JP3405293B2 - Electric power steering device for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
Equipped with an electric motor that gives assist force to dynamic operation
The present invention relates to an electric power steering device for a vehicle,
Depending on the magnitude and direction of the current flowing through the electric motor
Electric power configured to change the assist force
The present invention relates to a steering device. [0002] 2. Description of the Related Art This type of electric power steering device
Is disclosed in, for example, JP-A-4-251596.
As shown in the figure, the electric motor is
Determine the command current value to flow, and use the motor control circuit to
Assisting force by passing a current according to the command current value through the electric motor
Is to control. The device also has a motor
A resistor is connected in series with the circuit part where the motor drive current of the control circuit flows.
By connecting the anti and detecting the voltage across this resistor
The motor current is detected, and electric power is generated according to the detected motor current.
Control the amount of current flowing to the motor to prevent the electric motor from overheating
Configured to protect. [0003] However, the above-mentioned subordinates
In the future technology, the magnitude of the motor current can be detected
However, because the direction of the motor current cannot be detected,
Precise assist force control according to the direction of motor current
There is no problem. In addition, the above publication discloses an electric motor.
Current path for flowing current in a specified direction of the
Current paths for current flow in the opposite direction
Also disclosed is a technique for connecting current detection resistors in series.
The In this case, it is possible to detect the direction of the motor current.
Although it becomes possible, two new resistances are required.
There is a problem that the cost of the apparatus increases. [0004] SUMMARY OF THE INVENTION The present invention provides a command current for an electric motor.
Since the electric current according to the direction flows,
If the magnitude of the current flowing through the
It can be determined according to the command current
It was made based on the idea. And the present invention
The structural feature is that it generates torque according to the current that flows.
To detect the steering torque of the steering motor
Steering torque detection means and response to the detected steering torque
The magnitude and direction of the command currentEvery predetermined timedecide
Command current determining means and a large amount of current flowing through the electric motor;
Kiss and directionEvery predetermined timeDetecting motor current detection
Depending on the stage and the magnitude and direction of the detected current
The command currentEvery predetermined timeCommand current changing means to change
And connected to both ends of the power source and the electric motor.
The magnitude of current flowing from the same power source to the same electric motor and
Motor driving means for changing the direction, and the changed command
A current corresponding to the magnitude and direction of the current is supplied to the electric motor.
Energization control means for controlling the motor drive means to flow
And the electric power with respect to the turning operation of the steering handle.
Electric power of a vehicle that gives assist force by a dynamic motor
In the steering apparatus, the motor current detection means
Is in a circuit formed by the motor driving means and the power source.
A path through which the current flowing through the electric motor always flows
Detects the resistance connected in series and the voltage across the resistor
Means to doIncludingBased on the detected voltage
While obtaining the magnitude of the current flowing through the electric motorAbove
Previously changed by command current changing meansCommand current
Direction of current flowing through the electric motor based onAsk
The magnitude and direction of the current flowing through the electric motor
It is configured to detect the direction. According to this, at least steering torque detection
Steering torque detected by the means and motor current detection
The magnitude of the current flowing in the electric motor detected by the stage and
Command current to be sent to the electric motor according to the direction
The size and direction ofEvery predetermined timeIt is determined. Also,
The motor current detecting means is formed by the motor driving means and the power source.
Current flowing in the electric motor is always flowing.
A resistor connected in series to the
Means for detecting pressure and based on the detected voltage
While obtaining the magnitude of the current flowing through the electric motor
Previously changed by command current changing meansCommand current
Direction of current flowing through the electric motor based onSeeking
As a result, the current flowing through the electric motor every predetermined time
Detect size and direction. Accordingly, a large current flows through the electric motor.
Detects the direction and direction using only one resistor
Therefore, the cost of the apparatus can be reduced. Also general
Is in series with the path where the current flowing through the electric motor always flows.
The connected resistor is used when the drive means fails (eg
If the switching element included in the drive means
In the case where the
It is anti. For this reason, a new one is used for the motor current detection.
There is no need to provide (extra) resistance,
Cost reduction of the device is achieved. [0007] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described.
Referring to the drawings, FIG.
Outline of dynamic power steering system is shown in block diagram
This electric power steering device is
Control circuit 10 and drive connected to the electric control circuit 10
An electric control unit (EC) comprising a circuit 20
U) 25 and DC power controlled by the drive circuit 20
And a dynamic motor 30. The electric motor 30 has a steering handle (steer).
