US20020179363A1 - Electric power steering control system - Google Patents

Electric power steering control system Download PDF

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Publication number
US20020179363A1
US20020179363A1 US09/995,675 US99567501A US2002179363A1 US 20020179363 A1 US20020179363 A1 US 20020179363A1 US 99567501 A US99567501 A US 99567501A US 2002179363 A1 US2002179363 A1 US 2002179363A1
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United States
Prior art keywords
temperature
current
section
motor
detected
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US09/995,675
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English (en)
Inventor
Yuji Takatsuka
Katsuhiko Ohmae
Norihiro Yamaguchi
Susumu Zeniya
Takayuki Kifuku
Shigeki Ohtagaki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
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Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Assigned to MITSUBISHI DENKI KABUSHIKI KAISHA reassignment MITSUBISHI DENKI KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KIFUKU, TAKAYUKI, OHMAE, KATSUHIKO, OHTAGAKI, SHIGEKI, YAMAGUCHI, NOIHIRO, TAKATSUKA, YUJI, ZENIYA, SUSUMU
Assigned to MITSUBISHI DENKI KABUSHIKI KAISHA reassignment MITSUBISHI DENKI KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KIFUKU, TAKAYUKI, OHMAE, KATSUHIKO, OHTAGAKI, SHIGEKI, YAMAGUCHI, NORIHIRO, TAKATSUKA, YUJI, ZENIYA, SUSUMU
Publication of US20020179363A1 publication Critical patent/US20020179363A1/en
Priority to US10/634,955 priority Critical patent/US6860361B2/en
Priority to US10/864,397 priority patent/US6902028B2/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/046—Controlling the motor
    • B62D5/0463—Controlling the motor calculating assisting torque from the motor based on driver input
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/0481—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures
    • B62D5/0496—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures by using a temperature sensor

Definitions

  • the present invention relates to electric power steering for reducing a required steering force in a steering system by means of mechanical power of a motor. More particularly, the present invention relates to an electric power steering control system for preventing overheating of the motor and a motor drive circuit.
  • a heat sensor is provided on a periphery of the motor or the motor drive circuit portion, a motor current limit value is calculated based on a heating value estimated from a temperature detected by the temperature sensor and a current of the motor, and the motor current is limited by means of this calculated motor current limit value. Accordingly, the overheating of the motor is prevented.
  • the heat sensor is provided to a vicinity of a location generating heat, and control for preventing overheating is realized by means of directly detecting an ambient temperature of the location generating heat.
  • control for preventing overheating is realized by means of directly detecting an ambient temperature of the location generating heat.
  • the temperature sensor in an actual system there are cases when it is difficult, for reasons of construction and cost, to place the temperature sensor in the vicinity of the heat-generating part. In such cases, prevention of overheating becomes problematic in the conventional art.
  • a plurality of heat-generating parts or parts at which it is desirable to estimate the temperature thereof
  • a plurality of temperature sensors and I/F circuits need to be installed. Therefore, there was a problem that it was disadvantageous in terms of cost and miniaturization.
  • an object of the present invention is to obtain an electric power steering control system capable of achieving overheating prevention even without a temperature sensor being provided to a vicinity of a heat-generating location.
  • An electric power steering control system comprises a motor for adding a steering assisting force to a steering system; a steering force detection section for detecting steering force in the steering system; a motor current determination section for determining a motor current based on at least the steering force detected by means of the steering force detection section; a temperature detection section for detecting an ambient temperature; a coefficient setting section for setting a coefficient in accordance with a detected temperature obtained by means of the temperature detection section; a motor current determination section for detecting a current being passed to the motor; a maximum current limit value calculation section for calculating a maximum current limit value based on the detected current detected by means of the motor current detection section and the coefficient set by the coefficient setting section; a current limiting section for selecting and outputting as a target current the smaller of either the motor current determined by means of the motor current determination section or the maximum current value calculated by means of the maximum current limit value calculation section; a motor current control section for passing the target current to the motor such that the target current becomes equal to the detected current being detected
  • An electric power steering control system comprises a motor for adding steering assistance force to a steering system; a steering force detection section for detecting steering force of the steering system; a motor current determination section for determining a motor current based on at least the steering force detected by means of the steering force detection section; a temperature detection section for detecting an ambient temperature; a timer for measuring time from when predetermined conditions are established; a control temperature calculation section for calculating a control temperature based on the temperature detected by the temperature detection section and the time measured by the timer; a coefficient settling section for setting a coefficient based on the control temperature calculated by the control temperature calculation section; a motor current detection section for detecting a current being passed to the motor; a maximum current limit value calculation section for calculating a maximum current limit value based on a current detected by the motor current detection section and the coefficient set by the coefficient setting section; a current limiting section for selecting the smaller value between the motor current determined by the motor current determination section and the maximum current limit value calculated by the maximum current limit value
  • An electric power steering control system comprises a motor for adding steering assistance force to a steering system; a steering force detection section for detecting steering force of the steering system; a motor current determination section for determining a motor current based on at least the steering force detected by means of the steering force detection section; a temperature detection section for detecting an ambient temperature; a timer for measuring time from when predetermined conditions are established; a control temperature calculation section for calculating a control temperature based on the temperature detected by the temperature detection section and the time measured by the timer; a coefficient setting section for setting a coefficient based on the control temperature calculated by the control temperature calculation section and the temperature detected by the temperature detection section; a motor current detection section for detecting a current being passed to the motor; a maximum current limit value calculation section for calculating a maximum current limit value based on a current detected by the motor current detection section and the coefficient set by the coefficient setting section; a current limiting section for selecting the smaller value between the motor current determined by the motor current determination section and the maximum current limit
  • the predetermined condition is that the key switch is on.
