JP2003276619A - Duty blind sector correction method for electric power- steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct variation of a hardware of an electric device to achieve uniformity of characteristics between a duty signal for control and a motor current in an electric power-steering device, and to arbitrarily correct a duty blind sector needed for a system. <P>SOLUTION: This duty blind sector correction method is applied to an electric power-steering device provided with a steering torque detecting element outputting a steering torque signal, a motor providing steering torque, and a motor control part generating a duty signal for control (PWM signal), activating an H type bridge circuit, controlling a motor current, and driving the motor. A duty blind sector correction method comprises steps (S12, S13) memorizing a duty value at which the motor current begins to flow when a duty the duty signal outputted from a motor control part is gradually increased as blind sector duty, and steps (S15, S16, S17) correcting the duty of the duty signal generated by the motor control part with the blind sector duty. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duty dead zone correction method for an electric power steering apparatus, and more particularly to a steering apparatus for a vehicle such as a passenger car, in which the rotational force of a motor is applied to a steering system to reduce the steering force of a driver. The present invention relates to a duty dead zone correction method for an electric power steering device that reduces steering noise and enhances steering feeling.

[0002]

2. Description of the Related Art An electric power steering system is provided with a motor in a steering system, and when a driver operates a steering wheel (steering wheel), the power supplied from the motor is controlled by a control device to drive the vehicle. The steering force of the person is reduced.

FIG. 6 shows a schematic configuration of the entire system of a conventional electric power steering apparatus. In the electric power steering apparatus 100, by connecting the steering shaft 102 integrally provided on the steering wheel 101 to the pinion 105a of the rack and pinion mechanism 105 via the connecting shaft 103 having the universal joints 103a and 103b, The steering torque generation mechanism 106 is configured. Rack teeth 107a meshing with the pinion 105a
The rack shaft 107 which has a shaft and which is reciprocated by being meshed with each other in the axial direction is provided with tie rods 1 at both ends thereof.
08 are connected to the left and right front wheels 109 as rolling axes. By operating the steering wheel 101, the driver swings the front wheels through the steering torque generating mechanism 106 and the rack and pinion mechanism 105 to change the direction of the vehicle.

In the electric power steering apparatus 100, in order to reduce the manual steering torque generated by the steering torque generating mechanism 106, the motor 110 that supplies the assist torque (steering assist torque) is, for example, the rack shaft 107.
It is installed coaxially with. The assist torque supplied by the rotary motion from the motor 110 is
Is converted into a force for linear movement through a ball screw mechanism 111 provided substantially in parallel with, and acts on the rack shaft 107. A drive side helical gear 110a is integrally provided on the rotor of the motor 110. The helical gear 110a is a screw shaft 111 of the ball screw mechanism 111.
It meshes with a helical gear 111b that is integrally provided at the shaft end of a. The nut of the ball screw mechanism 111 is connected to the rack shaft 107.

In FIG. 6, a steering torque detector 112 for detecting a steering torque T acting on the pinion 105a is provided in a steering gear box (not shown). The steering torque detection unit 112 converts the detected steering torque T into a steering torque detection signal Td and inputs it to the control device 114. The control device 114 operates using the steering torque detection signal Td as a main signal and controls the power output from the motor 110 (auxiliary steering torque).

As shown in FIG. 7, the control device 114 includes a target current determining section 115 and a control section 116. The target current determination unit 115 determines the target auxiliary torque based on the steering torque detection signal Td, and the target current signal I necessary for supplying the target auxiliary torque from the motor 110.
Output T. The detailed internal structure of the control unit 116 is shown in FIG.

The controller 116 includes a deviation calculator 117, a motor controller 118, a motor driver 119, and a current value detector 1.
Equipped with 20. The motor controller 118 includes a deviation current controller 121 and a PWM signal generator 122. The deviation current control unit 121 performs PI processing such as proportional / integral on the current signal 117a given from the deviation calculation unit 117 to generate and output a driving current signal 121a for controlling the motor current supplied to the motor 110. To do. The PWM signal generation unit 122 generates a PWM (pulse width modulation) signal for performing the PWM operation of the motor 110 based on the drive current signal 121a provided from the deviation current control unit 121. This PWM signal is a duty signal, which will be described later, and is output from the motor controller 118 as a drive control signal 122a.

