JP2009229404A - Current value measuring method and current value measuring device of battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current value measuring method and a current value measuring device of a battery for correcting a measurement error of a battery current value measured by a current sensor by utilizing a voltage measuring device, in a battery system having the voltage measuring device including the current sensor. <P>SOLUTION: This current value measuring device of the battery provided in the battery system 1 equipped with a high-voltage battery 10, a main current sensor 40 for measuring a charge/discharge current of the battery, a series connection comprising a current sensor 52 and a resistance circuit 22, and the voltage measuring device 50 for detecting a voltage of the battery based on a measured value by the current sensor 52, includes a resistance value changing means for changing a resistance value of the resistance circuit 22, a circuit switching means for switching connection to form a closed circuit for correction including the main current sensor 40, and a controller 30 for correcting a measured value of the charge/discharge current measured by the main current sensor 40. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery current value measuring method and a current value measuring apparatus, and particularly, as in a hybrid vehicle, a current sensor and a current sensor different from the current sensor are incorporated between a battery and an electric load. The present invention relates to a battery current value measuring method and a current value measuring apparatus applied to a battery system including the voltage measuring apparatus.

  Conventionally, a vehicle is provided with a current sensor that measures the charging / discharging current of an on-vehicle battery. A measurement value by the current sensor includes a measurement error, and a technique for correcting this measurement error has been proposed ( For example, see Patent Document 1). In the current detection device described in Patent Literature 1, a measurement error is calculated from a difference between an actual value measured by a current sensor and a theoretical value, and a correction amount of the actual value is determined based on the measurement error.

JP-A-2005-37286

When performing the above method, for example, it is desirable to increase the accuracy of correction by providing a plurality of current sensors and averaging the correction amounts obtained from them. However, there is a problem that simply increasing the number of current sensors leads to an increase in the number of parts and cost.
On the other hand, a vehicle battery system is provided with a voltage measuring device for detecting the voltage of the battery. In particular, in a battery system including a high voltage battery such as a hybrid vehicle, the voltage measuring device usually incorporates a current sensor. It has a configuration.

  The present invention has been made to solve the above problems, and in a battery system having a voltage measuring device including a current sensor, the battery current value measured by the current sensor is measured using the voltage measuring device. An object of the present invention is to provide a battery current value measuring method and a current value measuring apparatus that correct errors.

  In order to achieve the above object, the present invention provides a battery that is connected to an electrical load for charging and discharging, a first current sensor that measures charge / discharge current input to and output from the battery, a second current sensor, and a resistor. A battery current in a battery system comprising: a series connection comprising a circuit; and a voltage detection device that detects a voltage of the battery based on a measurement value of a current flowing through a closed circuit formed by the battery and the series connection by a second current sensor. A method for measuring a value, wherein a circuit switching step for forming a correction closed circuit including a battery connected in series with a first current sensor, and a correction closed circuit based on measurement by the first current sensor and the second current sensor. The measurement value acquisition step for acquiring the current value of the flowing current, the resistance value change step for changing the resistance value of the resistor circuit, and the measurement value after the resistance value change step A step of repeating the obtaining step, a correction amount setting step for setting a correction amount for correcting the current value by the first current sensor based on the plurality of acquired current values, and a correction amount set by the correction amount setting step And a correction step of correcting the current value of the charge / discharge current measured by the first current sensor.

  According to the present invention configured as described above, in order to set the correction amount of the measurement value of the first current sensor, the correction closed circuit is provided so that the first current sensor and the second current sensor can measure the same current. Further, the resistance value of the resistor circuit forming a part of the correction closed circuit is changed. Thereby, the measurement current can be changed to a different magnitude. Therefore, it is possible to acquire the measured current values of the first current sensor and the second current sensor for a plurality of measured currents. Accordingly, the correction amount can be set so that the current value obtained by the first current sensor matches the current value obtained by the second current sensor, for example. That is, the gain error and the offset error due to the first current sensor can be corrected. Thereby, the measurement precision of a battery charging / discharging electric current value can be improved without adding a current sensor newly by utilizing existing components effectively.

  In the present invention, preferably, the measurement value acquisition step is performed in a state where the connection between the battery and the electric load is disconnected. According to the present invention configured as described above, the measured currents of the first current sensor and the second current sensor can be matched more reliably.

