Vehicle body insulation resistance test method

Abstract

The invention provides a method for testing the insulation resistance of a vehicle body, comprising the following steps: (1) generating a low-frequency AC signal and injecting the low-frequency AC signal into the vehicle body; (2) obtaining U through a first-level measurement circuit 9_30 ; 9‑30 The average value in one cycle reflects the unbalanced condition of the positive and negative poles to the body resistance; the variation dU in half a cycle 9_30 Participate in the calculation of the resistance value of the second-level measurement as the fluctuation parameter of the bus voltage; (3) obtain the AC voltage amplitude U through the second-level measurement circuit 9_25 , a single insulation resistance R = F (U 9_25 )*W, W is the weight, W=f(dU 9_30 ); (4) Take the average value of each measurement to obtain the vehicle body insulation resistance Ravr=(w1*R1+w2*R2+.....Wn*Rn) / (w1+w2+....Wn). On the basis of the original low-frequency signal injection method, the present invention correlates the weight of the weighted filter when calculating the insulation resistance with the variation of the DC bus voltage fluctuation, the weight is small when the bus voltage fluctuates greatly, and the weight is large when the bus voltage fluctuates small, thus Make the test results tend to be stable and reliable.

Description

technical field [0001] The invention belongs to the field of electric vehicles, and more specifically relates to a method for testing the insulation resistance of a vehicle body. Background technique [0002] With the increasing requirements of human society for environmental protection, electric vehicles have begun to be paid attention to and developed all over the world. Various technologies related to electric vehicles have also been developed accordingly. As my country is a big oil importing country, the development of electric vehicles has more strategic significance for energy security. As a relatively backward country in the automobile industry, electric vehicles also carry the country's expectation of overtaking in curves in the automobile industry. As one of the electric vehicle technologies, insulation monitoring has been developed in many ways. The international standard for electric vehicles stipulates that the insulation resistance value divided by the nomina...

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Problems solved by technology

[0012] Aiming at the defects of the prior art, the object of the present invention is to provide a method for measuring the insulation resistance of the vehicle body, aiming to solve the problem that the bus voltage of the change will be different from that of the original low-frequency signal injection method in the prior art when the bus voltage changes. The injected low-frequency signals are superimposed, which affects the measurement effect

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