JP2005100682A - Battery charge and discharge current detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery charge and discharge current detection device which can detect frequently with a simple structure the offset error contained in the detection value of a current sensor for detecting the charge and discharge current of a battery. <P>SOLUTION: In the detection of an offset error, the consumption current Ig of PWM loading (consumption current variable loading) is fixed to a prescribed value Igo and the power generation amount is controlled so that the detection value Is of a current sensor 11 may become nearly zero (reference value Iso), and the output current Ig of a generator is fixed to a value Igo at the time when the detection value Is of the charge and discharge current has become nearly zero, and changes of the battery voltage Vs after a prescribe time T has passed since the time of this fixing is detected, and, when the voltage change amount ΔVs is within a prescribed range (nearly zero), the detection value Is of the current sensor 11 after the passage of the prescribed time T is made an offset error D. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a current detection device for detecting a charge / discharge current of a battery, and belongs to the technical field of error correction of a current sensor.

  In general, a vehicle is provided with a battery for supplying electric power to the electric load for the vehicle, a generator for supplying electric power to the electric load for the vehicle and the battery, and a current sensor for detecting the charge / discharge current of the battery. However, the detected value of the current sensor may include an error such as an offset error that causes the detected value to be a value other than zero when the true value is zero. Problems arise.

  That is, the remaining capacity of the battery is calculated by adding the integrated value (charge amount) of the charging current value detected by the current sensor and subtracting the integrated value (discharge amount) of the discharge current value to the initial capacity. However, when the above error occurs, the calculation accuracy of the charge amount, the discharge amount, and the remaining capacity of the battery calculated based on these decreases. For example, when the battery is charged, the detected charge current value ( If the detected value is larger than the actual charging current value (true value), the actual charge amount may be insufficient and the battery may run out. If the detected value is smaller than the true value, There is a risk that the battery will deteriorate. In addition, when the battery is discharged, if the detected discharge current value (detected value) is smaller than the actual discharge current value (true value), there is a possibility that the battery will run out due to excessive discharge. When the value is larger than the true value, the actual remaining capacity of the battery becomes larger than the calculated remaining capacity, which may lead to overcharge at the next charging.

  Therefore, the offset error that occupies a large specific gravity of the error may be detected to correct the detection value detected by the current sensor. For example, in Patent Document 1, power is supplied to an electric load and a battery is connected. In order to detect an offset error included in a detection value of a current sensor for measuring an output current of a generator to be charged, a method of making the generator output current zero is disclosed. In this method, the output current of the generator is made zero by discharging the battery by temporarily lowering the generated voltage of the generator below the battery voltage (supplying electric power from the battery to the electric load).

JP-A-3-256539

  By the way, when detecting the offset error of the current sensor for detecting the charge / discharge current of the battery exemplified in the background art, it is necessary to set the charge / discharge current of the battery to zero. Even if the voltage is lowered, the battery is discharged and electric power is supplied from the battery to the electric load as described above. Therefore, the charge / discharge current of the battery does not become zero.

  Therefore, a method of controlling the power generation voltage of the generator so that the charging / discharging current of the battery becomes zero can be considered, but the detection value itself of the current sensor for detecting the charging / discharging current of the battery includes an error in the first place. Since it is going to detect, the detected value of this current sensor cannot be used for this power generation voltage control.

  Therefore, in order to create a situation where the charging / discharging current of the battery is surely zero, it is conceivable to provide a switch for interrupting the current flowing in the charging / discharging circuit of the battery. In addition to the complicated configuration, the control is not frequently performed.

  Accordingly, an object of the present invention is to provide a battery charge / discharge current detection device capable of frequently detecting an offset error included in a detection value of a current sensor that detects a charge / discharge current of a battery with a simple configuration. To do.

  In order to solve the above-mentioned problems, the present invention is configured as follows.

  First, the invention according to claim 1 of the present application (hereinafter referred to as the first invention) includes a battery that supplies electric power to an electric load for a vehicle, and a generator that is driven by an engine and supplies electric power to the electric load and the battery. A battery charge / discharge current detection device comprising: a power generation amount control means for controlling the power generation amount of the generator; and a current detection means for detecting a charge / discharge current of the battery. Current consumption control means for controlling the current consumption of the electric load whose current is variable, and when detecting an offset error, the current consumption control means is controlled to fix the current consumption of the current consumption variable load to a predetermined value, The power generation amount control means is controlled so that the detection value of the charge / discharge current by the current detection means becomes a reference value, and the output current of the generator is the value when the detection value of the charge / discharge current becomes a predetermined value. Fixed to Offset error detection preparation means, battery voltage change detection means for detecting a change in battery voltage after a predetermined time has elapsed since the output current of the generator was fixed by the offset error detection preparation means, and the battery voltage change detection means When the change in the battery voltage detected in the step is within a predetermined range, an offset error detection unit is provided which uses the detection value of the current detection unit when the predetermined time has elapsed as an offset error.