(Ring wheel) 31
To provide assist force, and through the speed reduction mechanism 32
Is attached to the steering shaft 33 so that torque can be transmitted.
The rack bar 34 is driven in the axial direction according to the rotation of the
Before being connected to the rack bar 34 via a tie rod
Steer the wheel. The steering shaft 33 has a steering torque sensor 35.
The steering torque sensor 35 is steered.
The steering torque TM acting on the shaft 33 is detected and the torque is displayed.
A steering torque signal is output. The steering torque sensor 35
The steering torque TM to be detected is determined by the driver using the steering handle 31.
Positive value when trying to turn right, left
Is configured to be negative when trying to rotate
ing. Next, the electric power stearin shown in FIG.
Details of the electric circuit of the switching device will be described with reference to FIG.
Then, the electric control circuit 10 is a microcomputer.
(CPU) 11, input interface 12, and output
Interface 13 and EEPROM 14 (Electric
al Erasable PROM) and CPU 11
Is a memory that stores programs, maps, etc.
11a is built in. The input interface 12 is connected via a bus.
Connected to the CPU 11 and the aforementioned steering torque.
Sensor 35, vehicle speed sensor 41 for detecting vehicle speed V,
An engine speed sensor 42 for detecting the gin speed NE;
And the printed circuit board disposed on the printed circuit board of the drive circuit.
Connected to board temperature sensor 23 to detect board temperature TMPBORD
The detection signal of each sensor is supplied to the CPU 11
It is like that. The output interface 13 is connected via a bus.
Connected to the CPU 11, and the drive circuit 20, and
Connected to a normally open relay 21
These guides are based on commands from the CPU 11.
A signal for changing the communication state is transmitted. Ma
The EEPROM 14 is supplied with power from the vehicle battery 50.
Store and retain data even when not supplied
Which is connected to the CPU 11 via a bus.
Hold data supplied from the CPU 11
Along with the data held in response to the request of the CPU 11
Is supplied to the CPU 11. The drive circuit 20 has a gate with an output interface.
Consisting of MOSFETs connected to each of the cases 13
Four switching elements Tr1 to Tr4 (motor driver
Stage), two resistors 20a and 20b, and the substrate temperature described above.
Degree sensor 23. One end of the resistor 20a
The upstream end of the power line L of the battery 50 mounted on both ends
Connected to the downstream terminal of the relay 21 to which the child is connected.
The other end of the resistor 20a is the switching element Tr
1 and Tr2 are connected to each source. Switching
The drains of the elements Tr1 and Tr2 are the switching elements T
The same switch is connected to the source of r3, Tr4
The drains of the transistors Tr3 and Tr4 are connected via a resistor 20b.
Is grounded. In other words, the resistors 20a and 20b are
Motor driving means (Tr1 to Tr4) and power source (battery 5
0) (ie, ground-battery 50-relay)
-21-Tr1-Tr4-Ground)
The In addition, there is no electric current between the switching elements Tr1 and Tr3.
The switching element Tr is connected to one side of the dynamic motor 30
2 and Tr4 are connected to the other side of the electric motor 30.
Yes. Both ends of the electric motor 30 are input interfaces.
The CPU 11 is connected to the power source 12.
One terminal voltage Va and the other terminal voltage Vb of the dynamic motor 30
And are to be detected. Also, on the resistor 20b
The flow side and the downstream side (both ends of the resistor 20b) are also connected to the input interface.
The CPU 11 is connected to the source 12 and the resistor 20b
Detecting upstream voltage V2 and downstream voltage V1, respectively,
The difference (V2−V1) between these is the resistance value R20 of the resistor 20b.
The motor current value IMOTR of the electric motor 30 from the value divided by b
Is supposed to be detected. With the above configuration, the drive circuit 20 (that is,
When the relay 21 is turned on (closed), the electric motor 30)
The power supply from the battery 50 can be received.
The switching elements Tr1 and Tr4 are selectively turned on (on
In the predetermined direction when the electric motor 30
When current flows, the motor 30 rotates to the right, and the steering shaft 33 moves to the right.
An assist force that rotates in the rotational direction is generated. Sui
The etching elements Tr2 and Tr3 are selectively turned on.
The electric motor 30 has a direction opposite to the predetermined direction.
When current flows, the motor 30 rotates counterclockwise and the steering shaft 33 is moved to the left.
An assist force that rotates in the rotational direction is generated. Relay 21
When the motor is off (opened), power is supplied to the electric motor 30.
The path is interrupted, and energization of the motor 30 is stopped. This
As is clear from these, the resistors 20a and 20b have no electric current.
The current flowing through the dynamic motor 30 always flows.
The The power line L of the battery 50 is operated.
Turned on (closed) or off (opened) by the driver
Changeable ignition switch (I / G switch)
One end of 22 is connected. Ignition switch
The other end of 22 is connected to the CPU 11 via the diode D1.
Interface 12, output interface 13, E
Connected to EPROM 14 and steering torque sensor 35
And the ignition switch 22 is turned on.
When power is supplied to each. The downstream side of the diode D1 is under the relay 21.
Only the current going from the flow side to the downstream side of the diode D1
Downstream of the relay 21 via an allowable diode D2.
Is connected to the side terminal and the relay 21 is turned on.
The ignition switch 22
CPU11, input interface 12, output in
Interface 13, EEPROM 14 and steering torque sensor
The power is supplied to the sensor 35. In addition,
The EEPROM 14 is C when the power is supplied.
Data can be written (stored) and read by PU11
It becomes ability. Next, the electric powers configured as described above.
Refer to FIGS. 3 to 10 for the operation of the tearing device.
I will explain. Here, FIG. 3 shows that the CPU 11 performs every predetermined time.
The main routine to be repeatedly executed in the flowchart
6 to 9 show the main routine of FIG.
Routine routines detailing some of the steps
This is shown in the chart. In addition, FIGS.
Indicates the map (table) to be used during execution of the routine
FIG. 10 shows the execution time of the main routine.
The CPU 11 executes every elapse of a predetermined time shorter than the interval.
The output processing routine is shown in the flowchart.
The First, the driver starts driving the vehicle.
The ignition switch 22 from the off state to the on state
When changing to the state, the CPU 11 does not show the initials.
A routine is executed to change the relay 21 to the ON state.
Thereafter, the CPU 11 is shown in FIG. 3 at a predetermined timing.
The main routine is started from step 300,
Proceeding to step 310, basic target current value (command current) TK
Calculate IHON. This calculation is performed by the steering torque sensor 35.
The steering torque TM detected by the vehicle speed sensor 41 and the vehicle speed sensor 41
Vehicle speed V detected and stored in the memory 11a.
Based on the basic target current map (table) shown in FIG.
The basic target current value TKIHON at that time
is there. More specifically, the basic target current map is a vehicle.
Classified by speed (in this case, low, medium, and high)
The CPU 11 detects the vehicle speed closest to the detected vehicle speed V and
Select two basic target current maps corresponding to the next closest vehicle speed
The detected steering torque TM and the steering torque indicated by the selected map.
From the relationship between the voltage and the basic target current value TKIHON,
This target current value TKIHON is obtained and compensated for the vehicle speed V.
Calculate the final basic target current value TKIHON. Next, the CPU 11 performs step 32 in FIG.
Proceed to 0 to reduce the inertia of the motor, etc.
Inertia compensation current value TKAN is calculated to improve the operation.
Specifically, the time differential value of the detected steering torque TM (dTM / d
t), the time differential value of the steering torque TM and FIG.
Corresponding to the inertia compensation current basic value TKANB shown in
Inertia compensation current basic value TKANB
From the speed V and the gain map shown in FIG.
Ink1, and the product (= k1 · TKANB)
Inertia compensation current value TKAN. Next, the CPU 11 performs step 33 in FIG.
Proceed to 0, voltage (both ends voltage) Vt of the electric motor 30,
Motor current value IMOTR which is the magnitude of the current of the motor 30
And the motor current value according to the current direction of the motor 30
Calculate signed motor current value SGNIMOTR with IMOTR
To perform the calculation. Specifically, the detailed flow chart in FIG.
As shown in the chart, the CPU 11 performs step 60.
The process starts from 0, and the process proceeds to step 605 where the electric mode is
The difference (Va−Vb) between the voltage Va and Vb at both ends of the capacitor 30 is obtained.
Therefore, this is referred to as a motor terminal voltage Vt. Then the CPU
11 goes to step 610 and the upstream voltage of the resistor 20b
The difference between V2 and the downstream voltage V1 (V2-V1) is the resistance 20b
The resistance value R20b divided by
Is set as the motor current value IMOTR. Next, the CPU 11 proceeds to step 615.
The last assist current value IFINALOLD (before)
(Command current) is greater than 0 (is positive value)
Or not). Then, in step 615, “Ye
If it is determined as “s”, the CPU 11 performs step 62.
Proceed to 0 and set the motor current value IMOTR to the sign of the electric motor 30.
Set as motor current value SGNIMOTOR with sign and step
Proceeding to 695, the present routine is terminated. On the other hand, “No” is determined in step 615.
If so, the CPU 11 proceeds to step 625,
Whether the last final assist current value IFINALOLD is less than 0
It is determined whether or not (a negative value). And the same
If “Yes” is determined in step 625, the step
Go to step 630 and add a minus sign to the motor current value IMOTR.
The value with the symbol (-IMOTOR) is the signed mode of the electric motor 30.
Set as the current value SGNIMOTOR and go to step 695
Proceed to finish this routine. In step 625, "No" is determined.
In other words, the last final assist current value IFINALOL
When D is “0”, the CPU 11 performs step 63.
Proceed to step 5, and have already been obtained by the previous execution of this routine.
The signed motor current value SGNIMOTOR is 0 or more
It is determined whether or not. Then, in step 635, “Ye
If it is determined as “s”, it is signed at step 640.
Motor current value SGNIMOTOR and motor current value IMOTR
If it is set and “No” is determined in step 635,
If the motor current value IMOTR is
Value with minus sign (-IMOTOR) as signed motor current
Set as value SGNIMOTOR, then go to step 695
This routine is finished. Next, the CPU 11 performs step 34 in FIG.
Proceed to 0, return performance of the steering wheel 31 (return to the neutral point
Mechanical friction caused by steering and steering
The handle return control current value TMOD is calculated to compensate for
Yeah. Specifically, a detailed flowchart is shown in FIG.
Thus, the CPU 11 performs the previous step in step 710
The voltage Vt between the terminals of the electric motor 30 obtained in 605, the step
The sign of the electric motor 30 obtained in steps 610 to 645
Motor current value SGNIMOTR and voltage equation (K ・ ω = V
tR ・ SGNIMOTR, where K is a constant, R is an electric motor 3
0), the rotation angle of the electric motor 30
Obtain the speed ω and multiply it by a predetermined constant to estimate the steering angular speed.
Find the constant value STRV. Next, the CPU 11 operates at step 720.
Estimated rudder angular velocity STRV and the map shown in step 720
Obtain the handle return control current basic value TMODB from the
Step 73 is the same as the estimated steering angular velocity STRV at step 730.
Find the friction compensation current basic value TMASAB from the map shown in 0
Therefore, in the following step 740, the same step 740 as the vehicle speed V
The gain k2 is obtained from the map shown in the inside. Next, the CPU 11 performs step 750.
It is determined whether or not the value of the flag FMOD is “1”. This flag
FMOD is in a state where the steering wheel 31 is returned at the value “1”.
The steering torque TM is a positive value.
There is a state where the estimated steering angular velocity STRV is negative.
It is set to “1” if it continues for a certain time, in this case
When the estimated steering angular velocity STRV is positive
Set to “0”. Similarly, the flag FMOD
TM is a negative value and the estimated steering angular velocity STRV is a positive value
Set to "1" when the state is more than a predetermined time
In this case, the estimated steering angular velocity STRV is a negative value.
Is set to "0". Then, the CPU 11 determines that the value of the flag FMOD is
In the case of “1”, the steering wheel return system in step 760
The value obtained by multiplying the basic current value TMODB by the gain k2 is
Set the dollar return control current value TMODX and the FMOD value is “0”.
In this case, the friction compensation current basic value TM is determined in step 770.
The value obtained by multiplying ASAB by gain k2
Set to stream value TMODX. Next, the CPU 11
Step to prevent sudden change of return control current value TMOD
Formula 780 (where knm1 is a constant from 0 to 1)
Is used to smooth the handle return control current value TMOD.
The correct handle return control current value TMOD is calculated. Next, the CPU 11 performs step 35 in FIG.
Proceed to 0, convergence of steering wheel at high vehicle speed, and driving
The person is steering the steering handle 31 to a predetermined angle
The feeling of response when the angle is further increased (cut) from
Calculation of damping control current value TDAMP for improvement
Do. Specifically, FIG. 8 shows a detailed flowchart.
As shown in FIG.
Judges whether the absolute value of TM is smaller than a predetermined threshold THD
However, if it is small (if “Yes” is determined),
Proceed to step 820 to estimate the steering angular velocity STRV and
Damping control current from the map shown in 820
The basic value TDAMPB is calculated. Next, the CPU 11 proceeds to step 830.
From the vehicle speed V and the map shown in step 830,
Ink 3 is calculated and this damping system is performed at step 840
Control current value TDAMPX and damping control current basic value TDAMPB
The product value of in k3. On the other hand, in step 810
If “No” is determined, in step 850,
Set the current damping control current value TDAPX to "0"
The Then, the CPU 11 performs dumping at step 860.
Step to prevent sudden change in control current value TDAMP
Calculation formula shown in 860 (where knm2 is a constant of 0 to 1)
Is used to smooth the damping control current value TDAMP.
The damping control current value TDAMP is calculated. In step 810, the steering torque
If the absolute value of TM is greater than the predetermined threshold THD,
Set damping control current value TDAMPX to “0” in step 850
The damping control value itself is the reaction force against the steering.
To improve the steering feeling
There is a real, quick and large steering handle 31
If it is necessary to steer, decrease the damping control value.
Because it is necessary to give priority to the steering
It is. Next, the CPU 11 performs step 36 in FIG.
Proceed to 0, switch on in the ECU 25 (drive circuit 20)
ECU side current for overheating protection of the switching elements Tr1 to Tr4
Calculate the limit value ILECU. Specifically, motor current value IMO
Obtain the electric motor current integrated value ISUM by pseudo-integrating TR.
Therefore, the predetermined coefficient ke3, the electric motor current integral value ISUM,
Using the substrate temperature TMPBORD detected by the substrate temperature sensor 23
And follow the prescribed formula (TMPECU = ke3 · ISUM + TMPBORD)
By performing the calculation, the switching elements Tr1 to Tr1
Estimate Tr4's estimated temperature TMPECU and estimate switching element
ECU side current limit value ILECU decreases with increasing temperature TMPECU
To decide. Next, the CPU 11 performs step 3 in FIG.
70, the motor for overheating protection of the electric motor 30
Side current limit value ILMOTR is calculated. Specifically, motor power
From current value IMOTR to heat balance current THSQIM (electric motor
Even when the power is continuously supplied to the electric motor 30, the electric motor 30
Subtracts the current value that equilibrates at a predetermined temperature below the overheating temperature)
Calculate the current IMBARA after balancing the heat balance. And
The current IMBARA after balancing this heat balance is “0” or more.
In this case, the current IMBARA is squared after balancing the heat balance
Multiplied by a predetermined positive coefficient kup
In addition to the current square integrated value SQIMSUM, the result is a new motor.
The current squared integrated value SQIMSUM is used, and the current I after balancing the heat balance
When MBARA is smaller than “0”, the same heat balance is achieved.
Multiply the value obtained by squaring the rear current IMBARA by a predetermined positive coefficient kdwn.
Value is decremented from motor current square integrated value SQIMSUM
And the result is a new motor current square integrated value SQIMSU
The current I after balancing the heat balance by performing the calculation as M
Ask for MBARA. Next, the motor current square integrated value SQIMSU
M is the motor current that decreases as the substrate temperature TMPBORD increases.
Compared with the limit judgment value ITH, the motor current square integrated value SQIMS
If UM is greater than or equal to the motor current limit judgment value ITH
Decrease the positive predetermined value α from the current motor side current limit value ILMOTR
The calculated value is used as a new motor-side current limit value ILMOTR.
Is the motor current limit judgment value ITH or less.
If it is below, current motor side current limit value ILMOTR
The value obtained by adding a positive predetermined value β to the new motor-side current limit value
Performs an operation called ILMOTR. After calculating the motor side current limit value ILMOTR,
The CPU 11 proceeds to step 380 in FIG.
Of the limit value ILECU and motor side current limit value ILMOTR, the smaller
Is set as the final current limit value ILTEMP. Next, the CPU 11 performs step 3 in FIG.
90, the final assist current value IF shown in detail in FIG.
Execute the INAL arithmetic routine. Specifically, CPU1
In step 905, the inertia compensation current value TKAN and the hand
The sum of the return control current value TMOD and the inertia / return current value TKM
The inertia is obtained by executing Step 910 to Step 925.
