New Coreless Current Sensor Shrinks EV Charger

Asahi Kasei Microdevices Corporation (AKM) has started mass production of the CZ39 Series of coreless current sensors. Particularly, the CZ39 device family perfectly suits electric vehicle (EV) applications due to its 100ns response time, low heat generation, and noise immunity. These properties are highly compatible with the silicon carbide (SiC)- and gallium nitride (GaN)- based power devices favored by OEMs for their reduced form factor and high efficiency. As such, the CZ39 Series allows for the implementation of substantially smaller, lighter, and more accurate on-board charging systems for EVs.

Asahi Kasei Microdevices’ CZ39 Series coreless current sensor (Photo: Business Wire)

Fast Current Measurements

Mainly, the CZ39 Series features a high-sensitivity compound Hall element that enables a response time of 100 ns. Accordingly, it makes it possible for current measurements to keep up with the high switching speed of SiC- and GaN-based power solutions. This allows OEMs to take advantage of those devices’ smaller size. Thus, it reduces the weight of on-board charging systems to extend cruising range. Moreover, the CZ39 Series’ ability to quickly signal the system to interrupt current flow during an overcurrent condition also makes for a robust electronic fuse, or e-fuse, implementation.

Mechanism of current measurement (Graphic: Business Wire)

Reduced Heat Generation

Additionally, AKM has developed a unique package for the CZ39 Series. Specifically, it achieves a primary conductor resistance of only 0.3mΩ. Even under continuous 40Arms current flow at an ambient temperature of 125ºC, heat generation is minimal. Accordingly, this greatly reduces the need for bulky thermal management measures. Also, the structure of the package provides sufficient creepage and clearance distances for use in applications above 650V.

Enhanced Noise Immunity

Mainly, combining high voltage and high-speed switching in SiC- and GaN-based systems presents a challenge in electrical noise mitigation. The CZ39 family is exceptionally resilient to such conditions. Specifically, it ensures continuous and highly accurate current detection even in noisy environments.

Evolution of Asahi Kasei’s current sensors (Graphic: Business Wire)