Abnormality detection device, load driving device, abnormality detection method and storage medium

Abstract

The present disclosure provides an abnormality detection device, a load driving device, an abnormality detection method and a storage medium for detecting an abnormality of a driving circuit by a simple structure. A microcomputer functions as a control unit and a judgment unit. In a driving circuit including a first relay provided between a heater and a power supply unit and a second relay provided between a heater and a ground line, the control unit controls the first relay to connect the heater and the power supply unit to an on state or to cut off the heater and the power supply unit, and controls the second relay to connect the heater and the ground line to an on state or to cut off the heater and the ground line. The judgment unit judges the abnormality of the driving circuit based on the on and off states of the first relay and the second relay, and the judgment voltage detected by the voltage sensor circuit that detects the judgment voltage between the first relay and the heater.

Description

Technical Field

[0001] The present disclosure relates to an abnormality detection device, a load driving device, an abnormality detection method, and a storage medium storing an abnormality detection program. Background Art

[0002] The control device described in Japanese Patent Application Publication No. 2020-137089 includes: a high-side wiring connecting a heater and a power supply, a low-side wiring connecting a heater and a ground, an induction wiring connected to a heating electrode of the heater, and a fault detection unit for detecting faults in each wiring connected to the heater. The fault detection unit determines the mode of the fault and the location of the fault based on the high-side voltage, the low-side voltage, the induction voltage, the high-side current, and the low-side current.

[0003] The technology described in Japanese Patent Publication No. 2020-137089 needs to obtain voltages and currents at multiple locations of the driving circuit when detecting an abnormality in the driving circuit. Specifically, it needs to obtain a high-side voltage, a low-side voltage, an induced voltage, a high-side current, and a low-side current. Therefore, in the technology described in Japanese Patent Publication No. 2020-137089, the structure for detecting an abnormality in the driving circuit becomes complicated. Summary of the invention

[0004] The present disclosure is an invention completed in consideration of the above-mentioned facts, and provides an abnormality detection device, a load driving device, an abnormality detection method, and a storage medium storing an abnormality detection program that can detect abnormalities in a driving circuit with a simple structure.

[0005] The abnormality detection device involved in the first method includes: a control unit, which controls a first switch provided between an electrical load and a power supply unit and a second switch provided between the electrical load and a ground line in a driving circuit, controls the first switch to connect the electrical load and the power supply unit to an on-state or to cut off the electrical load and the power supply unit, and controls the second switch to connect the electrical load and the ground line to an on-state or to cut off the electrical load and the ground line; and a judgment unit, which judges the abnormality of the driving circuit based on the on-off states of the first switch and the second switch controlled by the control unit and the voltage detected by the detection unit that detects the voltage between the first switch and the electrical load.

[0006] In the first mode, the first switch is controlled to be in an on state or an off state, and the second switch is controlled to be in an on state or an off state. Furthermore, the abnormality of the drive circuit is determined based on the on and off states of the first switch and the second switch and the voltage detected by a detection unit that detects the voltage between the first switch and the electrical load. In this way, in the first mode, since the abnormality of the drive circuit is determined based on the voltage between the first switch and the electrical load, it is not necessary to obtain the voltages and currents of multiple parts of the drive circuit, so that the abnormality of the drive circuit can be detected with a simple structure.

[0007] The second method is that in the first method, the control unit sequentially switches the first switch and the second switch to a plurality of states in which the on and off states of the first switch and the second switch are different from each other, and the judgment unit judges the abnormality of the drive circuit based on the on and off states of the first switch and the second switch in each of the plurality of states and the voltages respectively detected by the detection unit in the plurality of states.

[0008] In the second method, the first switch and the second switch are switched in sequence to a plurality of different on and off states, and the abnormality of the drive circuit is judged based on the on and off states of the first switch and the second switch in each of the plurality of states and the voltages respectively detected by the detection unit in the plurality of states, thereby enabling the abnormality of the drive circuit to be fully detected.

[0009] A third method is that, in the first method or the second method, the control unit controls the on-off state of the first switch and the second switch when the drive circuit is started, and the judgment unit judges the abnormality of the drive circuit based on the on-off state of the first switch and the second switch controlled by the control unit when the drive circuit is started and the voltage detected by the detection unit.

[0010] In the third method, since the on and off states of the first switch and the second switch are controlled when the drive circuit is started to determine the abnormality of the drive circuit, if it is determined that there is no abnormality in the abnormality determination of the drive circuit, the drive circuit can be provided to drive the electrical load at an early stage.

[0011] A fourth mode is that, in any one of the first mode to the third mode, the control unit sequentially switches the first switch and the second switch to a plurality of states in which the first switch and the second switch are different from each other in terms of on and off states, and the judgment unit judges the abnormality of the drive circuit by comparing the voltages respectively detected by the detection unit when the first switch and the second switch are in the plurality of states with threshold values ​​that are different according to the on and off states of the first switch and the second switch.

[0012] In the fourth aspect, the abnormality detection can be performed more accurately by comparing the voltages detected when the first switch and the second switch are in the plurality of states with threshold values ​​that differ depending on the on and off states of the first switch and the second switch.

[0013] The fifth mode is that, in any one of the first mode to the fourth mode, the control unit switches the on / off state of the first switch and the second switch to a first state in which both the first switch and the second switch are set to an off state, a second state in which the first switch is set to an off state and the second switch is set to an on state, and a third state in which both the first switch and the second switch are set to an on state.

[0014] In the fifth embodiment, since the on / off states of the first switch and the second switch are switched to the first state, the second state, and the third state, the abnormality of the drive circuit is determined based on the voltages detected in each of these states. Thus, the abnormality of the drive circuit can be detected completely and efficiently.

[0015] According to a sixth aspect, in the fifth aspect, the control unit further switches the on-off state of the first switch and the second switch to a fourth state in which the first switch is turned on and the second switch is turned off.

[0016] In the sixth aspect, since the on / off states of the first switch and the second switch are switched to the fourth state, the abnormality of the drive circuit is also determined using the voltage detected in the fourth state. Thus, the location where the abnormality occurred and the content of the abnormality can be pinpointed.

[0017] A seventh aspect is that in any one of the first to sixth aspects, the determination unit determines that the drive circuit is abnormal based on the voltage detected in a second state in which the first switch is in an OFF state and the second switch is in an ON state when a short circuit occurs to a power supply between the first switch and the electrical load, and determines that the drive circuit is abnormal based on the voltage detected in a first state in which both the first switch and the second switch are in an OFF state, or a third state in which both the first switch and the second switch are in an ON state, or a fourth state in which the first switch is in an ON state and the second switch is in an OFF state when a short circuit occurs to a ground between the first switch and the electrical load, and determines that the drive circuit is abnormal based on the voltage detected in the second state in which a wire break occurs between the first switch and the electrical load, and determines that the drive circuit is abnormal based on the voltage detected in the second state in which the first switch is stuck in the ON state, and determines that the drive circuit is abnormal based on the voltage detected in the third state in which the first switch is stuck in the OFF state.

[0018] According to the seventh method, abnormalities around the first switch, specifically, a short circuit to the power supply between the first switch and the electrical load, a short circuit to the ground between the first switch and the electrical load, a disconnection between the first switch and the electrical load, the first switch sticking in the on state, and the first switch sticking in the off state, can be detected as abnormalities of the drive circuit.

[0019] The eighth mode is that in any one of the first to seventh modes, the judgment unit judges that the drive circuit is abnormal based on the voltage detected in the second state in which the first switch is set to the off state and the second switch is set to the on state when a short circuit occurs to the power supply between the second switch and the electrical load, and judges that the drive circuit is abnormal based on the voltage detected in the first state in which both the first switch and the second switch are set to the off state when a short circuit occurs to the ground between the second switch and the electrical load, and judges that the drive circuit is abnormal based on the voltage detected in the second state in which a wire break occurs between the second switch and the electrical load, and judges that the drive circuit is abnormal based on the voltage detected in the first state in which the second switch is stuck in the on state, and judges that the drive circuit is abnormal based on the voltage detected in the second state in which the second switch is stuck in the off state.

[0020] According to the eighth method, abnormalities around the second switch, specifically, a short circuit to the power supply between the second switch and the electrical load, a short circuit to the ground between the second switch and the electrical load, a disconnection between the second switch and the electrical load, the second switch sticking in the on state, and the second switch sticking in the off state, can be detected as abnormalities of the drive circuit.

[0021] The ninth mode is that, in any one of the first mode to the eighth mode, the judgment unit judges whether the drive circuit is normal or abnormal multiple times based on the voltage detected by the detection unit when the on and off states of the first switch and the second switch are fixed, and when it is judged as abnormal continuously for a prescribed number of times, it is determined that there is an abnormality in the drive circuit.

[0022] Immediately after the on / off states of the first switch and the second switch are switched, the voltage detected by the detection unit becomes an unstable transient state. In this regard, since the ninth aspect performs multiple determinations of whether the drive circuit is normal or abnormal based on the detected voltage, and determines that there is an abnormality in the drive circuit when it is continuously determined to be abnormal for a predetermined number of times, it is possible to suppress the voltage change in the transient state from affecting the abnormality detection.

[0023] A tenth aspect is, in any one of the first to eighth aspects, wherein the electrical load is a heater.

[0024] The tenth aspect can realize detection of an abnormality in a drive circuit that drives a heater as an electrical load with a simple configuration.

[0025] A load driving device according to an eleventh aspect includes: the abnormality detection device according to any one of the first to tenth aspects, the driving circuit including the first switch and the second switch, and the detection unit.

[0026] In the eleventh aspect, since the abnormality detection device described in any one of the first to tenth aspects is included, it is possible to realize detection of abnormality of the drive circuit with a simple configuration similarly to the first aspect.

[0027] The abnormality detection method involved in the twelfth embodiment causes a computer to perform the following processing, namely: in a driving circuit including a first switch provided between an electrical load and a power supply unit and a second switch provided between the electrical load and a ground line, the first switch is controlled to be in an on state connecting the electrical load and the power supply unit or in an off state disconnecting the electrical load and the power supply unit, and the second switch is controlled to be in an on state connecting the electrical load and the ground line or in an off state disconnecting the electrical load and the ground line, and the abnormality of the driving circuit is judged based on the on and off states of the controlled first switch and the second switch and the voltage detected by a detection unit that detects the voltage between the first switch and the electrical load.

[0028] According to the twelfth aspect, similarly to the first aspect, it is possible to realize detection of abnormality in the drive circuit with a simple configuration.

[0029] The non-temporary storage medium involved in the thirteenth method stores a program that enables a computer to execute an abnormality detection process, and the abnormality detection process includes the following processing: in a driving circuit including a first switch arranged between an electrical load and a power supply unit and a second switch arranged between the electrical load and a ground line, the first switch is controlled to be in an on-state connecting the electrical load and the power supply unit or in an off-state cutting off the electrical load and the power supply unit, and the second switch is controlled to be in an on-state connecting the electrical load and the ground line or in an off-state cutting off the electrical load and the ground line, and the abnormality of the driving circuit is judged based on the on-off states of the controlled first switch and the second switch and the voltage detected by a detection unit that detects the voltage between the first switch and the electrical load.

[0030] According to the thirteenth aspect, similarly to the first aspect, it is possible to realize detection of abnormality in the drive circuit with a simple configuration.

[0031] The present disclosure can realize detection of abnormality in a drive circuit with a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram showing a battery pack and a heater drive ECU according to the embodiment.

[0033] Figure 2 This is a functional block diagram of a microcomputer.

[0034] Figure 3 This is a schematic diagram showing a situation where a "high side + B short" occurs in the drive circuit.

[0035] Figure 4 This is a schematic diagram showing a situation where a "high-side GND short" occurs in a drive circuit.

[0036] Figure 5 This is a schematic diagram showing a situation where a "high-side open" occurs in a drive circuit.

[0037] Figure 6 This is a schematic diagram showing a situation where "high-side on-stuck" occurs in a driving circuit.

[0038] Figure 7 This is a schematic diagram showing a situation where "high-side disconnection sticking" occurs in a drive circuit.

[0039] Figure 8 This is a schematic diagram showing a situation where a "low side + B short" occurs in the drive circuit.

[0040] Fig. 9 This is a schematic diagram showing a situation where a "low-side GND short" occurs in a drive circuit.

[0041] Fig.10 This is a schematic diagram showing a situation where a "low-side open" occurs in a drive circuit.

[0042] Fig.11 This is a schematic diagram showing a situation where "low-side on-stuck" occurs in a drive circuit.

[0043] Fig.12 This is a schematic diagram showing a situation where "low-side disconnection sticking" occurs in a drive circuit.

[0044] Fig.13 This is a graph showing whether various abnormalities can be detected in each state where both relays are off, the low-side relay is on, and both relays are on.

[0045] Fig.14 It is a flowchart which shows the abnormality detection process which concerns on 1st Embodiment.

[0046] Fig.15 1 is a flowchart showing the two-relay disconnection determination process according to the first embodiment.

[0047] Fig.16 1 is a flowchart showing the low-side relay on-time determination process according to the first embodiment.

[0048] Fig.17 1 is a flowchart showing the two-relay-on determination process according to the first embodiment.

[0049] Fig.18 This is a graph showing whether various abnormalities can be detected in each state where both relays are off, the high-side relay is on, the low-side relay is on, and both relays are on.

[0050] Fig.19 It is a flowchart which shows the abnormality detection process which concerns on 2nd Embodiment.

[0051] Fig. 20 1 is a flowchart showing the two-relay disconnection determination process according to the second embodiment.

[0052] Fig.21 1 is a flowchart showing the high-side relay on-time determination process according to the second embodiment.

[0053] Fig. 22 1 is a flowchart showing the low-side relay on-time determination process according to the second embodiment.

[0054] Fig.23 2 is a flowchart showing a two-relay-on determination process according to the second embodiment. DETAILED DESCRIPTION

[0055] Hereinafter, one example of an embodiment of the present disclosure is described in detail with reference to the drawings.

[0056] [First embodiment]

[0057] exist Figure 1 , a battery pack 10 and a heater drive ECU 22 that drives a heater 18 built into the battery pack 10 are shown. The battery pack 10 and the heater drive ECU 22 are mounted on a vehicle (not shown) and are connected via a high-side connection line 38 and a low-side connection line 40.

[0058] The battery pack 10 includes a battery 12, a temperature sensor circuit 14 for detecting the temperature of the battery 12, an IC (Integrated Circuit) 16 for transmitting the temperature of the battery 12 detected by the temperature sensor circuit 14 to the heater drive ECU 22, and a heater 18 for heating the battery 12 when powered on. The heater 18 is an example of an electrical load in the present disclosure. The battery 12 of the battery pack 10 functions as a backup power source for an auxiliary battery (not shown) mounted on a vehicle, for example.

