Fault detection device and semiconductor device

Abstract

To provide a fault detection device capable of detecting a fault in an electromagnetic contactor with a simple configuration.SOLUTION: A fault detection device 100 detects an abnormality in a switching unit that opens and closes a current path by a current flowing through a coil. The fault detection device 100 includes: a current detection unit 110 that detects the value of a current flowing through the coil; and a voltage conversion unit 130 that converts the current value into a voltage value. The fault detection device 100 also includes: an averaged signal generation unit 160a that generates an averaged signal obtained by averaging fluctuations in the voltage value; and a comparator Comp that detects an abnormality in the switching unit by comparing the voltage value with the averaged signal.SELECTED DRAWING: Figure 3A

Description

Technical Field

[0001] The present disclosure relates to a failure detection device and a semiconductor device.

Background Art

[0002] Conventionally, a technique for detecting a failure of a power supply device including an electromagnetic contactor has been proposed. Patent Document 1 discloses a relay failure detection device that detects a failure of a relay contact provided in a power supply device. The relay failure detection device disclosed in Patent Document 1 detects a failure of a relay by detecting the presence or absence of a change in the inductance of a relay internal coil from a change in the current value flowing through the relay internal coil.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The relay failure detection device disclosed in Patent Document 1 determines the presence or absence of contact welding by differentiating the drive current value of the coil with respect to a change in the current value. However, determining the presence or absence of contact welding by differentiating the drive current value of the coil requires a device such as a CPU that performs a differentiation operation, increasing the circuit scale.

[0005] The present disclosure has been made in view of the problems of such conventional techniques. An object of the present disclosure is to provide a failure detection device capable of detecting a failure of an electromagnetic contactor with a simple configuration.

Means for Solving the Problems

[0006] A failure detection device according to an aspect of the present disclosure is a failure detection device that detects an abnormality of an opening / closing unit that opens and closes a current path by a current flowing through a coil, and includes a current detection unit that detects a current value flowing through the coil, a voltage conversion unit that converts the current value into a voltage value, an averaging signal generation unit that generates an averaging signal obtained by averaging fluctuations in the voltage value, and a comparator that detects an abnormality of the opening / closing unit by comparing the voltage value and the averaging signal.

[0007] A semiconductor device according to another aspect of the present disclosure includes an opening / closing unit that opens and closes a current path by a current flowing through a coil, and the above-described failure detection device.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to provide a failure detection device that can detect a failure of an electromagnetic contactor with a simple configuration.

Brief Description of the Drawings

[0009]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 7A

Figure 7B

Figure 7C

DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the failure detection device 100 and the semiconductor device 10 according to some embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings of the failure detection device 100 and the semiconductor device 10 according to each embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0011] (First Embodiment) FIG. 1A and FIG. 1B are diagrams showing the configuration of the semiconductor device 10 to which the failure detection device 100 according to the present embodiment is applied. As shown in FIGS. 1A and 1B, the semiconductor device 10 includes a contactor 200 and a failure detection device 100. Further, the failure detection device 100 includes a current detection unit 110, a voltage conversion unit 130, and a failure detection unit 150. Details of the current detection unit 110, the voltage conversion unit 130, and the failure detection unit 150 will be described later. Note that FIG. 1A shows the configuration when the current detection unit 110 is connected to the low side of the contactor 200. FIG. 1B shows the configuration when the current detection unit 110 is connected to the high side of the contactor 200.

[0012] The contactor 200 is composed of an electromagnetic coil and a contact. The contactor 200 opens and closes the contact by a magnetic field generated by the current flowing through the electromagnetic coil. That is, the contactor 200 is driven by the current flowing through the coil and opens and closes the current path. Note that the contactor 200 corresponds to an opening / closing unit. The failure detection device 100 according to the present embodiment is a device that detects an abnormality of the contactor 200.

[0013] FIG. 2A is a diagram for explaining the current when the contactor 200 is normal with respect to the current flowing through the coil. FIG. 2B is a diagram for explaining the current when the contactor 200 has a welding failure with respect to the current flowing through the coil.

