适合车载和轨道应用的DC/DC转换器

Over the last few years, RECOM has greatly extended its product portfolio of EN50155-certified components and now offers a huge range of AC/DC and DC/DC converters for railway. With the acquisition of the Italian power specialist Power Control Systems, RECOM is able to provide customized power solutions up to 18kW.

DC/DC converters are used in railway environments to convert DC battery voltages to a lower voltage for usage in a variety of control and energy circuits. This is because railway rolling stock uses a DC power distribution system so that batteries can be used to maintain electrical power in the event of a generator failure.

These converters need to be constructed according to EN 50155 to ensure harsh environmental conditions do not influence its mode of operation.

Main applications are:

• Railway rolling stock
• On-board and trackside application
• Industrial applications
• High voltage battery-powered applications
• Distributed power supply architectures

Heat, frost, vibration, mechanical impact – they all can cause serious damage to electronic assemblies. DC/DC converters used in railway technology are exposed to extremely tough conditions and must work properly and reliably for their entire service life.

Engineers are therefore looking for DC/DC converters that can withstand these exceptional conditions and are certified for railway applications.

The EN50155 (Railway Applications - Electronic equipment used on rolling stock) specifies carefully defined requirements for information systems and electronic components used in railway engineering. This also applies for DC/DC converters which have to function as reliable power supplies for many years under extreme conditions such as heat, cold, shock and vibration.

EN50155 is a performance standard for electronic equipment used in rolling stock (basically all rail vehicles that move; including locomotives, passenger wagons, light railways and freight trains). It lays down minimum requirements for the input voltage range, electrical isolation, operating temperature, shock and vibration, humidity and EMC, as well as equipment reliability and expected useful life.

Electronic equipment used on rolling stock is expected to have a very long operational life of up to 20 years, therefore the environmental testing should be thorough. Besides the normal operating temperature tests, additional thermal cycling, dry heat and damp heat testing is specified. Only a fully potted or sealed DC/DC converter can meet these requirements.

In the summer, temperatures can reach +60°C or more. In the winter, they frequently drop to -30°C or even lower. Where converters are operated in rolling stock, they are exposed to heavy vibration. All this pushes conventional DC/DC converters to the limits.

The new EN50155 standard defined six different operating temperature ranges and also include testing the operating temperatures and the extended temperature limits during start-up.

Components installed in railcars and locomotives are exposed to considerable vibration and other mechanical stress. During shunting, acceleration up to 5G is a common occurrence. An even greater problem is the constant vibration stress during travel, which can cause mechanical fatigue, resulting in module failure. To prevent such failures, EN 61373 has been drawn up, specifying minimum vibration and shock strengths for power supplies used in railway applications.

When testing vibration, shock and bump it is important to know the location of the final equipment – whether it is mounted in the driver’s cab or inside the passenger wagons or more exposed on the undercarriage or bogies. As DC/DC converters are primarily installed in locomotives, they must normally conform to the requirements of class 1B.

EN 50155 gives general guidelines: relative humidity of 75% on average, followed by 30 consecutive days with 95% relative humidity. For the electronic equipment this means in most cases watertight cases or lacquered assemblies.

Railway electronics must work properly even in extremely unfavourable electromagnetic environments. On the one hand, they are exposed to strong magnetic fields generated by electric motors and transformers. On the other, they must be able to withstand interference emitted from the pantographs.

And there are numerous additional sources of interference, brought on board by passengers carrying mobile phones and laptops. None of these sources of interference must in any way impair the function of highly sensitive components such as drive assemblies, motor control units and displays.

To ensure this, EN 50155 repeatedly makes reference to collateral standard EN 50121-3-2 "Railway applications – Electromagnetic compatibility – Rolling stock – Apparatus", which defines clear limits for radiated and conducted interference as well as stringent requirements with regard to resistance to overvoltage and transients. To meet these EMC requirements, an EMC filter is needed to protect the DC/DC converter and absorb any conducted emissions.

For historical reasons, a large number of different supply voltages are used in railway applications. The most common ratings are 24VDC, 48VDC, 72VDC, 96VDC and 110VDC.

The latest version of EN50155 defines seven different standardized DC voltages, although 110VDC is the most commonly used on trains. The 24V thru 48V is often used on light railways, trams and trolley buses.

In order to meet these requirements for nominal input voltages, railway application developers opt for 4:1 converters such as the RP20-FR and RP40-FR series from RECOM, as they cover the entire nominal input voltage range with 3 different converter models only.

