Creating an off-line power supply with a high voltage BCM and a PFC FrontEnd

The high voltage (HV) BCM (B384F120T30) is one of the latest members of our V•I Chip component families of product. With an input voltage range of 360 to 400Vdc the HV BCM is ideal for use in an off line power supply with a PFC frontend.

The following steps show how easy this is to achieve.

The HV BCM

The V•I Chip Bus Converter Module is a high efficiency (>95%), narrow input range Sine Amplitude Converter (SAC) operating from a 360 to 400 Vdc primary bus to deliver an isolated extra low voltage secondary (ELV). The HV BCM provides an isolated 11.3 – 12.5 V distribution bus and is ideal for use in silver boxes and PFC front ends. Due to the fast response time, low noise and low output impedance of the BCM, the need for limited life aluminum electrolytic or tantalum capacitors at the input of POL converters is reduced – or eliminated – resulting in savings of board area, materials and total system cost.

The basic operation of the HV BCM is shown in Figure 1, and how it can be used to simplify the complete power system – from the wall plug to the load – is shown in Figure 2.

Figure 1 shows a diagram of the HV BCM with its stacked half bridge primary side. The BCM is in fully synchronous operation, at a switching frequency of >1MHz.

The B384F120T30 BCM acts as an isolated DC-DC transformer with step down ratio of 32:1. The significance is over 1000 times reduction of source impedance over a wide bandwidth seen by its downstream stage.

The BCM delivers 300W at 12V and multiple BCMs are capable of being put in parallel for much higher power and current, or being put in series for higher power and voltage.

The high voltage BCM provides a high degree of flexibility to the designer, and if required can also be easily arranged in parallel or serial output voltage arrays, as shown in Figures 3 and 4.

An easy way to start using the BCM

The HV BCM Series Array Evaluation Board has been designed to demonstrate the B384F120T30 Bus Converter's flexibility and superior performance in the areas of power density, efficiency (over a wide load range), fast response, and quiet, low noise operation. This Evaluation Board (B384F120T30-Sb) is a two-piece system for powering, testing and evaluating the HV BCM. The vertically mounted system-in-package (SIP) card contains four BCMs (two on each side) and is mounted to the base board via a multi-pin connector. The base board provides input and output connections, oscilloscope probe jacks, Kelvin connections, input fusing, system enable / disable and output power indicators. The B384F120T30-Sb operates from a 380Vdc input and delivers 48Vdc at 25A and / or up to 25A at 12Vdc with a maximum total power of 1200W.

Because of the high output power required, there are very few products on the market that will provide the designer with a suitable front end element of the system. However, our PFC FrontEnd (FE375) is an excellent solution as the input stage to create the 375Vdc bus voltage for the HV BCM power array.

The PFC FrontEnd

The PFC FrontEnd is an extremely low profile, 375V, 1 RU enclosed chassis mount AC front end that may be used with any Vicor 300V VI-200/VI-J00 or 375V Maxi, Mini, Micro modules, ViPAC Arrays or HV BCM to create a complete, high density AC-DC power supply. It is capable of providing up to 4 non-isolated outputs (additional using "Y" adapters). Accepting universal input voltages of 85 Vac to 264 Vac, and 100 to 380 Vdc, the PFC FrontEnd can create up to 2.2kW at a regulated 375V with auxiliary 14V outputs in a package size of 1.72" H (43,6mm) x 6.4" W (162,6mm) x 7" L(177,8mm).

The PFC FrontEnd consists of an off-line single phase, power-factor-corrected front end, EMI filter, cooling fan, customer interface and associated housekeeping circuits. Compact and rugged, the PFC FrontEnd (FE375) is a ready-made front end solution that meets Mil Std 810E for vibration. It also complies with harmonic current limits per EN61000-3-2, Electrical fast Transient/burst as per EN61000-4-4 and surge immunity as per EN61000-4-5, and also has worldwide safety agency approvals from CE and cTÜVus.

Other Solutions

Looking for a complete PFC power supply? Here's the list of choices

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