Bias correction device and bias correction circuit

Abstract

The invention provides a bias correction device and a bias correction circuit capable of suppressing an increase in bias drift and improving measurement accuracy of a sensor unit. An offset correction device for performing offset correction of a sensor unit includes: a first wiring unit connected to an input line and an output line and disposed in a measurement region of the sensor unit; a second wiring portion connected in parallel with the first wiring portion and disposed in the measurement region; a switch unit that switches at least the second wiring unit to either conductive or non-conductive; and a control unit that controls the switch unit so as to perform offset correction of the sensor unit, and the second wiring unit is disposed so that a current in the opposite direction to the current of the first wiring unit is measured by the sensor unit.

Description

Technical Field

[0001] The invention relates to a bias correction device and a bias correction circuit. Background Art

[0002] In the past, it is known to provide a sensor unit capable of measuring current in a circuit that supplies current to a load. Since the measured value of the sensor unit includes an offset value, an offset correction is generally performed (for example, refer to Patent Document 1). Usually, the offset correction is performed when no current flows in the sensor unit.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-16493 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] However, if external interference or temperature changes occur during load operation, bias drift may occur, and the measured value of the sensor unit may include a bias value based on the bias drift. In the previous structure, when current flows in the sensor unit, bias correction cannot be performed. Therefore, when the circuit is used in a manner in which current always flows in the sensor unit, there is no opportunity for bias correction, resulting in a problem of increased bias drift.

[0008] An object of the present invention is to provide an offset correction device and an offset correction circuit capable of suppressing an increase in an offset drift and improving the measurement accuracy of a sensor unit.

[0009] Solutions to the problem

[0010] The bias correction device of the present invention is a bias correction device for performing bias correction on a sensor unit, and comprises: a first wiring unit connected to an input line and an output line and arranged in a measurement area of ​​the sensor unit; a second wiring unit connected in parallel to the first wiring unit and arranged in the measurement area; a switch unit that switches the second wiring unit to at least one of conduction and non-conduction; and a control unit that controls the switch unit to perform bias correction on the sensor unit, the second wiring unit being arranged in such a way that a current in a direction opposite to that of a current in the first wiring unit is measured by the sensor unit.

[0011] The bias correction circuit of the present invention is a bias correction circuit for performing bias correction on a sensor unit, and comprises: a first wiring unit connected to an input line and an output line and arranged in a measurement area of ​​the sensor unit; a second wiring unit connected in parallel to the first wiring unit and arranged in the measurement area; and a switch unit that switches the second wiring unit to at least one of conducting and non-conducting, the second wiring unit being arranged in such a way that a current in a direction opposite to that of a current in the first wiring unit is measured by the sensor unit.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to suppress an increase in bias drift and improve the measurement accuracy of the sensor unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a diagram showing a schematic configuration of an offset correction device according to an embodiment of the present invention.

[0015] Figure 2 2 is a diagram showing the offset correction device in the first measurement state.

[0016] Figure 3 2 is a diagram showing the offset correction device in the second measurement state.

[0017] Figure 4 This is a flowchart showing an example of the flow of processing executed by the offset correction device according to this embodiment.

[0018] Figure 5 It is a diagram showing an offset correction device according to a modified example.

[0019] Figure 6 It is a diagram showing an offset correction device according to a modified example.

[0020] Description of Reference Numerals

[0021] 1: Bias correction device;

[0022] 2: Power supply;

[0023] 3: Load;

[0024] 4: Sensor part;

[0025] 10: Bias correction circuit;

[0026] 10A: input line;

[0027] 10B: output line;

[0028] 11: first wiring portion;

[0029] 11A: first measurement section;

[0030] 11B: non-measurement part;

[0031] 12: second wiring section;

[0032] 12A: first non-measurement portion;

[0033] 12B: second non-measurement part;

[0034] 12C: second measurement section;

[0035] 13: switch part;

[0036] 13A: first switch;

[0037] 13B: second switch;

[0038] 14: Circuit components;

[0039] 20: Control department;

[0040] C1: connection point;

[0041] C2: connection point;

[0042] C3: point;

[0043] C4: point. DETAILED DESCRIPTION

[0044] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Figure 1 It is a diagram showing a schematic configuration of an offset correction device 1 according to an embodiment of the present invention.

[0045] like Figure 1 As shown, the offset correction device 1 is a device that can perform offset correction on a sensor unit 4 provided on a power line connecting a power source 2 and a load 3, for example.

