Battery voltage measurement circuit

Abstract

To provide a technology that allows for the measurement of the potential of high-voltage circuits in batteries using an inexpensive configuration. [Solution] The voltage measurement circuit 100 disclosed herein comprises a reference power supply 11, 12, a first resistor 21, a second resistor 22, a third resistor 23, and a voltage measuring instrument 30. The reference power supplies 11, 12 apply a predetermined voltage E1. The first resistor 21 and the second resistor 22 have predetermined resistance values ​​Ra1 and are connected in series between the ground 101 of the voltage measurement circuit 100 and the reference power supply 12. The third resistor 23 is connected between the first resistor 21 and the second resistor 22 and to the object to be measured 10 and has a predetermined resistance value Rb. The voltage measuring instrument 30 obtains the potential of the object to be measured 10 based on the potential Vin obtained from the voltage divider point P1 obtained by the first resistor 21 and the second resistor 22.

Description

Technical Field

[0001] The present disclosure relates to a battery voltage measurement circuit.

Background Art

[0002] Japanese Patent No. 4293942 discloses an electric vehicle leakage detection circuit for detecting electric leakage of an assembled battery for an electric vehicle. It is described that such an electric vehicle leakage detection circuit includes an assembled battery, a leakage detection resistor, a voltage detection unit, a leakage detection switch, a voltage detection circuit, and a leakage rendering unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present inventor has sought to make it possible to measure the potential of a high-voltage circuit in a battery with a more inexpensive configuration.

Means for Solving the Problems

[0005] The battery voltage measurement circuit disclosed herein is a voltage measurement circuit that measures the potential of a target to be measured in a circuit to which a battery is connected. The voltage measurement circuit comprises a reference power supply, a first resistor, a second resistor, a third resistor, and a voltage measuring instrument. The reference power supply applies a predetermined voltage. The first and second resistors are connected in series between the ground of the voltage measurement circuit and the reference power supply and have predetermined resistance values. The third resistor is connected between the first and second resistors and to the target to be measured and has predetermined resistance values. The voltage measuring instrument acquires the potential of the target to be measured based on the potentials obtained from the voltage division points obtained by the first and second resistors. According to such a battery voltage measurement circuit, the potential of a high-voltage circuit in a battery can be measured with an inexpensive configuration. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a schematic diagram of circuit 600. [Figure 2] Figure 2 is a schematic diagram of circuit 600A. [Figure 3] Figure 3 is a schematic diagram showing the battery voltage measurement circuit 100. [Figure 4] Figure 4 is a schematic diagram of the equivalent circuit obtained by replacing a part of the measurement circuit in Figure 3 with a Thevenin equivalent circuit. [Figure 5] Figure 5 is a schematic diagram showing a battery voltage measurement circuit 100A. [Figure 6] Figure 6 is a schematic diagram of the equivalent circuit obtained by replacing a part of the measurement circuit in Figure 5 with a Thevenin equivalent circuit. [Figure 7] Figure 7 is a schematic diagram showing the battery voltage measurement circuit 200. [Figure 8] Figure 8 is a schematic diagram showing the battery voltage measurement circuit 300. [Figure 9] Figure 9 is a schematic diagram showing the battery voltage measurement circuit 400. [Modes for carrying out the invention]

[0007] Hereinafter, several embodiments of the technology disclosed herein will be described with reference to the drawings. In the drawings, components and parts that perform the same function are appropriately denoted by the same reference numerals. Furthermore, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships. The technology disclosed herein can be implemented based on the contents disclosed herein and common technical knowledge in the art. Furthermore, the following description is not intended to limit this disclosure to the following forms.

[0008] In this specification, the notation "A~B" indicating a range means "A or greater and B or less." Furthermore, the notation "A~B" shall also encompass the meanings of "greater than A" and "less than B."

[0009] A "battery" may be one installed in a mobility device such as an electric vehicle or a ship. Examples of "electric vehicles" include electric bicycles, electric motorcycles, electric cars, and trains. Examples of electric cars include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), electric buses, and electric trucks. Examples of "ships" include electric tankers. In the following explanation, a "battery voltage measurement circuit" may also be simply referred to as a "voltage measurement circuit."

[0010] Such a mobility device is equipped with a motor that provides power for propelling the device and a drive power supply that outputs power to the high-voltage circuit including the motor. Furthermore, electronic devices such as the ECU mounted on the mobility device are powered through a low-voltage circuit to which a significantly lower voltage is applied than that of the high-voltage circuit including the motor. This invention relates to a voltage measurement circuit for such a mobility device, which includes a circuit for measuring the potential of a target object located in the high-voltage circuit.

[0011] Here, Figure 1 is a schematic diagram of circuit 600. Figure 2 is a schematic diagram of circuit 600A. Circuit 600 shown in Figure 1 and circuit 600A shown in Figure 2 represent, respectively, one embodiment based on the inventor's knowledge, of a circuit for measuring the potential (HV) of a target to be measured in a high-voltage circuit. In this case, the target to be measured is terminal 610 of the high-voltage circuit.

[0012] As shown in Figure 1, circuit 600 comprises resistor 611, resistor 612, voltage measuring instrument 613, and power supply 614 for the device. As shown in Figure 1, resistors 611 and 612 are connected in series between the potential (HV) of terminal 610 of the high-voltage circuit to be measured and a reference potential (GND). A voltage divider point p1 is set between resistors 611 and 612 to divide the potential (HV) of terminal 610 of the high-voltage circuit to be measured. The voltage measuring instrument 613 receives the potential of voltage divider point p1 as input. The voltage measuring instrument 613 is composed of an AD measuring instrument.

[0013] Here, the potential (HV) of terminal 610 of the high-voltage circuit is assumed to fluctuate between, for example, -200V and +200V relative to the reference potential (GND). Terminal 610 of the high-voltage circuit to be measured can be located at an appropriate position within the high-voltage circuit. The voltage measuring instrument 613 is a device driven by a low voltage of 5V. The power supply 614 for the device connected to the voltage measuring instrument 613 is configured to apply a low voltage of 5V relative to the reference potential (GND).

[0014] For example, the resistance value Rb of the resistor 611 is 990 kΩ, and the resistance value Ra of the resistor 612 is 10 kΩ. In this case, at the voltage dividing point p1, the potential (HV) at the terminal 610 of the high-voltage circuit is divided to 1 / 100 and input to the voltage measuring instrument 613. For example, if the potential (HV) at the terminal 610 of the high-voltage circuit to be measured is approximately 200 V relative to the reference potential (GND), it is input to the voltage measuring instrument 613 as approximately 2 V. For this reason, in the circuit 600 shown in FIG. 1, since the resistance value Rb of the resistor 611 is set to 990 kΩ, which is large relative to the resistor 612, a large potential is not applied from the terminal 610 of the high-voltage circuit to the voltage measuring instrument 613.

