What methods do you think of when you hear the phrase “measuring the amount of current”? Perhaps many people imagine a method of calculating the current value from the voltage value that flows through a known resistor by passing the current to be measured.
Such a current detection method is generally called a “shunt method (current shunt method).” This method is suitable for detecting a small current in a system driven by a relatively low voltage without isolation. There are many inconveniences in handling in applications where high voltage of 100V or higher and large current of several to several hundred amperes flow, such as industrial equipment and residential equipment.
About Current Sensor
In order to solve these problems, a so-called “current sensor” was brought to the market.
The principle of the current sensor is shown in Figure 2.
The current to be measured generates a magnetic field around the current path. By detecting this generated magnetic field using a magnetic sensor, the amount of current can be measured.
Unlike the shunt method, the current sensor uses a conductor with a comparatively low resistance value as a current path. There is also no need to change the resistance depending on the amount of current. The current sensor will solve the inconveniences of the shunt method in the following ways:
In late 1980s, current sensors of various kinds (e.g. cored current sensor, module-type current sensor, and current transducer) were brought to the market and were used in many applications (Figure 3).
In late 2000s, the downsizing of industrial equipment accelerated and concern for the environment has led to the requirement of high efficiency and energy saving. This market trend revealed the following issues about current sensors in certain applications:
To remedy these problems, a “coreless current sensor” - a current sensor without a magnetic core - was developed (Figure 4).
The coreless current sensor solves the problems caused by the core while also maintaining the advantages of the cored current sensors.
Since the early 2010s, coreless current sensors have been used in many applications such as low voltage drives, AC servo motor drives, robot controllers, and air conditioners.
Summary of This Page
Types and Characteristics of Current Sensors
'Currentier' series are open-type current sensors which have the world's smallest package, high accuracy, high S/N ratio, and the world's fastest response time.
With these advantages, we will offer the best current sensing solution to wide-ranging applications, such as inverter control, overcurrent detection, and electrical power detection.
* Currentier is a trademark of Asahi Kasei Microdevices Corporation.