JP5812514B2 - Electric system - Google Patents

Description

  The present invention relates to an electric system including a converter that boosts power from a power supply source.

  For example, as a fuel cell system, a failure detection unit that detects a failure of a current sensor of a DC / DC converter connected between a power storage device and a fuel cell based on a deviation between primary power and secondary power, and failure detection There is known a failure detection area setting section that causes a section to function except an area where the converter passing power efficiency of a DC / DC converter is significantly reduced (see, for example, Patent Document 1).

JP 2010-124589 A

  By the way, in an electric system such as a fuel cell system, abnormality determination of a converter is performed by diagnosis (self-diagnosis function). However, if the self-diagnosis is performed in a state where the converter components and the elements on the board do not operate normally, the abnormality determination may not be performed accurately.

  In the system of Patent Document 1 described above, it is described that the failure detection unit is allowed to function except in a region where the converter passing power efficiency is remarkably reduced. In this way, except for a region where the converter passing power efficiency is remarkably reduced. The function of the fault detection unit is not sufficient as a condition for avoiding false detection of abnormality determination by prohibiting self-diagnosis in a state where the converter components and the elements on the board do not operate normally.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an electric system capable of performing a self-diagnosis and performing an accurate abnormality determination only in an appropriate state.

In order to achieve the above object, an electric system of the present invention includes a power supply source and a boost converter that boosts power from the power supply source.
An electric system that detects various states of the boost converter and performs self-diagnosis of the boost converter according to the detection result,
The self-diagnosis of the boost converter is prohibited when the reliability reduction condition in which the reliability of the detection results of the various states of the boost converter is reduced.

  According to this configuration, since the self-diagnosis is prohibited when the reliability of the detection results of various states for determination by the self-diagnosis is reduced, it is possible to suppress erroneous detection due to an inappropriate self-diagnosis.

  In the electric system of the present invention, the step-up converter may be a multiphase converter including a plurality of reactors.

  In the electric system of the present invention, the item of the self-diagnosis may be an overcurrent abnormality, an element overheating abnormality, a circuit abnormality, and an overvoltage abnormality in the boost converter.

  The electric system according to the present invention includes a plurality of sensors for detecting various states of the step-up converter, and the reliability reduction condition includes a power supply abnormality to which the sensor is connected, a voltage drop of a battery to which the sensor is connected, It may be immediately after the voltage drop of the power supply in the drive circuit to which the sensor is connected, the A / D converter abnormality of the drive circuit, or the CPU activation of the drive circuit.

  In the electric system of the present invention, a fuel cell that generates electric power by an electrochemical reaction between fuel gas and oxidizing gas may be provided as the power supply source.

  According to the electric system of the present invention, it is possible to provide an electric system that can perform a self-diagnosis and perform an accurate abnormality determination only in an appropriate state.

1 is a schematic circuit diagram of a fuel cell system that is an electric system according to an embodiment of the present invention. It is a flowchart explaining self-diagnosis, such as overcurrent. It is a flowchart explaining the self-diagnosis of a circuit abnormality. It is a flowchart explaining self-diagnosis, such as an output side overvoltage. It is a flowchart explaining self-diagnosis, such as an input side overvoltage.

  Hereinafter, an embodiment of an electric system according to the present invention will be described with reference to the accompanying drawings. In the present embodiment, a fuel cell system of a fuel cell vehicle (FCHV) will be described as an example of the electric system according to the present invention.

With reference to FIG. 1, the structure of the fuel cell system in this embodiment is demonstrated.
As shown in FIG. 1, the fuel cell system 11 includes a fuel cell (power supply source) 12 that generates electric power by an electrochemical reaction between an oxidizing gas as a reaction gas and the fuel gas.

  The fuel cell 12 is, for example, a polymer electrolyte fuel cell, and has a stack structure in which a large number of single cells are stacked. The single cell has an air electrode on one surface of an electrolyte composed of an ion exchange membrane, a fuel electrode on the other surface, and a structure having a pair of separators so as to sandwich the air electrode and the fuel electrode from both sides. It has become. In this case, hydrogen gas is supplied to the hydrogen gas flow path of one separator, and air, which is an oxidizing gas, is supplied to the oxidizing gas flow path of the other separator, and electric power is generated by the chemical reaction of these reaction gases. .

