At low currents, shunts remain a viable solution, but they have isolation challenges and cannot provide the current sensing function alone. They require amplifiers and/or analogue-digital conversion (ADC) for signal treatment of the measured voltage drop.
Thanks to technical progress in semiconductor manufacturing and packaging, it is now possible to integrate all the stages of a current sensor in 1 single package. Current flows through the device, the induced magnetic field is sensed by two Hall-effect plates, the operation is contactless and provides inherent galvanic isolation, the voltage signal is treated inside an application-specific integrated circuit (ASIC) and this very ASIC also allows to add other ad hoc features.
As a leader in electrical measurement for 50 years, LEM is constantly developing new technologies to fit customers evolving needs. The company is now building a complete ICS range to serve evolving needs as well as new applications.
Integrated Current Sensors are Hall-effect based sensors that integrate the current conductor, the sensing elements, the signal treatment die, some dedicated features such as fault detections, and the isolation, all in one single package to reduce the footprint of the current sensing function.
For low current, shunts remain an alternative, but they have isolation issues and require additional electronics parts to fully complete the current sensing function. ICS are highly integrated products that work seamlessly in every application. At LEM they are the result of leveraging 50 years of fundamental electrical knowledge, customers applications understanding and product innovation. Integrated sensors are the most optimized pieces of hardware to sense the current in every environment.
IC sensors can use Hall-effect technology for current sensing.
Hall-effect sensing is one way to do contactless measurement of the current-induced magnetic field. A Hall cell is a sensing element that converts a change in the magnetic field into a change of its resistance. When a constant current goes through the hall cell, it will give a voltage output change proportional to the magnetic field.
Contrary to traditional Hall-effect current sensors, integrated current sensors are not using a ferrite core around the current conductor and the sensing elements to concentrate the magnetic field. They are using differential measurement.
Thanks to differential measurement, it is possible to get rid of the ferrite core while keeping a good response to external fields perturbations. Differential measurement uses 2 sensing elements (the Hall cells). They both receive the magnetic field to be measured, one with a positive factor, and the other with a negative factor. They also receive any external fields with the same incidence. When making the difference between the fields seen by the 2 cells, the unwanted fields cancel each other.
Integrated current sensors take advantage of differential measurement by not using a ferrite core. Getting rid of the magnetic core offers several benefits for embedded applications:
ICS are suitable for a wide range of applications where accurate control, efficiency and protection is needed. They allow designers to realize the current sensing function with a plug-and-play approach, with virtually all their challenges solved using only one part.
In DC/AC inverters and motors drives for example, LEM GO and HMSR can increase compactness and simplify design :
|GO Series||HMSR Series|
|IEC 61800-5-1: 2007||IEC 61800-5-1: 2007|
|IEC 62109-1: 2010||IEC 62109-1: 2010|
|IEC 62368-1:2018 (supersedes IEC 60950-1: 2005)||IEC 60950-1: 2005|
|UL 1577: 2014||UL 1577: 2014 (pending)|
|UL 62368: 2019.|