Jtekt Corporation

Toshie Hibi

Hidenori Itamoto

Takashi Kageyama

Akihiro Tomita

Osamu Takahashi

Provided is a steering control unit for improving influence of fluctuations in an estimated electrical angle on steering feel. A steering control unit includes a microcomputer that performs sensorless control of the driving of a motor by using an estimated electrical angle estimated by calculation. The microcomputer calculates the estimated electrical angle from a value that is obtained by selectively accumulating a first additional angle or a second additional angle. The microcomputer adjusts a vibration component of fluctuations in the estimated electrical angle by varying the amount of change in the first additional angle and the second additional angle.

Steering control unit

Provided is a steering control apparatus in which the response of steering assistance to driver's steering can be improved during execution of rotation angle sensor-less control. When the rotation angle sensor-less control is executed and when an induced voltage value is equal to or lower than a threshold voltage, driving of a motor is controlled based on a second addition angle. The second addition angle is calculated such that values obtained by multiplying a first pre-addition angle calculated based on a steering torque and a second pre-addition angle calculated based on an induced voltage derivative by respective predetermined use ratios that are based on the induced voltage value are added together. By using the second addition angle, a more appropriate estimated electrical angle is calculated in response to a driver's steering situation.

Steering control apparatus

Provided is a steering control apparatus capable of executing driving assistance control even during rotation angle sensor-less control. When an induced voltage generated in a motor is equal to or lower than a threshold voltage at an early stage of execution of the rotation angle sensor-less control and when the driving assistance control is executed based on a command value from a higher-level control apparatus, a second pre-addition angle that is based on the command value is used as a second addition angle in place of a first pre-addition angle that is based on a steering torque. Therefore, even in a situation in which the steering torque is not detected due to, for example, execution of driving assistance, an estimated electrical angle of the motor is calculated by integrating the second addition angle. Then, driving of the motor is controlled based on the calculated estimated electrical angle.

A current command value calculation circuit includes an end abutment determination circuit and a guard processing circuit. When a decrease amount of an induced voltage value within a predetermined time is equal to or larger than a predetermined decrease amount in the state that a steering torque is equal to or larger than a predetermined torque, the end abutment determination circuit determines that the end abutment occurs. When a determination signal indicating that the end abutment state does not occur is input, the guard processing circuit outputs an elemental current command value directly as a q-axis current command value. When a determination signal indicating that the end abutment state occurs is input, the guard processing circuit outputs, as the q-axis current command value, a value obtained by limiting the elemental current command value so that its absolute value is equal to or lower than a predetermined limit current value.

A torque sensor includes a first resolver that outputs a signal corresponding to a rotation angle of a first rotor fitted on an outer periphery of a first rotary shaft, and a second resolver that outputs a signal corresponding to a rotation angle of a second rotor fitted on an outer periphery of a second rotary shaft coupled to the first rotary shaft via a torsion bar. The torque sensor detects a torque exerted on the first rotary shaft or the second rotary shaft based on the signals output from the first resolver and the second resolver. A first junction between the first rotary shaft and the first rotor, and a second junction between the second rotary shaft and the second rotor are formed so as to have different shapes or different sizes.

Growing community of inventors

Okazaki, Japan

Toshie Hibi