Self-checking device and method for braking device and elevator system

A self-checking device for a braking device, the braking device comprising a static plate, a movable plate movably connected to the static plate, and a friction lining provided on a side of the movable plate facing away from the static plate, and an electromagnetic brake coil moving the movable plate relative to the static plate, wherein, the self-checking device comprises:

• an inductance testing module configured to measure an electromagnetic brake coil inductance L of the braking device;
• and
• a processing module electrically connected to the inductance testing module, and storing a mathematical model of an air gap a between the movable plate and the static plate with respect to the electromagnetic brake coil inductance L in a brake state;
• wherein, the processing module is configured to execute a checking mode in the brake state of the braking device, and in the checking mode, the processing module receives a current inductance Lo measured by the inductance testing module,
• calculates a current air gap ao based on the mathematical model stored, and determines a wear degree of the friction lining based on the current air gap ao calculated;
• wherein the mathematical model is a=f(L), and the mathematical model is trained by at least two sets of data of corresponding air gaps and electromagnetic brake coil inductances (allla2, L2) received in a testing mode of the braking device.