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The Advantages and Disadvantages of LLC Transformers

LLC is one of many switch mode topologies for power supply and battery charging. The LLC transformer is critical in determining an LLC resonant converter’s efficiency. Resonant tanks are circuits comprised of inductors (L) and capacitors (C) that oscillate at a fixed frequency known as the resonant frequency. LLC transformers have two inductors and one capacitor, a configuration that creates resonance at the switching frequency.

Here we’ll explain the pros and cons of LLC transformers, as well as their common applications.

What Is LLC Topology?

Half Bridge LLC Resonant Transformers
LLC is one of several switch mode topologies used in power supply and battery charging operations. The LLC transformer helps determine an LLC resonant converter’s efficiency. An LLC resonant power conversion topology reduces switching losses by enabling zero voltage switching (ZVS), which reduces needless power waste in switches. Power dissipation can be limited to as little as 2%, ensuring 98% total efficiency.

Advantages of LLC Transformers

These are some of the advantages of LLC transformers.

Cost Savings

LLC resonant converters are extensively used in industrial applications because they can integrate two resonant elements into one transformer. This helps designers save money on construction and supplies.

Regulation Compliance

Energy efficiency is critical for decreasing environmental impact while saving money. Even a 2% increase in total efficiency can significantly impact energy costs. With federal Energy Star criteria becoming increasingly stringent, LLC transformers are ideal solutions to achieve optimum efficiency.

Energy Efficiency & Sustainability

The market demands greater efficiency in server farms, LED lighting, gate automation, vending machines, battery chargers, and other areas. LLC resonant topology has an efficiency of 94-96% in the most basic circuit solutions, and it can improve further through synchronous rectification and other precautionary measures.

Compact & Effective

Compared to other topologies, LLC-LCC power supplies are smaller and have significantly lower electromagnetic interference (EMI) concerns, reducing EMI and harmonic pollution.

Aids EMI Design

It can control the output across a wide range of line and load fluctuations with very little difference in switching frequency, making basic EMI filters considerably easier to build.

Applications of LLC Transformers

LCC topology is the best choice for applications requiring a broad output voltage range, such as power supply for variable length LED strings (including deep dimming) or high-performance battery chargers.

Electronics industries rely on LLC transformers for their:

  • Electrical isolation
  • High energy density
  • High operation frequency
  • Low voltage stress
  • Magnetic integration
  • Wide output ranges

A precision LLC transformer is best for converters in a variety of energy-sensitive applications, such as:

  • Computers
  • High-end audio
  • Home appliances
  • Industrial LED lighting
  • LED/LCD televisions
  • Military

Drawbacks of LLC Transformers

These are some potential drawbacks to keep in mind when working with LLC topology.

Requires Sensitive Customization

The best design of a switch mode power supply (SMPS) transformer must inevitably address the limits associated with magnetic components; otherwise, it may result in a significant drop in efficiency.

Not Suitable for Operating Voltage Variations

Resonant topologies’ major shortcoming is in applications with substantial input or output operating voltage changes.

If the tank is appropriately designed, ZVS can be maintained even in the face of relatively high voltage changes. However, the benefits are reduced compared to alternative topologies due to the negative influence on cost and performance. The magnitude of this influence is often tolerable, but it does grow generally in proportion with voltage range expansion.

Contact MPS Industries for More on LLC Transformers

MPS Industries takes pride in offering high-quality LLC transformers and other magnetic components to clients in the automotive, aerospace, military, industrial, electronics, medical, and telecommunications industries. MPS is committed to meeting and surpassing client expectations as a leading manufacturer of standard and custom electronic components like transformers, common mode chokes, inductors, power supplies, and current sensors. Our strict quality management system and ISO certifications demonstrate our dedication to quality.

For additional information, contact us today, or request a quote for your next project.

Choke vs. Inductor: What’s the Difference?


Click to ExpandChoke vs. Inductor: What’s the Difference?

Choke vs. Inductor: What’s the Difference?

At MPS Industries, we specialize in manufacturing high-quality magnetic parts for automotive, medical, power distribution, and more. We’re ISO 9001:2015 certified, and we prioritize quality engineering practices to create products our clients can trust in critical applications, including inductors and chokes.

Both chokes and inductors can deliver and modify electrical current. However, inductors are generally used to sense, filter, or transform electrical current. They store that energy as a magnetic field around their inbuilt insulated coil. Chokes, on the other hand, are a specific type of inductor that restricts the flow of high-frequency AC and only allows DC through to downstream parts within an electrical system. Learn more about the differences between the two and how to determine the best fit for your needs.

