Offset correction device and offset correction circuit

Abstract

To provide an offset correction device and an offset correction circuit that are capable of suppressing an increase in offset drift and thereby improving the measurement accuracy of a sensor unit.SOLUTION: An offset correction device for performing offset correction of a sensor unit includes a first wiring section connected to an input line and an output line and positioned in a measurement area of the sensor unit, a second wiring section connected in parallel to the first wiring section and positioned in the measurement area, a switch section that switches at least the second wiring section between a conductive state and a non-conductive state, and a control section that controls the switch section to perform offset correction of the sensor unit. The second wiring section is positioned so that a current in the opposite direction to the current in the first wiring section is measured by the sensor unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an offset correction device and an offset correction circuit. [Background technology]

[0002] Conventionally, it is known that a circuit that supplies a current to a load is provided with a sensor unit capable of measuring the current. Since the measurement value of the sensor unit includes an offset value, offset correction is generally performed (for example, see Patent Document 1). Usually, offset correction is performed when no current flows through the sensor unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-16493 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, if disturbances or temperature changes occur during the operation of the load, offset drift may occur, and the measurement value of the sensor unit may include an offset value based on the offset drift. In the conventional configuration, it was not possible to perform offset correction when current was flowing through the sensor unit. Therefore, if a circuit is used such that current continues to flow through the sensor unit at all times, there is no opportunity for offset correction, and the problem of increased offset drift occurs.

[0005] An object of the present disclosure is to provide an offset correction device and an offset correction circuit that are capable of suppressing an increase in offset drift and thereby improving the measurement accuracy of a sensor unit. [Means for solving the problem]

[0006] The offset correction device according to the present disclosure comprises: An offset correction device for performing offset correction on a sensor unit, a first wiring section connected to the input line and the output line and disposed in a measurement area of ​​the sensor section; a second wiring portion connected in parallel to the first wiring portion and disposed in the measurement area; a switch section that switches at least the second wiring section between a conductive state and a non-conductive state; a control unit that controls the switch unit to perform offset correction of the sensor unit; Equipped with The second wiring portion is disposed so that a current in a direction opposite to that of the first wiring portion is measured by the sensor portion.

[0007] The offset correction circuit according to the present disclosure comprises: An offset correction circuit for performing offset correction of a sensor unit, a first wiring section connected to the input line and the output line and disposed in a measurement area of ​​the sensor section; a second wiring portion connected in parallel to the first wiring portion and disposed in the measurement area; a switch section that switches at least the second wiring section between a conductive state and a non-conductive state; Equipped with The second wiring portion is disposed so that a current in a direction opposite to that of the first wiring portion is measured by the sensor portion. Effect of the Invention

[0008] According to the present disclosure, it is possible to suppress an increase in offset drift, and thus improve the measurement accuracy of the sensor unit. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating a schematic configuration of an offset correction device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing the offset correction device in a first measurement state. [Diagram 3] FIG. 13 is a diagram showing the offset correction device in a second measurement state. [Figure 4] 5 is a flowchart showing an example of a flow of processing executed by the offset correction device according to the present embodiment. [Diagram 5] FIG. 13 is a diagram showing an offset correction device according to a modified example. [Figure 6] FIG. 13 is a diagram showing an offset correction device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. Fig. 1 is a diagram showing a schematic configuration of an offset correction device 1 according to an embodiment of the present disclosure.

[0011] As shown in FIG. 1, the offset correction device 1 is a device capable of performing offset correction of a sensor unit 4 provided on a power line connecting a power source 2 and a load 3, for example.

[0012] The power source 2 is, for example, a battery provided in the vehicle. The load 3 is, for example, a motor, an inverter, or the like provided in the vehicle, which can be operated by electric power. The sensor unit 4 is a current sensor capable of measuring the current in a circuit, and may be of a known configuration, for example, a Hall type, a shunt type, or the like. In FIG. 1, a Hall type current sensor is illustrated as the sensor unit 4.

[0013] The offset correction device 1 includes an offset correction circuit 10 and a control unit 20.

[0014] The offset correction circuit 10 is a circuit provided at a position corresponding to the sensor unit 4, and includes a first wiring unit 11, a second wiring unit 12, and a switch unit 13.

[0015] The first wiring section 11 and the second wiring section 12 are power lines connected to the input line 10A and the output line 10B of the offset correction circuit 10, and the second wiring section 12 is connected in parallel with the first wiring section 11. The input line 10A is a power line connected to the power source 2, and the output line 10B is a power line connected to the load 3.

