Relay monitoring circuit, power supply wiring monitoring circuit, welding detection circuit, relay monitoring module, power supply wiring monitoring module, and welding detection method

Abstract

To enable welding detection of a relay with a small circuit scale.SOLUTION: A relay monitoring circuit 1 of an embodiment outputs a welding determination signal Vo for a high-voltage-resistance relay RL. The relay monitoring circuit 1 includes: a first input terminal T1 connected to one of two terminals RL1 and RL2 that sandwich an open / close part of the high-voltage-resistance relay RL; a second input terminal T2 connected to the other of the two terminals RL1 and RL2; an output terminal T3 for outputting the determination signal Vo; a first voltage dividing circuit 3 for generating a first voltage Vf1 which is a voltage dropped from a voltage Vi1 of the first input terminal T1; a second voltage dividing circuit 4 for generating a second voltage Vf2 which is a voltage dropped from a voltage Vi2 of the second input terminal T2; and a negative feedback amplifying circuit 2 configured to output a voltage, according to a difference between the voltage Vi1 of the first input terminal T1 and the voltage Vi2 of the second input terminal T2 caused by applying the first voltage Vf1 and the second voltage Vf2, to the output terminal T3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a relay monitoring circuit, a power wiring monitoring circuit, a welding detection circuit, a relay monitoring module, a power wiring monitoring module, and a welding detection method. [Background technology]

[0002] Conventionally, a relay element (electrical relay) has been arranged in a line connecting a power source and a load supplied with power from the power source so that the power source and the load can be separated as needed. The relay element includes a switching unit such as a contact interposed between the lines to be separated or connected by the relay element, and an input unit for a control signal that controls the open / closed state of the switching unit. The relay element may be controlled to an open state while a current is flowing through the switching unit in a closed state. When the relay element transitions to such an open state, an arc discharge occurs in the switching unit according to the magnitude of the current that was flowing immediately before. Depending on the energy released in the arc discharge and the frequency of the arc discharge, the switching unit of the relay element may become stuck and unable to open, i.e., may become welded.

[0003] In particular, relay elements connected to DC power supplies that supply high voltage to loads are prone to welding because they may be controlled to an open state while a large current is flowing. For example, relay elements placed between an electric vehicle battery and various on-board loads that receive power from the battery may be at risk of welding because the battery voltage of an electric vehicle is high, exceeding 100 V. On the other hand, relay elements used in on-board equipment that require safe and reliable operation are required to be able to reliably detect welding so that fail-safe control can function appropriately in the event of welding.

[0004] Patent Document 1 discloses a power supply control device equipped with a welding detection circuit for checking for welding of such relays. In the power supply control device of Patent Document 1, an AC source that generates a square wave is connected to the relay for which welding detection is to be performed via a welding detection resistor. The difference between the voltage across the AC source when the AC source generates a square wave and the voltage across the series circuit of the AC source and the welding detection resistor is different when the relay is welded and when it is normal, and this is used to detect welding of the relay. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-185812 Summary of the Invention [Problem to be solved by the invention]

[0006] The power supply control device disclosed in Patent Document 1, which uses an AC source, has a large welding detection circuit. Therefore, if the welding detection circuit is implemented on a wiring board, the welding detection circuit occupies a large area on the wiring board. Patent Document 1 also primarily describes an example in which welding of the relays on the positive and negative sides of the power supply is detected simultaneously. However, to ensure proper and efficient replacement of a welded relay, it is preferable to be able to detect the welding of each relay individually. However, to achieve such detection, two welding detection circuits are required, which further increases the area occupied by the welding detection circuits on the wiring board. This is particularly problematic in devices where the size of circuits other than the relay welding detection circuit is not particularly large, as the relay welding detection circuit significantly increases the board area required for the entire device's circuit configuration.

[0007] Furthermore, peripheral circuits of relays that are combined with high-voltage power supplies, etc., are required to maintain the creepage distance stipulated by standards such as those of the International Electrotechnical Commission (IEC) around conductive parts that are at high potentials, which can cause problems by significantly increasing the area occupied by circuits for detecting relay welding.

[0008] In view of the above problems, an object of the present invention is to enable detection of welding of one or more relays with a small circuit scale and therefore with a small occupancy area when implemented. [Means for solving the problem]

[0009] A relay monitoring circuit according to one embodiment of the present invention is a relay monitoring circuit that outputs a signal for determining whether a high-voltage relay has welded, and includes: a first input terminal connected to one of two terminals that sandwich an opening / closing part of the high-voltage relay; a second input terminal connected to the other of the two terminals; an output terminal that outputs the determination signal; a first voltage divider circuit that generates a first voltage that is a voltage obtained by stepping down the voltage of the first input terminal; a second voltage divider circuit that generates a second voltage that is a voltage obtained by stepping down the voltage of the second input terminal; and a negative feedback amplifier circuit configured to output, to the output terminal, a voltage that corresponds to the difference between the voltage of the first input terminal and the voltage of the second input terminal upon application of the first voltage and the second voltage.

[0010] A power supply wiring monitoring circuit according to one embodiment of the present invention is a power supply wiring monitoring circuit that outputs a signal for determining whether a first high-voltage relay connected to one of the positive and negative electrodes of a DC power supply and a second high-voltage relay connected to the other of the positive and negative electrodes, and includes a first relay monitoring unit and a second relay monitoring unit, each configured by the relay monitoring circuit, and a power supply monitoring unit connected to the positive and negative electrodes, wherein the first relay monitoring unit is configured to output the signal for determining whether the first high-voltage relay is welded by connecting the first input terminal and the second input terminal included in the first relay monitoring unit to the first high-voltage relay, the second relay monitoring unit is configured to output the signal for determining whether the second high-voltage relay is welded by connecting the first input terminal and the second input terminal included in the second relay monitoring unit to the second high-voltage relay, and the power supply monitoring unit is configured to output a voltage based on a potential difference between the positive electrode and the negative electrode.

[0011] A welding detection circuit according to one embodiment of the present invention is a welding detection circuit that detects welding of a first high-voltage relay connected to one of the positive and negative poles of a DC power supply and a second high-voltage relay connected to the other of the positive and negative poles, and includes the power supply wiring monitoring circuit and a determination circuit that is configured to determine whether the first high-voltage relay and the second high-voltage relay are welded based on the determination signals from the first relay monitoring unit and the second relay monitoring unit when the output voltage of the power supply monitoring unit indicates that the potential difference between the positive pole and the negative pole is equal to or greater than a predetermined voltage.

[0012] A relay monitoring module of one embodiment of the present invention includes a first semiconductor integrated circuit device and a second semiconductor integrated circuit device that respectively constitute the above-mentioned relay monitoring circuit, and a wiring substrate having a first surface on which the first semiconductor integrated circuit device is mounted and a second surface that is the surface opposite to the first surface, wherein the second semiconductor integrated circuit device is mounted on the second surface and overlaps the first semiconductor integrated circuit device via the wiring substrate, the first input terminal of the first semiconductor integrated circuit device is electrically connected to the first input terminal of the second semiconductor integrated circuit device, and the second input terminal of the first semiconductor integrated circuit device is electrically connected to the second input terminal of the second semiconductor integrated circuit device.

[0013] A power wiring monitoring module according to one embodiment of the present invention is a power wiring monitoring module including the above-described power wiring monitoring circuit and a wiring board having a first surface and a second surface opposite to the first surface and on which the power wiring monitoring circuit is mounted, wherein the first relay monitoring unit includes a first semiconductor integrated circuit device and a second semiconductor integrated circuit device that respectively constitute the relay monitoring circuit of the first relay monitoring unit, the first semiconductor integrated circuit device is mounted on the first surface, and the second semiconductor integrated circuit device is mounted on the second surface and overlaps the first semiconductor integrated circuit device via the wiring board, the first input terminal of the first semiconductor integrated circuit device is electrically connected to the first input terminal of the second semiconductor integrated circuit device, and the second input terminal of the first semiconductor integrated circuit device is electrically connected to the second input terminal of the second semiconductor integrated circuit device.