[0046] The power source 2 is, for example, a battery installed in the vehicle. The load 3 is, for example, a device that can be operated by power, such as a motor or an inverter installed in the vehicle. The sensor unit 4 is a current sensor that can measure the current of the circuit, and can be, for example, a well-known structure such as a Hall type or a shunt type. Figure 1 In FIG. 4 , a Hall-type current sensor is exemplified as the sensor unit 4 .

[0047] The offset correction device 1 includes an offset correction circuit 10 and a control unit 20 .

[0048] 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 .

[0049] First wiring section 11 and second wiring section 12 are power lines connected to input line 10A and output line 10B of offset correction circuit 10, and second wiring section 12 is connected in parallel to first wiring section 11. Input line 10A is a power line connected to power supply 2, and output line 10B is a power line connected to load 3.

[0050] The first wiring section 11 has a first measuring portion 11A disposed in the measuring region of the sensor section 4. The first measuring portion 11A is a portion connecting two connection points C1 and C2 between the first wiring section 11 and the second wiring section 12. The connection point C1 is connected to the input line 10A, and the connection point C2 is connected to the output line 10B.

[0051] In addition, the sensor unit 4 is arranged in the area between the connection point C1 and the connection point C2, and the area where the sensor unit 4 is arranged is the measurement area.

[0052] A portion of the first measurement portion 11A is configured so that a current flows in a direction (first direction) from the connection point C1 toward the connection point C2 in the measurement region of the sensor portion 4. In other words, the first measurement portion 11A of the first wiring portion 11 is configured so that the current of the first wiring portion 11 is measured by the sensor portion 4 as a current in a positive direction.

[0053] The second wiring section 12 includes a first non-measurement portion 12A and a second non-measurement portion 12B arranged outside the measurement region (non-measurement region) of the sensor section 4, and a second measurement portion 12C arranged in the measurement region of the sensor section 4. The first non-measurement portion 12A and the second non-measurement portion 12B correspond to the "two portions" of the present invention.

[0054] The first non-measurement portion 12A is connected to a connection point C1 on the input line 10A side of the first wiring section 11 and the second wiring section 12 via a second switch 13B described later. The first non-measurement portion 12A is arranged in the non-measurement region of the sensor section 4 so as to connect the connection point C1 and the point C3. The point C3 is a point located on the connection point C2 side of the measurement region (sensor section 4) and is connected to the second measurement portion 12C described later.

[0055] The second non-measurement portion 12B is connected to the connection point C2 on the output line 10B side of the first wiring section 11 and the second wiring section 12. The second non-measurement portion 12B is arranged in the non-measurement region of the sensor section 4 so as to connect point C4 to the connection point C2. Point C4 is a point located closer to the connection point C1 side than the measurement region (sensor section 4), and is a point connected to the second measurement portion 12C described later.

[0056] The second measurement portion 12C is arranged between point C3 of the first non-measurement portion 12A and point C4 of the second non-measurement portion 12B so as to pass through the measurement area. That is, the first non-measurement portion 12A and the second non-measurement portion 12B are connected to both sides of the portion of the second measurement portion 12C corresponding to the measurement area.

[0057] The current flowing in the second measurement portion 12C flows in a direction from point C3 of the first non-measurement portion 12A toward point C4 of the second non-measurement portion 12B. That is, the second measurement portion 12C is configured so that the current flows in the second direction, which is the opposite direction of the first direction described above. In other words, the second wiring portion 12 is configured so that the current in the opposite direction to the current of the first wiring portion 11 (current in the negative direction) is measured by the sensor portion 4.

[0058] Thus, the second measuring portion 12C is configured so that the current of the second wiring portion 12 is measured as a negative current by the sensor portion 4. As a result, when both the first wiring portion 11 and the second wiring portion 12 are turned on, the sensor portion 4 outputs the difference between the absolute value of the current of the first wiring portion 11 and the absolute value of the current of the second wiring portion 12 as a measured value.

[0059] The switch section 13 is a switch group for switching the first wiring section 11 and the second wiring section 12 to either conduction or non-conduction, and includes a first switch 13A and a second switch 13B. The first switch 13A and the second switch 13B may be semiconductor switch elements such as FETs (Field Effect Transistors).

[0060] The first switch 13A is a switch that switches the first wiring section 11 to one of conduction and non-conduction. The second switch 13B is a switch that switches the second wiring section 12 to one of conduction and non-conduction.

