Jtekt Corporation

Koyo Seiko Company, Ltd.

Koyo Electronics Industries Co., Ltd.

Panasonic Intellectual Property Management Co., Ltd.

Takeshi Ueda

Shigeki Nagase

Katsutoshi Nishizaki

Hiroshi Sumasu

Masahiko Sakamaki

Hayato Komatsu

Kouya Yoshida

Shingo Maeda

Yuji Kariatsumari

Yoshinobu Shimizu

Toshiaki Oya

Nobuhiro Uchida

Ken Matsubara

Kosuke Yamanaka

Naoki Maeda

Shirou Nakano

Minoru Sentoku

Atsushi Ishihara

Tatsuma Kouchi

Masanori Arima

Hideki Higashira

Yoshikazu Kuroumaru

Yasuyuki Yoshii

Daisuke Maeda

Daigo Yamashina

Noboru Niguchi

Kensaku Kinugawa

Takayasu Yamazaki

Yasuhiro Saitou

Yasuhiro Kamatani

Genki Murata

Akira Sugimoto

Yasunobu Tomizawa

Seiji Uematsu

Kimihito Chino

Angular widths of respective magnetic poles of a detection rotor are stored and divisions are set for respective magnetic pole pairs. Based on output signals from first and second magnetic sensors, a rotation angle computation unit computes first and second rotation angles that are rotation angles within the corresponding division. Based on the angular widths, the rotation angle computation unit identifies the magnetic pole sensed by the first magnetic sensor and computes a first absolute rotation angle using the first rotation angle. Based on the identified magnetic pole and the second rotation angle, the rotation angle computation unit computes a second absolute rotation angle. The rotation angle of the detection rotor is computed based on the first and second absolute angles.

Rotation angle detection device compromising

A rotation angle calculation unit includes a first rotation angle calculation portion, a second rotation angle calculation portion, a third rotation angle calculation portion, an abnormality monitoring portion, and a final rotation angle calculation portion. The abnormality monitoring portion determines, based on a first output signal, a second output signal, and a third output signal, whether the first to third output signals are each normal or abnormal. The final rotation angle calculation portion calculates a final rotation angle based on the final determination result obtained by the abnormality monitoring portion and the first to third rotation angles calculated by the first to third rotation angle calculation portions, respectively.

Rotation angle detection device

A torque detecting apparatus detects a torque applied to a first shaft, based on a relative rotational displacement between the first shaft and a second shaft caused by torsion in a coupling shaft which couples the first shaft and the second shaft. The torque detecting apparatus includes: first and second magnets which are coupled to the first shaft and the second shaft so as to rotate together with the first shaft and second shaft, respectively; and a plurality of magnetic sensors which are disposed between the first magnet and the second magnet and which detect a rotational angle of the first shaft and a rotational angle of the second shaft.

Torque detecting apparatus

Upon detecting a peak value from output signals of one of either a first or a second magnetic sensor, an rotation angle computation device identifies, on basis of an amplitude compensation table corresponding to the one magnetic sensor for which the peak value was detected, a pole number of a magnetic pole sensed by the magnetic sensor. Then, based on the identified pole number and a magnetic pole identification table, a pole number of a magnetic pole sensed by the other magnetic sensor is identified. The pole numbers of the magnetic poles sensed by the respective magnetic sensors are thus identified, and the rotation angle computation device compensates the output signals of the respective magnetic sensors using amplitude compensation gains corresponding to the sensed magnetic poles (magnetic pole pair).

A first third harmonic component removing portion calculates an approximate value (sin &#x3b8;)of a signal sin &#x3b8; that is an output signal of a first magnetic sensor from which third harmonic components have been removed. A second third harmonic component removing portion calculates an approximate value (cos &#x3b8;)of a signal cos &#x3b8; that is an output signal of a second magnetic sensor from which third harmonic components have been removed. A rotation angle calculation portion calculates a rotation angle &#x3b8; of a rotor based on the approximate value (sin &#x3b8;)of sin &#x3b8;, which has been calculated by the first third harmonic component removing portion and the approximate value (cos &#x3b8;)of cos &#x3b8;, which has been calculated by the second third harmonic component removing portion.

Rotation angle detection apparatus

An output signal V=sin &#x3b8; is output from a first magnetic sensor and an output signal V=cos(&#x3b8;+&#x3b1;) is output from a second magnetic sensor. An output signal correction unit in a rotation angle computing device corrects the output signal Vfrom the second magnetic sensor to an output signal V' (=cos &#x3b8;) so that a positional phase difference (90&#xb0;+&#x3b1;) between the magnetic sensors and is made equal to a target phase difference of 90&#xb0;. A rotation angle computing unit computes the rotation angle &#x3b8; of a rotor based on the corrected signal V&#x2032; (=cos &#x3b8;) and the other output signal V(=sin &#x3b8;).

In a material handling and stair climbing vehicle, when the vehicle is shifted from a state where the wheels with two axles are grounded on a travelling surface to a standing state achieved by the wheels with one axle, a main body portion is turned around support shafts with respect to supporting portions in the two-axle wheel grounded state. Then, an inertial force around the support shafts is generated by reducing the speed of turning of the main body portion with respect to the supporting portions. Then, the vehicle is shifted to the standing state achieved by the wheels with one axle by turning the supporting portions around the axles of the wheels with one axle, which are grounded on the travelling surface, by the inertial force.

