JP5099057B2 - Detection value correction device for current sensor - Google Patents

Description

  The present invention relates to a detection value correction apparatus that corrects a detection value of a current sensor.

  There is a magnetic detection type current sensor that detects a current generated by detecting a magnetic field generated according to a current flowing in a current path.

  In Patent Document 1, in a vehicle including a connection portion that connects and disconnects a supply path for supplying current from a DC power supply to an electric circuit, and a current sensor that detects a current flowing through the supply path, the connection portion is in a disconnected state. It is described that the offset value of the current sensor is observed and the output of the current sensor when the connection portion is in the connected state is corrected by the offset value.

  Patent Document 2 describes that the detected current is corrected by the current sensor based on the current detected by the current sensor when the connection between the secondary battery and the electric device is cut off.

  In Patent Document 3, in order to determine whether an unexpected charging current flows in the secondary battery, in the configuration for determining whether the magnitude of the current flowing in the secondary battery exceeds a threshold charging current, In the case where there is an offset in the detection capability or the like of the current detection unit, the threshold charging current is set in consideration of the offset.

JP 2006-246564 A JP 2002-151165 A JP 2008-199761 A

  By the way, when the magnetic detection type current sensor and the electromagnetic relay are arranged close to each other, when the electromagnetic relay is in the ON state, the current is influenced by the influence of the magnetic field generated by the electromagnet for driving the contact of the electromagnetic relay. A detection error occurs in the sensor. In particular, when a magnetic detection type current sensor that is easily affected by an externally applied magnetic field, such as a coreless type current sensor that directly detects a magnetic field without using a magnetic collecting core, is used, the current detection accuracy is significantly deteriorated. It is. In addition, even when the distance between the current sensor and the electromagnetic relay is close due to the downsizing of the device, the current detection accuracy is significantly deteriorated.

  The present invention provides a detection value correction device for a current sensor capable of correcting a detection error of the current sensor by an electromagnetic relay.

  A detection value correction apparatus for a current sensor according to the present invention includes a positive electromagnetic relay connected between a positive electrode of a DC power supply and a load, and a negative electrode side connected between the negative electrode of the DC power supply and the load. Correction of the detected value of the current sensor in a system including an electromagnetic relay and a current sensor that detects the current by detecting a magnetic field generated according to a current flowing in a current path between the DC power source and the load A detection value of the current sensor when only the positive electromagnetic relay is turned on among the electromagnetic relays, and the detected value when only the negative electromagnetic relay is turned on among the electromagnetic relays. Using the detected value of the current sensor, the detected value of the current sensor when both the positive and negative electromagnetic relays are in the on state is corrected.

  According to the present invention, it is possible to correct a detection error of a current sensor by an electromagnetic relay.

It is the schematic which shows an example of the structure of the system containing the current sensor detection value correction apparatus which concerns on embodiment. It is the schematic which shows an example of the specific structure of a system. It is a time chart which shows an example of operation | movement of the system of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an example of a configuration of a system 100 including a current sensor detection value correction apparatus 10 according to the present embodiment. In FIG. 1, a system 100 includes a DC power source 1, a load 2, a system main relay (hereinafter referred to as “SMR”) 3B, 3G, 3P, a resistor 4, a current sensor 5, and a current sensor detection value correction device 10.

  The DC power source 1 is a power source that supplies DC power. In one aspect, the DC power supply 1 is a chargeable / dischargeable power supply, such as a secondary battery or a large-capacity capacitor. A power supply line L1 is connected to the positive electrode of the DC power supply 1, and an earth line L2 is connected to the negative electrode.

  The load 2 is an electric load that receives supply of electric power from the DC power source 1. In one aspect, the system 100 is a drive system mounted on a hybrid vehicle or an electric vehicle, and the load 2 is supplied with power from the DC power source 1 via the capacitor that smoothes the voltage of the DC power source 1 and the capacitor. Including a receiving inverter, a traveling motor driven by the inverter, and the like. Such a configuration is disclosed in, for example, Patent Document 1, and detailed description thereof is omitted here.

  The SMR 3B is a positive-side electromagnetic relay connected between the positive electrode of the DC power source 1 and the load 2. The SMR 3G is a negative electromagnetic relay connected between the negative electrode of the DC power source 1 and the load 2. The SMR 3P is an electromagnetic relay connected in parallel to the SMR 3G, and a resistor 4 is connected to the SMR 3P in series. SMRs 3B, 3G, and 3P include an electromagnet and a contact driven by the electromagnet. When the electromagnet is in a non-excited state (non-energized state), the contact is held in an open state (off state), and the electromagnet is excited. The contact is held in a closed state (on state) when in a state (energized state).

  Here, the operation when starting the power supply from the DC power supply 1 to the load 2 will be briefly described. First, SMR3P is turned on after SMR3B is turned on. Thereby, the DC power source 1 and the capacitor in the load 2 are connected via the resistor 4, and charging of the capacitor is started while the inrush current is suppressed by the resistor 4. Then, after the capacitor is charged to some extent, SMR3P is turned off and SMR3G is turned on. As a result, the DC power supply 1 and the load 2 are connected without the resistor 4 interposed therebetween. As described above, the SMR 3P and the resistor 4 are for suppressing an inrush current at the start of power supply, but they may be omitted.