  The fuel cell 12 is connected to a drive motor (drive source, load) 13 for running the vehicle, and supplies power to the drive motor 13. An FC boost converter (boost converter) 14, a capacitor 15, and a drive inverter 16 are connected to the power supply path from the fuel cell 12 to the drive motor 13 in order from the fuel cell 12 side.

  Thus, in the fuel cell system 11, the electric power generated by the fuel cell 12 is boosted by the FC boost converter 14 and supplied to the drive motor 13 via the drive inverter 16.

  The FC boost converter 14 is a multiphase converter that is a multiphase converter, and includes a plurality (four in this example) of conversion units 31a to 31d. Each of the conversion units 31a to 31d includes a reactor 32, a transistor 33, and a diode 34.

  The drive motor 13 is, for example, a three-phase AC motor, and the drive inverter 16 to which the drive motor 13 is connected converts a direct current into a three-phase alternating current and supplies it to the drive motor 13.

  The fuel cell system 11 includes a battery 21 that supplies power to the drive motor 13. A battery boost converter 23 is connected to the power supply path from the battery 21 to the drive motor 13. The fuel cell system according to the present invention may be configured not to include the battery boost converter 23.

  The power supply path of the battery 21 is connected to the power supply path of the fuel cell 12, and the power from the battery 21 can be supplied to the drive motor 13.

  The battery boost converter 23 of the present embodiment is a DC voltage converter, and has a function of adjusting a DC voltage input from the battery 21 and outputting the same to the drive motor 13 side, and an input from the fuel cell 12 or the drive motor 13. And a function of adjusting the direct-current voltage and outputting it to the battery 21. By such a function of the battery boost converter 23, charging / discharging of the battery 21 is realized. Further, the output voltage of the fuel cell 12 is controlled by the battery boost converter 23. The battery 21 can be charged with surplus power or supplementarily supplied with power.

  The fuel cell system 11 includes an ECU (control unit) 41 having a volatile memory 40. The ECU 41 is connected to the fuel cell 12, the FC boost converter 14, the battery 21, the battery boost converter 23, the drive inverter 16, and the drive motor 13. The ECU 41 includes the fuel cell 12, the FC boost converter 14, the battery. 21, controls the battery boost converter 23, the drive inverter 16, and the drive motor 13.

  The FC boost converter 14 including a multiphase converter includes an IPM (Intelligent Power Module) on which a control board having circuits such as a drive circuit and a protection circuit is mounted.

  In the fuel cell system 11 described above, abnormality determination is performed by a diagnosis (self-diagnostic function) for self-diagnosis of the IPM of the FC boost converter 14. This diagnosis is performed based on detection results from each sensor provided in the FC boost converter 14.

  The items of self-diagnosis include overcurrent abnormality, element overheating abnormality, circuit abnormality, and overvoltage abnormality.

  If an overcurrent abnormality occurs, it recovers if the current reaches a normal value, and if an element overheating abnormality occurs, it recovers if the temperature reaches a normal value. However, when a circuit abnormality occurs, the IPM circuit itself is damaged or defective, and repair is necessary. In addition, when an overvoltage abnormality occurs, the IPM electrical / electronic components are damaged or damaged, so that repair is also necessary.

  For example, in the fuel cell system 11 including the fuel cell 12, a large current flows from the fuel cell 12, so that the FC boost converter 14 that boosts the current of the fuel cell 12 has a plurality of conversion units 31a as described above. A multi-phase converter, which is a multi-phase converter provided with ˜31d, is used. In such a multi-phase converter, even if the current to each phase is evenly distributed, there is a possibility that the current flowing in each phase varies and a current exceeding the allowable value is passed. Even if the total current value is within the allowable value, if the current in any phase is low, an overcurrent exceeding the allowable value may flow in the other phase. Therefore, in a system including a multi-phase converter as the FC boost converter 14, it is preferable that an overcurrent abnormality in the FC boost converter 14 can be self-diagnosed.

