types of optical isolator for ac transmission

#Types of optical isolator for ac transmission drivers#
#Types of optical isolator for ac transmission Offline#

A capacitive isolator’s inability to pass DC signals makes it inherently the right choice for isolation, which is why it is widely used in sensitive and important applications, such as telecom and industrial power. According to Reference 1, magnetic isolation can be sensitive to electromagnetic interference, and high magnetic fields are strong and prevalent in some applications, such as HVAC systems and factory automation involving motors.įigure 1: Various Galvanic Isolation Technologiesįor capacitive isolation, which is made by adding capacitive isolation barrier on top of each die to connect in series, digital circuits are used for encoding and decoding various signals through the isolation barrier.

A popular physical form for magnetic isolation in AC/DC conversion is to use a special tooled lead frame to form a magnetic link between the primary and secondary side. Magnetic isolation can be achieved using coupled inductors. It is easy to see how much space two big optocouplers take up on a small 5W Apple adaptor in Reference 4 4. Sometimes, a second optocoupler is required for additional over-voltage protection (OVP) and takes up quite a bit of PCB space. However, the reliability of optocouplers can degrade as these devices suffer from aging, temperature drift, and varying current gain issues. Optical technology is light-emitting diode (LED)-based and is widely used in AC/DC conversion for output feedback. However, IoT devices may not require isolation from AC, as the AC/DC portion of such device has no direct contact with the end users during normal operation.Ī galvanic isolation barrier is based on either optical, magnetic, or capacitive isolation (see Figure 1) 2,3. As another example, AC/DC battery chargers are required by UL to offer isolation protection, as the output is typically user-accessible. A more detailed introduction to galvanic isolation can be found in Reference 1.įor example, as in electric vehicles, the high-voltage battery that powers the drivetrain is isolated from the low-voltage electronics by various isolated links across all sub-systems. If any failure occurs on the control end, the isolation barriers prevent the high voltage from reaching users and cause catastrophic results. For power supplies where the input end may be a hazardous high voltage, the input must be galvanic isolated from the control end or output end (which may include a human-accessible terminal) with enough safety distance. The “isolation” mentioned in this article also refers to galvanic isolation, which is used to isolate functional sections of electrical systems to prevent direct current from flowing between them.

This articles explains why capacitive isolation can be a fundamental building block in future AC/DC power conversion, how it exceeds the performance of other isolation technologies, and the unique advantages it can bring to end applications.

#Types of optical isolator for ac transmission Offline#

However, the potential to use capacitive isolation to replace optocouplers in offline adaptors is often neglected.

Switching Converters and Controllers AECQ GradeĬapacitive Isolation: A Fundamental Building Block in Future AC/DC Power Conversion by Zhihong Yu, AC/DC & Lighting Product Marketing Manager, Monolithic Power SystemsĬapacitive isolation is a mature solution developed over the past decade to replace optocouplers in signal isolators, isolated gate drivers, isolated transceivers, and other applications 1.

#Types of optical isolator for ac transmission drivers#

BLDC Pre Drivers and Integrated Solutions.Battery Management System: Monitor & Protection.Digital Isolators with Integrated Power.Multi Phase Controllers & Intelli-Phase.