  • an electric power steering control system further comprises an engine rotation detection section for detecting the number of engine rotations, wherein the predetermined condition is that the number of engine rotations detected by the engine rotation detection section is greater than a predetermined value.
  • an electric power steering control system further comprises a vehicle speed detection section for detecting a vehicle speed, wherein the predetermined condition is that the vehicle speed detected by the vehicle speed detection section is above a predetermined value.
  • the predetermined condition is that the steering force detected by the steering force detection section is greater than a predetermined value.
  • the predetermined condition is that the motor current is greater than a predetermined value.
  • the coefficient setting unit sets the coefficient in accordance with a detected temperature at the time of activation obtained by means of the temperature detection section.
  • an electric power steering control system further comprises a power supply holding section for holding a power supply until the temperature detected by the temperature detection section drops below a predetermined value after the key switch is turned off.
  • an electric power steering control system further comprises a power supply holding section for holding a power supply until the temperature detected by the temperature detection section drops below a predetermined value after the key switch is turned off, or until a duration of time having elapsed since the key switch was turned off is measured and the elapsed duration of time becomes greater than a predetermined duration of time.
  • control temperature calculation section calculates the control temperature based on a temperature that is the temperature detected by the temperature detection section and corrected by a correction amount set in accordance with characteristics of self-generation of heat, and the duration of time measured by the timer.
  • FIG. 1 is a diagram depicting a construction of an electric power steering control system according to Embodiment 1 of the present invention
  • FIG. 2 is a block diagram depicting a construction of the a control apparatus of the electric power steering control system according to Embodiment 1 of the present invention
  • FIG. 3 is a diagram depicting a control block of the control apparatus of the electric power steering control system according to 1 of the present invention
  • FIG. 4 is a diagram depicting input and output characteristics of a motor current determination unit of the control apparatus of the electric power steering control system, according to Embodiment 1 of the present invention.
  • FIG. 5 is a diagram depicting a current limiting unit of the control apparatus of the electric power steering control system, according to Embodiment 1 of the present invention.
  • FIG. 6 is a flow chart depicting processing of a calculation of a maximum current limit value for the control apparatus of the electric power steering control system, according to Embodiment 1 of the present invention.
  • FIG. 7 is a diagram depicting a coefficient of a coefficient determining unit of the control apparatus in the electric power steering control system according to Embodiment 1 of the present invention.
  • FIG. 8 is a diagram depicting an example of results of calculations by a maximum current limit value calculation unit of the control apparatus in the electric power steering control system according to Embodiment 1 of the present invention.
  • FIG. 9 is a diagram depicting a control block of a control apparatus in an electric power steering control system according to Embodiment 2 of the present invention.
  • FIG. 10 is a flow chart depicting processing of a timer and a control temperature calculation unit of the control apparatus in the electric power steering control system according to Embodiment 2 of the present invention.
  • FIG. 11 is a timing chart depicting operation of the timer and the control temperature calculation unit of the control apparatus in the electric power steering control system according to Embodiment 2 of the present invention.
  • FIG. 12 is a diagram depicting a block control of an electric power steering control system according to Embodiment 3 of the present invention.
  • FIG. 13 is a flow chart depicting processing of a timer and a control temperature calculation unit of a control apparatus in the electric power steering control system according to Embodiment 3 of the present invention
  • FIG. 14 is a flow chart depicting processing of a coefficient setting unit of the control apparatus in the electric power steering control system according to Embodiment 3 of the present invention.
  • FIG. 15 is a timing chart depicting operation of the timer, the control temperature calculation unit and the coefficient setting unit of the control apparatus in the electric power steering control system according to Embodiment 3 of the present invention.
  • FIG. 16 is a diagram depicting a coefficient of the coefficient setting unit of the control apparatus in the electric power steering control system according to Embodiment 3 of the present invention.
  • FIG. 17 is a diagram depicting a control block of a control apparatus of an electric power steering control system according to Embodiment 4 of the present invention.