[0016] The first wiring part 11 also has a first measurement part 11A disposed in the measurement region of the sensor part 4. The first measurement part 11A is a part that connects two connection points C1 and C2 between the first wiring part 11 and the second wiring part 12. The connection point C1 is connected to an input line 10A, and the connection point C2 is connected to an output line 10B.

[0017] Moreover, the sensor unit 4 is disposed in the region between the connection point C1 and the connection point C2, and the region in which the sensor unit 4 is disposed is the measurement region.

[0018] A part of the first measurement portion 11A is disposed so that a current flows in a direction (first direction) from the connection point C1 to the connection point C2 in the measurement region of the sensor unit 4. In other words, the first measurement portion 11A of the first wiring portion 11 is disposed so that the current of the first wiring portion 11 is measured by the sensor unit 4 as a current in the positive direction.

[0019] The second wiring part 12 has a first non-measurement part 12A and a second non-measurement part 12B that are disposed outside (non-measurement area) of the measurement area of ​​the sensor part 4, and a second measurement part 12C that is disposed in the measurement area of ​​the sensor part 4. The first non-measurement part 12A and the second non-measurement part 12B correspond to the "two parts" in this disclosure.

[0020] The first non-measurement portion 12A is connected to a connection point C1 on the input line 10A side between the first wiring portion 11 and the second wiring portion 12 via a second switch 13B described later. The first non-measurement portion 12A is disposed so as to connect the connection point C1 and point C3 in the non-measurement area of ​​the sensor portion 4. Point C3 is a point located on the connection point C2 side of the measurement area (sensor portion 4), and is a point connected to a second measurement portion 12C described later.

[0021] The second non-measurement portion 12B is connected to a connection point C2 on the output line 10B side between the first wiring portion 11 and the second wiring portion 12. The second non-measurement portion 12B is disposed so as to connect point C4 and the connection point C2 in the non-measurement region of the sensor portion 4. Point C4 is a point located on the connection point C1 side of the measurement region (sensor portion 4), and is a point connected to the second measurement portion 12C described later.

[0022] The second measurement portion 12C is disposed so as to pass through the measurement region between point C3 of the first non-measurement portion 12A and point C4 of the second non-measurement portion 12B. In other words, the first non-measurement portion 12A and the second non-measurement portion 12B are connected to both sides of a portion of the second measurement portion 12C that corresponds to the measurement region.

[0023] The current flowing through the second measurement portion 12C flows in a direction from point C3 of the first non-measurement portion 12A to point C4 of the second non-measurement portion 12B. That is, the second measurement portion 12C is disposed so that the current flows in a second direction opposite to the first direction. In other words, the second wiring portion 12 is disposed so that the current in the opposite direction to the current in the first wiring portion 11 (negative current) is measured by the sensor portion 4.

[0024] Thereby, the second measurement portion 12C is disposed so that the current in the second wiring portion 12 is measured as a current in the negative direction by the sensor portion 4. As a result, when the first wiring portion 11 and the second wiring portion 12 are both conductive, the sensor portion 4 outputs the difference value between the absolute value of the current in the first wiring portion 11 and the absolute value of the current in the second wiring portion 12 as a measurement value.

[0025] The switch section 13 is a group of switches for switching each of the first wiring section 11 and the second wiring section 12 between conductive and non-conductive states, and includes a first switch 13A and a second switch 13B. The first switch 13A and the second switch 13B may be semiconductor switching elements such as FETs (Field Effect Transistors).

[0026] The first switch 13A is a switch that switches the first wiring portion 11 between a conductive state and a non-conductive state. The second switch 13B is a switch that switches the second wiring portion 12 between a conductive state and a non-conductive state.

[0027] Furthermore, the first switch 13A and the second switch 13B have the same impedance. That is, the impedance of the second wiring portion 12 is equal to the impedance of the first wiring portion 11. Therefore, when the first wiring portion 11 and the second wiring portion 12 are both conductive, the absolute value of the current in the first wiring portion 11 is equal to the absolute value of the current in the second wiring portion 12.

[0028] Here, the impedance of the second wiring part 12 being equal to the impedance of the first wiring part 11 not only means that the two impedances are completely identical, but also includes the case where the difference between the two impedances is very small due to differences in wiring resistance.

[0029] The control unit 20 is, for example, an ECU (Electronic Control Unit) provided in a vehicle, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output circuit (not shown). The control unit 20 controls the switch unit 13 to perform offset correction of the sensor unit 4.

