JP2001186790A - Electric power steering controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electric power steering controller for vehicle capable of sufficiently reducing torque ripples even if supply voltage fluctuates. SOLUTION: The electric power steering controller is provided with a rotational angle calculating means 4e that calculates the electrical angle signal and rotational speed of a DC brushless motor 7; a compensation signal calculating means 4f that calculates the torque ripple compensation signal of the DC brushless motor 7; a target current value calculating means 4a that calculates a target current value for driving the DC brushless motor 7 from steering wheel torque and driving speed; a voltage allowance value setting means 4j for setting a voltage allowance value to the target current value; a current command value setting means 4b for setting a current command value based on a target current value, a supply voltage value, and a voltage allowance value; and a driving signal calculating means 4g that outputs a PWM signal to the drive circuit 5 of the DC brushless motor 7 based on the current command value, the torque ripple compensation signal, and the electrical angle signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering control device for a vehicle which assists a steering force by using a DC brushless motor.

[0002]

2. Description of the Related Art In an electric power steering apparatus used in a vehicle, a steering torque is provided by a torque sensor provided on a steering shaft, a vehicle speed is detected by a vehicle speed sensor, and a drive current corresponding to the vehicle speed and the steering torque is supplied to a motor. And a DC brushless motor is used for the motor to simplify maintenance or to eliminate maintenance. In the electric power steering apparatus using such a DC brushless motor, the motor current control unit determines a target current value corresponding to the detected vehicle speed and steering torque, sets the target current value as a command value, and sets a drive current of the motor and a rotating electric motor. An angle monitor is provided to detect a current value corresponding to the rotational electrical angle of the motor, and the motor current control unit calculates a deviation between the detected value and the target current value so that the detected value matches the target current value. Is controlling the inverter.

As described above, in the control method in which the current value is merely controlled to the target current value in order to obtain the target torque value, torque ripple is generated in the DC brushless motor, and the torque ripple is applied to the steered wheels to give the driver a command. May cause discomfort. The torque ripple is generated when the electric angle of rotation of the motor is detected and commutation is performed based on the detected position of the rotor. That is, when the current fluctuates at the time of commutation, torque ripple is generated, which causes vibration and noise.

[0004] As a method of reducing the torque ripple, literatures, IEEE TRANSACTIONS O
N POWER ELECTRONICS, VOL8,
NO. 2, APRIL 1993, "Commutat
ion Strategies for Brushl
ess DC Motors: Influenceon
"Instant Torque", as another reference, 1993 The European Powe
r Electronics Association
"A NOVEL CURRENT CONTROL
STRATEGY IN TRAPEZOIDAL
EMF ACTUATORS TOMINIMIZE
TORQUE RIPPLES DUE TO PHA
SES COMMUTIONS "is disclosed.

[0005] These are related to rectangular wave drive control of a trapezoidal magnetic flux distribution type DC brushless motor. If the former is referred to as Document 1 and the latter is referred to as Reference 2, Document 1 applies a voltage applied to the motor in a non-commutation section. The voltage applied between the motor terminals to control the current in the non-commutation phase and the voltage applied between the motor terminals to control the rise and fall of the current during commutation to reduce torque ripple In order to compensate for the torque ripple, the current command value is corrected by a compensation current having the rotation electrical angle of the motor as a parameter. Reference 2 discloses that a torque ripple is controlled by controlling a voltage applied to a motor between a motor terminal for controlling a non-commutation phase current and a rise and fall of a current during commutation. In order to reduce this, the voltage is applied to a phase that is normally turned off during commutation.

[0006]

In the conventional method for reducing the torque ripple of the DC brushless motor controlled as described above, the torque ripple is controlled by controlling the rise and fall of the current during commutation as described above. Since the compensation is performed by applying a voltage such as the voltage applied between the motor terminals to reduce the voltage, the effect is limited by the power supply voltage. Therefore, there is a problem that an area where torque ripple cannot be sufficiently reduced remains. In particular, in an electric power steering apparatus for a vehicle, the power supply is a battery, and in a vehicle equipped with a large number of electric components that consume a large amount of power, as in recent years, the power supply voltage greatly fluctuates, and the effect is large.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to eliminate a limit of torque ripple suppression by a power supply voltage and to sufficiently reduce a torque ripple even when a power supply voltage fluctuates. It is an object of the present invention to obtain an electric power steering control device for a vehicle capable of performing the following.

[0008]

SUMMARY OF THE INVENTION An electric power steering control device according to the present invention comprises: a rotation angle calculation means for calculating an electric angle signal and a rotation speed of a DC brushless motor; and a torque ripple compensation signal for the DC brushless motor. Signal calculating means for calculating a target current value for driving the DC brushless motor from steering torque and the traveling speed of the vehicle;
C voltage margin value setting means for setting a voltage margin value with respect to a power supply voltage in order to prevent distortion of a brushless motor driving current, a current for setting a current command value from the target current value, the power supply voltage value, and the voltage margin value Command value setting means; and drive signal calculation means for outputting a PWM signal to the drive circuit of the DC brushless motor from the current command value, the torque ripple compensation signal and the electric angle signal.

