Electronic Design

It’s A Military Coup For Medical Power Supplies

Amongst government contractors in Europe, it’s a well-recognised requirement that equipment and products they procure must be highly reliable. Okay, so there’s nothing new about that.

Interestingly, SL Power Electronics, a designer and manufacturer of power supplies, says these military and government requirements aren’t being met by the company’s expertise in those particular fields. Rather, it comes from experience in making power-supply products for the medical market. Consequently, the company has experienced an increase in business because of its expertise in rugged, high-reliability medical equipment.

Nigel Davies, European managing director for SL Power says, “Like all markets in the world currently, the medical market isn’t immune from the world’s economic troubles. The purchaser of medical equipment is undoubtedly coming under increasing financial governmental constraints, but certain types of products, such as ventilator manufacturers, are seeing an increase in interest.

“At SL Power we have seen over the past 6 months, initially in USA and now in Europe, destocking by both direct customers and distribution networks. This appears now to have leveled off and the market is flat. Fortunately, SL Power took hard decisions early in the downturn, which have resulted in the company maintaining a healthy financial outlook despite reduced sales.

“We are, however, seeing a great deal of interest in our new generations of medical products, which have been introduced within the past six months. Manufacturers appear to be using the downturn to develop new equipment, demanding ever-lower prices, higher efficiencies and smaller sizes, and increasingly higher convection-cooled ratings.

“Major global manufacturers are looking for one-size-fits-all solutions to their equipment, so that they can minimise the variety of parts held. Ever-more complex power systems are being requested, with as many as 24 outputs, battery charging, and computer-controlled operating and monitoring.

“During this period, though, medical legislation for power supplies has not really changed. There are new power-supply energy consumption changes impacting on external commercial power supplies, such as the USA EISA laws, but all medical equipment is currently exempt from these requirements. SL Power is, however, implementing the improved efficiencies required as part of a general green initiative.”

According to Davies, there are varied, but complex, types of products currently being supplied. On the one hand, the company is supplying a power system for a shipborne communications system. The system uses multiple 5000W distributed- power systems, which include over a hundred 300W dc-dc converters. In contrast, a major U.S.- based military equipment manufacturer employs three different systems in a mobile land-based vehicle. The high-power system is supplied with either ac input, dc input, or dual ac-dc input.

Recently, the company won contracts to develop high-density platforms for secure broadband and radio data transmission in support of military and Homeland Security applications. SL Power expects greater demand for this service as countries try to re-equip with increasingly complex military hardware.

The company recently announced an addition to its Condor MINT Series of universal input power supplies designed for medical systems applications (Fig. 1). The single output MINT1110 series units feature a compact, open-frame design measuring 3 x 5 x 1.27in. and offer a typical full-load efficiency of up to 87%.

The supplies come in four outputs ranging from 12 to 24V. Their targeted at numerous medical applications, from diagnostic and respiratory care equipment to continuous positive airway pressure (CPAP) devices and monitors of all types.

The MINT1110 units feature a universal 100 to 240Vac input that provides flexibility for use anywhere in the world. They’re protected against overvoltage, overcurrent and short circuit, with optional overtemperature protection available.

The units carry a set of medical and safety approvals, including EN/IEC/UL 60601-1 and CSA 22.2 No. 601.1-M90. The family is also RoHS-compliant.

BASEPLATE-COOLED AC-DC POWER SUPPLY
Another U.K.-based company, Powersolve Electronics, introduced the PSL400BP Series of baseplatecooled ac-dc units. The new power supplies are designed to offer single outputs of 5, 12, 24, or 48Vdc with output power up to 400W. The input range is 85 to 264Vac, 47 to 63Hz, and all models feature active power factor correction (PFC) to conform with EN61000-3-2.

These ruggedised power supplies, housed in an extruded aluminium chassis, are designed for use in industrial or other types of equipment where cooling fans are undesirable and convection airflow isn’t available. Units can be mounted in a sealed box, provided that the external heat sinking is adequate to maintain the baseplate at a temperature of 80ºC or below.