The motor drive section 119 includes a gate drive circuit section 123 and four power field effect transistors (hereinafter referred to as "F").
ET ”) 124a to 124d are connected in an H-type bridge circuit configuration to form a motor drive circuit (H-type bridge circuit) 124. The gate drive circuit unit 123 includes two FETs according to the steering direction of the steering wheel 101 based on the drive control signal (PWM signal) 122a.
(124a, 124d), (124b, 124c) are appropriately selected, the gates of the two selected FETs are driven, and these FETs are switched. The motor drive circuit 124 composed of an H-type bridge circuit functions as a switching circuit.

As described above, the control device 114 PWM-controls the motor current supplied from the battery power source 126 to the motor 110 based on the steering torque T detected by the steering torque detection unit 112, and the power output from the motor 110 (auxiliary) Steering torque). Steering torque T of the driver
Is the steering torque detection unit 11 of the steering torque generation mechanism 106.
2, the control device 114 controls the output of the motor 110 based on this, and assists the linear movement force of the rack shaft 107 in the axial direction.

[0010]

Elements such as the target current determining section 115, the deviation calculating section 117, and the motor control section 118 in the control device 114 are realized by a microcomputer. As shown in FIG. 9, the microcomputer includes a CPU 131 having a memory 130. The functions of the target current determination unit 115, the motor control unit 118, and the like are realized by software when the CPU 131 executes a program prepared in the memory 130. Further, as described above, the PWM signal generator 12 of the motor controller 118
A gate drive circuit unit 123 is provided between the motor drive circuit 2 and the motor drive circuit (H-type bridge circuit) 124 of the motor drive unit 119. Therefore, as shown in FIG.
The PWM signal output port 131a is not directly connected to the gates of the four FETs 124a to 124d of the H-type bridge circuit 124, and the protection resistor 132 and the capacitor included in the gate drive circuit unit 123 are included in the path. Become. The protection resistor 132 prevents the CPU 13 from the unstable voltage.
1 and FETs 124a to 124d are provided for protection.

According to the above configuration, the rectangular wave (PWM signal) 122a output from the PWM signal generator 122 realized by the CPU 131 is converted into the H-type bridge circuit 124.
When applied to each gate of the four FETs of
First-order lag phenomenon occurs due to transient characteristics based on 2 etc.
The signal 133 in which the rising edge of 22a is blunt is given to the gate. Each FE of the H-type bridge circuit 124
In T124a to 124d, the ON state occurs when the gate-source voltage exceeds the specified voltage. When the circuit configuration of the control unit 116 has the above-described characteristics, the higher the ON level of the rectangular wave 122a to be output, the more
That is, the larger the ON time ratio of the PWM signal (higher duty), the less the influence of the first-order lag waveform rounding. This is because a sufficient rising level can be obtained with the signal given to the gate of each FET. On the other hand, when the on-level of the output rectangular wave 122a decreases, that is, when the on-time ratio of the PWM signal decreases (low duty: 5% or less), the waveform becomes liable to be affected by the first-order lag waveform. PWM signal (square wave 122a)
When the duty ratio of is small, the rounding of the waveform in the signal 133 becomes remarkable, and it becomes difficult to satisfy the ON condition of the FETs 124a to 124d.

FIG. 10 shows a part of the above-mentioned duty signal, and the duty signal will be described. The duty signal 141 is the aforementioned PWM signal, that is, the rectangular wave 122a.
Equivalent to. The duty signal 141 is formed of a rectangular wave that periodically turns on. In FIG. 10, t _ON (on time) and t _OFF (off time) are defined for a rectangular wave. By using t _ON (on time) and t _OFF (off time), duty (Duty) = t _ON / (t _ON + t
_The above "duty" is defined as _OFF ). If this value is large, the duty is high, and if it is small, the duty is low. Further in FIG. 10, the waveform 142 is
The change of the motor current generated corresponding to the duty signal 141 is shown.