Rotation angle detection means for detecting an electric angle signal and a rotation speed of the DC brushless motor; compensation voltage calculation means for calculating a torque ripple compensation signal from a neutral point voltage of a field coil of the DC brushless motor; Target current value calculating means for calculating a target current value for driving the DC brushless motor based on a steering torque and a traveling speed of the vehicle; and a voltage margin with respect to a power supply voltage for preventing distortion of the DC brushless motor driving current due to insufficient voltage. Voltage margin value setting means for setting a value, current command value setting means for setting a current command value from the target current value, the power supply voltage value and the voltage margin value, addition of the current command value and the torque ripple compensation signal And a drive signal calculating means for outputting a PWM signal to a drive circuit of the DC brushless motor from the value and the electrical angle signal. That.

Further, a rotation angle detecting means for detecting an electric angle signal and a rotation speed of the DC brushless motor, and a target current value calculation for calculating a target current value for driving the DC brushless motor from the steering torque and the running speed of the vehicle. Means, voltage margin value setting means for setting a voltage margin value with respect to a power supply voltage for preventing distortion of the DC brushless motor driving current due to insufficient voltage, and a current margin based on the target current value, the power supply voltage value, and the voltage margin value. Current command value setting means for setting a command value; compensation current calculation means for calculating a torque ripple compensation signal from the current command value and the electric angle signal; an addition value of the current command value and the torque ripple compensation signal; And a drive signal calculating means for outputting a PWM signal from the electrical angle signal to a drive circuit of the DC brushless motor.

Further, a rotation angle detecting means for detecting an electric angle signal and a rotation speed of the DC brushless motor, and a target current value for calculating a target current value for driving the DC brushless motor from the steering torque and the running speed of the vehicle. Arithmetic means,
Voltage margin value setting means for setting a voltage margin value with respect to a power supply voltage in order to prevent distortion of the DC brushless motor driving current due to insufficient voltage, a current command value based on the target current value, the power supply voltage value, and the voltage margin value Current command value setting means, a compensation current calculation means for calculating a first torque ripple compensation signal from the current command value and the electric angle signal, and a compensation current computing means for calculating a first torque ripple compensation signal from a neutral point voltage of a field coil of the DC brushless motor. Compensation voltage calculating means for calculating a second torque ripple compensation signal, current control means for calculating a command voltage from an added value of the current command value and the first torque ripple compensation signal, and the command voltage and the second torque A drive circuit for outputting a PWM signal to a drive circuit of the DC brushless motor from a sum of a ripple compensation signal and the electrical angle signal; A.

A rotation angle detection means for detecting an electrical angle signal and a rotation speed of the DC brushless motor; a target current value calculation for calculating a target current value for driving the DC brushless motor from a steering torque and a running speed of the vehicle; Means, voltage margin value setting means for setting a voltage margin value with respect to a power supply voltage for preventing distortion of the DC brushless motor driving current due to insufficient voltage, and a current margin based on the target current value, the power supply voltage value, and the voltage margin value. Current command value setting means for setting a command value; feedback signal calculating means for generating a feedback signal from the electric circuit current of the DC brushless motor and the electrical angle signal and providing the feedback signal to the current control means; Current control means for calculating a command voltage to match, the feedback signal and the electrical angle signal Compensation voltage calculating means for calculating a compensation voltage from the command voltage, the compensation voltage, and the electrical angle signal, and applies a PWM signal for two phases to be energized and a phase that is normally turned off during commutation. PW of compensation voltage
And a drive signal calculating means for supplying the M signal to the drive means of the DC brushless motor.

Further, a rotation angle detecting means for detecting an electric angle signal and a rotation speed of the DC brushless motor, and a target current value calculation for calculating a target current value for driving the DC brushless motor from the steering torque and the running speed of the vehicle. Means, voltage margin value setting means for setting a voltage margin value for a power supply voltage to prevent distortion of the DC brushless motor drive current due to insufficient voltage, a current command value from the target current value, the power supply voltage value, and the voltage margin value Current command value setting means, a compensation current calculation means for calculating a torque ripple compensation signal from the current command value and the electric angle signal, and a command voltage from an added value of the current command value and the torque ripple compensation signal. A current control means for calculating, generating a feedback signal from the electric circuit current of the DC brushless motor and the electric angle signal, and Feedback signal calculating means for providing to the current control means, current control means for calculating a command voltage to match the feedback signal with the sum of the current command value and the torque ripple compensation signal, the feedback signal and the electrical angle signal, Compensation voltage calculating means for generating a compensation voltage from the command voltage, the compensation voltage, and the electrical angle signal, and applies a PWM signal for two phases to be energized and a phase that is normally turned off during commutation. And a drive signal calculating means for supplying a PWM signal of the compensation voltage to the drive means of the DC brushless motor.