[0014] As shown in FIG. 2A, when the contactor 200 is normal, the value of the current flowing through the coil vibrates at the timing when the contact actually connects. For example, in the above-mentioned Patent Document 1, the characteristics of the current whose slope changes due to this current fluctuation are detected by differential processing, and a normal state is determined.

[0015] Further, as shown in FIG. 2B, when the contactor 200 has a welding failure such as contact welding, the current fluctuation of the coil increases while showing a certain tendency. That is, when the contactor 200 has a welding failure, the vibration of the current value as shown in FIG. 2A does not occur.

[0016] The fault detection device 100 according to this embodiment realizes the detection of the welding fault of the electromagnetic contactor (contactor 200) due to the oscillation of this current value with a simple configuration without providing a device that performs special processing such as differential processing.

[0017] (Configuration of the fault detection device 100) Next, the configuration of the fault detection device 100 according to this embodiment will be described. FIGS. 3A and 3B are diagrams showing an example of the configuration of the fault detection device 100 according to the first embodiment. Note that FIG. 3A shows the configuration when the current detection unit 110 is connected to the low side of the contactor 200. Further, FIG. 3B shows the configuration when the current detection unit 110 is connected to the high side of the contactor 200. Hereinafter, the description will proceed centering on the configuration of FIG. 3A.

[0018] As described above, the fault detection device 100 includes a current detection unit 110, a voltage conversion unit 130, and a fault detection unit 150. The current detection unit 110 detects the current value flowing through the coil. In the configuration shown in FIG. 3A, the current detection unit 110 includes a drive circuit 111 and an amplifier Amp whose first input terminal is connected to the coil. Further, the current detection unit 110 includes a low-side MOS 112a whose one end is connected to the coil and the first input terminal of the amplifier Amp and is controlled by the drive circuit 111. Further, the current detection unit 110 includes a sense MOS 113 whose one end is connected to the second input terminal of the amplifier Amp and is controlled by the drive circuit 111. Note that in the configuration example shown in FIG. 3A, the first input terminal of the amplifier Amp corresponds to the plus terminal (+). Further, the second input terminal of the amplifier Amp corresponds to the minus terminal (-). Note that in the configuration shown in FIG. 3A, the low-side MOS 112a corresponds to a current detection MOS.

[0019] On the other hand, in the configuration shown in FIG. 3B, the current detection unit 110 includes a drive circuit 111 and an amplifier Amp whose first input terminal is connected to the coil. Further, the current detection unit 110 includes a high-side MOS 112b whose one end is connected to the coil and the first input terminal of the amplifier Amp and which is controlled by the drive circuit 111. Further, the current detection unit 110 includes a sense MOS 113 whose one end is connected to the second input terminal of the amplifier Amp and which is controlled by the drive circuit 111. In the configuration example shown in FIG. 3B, the first input terminal of the amplifier Amp corresponds to the minus terminal (-). Further, the second input terminal of the amplifier Amp corresponds to the plus terminal (+). Note that in the configuration shown in FIG. 3B, the high-side MOS 112b corresponds to a current detection MOS.

[0020] With this configuration, for the current I flowing through the coil D a current corresponding to the ratio of the sense MOS 113 to the low-side MOS 112a or the high-side MOS 112b is output to the voltage conversion unit 130 via the transistor circuit 115 and the current mirror circuit 116. That is, in the first embodiment, the current detection unit 110 detects the current flowing through the low side or the high side of the coil, and the detected current is output to the voltage conversion unit 130.

[0021] The voltage conversion unit 130 converts the current value flowing through the coil detected by the current detection unit 110 into a voltage value. The voltage conversion unit 130 is configured by a general voltage conversion circuit including an amplifier and a resistor. The voltage converted in the voltage conversion unit 130 is output to the fault detection unit 150.

