Secure on-board system for charging the battery of a motor vehicle from a power supply network

A secure system for charging the battery of a motor vehicle from a power supply network, the system being on board the motor vehicle and comprising:

• means for measuring frequency of the power supply network;
• means for injecting current pulses into the power supply network;
• means for measuring voltage between ground and a neutral of the power supply network;
• an analog filter for filtering the measured voltages at high frequencies;
• a digital filter for filtering the analog-filtered voltages at low frequencies;
• and
• means for determining resistance between the ground and the neutral of the power supply network on the basis of the digitally filtered voltages and an amplitude of the current pulses;
• wherein the digital filter comprises a mean value filter determining a mean value on the basis of N voltage measurements spaced apart by a time interval T+T/N, with T the period of the power supply network determined by the means for measuring the frequency of the power supply network.

A secure method for charging the battery of a motor vehicle from a power supply network estimating resistance between the ground and a neutral of the power supply network,

• wherein frequency of the power supply network is measured;
• current pulses are injected into the power supply network;
• measurements of the voltage between the ground and the neutral of the power supply network are performed in response to each pulse;
• the measured voltages are analog-filtered at high frequencies;
• the analog-filtered voltages are filtered digitally at low frequencies;
• and
• resistance between the ground and the neutral is determined on the basis of the digitally filtered voltages and an amplitude of the current pulses;
• wherein the digital filtering comprises determining a mean value on the basis of N voltage measurements spaced apart by a time interval T+T/N, with T the period of the power supply network determined on the basis of the measurement of the frequency of the power supply network.