[0015] Further, when the potential (HV) at the terminal 610 of the high-voltage circuit to be measured varies between -200 V and +200 V, the potential Vin acquired by the voltage measuring instrument 613 is Vin = HV × {Ra / (Ra+Rb)} = (-200 V to +200 V) × (1 / 100) = -2 V to +2 V. The voltage measuring instrument 613 can detect a positive potential among these potentials.

[0016] In the circuit 600A shown in FIG. 2, a voltage measuring instrument 623 which is an AD measuring instrument capable of measuring positive potentials and negative potentials is used. In this case, the voltage measuring instrument 623 is preferably connected to the first power supply 621 which is a positive power supply and the second power supply 622 which is a negative power supply. Here, when the power supply for the device is 5 V, the first power supply 621 can be set to 2.5 V, and the second power supply 622 can be set to -2.5 V.

[0017] In this case, the potential Vin at the voltage dividing point p2, which has been divided by the resistor 611 and the resistor 612, is acquired by the voltage measuring instrument 623. Here, when the potential (HV) at the terminal 610 of the high-voltage circuit varies between -200 V and +200 V, the potential Vin after voltage division according to the ratio of the resistance values of the resistor 611 and the resistor 612 varies between -2 V and +2 V. As described above, in the embodiment shown in FIG. 2, in order to make it possible to measure the positive potential and the negative potential at the voltage dividing point p2 that varies between -2 V and +2 V, the voltage measuring instrument 623 which is an AD measuring instrument capable of measuring positive potentials and negative potentials is used.

[0018] To the voltage measuring instrument 623, in addition to the first power supply 621 which is at a positive potential, the second power supply 622 which is at a negative potential is connected. The potential at the voltage dividing point p2 measured by the voltage measuring instrument 623 is converted according to the ratio of the resistance values of the resistor 611 and the resistor 612. Therefore, the voltage measuring instrument 623 can measure the positive potential and the negative potential of the potential (HV) at the terminal 610 of the high-voltage circuit even when the potential varies between -200V and +200V. On the other hand, in the configuration as shown in FIG. 2, it is necessary to add the second power supply 622 at a negative potential in addition to the first power supply 621 at a positive potential. Preparing a negative potential in addition to such a positive potential may incur costs. Meanwhile, the present inventor has conceived that when the potential (HV) at the terminal 610 of the high-voltage circuit varies, for example, between -200V and +200V, it is desirable to measure this potential with a lower-cost configuration without preparing a negative potential.

[0019] <Battery Voltage Measurement Circuit 100> FIG. 3 is a schematic diagram showing the battery voltage measurement circuit 100. The voltage measurement circuit 100 shown in FIG. 3 is configured to measure the potential of the measurement target 10 without preparing a negative potential. In the embodiment shown in FIG. 3, the measurement target 10 is assumed to be a high-voltage power supply whose output varies within the range of -200V to +200V with respect to the ground (GND) 101 which is the reference potential (0V).

[0020] Here, as shown in FIG. 3, the voltage measurement circuit 100 includes reference power supplies 11 and 12, a first resistor 21, a second resistor 22, a third resistor 23, and a voltage measuring instrument 30.

[0021] (Reference Power Supplies 11, 12) Reference power supplies 11 and 12 are power supplies that apply a predetermined voltage E1 to the voltage measurement circuit 100. A reference voltage, which serves as the reference for the voltage measurement circuit 100, is applied from the reference power supplies 11 and 12. The reference power supplies 11 and 12 are composed of circuits that output a reference voltage, which serves as the reference for the voltage measurement circuit 100. In the configuration shown in Figure 3, the voltage of the reference power supplies 11 and 12 is 5V. It is preferable that the reference power supplies 11 and 12 are configured to have the same voltage applied from the same power source, for example. Here, the voltage value of the reference power supply 12 is denoted as E1.

[0022] (1st resistor 21, 2nd resistor 22) The first resistor 21 and the second resistor 22 are connected in series between the ground (GND) 101 of the voltage measurement circuit 100 and the reference power supply 12, as shown in Figure 3. The first resistor 21 and the second resistor 22 are resistors that divide the voltage output by the reference power supply 12. In this case, the first resistor 21 and the second resistor 22 are resistors with the same resistance value Ra1. In the configuration shown in Figure 3, the resistance value Ra1 of the first resistor 21 and the second resistor 22 is set to 20kΩ each.

[0023] (3rd resistor 23) The third resistor 23 is connected between the first resistor 21 and the second resistor 22, and to the object being measured 10. In the configuration shown in Figure 3, the resistance value Rb of the third resistor 23 is set to be significantly larger than that of the first resistor 21 and the second resistor 22. The resistance value Rb of the third resistor 23 is set to 990 kΩ.

[0024] (Voltage measuring instrument 30) The voltage measuring instrument 30 acquires the potential HV to be measured based on the potential Vin obtained from the voltage divider point P1, which is divided by the first resistor 21 and the second resistor 22. In this embodiment, the voltage measuring instrument 30 is configured by, for example, an ASIC (Application Specific Integrated Circuit). The ASIC is a dedicated integrated circuit for detecting the voltage of batteries when multiple batteries are connected. The ASIC may, for example, be equipped with an AD measuring instrument using general-purpose input / output terminals (GPIO: General-Purpose Input / Output) that have an AD conversion function.

[0025] In the configuration shown in Figure 3, the voltage measuring instrument 30 is equipped with an AD measuring instrument. The device power supply 11 attached to the voltage measuring instrument 30 is the power supply for the AD measuring instrument. The AD measuring instrument is configured to measure positive potential, and the device power supply 11 is a positive power supply. In this embodiment, an AD measuring instrument capable of measuring within the range of 0V to 5V is used. In the configuration shown in Figure 3, the voltage applied by the device power supply 11 is 5V. Any voltage measuring instrument that can be used for this type of application can be used without particular limitations. The voltage measuring instrument 30 outputs to, for example, a microcontroller, and the potential of the object to be measured 10 is obtained by a predetermined calculation. Here, part of the measurement circuit in Figure 3 is replaced with an equivalent circuit based on Thevenin's theorem.