[0022] The fault detection unit 150 includes an averaging signal generation unit 160a that generates an averaging signal obtained by averaging the fluctuations in the voltage value converted by the voltage conversion unit 130. Further, the fault detection unit 150 includes a comparator Comp that compares the voltage value converted by the voltage conversion unit 130 with the averaging signal to detect an abnormality of the contactor 200.

[0023] In the example shown in FIGS. 3A and 3B, the averaging signal generation unit 160a includes a diode D1 whose anode side is connected to the voltage conversion unit 130. Further, the averaging signal generation unit 160a includes a first voltage dividing resistor Rb1 connected in series with the cathode side of the diode D1. Further, the averaging signal generation unit 160a includes a second voltage dividing resistor Rb2 having one end connected in series with the first voltage dividing resistor Rb1 and the other end connected to the reference potential. Further, the averaging signal generation unit 160a includes a capacitor Cb connected in parallel with the second voltage dividing resistor Rb2. The averaging signal generated by the averaging signal generation unit 160a is the voltage value of the capacitor Cb. That is, the averaging signal generation unit 160a generates an averaging signal in which the change in voltage is averaged by the capacitor Cb having a predetermined capacitance.

[0024] Also, in the example shown in FIGS. 3A and 3B, the failure detection unit 150 includes a resistor Ra1 and a resistor Ra2 that divide the voltage output from the voltage conversion unit 130 without passing through a diode. Further, the failure detection unit 150 includes a capacitor Ca connected in parallel with the resistor Ra2. The failure detection unit 150 obtains effects such as noise by the capacitor Ca. Note that the capacitance of the capacitor Cb is sufficiently larger, about 20 to 100 times, than the capacitance of the capacitor Ca. Note that the failure detection unit 150 may be configured not to include the capacitor Ca.

[0025] FIG. 4A is a diagram showing the waveform of the internal voltage in the failure detection unit 150 when the contactor 200 is normal in the first embodiment. FIG. 4B is a diagram showing the waveform of the internal voltage in the failure detection unit 150 when the contactor 200 is abnormal in the first embodiment.

[0026] In the example shown in FIGS. 4A and 4B, I Dshows the drain current of the low-side MOS 112a in the configuration of FIG. 3A. Also, in the internal voltage of the fault detection unit, the voltage Vs, the voltage Va, and the voltage Vb respectively represent the voltage of the node Ns, the voltage of the node Na, and the voltage of the node Nb. Also, CMP_out represents the output value of the comparator Comp. Further, FF_out represents the output value of the flip-flop FF.

[0027] In the examples shown in FIGS. 4A and 4B, current starts to flow through the coil at time T1 and time T5. The voltage Va becomes a value that is resistively divided by the resistors Ra1 and Ra2 with respect to the voltage Vs converted by the voltage conversion unit 130. On the other hand, the voltage Vb rises when it becomes equal to or higher than the forward voltage (Vf) of the diode D1 (at time T2 and time T6). Therefore, the voltage Vb becomes lower than the voltage Va, and the output CMP_out of the comparator Comp becomes a low level.

[0028] When the contactor 200 shown in FIG. 4A is normal, when the contact is connected at time T3, the signal waveform oscillates as shown in FIG. 2A. Therefore, the voltage Va decreases and increases following the oscillation, but the change in the voltage Vb is averaged by the capacitance of the capacitor Cb. Therefore, as shown in FIG. 4A, at time T4, the value of the voltage Vb becomes higher than the value of the voltage Va. As a result, the output of the comparator Comp becomes a high level, and the normal operation of the contactor 200 is detected.

[0029] On the other hand, no oscillation occurs during a fault such as when the contact of the contactor 200 is welded. Therefore, as shown in FIG. 4B, there is no period during which the value of the voltage Vb becomes higher than the value of the voltage Va, and the output of the comparator Comp remains at a low level. As a result, the fault detection device 100 can detect a fault in the contactor 200.

