JP7802587B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device that has an assist function using a motor installed in the vehicle.

Conventionally, there have been vehicle control devices that reduce the discrepancy between a motor's target torque (current command value) and its actual torque (actual current) (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2021-27627

In the mounted EPS (electric power steering) system 1C shown in Figure 6, the CPU 4C of the 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 steering force, total steering angle, vehicle speed information, etc., and also performs feedback control based on the difference between the current command value and the current value actually flowing through the motor 3, which is calculated based on the detection results of the current detection circuit 6.

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-R7 and an operational amplifier AMP. The current flowing through the motor 3 (referred to here as "motor current") is converted into a voltage by passing it through shunt resistor R1. Resistors R2-R7 and the operational amplifier AMP form an offset-compensated negative feedback non-inverting amplifier circuit, with negative feedback provided by resistors R5 and R6, and resistors R2-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 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 to a digital voltage value by the CPU 4C and corrected.

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

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

At the 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 (offset correction when de-energized). The offset amount is calculated 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 the current point where the motor current is 0 [A], and is stored in memory 5C constructed from an EEPROM or the like. Furthermore, the amount of change in the offset amount related to the drift of the current detection circuit 6 (hereinafter referred to as "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.

In Figure 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 the "motor current-AD voltage characteristics after first correction"; in Figure 8(b), this is abbreviated to "characteristics after first correction") are shown by a dashed dotted line.

At a current point where the motor current is at the rated current value, a correction is made to match the AD voltage value of the first-corrected motor current-AD voltage characteristic to the AD voltage value of the ideal motor current-AD voltage characteristic. This correction is made by multiplying the AD voltage value of the first-corrected motor current-AD voltage characteristic at the current point by the correction gain value 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 first-corrected motor current-AD voltage characteristic. The correction gain value is stored in memory 5C, for example, during shipping inspection of the EPS-ECU 2C.

Next, the process for correcting the AD voltage AD will be explained with reference to Figure 9.

The CPU 4C performs a first correction process. In the first correction process, the CPU 4C adds the offset amount Offset stored in memory 5C and the temperature drift amount Drift corresponding to the thermistor temperature in the adder 11 to calculate the drift-correction offset amount Offset_Drift (Offset_Drift = Offset + Drift). The CPU 4C subtracts the drift-correction offset amount Offset_Drift from the AD voltage AD in the subtracter 12 to calculate the offset-correction AD voltage AD_Sub (AD_Sub = AD - Offset_Drift = AD - (Offset + Drift)).

The CPU 4C performs a second correction process. In the second correction process, the CPU 4C uses the multiplication unit 13 to multiply the offset-corrected AD voltage AD_Sub by the correction gain G stored in memory 5C to calculate the corrected AD voltage AD_COR_C (AD_COR_C = G x AD_Sub = G x (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.

The motor current value 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 motor current value have been eliminated by performing the first and second corrections described with reference to Figures 6 to 9.

However, the second correction described above uses a correction gain that matches 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 at the rated current value. This 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]. Therefore, when using the second correction that uses the correction gain obtained at the current point where the rated current value is 50 [A], errors are likely to occur in the current range of current values used under normal circumstances.

The object of the present invention is to provide a vehicle control device that can increase the accuracy of detecting the current value actually flowing through the motor over a wide current range.

In order to achieve the above object, a vehicle control device according to the present invention is a vehicle control device having an assist function using a motor mounted on a vehicle, and comprises: current detection means having an operational amplifier that converts a value of a current actually flowing through the motor into a voltage value and detects it; and correction means that performs correction processing to correct the voltage value detected by the current detection means, the correction means performs a first correction processing and then a second correction processing, and the first correction processing is a current-voltage characteristic that is a relationship between a motor current flowing through the motor and a voltage value converted from the motor current by the current detection means, and the voltage value detected by the current detection means when current is not being applied in an ideal motor current-voltage characteristic in which current and voltage are proportional to each other is compared to the voltage value detected by the current detection means when current is not being applied. The second correction process is a correction in which an offset amount is derived to match the voltage value measured by the current detection means when no current is applied in the motor current-voltage characteristic, and a correction amount obtained by adding a temperature drift amount derived in advance for each of a plurality of different temperatures of the current detection means to the offset amount is subtracted from the voltage value; the second correction process is a correction in which a correction coefficient corresponding to each current value is derived in advance based on the voltage value measured by the current detection means corresponding to each current value at each of a plurality of current values 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 match the voltage value in the ideal motor current-voltage characteristic .