  Preferably, in the present invention, the second current sensor includes an annular magnetic core having a through hole, a Hall element that detects a magnetic flux formed by a measurement current passing through the through hole of the magnetic core, and a magnetic element. A winding that is wound around the body core, and a current supply device that supplies current to the winding so as to cancel the magnetic flux formed in the magnetic core by the measurement current based on the detection value by the Hall element. The voltage detection device is configured to be able to detect the voltage of the battery based on the current supplied by the current supply device. In the correction amount setting step, the current value by the first current sensor matches the current value by the second current sensor. Alternatively, the correction amount is set so as to approach. According to the present invention configured as described above, when the second current sensor is a magnetic balance type current sensor and the first current sensor is not a magnetic balance type, for example, a magnetic proportional type current sensor, measurement is performed. By setting the correction amount so as to match the current value of the second current sensor with high accuracy, the measurement error of the current value of the first current sensor is improved, and as a result, the measurement accuracy can be improved.

  Moreover, in order to perform the said method, this invention connects the battery which charges / discharges connected to an electric load, the 1st current sensor which measures the charging / discharging electric current input / output to this battery, and an electric load and a battery. A closed circuit formed by a series connection of a second current sensor and a resistance circuit, one end connected to the positive terminal of the battery and the other end connected to the negative terminal of the battery, and a series connection with the battery. A voltage detection circuit for detecting a voltage of the battery based on a measurement value of a current flowing through the second current sensor, and a battery current value measurement device provided in the battery system, wherein the resistance value of the resistance circuit is A resistance value changing means for changing, a circuit switching means for switching the connection so as to form a correction closed circuit composed of a series connection and a battery with the first current sensor, and a first current sensor. Correction means for correcting a measured value of the measured charge / discharge current, and the correction means in each of the correction closed circuits having different resistance values by changing the resistance value of the resistance circuit by the resistance value changing means. A current value based on the measurement by the first current sensor and the second current sensor is acquired, and a correction amount for correcting the current value by the first current sensor is set based on the current value by the second current sensor. Based on this, the current value by the first current sensor is corrected.

  In the present invention, it is preferable that the battery system includes a cutoff unit that disconnects the connection between the battery and the electric load, and the correction unit includes the first current in a state where the connection between the battery and the electrical load is disconnected by the cutoff unit. The current value in the correction closed circuit based on the measurement by the sensor and the second current sensor is acquired.

  Preferably, in the present invention, the second current sensor includes an annular magnetic core having a through hole, a Hall element that detects a magnetic flux formed by a measurement current passing through the through hole of the magnetic core, and a magnetic element. A winding that is wound around the body core, and a current supply device that supplies current to the winding so as to cancel the magnetic flux formed in the magnetic core by the measurement current based on the detection value by the Hall element. The voltage detection device is configured to be able to detect the voltage of the battery based on the current supplied by the current supply device, and the correction means matches or approaches the current value of the first current sensor to the current value of the second current sensor. Set the correction amount as follows.

  According to the battery current value measuring method and the current value measuring apparatus of the present invention, in the battery system having the voltage measuring device including the current sensor, the battery current value measured by the current sensor is measured using the voltage measuring device. Measurement error can be corrected.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 8.
1 is an explanatory diagram of a battery system according to an embodiment of the present invention, FIG. 2 is a functional block diagram of a controller, FIG. 3 is an explanatory diagram of a main current sensor, FIG. 4 is an explanatory diagram of a voltage measuring device, and FIG. FIG. 6 is an explanatory diagram of the error, FIG. 6 is an explanatory diagram of the correction amount of the current sensor, FIG. 7 is a flowchart of the correction control process, and FIG. 8 is an explanatory diagram of the correction amount according to the modification.

In the present embodiment, an example in which the battery current value measuring method and apparatus of the present invention are applied to a battery system of a vehicle such as a hybrid vehicle or an electric vehicle will be described.
As shown in FIG. 1, the battery system 1 of this embodiment includes a high voltage battery 10 that supplies power to an electric load 2 of a vehicle, an electric circuit 20 that connects the high voltage battery 10 and the electric load 2, and controls these. The controller 30 is provided.
In the present embodiment, the current value measuring device is integrated in the battery system 1, and the controller 30 and the resistance circuit 22, the connection switching circuit 24, etc. in the electric circuit 20 correspond to the current value measuring device.

