When a power converter doesn’t require very high power – i.e. 200 watts or less – flyback converters are good choices due to their lower cost, decreased quantity of components, and simple design. Flyback converters are used in a variety of equipment, including televisions, LED lighting arrays, telecommunications, and industrial systems.
One of the main components within a flyback converter design is the transformer. The primary distinguishing feature of a flyback transformer is a gapped core that holds energy from each input cycle.
The energy stored in the transformer’s core allows it to efficiently increase or decrease the voltage as needed for equipment operation.
How Does a Flyback Transformer Work?
A flyback transformer circuit looks similar to other isolated transformers, and it uses many of the same components, including a switch, output rectifier or diode, and input and output capacitors. Unlike other isolated transformer designs, however, flyback transformers store energy within the core without the need for a separate output inductor. This highly efficient construction facilitates cost-effective power usage by ensuring circuit isolation and allowing both positive and negative output voltage.
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Switch
The most common switch design for flyback converters is the metal oxide semiconductor field effect transistor (MOSFET), which consists of three terminals that modify the intensity of and redirect electronic signals. Switches for flyback converters may also be composed of bipolar transistors, gallium nitride (GaN), or silicon carbide (SiC).
When the switch is closed (or in the on position), current flows through the primary coil and gets stored in the core. When the switch is off, the current flows through the secondary coil and is transmitted to the output load. The output voltage is modified by adjusting duty cycles and turn ratios between the primary and secondary coils.
Coupled Inductor
The coils that transmit and store energy in a flyback transformer form a coupled inductor. The two coils are linked by mutual electromagnetic inductance—when energy flows into the primary coil, it creates a magnetic link and generates voltage in the second coil.
Coupled inductors are used to modify voltage. They can also be used to isolate circuit components to enhance the efficiency of electrical flow. When the switch is on, energy flows into the primary winding and gets stored in the core. The stored magnetic flux flows into the secondary winding when the switch is turned off, and the energy is then distributed through a diode.
Output Diode
Current may be increased, decreased, or modified as it flows from the second coil. Diodes ensure that the current flows unidirectionally toward the output and keep the voltage as necessary to meet the needs of the application. Since current from the transformer can fluctuate based on the input voltage, the diode and output capacitor help to keep the outflow of current steady.
Input and Output Capacitors
Capacitors in flyback transformers can be installed on both the input and output ends of the current flow. They are used to store energy so that it can be released in controlled amounts. Input capacitors control the flow of energy into the primary coil, while output capacitors manage the output to ensure a smooth flow of energy at the desired voltage and current.
Applications of Flyback Transformers
Flyback transformers are highly efficient, compact, and cost-effective, which makes them ideal for numerous applications and industries. Some of these uses include:
DC-DC and AC-DC power supplies: Flyback transformers are used to facilitate the conversion of AC to DC and DC to DC in power supplies for a variety of devices that require current and voltage modification.
Televisions and computer monitors: The first flyback transformers were invented for use in televisions, and they continue to provide a reliable source of steady voltage for computer monitors, televisions, and other visual displays.
Aerospace components: The compact size, efficiency, and accuracy of flyback transformers make them perfect for use in electrical equipment found in aerospace applications.
Telecommunications equipment: Flyback power converters are often used for DC to DC power conversion in telecommunication systems.
LED lighting systems: Flyback transformers are used in LED drivers to regulate the output current from the power supply.
Capacitor and battery charging systems: Flyback transformers convert current and transmit energy in capacitor and battery chargers.
Converters and inverters: Since electrical converters and inverters operate at varying frequencies, flyback transformers adjust the voltage and current levels for a consistent power supply.
Industrial systems: A broad range of industrial equipment uses flyback transformers to enhance operational efficiency and improve the performance of electrical components.
Advantages of Using Flyback Transformers
Flyback transformers offer numerous advantages over other converters, including:
Circuit Isolation: A key benefit of flyback transformers is their circuit isolation, preventing electrical hazards and providing improved safety, particularly for those in the vicinity of high energy electrical systems.
Compact Size: The simple design of flyback transformers makes them smaller, lighter, and easier to install than comparable transformers – meaning they are likely to be a better fit within your overall electrical system.
Cost-Effectiveness: Flyback transformers are generally about the same investment as other transformers. However, flyback converters – of which flyback transformers are a key component – are typically less expensive than comparable converters, since they are made up of fewer components. This is important to keep in mind if you are considering flyback transformers and their application within flyback converters.
Convenience: You can use flyback transformers to isolate and manipulate multiple output voltages from one control.
Considerations When Designing a Flyback Transformer
Flyback transformers are available in numerous designs and configurations. Before attempting to select or design an appropriate flyback transformer for your needs, gather the following data about your application to present to your component provider:
Maximum size and weight requirements
Switching frequency
Max duty cycle
Mounting type: surface mount, through-hole, etc.
