JP2001315654A - Electric power steering control device and current characteristic adjusting device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor-driven power steering control device capable of correcting the dispersion of a motor current detection characteristic easily with accuracy. SOLUTION: This electric power steering control device is provided with a rewritable nonvolatile memory 23 stored with a coefficient for the correction of a current detection value, and constituted to correct the current detection value by multiplying the current detection value detected by a current detecting circuit 19, by the coefficient by the processing of a control circuit 13. The dispersion of the motor current detection characteristic can thereby be corrected easily with accuracy by correcting the data of the coefficient if necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device (a control device called an EPS controller or the like) in an electric power steering system (EPS system) of a vehicle, and more particularly to an electric power control system in which a variation in a motor current detection characteristic can be easily corrected. The present invention relates to a power steering control device and a current characteristic adjustment device thereof.

[0002]

2. Description of the Related Art In general, an electric power steering system used in a small vehicle such as a mini car detects a steering torque generated on a steering shaft by operating a steering wheel with a torque sensor, and forms a unitized control device (EPS controller). Under the control of (1), a steering assist torque is generated by flowing a current from a battery of a vehicle to an assist motor (hereinafter, sometimes simply referred to as a motor in some cases) attached to a steering shaft or the like in accordance with a detection value of a torque sensor. And, in the current control of the motor by the control device, an H-bridge circuit usually composed of four FETs (field effect transistors) is used,
This H is controlled by a control circuit including a microcomputer.
PWM motor via drive circuit consisting of bridge circuit
(Pulse width modulation) driving is generally used. Specifically, the control device includes, in addition to the drive circuit, a current detection circuit that detects a motor current, and a control circuit that calculates and determines a target current value as needed according to a detection value of the torque sensor. Then, a current detection value output from the current detection circuit matches the target current value,
The control circuit is configured to feedback-control the operation state (including the duty ratio of the PWM drive) of each FET of the drive circuit. Further, the current detection circuit includes:
For example, as shown by reference numeral 19 in FIG. 4A, a shunt resistor (current) connected in series to a current supply line L2 of the motor (a path through which a motor current flows; in this case, a current supply line between the drive circuit and the ground). Low resistance for detection) 20
And an amplifier circuit (analog operation circuit) 21 for calculating and amplifying the voltage between both terminals of the shunt resistor 20.

[0003]

The elements (the OP amplifier IC 22 and its peripheral resistors) constituting the shunt resistor 20 and the amplifier circuit 21 vary in the performance of each product, and the actual motor current As shown in FIG. 4B, the output voltage characteristic of the current detection circuit 19 with respect to
Variations occur in individual products with respect to ideal characteristics. The variation in the current detection characteristics is an error (error with respect to the actual motor current) of the current detection value (feedback value) grasped by the control circuit (indicated by reference numeral 13 in FIG. 4A). Even if the drive circuit is properly controlled based on the current detection value, there is a problem in that the motor current that matches the target current value does not actually flow, and the steering assist torque varies from product to product. Note that the steering assist torque in a vehicle power steering system has a large effect on the steering performance, which is an important factor that affects the vehicle quality. Therefore, in this type of system, the steering torque (the value detected by the torque sensor) is the same. However, various control measures such as slightly changing the steering assist torque (the target current value) depending on the running state (for example, the vehicle speed) are usually performed. However, even if the above-described variation is slight, the effect of such a contrivance is deteriorated, and a desired steering feeling may not be achieved.

To solve this problem, as shown in FIG. 4A, a voltage correction circuit 2 composed of voltage dividing resistors R1 and R2 is used.
3 is provided on the output side of the current detection circuit 19, and the circuit constants are adjusted one by one at the time of shipment of the control device (that is, the voltage dividing resistor R1 or R2 is changed to one having a different resistance value as necessary). Therefore, there is a method of correcting the variation of the current detection characteristics. However, in this method, a check is performed to determine whether the detected current value is appropriate. If necessary, the circuit constant is adjusted, and then a check is performed again to determine whether the detected current value is appropriate. If necessary, it is necessary for the operator to repeat troublesome manual work for each unit, such as performing the adjustment work of the circuit constant again, and the productivity is significantly reduced. Further, since fine adjustment is difficult, there may be a problem that the above-described variation in the steering assist torque cannot always be sufficiently corrected. Therefore, an object of the present invention is to provide an electric power steering control device capable of easily and accurately correcting variations in current detection characteristics and a current characteristic adjustment device thereof.

