According to the company, it has demonstrated a universal input single-switch 150W fly-back power supply design that delivers 97.5% average (99.5% peak, graph below) front-end efficiency while maintaining 90% at 2W. A 240W interleaved fly-back is currently being developed, as are higher power examples.
Pulsiv is currently sampling a pair of microcontrollers (PSV-AD-150 and PSV-AD-250), branded Osmium, to operate front-ends up to 150W or 250W. Another, PSV-AD-10K, is planned for outputs between 250W and over 10kW – the overall converter technology is also branded Osmium.
The MCUs “do not directly determine output power and can be used as a platform for any application requiring 1W to 10kW, by adjusting only three system components and connecting a suitable dc-dc converter”, said Pulsiv. “Osmium technology supports active bridge control, configurable hold-up, X-cap discharge, a power consumption indicator and grid failure detection. These optional features can be selected as required.”
The PSV-AD-250 variant supports the extra components needed for active bridge control and X-cap discharge.
Looking at the circuit (left), there is buck converter charging a reservoir capacitor from the rectified ac rail during parts of the mains half-cycle (path 1), which then delivers current back to the rail during other parts of the half-cycle (path 2).
“The buck is directing a shaped current during the parts of the mains cycle that produces the maximum power factor,” company founder Zaki Ahmed told Electronics Weekly.
The following dc-dc converter sets capacitor discharge current, and its behaviour plus the buck’s behaviour sets in-rush at switch on – Pulsiv claims in-rush can be eliminated.
The microcontroller in the diagram (yellow) sets maximum capacitor voltage (to 150V or 180V) via pin 4, and sensing through pins 5 and 6 allows grid voltage and frequency to be monitored.
Osmium with 150W fly-back dc-dc load
According to the company, the topology can meet Energy Star VI (right), and is easily modified to include output hold-up capacity.
PSV-AD-250-DS (left) is a development system the technology, to be used with a following dc-dc converter.
Pulsiv was spun-out of the University of Plymouth in 2013, and has offices in Plymouth and Cambridge.