[0026] Figure 4 is a schematic diagram of an equivalent circuit in which a portion of the measurement circuit in Figure 3 is replaced with a Thevenin equivalent circuit. Specifically, in Figure 4, the measurement circuit shown in frame F1, which is an excerpt between A and B in Figure 3, is replaced with the Thevenin equivalent circuit shown in frame F2. In this embodiment, although not shown, the voltage measurement circuit 100 is connected to the circuit to which the battery of the electric vehicle is connected. The measurement circuit in frame F1 shown in Figure 3 is replaced with a voltage source with internal resistance based on Thevenin's theorem. That is, the measurement circuit in frame F1 in Figure 3 is replaced with a circuit having an equivalent resistance 21a (internal resistance based on Thevenin's theorem) and an equivalent power supply 12a (voltage source based on Thevenin's theorem), as shown in frame F2 in Figure 4. Here, the voltage value of the equivalent power supply 12a is V0. Also, the resistance value of the equivalent resistance 21a is R0.

[0027] In Figure 4, the equivalent voltage V0 of power supply 12a is V0 = E1 × {Ra1 / (Ra1+Ra1)} = 5V × (1 / 2) = 2.5V. Also, the equivalent resistance R0 of resistor 21a is R0 = Ra1 × (1 / 2) = 20kΩ × (1 / 2). In other words, the equivalent resistance R0 is R0 = 10kΩ. The potential Vin at voltage divider point P1 is Vin = V0 + (HV - V0) × {R0 / (R0+Rb)}.

[0028] Therefore, Vin = V0 + (HV - V0) × {R0 / (R0 + Rb)} = 2.5V + (HV - 2.5V) × {10 / (10 + 990)}. Here, if HV fluctuates between -200V and +200V, then 2.5V + {(HV - 2.5V) × (1 / 100)} = 2.5V + (-2.025V to +1.975V), and the potential Vin at the voltage divider point P1 becomes Vin = 0.475V to 4.475V.

[0029] In other words, this circuit is designed so that the potential Vin at the voltage divider point P1 is offset by -2.5V from the potential HV of the object being measured 10, and then further offset by +2.5V with Gain 1 / 100 before being output. As a result, the potential HV of the object being measured 10, which fluctuates between -200V and +200V, is output at 0.475V to 4.475V.

[0030] As a result, it becomes possible to use a voltage measuring instrument 30 with a measurement range of 0 to 5V. With this configuration of the voltage measuring circuit 100, even if the potential (HV) of the object to be measured 10 fluctuates between -200V and +200V, the voltage value of the object to be measured acquired by the AD measuring instrument of the voltage measuring instrument 30 will be a positive value within 0 to 5V. Therefore, the AD measuring instrument of the voltage measuring instrument 30 only needs to be capable of measuring positive potential. For this reason, the voltage measuring circuit 100 does not require the provision of negative potential and can measure the potential (HV) of the object to be measured 10 that fluctuates between -200V and +200V using a more inexpensive AD measuring instrument. Thus, the battery voltage measuring circuit 100 allows for the measurement of the potential of the high-voltage circuit in the battery with an inexpensive configuration.

[0031] In this way, the voltage measuring instrument 30 measures the potential Vin at the voltage division point P1. Based on the potential Vin at the voltage division point P1 measured by the voltage measuring instrument 30, the potential HV of the object to be measured 10 is obtained. Here, the resistance values ​​Ra1 of the first resistor 21 and the second resistor 22, the resistance value Rb of the third resistor 23, and the voltage value E1 of the reference power supply 12 are known. Then, the voltage value V0 of the equivalent power supply 12a, the resistance value R0 of the equivalent resistor 21a, and the third resistor Rb are obtained from the equivalent circuit substituted by Thevenin's theorem. For this reason, the relationship between the potential Vin at the voltage division point P1 measured by the voltage measuring instrument 30 and the potential HV of the object to be measured 10 is a predetermined relationship. Therefore, the potential HV of the object to be measured 10 is obtained by a predetermined calculation based on the potential Vin at the voltage division point P1 measured by the voltage measuring instrument 30. For example, the potential HV of the object to be measured 10 is determined by calculations performed by a computer such as a microcontroller, based on the potential Vin of the voltage divider point P1 measured by the voltage measuring instrument 30.

[0032] The offset amount of the potential Vin at the voltage divider point P1 and the Gain are determined by the resistance values ​​Ra1 of the first resistor 21 and the second resistor 22, the resistance value Rb of the third resistor 23, and the voltage value E1 of the reference power supply 12. Therefore, by appropriately selecting the resistance values ​​Ra1 of the first resistor 21 and the second resistor 22, the resistance value Rb of the third resistor 23, and the voltage value E1 of the reference power supply 12 according to the potential (HV) of the object to be measured 10, a wider range of potential (HV) of the object to be measured 10 can be measured. The high-voltage circuit proposed here is also applicable to high-voltage circuits in high-power batteries used in large, electrified means of transport and transportation such as EV buses, EV trucks, and EV tankers. Thus, the resistance values ​​Ra1 of the first resistor 21 and the second resistor 22, the resistance value Rb of the third resistor 23, and the voltage value E1 of the reference power supply 12 are not limited to the above embodiment, but may be determined according to the voltage output at the object to be measured 10.

[0033] For example, in order to measure the potential of the object to be measured 10 with high precision, it is necessary to improve the precision of each component of the voltage measurement circuit 100. In such cases, high-precision components are needed for the resistor, AD measuring instrument, and the reference power supply 11 used for the AD measuring instrument. However, from the standpoint of cost, it is preferable to use a general-purpose power supply with standard output precision for the reference power supply 12. Using a high-precision power supply may require additional components in some cases, which is not economical. On the other hand, if a general-purpose power supply with standard output precision is used as the reference power supply 12, errors may occur in the output voltage due to the influence of temperature characteristics, etc. In such cases, there is a risk that errors may occur in the potential of the object to be measured 10 acquired by the voltage measuring instrument 30. The inventors of this invention want to acquire the potential of the object to be measured 10 with high precision even when a general-purpose power supply with standard output precision is used as the reference power supply 12.

[0034] <Battery voltage measurement circuit 100A> Figure 5 is a schematic diagram showing the battery voltage measurement circuit 100A. The voltage measurement circuit 100A shown in Figure 5 is configured to measure the potential of the device to be measured 10 without providing a negative potential. In the configuration shown in Figure 5, the device to be measured 10 is assumed to be a high-voltage power supply whose output fluctuates within a range of 200V relative to the ground (GND) 101, which is the reference potential (0V). Figure 6 is a schematic diagram of an equivalent circuit in which a part of the measurement circuit in Figure 5 is replaced with a Thevenin equivalent circuit. Specifically, in Figure 6, the measurement circuit shown in frame F1, which is an excerpt between A and B in Figure 5, is replaced with the Thevenin equivalent circuit shown in frame F2. In this embodiment, although not shown, the voltage measurement circuit 100A is connected to the circuit to which the battery of the electric vehicle is connected.