[0005]

SUMMARY OF THE INVENTION An electric power steering control device (hereinafter sometimes simply referred to as a control device) according to the present invention is connected to a steering system of a vehicle and drives an assist motor for generating a steering assist torque. A drive circuit, a current detection circuit that outputs a current detection value according to a motor current flowing through a current supply line of the assist motor, and the motor so that the steering assist torque becomes a value corresponding to a steering torque of the steering system. A control circuit that determines a target current value of the current as needed and controls the drive circuit so that the current detection value matches the target current value. And correction means for multiplying the current detection value by a coefficient stored in the nonvolatile memory to correct the current detection value. Those digits. Here, for example, an EEPROM can be used as the “non-volatile memory”. Further, the “control circuit” can be configured by a circuit including a microcomputer (hereinafter, referred to as a microcomputer), for example. The "correction means" can be realized, for example, as an arithmetic function of a control circuit. That is, for example, as a content of a control process realized by a microcomputer constituting the control circuit and its operation program, the current detection value input from the current detection circuit is multiplied by the coefficient, and the multiplication result is used as a feedback value in the drive operation. What is necessary is just to employ | adopt the structure used for the control processing of a circuit. However, in this case, if necessary, means (for example, A) for converting a raw signal (normally, an analog value) of the current detection value input from the current detection circuit into a form that can be handled by information processing in the control circuit (for example, A / D converter).

According to the present invention, at least a variation in the current detection characteristic of the current detection circuit can be easily corrected by changing (rewriting) the coefficient stored in the nonvolatile memory. At least, the extremely troublesome work of replacing the voltage dividing resistor R1 or R2 as in the case of providing the above-described voltage correction circuit 23 does not occur at all, so that the productivity of the control device (EPS controller) is significantly improved. Further, by making the change width of the coefficient sufficiently small, fine adjustment is possible, and the characteristics of the control device including the current detection characteristics are accurately corrected, and the characteristics of the steering assist torque in the electric power steering system are always optimized. As a result, it can contribute to stabilization of high quality (steering feeling) of the vehicle. The coefficient is
An initial value is set to, for example, “1”, and in that state, a test for determining a variation in the detected voltage characteristic is performed. Depending on the test result, a value slightly larger than “1” or a value slightly smaller than “1” is corrected. I just need. Specifically, for example, when an adjustment load equivalent to the motor is connected to the control device, and the specified torque signal (may be a pseudo signal) is input to the control device, the motor is energized. The actual current flowing in the line is accurately measured by a current measuring means for inspection, and the measured current value coincides with a target current value (ideal current value determined as a design value) corresponding to the prescribed torque signal. Compare whether or not. And
If they match within the allowable error range, the coefficient remains at the initial value (for example, “1”). If they do not match, a value that can correct the difference (specifically, measured current value / target current value) Value) may be replaced with the coefficient data.

Further, a more preferable configuration of the present invention is a configuration in which the control device has a communication unit for rewriting the coefficient data in the nonvolatile memory according to a signal input from the outside. With this configuration, the coefficient data can be easily rewritten by connecting an input device having a communication function corresponding to the communication means to the control device and operating the input device, for example (for example, the nonvolatile memory). This eliminates the need for the troublesome work of removing the non-volatile memory from the board of the control device and rewriting data with a dedicated writer.) Here, the “communication means” specifically includes, for example, a communication function of a control circuit and a hardware configuration therefor (a communication cable connection terminal connected to a communication port of the control circuit, or an infrared signal transmission / reception means). Can be realized by The communication method of the “communication means” is not particularly limited, and various known methods can be adopted.
Wireless communication (for example, infrared communication) that is widely used in personal computer LAN systems and the like can also be used.