  • FIG. 18 is a flow chart depicting processing of a timer and a control temperature calculation unit of the control apparatus in the electric power steering control system, according to Embodiment 4 of the present invention.
  • FIG. 19 is a timing chart of operations of the timer, the control temperature calculation unit and a coefficient setting unit of the control apparatus in the electric power steering control system, according to Embodiment 4 of the present invention.
  • FIG. 20 is a diagram depicting a control block of a control apparatus of an electric power steering control system, according to Embodiment 5 of the present invention.
  • FIG. 21 is a flow chart depicting processing of a timer and a control temperature calculation unit of the control apparatus in the electric power steering control system, according to Embodiment 5 of the present invention.
  • FIG. 22 is a flow chart depicting processing of the timer and the control temperature calculation unit of the control apparatus in the electric power steering control system, according to Embodiment 5 of the present invention.
  • FIG. 24 is a diagram depicting a control block of a control apparatus of an electric power steering control system according to Embodiment 6 of the present invention.
  • FIG. 25 is a flow chart depicting processing of a timer and a control temperature calculation unit of the control apparatus in the electric power steering control system, according to Embodiment 6 of the present invention.
  • FIG. 26 is a flow chart depicting processing of the timer and the control temperature calculation unit of the control apparatus in the electric power steering control system, according to Embodiment 6 of the present invention.
  • FIG. 27 is a timing chart depicting operations of the timer, the control temperature calculation unit and the coefficient setting unit of the control apparatus in the electric power steering control system, according to Embodiment 6 of the present invention.
  • FIG. 28 is a flow chart depicting processing of a coefficient setting unit of a control apparatus of an electric power steering control system according to Embodiment 7 of the present invention.
  • FIG. 29 is a diagram depicting a construction of a control apparatus of an electric power steering control system according to Embodiment 8 of the present invention.
  • FIG. 30 is a diagram depicting a construction of a power circuit of the control apparatus in the electric power steering control system according to Embodiment 8 of the present invention.
  • FIG. 31 is a flow chart depicting processing of a micon in the control apparatus in the electric power steering control system according to Embodiment 8 of the present invention.
  • FIG. 32 is a flow chart depicting processing of a micon in a control apparatus in an electric power steering control system according to Embodiment 9 of the present invention.
  • FIG. 33 is a flow chart depicting processing of a timer and a control temperature calculation unit of a control apparatus in an electric power steering control system according to Embodiment 10 of the present invention.
  • FIG. 34 is a diagram depicting characteristics of a correction amount of the control apparatus in the electric power steering control system according to 10 of the present invention.
  • FIG. 1 is a diagram depicting a construction of the electric power steering control system according to Embodiment 1 of the present invention. Note that the same reference numerals in each of the drawings indicate the same or equivalent parts.
  • FIG. 2 is a diagram depicting a construction of a control apparatus of the electric power steering control system according to Embodiment 1 of the present invention.
  • 11 is the tie rod.
  • FIG. 2 the torque sensors 2 through the control device 7 are the same as those of FIG. 1.
  • Reference numeral 12 is a battery for providing electric power to the control device 7 .
  • 71 is an I/F circuit for inputting a signal from the torque sensor 2 ;
  • 72 is an I/F circuit for inputting a signal from the vehicle speed sensor 3 ;
  • 73 is an I/F circuit for inputting the engine rotation signal 4 ;
  • 74 is an I/F circuit for inputting a signal from the key switch 5 ;
  • 75 is the temperature sensor (the temperature detection section) for detecting the temperature;
  • 76 is an I/F circuit for inputting a signal from the temperature sensor 75 ;
  • 77 is a motor drive circuit for driving the motor 6 ;
  • 78 is a current detection circuit for detecting the current being passed to the motor 6 ;
  • 79 is a micon for performing control of the electrical power steering.
  • FIG. 3 is a diagram depicting a control block of processing carried out by the micon inside the control apparatus of the electric power steering control system according to Embodiment 1.
  • reference numeral 101 is a vehicle speed signal detected by the vehicle speed sensor 3 ; 102 is a torque signal detected by the torque sensor 2 ; and 103 is a temperature signal detected by the temperature sensor 75 .
  • 104 is a motor current determination unit (i.e., the motor current determination section) for determining, based on a vehicle speed signal 101 (VSP) and a torque signal 102 (TRQ), the motor current for assisting the steering force;
  • 105 is a current limiting unit (i.e., the current limiting section) for applying a limit being the maximum current limit value (Limit), explained below, to the motor current (Im 1 ) determined by the motor current determination unit 104 ;
  • 106 is a motor current control unit (i.e., the motor current control section) for passing the target current (Imt) indicated by the current limiting unit 105 to the motor 6 in a controlled fashion such that the target current (Imt) is equivalent to the detected current (Imd) which is detected by an motor current detection unit explained below;
  • 107 is the motor current detection unit (i.e., the motor current detection section) for detecting the motor current and corresponds to the current detection circuit 78 of FIG. 2.
