Patent ID: 8766653
Filing Date: 2014-07-01
Classification: G01R

Abstract:
1. A measuring device for measuring insulation resistance of an electric vehicle, the electric vehicle including a high voltage system and a low voltage system, a high potential insulation resistance being a resistance between a high potential side of the high voltage system and a ground side of the low voltage system, a low potential insulation resistance being a resistance between a low potential side of the high voltage system and the ground side of the low voltage system, said measuring device comprising: a measuring unit including a first tap, a second tap, a switch, and a measuring resistor, said first tap to be electrically coupled to the high potential side of the high voltage system, said second tap to be electrically coupled to the ground side of the low voltage system, said switch and said measuring resistor being connected in series between said first tap and said second tap; a voltage detecting unit, for detecting a voltage formed between said first tap and said second tap; and a control unit coupled to said switch and said voltage detecting unit, said control unit including a control module that is operable for controlling ON and OFF states of said switch, and that stores a highest voltage value of the high potential side, a resistance value of said measuring resistor, a first function, and a second function, wherein: said control module acquires a first voltage via said voltage detecting unit when said switch is in the OFF state, and acquires a second voltage via said voltage detecting unit when said switch is in the ON state; each of the first voltage and the second voltage is related to the voltage between said first tap and said second tap; each of said first function and said second function is a function of the highest voltage value, the first voltage, and the second voltage; and said control module is configured to determine the high potential insulation resistance from a product of the resistance value of said measuring resistor and said first function, and to determine the low potential insulation resistance from a product of the resistance value of said measuring resistor and said second function.