[0030] 2, the control unit 20 controls the switch unit 13 to enter a first measurement state in which the first wiring unit 11 is conductive and the second wiring unit 12 is non-conductive. Specifically, the control unit 20 controls the first switch 13A to make the first wiring unit 11 conductive and controls the second switch 13B to make the second wiring unit 12 non-conductive. The first measurement state is a state in which only the current flowing through the first wiring unit 11 is measured by the sensor unit 4.

[0031] When current continues to be supplied to the load 3 in the first measurement state, an offset drift occurs in the measurement value of the sensor unit 4 due to disturbances, temperature changes while the vehicle is running, and the like. Since the measurement value of the sensor unit 4 originally contains an offset value, offset correction is generally performed in advance. Usually, offset correction is performed when no current flows through the sensor unit 4.

[0032] However, when the load 3 is used such that current continues to be supplied thereto, as described above, offset drift occurs, and the measurement value of the sensor unit 4 includes an offset value caused by the offset drift, which may result in a value different from the current value actually supplied to the load 3.

[0033] In this embodiment, the control unit 20 performs offset correction based on the measurement state of the sensor unit 20 in the first measurement state. Specifically, the control unit 20 determines whether or not the latest measurement value of the sensor unit 4 in the first measurement state has changed from the initial measurement value of the sensor unit 4 when the sensor unit 4 is in the first measurement state.

[0034] Then, when the control unit 20 determines that the latest measurement value has fluctuated from the initial measurement value, it controls the switch unit 13 to enter a second measurement state in which the first wiring unit 11 and the second wiring unit 12 are conductive. Specifically, as shown in Fig. 3, the control unit 20 controls the first switch 13A to make the first wiring unit 11 conductive, and controls the second switch 13B to make the second wiring unit 12 conductive. The second measurement state is a state in which the sensor unit 4 measures the current flowing through the first wiring unit 11 and the current flowing through the second wiring unit 12.

[0035] As described above, when the first wiring part 11 and the second wiring part 12 are both conductive, the sensor part 4 outputs, as a measurement value, a difference value between the absolute value of the current in the first wiring part 11 and the absolute value of the current in the second wiring part 12. Also, as described above, the absolute value of the current in the first wiring part 11 is the same as the absolute value of the current in the second wiring part 12.

[0036] Therefore, in the second measurement state, the current in the first wiring portion 11 and the current in the second wiring portion 12 are offset, and only the measurement value of the offset current based on the offset drift is measured by the sensor portion 4. That is, in the second measurement state, the offset current can be measured by the sensor portion 4.

[0037] The control unit 20 performs offset correction based on the measurement result of the sensor unit 4 in the second measurement state. Specifically, the control unit 20 determines the measurement value of the sensor unit 4 after the offset correction to be the value obtained by subtracting the measurement value of the offset current from the measurement value of the sensor unit 4 before the offset correction.

[0038] This provides an opportunity for offset correction when the circuit is used so that current constantly flows through the sensor unit 4, making it possible to suppress the occurrence of offset drift.

[0039] Next, a description will be given of the operation of the offset correction device 1. Fig. 4 is a flowchart showing an example of the flow of processing executed by the offset correction device 1 in this embodiment. The processing in Fig. 4 is executed when a vehicle equipped with the offset correction device 1 starts operating.

[0040] 4, the control unit 20 makes the first wiring unit 11 conductive and makes the second wiring unit 12 non-conductive (step S101). That is, the control unit 20 controls the switch unit 13 to be in the first measurement state.

[0041] After step S101, the control unit 20 measures an initial measurement value by the sensor unit 4 (step S102). After measuring the initial measurement value, the control unit 20 monitors the measurement value by the sensor unit 4 and determines whether or not the latest measurement value has changed from the initial measurement value (step S103). The process of step S103 may be executed every time a certain period of time has elapsed.

[0042] If the determination result shows that the latest measurement value has not changed from the initial measurement value (step S103, NO), the process of step S103 is repeated. On the other hand, if the latest measurement value has changed from the initial measurement value (step S103, YES), the control unit 20 makes the second wiring unit 12 conductive (step S104). That is, the control unit 20 controls the switch unit 13 to enter the second measurement state.

[0043] Then, the control unit 20 measures the offset current by the sensor unit 4 (step S105). After step S105, the control unit 20 executes offset correction based on the measured value of the offset current (step S106).