  • 108 is a coefficient setting unit (i.e., the coefficient setting section) for setting a coefficient for calculation of the maximum current limit value described below in accordance with the temperature signal 103 (i.e., Temp); and 109 is a maximum current limit value calculation unit (i.e., the maximum current limit value calculation section) for calculating the maximum current limit value (i.e., Limit) based on the detected current (i.e., Imd) detected by means of the motor current detection unit 107 and the coefficient which is determined by means of the coefficient setting unit 108 (i.e., the maximum current limit value calculation section).
  • FIG. 4 is a diagram depicting input output characteristics of the motor current determination unit.
  • the motor current determination unit 104 has the input and output characteristics shown in FIG. 4 and determines the motor current (Im 1 ) in accordance with the torque (TRQ) and the vehicle speed (VSP). By having the characteristics shown in FIG. 4 a result is produced such that at a time of steering to the right the motor current is passed to the right direction, so less steering force is required. Further, at a time of steering to the left, on the other hand, the motor current is passed to the left direction, so less steering force is required. Additionally, altering the motor current in accordance with the vehicle speed (VSP) produces a result that the steering assisting force appropriate for each vehicle speed (ex, low vehicle speed through high vehicle speed) is generated.
  • VSP vehicle speed
  • FIG. 5 is a diagram depicting a construction of the current limiting unit.
  • the current limiting unit 105 has a construction as shown in FIG. 5, and selects and outputs as a target current (i.e., Imt) the smaller of either the motor current (i.e., Im 1 ) determined by means of the motor current determination unit 104 or the maximum current limit value (i.e., Limit) calculated by means of the maximum current limit value calculation unit 109 .
  • a target current i.e., Imt
  • the maximum current limit value i.e., Limit
  • FIG. 6 is a flow chart depicting processing of the maximum current limit value calculation unit 109 .
  • the maximum current limit value calculation unit 109 According to FIG. 6, at first when the control device 7 is activated at step 121 , an initial value is set for the maximum current limit value (i.e., Limit). Next, at step 122 an the current increase rate (kim) is calculated; at step 123 the current increase rate (kim) is added to the maximum current limit value (i.e., Limit); and steps 122 to 123 are repeated thereafter.
  • the maximum current limit value i.e., Limit
  • FIG. 7 is a diagram depicting characteristics (i.e., coefficients) of the current increase rate of the maximum current limit value calculation unit.
  • the characteristics of the current increase rate (kim) are as in FIG. 7 by the detected current of the motor (i.e., Imd). Further, the characteristic (i.e., coefficient) of the current increase rate (kim) is constructed such that when the temperature is low the coefficient is as indicated by (1) (n.b. the encircled numbers in the diagrams are represented in parenthesis in the specification for reasons of convenience), and as the temperature rises the coefficient changes to (2) and (3). It is the coefficient setting unit 108 which makes the coefficient change in accordance with the temperature.
  • FIG. 8 is a diagram depicting a result (i.e., an attenuation characteristic) of the calculation performed by the maximum current limit value calculation unit. Note that this FIG. 8 depicts an example in which the coefficient does not change. When the detected temperature changes, smooth curved lines as shown in FIG. 8 are not produced.
  • the efficient setting unit 108 sets the coefficient based on a temperature Temp detected by means of the temperature sensor 75 , and the maximum current limit value calculation unit 109 calculates the maximum current limit value Limit based on the coefficient set by the coefficient setting unit 108 .
  • the maximum current limit value i.e., Limit
  • the maximum current limit value attenuates as shown in FIG. 8 and limits the motor current. Accordingly, it becomes possible to prevent overheating of the motor 6 and the control device 7 .
  • 110 is a key switch (signal); 111 is timer for measuring a duration of time from when the key switch 110 is turned on; and 112 is a control temperature calculation unit (i.e., a control temperature calculation section) for calculating the control temperature (i.e., Temp) in accordance with the temperature signal 103 and the timer 111 .
  • a control temperature calculation unit i.e., a control temperature calculation section
  • FIG. 10 is a flow chart depicting an operation of the control temperature calculation unit.
  • a temperature correction value TempC and the timer are initialized to zero (0).
  • step 131 the signal 103 from the temperature sensor 75 is assigned to TempM.
  • step 132 the status of the key switch 110 is determined, and if the key switch is off then step 133 is carried out.
  • step 133 the timer 111 for measuring the on time of the key switch is cleared to zero and the procedure advances to step 138 .
  • step 132 the procedure splits off to YES, and at step 134 the timer 111 is incremented.
  • the value indicated by the timer 111 is compared against a predetermined value Time 1 , and in the case when the value of the timer 111 is smaller the procedure splits off to NO and advances to step 138 .
  • step 137 the predetermined value T 1 is added to the temperature correction value TempC and the procedure advances to step 138 .
