| CPC G01R 31/14 (2013.01) [G01R 31/006 (2013.01)] | 20 Claims |

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1. An insulation resistor detection circuit, comprising a state control unit, a first voltage division branch, a second voltage division branch, a processor, a to-be-detected apparatus, a first capacitor, a second capacitor, and a ground, wherein
the state control unit is connected between a positive electrode and a negative electrode of a power supply of the to-be-detected apparatus; the state control unit is configured to switch between a first state and a second state in response to control from the processor; when the state control unit is in the first state, the first capacitor is configured to charge and the second capacitor is configured to discharge electricity; when the state control unit is in the second state, the first capacitor is configured to discharge electricity and the second capacitor is configured to charge; the first capacitor is a capacitor between the positive electrode of the power supply and the ground; and the second capacitor is a capacitor between the negative electrode of the power supply and the ground;
the first voltage division branch is connected in parallel to the first capacitor, and is configured to divide voltages at two ends of the first capacitor to obtain a first voltage waveform;
the second voltage division branch is connected in parallel to the second capacitor, and is configured to divide voltages at two ends of the second capacitor to obtain a second voltage waveform; and
the processor is separately connected to the state control unit, the first voltage division branch, and the second voltage division branch, and the processor is configured to: calculate, based on the first voltage waveform obtained at a current moment, voltage feature values of the first capacitor at different moments in a specified duration before the current moment; calculate, based on the second voltage waveform obtained at the current moment, voltage feature values of the second capacitor at different moments in the specified duration before the current moment; determine a next switching moment based at least on the voltage feature values of the first capacitor at the different moments or the voltage feature values of the second capacitor at the different moments; and control, when the next switching moment arrives, the state control unit to switch a state.
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