[0035] (Switch 150) In the configuration shown in Figure 5, the voltage measurement circuit 100A further includes a switch 102. The switch 102 is connected between the device to be measured 10 and the voltage divider point P1. The switch 102 is also configured to switch between connecting and disconnecting the first resistor 21 and the second resistor 22 and the third resistor 23. Any switch suitable for this type of application can be used without particular limitations as the switch 102. The switch 102 may be, for example, a photoMOS.

[0036] For example, in the configuration shown in Figure 5, an error of approximately +0.1V may occur in the reference power supply 12, which is supposed to apply a voltage of 5V. In such a case, in Figure 6, an error of approximately +0.05V will occur in the equivalent power supply 12a, which is supposed to apply a voltage of 2.5V. In such cases, an error may occur in the potential Vin of the object to be measured 10, which is acquired by the voltage measuring instrument 30.

[0037] As shown in Figure 5, the voltage measurement circuit 100A is configured so that the connection of the resistor voltage divider (-Rb-HV) can be disconnected by switch 102. In this case, the voltage value across the voltage divider resistor (Vinoff) measured when switch 102 is turned OFF and the connection is disconnected can be used as the equivalent voltage value V0 of the Thevenin equivalent circuit.

[0038] For example, suppose the error in the voltage E1 of the reference power supply 12 is +0.1V, and the voltage E1 of the reference power supply 12 is 5.1V. In this case, as shown in Figure 5, switch 102 is turned OFF to obtain Vinoff. In this case, Vinoff = E1 × {Ra1 / (Ra1+Ra1)} = (5V+0.1V) × (1 / 2) = 2.55V. This value is taken as the voltage value V0 of the equivalent power supply 12a.

[0039] As shown in Figure 6, when switch 102 is ON, the voltage value (Vinon) of the object to be measured 10 acquired by the voltage measuring instrument 30 is Vinon = V0 + (HV - V0) × {R0 / (R0 + Rb)} = Vinoff + (HV - Vinoff) × {R0 / (R0 + Rb)} = 2.55V + (200V - 2.55V) × {10 / (10 + 990)} = 4.5245V. Therefore, the potential of the object to be measured 10 is HV = Vinoff + (Vinon - Vinoff) × {(R0 + Rb) / R0} = 2.55V + (4.5245V - 2.55V) × 100 = 200V. Even if there is an error in the output of the reference power supply 12, an accurate value can be obtained as the potential of the object to be measured 10.

[0040] Thus, in the voltage measurement circuit 100A, Vinoff can be obtained by turning switch 102 OFF, allowing the effect of the error in the voltage E1 of the reference power supply 12 to be measured. Vinoff corresponds to the voltage V0 of the reference power supply 12a in Thevenin's equivalent circuit (see Figure 6). For example, if the error in the voltage E1 of the reference power supply 12 is +0.1V and the voltage E1 of the reference power supply 12 is 5.1V, then the voltage V0 of the reference power supply 12a in Thevenin's equivalent circuit will be 2.55V. Note that the values ​​of Vinoff and the voltage V0 of the reference power supply 12a will vary according to the error in the voltage E1 of the reference power supply 12.

[0041] As shown in Figure 5, the voltage measurement system 100A is equipped with a switch 102 for switching the connection and disconnection between the first resistor 21 and the second resistor 22 and the third resistor 23. Therefore, the potential of the measurement target 10 can be calculated with greater accuracy from the voltage value (Vinon) of the voltage divider resistor measured when connected to the measurement target 10, which is obtained when the switch 102 is turned ON, and the voltage value V0 (corresponding to Vinoff) of the equivalent power supply 12a, which is obtained when the switch 102 is turned OFF. In other words, as described above, in the voltage measurement circuit 100A, the voltage value measured by the voltage measuring instrument 30 when the switch 102 is OFF is the voltage value V0 of the equivalent power supply 12a of the Thevenin equivalent circuit shown in Figure 6. And the voltage value V0 of the equivalent power supply 12a can be measured. Therefore, the voltage (Vinon) of the measurement target 10 measured when the switch 102 is ON can be obtained with high accuracy.

[0042] In addition to the effects described above, the voltage measurement system 100A allows the switch 102 to be turned OFF when not measuring. For this reason, the voltage measurement system 100A can be preferably used from the viewpoint of suppressing leakage current of high-voltage systems and providing insulation from high-voltage systems.

[0043] <Battery voltage measurement circuit 200> Figure 7 is a schematic diagram showing the battery voltage measurement circuit 200. The voltage measurement circuit 200 is applied to the total voltage detection circuit.

[0044] In Figure 7, the configuration of switches 202A, 202B, device power supplies 211, 211A, reference power supply 212, first resistors 221A, 221B, second resistors 222A, 222B, third resistors 223A, 223B, and voltage measuring instruments 230, 230A may be the same as in the above embodiment, and a detailed explanation is omitted.

[0045] In the configuration shown in Figure 7, the voltage measurement circuit 200 further includes external equipment 203, a precharge resistor 224, a power supply 240A, a power supply unit 240, a total of positive terminals 250, a total of negative terminals 252, contactors 260A, 260B, 260C, and a fuse 270. Each component will be described below.

[0046] (External device 203) As shown in Figure 7, in this embodiment, the voltage measurement circuit 200 is connected in series to the external device 203 via a total positive terminal 250 and a total negative terminal 252. In the configuration shown in Figure 7, the voltage measurement circuit 200 is connected to the external device 203 of the mobility device. The external device 203 may be, for example, a load such as a motor or inverter of the mobility device. Power is supplied to the external device 203 from the power supply unit 240 of the voltage measurement circuit 200.

[0047] (Power supply unit 240) As shown in Figure 7, the power supply unit 240 comprises multiple power supplies 240A. The power supply unit 240 is, for example, a battery for mobility. Although not shown in the figure, a power supply 240A here has an electrode body and a sealed case. A power supply 240A is an energy storage device from which electrical energy can be extracted. A power supply 240A includes a rechargeable battery that can be repeatedly charged and discharged by the movement of a charge carrier between a pair of electrodes (positive and negative electrodes) via an electrolyte. Examples of power supplies 240A include lithium-ion rechargeable batteries and nickel-metal hydride batteries.

[0048] The connection configuration of the multiple 240A power supplies is not particularly limited. The multiple 240A power supplies are electrically connected to each other, for example, via busbars, and constitute a power supply unit 240. The multiple 240A power supplies may be connected in series, in parallel, or a combination of series and parallel connections. In the configuration shown in Figure 7, the multiple 240A power supplies are connected in series.