A current characteristic adjusting device for an electric power steering control device according to the present invention is a device for adjusting the coefficient data of the control device of the present invention to an appropriate value.
Torque signal output means capable of outputting the steering torque signal to the control device; an adjustment load corresponding to the assist motor; current measurement means for measuring a current flowing through the adjustment load; In the operating state in which a signal is output from the torque signal output means, a current measurement value of the current measurement means is read, and the current measurement value is a specified allowable error range with respect to a target current value corresponding to the specified torque signal. Control processing means for outputting a signal for rewriting the coefficient data in the non-volatile memory to predetermined data via the communication means as necessary. Here, “adjustment load” is
For example, it may be a motor equivalent to the assist motor, a circuit equivalent to the assist motor, or the assist motor itself. The "torque signal output means" is a means for outputting a signal equivalent to a torque sensor for detecting steering torque. For example, in the case of a torque sensor comprising a potentiometer, a potentiometer equivalent thereto can be used. The “specified torque signal” is a torque detection signal corresponding to a steering torque set in advance for inspection for adjustment, and a specific numerical value (magnitude of the torque signal) is not particularly limited. From the viewpoint of improving the accuracy of the target current value, as shown in an embodiment described later (point A in FIG. 2B), the target current value (FIG.
It is preferable that the point (b) in (b) is as large as possible and the target current value is clear. The "adjustment control processing means" can be constituted by a processing device including a microcomputer, for example. When the "torque signal output means" is constituted by, for example, a potentiometer, the rotor of the potentiometer is driven and controlled by a servomotor or the like controlled by the above processing device, and a signal corresponding to the "specified torque signal" is obtained. (In this case, terminal voltage) can be output from the potentiometer.

According to the present invention, if the current characteristic adjusting device is connected to the control device and the current characteristic adjusting device (particularly, the adjusting control processing means) is activated, the adjusting control processing means can be used. By the function, the above-described inspection and the adjustment of the coefficient are automatically performed, and the coefficient is adjusted to an optimum one. That is, when the current characteristic adjusting device is activated, the adjusting control processing means causes a specified torque signal to be output from the torque signal output means, and a predetermined operating state (the control circuit of the control device having received the specified torque signal outputs the specified torque signal). (A steady state in which the drive circuit is controlled so that the corresponding target current value flows to the adjustment load). Then, in this operating state, the adjustment control processing means reads the current measurement value of the current measurement means, and the current measurement value is within a prescribed allowable error range with respect to the target current value corresponding to the prescribed torque signal. And outputting a signal for rewriting the data of the coefficient in the nonvolatile memory to predetermined data via the communication means as needed so that the data match. Therefore, the coefficient is
Automatic adjustment is performed so that the actual motor current matches a predetermined target current value corresponding to the steering torque within an allowable error range. Therefore, troublesome manual work as described above is not required at all, and the productivity of the control device can be greatly improved.

The initial value of the coefficient should preferably be set to "1". If the coefficient is "1", the current detection value, which is the output value of the current detection circuit, is used as it is in the control circuit as a feedback value, and the variation in the current detection characteristics of the current detection circuit indicates the difference between the current values (as described above). This is because the difference between the target current value and the current measurement value) appears. In addition, when the initial value of the coefficient is “1”, the “predetermined data” preferably divides the measured current value read in the operating state by a target current value corresponding to a prescribed torque signal. (Current measured value / target current value). In this case, by multiplying the detection value (current detection value) of the current detection circuit by a coefficient corresponding to the ratio of the current measurement value (actual motor current) to the target current value,
This is because variations in current characteristics of the control device including variations in current detection characteristics are canceled. In this case, the adjustment is easily completed by one data rewrite. The “predetermined data” may be data obtained by increasing or decreasing the coefficient data at that time by a predetermined change width. That is,
If the actual current (measured current value) is larger than the target current value, for example, the data of the coefficient is increased by a predetermined range to correct the difference, and then the current measurement is performed again. A configuration in which the value is read and the process of increasing the coefficient data again as needed may be repeated.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, an example of a hardware configuration of the electric power steering device will be described with reference to FIG. The present device includes an assist motor 11 (hereinafter, sometimes simply referred to as a motor 11 in some cases) connected to a steering system of a vehicle to generate a steering assist torque, and a drive circuit 12 (H
And a power supply circuit 15 for supplying predetermined power to the control circuit 13 based on the output of a power supply (battery) 14 of the vehicle.
And a torque sensor 1 for detecting a steering torque of the steering system
6 is provided.