[0030] That is, when the voltage value converted by the voltage conversion unit 130 changes (fluctuates), the averaging signal generation unit 160a generates an averaging signal that averages out the change (fluctuation) according to the capacitance of the capacitor Cb. On the other hand, when the voltage value converted by the voltage conversion unit 130 does not fluctuate, the averaging signal generation unit 160a generates the voltage value of the capacitor Cb as the averaging signal as it is.

[0031] As described above, the fault detection device 100 according to the first embodiment is a fault detection device 100 that detects an abnormality in an opening / closing unit that opens and closes a current path by the current flowing through a coil. The fault detection device 100 includes a current detection unit 110 that detects the current value flowing through the coil, and a voltage conversion unit 130 that converts the current value into a voltage value. Further, the fault detection device 100 includes an averaging signal generation unit 160a that generates an averaging signal obtained by averaging the fluctuation of the voltage value, and a comparator Comp that detects an abnormality in the opening / closing unit by comparing the voltage value with the averaging signal.

[0032] Thereby, the fault detection device 100 according to the first embodiment does not need to provide a circuit that performs special processing such as differential processing, and can detect a fault in the electromagnetic contactor with a simple configuration by comparing the current detection signal with the signal obtained by averaging the fluctuation.

[0033] Also, the current detection unit 110 of the fault detection device 100 may include a drive circuit 111, an amplifier Amp whose first input terminal is connected to the coil, and a current detection MOS whose one end is connected to the coil and the first input terminal of the amplifier Amp and is controlled by the drive circuit 111. Further, the current detection unit 110 may have a sense MOS 113 whose one end is connected to the second input terminal of the amplifier Amp and is controlled by the drive circuit 111. Thereby, the fault detection device 100 according to the first embodiment can detect an accurate current value with a simple configuration, and can improve the accuracy of fault detection. Note that the current detection MOS corresponds to the low-side MOS 112a or the high-side MOS 112b.

[0034] Furthermore, the averaging signal generation unit 160a of the failure detection device 100 includes a diode D1 with its anode side connected to the voltage conversion unit 130, and a first voltage dividing resistor Rb1 connected in series to the cathode side of the diode D1. Also, the averaging signal generation unit 160a includes a second voltage dividing resistor Rb2 with one end connected in series to the first voltage dividing resistor Rb1 and the other end connected to the reference potential. Further, the averaging signal generation unit 160a has a capacitor Cb connected in parallel to the second voltage dividing resistor Rb2. Moreover, the averaging signal generated by the averaging signal generation unit 160a is the voltage value of the capacitor Cb. Thereby, the failure detection device 100 can generate an averaging signal necessary for failure detection with a simple configuration.

[0035] (Second Embodiment) As described above, one specific embodiment has been described, but the above-described embodiments are examples and do not limit the embodiments. For example, in the above-described embodiments, the averaging signal generation unit 160a of the failure detection unit 150 is exemplified in a form including a voltage dividing resistor and a capacitor Cb. Here, a failure detection device 100 according to a second embodiment in which the averaging signal generation unit of the failure detection unit 150 is configured by a peak hold circuit 160b will be described with respect to configurations different from those of the first embodiment.

[0036] FIGS. 5A and 5B are diagrams showing the configuration of the failure detection device 100 according to the second embodiment. Note that FIG. 5A shows the configuration when the current detection unit 110 is connected to the low side of the contactor 200. Also, FIG. 5B shows the configuration when the current detection unit 110 is connected to the high side of the contactor 200. As shown in FIGS. 5A and 5B, the failure detection device 100 according to the second embodiment is different from the failure detection device 100 according to the first embodiment in that it includes a peak hold circuit 160b as an averaging signal generation unit.

[0037] In the failure detection device 100 according to the second embodiment shown in FIGS. 5A and 5B, a signal converted into a voltage by the voltage conversion unit 130 is input to the minus terminal of the comparator Comp. Further, a signal converted into a voltage by the voltage conversion unit 130 is input to the peak hold circuit 160b after being resistance-divided.