[0049] The number of power supply units 240 in the voltage measurement circuit 200 may be one or two or more. In the configuration shown in Figure 7, the voltage measurement circuit 200 is equipped with four power supply units 240. The number of power supplies 240A constituting the power supply unit 240 may be, for example, five or more, ten or more, or twenty or more. The upper limit of the number of power supplies 240A constituting the power supply unit 240 may be, for example, 40 or less, or 30 or less. In the configuration shown in Figure 7, the power supply unit 240 is composed of 20 power supplies 240A.

[0050] (Total positive terminals: 250, Total negative terminals: 252) In the configuration shown in Figure 7, the total positive terminal 250 is comprised of multiple positive terminals in the power supply unit 240. The total positive terminal 250 is a positive terminal that is open for connection to an external device 203. The total negative terminal 252 is comprised of multiple negative terminals in the power supply unit 240. The total negative terminal 252 is a negative terminal that is open for connection to an external device 203. In the configuration shown in Figure 7, the third resistor 223A is electrically connected to the total positive terminal 250. The third resistor 223B is electrically connected to the total negative terminal 252.

[0051] (Contactors 260A, 260B, 260C) In the configuration shown in Figure 7, the voltage measurement circuit 200 includes contactors 260A, 260B, and 260C. Here, contactor 260A is a pre-charge contactor. Contactor 260B is the positive terminal contactor. Contactor 260C is the negative terminal contactor. Contactors 260A, 260B, and 260C are configured to switch the connection between the external device 203 and the power supply unit 240.

[0052] In the configuration shown in Figure 7, the contactor 260A is included in the pre-charge circuit C together with the pre-charge resistor 224. The pre-charge circuit C is a circuit in which the pre-charge resistor 224 and the contactor 260A are connected in series. The pre-charge circuit C is connected to the positive terminal side of the power supply unit 240. The external device 203 is connected to the voltage measurement circuit 200 via the pre-charge circuit C. The pre-charge circuit C is a circuit that prevents inrush current from flowing to the external device 203 when power is supplied from the power supply unit 240 to the external device 203. Furthermore, because the pre-charge resistor 224 is provided in the pre-charge circuit C, the external device 203 is supplied with power from the power supply unit 240 at a low current. This effectively prevents a large current from flowing to the external device 203.

[0053] Before the external device 203 is started, contactors 260A, 260B, and 260C are in the open state. When the voltage measurement circuit 200 is started, contactors 260A and 260C are switched to the closed state. Then, after precharging is complete, contactor 260A is switched to the open state and contactor 260B is switched to the closed state. In this way, power is supplied from the power supply unit 240 to the external device 203.

[0054] (Fuse 270) The fuse 270 is configured to blow when a current exceeding a predetermined amount (e.g., a short-circuit current) flows through the voltage measurement circuit 200. The fuse 270 may be configured to blow when a current of 1000A or more flows through it. In the configuration shown in Figure 7, the fuse 270 is located at the end of total minus 252. The fuse 270 is connected in series with the contactor 260C. Any fuse suitable for this type of application can be used as the fuse 270 without any particular limitations.

[0055] In the configuration shown in Figure 7, the measurement targets are point P2 between the external device 203 and the total positive terminal 250, and point P3 between the external device 203 and the total negative terminal 252. In this embodiment, the voltage measurement circuit 200 measures the potential at point P2 and the potential at point P3.

[0056] In Figure 7, when the ground 201 (GND) of the ASIC constituting the voltage measuring instrument 240A is used as the reference (i.e., set to 0V), when both the positive contactor 260B and the negative contactor 260C are switched to the closed state, the potential at point P2 becomes approximately +200V, and the potential at point P3 becomes approximately -200V. Furthermore, when the positive contactor 260B is switched to the closed state and the negative contactor 260C is switched to the open state, the potentials at both points P2 and P3 become approximately +200V. And when the negative contactor 260C is switched to the closed state and the positive contactor 260B is switched to the open state, the potentials at both points P2 and P3 become approximately -200V. In other words, in the voltage measurement circuit 200, the potential at point P2 and the potential at point P3 are both approximately -200V to +200V relative to the ASIC ground 201.

[0057] As shown in Figure 7, the voltage measurement circuit 200 includes a reference power supply 212, a first resistor 221A, a second resistor 222A, and a third resistor 223A. The first resistor 221A and the second resistor 222A are connected in series between the ground 201 and the reference power supply 212, and are configured to divide the voltage output by the reference power supply 212 at the voltage division point P1A.

[0058] The voltage measurement circuit 200 also includes a reference power supply 212, a first resistor 221B, and a second resistor 222B. The first resistor 221B and the third resistor 222B are connected in series between the ground 201 and the reference power supply 212, and are configured to divide the voltage output by the reference power supply 212 at the voltage division point P1B.

[0059] The potentials at voltage divider point P1A and voltage divider point P1B are obtained by voltage measuring instrument 230A.

[0060] Here, although not shown in the diagram, in the equivalent circuit obtained by replacing the area around the reference power supply 212, the first resistor 221A, and the second resistor 222A in Figure 7 with a Thevenin equivalent circuit, the equivalent resistor is 221a (internal resistance based on Thevenin's theorem), and the equivalent power supply is 212a (voltage source based on Thevenin's theorem). The voltage value of the equivalent power supply 212a is V0. The resistance value of the equivalent resistor 221a is R0.

[0061] In this equivalent circuit, the voltage value V0 of the equivalent power supply 212a is V0 = E1 × {Ra1 / (Ra1+Ra1)} = 5V × (1 / 2) = 2.5V. Also, the resistance value R0 of the equivalent resistor 221a is R0 = Ra1 × (1 / 2) = 20kΩ × (1 / 2). In other words, the equivalent resistance R0 is R0 = 10kΩ. The potential Vin at the voltage divider point P1A is Vin = V0 + (HV - V0) × {R0 / (R0+Rb)}. Here, Ra1 = 20kΩ and Rb = 990kΩ.

[0062] Therefore, Vin = V0 + (HV - V0) × {R0 / (R0 + Rb)} = 2.5V + (HV - 2.5V) × {10 / (10 + 990)}. Here, if HV fluctuates between -200V and +200V, then 2.5V + {(HV - 2.5V) × (1 / 100)} = 2.5V + (-2.025V to +1.975V), and the potential Vin at the voltage divider point P1A becomes Vin = 0.475V to 4.475V.

[0063] In other words, this circuit outputs the potential Vin at voltage divider point P1A after the measured potential (HV) is offset by -2.5V, and then further offset by +2.5V with Gain 1 / 100. As a result, the measured potential (HV), which fluctuates between -200V and +200V, is output at a range of 0.475V to 4.475V.

[0064] Similarly, for the potential Vin at the voltage divider point P1B, the potential (HV) of the measured object, which fluctuates between -200V and +200V, is output in the range of 0.475V to 4.475V.