Further, the voltage margin value set by the voltage margin value setting means is calculated using the back electromotive voltage calculated from the rotation speed of the DC brushless motor as a parameter. The voltage margin value set by the voltage margin value setting means is calculated using the rotation speed of the DC brushless motor as a parameter. Further, the voltage margin value set by the voltage margin value setting means is a predetermined constant value. Still further, the voltage margin value set by the voltage margin value setting means is calculated by a predetermined arithmetic expression.

The current command values set by the current command value setting means include a maximum current command value of TImax, a power supply voltage of a, a voltage margin value of b, a motor back electromotive voltage of e, and a motor winding resistance value of d. In this case, TImax = (ab-e) / d is obtained.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram illustrating a configuration of an electric power steering control device according to a first embodiment of the present invention, and FIGS. 2 to 7 are explanatory diagrams illustrating operations thereof. In FIG. 1, reference numeral 1 denotes a torque sensor provided on a steering shaft of a vehicle, 2 denotes a vehicle speed sensor that detects a traveling speed of the vehicle, 3 denotes a voltage detection circuit that detects a power supply voltage, and 4 denotes signals of these sensors and the like. A driving circuit for driving a three-phase inverter 6 based on a signal from the control device 4; a DC brushless motor 7 for applying an auxiliary torque to the steering device by electric power from the inverter 6; To DC
A current detection circuit for detecting the electric circuit current based on the outputs of the phase current detection resistors 8a and 8b provided on the electric circuit to the brushless motor 7, and a neutral point 10 for detecting the neutral point voltage of the field of the DC brushless motor 7 The voltage detection circuit 11 includes Hall sensors 12 a and 12 provided in the DC brushless motor 7.
Hall sensor I for applying the outputs of b and 12c to the controller 4
/ F circuit.

The control device 4 is a software configuration block that uses the outputs of the torque sensor 1 and the vehicle speed sensor 2
A target current value calculator 4a for calculating a target current value for the C brushless motor 7, and a current command value for calculating a current command value based on signals from the target current value calculator 4a and a voltage detection circuit 3 for detecting a power supply voltage. A setting section 4b, a current control section 4c for controlling a supply current based on a current command value of the current command value setting section 4b, and a feedback current calculation section 4d for providing the current value detected by the current detection circuit 9 to the current control section 4c. And the signal of the Hall sensor I / F circuit 11
An electrical angle calculator 4e for detecting an electrical angle of the C brushless motor 7 and outputting an electrical angle signal;
, A torque ripple compensation voltage calculation unit 4f that calculates a torque ripple compensation voltage based on the signal, an added value of the current control unit 4c and the torque ripple compensation voltage calculation unit 4f, and an electrical angle signal. Signal calculating section 4g for controlling the electric angle and DC from the electric angle signal of the electric angle calculating section 4e.
A motor rotation speed calculation unit 4h that calculates the rotation speed of the brushless motor 7, a motor back electromotive voltage calculation unit 4i that calculates the back electromotive voltage from the calculated motor rotation speed, and a voltage margin value based on the back electromotive voltage of the motor. And a voltage margin value setting unit 4j to be calculated and given to the current command value setting unit 4b.

In the electric power steering control apparatus according to the first embodiment of the present invention, when a steering force is applied to the torque sensor 1, the signals from the torque sensor 1 and the vehicle speed sensor 2 are used to calculate a target current value. The target current value calculator 4a calculates a target current value for causing the DC brushless motor 7 to output a torque corresponding to the vehicle speed and the steering force, and outputs the target current value to the current command value setting unit 4b. This target current value is applied to the drive circuit 5 via the current control unit 4c and the drive signal calculation unit 4g, and is applied to the DC brushless motor 7
At this time, the electrical angle calculator 4e calculates the electrical angle θ based on the rotational position signals from the Hall sensors 12a, 12b, 12c, and converts the electrical angle signal into a feedback current calculator 4d and a motor speed calculator 4h. And give to. The motor rotation speed calculation unit 4h calculates the rotation speed of the DC brushless motor 7 from the electrical angle signal and provides it to the motor back electromotive voltage calculation unit 4i. The motor back electromotive voltage calculation unit 4i calculates the back electromotive voltage of the motor from the rotation speed. The calculation is given to the voltage margin value setting unit 4j.

The voltage margin value setting unit 4j has a motor back electromotive voltage conversion table as shown in FIG. 2, converts the input back electromotive voltage of the motor into a voltage margin value, and inputs it to the current command value setting unit 4b. I do. The current command value setting unit 4b limits the target current from the target current value calculation unit 4a according to the flowchart shown in FIG. That is, in step 301 of FIG. 3, the power supply voltage value a
The voltage margin b and the motor back electromotive voltage e from the voltage margin value setting unit 4j, the target current value c from the target current value calculation unit 4a, and the stored winding resistance d of the DC brushless motor 7. The maximum current command value TImax is determined in step 302 as TImax = (ab-e) / d. In step 303, the target current value c is compared with the maximum current command value TImax, and if TImax <c If there is, the current command value is set to TImax in step 304, and if TImax ≧ c, the current command value is set to the target current value in step 305, and the current command value is output to the current control unit 4c.

