Vehicle control device

Abstract

To provide a vehicle control device that can increase the accuracy of detecting a current value of a current actually flowing through a motor in a wide current range.SOLUTION: A current detection circuit 6 corrects an AD voltage converted from a motor current by using a correction gain (correction gain corresponding to each of a first correction amount, a second correction amount, and a third correction amount) that are multiplied by a voltage value of the AD voltage of motor current-AD voltage characteristic after first correction to match a voltage value of an AD voltage of the first corrected motor current-AD voltage characteristic at each of a first current point, a second current point, and a third current point to a voltage value of the AD voltage of an ideal motor current-AD voltage characteristic.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device having an assist function using a motor mounted on the vehicle. [Background technology]

[0002] BACKGROUND ART Conventionally, there are vehicle control devices that reduce the difference between a target torque (current command value) and an actual torque (actual current) of a motor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-27627 Summary of the Invention [Problem to be solved by the invention]

[0004] In the mounted EPS (electric power steering) system 1C shown in FIG. 6, a CPU 4C of an EPS-ECS (Electric Power Steering - Electronic Control Unit) 2C calculates a current command value and controls the current flowing through the motor 3 based on the steering force, total steering angle, vehicle speed information, and the like, and also performs feedback control based on the difference between a current command value and the current value of the current actually flowing through the motor 3, which is calculated based on the detection result of a current detection circuit 6.

[0005] The current detection circuit 6 has the configuration of a typical current detection circuit shown in Figure 7, and will be described briefly without further detail. The current detection circuit 6 includes resistors R1 to R7 and an operational amplifier AMP. The current flowing through the motor 3 (herein referred to as "motor current") is converted into a voltage by passing it through resistor R1, which serves as a shunt resistor. Resistors R2 to R7 and the operational amplifier AMP form an offset-compensated negative feedback non-inverting amplifier circuit, with resistors R5 and R6 providing negative feedback and resistors R2 to R3 compensating for the offset voltage generated between the non-inverting and inverting input terminals of the operational amplifier AMP. Resistors R4 and R5 are connected to the non-inverting and inverting terminals of the operational amplifier AMP, respectively, and resistor R7 is connected to the output terminal of the operational amplifier AMP. The voltage converted by passing the motor current through the shunt resistor R1 is amplified by the operational amplifier AMP and resistors R5 and R6, and the amplified voltage is output from terminal T. The analog voltage value amplified by the current detection circuit 6 is converted into a digital voltage value by the CPU 4C and corrected.

[0006] First, the preparations for correcting the voltage (hereinafter referred to as "AD voltage") converted from analog to digital by the CPU 4C will be described with reference to Fig. 8. In Fig. 8(a) and Fig. 8(b), the horizontal axis represents the motor current [A] and the vertical axis represents the AD voltage [V], and Fig. 8(a) and Fig. 8(b) show the relationship between the motor current [A] and the AD voltage [V] (hereinafter referred to as "motor current-AD voltage characteristic").

[0007] In Figure 8(a), the solid line shows the ideal motor current-AD voltage characteristic (hereinafter referred to as the "ideal motor current-AD voltage characteristic"; in Figures 8(a) and 8(b) this is simply referred to as the "ideal characteristic"), where the motor current [A] and AD voltage [V] are proportional, and the dotted line shows the motor current-AD voltage characteristic (hereinafter referred to as the "actual motor current-AD voltage characteristic"; in Figures 8(a) and 8(b) this is simply referred to as the "actual characteristic"), which shows the relationship between the current (motor current) [A] passed through the actual motor 3 and the AD voltage [V] based on the detection results by the actual current detection circuit 6.

[0008] At a current point where the motor current is 0 [A], the AD voltage value of the actual motor current-AD voltage characteristic is corrected to match the AD voltage value of the ideal motor current-AD voltage characteristic (correction of the offset amount when power is off). The offset amount is a value obtained by subtracting the AD voltage value of the ideal motor current-AD voltage characteristic from the AD voltage value of the actual motor current-AD voltage characteristic at a current point where the motor current is 0 [A], and is stored in memory 5C constructed using an EEPROM or the like. In addition, the amount of change in the offset amount related to the drift of the current detection circuit 6 (hereinafter referred to as the "temperature drift amount") is stored in memory 5C for each temperature (thermistor temperature) of the EPS-ECU 2C. The offset amount and temperature drift amount are stored in memory 5C, for example, during shipping inspection of the EPS-ECU 2C.