  • step 138 the temperature correction value TempC is subtracted from the TempM which has saved the signal 103 of the temperature sensor 75 , and the result is assigned to the control temperature Temp.
  • step 139 the control temperature Temp is compared against the predetermined value T 2 , and in the case when the control temperature Temp is equal to or greater than the predetermined value T 2 the procedure splits off to NO and returns to step 131 .
  • the procedure splits off to YES and the predetermined value T 2 is then assigned to the Temp at step 140 .
  • the temperature correction value TempC is zero immediately after the activating of the control device 7 ; therefore, at step 138 the value TempM detected by means of the temperature sensor 75 is assigned to the control temperature Temp. After that, when the key switch 110 is turned on the temperature correction value TempC increases by increments of the predetermined value T 1 for each time a predetermined duration of time Time 1 elapses. At step 138 the control temperature Temp drops as this temperature correction value TempC increases. Note that at steps 139 and 140 the control temperature Temp is clipped so that it drops only as far as the predetermined value T 2 . This situation is depicted by the timing chart of FIG. 11.
  • the coefficient setting unit 108 sets the coefficient based on the control temperature Temp calculated by means of the control temperature calculation unit 112 , and the maximum current limit value calculation unit 109 calculates the maximum current limit value Limit based on the coefficient set by the coefficient setting unit 108 .
  • Embodiment 2 of the present invention the operations as described above produce effects as follows.
  • the control temperature Temp gradually drops and the maximum current limit is relaxed in accordance with the elapsing of time from when the key switch was turned on. That is, even when a temperature inside the passenger compartment of the vehicle (i.e., an ambient temperature) rises, when the driver boards the vehicle the control anticipates that the driver will normally operate the air conditioning or open a window to lower the temperature inside the passenger compartment.
  • 150 is the number of engine rotations obtained from the engine rotation signal 4 (i.e., the engine rotation detection section); 151 is a timer for measuring a duration of time from when the number of engine rotations 150 reaches a predetermined value or greater; 152 is a control temperature calculation unit for calculating the control temperature Temp in accordance with the temperature signal 103 and the timer 151 ; 153 is a coefficient setting unit for setting a coefficient of the maximum current limit value calculation unit 109 based on the control temperature Temp and the temperature signal 103 .
  • step 132 in FIG. 10 of Embodiment 2 has been changed to step 161 . That is, the only change is that the on/off status of the key switch in FIG. 10 has been changed to the number of engine rotations being greater than/less than the predetermined value NE 1 .
  • step 174 the detected temperature and the predetermined value T 4 are compared, and if the detected temperature is greater than the predetermined value T 4 then the procedure splits off to NO and returns to step 172 . In the case when the detected temperature is less than the predetermined value T 4 the procedure splits off to YES at step 174 , and at step 175 the flag F_mode is cleared to 0, and thereafter, steps 172 to 175 are repeated.
  • FIGS. 13 and 14 The operations of FIGS. 13 and 14 are depicted as a timing chart as shown in FIG. 15.
  • the coefficient setting unit 153 sets the coefficients (1)-(3) in FIG. 16 in accordance with the control temperature Temp.
  • the coefficient (3) is selected, and as the control temperature drops the coefficient is switched from (3) to (2) to (1).
  • the coefficient setting unit 153 is configured to select coefficient (4) regardless of the control temperature Temp. This produces a result of the following operations.
  • the flag F_mode is set to 1.
  • the coefficient setting unit 153 selects the coefficient (4) in FIG. 16. This coefficient (4) is the coefficient which most quickly limits the motor current, so the rising of the temperature may be suppressed.
  • the flag F_mode is cleared to 0 and the maximum current limit value calculation which is suitable for the original control temperature Temp is reset again.
  • Embodiment 3 Operations in accordance with Embodiment 3 are as described above; therefore, in this embodiment it is forecast that the ambient temperature (i.e., the temperature inside the passenger compartment) will drop due to operation of the air conditioner or such when the driver boards the vehicle and starts the engine, and the maximum current calculation is performed in accordance with that effect. Accordingly, unnecessary limitation of the current is not performed, so the overall control is pleasant in feeling. Additionally, in a case when the temperature rises and the temperature detected by target current temperature sensor 75 rises in contrast to the forecast that the temperature would drop, it is possible to force a switch of the control coefficient and urge the system to perform the calculation of the maximum current limit value so as to immediately suppress the rising of the temperature.
  • the ambient temperature i.e., the temperature inside the passenger compartment
  • FIG. 17 is a control block diagram of Embodiment 4, in which the engine rotation signal 150 of the control block of Embodiment 3 shown in FIG. 12 is changed to a vehicle speed 101 .
  • FIG. 18 is a flow chart of this Embodiment 4 in which the step 161 of Embodiment 3 shown in FIG. 13 has been changed as indicated at step 191 .