With this configuration, correction processing is performed based on a correction coefficient for each of multiple current values, including a predetermined current value, thereby improving the accuracy of detecting the current value actually flowing through the motor over a wide current range.

The correction means may perform 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.

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

The correction means may perform the first and second correction processes using a map created based on the correction coefficient at each of the plurality of temperatures and each of the plurality of current values.

This configuration allows the correction means to use appropriate correction coefficients in the correction process.

According to the present invention, by performing correction processing based on correction coefficients for each of multiple current values, including a predetermined current value, it is possible to improve the detection accuracy of the current value actually flowing through the motor over a wide current range.

1 is a system configuration diagram showing the configuration of an EPS (electric power steering) system according to an embodiment of the present invention. 2 is an explanatory diagram for explaining correction of an AD voltage by a CPU in FIG. 1; FIG. 2 is an explanatory diagram for explaining correction of an AD voltage by a CPU in FIG. 1; FIG. 2 is an explanatory diagram for explaining a correction process of an AD voltage by a CPU in FIG. 1; FIG. 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. FIG. 1 is a system configuration diagram showing the configuration of a conventional EPS (electric power steering) system. FIG. 7 is a circuit diagram showing the configuration of the current detection circuit of FIG. 6 . FIG. 7 is an explanatory diagram for explaining correction of an AD voltage by the CPU of FIG. 6 . 7 is an explanatory diagram for explaining a correction process of an AD voltage by the CPU of FIG. 6. FIG.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

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

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 mechanism by which the CPU 4 of the EPS-ECU 2 corrects the AD voltage AD using the stored contents of memory 5 is different from the mechanism by which the CPU 4C of the EPS-ECU 2C corrects the AD voltage AD using the stored contents of memory 5C. In all other respects, the EPS system 1 is similar to the conventional EPS system 1C, and the same components are designated by the same reference numerals and their description will be omitted. The EPS-ECU 2 corresponds to the "vehicle control device" of the present invention. Furthermore, 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.

First, we will explain the preparations made by the CPU 4 to correct the digital voltage value (the voltage value of the AD voltage AD) obtained by converting the analog voltage value detected by the current detection circuit 6, 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]. Figures 2(a), (b), and 3 show the relationship between the motor current [A] and the AD voltage [V] (motor current-AD voltage characteristic).

Figure 2(a) shows, using a solid line, the ideal motor current-AD voltage characteristic (ideal motor current-AD voltage characteristic: abbreviated as "ideal characteristic" in Figures 2(a), (b), and 3), where the motor current [A] and AD voltage [V] are proportional, and, using a dotted line, 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 from the actual current detection circuit 6.

At a specified temperature (hereinafter referred to as the "thermistor reference temperature") of the EPS-ECU 2, 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 the current point where the motor current is 0 [A] (correction of the offset amount when power is off). The offset amount is the 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 the current point where the motor current is 0 [A], and is stored in memory 5 constructed from 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 memory 5. However, the temperature drift amount at each thermistor temperature is the offset amount at that thermistor temperature minus the offset amount at the thermistor reference temperature. The offset amount and temperature drift amount map are stored in memory 5, for example, during shipping inspection of the EPS-ECU 2.

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: simply referred to as "characteristics after first correction" in Figures 2(b) and 3).