[0014] A welding detection method according to one embodiment of the present invention is a method for detecting welding of a high-voltage relay, the method including: reducing the voltage of one of two terminals that sandwich an opening / closing unit of the high-voltage relay by a first voltage divider circuit that is provided between the one terminal and a predetermined reference potential, and applying the reduced voltage to a non-inverting input terminal of an operational amplifier that is connected via negative feedback; applying the voltage of the other of the two terminals to the inverting input terminal of the operational amplifier via a second voltage divider circuit that is provided between the other terminal and an output terminal of the operational amplifier; and determining whether the high-voltage relay is welded based on the output voltage of the operational amplifier, wherein the high-voltage relay is controlled to be in an open state, and when the potential of the output terminal of the operational amplifier is approximately the same as the predetermined reference potential, it is determined that the high-voltage relay is welded. [Effects of the Invention]

[0015] According to the relay monitoring circuit, power supply wiring monitoring circuit, welding detection circuit, relay monitoring module, power supply wiring monitoring module, and welding detection method of the present invention, it is believed that it is possible to detect welding of one or more relays with a small circuit scale and therefore with a small occupancy area when implemented. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a circuit diagram illustrating an example of a relay monitoring circuit according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing an example in which components of a relay monitoring circuit according to an embodiment of the present invention are configured in a semiconductor integrated circuit device; [Figure 3] 1 is a circuit diagram illustrating an example of a power supply wiring monitoring circuit and a welding detection circuit according to an embodiment of the present invention. [Figure 4A] FIG. 2 is a diagram illustrating a first surface side of an example of a relay monitoring module according to an embodiment of the present invention. [Figure 4B] FIG. 4B is a view showing the second surface side of the relay monitoring module of FIG. 4A. [Figure 4C] FIG. 4C is a cross-sectional view taken along line IVC-IVC in FIG. 4B. [Figure 5A]1 is a diagram showing a first surface side of an example of a power wiring monitoring module according to an embodiment of the present invention. [Figure 5B] 5B is a diagram showing the second surface side of the power wiring monitoring module of FIG. 5A. FIG. [Figure 5C] FIG. 5C is a cross-sectional view taken along line VC-VC in FIG. 5B. [Figure 5D] FIG. 5B is a cross-sectional view taken along line VD-VD in FIG. 5A. DETAILED DESCRIPTION OF THE INVENTION

[0017] Embodiments of the relay monitoring circuit, power wiring monitoring circuit, welding detection circuit, relay monitoring module, power wiring monitoring module, and welding detection method of the present invention will be described in order with reference to the drawings. However, the relay monitoring circuit, power wiring monitoring circuit, welding detection circuit, relay monitoring module, power wiring monitoring module, and welding detection method of the present invention are not limited to the embodiments described below. For example, the circuits shown in the drawings may include circuit elements that are not shown, and conversely, may not include all of the circuit elements shown. Furthermore, each element shown in the drawings may have any characteristics or constants, and the characteristics and constants of each element should be understood to be limited only by the claims.

[0018] <Configuration of relay monitoring circuit> FIG. 1 illustrates a relay monitoring circuit 1, which is an example of a relay monitoring circuit according to an embodiment. The relay monitoring circuit according to the embodiment outputs a signal used to determine whether a high-voltage relay is welded. The relay monitoring circuit 1 illustrated in FIG. 1 outputs a signal Vo for determining whether a high-voltage relay RL is welded. The high-voltage relay RL is disposed on a power supply path from a high-voltage DC power supply VBAT to a load L. The high-voltage relay RL has two terminals (a first terminal RT1 and a second terminal RT2) disposed across a switching unit (contact) of the high-voltage relay RL. The state of the switching unit is controlled by a control signal input to a control terminal (not illustrated). The "switching unit" of the high-voltage relay RL is a part of the high-voltage relay RL that is conductive when the high-voltage relay RL is closed and non-conductive when the high-voltage relay RL is open. In FIG. 1, the first terminal RT1 is connected to the positive electrode of the DC power supply VBAT, and the second terminal RT2 is connected to one end of the load L (the other end of the load L is connected to a GND potential). Therefore, in FIG. 1, in the high voltage relay RL, the first terminal RT1 is a high voltage side terminal, and the second terminal RT2 is a low voltage side terminal.

[0019] Note that a "high-voltage relay" refers to a relay element in which the two terminals connected by conducting its switching part (between the first terminal RT1 and the second terminal RT2 in the case of a high-voltage relay RL) are resistant to "high voltage." Here, "high voltage" refers to, for example, a voltage of 100 V or more and 1000 V or less, or may refer to a voltage of 400 V or more and 600 V or less. Note that the high-voltage relay RL will also be referred to simply as "relay RL" below.

[0020] The relay monitoring circuit 1 includes a first input terminal T1, a second input terminal T2, an output terminal T3, a negative feedback amplifier circuit 2n, a first voltage divider circuit 3, and a second voltage divider circuit 4. As shown in FIG. 1, the first input terminal T1 is connected to one of two terminals of the relay RL that sandwich the switch, and the second input terminal T2 is connected to the other of the two terminals that sandwich the switch. The output terminal T3 outputs a signal Vo for determining whether the relay RL is welded. In FIG. 1, the first input terminal T1 is connected to a first terminal RT1 of the relay RL, and the second input terminal T2 is connected to a second terminal RT2 of the relay RL. Note that, unlike FIG. 1, the first input terminal T1 may be connected to a low-voltage side terminal of the relay RL (a terminal connected to the negative side of the DC power supply VBAT), and the second input terminal T2 may be connected to a high-voltage side terminal of the relay RL (a terminal connected to the positive side of the DC power supply VBAT).

[0021] The first voltage divider circuit 3 generates a first voltage Vf1, which is a voltage obtained by stepping down the voltage Vi1 at the first input terminal T1, while the second voltage divider circuit 4 generates a second voltage Vf2, which is a voltage obtained by stepping down the voltage Vi2 at the second input terminal T2.

[0022] The negative feedback amplifier circuit 2n is configured to output a voltage corresponding to the difference between the voltage at the first input terminal T1 and the voltage at the second input terminal T2 to the output terminal T3 when a first voltage Vf1 and a second voltage Vf2 are applied to the negative feedback amplifier circuit 2n. The output voltage of the negative feedback amplifier circuit 2n is output from the output terminal T3 as a signal Vo for determining whether the relay RL is welded. In the relay monitoring circuit 1 of FIG. 1, the negative feedback amplifier circuit 2n includes an operational amplifier 2. The negative feedback amplifier circuit 2n is composed of the operational amplifier 2 and a fourth resistor 44. The operational amplifier 2 is negatively feedback connected via the fourth resistor 44, and this connection forms the negative feedback amplifier circuit 2n. The negative feedback-connected operational amplifier 2 outputs a voltage such that the potential of the non-inverting input terminal is equal to the potential of the inverting input terminal. Therefore, when the first voltage Vf1 and the second voltage Vf2 are applied to the negative feedback amplifier circuit 2n, the negative feedback amplifier circuit 2n outputs a voltage corresponding to the difference between the voltage at the first input terminal T1 and the voltage at the second input terminal T2. The operational amplifier 2 can be configured by any circuit using semiconductor elements such as transistors and resistor elements, and is preferably integrated on a semiconductor substrate.

[0023] In the above and following descriptions, an electrical quantity simply referred to as a "voltage" for a terminal, node, or signal means the potential difference between the potential of the terminal, node, or signal and a specific constant potential. Unless a specific description is given about the "specific constant potential," the "specific constant potential" may be the ground (GND) potential.

[0024] In the relay monitoring circuit 1 of this embodiment, the first voltage divider circuit 3 generates a first voltage Vf1 that is lower than the voltage at the first input terminal T1, i.e., the voltage at the first terminal RT1 of the relay RL. The second voltage divider circuit 4 generates a second voltage Vf2 that is lower than the voltage at the second input terminal T2, i.e., the voltage at the second terminal RT2 of the relay RL. The first voltage Vf1 and the second voltage Vf2 are input to the negative feedback amplifier circuit 2n. The negative feedback amplifier circuit 2n receives the first voltage Vf1 and the second voltage Vf2 and outputs a voltage based on the difference between the voltage at the first input terminal T1 and the voltage at the second input terminal T2 to the output terminal T3.

[0025] As an example, the negative feedback amplifier circuit 2n outputs a larger voltage the greater the difference between the voltage at the first input terminal T1 (i.e., the voltage at the first terminal RT1 of the relay RL) and the voltage at the second input terminal T2 (i.e., the voltage at the second terminal RT2 of the relay RL), and outputs a smaller voltage the smaller the difference between the voltage at the first terminal RT1 and the voltage at the second terminal RT2 of the relay RL. The difference between the voltage at the first terminal RT1 and the voltage at the second terminal RT2 of the relay RL when the relay RL is in the open state is larger than the difference between the voltage at the first terminal RT1 and the voltage at the second terminal RT2 when the relay RL is in the closed or welded state.

[0026] Therefore, by providing an appropriate threshold value for determining whether relay RL is welded, monitoring the output voltage of output terminal T3 (weld determination signal Vo) while relay RL is controlled to the open state, and comparing the determination signal Vo with the threshold value provided for determining whether relay RL is welded, it is possible to determine whether relay RL is welded. That is, the relay monitoring circuit of the embodiment can generate a determination signal for whether a high-voltage relay is welded and detect welded relays using only a simple and small number of components: two voltage-divider circuits, which can be configured, in the simplest example, by a series resistor circuit, and a negative-feedback amplifier circuit primarily configured with an operational amplifier. Because it does not require an AC source as in Patent Document 1, the relay monitoring circuit of the embodiment is considered to enable detection of welded relays with a small circuit scale and therefore a small footprint when implemented.