[0059] In addition, the heater drive ECU 22 includes: a power supply unit 24, a first relay 26 provided between the heater 18 and the power supply unit 24, a second relay 28 provided between the heater 18 and the ground line, a voltage sensor circuit 30, and a microcomputer 46. In addition, the first relay 26 is an example of a first switch in the present disclosure, and is referred to as a "high-side relay 26" as needed. In addition, the second relay 28 is an example of a second switch in the present disclosure, and is referred to as a "low-side relay 28" as needed. In addition, the heater drive ECU 22 is an example of a load drive device in the present disclosure.

[0060] The first relay 26 includes an excitation coil 26A and a switch 26B that switches between an on / off state according to the excitation / non-excitation state of the excitation coil 26A. Both ends of the excitation coil 26A are connected to the microcomputer 46, one end of the switch 26B is connected to the positive terminal of the power supply unit 24, and the other end of the switch 26B is connected to one end of the heater 18 via the high-side connection line 38. The microcomputer 46 controls the first relay 26 to be in an on state that connects the heater 18 and the power supply unit 24, or in an off state that cuts off the heater 18 and the power supply unit 24 by switching the excitation / non-excitation state of the excitation coil 26A.

[0061] In addition, the second relay 28 includes an excitation coil 28A and a switch 28B that switches between an on and off state according to the excitation / non-excitation state of the excitation coil 28A. Both ends of the excitation coil 28A are connected to the microcomputer 46, one end of the switch 28B is connected to the other end of the heater 18 via the low-side connection line 40, and the other end of the switch 28B is connected to the ground line. The microcomputer 46 controls the second relay 28 to be in an on state that connects the heater 18 and the ground line, or in an off state that cuts off the heater 18 and the ground line by switching the excitation / non-excitation state of the excitation coil 28A.

[0062] The power supply unit 24 , the first relay 26 , the high-side connection line 38 , the second relay 28 , the low-side connection line 40 , and the ground line described above are an example of a drive circuit for the heater 18 , and are hereinafter collectively referred to as a “drive circuit 42 ” as needed.

[0063] In addition, the voltage sensor circuit 30 includes resistors 32, 34, and 36. One end of the resistor 32 is connected to the positive terminal of the power supply unit 24, and the other end is connected to the middle of the high-side connection line 38. One end of the resistor 34 is connected to the middle of the high-side connection line 38, and the other end is connected to one end of the resistor 36. The other end of the resistor 36 is connected to the ground line. In the voltage sensor circuit 30, the connection point between the resistor 34 and the resistor 36 is connected to the microcomputer 46. As a result, the voltage obtained by dividing the voltage of the high-side connection line through the resistors 34 and 36 is input to the microcomputer 46. In addition, the voltage sensor circuit 30 is an example of a detection unit, and the voltage input from the voltage sensor circuit 30 to the microcomputer 46 is an example of "the voltage between the first switch and the electrical load".

[0064] The microcomputer 46 includes a CPU 48, a memory 50 such as a ROM or RAM, a nonvolatile storage unit 52 such as a HDD or SSD, and a communication unit 54. The CPU 48, the memory 50, the storage unit 52, and the communication unit 54 are connected to each other via an internal bus 56 so as to be able to communicate with each other. The microcomputer 46 determines whether it is necessary to heat the battery 12 by the heater 18 based on the temperature of the battery 12 received from the IC of the battery pack 10. When the microcomputer 46 determines that it is necessary to heat the battery 12 by the heater 18, the first relay 26 and the second relay 28 are controlled to be in the on state, thereby energizing the heater 18.

[0065] In addition, the storage unit 52 stores an abnormality detection program 58. The microcomputer 46 reads the abnormality detection program 58 from the storage unit 52 and expands it in the memory 50. When the ignition switch of the vehicle is turned on and the drive circuit 42 is started, for example, the CPU 48 executes the abnormality detection program 58 expanded in the memory 50, thereby implementing the abnormality detection process described later. The microcomputer 46 implements the abnormality detection process, thereby serving as Figure 2 The microcomputer 46 is an example of an abnormality detection device in the present disclosure, and is an example of a computer in the present disclosure.

[0066] The control unit 62 controls the first relay 26 to connect the heater 18 and the power supply unit 24 to an on state or to cut off the heater 18 and the power supply unit 24 to an off state, and controls the second relay 28 to connect the heater 18 and the ground line to an on state or to cut off the heater 18 and the ground line to an off state.

[0067] The disconnection unit 64 determines an abnormality in the drive circuit 42 based on the on / off states of the first relay 26 and the second relay 28 controlled by the control unit 62, and the voltage detected by the voltage sensor circuit 30 that detects the voltage between the first relay 26 and the heater 18 (the high-side connecting line 38).

[0068] Next, the operation of the first embodiment will be described. In this embodiment, as abnormalities of the drive circuit 42, the following ten abnormalities are considered.

[0069] (1) An abnormality occurs when a short circuit occurs between the first relay 26 and the heater 18 to the power supply (see Figure 3 , hereinafter referred to as "high side + B short")

[0070] (2) An abnormality occurs in which a short circuit occurs between the first relay 26 and the heater 18 to the ground (see Figure 4 , hereinafter referred to as "high-side GND short")

[0071] (3) A disconnection occurs between the first relay 26 and the heater 18 (see Figure 5 , hereinafter referred to as "high side open")

[0072] (4) The first relay 26 is stuck in the on state (see Figure 6 , hereinafter referred to as "high-side on-stuck")

[0073] (5) The first relay 26 is stuck in the disconnected state (see Figure 7 , hereinafter referred to as "high side disconnect bonding")

[0074] (6) An abnormality occurs when a short circuit occurs between the second relay 28 and the heater 18 to the power supply (see Figure 8 , hereinafter referred to as "low side + B short connection")

[0075] (7) A short circuit occurs between the second relay 28 and the heater 18 to the ground (see Fig. 9 , hereinafter referred to as "low-side GND short")

[0076] (8) A disconnection occurs between the second relay 28 and the heater 18 (see Fig.10, hereinafter referred to as "low-side open")

[0077] (9) The second relay 28 is stuck in the on state (see Fig.11 , hereinafter referred to as "low-side conduction sticking")

[0078] (10) The second relay 28 is stuck in the disconnected state (see Fig.12 , hereinafter referred to as "low side disconnect sticking")

[0079] Here, the control unit 62 switches both the first relay (high-side relay) 26 and the second relay (low-side relay) 28 to the OFF state ( Fig.13 The "two relays are disconnected" shown in: an example of the first state in the present disclosure) is considered. In the "two relays are disconnected", when the drive circuit 42 is normal, as shown in Fig.13 As shown in FIG. 1 , the voltage (judgment voltage) of the high-side connection line 38 detected by the voltage sensor circuit 30 becomes the voltage V2. On the other hand, in the case where "high-side GND short circuit" or "low-side GND short circuit" or "low-side conduction sticking" occurs in the drive circuit 42 during "both relays are disconnected", as shown in FIG. Fig.13 As shown, the judgment voltage will become 0.

[0080] Therefore, in the "two relays are disconnected", the threshold voltage relative to the judgment voltage is set to a value less than voltages V1 and V2 and greater than 0, and the judgment unit 64 judges that an abnormality has occurred in the drive circuit 42 when the judgment voltage is less than the threshold voltage, thereby being able to detect the occurrence of "high side GND short circuit" or "low side GND short circuit" or "low side conduction adhesion" in the drive circuit 42.

[0081] In addition, Fig.13 In the figure, "○" means that the abnormality can be detected, and "×" means that the abnormality cannot be detected. In addition, "△" means that the abnormality can be detected if the change in the determination voltage is small.

[0082] Next, the control unit 62 switches the first relay (high-side relay) 26 to the OFF state and simultaneously switches the second relay (low-side relay) 28 to the ON state ( Fig.13 The "low side relay is on" shown in: an example of the second state in the present disclosure) is considered. Fig.13 As shown in FIG. 1 , in the “low-side relay on” state, when the drive circuit 42 is normal, the judgment voltage becomes 0. On the other hand, Fig.13As shown, in the "low side relay on", when "high side + B short circuit" or "high side conduction sticking" or "low side + B short circuit" occurs in the drive circuit 42, the judgment voltage will become V4. Fig.13 As shown in FIG. 1 , when “high side open circuit” or “low side open circuit” occurs in the drive circuit 42 during “low side relay on”, the judgment voltage becomes V2. In addition, when “low side disconnection adhesion” occurs in the drive circuit 42 during “low side relay on”, as shown in FIG. Fig.13 As shown, the judgment voltage will become V1.

[0083] Therefore, in the "low-side relay is turned on", the threshold voltage relative to the judgment voltage is set to a value lower than the voltages V1 and V2, and the judgment unit 64 judges that an abnormality has occurred in the drive circuit 42 when the judgment voltage is greater than the threshold voltage, thereby being able to detect the occurrence of "high side + B short circuit" or "high side conduction adhesion" or "high side open circuit" or "low side + B short circuit" or "low side open circuit" or "low side disconnection adhesion" in the drive circuit 42.

[0084] Next, the control unit 62 switches both the first relay (high-side relay) 26 and the second relay (low-side relay) 28 to the on state ( Fig.13 The "two relays are turned on" shown in: an example of the third state in the present disclosure) is considered. Fig.13 As shown, in the "both relays are turned on", when the drive circuit 42 is normal, the voltage (judgment voltage) of the high-side connection line 38 detected by the voltage sensor circuit 30 becomes the voltage V3. Fig.13 As shown, when "high side GND short circuit" or "high side disconnection sticking" occurs in the drive circuit 42 during "both relays are turned on", the determination voltage becomes zero.

[0085] Therefore, in the "two relays are turned on", the threshold voltage relative to the judgment voltage is set to a value less than voltages V3 and V4 and greater than 0, and the judgment unit 64 judges that an abnormality has occurred in the drive circuit 42 when the judgment voltage is less than the threshold voltage, thereby being able to detect the occurrence of "high-side GND short circuit" or "high-side disconnection and adhesion" in the drive circuit 42.

[0086] Therefore, by switching the first relay 26 and the second relay 28 to the respective states of "both relays disconnected", "low-side relay turned on", and "both relays turned on" by the control unit 62, and the judgment unit 64 comparing the judgment voltage with the threshold voltage corresponding to each state, the ten abnormalities of the drive circuit 42 can be fully detected.

[0087] Next, refer to Fig.14 The abnormality detection process involved in the first embodiment is described. In step 100, the control unit 62 determines whether all the judgments ("judgment when both relays are disconnected", "judgment when the low-side relay is on", and "judgment when both relays are on") have not been completed. If the judgment in step 100 is affirmative, the process proceeds to step 102.

[0088] In step 102, the control unit 62 switches the on / off state of the high-side relay 26 and the low-side relay 28 to judgment. That is, first, in order to implement the "judgment when both relays are off", both the high-side relay 26 and the low-side relay 28 are turned off. When the "judgment when both relays are off" is completed, next, in order to implement the "judgment when the low-side relay is on", the high-side relay 26 is turned off and the low-side relay 28 is turned on. When the "judgment when the low-side relay is on" is completed, next, in order to implement the "judgment when both relays are on", both the high-side relay 26 and the low-side relay 28 are turned on.

[0089] In step 104, the determination unit 64 increments the determination counter that was cleared at the start of the abnormality detection process. In step 106, the determination unit 64 determines whether the value of the determination counter is less than a predetermined value. If the determination in step 106 is affirmative, the process proceeds to step 108. In step 108, the determination unit 64 obtains a determination voltage (monitoring voltage) from the voltage sensor circuit 30.

[0090] In step 110, the determination unit 64 determines whether the judgment is not completed when the two relays are disconnected, and both the high-side relay 26 and the low-side relay 28 are disconnected. In addition, the judgment of whether the judgment is not completed when the two relays are disconnected is realized by judging whether a judgment flag when the two relays are disconnected (this flag is cleared when the abnormality detection process is started) described later is zero.

[0091] If the determination in step 110 is affirmative, the process proceeds to step 112, and in step 112, the determination unit 64 performs both relays disconnected determination processing and then proceeds to step 118. If the determination in step 110 is negative, step 112 is skipped and the process proceeds to step 118.

[0092] like Fig.15As shown, in step 150 of the judgment process when the two relays are disconnected, the judgment unit 64 judges whether the judgment voltage (monitoring voltage) obtained in the previous step 108 is within a prescribed range that can be judged as normal for the drive circuit 42. In addition, as the above-mentioned prescribed range in the judgment process when the two relays are disconnected, a range of a threshold voltage that is smaller than the voltages V1 and V2 and greater than 0 can be applied.

[0093] If the determination in step 150 is affirmative, the process proceeds to step 152. In step 152, the determination unit 64 clears the abnormal counter, increments the value of the normal counter, and proceeds to step 156. If the determination in step 150 is negative, the process proceeds to step 154. In step 154, the determination unit 64 increments the value of the abnormal counter, clears the normal counter, and proceeds to step 156.

[0094] In step 156, the determination unit 64 determines whether the value of the abnormality counter is greater than or equal to a predetermined value. If the determination in step 156 is affirmative, the process proceeds to step 158. In step 158, the determination unit 64 sets "ON" (a value indicating this meaning) in the abnormality flag when both relays are disconnected, sets "OFF" (a value indicating this meaning) in the normal flag when both relays are disconnected, and sets "PROCESSING COMPLETED" (a value indicating this meaning) in the determination flag when both relays are disconnected. In addition, if the determination in step 156 is negative, step 158 is skipped.

[0095] In addition, immediately after the on / off states of the first relay 26 and the second relay 28 are switched, the determination voltage becomes an unstable transition state. In view of this, in steps 150 to 158, the determination of whether the drive circuit 42 is normal or abnormal is performed multiple times based on the determination voltage, and when it is determined to be abnormal for a predetermined number of times, it is determined that there is an abnormality in the drive circuit 42. In this way, it is possible to suppress the situation where the change of the determination voltage in the transition state affects the abnormality detection.

[0096] Furthermore, in step 166, the determination unit 64 determines whether the value of the normal counter is greater than or equal to a predetermined value. If the determination in step 166 is affirmative, the process proceeds to step 168. In step 168, the determination unit 64 sets "off" in the abnormal flag when both relays are disconnected, sets "on" in the normal flag when both relays are disconnected, and sets "processing completed" in the determination flag when both relays are disconnected. In addition, if the determination in step 166 is negative, step 168 is skipped.

[0097] exist Fig.14In step 118, the determination unit 64 determines whether the low-side relay is turned on and the determination is not completed, the high-side relay 26 is turned off, and the low-side relay 28 is turned on. In addition, the determination of whether the low-side relay is turned on and the determination is not completed is achieved by determining whether the low-side relay is turned on determination flag (this flag is cleared when the abnormality detection process is started) described later is zero.

[0098] If the determination in step 118 is affirmative, the process proceeds to step 120, and in step 120, the determination unit 64 performs the low-side relay on-time determination process and then proceeds to step 122. If the determination in step 118 is negative, step 120 is skipped and the process proceeds to step 122.

[0099] Reference Fig.16 , the judgment processing when the low-side relay is turned on is different from the judgment processing when the two relays are disconnected ( Fig.15 ) are mainly described. In step 150 of the judgment process when the low-side relay is turned on, the judgment unit 64 judges whether the judgment voltage (monitoring voltage) is within a prescribed range that can be judged as normal for the drive circuit 42, similarly to the judgment process when the two relays are disconnected. However, as the above-mentioned prescribed range in the judgment process when the low-side relay is turned on, a range below the threshold voltage of the voltages V1 and V2 can be applied.

[0100] In addition, in the low-side relay on-time judgment process, if the judgment in step 156 is affirmative, the process proceeds to step 162. In step 162, the judgment unit 64 sets "on" in the low-side relay on-time abnormal flag, sets "off" in the low-side relay on-time normal flag, and sets "processing completed" in the low-side relay on-time judgment flag.

[0101] In addition, in the low-side relay on-time judgment process, if the judgment in step 166 is affirmative, the process proceeds to step 172. In step 172, the judgment unit 64 sets "off" in the low-side relay on-time abnormal flag, sets "on" in the low-side relay on-time normal flag, and sets "processing completed" in the low-side relay on-time judgment flag.

[0102] exist Fig.14 In step 122, the determination unit 64 determines whether the judgment is not completed when the two relays are turned on, and both the high-side relay 26 and the low-side relay 28 are turned on. In addition, the judgment of whether the judgment is not completed when the two relays are turned on is realized by judging whether the judgment flag when the two relays are turned on (this flag is cleared when the abnormality detection process is started) described later is zero.

[0103] If the determination in step 122 is affirmative, the process proceeds to step 124, and in step 124, the determination unit 64 performs both relays on determination processing and then returns to step 100. If the determination in step 122 is negative, step 124 is skipped and the process returns to step 100.

[0104] Reference Fig.17 , the judgment process when the two relays are turned on is different from the judgment process when the two relays are turned off ( Fig.15 ) are mainly described. In step 150 of the judgment process when the two relays are turned on, the judgment unit 64 judges whether the judgment voltage (monitoring voltage) is within a prescribed range that can be judged as normal for the drive circuit 42, similarly to the judgment process when the two relays are turned off. However, as the above-mentioned prescribed range in the judgment process when the two relays are turned on, a range of a threshold voltage that is smaller than the voltages V3 and V4 and greater than 0 can be applied.

[0105] In the judgment process when both relays are conducting, if the judgment in step 156 is affirmative, the process proceeds to step 164. In step 164, the judgment unit 64 sets "ON" in the abnormal flag when both relays are conducting, sets "OFF" in the normal flag when both relays are conducting, and sets "processing completed" in the judgment flag when both relays are conducting.

[0106] In the judgment process when both relays are conducting, if the judgment in step 166 is affirmative, the process proceeds to step 174. In step 174, the judgment unit 64 sets "off" in the abnormal flag when both relays are conducting, sets "on" in the normal flag when both relays are conducting, and sets "processing completed" in the judgment flag when both relays are conducting.

[0107] exist Fig.14 In the case where all the judgments ("judgment when both relays are disconnected", "judgment when the low-side relay is on", and "judgment when both relays are on") are completed, the judgment of step 100 is denied and the process moves to step 126. In addition, when the value of the counter becomes greater than a predetermined value before all the judgments are completed, the judgment of step 106 is denied and the process moves to step 126. In step 126, the control unit 62 disconnects both the high-side relay 26 and the low-side relay 28, and ends the abnormality detection process.

[0108] In addition, as a case where the judgment of step 106 is denied, for example, a case where the judgment voltage repeatedly becomes normal and abnormal, indicating an abnormality that does not belong to any of the ten abnormalities of the drive circuit 42 described above and cannot judge the operating state of the heater 18 can be listed. The predetermined value in the judgment of step 106 can be set to a time (for example, 8 seconds) that is longer than the time when each of the judgments of "judgment when both relays are disconnected", "judgment when the low-side relay is turned on", and "judgment when both relays are turned on" is completed, and shorter than the time (for example, 10 seconds) from the start of the drive circuit 42 to start the use of the heater 18.

[0109] In the abnormality detection process involved in the first embodiment described above, when an abnormality occurs in the "judgment when both relays are disconnected", the abnormality flag when both relays are disconnected becomes "ON", when an abnormality occurs in the "judgment when the low-side relay is turned on", the abnormality flag when the low-side relay is turned on becomes "ON", and when an abnormality occurs in the "judgment when both relays are turned on", the abnormality flag when both relays are turned on becomes "ON". Therefore, by judging the drive circuit 42 as abnormal when at least one of the abnormality flag when both relays are disconnected, the abnormality flag when the low-side relay is turned on, and the abnormality flag when both relays are turned on is "ON", it is possible to fully detect ten types of abnormalities of the drive circuit 42.

[0110] On the other hand, when the abnormal mark when the two relays are disconnected, the abnormal mark when the low-side relay is turned on, and the abnormal mark when the two relays are turned on are all "off", and the judgment mark when the two relays are disconnected, the judgment mark when the low-side relay is turned on, and the judgment mark when the two relays are turned on are all "processed", the drive circuit 42 can be judged as normal.

[0111] Thus, in the first embodiment, the control unit 62 controls the first relay 26 to connect the heater 18 and the power supply unit 24 or to disconnect the heater 18 and the power supply unit 24 in the drive circuit 42 including the first relay 26 provided between the heater 18 and the power supply unit 24 and the second relay 28 provided between the heater 18 and the ground line, and controls the second relay 28 to connect the heater 18 and the ground line or to disconnect the heater 18 and the ground line. In addition, the judgment unit 64 judges the abnormality of the drive circuit 42 based on the on / off state of the first relay 26 and the second relay 28 controlled by the control unit 62 and the judgment voltage detected by the voltage sensor circuit 30 that detects the judgment voltage between the first relay 26 and the heater 18. As a result, when judging the abnormality of the drive circuit 42, it is not necessary to obtain the voltage and current of multiple parts of the drive circuit 42, so that the abnormality of the drive circuit can be detected by a simple structure.

[0112] In addition, in the first embodiment, the control unit 62 sequentially switches the first relay 26 and the second relay 28 to a plurality of states in which the on / off states of the first relay 26 and the second relay 28 are different from each other. In addition, the determination unit 64 determines the abnormality of the drive circuit 42 based on the on / off states of the first relay 26 and the second relay 28 in each of the plurality of states and the determination voltages respectively detected by the voltage sensor circuit 30 in the plurality of states. Thus, the abnormality of the drive circuit 42 can be fully detected.

[0113] Furthermore, in the first embodiment, the control unit 62 controls the on / off state of the first relay 26 and the second relay 28 at the start of the drive circuit 42, and the determination unit 64 determines the abnormality of the drive circuit 42 based on the on / off state of the first relay 26 and the second relay 28 controlled by the control unit 62 at the start of the drive circuit 42 and the determination voltage detected by the voltage sensor circuit 30. Thus, when it is determined that there is no abnormality in the abnormality determination of the drive circuit 42, the drive circuit 42 can be provided to the drive of the heater 18 at an early stage.

