JP3846888B2 - Electric power steering control device and electric power steering control method - Google Patents

Description

  The present invention relates to an electric power steering control device and an electric power steering control method, and more particularly to an electric power steering control device and an electric power steering control method used when current-controlling a DC motor.

  2. Description of the Related Art A power steering device that reduces a force for operating a steering wheel for steering an automobile is known. Such a power steering device includes a steering wheel, a manual steering torque detection device, a battery, an electric power steering control device, a DC motor, and a front wheel. The front wheels are used when propelling the automobile by rotating around the rotation axis. The steering wheel is operated by the driver of the automobile to change the direction in which the automobile is propelled by rotating the rotating shaft of the front wheel. The manual steering torque detector measures the steering torque applied to the steering wheel by the driver's operation. The manual steering torque detection device further calculates a target current based on the steering torque. The battery outputs electric power to the outside as a direct current.

  The electric power steering control device is composed of an electronic control unit (ECU). The electric power steering control device supplies the electric power generated by the battery to the DC motor, and controls the electric power based on the target current calculated by the manual steering torque detection device. The DC motor converts electric power supplied from the electric power steering control device into rotational power. The rotational power is used to reduce the force for operating the handle.

  FIG. 7 shows a known electric power steering control device. The electric power steering control device 101 includes a peak current value detection unit 111, a current detection correction unit 112, a deviation calculation unit 113, a motor operation control unit 114, and a motor drive unit 115 formed from an electric circuit.

  The peak current value detection unit 111 measures the current flowing through the DC motor 106 every sampling period. The peak current value detection unit 111 further outputs an ISP signal 116 indicating the detected peak current value ISP which is the actually measured current value to the current detection correction unit 112. The current detection correction unit 112 calculates a correction current value based on the detected peak current value ISP indicated by the ISP signal 116, and outputs an IPM signal 117 indicating the correction current value to the deviation calculation unit 113. The deviation calculation unit 113 calculates a deviation between the target current indicated by the IT signal 118 output from the manual steering torque detection device and the correction current value indicated by the IPM signal 117, and uses the deviation signal 119 indicating the deviation as the motor operation. Output to the control unit 114.

  The motor operation control unit 114 calculates the pulse width at regular intervals based on the deviation indicated by the deviation signal 119. As the pulse width, a value is calculated such that the deviation indicated by the deviation signal 119 becomes zero when a pulse having the pulse width is applied to the DC motor 106 every pulse period. The motor operation control unit 114 outputs a PWM signal 120 indicating the pulse width to the motor driving unit 115. The motor driving unit 115 applies a pulse having a pulse width based on the PWM signal 120 and having a pulse height of the voltage of the battery 105 to the DC motor 106 at each pulse period. That is, the motor operation control unit 114 and the motor driving unit 115 change the ratio (duty) of the time for applying voltage to the DC motor 106 with respect to the pulse period, that is, the time for applying the voltage to the DC motor 106 and the DC motor. Predetermined power is supplied to the DC motor 106 so that the deviation indicated by the deviation signal 119 becomes zero by pulse width modulation control (PWM control) that changes the ratio with the time during which no voltage is applied to 106.

  FIG. 8 shows the current detection correction unit 112 in detail. The current detection correction unit 112 includes a correction amount search unit 123 and a deviation calculation unit 125 formed from an electric circuit. The correction amount search unit 123 calculates a correction amount based on the detected peak current value ISP indicated by the ISP signal 116, and outputs a correction amount signal 129 indicating the correction amount to the deviation calculation unit 125. The deviation calculation unit 125 calculates a correction current value IPM by subtracting the correction amount indicated by the correction amount signal 129 from the detected peak current value ISP indicated by the ISP signal 116, and generates an IPM signal 130 indicating the correction current value IPM. Output. The IPM signal 130 matches the IPM signal 117.

  The correction amount search unit 123 includes a storage device that records a correction table. The correction table 141 associates the detected peak current value ISP with the correction amount C as shown in FIG. At this time, when the ISP signal 116 indicates the detected peak current value ISP ′, the correction amount search unit 123 refers to the correction table 141 and corrects the correction amount corresponding to the detected peak current value ISP ′ from among the correction amounts C. C ′ is searched, and a correction amount signal 129 indicating the correction amount C ′ is output to the deviation calculation unit 125.