  In the invention according to claim 2 of the present application (hereinafter referred to as the second invention), in the first invention, the offset error detection preparation means includes a battery voltage change detected by the battery voltage change detection means deviating from a predetermined range. If the change is lower than the predetermined range, the current consumption of the variable current consumption load is increased by a predetermined amount. The battery voltage change detecting means detects the change in the battery voltage after the second predetermined time from the time when the current consumption of the variable current consumption load is increased or decreased by the predetermined amount by the current consumption control means, and the offset The error detection means is a battery voltage change detection means after a second predetermined time has elapsed since the current consumption of the current consumption variable load was increased or decreased by a predetermined amount as described above. When issued battery voltage change is within a predetermined range, the detection value of the current detecting means upon elapse second predetermined time, characterized in that the offset error.

  The invention according to claim 3 of the present application (hereinafter referred to as the third invention) is the second invention, wherein the offset error detection preparation means, the battery voltage change detection means, and the offset error detection means are controlled by the consumption current control means. If the battery voltage change detected by the battery voltage change detecting means is not within the predetermined range after the second predetermined time has elapsed since the current consumption of the current consumption variable load is increased or decreased by a predetermined amount, the predetermined amount is reduced, The process according to claim 2 is repeated.

  The invention according to claim 4 of the present application (hereinafter referred to as the fourth invention) is provided with counter means for counting the number of times of operation of the battery voltage change detecting means in the third invention, and the offset error detecting means is Even when the battery voltage change detected by the battery voltage change detecting means is not within the predetermined range, when the number of operation times of the battery voltage change detecting means counted by the counter means reaches the predetermined number, the predetermined number has been reached. In this case, the detected value of the current detecting means is an offset error.

  Further, the invention according to claim 5 of the present application (hereinafter referred to as the fifth invention) is provided with counter means for counting the number of operation times of the battery voltage change detecting means in the third invention, and the offset error detecting means is Even when the battery voltage change detected by the battery voltage change detecting means is not within the predetermined range, when the number of operation times of the battery voltage change detecting means counted by the counter means reaches the predetermined number, the predetermined number has been reached. The average value of the detected value of the current detecting means and the previous detected value of the current detecting means is used as an offset error.

  In the invention according to claim 6 of the present application (hereinafter referred to as the sixth invention), in the third invention, the offset error detecting means is such that the battery voltage change detected by the battery voltage change detecting means is not within a predetermined range. Even when the predetermined amount of increase or decrease in the current consumption of the variable current consumption load is equal to or less than the predetermined increase / decrease amount, the detected value of the current detection means when the predetermined amount of increase / decrease is equal to or less than the predetermined increase / decrease amount It is characterized by that.

  Next, the effect of the present invention will be described.

  First, according to the first invention, as preparation for detecting an offset error, the consumption current of the consumption current variable load is controlled to a predetermined value, and the detection value of the charge / discharge current becomes the reference value by controlling the amount of power generation. The output current of the generator is fixed to the output current value when the detected value of the charge / discharge current becomes the reference value. When the change in the battery voltage after a predetermined time has elapsed from the time when the output current of the generator is fixed is within a predetermined range, the detection value of the current detection means when the predetermined time has elapsed is regarded as an offset error.

  That is, when the battery voltage increases after a predetermined time elapses, charging current flows through the battery, and when it decreases, discharging current flows from the battery. Within the range means that the battery charging current or discharging current hardly flows, that is, the current is almost zero, and the detected value at this time is set as an offset error.

  Moreover, according to the first invention, it is possible to detect the offset error with a simple configuration without newly providing a detection device. In addition, since the change in the battery voltage appears in a short time, not only can the offset error detection control be executed frequently and frequently, but also the operating state of the electric load fluctuates during the detection of the battery voltage change (the electric load Since there are rare cases of new operation or operation stoppage, detection control can be completed almost certainly.

  According to the second aspect of the invention, when the battery voltage change detected by the battery voltage change detecting means rises outside the predetermined range, the current consumption of the current consumption variable load is increased by a predetermined amount, and the change is within the predetermined range. In the case of a drop that deviates from, the current consumption of the current consumption variable load is reduced by a predetermined amount. When the change in the battery voltage after the second predetermined time has elapsed from the time when the current consumption of the variable current consumption load is increased or decreased by the predetermined amount, the current detection means at the time when the second predetermined time has elapsed The detected value is an offset error.