[0027] In the relay monitoring circuit 1 of Fig. 1, a first voltage divider circuit 3 is provided between a first input terminal T1 and a predetermined reference potential Vref. The first voltage divider circuit 3 includes a first resistor 31 and a second resistor 32 connected in series. The first resistor 31 is provided between the first input terminal T1 and the non-inverting input terminal of the operational amplifier 2, and the second resistor 32 is provided between the non-inverting input terminal of the operational amplifier 2 and the reference potential Vref. The first voltage divider circuit 3 generates a first voltage Vf1 at the connection node between the first resistor 31 and the second resistor 32, and therefore the first voltage Vf1 is applied to the non-inverting input terminal of the operational amplifier 2.

[0028] The predetermined reference potential Vref may be a potential of any value generated by any constant voltage generator (not shown). The reference potential Vref may be generated within the relay monitoring circuit 1 or may be provided from outside the relay monitoring circuit 1. From the viewpoint of utilizing the entire output voltage range of the operational amplifier 2, for example, an intermediate potential between the positive power supply voltage and the negative power supply voltage of the operational amplifier is selected as the reference potential Vref, but any value may be selected for the reference potential Vref.

[0029] In the relay monitoring circuit 1 of FIG. 1, the second voltage divider circuit 4 is provided between the second input terminal T2 and the output terminal T3. The second voltage divider circuit 4 includes a third resistor 43 and a fourth resistor 44 connected in series. The third resistor 43 is provided between the second input terminal T2 and the inverting input terminal of the operational amplifier 2, and the fourth resistor 44 is provided between the inverting input terminal of the operational amplifier 2 and the output terminal T3. The second voltage divider circuit 4 generates a second voltage Vf2 at the connection node between the third resistor 43 and the fourth resistor 44, and therefore the second voltage Vf2 is applied to the inverting input terminal of the operational amplifier 2. The output terminal of the operational amplifier 2 is connected to the output terminal T3 of the relay monitoring circuit 1 and the fourth resistor 44. The fourth resistor 44 forms a negative feedback path of the negative feedback amplifier circuit 2n.

[0030] <Relay monitoring circuit output voltage (welding detection signal Vo)> In the circuit configuration shown in FIG. 1, the output voltage of the relay monitoring circuit 1 output from the negative feedback amplifier circuit 2n, i.e., the voltage of the welding determination signal Vo, is expressed by the following equation (1), ignoring the offset voltage, common-mode rejection ratio, and power supply rejection ratio of the operational amplifier 2. Vo=(Vi1×R2×R34) / (R12×R3)-(Vi2×R4) / R3+(Vref×R1×R34) / (R12×R3) ···(1) Here, R1, R2, R3, and R4 are the resistance values of the first resistor 31, the second resistor 32, the third resistor 43, and the fourth resistor 44, respectively; R12 is the combined resistance value of the first resistor 31 and the second resistor 32 connected in series; and R34 is the combined resistance value of the third resistor 43 and the fourth resistor 44 connected in series.

[0031] As can be seen from the first and second terms on the right side of equation (1), the negative feedback amplifier circuit 2n is configured to output a voltage (welding detection signal Vo) corresponding to the difference between the voltage Vi1 at the first input terminal T1 and the voltage Vi2 at the second input terminal T2. In particular, when the first resistor 31 and the third resistor 43 have the same resistance value and the second resistor 32 and the fourth resistor 44 have the same resistance value, R1=R3 (hereinafter referred to as R1), R2=R4 (hereinafter referred to as R2), and R12=R34, and therefore, equation (2) below holds. Vo=(Vi1-Vi2)×R2 / R1+Vref ···(2)

[0032] By selecting the same resistance value for the first resistor 31 and the third resistor 43 and the same resistance value for the second resistor 32 and the fourth resistor 44, the calculation formula for the theoretical value of the welding determination signal Vo is simplified, as shown in Equation (2) above. This is believed to facilitate welding determination. Furthermore, since the number of factors affecting the determination signal Vo, such as the resistance value of each resistor, is reduced, variation in the welding determination signal Vo is reduced, and welding can be more accurately determined. For these reasons, it may be preferable that the resistance values of the first resistor 31 and the third resistor 43 are the same or approximately the same, and that the resistance values of the second resistor 32 and the fourth resistor 44 are the same or approximately the same. Note that "approximately the same" in relation to the resistance values of the first resistor 31 to the fourth resistor 44 means that the difference between the resistance values of any two of the first resistor 31 to the fourth resistor 44 is within 5% of the average resistance value of the two resistors.

[0033] For example, in a relay monitoring circuit 1 where R1=R3, R2=R4, R2 / R1=1 / 200, and the reference potential Vref=2.5V, when the relay RL is in the open state, the voltage Vi1 of the first input terminal T1 is 500V, and the voltage Vi2 of the second input terminal T2 is 2.5V, the voltage of the welding determination signal Vo is Vo=(500-2.5)×(1 / 200)+2.5=4.9875V If the relay is closed under the same conditions as in the example above, Vi1 = Vi2 = 500V, so Vo = (500 - 500) × (1 / 200) + 2.5 = 2.5V. That is, the potential of the welding determination signal Vo is the same as the reference potential Vref. When the relay RL is welded, the relay monitoring circuit 1 outputs the welding determination signal Vo having substantially the same voltage as when the relay RL is in the closed state, regardless of the control status of the relay RL. Therefore, in the above example, a voltage between 4.9875V and 2.5V, for example, a voltage between 3V and 4.5V, is set as the threshold, and the welding determination signal Vo is monitored with the relay RL controlled to the open state. Then, when the voltage of the determination signal Vo is equal to or lower than the threshold, it can be determined that the relay RL is welded. Alternatively, when the relay RL is controlled to the open state, it can be determined that the relay RL is welded when the potential of the determination signal Vo is substantially the same as the reference potential Vref.

[0034] In addition, when the first input terminal T1 of the relay monitoring circuit 1 is connected to the low-voltage side terminal of the relay RL and the second input terminal T2 is connected to the high-voltage side terminal of the relay RL, as can be seen from equations (1) and (2), the relay monitoring circuit 1 outputs a determination signal Vo whose voltage is lower than the voltage of the reference potential Vref when the relay RL is in the open state.

[0035] The ratio (R2 / R1) of the resistance value R2 of the second resistor 32 to the resistance value R1 of the first resistor 31 and the ratio (R4 / R3) of the resistance value R4 of the fourth resistor 44 to the resistance value R3 of the third resistor 43 are not particularly limited as long as they are values that can step down the voltage Vi1 of the first input terminal T1 and the voltage Vi2 of the second input terminal T2 to voltages that can be input to the operational amplifier 2. As an example, the resistance value R2 of the second resistor 32 is 0.3% to 1.0% of the resistance value R1 of the first resistor 31, and the resistance value R4 of the fourth resistor 44 is 0.3% to 1.0% of the resistance value R3 of the third resistor 43.

[0036] When the ratio (R2 / R1) and the ratio (R4 / R3) are 1.0% or less, even if the voltage Vi1 at the first input terminal T1 and the voltage Vi2 at the second input terminal T2 are on the order of several hundred volts, it is possible to generate the first voltage Vf1 and the second voltage Vf2 of about several volts, which are commonly used as power supply voltages in electronic devices. Furthermore, when the ratio (R2 / R1) and the ratio (R4 / R3) are 0.3% or more, it is thought that even if the voltages Vi1 and Vi2 are on the order of 100 V, the operational amplifier 2 can generate the first voltage Vf1 and the second voltage Vf2 of about 0.3 V, which is thought to be an output voltage corresponding to the difference between the voltages Vi1 and Vi2 without being affected by noise or characteristic variations.

[0037] The first resistor 31 and the second resistor 32, which are arranged between the first input terminal T1, to which a high voltage exceeding several hundred volts may be applied, and a predetermined reference potential Vref, for example, of several volts, preferably have large resistance values to prevent large currents from flowing. In particular, the first resistor 31, which has a resistance value preferably 200 times (the reciprocal of 0.5%) or more the resistance value of the second resistor 32, is required to have an extremely large resistance value. Similarly, the third resistor 43 and the fourth resistor 44 also preferably have large resistance values, and the third resistor 43 is particularly required to have an extremely large resistance value. For example, the resistance values of the first resistor 31 and the third resistor 43 may be tens of megohms or more, or may be on the order of hundreds of megohms. Furthermore, the resistance values of the second resistor 32 and the fourth resistor 44 may be tens of kiloohms or more, or may be on the order of hundreds of kiloohms.

[0038] <Method for detecting welding using a relay monitoring circuit> In a method for detecting welding of a high-voltage relay such as a relay RL using a relay monitoring circuit 1, the voltage of one of two terminals sandwiching the switching section of the high-voltage relay (e.g., the first terminal RT1 of the relay RL in FIG. 1 ) is stepped down by a first voltage divider circuit 3 provided between the first terminal and a predetermined reference potential Vref, and applied to the non-inverting input terminal of a negative-feedback-connected operational amplifier 2. The voltage of the other of the two terminals sandwiching the switching section of the high-voltage relay (e.g., the second terminal RT2 of the relay RL in FIG. 1 ) is applied to the inverting input terminal of the operational amplifier 2 via a second voltage divider circuit 4 provided between the other terminal and the output terminal of the operational amplifier 2. Whether the high-voltage relay is welded is then determined based on the output voltage of the operational amplifier 2. Specifically, when the high-voltage relay is controlled so that it is in an open state, it is determined that the high-voltage relay is welded when the potential of the output terminal of the operational amplifier 2 is approximately the same as the predetermined reference potential Vref. Alternatively, it may be determined that the high-voltage relay is welded when the output voltage of the operational amplifier 2 exceeds or falls below a predetermined threshold value while the high-voltage relay is controlled to be in an open state. Note that the phrase "the potential of the output terminal of the operational amplifier 2 is substantially the same as" the predetermined reference potential Vref means that the difference between these two potentials is within 5% of the reference potential Vref.

