Electrically Driven Power Steering System
First Claim
1. An electrically driven power steering system, comprising:
- a steering mechanism that steers steerable wheels along with a steering operation of a steering wheel;
a motor providing a steering force for the steering mechanism;
a control unit drivingly controlling the motor;
a command signal calculating section disposed in the control unit to calculate a vector control command signal for drivingly controlling the motor in accordance with a driving situation of a vehicle;
a two-phase to three-phase converting section disposed in the control unit to convert the vector control command signal into a voltage command signal for each phase of the motor;
a PWM control section disposed in the control unit to output a PWM duty signal (Du, Dv, Dw) of each phase of the motor in accordance with the voltage command signal of a corresponding one of the phases of the motor;
an inverter, disposed in the control unit, constituted by a switching circuit controlled by means of the PWM duty signals (Du, Dv, Dw), and drivingly controlling the motor;
a current sensor disposed in a direct current bus bar of the inverter to detect a direct current bus bar current;
a phase current detecting section disposed in the control unit to detect or estimate a current value Iu, Iv, Iw of each phase of the motor on the direct current bus bar current and the PWM duty signals (Du, Dv, Dw);
an estimated primary current calculating section disposed in the control unit to calculate an estimated primary current as follows;
(Iu×
Du+Iv×
Dv+Iw×
Dw)/100% on a basis of the current value (Iu, Iv, Iw) of each phase of the motor and the PWM duty signals (Du, Dv, Dw); and
an abnormality monitoring section configured to detect an abnormality of the control unit on a basis of the direct current bus bar and the estimated primary current.
3 Assignments
0 Petitions
Accused Products
Abstract
In an electrically driven power steering system having a blushless three phase motor, an abnormality of a control unit is detected on a basis of a direct current bus bar current of an inverter detected by a current sensor and an estimated primary current. The estimated primary current is calculated from, for example, the following equation, namely, Iu×Du+Iv×Dv+Iw×Dw)/100%, wherein Iu denotes a current of a U phase of the motor, Du denotes a PWM duty signal of the U phase, Iv denotes a current of a V phase of the motor, Dv denotes the PWM duty signal of the V phase of the motor, Iw denotes a current of a W phase of the motor, and Dw denotes the PWM duty signal of the W phase.
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Citations
20 Claims
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1. An electrically driven power steering system, comprising:
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a steering mechanism that steers steerable wheels along with a steering operation of a steering wheel; a motor providing a steering force for the steering mechanism; a control unit drivingly controlling the motor; a command signal calculating section disposed in the control unit to calculate a vector control command signal for drivingly controlling the motor in accordance with a driving situation of a vehicle; a two-phase to three-phase converting section disposed in the control unit to convert the vector control command signal into a voltage command signal for each phase of the motor; a PWM control section disposed in the control unit to output a PWM duty signal (Du, Dv, Dw) of each phase of the motor in accordance with the voltage command signal of a corresponding one of the phases of the motor; an inverter, disposed in the control unit, constituted by a switching circuit controlled by means of the PWM duty signals (Du, Dv, Dw), and drivingly controlling the motor; a current sensor disposed in a direct current bus bar of the inverter to detect a direct current bus bar current; a phase current detecting section disposed in the control unit to detect or estimate a current value Iu, Iv, Iw of each phase of the motor on the direct current bus bar current and the PWM duty signals (Du, Dv, Dw); an estimated primary current calculating section disposed in the control unit to calculate an estimated primary current as follows;
(Iu×
Du+Iv×
Dv+Iw×
Dw)/100% on a basis of the current value (Iu, Iv, Iw) of each phase of the motor and the PWM duty signals (Du, Dv, Dw); andan abnormality monitoring section configured to detect an abnormality of the control unit on a basis of the direct current bus bar and the estimated primary current. - View Dependent Claims (2, 5, 6, 7, 8, 20)
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3. An electrically driven power steering system, comprising:
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a steering mechanism that steers steerable wheels along with a steering operation of a steering wheel; a motor providing a steering force for the steering mechanism; a control unit drivingly controlling the motor; a command signal calculating section disposed in the control unit to calculate vector control command signals Vd*, Vq* for drivingly controlling the motor in accordance with a driving situation of a vehicle; a two-phase to three-phase converting section disposed in the control unit to convert each of the vector control command signals into the voltage command signal for each phase of the motor; a PWM control section disposed in the control unit to output a PWM duty signal (Du, Dv, Dw) of each phase of the motor in accordance with the voltage command signal of a corresponding one of the three phases of the motor; an inverter, disposed in the control unit, constituted by a switching circuit controlled by means of the PWM duty signals (Du, Dv, Dw), and drivingly controlling the motor; a current sensor disposed in a direct current bus bar of the inverter to detect a direct current bus bar current; a phase current detecting section disposed in the control unit to detect or estimate a current value of each phase of the motor on a direct current bus bar current and the PWM duty signals (Du, Dv, Dw); a three-phase to two-phase converting section disposed in the control unit to convert the current value of each phase of the motor into two phase current values Id, Iq for a vector control purpose; a voltage detector disposed in the control unit to detect a power supply voltage Vbatt supplied to the control unit; an estimated primary current calculating section disposed in the control unit to calculate an estimated primary current as follows;
(Id×
Vd*+Iq×
Vq*)/Vbatt on a basis of the vector control command signals Vd*, Vq*, two phase current values Id, Iq, and the power supply voltage; andan abnormality monitoring section configured to detect an abnormality of the control unit on a basis of the direct current bus bar current and the estimated primary current. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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4. An electrically driven power steering system, comprising:
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a steering mechanism that steers steerable wheels along with a steering operation of a steering wheel; a motor providing a steering force for the steering mechanism; a control unit drivingly controlling the motor; a command signal calculating section disposed in the control unit to calculate vector control command signals for drivingly controlling the motor in accordance with a driving situation of a vehicle; a two-phase to three-phase converting section disposed in the control unit to convert each of the vector control command signals into a voltage command signal for each phase of the motor; a PWM control section disposed in the control unit to output a PWM duty signal (Du, Dv, Dw) of each phase of the motor in accordance with the voltage command signal of a corresponding one of the three phases of the motor; an inverter, disposed in the control unit, constituted by a switching circuit controlled by means of the PWM duty signals (Du, Dv, Dw), and drivingly controlling the motor; a current sensor disposed in a direct current bus bar of the inverter to detect a direct current bus bar current; a phase current detecting section disposed in the control unit to detect or estimate a current value of each phase of the motor on a direct current bus bar current and the PWM duty signals (Du, Dv, Dw); a three-phase to two-phase converting section disposed in the control unit to convert the current value of each phase of the motor into two phase current values Id, Iq for a vector control purpose; another three-phase to two-phase converting section disposed in the control unit to convert the PWM duty signals into d-axis and q-axis PWM duty signals Dd, Dq; an estimated primary current calculating section disposed in the control unit to calculate an estimated primary current as follows;
(Id×
Dd+Iq×
Dq)/100% on a basis of the current values for the vector control signal purpose Id, Iq, d-axis, q-axis PWM duty vector control command signals Vd*, Vq*, two phase current values Id, Iq, and the power supply voltage; andan abnormality monitoring section configured to detect an abnormality of the control unit on a basis of the direct current bus bar current and the estimated primary current. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification