JP2007008214A - Load control system and load control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure electric power to drive a load of an important safety system while maintaining comfortability by restraining limitation of a load electric current to the requisite minimum. <P>SOLUTION: This load control system is furnished with a voltage measuring means 8a to occasionally measure terminal voltage V of a battery 5, an electric current measuring means 8b to occasionally measure an electric current I flowing to the side of the loads 6a to 6f from the battery 5, an electric power source state detection means 10 to find an electric current voltage characteristic 14 of the battery 5 by statistic treatment of measured values of the electric current I and the voltage V and a load control means 11 to secure the electric power necessary to drive the load of the important safety system by restricting a supply electric current to the load which is not the important safety system when the battery 5 can not sufficiently drive the load of the important safety system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a load control system and a load control program for performing drive control of a load mounted on an automobile.

  FIG. 13 is a diagram showing a configuration of a power supply circuit 90 in a conventional automobile. That is, while the engine 91 is rotating, the generator 92 converts the rotational force of the engine 91 into electric energy, supplies it to the loads 93a to 93f of each part, and uses the surplus power to recharge the secondary battery (battery). ) Charge 94. On the other hand, when the electric energy obtained by the generator 92 is not sufficient for the operation of the loads 93a to 93f, this can be compensated by supplying power from the battery 94. Therefore, in a state where the battery 94 is not sufficiently charged, power sufficient for the operation of the loads 93a to 93f cannot be obtained, and operation failure may occur.

  By the way, in recent years, there is a tendency that a part for controlling the automobile is an electrical load, and a burden on the battery 94 tends to be increased. For example, in an automobile steering section, an electric steering device called electric power steering (EPS) is used instead of hydraulic power steering. Further, assist functions such as an electric brake and a collision accident prevention system including a so-called “pre-crash system” also increase an electric load.

  In addition to the EPS, the electric brake, and the collision accident prevention system, some important safety loads including an air bag system instantaneously require large electric power. Therefore, it is necessary to use a battery 94 having a sufficient capacity so that the battery 94 can supply a large amount of power. Further, the current flowing through the loads 93b to 93f is limited in accordance with the state of the battery 94.

Patent Document 1 describes that a voltage drop in the case where a large current flows is detected by detecting the state of the battery 94, and the current flowing through the load is limited when the voltage drop is below a reference value.
JP 2004-194364 A

  However, in Patent Document 1, the magnitude of the voltage drop during the operation of the loads 93a to 93f is accurately obtained from the state of the battery 94 that changes from moment to moment, and whether or not the loads 93a to 93f can be driven is accurately determined. An effective means for judging was not described. For this reason, in Patent Document 1, it is impossible to consider the possibility of whether or not a load with high importance actually operates, and in order to secure a current necessary for a load with high importance. I had to limit the current supply to the load with a margin. Even when there is no influence on the operation of the load having high importance, the comfort may be lost due to frequent control.

  The present invention has been made in consideration of the above-described problems, and is intended to drive a load of an important safety system while maintaining comfort while minimizing a load current limit. To provide a load control system and a load control program capable of securing electric power.

In order to achieve the above object, a load control system according to claim 1 comprises:
Voltage measuring means for measuring the terminal voltage of the battery mounted on the vehicle as needed;
Current measuring means for measuring current flowing from the battery to the load side as needed;
A power supply state detection means for determining current and voltage characteristics of the battery at any time by performing statistical processing of current and voltage measured at any time;
A load control means for predicting a terminal voltage that drops with an operation of a load of an important safety system by using the current-voltage characteristics, and for limiting a current flowing to a load that is not an important safety system based on the predicted terminal voltage; It is characterized by having.

In the load control system of the present invention, since the state of the battery is represented by the current-voltage characteristic that is obtained at any time by statistical processing of the current and voltage measured at any time, the current battery is used as an important security system. It is possible to accurately predict the terminal voltage in a state where a current necessary for driving the load is supplied. If the current state of the battery is not sufficient for the operation of the important safety system load, it is possible to appropriately limit the current flowing to the non-critical safety system load. The current-voltage characteristic can be expressed by a function f (I) indicating the terminal voltage V, and this function f (I) can be easily expressed by a linear expression. It may be expressed using a trigonometric function. In any case, by obtaining the constant part of the function f (I) by statistical processing, it is possible to accurately represent the state of the battery that changes from moment to moment.
The important safety system load is, for example, an electric steering device (that is, EPS). That is, the safety of the automobile can be ensured by securing the electric power necessary for driving the electric steering apparatus.