[0039] <Example of a relay monitoring circuit> FIG. 2 schematically illustrates an example of an embodied relay monitoring circuit 1. In the example of FIG. 2, the components of the relay monitoring circuit 1 are configured using a semiconductor integrated circuit device 1a. Specifically, the first voltage divider circuit 3, the second voltage divider circuit 4, and the negative feedback amplifier circuit 2n are configured using a single semiconductor integrated circuit device 1a. The semiconductor integrated circuit device 1a may be a high-voltage monitoring semiconductor integrated circuit device suitable for monitoring the voltage between the positive and negative electrodes of a high-voltage power supply, for example. By integrating the relay monitoring circuit 1, particularly the first voltage divider path 3 and the second voltage divider circuit 4, into the semiconductor integrated circuit device 1a (hereinafter also referred to simply as the "semiconductor device 1a"), it is possible to detect relay welding in a smaller occupied area. That is, as described above, each resistor constituting the first voltage divider circuit 3 or the second voltage divider circuit 4 preferably has a large resistance value of several hundred megohms or more. If a resistor with such a large resistance value were configured using individual resistive elements, a long resistor would be required. However, when the first voltage-dividing circuit 3 and the second voltage-dividing circuit 4 are integrated into the semiconductor device 1a, it is possible to form extremely thin resistor patterns by semiconductor processing, and it is therefore possible to form the first to fourth resistors 31, 32, 43, 44 that are relatively short and have high resistance values. Therefore, it is possible to detect welding of the relay in a smaller occupied area.

[0040] 2 includes a terminal 1aa that functions as the first input terminal T1, a terminal 1ab that functions as the second input terminal T2, and a terminal 1ac that functions as the output terminal T3 of the relay monitoring circuit 1. The semiconductor device 1a of FIG. 2 further includes a terminal 1ad to which a predetermined reference potential Vref is applied, as well as a terminal 1ae for supplying a positive power supply voltage to the operational amplifier 2 and a terminal 1af for supplying a negative power supply voltage.

[0041] The semiconductor device 1a has a rectangular shape when viewed from above, and only two terminals, terminal 1aa and terminal 1ab, are arranged on one side E1 of the rectangular shape. Meanwhile, terminals 1ac to 1af are arranged on a side E2 opposite side E1. A high voltage from a DC power supply VBAT is applied to terminals 1aa and 1ab. By arranging terminals 1aa and 1ab on side E1 and arranging the other terminals 1ac to 1af on side E2 opposite side E1, it is possible to easily ensure an appropriate creepage distance between terminals 1aa and 1ab and the other terminals 1ac to 1af.

[0042] Furthermore, when relay RL is in an open state, it is considered that a high voltage is also applied between terminals 1aa and 1ab. By arranging only terminals 1aa and 1ab on one side E1, an appropriate creepage distance can also be easily ensured between terminals 1aa and 1ab. For example, semiconductor device 1a has a distance of more than 5 mm between terminals 1aa and 1ab, and between terminals 1aa and 1ab and terminals 1ac to 1af. By having a distance of more than 5 mm, for example, when the voltage of DC power supply VBAT is 1000V, it may be possible to comply with the creepage distance standard specified in IEC 60664-1.

[0043] <Power wiring monitoring circuit> Fig. 3 shows a power supply wiring monitoring circuit 10, which is an example of a power supply wiring monitoring circuit according to an embodiment. The power supply wiring monitoring circuit according to an embodiment outputs a signal for determining whether each of the high-voltage relays connected to the positive and negative electrodes of a DC power supply is welded. In the example of Fig. 3, a DC power supply VBAT that supplies a high voltage has a positive electrode BP and a negative electrode BN, of which a first high-voltage relay RL1 is connected to the negative electrode BN, and a second high-voltage relay RL2 is connected to the positive electrode BP of the DC power supply VBAT. The power supply wiring monitoring circuit 10 outputs a signal for determining whether the first high-voltage relay RL1 and the second high-voltage relay RL2 are welded.

[0044] The power supply wiring monitoring circuit 10 shown in FIG. 3 includes a first relay monitoring unit 11, a second relay monitoring unit 12, and a power supply monitoring unit 13. As shown in FIG. 3, the power supply monitoring unit 13 is connected to the positive electrode BP and the negative electrode BN of a DC power supply VBAT. The DC power supply VBAT shown in FIG. 3 is a so-called floating power supply in which neither the positive electrode BP nor the negative electrode BN is connected to ground. Therefore, high-voltage relays are provided on both the positive electrode wiring WP and the negative electrode wiring WN. A first high-voltage relay RL1 is provided on the negative electrode wiring WN, and a second high-voltage relay RL2 is provided on the positive electrode wiring WP (the first high-voltage relay RL1 and the second high-voltage relay RL2 will hereinafter also be referred to as the "first relay RL1" and the "second relay RL2," respectively).

[0045] As shown in Fig. 3, the first relay monitoring unit 11 and the second relay monitoring unit 12 are each configured by the relay monitoring circuit of the embodiment described using the relay monitoring circuit 1 of Fig. 1 as an example. The internal configuration and functions of the relay monitoring circuit 1 configuring the first relay monitoring unit 11 or the second relay monitoring unit 12 in the power supply wiring monitoring circuit 10 of Fig. 3 are similar to the internal configuration and functions of the relay monitoring circuit 1 described with reference to Fig. 1. Therefore, the components of Fig. 3 are assigned the same reference numerals as those assigned to the corresponding components in Fig. 1, or the reference numerals are omitted as appropriate, and repeated explanations of those components will be omitted.

[0046] 3, the first relay monitoring circuit 1 constituting the first relay monitoring unit 11 has a first input terminal T1 connected to a first terminal RT1 of a first relay RL1, and a second input terminal T2 connected to a second terminal RT2 of the first relay RL1. The first relay monitoring unit 11 monitors whether the first relay RL1 is welded. Meanwhile, the second relay monitoring unit 12 constituting the relay monitoring circuit 1 has a first input terminal T1 connected to a first terminal RT1 of a second relay RL2, and a second input terminal T2 connected to a second terminal RT2 of the second relay RL2. The second relay monitoring unit 12 monitors whether the second relay RL2 is welded. The first relay monitoring unit 11 is configured to output a signal Vo1 for determining whether the first relay RL1 is welded by connecting the first input terminal T1 and the second input terminal T2 included in the first relay monitoring unit 11 with the first relay RL1. The second relay monitoring unit 12 is configured to output a signal Vo2 for determining whether the second relay RL2 is welded by connecting the first input terminal T1 and the second input terminal T2 included in the second relay monitoring unit 12 to the second relay RL2.

[0047] That is, the first relay monitoring unit 11 is configured by the relay monitoring circuit of the embodiment, and therefore can output a signal Vo1 for determining whether the first relay RL1 to which the first input terminal T1 and the second input terminal T2 are connected, as described with reference to Fig. 1. Similarly, the second relay monitoring unit 12 is configured by the relay monitoring circuit of the embodiment, and therefore can output a signal Vo2 for determining whether the second relay RL2 to which the first input terminal T1 and the second input terminal T2 are connected are connected.

[0048] In addition, the first relay RL1 connected to the first relay monitoring unit 11 may be connected to the positive electrode BP of the DC power supply VBAT, and the second relay RL2 connected to the second relay monitoring unit 12 may be connected to the negative electrode BN.

[0049] The power supply monitor 13 is configured to output a voltage Vop based on the potential difference Vp between the positive electrode BP and the negative electrode BN of the DC power supply VBAT. The power supply monitor 13 may be configured, for example, to output a predetermined high level when the potential difference Vp between the positive electrode BP and the negative electrode BN is equal to or greater than a predetermined value, and to output a predetermined low level when the potential difference Vp is less than the predetermined value. The internal configuration of the power supply monitor 13 is not limited as long as it is capable of outputting a signal indicating whether the potential difference Vp between the positive electrode BP and the negative electrode BN is equal to or greater than a predetermined voltage. For example, the power supply monitor 13 may simply be configured as a comparator.

[0050] However, since the potential difference Vp is the potential difference between the positive electrode BP and the negative electrode BN of the DC power supply VBAT that provides the high voltage, it is a high voltage of at least several hundred volts or more. Therefore, it is preferable that the power supply monitoring unit 13 has an input unit connected to the DC power supply VBAT that can withstand high voltages of at least several hundred volts or more, and that the power supply monitoring unit 13 has a circuit that reduces the voltage of at least one of the positive electrode BP and the negative electrode BN. Therefore, in the example of Figure 3, the power supply monitoring unit 13 is configured with the same circuits as the circuits that configure the first relay monitoring unit 11 and the second relay monitoring unit 12, respectively.