At the beginning of turning the steering wheel 101 in the electric power steering apparatus 100, the sense of connection between the steering force and the assist force of the motor is evaluated. Therefore, when viewed from the PWM signal 122a, in most cases,
A low duty duty waveform region is utilized. When the H-type bridge circuit (motor drive circuit 124) is turned on / off using the low duty PWM signal to supply the motor current to the motor 110, the rise of the motor drive current due to the low duty PWM signal is If there is a certain degree of variation in the hardware related to the electronic device, there is a problem that the rising point of the variation varies. As a result, there arises a problem that steering feeling varies depending on the microcomputers mounted on the vehicle.

In view of the above problems, an object of the present invention is to correct variations in hardware of electronic equipment including microcomputers and the like that are mass-produced and mounted in vehicles, and provide characteristics between a control duty signal and a motor current. It is an object of the present invention to provide a duty dead zone correction method for an electric power steering apparatus that achieves a method of achieving uniformization of the above and further enabling arbitrary correction of the duty dead zone as needed in the system to be used.

[0015]

In order to achieve the above object, a duty dead zone correcting method for an electric power steering apparatus according to the present invention is configured as follows.

According to a first method of correcting a dead zone of an electric power steering apparatus (corresponding to claim 1), a steering torque detecting section for detecting a steering torque acting on a steering system and outputting a steering torque signal, and a steering system for steering. A motor that gives torque and a control duty signal (PWM signal) are generated based on at least the steering torque signal,
The present invention is applied to an electric power steering apparatus including a motor control unit that drives a motor by controlling a motor current by operating a switching circuit based on the duty signal. This duty dead band correction method includes a first step of gradually increasing the duty of the duty signal output from the motor control unit and storing a duty value at which the motor current starts to flow in the motor as a dead band duty, and a step internally generated by the motor control unit. And a second step of correcting the duty of the duty signal with a dead zone duty.

In the duty dead zone correction method for the electric power steering apparatus described above, the dead zone duty of the duty signal (PWM signal for drive control) for controlling the operation of the motor of the electric power steering apparatus is obtained, and based on this dead zone duty, It is possible to arbitrarily set the duty dead band width of the duty signal. As a result, it is possible to correct the variation caused by the hardware of the electronic device that constitutes the electric power steering apparatus, and it is possible to make the characteristics of the duty of the duty signal and the motor current uniform.

A second duty dead zone correction method (corresponding to claim 2) is preferably the first method in the above method.
The steps are executed in the initial diagnosis stage, and the motor current energization time by the dead zone duty is characterized by being a time equal to or less than the mechanical time constant during which the motor does not operate. With this configuration, it is possible to prevent the user from feeling uncomfortable without rotating the motor.

The third duty dead zone correction method (corresponding to claim 3) is preferably the second method in the above method.
The step calculates the dead zone correction amount based on the dead zone duty and the dead zone width required by the system, and the duty of the duty signal internally generated by the motor control section is corrected by the dead zone correction amount to output the duty for output. And a step of outputting a signal.

In a fourth duty dead zone correction method (corresponding to claim 4), in the above method, preferably, the switching circuit is an H-type bridge circuit, and the motor control unit is configured to rotate the motor in one or the other rotation direction. H to become
It is characterized in that a motor current is passed through the mold bridge circuit and dead zone duty is obtained in each of the one rotation direction and the other rotation direction.

In a fifth duty dead zone correction method (corresponding to claim 5), preferably, the motor is a brushless motor, and the dead zone duty is determined and stored for the motor current of each phase of the brushless motor. Then, the correction is performed.

This electric power steering apparatus detects a steering torque acting on a steering system and outputs a steering torque signal, a steering torque detecting unit, a motor for applying a steering torque to the steering system, and a control based on at least the steering torque signal. This is an electric power steering device that includes a motor control unit that generates a duty signal for use and operates a switching circuit based on the duty signal to output a motor current to drive the motor. Means for forcibly operating the switching circuit for a time equal to or less than a constant, means for detecting the motor current supplied to the motor, means for storing a duty value corresponding to the rising point of the motor current as a dead zone duty, and a motor The duty of the duty signal generated internally by the control unit And means for correcting-sensitive band duty,
Is configured.

