New leakage current sensor for electric vehicle charging stations

22-03-2021 | LEM | Automotive Technologies

LEM has launched the CDSR, a new leakage current sensor based on its open-loop Fluxgate Technology. The CDSR is innovative, remarkably compact and safe, enabling manufacturers to optimise the electronic design of their charger products.


Since 2016, IEC standards and more particularly IEC 62955/IEC 62752, need the detection of a Direct Leakage current at 6mA DC to avoid the home RCD Type A being ineffective. This effect, called 'the blinding effect', arises when an EV develops an insulation fault.


EV architecture combines a battery pack powered by DC, which can generate a leakage current that can deactivate a home RCD. To protect the RCD and evade the requirement to install an RCD type B in the electrical panel of home EV owners, these chargers incorporate a device to identify the DC leakage current. This detection is the role of the CDSR.


The device has been produced to satisfy market demand for a residential and commercial charging station, providing a version for single-phase architecture and another for three-phase topology. With a maximum current per phase of 32A RMS, the device can be combined into AC chargers from 3.7kW to 22kW.


Following the trend towards digital electronics, the device offers not only an analog communication output but also an SPI, facilitating simple interfacing of hardware. It operates from a +3.3VDC supply and has a typical current consumption of only 50mA when measuring 150mA as a maximum primary residual current.


Extremely robust, the device can function inside all EV chargers. It provides an operating temperature between -40C to 85C, can withstand acceleration forces up to 10G while sustaining nominal performance, and has a very high insulation level between its primary and measurement circuits due to long creepage and clearance distances (13.2mm).

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