  According to a known electric power steering control method, the electric power steering control device 101 first acquires the target current IT calculated based on the steering torque applied to the steering wheel by the operation of the driver from the manual steering torque detection device. . The electric power steering control device 101 uses the peak current value detection unit 111 to measure the detected peak current value ISP flowing through the DC motor 106. The electric power steering control device 101 calculates a correction amount C associated with the detected peak current value ISP by using the correction table 141. The electric power steering control device 101 calculates the correction current value IPM by subtracting the correction amount C from the detected peak current value ISP. The electric power steering control device 101 calculates the pulse width of the pulse so that the deviation between the target current IT and the correction current value IPM becomes zero when a pulse is applied to the DC motor 106 every pulse period. The electric power steering control device 101 applies a pulse having a pulse width of which the voltage is the voltage of the battery 105 to the DC motor 106 at each pulse period to supply electric power to the DC motor 106. That is, the electric power steering control device 101 supplies predetermined power to the DC motor 106 by pulse width modulation control (PWM control) so that the deviation between the target current IT and the correction current value IPM becomes zero. Such an operation is repeatedly executed at regular intervals longer than the pulse cycle.

  FIG. 10 shows a relationship 151 between the current IM that actually flows through the DC motor 106 and the detected peak current value ISP. The relationship between the detected peak current value ISP and the current IM is indicated by a curve 152. There is an error between the current IM actually flowing through the DC motor 106 and the detected peak current value ISP. Further, the ratio between the current IM and the detected peak current value ISP is relatively large in a region where the detected peak current value ISP is small. Such a large error is generated when the pulse width of the pulse applied to the DC motor 106 is small, that is, when the steering wheel starts to be turned. According to such an electric power steering control method, such an error in current can be corrected.

  According to such an electric power steering control method, the electric power steering control device 101 can control the DC motor 106 more appropriately, improving the assist feeling of the power steering, particularly when starting to turn the steering wheel. The power steering assist feeling can be improved. An automobile is desired to further improve the assist feeling of power steering. The direct current motor control device is desired to control the direct current motor more appropriately.

  Japanese Patent Application Laid-Open No. 2003-137109 discloses a method for controlling an electric power steering device that can obtain sufficient assist by reducing a difference from a target assist current even in a region where the target current is small. The control method of the electric power steering apparatus detects a peak value ISP of a motor current flowing in a motor to be driven and controlled by a PWM signal generated according to a target current signal IT, and performs feedback control based on the detected peak current value ISP. At this time, the detected peak current value ISP is corrected, and this correction value IPM is used for feedback control. The detected peak current value IPS is corrected based on the current correction table. Further, the current correction correspondence correction table is obtained from the relationship between the average value Ia of the current flowing through the motor when the motor is used and the detected peak current value ISP.

JP 2003-137109 A

An object of the present invention is to provide an electric power steering control device and an electric power steering control method that improve the assist feeling of power steering.
Another object of the present invention is to provide an electric power steering control device and an electric power steering control method that can improve the assist feeling of power steering at a lower cost.
Still another object of the present invention is to provide an electric power steering control device and an electric power steering control method for reducing the storage capacity of a storage device used for improving the assist feeling of power steering.
Still another object of the present invention is to provide a direct current motor control device that performs current control of a direct current motor more appropriately.

  In the following, means for solving the problems will be described using the reference numerals used in the best modes and embodiments for carrying out the invention in parentheses. This reference numeral is added to clarify the correspondence between the description of the claims and the description of the best mode for carrying out the invention / example, and is described in the claims. It should not be used to interpret the technical scope of the invention.

  The electric power steering control device (1) according to the present invention has a force when operating a voltmeter (21) for measuring a voltage (E) of a battery (5) and a handle (3) for steering an automobile (2). An ammeter (11) that measures the current (ISP) flowing through the DC motor (6) that generates the power to be reduced, and a control that calculates the correction current value (IPM) based on the voltage (E) and the current (ISP) From the battery (5) to the DC motor (6) so that the correction current value (IPM) matches the target current value (IT) calculated based on the steering torque applied to the device (12) and the steering wheel (3). And a motor drive circuit (13, 14, 15) for supplying electric power.

  As shown in the graph of FIG. 6, the current (ISP) measured by the ammeter (11) has an error between the current (IM) actually flowing through the DC motor (6). The error with respect to the current (ISP) depends on the voltage (E) of the battery (5). That is, as a graph showing the error with respect to the current (ISP), a plurality of graphs having different shapes for each voltage (E) are formed. According to the electric power steering control device (1), such an error in current can be corrected. For this reason, the electric power steering control device (1) can more appropriately control the current of the DC motor (6), and can improve the assist feeling of the power steering.