What Is a Choke?

Chokes, a subtype of an inductor, are designed to restrict or control the flow of electrical current passing through its coil and core, which consists of a magnetic core wrapped in a wire insulated coil or a donut-shaped ferrite bead strung on a wire. Primarily, they prevent the flow of alternating current (AC). This component ensures only direct current (DC) passes through and reaches subsequent components. Because of this core functionality, chokes are typically used for protection. If they precede insulative components, they can increase the insulation’s longevity by blocking high-frequency alternating currents and sharp fluctuations in current levels. Chokes only allow a flow of more controllable (and thereby less damaging) current to pass through. They can also act as a check on certain systems.

Chokes can be designed for optimal performance in different types of environments, such as high-speed applications, circuits with next to no grounding components, electrical circuitry that may face disruption from noise, signal mixing, and other complications. They’re also commonly used in power supplies and direct current power lines.
Series 3 Phase Common Mode Choke

What Is an Inductor?

Inductors represent a wide array of different electrical components that can change, filter, store, and otherwise interact with electrical current. While chokes can restrict current and protect downstream components from overload, inductors are also valued for their storage capabilities. They also have a magnetic coil, which, properly energized by electrical current, generates and holds a magnetic field. These components can be large, often the largest component in a circuit, and can come in a wide range of shapes and sizes to meet the needs of a specific electrical system.

Common use cases for inductors include:

  • Filters: Inductors can restrict the flow of current and allow only certain ranges of electricity through to downstream components.
  • Energy storage: Inductors store energy by generating and holding a magnetic field.
  • Transformers: Inductors can be combined to create a transformer which transfers energy from one to subsequent multiple or singular circuits. They can change the voltage as the electricity is transferred from circuit to circuit, but the frequency won’t change.
  • Motors: Inductors convert electrical and magnetic energy into physical motive force.
  • Sensors: Inductors detect changes in electrical current through its impact on the inductor’s magnetic field.

Series Power Inductor

Chokes vs. Inductors: The Main Differences

Because chokes and inductors share many core attributes and applications, it can be difficult to know which one best serves a specific application. The key differences between chokes and inductors are:

  • Magnetic Field: Inductors can generate and hold magnetic fields as a form of temporary energy storage, often to switch power supplies and energizing circuits. Chokes do not.
  • Purpose: Chokes remove AC and only allow DC to filter through. Inductors can also provide this functionality, along with signal filtering; however, the inductor is then considered a choke when used for that purpose.

Before choosing the component for your design or system, determine its primary function and then select the best inductor or choke for those circumstances.

Chokes and Inductors From MPS Industries

When choosing high-quality electrical components, it is critical to know which components best serve your application. MPS Industries is a leading provider of inductors, chokes, and other electrical components that manufacturers can trust in their products and installations. Contact us today to learn more about our selection of inductors and chokes, as well as our manufacturing capabilities.

The Role of Forward Converters

Forward converters—also referred to as forward-converter transformers or transformers for forward-mode topology—are used in DC-DC conversion applications to provide voltage transformation and circuit isolation. They increase or decrease the voltage levels of DC input, depending on the duty cycle and number of windings. Compared to alternative topologies, they offer greater design simplicity, multiple isolated output potential, and ease of use.

The following article provides an overview of forward converters, outlining the types available, how they compare to flyback transformers, and typical end applications.

Types of Forward Converters

There are three main types of forward converters available:

Active Clamp Forward Converters

Active clamp forward converters have compound gates that move quickly to reduce switching losses during power conversion cycles. When voltage passes through the primary transformer coil, energy immediately transfers from the primary component to the secondary component, prompting current to pass from the output unit to the connected load.

Both forward converters and flyback converters can integrate clamp mechanisms in their designs—forward converters employ active clamps, while flyback converters utilize resistor-capacitor-diode (RCD) clamps. Despite similarities in the terminology, these clamps function and perform differently. For example, active clamps reclaim a large majority of leakage energy and recover almost all magnetizing energy. They also experience smaller energy losses during zero voltage switching and no voltage spike when turned off.

Fig.1: Typical Active Clamp Forward Converter Circuit Diagram

Fig.1: Typical Active Clamp Forward Converter Circuit Diagram

Fig.2: Current Flow w/ Q1 Closed, Q2 Open

Fig.2: Current Flow w/ Q1 Closed, Q2 Open

Fig.3: Current Flow w/ Q2 Closed, Q1 Open

Fig.3: Current Flow w/ Q2 Closed, Q1 Open

Single Switch Forward Converters

Employing the design principles used in buck topology, single switch forward converters focus on providing galvanic isolation in applications involving power levels of less than 200 watts. In these converters, closing the active switch connects the supply to the primary, which prompts the rectifier to conduct the current and pass it through the output inductor to the connected load. Until the switch reopens, the current rises linearly. Once the switch is opened, any energy stored in the inductor transfers directly to the load through the secondary diode.