[0051] In particular, the power supply monitoring unit 13 in the example of FIG. 3 is configured by the relay monitoring circuit 1 of the embodiment described with reference to FIG. 1. That is, the power supply monitoring unit 13 includes a first input terminal T1, a second input terminal T2, an output terminal T3, a negative feedback amplifier circuit 2n, a first voltage divider circuit 3, and a second voltage divider circuit 4. In FIG. 3, the first input terminal T1 of the power supply monitoring unit 13 is connected to the negative terminal BN of the DC power supply VBAT, and the second input terminal T2 is connected to the positive terminal BP. The output terminal T3 outputs a voltage Vop, which is the output voltage of the negative feedback amplifier circuit 2n and is based on the potential difference Vp between the positive terminal BP and the negative terminal BN of the DC power supply VBAT. Each component of the power supply monitoring unit 13 in FIG. 3 functions in the same way as each component of the relay monitoring circuit 1 in FIG. 1, and therefore a description of the function and operation of each component of the power supply monitoring unit 13 will be omitted.

[0052] The power supply monitor 13 operates in a manner similar to that of the relay monitor circuit 1 described with reference to FIG. 1, thereby outputting a voltage Vop based on a potential difference Vp between the positive electrode BP and the negative electrode BN of the DC power supply VBAT. That is, the above formula (2) may be applicable as a relational expression between the voltages at the first input terminal T1 and the second input terminal T2 of the power supply monitor 13 and the output voltage Vop. For example, when formula (2) is applicable, the attenuation ratio (R2 / R1) of the first voltage divider circuit 3 is 1 / 200, and the predetermined reference potential Vref is 2.5 V, the power supply monitor 13 outputs a voltage Vop of approximately 0 V when the DC power supply VBAT supplies a normal voltage (e.g., 500 V). However, when the DC power supply VBAT is not supplying voltage due to some abnormality (potential difference Vp = 0 V), the power supply monitor 13 outputs a voltage Vop of approximately 2.5 V. Therefore, by comparing the voltage Vop output from the power supply monitor 13 with an appropriate threshold value or the reference potential Vref, it is possible to determine whether the DC power supply VBAT is supplying voltage normally.

[0053] Alternatively, the first input terminal T1 of the power supply monitoring unit 13 may be connected to the positive electrode BP of the DC power supply VBAT, and the second input terminal T2 may be connected to the negative electrode BN. In this case, the direction of change (increase or decrease) of the voltage Vop output from the power supply monitoring unit 13 in response to a change in the potential difference Vp will be opposite to that in the example of Fig. 3, but the power supply monitoring unit 13 can output the voltage Vo based on the potential difference Vp.

[0054] The power supply wiring monitoring circuit of the embodiment can output a signal for determining whether a high-voltage relay connected to the positive electrode of a DC power supply and a high-voltage relay connected to the negative electrode is welded, thereby providing information useful for appropriately replacing a welded high-voltage relay. Furthermore, since the power supply monitoring unit is provided, it can provide information on whether the current period is suitable for determining whether a high-voltage relay is welded.

[0055] In other words, when the DC power supply VBAT is not outputting a voltage normally due to some kind of abnormality or a disconnected connector, it is thought that a sufficiently large potential difference cannot be generated across the first relay RL1 or the second relay RL2, even if those relays are normally in an open state. If the welding of each relay is determined based on the determination signals Vo1 and Vo2 in such a state, it is thought that each relay will be mistakenly determined to be welded, even though it is normal. In contrast, the power supply wiring monitoring circuit of the embodiment including a power supply monitoring unit outputs a voltage based on the potential difference between the positive and negative electrodes of the DC power supply, so it is possible to provide information on whether it is appropriate to determine whether a relay is welded, and therefore it is possible to prevent erroneous detection of a weld.

[0056] 1 can be realized in a smaller area than conventional ones. Therefore, the power supply wiring monitoring circuit of the embodiment that monitors welding of each of a plurality of high-voltage relays can be realized in a smaller area than when multiple welding detection circuits described in Patent Document 1 are used.

[0057] From the viewpoint of reducing the area occupied by the power line monitoring circuit of the embodiment, the first relay monitoring unit 11, the second relay monitoring unit 12, and the power supply monitoring unit 13 of the power line monitoring circuit 10 shown in Fig. 3 may each be configured by a single semiconductor integrated circuit device 1a as shown in Fig. 2. The semiconductor integrated circuit device 1a configuring the first relay monitoring unit 11, the second relay monitoring unit 12, and the power supply monitoring unit 13 may be a semiconductor integrated circuit device for high voltage monitoring, as described above for the relay monitoring circuit of the embodiment. By configuring the first relay monitoring unit 11, the second relay monitoring unit 12, and the power supply monitoring unit 13 each by a single semiconductor integrated circuit device 1a, it is thought that the power line monitoring circuit 10 can be realized in a smaller area.

[0058] When at least one of the first relay monitoring unit 11 and the second relay monitoring unit 12 and the power supply monitoring unit 13 are configured by a semiconductor integrated circuit device for high voltage monitoring, at least one of the first relay monitoring unit 11 and the second relay monitoring unit 12 and the power supply monitoring unit 13 may be configured by the same type of semiconductor integrated circuit device for high voltage monitoring. In this case, the number of types of parts required for the power supply wiring monitoring circuit of the embodiment is reduced, which may facilitate the procurement of parts and management during manufacturing of the power supply wiring monitoring circuit.

[0059] The term "same model" means that the internal circuit configurations and characteristics of two or more high-voltage monitor semiconductor integrated circuit devices are not intentionally different in design. For example, when two or more high-voltage monitor semiconductor integrated circuit devices are "same model," it means that the two or more high-voltage monitor semiconductor integrated circuit devices are sold under the same name, product number, model number, product name, or model name.

[0060] <Welding detection circuit> FIG. 3 further illustrates a welding detection circuit 100, which is an example of a welding detection circuit according to an embodiment. The welding detection circuit according to the embodiment detects welding of each of the high-voltage relays connected to the positive and negative terminals of a DC power supply. The welding detection circuit 100 of the example in FIG. 3 detects welding of a first high-voltage relay RL1 connected to the negative terminal BN of the DC power supply VBAT and a second high-voltage relay RL2 connected to the positive terminal BP. As shown in FIG. 3, the welding detection circuit 100 includes the power supply wiring monitoring circuit 10 according to the above-described embodiment and a determination circuit 10a. The determination circuit 10a is configured to determine welding of the first relay RL1 based on a welding determination signal Vo1 from a first relay monitoring unit 11 and to determine welding of the second relay RL2 based on a welding determination signal Vo2 from a second relay monitoring unit 12. Here, the determination circuit 10a is configured to determine whether the first relay RL1 and the second relay RL2 are welded when the voltage Vop output from the power supply monitoring unit 13 indicates that the potential difference Vp between the positive electrode BP and the negative electrode BN of the DC power supply VBAT is equal to or greater than a predetermined voltage.

[0061] That is, when the DC power supply VBAT is normally supplying voltage and the voltage Vop of the power supply monitoring unit 13 indicates that the potential difference Vp is equal to or greater than a predetermined voltage, the determination circuit 10a determines that the first relay RL1 is in a welded state if the determination signal Vo1 from the first relay monitoring unit 11 indicates that the first relay RL1 is in a welded state. Furthermore, when the voltage Vop of the power supply monitoring unit 13 indicates that the potential difference Vp is equal to or greater than a predetermined voltage, the determination circuit 10a determines that the second relay RL2 is in a welded state if the determination signal Vo2 from the second relay monitoring unit 12 indicates that the second relay RL2 is in a welded state. However, when the voltage Vop of the power supply monitoring unit 13 indicates that the potential difference Vp is less than the predetermined voltage due to some abnormality in the DC power supply VBAT, the determination circuit 10a does not determine whether the first relay RL1 or the second relay RL2 is in a welded state, regardless of the state indicated by the determination signals Vo1 and Vo2.

[0062] Therefore, the welding detection circuit of the embodiment can prevent erroneous detection by avoiding welding determination at times that are unsuitable for determining whether a relay is welded, such as when the DC power supply VBAT is abnormal, thereby enabling appropriate determination of welding. The determination circuit 10a in FIG. 3 may have any circuit configuration as long as it can determine whether the first relay RL1 and the second relay RL2 are welded as described above based on the welding determination signals Vo1 and Vo2 and the voltage Vop output from the power supply monitor 13. For example, the determination circuit 10a may be configured by a combination circuit of a comparator and logic gates, or by a microcomputer that operates according to instructions written in a stored program.