-The absolute value of the return current value TKM does not exceed the guard value KG.
To guard. Next, the CPU 11 performs step 930.
Basic target current value TKIHON, inertia / return current value TKM,
The sum of the ping control current value TDAMP is calculated and
Current value ICTRL and the same assist power in step 935
The absolute value of the current value ICTRL is compared with the current limit value ILTEMP.
The absolute value of the assist current value ICTRL is the current limit value ILT.
If it is larger than EMP, the same assist is made at step 940.
Determines whether the current value ICTRL is positive or negative.
In step 945, the final assist current value IFINAL is changed to the current limit value IL.
If TEMP is negative, step 950 is the last
The sign of the current limit value ILTEMP is reversed from the cyst current value IFINAL.
Value (-ILTEMP). Next, the CPU 11
960, the previous last assist current value IF described above
Write the final assist current value IFINAL obtained this time to INALOLD
After that, go to step 995 to end this routine once
To do. On the other hand, at step 935, the assist current value
Judged that the absolute value of ICTRL is smaller than the current limit value ILTEMP
When it is done, the CPU 11 makes an assist in step 955.
Current value ICTRL as final assist current value IFINAL,
The previous last assist current value as described above
Write the final assist current value IFINAL found this time in IFINALOLD
After that, proceed to step 995 to end this routine once.
End. Due to the above, there is no limit by the current limit value ILTEMP.
Determined assist current value (final assist current value) IFINAL
As well as the last final assist current value IFINALOL
D goes updated. In this way, the final assist power
When the flow value IFINAL is determined, the CPU 11 performs the step of FIG.
395 once the main routine is finished, and after a predetermined time
The routine starts again at step 300 and the final
Start updating the cyst current value IFINAL. Next, based on the final assist current value IFINAL,
Accordingly, the switching elements Tr1 to Tr4 are switched on.
The final assist current value IFINAL is applied to the electric motor 30.
Refer to FIG. 10 for a process for supplying a current corresponding to
I will explain. Note that the routine of FIG.
lse Width Modulation) control means to control
is doing. First, at a predetermined timing, the CPU 11
When processing of this routine is started from step 1000,
Proceed to step 1005 and set the value of counter n to “1”
Increase. This counter n is used to create a triangular wave.
It is used. Next, the CPU 11 performs step 10.
10 and the value of the counter n is
It is determined whether or not it is equal to the maximum value nmax.
If determined, the value of the counter n in step 1015
Is cleared to “0” and the process proceeds to Step 1020. on the other hand,
If the value of the counter n is not equal to the maximum value nmax,
In step 1010, “No” is determined, and the process proceeds as it is.
Proceed to step 1020. Next, the CPU 11 goes to step 1020.
To determine whether the value of the counter n is less than or equal to the value n1
The This value n1 is half the maximum value nmax.
In order to determine the apex of the triangular wave. Ste
If “Yes” is determined in step 1020, C
PU11 determines the value of counter n in step 1025
Multiply the value ST and use the result as the value of the first triangular wave KIJUNA
Set. On the other hand, it is determined as “No” in Step 1020.
If so, in step 1030 the maximum value nmax
A value obtained by multiplying a value obtained by subtracting the value of counter n by a predetermined value ST
Is set as the value of the first triangular wave KIJUNA. With the above processing, the value of the counter n is
As it increases by 1 between “0” and “n1”,
The value of 1 triangle wave KIJUNA is in the range of “0” to “n1 · ST”.
It increases by a predetermined value ST. The value of the counter n is “n
As it increases by 1 between 1 ”and“ nmax ”,
The value of 1 triangle wave KIJUNA is in the range of “n1 · ST” to “0”
Decrease by a predetermined value ST. Next, the CPU 11 goes to step 1035.
Leading triangular wave KIJUNA value with minus sign
(-KIJUNA) is set as the value of the second triangular wave KIJUNB.
As a result, the second triangular wave KIJUNB is paired with the first triangular wave KIJUNA.
The value changes symmetrically about the center value “0”. Next, the CPU 11 proceeds to Step 1040.
Check whether the final assist current value IFINAL is "0" or more
If it is determined that the value is “0” or more,
Steps 1045 to 1055 are executed and the final
When the assist current value IFINAL is greater than the first triangular wave KIJUNA
In this case, the switching elements Tr1 and Tr4 are turned on.