The feedback current calculator 4d stores a formula for calculating the feedback current with respect to the input electrical angle signal, and calculates a feedback current value (non-inverting value) calculated based on the signal from the current detection circuit 9 and the electrical angle signal. The current value of the current phase) is output to the current control unit 4c. Current control unit 4
c sets the target voltage value so that the current command value provided from the current command value setting unit 4b matches the feedback current value. On the other hand, the torque ripple compensation voltage calculation unit 4f
A torque ripple for compensating the neutral point voltage to obtain the neutral point voltage from the neutral point voltage detection circuit 10 and control the rise and fall of the current at the time of commutation in the same manner as in the above-mentioned prior art document 1 Set the compensation voltage value.

The drive signal calculating section 4g is configured to calculate the target voltage value set by the current control section 4c and the torque ripple compensation voltage calculating section 4g.
f, an added value to the torque ripple compensation voltage value set, and an electric angle signal are input, and a three-phase PWM signal for driving the DC brushless motor 7 is output.
The M signal is input to the three-phase inverter 6 via the drive circuit 5, and a three-phase field voltage is generated to drive the DC brushless motor 7. Thus, the voltage margin value setting unit 4j converts the back electromotive voltage of the motor into a voltage margin value, and as shown in FIG. 3, the maximum current command is obtained from the value obtained by subtracting the voltage margin value and the back electromotive voltage from the power supply voltage. Since the current value is calculated and the current command value is determined by comparison with the target current value, the current value of the DC brushless motor 7 can be set in a state where a voltage margin is always provided, and torque ripple is suppressed. It is possible.

The suppression of the torque ripple will be described with reference to FIGS. 4 to 6. FIG. 4 shows the current waveform and the output torque when the back electromotive voltage is low at low speed rotation. In addition, a sufficient voltage margin is obtained, no torque ripple occurs, and no current ripple occurs during commutation. If the rotation speed increases and the back electromotive voltage increases, the voltage margin value becomes insufficient accordingly. At the same current setting as in the low-speed rotation, a current ripple occurs at the time of commutation as shown in FIG. Torque ripple occurs due to the current ripple. In the electric power steering control device according to the first embodiment of the present invention, as described above, the voltage margin value is obtained from the back electromotive force, and the voltage margin value is subtracted from the power supply voltage to determine the current command value TImax. Therefore, a voltage margin value can always be secured, and as shown by the solid line in FIG. 6, an electric power steering control device can be obtained in which current ripple during commutation does not occur even during high-speed rotation, and therefore, no torque ripple occurs. Will be.

In the above description, the voltage margin value setting unit 4
Although the description has been given with the content that the motor back electromotive voltage conversion table as shown in FIG. 2 is stored in j, the motor rotation speed conversion table for determining the voltage margin value with respect to the motor rotation speed as shown in FIG. A similar effect is obtained, and instead of these tables, a preset constant voltage is stored in the voltage margin value setting unit 4j, or an arithmetic expression to be calculated according to the condition is stored in the voltage margin value setting unit 4j. Voltage margin can be obtained.

Embodiment 2 FIG. FIG. 8 is a block diagram illustrating a configuration of an electric power steering control device according to Embodiment 2 of the present invention. In the figure, reference numeral 1 denotes a torque sensor, 2 denotes a vehicle speed sensor, 3 denotes a power supply voltage detection circuit, and 4 denotes A control device comprising a microcomputer for inputting signals of the sensors and the like; 5, a drive circuit for driving a three-phase inverter 6;
7 is a DC brushless motor, 8a and 8b are phase current detection resistors, and 9 is a current detection circuit, except that the contents of the control device 4 are different from those of the electric power steering control device of the first embodiment as described later. Is similar.
Reference numeral 13 denotes a resolver I / F circuit for detecting the rotation angle of the DC brushless motor 7 by adding a rotation position signal detected by a resolver 12d provided in the DC brushless motor 7 to the control device 4.

Further, the control device 4 is a software configuration block that controls the DC brushless motor 7 based on signals from a target current value calculation unit 4a, a current command value setting unit 4b, a feedback current calculation unit 4d, and a resolver 12d. An electrical angle calculation unit 4e for calculating an electrical angle signal, a current command value output from the current command value setting unit 4b, and an electrical angle signal output from the electrical angle calculation unit 4e are input to generate a torque ripple compensation current. A current that inputs a torque ripple compensation current calculation unit 4k, an added value of a current command value output from the current command value setting unit 4b, a compensation current value output from the torque ripple compensation current calculation unit 4k, and a feedback signal of a circuit current. The drive circuit 5 is controlled by inputting a control unit 4c and a target voltage value output from the current control unit 4c and an electrical angle signal output from the electrical angle calculation unit 4e. A drive signal calculation unit 4g, a motor rotation speed calculation unit 4h that calculates the rotation speed of the DC brushless motor 7 from the electrical angle signal output from the electrical angle calculation unit 4e, and a back electromotive voltage of the DC brushless motor based on the rotation speed. It comprises a motor back electromotive voltage calculation unit 4i for calculating, and a voltage margin value setting unit 4j which calculates a voltage margin value from the back electromotive voltage and gives the voltage margin value to the current command value setting unit 4b.

