On-line insulated monitoring method for high voltage of electromobile

Abstract

The invention relates to an on-line insulated monitoring method for high voltage of an electromobile, which comprises the following steps: 1) at a static state, switch tubes of an inverter are all controlled in an off-state firstly, ground insulation resistances of anode and cathode buses of a direct-current side are detected; 2) an upper or lower switch tube of a certain phase of bridge arm of the inverter is selectively closed to work out the ground insulation resistance of the phase of bus at an alternating-current side; 3) at a dynamic state, the ratios of the voltage to ground to the bus voltage before and after a known-resistance standard resistor is merged between the anode bus and an electromobile body are monitored to respectively extract direct-current components in a filtering method, so that the parallel value of all insulation resistors at the direct-current side and the alternating-current side at the dynamic state is worked out; and the ground insulation fault of any one or a plurality of buses can be obtained through monitoring the parallel value. Compared with the prior art, the method disclosed by the invention has the advantages that the monitoring range at an insulated state is expanded, the insulated state at the direct-current side and the insulated state at the alternating-current side can both be monitored no matter at the static state or at the dynamic state and the like.

Description

technical field [0001] The invention relates to a detection technology for an electric vehicle, in particular to a method for monitoring the high-voltage online insulation of an electric vehicle. Background technique [0002] In the existing electric vehicle insulation monitoring methods, most of the standard resistors with known resistance are incorporated between the positive and negative busbars and the body ground, and whether they are connected is controlled by a switch. By detecting the value of the voltage of the positive and negative busbars to the ground before and after the access resistance, the insulation resistance of the positive and negative busbars to the ground can be calculated. Because this method generally does not consider the change of insulation resistance after the introduction of the motor and controller, it cannot measure the insulation resistance value of the three-phase AC measurement of the motor. And in practical application, it is found that t...

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Problems solved by technology

Because this method generally does not consider the change of insulation resistance after the introduction of the motor and controller, it cannot measure the insulation resistance value of the three-phase AC measurement of the motor.

And in practical application, it is found that this method can obtain better results when the static measurement is performed before the driving motor is enabled. When the dynamic measurement is performed after the driving motor is enabled, the insulation resistance measurement value is unstable or inaccurate.

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