  The electric load 2 includes an inverter, a drive motor, and the like, and the high voltage battery 10 supplies DC power to the inverter and the like. The inverter converts the DC power of the high-voltage battery 10 into AC power, and drives a drive motor that generates vehicle driving force by the AC power. The high voltage battery 10 is charged by a charging current from the electric load 2 supplied via the electric circuit 20.

The electric circuit 20 includes a pair of main relays 21 a and 21 b, a main current sensor 40, a voltage measuring device (voltage sensor) 50, a resistance circuit 22, and a connection switching circuit 24.
The pair of main relays 21 a and 21 b are switches that connect the electric circuit 20 to the electric load 2. Specifically, the main relays 21a and 21b are arranged between the high voltage battery 10 and the electric load 2, and the wiring 28a connecting the positive terminal of the high voltage battery 10 and the electric load 2 respectively, the negative terminal and the electric relay. The wiring 28b connecting the load 2 is disposed. The main relays 21 a and 21 b are controlled by the controller 30 and are configured to connect or disconnect between the electric load 2 and the high voltage battery 10.

  The main current sensor 40 is disposed on the wiring 28b between the main relay 21b and the electric load 2, measures the charge / discharge current that is the input / output current of the high-voltage battery 10, and measures the measured current value (measured value). ) Im is output to the controller 30.

  The voltage measuring device 50 is arranged in parallel with the electric load 2 so as to connect the positive terminal and the negative terminal of the high-voltage battery 10. The voltage measuring device 50 is a current-voltage transducer, and is configured to measure the voltage of the high voltage battery 10 and output the measured voltage value Vt to the controller 30. As will be described later, the voltage measurement device 50 includes a non-contact type current sensor 52 and a voltage detection circuit 56, and converts the current value It measured by the current sensor 52 into a voltage value Vt by the voltage detection circuit 56. The voltage value Vt is output. In the normal mode, that is, the battery voltage measurement mode, the voltage value Vt represents the voltage between both terminals of the high voltage battery 10.

  The resistance circuit 22 is connected in series with the voltage measuring device 50, and this series connection is connected to the high voltage battery 10 in parallel with the electric load 2. Specifically, the resistance circuit 22 connects the voltage measuring device 50 and the wiring 28a, and one end of the resistance circuit 22 is connected to the wiring 28a between the positive terminal of the high voltage battery 10 and the main relay 21a. The other end is connected to the voltage measuring device 50 (actually, the wiring 26a to which the voltage measuring device 50 is attached).

  The resistance circuit 22 includes two resistors 22a and 22b and a connection switch 22c. The resistor 22a is connected in parallel with the resistor 22b via the connection switch 22c. The connection switch 22c is ON / OFF controlled by the controller 30 and is OFF (open state) in the normal battery voltage measurement mode, and is temporarily turned ON (closed state) from OFF during the correction mode described in detail below, and then turned OFF again. Controlled to return. The resistance circuit 22 and the controller 30 correspond to resistance value changing means.

The connection switching circuit 24 is disposed so as to connect the voltage measuring device 50 and the wiring 28b. The connection switching circuit 24 includes a connection switching switch 25 (hereinafter referred to as “switch 25”), a terminal 25a of the switch 25, a wiring 26a extending to the voltage measuring device 50, and a terminal 25b of the switch 25. Wiring 26b connected to the wiring 28b between the main current sensor 40 and the wiring 26b connecting the terminal 25c of the switch 25 to the wiring 28b between the main current sensor 40 and the main relay 21b.
The wiring 26a is connected to the resistor 22a of the resistor circuit 22 and the connection switch 22c through the voltage measuring device 50.

The switch 25 is controlled by the controller 30, and is controlled so that the terminal 25a and the terminal 25b are connected in the normal battery voltage measurement mode, and the terminal 25a and the terminal 25c are connected in the correction mode.
Therefore, in the normal battery voltage measurement mode, the high voltage battery 10, the wiring 28a, the resistor 22a of the resistance circuit 22, the voltage measuring device 50, the wiring 26a of the connection switching circuit 24, the switch 25, the wiring 26b, and the wiring 28b are included. A closed circuit is formed, and the voltage measuring device 50 outputs a voltage value Vt based on the current flowing through the closed circuit.
The connection switching circuit 24 and the controller 30 correspond to circuit switching means.