  The motor drive circuit (13, 14, 15) is a pulse width modulation control that changes the ratio of the time during which the voltage (E) is applied to the DC motor (6) and the time during which the voltage (E) is not applied to the DC motor (6). Thus, electric power is supplied from the battery (5) to the DC motor (6) so that the correction current value (IPM) matches the target current value (IT). That is, the electric power steering control device (1) according to the present invention is preferably applied when power is supplied to the DC motor (6) by pulse width modulation control.

  The controller (12) calculates the parameter (B) based on the correction table (41) that associates the plurality of parameters (B) with the plurality of correction amounts (C), and the current (ISP) and the voltage (E) ( B) A first correction amount search unit (23) that extracts a first correction amount (C) corresponding to the parameter (B) of the plurality of correction amounts (C) with reference to the calculation unit and the correction table (41). And an actual correction amount calculation unit (24) for calculating an actual correction amount (VAL) based on the first correction amount (C) and the voltage (E), and subtracting the actual correction amount (VAL) from the current (ISP) And a correction current value calculation unit (25) for calculating a correction current value (IPM). Such a correction table (41) has a smaller amount of information than the correction table (41) in which the combination of the current (ISP) value and the voltage (E) value is associated with the correction current value (IPM). The electric power steering control device (1) uses a correction table (41) for associating a combination of a current (ISP) value and a voltage (E) value with a correction current value (IPM), so that the memory of the mounted storage device can be used. The capacity can be reduced.

  The function that associates the first correction amount (C) with the actual correction amount (VAL) is preferably an inverse function of the function that associates the current (ISP) with the parameter (B). The parameter (B) is a value obtained by multiplying the current (ISP) by a reciprocal of a multiple of the voltage (E), and the actual correction amount (VAL) is a value obtained by multiplying the first correction amount (C) by a multiple. Is more preferable.

  The controller (12) includes a correction table (41) for associating a combination of one value of the plurality of current (ISP) values and one value of the plurality of voltage (E) values with the plurality of current (ISP) values. , Referring to the correction table (41), the current (ISP) value corresponding to the set formed from the current (ISP) and the voltage (E) among the plurality of correction current values (IPM) is calculated as the correction current value (IPM). ) As a calculation unit. At this time, the electric power steering control device (1) is preferable in that the correction current value (IPM) can be calculated more quickly.

  The automobile (2) according to the present invention preferably includes the electric power steering control device (1) according to the present invention, a battery (5), a handle (3), and a DC motor (6).

  The electric power steering control method according to the present invention includes the step (S3) of measuring the voltage (E) of the battery (5) and the power for reducing the force when operating the steering wheel (3) for steering the automobile (2). A step (S2) of measuring a current (ISP) flowing through the DC motor (6) to be generated, and a step of calculating a correction current value (IPM) based on the voltage (E) and the current (ISP) (S4 to S7) Then, electric power is supplied from the battery (5) to the DC motor (6) so that the correction current value (IPM) matches the target current value (IT) calculated based on the steering torque applied to the steering wheel (3). Steps (S8 to S9).

  The current (ISP) measured by the ammeter (11) has an error with respect to the current (IM) actually flowing through the DC motor (6) as shown in the graph of FIG. The error with respect to the current (ISP) depends on the voltage (E) of the battery (5). That is, as a graph showing the error with respect to the current (ISP), a plurality of graphs having different shapes for each voltage (E) are formed. According to the electric power steering control method, such an error in current can be corrected. For this reason, the electric power steering control method can more appropriately control the current of the DC motor (6), and can improve the assist feeling of the power steering.

  The step of supplying power to the DC motor (6) (S8 to S9) is a ratio between the time during which the voltage (E) is applied to the DC motor (6) and the time during which the voltage (E) is not applied to the DC motor (6). This is executed by the pulse width modulation control for modulating. That is, the electric power steering control method according to the present invention is preferably applied when power is supplied to the DC motor (6) by pulse width modulation control.

  The steps (S4 to S7) for calculating the corrected current value (IPM) include a step (S4) for calculating the parameter (B) based on the current (ISP) and the voltage (E), and a plurality of parameters (B). With reference to the correction table (41) associated with the correction amount (C), a step (S5) of extracting a first correction amount (C) corresponding to the parameter (B) of the plurality of correction amounts (C), 1 A step of calculating an actual correction amount (VAL) based on the correction amount (C) and the voltage (E) (S6), and subtracting the actual correction amount (VAL) from the current (ISP) to obtain a correction current value (IPM ) Is calculated (S7). Such a correction table (41) has a smaller amount of information than the correction table (41) in which the combination of the current (ISP) value and the voltage (E) value is associated with the correction current value (IPM). The electric power steering control device (1) for executing the electric power steering control method according to the present invention has a correction table (41) for associating a combination of a current (ISP) value and a voltage (E) value with a correction current value (IPM). By using it, the storage capacity of the storage device to be mounted can be reduced.