  • Embodiment 3 the timer begins operating from the time of the starting of the engine; however, in Embodiment 4 the timer only begins operating from the time when the vehicle speed 101 becomes greater than a predetermined value of SP 1 . Therefore, Embodiment 4 operates as shown in the timing chart of FIG. 19.
  • FIG. 20 is a control block diagram of Embodiment 5, in which the engine rotation signal 150 of the control block of Embodiment 3 shown in FIG. 12 is changed to a torque 102 .
  • the control temperature calculation unit 152 clears the flag F_TRQ to zero.
  • step 202 an absolute value of the torque signal 102 and a predetermined value TRQ 1 are compared against each other, and in the case when the absolute value of the torque is less than the predetermined value TRQ 1 the procedure splits off to NO and returns to step 202 . In the case when the absolute value of the torque is greater than the predetermined value TRQ 1 the procedure splits off to YES, and at step 203 the flag F_TRQ is set to 1 and the procedure returns to step 202 .
  • step 161 of the flow chart of FIG. 13 of Embodiment 3 has been changed to step 204 .
  • the flag F_TRQ remains set at 1 thereafter even if the absolute value of the torque drops below the predetermined value of TRQ 1 .
  • the flag F_TRQ is set to 1 the procedure splits off to YES at step 204 , and the timer 151 performs its incremental operation. This enables operations as depicted in the timing chart of FIG. 23.
  • FIG. 24 is a control block diagram of Embodiment 6, in which the engine rotation signal 150 of the control block of Embodiment 3 shown in FIG. 12 is changed to a motor current Imd.
  • the control temperature calculation unit 152 clears the flag F_Im to zero.
  • the motor current Imd obtained through the timer 151 and a predetermined value Imd 1 are compared against each other, and in the case when motor current Imd is less than the predetermined value Imd 1 the procedure splits off to NO and returns to step 212 . In the case when the motor current Imd is greater than the predetermined value Imd 1 the procedure splits off to YES, and at step 213 the flag F_Im is set to 1 and the procedure returns to step 212 .
  • step 161 of the flow chart of FIG. 13 of Embodiment 3 has been changed to step 214 .
  • control block diagram of this Embodiment 7 is the same as the diagram used in connection with the above-mentioned Embodiment 1.
  • Embodiment 7 differs from Embodiment 1 only with respect to temperature detection 103 .
  • the control device 7 has each of the circuits shown in FIG. 2 other than the motor drive circuit 77 built therein. Due to this, when an electrical power source is turned on for the control device 7 the temperature of the control device 7 rises even if the motor current is not flown (hereinafter, this is referred to as self-generation of heat). When the temperature sensor 75 is installed to the inside portion of the control device 7 the temperature detected by the temperature sensor 75 rises due to the self-generation of heat, and it becomes impossible to accurately detect the ambient temperature.
  • Embodiment 7 the coefficient is set using the temperature immediately after activation. Immediately after activation there is almost no self-generation of heat; therefore, the detected temperature is the same as the ambient temperature. Therefore, it becomes possible to set the coefficient in accordance with the ambient temperature.
  • Embodiment 7 the temperature that was measured once at the time of activation is held; however, it is also possible to hold a value of an average temperature during a fixed period of time after activation when the influence of the self-generation of heat is small, and the coefficient for the calculation of the maximum current limit value may be set according to this held temperature.
  • FIG. 29 is a diagram depicting a construction of a control apparatus according to Embodiment 8 of the present invention.
  • the same reference numerals as those in FIG. 2 refer to parts which are the same as in Embodiment 1; therefore, explanation will be made of parts other than these.
  • reference numeral 80 is a power circuit (a part of a power supply holding unit).
  • FIG. 30 is a diagram depicting an interior construction of the current according to Embodiment 8.
  • Q 1 , Q 2 and Q 3 are transistors, and 81 is a 5- volt power circuit for generating a steady 5 volts of voltage from a battery voltage VB (12 volts) obtained through the transistor Q 3 .
  • a construction such as that of FIG. 30 enables a key switch 5 to turn on, and when the transistor Q 1 is turned on or the transistor Q 2 is turned on by means of a signal (VCONT) outputted from the micon 79 , the transistor Q 3 is turned on and the battery voltage VB is supplied to the 5-volt power circuit 81 . Accordingly, it becomes possible for the 5-volt power circuit 81 to supply 5 volts of electrical voltage Vcc to the micon 79 .
  • step 231 the power supply holding unit (not shown; i.e., the part of the power supply holding section) inside the micon 79 performs an on/off determination of the key switch 5 based on information outputted from the key switch I/F circuit in FIG. 29. If the key switch 5 is on, then the procedure splits off to YES at step 231 . After splitting off to YES at step 231 , the VCONT signal being outputted from the micon 79 is set to high at step 234 and the transistor Q 2 is turned on. After that the procedure returns to step 231 .