In FIG. 1, reference numeral 17 denotes an ignition switch of the vehicle, which functions as a start switch of the control circuit 13 in the present apparatus. Reference numerals 18a and 18b denote electromagnetic relays (more precisely, contact points of the electromagnetic relays). The coils of these electromagnetic relays are driven and controlled by the control circuit 13 via a circuit not shown. I have. In FIG. 1, reference numeral 19 denotes the current detection circuit described with reference to FIG. 4A, and the shunt resistor 20 and the OP amplifier IC 22
And an amplifier circuit 21 including Shunt resistor 20
Is a ground side of the bridge circuit 12a (that is, an energizing line L2 between the bridge circuit 12a and the negative electrode of the power supply 14).
The voltage corresponding to the voltage drop of the shunt resistor 20 is calculated and amplified by the amplifier circuit 21 and input to the control circuit 13. here,
The output of the amplifier circuit 21 (analog signal of the current detection value) input to the control circuit 13 is converted into a digital signal by an A / D converter 13 a provided in the control circuit 13, and further converted into a digital signal in the control circuit 13 described later. After being multiplied by a predetermined coefficient (to be described in detail later) by a calculation process of the microcomputer, the multiplication is used as a feedback value of the motor current control. Further, in FIG.
Reference numerals 3, 24, and 25 denote a nonvolatile memory, a communication I / F (interface) circuit, and a communication terminal, respectively, as peripheral elements of the control circuit. The driving circuit 1
2, control circuit 13, power supply circuit 15, current detection circuit 19,
The non-volatile memory 23, the communication I / F circuit 24, the communication terminal 25, and the like are provided in a set of housings (inside or on a wall surface) and are unitized. EPS control unit,
Alternatively, it is called an EPS controller and corresponds to a power steering control device of the present invention).

In this case, the drive circuit 12 includes four field effect transistors SW1 to SW4 (hereinafter referred to as FETS).
W1 to SW4) are connected to the motor 11 in the form of an H-bridge.
Each of the FETs SW1 to SW4, which are switching elements of the H-bridge circuit 12a, is operated by a PWM drive signal (or a simple ON / OFF drive signal) output from the control circuit 13. Note that each of the FETs SW1 to SW
4 is an N-channel enhancement type MO in this case.
This is an SFET, and diodes D1 to D4 (parasitic diodes) are formed between the drain and the source due to its structure. The electromagnetic relay 18a (relay A) is provided on the power supply line L1 between the bridge circuit 12a and the positive electrode of the power supply 14, and controls the control circuit 13 in order to prevent an overcurrent in the event of an abnormality (such as when the FET is turned on). Control, the current supply line L1 is cut off. Also, the electromagnetic relay 18b
The (relay B) is provided on one energizing line L3 between the bridge circuit 12a and the motor 11, and a control circuit 13 is provided to prevent an increase in required steering force due to regenerative current (so-called regenerative lock) when the FET is turned on. Control, the current supply line L3 is turned off.

The control circuit 13 is composed of a circuit including a microcomputer, and generates a steering assist torque corresponding to a steering torque detected from a detection signal of the torque sensor 16 (or a detection value of a vehicle speed sensor not shown). For this purpose, the target current value according to the steering torque and the like is determined as needed according to a preset characteristic diagram (in this case, for example, shown in FIG. 2B), and the current detection value (motor current feedback value) is determined. ) Matches the target current value,
It has a function of generating a drive signal for each of the FETs SW1 to SW4 and controlling the H-bridge circuit 12a. The control circuit 13 uses the A / D converter 1 as the current detection value (motor current feedback value) used in drive control of the drive circuit 12 (ie, motor current control).
The value after correction by multiplying the output value of 3a by the coefficient data (“1” or a value close thereto) stored in the nonvolatile memory 23 is always used. That is, the control circuit 13 in this case is configured to also function as the correction unit of the present invention. Further, the control circuit 13 has a function of communicating with an external device having a corresponding communication function via the communication I / F circuit 24 and the communication terminal 25. 23 has a function of rewriting the data of the coefficient. That is, in this case, the control circuit 13, the communication I / F circuit 24, and the communication terminal 2
Reference numeral 5 constitutes the communication means of the present invention. Note that the communication terminal 25 in this case is a terminal constituting a connector for connecting a communication cable. In addition, the nonvolatile memory 23
Is a rewritable memory that stores data even when the power is turned off, and is, for example, an EEPROM. Note that the nonvolatile memory 23 and the communication I / F circuit 24
It may be built in the control circuit 13.