In the above electric power steering device,
By providing a configuration for performing duty dead zone correction,
It is configured to obtain a dead zone duty of a duty signal (a PWM signal for drive control) that controls the operation of the motor of the electric power steering apparatus, and arbitrarily set the duty dead zone width of the duty signal based on the dead zone duty. As a result, the variation caused by the hardware of the electronic device that constitutes the electric power steering apparatus is corrected, and the characteristics of the duty of the duty signal and the motor current are made uniform.

Further, in the electric power steering apparatus having the above-mentioned structure, the motor is a brushless motor, and the dead zone duty of the motor current of each phase of the brushless motor is obtained, stored and corrected.

[0025]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

The configurations, shapes, sizes, and arrangement relationships described in the embodiments are merely shown to the extent that the present invention can be understood and put into practice, and the numerical values and the compositions (materials) of the respective components are shown. Is only an example. Therefore, the present invention is not limited to the embodiments described below, and can be modified into various forms without departing from the scope of the technical idea shown in the claims.

The basic structure of the electric power steering apparatus according to the present invention is the same as the conventional apparatus described with reference to FIGS. Therefore, if necessary in the description of the following embodiments, FIGS.
The components shown in each figure will be referred to by using reference numerals as appropriate.

As compared with the conventional electric power steering apparatus described above, the feature of the present invention is that the current rising point of the motor current for driving the motor 110 provided in the electric power steering apparatus 100 can be controlled. Further, the PWM signal 122a for controlling the motor current to the motor 110, that is, the duty signal 141
It is possible to eliminate the variation of the duty dead zone in the above, and to further arbitrarily control the dead zone width according to the demand of the system. The configuration relating to these characteristics is realized by improving the software configuration of the control device 114.

The function realized by the motor control unit 118 (shown in FIG. 8) in the control unit 116 in the control unit 114 is that the motor control unit 118 is composed of a CPU 131 having a memory 130 as shown in FIG. It is realized by software. Therefore, for the duty dead zone correction function in the electric power steering apparatus according to the present embodiment, the memory 130 is provided with a program that implements the duty dead zone correction method. CP of the program prepared in the memory 130
The U131 reads and executes the duty dead zone correction method according to the present embodiment, and an electric power steering apparatus having the duty dead zone correction function is configured.

A typical duty dead zone correction method executed in the electric power steering apparatus 100 will be described with reference to the flowchart shown in FIG. In the first determination step S11, it is determined whether the control stage is an initial diagnosis control stage or a normal control stage. When it is determined that it is the stage of initial diagnosis, the process proceeds to step S12, and when it is determined that it is the stage of normal control, step S15.
Move to. Generally, whether or not it is in the initial diagnosis stage will be determined by, for example, whether or not the ignition switch is turned on. If it is not the initial diagnosis stage, it is determined to be the normal control stage.

The step S12 is executed at the stage of initial diagnosis. The stage of initial diagnosis is a control stage for initially diagnosing a system including electric and electronic devices mounted on a vehicle such as a passenger car. Step S12 is executed in a short time before the vehicle starts traveling, for example, when the engine is started. In the initial diagnosis, it is checked whether a large number of electric / electronic devices mounted on the vehicle satisfy normal operating conditions. The electric power steering device 1 as one of electric / electronic devices mounted on a vehicle
00 is also included.

In step S12, the initial diagnosis performed on the electric power steering system 100 is as follows. From the PWM signal generator 122 to the PWM signal 12
2a, that is, the duty signal 141 is output, the on-time (t _ON ) in the duty signal 141 is gradually increased from 0%, and the ON / OFF operation of one of the FETs of the motor drive circuit 124 which is an H-type bridge circuit ( Based on the switching operation), the duty value at the time when the motor current ( _IM ) starts to flow to the motor 110 is obtained. This duty value is set to "DY ₀ ".

Duty value DY at the above initial diagnosis stage
_{In the} case of obtaining ₀ , the time for turning on / off the FET of the motor drive circuit 124 by continuing the duty value DY ₀ of the duty signal 141 is
It is assumed that 0 is a time equal to or less than the mechanical time constant of the motor in a state where it does not move (due to its inertia).