  As sensors for self-diagnosis, there are a reactor current sensor S1, an IPM element temperature sensor S2, an IPMFAIL state time detection sensor S3, an output side voltage sensor S4, and an input side voltage sensor S5.

  In the self-diagnosis function, an overcurrent flag is set when the current of the reactor 32 is an overcurrent, and an overheat flag is set when the temperature of an element such as a transistor or a diode is overheated. The FVH overvoltage flag is set when the output side voltage (FVH) of the FC boost converter 14 is an overvoltage, and the FVL overvoltage flag is set when the input side voltage (FVL) of the FC boost converter 14 is an overvoltage. It is done.

  Reactor current sensor S1 is connected to the + and − poles of the power source provided in FC boost converter 14. The IPMFAIL state time detection sensor S3 is connected to a power source in the driving circuit of the IPM. The IPM element temperature sensor S2, the output side voltage sensor S4, and the input side voltage sensor S5 are connected to electrodes of a battery connected to an IPM circuit.

Next, various self-diagnosis will be described.
(Self-diagnosis such as overcurrent)
Self-diagnosis such as overcurrent will be described with reference to the flowchart of FIG.

  Based on the signal from the IPMFFAIL state time detection sensor S3, the diagnosis is started when the duration of the abnormality in the IPMFFAIL state continues for the diagnosis start time (50 ms) (step S01).

  Based on the detection result from the reactor current sensor S1, an overcurrent determination is made as to whether or not an overcurrent flows through the reactor 32 (step S02).

  As a result of the overcurrent determination (step S02), if it is determined that an overcurrent flows through the reactor 32 (with an overcurrent flag), an overcurrent abnormality (step S03) is diagnosed.

  As a result of the overcurrent determination (step S02), if it is determined that no overcurrent flows through the reactor 32 (no overcurrent flag), the IPM element is overheated based on the detection result from the IPM element temperature sensor S2. It is determined whether or not it is overheated (step S04).

  As a result of this overheat determination (step S04), if it is determined that the IPM element is in an overheated state (with an overheat flag), an overheat abnormality (step S05) is diagnosed.

  If it is determined that the IPM element is not in an overheated state (no overheat flag) as a result of the overheat determination (step S05), the IPMFFAIL state abnormality duration is determined based on the signal from the IPMFFAIL state time detection sensor S3. A circuit abnormality determination is made as to whether it is less than the determination time (200 ms) (step S06).

  As a result of the circuit abnormality determination (step S06), if it is determined that the duration of the abnormality in the IPMFFAIL state is less than the circuit abnormality determination time (200 ms), an overcurrent abnormality (step S03) is diagnosed.

  As a result of the circuit abnormality determination (step S06), if it is determined that the duration of the abnormality in the IPMFFAIL state is equal to or longer than the circuit abnormality determination time (200 ms), the IPM circuit abnormality (step S07) is diagnosed.

  An overcurrent abnormality or an overheating abnormality is determined after the continuation time of the abnormality in the IPMFFAIL state has passed the recovery time (200 ms).

(Self-diagnosis of circuit abnormality)
A circuit abnormality self-diagnosis will be described with reference to the flowchart of FIG.

  Based on the signal from the IPMFAIL state time detection sensor S3, the diagnosis is started when the duration of the abnormality in the IPMFFAIL state continues for the diagnosis start time (50 ms) (step S11).

  Based on the signal from the IPMFAIL state time detection sensor S3, a circuit abnormality determination is made as to whether or not the IPMFFAIL state has returned to normal when the duration of the abnormality in the IPMFFAIL state is less than the severe circuit abnormality determination time (400 ms) (step) S12).

  As a result of the circuit abnormality determination (step S12), if it is determined that the IPMFFAIL state has been restored to normal, the IPM circuit abnormality is not determined (step S13).

  As a result of the circuit abnormality determination (step S12), if it is determined that the IPMFFAIL state has not been restored to normal, the IPM circuit abnormality is determined (step S14), and a severe circuit abnormality is diagnosed.