[0061] In addition, the first switch 13A and the second switch 13B have the same impedance. That is, the impedance of the second wiring section 12 is equal to the impedance of the first wiring section 11. Therefore, when both the first wiring section 11 and the second wiring section 12 are turned on, the absolute value of the current in the first wiring section 11 is the same as the absolute value of the current in the second wiring section 12.

[0062] It should be noted that, in addition to the case where the two impedances are completely identical, “the impedance of the second wiring portion 12 is equal to the impedance of the first wiring portion 11 ” mentioned here also includes the case where the difference between the two impedances is a small value due to the difference in wiring resistance.

[0063] The control unit 20 is, for example, an ECU (Electronic Control Unit) provided in the 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 bias correction of the sensor unit 4.

[0064] like Figure 2 As shown, the control unit 20 controls the switch unit 13 so as to achieve the first measurement state in which the first wiring unit 11 is turned on and the second wiring unit 12 is turned off. Specifically, the control unit 20 controls the first switch 13A so as to turn on the first wiring unit 11, and controls the second switch 13B so as to turn off the second wiring unit 12. The first measurement state is a state for measuring only the current flowing in the first wiring unit 11 using the sensor unit 4.

[0065] When current is continuously supplied to the load 3 in the first measurement state, an offset drift occurs in the measured value of the sensor unit 4 due to external disturbance, temperature change during vehicle travel, etc. The measured value of the sensor unit 4 originally includes an offset value, so an offset correction is generally performed in advance. Usually, the offset correction is performed when no current flows in the sensor unit 4.

[0066] However, when used in a manner of continuously supplying current to the load 3 , an offset drift occurs as described above, and the measured value of the sensor unit 4 includes an offset value caused by the offset drift, and thus may be different from the current value actually supplied to the load 3 .

[0067] 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 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 in the first measurement state.

[0068] Furthermore, when it is determined that the latest measured value has changed from the initial measured value, the control unit 20 controls the switch unit 13 so as to achieve the second measurement state in which the first wiring unit 11 and the second wiring unit 12 are connected. Figure 3 As shown, the control unit 20 controls the first switch 13A so as to conduct the first wiring unit 11, and controls the second switch 13B so as to conduct the second wiring unit 12. The second measurement state is a state for measuring the current flowing in the first wiring unit 11 and the current flowing in the second wiring unit 12 using the sensor unit 4.

[0069] As described above, when both the first wiring section 11 and the second wiring section 12 are turned on, the sensor section 4 outputs the difference between the absolute value of the current of the first wiring section 11 and the absolute value of the current of the second wiring section 12 as a measured value. In addition, as described above, the absolute value of the current of the first wiring section 11 is the same as the absolute value of the current of the second wiring section 12.

[0070] Therefore, in the second measurement state, the current of the first wiring section 11 and the current of the second wiring section 12 cancel each other, and only the measurement value of the bias current based on the bias drift is measured by the sensor section 4. That is, in the second measurement state, the bias current can be measured by the sensor section 4.

[0071] 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 subtracts the measured value of the bias current from the measured value of the sensor unit 4 before the offset correction as the measured value of the sensor unit 4 after the offset correction.

[0072] Thus, when the circuit is used so that current always flows in the sensor unit 4 , an opportunity for offset correction can be obtained, and the occurrence of offset drift can be suppressed.

[0073] Next, the operation of the offset correction device 1 will be described. Figure 4 This is a flowchart showing an example of the flow of processing executed by the offset correction device 1 according to the present embodiment. Figure 4 The processing in is executed when the vehicle including the offset correction device 1 starts to move.

[0074] like Figure 4 As shown, the control unit 20 makes the first wiring unit 11 conductive and the second wiring unit 12 non-conductive (step S101). That is, the control unit 20 controls the switch unit 13 so as to be in the first measurement state.

[0075] After step S101, the control unit 20 uses the sensor unit 4 to measure the initial measurement value (step S102). After measuring the initial measurement value, the control unit 20 monitors the measurement value of the sensor unit 4 and determines whether the latest measurement value has changed from the initial measurement value (step S103). It should be noted that the processing of step S103 may also be performed every time a certain period of time has passed.

[0076] If the result of the determination is that the latest measured value has not changed from the initial measured value (step S103: No), the process of step S103 is repeated. On the other hand, if the latest measured value has changed from the initial measured value (step S103: Yes), the control unit 20 turns on the second wiring unit 12 (step S104). That is, the control unit 20 controls the switch unit 13 so as to set it to the second measurement state.