Input voltage
Power and Output voltage (load)
Quality Flyback Transformers at MPS Industries
MPS Industries, Inc. is proud to offer an extensive range of quality electronic components for our customers in a wide range of industries, from aerospace and automotive to military, telecommunications, and renewable energy. We specialize in custom-manufactured inductors, power supplies, current sensors, and transformers. Our extensive experience in circuit design and engineering allows us to create unique electronic components to meet the most stringent industry standards and specifications.
MPS Industries is a U.S.-based magnetic components manufacturer specializing in the design of custom transformers, inductors, common mode chokes, current sensors and many other custom magnetics.
Switch mode power supply (SMPS) transformers use different switching topologies, transferring the required power from input to output in the electronic systems. Here, we have answered some of the most frequently asked questions regarding this unique and efficient transformer technology.
How Does a Switch Mode Power Transformer Work?
Switch mode transformers are used within switch mode power supplies to provide power to a range of commercial and industrial electronic systems. These transformers are highly efficient at converting alternating current (AC) main power to direct current (DC) output voltage. The AC main power is filtered through a capacitor when power is switched on, allowing it to be converted from AC voltage with rectifiers to unregulated DC voltage. Using a regulator, the switch mode transformer then converts this unregulated DC voltage into regulated DC output voltage at different voltage levels.
What Are the Common Applications of a Switch Mode Power Transformer?
Most modern electronic applications rely on power supplies that can very efficiently convert low-frequency main AC power to the well-regulated DC voltage required by the circuit. SMPS transformers are often preferred due to their ability to provide a tightly regulated output voltage. A few specific applications of these transformers include:
Medical devices
Communication devices
Commercial power supplies
Security systems
Support supplies for PLCs
Audiovisual products
What Makes Switch Mode Power Transformers Different From Other Transformers?
By internally switching the transistor between an on and off state, switch mode transformers can minimize a power supply’s energy dissipation, resulting in a higher efficiency with less heat produced when compared with those transformers used in linear power supplies. Linear power supplies typically require large power transformers to step up or down voltage before it can be applied to the regulator circuit. In general, linear power transformers tend to be bulkier and substantially less efficient than switch mode power transformers which are smaller and compact given their higher operating frequency.
What Are the Different Switch Mode Power Transformer Topologies?
The topology of a switch mode power transformer refers to its specific circuit configuration. A few of the basic topologies used in power design include:
Flyback: The flyback is an isolated topology in which energy accumulated and stored during the “on” state of the switch is transferred to the output during the “off” state. This is one of the simplest and lowest-cost isolated topologies and is best suited for lower-power applications.
Forward converter: Rather than storing energy in the core, forward converters directly transfer energy between the primary secondary sides. Like flybacks, forward converters are best suited for lower power applications.
Push-pull: The push-pull topology is basically a forward converter with a dual-drive winding, making it much more efficient at utilizing the core of the transformer when compared with flybacks or simple forward converters.
Half-bridge: The half-bridge is a type of forward converter topology. Half-bridge topologies are designed so that the load current can flow in two directions.
Full-bridge: The full-bridge topology is essentially two half bridges. It has similar switch ratings as the half-bridge but provides twice the output power.
Gate-drive: Gate-drive transformers are used in switch mode power supplies to control circuit timing through the delivery of electrical pulses.
What Are the Advantages of Using a Switch Mode Power Transformer?
When it comes to modern electronic applications, SMPS transformers offer several clear advantages over alternative methods of converting DC power. These include:
Higher efficiency: The regulator’s switching action allows it to be in either on or off mode. Because of this, energy dissipation is minimal and power can be used extremely efficiently.
Lighter weight: Compared with linear transformers, switch mode power transformers are much smaller and lighter. This is possible due to their high operating frequency and highly efficient power usage.
Greater flexibility: Unlike linear transformers, switch mode power transformers are capable of creating high conversions in both voltage-boosting and voltage step-down applications.
What Are the Design Considerations for an SMPS Transformer?
When designing an SMPS transformer, it is important to consider the following parameters:
Input and output voltage
Output power or current
Switching frequency
Operating mode
Maximum duty cycle of the IC
Safety standards
Temperature requirements
Size requirements
Three primary design considerations are core shape, type, and size, all of which should be chosen based on your application’s power requirements, switching topology, and anticipated switching frequency. Certain core materials have properties that make them better suited for higher-frequency applications. It is also important to make sure the components and wiring do not go above their rated temperatures, as this will affect overall circuit reliability. Industry-specific safety requirements should also be kept in mind to ensure the compliance of your design with relevant regulatory standards.
Are There Any Transformer Design Considerations for IC Chips?