(Self-diagnosis of output overvoltage, etc.)
Self-diagnosis such as output-side overvoltage will be described with reference to the flowchart of FIG.

  Based on the signal from the IPMFFAIL state time detection sensor S3, the diagnosis is started when the duration of the abnormality in the IPMFFAIL state continues for the diagnosis start time (50 ms) (step S21).

  Based on the detection result from the output side voltage sensor S4, an output overvoltage determination is made as to whether or not the output voltage (FVH) is an overvoltage (step S22).

  As a result of the output overvoltage determination (step S22), if it is determined that the output voltage is an overvoltage (with an FVH overvoltage flag), an overvoltage abnormality (step S23) is diagnosed.

  As a result of the output overvoltage determination (step S22), when it is determined that the output voltage is not overvoltage (no FVH overvoltage flag), the IPMFFAIL state abnormality duration is determined based on the signal from the IPMFFAIL state time detection sensor S3. A circuit abnormality determination is made as to whether it is less than the determination time (200 ms) (step S24).

  As a result of the circuit abnormality determination (step S24), if it is determined that the duration of the abnormality in the IPMFFAIL state is less than the circuit abnormality determination time (200 ms), an overvoltage abnormality (step S23) is diagnosed.

  If it is determined as a result of the circuit abnormality determination (step S24) that the duration of the abnormality in the IPMFFAIL state is equal to or longer than the circuit abnormality determination time (200 ms), an IPM circuit abnormality (step S25) is diagnosed.

  The overvoltage abnormality is determined after the continuation time of the abnormality in the IPMFFAIL state has passed the recovery time (200 ms).

(Self-diagnosis of input side overvoltage, etc.)
Self-diagnosis such as input-side overvoltage will be described with reference to the flowchart of FIG.

  Based on the signal from the IPMFFAIL state time detection sensor S3, the diagnosis is started when the duration of the abnormality in the IPMFFAIL state continues for the diagnosis start time (50 ms) (step S31).

  Based on the detection result from the input side voltage sensor S5, an input overvoltage determination is made as to whether or not the input voltage (FVL) is an overvoltage (step S32).

  As a result of this input overvoltage determination (step S32), if it is determined that the input voltage is an overvoltage (with FVL overvoltage flag), an overvoltage abnormality (step S33) is diagnosed.

  As a result of the input overvoltage determination (step S32), when it is determined that the input voltage is not overvoltage (no FVL overvoltage flag), the IPMFFAIL state abnormality duration is determined based on the signal from the IPMFFAIL state time detection sensor S3. A circuit abnormality determination is made as to whether it is less than the determination time (200 ms) (step S34).

  As a result of the circuit abnormality determination (step S34), when it is determined that the duration of the abnormality in the IPMFFAIL state is less than the circuit abnormality determination time (200 ms), an overvoltage abnormality (step S33) is diagnosed.

  As a result of the circuit abnormality determination (step S34), if it is determined that the duration of the abnormality in the IPMFFAIL state is equal to or longer than the circuit abnormality determination time (200 ms), the IPM circuit abnormality (step S35) is diagnosed.

  The overvoltage abnormality is determined after the continuation time of the abnormality in the IPMFFAIL state has passed the recovery time (200 ms).

  Incidentally, as described above, the reactor current sensor S <b> 1 is connected to the + pole and the −pole of the power source provided in the FC boost converter 14. The IPMFAIL state time detection sensor S3 is connected to a power source in the driving circuit of the IPM. The IPM element temperature sensor S2, the output side voltage sensor S4, and the input side voltage sensor S5 are connected to electrodes of a battery connected to an IPM circuit.

  For this reason, if the reactor current sensor S1 has an abnormality in the power supply of the FC boost converter 14, the reliability of the detection result decreases. Further, in the IPM element temperature sensor S2, the output-side voltage sensor S4, and the input-side voltage sensor S5, if the battery voltage is lower than the reference value, the reliability of the detection result is lowered. Further, the reliability of the detection result of the IPMFAIL state time detection sensor S3 is lowered when the voltage of the power source in the drive circuit of the IPM is lower than the reference value.