  That is, as compared with the first invention, the probability that an offset error is detected increases and the accuracy of the detected offset error is improved.

  According to the third aspect of the present invention, the predetermined amount is reduced when the change in the battery voltage after the second predetermined time has elapsed from the time when the consumption current of the variable consumption current load is increased or decreased by the predetermined amount. Thus, the process of claim 2 is repeatedly executed. That is, the offset error is detected more reliably and the accuracy of the detected offset error is further improved.

  According to the fourth aspect of the invention, even when the battery voltage change detected by the battery voltage change detecting means is not within the predetermined range, when the number of operation times of the battery voltage change detecting means reaches the predetermined number, the predetermined number of times is reached. The detected value of the current detection means when it is reached is taken as an offset error. That is, in the third invention, the control for detecting the offset error is repeatedly executed until the offset error is detected. However, in practice, the offset error is detected to the extent that there is no problem if it is executed a predetermined number of times. Accuracy is improved. Therefore, even when the battery voltage change detected by the battery voltage change detecting means is not within the predetermined range, this control is terminated when the predetermined number of times is executed. Moreover, according to this, it is avoided that this control is performed for a long time forever.

  According to the fifth aspect of the invention, even when the battery voltage change detected by the battery voltage change detecting means is not within the predetermined range, when the number of operation times of the battery voltage change detecting means reaches the predetermined number, the predetermined number of times is reached. The average value of the detection value of the current detection means when reached and the detection value of the previous current detection means is taken as the offset error. In other words, when the increase and decrease of the consumption current of the consumption current variable load are repeated alternately, the offset error is set to the above average value, so that a more accurate offset error can be detected even if the number of detections is small. Can do it.

  According to the sixth aspect of the invention, even when the battery voltage change detected by the battery voltage change detecting means is not within the predetermined range, the predetermined amount of increase or decrease of the consumption current of the consumption current variable load is equal to or less than the predetermined increase / decrease amount. When this happens, the detected value of the current detection means when the amount is less than or equal to the predetermined increase / decrease amount is taken as an offset error. That is, when the predetermined amount of increase or decrease in the consumption current of the consumption current variable load is equal to or less than the predetermined increase / decrease amount, it is possible to sufficiently secure the detection accuracy of the offset error.

  Hereinafter, a battery charge / discharge current detecting apparatus according to the best mode for carrying out the present invention will be described.

  FIG. 1 shows a configuration of a battery charge / discharge current detection device 1 according to the first best mode. The vehicle is provided with a battery 3 for supplying electric power to the vehicle electric load 2 and a generator 4 for supplying electric power to the vehicle electric load 2 and charging the battery 3. Here, the battery 3 is a lead storage battery generally used for automobiles, and the generator 4 is constituted by an alternator, a regulator for adjusting output voltage, and the like. Further, as the electric load 2 for the vehicle, in addition to loads such as an air conditioner, a headlamp, and a defogger, a current consumption Ig can be arbitrarily controlled by PWM (Pulse Width Modulation) control, for example, an electric fan for forcibly cooling a radiator, A variable consumption current load 2a (hereinafter referred to as “PWM load 2a”) such as a transmission oil pump and a fuel pump is provided.

  In addition, the vehicle includes a control unit 10, a current sensor 11 that detects a charge / discharge current value of the battery 3, and a battery voltage sensor 12 that detects a terminal voltage of the battery 3. The control unit 10 inputs signals from these sensors 11 and 12 and controls the output voltage of the generator 4 based on the signals, thereby charging and discharging the battery 3 and the remaining capacity of the battery 3. To control.

  By the way, as described in the background art, the detection value of the current sensor generally includes an error such as an offset error. This will be described with reference to FIG. 2. The ideal characteristic of the detected value Y with respect to the true value X should be Y = X as indicated by the solid line, but is indicated by the dotted line due to the offset error D. Thus, Y = X + D characteristics are obtained. In this case, since the accuracy of the remaining battery capacity control is lowered, in order to prevent this, the detection value output with the characteristic Y = X + D may be corrected so as to coincide with the ideal characteristic Y = X. That is, a process of calculating back the true value X from the detected value Y by X = Y−D, which is a modification of the above actual characteristic formula, may be performed. Actually, since the numerical value obtained by the modified expression is not the true true value X but the true value X ′ obtained from the detected value Y, X ′ = Y−D is set so as not to cause misunderstanding. Hereinafter, this is referred to as a detection value correction formula.

  In this case, in order to correct the detection value based on the equation, it is necessary to grasp the offset error D. However, the detection of the offset error of the current sensor for detecting the charge / discharge current of the battery is also described in the background art. There are various problems.

