Apparatus and method of controlling an electric oil pump driving motor

An apparatus for controlling an electric oil pump driving motor in an oil pump system, the oil pump system comprising a mechanical oil pump that is driven by an engine to supply a hydraulic pressure, an electric oil pump that is driven by a sensorless electric motor to supply a hydraulic pressure, an oil supply changeover mechanism that selects oil supply from the mechanical oil pump when the engine is in a driving condition, and oil supply from the electric oil pump when the engine is in a stopped condition, and an automatic transmission control unit that generates a start command for the electric motor and oil supply information about the oil supply in the oil pump system when the engine is in the stopped condition, the apparatus comprising:

• a control command generating section that generates a sum signal indicating a sum of a first current command signal to determine torque for the electric motor and a second current command signal determined by a deviation in rotational speed of the electric motor, on the basis of the oil supply information from the automatic transmission control unit;
• a current control section that generates a third current command signal determined from a difference between the sum signal outputted from the control command generating section and a load current flowing in the electric motor;
• an electric motor control section that receives the third current command signal outputted from the current control section and executes vector control;
• and
• an electric power conversion section that is controlled by the electric motor control section so as to control an alternating current to be applied to the electric motor;
• wherein the control command generating section comprises a rotational speed limiting section to obtain the second current command signal,
• the rotational speed limiting section has a first upper limit value and a first lower limit value of the rotational speed of the electric motor,
• in a case where the rotational speed of the electric motor deviates from a first range defined between the first upper limit value and the first lower limit value, the rotational speed limiting section generates the second current command signal acting for controlling the rotational speed of the electric motor to suppress deviation of the rotational speed of the electric motor from the first range, and
• in a case where deviation of the rotational speed of the electric motor from the first range is continued for a predetermined time or more, the rotational speed limiting section sets a second range defined between a second upper limit value and a second lower limit value of the rotational speed of the electric motor which are respectively displaced from the first upper limit value and the first lower limit value in a direction in which the deviation of the rotational speed of the electric motor from the first range is continued.