Inverter control circuit of motor-driven blower for electric vacuum cleaner, drive control circuit using the same, and electric vacuum cleaner using the drive control circuit

An electric vacuum cleaner of the present invention includes a housing having a fluid suction port and a motor-driven blower accommodated in the housing so as to be capable of sucking a fluid from the fluid suction port, to AC-drive the motor-driven blower by an inverter circuit. The inverter circuit has a plurality of switching elements and AC-drives the motor-driven blower according to periodical switching between these switching elements, based on detected value of physical quantity detecting means which detects physical quantities related to the electric vacuum cleaner. The switching elements of the inverter circuit are driven by a drive circuit which drives the switching elements according to input pulse signal. The pulse signal input into the drive circuit is generated by an inverter control circuit for use in the motor-driven blower for the electric vacuum cleaner, and be input into the drive circuit. The inverter control circuit includes means for setting a period in which a rotation velocity of the motor-driven blower is calculated, means for performing interrupt processing including a calculation of the rotation velocity of the motor-driven blower based on the detected value of the physical quantity detecting means, and means for generating the pulse signal according to a carrier wave having a period shorter than a period in which the rotation velocity of the motor-driven blower is calculated, and longer than the time required to perform interrupt processing including the calculation of the rotation velocity of the motor-drive blower, and inputting the pulse signal into the drive circuit. Thus, it is possible to control the rotation velocity of the motor excellent in response. Therefore, even if the electric vacuum cleaner being in use in the highest operation mode, for example, undergoes a sudden fluid load variation and the rotation velocity of the rotor of the motor abruptly changes due to the fluid load variation, the width of the pulse outputted from the inverter controller changes quickly and the rotation velocity of the rotor is promptly returned to a desired rotation velocity. Therefore, the time spent on an unpleasant sound produced due to the change in rotation velocity becomes short, and discomfort given to a user can be lessened.