  Thus, in the state where the reliability of the detection results of the reactor current sensor S1, the IPM element temperature sensor S2, the IPMFAIL state time detection sensor S3, the output side voltage sensor S4, and the input side voltage sensor S5 has been lowered, these sensors S1 to S1. When the self-diagnosis is performed based on the detection result of S5, there is a possibility that an overcurrent abnormality, an element overheating abnormality, a circuit abnormality, and an overvoltage abnormality may be erroneously detected.

  For this reason, in the present embodiment, when the conditions for reducing the reliability of the reactor current sensor S1, the IPM element temperature sensor S2, the IPMFFAIL state time detection sensor S3, the output side voltage sensor S4, and the input side voltage sensor S5 are satisfied, Self-diagnosis is prohibited because the function of self-diagnosis cannot be guaranteed.

  Further, even when an abnormality occurs in the A / D converter of the control board in the IPM or when the IPM CPU is in a state immediately after startup (300 ms), the self-diagnosis function guarantee may not be obtained. Therefore, in this embodiment, self-diagnosis is prohibited even in such a state.

  Specifically, the following reliability degradation conditions (1) to (5) are set, and when any of these reliability degradation conditions (1) to (5) is satisfied, self-diagnosis is performed. Is prohibited.

(Reliability degradation condition)
(1) Power failure of FC boost converter 14 (2) Voltage drop of battery (3) Voltage drop of power supply in IPM drive circuit (4) A / D converter failure (5) Immediately after CPU activation (300 ms)

  Thus, according to the electric system composed of the fuel cell system 11 according to the embodiment, when the reliability of the detection results of various states for determination by the self-diagnosis is reduced, the self-diagnosis is prohibited. False detection due to inappropriate self-diagnosis can be suppressed. In other words, self-diagnosis can be performed only in an appropriate state to make an accurate abnormality determination.

  Regarding the reliability lowering condition (2), the Fail signal is not output before the voltage lowering flag is set by the IPM CPU for the disconnection from the performance guarantee voltage. This voltage drop flag is set when the voltage value from the battery voltage monitor becomes a predetermined value or less. As a result, it is possible to suppress self-diagnosis as an abnormality that requires replacement of the FC boost converter 14 due to a failure of the relay or connector on the upstream side of the FC boost converter 14.

  Moreover, although the case where this invention was applied to the fuel cell system was illustrated in the said embodiment, this invention is applicable also to a hybrid system, a plug-in hybrid system, etc., if it is an electric system.

  In the above-described embodiment, the electric system according to the present invention can be applied to various mobile bodies (robots, ships, aircrafts, etc.) other than vehicles.

DESCRIPTION OF SYMBOLS 11 ... Fuel cell system (electric system), 12 ... Fuel cell (power supply source), 14 ... FC boost converter (boost converter), 32 ... Reactor, S1 ... Reactor current sensor (sensor), S2 ... IPM element temperature sensor ( Sensor), S3... IPMFAIL state time detection sensor (sensor), S4... Output side voltage sensor (sensor), S5... Input side voltage sensor (sensor)

Claims (4)

A power supply source, and a boost converter that boosts the power from the power supply source,
An electric system that detects various states of the boost converter and performs self-diagnosis of the boost converter according to the detection result,
The self-diagnosis of the boost converter is prohibited when the reliability deterioration condition in which the reliability of the detection result of the various states of the boost converter is reduced ,
A plurality of sensors for detecting various states of the boost converter;
The reliability lowering conditions are: power supply abnormality to which the sensor is connected, voltage drop of the battery to which the sensor is connected, voltage drop of the power supply in the drive circuit to which the sensor is connected, A / D converter abnormality of the drive circuit, Or the electric system which is immediately after starting CPU of a drive circuit . The electric system according to claim 1, wherein the boost converter is a multi-phase converter including a plurality of reactors. The electric system according to claim 1, wherein the self-diagnosis items are an overcurrent abnormality, an element overheating abnormality, a circuit abnormality, and an overvoltage abnormality in the boost converter. A fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidizing gas is used as the power supply source.
The electric system as described in any one of Claim 1 to 3 provided.

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