3.6 PSFB-CDR Transformer Design

The main power transformer for this application was custom designed together with Payton. Two variants with different leakage inductances were manufactured. Primary side winding uses Litz wire, while the secondary side has bus bars for high secondary side currents and low leakage inductance.

Figure 3-8. Microchip-Payton 800V-12V, 2700W Power Transformer (PSFB Application)

Table 3-3 contains basic electrical parameters for the main transformer.

Table 3-3. Electrical Specifications for Payton 2700W PSFB Transformer
Properties	Value
Manufacturer	Payton
Payton part number	63208 (7 uH) 63209 (4 uH)
Output power maximum	2700W (15V/180A) for 10s with 20s breaks
Output power continuous	1200W (12V/100A) continuous operation
Operating frequency	100 kHz
Rectified Ripple current frequency	100 kHz
Input voltage of the power stage	400-950V DC Link
Topology	Phase shifted full bridge, ZVS, current doubler
Primary to secondary side turns ratio	17:1
Primary current, max	8.5 Apeak
Primary inductance	1000 uH +/-5%
Primary to secondary leakage 63208 63209	- 7 uH, estimated 4 uH
Dielectric strength Primary to Secondary + Core Secondary to Core	- 4 kVrms 500 VDC
Temperature range	-40 to +65°C
Estimated total loss	~22W for 2700W ~8W for 1200W
Mechanical dimension	88L x 66W x 25H mm