  • the value detected by the temperature sensor 75 and a predetermined value T 5 are compared against each other, and in the case when the detected temperature is greater than the predetermined value T 5 the procedure splits off to YES and the transistor Q 2 is turned on at step 234 . In the case when the detected temperature is less than the predetermined value T 5 the procedure splits off to NO at step 232 and the transistor Q 2 is turned off at step 233 . After that, the procedure returns to step 231 and the same processing is repeated.
  • the power supply holding section which is constructed of the power circuit 80 and the power supply holding unit inside the micon 79 , holds the electrical source Vcc (5 volts) for the micon 79 until the temperature detected by the temperature sensor 75 drops below the predetermined value T 5 .
  • Embodiment 8 When Embodiment 8 is joined together with Embodiment 3, for example, the following effects are obtained. According to Embodiment 3, when the engine starts it is considered that the driver has boarded the vehicle, and the process is performed for gradually lowering the control temperature Temp. Accordingly, even in the case when the temperature detected by the temperature sensor 75 is high the control temperature Temp is dropping. Therefore, the limit set by the maximum current limit value calculation is relaxed, and good electrical power steering may be realized. However, when the key switch 5 is turned off while the temperature detected by the temperature sensor 75 is still high and the electrical source of the control device 7 is cut off and then the system is immediately reactivated, the micon 79 performs processing once again from the beginning. Accordingly, control is started once again beginning with the high temperature detected by the temperature sensor 75 , which is not desirable.
  • the control device 7 continues performing control when the temperature detected by the temperature sensor 75 is still high after the key switch is turned off. Even if the key switch is turned off and then immediately turned on, the control device 7 does not perform processing again from the beginning. Therefore, the maximum current limit value calculation is not performed using a high temperature. Additionally, after the key switch is turned off, if the temperature detected by the temperature sensor 75 drops and goes below the predetermined value, T 5 then the electrical source of the control device 7 is cut off. When it is reactivated the next time the processing is performed again from the beginning; however, at this point the temperature of the temperature sensor 75 has dropped, so a current limiting value calculation is not performed using a high temperature. In this way in Embodiment 8 it is possible to avoid performing a calculation of the motor current limit value at a high temperature, so good electrical power steering may be realized.
  • Embodiment 9 the flow chart in FIG. 31 pertaining to Embodiment 8 is changed to FIG. 32.
  • step 241 the electrical source holding unit inside the micon 79 determines whether the key switch 5 is ON or OFF based key switch information inputted from the key switch I/F circuit 74 in FIG. 29, and in the case when the key switch is on the procedure splits off to NO.
  • step 242 the key off timer is cleared to zero and at step 243 the VCONT signal (high) is outputted so as to turn on the transistor Q 2 . Then the procedure returns to step 241 .
  • the key off timer is checked, and when the key off timer is below a fixed time Time 2 the procedure splits off to NO.
  • the temperature detected by the temperature sensor 75 and the predetermined value T 5 are compared against each other, and when the detected temperature is greater than the predetermined value T 5 the procedure splits off to NO and advances to step 243 .
  • step 247 when a fixed duration of time elapses after the key off timer is used to turn the key switch off, according to step 247 the transistor Q 2 is turned off and enables the control device 7 to be turned off. Because of this process, when the temperature sensor 75 fails and a state continues in which the detected temperature value exceeds the predetermined value T 5 it is still possible to cut off the electrical source and stop the control device 7 when the predetermined duration of time elapses. Therefore, even if the temperature sensor 75 fails it is possible to prevent the battery from going dead.
  • Embodiment 10 the flow chart of FIG. 13 for Embodiment 3 is altered as depicted in FIG. 33.
  • the reference numerals in FIG. 33 which are the same as those in FIG. 13 indicate processes which are the same as Embodiment 3.
  • Embodiment 10 may be applied not only to Embodiment 3, but also to Embodiments 1 and 2.
  • step 130 the control temperature calculation unit 152 performs initialization of a corrected temperature value TempC and of the timer, and then at step 251 clears an activation timer to zero.
  • step 252 a value equal to the temperature detected by the temperature sensor 75 less a correction amount COR is substituted for TempM.
  • step 253 the above-mentioned activation timer is incremented. Thereafter, the processing from step 161 to step 140 is the same as in Embodiment 3 described above, and after that, the process returns to step 252 and repeats the same processing.
  • This correction amount COR is a value which changes with time, as shown in FIG. 34, and this time is the time measured by the above-mentioned activation timer.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Steering Mechanism (AREA)
  • Steering Control In Accordance With Driving Conditions (AREA)
  • Control Of Electric Motors In General (AREA)
US09/995,675 2001-06-05 2001-11-29 Electric power steering control system Abandoned US20020179363A1 (en)

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US10/864,397 US6902028B2 (en) 2001-06-05 2004-06-10 Electric power steering control system

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JP2001169669A JP3723748B2 (ja) 2001-06-05 2001-06-05 電動パワーステアリング制御システム
JP2001-169669 2001-06-05

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US20040227481A1 (en) * 2003-05-12 2004-11-18 Denso Corporation Electric motor drive apparatus and motor-driven power steering system
FR2876650A1 (fr) * 2004-05-06 2006-04-21 Favess Co Ltd Dispositif formant direction assistee electrique.
