Battery leakage detection circuit for electric vehicle and leakage detection method for electric vehicle

摘要

The present provides a leakage detection circuit for an electric vehicle, and so on, capable of calculating a leakage resistance. The leakage detection circuit for an electric vehicle detects a current I_g11(t₁) that flows in leakage resistances R_a and R_b when one leakage detection switch SW₁ is closed at t₁ and the other leakage detection switch SW₂ is opened, and detects a current I_g12(t₂) when the switch SW₁ is opened at t₂ and the switch SW₂ is closed. In addition, the circuit detects voltages V_l11(t₁, t₂) and V_l12(t₁, t₂) of portions where these leakage detection resistances R_a are connected. A combined value R_l of the leakage resistances is calculated by a leakage calculator based on the following equation 34 $\begin{array}{cc}{R}_l=\frac{R_a}{\frac{V_{\mathrm{l12}}\left(t_2\right)}{V_{\mathrm{g11}}\left(t_2\right)-V_{\mathrm{g12}}\left(t_2\right)}-\frac{V_{\mathrm{l11}}\left(t_1\right)}{V_{\mathrm{g11}}\left(t_1\right)-V_{\mathrm{g12}}\left(t_1\right)}}-\left(R_a+R_b\right).& \mathrm{Equation}34\end{array}$