[0114] In addition, in the first embodiment, the control unit 62 sequentially switches the first relay 26 and the second relay 28 to a plurality of states in which the on / off states of the first relay 26 and the second relay 28 are different from each other. In addition, the determination unit 64 determines the abnormality of the drive circuit 42 by comparing the determination voltages respectively detected by the voltage sensor circuit 30 in the plurality of states of the first relay 26 and the second relay 28 with threshold values ​​that differ according to the on / off states of the first relay 26 and the second relay 28. Thus, the abnormality detection can be performed with higher accuracy.

[0115] In addition, in the first embodiment, the control unit 62 switches the on / off state of the first relay 26 and the second relay 28 to a first state (both relays are off) in which both the first relay 26 and the second relay 28 are set to an off state, a second state (low-side relay is on) in which the first relay 26 is set to an off state and the second relay 28 is set to an on state, and a third state (both relays are on) in which both the first relay 26 and the second relay 28 are set to an on state. Thus, an abnormality of the drive circuit 42 can be detected completely and efficiently.

[0116] In addition, in the first embodiment, the judgment unit 64 judges the drive circuit 42 as abnormal based on the judgment voltage detected in the second state (low-side relay is turned on) when "high-side +B short circuit" occurs, and judges the drive circuit 42 as abnormal based on the judgment voltage detected in the first state (both relays are turned off) or the third state (both relays are turned on) when "high-side GND short circuit" occurs, and judges the drive circuit 42 as abnormal based on the judgment voltage detected in the second state when "high-side open circuit" occurs, and judges the drive circuit 42 as abnormal based on the judgment voltage detected in the second state when "high-side conduction adhesion" occurs, and judges the drive circuit 42 as abnormal based on the judgment voltage detected in the third state when "high-side disconnection adhesion" occurs. Thus, the abnormality around the first relay 26 can be detected as an abnormality of the drive circuit 42.

[0117] In addition, in the first embodiment, the judgment unit 64 judges the drive circuit 42 as abnormal based on the judgment voltage detected in the second state (low-side relay conduction) when "low-side +B short circuit" occurs, and judges the drive circuit 42 as abnormal based on the judgment voltage detected in the first state (both relays are disconnected) when "low-side GND short circuit" occurs, and judges the drive circuit 42 as abnormal based on the judgment voltage detected in the second state when "low-side open circuit" occurs, and judges the drive circuit 42 as abnormal based on the judgment voltage detected in the first state when "low-side conduction adhesion" occurs, and judges the drive circuit 42 as abnormal based on the judgment voltage detected in the second state when "low-side disconnection adhesion" occurs. Thus, the abnormality around the second relay 28 can be detected as an abnormality of the drive circuit 42.

[0118] Furthermore, in the first embodiment, when the on / off state of the first relay 26 and the second relay 28 is fixed, the determination unit 64 repeatedly performs the determination of whether the drive circuit 42 is normal or abnormal based on the determination voltage detected by the voltage sensor circuit 30, and determines that there is an abnormality in the drive circuit 42 when it is determined to be abnormal continuously for a predetermined number of times. Thus, it is possible to suppress the situation in which the change of the determination voltage in the transition state immediately after the on / off state of the first relay 26 and the second relay 28 is switched affects the abnormality detection.

[0119] [Second embodiment]

[0120] Next, the second embodiment of the present disclosure is described. In addition, since the second embodiment has the same structure as the first embodiment, the same symbols are added to each part and the description of the structure is omitted. In the following, the function of the second embodiment is described for the parts that are different from the first embodiment.

[0121] In the first embodiment, the control unit 62 switches the first relay 26 and the second relay 28 to the three states of "both relays are off", "low-side relay is on", and "both relays are on". In the second embodiment, in addition to the above three states, the control unit 62 switches the first relay 26 and the second relay 28 to "high-side relay is on" (refer to Fig.18 : An example of the fourth state in the present disclosure) is switched.

[0122] When the control unit 62 switches the first relay 26 and the second relay 28 to "high-side relay on", if the drive circuit 42 is normal, Fig.18 As shown in FIG. 1 , the judgment voltage becomes V4. On the other hand, when “high-side relay is turned on”, if “high-side GND short circuit” occurs in the drive circuit 42, as shown in FIG. Fig.18 As shown, the judgment voltage will become 0. Therefore, in the "high-side relay is turned on", the threshold voltage relative to the judgment voltage is set to a value smaller than the voltages V3 and V4, and the judgment unit 64 judges that an abnormality has occurred in the drive circuit 42 when the judgment voltage is below the threshold voltage, thereby being able to detect the occurrence of "high-side + GND short circuit" in the drive circuit 42.

[0123] Next, refer to Fig.19 The abnormality detection process involved in the second embodiment is described. In the abnormality detection process involved in the second embodiment, in step 102, the first relay 26 and the second relay 28 are switched to the four states of "both relays are disconnected", "high-side relay is turned on", "low-side relay is turned on" and "both relays are turned on" in sequence. In addition, in the abnormality detection process involved in the second embodiment, the process of incrementing the counter in judgment and comparing it with the specified value (steps 104 and 106) is omitted, and in the abnormality detection process involved in the second embodiment, the judgment process when the two relays are disconnected is implemented in step 112, or the process is transferred to step 114 when the judgment in step 110 is denied.

[0124] In step 114, the determination unit 64 determines whether the high-side relay is turned on and the determination is not completed, and the high-side relay 26 is turned on and the low-side relay 28 is turned off. In addition, the determination of whether the high-side relay is turned on and the determination is not completed is achieved by determining whether the high-side relay is turned on determination flag (this flag is cleared when the abnormality detection process is started) described later is zero.

[0125] If the determination in step 114 is affirmative, the process proceeds to step 116, and in step 116, the determination unit 64 performs the high-side relay on-time determination process and then proceeds to step 118. If the determination in step 114 is negative, step 116 is skipped and the process proceeds to step 118.

[0126] Next, refer to Fig. 20 Regarding the judgment process when both relays are disconnected according to the second embodiment, only the process described in the first embodiment ( Fig.15) are described. In the judgment process when the two relays are disconnected involved in the second embodiment, in step 130, the judgment unit 64 increments the judgment counter 1 used for judging when the two relays are disconnected. In step 132, the judgment unit 64 judges whether the judgment counter 1 is less than a specified value. In addition, as the specified value, for example, it can be set to a time longer than the time it takes to judge that the process is completed when the two relays are disconnected under normal circumstances. If the judgment in step 132 is affirmative, the process proceeds to step 150. The processing after step 150 is the same as that of the first embodiment ( Fig.15 )same.

[0127] In addition, when the counter 1 is judged to be greater than the prescribed value, the judgment of step 132 is denied and the process is transferred to step 146. In step 146, the judgment unit 64 sets "on" in the abnormal flag when the two relays are disconnected, sets "off" in the normal flag when the two relays are disconnected, sets "processing completed" in the judgment flag when the two relays are disconnected, and ends the judgment process when the two relays are disconnected. Thus, after the abnormal detection process is completed, when the abnormal flag when the two relays are disconnected is "on", it is possible to judge whether an abnormality such as the judgment voltage repeatedly becoming normal and abnormal has not occurred during the execution of the judgment process when the two relays are disconnected based on whether the counter 1 is judged to be greater than the prescribed value.

[0128] Next, refer to Fig.21 , the high-side relay on-time judgment process involved in the second embodiment is described. In step 134 of the high-side relay on-time judgment process, the judgment unit 64 increments the judgment counter 2 for judging when the high-side relay is on. In step 136, the judgment unit 64 judges whether the judgment counter 2 is less than a specified value. In addition, as the specified value, for example, it can be set to a time longer than the time when the judgment process is completed when the high-side relay is on in normal conditions. If the judgment in step 136 is affirmative, the process proceeds to step 150.

