并联DCDC模块产生更高的输出功率

　　并联DC/DC模块产生更高的输出功率

　　在中间总线体系结构（IBA）应用中，通常单个DC / DC总线转换器没有足够的电源来供电横跨系统板的所有电子负载。在这种情况下，设计者必须从头开始构建高功率、高效率的转换器或类似的高效率电源模块，以将系统输出功率提高到所需的水平。

　　设计一种具有高效率和高性能的千瓦级或更高功率的DC/DC变换器，既不简单，又费时费力，而且由于较大的无源元件增加了高度的可能。并联相同的DC / DC模块的更高的输出功率可以加快任务，同时保持所需的性能和配置文件。然而，为了满足这些要求，每个转换器都必须共享负载电流，以尽量减少每个动态响应或恢复。

　　使用两个或两个以上的低功率模块，以产生更高的输出功率也有助于分布在较大的印刷电路板（PCB）面积的热负荷，从而避免了任何热点板上。然而，并非所有模块都是为并行操作设计的，因此在将它们并行连接之前，设计者必须确保模块提供负载共享功能。

　　Paralleling DC/DC modules

　　In essence， modules that are designed to permit paralleling typically use active current sharing or a passive droop compensation technique. In active current sharing， which is usually found on higher-power modules， a separate signal line connects the paralleled modules and actively controls internal switching operation as a function of the sensed current level in each module. Allowing the power converters to communicate improves the accuracy of load sharing as well as maximizes the power output of the paralleled converter array.

　　By allowing the power output voltage to sag as a function of load current， droop compensation ensures balanced current sharing among the modules connected in parallel. Several power supply makers include this feature in DC/DC converters. Texas Instruments is one of them. According to TI’s Bob Sheehan， member of the technical staff， SVA application design services， current-mode controllers can be used for droop compensation and load sharing in parallel operation. However， Sheehan recommends using the circuit in Figure 1， which is a general method for droop compensation and load sharing when using a current-mode controller such as TI’s LM25117 or other similar controllers.