In Figure 3, at each of the first current point where the motor current is the rated current value, the second current point where the motor current is a current value less than the rated current value and greater than 0 [A], and the third current point where the motor current is a current value less than the second current point and greater than 0 [A], a correction is made 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. The correction for each of the first current point, second current point, and third current point is a correction in which the AD voltage value of the motor current-AD voltage characteristic after the first correction at the current point is multiplied by the correction gain value to match the AD voltage value of the ideal motor current-AD voltage characteristic. Here, the correction amount corrected by the correction gain value at the current points (first current point, second current point, third current point) is the correction amount (first correction amount, second correction amount, third correction amount) obtained by subtracting the voltage value of the AD voltage of the ideal motor current-AD voltage characteristic from the voltage value of the AD voltage of the first corrected motor current-AD voltage characteristic. A correction gain map showing the correspondence between the current command value (current value at the current point) [A] and the correction gain [- (unitless)] for each of the first current point, second current point, and third current point is created and stored in memory 5. The correction gain corresponds to the "correction coefficient" in this invention.

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 the 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 the 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 the 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 shipping inspection of the EPS-ECU 2.

Next, the process for correcting the AD voltage AD will be described with reference to Figure 4. Note that the part of CPU 4 that processes the correction details described with reference to Figures 4 and 5 corresponds to the "correction means" of the present invention.

The CPU 4 performs a first correction process. In the first correction process, the CPU 4 references the temperature drift map stored in the memory 5 to obtain the temperature drift amount Drift corresponding to the thermistor temperature. Note that in the temperature drift map in Figure 4, the thermistor temperature is simplified to "temperature" and the temperature drift amount is simplified to "drift."

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

The CPU 4 calculates the offset-corrected AD voltage AD_Sub by subtracting the drift correction offset amount Offset_Drift from the AD voltage AD (the analog voltage obtained by the current detection circuit 6 converted to a digital voltage by the CPU 4) in the subtraction unit 12 (AD_Sub = AD - Offset_Drift = AD - (Offset + Drift)).

The CPU 4 performs a second correction process. In the second correction process, the CPU 4 calculates a current command value based on, for example, steering force, total steering angle, vehicle speed information, etc., and further performs feedback control 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 results of the current detection circuit 6. The CPU 4 references the -30-degree correction gain map stored in the memory 5 to obtain a correction gain (hereinafter referred to as the "-30-degree correction gain") GAIN_m30 corresponding to the calculated current command value [A], references the 25-degree correction gain map to obtain a correction gain (hereinafter referred to as the "25-degree correction gain") GAIN_25 corresponding to the calculated current command value [A], and references the 65-degree correction gain map to obtain a correction gain (hereinafter referred to as the "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).

Next, the CPU 4 calculates the post-calculation correction gain GAIN_CAL in the calculation unit 20. The calculation process for the post-calculation correction gain GAIN_CAL performed in the calculation unit 20 of the CPU 4 will be described with reference to Figure 5.

The calculation of the post-calculation correction gain GAIN_CAL is performed according to the EPS-ECU temperature (thermistor temperature) Temp measured by the thermistor. In this embodiment, the process is divided into three cases: (A) when the thermistor temperature is less than -30 degrees, (B) when the thermistor temperature is -30 degrees or more but less than 25 degrees, (C) when the thermistor temperature is 25 degrees or more but less than 65 degrees, and (D) when the thermistor temperature is 65 degrees or more.

(A) When the thermistor temperature is less than −30 degrees Celsius When the thermistor temperature Temp is less than −30 degrees Celsius, the −30 degree correction gain GAIN_m30 is set as the post-calculation correction gain GAIN_CAL (GAIN_CAL=GAIN_m30).

(B) When the thermistor temperature is -30 degrees or more and less than 25 degrees When the thermistor temperature Temp is -30 degrees or more 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).

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

Specifically, the calculation unit 20 calculates the correction gain difference GAIN_DIF by subtracting the first correction gain GAIN_MAP1 from the second correction gain GAIN_MAP2 in the subtraction unit 21 (GAIN_DIF = GAIN_MAP2 - GAIN_MAP1 = GAIN_25 - GAIN_m30). The calculation unit 20 calculates the correction gain slope GAIN_TILT by dividing the correction gain difference GAIN_DIF by the temperature difference Temp_DIF in the division unit 22 (GAIN_TILT = GAIN_DIF / Temp_DIF = (GAIN_MAP2 - GAIN_MAP1) / Temp_DIF = (GAIN_25 - GAIN_m30) / 55).

