Patent ID: 11894723
Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC B  H  Y | IPC B  H

Claim 0:
1. An electric tool, comprising:
an electric motor including a permanent magnet and a coil; and
a control unit configured to perform control on operation of the electric motor,
the control performed by the control unit including field weakening control by which the control unit causes a flux-weakening current to flow through the coil, the flux-weakening current being a current that generates, in the coil, a magnetic flux that weakens a magnetic flux of the permanent magnet
the control unit having a function of changing a magnitude of the flux-weakening current in the field weakening control,
the control unit being configured to, when a predetermined increase condition is satisfied, perform gradual-increase control of increasing an absolute value of the flux-weakening current over time in the field weakening control,
the control unit being configured to, when a predetermined decrease condition is satisfied, perform gradual-decrease control of decreasing the absolute value of the flux-weakening current over time in the field weakening control, the predetermined decrease condition being different from the predetermined increase condition, a rate of change of the flux-weakening current in the gradual-decrease control being less than a rate of change of the flux-weakening current in the gradual-increase control.