[0038] FIG. 6A is a diagram showing the waveform of the failure detection unit 150 when the contactor 200 is normal in the second embodiment. FIG. 6B is a diagram showing the waveform of the failure detection unit 150 when the contactor 200 is abnormal in the second embodiment.

[0039] In the examples shown in FIGS. 6A and 6B, I D represents the drain current of the low-side MOS 112a in the configuration of FIG. 5A. Also, in the internal voltage of the failure detection unit, the voltages Vc and Vd represent the voltage of the node Nc and the voltage of the node Nd, respectively. Further, CMP_out represents the output value of the comparator Comp. Furthermore, FF_out represents the output value of the flip-flop FF.

[0040] In FIGS. 6A and 6B, when a drive current flows through the coil (at times T7 and T10), the voltage Vd of the node Nd, which is the output value of the peak hold circuit 160b, rises to a lower value by the amount of resistance division with respect to the voltage Vc of the node Nc, which is the voltage output from the voltage conversion unit 130. Therefore, the output of the comparator Comp becomes low level.

[0041] In the example shown in FIG. 6A, when the contact connects at time T8, the signal waveform vibrates. At this time, the voltage Vc of the node Nc decreases and increases following the vibration. On the other hand, since the output value of the peak hold circuit 160b holds the peak value of the voltage, the voltage Vd of the node Nd does not decrease. Therefore, at time T9, the value of the voltage Vd becomes higher than the value of the voltage Vc. As a result, the output of the comparator Comp becomes high level.

[0042] On the other hand, when a failure such as welding of the contacts of the contactor 200 occurs, vibration does not occur. Therefore, as shown in FIG. 6B, there is no period during which the value of the voltage Vd is higher than the value of the voltage Vc, and the output of the comparator Comp remains at a low level. As a result, the failure detection device 100 can detect a failure of the contactor 200.

[0043] As described above, the averaging signal generation unit of the failure detection device 100 according to the second embodiment may generate an averaging signal using the output of the voltage conversion unit 130 as a peak value. That is, as the averaging signal generation unit, the peak hold circuit 160b may be applied to the failure detection device 100 according to the second embodiment. Thereby, the failure detection device 100 according to the second embodiment can realize a function of detecting a failure in the contactor 200 with a simple configuration using, for example, a general peak hold circuit 160b.

[0044] (Other Embodiments) Although the embodiments have been described in detail with reference to the drawings, the present embodiment is not limited by the contents described in the above embodiments. In addition, the constituent elements described above include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described above can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the embodiment.

[0045] As described above, in the current detection unit 110 of the failure detection device 100 according to the first and second embodiments, a configuration in which the current flowing through the coil is detected using the sense MOS 113 is shown, but the configuration of the embodiment is not limited to this. FIGS. 7A, 7B, and 7C show a configuration in the case where the current value is detected using a resistor instead of the sense MOS 113.

[0046] In the configuration shown in FIG. 7A, similar to the first and second embodiments, the current detection unit 110 includes a drive circuit 111, an amplifier Amp, and a low-side MOS 112a whose drain terminal is connected to a coil. The current detection unit 110 also includes a first resistor R1 having one end connected to the source terminal of the low-side MOS 112a and the other end connected to the first input terminal of the amplifier Amp, and a second resistor R2 having one end connected to the second input terminal of the amplifier Amp. The current detection unit 110 further includes a third resistor R3 having one end connected to the source terminal of the low-side MOS 112a and the other end connected to the other end of the second resistor R2. In the example shown in FIG. 7A, the first input terminal of the amplifier Amp corresponds to the plus terminal (+). Also, the second input terminal of the amplifier Amp corresponds to the minus terminal (-).

