs to be balanced. This could be achieved either by peak current mode or if we put a small capacitor in series to the transformer winding, we could also use voltage mode. Similar to half bridge and push/pull, the output filter sees twice the switching frequency.
The body diodes are clamping to input voltage. So we have low EMI, no ringing, and we have high efficiency here for the full bridge converter.
Have a look at the full bridge power stage. We are now switching the diagonal [? LEX. ?] We are switching Q3 and Q1. So input voltage is present across the primary winding.
Under secondary side, we've got the primary. So we've got the input voltage multiplied by the windings ratio across secondary one and secondary two. Secondary two is reversed bias, so D2 is non-conducting, but D1 is conducting.
We've got the secondary voltage minus the output voltage present across inductor L1. We are magnetizing L1 and we are delivering energy to the load and the output capacitor.
Now, if we open the switch, similar to the push/pull, similar to the half bridge, the energy is stored at the air gap of L1 is driving the freewheeling current across our diode D1 and our diode D2.
And the next cycle starts switching the opposite diagonal Q2 by Q4 in the other voltage direction across the transformer. 最后，我们将以 最高功率级别收场。 我们现在将介绍 全桥转换器。 全桥转换器可以 是硬开关式， 也可以是移相式。 我们将讨论这两者。 一般来说， 功率范围 为 400 瓦 到几千瓦， 而且我相信，它是 适用于这些较高功率范围的 众所周知的拓扑。 遗憾的是，我们 此处需要四个 FET。 因此我们有一些芯片成本。 与半桥相似， FET 上的电压应力 仅为输入电压。 但现在，变压器 绕组上有全桥 全输入电压， 因此，我们 此处可得到 更大的输出功率。 现在，我们有两个高侧 FET。 与半桥相比， 我们需要两个浮动驱动器。 我们此处必须使用 两个半桥驱动器。 并且我们的控制器 本身需要四个输出 来控制这些驱动级。 因此我们此处还有 更大的芯片成本。 它本身，即全桥， 提供最佳内核 利用率，并可以最好地 利用绕组空间。 对于全桥， 变压器内核本身 需要进行平衡。 这可以通过 峰值电流模式来实现， 如果我们以 与变压器绕组 串联的方式放置一个小电容器， 则也可以使用电压模式。 与半桥和 推挽式相似， 输出滤波器具有 两倍的开关频率。 体二极管连接 到输入电压。 因此我们具有低的 EMI、无振铃， 并且我们在此处 具有适合全桥 转换器的高频率。 请看一下全桥 功率级。 我们现在开关 对角 [? LEX. ?] 我们开关 Q3 和 Q1。 因此，存在跨初级 绕组的输入电压。 在次级侧下面， 我们有初级。 因此，我们可以 将输入电压 乘以次级 1 和 次级 2 的 绕组比。 次级 2 是反向偏置的， 因此，D2 不导通， 但 D1 导通。 我们将次级电压 减去跨电感器 L1 存在的 输出电压。 我们磁化 L1 并 向负载和 输出电容器 输送能量。 现在，如果我们断开此开关， 与推挽式和半桥相似， 存储在 L1 的 气隙中的能量 会驱动续流电流 通过二极管 D1 和二极管 D2。 下一个周期 开始时， 跨变压器在另一个 电压方向上开关处于相对 对角线上的 Q2 和 Q4。 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.