[0009] In FIG. 8(b), the motor current-AD voltage characteristics obtained by subtracting the offset amount from each current value of the actual motor current-AD voltage characteristics (hereinafter referred to as "motor current-AD voltage characteristics after first correction"; in FIG. 8(b) it is simply referred to as "characteristics after first correction") are shown by a dashed dotted line.

[0010] At a current point where the motor current is at the rated current value, a correction is performed to match the AD voltage value of the motor current-AD voltage characteristic after the first correction to the AD voltage value of the ideal motor current-AD voltage characteristic. This correction is performed by multiplying the AD voltage value of the motor current-AD voltage characteristic after the first correction at the current point by the value of a correction gain to match the AD voltage value of the ideal motor current-AD voltage characteristic, and the correction gain value is stored in memory 5C. Here, the correction amount corrected using the correction gain value at the current point is the correction amount obtained by subtracting the AD voltage value of the ideal motor current-AD voltage characteristic from the AD voltage value of the motor current-AD voltage characteristic after the first correction. The correction gain value is stored in memory 5C, for example, during shipping inspection of EPS-ECU 2C.

[0011] Next, the process of correcting the AD voltage AD will be described with reference to FIG.

[0012] The CPU 4C performs a first correction process. In the first correction process, the CPU 4C calculates a drift-correction offset amount Offset_Drift by adding the offset amount Offset stored in the memory 5C and a temperature drift amount Drift corresponding to the thermistor temperature in an adder 11 (Offset_Drift=Offset+Drift). The CPU 4C calculates an offset-correction AD voltage AD_Sub by subtracting the drift-correction offset amount Offset_Drift from the AD voltage AD in a subtracter 12 (AD_Sub=AD-Offset_Drift=AD-(Offset+Drift)).

[0013] The CPU 4C performs a second correction process. In the second correction process, the CPU 4C calculates a corrected AD voltage AD_COR_C by multiplying the offset-corrected AD voltage AD_Sub by the correction gain G stored in the memory 5C in the multiplication unit 13 (AD_COR_C=G×AD_Sub=G×(AD−(Offset+Drift)). Then, the CPU 4C calculates the current value of the motor current actually flowing through the motor 3 based on the voltage value of the corrected AD voltage AD_COR_C.

[0014] The current value of the motor current that determines the motor assist in the EPS system 1 affects the steering force of the user's handlebars while driving, so high accuracy in detecting the current is required. Conventionally, errors in the current value of the motor current have been eliminated by performing the first and second corrections described with reference to Figures 6 to 9.

[0015] However, in the second correction, a correction gain is used to match the AD voltage value of the motor current-AD voltage characteristic after the first correction with the AD voltage value of the ideal motor current-AD voltage characteristic at the current point where the motor current is the rated current value, which makes it easy for errors to occur in other current value ranges, leading to a deterioration in the continuity of the user steering force.For example, in the IPA (Intelligent Parking Assist) specification, the maximum normal current value is set to, for example, 45 [A] for a rated current value of 50 [A], so the second correction using a correction gain obtained at the current point where the rated current value is 50 [A] makes it easy for errors to occur in the current range of current values ​​used under normal conditions.

[0016] An object of the present invention is to provide a vehicle control device that can improve the accuracy of detecting the current value of the current actually flowing through the motor over a wide current range. [Means for solving the problem]

[0017] In order to achieve the above object, the present invention provides a vehicle control device having an assist function using a motor mounted on a vehicle, and converting a current value actually flowing through the motor into a voltage value and detecting the voltage value. With an op-amp The present invention includes a current detection unit and a correction unit that performs a correction process to correct a voltage value detected by the current detection unit, and the correction unit The second correction process is performed after the first correction process, and the first correction process is a correction that derives an offset amount that matches the voltage value measured by the current detection means when no current is applied in the actual motor current-voltage characteristic of an actual motor current applied to the motor, with the voltage value measured by the current detection means when no current is applied in the ideal motor current-voltage characteristic in which current and voltage are proportional, and subtracts from the voltage value a correction amount that takes into account a temperature drift amount calculated in advance for each of a plurality of different temperatures of the current detection means to the offset amount; and the second correction process is a correction that subtracts from the voltage value a correction amount that takes into account a rated current value of the motor, and At each of a plurality of current values ​​including The above Voltage value and , in the ideal motor current-voltage characteristic The current value The above Correction coefficients corresponding to each of the current values ​​based on the voltage values is derived in advance, and the voltage value after the first correction process is multiplied by the correction coefficient corresponding to the current value to make it coincide with the voltage value in the ideal motor current-voltage characteristics. It is characterized by the following.