  Therefore, in the present embodiment, when detecting the offset error, the control unit 10 outputs the control signal a to the PWM load 2a and fixes the current consumption Ip to a predetermined value Ipo, and also supplies the control signal to the generator 4. b is output to control the amount of power generation so that the detected value Is of the charge / discharge current by the current sensor 11 becomes the reference value Iso (approximately 0 in the present embodiment), and the output current Ig of the generator 4 is The detection value Is of the charge / discharge current is fixed to the value Igo when the reference value Iso is reached. Then, a change in the battery voltage Vs after the elapse of a predetermined time T from the time when the output current Ig of the generator 4 is fixed is detected, and the change in the battery voltage is within a predetermined range (almost zero (eg, zero ± 1 (A)). In the range)), the detected value A of the current sensor 11 when the predetermined time T elapses is set as the offset error D. Hereinafter, the offset error detection control by the control unit 10 will be described in detail with reference to the flowchart of FIG.

  First, in step S1, it is determined whether an offset error detection condition is satisfied. Here, whether or not the offset error detection condition is satisfied is determined from the viewpoint of not impairing the function of the PWM load 2a by executing the control for detecting the offset error. For example, when the PWM load 2a is an electric fan, if the control for detecting the offset error is performed when the cooling water temperature of the engine is high, the original function of the electric fan cannot be fully exhibited. Therefore, in such a case, it is determined that the offset error cannot be detected so that the offset error detection control is not executed. On the other hand, when the cooling water temperature is low or the electric fan is stopped, the function of the electric fan is not impaired, and it is determined that the offset error can be detected.

  When the determination in step S1 is YES, that is, when the offset error detection condition is satisfied, the consumption current Ip of the PWM load 2a is controlled to a predetermined value Ipo in step S2. Here, the predetermined value Ipo is set to a value approximately half (half) of the maximum consumption current of the PWM load 2a. For example, if the maximum current consumption of the electric fan is 15A, it is 8A. As will be described later, the purpose of this is to ensure substantially the same increase / decrease amount in any direction when increasing / decreasing the current consumption Ip.

  Next, in step S3, the detection value Is of the current sensor 11 is read. In step S4, the power generation amount of the generator 4 is controlled so that the detection value Is of the current sensor 11 becomes zero (the above-described reference value Iso). The reference value Iso may not be zero, but may be any other value as long as it is within the maximum error of the current sensor 11 (for example, ± 3 (A)). In step S5, it is determined whether or not the detection value Is is substantially zero. Here, substantially zero means that the detection value Is is within a predetermined range, for example, within zero ± 1 (A). When the determination in step S5 is YES, in step S6, the output current Ig of the generator 4 is fixed to the current value Igo, and in step S7, the latest detection values Is of the current sensor 11 and voltage sensor 12 are fixed. , Vs are read and stored as fixed values Is1, Vs1. On the other hand, when the determination in step S5 is NO, that is, when the detected value Is is not substantially zero, the processes in steps S3 to S5 are repeated until YES is determined in step S5, and then steps S6 and S7 are performed. Execute.

  Next, in step S8, it is determined whether or not the predetermined time T has elapsed since the time when the output current Ig of the generator 4 was fixed as described above. If YES, that is, if the predetermined time T has elapsed, In S9, the latest detected values Is and Vs of the current sensor 11 and the voltage sensor 12 are read and stored as values Is2 and Vs2 after the elapse of the predetermined time T, and values Is2 and Vs2 after the elapse of the predetermined time T in step S10. By subtracting the fixed values Is1 and Vs1 from Vs2, respectively, a change amount ΔVs of the battery voltage Vs and a change amount ΔIs of the charge / discharge current are calculated.

  Next, in step S11, whether or not the change amount ΔIs of the charging / discharging current Is is substantially zero, that is, the detected value of the current sensor 11 after the predetermined time T has elapsed since the output current Ig of the generator 4 is fixed to Igo. It is determined whether or not the change amount ΔIs of Is is within a predetermined range (−α ≦ ΔIs ≦ α). If YES, that is, if the change amount ΔIs is within the predetermined range, step S12 and subsequent steps are executed. To do. On the other hand, when this determination is NO, that is, when the change amount ΔIs is not within the predetermined range, the process returns to step S3, and the subsequent processing is executed again. Here, after the output current Ig of the generator 4 is fixed to Igo, the charge / discharge current value changes when the operating state of the electric load 2 fluctuates (new operation of the electric load 2 or operation stop). Since the offset error D cannot be detected, the process is restarted from step S3.