FIG. 2 is a conceptual block diagram showing a method of obtaining the dead zone duty value DY ₀ in the initial diagnosis stage. In FIG. 2, C that constitutes the motor control unit 118
The PU 131 gives the duty signal 141 to the motor drive circuit (H-type bridge circuit) 124 via the gate drive circuit 123. This duty signal 14
1 is the PWM signal 122a. Motor drive circuit 124
A motor current detector 11 is attached to this. The motor current detection unit 11 may be the above-described current value detection unit 120 or another current sensor. Further, the arrangement position may be 120 or on the current supply line to the motor 110. The output signal from the motor current detector 11 is fed back to the CPU 131. With this motor current feedback configuration, the CPU 131 can know whether or not the motor current I _M has started to flow. The graph 12 shown in FIG. 2 shows the duty (Duty:
Change characteristics of motor current (vertical axis) against changes in horizontal axis 1
3 is shown. The duty value corresponding to the lower end point 13a of the change characteristic 13 matches DY ₀ described above. In this way, the duty value DY ₀ is determined.

Duty value DY obtained as described above
₀ is stored in the memory 130 (step S13). When step S13 ends, the process moves to the next step S14.

In the above, the step of obtaining the duty value DY ₀ can be performed even when a similar control state other than the initial diagnosis is occurring.

In step S14, the dead zone width DY _req required by the system is set. This dead zone width DY
_req is a control element required in the system itself of the electric power steering apparatus 100, and is originally determined according to the system condition. Therefore, the dead zone width DY _req does not necessarily have to be sequentially set in step S14, and may be stored in the memory 130 in advance. In this case, step S14 is omitted. After step S14, the process proceeds to determination step S18.

In the judgment step S18, the motor control unit 1
It is determined whether to end the control in 18. If NO in determination step S18, the first determination step S1
Return to 1. When it is judged at the judgment step S11 that the control step is the normal control, step S15 is executed. In step S15, the duty dead zone correction amount DY _cor is calculated. The duty dead zone correction amount DY _cor is the duty value DY ₀ and the dead zone width DY required by the system.
It is calculated as the difference from _req , that is, DY ₀ −DY _re .
When the duty dead zone correction amount is obtained, the duty signal is corrected using this correction amount (step S16). The duty value of the duty signal 141 output from the CPU 131 (corrected duty value) is “D
Y _CPUOUT ”, and when the duty value of the duty signal before correction (duty value before correction) generated inside the CPU 131 is“ DY _CPUIN ”, DY
_{CPUOU T} is calculated by equation _{DY CPUOUT = DY CPUIN + DY cor} . Here, the duty dead zone correction amount DY _cor has a value including a sign. The corrected duty value DY _CPUOUT duty signal 141 thus obtained
Is output from the CPU 131 (step S17).

FIG. 3 is a control block diagram showing the components of the control device for executing the contents of the normal control based on steps S15, S16 and S17 described above. The target current IT is input to the deviation current control unit 121 via the deviation calculation unit 117. The deviation current control unit 121 performs the PI control as described above. Next stage PWM signal generator 1
At 22, a PWM signal is output. This PWM signal is
It is a duty signal (duty value DY _CPUIN ) before correction generated inside the CPU 131. This duty signal is input to the addition unit 14 where the duty dead zone correction amount DY _cor given from the storage unit 15 is added. As a result, the corrected duty signal (duty value DY _CPUOUT ) is output from the addition unit 14. The corrected duty signal is the CPU 131, that is, the motor control unit 11.
8 is output, the motor current I passes through the primary delay circuit 16 based on the corrected duty signal.
_M is output. This motor current is the motor drive circuit 1
It is output from 24 and given to the motor 110. The first-order delay circuit 16 is a circuit portion having a first-order delay action generated in the gate drive circuit section 123. The output motor current I _M is fed back via the deviation calculator 117.

At the next judgment step S18, it is judged again whether the control is ended or not. If NO in determination step S18, the process proceeds to first determination step S11. Thus, steps S11 to S18 are repeated while the normal control is performed. If YES in determination step S18,
finish.

The check based on the above steps S12 to S14 is performed every time the CPU 131 is started. As a result, variations in hardware related to the electronic device (due to variations in the electric time constant of the motor, the ON / OFF time constant of the FET, the battery voltage, etc.) are canceled out, and a desired duty current characteristic is realized.