That is, the present embodiment differs from the electric power steering control apparatus of the first embodiment in that the rotational position signal of the DC brushless motor 7 is obtained by the resolver 12d instead of the hall sensor, and the neutral point Instead of the torque ripple compensation voltage calculation unit that obtains a voltage to generate a torque ripple compensation voltage value, the torque ripple is input by inputting the electrical angle signal output by the electrical angle calculation unit 4e and the target voltage value output by the current control unit 4c. And a torque ripple compensation current calculation unit 4k for compensating for
The output of the current command value setting unit 4b and the output of the torque ripple compensation current calculation unit 4k are added to and input to the current control unit 4c, and the output of the current control unit 4c is directly input to the drive signal calculation unit 4g. It was made. The calculation contents of the current command value setting unit 4b and the voltage margin value setting unit 4j
Are the same as those in the first embodiment.

Then, the torque ripple compensation current calculator 4
k generates a torque ripple compensation current value for correcting the current command value so as to cancel the torque fluctuation from the electric angle signal and the current command value described in the first embodiment. In the same manner as in the first embodiment, a feedback current value (a non-commutation phase current value) calculated from the electrical angle signal and the signal from the current detection circuit 9 is used as the current control unit 4c.
The current controller 4c sets the target voltage value so that the second current command value obtained from the sum of the current command value and the torque ripple compensation current value matches the feedback current value, and calculates the drive signal. Drive signal calculation unit 4 in addition to the
g outputs a three-phase PWM signal based on the electrical angle signal and the target voltage value, and drives the DC brushless motor 7.

As described above, in the electric power steering control device according to the second embodiment of the present invention, similarly to the first embodiment, current command value setting section 4b subtracts the voltage margin and the back electromotive voltage from the power supply voltage. Calculates the maximum current command value from the calculated current value, and determines the current command value by comparing it with the target current value.This makes it possible to suppress torque ripple, reduce vibration applied to the steered wheels, and reduce noise. Can be done. The voltage margin value setting unit 4j, like the first embodiment, converts the motor back electromotive voltage conversion table shown in FIG.
A voltage margin can be obtained by storing any one of the motor rotation speed conversion table in FIG. 7, a preset constant voltage, and an arithmetic expression.

Embodiment 3 FIG. 9 is a block diagram illustrating a configuration of an electric power steering control device according to Embodiment 3 of the present invention. In this embodiment, the rotational position of DC brushless motor 7 shown in Embodiment 1 is detected. Hall sensor I / F circuit 11 and Hall sensor 12
The resolver 12d and the resolver I / F circuit 13 are used in place of a, 12b, and 12c, and the current command value output from the current command value command unit 4b and the electrical angle signal obtained from the electrical angle calculation unit 4e are used. A torque ripple compensation current calculation unit 4k for inputting and compensating torque ripple is additionally provided, and the torque ripple compensation current calculation unit 4k corrects the current command value so as to cancel the torque ripple from the electric angle signal and the current command value. A torque ripple compensation current value is generated, and the current control unit 4c
Sets the target voltage value from the sum of the current command value and the torque ripple compensation current value and the feedback signal of the circuit current, and sets the target voltage value to the torque ripple compensation voltage generated by the torque ripple compensation voltage calculation unit 4f. The values are added and added to the drive signal calculation unit 4g.

In the electric power steering control device according to the third embodiment of the present invention, the torque ripple compensation current calculation unit 4k uses the electric angle signal obtained from the resolver 12d and the current command value to calculate the torque ripple compensation current. To correct the current command value so as to cancel the torque fluctuation, and correct the target voltage value obtained from the corrected current command value by the torque ripple compensation voltage for further compensating the neutral point voltage, and commutation The rise and fall of the current at the time are controlled. Further, since the current command value setting unit 4b calculates the current command value based on the voltage margin value as in the first embodiment, the torque ripple suppressing effect is assured and the steering performance can be further stabilized. It is. Note that the voltage margin value setting unit 4j, like the first embodiment, converts the motor back electromotive voltage conversion table in FIG. 2, the motor rotation speed conversion table in FIG. 7, a predetermined constant voltage, or an arithmetic expression. Any of them can be stored to obtain a voltage margin.