  Next, in step S12, whether or not the change amount ΔVs of the battery voltage Vs calculated in step S10 is substantially zero, that is, the voltage sensor 12 after the predetermined time T has elapsed from when the output current Ig of the generator 4 is fixed. It is determined whether the change amount ΔVs of the detected value Vs is within a predetermined range (−β ≦ ΔV ≦ β). In other words, the fact that the voltage change ΔVs is almost zero (within a predetermined range) means that almost no charge / discharge current is flowing in the battery 3, so this step S12 is performed when the charge / discharge current of the battery 3 is zero. In other words, it is determined whether or not the current detection value Is may be used as an offset error. Here, the predetermined value β may be set in consideration of the required accuracy of offset error detection and the like. When the determination in step S12 is YES, that is, when the change amount ΔVs is within a predetermined range, the detected value Is at that time may be used as an offset error. The detected value Is2 of the current sensor 11 later is stored as an offset error D. That is, the value of the parameter D in the detection value correction formula X ′ = Y−D is rewritten to this detection value Is2.

  On the other hand, when the determination in step S12 is NO, that is, when the change amount ΔVs is not within the predetermined range, the current detection value Is should not be the offset error D. Therefore, the process does not proceed to step S18. Proceeding to S13, 1 is added to the value of the counter n for counting the number of executions n of steps S7 to S10, that is, the number n of detections of battery voltage change. The initial value of n is zero, and the value of n becomes 1 by addition at this time. In step S14, it is determined whether or not the value of the counter n is greater than or equal to a predetermined value N. If YES, that is, if the value of the counter n is greater than or equal to the predetermined value N (has reached the predetermined value N), step In S18, the detected value Is2 of the current sensor 11 after a predetermined time T has elapsed is stored as an offset error D.

  On the other hand, when the determination in step S14 is NO, that is, when the value of the counter n is not equal to or greater than the predetermined value N, it is determined in step S15 whether or not the change in the battery voltage Vs is increased. Here, the fact that the battery voltage Vs is increasing means that the battery 3 is in a charged state, and the fact that the battery voltage Vs is decreasing means that the battery 3 is in a discharging state. Step S15 determines whether the battery 3 is in a charged state or a discharged state.

  When the determination in step S15 is YES, that is, when the change in the battery voltage Vs is increased, in step S16, the consumption current Ip of the PWM load 2a is reduced by a predetermined amount K so that the charging current of the battery 3 decreases. When the determination in step S15 is NO, that is, when the change in the battery voltage Vs is not an increase (when it is decreasing), the discharge current of the battery 3 decreases in step S17. As described above, the current consumption Ip of the PWM load 2a is reduced by the predetermined amount K, and the steps after step S7 are executed again.

  That is, in step S7, the latest detection values Is and Vs of the current sensor 11 and the voltage sensor 12 when the consumption current Ip of the PWM load 2a is increased or decreased by a predetermined amount K are read, and the value Is1 when the current is increased or decreased. , Vs1, and after the elapse of a predetermined time T, in step S9, the latest detection values Is, Vs of the current sensor 11 and the voltage sensor 12 are read and stored as values Is2, Vs2 after the elapse of the predetermined time, and step S10. The values Is1 and Vs1 when the current consumption Ip of the PWM load 2a is increased or decreased by a predetermined amount K are subtracted from the values Is2 and Vs2 after the predetermined time T has elapsed, respectively, so that the change amount ΔVs of the battery voltage Vs, And a change amount ΔIs of the charge / discharge current Is is calculated, and it is determined whether or not the change amounts ΔIs and ΔVs are within the predetermined range. Executing a control according to the determination result. That is, according to the control according to this flowchart, when the battery voltage change amount ΔVs falls within the predetermined range, or when the number n of detections of the battery voltage change amount ΔVs reaches the predetermined number N, the current sensor 11 The detected current value Is is stored as the offset error D.

  Here, the predetermined amount K of increase or decrease of the current consumption Ig of the PWM load 2a in the above step S16 and step S17 is 0.5, 3 if the value at the first increase or decrease is 1, for example. The number of times is set to 0.25, such as 0.25 each time the times are repeated.

  Next, the operation and effect of the battery charge / discharge current detection device 1 will be described with reference to FIG. In this description, specific numerical values are used for easy understanding.

  First, when the offset error detection condition is satisfied, the current consumption Ip of the PWM load 2a is controlled to 8A of a predetermined value Ipo. Here, the value 8A of the predetermined value Ipo is a value when the PWM load 2a is an electric fan having a maximum current consumption 15A. At this time, the power generation amount of the generator 4 is controlled so that the detection value Is of the current sensor 11 becomes zero (A) of the reference value Iso, and the output current Ig of the generator 4 is set to the detection value Is. Is fixed to the value Igo when the value becomes zero (A) (time t0).