  The current sensor 5 is a magnetic detection type current sensor that detects a current flowing in the current path by detecting a magnetic field generated according to a current flowing in the current path between the DC power source 1 and the load 2. In the example of FIG. 1, the current sensor 5 is provided on the earth line L2.

  The current sensor detection value correction device 10 corrects the detection value of the current sensor 5. Specifically, the current sensor detection value correction device 10 detects the detection value of the current sensor 5 when only the positive electromagnetic relay (SMR3B) among the electromagnetic relays is turned on, and the negative electromagnetic of the electromagnetic relay. Using the detection value of the current sensor 5 when only the relay (SMR3G) is turned on, the detection value of the current sensor 5 when both the positive and negative electromagnetic relays (SMR3B, 3G) are on. Correct.

More specifically, the current sensor detection value correction device 10 executes the following processes (1) to (5). The order in which the processes (1) to (3) are executed is not particularly limited.
(1) When the SMRs 3B, 3G, and 3P are all turned off, the detection value of the current sensor 5 in the state of zero actual current is acquired, and the detection value is stored as OFFSET_BASE.
(2) The detection value of the current sensor 5 in a state where the actual current is zero when only the SMR 3B is turned on in the SMR is acquired, and the detection value is stored as OFFSET_PLUS.
(3) The detection value of the current sensor 5 in the state where the actual current is zero when only the SMR 3G is turned on in the SMR is acquired, and the detection value is stored as OFFSET_MINUS. (4) From the stored value, the offset value OFFSET is obtained as a correction value for the offset error of the current sensor 5 by the following equation. In the following equation, (OFFSET_PLUS-OFFSET_BASE) is an error due to SMR3B, and (OFFSET_MINUS-OFFSET_BASE) is an error due to SMR3G.
OFFSET
= OFFSET_BASE + (OFFSET_PLUS−OFFSET_BASE) + (OFFSET_MINUS−OFFSET_BASE)
= OFFSET_PLUS + OFFSET_MINUS-OFFSET_BASE
(5) The offset value OFFSET is used to correct the detection value I of the current sensor 5 when both the SMR 3B and SMR 3G are in the ON state, and the current value I ′ during SMR ON is obtained. Specifically, the current value I ′ during SMR-on is calculated by the following equation.
I '= I-OFFSET

  In the example of FIG. 1, the current sensor detection value correction device 10 includes an SMR drive unit 11, a current sensor offset calculation unit 12, and a current detection value correction unit 13 as functional blocks.

  The SMR drive unit 11 drives the SMRs 3B, 3G, and 3P, and passes the on / off states of the SMRs 3B, 3G, and 3P to the current sensor offset calculation unit 12. The SMR driver 11 is configured to form a period in which all of the SMRs 3B, 3G, and 3P are in an off state, a period in which only the SMR 3B is in an on state, and a period in which only the SMR 3G is in an on state. 3P is driven and controlled.

  Based on the on / off information from the SMR driving unit 11, the current sensor offset calculation unit 12 detects the detection value of the current sensor 5 during the period in which all of the SMRs 3B, 3G, and 3P are in the off state, and the current during the period in which only the SMR 3B is in the on state. The detection value of the sensor 5 and the detection value of the current sensor 5 during a period in which only the SMR 3G is on are acquired, and the offset value OFFSET is calculated from these detection values.

  The current detection value correction unit 13 acquires the detection value I of the current sensor 5 when both the SMR 3B and SMR 3G are on, and uses the offset value OFFSET calculated by the current sensor offset calculation unit 12 to detect the detection value I I is corrected to obtain a current value I ′ during SMR-on. That is, the current detection value correction unit 13 calculates the current value I ′ while the SMR is on by I ′ = I−OFFSET. The detected current value correction unit 13 outputs the calculated current value I ′ during SMR ON as a final output.

  In one aspect, the current sensor detection value correction device 10 is realized by cooperation of hardware resources and software, and is, for example, an electronic control unit (ECU). Specifically, the function of the current sensor detection value correction device 10 is that a program recorded in a recording medium such as a ROM (Read Only Memory) is read out to a main memory and executed by a CPU (Central Processing Unit). It is realized by. The program can be provided by being recorded on a computer-readable recording medium, or can be provided by communication as a data signal. However, the current sensor detection value correction apparatus 10 may be realized only by hardware. Further, the current sensor detection value correction device 10 may be physically realized by one device or may be realized by a plurality of devices.

  FIG. 2 is a schematic diagram illustrating an example of a specific configuration of the system 100. In FIG. 2, a system 100 includes a DC power supply 1, a load 2, a system main relay (hereinafter referred to as “SMR”) 3B, 3G, 3P, a resistor 4, a current sensor 5, a battery monitoring unit 20, and a power management ECU 30. Including.

  In the example of FIG. 2, the system 100 is a drive system mounted on a hybrid vehicle having an internal combustion engine and a motor as drive sources, the DC power source 1 is a secondary battery, the load 2 is a smoothing capacitor, DC− A DC converter, an inverter, a motor and the like are included.

