Monitoring the insulation in electric vehicles

摘要

The device (25) for monitoring and signalling the absence of electrical insulation between traction unit and bodywork in electric vehicles comprises a generator (47) of AC voltage to be applied to the vehicle's traction and supply circuit by means of a de-coupling capacitor (38), to eliminate the effects of the DC voltage of the battery. A shunt resistor (37) is arranged in series with the voltage generator, the voltage of which resistor is measured as an indicator of the alternating current originated by the AC voltage applied in the presence of leakages with respect to the bodywork which close the circuit comprising the voltage generator and the shunt resistor. From the measurement of the leakage current, which is proportional to the extent of the leakages present in the circuit, it is possible to detect the presence of leakages and of short-circuits with respect to the bodywork and generate an appropriate signal for the driver. <IMAGE>