[0044] After step S106, the control unit 20 disconnects the second wiring unit 12 (step S107). That is, the control unit 20 controls the switch unit 13 to be in the first measurement state. Note that the process of step S107 may be executed at any timing as long as it is after the offset current is measured in the process of step S105.

[0045] After step S107, this control ends. Note that after the process of step S107, the process may return to step S102.

[0046] According to the present embodiment configured as described above, the second wiring part 12 is arranged so that a current in a direction opposite to the current of the first wiring part 11 is measured by the sensor part 4. Specifically, the first wiring part 11 has a first measurement part 11A arranged so that a current flows in a first direction, and the second wiring part 12 has a second measurement part 12C arranged so that a current flows in a second direction opposite to the first direction.

[0047] As a result, when current is passed through both the first wiring portion 11 and the second wiring portion 12, the current value obtained by subtracting the current through the second wiring portion 12 from the current through the first wiring portion 11 can be measured by the sensor portion 4.

[0048] As a result, when an offset drift occurs, the offset value can be easily measured by the sensor unit 4, so that offset correction can be performed even when the current in the circuit continues to flow. That is, in this embodiment, an increase in the offset drift can be suppressed, and the measurement accuracy of the sensor unit 4 can be improved.

[0049] In addition, since the first wiring portion 11 and the second wiring portion 12 are connected in parallel, even if a current is caused to flow through both the first wiring portion 11 and the second wiring portion 12, there is almost no effect on the current supplied to the load 3. Therefore, it is possible to perform offset correction while continuing to supply a current to the circuit.

[0050] Moreover, the control unit 20 sets the first measurement state in which the first wiring unit 11 is conductive and the second wiring unit 12 is non-conductive, and sets the second measurement state in which the first wiring unit 11 and the second wiring unit 12 are conductive based on the measurement result of the sensor unit 4 in the first measurement state. Thereby, by detecting the occurrence of offset drift due to fluctuations in the measurement value of the sensor unit 4 in the first measurement state, it is possible to switch to the second measurement state and quickly detect the offset value.

[0051] That is, by simply controlling the switch unit 13, it is possible to quickly detect the offset value while continuing to supply current to the circuit, thereby enabling a simple configuration and simple control.

[0052] In addition, since the impedance of the second wiring portion 12 is equal to the impedance of the first wiring portion 11, the measurement value of the sensor portion 4 can be set as the offset value when a current is passed through both the first wiring portion 11 and the second wiring portion 12. As a result, it is possible to easily measure the offset value.

[0053] Moreover, the input line 10A is connected to a power source 2 of the vehicle, and the output line 10B is connected to a load 3 of the vehicle. When the vehicle is running, the temperature around the vehicle may fluctuate due to fluctuations in the surrounding environment. This may make offset drift more likely to occur. Since vehicles often operate continuously, there is a high need to perform offset correction frequently. In particular, in the case of commercial vehicles, the bodywork often continues to operate even when the vehicle is not running, so the need to perform offset correction frequently becomes even higher.

[0054] In this embodiment, offset correction can be performed while continuing to supply current to the circuit. Therefore, when the sensor is mounted on a vehicle, offset correction can be performed in a timely manner, which in turn makes it easier to improve the measurement accuracy of the sensor unit 4.

[0055] In the above embodiment, no particular consideration was given to the wiring resistances of the first wiring portion 11 and the second wiring portion 12. Specifically, in the above embodiment, the second wiring portion 12 has a longer wiring length and a larger wiring resistance than the first wiring portion 11 because it has the first non-measurement portion 12A, the second non-measurement portion 12B, and the second measurement portion 12C. However, the present disclosure is not limited to this, and the first wiring portion 11 and the second wiring portion 12 may be configured to have the same wiring resistance.

[0056] 5, the first wiring part 11 may have a non-measurement part 11B that is connected to a rear part of the sensor part 4 in the first measurement part 11A. The non-measurement part 11B is disposed in a non-measurement area of ​​the sensor part 4, and has a length such that the wiring resistance of the first wiring part 11 is equal to the wiring resistance of the second wiring part 12.

[0057] This allows the impedances of the first wiring portion 11 and the second wiring portion 12 to match, thereby enabling more accurate offset correction.

[0058] In the above embodiment, the first switch 13A is provided in the first wiring section 11, and the second switch 13B is provided in the second wiring section 12. That is, in the above embodiment, the first wiring section 11 is controlled to be conductive in the first measurement state and the second measurement state, but the present disclosure is not limited to this.