The current-voltage characteristic is an internal resistance value of the battery,
The power supply state detection means calculates and updates the internal resistance value at each point in time from the current and voltage variation measured at any time, and
The load control means may predict the terminal voltage in a state where the current for driving the load of the important safety system is passed from the measured value of the internal resistance value and the voltage and current at each time point.

  That is, since the relationship between the terminal voltage of the battery and the current flowing from the battery to the load side is in a first-order proportional relationship, the internal resistance value can be statistically obtained from the amount of change in the terminal voltage of the battery and the current flowing from the battery. Based on the relationship between the calculated internal resistance value and the current terminal voltage and current of the battery, it is easy to obtain an accurate terminal voltage when a current of a magnitude required to drive an important safety load is supplied from the battery. Can be requested. In addition, since the calculation for obtaining the internal resistance value from the amount of change in current and voltage is extremely simple, the configuration of the power supply state detection means can be simplified.

  If the internal resistance value of the battery can be obtained and the relationship between the terminal voltage and current at an arbitrary time can be obtained, the terminal voltage in the open state of the battery (when the current is 0), that is, the electromotive force (internal voltage) inside the battery And can accurately represent the current-voltage characteristics of the battery using Ohm's law. That is, a linear function having the internal voltage and the internal resistance value as constants may be used as the current-voltage characteristic.

  The power supply state detection means may separately obtain a current-voltage characteristic during charging and a current-voltage characteristic during discharging. In other words, a battery has a charge characteristic and a discharge characteristic. By obtaining these separately, the current required to drive an important safety load is calculated based on the current-voltage characteristic that matches the discharge characteristic of the battery. The terminal voltage in the flowing state can be predicted more accurately.

  The load control means may adjust the load limit level according to the magnitude of the current predicted to be insufficient for driving the important safety system load. With this configuration, the limit level is adjusted in accordance with the magnitude of the current that is predicted to be insufficient for driving the important safety system load, so that the necessary minimum load current can be limited. That is, it is possible to secure the electric power necessary for driving the important safety system load without impairing the comfort as much as possible. Note that the load control system may include load current prediction means for predicting the magnitude of the current flowing through the important safety system load.

  Further, it is desirable that the load for limiting the current be divided into high speed traveling and low speed traveling according to the speed of the automobile. That is, during high speed traveling, for example, loads such as an air conditioner and a heater are almost unnecessary, and the current supplied to these loads can be positively limited. Similarly, when driving at a low speed, for example, loads such as a high beam of a headlight and a fog lamp are almost unnecessary, and it is preferable to more actively limit the current supplied to these loads.

The present invention also provides a load control program.
The load control program of the present invention is
By being executed by an arithmetic processing unit of a load control system comprising voltage measuring means for measuring terminal voltage of a battery mounted on a vehicle as needed and current measuring means for measuring current flowing from the battery to the load side as needed, A load control program for monitoring voltage and current measurement values measured at any time by the voltage measurement means and the current measurement means, and ensuring power necessary for the operation of the load of the important safety system,
A power supply state detection program for determining the current-voltage characteristics of the battery at any time by performing statistical processing of the current and voltage measured at any time;
A load current limiting program that predicts a terminal voltage that drops with the operation of an important safety system load by using the current-voltage characteristics, and that limits a current that flows to a load that is not an important safety system based on the predicted terminal voltage It is characterized by having.

  In the load control program of the present invention, the state of the battery is represented by current-voltage characteristics that are obtained as needed by statistical processing. Therefore, by using this current-voltage characteristic, the terminal voltage of the battery can be accurately predicted in a state where a current necessary for driving an important safety load that always matches the current state of the battery is passed. When the operation of the important safety system load is not sufficient, it is possible to appropriately limit the current flowing through the non-critical safety system load.

The power supply state detection program has an internal resistance value calculation program that calculates and updates the internal resistance value at each time point from the current and voltage change amounts measured at any time,
The load current limiting program may predict a terminal voltage in a state where a predetermined current is passed through an important safety system load using the internal resistance value updated as needed.

  By configuring in this way, the internal resistance value of the battery can be obtained by a very simple calculation, so that the internal resistance value calculation program is simplified, the burden on the arithmetic processing unit is small, and the processing can be performed at high speed. In addition, since the load current limit program predicts the terminal voltage using the internal resistance value that is updated from time to time, the terminal voltage can be predicted according to the current state of the battery through extremely simple calculations. It can be processed at high speed.

  As described above, the load control system of the present invention accurately obtains the current-voltage characteristics of the battery that change from moment to moment, and accurately determines the terminal voltage of the battery in a state in which the current necessary for the important safety system load is passed. Therefore, it is possible to appropriately limit the current flowing to a load that is not an important safety system. In other words, it is possible to secure the power supplied to the important security system while maintaining comfort.

By paying attention to the internal resistance value of the battery as the current-voltage characteristic of the battery, the internal resistance value can be easily obtained from the amount of change in the current and voltage, thereby accurately and rapidly determining the current-voltage characteristic of the battery at each time point. Can be requested.
Further, by obtaining separately the current-voltage characteristics at the time of charging and discharging, it is possible to perform a more accurate prediction that matches the actual characteristics with the characteristics of the battery.
In addition, by adjusting the load limit level according to the magnitude of the current that is expected to be insufficient for driving critical safety loads, the necessary minimum limit can be applied, thus maintaining comfort. be able to.

  In addition, the load control program according to the present invention accurately obtains the current-voltage characteristics of the battery that change from moment to moment by statistical processing, and calculates the terminal voltage of the battery in a state in which the current required for the important safety system load flows. It is possible to accurately predict and appropriately limit the current that flows to a load that is not an important safety system, and to secure electric power to be supplied to the important safety system while maintaining comfort as much as possible. By easily obtaining the internal resistance value of the battery from the amount of change in current and voltage, the current-voltage characteristic of the battery can be obtained accurately and at high speed. When the current-voltage characteristics at the time of charging and discharging are determined separately, more accurate prediction can be performed. When the load restriction level is adjusted according to the magnitude of the current that is predicted to be insufficient for driving the important safety system load, comfort can be kept high by applying the necessary minimum restriction.

  FIG. 1 is a block diagram showing a configuration of an automobile power supply system according to a load control system 1 of the present invention. In FIG. 1, 2 is an automobile engine, 3 is an engine starter, 4 is a generator such as an alternator, 5 is a battery, 6a to 6f are loads, 7 is a vehicle speed sensor, and 8a to 8c are for detecting the state of the battery. Various sensors.

  The load control system 1 includes a power supply state detection means 10 for obtaining a current-voltage characteristic of the battery 5 using measured values of the various sensors 8a to 8c, and an operation of an important safety system load 6a among the loads 6a to 6f. Load control means 11 for outputting control signals Sb to Sf for limiting the currents Ib to If supplied to the loads 6b to 6f, which are not important safety systems, respectively.

  Since the load control system 1 of the present invention is an automobile system, the engine 2 is an automobile engine including a truck. Needless to say, this can also be applied to other vehicles and ships. The generator 4 is generally an alternator, but other AC or DC generators may be used.

  Further, when the load control system 1 of the present invention is used, it is possible to prevent the current capacity of the battery 5 from changing even if the power required to drive the important safety load 6a increases. However, it goes without saying that the capacity of the battery 5 may be set sufficiently large as the power required for driving the important security load 6a increases.

  The important safety system load 6a is an electric load of a power system and a braking system that play an important role in ensuring safety, such as EPS, electric brake, collision accident prevention system, and air bag system. Then, since especially it demonstrates centering on EPS, the important security system load 6a is also expressed as EPS 6a.

  Note that the EPS 6a shown in the present embodiment is configured to suppress the load applied to the battery 5 by applying the assist limitation step by step when the current I supplied from the battery 5 reaches, for example, 30A, 60A, and 90A. In addition, the operation of the EPS 6a is guaranteed if the voltage is 10V (voltage threshold Vth) or more, but if the terminal voltage V of the battery 5 is less than 10V, the EPS 6a may not be driven. Therefore, in this embodiment, an example is shown in which the assist limit currents Ieps1 to Ieps3 are set to 30A, 60A, and 90A, respectively, and three-stage control is performed.

  The loads 6b to 6f are loads that are not important safety systems. For example, the load 6b is a cooling / heating load such as an air conditioner or an electric heater, the load 6c is a warm air load such as a defogger or a seat heater, and the load 6d is a room. A load of auxiliary lighting systems such as lamps and fog lamps, a load 6e is a load of a light meter such as a headlight, and a load 6f is other loads such as an accessory system and a security system.

  The vehicle speed sensor 7 may measure the vehicle speed using tire rotation or the like, but may obtain a vehicle speed signal from an ECU having a function for obtaining the vehicle speed. In this case, the vehicle speed sensor 7 referred to in the present invention includes an ECU.

  The sensor 8a is a voltage measuring means (hereinafter referred to as a voltmeter) that constantly measures the terminal voltage V of the battery 5 and outputs it as an electrical signal. The sensor 8b detects the current I flowing from the battery 5 to the load 6 side. Current measuring means (hereinafter referred to as an ammeter) that constantly measures and outputs this as an electrical signal. The sensor 8c is a temperature sensor that measures the temperature of the battery 5 and outputs it as an electrical signal. However, the temperature sensor 8c can be omitted.

  In the following description, the output signals of the sensors 8a and 8b are given the same reference numerals as the measured values (physical quantities) I and V of the sensors 8a and 8b, thereby simplifying the description. That is, the voltmeter 8a outputs the voltage value signal V, and the ammeter 8b outputs the current value signal I.

  The power supply state detection means 10 samples the voltage V measured by the voltmeter 8a and the current I measured by the ammeter 8b as needed, and records the relationship between the current I and the voltage V at a plurality of points in the memory. Thus, the current-voltage characteristic table 12 is generated, and the internal resistance value calculating means 13 for obtaining the internal resistance value of the battery 5 that changes every moment by performing statistical processing using the current-voltage characteristic table 12. Is provided. Further, the internal resistance value calculating means 13 obtains the current-voltage characteristic 14 of the battery 5 as the internal resistance value changes.

Here, as shown in FIG. 2, it is assumed that the battery 5 can be expressed by an equivalent circuit using an internal voltage source V0 and an internal resistance R, and the current-voltage characteristic 14 is expressed by a linear expression shown in the following expression (1). To express. The voltage supplied from the internal voltage source V0 is a terminal voltage V when the battery 5 is not loaded (in an open state). In the following description, the magnitude of the voltage supplied from the internal voltage source V0 is also represented by the symbol V0. Also expressed as an internal voltage V0. Similarly, the value of the internal resistance R is also expressed as an internal resistance value R.
V = f (I) = V0−I × R (1)

  In the current-voltage characteristic 14, as shown in FIG. 3, the current I and the voltage V have a substantially linear proportional relationship. Therefore, each point d on which the measured values recorded in the current-voltage characteristic table 12 are plotted substantially overlaps with a straight line indicating the current-voltage characteristic 14. In other words, the power supply state detection means 10 uses the maximum likelihood estimation method such as the least square method to statistically calculate the value of the internal resistance R or the value of the internal voltage V0 to which each point d recorded in the current-voltage characteristic table 12 is best applied. Can be requested. Alternatively, the internal resistance value R of the battery 5 can be obtained by statistical processing and used as the current-voltage characteristic 14.

  Furthermore, the current-voltage characteristic 14 can be a high-order function V = f (I). In any case, by obtaining the current-voltage characteristic 14 using statistical processing of the relationship between the current I and the voltage V, the more accurate current-voltage characteristic 14 can be derived, and the accuracy is improved accordingly.

  The power supply state detection means 10 may perform the statistical processing in consideration of the temperature of the battery 5 obtained from the temperature sensor 8c. Moreover, the power supply state detection means 10 of the present embodiment can also calculate the state of charge SOC of the battery 5 from the value of the voltage V (internal voltage V0) when the discharge current is zero.

  The load control means 11 is connected to the power supply control circuit of each of the loads 6b to 6f using the CAN communication line C, and has a limit level adjusting means 11a for adjusting the current limit level of each of the loads 6b to 6f. It is. Sb to Sf are control signals for current limitation transmitted from the limit level adjusting means 11a to the loads 6b to 6f.

  That is, the load control unit 11 predicts the terminal voltage Vf = f (Ieps) when the current Ieps flows from the battery 5 by substituting the current Ieps into the function f (I) shown in the equation (1). When wearing the voltage threshold value Vth, the current is limited to the loads 6b to 6f.

Alternatively, if only the internal resistance value R of the battery 5 can be calculated by statistical processing, the current Ieps is calculated from the battery 5 using the measured value of the current I and voltage I and the internal resistance value R using the above equation (1). It is also possible to predict the terminal voltage Vf of the battery 5 when flowing. That is, the following equation (2) is obtained.
Vf = f (Ieps) = V0−Ieps × R = V−R (Ieps−I) (2)

  In the present embodiment, both the power supply state detection means 10 and the load control means 11 (the restriction level adjustment means 11a) are configured by a program executed by an arithmetic processing unit constituting the ECU. That is, each program 10 and 11 is the load control program P which comprises the load control system 1 of this invention. In the following description, the means 10, 11, 11a may be expressed as the power state detection program 10, the load control program 11, and the limit level adjustment program 11a.

As in this embodiment, the load control program P is software that can be executed by the ECU, and the means 10 and 11 are configured by the programs 10 and 11, thereby eliminating hardware changes and reducing the manufacturing cost. be able to.

  4 to 7 are diagrams for explaining the operation of the load control program P when the battery 5 is approximated by the equivalent circuit shown in FIG. In particular, paying attention to the internal resistance value R of the battery 5, the terminal voltages Vf1 to Vf3 of the battery 5 when the assist limiting currents Ieps1 to Ieps3 are passed from the voltage V and current I at each time point are obtained, and the loads 6b to 6f are obtained. An operation for limiting the current will be described.

  In FIG. 4, S1 is a step of turning on the ignition key, which is usually operated by the owner of the car.

  S2 is a step of obtaining a measured value of the current I flowing from the battery 5 and a measured value of the terminal voltage V of the battery. The acquisition of the current value I and the voltage value V can be performed by taking in the measurement value signals I and V measured using the voltmeter 8a and the ammeter 8b that always perform measurement. , V are preferably performed simultaneously.

S3 is a step of predicting the terminal voltage Vf1 of the battery 5 when the assist limiting current Ieps1 (that is, 30 A) is supplied from the battery 5. At this time, the current value I, the voltage value V, and the current-voltage characteristic 14 (in the present embodiment, the internal resistance value R) acquired in step S2 are substituted into the equation (2), and the equation (3) is obtained. Thus, the terminal voltage Vf1 can be obtained.
Vf1 = VR (Ieps1-I) (3)

  S4 is a step of determining whether or not the terminal voltage Vf1 obtained in step S3 is less than the voltage threshold Vth at which the assist is stopped. If it is determined that there is a possibility that the assist is stopped, the process jumps to J1 shown in FIG. 5 to perform load control at the maximum load limit level. On the other hand, if it is determined that there is no possibility of stopping the assist even when the assist limit current Ieps1 is supplied, the next step S5 is executed.

S5 is almost the same as step S3, but is a step of predicting the terminal voltage Vf2 when the assist limiting current Ieps2 (ie, 60 A) flows. It is obtained as in equation (4).
Vf2 = VR (Ieps2-I) (4)

  S6 is a step of determining whether or not the voltage Vf2 obtained in step S5 is less than the voltage threshold Vth. If it is determined that there is a possibility that the assist is stopped, the process jumps to J2 shown in FIG. 6 to perform load control at the standard load limit level. On the other hand, if it is determined that there is no possibility of stopping the assist even when the assist limit current Ieps2 is supplied, the next step S7 is executed.

S7 is almost the same as step S5, but predicts the terminal voltage Vf3 when the assist limiting current Ieps3 (that is, 90 A) flows. It is calculated | required like Formula (5).
Vf3 = VR (Ieps3-I) (5)

  S8 is a step of determining whether or not the voltage Vf3 obtained in step S7 is less than the voltage threshold Vth. If it is determined that there is a possibility that the assist is stopped, the process jumps to J3 shown in FIG. 7 and performs load control at the minimum load limit level. On the other hand, if it is determined that there is no possibility of stopping the assist even when the assist limit current Ieps3 is supplied, the next step S9 is executed.

  The operations shown in steps S3 to S8 and FIGS. 5 to 7 show the load current limiting program 11. On the other hand, the operations of step S2 and steps S9 to S14 described below indicate the operations of the power supply state detection program 10.

  S9 is a step of obtaining the change amount ΔIk of the current value I from the battery 5. Here, the subscript is a counter for counting the number of acquisitions of the measured values I and V shown in step S2, and the change amount ΔIk of the current Ik is calculated from the current value I obtained by the current acquisition (kth) ( It can be obtained by subtracting the current value I obtained by the (k-1) th acquisition.

  S10 is a step for obtaining a change amount ΔV of the voltage value V of the battery 5. Here, the amount of change ΔVk of the current Vk can be obtained by subtracting the voltage value V obtained by the previous (k−1) acquisition from the voltage value V obtained by the current (k) acquisition. it can.

  S11 is a step of obtaining the internal resistance value Rk during this period by dividing the voltage change amount ΔV obtained in step S10 by the current change amount ΔI obtained in step S9. That is, step S11 shown in FIG. 1 is a program that constitutes the internal resistance value calculating means 13.