[0077] Then, the control unit 20 measures the bias current using the sensor unit 4 (step S105). After step S105, the control unit 20 performs offset correction based on the measured value of the bias current (step S106).

[0078] After step S106, the control unit 20 makes the second wiring unit 12 non-conductive (step S107). That is, the control unit 20 controls the switch unit 13 to be in the first measurement state. It should be noted that the process of step S107 may be performed at any time after the bias current is measured by the process of step S105.

[0079] This control ends after step S107. It should be noted that after the process of step S107, the process may return to the process of step S102.

[0080] According to the present embodiment configured as described above, the second wiring section 12 is configured so that the current in the opposite direction to the current in the first wiring section 11 is measured by the sensor section 4. Specifically, the first wiring section 11 has a first measuring portion 11A configured so that the current flows in the first direction, and the second wiring section 12 has a second measuring portion 12C configured so that the current flows in the second direction which is the opposite direction to the first direction.

[0081] Thus, when current flows through both the first wiring portion 11 and the second wiring portion 12 , the sensor portion 4 can measure a current value obtained by subtracting the current flowing through the second wiring portion 12 from the current flowing through the first wiring portion 11 .

[0082] As a result, the sensor unit 4 can easily measure the offset value when the offset drift occurs, so the offset correction can be performed even when the circuit current continues to flow. That is, in this embodiment, the increase of the offset drift can be suppressed and the measurement accuracy of the sensor unit 4 can be improved.

[0083] Furthermore, since the first wiring section 11 and the second wiring section 12 are connected in parallel, even if current flows to both the first wiring section 11 and the second wiring section 12, it has little effect on the current supplied to the load 3. Therefore, the offset correction can be performed while the current is supplied to the circuit.

[0084] In addition, the control unit 20 sets the first measurement state in which the first wiring unit 11 is turned on and the second wiring unit 12 is turned off, and sets the second measurement state in which the first wiring unit 11 and the second wiring unit 12 are turned on based on the measurement result of the sensor unit 4 in the first measurement state. Thus, the occurrence of bias drift is detected based on the change in the measurement value of the sensor unit 4 in the first measurement state, so that the second measurement state can be switched to quickly detect the bias value.

[0085] That is, only by controlling the switch section 13, it is possible to quickly detect the offset value while supplying current to the circuit, thereby achieving a simple structure and simple control.

[0086] Furthermore, since the impedance of the second wiring section 12 is equal to the impedance of the first wiring section 11, the measured value of the sensor section 4 can be used as an offset value when current flows through both the first wiring section 11 and the second wiring section 12. As a result, the offset value can be easily measured.

[0087] In addition, the input line 10A is connected to the power supply 2 of the vehicle, and the output line 10B is connected to the load 3 of the vehicle. When the vehicle is running, the temperature around the vehicle may change due to changes in the surrounding environment. As a result, bias drift may occur easily. Since the vehicle is often in continuous operation, it is necessary to frequently perform bias correction. In particular, in the case of a commercial vehicle, the vehicle-mounted device mounting unit is often in continuous operation even when the vehicle is not running, so the necessity of frequently performing bias correction becomes even higher.

[0088] According to the present embodiment, the offset correction can be performed while the current is being supplied to the circuit. Therefore, when the sensor is mounted on a vehicle, the offset correction can be performed at an appropriate time, and the measurement accuracy of the sensor unit 4 can be easily improved.

[0089] It should be noted that in the above embodiment, the wiring resistances of the first wiring section 11 and the second wiring section 12 are not particularly considered. Specifically, in the above embodiment, the second wiring section 12 has the first non-measurement portion 12A, the second non-measurement portion 12B, and the second measurement portion 12C, and accordingly, its wiring is longer than the first wiring section 11, and the wiring resistance is larger. However, the present invention is not limited to this, and the wiring resistances of the first wiring section 11 and the second wiring section 12 may be equal.

[0090] For example, Figure 5As shown, the first wiring section 11 may also include a non-measurement section 11B connected to the subsequent section of the sensor section 4 in the first measurement section 11A. The non-measurement section 11B is arranged in the non-measurement area of ​​the sensor section 4 and has a length such that the wiring resistance of the first wiring section 11 is equal to the wiring resistance of the second wiring section 12.

[0091] As a result, the impedances of the first wiring portion 11 and the second wiring portion 12 can be made consistent with each other, and thus more accurate offset correction can be performed.

