Nsk Corporation

Nec Corporation

Nsk Steering & Control, Inc.

Hideki Sawada

Takayoshi Sugawara

Ryo Minaki

Hiroaki Takase

Mitsumasa Tanaka

Masaru Terashima

Takashi Sameshima

Keita Yoshida

Takuya Masuko

Takashi Samejima

Tomoki Fukuda

Hidetaka Koinuma

Yukie Fujiwara

An electric power steering device including: a motor configured to generate a steering assist force; a current command value calculation unit configured to calculate a current command value to control driving current of the motor; a current control unit configured to output a first voltage command value, based on current deviation of a measured value of the driving current to the current command value; a first gain setting unit configured to set a first gain depending on rotational velocity of the motor; a disturbance voltage suppression unit configured to calculate a third voltage command value by adding output from a first delay element to a second voltage command value obtained by limiting the first voltage command value by the first gain and input the third voltage command value to the first delay element; and a driving circuit configured to drive the motor, based on the third voltage command value.

Electric power steering device

The motor control device includes: a d-axis current command value calculation unit configured to set a first d-axis current command value for field-weakening; a first current limiting unit configured to calculate a first q-axis current command value by limiting a base q-axis current command value as to satisfy a condition of motor rated current; a second current limiting unit configured to calculate a second d-axis current command value and a second q-axis current command value by limiting the first d-axis current command value and the first q-axis current command value, respectively to satisfy and not exceed an allowable upper limit battery current; voltage command value calculation units configured to calculate voltage command values, based on the second d-axis current command value and the second q-axis current command value; and a voltage limiting unit configured to prevent saturation of a duty ratio by limiting the voltage command values.

Motor control device and electric power steering device

An electric power steering apparatus including a torque sensor to detect a steering torque and a motor control unit to control a motor that applies an assist torque to a steering system of a vehicle, including: a function to switch a control system of the motor between a torque control system to control a motor output torque and a position/speed control system to control a steering angle of a steering in accordance with a predetermined switching trigger. The fade processing time from the torque control system to the position/speed control system and the fade processing time from the position/speed control system to the torque control system are individually set.

Electric power steering apparatus

[Problem] An object of the present invention is to provide a vector control type motor control unit that compensates a dead time of an inverter without a tuning operation, improves a distortion of a current waveform and responsibility of the current control, and suppresses sound, vibration and a torque ripple. [Means for Solving the Problem] The present invention is the vector control type motor control unit that calculates a q-axis control assist command value, calculates dq-axes current command values from the control assist command value, converts the dq-axes current command values into 3-phase duty command values, and drives and controls a 3-phase brushless motor by a PWM-controlled inverter, wherein dead time compensation of the inverter is performed by calculating 3-phase dead time reference compensation values based on a motor rotational angle, calculating 3-phase dead time compensation values by temperature-correcting the 3-phase dead time reference compensation values, and adding the 3-phase dead time compensation values to 3-phase voltage command values after performing dq-axes space vector modulation.

Motor control unit and electric power steering apparatus equipped with the same

An electric power steering apparatus includes a function to switch a control system of the motor between a torque control system of a torque system to control a motor output torque and a position and speed control system of a steering angle system to control a steering angle of a steering in accordance with an ON/OFF of a post-diagnosis automatic steering command being a judgment result of an automatic steering execution judging section; and a characteristic calculating section to calculate a fade gain signal Fthat applies a first fade characteristic of the torque system, a fade gain signal Fthat applies a second fade characteristic of the steering angle system, and a fade gain signal Fthat applies a third fade characteristic of the steering angle speed, sensitive to the steering torque.

A vector-control type motor control unit that calculates dq-axes control assist command values, calculates dq-axes current command values from the dq-axes control assist command values, converts the dq-axes current command values into 3-phase duty command values, and drives and controls a 3-phase brushless motor by an inverter of a PWM control, wherein a dead time compensation of the inverter is performed by calculating 3-phase dead time reference compensation values based on a motor rotational angle which is phase-corrected by using the dq-axes current command values, calculating dead time compensation values by processing the 3-phase dead time reference compensation values by a gain and a sign, and adding the dead time compensation values to dq-axes voltage command values or 3-phase voltage command values.

An electric power steering system is provided that is capable of performing assist control in which a change in a steering feel is reduced. The electric power steering system includes a current command value calculating unit configured to output a current command value Iref1 in accordance with steering torque and a vehicle speed on the basis of an assist map. The current command value calculating unit includes a vibration component reducing section configured to reduce a vibration component resulting from vibrations for warning that have been transmitted to a steering wheel and included in the steering torque.

Electric power steering system

An electric power steering apparatus of a vector control system that drives and controls a motor by an inverter and applies an assist torque to a steering system of a vehicle, including the first compensation function to perform a dead time (DT) compensation based on respective phase motor terminal voltages and respective phase duty command values, the second compensation function to perform a DT compensation based on steering assist command values, the third compensation function to perform the DT compensation based on dq-axis current command values, and a temperature detecting section to detect temperature of ECU, wherein the correction of the DT compensation is performed based on the temperature, wherein switches of the compensation functions are performed by using a conditional branch due to software and a gradual-changing switch, wherein the dq-axis DT compensation values after the conditional branch and the gradual-changing switch are performed are calculated, and wherein the dq-axis voltage command values are compensated by the dq-axis DT compensation values.