  The function that associates the first correction amount (C) with the actual correction amount (VAL) is preferably an inverse function of the function that associates the current (ISP) with the parameter (B). The parameter (B) is a value obtained by multiplying the current (ISP) by a reciprocal of a multiple of the voltage (E), and the actual correction amount (VAL) is a value obtained by multiplying the first correction amount (C) by a multiple.

  The step of calculating the corrected current value (IPM) includes correcting a combination of one value of the plurality of current (ISP) values and one value of the plurality of voltage (E) values to the plurality of current (ISP) values. With reference to the table (41), a current (ISP) value corresponding to a set formed from a current (ISP) and a voltage (E) among a plurality of corrected current values (IPM) is defined as a corrected current value (IPM). calculate. According to the electric power steering control method of the present invention, the correction current value (IPM) is preferably calculated more quickly.

  A DC motor control device (1) according to the present invention includes a voltmeter (21) for measuring a voltage (E) of a battery (5), and an ammeter (11) for measuring a current (ISP) flowing through the DC motor (6). And a controller (12) for calculating a corrected current value (IPM) based on the voltage (E) and current (ISP), and the corrected current value (IPM) in the target current value (IT) input from the outside. A motor drive circuit (13, 14, 15) for supplying electric power from the battery (5) to the DC motor (6) is provided so as to match.

  As shown in the graph of FIG. 6, the current (ISP) measured by the ammeter (11) has an error between the current (IM) actually flowing through the DC motor (6). The error with respect to the current (ISP) depends on the voltage (E) of the battery (5). That is, as a graph showing the error with respect to the current (ISP), a plurality of graphs having different shapes for each voltage (E) are formed. According to the DC motor control device (1), such an error in current can be corrected. For this reason, DC motor control device (1) can carry out current control of DC motor (6) more appropriately.

  The motor drive circuit (13, 14, 15) is a pulse width modulation control that changes the ratio of the time during which the voltage (E) is applied to the DC motor (6) and the time during which the voltage (E) is not applied to the DC motor (6). Thus, electric power is supplied from the battery (5) to the DC motor (6) so that the correction current value (IPM) matches the target current value (IT). That is, the DC motor control device (1) according to the present invention is preferably applied when power is supplied to the DC motor (6) by pulse width modulation control.

  The controller (12) calculates the parameter (B) based on the correction table (41) that associates the plurality of parameters (B) with the plurality of correction amounts (C), and the current (ISP) and the voltage (E) ( B) Referring to the calculation unit and the correction table (41), the first correction amount search unit (23) that extracts the first correction amount (C) corresponding to the parameter (B) among the plurality of correction amounts (C). ), The first correction amount (C) and the voltage (E), the actual correction amount calculation unit (24) for calculating the actual correction amount (VAL), and the actual correction amount (VAL) from the current (ISP). A correction current value calculation unit (25) that calculates a correction current value (IPM) by subtraction. Such a correction table (41) has a smaller amount of information than the correction table (41) in which the combination of the current (ISP) value and the voltage (E) value is associated with the correction current value (IPM). The DC motor control device (1) uses a correction table (41) that associates a combination of a current (ISP) value and a voltage (E) value with a correction current value (IPM), so that the storage capacity of the mounted storage device Can be reduced.

  The function that associates the first correction amount (C) with the actual correction amount (VAL) is preferably an inverse function of the function that associates the current (ISP) with the parameter (B). The parameter (B) is a value obtained by multiplying the current (ISP) by a reciprocal of a multiple of the voltage (E), and the actual correction amount (VAL) is a value obtained by multiplying the first correction amount (C) by a multiple.

  The controller (12) includes a correction table (41) for associating a combination of one value among the plurality of current (ISP) values and one value among the plurality of voltage (E) values with the plurality of current (ISP) values. With reference to the correction table (41), the current (ISP) value corresponding to the set formed from the current (ISP) and the voltage (E) among the plurality of correction current values (IPM) is corrected to the correction current value (IPM). ) As a calculation unit. At this time, it is preferable that the DC motor control device (1) can calculate the correction current value (IPM) faster.

  According to the electric power steering control device and the electric power steering control method of the present invention, it is possible to more appropriately control the current of the DC motor, and to improve the assist feeling of the power steering.