  The controller 30 performs SOC control of the high voltage battery 10, power supply control from the high voltage battery 10 to the electric load 2, operation control of the electric load 2, charge control of the high voltage battery 10 by regenerative power from the electric load 2 side, and the like. It is configured to perform. Furthermore, the controller 30 of the present embodiment is configured to perform control for correcting the measured current value Im of the main current sensor 40 in the SOC control. This correction control is configured to correct the measured current value Im of the main current sensor 40 based on the current value It measured by the current sensor 52 incorporated in the voltage measuring device 50.

The controller 30 of the present embodiment is configured by a microcomputer having a CPU, a memory, and the like. In FIG. 2, only a functional block diagram for performing the above-described correction control is shown.
As shown in FIG. 2, the controller 30 includes a correction unit 31, a correction amount setting unit 32, a circuit switching control unit 33, a correction amount setting instruction unit 34, and a conversion unit 35.

  The correction amount setting unit 32 sets a correction amount D for correcting the current value Im. The correction unit 31 corrects the current value Im using the correction amount D set by the correction amount setting unit 32, and outputs a corrected current value Imc. The correction amount setting instruction unit 34 outputs an instruction to start setting of the correction amount D when a vehicle condition capable of setting the correction amount D is satisfied. The circuit switching control unit 33 performs on / off control of the resistance circuit 22, the connection switching circuit 24, and the main relays 21a and 21b when setting the correction amount.

In addition, the conversion unit 35 converts the voltage value Vt, which is the output of the voltage measurement device 50, into a current value It that represents the magnitude of the current measured by the voltage measurement device 50 (current flowing through the wiring 26a).
As described above, in the correction control, the measurement current value Im of the main current sensor 40 is corrected based on the current value It measured by the current sensor 52 built in the voltage measurement device 50. However, the voltage measurement device 50 of the present embodiment is corrected. Is configured to output only the voltage value Vt according to the measurement current. For this reason, the conversion unit 35 performs processing for returning the voltage value Vt to the measurement value It by the current sensor 52 again. In this specification, the current value based on the measurement by the current sensor or the measured value is a signal value directly output from the current sensor and a signal value that represents the current value again after being converted into a voltage value as described above. Includes what was returned.

  In the present embodiment, the voltage measuring device 50 is configured to output only the voltage value Vt. However, the present invention is not limited to this, and the voltage measuring device 50 outputs both the voltage value Vt and the current value It. You may comprise as follows. In the case of such a configuration, the conversion unit 35 need not be provided, and the current value It may be directly input to the controller 30 from the voltage measuring device 50 (current sensor 52).

Next, the configuration of the main current sensor 40 will be described.
The main current sensor 40 of this embodiment is a non-contact type magnetic proportional current sensor. The main current sensor 40 includes a magnetic core 40a, a Hall element 40b, and an amplifier circuit 40c.
The magnetic core 40a is a member made of an annular magnetic material having a through-hole that penetrates the wiring 28b. The magnetic core 40a is provided with a notch in a part of the circumferential direction thereof, and has a substantially C shape in plan view. . The hall element 40b has a drive current terminal and an output terminal, and is disposed in a notch portion of the magnetic core 40a. The amplifier circuit 40 c is connected to the output terminal of the Hall element 40 b, and is configured to amplify the voltage output from the output terminal and output it to the controller 30.

  In the main current sensor 40, when a measurement current flows through the wiring 28b, a magnetic flux proportional to the magnitude of the measurement current is generated in the magnetic core 40a. A driving current is supplied to the hall element 40b through a driving current terminal, and when the magnetic flux generated in the magnetic core 40a passes through the hall element 40b, the hall element 40b outputs a voltage corresponding to the magnitude of the magnetic flux. Output from the terminal. The amplifier circuit 40c amplifies the voltage output from the output terminal, and outputs an output voltage corresponding to the magnitude of the measurement current as a current value Im.

Next, the configuration of the voltage measuring device 50 will be described.
The voltage measuring device 50 of this embodiment includes a non-contact type magnetic balance type current sensor 52 and a voltage detection circuit 56 that converts an output value It of the current sensor 52 into a voltage value Vt.
The current sensor 52 of this embodiment includes a magnetic core 52a, a Hall element 52b, an amplifier circuit 52c, a current buffer 52d, a winding 52e wound around the magnetic core 52a, and a voltage follower 52f. ing. The amplifier circuit 52c and the current buffer 52d correspond to the current supply device of the present invention.