Material handling and stair climbing vehicle

When the zero-crossing of one of the output signals of magnetic sensors has been detected, a rotation angle computing device identifies a magnetic pole sensed by the first magnetic sensor based on the other two output signals. Subsequently, the rotation angle computing device identifies the magnetic pole sensed by the second magnetic sensor and the magnetic pole sensed by the third magnetic sensor based on the magnetic pole sensed by the first magnetic sensor. After that, the rotation angle computing device corrects the amplitude of the output signal of each magnetic sensor based on the identified magnetic poles respectively sensed by the magnetic sensors. Then, the rotation angle computing device computes the electric angle &#x3b8;e of the rotor based on the corrected output signals.

Three magnetic sensors are arranged around a rotor at predetermined angular intervals about the rotation axis of the rotor. Sinusoidal signals that have a phase difference of a predetermined degree of 45&#xb0; are output from the respective magnetic sensors. A rotation angle computing device detects a magnetic pole transition in a first output signal as follows. Specifically, the rotation angle computing device detects a magnetic pole transition in the first output signal based on a value having a larger absolute value between a current value of the second sinusoidal signal and a current value of the third sinusoidal signal, an immediately preceding value of the first sinusoidal signal and a current value of the first sinusoidal signal.

Rotation angle detecting device

A motor control device for driving a brushless motor includes a current detecting unit which detects respective phase currents which flow into the brushless motor; a control calculation unit which calculates instruction values showing respective phase voltages to be applied to the brushless motor, and outputs the instruction values as phase voltage instruction values; a phase resistance calculation unit which calculates respective phase resistance values based on detection values of the respective phase currents detected by the current detecting unit, and the instruction values of the respective phase voltages applied to the brushless motor at the time of the detection of the detection values; a correction unit which corrects the phase voltage instruction values according to the respective phase resistance values calculated by the phase resistance calculation unit; and a driving unit which drives the brushless motor based on the phase voltage instruction values after correction by the correction unit.

Motor control device and electric power steering device

A rotor includes a cylindrical magnet having a plurality of magnetic pole pairs. There are two types of the magnitude of magnetic force in the magnetic pole pairs, that is, a relatively large first magnetic force and a second magnetic force that is smaller than the first magnetic force. Three magnetic sensors are arranged around the rotor. A rotation angle computing device detects the peak values of output signals of the respective magnetic sensors. Then, the rotation angle computing device identifies the magnetic pole pair, sensed by the first magnetic sensor, based on a combination of the local maximum values of the three output signals.

Rotation angle detection device and torque detection device

Three magnetic sensors are arranged around a rotor at predetermined angular intervals about the rotation axis of the rotor. Sinusoidal signals having a phase difference of 120&#xb0; are output from the magnetic sensors. A rotation angle computing device detects a magnetic pole transition in a first output signal as follows. The rotation angle computing device detects a magnetic pole transition in the first output signal based on a current value of one of the second and third sinusoidal signals, an absolute value of a difference between an immediately preceding value and the current value of the one of the second and third sinusoidal signals being larger than an absolute value of a difference between an immediately preceding value and the current value of the other of the second and third sinusoidal signals, an immediately preceding value of the first sinusoidal signal and a current value of the first sinusoidal signal.

A command current setting portion has a target value corrector that calculates d-axis and q-axis current command values idc, iqc that are to be supplied to an open-loop controller, based on d-axis and q-axis current target values id*, iq*. When d-axis and q-axis voltage target value vd*, vq* calculated from the d-axis and q-axis current target values id*, iq* by the motor circuit equations exceed a voltage limit, this target value correctorcorrects the d-axis and q-axis current target values id*, iq* by the field weakening control such that d-axis and q-axis voltages vd, vq and d-axis and q-axis currents id, iq satisfy &#x221a;(vd+vq)&#x2266;Vlim and &#x221a;(id+iq)&#x2266;Ilim respectively. The d-axis and q-axis current command values idc, iqc are obtained by this correction.

Motor controller and electronic power steering apparatus

An angle calculator detects a rotation angle &#x3b8;a of a rotor. A three-phase/d-q axis converter outputs detected current id, iq on d-q coordinate axes by making a conversion, based on a corrected detection angle &#x3b8;c obtained by adding or subtracting an amount of detection deviation from a time point of current detection to or from the detection angle &#x3b8;a. A command current calculator calculates command current id*, iq* on the d-q coordinate axes based on a steering torque T and a speed S. A feedback controller calculates command voltages vd, vq on the d-q coordinate axes based on the command current id*, iq* and the detected current id, iq. A d-q axis/three-phase converter converts the command voltages vd, vq into three-phase command voltages, based on a corrected detection angle &#x3b8;b obtained by adding an amount of detection deviation from a time point when a motor is driven to the detection angle &#x3b8;a. The deviation can be eliminated by the command voltages, and the motor can be driven with high precision.

An angular velocity estimate (&#x3c9;e) used in motor control of an electric power steering is obtained as follows. In a first state period during which the motor substantially stops its rotation, a resistance calculation unit calculates a motor resistance value (Rc) on the basis of a detected value (Vm) of motor voltage and a detected value (Im) of motor current. An average calculation unit obtains an average value (Rav) of the calculated resistance values (Rc) in a retained period. A current-resistance characteristic that associates motor current with motor resistance is held in a characteristic holding unit, and a characteristic updating unit updates the current-resistance characteristic on the basis of the average value (Rav). An estimate calculation unit calculates the angular velocity estimate (&#x3c9;e) on the basis of the detected value (Vm) of motor voltage, the detected value (Im) of motor current and a motor resistance value (Rm) obtained from the current-resistance characteristic.

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Kashiba, Japan

Takeshi Ueda