The calculation unit 20 calculates the temperature range 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).

The calculation unit 20 calculates the correction gain width GAIN_WID by multiplying the temperature width Temp_WID by the correction gain slope GAIN_TILT in the multiplication unit 24 (GAIN_WID = GAIN_TILT × Temp_WID = ((GAIN_25 - GAIN_m30) / 55) × (Temp - 25)).

The calculation unit 20 calculates the calculated correction gain GAIN_CAL by adding the second correction gain GAIN_MAP2 and the correction gain width GAIN_WID in the addition unit 25 (GAIN_CAL = GAIN_MAP2 + GAIN_WID = GAIN_25 + ((GAIN_25 - GAIN_m30)/55) x (Temp - 25)).

(C) When the thermistor temperature is equal to or greater than 25°C and less than 65°C When the thermistor temperature Temp is equal to or greater than 25°C and less than 65°C, the calculation parameters (first correction gain GAIN_MAP1, second correction gain GAIN_MAP2, temperature difference Temp_DIF, and reference temperature Temp_REF) are first 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). Furthermore, the temperature difference Temp_DIF is set to 40°C (Temp_DIF = 40), and the reference temperature Temp_REF is set to 65°C (Temp_REF = 65).

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

Specifically, the calculation unit 20 calculates the correction gain difference GAIN_DIF by subtracting the first correction gain GAIN_MAP1 from the second correction gain GAIN_MAP2 in the subtraction unit 21 (GAIN_DIF = GAIN_MAP2 - GAIN_MAP1 = GAIN_65 - GAIN_25). The calculation unit 20 calculates the correction gain slope GAIN_TILT by dividing the correction gain difference GAIN_DIF by the temperature difference Temp_DIF in the division unit 22 (GAIN_TILT = GAIN_DIF / Temp_DIF = (GAIN_MAP2 - GAIN_MAP1) / Temp_DIF = (GAIN_65 - GAIN_25) / 40).

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

The calculation unit 20 calculates the correction gain width GAIN_WID by multiplying the temperature width Temp_WID by the correction gain slope GAIN_TILT in the multiplication unit 24 (GAIN_WID = GAIN_TILT × Temp_WID = ((GAIN_65 - GAIN_25) / 40) × (Temp - 65)).

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

(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).

After one of the above processes (A) to (D) is performed depending on the thermistor temperature Temp, as shown in FIG. 4, 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 x AD_Sub). Then, for example, the CPU 4 stores in advance in memory 5 the correspondence 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.

According to the above-described embodiment, correction processing is performed 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), second current point, and third current point, thereby improving the detection accuracy of the current value actually flowing through the motor 3 over a wide current range.

In addition, by using the correction gain maps - 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, appropriate correction processing according to the temperature (thermistor temperature) of the EPS-ECU 2 becomes possible, and the detection accuracy of the current value actually flowing through the motor 3 can be improved even if the temperature (thermistor temperature) of the EPS-ECU 2 changes.

In addition, by using correction gain maps (-30 degree correction gain map, 25 degree correction gain map, 65 degree correction gain map), correction processing can be performed using the appropriate correction gain.

In addition, various design modifications may be made to the above-described configuration within the scope of the claims.

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

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. It is also possible to use correction gain maps corresponding to two temperatures, or correction gain maps corresponding to four or more temperatures.

In addition, the contents described in the above embodiment and the contents described in the above modified example may be combined as appropriate.

The present invention is widely applicable to vehicle control devices that have an assist function using a motor installed in the vehicle.

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: Calculation section 21: Subtraction section 22: Division section 23: Subtraction section 24: Multiplication section 25: Addition section 30: Multiplication section

Claims (3)

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 unit that performs a correction process to correct the voltage value detected by the current detection unit,
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. 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. 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.