[0063] <Relay monitoring module> 4A to 4C schematically illustrate a relay monitoring module 5, which is an example of a relay monitoring module according to an embodiment. FIG. 4A illustrates a first surface 5a of a wiring substrate 50, FIG. 4B illustrates a second surface 5b of the wiring substrate 50, and FIG. 4C illustrates a cross section taken along line IVC-IVC in FIG. 4B. As illustrated in FIGS. 4A to 4C, the relay monitoring module 5 includes a wiring substrate 50 having a first surface 5a and a second surface 5b opposite the first surface 5a, a first semiconductor integrated circuit device 51, and a second semiconductor integrated circuit device 52. The first semiconductor integrated circuit device 51 (hereinafter also simply referred to as the "first semiconductor device 51") is mounted on the first surface 5a of the wiring substrate 50, and the second semiconductor integrated circuit device 52 (hereinafter also simply referred to as the "second semiconductor device 52") is mounted on the second surface 5b.

[0064] As shown in FIGS. 4A and 4B , the first semiconductor device 51 and the second semiconductor device 52 constitute the relay monitoring circuit 1 of the embodiment described with reference to FIG. 1 . Therefore, each component of the first semiconductor device 51 and the second semiconductor device 52 functions in the same manner as each component of the relay monitoring circuit 1 of FIG. 1 . That is, the first semiconductor device 51 outputs a voltage corresponding to the difference between the voltage at the first input terminal T1 and the voltage at the second input terminal T2 included in the first semiconductor device 51 from the output terminal T3 of the first semiconductor device 51 as a signal Vo for determining whether the relay connected to the first input terminal T1 and the second input terminal T2 is welded. Similarly, the second semiconductor device 52 outputs a voltage corresponding to the difference between the voltage at the first input terminal T1 and the voltage at the second input terminal T2 included in the second semiconductor device 52 from the output terminal T3 of the second semiconductor device 52 as a signal Vo for determining whether the relay connected to the first input terminal T1 and the second input terminal T2 is welded.

[0065] The components of the first semiconductor device 51 and the second semiconductor device 52 are assigned the same reference numerals as those assigned to the corresponding components in the relay monitoring circuit 1 of Fig. 1 or are omitted as appropriate, and repeated explanations thereof will be omitted. Furthermore, the functions and actions of the individual components of the first semiconductor device 51 and the second semiconductor device 52 are similar to the functions and actions of the corresponding components in the relay monitoring circuit 1 of Fig. 1, and therefore repeated explanations thereof will be omitted.

[0066] Wiring board 50 includes conductor patterns 571 to 574 formed of a conductor such as copper on base material 58 formed of an insulating material such as glass epoxy or ceramic. Conductor patterns 571 and 572 are formed on first surface 5a, and conductor patterns 573 and 574 are formed on second surface 5b. Wiring board 50 further includes a through conductor 561 that penetrates base material 58 to connect conductor pattern 571 and conductor pattern 573, and a through conductor 562 that penetrates base material 58 to connect conductor pattern 572 and conductor pattern 574. A positive electrode BP of a DC power supply VBAT is connected to conductor pattern 571, and a load L is connected to conductor pattern 572.

[0067] The first input terminal T1 of the first semiconductor device 51 is connected to the conductor pattern 571, and the second input terminal T2 of the first semiconductor device 51 is connected to the conductor pattern 572. The first terminal RT1 of the relay RL is also connected to the conductor pattern 571, and the second terminal RT2 of the relay RL is also connected to the conductor pattern 572. Meanwhile, the first input terminal T1 of the second semiconductor device 52 is connected to the conductor pattern 573, and the second input terminal T2 of the second semiconductor device 52 is connected to the conductor pattern 574. Therefore, the first terminal RT1 of the relay RL and the first input terminal T1 of the first semiconductor device 51 are electrically connected to the first input terminal T1 of the second semiconductor device 52 via the conductor patterns 571 and 573 and the through conductor 561. Furthermore, the second terminal RT2 of the relay RL and the second input terminal T2 of the first semiconductor device 51 are electrically connected to the second input terminal T2 of the second semiconductor device 52 via the conductor patterns 572 and 574 and the through conductor 562.

[0068] 4A to 4C, both the first semiconductor device 51 and the second semiconductor device 52 output a signal Vo for determining whether the relay RL is welded. That is, the relay monitoring module 5 of the embodiment has redundancy in generating the signal Vo for determining whether the relay RL is welded. For example, even if the first semiconductor device 51 fails, the second semiconductor device 52 can output the signal Vo for determining whether the relay RL is welded. This can improve the reliability of detecting whether the relay RL is welded.

[0069] In the relay monitoring module shown in FIGS. 4A to 4C, the first semiconductor device 51 and the second semiconductor device 52 are mounted so as to overlap with each other via the wiring board 50. In particular, in the example of FIGS. 4A to 4C, the first semiconductor device 51 and the second semiconductor device 52 almost completely overlap with each other in a plan view (as viewed perpendicular to the wiring board 50). Therefore, while two semiconductor devices that provide redundancy are provided, an increase in the area of the wiring board 50 is suppressed. Note that the first semiconductor device 51 and the second semiconductor device 52 do not necessarily have to completely overlap with each other; for example, they may overlap partially. If there is a partial overlap, it is possible to somewhat suppress an increase in the area of the wiring board 50 that would be caused by providing two semiconductor devices for redundancy.

[0070] Furthermore, because the first semiconductor device 51 is mounted on the first surface 5a of the wiring board 50 and the second semiconductor device 52 is mounted on the second surface 5b of the wiring board 50, there is no need to space the two semiconductor devices apart in plan view in consideration of creepage distance, as is the case when both semiconductor devices are mounted on one surface. In this way, the relay monitoring module of the embodiment can achieve a compact relay monitoring circuit with redundancy while ensuring creepage distance.

[0071] 4A, the first input terminal T1 and the second input terminal T2 of the first semiconductor device 51 are arranged on one side E11 of the rectangular first semiconductor device 51. On the other hand, as shown in FIG. 4B, the first input terminal T1 and the second input terminal T2 of the second semiconductor device 52 are arranged on one side E12 of the second semiconductor device 52. The first input terminal T1 and the second input terminal T2 of the second semiconductor device 52 are arranged on the side E12 of the second semiconductor device 52 in an arrangement that is the reverse of the arrangement of the first input terminal T1 and the second input terminal T2 of the first semiconductor device 51 on the side E11.

[0072] That is, the first input terminal T1 and the second input terminal T2 of the first semiconductor device 51, and the first input terminal T1 and the second input terminal T2 of the second semiconductor device 52 are arranged so that when the first semiconductor device 51 and the second semiconductor device 52 are placed on the same plane with one side E11 and one side E12 facing each other, the first input terminals T1 face each other and the second input terminals T2 face each other. Hereinafter, an arrangement in which the first input terminals T1 and the second input terminals T2 of the second semiconductor device 52 are reversed to the arrangement of the first input terminals T1 and the second input terminals T2 of the first semiconductor device 51 is also referred to as an "inverted arrangement."

[0073] Since the first input terminal T1 and the second input terminal T2 are arranged in this manner in each semiconductor device, the conductor patterns 571 to 574 can be arranged in an orderly manner as shown in Figures 4A and 4B. In other words, for example, on the second surface 5b, it is not necessary to route the conductor pattern 574 a long distance from the through conductor 562 to the second terminal T2 of the second semiconductor device 52 while taking into consideration the creepage distance. Therefore, by arranging the first input terminal T1 and the second input terminal T2 of each semiconductor device as in the example of Figures 4A and 4B, it may be possible to realize a small-sized relay monitoring circuit.

[0074] <Power wiring monitoring module> 5A to 5D schematically illustrate a power wiring monitoring module 6, which is an example of a power wiring monitoring module according to an embodiment. FIG. 5A illustrates the first surface 6a of a wiring substrate 60, FIG. 5B illustrates the second surface 6b of the wiring substrate 60, FIG. 5C illustrates a partial cross section taken along line VC-VC in FIG. 5B, and FIG. 5D illustrates a partial cross section taken along line VD-VD in FIG. 5A. As illustrated in FIGS. 5A to 5D, the power wiring monitoring module 6 includes a power wiring monitoring circuit 600 and a wiring substrate 60 having a first surface 6a and a second surface 6b opposite the first surface 6a. The power wiring monitoring circuit 600 is mounted on the first surface 6a and the second surface 6b of the wiring substrate 60. The power wiring monitoring circuit 600 includes the components of the power wiring monitoring circuit 10 according to the embodiment described with reference to FIG. 3. Therefore, the power wiring monitoring module 6 includes a first relay monitoring unit 601 that outputs a signal for determining whether the first relay RL1 is welded, and a second relay monitoring unit 602 that outputs a signal for determining whether the second relay RL2 is welded. The power wiring monitoring circuit 600 further includes a power supply monitoring unit 603 that is connected to the positive electrode BP and negative electrode BN of the DC power supply VBAT.

