Motor drive device capable of informing malfunction in operation of fan, and method thereof

Abstract

A motor drive device can improve the accuracy of detection of malfunction in a fan. The motor drive device includes a fan, a fan controller for controlling the fan, a rotation speed detecting part for detecting the rotation speed of the fan, a relationship acquiring part for acquiring a relationship between a time elapsed from a time point, at which the fan controller changes the rotation speed, and the rotation speed detected by the rotation speed detecting part, a malfunction determining part for determining whether the relationship acquired by the relationship acquiring part is different from a predetermined standard, and a malfunction signal generating part for generating a signal representing the occurrence of malfunction in the fan, when it is determined that the relationship is different from the standard.

1 . A motor drive device comprising:
 a fan;   a fan controller which controls the fan;   a rotation speed detecting part which detects a rotation speed of the fan;   a relationship acquiring part which acquires a relationship between a time elapsed from a time point, at which the fan controller changes the rotation speed, and the rotation speed detected by the rotation speed detecting part;   a malfunction determining part which determines whether the relationship acquired by the relationship acquiring part is different from a predetermined standard; and   a malfunction signal generating part which generates a signal indicating that a malfunction occurs in the fan when the malfunction determining part determines that the relationship is different from the standard.   
     
     
         2 . The motor drive device according to  claim 1 , wherein the relationship acquiring part acquires, as the relationship, an amount of change in the rotation speed detected by the rotation speed detecting part within a time period until a predetermined time elapses from the time point at which the fan controller sends to the fan a command for changing the rotation speed,
 wherein the malfunction determining part determines that the relationship is different from the standard when the acquired amount of change is greater or smaller than a predetermined threshold value.   
     
     
         3 . The motor drive device according to  claim 1 , wherein the relationship acquiring part acquires, as the relationship, a ratio of an amount of change in the rotation speed detected by the rotation speed detecting part within a time period until a predetermined time elapses from the time point at which the fan controller sends to the fan a command for changing the rotation speed, to the standard,
 wherein the malfunction determining part determines that the relationship is different from the standard when the ratio is greater or smaller than a predetermined threshold value.   
     
     
         4 . The motor drive device according to  claim 1 , wherein the relationship acquiring part acquires, as the relationship, a time until the rotation speed detected by the rotation speed detecting part changes from a first rotation speed to a second rotation speed different from the first rotation speed when the fan controller sends to the fan a command for changing the rotation speed from the first rotation speed to the second rotation speed,
 wherein the malfunction determining part determines that the relationship is different from the standard when the acquired time is greater or smaller than a predetermined threshold value.   
     
     
         5 . The motor drive device according to  claim 1 , further comprising a timer which measures the time from the time point at which the fan controller changes the rotation speed. 
     
     
         6 . The motor drive device according to  claim 1 , further comprising a storage which stores the rotation speed detected by the rotation speed detecting part or the time from the time point at which the fan controller changes the rotation speed. 
     
     
         7 . The motor drive device according to  claim 1 , further comprising an alarm output part which receives the signal and outputs an alarm to a user. 
     
     
         8 . A method of notifying a user of an occurrence of a malfunction in a fan provided at a motor drive device, comprising:
 changing a rotation speed of the fan;   detecting the rotation speed when changing the rotation speed;   acquiring a relationship between a time elapsed from a time point, at which the rotation speed is changed, and the detected rotation speed;   determining whether the acquired relationship is different from a predetermined standard; and   notifying to a user that a malfunction occurs in the fan when determining that the relationship is different from the standard.