The configuration of the magnetic core 52a, the Hall element 52b, and the amplifier circuit 52c is the same as that of the magnetic core 40a, the Hall element 40b, and the amplifier circuit 40c of the main current sensor 40. The wiring 26a is passed through the through hole of the magnetic core 52a.
The amplifier circuit 52c amplifies the output voltage appearing at the output terminal of the Hall element 52b and outputs it to the current buffer 52d. The current buffer 52d supplies a cancel current corresponding to the output voltage to the winding 52e.

  The winding 52e generates a magnetic flux in the magnetic core 52a by the cancel current supplied from the current buffer 52d. This magnetic flux is a canceling magnetic flux in a direction that cancels out the magnetic flux generated in the magnetic core 52a by the measurement current flowing through the wiring 26a. The winding 52e is wound around the magnetic core 52a so as to generate such a canceling magnetic flux.

The current buffer 52d has a cancel current applied to the winding 52e by feedback control so that the magnetic flux passing through the magnetic core 52a becomes a zero value by the cancel magnetic flux, that is, the output voltage of the Hall element 52b becomes a zero value. Supply.
This canceling current is input to the voltage follower 52f via the resistor Ra connected in parallel, and the voltage follower 52f outputs a current value It representing the magnitude of the measurement current.

The current value It that is the output of the voltage follower 52 f is input to the voltage detection circuit 56. In the voltage detection circuit 56, the current value It is amplified and converted to a voltage value Vt representing the voltage of the high voltage battery 10, and the voltage detection circuit 56 outputs the voltage value Vt to the controller 30.
Note that the voltage follower 52f and the voltage detection circuit 56 may be integrally formed to output the voltage value Vt. In this case, the current value It may not appear. However, as in the present embodiment, the conversion unit 35 of the controller 30 calculates the current value It from the voltage value Vt in consideration of the theoretical amplification factor. Can do.

  In the present embodiment, the voltage measuring device 50 outputs the voltage value Vt to the converter 35 in the form of a voltage. However, the present invention is not limited to this, and the voltage measuring device 50 may be configured to output a cancel current to the controller 30. Good. In this case, the voltage follower 52f and the voltage detection circuit 56 are provided on the controller 30 side, and the controller 30 converts the cancel current into a voltage value Vt and a current value It in a voltage format.

  As described above, in the present embodiment, the main current sensor 40 is a magnetic proportional type current sensor, the current sensor 52 is a magnetic balance type current sensor, and the measurement methods of both are different. In general, a magnetic proportional current sensor includes an error due to the hysteresis characteristic of the magnetic core, whereas a magnetic balance current sensor does not include an error due to the hysteresis characteristic. For this reason, the current sensor 52 is superior to the main current sensor 40 in measurement accuracy. For this reason, in this embodiment, the correction is performed so that the measurement value of the main current sensor 40 matches the measurement value of the current sensor 52, as described in the following correction control.

Next, the principle of correction control according to this embodiment will be described.
As described above, since the current sensor 52 is superior in measurement accuracy to the main current sensor 40, in the present embodiment, the current value It by the current sensor 52 is set to a true value, and the current of the main current sensor 40 is set to this value. The correction amount D is determined so that correction for matching the value Im is possible.
FIG. 5 shows the relationship between the current value It and the current value Im when the current sensor 52 and the main current sensor 40 measure the same measurement current. In FIG. 5, the horizontal axis represents the current value It, and the vertical axis represents the current value Im.

A broken line B indicates a relationship between the current value Im when the current value Im does not include a measurement error, that is, when the current value It matches the current value Im. In this case, the relationship between the two is expressed as Im = It.
On the other hand, a solid line A indicates a relationship between the current value Im and the measurement error E when the current value Im includes the measurement error E. In this embodiment, the relationship between the two is expressed by the following linear function.
Im = a · It + b (Formula 1)

This measurement error E is given by the following equation from Equation 1.
E = It−Im = (1 / a−1) · Im−b / a (Formula 2)
Equation 2 indicates that the measurement error E can be calculated from the current value Im if the correction constants a and b are known. That is, the measurement error E can be expressed as a function of the current value Im. FIG. 6 shows the relationship between the current value Im and the measurement error E.