[0075] Like the first relay monitoring unit 11 and the second relay monitoring unit 12 of the power supply wiring monitoring circuit 10 of FIG. 3 , the first relay monitoring unit 601 and the second relay monitoring unit 602 are configured by the relay monitoring circuit of the embodiment described using the relay monitoring circuit 1 of FIG. 1 as an example. The first relay monitoring unit 601 includes two semiconductor integrated circuit devices (a first semiconductor integrated circuit device 61 and a second semiconductor integrated circuit device 62) that respectively configure the relay monitoring circuit 1 included in the first relay monitoring unit 601. The second relay monitoring unit 602 includes two semiconductor integrated circuit devices (a third semiconductor integrated circuit device 63 and a fourth semiconductor integrated circuit device 64) that respectively configure the relay monitoring circuit 1 included in the second relay monitoring unit 602. Hereinafter, the first semiconductor integrated circuit device 61, the second semiconductor integrated circuit device 62, the third semiconductor integrated circuit device 63, and the fourth semiconductor integrated circuit device 64 will also be simply referred to as the “first semiconductor device 61,” the “second semiconductor device 62,” the “third semiconductor device 63,” and the “fourth semiconductor device 64,” respectively.

[0076] The first semiconductor device 61 and the third semiconductor device 63 are mounted on a first surface 6a of the wiring board 60, and the second semiconductor device 62 and the fourth semiconductor device 64 are mounted on a second surface 6b. Each of the components of the first semiconductor device 61 to the fourth semiconductor device 64 functions in the same manner as each of the components of the relay monitoring circuit 1 in Fig. 1. That is, each of the first semiconductor device 61 to the fourth semiconductor device 64 outputs a voltage corresponding to the difference between the voltage of the first input terminal T1 and the voltage of the second input terminal T2 included in the semiconductor device from the output terminal T3 of the semiconductor device as a signal for determining whether the relay connected to the first input terminal T1 and the second input terminal T2 is welded.

[0077] The power supply monitoring unit 603 is configured by a fifth semiconductor integrated circuit device 65 (hereinafter also simply referred to as "fifth semiconductor device 65") that constitutes the power supply monitoring unit 13 of the power supply wiring monitoring circuit 10 in Figure 3. Therefore, the power supply monitoring unit 603 functions as described for the power supply monitoring unit 13 in Figure 3, and outputs a voltage based on the potential difference between the positive electrode BP and negative electrode BN of the DC power supply VBAT. As shown in Figure 5A, the fifth semiconductor device 65 includes each component of the relay monitoring circuit 1 in Figure 1.

[0078] The components of the first semiconductor device 61 to the fifth semiconductor device 65 are assigned the same reference numerals as those assigned to the corresponding components in the relay monitoring circuit 1 of Fig. 1 or are omitted as appropriate, and repeated explanations of those components will be omitted. Also, the functions and actions of the individual components of the first semiconductor device 61 to the fifth semiconductor device 65 are similar to the functions and actions of the corresponding components in the relay monitoring circuit 1 of Fig. 1, so repeated explanations of those components will be omitted.

[0079] The wiring board 60 includes a base material 68 formed of an insulating material such as a glass epoxy material or a ceramic material, and conductor patterns 671 to 678 formed of a conductor such as copper on the base material 68. The conductor patterns 671, 672, 675, and 676 are formed on the first surface 6a, and the conductor patterns 673, 674, 677, and 678 are formed on the second surface 6b. The wiring board 60 further includes through conductors 661 to 664 that penetrate the base material 68. The through conductor 661 connects the conductor pattern 671 to the conductor pattern 673, and the through conductor 662 connects the conductor pattern 672 to the conductor pattern 674. The through conductor 663 connects the conductor pattern 675 to the conductor pattern 677, and the through conductor 664 connects the conductor pattern 676 to the conductor pattern 678. The negative electrode BN of the DC power supply VBAT is connected to the conductive pattern 671 , the positive electrode BP of the DC power supply VBAT is connected to the conductive pattern 675 , and a load L is connected between the conductive patterns 672 and 676 .

[0080] The first input terminal T1 of the first semiconductor device 61 is connected to the conductor pattern 671, and the second input terminal T2 of the first semiconductor device 61 is connected to the conductor pattern 672. The first terminal RT1 of the first relay RL1 is also connected to the conductor pattern 671, and the second terminal RT2 of the first relay RL1 is also connected to the conductor pattern 672. The first input terminal T1 of the second semiconductor device 62 is connected to the conductor pattern 673, and the second input terminal T2 of the second semiconductor device 62 is connected to the conductor pattern 674. Therefore, the first terminal RT1 of the first relay RL1 and the first input terminal T1 of the first semiconductor device 61 are electrically connected to the first input terminal T1 of the second semiconductor device 62 via the conductor patterns 671 and 673 and the through conductor 661. Furthermore, the second terminal RT2 of the first relay RL1 and the second input terminal T2 of the first semiconductor device 61 are electrically connected to the second input terminal T2 of the second semiconductor device 62 via the conductor patterns 672 and 674 and the through conductor 662.

[0081] Furthermore, the first input terminal T1 of the third semiconductor device 63 is connected to the conductor pattern 675, and the second input terminal T2 of the third semiconductor device 63 is connected to the conductor pattern 676. The first terminal RT1 of the second relay RL2 is also connected to the conductor pattern 675, and the second terminal RT2 of the second relay RL2 is also connected to the conductor pattern 676. The first input terminal T1 of the fourth semiconductor device 64 is connected to the conductor pattern 677, and the second input terminal T2 of the fourth semiconductor device 64 is connected to the conductor pattern 678. Therefore, the first terminal RT1 of the second relay RL2 and the first input terminal T1 of the third semiconductor device 63 are electrically connected to the first input terminal T1 of the fourth semiconductor device 64 via the conductor patterns 675, 677, and the through conductor 663. Furthermore, the second terminal RT2 of the second relay RL2 and the second input terminal T2 of the third semiconductor device 63 are electrically connected to the second input terminal T2 of the fourth semiconductor device 64 via the conductor patterns 676, 678, and the through conductor 664.

[0082] Therefore, in the power wiring monitoring module 6 of the embodiment shown in FIGS. 5A to 5D, both the first semiconductor device 61 and the second semiconductor device 62 output a signal for determining whether the first relay RL1 is welded. Furthermore, both the third semiconductor device 63 and the fourth semiconductor device 64 output a signal for determining whether the second relay RL2 is welded. That is, the power wiring monitoring module 6 of the embodiment shown in FIGS. 5A to 5D has redundancy in generating the signals for determining whether the first relay RL1 and the second relay RL2 are welded. This can improve the reliability of detecting whether the first relay RL1 and the second relay RL2 are welded. Note that the power wiring monitoring module 6 of the embodiment may have redundancy only in generating the signals for determining whether either the first relay RL1 or the second relay RL2 is welded. For example, only either the second semiconductor device 62 or the fourth semiconductor device 64 may be provided.

[0083] In the power wiring monitoring module 6 shown in FIGS. 5A to 5D, the first semiconductor device 61 and the second semiconductor device 62 are mounted so as to overlap with each other via the wiring substrate 60. Similarly, the third semiconductor device 63 and the fourth semiconductor device 64 are mounted so as to overlap with each other via the wiring substrate 60. In particular, in the example shown in FIGS. 5A to 5D, the first semiconductor device 61 and the second semiconductor device 62 almost completely overlap with each other in a plan view. The third semiconductor device 63 and the fourth semiconductor device 64 almost completely overlap with each other in a plan view. Therefore, while providing four semiconductor devices that provide redundancy, an increase in the area of the wiring substrate 60 is suppressed. Note that the first semiconductor device 61 and the second semiconductor device 62 do not necessarily have to completely overlap with each other and may, for example, partially overlap with each other. The third semiconductor device 63 and the fourth semiconductor device 64 do not necessarily have to completely overlap with each other and may, for example, partially overlap with each other.

[0084] Furthermore, the first semiconductor device 61 and the third semiconductor device 63 are mounted on the first surface 6a of the wiring board 60, and the second semiconductor device 62 and the fourth semiconductor device 64 are mounted on the second surface 6b of the wiring board 60. Therefore, as described above with respect to the relay monitoring module 5 in Figures 4A to 4C, it is possible to realize a small-sized power supply wiring monitoring circuit with redundancy while ensuring the creepage distance.

[0085] 5A to 5D, the first input terminals T1 and T2 of the second semiconductor device 62 are arranged in an inverted arrangement relative to the arrangement of the first input terminals T1 and T2 of the first semiconductor device 61. Also, the first input terminals T1 and T2 of the fourth semiconductor device 64 are arranged in an inverted arrangement relative to the arrangement of the first input terminals T1 and T2 of the third semiconductor device 63. Therefore, similar to the effect described above with respect to the relay monitoring module 5 of FIGS. 4A to 4C, it may be possible to realize an even more compact power wiring monitoring circuit.