(Steps 1045 and 1050), final assist current value
Switch when IFINAL is smaller than the first triangular wave KIJUNA
The turning elements Tr1 and Tr4 are turned off (step 1).
045, 1055). And CPU11 is step
Proceed to 1060 and switch elements Tr2 and Tr3 off.
Go to step 1095 and complete this routine.
The day ends. On the other hand, in the previous step 1040, “No”.
(The final assist current value IFINAL is “0”)
If smaller, the CPU 11 performs step 1065.
Step 1075 is executed, and the final assist current
When the value IFINAL is smaller than the second triangular wave KIJUNB,
The chucking elements Tr2 and Tr3 are turned on (step 1
065, 1070), the final assist current value IFINAL is the second
When larger than triangular wave KIJUNB, switching element Tr
2 and Tr3 are turned off (steps 1065 and 10).
75). Then, the CPU 11 proceeds to step 1080.
Then, the switching elements Tr1 and Tr4 are turned off,
Proceeding to step 1095, the present routine is temporarily terminated. In this way, the CPU 11 performs the process shown in FIG.
Final assistance obtained by executing the routine
The current value IFINAL and the number that changes in a triangular waveform over time
Compare 1 triangle wave KIJUNA or 2nd triangle wave KIJUNB,
Controls the conduction state of the etching elements Tr1 to Tr4. Immediately
That is, when the final assist current value IFINAL is a positive value
The switching elements Tr1 and Tr4 are intermittently turned on or off.
Is turned off, and the switching elements Tr2 and Tr3 are
Maintained off. As a result, the electric motor 30
Is the predetermined direction and the final assist current value IFINAL is large
A current of a value corresponding to the absolute value (absolute value) is supplied, and the motor 30
Rotates clockwise to generate assist force in the same direction. Also, the final assist current value IFINAL is a negative value.
When the switching elements Tr2 and Tr3 are
It is essentially turned on or off, and the switching element Tr
1, Tr4 is maintained in the off state. This makes it electric
The motor 30 has a current in the direction opposite to the predetermined direction,
Value according to the magnitude (absolute value) of the final assist current value IFINAL
Current flows, the motor 30 rotates counterclockwise and rotates in the same direction.
Generates assist power. As you can see from this
In addition, the direction of the current flowing through the electric motor 30 is the final assist.
The current value is changed according to the current value IFINAL.
The direction of the current of the motor 30 at the time of
The direction of the final assist current value IFINAL, that is, the last final current value
It matches the direction (sign) of the cyst current value IFINALOLD.
The As described above, the implementation according to the present invention.
The electric power steering device of the form is a steering torque TM,
Basic target current value TKIHON which is command current value according to vehicle speed V
The appropriate assist force is controlled based on this value.
Yeah. In the present embodiment, the electric motor 30 is
Steering angular velocity estimation based on current magnitude and direction
The value STRV is obtained, and based on this steering angular velocity estimated value STRV,
Various control values (handle return control current value TMOD, damping
Basic control current value TKIHO
Change (correct) N. Therefore, the flow to the electric motor 30
Precise assist force control according to the current direction is achieved.
The Also, the magnitude of the current flowing through the electric motor 30
The drive means Tr1-Tr4 and the battery 5 as a power source
Is a current path formed by zero and flows to the electric motor 30
The path through which the current always flows, i.e.
The voltage across the resistor 20b connected in series to the path is detected.
And detected. On the other hand, the current flowing through the electric motor
The direction has already been sought (ie the previous main loop
Final assist current value IFINAL (ie last time)
The final assist current value of IFINALOLD is determined according to the sign of
Is done. Therefore, according to this embodiment, the drive circuit 20
For short circuit failure of switching elements Tr1 to Tr4
Of the electric motor 30 using only the necessary resistor 20b.
Detect the magnitude and direction of the current as they can be detected
No extra resistance is needed to reduce the cost of the equipment
Can be reduced. The present invention is limited to the above embodiment.
However, various embodiments of the electric power are within the scope of the present invention.
-It can be applied to a steering device. For example, the above implementation
In the embodiment, the magnitude of the current of the electric motor 30 is resistance.
It was detected by detecting the voltage across 20b
Is the voltage across the resistor 20a and the voltage upstream of the resistor 20a.
And the potential difference between the downstream side of the resistor 20b and the resistor 20b.
You can also. Also, steps 1040 to 108 in FIG.