Further, from Equation 2, the current value It is given by the following equation.
It = Im + E (Formula 3)
In this embodiment, as described below, the correction current value Imc is calculated by adding the correction amount D to the current value Im (Imc = Im + D).
In this case, if the correction amount D is equal to the measurement error E (D = E), Imc = It can be obtained.

As shown in FIG. 5, if a combination of a plurality of current values It and Im is acquired with different measurement currents, Equation 1 represented by the solid line A can be obtained. That is, when the combination of current values (Ita, Ima) and (Itb, Imb) is acquired, the correction constants a and b are
a = (Imb−Ima) / (Itb−Ita) (Formula 4)
b = (Ima · Itb−Imb · Ita) / (Itb−Ita) (Formula 5)
Given in.
Note that FIG. 5 shows the case where the number of combinations of the current values It and Im is two. However, the present invention is not limited to this, and three or more combinations may be acquired.

Next, the correction control processing procedure of the controller 30 will be described with reference to FIG.
The controller 30 is configured to repeatedly perform the process of FIG. 7 until the power is turned off after the power is turned on.
First, the controller 30 (correction amount setting instruction unit 34) determines whether or not a condition for setting the correction amount is satisfied (step S1). The conditions for setting the correction amount are when the vehicle is parked (for example, when parking brake is turned on) or when the charge / discharge current of the high voltage battery 10 continuously becomes zero (current value). Im is continuously zero value), in the state diagnosis mode of the high voltage battery 10, and the power supply from the high voltage battery 10 to the electric load 2 and the regenerative power from the electric load 2 side to the high voltage battery 10. This corresponds to the case where there is no supply.

When it is not determined that the correction amount setting start condition is satisfied (step S1; No), the controller 30 ends the process and performs step S1 again after a predetermined time.
On the other hand, when it is determined that the correction amount setting start condition is satisfied (step S1; Yes), the controller 30 (circuit switching control unit 33) operates the main relays 21a and 21b to be in the open state. Thereby, the high voltage battery 10 is disconnected from the electric load 2. Thereby, as will be described below, when the connection switching circuit 24 is switched, the main current sensor 40 and the current sensor 52 can measure the same measurement current.

  Next, the controller 30 (circuit switching control unit 33) changes the connection switching circuit 24 from the normal mode to the correction mode (step S3). In this process, the controller 30 switches the switch 25 to the terminal 25c and connects the terminal 25a and the terminal 25c. As a result, in the correction mode, the high voltage battery 10, the wiring 28a, the resistance circuit 22, the voltage measuring device 50, the wiring 26a of the connection switching circuit 24, the switch 25, the wiring 26c, the main current sensor 40, and the wiring 28b for correction are closed. A circuit is formed.

After the correction closed circuit is formed, the controller 30 (correction amount setting unit 32) acquires the current value It from the current sensor 52 and the current value Im from the main current sensor 40 (step S4). In this process, the conversion unit 35 performs a process of returning the voltage value Vt received from the voltage measuring device 50 to the current value It by the current sensor 52, and outputs the current value It to the correction amount setting unit 32. Further, the correction amount setting unit 32 receives the current value Im from the main current sensor 40. The correction amount setting unit 32 stores the acquired current values It and Im in the memory as current values Ita and Ima, respectively.
In this process, the connection switch 22c of the resistance circuit 22 is off (open state).

Next, the controller 30 (correction amount setting unit 32) compares the current values Ita and Ima stored in the memory, and determines whether or not the difference between them is within a predetermined threshold range (step S5).
When the current values Ita and Ima are substantially equal within the predetermined threshold range (step S5; Yes), the measurement error included in the measurement value by the main current sensor 40 is very small, so the controller 30 corrects the correction constant a that determines the correction amount D. , B are reset to zero values, the electric circuit 20 is returned to the normal mode (step S10), and the process is terminated.

  On the other hand, when the current values Ita and Ima are different from each other beyond the predetermined threshold range (step S5; No), the controller 30 (circuit switching control unit 33) operates (turns on) the connection switch 22c of the resistance circuit 22 to be in the closed state. (Step S6). As a result, the resistance value of the resistance circuit 22 changes compared to before the connection switch 22c operates (when the connection switch 22c is off), and the measurement current flowing through the correction closed circuit also changes.