  Here, a method of obtaining the internal resistance value Rk from the changes ΔI and ΔV of the current I and the voltage V performed in the steps S9 to S11 will be described with reference to FIG. As shown in FIG. 8, by subtracting the measurement values Ik and Vk when the kth acquisition is performed by the measurement values at the previous time (k−1), the change amounts ΔIk and ΔVk can be obtained. When the change amounts ΔIk, ΔVk at each time point are plotted with the current change amount ΔI on the horizontal axis and the voltage change amount ΔV on the vertical axis, the points Dk,... Corresponding to the change amounts ΔIk, ΔVk at each time point pass through the origin. It arrange | positions so that it may mount on the two straight lines L substantially.

  Further, the slope of the straight line Lk connecting the origin and the point Dk indicates the internal resistance value Rk obtained based on the k-th change amounts ΔIk and ΔVk. As shown in FIG. 8, the ratio ΔVk / ΔIk of the amount of change at each time point k, k−1,. Therefore, a more accurate internal resistance value R of the battery 5 can be obtained by collecting a plurality of internal resistance values Rk.

  Referring back to FIG. 4 again, S12 is a step of determining whether or not n samples of the internal resistance value Rk have been obtained. If it is determined that n samples have been collected, the process proceeds to the next step S13. If it is determined that n samples have not yet been collected, the process jumps to step S2.

  Step S13 is a step of calculating the internal resistance value of the representative battery 5 of the n internal resistance values R1 to Rn at the time by statistical processing of the n internal resistance values R1 to Rn. Since the internal resistance values R1 to Rn are substantially the same value and do not vary greatly, the statistical calculation for obtaining the representative internal resistance value is the gross average even if it is the total arithmetic average. Alternatively, other calculation methods may be used.

  Step S14 is a step of updating the internal resistance value R used in steps S3, S5, and S7 using the representative internal resistance value obtained in step S13. When step S14 ends, the process jumps to step S2. Again, since it is not considered that the internal resistance value R changes significantly, it can be considered that some abnormality has occurred when the change in the internal resistance value R is large.

  Next, FIG. 5 is executed when the EPS 6a determines that the assist is stopped even in the state where the assist limiting current Ieps1 is supplied in the step S4. Therefore, the operation for performing the load control at the maximum load limiting level will be described. is doing.

  In FIG. 5, S20 is a step of determining whether or not the vehicle speed of the automobile obtained using the company law sensor 7 is less than the vehicle speed threshold value. Here, when it is determined that the vehicle speed is equal to or higher than the vehicle speed threshold value (during low speed travel), step S21 is executed, and when it is determined that the vehicle speed is less than the vehicle speed threshold value (during high speed travel), step S22 is executed.

  S21 is a step of cutting the current flowing through all loads that can be disconnected during low-speed traveling.

  On the other hand, S22 is a step of cutting the current flowing through all loads that can be disconnected during high-speed traveling.

  After the end of steps S21 and S22, the process jumps to step S9 (J4) in FIG. 4 to repeat the loop process.

  Next, FIG. 6 is executed when it is determined in step S6 that the assist limit current Ieps2 is supplied and the EPS 6a is in the assist stop state. That is, the operation for performing load control at the load limit level standard is described.

  In FIG. 6, S25 is a step of determining whether or not the vehicle speed of the automobile is less than the vehicle speed threshold. If it is determined that the vehicle speed is equal to or higher than the vehicle speed threshold, step S26 is executed and the vehicle speed is less than the vehicle speed threshold. If it is determined, step S27 is executed.

  S26 is a step of cutting a current that flows through some of the loads that can be cut off during low speed running, and S27 is a step that cuts the current that flows through some of the loads that can be cut off during high speed running. It is a step. After the steps S26 and S27 are completed, the process jumps to step S9 (J4) in FIG. 4 to repeat the loop process.

  Next, FIG. 7 is executed when it is determined in step S8 that the assist limit current Ieps3 is supplied and the EPS 6a stops the assist. That is, an operation for performing load control at the minimum load limit level is described.

  In FIG. 7, S30 is a step for determining whether or not the vehicle speed of the automobile is less than the vehicle speed threshold. If it is determined that the vehicle speed is greater than or equal to the vehicle speed threshold, step S31 is executed and the vehicle speed is less than the vehicle speed threshold. If it is determined, step S32 is executed.

  S31 is a step of intermittently cutting the current that flows through some of the loads that can be disconnected during low-speed traveling, and S32 is the current that flows through some of the loads that can be disconnected during high-speed traveling. Is a step of intermittently cutting. Then, after the end of steps S31 and S32, the process jumps to step S9 (J4) in FIG. 4 to repeat the loop process.