[0129] The processing after step 150 is the same as the processing when the two relays are disconnected ( Fig. 20 ) are mainly described. In step 150 of the high-side relay on-time judgment process, the judgment unit 64 judges whether the judgment voltage is within a prescribed range that can be judged as normal for the drive circuit 42, similarly to the judgment process when both relays are disconnected. However, as the above-mentioned prescribed range in the high-side relay on-time judgment process, a range below the threshold voltage of the voltages V3 and V4 can be applied.

[0130] In the high-side relay on-time judgment process, if the judgment in step 156 is affirmative, the process proceeds to step 160. In step 160, the judgment unit 64 sets "ON" in the high-side relay on-time abnormal flag, sets "OFF" in the high-side relay on-time normal flag, and sets "processing completed" in the high-side relay on-time judgment flag.

[0131] In the high-side relay on-time judgment process, if the judgment in step 166 is affirmative, the process proceeds to step 170. In step 170, the judgment unit 64 sets "off" in the high-side relay on-time abnormal flag, sets "on" in the high-side relay on-time normal flag, and sets "processing completed" in the high-side relay on-time judgment flag.

[0132] In addition, when the counter 2 is judged to be greater than the prescribed value, the judgment of step 136 is denied and the process is transferred to step 146. In step 146, the judgment unit 64 sets "ON" in the abnormal flag when the high-side relay is turned on, sets "OFF" in the normal flag when the high-side relay is turned on, sets "processing completed" in the judgment flag when the high-side relay is turned on, and ends the judgment process when the high-side relay is turned on. Thus, after the abnormal detection process is completed, when the abnormal flag when the high-side relay is turned on is "ON", it is possible to judge whether an abnormality such as the judgment voltage repeatedly becoming normal and abnormal has not occurred during the execution of the judgment process when the high-side relay is turned on, based on whether the counter 2 is judged to be greater than the prescribed value.

[0133] Next, refer to Fig. 22 Regarding the low-side relay on-time determination process according to the second embodiment, only the process described in the first embodiment ( Fig.16 ) are described. In the judgment process when the low-side relay is turned on involved in the second embodiment, in step 138, the judgment unit 64 increments the judgment counter 3 used for judging when the low-side relay is turned on. In step 140, the judgment unit 64 judges whether the judgment counter 3 is less than a specified value. In addition, as the specified value, for example, it can be set to a time longer than the time it takes to judge that the process is completed when the low-side relay is turned on under normal circumstances. If the judgment in step 140 is affirmative, transfer to step 150. The processing after step 150 is the same as that of the first embodiment ( Fig.16 )same.

[0134] In addition, when the counter 3 is judged to be greater than the prescribed value, the judgment of step 140 is denied and the process is transferred to step 146. In step 146, the judgment unit 64 sets "on" in the abnormal flag when the low-side relay is turned on, sets "off" in the normal flag when the low-side relay is turned on, sets "processing completed" in the judgment flag when the low-side relay is turned on, and ends the judgment process when the low-side relay is turned on. Thus, after the abnormal detection process is completed, when the abnormal flag when the low-side relay is turned on is "on", it is possible to judge whether an abnormality such as the judgment voltage repeatedly becoming normal and abnormal has not occurred in the execution of the judgment process when the low-side relay is turned on, based on whether the counter 3 is judged to be greater than the prescribed value.

[0135] Next, refer to Fig.23 Regarding the judgment process when both relays are turned on in the second embodiment, only the process described in the first embodiment ( Fig.17 ) are described. In the judgment process when the two relays are conducting according to the second embodiment, in step 142, the judgment unit 64 increments the judgment counter 4 used for judging when the two relays are conducting. In step 144, the judgment unit 64 judges whether the judgment counter 4 is less than a specified value. In addition, as the specified value, for example, it can be set to a time longer than the time it takes to judge that the process is completed when the two relays are conducting under normal circumstances. If the judgment in step 144 is affirmative, the process proceeds to step 150. The processing after step 150 is the same as that of the first embodiment ( Fig.17 )same.

[0136] In addition, when the counter 4 is judged to be greater than the prescribed value, the judgment of step 144 is denied and the process is transferred to step 146. In step 146, the judgment unit 64 sets "on" in the abnormal flag when both relays are on, sets "off" in the normal flag when both relays are on, sets "processing completed" in the judgment flag when both relays are on, and ends the judgment process when both relays are on. Thus, after the abnormal detection process is completed, when the abnormal flag when both relays are on is "on", it is possible to judge whether an abnormality such as the judgment voltage repeatedly becoming normal and abnormal has not occurred during the execution of the judgment process when both relays are on, based on whether the counter 4 is judged to be greater than the prescribed value.

[0137] In the second embodiment, the drive circuit 42 is determined to be abnormal when at least one of the abnormal flag when both relays are disconnected, the abnormal flag when the high-side relay is turned on, the abnormal flag when the low-side relay is turned on, and the abnormal flag when both relays are turned on is "on", thereby being able to fully detect ten types of abnormalities of the drive circuit 42. In addition, since the abnormality of the drive circuit 42 can be determined as "high-side GND short circuit" when only the abnormal flag when the high-side relay is turned on among the above four flags is "on", it is possible to pinpoint the location where the abnormality has occurred and the content of the abnormality compared to the first embodiment.

[0138] On the other hand, when the abnormal mark when the two relays are disconnected, the abnormal mark when the high-side relay is turned on, the abnormal mark when the low-side relay is turned on, and the abnormal mark when the two relays are turned on are all "off", and the judgment mark when the two relays are disconnected, the judgment mark when the high-side relay is turned on, the judgment mark when the low-side relay is turned on, and the judgment mark when the two relays are turned on are all "processed", the drive circuit 42 can be judged as normal.

[0139] Thus, in the second embodiment, the control unit 62 also switches the on / off state of the first relay 26 and the second relay 28 to a fourth state (high-side relay on) in which the first relay 26 is turned on and the second relay 28 is turned off. Thus, the abnormal part and the content of the abnormality can be locked.

[0140] In addition, in the first embodiment, the first relay 26 and the second relay 28 are sequentially switched to the three states of "both relays are disconnected", "low-side relay is turned on", and "both relays are turned on", and the method of sequentially implementing the judgment processing corresponding to each state is described. In addition, in the second embodiment, the first relay 26 and the second relay 28 are sequentially switched to the four states of "both relays are disconnected", "high-side relay is turned on", "low-side relay is turned on", and "both relays are turned on", and the method of sequentially implementing the judgment processing corresponding to each state is described. However, in the present disclosure, the order of state switching of the first relay 26 and the second relay 28 is not limited to the above order, but can be appropriately changed.

[0141] In addition, although the above describes a method in which the first relay 26 is applied as an example of the first switch involved in the present disclosure, and the second relay 28 is applied as an example of the second switch, the present disclosure is not limited to this, and the first switch and the second switch may also be other structures such as semiconductor switching elements.

[0142] Furthermore, although the heater 18 built into the battery pack 10 is described above as an example of the electric load in the present disclosure, the present disclosure is not limited thereto, and for example, the heater may be built into a gas sensor or the like.

[0143] In addition, although the above description is given of the abnormality detection program 58 as an example of the abnormality detection program involved in the present disclosure being pre-stored (installed) in the storage unit 52, the present disclosure is not limited thereto. The abnormality detection program involved in the present disclosure can also be provided in a manner recorded in a non-temporary recording medium such as an HDD, an SSD, or a DVD.

