With single to 3-phase input voltage range of 90-528VAC
Abhishek Shukla, Vendor Development & Marketing, Saison Components & Solutions
Aimtec is a manufacturer of modular power supplies headquartered in Montreal, Canada with offices in Europe and Asia. Aimtec’s research, development,and design is driven by technological advancements, industry trends,and market needs. Aimtec’s product portfolio includes modular AC-DC and DC-DC switching power converters and LED drivers. Aimtec’s designs are intended to assist customers worldwide in reducing engineering design time and expense while facilitating miniaturization and enhancing the performance of their applications.
The depth of Aimtec’s electronic design capabilities allows it to deliver highly integrated power supplies that provide energy efficient and cost-effective solutions for a multitude of applications.Aimtec’s stringent guidelines for design criteria have made its power converters renowned for being reliable and robust products that are best in their class for their technical parameters and their quality/cost ratio. Aimtec’s AC-DC and DC-DC power supplies are recognized for exceeding industry norms in terms of features, performance, safety standards and power density.
In 2013, following the electronics trend of miniaturization, Aimtec began the development of an industry-first, low voltage (1, 2, 3 watts) power modules that provide the unique capability of combining single and three phase AC input voltages into a single power module. These new modules are particularly suited for industrial or building automation applications where a 3-phase transformer with very low efficiency is used to accommodate an input voltage up to 528VAC while providing high-efficiency conversion in a very small package.
During our development process, we used the most common 3-phase 480VAC systems: the 480VAC ∆ connection system and the 277/480VAC Y connection system. There might be a neutral in a 480VAC ∆ system and if so, it would be part of a 240/480VAC single-phase system and would be rather unusual. The 480VAC corner grounded ∆ supply system is essentially obsolete. For new constructions, the 277/480VAC Y supply system is preferred because:
- It can supply substantial power to three-phase loads
- It can supply 277VAC single-phase loads, including fluorescent lighting, using “300-volt class” wiring. Also, a 480-to-120VAC system is practical for most applications such as:
- Control power units that need to reduce the supplied voltage to lighting systems, test and control equipment, machinery, etc.
- Medical instruments that need reduced AC voltage to beplugged in directly.
iii.In several countries, power line instability must also be considered. As an example,the power line supply system in rural India has very wide upper and lower voltage variations.
With all these considerations, the priority for this cutting-edge design was to develop a direct plug-in type, switching mode power unit, that could provide voltage stability with high efficiency and high isolation. It also needed to havevery low no-load powerconsumption that would comply with all green initiatives and regulations.
These power modules allow the application system to be grounded in different terminal connection combinations while still complying to EN55022/EN55032 class B EMI.
In the most modern applications where the AME1-AZ, AME2-AZ or AME3-AZ series are used, system protection is our first consideration where a direct connection to ground could be applied to the input or output terminals. Therefore, the equipment will remain in electromagnetic compliance with the required levels for safe human operation.
Challenges in designing an AC-DC switching power supply with an ultra-wide 90-528VACinput
It is extremely difficult for electronic components to meet the full input voltage range with their standard specifications. To overcome this design barrier, the components had to be used in a series or parallel connection.
- The main challenge for these modules is designthe smallest formfactorwith careful attention to the PCB layout since the number of components is increased due to the added safety requirements at ahigh input voltage range.
- Another challenge for this design was to meet the EMC compliance and incorporate an EMI filter and EMC protection circuit in this very limited space.
- The most difficult part of the design was the Hi-Pot test because the case size is much smaller than traditional designs. The typical isolation distance by the safety standard IEC60950-1 is a minimum of 6 mm from the primary to the secondary side. In the AME1-AZ, AME2-AZ and AME3-AZ series, there is only 14 mm of physical space to place the components on the PCB with respect to the primary and secondary side.
- Lastly, the challenge with this design was filling the internal space with epoxy in order to split the heat equally and dissipate as much heat as possible to keep the component sufficiently cool during operation. As this is a very compact design, the uniformity of the potting process became very essential.
Internal circuit design
Even with the doubled Input Voltage range of 90-528VAC, the AME1-AZ, AME2-AZ and AME3-AZ series contain allthe modules incorporated in the standard power supplies working in the standard universal 1 phase input voltage range of 90-264VAC, as shown in Figure 1.
Because of the incorporated bridge rectifier, these switching power supplies may be used as low power (1, 2 and 3Watt) DC-DC Converters with input range 135 – 745VDC.
All internal electronic components are based on the standardrated and sizes available on the market. The design is an elegant and compact combination of standard electronic components with a unique mixture to deliver a truly innovative product.
The cutting-edge technology in the series designed as class II power supply (with no Earth/Ground input pin) have the advantage of performance not only in the ultra-wide input voltage range but also when it comes to performing with stable EMI compliance while connected to ground. Without the need of an external EMI filter, these power supplies can meet the EMI compliance with connections to the ground as shown in Figure 2 below.
AME1-AZ, AME2-AZ and AME3-AZ series with an ultra-wide input voltage range of 90-528VAC are remarkable unique low power AC-DC Converters with very low standby power andthe fullbreadth of features. They offer an exceptional advantage in applications such as home automation, control board power and any other applications where small power is supplied from a 3-phase power source or where the power line suffers from huge variations.