0 makes the command current (final assist current value IFINAL) positive
Depending on the negative (sign), the switching elements Tr1 to Tr4
Which one will be turned on is uniquely determined
In addition, the conduction state of the switching elements Tr1 to Tr4 (ON
・ Off state) is detected from the gate voltage, for example, and this conduction
The sign of the motor current value IMOTR detected based on the status
The determination is also included in the present invention. In this case, all scans
There is no need to monitor the gate voltage of the switching element.
A combination of elements that sometimes does not turn on, ie, T
r1 and Tr2, Tr1 and Tr3, Tr4 and Tr2, and
What is necessary is just to detect the conduction | electrical_connection state of each element of Tr4 and Tr3.
The gate voltage is detected when each gate voltage rises.
Interrupt routine for CPU 11
Can also be done. The switching elements Tr1 to Tr4
When configured to detect the conduction state,
Switching elements to be turned on (Tr1 and Tr
4. Tr2 and Tr3) must not be on at the same time
(One is on and the other is off) is detected
Switch that does not turn on at the same time
Elements (Tr1 and Tr2, Tr1 and Tr3, Tr4 and
Tr2 and Tr4 and Tr3) are simultaneously turned on.
Is detected, the corresponding switching element is
You may comprise so that it may determine with it being normal. Furthermore, in the above embodiment, the motor power
The flow PI control is not performed, but more stable assist
PI control can also be employed for force control.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of an electric power steering apparatus according to an embodiment of the present invention. 2 is an electric circuit diagram of the electric power steering apparatus shown in FIG. 1. FIG. 3 is a flowchart showing a program (a main routine for determining a command current) executed by the CPU shown in FIG. 2. FIG. FIG. 4 is a map (table) of basic target current values. FIG. 5A is a map of an inertia compensation current basic value;
(B) is a map of the gain. 6 is a flowchart showing a program (a routine for determining a signed motor current value) executed by the CPU shown in FIG. 2; FIG. 7 is a program executed by the CPU shown in FIG. 2 (routine for determining a handle return control current value).
It is a flowchart which shows. FIG. 8 is a flowchart showing a program (a routine for determining a damping control current value) executed by the CPU shown in FIG. 2; FIG. 9 is a flowchart showing a program (a routine for determining a motor current final output value) executed by the CPU shown in FIG. 2; 10 is a flowchart showing a program executed by the CPU shown in FIG. 2 (a routine for performing an output process for controlling the conduction state of the switching element). DESCRIPTION OF SYMBOLS 10 ... Electric control circuit, 11a ... Memory, 20 ... Drive circuit, 21 ... Relay, 22 ... Ignition switch, 2
DESCRIPTION OF SYMBOLS 3 ... Board | substrate temperature sensor, 30 ... DC electric motor, 31 ... Steering handle, 32 ... Deceleration mechanism, 33 ... Steering shaft, 35 ... Steering torque sensor, 50 ... Battery, Tr1-Tr4 ... Switching element.

──────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ identification symbol FI B62D 127: 00 B62D 127: 00 (58) Field surveyed (Int.Cl. ⁷ , DB name) B62D 5/04 B62D 6/00

Claims (1)

(57) [Claims] [Claims] [Claim 1] An electric motor that generates torque according to a current that flows, steering torque detection means that detects steering torque of a steering wheel, and according to the detected steering torque Command current deciding means for deciding the magnitude and direction of the command current every predetermined time, and the magnitude and direction of the current flowing through the electric motor at a predetermined time
Motor current detecting means for detecting every interval, command current changing means for changing the command current at predetermined times according to the magnitude and direction of the detected current, and connected to both ends of the power source and the electric motor. And a motor driving means for changing the magnitude and direction of a current passed from the same power source to the same electric motor, and the motor so that a current corresponding to the changed magnitude and direction of the command current is passed to the electric motor. An electric power steering device for a vehicle that includes an energization control unit that controls a driving unit, and applies an assisting force to the turning operation of the steering handle by the electric motor. The motor current detecting unit includes the motor driving unit. And a resistor connected in series to a path through which a current flowing through the electric motor always flows in a circuit formed by the power source and the power source. The instruction together and means for detecting a voltage, determine the magnitude of current flowing through the electric motor based on the detected voltage
Based on the direction of the changed previous command current by the current changing means determining the direction of the current flowing in the electric motor
To determine the magnitude and direction of the current flowing in the electric motor.
An electric power steering device configured to detect .