[0047] In the example shown in FIG. 7A, assuming that the drive current of the contactor 200 is current Io and the output current of the current detection unit 110 is current Im, the current Im can be obtained by the following calculation. First, assuming that the input current of the amplifier Amp is 0 A, the voltage Vp at the plus terminal of the amplifier Amp is obtained by the following equation (1). Vp = V1 = V2+(Io × R3) ··· (1)

[0048] Also, the voltage Vm at the minus terminal of the amplifier Amp is obtained by the following equation (2). Vm = V2+(Im × R2) ··· (2)

[0049] Here, from Vp = Vm, the following equations (3) and (4) are derived from the above equations (1) and (2). V2+(Io × R3)=V2+(Im × R2) ··· (3) Io × R3 = Im × R2 ··· (4)

[0050] Then, from equation (4), the current Im, which is the output current of the current detection unit 110, is determined by the following equation (5). Im = Io(R3 / R2) ··· (5)

[0051] In this way, in the configuration of the current detection unit 110, by configuring it without using the sense MOS 113, the failure detection device 100 shown in FIG. 7A can realize the function of current detection with a simple configuration having a small circuit scale.

[0052] In the configuration shown in FIG. 7A, an example where the first resistor R1, the second resistor R2, and the third resistor R3 are located on the reference potential (GND) side is shown. However, this configuration does not limit the configuration of the embodiment. For example, a configuration as shown in FIG. 7B may be used. Also in the example shown in FIG. 7B, similar to the configuration of FIG. 7A, the current Im is determined by the above formulas (1) to (5), and the function of current detection can be realized with a simple configuration having a small circuit scale.

[0053] Further, in FIGS. 7A and 7B, a configuration in which the low-side MOS 112a is applied as the MOS for current detection driven by the drive circuit 111 is shown. However, the configuration of the embodiment is not limited thereto. For example, the current detection unit 110 may be configured to use the high-side MOS 112b as the MOS for current detection as shown in FIG. 7C.

[0054] In the configuration shown in FIG. 7C, the current detection unit 110 includes a drive circuit 111, an amplifier Amp, and a high-side MOS 112b whose drain terminal is connected to the battery. The current detection unit 110 also includes a fourth resistor having one end connected to the source terminal of the high-side MOS 112b and the other end connected to the first input terminal of the coil and the amplifier Amp. The current detection unit 110 also includes a fifth resistor R5 having one end connected to the source terminal of the high-side MOS 112b and the other end connected to the second input terminal of the amplifier Amp. In the example shown in FIG. 7C, the first input terminal of the amplifier Amp corresponds to the plus terminal (+). Also, the second input terminal of the amplifier Amp corresponds to the minus terminal (-). The fourth resistor corresponds to the current detection resistor R4.

[0055] In the example shown in FIG. 7C, similar to FIGS. 7A and 7B, the drive current of the contactor 200 is defined as current Io, and the output current of the current detection unit 110 is defined as current Im. Also, a current detection resistor R4 is provided. The current Im can be obtained by the following calculation.

[0056] First, the value of voltage V3 can be obtained by the following formula (6). V3 = V4+(Io × R4) ··· (6)

[0057] Also, assuming that the input current of the amplifier Amp is 0A, then Vp = V4, and Vm can be obtained by the following formula (7). Vm = V3-(Im × R5) ··· (7)

[0058] Here, since Vp = Vm = V4, the following formula (8) is derived from the above formula (7). V4 = V3-(Im × R5) ··· (8)

[0059] Also, V3 is derived from formula (8) as in the following formula (9). V3 = V4+(Im × R5) ··· (9)

[0060] Here, the following formulas (10) and (11) are derived from the above formulas (6) and (9). V4+(Io × R4)=V4+(Im × R5) ··· (10) Io × R4 = Im × R5 ··· (11)

[0061] Then, according to formula (11), the current Im, which is the output current of the current detection unit 110, is determined by the following formula (5). Im = Io(R4 / R5) ··· (12)

[0062] In this way, also in the configuration of the current detection unit 110 according to FIG. 7C, by configuring without using the sense MOS113, the fault detection device 100 shown in FIG. 7C can realize the function of current detection with a simple configuration having a small circuit scale.

[0063] The features of the fault detection device 100 will be described below.