  After switching the connection switch 22c of the resistor circuit 22, the controller 30 (correction amount setting unit 32) again calculates the current value It by the current sensor 52 and the current value Im by the main current sensor 40, similarly to the process of step S4. Obtain (step S7). The correction amount setting unit 32 stores the acquired current values It and Im in the memory as current values Itb and Imb, respectively.

  Next, the controller 30 (correction amount setting unit 32) sets a correction amount for the current value Im (step S8). In this process, first, the correction amount setting unit 32 calculates the correction constants a and b from the above equations 4 and 5 based on the current value pairs (Ita, Ima) and (Itb, Imb) stored in the memory. Is stored in the memory of the correction unit 31. Next, the correction amount setting unit 32 sets the correction amount D to the amount given by Equation 2 from the correction constants a and b stored in the memory, and stores the correction amount D in the correction unit 31. Therefore, in the present embodiment, the correction amount D is given as a function of the current value Im.

  In the present embodiment, the correction amount D is set from two sets of current values Im and It, but the present invention is not limited to this, and the correction amount D may be set from three or more sets. For example, in order to obtain three sets, a connection switch and a resistor are further added to the resistor circuit 22 so that the resistance value can be changed in three ways, and the current values Im and It can be obtained for each of the three resistance values. That's fine.

Moreover, in order to acquire three sets, you may add the connection switch for interrupting | blocking the connection of a correction | amendment closed circuit. For example, a connection switch that cuts off the series connection with the voltage measuring device 50 may be added to the resistance circuit 22. In this case, a set of current values Im and It in a state where there is no measurement current can be acquired.
When three or more sets are acquired in this way, an approximate expression can be obtained from these three or more sets by various statistical methods. The approximate expression is not limited to the linear function described above, but may be a high-order function.

  After setting the correction amount, the controller 30 (circuit switching control unit 33) performs a process of returning the connection switch 22c of the resistance circuit 22 to the original open state (step S9). Further, the controller 30 (circuit switching control unit 33) operates the switch 25 of the connection switching circuit 24 to perform the process of returning the terminal 25a and the terminal 25c to the connected state (step S10), and ends the process. The controller 30 operates the main relays 21a and 21b in a closed state as necessary.

  As described above, in the correction control performed in the correction mode, the controller 30 can set the correction amount D. In the normal mode, the controller 30 (correction unit 31) calculates the corrected current value Imc by correcting the current value Im received from the main current sensor 40 with the correction amount D, and uses the corrected current value Imc for SOC control or the like. Use.

  Thus, in the present embodiment, the correction amount D is calculated using the current sensor 52 incorporated in the voltage measuring device 50 without adding the current sensor to the battery system 1 in addition to the main current sensor 40. The measurement error included in the measurement value of the main current sensor 40 can be calculated and corrected.

In the above embodiment, the correction amount D is set equal to the measurement error E (D = E), but the present invention is not limited to this and may be set as follows.
FIG. 8 is a graph similar to FIG. 6, but a straight line indicating the correction amount D is added. In FIG. 8, D = E / 2 is set. That is, the correction unit 31 corrects the current value Im with a value half the measurement error E (Imc = Im + E / 2). In other words, the correction current value Imc corresponds to an average value of the current value Im and a current value It corresponding to the current value Im in calculation.

  Therefore, by repeating the correction mode and the normal mode a plurality of times, the current value Im gradually approaches the current value It. By correcting in this way, it is possible to prevent the difference between the current value Im or the corrected current value Imc before and after the correction mode from becoming too large when the normal mode is returned from the correction mode.

It is explanatory drawing of the battery system by embodiment of this invention. It is a functional block diagram of the controller by embodiment of this invention. It is explanatory drawing of the main current sensor by embodiment of this invention. It is explanatory drawing of the voltage measurement apparatus by embodiment of this invention. It is explanatory drawing of the measurement error of the current sensor by embodiment of this invention. It is explanatory drawing of the corrected amount of the current sensor by embodiment of this invention. It is a flowchart of the correction control process by embodiment of this invention. It is explanatory drawing of the corrected amount concerning the modification by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery system 2 Electric load 10 High voltage battery 20 Electric circuit 21a, 21b Main relay (cut-off means)
22 resistor circuit 22a, 22b resistor 22c connection switch 24 connection switch circuit 25 connection switch 25a, 25b, 25c terminal 26a, 26b, 26c wiring 28a, 28b wiring 30 controller (correction means)
31 correction unit 32 correction amount setting unit 33 circuit switching control unit control unit 34 correction amount setting instruction unit 35 conversion unit 40 main current sensor (first current sensor)
50 Voltage measuring device 52 Current sensor (second current sensor)
56 Voltage detection circuit