An electric power steering apparatus that drives and controls a motor which applies an assist torque to a steering system of a vehicle and has a function switching between an assist mode and an automatic mode, including a torsion bar torsional angle calculating section to calculate a torsion bar torsional angle based on a torque information, an output-side column shaft relative angle generating section to output an output-side relative angle from an electrical angle signal of the motor, an actual handle angle calculating section to calculate an actual handle angle based on the torsion bar torsional angle and the output-side relative angle, a resonance filter to obtain an estimated handle angle in a hands-off state from the output-side relative angle, and a hands-on/off judging section to judge a hands-on state when a time that a deviation angle between the actual handle angle and the estimated handle angle is equal to or more than a predetermined angle is continued for the predetermined time or more.

An electric power steering apparatus of a vector control system that compensates a dead time of an inverter without tuning operation, improves a distortion of a current waveform and a responsibility of a current control, and suppresses a steering sound, a vibration and a ripple. The apparatus converts dq-axes current command values calculated based on at least a steering torque into 3-phase voltage command values, converts the 3-phase voltage command values into duty command values, driving-controls a 3-phase brushless motor by an inverter of a PWM control, and applies an assist torque to a steering system of a vehicle, wherein 3-phase detection voltages are estimated based on 3-phase motor terminal voltages, wherein loss voltages due to a dead time of the inverter are estimated from differences between 3-phase command voltages calculated from the duty command values and the 3-phase detection voltages, and wherein a dead time compensation of the inverter is performed by feeding-back dead time compensation values obtained by compensating the loss voltages to the 3-phase voltage command values.

An electric power steering apparatus compensates a dead time of an inverter without tuning operation, improves distortion of a current waveform and responsibility of a current control, and suppresses sound, vibration and ripple. The apparatus calculates dq-axes steering-assist command values based on at least a steering torque, calculates dq-axes current command values from the dq-axes steering-assist command values, converts the dq-axes current command values into 3-phase duty command values, driving-controls a 3-phase brushless motor by an inverter of a PWM control, and applies an assist torque to a steering system of a vehicle. Dead time reference compensation values are calculated based on a motor rotational angle. Dead time compensation of the inverter adds dead time compensation values in which the dead time reference compensation values are processed by using a gain, a sign and the like, to dq-axes voltage command values or to 3-phase voltage command values.

An electric power steering apparatus of vector control system that calculates steering assist command values of dq axes based on at least a steering torque, calculates dq-axes current command values from the steering assist command values, converts the dq-axes current command values into 3-phase duty command values, driving-controls a 3-phase brushless motor by an inverter of a PWM control, and applies an assist torque to a steering system of a vehicle, wherein the electric power steering apparatus has plural dead time compensating functions of which efficiencies to respectively perform a dead time compensation of the inverter are different each other, and performs the dead time compensation by switching from one of the plural dead time compensating functions to an another dead time compensating function with a predetermined condition.

A vector control type electric power steering apparatus that compensates a dead time of an inverter, a motor back-EMF and an interference voltage by means of a mutual inductance between motor windings, improves a distortion of a current waveform and a responsibility of a current control, and suppresses a noisy sound, vibration and a ripple. The apparatus driving-controls a three-phase brushless motor which applies an assist torque to a steering mechanism of a vehicle by using a current command value calculated based on at least a steering torque, and vector-controls the three-phase brushless motor by using dq-axis command values that are converted from the current command value via an inverter, including: a 3-phase disturbance observer to compensate respective phase disturbance voltages, which include a dead time of the inverter, for 3-phase voltage command values.

[Problem] An object of the present invention is to provide an electric power steering apparatus of a vector control system that compensates a dead time of an inverter, a motor back-EMF and an interference voltage due to a mutual inductance between motor windings, improves a distortion of a current waveform and a responsibility of a current control, and suppresses a noise, vibration and a ripple. [Means for Solving the Problem] The present invention is the electric power steering apparatus that driving-controls a 3-phase brushless motor which applies an assist torque to a steering mechanism of a vehicle by using a current command value calculated based on at least a steering torque, and vector-controls the 3-phase brushless motor, via an inverter, by converting dq-axes command values converted from the current command value into 3-phase values, comprising a dq-axes disturbance observer to compensate respective axes disturbance voltages, which include a dead time of the inverter, for the dq-axes command values, or comprising: a dq-axes disturbance observer to compensate respective axes disturbance voltages, which include a dead time of the inverter, for the dq-axes command values and a spatial vector modulating section.

An electric power steering apparatus that ideally compensates dead time of the inverter without the tuning operation, improves distortion of the current waveform and the responsibility of the current control, and suppresses sound, vibration, the ripple that the low speed steering maneuver is effective. The apparatus converts dq-axes current command values calculated based on at least a steering torque into 3-phase duty command values, controls a 3-phase brushless motor by an inverter of a PWM-control, and applies an assist torque to a steering system of a vehicle, wherein 3-phase detection voltages are estimated based on 3-phase motor terminal voltages, loss voltages due to a dead time of the inverter are estimated from differences between 3-phase correction command voltages calculated from the 3-phase duty command values and the 3-phase detection voltages, and a dead time compensation of the inverter is performed by feeding back dead time compensation values obtained by compensating the loss voltages to the dq-axes current command values.

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Tokyo, Japan

Hideki Sawada