[0064] The fault detection device 100 according to the first aspect is a fault detection device 100 that detects an abnormality of an opening / closing unit that opens and closes a current path by the current flowing through a coil. The fault detection device 100 includes a current detection unit 110 that detects a current value flowing through the coil, and a voltage conversion unit 130 that converts the current value into a voltage value. Further, the fault detection device 100 includes an averaging signal generation unit 160a that generates an averaging signal obtained by averaging the fluctuations of the voltage value, and a comparator Comp that detects an abnormality of the opening / closing unit by comparing the voltage value with the averaging signal.

[0065] With this configuration, the fault detection device 100 does not need to provide a circuit that performs special processing such as differential processing, and can detect a fault of the electromagnetic contactor with a simple configuration by comparing the detection signal of the current with the signal obtained by averaging the fluctuations.

[0066] The current detection unit 110 of the fault detection device 100 according to the second aspect may include a drive circuit 111 and an amplifier Amp whose first input terminal is connected to the coil. Further, the current detection unit 110 may include a current detection MOS controlled by the drive circuit 111, one end of which is connected to the coil and the first input terminal of the amplifier Amp. Further, the current detection unit 110 may have a sense MOS 113 controlled by the drive circuit 111, one end of which is connected to the second input terminal of the amplifier Amp. Note that the current detection MOS corresponds to a low-side MOS 112a or a high-side MOS 112b.

[0067] With this configuration, the fault detection device 100 can detect an accurate current value with a simple configuration, and can improve the accuracy of fault detection.

[0068] The current detection unit 110 of the fault detection device 100 according to the third aspect may include a drive circuit 111, an amplifier Amp, and a low-side MOS 112a whose drain terminal is connected to a coil. Further, the current detection unit 110 may include a first resistor R1 having one end connected to the source terminal of the low-side MOS 112a and the other end connected to the first input terminal of the amplifier Amp. Further, the current detection unit 110 may include a second resistor R2 having one end connected to the second input terminal of the amplifier Amp, and a third resistor R3 having one end connected to the source terminal of the low-side MOS 112a and the other end connected to the other end of the second resistor R2.

[0069] With this configuration, the fault detection device 100 can realize the current detection function with a simple configuration having a small circuit scale by configuring the current detection unit 110 without using the sense MOS 113.

[0070] The current detection unit 110 of the fault detection device 100 according to the fourth aspect may include a drive circuit 111, an amplifier Amp, and a high-side MOS 112b whose drain terminal is connected to a battery. Further, the current detection unit 110 may include a fourth resistor having one end connected to the source terminal of the high-side MOS 112b and the other end connected to the coil and the first input terminal of the amplifier Amp. Further, the current detection unit 110 may include a fifth resistor R5 having one end connected to the source terminal of the high-side MOS 112b and the other end connected to the second input terminal of the amplifier Amp.

[0071] With this configuration, the fault detection device 100 can realize the current detection function with a simple configuration having a small circuit scale by configuring the current detection unit 110 without using the sense MOS 113.

[0072] The averaging signal generation unit 160a of the fault detection device 100 according to the fifth aspect may include a diode D1 with its anode side connected to the voltage conversion unit 130, and a first voltage dividing resistor Rb1 connected in series to the cathode side of the diode D1. Further, the averaging signal generation unit 160a may include a second voltage dividing resistor Rb2 with one end connected in series to the first voltage dividing resistor Rb1 and the other end connected to the reference potential. Further, the averaging signal generation unit 160a may include a capacitor Cb connected in parallel to the second voltage dividing resistor Rb2. Furthermore, the averaging signal generated by the averaging signal generation unit 160a may be the voltage value of the capacitor Cb.

[0073] With this configuration, the fault detection device 100 can generate an averaging signal necessary for fault detection with a simple configuration.

[0074] The averaging signal generation unit of the fault detection device 100 according to the sixth aspect may generate an averaging signal with the output of the voltage conversion unit 130 as the peak value. That is, the averaging signal generation unit may be composed of a peak hold circuit 160b.