[0018] According to this configuration, by performing correction processing based on a correction coefficient for each of a plurality of current values ​​including a predetermined current value, it is possible to improve the detection accuracy of the current value of the current actually flowing through the motor over a wide current range.

[0019] The correction means calculates the current value based on the correction coefficient at each of the plurality of temperatures of the vehicle control device. First and second Correction processing may be performed.

[0020] This configuration enables appropriate correction processing according to the temperature of the vehicle control device, thereby improving the accuracy of detecting the current value of the current actually flowing through the motor even if the temperature of the vehicle control device changes.

[0021] The correction means calculates the temperature by using a map created based on the correction coefficient at each of the plurality of temperatures and the plurality of current values. First and second Correction processing may be performed.

[0022] According to this configuration, an appropriate correction coefficient can be used in the correction process by the correction means. [Effects of the Invention]

[0023] According to the present invention, by performing correction processing based on a correction coefficient for each of a plurality of current values ​​including a predetermined current value, it is possible to improve the detection accuracy of the current value of the current actually flowing through the motor over a wide current range. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a system configuration diagram showing the configuration of an EPS (electric power steering) system according to one embodiment of the present invention. [Figure 2] 2 is an explanatory diagram for explaining correction of an AD voltage by a CPU in FIG. 1. FIG. [Figure 3] 2 is an explanatory diagram for explaining correction of an AD voltage by a CPU in FIG. 1. FIG. [Figure 4] 2 is an explanatory diagram for explaining a correction process of an AD voltage by a CPU in FIG. 1. FIG. [Figure 5] 1. FIG. 4 is an explanatory diagram for explaining a calculation process of a post-calculation correction gain performed by a calculation unit of a CPU in FIG. [Figure 6]FIG. 1 is a system configuration diagram showing the configuration of a conventional EPS (electric power steering) system. [Figure 7] FIG. 7 is a circuit diagram showing the configuration of the current detection circuit of FIG. 6. [Figure 8] 7 is an explanatory diagram for explaining correction of an AD voltage by a CPU in FIG. 6. FIG. [Figure 9] 7 is an explanatory diagram for explaining the correction process of the AD voltage by the CPU of FIG. 6. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0026] The configuration of an EPS (electric power steering) system 1 according to one embodiment of the present invention will be described with reference to FIG.

[0027] The EPS system 1 of this embodiment differs from the conventional EPS system 1C described with reference to Figures 6 to 9 in that the CPU 4 of the EPS-ECU 2 corrects the AD voltage AD using the contents stored in memory 5, whereas the CPU 4C of the EPS-ECU 2C corrects the AD voltage AD using the contents stored in memory 5C. Otherwise, the EPS system 1 is similar to the conventional EPS system 1C, and the same components are designated by the same reference numerals and will not be described again. The EPS-ECU 2 corresponds to the "vehicle control device" of the present invention. The current detection circuit 6 of Figure 1, which has the circuit configuration shown in Figure 7, corresponds to the "current detection means" of the present invention.

[0028] First, the preparations for correcting the digital voltage value (AD voltage value) into which the CPU 4 converts the analog voltage value detected by the current detection circuit 6 will be described with reference to Figures 2 and 3. In Figures 2(a), (b) and 3, the horizontal axis represents the motor current [A] and the vertical axis represents the AD voltage [V], and Figures 2(a), (b) and 3 show the relationship between the motor current [A] and the AD voltage [V] (motor current-AD voltage characteristic).

[0029] In Figure 2(a), the solid line shows the ideal motor current-AD voltage characteristic (ideal motor current-AD voltage characteristic: abbreviated as "ideal characteristic" in Figures 2(a), (b), and 3), in which the motor current [A] and AD voltage [V] are proportional, and the dotted line shows the motor current-AD voltage characteristic (actual motor current-AD voltage characteristic: abbreviated as "actual characteristic" in Figures 2(a), (b), and 3), which shows the relationship between the current (motor current) [A] passed through the actual motor 3 and the AD voltage [V] based on the detection results by the actual current detection circuit 6.