[0092] In addition, 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 turned on in the first measurement state and the second measurement state, but the present invention is not limited thereto.

[0093] For example, it can also be, Figure 6 As shown, the switch section 13 (one switch) is provided only in the second wiring section 12. In this case, in order to make the impedances of the first wiring section 11 and the second wiring section 12 equal, for example, some circuit elements 14 (for example, a resistor element, a switch element fixed in an on state, etc.) can be provided in the first wiring section 11. It should be noted that in this structure, another switch can be provided in the input line 10A or the output line 10B to cut off the supply of power when the operation of the load 3 is stopped.

[0094] In addition, in the above embodiment, the sensor unit 4 measures the current of the first wiring unit 11 as a current in the positive direction, and measures the current of the second wiring unit 12 as a current in the negative direction, but the present invention is not limited to this. For example, the sensor unit may measure the current of the first wiring unit as a current in the negative direction, and measure the current of the second wiring unit as a current in the positive direction.

[0095] In addition, in the above-mentioned embodiment, the offset correction device 1 is mounted on a vehicle, but the present invention is not limited thereto, and may be mounted on a device other than a vehicle. As a device other than a vehicle, any device may be used as long as it is a device having a load that can be operated using electricity. In addition, it is considered that if an offset correction device is provided in a facility such as a factory or a building where a load needs to be operated continuously, the offset correction can be performed during the operation of the load, thereby contributing to the improvement of the measurement accuracy of the sensor unit.

[0096] The above-mentioned embodiments are merely examples of specific implementations of the present invention, and the technical scope of the present invention should not be limited by these embodiments. That is, the present invention can be implemented in various forms without departing from the gist or main features thereof.

[0097] Industrial Applicability

[0098] The offset correction device of the present invention is useful as an offset correction device and an offset correction circuit capable of suppressing an increase in offset drift and improving the measurement accuracy of a sensor unit.

Claims

1. An offset correction device for performing offset correction of a sensor unit, the offset correction device comprising: a first wiring section connected to the input line and the output line and arranged in a measurement area of ​​the sensor section; a second wiring section connected in parallel with the first wiring section and arranged in the measurement area; a switch section that switches at least the second wiring section to one of conducting and non-conducting; and a control unit that controls the switch unit to perform bias correction on the sensor unit, The second wiring portion is arranged so that a current in a direction opposite to a current in the first wiring portion is measured by the sensor portion.

2. The bias correction device according to claim 1, wherein: The first wiring section has a first measuring portion, the first measuring portion being arranged in the measuring region and arranged so that current flows in a first direction. The second wiring portion has: a second measuring portion disposed in the measuring region and arranged so that current flows in a second direction opposite to the first direction; as well as Two parts are respectively connected to both sides of a part of the second measuring part corresponding to the measuring area.

3. The bias correction device according to claim 2, wherein: One of the two parts is connected to a connection point on the input line side of the first wiring section and the second wiring section, The other of the two parts is connected to a connection point on the output line side of the first wiring section and the second wiring section.

4. The bias correction device according to claim 1, wherein: The control unit performs the following steps: controlling the switch section so as to achieve a first measurement state in which the second wiring section is not conductive; controlling the switch section so as to achieve a second measurement state in which the second wiring section is turned on, based on a measurement result of the sensor section in the first measurement state; as well as The offset correction is performed based on the measurement result of the sensor unit in the second measurement state.

5. The bias correction device according to claim 4, wherein: The switch section includes: a first switch that switches the first wiring section to one of conducting and non-conducting; and a second switch that switches the second wiring section to one of conducting and non-conducting. The control section controls the switch section so as to bring the first wiring section into conduction in the first measurement state and in the second measurement state.

6. The bias correction device according to claim 1, wherein: The impedance of the second wiring portion is equal to the impedance of the first wiring portion.

7. The bias correction device according to claim 1, wherein: The input line is connected to the power supply of the vehicle, The output line is connected to a load of the vehicle.

8. An offset correction circuit for performing offset correction of a sensor unit, the offset correction circuit comprising: a first wiring section connected to the input line and the output line and arranged in a measurement area of ​​the sensor section; a second wiring section connected in parallel with the first wiring section and arranged in the measurement area; and a switch section that switches at least the second wiring section to one of conducting and non-conducting, The second wiring portion is arranged so that a current in a direction opposite to a current in the first wiring portion is measured by the sensor portion.

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