In a more electric aircraft, with strong demand for numerous independently controlled AC and DC power utilities, a new concept of secondary power distribution system has emerged. Based on common core software applications, local area network, and electronic modules with Solid State Power Controllers (SSPC), secondary power distribution system becomes a network of independent Power Distribution Units (PDU), installed in various locations throughout aircraft fuselage. This new decentralized concept has many benefits, including wiring weight reduction, electronic over-current and arc fault protection, and software controlled circuit breakers status and indication.
An attempt to optimize allocation of SSPCs to aircraft electric utilities and the number of electronic Power Modules in Power Distribution Units has become a more complex problem. Each Power Distribution Unit contains several Power Electronics modules, where each module has its own power dissipation limit. It is known that the power dissipation characteristics of an SSPC are a function of ambient temperature and nominal load current. Although, Power Distribution Units are located inside the aircraft pressurized vessel, ambient temperature can vary in a wide range, while nominal current loads typically depend on specific phase of flight and aircraft configuration. This article presents a power analysis numeric algorithm, which is used to determine total power dissipation for each AC or DC type electronic Power Module, and total power consumption for entire Power Distribution Unit in all aircraft configuration conditions, across the entire operating temperature range.
In aircraft secondary power distribution system with multiple Power Distribution Units, the power analysis method presented herein becomes a critical part of the iterative aircraft power optimization process to establish interface definition between SSPC channels and aircraft electrical loads.