Electric charging system and electric charger

An electric charging system in which an electric charger and an electric vehicle are connected by a charging cable, and an electric storage device installed on the electric vehicle is charged, the electric charging system comprising:

• a first reference setting unit for setting a reference point for supplied voltage data calculated by subjecting a supplied voltage at the electric charger side to predetermined filter processing, the reference point being set on the basis of a variation rate of the supplied voltage data;
• a second reference setting unit for setting a reference point for received voltage data calculated by subjecting a received voltage at the electric vehicle side to predetermined filter processing, the reference point being set on the basis of a variation rate of the received voltage data;
• a data synchronization unit for synchronizing the supplied voltage data and the received voltage data on the basis of the reference points of the supplied voltage data and the received voltage data;
• a voltage difference calculation unit for comparing the synchronized supplied voltage data and received voltage data and calculates a voltage difference between the supplied voltage and the received voltage;
• a resistance calculation unit for calculating a power supply resistance of the charging cable on the basis of the voltage difference between the supplied voltage and the received voltage;
• a drop amount calculation unit for calculating a voltage drop amount in the charging cable on the basis of the power supply resistance of the charging cable and a supplied current on the electric charger side or a received current on the electric vehicle side;
• and
• a charging determination unit for comparing a determination voltage updated on the basis of the voltage drop amount with the supplied voltage on the electric charger side and determines a state of charge of the electric storage device.