GB 18384-2020绝缘电阻计算公式研究及替代方法

Study on Insulation Resistance Calculation Formula and Alternative Methods in GB 18384-2020

本文根据电动汽车有源电路绝缘电阻测量原理推导出绝缘电阻计算公式,当对公式参数进行适当简化时,就得出了与GB 18384-2020标准相同的绝缘电阻计算公式。然而在实践中,本文发现公式中的某些参数发生的微小变化会导致计算结果的极大不稳定,进而分析了其可能的影响因素。对此,本文推荐使用“并接电阻法”求解绝缘电阻,其核心做法就是先对被测电路进行改造:在被测电路中并入一对至少小于电压表内阻2个数量级的等值电阻,通过相关公式计算出被测电路绝缘电阻与并入电阻的并联值,再通过电阻并联公式就可以得出被测电路的绝缘电阻值。

According to the principle of insulation resistance measurement for active circuit of electric vehicle, this paper deduces the calculation formula of insulation resistance. When the formula parameters are properly simplifi ed, the same formula of insulation resistance calculation as that in GB 18384-2020 is obtained. However, in practice, this paper fi nds that the small changes of some parameters in the formula will lead to great instability of the calculation results, and analyzes the possible infl uencing factors of it. In this regard, this paper recommends the use of the "parallel resistance method" to solve the insulation resistance. The core method is to transform the circuit fi rstly: a pair of at least two orders of magnitude smaller than the internal resistance of the voltmeter is incorporated into the circuit, the parallel value of the insulation resistance of the circuit and the incorporated resistance is calculated with the relevant formula, and the insulation resistance value of the circuit is obtained through the resistance parallel formula.