  Whether or not the change amount ΔVs of the battery voltage Vs is substantially zero, that is, within a predetermined range (−β ≦ ΔV ≦ β) after a predetermined time T has elapsed (time t1) from the fixed time (t0). In this example, since the change amount ΔVs after the lapse of the predetermined time T is not within the predetermined range, 1 is added to the counter n and the change in the battery voltage V is increased. The current consumption Ig of the PWM load 2a is increased by 2 (A) by a predetermined amount K to the above-mentioned Igo and controlled to 10 (A). At this time, the detection value Is of the current sensor 11 is −2 (A).

  Then, after the current consumption Ip of the PWM load 2a is increased by 2 (A), the change amount ΔVs of the battery voltage Vs is within a predetermined range (−β ≦ ΔV ≦) after the elapse of the predetermined time T (time t2). In this example, since the change amount ΔVs is not yet within the predetermined range, 1 is added to the counter n, the value of the counter n becomes 2, and the battery Since the change in the voltage Vs is a drop, the current consumption Ip of the PWM load 2a is reduced by 1 (A), which is half the increase 2 (A), from the value 10 (A) after the increase, and 9 (A ) Is controlled. At this time, the detection value Is of the current sensor 11 is −1 (A).

  Then, after the current consumption Ip of the PWM load 2a is reduced by 1 (A), after a predetermined time T has elapsed (time t3), the change amount ΔVs of the battery voltage Vs is within a predetermined range (−β ≦ ΔV ≦ β) is determined, but since the change amount ΔVs is not yet within the predetermined range, 1 is added to the counter n, the value of the counter n becomes 3, and the change in the battery voltage V Since the current consumption Ip of the PWM load 2a is increased by 0.5 (A), which is half of the reduced amount 1 (A), the current consumption Ip of the PWM load 2a is 9.5 ( Controlled by A). At this time, the detection value Is of the current sensor 11 is −1.5 (A).

  Then, after the current consumption Ip of the PWM load 2a is reduced by 0.5 (A) in this way, after a predetermined time T has elapsed (time t4), the change amount ΔVs of the battery voltage Vs is within a predetermined range (−β ≦ It is determined whether or not ΔV ≦ β). In this example, since the change amount ΔVs is within a predetermined range, the value Is2 that is detected and stored after the elapse of the predetermined time T is −1. .5 (A) is stored as the value of the latest offset error D, the parameter (offset error) D of the detection value correction formula X ′ is rewritten, and the detection value Is of the current sensor 11 thereafter is rewritten. Correction is performed based on the detection value correction formula X ′.

  By the way, in the above example, the case where the change amount ΔVs of the battery voltage Vs is within a predetermined range (−β ≦ ΔV ≦ β) at time t4 has been described, but as indicated by the dotted line a, the current consumption of the PWM load 2a If the amount of change ΔVs of the battery voltage Vs after the predetermined time T has elapsed (time t4) from when Ip is reduced by 0.5 (A), the above determination may be repeated indefinitely. For example, if the predetermined value N related to the value of the counter n is set to 4, the value of the counter n reaches 4 even when the change amount ΔVs of the battery voltage Vs at time t4 is not within the predetermined range. (Time t4), -1.5 (A) of the value Is2 detected and stored after the lapse of the predetermined time T is stored as the value of the offset error D, and the detected value correction formula X ' Parameter ( Offset error) D is rewritten, the detection value Is of the subsequent current sensor 11 is to be corrected on the basis of the rewritten detected value correction formula X '. Note that the value of the predetermined value N may be set to a value that sufficiently guarantees the offset error detection accuracy if the detection is repeated the number of times.

  In this example, the value of the offset error D stored when the value of the counter n reaches 4 is the value Is2 detected at the time t4. As described above, the increase and decrease are alternately performed. When a predetermined value K for increasing and decreasing is set to a value to be performed, the value of the offset error D is an average value of the value Is2 detected at time t4 and the value Is2 detected at time t3. It is good. According to this, as will be described later, it is possible to improve the accuracy of the detected offset error even if the number n of battery voltage change detections is small. Hereinafter, the control in that case will be described with reference to the flowchart shown in FIG. Although the description of the steps before step S32 is omitted in FIG. 5, the same processing as steps S1 to S11 in the flowchart of FIG. 3 is performed as steps S21 to S31 before step S32. Further, the processes of steps S32 to S34 and step S39 are the same as the processes of steps S12 to S14 and step S18 in the flowchart of FIG.