Fig.4: Typical Single Switch Forward Converter Circuit Diagram

Fig.4: Typical Single Switch Forward Converter Circuit Diagram

Fig.5: Current Flow w/ Switch Closed

Fig.5: Current Flow w/ Switch Closed

Fig.6: Current Flow w/ Switch Open

Fig.6: Current Flow w/ Switch Open

Two Switch Forward Converters

As the name suggests, two switch forward converters feature two switches that open and close together when prompted. Closing both switches allows energy to transfer from the primary into the secondary. Within the secondary, a tertiary diode conducts energy into the output inductor and the load. Once the switches are opened, energy flowing the tertiary and quaternary diodes flows back into the source. Compared to the single switch topology, the two-switch topology does not require the use of a snubber circuit or demagnetizing winding.

Fig.7: Typical 2-Switch Forward Converter Circuit Diagram

Fig.7: Typical 2-Switch Forward Converter Circuit Diagram

Fig.8: Current Flow w/ BOTH Switches Closed

Fig.8: Current Flow w/ BOTH Switches Closed

Fig.9: Current Flow w/ BOTH Switches Open

Fig.9: Current Flow w/ BOTH Switches Open

Differences Between Forward Converters and Flyback Transformers

While forward converters and flyback transformers may look similar, there are several key differences between them. For example:

  • Forward converters use transformers to transfer energy, while flyback transformers store energy.
  • Forward converters feature a more complex circuit topology as compared to that of flyback transformers.
  • Forward converters are suitable for applications that require greater energy efficiency and higher power outputs (100 to 200 watts), while flyback transformers are suitable for power outputs up to 120 watts.

Typical Applications of Forward Converters                              

Fig. 10: Typical Flyback Converter Circuit Diagram

Fig. 10: Typical Flyback Converter Circuit Diagram

The Role of Forward ConvertersForward converters find use in the power supplies of a wide range of equipment and systems, including those for the following industries:

  • For the military: Military manufacturers use forward converters in unmanned aerial vehicles (UAVs), stun guns, dipole antennas, and more.
  • For aerospace: Aircraft have forward converters in their lighting systems, entertainment devices, searchlights, and cameras.
  • For renewable energy (i.e., solar power): Forward converters help prepare solar energy for storage and distribution by standardizing the output voltages. These components are in inverters and grid monitors in solar panel systems and built into electrical drive systems, storage inverters, and battery chargers.
  • For computers: Forward converters can be found in a variety of powered computer equipment, including laser printers, laptops, and IP routers. Home entertainment systems with set-top boxes that receive digital television broadcasts also use them.

Forward Converter Solutions From MPS Industries

Forward converters allow industry professionals to transform DC input to higher or lower voltage levels to suit the output demands of the end application. Compared to flyback transformers, they are more efficient and accommodate higher power outputs. Available in several different designs, they can meet a variety of power requirements and restrictions.

At MPS Industries, one of our core specialties is the production of forward transfers and output inductors for forward converters. By working closely with customers, our expert team designs and delivers quality magnetic solutions tailored to their exact needs.

We’re proud to serve the following industries:

For additional information about our forward converters or our other products and services, contact us today.

MPS Contributes to Clean Year Round

With Earth Day quickly approaching, our MPS Industries team is taking the time to assess how our magnetic components contribute to the global movement for clean, renewable energy sources. The annual day for celebrating green initiatives lands on April 22.

Our Year’s Vision

MPS Industries recently shared our expansion plan for 2017: extending our product lines and providing excellent engineering support, including improved lead times. In our efforts to provide an even higher level of overall customer service, we are paying attention to industry trends, specifically the rising popularity of electric cars.

Advancing Clean Technology and Green Initiatives

We expect the EV (Electric & Hybrid Vehicle) industry to continue to expand and MPS Industries is responding to growing customer demand in the plug-in marketplace. This is why our engineers, with over 60 years of design experience, are working alongside leading EV technology developers to develop components that will have a large impact in the industry. Our mechanisms can be used in EV Charging stations, including wireless charging stations, just as easily.