  The battery monitoring unit 20 is a device that monitors the state of the DC power supply 1 (secondary battery). The battery monitoring unit 20 performs A / D conversion on the output of the current sensor 5 and outputs a digital current detection value to the power management ECU 30 by serial communication, for example.

  The power management ECU 30 is a device that manages power supply to the load 2 and includes a function of a current sensor detection value correction device in the present embodiment. That is, the power management ECU 30 performs an SMR drive function for driving and controlling the SMRs 3B, 3G, and 3P, a current sensor offset calculation function for calculating an offset value of the current sensor, and a current detection value correction operation to perform current calculation during the SMR on-state. And a current detection value correction function for outputting a value.

  FIG. 3 is a time chart showing an example of the operation of the system 100 of FIG. FIG. 3 shows the ready signal (RDY signal) indicating the start-up state of the system 100, and the on / off states of SMR3B, SMR3G, and SMR3P.

  In the ignition-on state, the ready signal, SMR3B, and SMR3G are on, and SMR3P is off.

  When the ignition is turned off, the ready signal, SMR3B, and SMR3G are turned off.

  Thereafter, only the SMR 3B is turned on for a predetermined period, and OFFSET_PLUS is learned in this period.

  After SMR3B is turned off, only SMR3G is turned on for a predetermined period, and OFFSET_MINUS is learned during this period.

  After SMR3G is turned off, OFFSET_BASE learning is performed in a section in which all SMRs are off.

  Thereafter, the offset value OFFSET is calculated based on the OFFSET_PLUS, OFFSET_MINUS, and OFFSET_BASE.

  Note that the above time chart is an example, and it is sufficient to provide an SMR3B single-on period, an SMR3G single-on period, and all SMR-off periods, and operations of the SMRs 3B, 3G, and 3P after the ignition is turned off. May be changed as appropriate. For example, after the ignition is turned off, an abnormality detection process such as SMR welding check may be performed, and the SMR operation may be different from the above.

  In FIG. 3, the offset value is acquired after the ignition is turned off. However, it is also possible to acquire the offset value when the ignition is turned on. However, when the offset value is acquired when the ignition is on, the system startup time is delayed, so it is desirable to acquire it after the ignition is off.

  Further, when the offset value is acquired after the ignition is turned off, it is preferable to acquire the offset value only when the auxiliary machine voltage is higher than a predetermined value. This is due to the following reason. While the ignition is on (system is operating), the DC / DC converter that reduces the DC voltage of the DC power supply 1 to the auxiliary machine voltage is operating, so the SMR is driven at a relatively high auxiliary machine voltage (around 14V). . On the other hand, after the ignition is turned off (after the system is stopped), the DC / DC converter is stopped. For this reason, when the secondary battery for auxiliary machines has deteriorated, it will be in the state which the auxiliary machine voltage fell. When the SMR is turned on in a state where the auxiliary machine voltage is lowered, the current flowing through the electromagnet in the SMR is lowered, so that the magnetic field generated by the SMR is lower than the magnetic field generated during system operation. For this reason, if the offset value learning is performed in a state where the auxiliary device voltage is lowered due to the deterioration of the secondary battery for auxiliary machinery, the learning accuracy of the offset value is deteriorated, and consequently the current detection accuracy is deteriorated.

  As described above, in the present embodiment, a positive-side electromagnetic relay connected between the positive electrode of the DC power supply and the load, a negative-side electromagnetic relay connected between the negative electrode of the DC power supply and the load, In a system including a current sensor that detects the current by detecting a magnetic field generated according to a current flowing in a current path between a DC power source and a load, the current sensor detection value correction device includes the electromagnetic relay Using the detected value of the current sensor when only the positive electromagnetic relay is turned on and the detected value of the current sensor when only the negative electromagnetic relay of the electromagnetic relays is turned on, the positive side Then, the detection value of the current sensor is corrected when both the negative-side electromagnetic relay and the negative-side electromagnetic relay are on. For this reason, according to this Embodiment, the electric current detection error by an electromagnetic relay can be correct | amended, and electric current detection accuracy can be improved. Thereby, for example, when estimating the remaining capacity (SOC: State of Charge) of the DC power source using the current detection value, it is possible to improve the estimation accuracy of the SOC.

  1 DC power supply, 2 load, 3B, 3G, 3P system main relay (SMR), 4 resistance, 5 current sensor, 10 current sensor detection value correction device.

Claims (1)

A positive electromagnetic relay connected between a positive electrode of a DC power supply and a load; a negative electromagnetic relay connected between a negative electrode of the DC power supply and the load; and the DC power supply and the load. A detection value correction device for a current sensor in a system including a current sensor for detecting the current by detecting a magnetic field generated according to a current flowing in a current path between the current sensors,
The detected value of the current sensor when only the positive electromagnetic relay of the electromagnetic relays is turned on, and the detected value of the current sensor when only the negative electromagnetic relay of the electromagnetic relays is turned on And correcting the detection value of the current sensor when both the positive and negative electromagnetic relays are in the ON state.

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