[0030] At a predetermined temperature of the EPS-ECU 2 (hereinafter referred to as the "thermistor reference temperature"), the AD voltage value of the actual motor current-AD voltage characteristic is corrected to match the AD voltage value of the ideal motor current-AD voltage characteristic at a current point where the motor current is 0 [A] (correction of the offset amount when power is off). The offset amount is a value obtained by subtracting the AD voltage value of the ideal motor current-AD voltage characteristic from the AD voltage value of the actual motor current-AD voltage characteristic at a current point where the motor current is 0 [A], and is stored in a memory 5 constructed using an EEPROM or the like. In addition, a temperature drift amount map showing the correspondence between the thermistor temperature for each of multiple temperatures (thermistor temperatures) of the EPS-ECU 2 and the fluctuation amount of the offset amount related to the drift of the current detection circuit 6 at that thermistor temperature is created and stored in the memory 5. The temperature drift amount at each thermistor temperature is calculated by subtracting the offset amount at the reference thermistor temperature from the offset amount at that thermistor temperature. The offset amount and the temperature drift amount map are stored in the memory 5, for example, during a shipping inspection of the EPS-ECU 2.

[0031] In Figures 2(b) and 3, the motor current-AD voltage characteristics obtained by subtracting the offset amount from each current value of the actual motor current-AD voltage characteristics are shown by dashed dotted lines (motor current-AD voltage characteristics after first correction: in Figures 2(b) and 3, these are simply referred to as "characteristics after first correction").

[0032] 3, at a first current point where the motor current is the rated current value, a second current point where the motor current is a current value smaller than the rated current value and greater than 0 [A], and a third current point where the motor current is a current value smaller than the second current point and greater than 0 [A], a correction is made to match the AD voltage values ​​of the motor current-AD voltage characteristics after the first correction to the AD voltage values ​​of the ideal motor current-AD voltage characteristics. The correction at each of the first current point, second current point, and third current point is made by multiplying the AD voltage values ​​of the motor current-AD voltage characteristics after the first correction at the current point by the value of the correction gain to match the AD voltage values ​​of the ideal motor current-AD voltage characteristics. Here, the correction amounts corrected by the correction gain values ​​at the current points (first current point, second current point, third current point) are correction amounts (first correction amount, second correction amount, third correction amount) obtained by subtracting the AD voltage value of the ideal motor current-AD voltage characteristics from the AD voltage value of the first corrected motor current-AD voltage characteristics. Based on the current command values ​​(current values ​​at the current points) [A] and the correction gains [-(unitless)] for the first current point, second current point, and third current point, a correction gain map showing the correspondence between them is created and stored in memory 5. The correction gains correspond to the "correction coefficients" of the present invention.

[0033] In this embodiment, the memory 5 stores three correction gain maps: a correction gain map created using the ideal motor current-AD voltage characteristics and the motor current-AD voltage characteristics after first correction when the thermistor temperature is −30 degrees (hereinafter referred to as the “−30 degree correction gain map”), a correction gain map created using the ideal motor current-AD voltage characteristics and the motor current-AD voltage characteristics after first correction when the thermistor temperature is 25 degrees (hereinafter referred to as the “25 degree correction gain map”), and a correction gain map created using the ideal motor current-AD voltage characteristics and the motor current-AD voltage characteristics after first correction when the thermistor temperature is 65 degrees (hereinafter referred to as the “65 degree correction gain map”). The −30 degree correction gain map, the 25 degree correction gain map, and the 65 degree correction gain map are stored in the memory 5, for example, during a shipping inspection of the EPS-ECU 2.

[0034] Next, the processing contents of the correction of the AD voltage AD will be described with reference to Fig. 4. The part of the CPU 4 that performs the processing of the correction contents described with reference to Figs. 4 and 5 corresponds to the "correction means" of the present invention.

[0035] The CPU 4 performs a first correction process. In the first correction process, the CPU 4 acquires a temperature drift amount Drift corresponding to the thermistor temperature by referring to a temperature drift map stored in the memory 5. In the temperature drift map of FIG. 4, the thermistor temperature is simplified as "temperature" and the temperature drift amount is simplified as "drift."

