Parallel AC/DC Power Supplies

Paralleling AC/DC power supplies is a proven method for increasing output capacity and improving system reliability, but successful implementation requires more than simply connecting multiple power supplies together. The two primary reasons for operating power supplies in parallel are increasing available output power and providing redundancy through N+1 or N+2 system configurations. Redundant power architectures help ensure continuous system operation if a power supply fails, while parallel current sharing allows multiple units to evenly distribute load current for higher power applications.

There are several situations where using multiple power supplies is preferable to selecting a single higher-power unit. Engineers may encounter mechanical space constraints that require slimmer power supplies, need lower output voltages that are unavailable in higher-power models, require compatibility with lower AC input voltages, or simply wish to expand an existing design using proven hardware. Parallel configurations can also improve thermal management by distributing heat generation across multiple locations within an enclosure.

Not all power supplies are designed for parallel operation. Modern current-sharing power supplies typically incorporate active current sharing through dedicated communication signals, providing excellent load balancing between units. Other designs utilize droop current sharing, while standard power supplies without built-in sharing circuitry often rely on brute-force parallel connections that can result in uneven current distribution and overload conditions. Proper implementation includes matching output voltages before connection, maintaining equal cable lengths to minimize voltage drop differences, incorporating ORing diodes or ORing MOSFETs for redundant systems, and derating total available output power to maintain long-term reliability. Cotek's parallel-capable AC/DC power supplies incorporate advanced current sharing technology to simplify high-power and redundant system design while delivering dependable performance in industrial automation, telecommunications, transportation, battery charging, and mission-critical applications.