  That is, when the determination in step S34 is NO, that is, when the value of the counter n is not equal to or greater than the predetermined value N, in step S35, the stored n-th detection value Isn is stored as Isn-1, and the above detection is performed. The value Is2 is stored as the nth detection value Isn. Next, in step S36, it is determined whether or not the change in the battery voltage Vs is an increase. When this determination is NO, that is, when the change in the battery voltage V increases, in step 37, the consumption current Ip of the PWM load 2a is increased by a predetermined amount K, and the above steps S27 and subsequent steps are executed again, and step S36 When the determination of NO is NO, that is, when the change of the battery voltage Vs is not an increase (a decrease), in step S38, the consumption current Ip of the PWM load 2a is decreased by the predetermined amount K, and the steps after step S27 are executed again. To do.

  On the other hand, when the determination in step S34 is YES, that is, when the value of the counter n is equal to or greater than the predetermined value N (has reached the predetermined value N), the stored n-th detection value Isn is set to Isn− in step S40. 1 and the detected value Is2 is stored as the nth detected value Isn. In step S41, an average value of the newly stored nth detection value Isn and n−1th detection value Isn−1 is calculated, and this average value is stored as an offset error D. Then, the stored data of the nth detection value Isn and the n−1th detection value Isn−1 are reset to zero.

  According to the control of the flowchart of FIG. 5, in the time chart of FIG. 4, the nth detection value Isn is −1.5 (A), and the (n−1) th detection value Isn−1 is −. Since it is 1 (A), the average value is -1.25 (A). Here, when the increase / decrease amount K is halved, in the example of FIG. 4, the amount is then increased by 0.25 A. In this case, the current sensor 11 will next detect it. The value Is is -1.25 (A) and the average value is equal to the value that would be detected. That is, it is equal to the offset error when the change amount ΔVs of the battery voltage Vs falls within the predetermined range at the time of detecting the next battery voltage change. That is, it is possible to improve the detection accuracy of the offset error while reducing the number of detections n.

  In this example, the case where the predetermined value K for the increase and the decrease is set to a value at which the increase and the decrease are alternately performed has been described. However, depending on the value of the predetermined value K for the increase and the decrease, it is not always necessary. Since the battery voltage change is not necessarily repeated between rising and falling (for example, when the battery voltage change is rising → decreasing → decreasing), in such a case, when the predetermined number N is reached The detected current value Is is opposite to the direction of battery voltage change when the predetermined number N is reached and is detected before reaching the predetermined number N, which is closest to the current detected value Is when the predetermined number N is reached. An average value of the detected current value Is may be used as the offset error D.

  In the above example, when the voltage change amount ΔVs falls within the predetermined range, the offset error D is determined when the detection number n reaches the predetermined number N. However, the battery voltage change is detected. The offset error D may be determined when the increase / decrease amount K, which is reduced each time it is performed, becomes equal to or less than a predetermined increase / decrease amount. In this case, the predetermined increase / decrease amount may be a sufficiently small value that can sufficiently ensure the accuracy of the offset error detection.

  As described above, according to the best mode for carrying out the present invention, the offset error D can be detected with a simple configuration. Further, since the change in the battery voltage appears in a short time, the offset error detection control can be executed frequently and frequently as long as the condition that the function of the PWM load 2a that is the offset error detection condition is not impaired is satisfied. In addition, since it is rare that the operating state of the electric load 2 fluctuates (new operation or operation stop of the electric load 2) during the detection of the battery voltage change, the detection control can be almost certainly completed.

  Even when the amount of change ΔVs of the battery voltage Vs is not within the predetermined range, when the battery voltage change detection number n reaches the predetermined number N, the detected value A of the current sensor 11 when the predetermined number N is reached. Since the offset error D is set, it is avoided that the control is continuously executed for a long time.

  Further, if the current detection device 1 described in the first and second embodiments is applied to a battery capacity detection device, the charge / discharge current of the battery 3 can be detected with high accuracy, and the capacity of the battery 3 can be reduced. It becomes possible to estimate with high accuracy. That is, it is possible to effectively prevent the battery from being charged due to insufficient charging of the battery 3 or the battery deterioration due to battery overcharging.

  In the description of the operation in the above-described embodiment, the predetermined value N related to the value of the counter n is set to 4. However, the present invention is not limited to this, and may be changed according to the required offset error detection accuracy. .

  In the above embodiment, the increase / decrease amount K is halved each time the determination is repeated. However, the present invention is not limited to this, and the first increase / decrease amount is, for example, 1/10 of the above embodiment, The increase / decrease amount may be finely changed with this value without being changed.