US20060103337A1 (en) * 2003-02-20 2006-05-18 Koyo Steering Europe (K.S.E) Method of controlling motor thermal protection for an electric power steering system of a motor vehicle
US20070247766A1 (en) * 2006-04-19 2007-10-25 Mitsubishi Electric Corporation Electric power steering device
CN100393567C (zh) * 2004-05-31 2008-06-11 日产自动车株式会社 用于机动车辆的转向装置以及转向比控制方法
US20080167776A1 (en) * 2007-01-05 2008-07-10 Delphi Technologies Inc. Methods and Motor Computer Program Products for Motor Control by the Implementation of Damping for Over-Speed Conditions
US20080181786A1 (en) * 2001-11-26 2008-07-31 Meza Humberto V Pump and pump control circuit apparatus and method
US20080203690A1 (en) * 2007-02-27 2008-08-28 Honda Motor Co., Ltd. Alignment changing control device
DE102012215400A1 (de) * 2012-08-30 2014-03-06 Siemens Aktiengesellschaft Verfahren zur Bestimmung des Zustandes einer elektrischen Anlage
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US20140257642A1 (en) * 2013-03-05 2014-09-11 Jtekt Corporation Electric power steering system
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US20030079932A1 (en) * 2001-10-12 2003-05-01 Nissan Motor Co., Ltd. Steering angle ratio control system and method
US9109590B2 (en) * 2001-11-26 2015-08-18 Shurflo, Llc Pump and pump control circuit apparatus and method
US20080181786A1 (en) * 2001-11-26 2008-07-31 Meza Humberto V Pump and pump control circuit apparatus and method
US7375481B2 (en) * 2003-02-20 2008-05-20 Jtekt Europe Method of controlling motor thermal protection for an electric power steering system of a motor vehicle
US20060103337A1 (en) * 2003-02-20 2006-05-18 Koyo Steering Europe (K.S.E) Method of controlling motor thermal protection for an electric power steering system of a motor vehicle
US20040227481A1 (en) * 2003-05-12 2004-11-18 Denso Corporation Electric motor drive apparatus and motor-driven power steering system
US7164248B2 (en) * 2003-05-12 2007-01-16 Denso Corporation Electric motor drive apparatus and motor-driven power steering system
FR2876650A1 (fr) * 2004-05-06 2006-04-21 Favess Co Ltd Dispositif formant direction assistee electrique.
FR2876649A1 (fr) * 2004-05-06 2006-04-21 Favess Co Ltd Dispositif formant direction assistee electrique.
CN100393567C (zh) * 2004-05-31 2008-06-11 日产自动车株式会社 用于机动车辆的转向装置以及转向比控制方法
US20070247766A1 (en) * 2006-04-19 2007-10-25 Mitsubishi Electric Corporation Electric power steering device
US7619859B2 (en) * 2006-04-19 2009-11-17 Mitsubishi Electric Corporation Electric power steering device
US20080167776A1 (en) * 2007-01-05 2008-07-10 Delphi Technologies Inc. Methods and Motor Computer Program Products for Motor Control by the Implementation of Damping for Over-Speed Conditions
US8498781B2 (en) * 2007-01-05 2013-07-30 Steven J. Collier-Hallman Methods and motor computer program products for motor control by the implementation of damping for over-speed conditions
US7878512B2 (en) 2007-02-27 2011-02-01 Honda Motor Co., Ltd. Alignment changing control device
US20080203690A1 (en) * 2007-02-27 2008-08-28 Honda Motor Co., Ltd. Alignment changing control device
DE102012215400A1 (de) * 2012-08-30 2014-03-06 Siemens Aktiengesellschaft Verfahren zur Bestimmung des Zustandes einer elektrischen Anlage
CN103802883A (zh) * 2012-11-01 2014-05-21 三菱电机株式会社 电动动力转向控制装置以及电动动力转向控制方法
US20140257642A1 (en) * 2013-03-05 2014-09-11 Jtekt Corporation Electric power steering system
US9174668B2 (en) * 2013-03-05 2015-11-03 Jtekt Corporation Electric power steering system
US10574173B2 (en) 2016-09-02 2020-02-25 Kongsberg Inc. Techniques for limiting electrical current provided to a motor in an electric power steering system

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US20040222037A1 (en) 2004-11-11
US20040026161A1 (en) 2004-02-12
JP2002362392A (ja) 2002-12-18
US6902028B2 (en) 2005-06-07
US6860361B2 (en) 2005-03-01
JP3723748B2 (ja) 2005-12-07
DE10162207A1 (de) 2002-12-19
DE10162207B4 (de) 2007-03-29

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