THERE ARE TWO REASONS WHY YOU WOULD NEED TO OPERATE POWER SUPPLIES OR DC-DC CONVERTERS IN PARALLEL.
ONE IS TO PROVIDE MORE CURRENT THAN AVAILABLE FROM A SINGLE UNIT AND THE SECOND IS TO PROVIDE REDUNDANT POWER SHOULD ONE UNIT FAIL.
FIRST LET’S TALK ABOUT PROVIDING MORE CURRENT. FOR EXAMPLE, YOUR SYSTEM REQUIRES 2000 WATTS OF POWER. NORMALLY YOU WOULD USE ONE 2000 WATT UNIT HOWEVER, YOUR CURRENT SUPPLIER MAY NOT HAVE A SINGLE 2000W UNIT AVAILABLE, A SOLUTION WOULD BE TO USE TWO 1000W UNITS IN PARALLEL.
MANY PEOPLE HOWEVER MAKE THE MISTAKE OF THINKING THAT ALL UNITS CAN BE EASILY PARALLELED. THAT IS NOT THE CASE. ASK YOUR SUPPLIER IF THEIR POWER SUPPLY HAS POWER SHARING CAPABILITY. ALL STANDARD PRODUCTS OFFERED BY TECHNOLOGY DYNAMICS INC. POSES THIS FEATURE. ACTIVE POWER SHARING MEANS THAT THE POWER SUPPLY HAS A TERMINAL THAT ALLOWS IT TO BE CONNECTED TO A SECOND OR THIRD UNIT. (SEE FIG 1.) CONNECTING THE POWER SHARE TERMINALS BETWEEN THE TWO UNITS ALLOWS THE POWER SUPPLIES TO COMMUNICATE WITH EACH OTHER AND ADJUST THEIR OUTPUT VOLTAGES SO THAT THE LOAD IS SHARED EVENLY, TYPICALLY WITHIN 10%.
THE SECOND REASON TO CONNECT UNITS IN PARALLEL IS TO PROVIDE BACK-UP SHOULD ONE UNIT FAIL. THIS IS ALSO CALLED N+1 REDUNDANCY. N IS THE NUMBER OF UNITS YOU NEED TO POWER THE LOAD, PLUS 1 AS THE BACK-UP. IF FOR EXAMPLE YOU NEED TO POWER A LOAD OF 2000W WITH REDUNDANCY, YOU COULD USE 3 X 1000 WATT UNITS.
2 UNITS WOULD BE CAPABLE OF SUPPLYING THE ENTIRE LOAD WHERE THE THIRD UNIT IS THE REDUNDANT UNIT. IN THIS CONFIGURATION ALL UNITS ARE ACTIVE, SHOULD ONE UNIT FAIL, THE REMAINING TWO UNITS ARE CAPABLE OF SUPPLYING THE ENTIRE LOAD. IN ADDITION TECHNOLOGY DYNAMICS INC. PROVIDES IN ALL THEIR PARALLEL OR REDUNDANT SYSTEMS AN OUTPUT ISOLATION DIODE FOR ADDED SYSTEM PROTECTION AGAINST A CATASTROPHIC FAILURE. (SEE FIG 2.)
IN A PARALLEL OR N+1 REDUNDANCY APPLICATION SOME GENERAL RULES SHOULD BE FOLLOWED.
- THE OUTPUT VOLTAGE OF EACH UNIT SHOULD BE SET AS EQUAL AS POSSIBLE.
- ENSURE THAT THE OUTPUT LEAD LENGTHS ARE AS SHORT AND EQUAL AS POSSIBLE.
- MAKE SURE YOU HAVE CONNECTED THE CURRENT SHARE FEATURE FROM UNIT TO UNIT
- ALL THE UNITS INPUTS AND OUTPUTS ARE PROPERLY BUSSED TOGETHER AND TIGHT
AND AS ALWAYS, COMMUNICATE WITH YOUR POWER SUPPLY COMPANY. THEY ARE IN THE BEST POSITION TO ASSIST YOU WITH THE MOST SUITABLE SOLUTION FOR YOUR NEXT N+1 REDUNDANCY OR PARALLEL APPLICATION.