[0086] 5A to 5D, the first input terminals T1 and T2 of the third semiconductor device 63 are arranged in an inverted arrangement relative to the arrangement of the first input terminals T1 and T2 of the first semiconductor device 61. Similarly, the first input terminals T1 and T2 of the fourth semiconductor device 64 are arranged in an inverted arrangement relative to the arrangement of the first input terminals T1 and T2 of the second semiconductor device 62. Therefore, the area to which a high voltage is applied can be limited to the area between the conductor patterns 671 and 672, the conductor patterns 675 and 676, and the area between the conductor patterns 673 and 674, and the conductor patterns 677 and 678. Because the area where creepage distance must be ensured is limited, a more compact power supply wiring monitoring circuit can be realized. [Explanation of symbols]

[0087] 1 Relay monitoring circuit 1a Semiconductor integrated circuit device 10 Power wiring monitoring circuit 10a Judgment circuit 100 Welding detection circuit 11 First relay monitoring unit 12 Second relay monitoring unit 13 Power supply monitoring section 2. Operational Amplifiers 2n negative feedback amplifier circuit 3. First voltage divider circuit 31 1st resistor 32 2nd resistor 4 Second voltage divider circuit 43 3rd resistor 44 4th resistor 5 Relay Monitoring Module 50 Wiring board 5a 1st page 5b 2nd side 51 First semiconductor integrated circuit device 52 Second semiconductor integrated circuit device 6 Power wiring monitoring module 60 Wiring board 6a 1st page 6b 2nd side 600 Power wiring monitoring circuit 601 First Relay Monitoring Unit 602 Second Relay Monitoring Unit 61 First semiconductor integrated circuit device 62 Second semiconductor integrated circuit device 63 Third semiconductor integrated circuit device 64 Fourth semiconductor integrated circuit device 65 Fifth semiconductor integrated circuit device BN Negative pole of DC power supply BP Positive pole of DC power supply E11 One side of the first semiconductor integrated circuit device E12 One side of the second semiconductor integrated circuit device RL High-voltage relay RL1 First high-voltage relay RL2 Second high-voltage relay RT1 High-voltage relay terminal 1 RT2 Second terminal of high voltage relay T1 First input terminal T2 Second input terminal T3 output terminal VBAT DC power supply Vf1 First voltage Vf2 Second voltage Vi1 Voltage of the first input terminal Vi2 Voltage of the second input terminal Vo, Vo1, Vo2 welding judgment signals Vop Output voltage of the power supply monitor Vref Reference potential

Claims

1. A relay monitoring circuit that outputs a signal for determining whether a high-voltage relay is welded, a first input terminal connected to one of two terminals sandwiching an opening / closing portion of the high-voltage relay; a second input terminal connected to the other of the two terminals; an output terminal for outputting the determination signal; a first voltage divider circuit that generates a first voltage that is a voltage obtained by stepping down the voltage at the first input terminal; a second voltage dividing circuit that generates a second voltage that is a voltage obtained by stepping down the voltage at the second input terminal; a negative feedback amplifier circuit configured to output a voltage corresponding to a difference between a voltage at the first input terminal and a voltage at the second input terminal by applying the first voltage and the second voltage to the output terminal; a relay monitoring circuit including:

2. the first voltage dividing circuit is provided between the first input terminal and a predetermined reference potential, the second voltage dividing circuit is provided between the second input terminal and the output terminal, the negative feedback amplifier circuit includes an operational amplifier connected in negative feedback; 2. The relay monitoring circuit of claim 1, wherein the first voltage is applied to a non-inverting input terminal of the operational amplifier, and the second voltage is applied to an inverting input terminal of the operational amplifier.

3. the first voltage dividing circuit includes a first resistor and a second resistor connected in series; the second voltage dividing circuit includes a third resistor and a fourth resistor connected in series; the first resistor is provided between the first input terminal and the non-inverting input terminal, the second resistor is provided between the non-inverting input terminal and the reference potential, the third resistor is provided between the second input terminal and the inverting input terminal, the fourth resistor is provided between the inverting input terminal and the output terminal; 3. The relay monitoring circuit according to claim 2.

4. a resistance value of the first resistor and a resistance value of the third resistor are substantially the same; The resistance value of the second resistor and the resistance value of the fourth resistor are substantially the same.

4. The relay monitoring circuit according to claim 3.

5. a resistance value of the second resistor is 0.3% or more and 1.0% or less of a resistance value of the first resistor, a resistance value of the fourth resistor is 0.3% or more and 1.0% or less of a resistance value of the third resistor; 5. The relay monitoring circuit according to claim 4.

6. 2. The relay monitoring circuit according to claim 1, wherein said first voltage dividing circuit, said second voltage dividing circuit, and said negative feedback amplifier circuit are configured by a single semiconductor integrated circuit device for monitoring high voltages.

7. a power supply wiring monitoring circuit that outputs a signal for determining whether a first high-voltage relay connected to one of a positive electrode and a negative electrode of a DC power supply and a second high-voltage relay connected to the other of the positive electrode and the negative electrode of the DC power supply are welded, a first relay monitoring unit and a second relay monitoring unit, each of which is configured by the relay monitoring circuit according to any one of claims 1 to 5; a power supply monitoring unit connected to the positive electrode and the negative electrode, the first relay monitoring unit is configured to output a signal for determining whether the first high-voltage relay is welded by connecting the first input terminal and the second input terminal included in the first relay monitoring unit to the first high-voltage relay, the second relay monitoring unit is configured to output a signal for determining whether the second high-voltage relay is welded by connecting the first input terminal and the second input terminal included in the second relay monitoring unit to the second high-voltage relay, The power supply monitoring unit is configured to output a voltage based on a potential difference between the positive electrode and the negative electrode.

8. the first relay monitoring unit, the second relay monitoring unit, and the power supply monitoring unit are each configured by a single semiconductor integrated circuit device for high voltage monitoring, 8. The power supply wiring monitoring circuit according to claim 7, wherein the high-voltage monitor semiconductor integrated circuit device constituting at least one of the first relay monitoring unit and the second relay monitoring unit and the high-voltage monitor semiconductor integrated circuit device constituting the power supply monitoring unit are of the same type.

9. a welding detection circuit for detecting welding of a first high-voltage relay connected to one of a positive electrode and a negative electrode of a DC power supply and a second high-voltage relay connected to the other of the positive electrode and the negative electrode of a DC power supply, a power supply wiring monitoring circuit according to claim 7; a determination circuit configured to determine whether the first high-voltage relay and the second high-voltage relay are welded based on the determination signals from the first relay monitoring unit and the second relay monitoring unit when the output voltage of the power supply monitoring unit indicates that the potential difference between the positive electrode and the negative electrode is equal to or greater than a predetermined voltage; a weld detection circuit including:

10. a first semiconductor integrated circuit device and a second semiconductor integrated circuit device each constituting the relay monitoring circuit according to any one of claims 1 to 5; a wiring substrate having a first surface on which the first semiconductor integrated circuit device is mounted and a second surface opposite to the first surface; A relay monitoring module including: the second semiconductor integrated circuit device is mounted on the second surface and overlaps the first semiconductor integrated circuit device via the wiring substrate, the first input terminal of the first semiconductor integrated circuit device and the first input terminal of the second semiconductor integrated circuit device are electrically connected; a relay monitoring module in which the second input terminal of the first semiconductor integrated circuit device and the second input terminal of the second semiconductor integrated circuit device are electrically connected to each other;

11. the first input terminal and the second input terminal of the first semiconductor integrated circuit device are arranged on one side of the first semiconductor integrated circuit device, 11. The relay monitoring module according to claim 10, wherein the first input terminals and the second input terminals of the second semiconductor integrated circuit device are arranged on one side of the second semiconductor integrated circuit device in an arrangement opposite to the arrangement of the first input terminals and the second input terminals of the first semiconductor integrated circuit device on the one side.

12. a power supply wiring monitoring circuit according to claim 7; a wiring board having a first surface and a second surface opposite to the first surface, the wiring board having the power wiring monitoring circuit mounted thereon, the first relay monitoring unit includes a first semiconductor integrated circuit device and a second semiconductor integrated circuit device that respectively configure the relay monitoring circuit of the first relay monitoring unit, the first semiconductor integrated circuit device is mounted on the first surface, the second semiconductor integrated circuit device is mounted on the second surface and overlaps the first semiconductor integrated circuit device via the wiring substrate, the first input terminal of the first semiconductor integrated circuit device and the first input terminal of the second semiconductor integrated circuit device are electrically connected; a power supply wiring monitoring module in which the second input terminal of the first semiconductor integrated circuit device and the second input terminal of the second semiconductor integrated circuit device are electrically connected to each other;

13. A welding detection method for detecting welding of a high-voltage relay, comprising: a first voltage divider circuit provided between the one terminal and a predetermined reference potential and reducing the voltage of one of the two terminals sandwiching an open / close unit of the high-voltage relay, and applying the reduced voltage to a non-inverting input terminal of an operational amplifier connected in negative feedback; applying the voltage of the other of the two terminals to the inverting input terminal of the operational amplifier via a second voltage divider circuit provided between the other terminal and an output terminal of the operational amplifier; determining whether the high-voltage relay is welded based on the output voltage of the operational amplifier; Including, the welding detection method determining that the high-voltage relay is welded when the potential of the output terminal of the operational amplifier is substantially the same as the predetermined reference potential in a state in which the high-voltage relay is controlled so as to be in an open state.

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