Generally, our customers’ design engineers will start with an integrated circuit/IC chip, which typically has some kind of reference design with suggestions on transformers and other components to be used with the chip. They can either start with the reference design and modify it to suit their application, or they might opt for their own custom design using the chip.
We currently work with several IC companies and are on some reference designs already. However, we can definitely work with the customer to supply transformers per their reference designs or create a custom design to meet their application needs.
Contact MPS Industries for SMPS Transformer Guidance
At MPS Industries, our electrical engineering team regularly provides magnetic component guidance and design assistance for even the most complex industrial systems. Whether you require minor modifications to a standard product or a complete custom design from scratch, our engineers possess the insight and resources to meet your exact specifications. We uphold a strong quality management system to make sure that every product we deliver meets or exceeds customer expectations and complies with all relevant industry standards.
To learn more about SMPS transformers at MPS, check out the links below:
Magnetic components are passive elements that rely on an internal magnetic field to alter electrical current. They play a critical role in many electronic devices, equipment, and systems. Some of the industries that often make use of them include:
Appliances: Magnetic components play critical roles in both common household and advanced industrial appliances (ranging from refrigerators to telecommunication devices), particularly when it comes to converting AC to DC as well as power line filtering.
Automotive: Magnetics are found throughout cars, regulating voltage in power supplies for climate control, dashboard display, interior and exterior lighting, and other systems. The advent of electric and hybrid vehicles has increased the range of applications for magnetics in the automotive industry.
Communications: Magnetic components are used for both low-voltage and high-voltage communication systems, such as radio frequency circuitry in cellphones or conductors in high-voltage transmission systems. Larger transformers are also critical to the telecom infrastructure.
Computers and Electronics: Many types of magnetics components are found in computers and other personal electronic devices. By selecting optimal components, manufacturers can increase power efficiency, and in certain cases can decrease size.
Defense: The defense industry’s demand for magnetic components has expanded as surveillance equipment, transport vehicles, and weaponry have become more and more advanced.
In the following article, we provide an overview of magnetic components and the three main types employed by industry professionals—i.e., transformers, inductors, and chokes. Additionally, we cover the product offerings available at MPS Industries.
What Are Magnetic Components?
Depending on their configuration and function, magnetic components can be categorized into the following groups:
Low-Frequency Magnetic Components: These elements are generally designed for use in applications involving frequencies between 50 to 500 Hz and voltages of 220 to 240 VAC. Typical applications include conveyor systems, HVAC systems, line filtering, motor drives, and uninterrupted power supplies (UPSs).
High-Frequency Magnetic Components: These elements are designed for frequencies in the kilohertz (kHz) or Megahertz (MHz) range. Typical applications include computers, communication systems, electric cars, and mobile device charging systems.
Isolated Magnetic Components: These elements protect users from electrical shock in applications where incidental contact may occur. Typical applications include laptop power supplies and wearable medical devices.
Non-Isolated Magnetic Components: These elements reduce noise or briefly store energy for use in future operations. They are generally used in applications where human contact is less of a concern.
They can also be classified into two main product groups: transformers and inductors. Transformers change the voltage level by stepping it up or down, while inductors introduce resistance to the circuit and store current.
Both products rely on the property of electromagnetic inductance, which was discovered by English scientist and inventor Michael Faraday and American scientist Joseph Henry separately but concurrently in the 1830s. Faraday’s Law, as it is often called, describes how changes in the magnetic environment of a circuit result in the generation of electrical current and, conversely, how an electrical current generates a magnetic field.
Below we provide a more detailed description of transformers and inductors, outlining their function, basic design and construction elements, types available, and key design and selection considerations.
Transformers
Transformers consist of two or more coils of wire that allow for the transference of electrical energy when subjected to a changing magnetic field. They are primarily used when the power within a circuit must be transferred between two different levels. In addition to stepping the voltage up or down, they also function as filters or stabilizers for the circuit’s voltage levels.
Types of Transformers
These magnetic components are available in many designs and configurations, each of which is suitable for different use cases. Some of the most common include:
Single-Phase Transformers: Single-phase transformers contain two windings, a primary and secondary one. By connecting the two components, they enable the transfer of AC power from one circuit to another.
Three-Phase Transformers: Three-phase transformers consist of primary and secondary windings that each contain three separate but connected windings. They are generally used for the generation, transmission, and distribution of electrical power in industrial applications.
Step-Up/Step-Down Transformers: These transformers increase (step-up) or decrease (step-down) the voltage as current flows through them.
Power Transformers: Power transformers are used for the transmission of higher voltages within and between systems.
Current transformers: Current transformers are used for measuring or monitoring current for control and/or load centers. They are implemented for current measurement, electrical load monitoring, energy and sub-metering products, network equipment, instruments and sensors, control systems, and green initiatives.
