10/10/2023In this, the first article of the series, I present a new custom product – centralized power supply JETAB3600 for construction of uninterruptible centralized bus (see Fig. 1) as a basis of matrix power supply systems.
Fig. 1 – JETAB3600 centralized AC/DC converter for building a 27 V uninterruptible distributed power bus
It was created as a universal unit to work on impulse load with 27V buffer battery with output power of 0-6000W from three-phase 3/220V or 3/380V, 47-440Hz networks or from analogous single-phase networks. Parallel operation with similar units of more than 24 000W is possible.
Unique parameters of this unit are:
Fig. 2 – Block diagram of the JETAB3600 centralized power supply unit
The block structural diagram is shown in Figure 2. The base of AEPS-group’s unit consists of 3 parallel connected AC/DC modules M1, M2 and M3. This unit can be equipped with JETNA1000-LP or JETNA2000-LP modules, but if the unit size increases, more powerful JETNA3000-LP or brand new JETNA5000-LP modules can be added. This increases the maximum power per unit to 15 000 W, and to 60 000 W for four units.
The outputs of the M1-M3 modules are connected in parallel according to a common scheme – through Schottky diodes to eliminate the influence of failures in the output part of one of the modules on the remaining modules.
Thermal modeling of the design was aimed at developing a small-sized high-efficiency radiator, which provides minimal overheating of the module cases, and a system of fans, which form laminar air flows with uniform distribution within individual air channels.
The system contains all necessary deflectors, overhead chambers and airflow short-circuit blockers for optimization.
Achieved overheating of M1-M3 modules bodies in relation to the ambient air temperature was not more than 20°C, which ensures that the temperature of the modules bodies is not higher than 80°C. A distributed-type thermal protection system is used, which activates at case temperatures of 82-87°C.
Speaking of these remarkable and internationally popular low-profile (planar) AC/DC modules, it should be noted that they are installed in this unit according to specific customer requirements. These requirements include remote functionality; temperature dependence of output voltage for specific batteries; compliance to MIL-STD-810-F (mechanical), MIL-STD-461F.2007 (EMC) standards; voltage and current monitors; distributed temperature protection and much more.
AC/DC modules have self-contained EMC input and output filters and fire protection input fuses that cut off the input-side emergency module from the others when it fails.
The modules are non-repairable, have a special thermally conductive rigid polymer casting and encapsulated components for operation in dusty, humid environments and, of course, in conditions of sufficiently large mechanical impacts.
Fig. 3 – The most popular AC/DC module on the market JETNA3000 for building centralized converters of matrix power supply systems
Figure 3 shows one of the planar AC/DC modules from the AEPS-group. These works of art, created by the engineers of the Alexander Electric Group, can do a lot of things. But perhaps the most unique thing apart from their planarity (the profile of the whole series is unprecedentedly small – only 38 mm; you can sink the modules into the body of the radiator for another 6 mm) is the separation of heat flows coming down to the base of the module and in the opposite direction – up. In this case, optimizing the separation of heat fluxes on the sides of the structure resulted in a result of 87% by 13%. So there is a kind of thermal management (do not remember the foreign name of this process – I do not like it either).