Claims (6)

A battery connected to an electrical load for charging and discharging;
A first current sensor for measuring a charge / discharge current input to and output from the battery;
A series connection of a second current sensor and a resistance circuit;
A battery current value measurement method in a battery system, comprising: a voltage detection device that detects a voltage of the battery based on a measurement value by the second current sensor of a current flowing through a closed circuit formed by the series connection with the battery. Because
A circuit switching step for forming a closed circuit for correction comprising the first current sensor, the series connection and the battery;
A measurement value acquisition step of acquiring a current value of a current flowing through the correction closed circuit based on the measurement by the first current sensor and the second current sensor;
A resistance value changing step for changing the resistance value of the resistance circuit;
Repeating the measured value obtaining step after the resistance value changing step;
A correction amount setting step for setting a correction amount for correcting the current value by the first current sensor based on the plurality of acquired current values;
A current value measurement method comprising: a correction step of correcting the current value of the charge / discharge current measured by the first current sensor based on the correction amount set by the correction amount setting step.   The current value measurement method according to claim 1, wherein the measurement value acquisition step is performed in a state in which the connection between the battery and the electric load is disconnected. The second current sensor is wound around the magnetic core, an annular magnetic core having a through hole, a Hall element that detects a magnetic flux formed by a measurement current passing through the through hole of the magnetic core, and the magnetic core. And a current supply device for supplying a current to the winding so as to cancel a magnetic flux formed in the magnetic core by a measurement current based on a detection value by the Hall element,
The voltage detection device is configured to be able to detect the voltage of the battery based on the current supplied by the current supply device,
3. The current according to claim 1, wherein in the correction amount setting step, the correction amount is set so that a current value obtained by the first current sensor matches or approaches a current value obtained by the second current sensor. Value measurement method. A battery connected to an electrical load for charging and discharging;
A first current sensor for measuring a charge / discharge current input to and output from the battery;
On the circuit connecting the electric load and the battery, one end is connected to the positive terminal of the battery, the other end is connected to the negative terminal of the battery, a series connection consisting of a second current sensor and a resistance circuit,
A voltage detection circuit that detects a voltage of the battery based on a measured value by the second current sensor of a current flowing through a closed circuit formed by the battery and the series connection; and a battery provided in a battery system comprising: A current measuring device,
Resistance value changing means for changing the resistance value of the resistor circuit;
Circuit switching means for switching connection so as to form a correction closed circuit comprising the first current sensor, the series connection and the battery;
Correction means for correcting the measured value of the charge / discharge current measured by the first current sensor,
Based on the measurement by the first current sensor and the second current sensor in each of the correction closed circuits having different resistance values by the correction means changing the resistance value of the resistance circuit by the resistance value changing means. A correction amount for correcting the current value by the first current sensor based on the current value by the second current sensor is set, and the current by the first current sensor is set based on the correction amount. A current value measuring device which corrects a value. The battery system includes a blocking means for disconnecting the connection between the battery and an electric load,
The correction means obtains a current value in the correction closed circuit based on the measurement by the first current sensor and the second current sensor in a state where the connection between the battery and the electric load is disconnected by the interruption means. The current value measuring device according to claim 4, wherein: The second current sensor is wound around the magnetic core, an annular magnetic core having a through hole, a Hall element that detects a magnetic flux formed by a measurement current passing through the through hole of the magnetic core, and the magnetic core. And a current supply device for supplying a current to the winding so as to cancel a magnetic flux formed in the magnetic core by a measurement current based on a detection value by the Hall element,
The voltage detection device is configured to be able to detect the voltage of the battery based on the current supplied by the current supply device,
6. The current value measurement according to claim 4, wherein the correction unit sets the correction amount so that a current value obtained by the first current sensor matches or approaches a current value obtained by the second current sensor. apparatus.

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