[0036] The CPU 4 calculates the drift correction offset amount Offset_Drift by adding the offset amount Offset stored in the memory 5 and the temperature drift amount Drift corresponding to the thermistor temperature in the adder 11 (Offset_Drift=Offset+Drift).

[0037] In the subtraction unit 12, the CPU 4 subtracts the drift correction offset amount Offset_Drift from the AD voltage AD (the analog voltage obtained by the current detection circuit 6 converted into a digital voltage by the CPU 4) to calculate the offset correction AD voltage AD_Sub (AD_Sub=AD-Offset_Drift=AD-(Offset+Drift)).

[0038] The CPU 4 performs a second correction process. In the second correction process, the CPU 4 calculates a current command value by performing feedback control based on, for example, steering force, total steering angle, vehicle speed information, and the like, and further based on the difference between the current command value and the current value of the current actually flowing through the motor 3, which is calculated based on the detection result of the current detection circuit 6. The CPU 4 references a -30-degree correction gain map stored in the memory 5 to acquire a correction gain (hereinafter referred to as "-30-degree correction gain") GAIN_m30 corresponding to the calculated current command value [A], references a 25-degree correction gain map to acquire a correction gain (hereinafter referred to as "25-degree correction gain") GAIN_25 corresponding to the calculated current command value [A], and references a 65-degree correction gain map to acquire a correction gain (hereinafter referred to as "65-degree correction gain") GAIN_65 corresponding to the calculated current command value (A). For example, interpolation or extrapolation is performed to obtain the correction gains (-30 degree correction gain, 25 degree correction gain, 65 degree correction gain) using the correction gain maps (-30 degree correction gain map, 25 degree correction gain map, 65 degree correction gain map).

[0039] Next, the CPU 4 calculates the post-calculation correction gain GAIN_CAL in the calculation unit 20. The calculation process of the post-calculation correction gain GAIN_CAL performed in the calculation unit 20 of the CPU 4 will be described with reference to FIG.

[0040] The post-calculation correction gain GAIN_CAL is calculated according to the temperature (thermistor temperature) Temp of the EPS-ECU measured by the thermistor. In this embodiment, the calculation is performed for the following cases: (A) when the thermistor temperature is less than -30°C, (B) when the thermistor temperature is -30°C or more and less than 25°C, (C) when the thermistor temperature is 25°C or more and less than 65°C, and (D) when the thermistor temperature is 65°C or more.

[0041] (A) When the thermistor temperature is below -30°C When the thermistor temperature Temp is less than −30 degrees, the −30 degree correction gain GAIN_m30 is set as the post-calculation correction gain GAIN_CAL (GAIN_CAL=GAIN_m30).

[0042] (B) When the thermistor temperature is between -30°C and 25°C When the thermistor temperature Temp is equal to or greater than -30 degrees and less than 25 degrees, first, the calculation parameters (first correction gain GAIN_MAP1, second correction gain GAIN_MAP2, temperature difference Temp_DIF, reference temperature Temp_REF) are set. In this embodiment, the first correction gain GAIN_MAP1 is set to a -30 correction gain GAIN_m30 (GAIN_MAP1=GAIN_m30), and the second correction gain GAIN_MAP2 is set to a 25 correction gain GAIN_25 (GAIN_MAP2=GAIN_25). Furthermore, the temperature difference Temp_DIF is set to 55 degrees (Temp_DIF=55), and the reference temperature Temp_REF is set to 25 degrees (Temp_REF=25).

[0043] Next, the post-calculation correction gain GAIN_CAL is calculated using the set calculation parameters. Note that this calculation uses a technique called linear interpolation, but is not limited to this.

[0044] Specifically, in the calculation unit 20, a subtraction unit 21 subtracts the first correction gain GAIN_MAP1 from the second correction gain GAIN_MAP2 to calculate the correction gain difference GAIN_DIF (GAIN_DIF=GAIN_MAP2-GAIN_MAP1=GAIN_25-GAIN_m30). In the calculation unit 20, a division unit 22 divides the correction gain difference GAIN_DIF by the temperature difference Temp_DIF to calculate the correction gain slope GAIN_TILT (GAIN_TILT=GAIN_DIF / Temp_DIF=(GAIN_MAP2-GAIN_MAP1) / Temp_DIF=(GAIN_25-GAIN_m30) / 55).