By participating in trade shows, such as the Electric & Hybrid Vehicle Technology Expo last September, MPS aims to have more involvement in developing and contributing to the worldwide effort for energy sustainability. We will also be exhibiting at the 2017 EV TECH show as well.

Other clean, renewable energy and green initiatives that we have taken on include the implementation of fuel cell, PV and wind turbine systems. Moreover, MPS products are used in converting power for inverter applications, for example, off-grid inverters, grid-tied inverters, string and central solar inverters, solar optimizers, solar maximizers, solar micro-inverters, and they are also being used in smart metering applications.

Innovative Strategies

Within the magnetic components field, MPS proudly holds a name for manufacturing sophisticated, innovative parts that meet the needs of the general industry, EV magnetic technology, charging stations, wind turbine systems, inverters, the solar industry, smart applications, and more. Our engineers offer custom design on magnetic components, to meet clients’ individual project needs, whether it be electrical or mechanical variations or a completely new design.

MPS Industries provides a broad range of products, from transformers to common mode chokes, inductors, current sensors, and power supplies, to U.S.-based customers. Our magnetic components come in a range of sizes, and the power supplies include desktop, industrial, open frame, wall mount, and medical-grade varieties.

Keep up to date on how our MPS team is engaging in greener solutions, on Earth Day and throughout the rest of the year, by connecting via our blog, Twitter, and LinkedIn. For your next magnetic component project, please contact us today.

Advancing Energy Efficiency

A growing concern among many different industries is energy efficiency.  From energy efficient cars, to an electricity grid that comes from renewable sources (or both if you’re Elon Musk), to the next phase in the Energy Efficiency and Security Act, the goal of more efficient ways to produce, store, and use energy are on the minds of consumers and business owners alike.

Being efficient with our energy has many implications.  On the consumer level, being energy efficient may mean a decrease in a monthly electric bill, and thus a more flexible budget.  At a business level, investing in efficient energy sources and use can not only affect the bottom line, but can future-proof your business from both the perspectives of a changing attitude toward energy sources and a public policy that reflects that changing attitude.  On a global scale, the way we use our energy can have economic and environmental effects, by easing the strain on the grid to prevent blackouts at peak use times, and by lessening our impact on the use of energy sources that are not renewable.

As we search for better ways to produce and use energy, the burden on manufacturers of all kinds is to build products that use energy in more efficient ways.  In the auto industry, for example, this has led to a “lightweighting” trend, as lighter materials improve fuel economy.  In electronics, the same principles of efficiency apply: improving performance while consuming less power.  This is what MPS is seeking to do with our new LLC Resonant Transformers, and as an integral part of our design and engineering philosophy.  We’re constantly looking toward the future, and in this case, the future is one where we use our energy more efficiently.

Augmented Reality and the Future of Electronics Technology

As we’ve mentioned in previous blogs, our industry is one that is constantly being inundated with new and exciting technologies, all of which are of interest to electronics manufacturers as interesting combinations of developments that seek to improve our lives.  One exciting new technology we’re interested in here at MPS is the field of augmented reality.

The concept isn’t that new, but the recent development of Google Glass has thrown the subject into the public eye again.  In our age of ever increasing and exhaustive information, augmented reality seeks to tap into that wealth of knowledge in real time to give us instantaneous and personalized access to deeper levels of information based on our surroundings or inquiries.  Smartphones have already made huge strides in this pursuit, but the innovation of Google Glass is the visual and vocal access to that information.  Now, rather than pulling out a smartphone, you can give a voice command, and read the results projected in your field of vision from a tiny projector, visible only to you.

The implications of this are astounding for medicine, the military, the consumer, travel, education, industry – the list goes on.  Even though the technology is in an early stage, as it improves, and we approach universal and access to wireless internet at high speeds, this type of technology is a bit step toward universal connectivity, a still astonishing and ambitious goal.  It also of high interest to custom electronics manufacturers like MPS, as we’re seeing the elements of our business combined in ways that improve lives and make information management more efficient.  These are the moments and times when we’re proud and excited for what the future of the electronics industry holds.  Tweet @MPSIndustries to get in touch, or visit our website to find out how MPS can help make your latest technology a reality – we’d love to hear from you.

MPS and Oceanic Research

Part of the exciting nature of our job here at MPS is the opportunity to be a part of fascinating projects from time to time.  We think one of our latest projects is especially interesting, and worth talking about with you here on our blog.