Nominal Input Voltage	EN50155			RECOM RPxx-FR Serie
	Input Range	Min. Input (0,1s)	Max. Input (1s)	Input Range	Min. Input	Max. Input (1s)
24V	16.8-30V	14.4V	33.6V	9-36V	9V	50V
48V	33.6-60V	28.8V	67.2V	18-75V	18V	100V
72V	50.4-90V	43.2V	100.8V	43-160V	43V	170V
96V	67.2-120V	57.6V	134.4V	43-160V	43V	170V
110V	77-137.5V	66V	154V	43-160V	43V	170V

Fig.: EN50155 certified DC / DC converters must tolerate strong input voltage fluctuations. With the RPxx-FR series from Recom, the entire range from 24 to 110 V can be covered with three converter types. The RPA100H and RPA200H even cover the entire voltage range with only one module

EN50155 states that the nominal input voltage may fluctuate between 0.7 and 1.25 times the rated voltage, and permits short-term deviations between 0.6 and 1.4 times that value. This means that a 48V DC/DC converter must cater for a voltage range of 28.8V to 67.2V.

Until recently, there was a consensus that 4:1 converters had reached their limits with regard to efficiency and cost-effectiveness. This is now all changing with the latest 100W and 200W DC/DC converters from RECOM. The RPA100H and RPA200H feature a broad 10:1 input to cover all common voltage ratings in one module.

DC/DC railway converters are often referred to as bricks, half-bricks, and quarter-bricks. A full-brick measures 4.6 x 2.4 x 0.5 inches, a half-brick measures 2.3 x 2.4 x 0.35 inches, and a quarter brick measures 2.3 x 1.45 x 0.35 inches. But there are also DIP24, 1’’x1’’ and 2’’x1’’ cases for lower power converters.

Newer switched-mode power supplies in quarter-brick format deliver an electrical output of 250 watts or higher. This is a significant improvement in the slot that was previously needed and means more room for features that can now be added to the product.

The specification also includes the pin output; therefore, when using DC/DC railway converters that meet the standard, products can be easily replaced if the designer so desires.

这些年来RECOM将铁路行业所用的DC/DC转换器系列从8W拓展至240W，并且取得了市场高度认可的EN50155认证。

轨道交通认证系列产品最高功率240W，功率密度为4,5w / cm，是目前市场上最高功率密度的产品之一。为了优异的散热性能，RECOM推出1“x1”封装的12W RP12-AR、20W RPA20-AW和30W RPA30-AW系列，以及2“x1”封装的60W RPA60-FW系列。除了原有的专为铁路应用设计的4:1输入电压范围的DC/DC转换器是之外，最新的RPA100H和RPA200H系列甚至提供了一个令人印象深刻的10:1的输入电压范围，超宽输入电压范围涵盖了从24VDC至110VDC的标称电压（14.4VDC至156VDC）。

所有系列产品均有EN50155认证*，适用于轨道交通的恶劣环境。同时它们也是具有UL / cUL60950认证的，所以也是工业和电信应用的可靠选择。除了3.3V、5V、12V和15V的单输出，转换器也有±12V和±15V的双输出选择。控制引脚逻辑可以选择正或负。由于效率高达93%，自然对流的冷却方式已足够，但如果需要，模块也可以预先安装散热器。模块享有RECOM标准的三年质量保证。

RSPxxx-168是一款瞬态保护模块，用于保护铁路DC/DC电源免受高达385VDC的瞬态高压。

RECOM为DC/DC铁路转换器推出了高达240W的全系列评估板，适合高压(-1)或高电流(-2)输出的同时还包括RIA12浪涌抑制器。 R-REF04-RIA12.

• 输入电压范围: 9V至160VDC（标称)
• 功率8W至240W
• EN50155认证
• UL/IEC/EN60950认证 & CE
• UL 组件认可
• 效率高达93%
• 温度范围: -45°C至+97°C
• DIP24/SMD, 1"x1"、2"x1"、1/4砖型和1/2砖型

*RP08-AW, RP12-AR, RP20-FR, RPA20-AW, RPA30-AW, RP40-FR, RP40Q-RUW, RP60Q-RUW, RPA60-FW, RP75HRW, RP90Q-RW, RP100H-RW, RP120Q-RW, RP180H-RW, RP240H-RW