  An embodiment of an electric power steering control device according to the present invention will be described with reference to the drawings. The electric power steering control device 1 is applied to an automobile 2 as shown in FIG. The automobile 2 includes a handle 3, a manual steering torque detection device 4, a battery 5, an electric power steering control device 1, a DC motor 6, and a front wheel 7. The front wheel 7 is used when propelling the automobile 2 by rotating around the rotation axis. The handle 3 is operated by the driver of the automobile 2 and rotates the rotation shaft of the front wheel 7 to change the direction in which the automobile 2 is propelled. The manual steering torque detection device 4 measures the steering torque applied to the handle 3 by the operation of the driver. The manual steering torque detection device 4 further calculates a target current based on the steering torque. The battery 5 converts electrical energy obtained from the outside into chemical energy and stores it, and outputs electric power to the outside as a direct current as necessary.

  The electric power steering control device 1 is configured by an electronic control unit (ECU). The electric power steering control device 1 supplies the electric power generated by the battery 5 to the DC motor 6 based on the target current calculated by the manual steering torque detection device 4. The DC motor 6 converts electric power supplied from the electric power steering control device 1 into rotational power. The rotational power is used to reduce the force for operating the handle 5.

  FIG. 2 shows the electric power steering control device 1 in detail. The electric power steering control device 1 includes a peak current value detection unit 11, a current detection correction unit 12, a deviation calculation unit 13, a motor operation control unit 14, and a motor drive unit 15 formed from an electric circuit.

  The peak current value detector 11 measures the current flowing through the DC motor 6 at every sampling period. The peak current value detection unit 11 further outputs an ISP signal 16 indicating the detected peak current value that is the actually measured current value to the current detection correction unit 12. The current detection correction unit 12 calculates a correction current value based on the detected peak current value indicated by the ISP signal 16, and outputs an IPM signal 17 indicating the correction current value to the deviation calculation unit 13. The deviation calculation unit 13 calculates a deviation between the target current indicated by the IT signal 18 output from the manual steering torque detection device 4 and the correction current value indicated by the IPM signal 17, and uses the deviation signal 19 indicating the deviation as a motor. Output to the operation control unit 14.

  The motor operation control unit 14 calculates the pulse width at regular intervals based on the deviation indicated by the deviation signal 19. As the pulse width, a value is calculated such that the deviation indicated by the deviation signal 19 becomes zero when a pulse having the pulse width is applied to the DC motor 6 every pulse period. The motor operation control unit 14 outputs a PWM signal 20 indicating the pulse width to the motor driving unit 15. The motor drive unit 15 applies a pulse having a pulse width based on the PWM signal 20 and having the voltage of the battery 5 to a pulse height to the DC motor 6 at each pulse period. That is, the motor operation control unit 14 and the motor driving unit 15 change the ratio (duty) of applying voltage to the DC motor 6 with respect to the pulse period, that is, the time for applying the voltage to the DC motor 6 and the DC motor. A predetermined power is supplied to the DC motor 6 so that the deviation indicated by the deviation signal 19 becomes 0 by pulse width modulation control (PWM control) that changes the ratio of the voltage 6 to the time when no voltage is applied.

  FIG. 3 shows the current detection correction unit 12 in detail. The current detection correction unit 12 includes a battery average voltage value calculation unit 21, a correction table search parameter calculation unit 22, a correction amount search unit 23, a voltage correction amount calculation unit 24, and a deviation calculation unit 25 formed from an electric circuit. ing.

The battery average voltage value calculation unit 21 measures the voltage of the battery 5 for each sampling period. The battery average voltage value calculation unit 21 further converts the AVE signal 26 indicating the average value of a plurality of (for example, four) voltage values measured adjacent to each other in time with the correction table search parameter calculation unit 22 and the voltage correction. It outputs to the quantity calculation part 24. The correction table search parameter calculation unit 22 calculates a parameter based on the detected peak current value indicated by the ISP signal 16 and the voltage indicated by the AVE signal 26, and a parameter signal 27 indicating the parameter is calculated as the correction amount search unit 23. Output to. The parameter B uses the detected peak current value ISP indicated by the ISP signal 16, the voltage E indicated by the AVE signal 26, and the reference voltage Ef as follows:
B = (Ef / E) × ISP
It is expressed by The correction amount search unit 23 calculates a correction amount based on the parameter indicated by the parameter signal 27, and outputs a correction amount signal 28 indicating the correction amount to the voltage correction amount calculation unit 24.