Embodiment 4 FIG. FIG. 10 is a block diagram illustrating a configuration of an electric power steering control device according to Embodiment 4 of the present invention. In the figure, reference numeral 1 denotes a torque sensor provided on a steering shaft, and 2 denotes a vehicle speed sensor for detecting a traveling speed. ,
3 is a voltage detection circuit for detecting a power supply voltage, 4 is a control device including a microcomputer for inputting signals of these sensors, 5 is a drive circuit for driving a three-phase inverter 6 by a signal from the control device 4, and 7 is a drive circuit. A DC brushless motor 9 that applies an auxiliary torque to the steering device by the electric power from the inverter 6. Current detection circuit, 11 is D
Hall sensor 12 provided in C brushless motor 7
a, 12b, and 12c are applied to the control device 4 to detect the rotation angle of the DC brushless motor 7.
This is an F circuit.

The control device 4 is a software configuration block. The target current value calculator 4a calculates the target current of the DC brushless motor 7 based on the outputs of the torque sensor 1 and the vehicle speed sensor 2, and the target current value calculator 4a. Command value setting unit 4b for setting a current based on signals from the voltage detection circuit 3 and the like, a current control unit 4c for controlling a supply current according to a command from the current command value setting unit 4b, and a feedback current value (non-commutation) A current value of the phase) to the current control unit 4c, an electric angle calculation unit 4e that calculates an electric angle signal of the DC brushless motor 7 based on a signal of the Hall sensor I / F circuit 11, and an electric angle Arithmetic unit 4
The torque ripple compensation voltage calculation unit 4f that outputs a torque ripple compensation voltage based on the signal e and the feedback current value, the signal of the current control unit 4c, the signal of the torque ripple compensation voltage calculation unit 4f, and the electrical angle signal are input. A driving signal calculating unit 4g for controlling the voltage of the driving circuit 5, a motor rotation speed calculating unit 4h for calculating the rotation speed of the DC brushless motor 7 based on the output of the electrical angle calculation unit 4e, and a back electromotive force based on the motor rotation speed. A motor back electromotive voltage calculation unit 4i for calculating
It comprises a voltage margin value setting unit 4j which calculates a voltage margin value from the back electromotive force and gives the voltage margin value to the current command value setting unit 4b.

The electric power steering control device according to the fourth embodiment of the present invention is different from the first embodiment in that the input to the torque ripple compensation voltage calculator 4f is an electric angle signal and a feedback current value. Then, the torque ripple compensation voltage calculation unit 4f applies a voltage to a phase which is normally turned off at the time of commutation in order to control the rise and fall of the current at the time of commutation, as in the above-described prior art document 2. Configured to generate a target voltage. The drive signal calculator 4g is configured to supply a current based on the electrical angle signal output by the electrical angle calculator 4e, the target voltage value output by the current controller 4c, and the target voltage output by the torque ripple compensation voltage calculator 4f. -Phase PWM signal for a two-phase PWM signal and a PWM signal for a phase that is normally off during commutation
Generate an M signal.

As described above, the method of suppressing the torque ripple is different from that of the first embodiment. However, similarly to the first embodiment, the target voltage value output from the current control unit 4c is set to the current command value setting unit 4b. Is calculated based on the current command value that is calculated and output. Since the current command value is calculated from the value obtained by subtracting the voltage margin value and the back electromotive voltage from the power supply voltage, the voltage margin required for reducing the torque ripple is calculated. The value can be secured, vibration applied to the steered wheels can be reduced, and noise can be suppressed. The voltage margin value setting unit 4
j is a voltage obtained by storing any of the motor back electromotive voltage conversion table of FIG. 2, the motor rotation speed conversion table of FIG. 7, a preset constant voltage, or an arithmetic expression, as in the first embodiment. It is something that can afford.

Embodiment 5 FIG. FIG. 11 is a block diagram illustrating a configuration of an electric power steering control device according to a fifth embodiment of the present invention. This embodiment is different from the fourth embodiment in that an electric angle signal of DC brushless motor 7 is detected. Is obtained from the resolver 12d and the resolver I / F circuit 13, and a torque ripple compensation current calculation unit 4k for inputting an electric angle signal obtained from the resolver I / F circuit 13 and compensating for torque ripple is additionally provided. The torque ripple compensation current calculation unit 4k generates a torque ripple compensation current value for correcting the current command value from the electric angle signal and the current command value so as to cancel the fluctuation of the torque.
c sets the target voltage value from the sum of the current command value and the torque ripple compensation current value and the feedback signal of the circuit current and outputs the target voltage value to the drive signal calculation unit 4g. 4, a target voltage and an electrical angle signal applied to a phase which is normally turned off at the time of commutation for controlling the rise and fall of the current at the time of commutation generated by the torque ripple compensation voltage calculation unit 4f. Is input.