  Steps S20 to S32 make it possible to adjust the load limit level in three stages, and these programs constitute the limit level adjusting means 11a shown in FIG.

  As in the present embodiment, the internal resistance value R of the battery 5 is calculated as the current-voltage characteristic 14 of the battery 5, and the internal resistance value is calculated and updated as needed, so that extremely simple four arithmetic calculations and statistical processing are performed. It is possible to easily and accurately obtain the terminal voltages Vf1 to Vf3 of the battery 5 in a state in which the currents Ieps1 to Ieps3 for driving the load of the important safety meter are passed by appropriately expressing the state of the battery 5 by calculation that the computer is good at it can.

  However, the present invention is not limited to the current-voltage characteristic 14 being the internal resistance value R.

FIG. 9 is a diagram showing a second embodiment in which a primary expression V = f (I) indicating the relationship between the terminal voltage V and the current I is obtained as the current-voltage characteristic 14. In FIG. 9, the operation of S1 to S8 is almost the same as that of FIG. 1, but the current-voltage characteristic equation 14 for obtaining the predicted voltage Vf from the assist limiting current Ieps in steps S3, S5 and S7 is as shown in the following equation (6). become.
Vf = V0−R × Ieps (6)

  The equation (6) can be obtained by substituting V = V0−R × I for the voltage V in the equations (3) to (5). Therefore, except that the internal voltage V0 is used as a constant, the equation (6) It means essentially the same as 3) to formula (5).

  S15 is a step of determining whether or not the number of samples of current I and voltage V exceeds n. Steps S2 to S2, that is, all measured values of current I and voltage V (samples) until n samples are obtained. ) Is recorded in the current-voltage characteristic table 12 by a predetermined number n.

  S16 is a step of obtaining the current-voltage characteristic formula 14 of the battery 5 using the samples of the current I and the voltage V recorded in the current-voltage characteristic table 12. That is, since there is a relationship as shown in FIG. 3 between the current I and the voltage V, the current-voltage characteristic formula 14 can be obtained by obtaining the values of the internal voltage V0 and the internal resistance R by statistical processing.

  By configuring as in the present embodiment, the internal voltage V0 can always be obtained, so the state of charge SOC of the battery 5 can also be obtained from the value of the internal voltage V0.

  FIG. 10 shows an equivalent circuit of the battery 5 paying attention to the fact that the current-voltage characteristics of the battery 5 are different between charging and discharging. In FIG. 10, the battery 5 has an internal voltage source V0, an internal resistance Rd during discharging, an internal resistance Rc during charging, and an equivalent circuit using ideal diodes Dd and Dc.

The current-voltage characteristics of the battery 5 shown in FIG. 11 are different when the current I is positive (during discharging) and negative (during charging). The current-voltage characteristic equation fc (I during charging and discharging is different. ) And fd (I) are as shown in the following equations (7) and (8), respectively.
V = fc (I) = V0−Rc (I) (7)
V = fd (I) = V0−Rd (I) (8)

  It should be noted that the formulas (7) and (8) are merely examples of the current-voltage characteristic formulas fc (I) and fd (I) of the present invention, and do not limit the present invention. Nor. That is, the terminal voltage V0 at the time of no load in the current-voltage characteristic formulas fc (I) and fd (I) is set to a different value, and the current-voltage characteristic formulas at the time of charging and discharging are higher than the second order. Various modifications are possible, such as using relational expressions, logarithms, trigonometric functions, and the like.

FIG. 12 is a diagram showing a third embodiment in which the current-voltage characteristics 14 are obtained separately by charging and discharging current-voltage characteristics. In FIG. 12, the operations of S1 to S15 are almost the same as those in FIG. 1, but the current-voltage characteristic equation 14 for obtaining the predicted voltage Vf from the assist limiting current Ieps in steps S3, S5, and S7 is the current-voltage characteristic at the time of discharging. Expression (9) is obtained by substituting the assist limiting current Ieps into Expression (8).
Vf = V0−Rd × Ieps (9)

Further, when the expression (9) is expressed using the current voltages V and I without using the internal voltage V0, the expression (10) is obtained.
Vf = V−Rd (Ieps−I) (10)

  S17 is a step of obtaining the current-voltage characteristic formula 14 of the battery 5 using the samples of the current I and the voltage V recorded in the current-voltage characteristic table 12. The present embodiment is different from the second embodiment in that the current-voltage characteristic equation is obtained separately for the magnitude (positive / negative) of the current I. That is, three constants V0, Rc, and Rd are obtained in the signal processing in step S17.