[0065] The voltage measurement circuit 200 allows the use of a voltage measuring instrument 230A with a measurement range of 0 to 5V. With the configuration of this voltage measurement circuit 200, even if the potential (HV) of points P2 and P3 fluctuates between -200V and +200V, the potential of the target to be measured acquired by the AD measuring instrument of the voltage measuring instrument 230A will be a positive value within the range of 0 to 5V. Therefore, the AD measuring instrument of the voltage measuring instrument 230A only needs to be capable of measuring positive potential. Thus, the voltage measurement circuit 200 does not require the provision of negative potential and can measure the potential (HV) of a target to be measured that fluctuates between -200V and +200V using a more inexpensive AD measuring instrument. In this way, the battery voltage measurement circuit 200 allows the potential of the high-voltage circuit in a battery to be measured with an inexpensive configuration.

[0066] <Battery voltage measurement circuit 300> Figure 8 is a schematic diagram showing the battery voltage measurement circuit 300. The voltage measurement circuit 300 is applied to the leakage current detection circuit.

[0067] In Figure 8, the configuration of switches 302A, 302B, device power supplies 311, 311A, 311B, reference power supplies 312A, 312B, first resistors 321A, 321B, second resistors 322A, 322B, third resistors 323A, 323B, precharge resistor 324, voltage measuring instruments 330, 330A, 330B, power supply 340A, power supply unit 340, contactors 360A, 360B, 360C, and fuse 370 may be the same as in the above embodiment, and a detailed explanation is omitted.

[0068] In the configuration shown in Figure 8, the voltage measurement circuit 300 further includes leakage current detection resistors 325A and 325B.

[0069] (Resistors for detecting leakage current: 325A, 325B) In the configuration shown in Figure 8, the voltage measurement circuit 300 includes a power supply unit 340 to which multiple power supplies 340A are electrically connected. The positive or negative side of the power supply unit 340 is electrically isolated from the ground LV_GND, which is the grounding point. In this embodiment, when a leakage current occurs on the positive side, the leakage resistor 325A is connected to the positive side of the power supply unit 340 and the ground LV_GND, which is the grounding point. When a leakage current occurs on the negative side, the leakage resistor 325B is connected to the negative side of the power supply unit 340 and the ground LV_GND, which is the grounding point. In addition, the third resistors 323A and 323B are each connected to the ground LV_GND, which is the grounding point.

[0070] In the configuration shown in Figure 8, the object of measurement is the ground LV_GND. In this embodiment, the voltage measurement circuit 300 measures the potential of the ground LV_GND through the leakage resistors 325A and 325B. For example, in Figure 8, when a leakage current occurs, abnormal leakage currents I1 and I2 flow through the voltage measurement circuit 300.

[0071] In Figure 8, when the ground (GND) 301A of ASIC1, which constitutes the voltage measuring instrument 330A, is used as the reference (i.e., set to 0V), if the leakage resistor 325A is connected to HV+, the potential at ground LV_GND will be approximately +100V at most. If the leakage resistor 325B is connected to HV-, the potential at ground LV_GND will be approximately -300V at most. In other words, in the voltage measuring circuit 300, the potential at ground LV_GND will be approximately -300V to +100V with respect to the ground 301A of ASIC1.

[0072] Furthermore, in Figure 8, when the ground (GND) 301B of the ASIC2 constituting the voltage measuring instrument 330B is used as the reference (i.e., set to 0V), if the leakage resistor 325A is connected to HV+, the potential at ground LV_GND will be approximately +300V at most. If the leakage resistor 325B is connected to HV-, the potential at ground LV_GND will be approximately -100V at most. In other words, in the voltage measuring circuit 300, the potential at ground LV_GND will be approximately -100V to +300V with respect to the ground 302A of the ASIC2.

[0073] As shown in Figure 8, the voltage measurement circuit 300 includes a reference power supply 312A, a first resistor 321A, a second resistor 322A, and a third resistor 323A on the positive side. The first resistor 321A and the second resistor 322A are connected in series between the ground 301A and the reference power supply 312A, and are configured to divide the voltage output by the reference power supply 312A at the voltage divider point P1A.

[0074] Furthermore, the voltage measurement circuit 300 includes a reference power supply 312B, a first resistor 321B, and a second resistor 322B on the negative terminal side. The first resistor 321B and the second resistor 322B are connected in series between the ground 301B and the reference power supply 312B, and are configured to divide the voltage output by the reference power supply 312B at the voltage division point P1B.

[0075] The potentials at voltage divider point P1A and voltage divider point P1B are obtained by voltage measuring instruments 330A and 330B, respectively.

[0076] Here, although not shown in the diagram, in the equivalent circuit obtained by replacing the area around the reference power supply 312A, the first resistor 321A, and the second resistor 322A in Figure 8 with a Thevenin equivalent circuit, the equivalent resistor is 321a (internal resistance based on Thevenin's theorem), and the equivalent power supply is 312a (voltage source based on Thevenin's theorem). Also, the voltage value of the equivalent power supply 312a is V0. Also, the resistance value of the equivalent resistor 321a is R0.

[0077] In this equivalent circuit, the voltage value V0 of the equivalent power supply 312a is V0 = E1 × {Ra1 / (Ra1+Ra1)} = 5V × (1 / 2) = 2.5V. Also, the resistance value R0 of the equivalent resistor 321a is R0 = Ra1 × (1 / 2) = 10kΩ × (1 / 2). In other words, the equivalent resistance R0 is R0 = 5kΩ. The potential Vin at the voltage divider point P1A is Vin = V0 + (HV - V0) × {R0 / (R0+Rb)}. Here, Ra1 = 10kΩ and Rb = 995kΩ.

[0078] Therefore, Vin = V0 + (HV - V0) × {R0 / (R0 + Rb)} = 2.5V + (HV - 2.5V) × {5 / (5 + 995)}. Here, if HV fluctuates between -300V and +100V, then 2.5V + {(HV - 2.5V) × (1 / 200)} = 2.5V + (-1.5125V to +0.4875V), and the potential Vin at the voltage divider point P1A becomes Vin = 0.9875V to 2.9875V.

[0079] In other words, this circuit outputs the potential Vin at voltage divider point P1A after the measured potential (HV) is offset by -2.5V, and then further offset by +2.5V with Gain 1 / 200. As a result, the measured potential (HV), which fluctuates between -300V and +100V, is output at a range of 0.9875V to 2.9875V.