The power supply circuit 15 changes the voltage of the battery 14 (normally, 12 V to 14 V) to a predetermined voltage (for example, 5 V).
V) and supplies it to the control circuit 13. In this case, the torque sensor 16 includes a potentiometer that detects a torsion angle of a steering shaft of the vehicle as a steering torque. Note that a relay such as the electromagnetic relay 18a is usually always provided, but a relay such as the electromagnetic relay 18b is not necessarily required, and when the above-described regenerative lock does not pose a problem (for example, the motor 1
Even if both ends of the coil 1 are in a connected state, if the handle can be operated to rotate somehow, this is unnecessary. Also,
Although not shown, the control device 30 includes, in addition to the above-described elements, an electrolytic capacitor that backs up a power supply when the current of the motor 11 (hereinafter, sometimes simply referred to as a motor current) increases, and a noise emission. A ceramic capacitor or a choke coil for suppressing radio waves is provided.

Next, an embodiment of the current characteristic adjusting device for adjusting the coefficient data to an appropriate value in the control device 30 will be described. FIG. 2A shows the control device 30 (E
FIG. 3 is a block diagram showing a state where a PS controller (PS controller) is connected to a current characteristic adjusting device 40 of the present example. This FIG. 2 (a)
As shown in FIG. 7, the current characteristic adjusting device 40 of the present embodiment includes a pseudo torque sensor 41 (torque signal output means) capable of outputting a steering torque signal to the control device 30 and a pseudo load motor corresponding to the assist motor 11. 42 (adjustment load)
A current sensor 43 (current measuring means) for measuring a current flowing through the pseudo load motor 42;
1 as well as an inspection device 44 (adjustment control processing means) which reads the current measurement value by the current sensor 43 and adjusts the coefficient data of the control device 30. Here, the pseudo load motor 42 is, for example, a motor equivalent to the assist motor 11. In this case, the pseudo torque sensor 41 is a potentiometer whose rotor is driven by a servo motor (not shown).

The inspection device 44 is a processing device including, for example, a microcomputer. The inspection device 44 controls the servomotor described above to drive and control the rotor of the potentiometer constituting the pseudo torque sensor 41, and outputs a specified torque signal (in this case, FIG.
The potentiometer has a function of outputting a terminal voltage corresponding to the voltage at the point A shown in FIG. 3B from the potentiometer. The communication I / F circuit 24 and the like described above are also connected to the control circuit 13 of the control device 30. It has the function of communicating via The inspection device 44 has a function of outputting a signal (pseudo signal) of the vehicle speed sensor to the control circuit 13 of the control device 30 in some cases.
2B is realized in a pseudo manner, and the adjustment of the coefficient data in the nonvolatile memory 23 is automatically performed. The data of the characteristic diagram as shown in FIG. 2B is naturally registered in a ROM or the like in the control circuit 13 of the control device 30. In this case, at least the data corresponding to the point A in FIG. Data of the current at the point B (the target current value corresponding to the point A) and the like are registered in advance in a storage unit (not shown) in the inspection device 44.

FIG. 3 is a flowchart showing an example of the processing contents (adjustment operation procedure of the coefficient data) of the inspection device 44. Hereinafter, this will be described. The inspection device 44 is powered on and connected to devices such as the predetermined control device 30 and the pseudo torque sensor 41 as shown in FIG. , A mouse or the like), the processing of FIG. 3 is executed. First, in step S1, the coefficient data in the nonvolatile memory 23 of the control device 30 is read by the communication function described above, and it is confirmed that the value is "1". If the value is not "1", rewriting for correcting the value to "1" is performed, and then the process proceeds to the next step S2. Next, in step S2, the pseudo torque sensor 41 (potentiometer) is controlled so that the torque signal at point A in the characteristic diagram shown in FIG. That is, the control device 3
0 is performing current control considering vehicle speed),
A signal of the vehicle speed corresponding to the characteristic diagram shown in FIG. 2B is input to the control circuit 13 of the control device 30, and the operation state of the control device 30 specified at the point A in FIG. FIG.
(Maximum current output state in the characteristic of (b)).