As described above, in the electric power steering control apparatus according to Embodiment 5 of the present invention, the drive signal calculating section 4g includes the electric angle signal of the electric angle calculating section 4e and the target voltage value output by the current control section 4c. From the compensation voltage value output from the torque ripple compensation voltage calculation unit 4f, a three-phase PWM signal of a PWM signal for two phases to be energized and a PWM signal for a phase which is normally turned off during commutation is generated.
The target voltage value output by the current control unit 4c is determined by the resolver 12
d is obtained from the current command value corrected by the torque ripple compensation current generated by the electric angle signal obtained from the current angle d. The current command value input to the current control unit 4c is a current command value setting unit 4b. Is calculated from the value obtained by subtracting the voltage margin value and the back electromotive voltage from the power supply voltage. Therefore, similarly to the second embodiment, the effect of suppressing the torque ripple becomes more reliable, and the steering performance can be further stabilized. As in the first embodiment, the voltage margin value setting unit 4j may be any of the motor back electromotive voltage conversion table shown in FIG. 2, the motor rotation speed conversion table shown in FIG. 7, a predetermined constant voltage, or an arithmetic expression. Is stored to obtain a voltage margin value.

[0037]

As described above, according to the electric power steering control device of the present invention, the control device for controlling the current for driving the DC brushless motor is different from the control device for controlling the current for driving the DC brushless motor by the technique of suppressing the torque ripple by each method. A command value setting unit is provided. The current command value setting unit sets a voltage margin value based on a motor back electromotive voltage and a motor rotation speed, and sets a current command value based on a value obtained by subtracting the voltage margin value from the power supply voltage. With this configuration, the torque ripple of the DC brushless motor can be completely removed regardless of the fluctuation of the power supply voltage in the entire rotation range, and an electric power steering control device with good operability can be obtained. It is.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an electric power steering control device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an operation of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an operation of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating an operation of the first embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating the operation of the first embodiment of the present invention.

FIG. 6 is an explanatory diagram illustrating an operation of the first embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating an operation of the first embodiment of the present invention.

FIG. 8 is a block diagram illustrating a configuration of an electric power steering control device according to a second embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of an electric power steering control device according to a third embodiment of the present invention.

FIG. 10 is a block diagram illustrating a configuration of an electric power steering control device according to a fourth embodiment of the present invention.

FIG. 11 is a block diagram illustrating a configuration of an electric power steering control device according to a fifth embodiment of the present invention.

[Description of Signs] 1 torque sensor, 2 vehicle speed sensor, 3 voltage detection circuit, 4 control device, 4a target current value calculation unit, 4b current command value setting unit, 4c current control unit, 4d feedback current calculation unit, 4e electrical angle Calculation section, 4f Torque ripple compensation voltage calculation section, 4g drive signal calculation section, 4h
Motor rotation speed calculator, 4i motor back electromotive voltage calculator, 4
j Voltage margin setting section, 4k torque ripple compensation current calculation section, 5 drive circuit, 6 inverter, 7 DC brushless motor, 8a, 8b phase current detection resistor, 9 current detection circuit, 10 neutral point voltage detection circuit, 11 Hall sensor I / F circuit, 12a, 12b, 12c Hall sensor, 12d resolver, 13 resolver I / F circuit.

Continued on the front page F term (reference) 3D032 CC08 DA15 DA23 DA63 DA64 DA65 DD10 DD17 EA01 EB11 EC23 GG01 3D033 CA03 CA13 CA16 CA20 CA21 5H560 AA10 BB04 BB07 BB12 DA02 DA10 DA14 DA18 DA19 DC01 DC03 DC12 DC13 EB01 XRR XA X02 X

Claims (11)