The voltage correction amount calculation unit 24 calculates an actual correction amount based on the correction amount indicated in the correction amount signal 28 and outputs an actual correction amount signal 29 indicating the actual correction amount to the deviation calculation unit 25. The actual correction amount VAL is calculated by using the correction amount C indicated by the correction amount signal 28 as follows:
VAL = (E / Ef) × C
It is expressed by Thus, the function that calculates the actual correction amount VAL based on the correction amount C forms an inverse function of the function that calculates the parameter B based on the detected peak current value ISP. The deviation calculator 25 calculates a correction current value based on the actual correction amount indicated by the actual correction amount signal 29 and the detected peak current value indicated by the ISP signal 16, and outputs an IPM signal 30 indicating the correction current value. To do. The IPM signal 30 matches the IPM signal 17.

  The correction amount search unit 23 includes a storage device that records a correction table. The correction table 41 associates the parameter B with the correction amount C as shown in FIG. The relationship between the parameter B and the correction amount C is that the detected peak current value ISP measured by the peak current value detection unit 11 and the actual voltage E of the battery 5 match the reference voltage Ef (for example, 14V). This corresponds to the relationship with the correction amount VAL. At this time, when the parameter signal 27 indicates the parameter B ′, the correction amount search unit 23 searches the correction table 41 for the correction amount C ′ corresponding to the parameter B ′ from the correction amount C, and A correction amount signal 28 indicating the correction amount C ′ is output to the voltage correction amount calculation unit 24.

  In addition, the some circuit of the circuits with which the electric power steering control apparatus 1 is provided can be comprised by one CPU. The plurality of circuits are formed by a deviation calculation unit 13, a motor operation control unit 14, a correction table search parameter calculation unit 22, a correction amount search unit 23, a voltage correction amount calculation unit 24, and a deviation calculation unit 25. At this time, the CPU executes the plurality of operations by including a plurality of computer programs indicating the plurality of operations respectively executed by the plurality of circuits.

  The embodiment of the electric power steering control method according to the present invention is executed by the electric power steering control device 1. According to the electric power steering control method, as shown in FIG. 5, the electric power steering control device 1 first calculates a target current calculated based on the steering torque applied to the handle 3 by the operation of the driver. IT is acquired from the manual steering torque detector 4 (step S1). The electric power steering control device 1 measures the detected peak current value ISP flowing through the DC motor 6 using the peak current value detection unit 11 (step S2). The electric power steering control device 1 measures the voltage E of the battery 5 using the battery average voltage value calculation unit 21 (step S3).

The electric power steering control device 1 sets the parameter B to the following formula:
B = (Ef / E) × ISP
(Step S4). The electric power steering control device 1 calculates the correction amount C associated with the parameter B by using the correction table 41 (step S5). The electric power steering control device 1 calculates the actual correction amount VAL by the following formula:
VAL = (E / Ef) × C
(Step S6). The electric power steering control device 1 calculates the correction current value IPM by subtracting the actual correction amount VAL from the detected peak current value ISP (step S7).

  The electric power steering control device 1 calculates the pulse width of the pulse so that the deviation between the target current IT and the correction current value IPM becomes zero when the pulse is applied to the DC motor 6 every pulse period (step S8). ). The electric power steering control device 1 supplies a power to the DC motor 6 by applying a pulse having a pulse width, which is a pulse having a pulse height of the voltage E of the battery 5, to the DC motor 6 at each pulse period (step). S9). That is, the electric power steering control device 1 supplies predetermined power to the DC motor 6 by pulse width modulation control (PWM control) so that the deviation between the target current IT and the correction current value IPM becomes zero.

  The operations from step S1 to step S9 are repeatedly executed at regular intervals longer than the pulse cycle.

  FIG. 6 shows a relationship 51 between the voltage E, the current IM that actually flows through the DC motor 6, and the detected peak current value ISP. The relationship between the current IM and the detected peak current value ISP shows a curve 52 when the voltage E is 14V. The relationship between the current IM and the detected peak current value ISP shows a curve 53 when the voltage E is 8V. That is, the current IM that actually flows through the DC motor 6 has an error from the observed peak current value ISP. The error with respect to the detected peak current value ISP varies depending on the voltage E of the battery 5. That is, as a graph showing the error with respect to the detected peak current value ISP, a plurality of graphs having different shapes for each voltage E are formed. The plurality of graphs are similar in shape to each other. Further, the similarity ratio is approximately equal to the voltage E ratio. According to the electric power steering control method of the present invention, it is possible to correct the measured current that generates such an error to a value closer to the true value. For this reason, the electric power steering control device 1 can more appropriately control the current of the DC motor 6, and the automobile 2 can further improve the assist feeling of the power steering.

  Note that the electric power steering control method according to the present invention can also be applied to current control of a DC motor applied in addition to power steering. As a technique to which the electric power steering control method according to the present invention is applied, current control is performed on a DC motor that generates driving force of an automobile.

