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1. 发明申请

US20090059632A1 System And Method For Controlling A Current Limit With Primary Side Sensing Using A Hybrid PWM and PFM Control 有权
标题翻译：使用混合PWM和PFM控制的初级侧检测来控制电流限制的系统和方法
公开(公告)号：US20090059632A1
公开(公告)日：2009-03-05
申请号：US12199471
申请日：2008-08-27
申请人： Yong Li , Junjie Zheng , Liang Yan , John Kesterson , Xiao Yan Wang
发明人： Yong Li , Junjie Zheng , Liang Yan , John Kesterson , Xiao Yan Wang
IPC分类号： H02M7/155
CPC分类号： H02M3/33523
摘要： A hybrid constant current control system that uses both pulse width modulation (PWM) and pulse frequency modulation (PFM) control. When transitioning from constant voltage mode to constant current mode the present invention can continue to control using PWM. Thereafter, when the voltage has dropped, the present invention smoothly transitions to PFM mode. The point of transition is based upon the switching frequency and the lowest rated voltage of operation. The system and method avoids very short (narrow) Ton times which ensures accurate constant current (CC) control with bipolar junction transistor (BJT) devices. The present invention also avoids acoustic noise because the switching frequency is maintained at a high enough level to avoid such acoustic noise even when the energy transferred through the transformer is still substantial and the output voltage is not too low. In addition the output current limit is insensitive to variation in the inductance-input voltage ratio, and is minimized against leakage inductance.
摘要翻译：一种采用脉宽调制（PWM）和脉冲频率调制（PFM）控制的混合恒流控制系统。当从恒定电压模式转换到恒定电流模式时，本发明可以使用PWM继续控制。此后，当电压下降时，本发明平滑地转变为PFM模式。转换点基于开关频率和最低额定工作电压。该系统和方法避免了非常短（窄）的Ton次，从而确保使用双极结型晶体管（BJT）器件进行精确的恒定电流（CC）控制。本发明还避免了声学噪声，因为即使当通过变压器传送的能量仍然很大并且输出电压不是太低时，开关频率被保持在足够高的水平以避免这种声学噪声。此外，输出电流限制对电感 - 输入电压比的变化不敏感，并且对漏电感最小化。

2. 发明授权

US07974107B2 System and method for controlling a current limit with primary side sensing using a hybrid PWM and PFM control 有权
标题翻译：使用混合PWM和PFM控制来控制初级侧感测的电流限制的系统和方法
公开(公告)号：US07974107B2
公开(公告)日：2011-07-05
申请号：US12199471
申请日：2008-08-27
申请人： Yong Li , Junjie Zheng , Liang Yan , John Kesterson , Xiao Yan Wang
发明人： Yong Li , Junjie Zheng , Liang Yan , John Kesterson , Xiao Yan Wang
IPC分类号： H02M3/335
CPC分类号： H02M3/33523
摘要： A hybrid constant current control system that uses both pulse width modulation (PWM) and pulse frequency modulation (PFM) control. When transitioning from constant voltage mode to constant current mode the present invention can continue to control using PWM. Thereafter, when the voltage has dropped, the present invention smoothly transitions to PFM mode. The point of transition is based upon the switching frequency and the lowest rated voltage of operation. The system and method avoids very short (narrow) Ton times which ensures accurate constant current (CC) control with bipolar junction transistor (BJT) devices. The present invention also avoids acoustic noise because the switching frequency is maintained at a high enough level to avoid such acoustic noise even when the energy transferred through the transformer is still substantial and the output voltage is not too low. In addition the output current limit is insensitive to variation in the inductance-input voltage ratio, and is minimized against leakage inductance.
摘要翻译：一种采用脉宽调制（PWM）和脉冲频率调制（PFM）控制的混合恒流控制系统。当从恒定电压模式转换到恒定电流模式时，本发明可以使用PWM继续控制。此后，当电压下降时，本发明平滑地转变为PFM模式。转换点基于开关频率和最低额定工作电压。该系统和方法避免了非常短（窄）的Ton次，从而确保使用双极结型晶体管（BJT）器件进行精确的恒定电流（CC）控制。本发明还避免了声学噪声，因为即使当通过变压器传送的能量仍然很大并且输出电压不是太低时，开关频率被保持在足够高的水平以避免这种声学噪声。此外，输出电流限制对电感 - 输入电压比的变化不敏感，并且对漏电感最小化。

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