In step S3, the current measured value detected by the current sensor 43 (after the pseudo load motor 42 in the above-mentioned operation state) is passed after an appropriate standby time as necessary so that the above-mentioned operation state is stabilized. Read the actual current value). Note that this measured current value (hereinafter referred to as a point B read value) is ideally a prescribed target current value corresponding to the point A (ie, the current at the point B in FIG. 2B). (Referred to as the B point default value), but in practice, the value is slightly deviated from the B point default value due to the variation in the characteristics of the control device 30 including the variation in the current detection characteristics described above. . Next, in step S4, the B-point read value and the B-point default value are compared, and it is determined whether or not the difference between these current values is within a specified allowable error range. In other words, it is determined whether or not the point B read value read in step S3 falls within a specified current range centered on the point B default value. And
If it is within the range, there is no need to modify the coefficient, so this processing ends. If it is not within the range, the process proceeds to step S5.

In step S5, a calculation of K = read value of point B / predetermined value of point B (= current measurement value / target current value) is performed, and the coefficient is stored in the nonvolatile memory 23 of the control device 30 by the communication function. The data is rewritten to the value of K. If the coefficient data is rewritten to K, for example, when the read value of the point B (measured current value) is larger than the predetermined value of the point B (target current value), the output value of the current detection value increases by that ratio. After the correction, the current is used as a feedback value in the above-described current control. Therefore, the drive signal of the drive circuit 12 is corrected so that the actual current decreases by that ratio, and the B-point read value (current measured value) Theoretically coincides with the B point predetermined value (target current value). Next, in step S6, while maintaining the above-described operation state (however, the coefficient is in the state of K), as in step S3,
The measured current value (B) detected by the current sensor 43
Read the point reading value) again. Thereafter, in step S7, the same comparison determination as in step S4 is performed again. If the read value of point B obtained in step S6 is within the specified current range, the correction is properly terminated and the present process is terminated. If not, the process proceeds to step S8. In step S8, correction of the coefficient (control device 30
(Adjustment of the characteristic variation) cannot be properly performed, and therefore, for example, control of some output (display on a display, lighting of a lamp, output of a buzzer sound) for notifying the inspector or the like of the fact. Processing (inspection NG processing)
Is executed.

According to the current characteristic adjusting device 40 described above, the current characteristic adjusting device 40 is connected to the control device 30, and the current characteristic adjusting device 40 (in particular, the inspection device 4) is connected.
If 4) is activated and the above-described processing operation of the inspection device 44 is executed, the inspection as to whether the coefficient needs to be adjusted (corrected) and the adjustment of the coefficient as needed are automatically performed. Thus, the coefficient is adjusted to an optimum one. Therefore, troublesome manual work as described above is not required at all, and the productivity of the control device 30 can be greatly improved. Also,
By making the change width of the coefficient sufficiently small (that is, in this case, by sufficiently increasing the number of digits (bit number) of the coefficient data), fine adjustment can be performed, and the control device including the current detection characteristics can be finely adjusted. 30 to accurately correct the variation in the current characteristics of the vehicle and, by extension, always optimize the characteristics of the steering assist torque to achieve high quality of the vehicle (steering feeling).
Can contribute to stabilization.