Isolation Transformers: Isolation transformers regulate high current and voltage levels by separating the primary and secondary windings. This design protects any devices connected to the secondary windings from overload damage. Current transformers and potential (i.e., voltage) transformers are both variations on this design.
Design and Selection Considerations
When designing and selecting a transformer, there are many factors to keep in mind to ensure it functions as intended. Some of the key considerations include:
Winding Design: The way a winding is coiled around the transformer core significantly affects the component’s efficiency and durability, as well as the resulting transformer type (i.e. flyback, push-pull). There are two types of electrical coils: primary and secondary windings. In a nutshell, primary windings receive power while secondary windings deliver the power. These windings are not electrically connected but share a common core, enabling the transfer of electrical power between the two coils. Voltage and current are directly correlated to the number of the primary and secondary coils’ turns around the core.
Material: Similar to the design of the winding, the material used for the construction of the winding and insulation can affect the performance of a transformer. Typical winding materials include aluminum and copper, and typical insulation materials include meta-aramid. The material makeup of the transformer core itself enables a successful pathway for magnetic flux. As well, the extent to which a magnetic field can be increased by the core is dependent on the magnetic permeability of the transformer core material. Examples of common transformer core materials include:
Amorphous Steel Core: ideal for high temperature, high efficiency, or medium frequency transformers; one of the most commonly implemented transformer core materials.
Solid Iron Core: This core material is able to produce high magnetic fields without iron saturation; DC applications are typical use cases.
Laminated Silicon Steel/Iron Core: Laminated cores are created by thin sheets of stacked silicon steel or iron, which are coated with an insulating layer to prevent losses of energy via eddy currents in alternating current (AC) components.
Size: The size of transformer needed depends on the expected load capacity required. Other factors that influence size include future growth expectations, space constraints, and budget limits.
Inductors
Inductors consist of a wire coil or loop wound around a metal core. They allow for the storage of energy and the introduction of resistance to a circuit. As current runs through the circuit, the element stores it in the form of magnetic energy. When the current flow ceases, the magnetic field generates voltage in the conductor.
Types of Inductors
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Similar to transformers, inductors are available in many variations to suit different applications, such as:
Bobbin-Based Inductors: As suggested by the name, these inductors are wound on cylindrical bobbins. They are generally employed in printed circuit boards (PCBs).
Toroidal Inductors: These inductors have toroidal (ring- or donut-shaped) cores.They typically come at a smaller size and lighter weight – about half the weight and size of more conventional inductors – making them a great choice for smaller power supplies. Toroidal inductors offer stronger magnetic fields and lower electromagnetic interference (EMI), making them ideal for higher-frequency and lower-power applications.
Multi-Layer Inductors: These inductors feature multiple winding layers, which increase inductance and capacitance capabilities. Multi-layer inductors are commonly found in DC/DC power conversion circuitry within smartphones and wearable devices, for example. The inherent structure of these inductors offers space and cost reductions for the circuit system overall.
Film Inductors: These thin inductors are used for DC to DC converters in mobile electronic devices, such as smartphones.
Variable Inductors: Variable inductors allow the magnetic core to be moved, allowing the circuit to “tune” between frequencies.
Design and Selection Considerations
When designing and selecting an inductor, industry professionals rely on some of the same considerations as those for transformers, such as winding design, size, and material. Other factors to keep in mind include series resistance and interference from other devices, both of which may cause operational issues if left unaccounted.
Chokes
Chokes consist of insulated wire coiled around a magnetic core. They are a type of specialized inductor designed to block high-frequency alternating current (AC) while allowing low-frequency direct current (DC) to pass through unhindered, minimizing the risk of noise interfering with system performance.
Types of Chokes
Chokes are available in two variations:
Common Mode Chokes: These chokes feature two or more coils on a single magnetic core, with each winding positioned in series with the conductors. They are effective at blocking noise in applications involving two conductors with currents that are equal but flowing in opposite directions.
Differential Mode Chokes: These chokes operate similarly to common mode chokes but generate flux in the opposite direction to cancel noise-causing current. They are ideal for use in applications that require noise filtration from a single conductor.
Design and Selection Considerations
When designing and selecting a choke, key considerations include impedance, frequency, and current requirements. These factors influence the optimal winding design, core, winding, and insulation materials, and mounting method for a given application.
Contact the Magnetic Component Experts at MPS Industries Today
At MPS Industries, we offer an extensive selection of magnetic components suitable for use in a wide range of electronic devices. Our product portfolio includes transformers, inducers, and common mode chokes. By partnering with us for their magnetic component needs, our customers benefit from our:
Broad product lines
Custom design capabilities
Domestic design and manufacturing support services
Commitment to superior product and service quality
For additional information about our magnetic component offerings, contact us today.