[0075] With this configuration, the fault detection device 100 can realize the function of detecting a fault in the contactor 200 with a simple configuration, for example, by using a general peak hold circuit 160b.

[0076] The semiconductor device 10 according to the seventh aspect includes an opening / closing unit that opens and closes an electric current path by the current flowing through a coil, and the above-described fault detection device 100.

[0077] With this configuration, the semiconductor device 10 does not need to provide a circuit for performing special processing such as differential processing, and can detect a fault in the electromagnetic contactor with a simple configuration by comparing the detection signal of the current with the signal obtained by averaging the fluctuations.

[0078] The opening / closing unit of the semiconductor device 10 according to the eighth aspect may be an electromagnetic contactor.

[0079] With this configuration, the semiconductor device 10 can detect an abnormality in the opening / closing unit that opens and closes the current path by the current flowing through the coil with a simple configuration.

Explanation of Signs

[0080] Amp Amplifier Ca, Cb Capacitor Comp Comparator FF Flip - Flop D1 Diode Na, Nb, Nc, Nd, Ns Node Ra1, Ra2 Resistor Rb1 First Voltage - Dividing Resistor Rb2 Second Voltage - Dividing Resistor Cb Capacitor 10 Semiconductor Device 100 Fault Detection Device 110 Current Detection Unit 111 Drive Circuit 112a Low - Side MOS 112b High - Side MOS 113 Sense MOS 115 Transistor Circuit 116 Current Mirror Circuit 130 Voltage Conversion Unit 150 Fault Detection Unit 160a Averaging Signal Generation Unit 160b Peak - Hold Circuit 200 Contact

Claims

1. A failure detection device for detecting an abnormality of an opening / closing unit that opens and closes a current path by a current flowing through a coil, comprising: a current detection unit that detects a current value flowing through the coil; a voltage conversion unit that converts the current value into a voltage value; an averaging signal generation unit that generates an averaging signal obtained by averaging fluctuations in the voltage value; a comparator that detects an abnormality of the opening / closing unit by comparing the voltage value with the averaging signal. The failure detection device according to claim 1.

2. The current detection unit includes: a drive circuit; an amplifier having a first input terminal connected to the coil; a current detection MOS having one end connected to the coil and the first input terminal of the amplifier and controlled by the drive circuit; a sense MOS having one end connected to a second input terminal of the amplifier and controlled by the drive circuit. The failure detection device according to claim 1.

3. The current detection unit includes: a drive circuit; an amplifier; a low-side MOS having a drain terminal connected to the coil; a first resistor having one end connected to a source terminal of the low-side MOS and the other end connected to a first input terminal of the amplifier; a second resistor having one end connected to a second input terminal of the amplifier; a third resistor having one end connected to the source terminal of the low-side MOS and the other end connected to the other end of the second resistor. The failure detection device according to claim 1.

4. The current detection unit includes: a drive circuit; an amplifier; a high-side MOS having a drain terminal connected to a battery; a fourth resistor having one end connected to a source terminal of the high-side MOS and the other end connected to the coil and a first input terminal of the amplifier; a fifth resistor having one end connected to the source terminal of the high-side MOS and the other end connected to a second input terminal of the amplifier. The failure detection device according to claim 1.

5. The averaging signal generation unit includes: a diode having an anode side connected to the voltage conversion unit; a first voltage dividing resistor connected in series with a cathode side of the diode; a second voltage dividing resistor having one end connected in series with the first voltage dividing resistor and the other end connected to a reference potential; a capacitor connected in parallel with the second voltage dividing resistor. The averaging signal is a voltage value of the capacitor. The failure detection device according to claim 1.

6. The averaging signal generation unit generates the averaging signal having the output of the voltage conversion unit as a peak value. The failure detection device according to claim 1.

7. ​ ​ ​ An opening / closing unit that opens and closes a current path by means of a current flowing through a coil, A failure detection device according to any one of claims 1 to 6, A semiconductor device comprising the same.

8. The semiconductor device according to claim 7, wherein the opening / closing unit is an electromagnetic contactor.

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