Standard features include overcurrent and short-circuit protection, overvoltage and overtemperature protection, output voltage adjust, remote on/off, output power-good signal, +5V/1A standby output, and LED indicator to show VOUT present. In addition, all units can operate in parallel for N+1 redundant operation, and they feature integral ORing diodes.

The PCB is conformally coated for protection against the ingress of moisture and dirt. Operating temperature range is −20 to +70ºC, if the baseplate temperature can be maintained at 80ºC or below.

All power supplies will carry full UL, cUL, and TUV EN60950 safety approvals. Moreover, they will conform to the EN55022-conducted EMC requirements.

PUSHING THE POWER BOUNDARIES
Commercial and MIL power solutions supplier Gresham Power Electronics believes it’s pushing the boundaries of power density in power-supply design. Its latest open-frame, switch-mode powersupply family, the HD365, offers 365W in a 76 × 127mm (3 × 5 in.) footprint and provides 18W/ in.3 power density (Fig. 2). Just a few years ago, this package size could only be expected to offer 100W, claims the company.

For cPCI system builders, Gresham Power’s latest rack-mount product, the CPCI-6U-600, now can provide 600W in a standard 6U with universal ac input or a 48Vdc input.

Jake Moir, managing director of Gresham Power Electronics, says “The whole market is under pressure to reduce cost. We have implemented an advanced research programme to increase the value for money offering of our most successful products rather than lower our quality standards by reducing the cost or quality of the components we use.

“Rather than manufacturing ‘for a price,’ we are increasing the power density of our products so that the cost-per-watt figure comes down in real terms. This also enables our customers to save valuable cabinet or rack space, which they can use to increase the value of their own products with added functionality. We see this as a real win-win situation with no reduction in quality or sacrifice of reliability, while allowing our customers to add value to, and increase the market life of, their products.”

The HD365 Series is claimed to deliver the industry’s smallest 365W switcher. The series is designed for medical, telecom, and industrial applications. To satisfy 1U height considerations, the package measures only 3.00 x 5.00 x 1.30in. All of the models offer universal ac input with active PFC, flexible output configurations, and compliance to worldwide safety and EMC standards.

Standard features include universal ac input with PFC, low-profile 1U package, convection-cooled operation up to 220W, 12V/1A auxiliary output to power fan, RoHS compliance, and high-efficiency operation of 90% (typical). Standard output voltages are 12, 24, and 48Vdc.

HOT-SWAPPABLE 48 Vdc MODULAR RECTIFIERS
The UNIPOWER Corp. has entered the fray with a generation of high-density, hot-swappable 48Vdc modular rectifiers and frontends. Called BLUEstreak, plans call for the front–end version to be factory set at 48Vdc, while the Rectifier version will be set at 54.4Vdc (Fig. 3).

BLUEstreak units can provide up to 2000W from a 1U-high package at power densities as high as 23.4W/in³. Input voltage range is between 85 to 264Vac. Efficiency levels are 92% at 75% load. Four units with a total output of up to 8000W can be housed in a flexible 1U system rack.

The modules feature automatic load sharing as well as an active ORing circuit using FETs. They have an operating temperature range of –20 to +70ºC managed by variable-speed cooling fans. LEDs indicate ac and dc power good. Two standby outputs are available, +5V at 1.8A and +12V at 0.8A.

Like other UNIPOWER rectifiers, BLUEstreak modules use the I²Cbased PMBus to pass status and control data between a host system, management unit, and the module.

Availability of the rectifiers and front-ends, which will find wide application in network equipment and data storage as well as in telecom battery systems, is expected at end of the second quarter. The Series will include additional output voltages and various power levels in the near future.

The designs meet all relevant safety standards including UL60950-1, CSA22.2 No. 60950-1, and EN60950-1, and are RoHS-compliant.

TAGS: Medical
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