[0045] The calculation unit 20 calculates the temperature width Temp_WID in the subtraction unit 23 by subtracting the reference temperature Temp_REF from the thermistor temperature Temp (Temp_WID=Temp-Temp_REF=Temp-25).

[0046] The calculation unit 20 multiplies the temperature range Temp_WID by the correction gain tilt GAIN_TILT in the multiplication unit 24 to calculate the correction gain range GAIN_WID (GAIN_WID=GAIN_TILT×Temp_WID=((GAIN_25−GAIN_m30) / 55)×(Temp−25)).

[0047] The calculation unit 20 calculates the post-calculation correction gain GAIN_CAL in the adder 25 by adding the second correction gain GAIN_MAP2 and the correction gain width GAIN_WID (GAIN_CAL=GAIN_MAP2+GAIN_WID=GAIN_25+((GAIN_25-GAIN_m30) / 55)×(Temp-25)).

[0048] (C) When the thermistor temperature is between 25°C and 65°C When the thermistor temperature Temp is equal to or greater than 25 degrees and less than 65 degrees, first, the calculation parameters (first correction gain GAIN_MAP1, second correction gain GAIN_MAP2, temperature difference Temp_DIF, reference temperature Temp_REF) are set. In this embodiment, the first correction gain GAIN_MAP1 is set to a 25 correction gain GAIN_25 (GAIN_MAP1=GAIN_25), and the second correction gain GAIN_MAP2 is set to a 65 correction gain GAIN_65 (GAIN_MAP2=GAIN_65). In addition, the temperature difference Temp_DIF is set to 40 degrees (Temp_DIF=40), and the reference temperature Temp_REF is set to 65 degrees (Temp_REF=65).

[0049] Next, the post-calculation correction gain GAIN_CAL is calculated using the set calculation parameters. Note that this calculation uses a technique called linear interpolation, but is not limited to this.

[0050] Specifically, in the calculation unit 20, a subtraction unit 21 subtracts the first correction gain GAIN_MAP1 from the second correction gain GAIN_MAP2 to calculate the correction gain difference GAIN_DIF (GAIN_DIF=GAIN_MAP2-GAIN_MAP1=GAIN_65-GAIN_25). In the calculation unit 20, a division unit 22 divides the correction gain difference GAIN_DIF by the temperature difference Temp_DIF to calculate the correction gain slope GAIN_TILT (GAIN_TILT=GAIN_DIF / Temp_DIF=(GAIN_MAP2-GAIN_MAP1) / Temp_DIF=(GAIN_65-GAIN_25) / 40).

[0051] The calculation unit 20 calculates the temperature width Temp_WID in the subtraction unit 23 by subtracting the reference temperature Temp_REF from the thermistor temperature Temp (Temp_WID=Temp-Temp_REF=Temp-65).

[0052] The calculation unit 20 multiplies the temperature range Temp_WID by the correction gain tilt GAIN_TILT in the multiplication unit 24 to calculate the correction gain range GAIN_WID (GAIN_WID=GAIN_TILT×Temp_WID=((GAIN_65−GAIN_25) / 40)×(Temp−65)).

[0053] The calculation unit 20 calculates the post-calculation correction gain GAIN_CAL in the adder 25 by adding the second correction gain GAIN_MAP2 and the correction gain width GAIN_WID (GAIN_CAL=GAIN_MAP2+GAIN_WID=GAIN_65+((GAIN_65-GAIN_25) / 40)×(Temp-65)).

[0054] (D) When the thermistor temperature is 65 degrees or higher When the thermistor temperature Temp is less than 65 degrees, the 65-degree correction gain GAIN_65 is set as the post-calculation correction gain GAIN_CAL (GAIN_CAL=GAIN_65).

[0055] After one of the above processes (A) to (D) is performed in accordance with the thermistor temperature Temp, the CPU 4 calculates the corrected AD voltage AD_COR by multiplying the offset-corrected AD voltage AD_Sub by the calculated correction gain GAIN_CAL in the multiplication unit 30 (AD_COR=GAIN_CAL×AD_Sub) as shown in Fig. 4. Then, the CPU 4 stores in advance in the memory 5, for example, a correspondence relationship between the voltage value of the corrected AD voltage AD_COR and the motor current actually flowing through the motor 3, and calculates the current value of the motor current actually flowing through the motor 3 based on the voltage value of the corrected AD voltage AD_COR.