  In another embodiment of the electric power steering control apparatus according to the present invention, the correction table search parameter calculation unit 22, the correction amount search unit 23, and the voltage correction amount calculation unit 24 in the above-described embodiment are different correction amounts. Replaced with search part. The correction amount search unit includes another correction table. The correction table associates a combination of current and voltage with a correction current value. Such a correction table has a larger amount of information than the correction table 41. The correction amount search unit searches the correction current value corresponding to the combination of the detected peak current value indicated by the ISP signal 16 and the voltage indicated by the AVE signal 26 with reference to the correction table, and the correction current value. Is output. The IPM signal 30 matches the IPM signal 17.

  Another embodiment of the electric power steering control method according to the present invention is executed by such an electric power steering control device, and steps S4 to S7 in the above-described embodiment are replaced with other steps. In that step, the electric power steering control device refers to the correction table and calculates a correction current value corresponding to the combination of the detected peak current value indicated by the ISP signal 16 and the voltage indicated by the AVE signal 26. .

  According to such an electric power steering control method, the correction current value can be calculated faster than using the correction table 41.

FIG. 1 is a block diagram showing an embodiment of an automobile according to the present invention. FIG. 2 is a block diagram showing an embodiment of the electric power steering control device according to the present invention. FIG. 3 is a block diagram illustrating the current detection correction unit. FIG. 4 is a graph showing a correction table. FIG. 5 is a flowchart showing an embodiment of the electric power steering control method according to the present invention. FIG. 6 is a graph showing the relationship between the battery voltage, the current that actually flows through the DC motor, and the detected peak current value. FIG. 7 is a block diagram showing an embodiment of a known electric power steering control device. FIG. 8 is a block diagram showing a known current detection correction unit. FIG. 9 is a graph showing a known correction table. FIG. 10 is a graph showing a known relationship between the current actually flowing through the DC motor and the detected peak current value.

Explanation of symbols

1: Electric power steering control device 2: Automobile 3: Steering wheel 4: Manual steering torque detection device 5: Battery 6: DC motor 7: Front wheel 11: Peak current value detection unit 12: Current detection correction unit 13: Deviation calculation unit 14: Motor operation control unit 15: Motor drive unit 16: ISP signal 17: IPM signal 18: IT signal 19: Deviation signal 20: PWM signal 21: Battery average voltage value calculation unit 22: Correction table search parameter calculation unit 23: Correction amount Search unit 24: Voltage correction amount calculation unit 25: Deviation calculation unit 26: AVE signal 27: Parameter signal 28: Correction amount signal 29: Actual correction amount signal 30: IPM signal

Claims (13)