The Canadian Scientific Submersible Facility is a non-profit in Canada that aids oceanic research and discovery, partnering with various universities and local companies to promote the national ocean technology industry.  Our expertise in custom electronics gave us the opportunity to supply their ROPOS (“Remotely Operated Platform for Ocean Science”) vehicle with a mini video isolation transformer.  This was then put onto an NTSC composite video isolation board that works in tandem with a Fiber Optic Mux Control Can in the ROV.  This essentially means that our technology aided in the capture and transmission of images from varying depths under the sea to the surface for observation and study, as well as to assist in a fiber optic cable laying program that the ROPOS was involved with.

Oceanic research is highly important for the understanding of our weather and climate, natural disaster research, geochemistry, and the investigation of potential alternative fuels located in deep-sea deposits.  MPS is proud to play a part in such impactful research, and to provide pieces of the electronic puzzle that aid a deeper understanding of our world.  Check out the expedition website here, and be sure to check back here at our blog for more interesting projects we’ve been involved in.

Customer Satisfaction Case Study

Here at MPS, we believe in our capability to design and manufacture great products.  We also believe that making the best products we can for a wide range of applications and industries, designing custom solutions to the exact specs our customers need, and using flexible shipping and sourcing options to provide great turn-around times, are great ways to ensure our customer’s satisfaction.  We know that keeping our customers happy is one of the key ways to keeping our customers – so every year, we conduct a survey to measure the level of satisfaction we were providing and find areas where we can improve.

We asked about our shipping time frame, product satisfaction, customer service evaluation, comparisons to competition, and whether our customers would recommend us, and the results were overwhelmingly positive: nearly 70% of customers who responded to the survey said they were “extremely likely” to recommend MPS to others; nearly %90 said they were “very satisfied” with our services.  Not one respondent said that they had found a competitor with better products.  These kinds of responses are wonderful for MPS to receive, because they reflect the kind of business that we are continually striving to be.

We do these surveys because we are committed to providing a caliber of service that is equal to the caliber of our products.  We want your feedback because we want to provide the kinds of service that will make you delighted to tell us and others about it, and are on an ever-expanding quest to see that we make that happen.  Head over to our web or social sites to get in touch with us, and make your voice part of our process of improvement here at MPS.

See the Latest Advancements at APEC 2013

We’re extremely happy to announce that we will be attending the Applied Power Electronics Conference, or APEC, this month in Long Beach, California. APEC has been held every year since 1986 to address practical and applied aspects of the complicated power electronics business. Whether you’re a power electronic designer, a manufacturer of such components, an OEM, or even just in marketing or sales in the industry, you’ll be able to get some important information and insights from APEC 2013.

At MPS we take great pride in the manufacture of all of our components. Materials used in the production of our power transformers and other pieces conform to the highest possible standards. Whether these components are being used in consumer electronics like your smartphone, or in the electronic systems of airplanes and automobiles, our customers know that our power electronics can always be relied on. By working together with our customers, and making sure that we make the best use of the information available to us, we will continue to improve our components and manufacturing process. This is why we go to industry expos like APEC and strive to make sure that we remain on the cutting edge of innovation and quality.

This year’s APEC will kick off on March 17th and end on the 21st. And while you’re attending, remember to come on down and visit us at Booth #1101 to see our skill and experience in power electronic manufacturing firsthand. We hope to see you there.

The Automotive Recovery, Powered by MPS

Recent news and trends all point to a giant recovery for the American auto industry. Most major automakers saw moderate to large sales increases in 2012; one market research firm, Polk, now expects new car sales to increase by 6.6% in 2013, thanks to a recovering economy and growth in the pickup truck and midsize sedan markets.

Last year, American auto company, Chrysler reported its highest sales since 2007. Meanwhile, the Japanese automakers have been recovering from the 2011 earthquake and tsunami that devastated factories and drastically decreased production; Toyota, for example, sold a record 9.7 million vehicles last year, and expects to sell even more in 2013.

Whether you’re dealing with a German vehicle or an American one, a pickup truck or a compact car, quality products from MPS Industries are the best parts for automotive applications. We provide TS16949-certified manufacturing, and we also bring extensive experience with automotive requirements like IMDS and PPAP to the table. Our transformers and inductors are not only reliable and energy efficient, but they’re competitively priced to boot.

No matter how severe the environmental condition or temperature, our magnetics are guaranteed to perform. We manufacture parts that can be used in fuel pumps, particulate matter sensors, and DC/AC inverters that can be used to power electrical devices inside of vehicles, like TV screens or DVD players. MPS Industries components are at work in every part of the car.

2013 promises to be a one of the biggest year for vehicle sales in quite a while, and MPS Industries products will be there to make sure everything keeps running smoothly.