并聯(lián)DC/DC模塊產(chǎn)生更高的輸出功率

　　在中間總線體系結(jié)構(gòu)（IBA）應(yīng)用中，通常單個DC / DC總線轉(zhuǎn)換器沒有足夠的電源來供電橫跨系統(tǒng)板的所有電子負載。在這種情況下，設(shè)計者必須從頭開始構(gòu)建高功率、高效率的轉(zhuǎn)換器或類似的高效率電源模塊，以將系統(tǒng)輸出功率提高到所需的水平。

　　設(shè)計一種具有高效率和高性能的千瓦級或更高功率的DC/DC變換器，既不簡單，又費時費力，而且由于較大的無源元件增加了高度的可能。并聯(lián)相同的DC / DC模塊的更高的輸出功率可以加快任務(wù)，同時保持所需的性能和配置文件。然而，為了滿足這些要求，每個轉(zhuǎn)換器都必須共享負載電流，以盡量減少每個動態(tài)響應(yīng)或恢復(fù)。

　　使用兩個或兩個以上的低功率模塊，以產(chǎn)生更高的輸出功率也有助于分布在較大的印刷電路板（PCB）面積的熱負荷，從而避免了任何熱點板上。然而，并非所有模塊都是為并行操作設(shè)計的，因此在將它們并行連接之前，設(shè)計者必須確保模塊提供負載共享功能。

　　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.