A voltmeter to measure the voltage of the battery;
An ammeter that measures the current flowing through the DC motor that generates power to reduce the force when operating the steering wheel of the automobile, and
A controller that calculates a correction current value based on the voltage and the current;
As the correction current value to the target current value calculated based on the steering torque applied to the handle matches, comprising a motor drive circuit that provides power from the battery to the DC motor,
The motor drive circuit matches the correction current value to the target current value by pulse width modulation control that changes a ratio of a time during which the voltage is applied to the DC motor and a time during which the voltage is not applied to the DC motor. To supply power from the battery to the DC motor ,
The controller is
A correction table for associating multiple parameters with multiple correction amounts;
A parameter calculator that calculates a parameter based on the current and the voltage;
Referring to the correction table, a correction amount search unit for extracting a correction amount corresponding to the parameter among the plurality of correction amounts;
An actual correction amount calculation unit that calculates the actual correction amount based on the correction amount and the voltage;
An electric power steering control device comprising: a correction current value calculation unit that calculates the correction current value by subtracting the actual correction amount from the current. In claim 1 ,
The function for causing the correction amount to correspond to the actual correction amount is an inverse function of the function for causing the current to correspond to the parameter. In claim 2 ,
The parameter is a value obtained by multiplying the current by a reciprocal of a multiple of the voltage,
The actual correction amount is a value obtained by multiplying the correction amount by the multiple. Electric power steering control device. A voltmeter to measure the voltage of the battery;
An ammeter that measures the current flowing through the DC motor that generates power to reduce the force when operating the steering wheel of the automobile, and
A controller that calculates a correction current value based on the voltage and the current;
A motor drive circuit for supplying power from the battery to the DC motor so that the correction current value matches a target current value calculated based on a steering torque applied to the steering wheel;
The motor drive circuit matches the correction current value to the target current value by pulse width modulation control that changes a ratio of a time during which the voltage is applied to the DC motor and a time during which the voltage is not applied to the DC motor. To supply power from the battery to the DC motor,
The controller is
A correction table for associating a combination of one value of the plurality of current values and one value of the plurality of voltage values with the plurality of current values;
An electric power steering control device comprising: a calculation unit that refers to the correction table and calculates a current value corresponding to a set formed from the current and the voltage of the plurality of correction current values as the correction current value . An electric power steering control device according to any one of claims 1 to 4 ,
The battery;
The handle;
An automobile comprising the DC motor. Measuring the voltage of the battery;
Measuring a current flowing through a DC motor that generates power to reduce the force when operating a steering wheel for steering an automobile;
Calculating a correction current value based on the voltage and the current;
As the correction current value to the target current value calculated based on the steering torque applied to the handle matches, comprising the steps for supplying electric power from the battery to the DC motor,
The step of supplying power to the DC motor is performed by pulse width modulation control that modulates a ratio between a time during which the voltage is applied to the DC motor and a time during which the voltage is not applied to the DC motor ,
The step of calculating the correction current value includes
Calculating a parameter based on the current and the voltage;
Extracting a correction amount corresponding to the parameter of the plurality of correction amounts with reference to a correction table associating a plurality of parameters with a plurality of correction amounts;
Calculating the actual correction amount based on the correction amount and the voltage;
Subtracting the actual correction amount from the current to calculate the correction current value. An electric power steering control method. In claim 6 ,
The function for associating the correction amount with the actual correction amount is an inverse function of the function for associating the current with the parameter. In claim 7 ,
The parameter is a value obtained by multiplying the current by a reciprocal of a multiple of the voltage,
The electric power steering control method, wherein the actual correction amount is a value obtained by multiplying the correction amount by the multiple. Measuring the voltage of the battery;
Measuring a current flowing through a DC motor that generates power to reduce the force when operating a steering wheel for steering an automobile;
Calculating a correction current value based on the voltage and the current;
Supplying power from the battery to the DC motor such that the correction current value matches a target current value calculated based on a steering torque applied to the steering wheel,
The step of supplying power to the DC motor is performed by pulse width modulation control that modulates a ratio between a time during which the voltage is applied to the DC motor and a time during which the voltage is not applied to the DC motor,
The step of calculating the correction current value refers to a correction table that associates a combination of one value of a plurality of current values and one value of a plurality of voltage values with a plurality of current values. An electric power steering control method, wherein a current value corresponding to a set formed from the current and the voltage is calculated as the correction current value. A voltmeter to measure the voltage of the battery;
An ammeter that measures the current flowing through the DC motor;
A controller that calculates a correction current value based on the voltage and the current;
As the correction current value to the target current value input from the outside are matched, comprising a motor drive circuit that provides power to the DC motor from the battery,
The motor drive circuit matches the correction current value to the target current value by pulse width modulation control that changes a ratio of a time during which the voltage is applied to the DC motor and a time during which the voltage is not applied to the DC motor. To supply power from the battery to the DC motor ,
The controller is
A correction table for associating multiple parameters with multiple correction amounts;
A parameter calculator that calculates a parameter based on the current and the voltage;
Referring to the correction table, a correction amount search unit for extracting a correction amount corresponding to the parameter among the plurality of correction amounts;
An actual correction amount calculation unit that calculates the actual correction amount based on the correction amount and the voltage;
A DC motor control device comprising: a correction current value calculation unit that calculates the correction current value by subtracting the actual correction amount from the current. According to claim 1 0,
The DC motor control device is a function that associates the correction amount with the actual correction amount and is an inverse function of a function that associates the current with the parameter. According to claim 1 1,
The parameter is a value obtained by multiplying the current by a reciprocal of a multiple of the voltage,
The actual correction amount is a value obtained by multiplying the correction amount by the multiple. A voltmeter to measure the voltage of the battery;
An ammeter that measures the current flowing through the DC motor;
A controller that calculates a correction current value based on the voltage and the current;
A motor drive circuit for supplying power from the battery to the DC motor so that the correction current value matches a target current value input from the outside,
The motor drive circuit matches the correction current value to the target current value by pulse width modulation control that changes a ratio of a time during which the voltage is applied to the DC motor and a time during which the voltage is not applied to the DC motor. To supply power from the battery to the DC motor,
The controller is
A correction table for associating a combination of one value of the plurality of current values and one value of the plurality of voltage values with the plurality of current values;
A DC motor control device comprising: a calculation unit that refers to the correction table and calculates a current value corresponding to a set formed from the current and the voltage among the plurality of correction current values as the correction current value.

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