  By separately determining the current-voltage characteristics at the time of charging and discharging as in this embodiment, the state of the battery 5 can be determined more accurately, and the predicted voltage Vf can be determined with high accuracy, and the minimum necessary Limit load limit.

  In each of the above-described embodiments, the current voltage characteristic 14 is an example of a linear function or a proportionality constant (internal resistance value R), but the present invention is not limited to this point. It goes without saying that various functions V = f (I) that can more accurately represent the state of the battery 5 can be used as the current-voltage characteristic 14. Also in this case, by obtaining each constant in the function V = f (I) by statistical processing of the current I and the voltage V measured at any time, an accurate current-voltage characteristic 14 is obtained by calculation that the computer is good at. be able to.

It is a block diagram which shows the structure of the load control system which concerns on the Example of this invention. It is a figure which shows the internal equivalent circuit of a battery. It is a figure which shows the example of the current voltage characteristic of a battery. It is a figure which shows the example of the load control program of 1st Example. It is a figure which shows another part of the said load control program. It is a figure which shows another part of the said load control program. It is a figure which shows another part of the said load control program. It is a figure explaining operation | movement of the load control program of 1st Example. It is a figure which shows the example of the load control program of 2nd Example. It is a figure which shows another example of the internal equivalent circuit of a battery. It is a figure which shows the characteristic of the battery shown in FIG. It is a figure which shows the example of the load control program of 3rd Example. It is a figure which shows the structure of the conventional power supply circuit.

Explanation of symbols

1 Load Control System 5 Battery 6a Important Safety Load (EPS)
6b-6f Non-critical safety load 10 Power supply state detection means (power supply state detection program)
11 Load control means (load control program)
11a Limit level adjusting means 13 Internal resistance value calculating means (internal resistance value calculating program)
14 Current-voltage characteristics P Load control program

Claims (8)

Voltage measuring means for measuring the terminal voltage of the battery mounted on the vehicle as needed;
Current measuring means for measuring current flowing from the battery to the load side as needed;
A power supply state detection means for determining current and voltage characteristics of the battery at any time by performing statistical processing of current and voltage measured at any time;
A load control means for predicting a terminal voltage that drops with an operation of a load of an important safety system by using the current-voltage characteristics, and for limiting a current flowing to a load that is not an important safety system based on the predicted terminal voltage; A load control system comprising: The current-voltage characteristic is an internal resistance value of the battery,
The power supply state detection means calculates and updates the internal resistance value at each point in time from the current and voltage variation measured at any time, and
2. The load control system according to claim 1, wherein the load control means predicts a terminal voltage in a state in which a current for driving a load of an important safety system flows from an internal resistance value and measured values of voltage and current at each time point.   3. The load control system according to claim 1, wherein the power supply state detection unit separately obtains a current-voltage characteristic during charging and a current-voltage characteristic during discharging.   The load according to any one of claims 1 to 3, wherein the load control means adjusts a load limit level according to a magnitude of a current predicted to be insufficient for driving an important safety system load. Control system. By being executed by an arithmetic processing unit of a load control system comprising voltage measuring means for measuring terminal voltage of a battery mounted on a vehicle as needed and current measuring means for measuring current flowing from the battery to the load side as needed, A load control program for monitoring voltage and current measurement values measured at any time by the voltage measurement means and the current measurement means, and ensuring power necessary for the operation of the load of the important safety system,
A power supply state detection program for determining the current-voltage characteristics of the battery at any time by performing statistical processing of the current and voltage measured at any time;
A load current limiting program that predicts a terminal voltage that drops with the operation of an important safety system load by using the current-voltage characteristics, and that limits a current that flows to a load that is not an important safety system based on the predicted terminal voltage And a load control program. The power supply state detection program has an internal resistance value calculation program that calculates and updates the internal resistance value at each time point from the current and voltage change amounts measured at any time,
6. The load control program according to claim 5, wherein the load current limiting program predicts a terminal voltage in a state where a predetermined current is passed through an important safety system load using the internal resistance value updated as needed. The power supply state detection program is obtained by dividing the current-voltage characteristics at the time of charging and the current-voltage characteristics at the time of discharging,
The load according to claim 5 or 6, wherein the load current limiting program predicts a terminal voltage in a state in which a predetermined current is passed through an important safety system load using the current-voltage characteristics at the time of discharging. Control program.   The load current limit program adjusts a load limit level according to a magnitude of a current predicted to be insufficient for driving a load of an important safety system. Load control program.

Images