Constant current controlled flyback converter is widely used in low power applications for its simple structure and low cost. In order to further improve the output power and the efficiency, active-clamp flyback converter with soft-switching technique is always used. To avoid the nonlinearity and temperature drift of opto-coupler in the feedback circuit, a constant current digital control method is proposed for a primary-side regulation active-clamp (PSRAC) flyback converter in this article. Soft-switching technique is realized in discontinuous conduction modulation mode with a modified active-clamp technique. To compensate the nonlinearity of the secondary diode current with primary-side regulation, a new output current estimation algorithm is put forward based on the charge balance principle. The output current is predicted from primary current and the auxiliary winding voltage, and constant output current control is realized with primary peak current control method. The cost is low as only one low speed digital-to-analog converter, three comparators and a digital controller are required. The proposed control scheme was verified by a field-programmable gate array controlled 5.4–10.8 V/1.80 A PSRAC flyback converter. The output current accuracy is within in 1.2% in different input and output condition and the peak efficiency is improved by 3.6% after active-clamp technique is used.

中文翻译：

---

一次侧调节有源钳位反激转换器的恒流数字控制方法

恒流控制反激转换器以其简单的结构和低成本而广泛用于低功率应用。为了进一步提高输出功率和效率，始终使用具有软开关技术的有源钳位反激式转换器。为了避免反馈电路中光耦合器的非线性和温度漂移，本文针对原边调节有源钳位（PSRAC）反激转换器提出了一种恒定电流数字控制方法。通过改进的有源钳位技术在不连续传导调制模式下实现软开关技术。为了利用一次侧调节来补偿二次侧二极管电流的非线性，基于电荷平衡原理提出了一种新的输出电流估计算法。根据初级电流和辅助绕组电压预测输出电流，并通过初级峰值电流控制方法实现恒定的输出电流控制。成本低，因为仅需要一个低速数模转换器，三个比较器和一个数字控制器。现场可编程门阵列控制的5.4-10.8 V / 1.80 A PSRAC反激式转换器验证了所提出的控制方案。使用有源钳位技术后，在不同输入和输出条件下，输出电流精度在1.2％以内，并且峰值效率提高了3.6％。现场可编程门阵列控制的5.4-10.8 V / 1.80 A PSRAC反激式转换器验证了所提出的控制方案。使用有源钳位技术后，在不同输入和输出条件下，输出电流精度在1.2％以内，并且峰值效率提高了3.6％。现场可编程门阵列控制的5.4-10.8 V / 1.80 A PSRAC反激式转换器验证了所提出的控制方案。使用有源钳位技术后，在不同输入和输出条件下，输出电流精度在1.2％以内，并且峰值效率提高了3.6％。