Claims

1. An abnormality detection device for detecting an abnormality of a drive circuit, wherein the drive circuit comprises a first switch provided between an electrical load and a power supply unit, a second switch provided between the electrical load and a ground line, and a detection unit for detecting a voltage between the first switch and the electrical load, wherein: The abnormality detection device comprises: Memory; a processor combined with said memory, The processor is configured to: The first switch is controlled to connect the electrical load and the power supply unit to a conducting state or to cut off the electrical load and the power supply unit, and the second switch is controlled to connect the electrical load and the ground line to a conducting state or to cut off the electrical load and the ground line to a cutting state, and Based on the on / off states of the first switch and the second switch and the voltage detected by the detection unit, an abnormality of the drive circuit is determined, and When the on and off states of the first switch and the second switch are fixed, a judgment of whether the drive circuit is normal or abnormal is performed multiple times based on the voltage detected by the detection unit, and when it is judged to be abnormal continuously for a specified number of times, it is determined that an abnormality exists in the drive circuit, and when it is judged to be normal continuously for a specified number of times, it is determined that the drive circuit is normal, and when it cannot be judged to be abnormal continuously for a specified number of times and cannot be judged to be normal continuously for a specified number of times even if the judgment is performed multiple times, it is determined that an abnormality has occurred in which the voltage repeatedly becomes normal and abnormal.

2. The abnormality detection device according to claim 1, wherein: The processor is configured to: The first switch and the second switch are sequentially switched to a plurality of states in which the on and off states of the first switch and the second switch are different from each other, An abnormality in the drive circuit is determined based on the on / off states of the first switch and the second switch in each of the plurality of states and the voltages detected by the detection unit in the plurality of states.

3. The abnormality detection device according to claim 1 or claim 2, wherein: The processor is configured to: When the driving circuit is started, the on and off states of the first switch and the second switch are controlled, An abnormality in the drive circuit is determined based on the on / off states of the first switch and the second switch at the time of activation of the drive circuit and the voltage detected by the detection unit.

4. The abnormality detection device according to claim 1 or claim 2, wherein: The processor is configured to: The first switch and the second switch are sequentially switched to a plurality of states in which the on and off states of the first switch and the second switch are different from each other, The abnormality of the drive circuit is determined by comparing the voltages respectively detected by the detection unit when the first switch and the second switch are in the plurality of states with threshold values ​​that differ according to the on / off states of the first switch and the second switch.

5. The abnormality detection device according to claim 1 or claim 2, wherein: The processor is configured to: The on / off states of the first switch and the second switch are switched to a first state in which both the first switch and the second switch are in an off state, a second state in which the first switch is in an off state and the second switch is in an on state, and a third state in which both the first switch and the second switch are in an on state.

6. The abnormality detection device according to claim 5, wherein: The processor is configured to: The on / off state of the first switch and the second switch is switched to a fourth state in which the first switch is in the on state and the second switch is in the off state.

7. The abnormality detection device according to claim 1 or claim 2, wherein: The processor is configured to: When a short circuit occurs to a power supply between the first switch and the electrical load, the drive circuit is determined to be abnormal based on the voltage detected in a second state in which the first switch is turned off and the second switch is turned on, In a case where a short circuit occurs to the ground between the first switch and the electrical load, the drive circuit is determined to be abnormal based on the voltage detected in a first state where both the first switch and the second switch are in an off state, a third state where both the first switch and the second switch are in an on state, or a fourth state where the first switch is in an on state and the second switch is in an off state, When a disconnection occurs between the first switch and the electrical load, the drive circuit is determined to be abnormal based on the voltage detected in the second state; When the first switch is stuck in the on state, the drive circuit is determined to be abnormal based on the voltage detected in the second state, When the first switch is stuck in the off state, the drive circuit is determined to be abnormal based on the voltage detected in the third state.

8. The abnormality detection device according to claim 1 or claim 2, wherein: The processor is configured to: When a short circuit occurs to a power supply between the second switch and the electrical load, the drive circuit is determined to be abnormal based on the voltage detected in a second state in which the first switch is turned off and the second switch is turned on. When a short circuit occurs to the ground between the second switch and the electrical load, the drive circuit is determined to be abnormal based on the voltage detected in a first state in which both the first switch and the second switch are turned off. When a disconnection occurs between the second switch and the electrical load, the drive circuit is determined to be abnormal based on the voltage detected in the second state. When the second switch is stuck in the on state, the drive circuit is determined to be abnormal based on the voltage detected in the first state, When the second switch is stuck in the OFF state, the drive circuit is determined to be abnormal based on the voltage detected in the second state.

9. The abnormality detection device according to claim 1 or claim 2, wherein: The electrical load is a heater.

10. A load driving device, comprising: The abnormality detection device according to any one of claims 1 to 9; The driving circuit comprises the first switch and the second switch; The detection unit.

11. An abnormality detection method, which is a method for detecting an abnormality of a drive circuit, the drive circuit comprising a first switch provided between an electrical load and a power supply unit, a second switch provided between the electrical load and a ground line, and a detection unit for detecting a voltage between the first switch and the electrical load, wherein: The anomaly detection method comprises: The first switch is controlled to connect the electrical load and the power supply unit to a conducting state or to cut off the electrical load and the power supply unit, and the second switch is controlled to connect the electrical load and the ground line to a conducting state or to cut off the electrical load and the ground line to a cutting state, Based on the on / off states of the controlled first switch and the second switch and the voltage detected by the detection unit, an abnormality of the drive circuit is determined, and When the on and off states of the first switch and the second switch are fixed, a judgment of whether the drive circuit is normal or abnormal is performed multiple times based on the voltage detected by the detection unit, and when it is judged to be abnormal continuously for a specified number of times, it is determined that an abnormality exists in the drive circuit, and when it is judged to be normal continuously for a specified number of times, it is determined that the drive circuit is normal, and when it cannot be judged to be abnormal continuously for a specified number of times and cannot be judged to be normal continuously for a specified number of times even if the judgment is performed multiple times, it is determined that an abnormality has occurred in which the voltage repeatedly becomes normal and abnormal.

12. A storage medium, which is a non-transitory storage medium storing a program that causes a computer to execute an abnormality detection process for detecting an abnormality of a drive circuit, wherein the drive circuit includes a first switch provided between an electrical load and a power supply unit, a second switch provided between the electrical load and a ground line, and a detection unit for detecting a voltage between the first switch and the electrical load, wherein: The abnormality detection process includes the following processes, namely: The first switch is controlled to connect the electrical load and the power supply unit to a conducting state or to cut off the electrical load and the power supply unit, and the second switch is controlled to connect the electrical load and the ground line to a conducting state or to cut off the electrical load and the ground line to a cutting state, Based on the on / off states of the controlled first switch and the second switch and the voltage detected by the detection unit, an abnormality of the drive circuit is determined, and When the on and off states of the first switch and the second switch are fixed, a judgment of whether the drive circuit is normal or abnormal is performed multiple times based on the voltage detected by the detection unit, and when it is judged to be abnormal continuously for a specified number of times, it is determined that an abnormality exists in the drive circuit, and when it is judged to be normal continuously for a specified number of times, it is determined that the drive circuit is normal, and when it cannot be judged to be abnormal continuously for a specified number of times and cannot be judged to be normal continuously for a specified number of times even if the judgment is performed multiple times, it is determined that an abnormality has occurred in which the voltage repeatedly becomes normal and abnormal.

Images