Elevator frequency converter bus capacitor capacity detection method and system and diagnosis early warning method and system

The invention provides an elevator frequency converter bus capacitor capacity detection method and system and a diagnosis early warning method and system. The detection method comprises the steps of controlling an elevator to ascend on floors in a no-load mode, wherein the number of ascending floors is at least the minimum number of floors reaching the nominal speed of the elevator; obtaining the capacitor voltage data u1 and u2 of a frequency converter bus capacitor at the moment t1 and the moment t2 in the ascending period of the elevator; detecting the car movement distance data h1 and h2 at the moment t1 and the moment t2 in the ascending process of the elevator; calculating the capacitor capacity C of the frequency converter bus capacitor according to the following formula: C=[2*k*m*g*(h2-h1)*eta-2*P*(t2-t1)]/(u2 -u1 ). The technical scheme can be applied to frequency convertor products of existing hardware systems of elevators, and low-cost and accurate detection on the capacity of the frequency converter bus capacitor can be achieved without additionally arranging any hardware. Meanwhile, according to the diagnosis early warning method and system achieved based on the elevator frequency converter bus capacitor capacity detection method and system, low-cost and accurate diagnosis early warning on the capacity of the frequency converter bus capacitor can be achieved, and maintenance, detection and replacement are convenient.