[0059] 6, a switch section 13 (one switch) may be provided only in the second wiring section 12. In this case, in order to equalize the impedances of the first wiring section 11 and the second wiring section 12, for example, some kind of circuit element 14 (for example, a resistive element, a switching element fixed in a conductive state, etc.) may be provided in the first wiring section 11. Note that in this configuration, in order to cut off the supply of power when the operation of the load 3 is stopped, another switch may be provided in the input line 10A or the output line 10B.

[0060] In the above embodiment, the sensor unit 4 measures the current in the first wiring unit 11 as a current in the positive direction and the current in the second wiring unit 12 as a current in the negative direction, but the present disclosure is not limited to this. For example, the sensor unit may measure the current in the first wiring unit as a current in the negative direction and the current in the second wiring unit as a current in the positive direction.

[0061] In the above embodiment, the offset correction device 1 is mounted on a vehicle, but the present disclosure is not limited thereto, and the offset correction device 1 may be mounted on something other than a vehicle. Anything other than a vehicle may be used as long as it has a load that can operate with electric power. For example, if an offset correction device is provided in a facility such as a factory or a building where the load needs to continue to operate, the offset correction can be performed while the load is operating, which is thought to contribute to improving the measurement accuracy of the sensor unit.

[0062] In addition, the above-mentioned embodiments are merely examples of the embodiment of the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by them. In other words, the present disclosure can be embodied in various forms without departing from the gist or main features thereof. [Industrial Applicability]

[0063] The offset correction device disclosed herein is useful as an offset correction device and offset correction circuit that can suppress an increase in offset drift and thereby improve the measurement accuracy of a sensor unit. [Explanation of symbols]

[0064] 1 Offset correction device 2 power supply 3. Load 4 Sensor section 10 Offset correction circuit 10A input line 10B Output line 11 1st wiring section 11A First measurement part 11B Non-measurement part 12 2nd wiring section 12A First non-measurement part 12B Second non-measurement part 12C Second measurement part 13 Switch section 13A 1st switch 13B Second switch 14 Circuit elements C1 Attachment Point C2 Attachment Point C3 point C4 point

Claims

1. An offset correction device for performing offset correction on a sensor unit, a first wiring portion connected to an input line and an output line and disposed in a measurement area of ​​the sensor portion; a second wiring portion connected in parallel to the first wiring portion and disposed in the measurement area; a switch section that switches at least the second wiring section between a conductive state and a non-conductive state; a control unit that controls the switch unit to perform offset correction of the sensor unit; Equipped with the second wiring portion is disposed so that a current in a direction opposite to a direction of the current in the first wiring portion is measured by the sensor portion; Offset correction device.

2. the first wiring portion has a first measurement portion that is disposed in the measurement region and that is disposed so that a current flows in a first direction; The second wiring portion is a second measurement portion disposed in the measurement region so that a current flows in a second direction opposite to the first direction; two portions connected to both sides of a portion of the second measurement portion corresponding to the measurement region; having 2. The offset correction device according to claim 1.

3. one of the two portions is connected to a connection point between the first wiring portion and the second wiring portion on the input line side; the other of the two portions is connected to a connection point between the first wiring portion and the second wiring portion on the output line side; 3. The offset correction device according to claim 2.

4. The control unit is controlling the switch unit to be in a first measurement state in which the second wiring unit is disconnected; controlling the switch unit to enter a second measurement state in which the second wiring portion is conductive, based on a measurement result of the sensor unit in the first measurement state; performing the offset correction based on a measurement result of the sensor unit in the second measurement state; 2. The offset correction device according to claim 1.

5. the switch unit includes a first switch that switches the first wiring unit between a conductive state and a non-conductive state, and a second switch that switches the second wiring unit between a conductive state and a non-conductive state, the control unit controls the switch unit to make the first wiring unit conductive in the first measurement state and the second measurement state.

5. The offset correction device according to claim 4.

6. The impedance of the second wiring portion is equal to the impedance of the first wiring portion.

2. The offset correction device according to claim 1.

7. The input line is connected to a vehicle power source; The output line is connected to a load of the vehicle.

2. The offset correction device according to claim 1.

8. An offset correction circuit for performing offset correction of a sensor unit, a first wiring portion connected to an input line and an output line and disposed in a measurement area of ​​the sensor portion; a second wiring portion connected in parallel to the first wiring portion and disposed in the measurement area; a switch section that switches at least the second wiring section between a conductive state and a non-conductive state; Equipped with the second wiring portion is disposed so that a current in a direction opposite to a direction of the current in the first wiring portion is measured by the sensor portion; Offset correction circuitry.

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