The above check may be performed on either the clockwise or counterclockwise motor current of the motor 110. Further, a duty dead zone correction amount is set independently for each of the clockwise motor current and the counterclockwise motor current of the motor 110, and the duty dead zone correction is independently performed for the clockwise and counterclockwise rotation of the motor 110. Of course you can.

Further, by performing the check based on the above steps S12 to S14 when the ignition is turned off, the dead zone correction for the temperature change can be performed.

Next, a specific application example of the duty dead zone correction method described above will be described with reference to FIG. In FIG. 4, the horizontal axis represents the duty related to the duty value DY _CPUIN.
(Duty:%), and the vertical axis represents the motor current I _M.

In FIG. 4, a graph K shows a motor current characteristic in a state where no correction is made. This motor current characteristic is C
This is caused by the duty signal (duty value DY _CPUIN ) generated inside the PU 131 being directly output from the output port without being corrected.
In the graph K relating to the motor current characteristic, the duty dead zone DY ₀ which the system of the electric power steering apparatus 100 has as an eigenvalue relating to hardware is 5% (in the figure). This value is obtained in advance by a preliminary diagnosis.

Here, the dead zone width D required for the system
An example in the case where Y _req is assumed to be 2% (graph A in the figure) will be described. In the case of this example, the duty dead zone correction amount DY _cor is DY _cor = 5-2 = + 3%. Therefore, the corrected duty value output from the CPU 131 is DY _CPUOUT = DY _CPUIN + DY _cor .
When DY _CPUIN becomes 2% or more, the duty signal of the duty value DY _CPUOUT of 5% is output to the output of the CPU 131. By performing the duty dead zone correction in this way,
The duty dead band width of the system of the electric power steering apparatus 100 can be set to 2%.

Next, the dead zone width DY required for the system
An example will be described on the assumption that _req is 8% (graph B in the figure). In the case of this example, the duty dead zone correction amount DY _cor is DY _cor = 5-8 = -3%.
Therefore, the corrected duty value output from the CPU 131 is DY _CPUOUT = DY _CPUIN + DY _{cor.
If the CPUIN} is 8% or more, the output of _CPU131 is 5
% Of the duty signal for the duty value DY _{C PUOUT} is output. By performing the duty dead zone correction in this way, the duty dead zone width of the system of the electric power steering apparatus 100 can be set to 8%.

FIG. 5 shows a drive circuit for a three-phase brushless motor. When a three-phase brushless motor is used as the motor 110, the drive circuit 21 shown in FIG. 5 is used instead of the motor drive circuit 124 described above. The drive circuit 21 is configured as a bridge circuit using six FETs 22a to 22f, and a U-phase motor current, a V-phase motor current,
W-phase motor current is output. Six FETs 22a-2
By applying a PWM signal (duty signal) to each gate of 2f, the on / off operation of the six FETs 22a to 22f is controlled, and the U-phase motor current, the V-phase motor current,
The W-phase motor current is output in an appropriate phase relationship. Also in the case of the drive circuit 21, the duty dead zone correction described above can be applied to the supply of each of the U-phase motor current, the V-phase motor current, and the W-phase motor current.

In the above embodiment, the moving average value of DY _cor for each ignition off is stored in the storage unit (EEPRO).
It is also possible to perform correction of the temperature characteristic component of the hardware of the electronic device and aging deterioration, or voltage correction by storing it in the M.

[0050]

As is apparent from the above description, according to the present invention, in the control device for controlling the operation of the assisting motor in the electric power steering device mounted on the vehicle, the motor control for controlling the rotating operation of the motor is performed. Since the dead band width of the duty of the duty signal (PWM signal) output from the section, that is, the rising point of the motor current with respect to the duty can be arbitrarily controlled, an electronic device including a microcomputer of an electric power steering device and the like. It is possible to correct the variation in the hardware, to achieve the uniformization of the characteristics between the control duty signal and the motor current, and further to correct the duty dead zone as needed in the system used. Further, the steering feeling at the beginning of turning the steering wheel can be improved, and in addition, the difference in steering feeling between vehicles can be eliminated.