It should be noted that the present invention is not limited to the above-described embodiments and the like, and various embodiments other than the above-described embodiments are possible.
First, the adjustment (correction) of the coefficient stored in the non-volatile memory of the control device of the present invention does not necessarily need to be automatically performed using the above-described fully automatic adjustment device.
For example, after an operator sets an inspection target (a product of the control device 30) in an inspection device that creates a simulated operation state for inspection to be in an operation state, a current measurement value displayed on a display of the inspection device, Compare with the ideal target current value in the operating state, calculate and determine the appropriate value of the coefficient with a calculator or the like, correct the coefficient data by inputting the appropriate value from the terminal, and then display again on the display. To check whether or not the measured current value matches the target current value. Even in this case, the productivity is remarkably improved and the adjustment accuracy is improved as compared with a case where a resistor is replaced each time in order to correct the current detection characteristics. Further, in the above-described embodiment, the above-described inspection and adjustment of the current value (correction of the coefficient) are performed only in one operation state. A similar inspection (and adjustment of the coefficient as necessary) is performed on the signal magnitude and direction or the vehicle speed signal magnitude), and a product with a favorable inspection result under each operating condition ( That is, only a product whose measured current value substantially matches the target current value of each operating condition may be shipped.

[0023]

Since the electric power steering control device according to the present invention has the correction means for correcting the current detection value by multiplying the coefficient stored in the rewritable nonvolatile memory by the current detection value, at least the current detection circuit It is possible to easily correct variations in characteristics by changing the coefficient (rewriting). At least, the extremely troublesome work of replacing the voltage dividing resistor R1 or R2 as in the case of providing the above-described voltage correction circuit 23 (FIG. 4A) does not occur at all, so that the productivity is remarkably improved. Further, by making the change width of the coefficient sufficiently small, fine adjustment is possible, and the characteristics of the control device including the current detection characteristics are accurately corrected, and the characteristics of the steering assist torque in the electric power steering system are always optimized. As a result, it can contribute to the stabilization of the high quality (steering feeling) of the vehicle.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an overall configuration of an electric power steering device.

FIG. 2 is a diagram illustrating a configuration and the like of a current characteristic adjustment device.

FIG. 3 is a flowchart illustrating an example of processing contents of a current characteristic adjustment device.

FIG. 4 is a diagram illustrating a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Assist motor 12 Drive circuit 12a H bridge circuit 13 Control circuit (correction means, communication means) 13a A / D converter 16 Torque sensor 19 Current detection circuit 20 Shunt resistor 21 Amplifier circuit 22 OP amplifier IC 23 Nonvolatile memory 24 Communication I / F circuit (communication means) 25 Communication terminal (communication means) 30 Control device (electric power steering control device) 40 Current characteristic adjustment device 41 Pseudo torque sensor (torque signal output means) 42 Pseudo load motor (adjustment load) 43 Current Sensor (current measurement means) 44 Inspection device (adjustment control processing means)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D033 CA03 CA20 CA28 5H571 AA03 CC02 GG04 HA09 HC03 JJ03 LL22 LL41

Claims (3)

[Claims] 1. A drive circuit for driving an assist motor that is connected to a steering system of a vehicle and generates a steering assist torque, and a current that outputs a current detection value corresponding to a motor current flowing through an energizing line of the assist motor. A detection circuit and a target current value of the motor current are determined as needed so that the steering assist torque becomes a value corresponding to the steering torque of the steering system, and the current detection value matches the target current value. An electric power steering control device having a control circuit for controlling the drive circuit, wherein the current detection value is obtained by multiplying the current detection value by a rewritable nonvolatile memory and a coefficient stored in the nonvolatile memory. An electric power steering control device, further comprising: a correction unit that corrects the power steering. 2. The electric power steering control device according to claim 1, further comprising communication means for rewriting data of the coefficient in the nonvolatile memory in accordance with a signal input from the outside. 3. A current characteristic adjusting device for adjusting the coefficient data to an appropriate value in the electric power steering control device according to claim 2, wherein the steering torque signal is output to the electric power steering control device. Possible torque signal output means, an adjusting load corresponding to the assist motor, current measuring means for measuring a current flowing through the adjusting load, and an operation state in which a specified torque signal is output from the torque signal output means. Reading the current measured value of the current measuring means, and performing the communication as needed so that the current measured value matches a target current value corresponding to the specified torque signal within a specified allowable error range. Adjusting control processing means for outputting a signal for rewriting the coefficient data in the nonvolatile memory to predetermined data via the means. Current characteristic adjustment device for an electric power steering control apparatus for.