[0056] According to the above-described embodiment, by performing correction processing based on correction gain maps (-30 degree correction gain map, 25 degree correction gain map, 65 degree correction gain map) created based on the correction gains at the first current point (current point at the rated current value), the second current point, and the third current point, the detection accuracy of the current value actually flowing through the motor 3 can be improved over a wide current range.

[0057] In addition, by using a -30 degree correction gain map when the thermistor temperature is -30 degrees, a 25 degree correction gain map when the thermistor temperature is 25 degrees, and a 65 degree correction gain map when the thermistor temperature is 65 degrees as correction gain maps, appropriate correction processing according to the temperature (thermistor temperature) of EPS-ECU2 becomes possible, and the detection accuracy of the current value actually flowing through motor 3 can be improved even if the temperature (thermistor temperature) of EPS-ECU2 changes.

[0058] Furthermore, by using the correction gain maps (-30 degree correction gain map, 25 degree correction gain map, 65 degree correction gain map), the correction process can be performed using a correction gain that is suitable for the correction process.

[0059] In addition, various design modifications can be made to the above-described configuration within the scope of the claims.

[0060] For example, in the above embodiment, correction gains at three current points, namely, the first current point, the second current point, and the third current point, are set in advance and used, but this is not limited to this, and correction gains at two current points (e.g., two current points including the current point at the rated current value) may be used, or correction gains at four or more current points (e.g., four or more current points including the current point at the rated current value) may be used.

[0061] In addition, in the above embodiment, correction gain maps corresponding to thermistor temperatures of -25 degrees, 30 degrees, and 65 degrees are set in advance and used, but this is not limited to this, and correction gain maps corresponding to two temperatures each may be used, or correction gain maps corresponding to four or more temperatures each may be used.

[0062] Furthermore, the contents described in the above embodiment and the contents described in the above modified examples may be combined as appropriate.

[0063] The present invention is widely applicable to vehicle control devices having an assist function using a motor mounted on the vehicle. [Explanation of symbols]

[0064] 1: EPS (electric power steering) system 2: EPS-ECU 3: EPS-ECU 4: CPU 5: Memory 6: Current detection circuit 11: Addition section 12: Subtraction section 20: Arithmetic section 21: Subtraction section 22: Division part 23: Subtraction section 24: Multiplication section 25: Addition section 30: Multiplication section

Claims

1. A vehicle control device having an assist function using a motor mounted on a vehicle, a current detection means including an operational amplifier for converting the value of the current actually flowing through the motor into a voltage value and detecting the voltage value; a correction means for performing a correction process to correct the voltage value detected by the current detection means; Equipped with the correction means performs a first correction process as the correction process and then a second correction process, The first correction process includes: a current-voltage characteristic that is the relationship between the motor current flowing through the motor and the voltage value converted from the motor current by the current detection means, the voltage value being an ideal motor current-voltage characteristic in which current and voltage are proportional to each other, and an offset amount that matches the voltage value being measured by the current detection means when no current is being applied in the actual motor current-voltage characteristic that is measured when no current is being applied to the motor; and a correction amount that takes into account temperature drift amounts calculated in advance for a plurality of different temperatures of the current detection means and adds to the offset amount, and then subtracts the resulting correction amount from the voltage value; The second correction process includes: A correction coefficient corresponding to each current value is derived in advance based on the voltage value detected by the current detection means corresponding to each current value, including the rated current value of the motor, and the voltage value at that current value in the ideal motor current-voltage characteristic, and the voltage value after the first correction process is multiplied by the correction coefficient corresponding to that current value to make it match the voltage value in the ideal motor current-voltage characteristic. A vehicle control device comprising:

2. 2. The vehicle control device according to claim 1, wherein the correction means performs the first and second correction processes based on the correction coefficients for each of the plurality of current values ​​at each of a plurality of temperatures of the vehicle control device.

3. 3. The vehicle control device according to claim 2, wherein the correction means performs the first and second correction processes using a map created based on the correction coefficients at each of the plurality of current values ​​at each of the plurality of temperatures.

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