Abstract: A power converter a controller that includes an instruction calculator calculating a first voltage instruction value that is applied to a first winding group, for example. An application voltage to the first winding group is controlled, for example, in a first period so that a first neutral point voltage shifts below a center-of-output value of an outputtable range is outputted, and a second neutral point voltage shifts above the center-of-output value of the outputtable range. The instruction calculator calculates the first instruction value for enabling a switching between the periods, after a lapse of a switch period that is variably calculated based on a preset physical quantity. In such manner, a ripple of a torque or an electric current accompanying the switching between the periods is reduced.

Abstract: A brushless motor for an electric power steering device that assists a steering operation includes: a stator having a plurality of winding sets for a plurality of systems respectively; and a rotator having a ferrite magnet. In the motor, a maximum current flowing without any demagnetization at high temperature is large. Hence, the torque of the motor is easily ensured at high temperature. In particular, when a failure occurs in one system, it is easy to ensure the torque of the normal system even at high temperature.

Abstract: An apparatus for estimating a transfer function of at target object having divided systems is disclosed. The apparatus acquires an estimation equation to estimate the transfer function of the target object, and determines, for each arithmetic operation in the estimation equation, whether the arithmetic operation is an addition or a multiplication. For the multiplication, the apparatus performs the multiplication of frequency response characteristics in the frequency domain. For addition, the apparatus converts the frequency response characteristics into time response characteristics, performs the addition of the time response characteristics in the time domain, and reconverts a result of the addition into the frequency domain.

Abstract: An apparatus for estimating a transfer function of at target object having divided systems is disclosed. The apparatus acquires an estimation equation to estimate the transfer function of the target object, and determines, for each arithmetic operation in the estimation equation, whether the arithmetic operation is an addition or a multiplication. For the multiplication, the apparatus performs the multiplication of frequency response characteristics in the frequency domain. For addition, the apparatus converts the frequency response characteristics into time response characteristics, performs the addition of the time response characteristics in the time domain, and reconverts a result of the addition into the frequency domain.