[Brief description of drawings]

FIG. 1 is a flowchart for explaining an embodiment of a duty dead zone correction method according to the present invention, which is implemented in an electric power steering system.

FIG. 2 is a diagram conceptually illustrating a method of determining a dead zone duty in an initial diagnosis stage.

FIG. 3 is a control block diagram showing a configuration in which a duty of a duty signal internally generated by a motor control unit is corrected by the obtained dead zone duty in a normal control stage.

FIG. 4 is a graph showing two examples of a duty dead zone correction method and illustrating how to determine a correction amount.

FIG. 5 is an electric circuit diagram showing a drive circuit for generating a motor current when the motor is a brushless motor.

FIG. 6 is a configuration diagram schematically showing an overall configuration of a conventional electric power steering device.

FIG. 7 is a diagram showing an internal configuration of a control device of a conventional electric power steering device.

FIG. 8 is a circuit diagram showing an internal configuration of a control unit in the control device.

FIG. 9 is a circuit diagram showing a circuit configuration between a CPU and an H-type budgie circuit.

FIG. 10: Duty in the duty signal
It is a figure explaining.

[Explanation of symbols]

Reference _{Signs List} 11 motor current detection unit 14 adder 15 storage unit (DY _cor ) 21 drive circuit 100 electric power steering device 110 motor 112 steering torque detection unit 114 control device 116 control unit 118 motor control unit 119 motor drive unit 122 PWM signal generation unit 124 Motor drive circuit (H-type bridge circuit) 130 Memory 131 CPU 141 Duty signal (PWM signal)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) B62D 137: 00 H02P 6/02 351J (72) Inventor Hiroaki Horii 1-4-1 Wako-Chu, Saitama Prefecture Incorporated company Honda Technical Research Institute (72) Inventor Kazuhisa Watanabe 1-4-1 Chuo, Wako City, Saitama Prefecture Stock company Honda Technical Research Institute (72) Inventor Osamu Tsurumiya 1-4-1 Wako-shi, Saitama Prefecture F-Term in Honda R & D Co., Ltd. (Reference) 3D032 CC08 DA15 DA64 DD10 EB06 EC23 3D033 CA16 CA20 5H560 AA10 DC12 EB01 EC01 GG04 RR10 TT05 TT06 TT07 TT12 TT15 TT20 UA05 XA02 XA12 XB04 DD0801 BB01 5H570 AA21 JJ03 JJ08 JJ17 JJ22 JJ25 KK06 LL02 PP02

Claims (5)

[Claims] 1. A steering torque detecting means for detecting a steering torque acting on a steering system and outputting a steering torque signal, a motor for applying a steering torque to the steering system, and a control duty signal based on at least the steering torque signal. In the electric power steering apparatus having a motor control means for driving the motor by controlling the motor current by operating the switching circuit based on the duty signal, the duty of the duty signal is gradually increased to the motor. A first step of storing a duty value at which the motor current starts to flow as a dead zone duty; and a second step of correcting the duty of the duty signal internally generated by the motor control means with the dead zone duty.
A method of correcting a duty dead zone of an electric power steering device, comprising: 2. The first step is executed in an initial diagnosis stage, and a motor current energization time by the dead zone duty is a time equal to or less than a mechanical time constant during which the motor does not operate. A duty dead zone correction method for an electric power steering device. 3. The step of calculating a dead zone correction amount based on the dead zone duty and a dead zone width required for the system, and the second step includes a duty of the duty signal internally generated by the motor control means. The method according to claim 1, further comprising the step of correcting with the dead zone correction amount and outputting a duty signal for output. 4. The switching circuit is an H-type bridge circuit, and the motor control means causes the motor current to flow through the H-type bridge circuit so that the motor is in one rotation direction or the other rotation direction. 2. The duty dead zone correction method for an electric power steering apparatus according to claim 1, wherein the dead zone duty is calculated for each of the rotation direction and the other rotation direction. 5. The motor is a brushless motor,
The duty of the electric power steering apparatus according to any one of claims 1 to 3, wherein the dead zone duty is obtained and stored for each phase motor current of the brushless motor, and the correction is performed. Dead band correction method.