[0080] Although not shown in the diagram, in the equivalent circuit obtained by replacing the area around the reference power supply 312B, the first resistor 321B, and the second resistor 322B in Figure 8 with a Thevenin equivalent circuit, the equivalent resistor is 321b (internal resistance based on Thevenin's theorem) and the equivalent power supply is 312b (voltage source based on Thevenin's theorem). The voltage value of the equivalent power supply 312b is V0. The resistance value of the equivalent resistor 321b is R0.

[0081] In this equivalent circuit, the voltage value V0 of the equivalent power supply 312b is V0 = E1 × {Ra1 / (Ra1+Ra1)} = 5V × (1 / 2) = 2.5V. Also, the resistance value R0 of the equivalent resistor 321b is R0 = Ra1 × (1 / 2) = 10kΩ × (1 / 2). In other words, the equivalent resistance R0 is R0 = 5kΩ. The potential Vin at the voltage divider point P1B is Vin = V0 + (HV - V0) × {R0 / (R0+Rb)}. Here, Ra1 = 10kΩ and Rb = 995kΩ.

[0082] Therefore, Vin = V0 + (HV - V0) × {R0 / (R0 + Rb)} = 2.5V + (HV - 2.5V) × {5 / (5 + 995)}. Here, if HV fluctuates between -100V and +300V, then 2.5V + {(HV - 2.5V) × (1 / 200)} = 2.5V + (-0.5125V to +1.4875V), and the potential Vin at the voltage divider point P1B becomes Vin = 1.9875V to 3.9875V.

[0083] In other words, this circuit outputs the potential Vin at voltage divider point P1B after the measured potential (HV) is offset by -2.5V, and then further offset by +2.5V with Gain 1 / 200. As a result, the measured potential (HV), which fluctuates between -100V and +300V, is output at 1.9875V to 3.9875V.

[0084] The voltage measurement circuit 300 allows the use of voltage measuring instruments 330A and 330B, which have a measurement range of 0 to 5V. With the configuration of this voltage measurement circuit 300, even if the potential (HV) of the ground LV_GND fluctuates between -300V and +100V or between -100V and +300V, the potential of the target to be measured acquired by the AD measuring instrument of the voltage measuring instruments 330A and 330B will be a positive value within the range of 0 to 5V. Therefore, the AD measuring instrument of the voltage measuring instruments 330A and 330B only needs to be capable of measuring positive potential. For this reason, the voltage measurement circuit 300 does not require the provision of negative potential and can measure the potential (HV) of a target to be measured that fluctuates between -300V and +100V using an AD measuring instrument that can be procured at a lower cost. Thus, the battery voltage measurement circuit 300 allows the potential of the high-voltage circuit in the battery to be measured with an inexpensive configuration.

[0085] <Battery voltage measurement circuit 400> Figure 9 is a schematic diagram showing the battery voltage measurement circuit 400. The voltage measurement circuit 400 is applied to the fuse blowout detection circuit.

[0086] In Figure 9, the configuration of the switch 402, external equipment 403, power supplies for the device 411, 411A, reference power supply 412, first resistor 421, second resistor 422, third resistor 423, precharge resistor 424, voltage measuring instruments 430, 430A, power supply 440A, power supply unit 440, contactors 460A, 460B, 460C, and fuse 470 may be the same as in the above embodiment, and a detailed explanation is omitted.

[0087] In the configuration shown in Figure 9, the voltage measurement circuit 400 includes a power supply unit 440 to which multiple power supplies 460A are electrically connected. The voltage measurement circuit 400 includes a fuse 470 connected to the negative terminal side of the power supply unit 440 and to the third resistor 423.

[0088] In the configuration shown in Figure 9, the object to be measured is the fuse 470. In this embodiment, the voltage measurement circuit 400 measures the potential of the output of the fuse 470.

[0089] In Figure 9, when the ground 401 (GND) of the ASIC constituting the voltage measuring instrument 440A is used as the reference (i.e., set to 0V), the potential of the output of fuse 470 is approximately -100V when fuse 470 is not blown. On the other hand, when fuse 470 is blown and the positive contactor 460B and the negative contactor 460C are switched to the closed state, the potential of the output of fuse 470 is approximately +300V. In other words, in the voltage measuring circuit 400, the potential at ground LV_GND is approximately -100V to +300V with respect to the ground 301A of ASIC1.

[0090] As shown in Figure 9, the voltage measurement circuit 400 includes a reference power supply 412, a first resistor 421, a second resistor 422, and a third resistor 423. The first resistor 421 and the second resistor 422 are connected in series between the ground 401 and the reference power supply 412, and are configured to divide the voltage output by the reference power supply 412 at the voltage division point P1.

[0091] The potential at voltage divider point P1 is obtained by voltage measuring instrument 430A.

[0092] Here, although not shown in the diagram, in the equivalent circuit obtained by replacing the area around the reference power supply 412, the first resistor 421, and the second resistor 422 in Figure 9 with a Thevenin equivalent circuit, the equivalent resistor is 421a (internal resistance based on Thevenin's theorem), and the equivalent power supply is 412a (voltage source based on Thevenin's theorem). The voltage value of the equivalent power supply 412a is V0. The resistance value of the equivalent resistor 421a is R0.

[0093] In this equivalent circuit, the voltage value V0 of the equivalent power supply 412a is V0 = E1 × {Ra1 / (Ra1+Ra1)} = 5V × (1 / 2) = 2.5V. Also, the resistance value R0 of the equivalent resistor 421a is R0 = Ra1 × (1 / 2) = 10kΩ × (1 / 2). In other words, the equivalent resistance R0 is R0 = 5kΩ. The potential Vin at the voltage divider point P1 is Vin = V0 + (HV - V0) × {R0 / (R0+Rb)}. Here, Ra1 = 10kΩ and Rb = 995kΩ.

[0094] Therefore, Vin = V0 + (HV - V0) × {R0 / (R0 + Rb)} = 2.5V + (HV - 2.5V) × {5 / (5 + 995)}. Here, if HV fluctuates between -100V and +300V, then 2.5V + {(HV - 2.5V) × (1 / 200)} = 2.5V + (-0.5125V to +1.4875V), and the potential Vin at the voltage divider point P1 becomes Vin = 1.9875V to 3.9875V.

[0095] In other words, this circuit outputs a voltage Vin at voltage divider point P1 that is offset by -2.5V from the potential of the object being measured (HV), and then further offset by +2.5V with Gain 1 / 200. As a result, the potential of the object being measured (HV), which fluctuates between -100V and +300V, is output at a voltage of 1.9875V to 3.9875V.

