Currentier

Issue & Solution

For the reasons outlined in that article, Asahi Kasei Microdevices (AKM) developed the unique coreless current sensor IC, titled “Currentier”. Currentier is the outcome of long experience and unique technology AKM has with compound semiconductor magnetic sensors (Hall elements), package design, and analog circuit design. 

Currentier is used in industrial and residential equipment around the world and contributes to meeting the following requirements:

Benefit

  • Reducing system size (i.e. equipment size)
  • Reducing design man-hours
  • Creating a safer system
  • Improving system efficiency and providing more precise control

Reducing Design Man-hours

In part 2, it will be explained here how Currentier can contribute to reducing design man-hours.

Load Capacity

Many control devices, such as general-purpose inverters for controlling motors, AC servo motor drives for precise position control, and controllers for robots to automate operations, need to support motors with various load capacities and torques depending on applications.

Current detection elements used for motor current control is an issue to be solved. For example, the conventional method is to use a shunt method for models with a relatively small current amount of 20A or less, and a cored current sensor for models with a larger current amount.

Some of issues are:

  • It is necessary to design and verify a control board in each model of the shunt method and the cored current sensor.
  • The shunt method needs to change resistance values depending on the amount of current. Therefore, it is necessary to design and verify a footprint of substrates and a subsequent stage correction circuit each time.
  • The shunt method generates a large amount of heat so that detailed heat radiation design and verification of the substrate are required.

Current Measurement Range

Currentier supports a current measurement range from ±5A to ±180A in the same packages. 

The current range, which previously required design and verification for both the shunt method and the cored current sensor, can be handled by Currentier alone, greatly reducing the number of design and verification processes. (Figure 1)

Figure 1. Current range of Currentier

Temperature Characteristics

Currentier has an internal memory to correct temperature characteristics so that there is no need to perform temperature correction using peripheral parts like shunt method, or to change and verify a compensation formula each time when resistance values change. Compared to competitors’ coreless current sensor, the compensation technology developed by AKM has achieved excellent temperature characteristics.

Figure 2. Temperature characteristics comparison between Currentier and competitor

Low Heat

Currentier has lower heat generation than other solutions, which can greatly reduce the man-hours for the heat dissipation design. As explained in #01, Figure 3 shows that Currentier is about 50°C lower than the shunt method and 20°C lower than other coreless current sensors.

Applied Current: 40A DC
Substrate: 70µm, 4 Layers
Thermal Image: 10 minutes after current applied
Upper Thermal Images: Red = 85°C, Blue = 25°C
Lower Thermal Images: Red = 55°C, Blue = 25°C

Figure 3. Heat generation comparison image of various current detection methods

'Currentier' series are open-type current sensor ICs 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.