  In the above embodiment, the predetermined time and the second predetermined time described in the claims are both set to the same value as the predetermined time T, but may be different values.

  The present invention is not limited to vehicles, and can be widely applied to a current detection device that detects a charge / discharge current of a battery.

It is a block diagram of the battery charging / discharging current detection apparatus which concerns on the best form for implementing this invention. It is explanatory drawing of the offset error contained in the detected value of a current sensor. It is an example of the flowchart of the offset error detection control which concerns on the best form. It is a time chart explaining the effect | action of the control. It is another example of the flowchart of offset error detection correction control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery charging / discharging electric current detection apparatus 2 Electric load for vehicles 2a PWM load (current consumption variable load)
3 battery 4 generator 10 control unit (power generation amount control means, current consumption control means, offset error detection preparation means, battery voltage change detection means, offset error detection means, counter means)
11 current sensor 12 voltage sensor T predetermined time (predetermined time, second predetermined time)

Claims (6)

A battery that supplies electric power to an electric load for vehicles, a generator that is driven by an engine to supply electric power to the electric load and the battery, a power generation amount control means that controls a power generation amount of the power generator, and charge / discharge of the battery A battery charge / discharge current detecting device comprising a current detecting means for detecting a current, wherein the current consumption of the electric load of the electric load is variable; At the time of error detection, the current consumption control means is controlled to fix the current consumption of the current consumption variable load to a predetermined value, and the power generation amount control is performed so that the charge / discharge current detection value by the current detection means becomes a reference value. Offset error detection preparation means for controlling the means and fixing the output current of the generator to a value when the detected value of the charge / discharge current reaches a predetermined value, and the offset error detection preparation means Battery voltage change detecting means for detecting a change in battery voltage after a predetermined time has elapsed from the time when the output current of the generator is fixed, and when the battery voltage change detected by the battery voltage change detecting means is within a predetermined range The battery charge / discharge current detecting device is provided with offset error detecting means that uses the detected value of the current detecting means when the predetermined time has passed as an offset error. The offset error detection preparation means controls the current consumption control means to increase the current consumption of the current consumption variable load by a predetermined amount when the battery voltage change detected by the battery voltage change detection means rises beyond a predetermined range. When the change falls outside the predetermined range, the current consumption of the variable current consumption load is decreased by a predetermined amount, and the battery voltage change detecting means is configured to reduce the current consumption of the variable current consumption load by the current consumption control means. The change in the battery voltage after the second predetermined time has elapsed from the time when the quantitative increase or decrease is detected, and the offset error detection means detects the current consumption of the variable current consumption load from the time when the current consumption is increased or decreased by a predetermined amount as described above. If the battery voltage change detected by the battery voltage change detecting means is within a predetermined range after the second predetermined time has elapsed, the current at the time when the second predetermined time has elapsed Battery charging and discharging current detecting apparatus according to claim 1, the detection value of the detecting means, characterized in that the offset error. The offset error detection preparation means, the battery voltage change detection means, and the offset error detection means are configured to change the battery voltage after a second predetermined time has elapsed from when the current consumption of the variable current consumption load is increased or decreased by a predetermined amount by the current consumption control means. 3. The battery charge / discharge current detecting device according to claim 2, wherein when the battery voltage change detected by the detecting means is not within a predetermined range, the predetermined amount is reduced and the processing according to claim 2 is repeated. . Counter means for counting the number of operation times of the battery voltage change detecting means is provided, and the offset error detecting means counts by the counter means even when the battery voltage change detected by the battery voltage change detecting means is not within a predetermined range. 4. The battery charge according to claim 3, wherein when the number of times of operation of the battery voltage change detection unit that has been reached reaches a predetermined number, the detected value of the current detection unit when the predetermined number of times is reached is used as an offset error. Discharge current detection device. Counter means for counting the number of operation times of the battery voltage change detecting means is provided, and the offset error detecting means counts by the counter means even when the battery voltage change detected by the battery voltage change detecting means is not within a predetermined range. When the number of operations of the battery voltage change detection means performed reaches a predetermined number, an average value of the detection value of the current detection means and the previous detection value of the current detection means when the predetermined number of times is reached is set as an offset error. The battery charge / discharge current detection device according to claim 3. The offset error detection means detects when the predetermined amount of increase or decrease in the current consumption of the variable current consumption load is equal to or less than the predetermined increase / decrease amount even when the battery voltage change detected by the battery voltage change detection means is not within the predetermined range. The battery charge / discharge current detection device according to claim 3, wherein the detected value of the current detection means when the amount is equal to or less than the predetermined increase / decrease amount is set as an offset error.

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