[0096] The voltage measurement circuit 400 allows the use of a voltage measuring instrument 430A with a measurement range of 0 to 5V. With the configuration of this voltage measurement circuit 400, even if the output potential (HV) of the fuse 470 fluctuates between -100V and +300V, the potential of the object being measured acquired by the AD measuring instrument of the voltage measuring instrument 430A will be a positive value within the range of 0 to 5V. Therefore, the AD measuring instrument of the voltage measuring instrument 430A only needs to be capable of measuring positive potential. Thus, the voltage measurement circuit 400 does not require the provision of negative potential and can measure the potential (HV) of an object fluctuating between -100V and +300V using a more inexpensive AD measuring instrument. In this way, the battery voltage measurement circuit 400 allows the potential of the high-voltage circuit in the battery to be measured with an inexpensive configuration.

[0097] The embodiments of the technology disclosed herein have been described above. However, the above description is illustrative and does not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated in the above description.

[0098] In each of the embodiments described above, specific values ​​for Ra1 and Rb are set, but these values ​​are merely examples and are not intended to limit the values ​​of Ra1 and Rb. As mentioned above, based on the Thevenin equivalent circuit, the equivalent resistance value R0 is given by R0 = Ra1 × (1 / 2), and the potential Vin at the voltage divider point can be given by Vin = V0 + (HV - V0) × {R0 / (R0 + Rb)}. The values ​​of Ra1 and Rb can be adjusted as appropriate so that the potential value Vin is a positive value.

[0099] For example, the voltage measurement circuit 200 has various components, but is not limited thereto. In other embodiments, the voltage measurement circuit 200 may have only the minimum components necessary for application to a total voltage detection circuit (e.g., a first resistor, a second resistor, a third resistor, a reference power supply, a voltage measuring instrument, a total positive terminal, a total negative terminal, etc.).

[0100] For example, the voltage measurement circuit 300 has various components, but is not limited thereto. In other embodiments, the voltage measurement circuit 300 may have only the minimum components necessary for application to a leakage current detection circuit (e.g., a first resistor, a second resistor, a third resistor, a reference power supply, a voltage measuring instrument, a power supply unit, etc.).

[0101] For example, the voltage measurement circuit 400 has various components, but is not limited thereto. In other embodiments, the voltage measurement circuit 400 may have only the minimum components necessary for application to a fuse blow detection circuit (e.g., a first resistor, a second resistor, a third resistor, a reference power supply, a voltage measuring instrument, a power supply unit, a fuse, etc.).

[0102] For example, in the above embodiment, the resistance value of the first resistor and the resistance value of the second resistor are the same, but the embodiment is not limited to this. In other embodiments, the resistance values ​​of the first resistor and the resistance value of the second resistor may be different. In such cases, measurement accuracy can be improved. For example, in the configuration shown in Figures 7 and 8, if the resistance values ​​of the first resistor and the second resistor are different, it is possible to set the offset voltage to a voltage value other than 2.5V (for example, 1.25V or 3.75V). In such cases, it is easier to keep the measurement range within -100V to +300V and -300V to +100V, and as a result, sufficient measurement resolution can be obtained. This improves measurement accuracy.

[0103] As described above, specific embodiments of the technology disclosed herein include those described in the following sections.

[0104] Section 1: A voltage measuring circuit that measures the potential of an object to be measured, provided in a circuit to which a battery is connected, A reference power supply that applies a predetermined voltage, A first resistor and a second resistor, each having a predetermined resistance value, are connected in series between the ground of the voltage measurement circuit and the reference power supply. A third resistor having a predetermined resistance value Rb is connected between the first resistor and the second resistor and to the object to be measured, A voltage measuring instrument that acquires the potential of the object to be measured based on the potential obtained from the voltage division points obtained by the first resistor and the second resistor, Equipped with Battery voltage measurement circuit.

[0105] Section 2: Connected between the object to be measured and the pressure divider point, The system includes a switch for switching between connecting and disconnecting the first resistor, the second resistor and the third resistor. The battery voltage measurement circuit described in item 1.

[0106] Section 3: The total positive terminal is a positive terminal that is open to connect to external devices, The total negative terminal is a negative terminal that is open and connectable to the external device. Equipped with, The third resistor is electrically connected to the total positive terminal or the total negative terminal. A battery voltage measurement circuit as described in item 1 or 2.

[0107] Section 4: Equipped with a power supply unit in which multiple power sources are electrically connected, The positive or negative terminal of the power supply unit is electrically insulated from the ground point. The third resistor is connected to the ground point, A battery voltage measurement circuit as described in any one of items 1 to 3.

[0108] Section 5: A power supply unit in which multiple power supplies are electrically connected, A fuse connected to the positive or negative terminal side of the power supply unit and the third resistor. It is equipped with A battery voltage measurement circuit as described in any one of items 1 to 4.

[0109] Item 6: The resistance values ​​of the first resistor and the second resistor are different from each other. A battery voltage measurement circuit as described in any one of items 1 to 5. [Explanation of symbols]

[0110] 10. Items to be measured 11,12 Reference power supply 12a equivalent power supply 21 1st resistor 21a Equivalent resistance 22 2nd resistor 23 3rd resistor 30. Voltage Measuring Instruments 100 Voltage Measurement Circuit 101 Grand 102 switches

Claims

1. A voltage measuring circuit that measures the potential of an object to be measured, provided in a circuit to which a battery is connected, A reference power supply that applies a predetermined voltage, A first resistor and a second resistor, each having a predetermined resistance value, are connected in series between the ground of the voltage measurement circuit and the reference power supply. A third resistor having a predetermined resistance value is connected between the first resistor and the second resistor and to the object to be measured. A voltage measuring instrument that acquires the potential of the object to be measured based on the potential obtained from the voltage division points obtained by the first resistor and the second resistor, Equipped with Battery voltage measurement circuit.

2. Connected between the object to be measured and the pressure divider point, The system includes a switch for switching between connecting and disconnecting the first resistor, the second resistor and the third resistor. A battery voltage measurement circuit according to claim 1.

3. The total positive terminal is a positive terminal that is open to connect to external devices, The total negative terminal is a negative terminal that is open and connectable to the external device. Equipped with, The third resistor is electrically connected to the total positive terminal or the total negative terminal. A battery voltage measurement circuit according to claim 1 or 2.

4. Equipped with a power supply unit in which multiple power sources are electrically connected, The positive or negative terminal of the power supply unit is electrically insulated from the ground point. The third resistor is connected to the ground point, A battery voltage measurement circuit according to claim 1 or 2.

5. A power supply unit in which multiple power supplies are electrically connected, A fuse connected to the positive or negative terminal side of the power supply unit and the third resistor. It is equipped with A battery voltage measurement circuit according to claim 1 or 2.

6. The resistance values ​​of the first resistor and the second resistor are different from each other. A battery voltage measurement circuit according to claim 1 or 2.

Images