[Claims] 1. A rotation angle calculation means for calculating an electric angle signal and a rotation speed of a DC brushless motor, a compensation signal calculation means for calculating a torque ripple compensation signal of the DC brushless motor, and a control signal based on a steering torque and a traveling speed of the vehicle. The DC
A target current value calculating means for calculating a target current value for driving the brushless motor; a voltage margin value setting means for setting a voltage margin value with respect to a power supply voltage for preventing distortion of the DC brushless motor driving current due to insufficient voltage; Current command value setting means for setting a current command value from a target current value, a power supply voltage value and the voltage margin value, a drive circuit for the DC brushless motor based on the current command value, the torque ripple compensation signal and the electric angle signal An electric power steering control device, further comprising a drive signal calculating means for outputting a PWM signal. 2. A rotation angle detection means for detecting an electric angle signal and a rotation speed of the DC brushless motor, a compensation voltage calculation means for calculating a torque ripple compensation signal from a neutral point voltage of a field coil of the DC brushless motor, Target current value calculating means for calculating a target current value for driving the DC brushless motor based on a steering torque and a traveling speed of the vehicle; and a voltage margin with respect to a power supply voltage for preventing distortion of the DC brushless motor driving current due to insufficient voltage. Voltage margin value setting means for setting a value, current command value setting means for setting a current command value from the target current value, the power supply voltage value and the voltage margin value, addition of the current command value and the torque ripple compensation signal A drive signal calculating means for outputting a PWM signal to a drive circuit of the DC brushless motor from the value and the electrical angle signal. Electric power steering control device. 3. A rotation angle detecting means for detecting an electric angle signal and a rotation speed of the DC brushless motor, and a target current value calculation for calculating a target current value for driving the DC brushless motor from a steering torque and a traveling speed of the vehicle. Means, voltage margin value setting means for setting a voltage margin value with respect to a power supply voltage for preventing distortion of the DC brushless motor driving current due to insufficient voltage, and a current margin based on the target current value, the power supply voltage value, and the voltage margin value. Current command value setting means for setting a command value,
Compensation current calculating means for calculating a torque ripple compensation signal from the current command value and the electric angle signal; driving the DC brushless motor from the sum of the current command value and the torque ripple compensation signal and the electric angle signal; PW in circuit
An electric power steering control device comprising a drive signal calculating means for outputting an M signal. 4. A rotation angle detecting means for detecting an electric angle signal and a rotation speed of the DC brushless motor, and a target current value calculation for calculating a target current value for driving the DC brushless motor from a steering torque and a traveling speed of the vehicle. Means, voltage margin value setting means for setting a voltage margin value with respect to a power supply voltage for preventing distortion of the DC brushless motor driving current due to insufficient voltage, and a current margin based on the target current value, the power supply voltage value, and the voltage margin value. Current command value setting means for setting a command value,
A compensation current calculation means for calculating a first torque ripple compensation signal from the current command value and the electrical angle signal;
Compensation voltage calculation means for calculating a second torque ripple compensation signal from a neutral point voltage of a field coil of the brushless motor,
A current control means for calculating a command voltage from an added value of the current command value and the first torque ripple compensation signal, from a sum of the command voltage and the second torque ripple compensation signal and the electrical angle signal; An electric power steering control device comprising: a drive circuit for outputting a PWM signal to a drive circuit of the DC brushless motor. 5. A rotation angle detecting means for detecting an electric angle signal and a rotation speed of the DC brushless motor, and a target current value calculation for calculating a target current value for driving the DC brushless motor from a steering torque and a traveling speed of the vehicle. Means, voltage margin value setting means for setting a voltage margin value with respect to a power supply voltage for preventing distortion of the DC brushless motor driving current due to insufficient voltage, and a current margin based on the target current value, the power supply voltage value, and the voltage margin value. Current command value setting means for setting a command value,
Feedback signal calculating means for generating a feedback signal from the electric circuit current of the DC brushless motor and the electrical angle signal and providing the feedback signal to the current control means; current control for calculating a command voltage to match the feedback signal with the current command value Means, a compensation voltage calculating means for calculating a compensation voltage from the feedback signal and the electric angle signal, a PWM signal for two phases to be energized from the command voltage, the compensation voltage and the electric angle signal, PWM of compensation voltage applied to phase that is normally off
An electric power steering control device, comprising: a drive signal calculation unit that supplies a signal to a drive unit of the DC brushless motor. 6. A rotation angle detecting means for detecting an electric angle signal and a rotation speed of the DC brushless motor, and a target current value calculation for calculating a target current value for driving the DC brushless motor from a steering torque and a traveling speed of the vehicle. Means, voltage margin value setting means for setting a voltage margin value for a power supply voltage to prevent distortion of the DC brushless motor drive current due to insufficient voltage, a current command value from the target current value, the power supply voltage value, and the voltage margin value Current command value setting means for setting
Compensation current computing means for computing a torque ripple compensation signal from the current command value and the electrical angle signal; current control means for computing a command voltage from the sum of the current command value and the torque ripple compensation signal; Feedback signal calculating means for generating a feedback signal from the electric circuit current of the motor and the electrical angle signal and providing the feedback signal to the current control means, in order to make the added value of the current command value and the torque ripple compensation signal coincide with the feedback signal; Current control means for calculating a command voltage, compensation voltage calculation means for generating a compensation voltage from the feedback signal and the electric angle signal, and two-phase to be energized from the command voltage, the compensation voltage and the electric angle signal. A PWM signal;
An electric power steering control device, comprising: a drive signal calculating unit that supplies a PWM signal of a compensation voltage applied to a phase that is normally turned off during commutation to a driving unit of the DC brushless motor. 7. The voltage margin value set by the voltage margin value setting means is calculated using a back electromotive voltage calculated from the rotation speed of the DC brushless motor as a parameter. The electric power steering control device according to claim 1. 8. The method according to claim 1, wherein the voltage margin value set by the voltage margin value setting means is calculated by using a rotation speed of the DC brushless motor as a parameter. Electric power steering control device. 9. The electric power steering control device according to claim 1, wherein the voltage margin value set by the voltage margin value setting means is a predetermined constant value. . 10. The method according to claim 1, wherein the voltage margin value set by the voltage margin value setting means is calculated by a predetermined arithmetic expression. Electric power steering control device. 11. The current command value set by the current command value setting means is such that the maximum current command value is TImax, the power supply voltage is a,
7. When the voltage margin value is b, the motor back electromotive voltage is e, and the motor winding resistance value is d, TImax = (ab-e) / d is obtained. The electric power steering control device according to claim 1.