Motor controller and electric power steering system

A motor controller for driving a motor comprising:

• a control unit for determining a level of a command voltage used for driving the motor;
• a motor drive unit for driving the motor by use of a voltage having the level determined by the control unit;
• a current detection unit for detecting an electric current flowing into the motor;
• and
• a parameter computing section which determines, from a current value detected by the current detection unit, a parameter used when the level of the command voltage is determined,
• wherein the control unit further includes
• a feedback control section which subjects a difference between the command current value and the current value detected by the current detection unit to proportional integration, thereby determining a level of the command voltage;
• and
• a command voltage selection section for outputting, in a switching manner, the level of the command voltage determined by the feedback control section and the level of the command voltage determined by the open loop control section.

A motor controller for driving a motor comprising:

• a control unit for determining a level of a command voltage used for driving the motor;
• a motor drive unit for driving the motor by use of a voltage having the level determined by the control unit;
• a current detection unit for detecting an electric current flowing into the motor;
• and
• a parameter computing section which determines, from a current value detected by the current detection unit, a parameter used when the level of the command voltage is determined, wherein the parameter computing section determines, from the current value detected by the current detection unit, a number of armature winding flux linkages included in the motor circuit equation,
• wherein the control unit comprises
• a dimension conversion section for computing a current torque constant by means of dimensionally converting the number of armature winding flux linkages determined by the parameter computing section;
• and
• a command current value computing section that receives the current torque constant from the dimensional conversion section and that determines a command current value showing an amount of electric current supplied to the motor equivalent to a value determined by dividing a torque, which serves as a target torque to arise in the motor, by the current torque constant.

A motor controller for driving a motor comprising:

• a control unit for determining a level of a command voltage used for driving the motor;
• a motor drive unit for driving the motor by use of a voltage having the level determined by the control unit;
• a current detection unit for detecting an electric current flowing into the motor;
• and
• a parameter computing section which determines, from a current value detected by the current detection unit, a parameter used when the level of the command voltage is determined,
• further comprising:
• a voltage detection unit for detecting a voltage corresponding to the voltage applied to the motor, wherein
• the motor drive unit comprises
• a switching circuit that has a plurality of switching elements and that supplies the motor with a current as a result of the plurality of switching elements being turning on or off;
• and
• a motor voltage determination section that turns on or off the plurality of switching elements by use of a voltage of the level determined by the control unit and a voltage detected by the voltage detection unit, wherein
• the voltage detection unit measures a voltage between a point on a path from one end of the switching circuit connected to a positive side of a power source for driving the motor to the positive side of the power source and another point on a path from the other end of the switching circuit, which is connected to the negative side of the power source, to the negative side of the power source.