JP2018019526A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device for detecting a failure of a current sensor while inhibiting a product cost from being increased.SOLUTION: A power conversion device 2 disclosed in the specification includes a controller 50 for performing control so as to make a transistor 6b on the high potential side of a second voltage converter of two voltage converters be in an ON state and make all of the remaining transistors 6a, 7a, 7b be in an OFF state to form a current path shown by a broken line, so that current having a predetermined current value flows through current sensors 10a, 10b. The controller 50, when a difference between respective measured values output by the two current sensors 10a, 10b exceeds a predetermined threshold, determines that at least one of the two current sensors 10a, 10b is out of order. Thereby, no other current sensor other than the two current sensors 10a, 10b, a target of failure determination, is required to provide. Therefore, failure detection of the current sensors is performed while inhibiting a product cost from being increased by providing another current sensor.SELECTED DRAWING: Figure 1

Description

  The technology disclosed in the present specification relates to a power conversion apparatus having two voltage converters capable of bidirectional voltage conversion.

  As a power conversion device having a plurality of booster circuits (voltage converters), for example, there is a power conversion system for an electric vehicle disclosed in Patent Document 1 below. In this system, a current detection unit (current sensor) is provided on the input side of each booster circuit in order to detect whether or not a failure has occurred in each booster circuit by the failure detection unit. The failure detection unit detects whether or not each booster circuit has failed based on the current value (current value flowing through the reactor of each booster circuit) obtained from the current detection unit of each booster circuit.

JP, 2015-073423, A

  Each current detector (current sensor) provided in each booster circuit does not necessarily fail. In order to detect a failure of each current detection unit, if a configuration in which another current detection unit (current sensor) is provided is adopted, the number of current detection units (current sensors) is doubled, resulting in an increase in product cost. Invite. The present specification provides a technique for detecting a failure of a current sensor while suppressing an increase in product cost.

  The power conversion device disclosed in the present specification includes two voltage converters capable of bidirectional voltage conversion between a low voltage side and a high voltage side, and a controller that controls the two voltage converters. ing. In these voltage converters, the high voltage sides are connected in parallel (the high voltage side positive terminals and the negative terminals of the two voltage converters are connected). The two voltage converters are connected in reverse parallel to two switching elements connected in series between the positive terminal and the negative terminal on the high voltage side, respectively. A diode, a reactor connected between the connection middle point of the two switching elements and the low voltage side, and a current sensor for measuring a current flowing through the reactor are provided.

  When the controller controls the switching element on the high potential side of one of the two voltage converters to the on state and controls all the remaining switching elements to the off state, the current sensor of one voltage converter A current path (sensor check current path) through which a current flows through the reactor, the high-potential side switching element, the high-potential side diode of the other voltage converter, the reactor, and the current sensor is formed. At this time, the controller determines that at least one of the two current sensors has failed if there is a difference exceeding a predetermined threshold value between the measured values of the two current sensors provided in the two voltage converters. judge.

  When the above-described sensor check current path is formed, the same current flows in the reactors of the two voltage converters. Therefore, if the measured values of the two current sensors included in each of the two voltage converters have a difference exceeding a predetermined threshold, it is determined that at least one of the two current sensors has failed. To do. Therefore, the power conversion device having the above configuration can detect a failure of the current sensor while suppressing an increase in product cost due to the provision of another current sensor.

  The low voltage side of the two voltage converters may be connected in parallel to one battery. Alternatively, the low voltage sides of the two voltage converters may each be connected in parallel to separate batteries. In the former case, the other voltage converter includes a bypass switch that disconnects the connection between the reactor and the positive electrode of the battery and connects the reactor and the negative electrode of the battery. Then, the controller controls the switching element on the high potential side of one voltage converter to the on state, controls all the remaining switching elements to the off state, and bypasses the reactor so that it is disconnected from the positive electrode of the battery and connected to the negative electrode. Control the switch. By doing so, the above-described sensor check current path is formed. In the latter case, a sensor check current path is formed in which a current flows from the positive electrode of the battery having a higher output voltage to the positive electrode of the battery having a lower output voltage without providing a bypass switch. Details of the technology disclosed in this specification, including specific examples of the former and the latter, and further improvements will be described in the embodiments of the invention.

It is a circuit diagram of the power converter device of an Example. It is a flowchart figure of the current sensor failure detection process which a controller performs. It is a circuit diagram of the power converter device by the modification (the 1) of an Example. It is a circuit diagram of the power converter device by the modification (the 2) of an Example.

  A power converter 2 according to an embodiment will be described with reference to the drawings. In FIG. 1, the circuit diagram of the power converter device 2 of an Example is shown. The power conversion device 2 is mounted on, for example, an electric vehicle, and mainly includes two voltage converters 19a and 19b, an inverter 20, a controller 50, and the like. The electric vehicle includes a traveling motor 30 (for example, a three-phase AC motor). The power conversion device 2 is configured to convert DC power supplied from the battery 3 into AC power suitable for the motor 30 and supply the AC power to the motor 30. Thus, when the driver steps on the accelerator pedal, the motor 30 rotates and the electric vehicle travels. When the driver steps on the brake pedal, the motor 30 generates power. The fact that the motor 30 outputs torque and the vehicle travels is referred to as “power running”, and that the motor 30 generates power as a generator is referred to as “regeneration”. The electric power generated by the regeneration is referred to as “regenerative electric power”, and the regenerative electric power is used to charge the battery 3.

  The two voltage converters are referred to as a first voltage converter 19a and a second voltage converter 19b. The first voltage converter 19a includes a reactor 5a, two transistors 6a and 7a, two diodes 8a and 9a, and a current sensor 10a. Reactor 5a has one end electrically connected to the positive terminal of battery 3 via switch 4a, and the other end connected to current sensor 10a. Further, the transistor 6a and the transistor 7a are connected in series between the positive terminal and the negative terminal on the high voltage side. The negative terminal on the high voltage side is directly connected to the negative terminal on the low voltage side. Therefore, the negative terminal on the high voltage side and the negative terminal on the low voltage side are hereinafter referred to as “common negative terminals”. The transistors 6a and 7a are, for example, IGBTs (Insulated Gate Bipolar Transistors).

  In this embodiment, the collector of the transistor 6a is connected to the positive terminal on the high voltage side, the emitter of the transistor 7a is connected to the common negative terminal, and the emitter of the transistor 6a and the collector of the transistor 7a are connected to each other. A connection portion between the transistor 6a and the transistor 7a is referred to as a connection midpoint, and the reactor 5a is connected to the connection midpoint via the current sensor 10a. Control signal lines wired from the controller 50 are connected to the gates of the transistors 6a and 7a, respectively, and are configured to be able to control the switching by transistor drive signals A1 and A2 output from the controller 50. Yes. The transistor 6a is located on the high potential side with respect to the midpoint of connection, and the transistor 7a is located on the low potential side of the midpoint of connection. Therefore, the transistor 6a is sometimes referred to as an upper arm transistor, and the transistor 7a is sometimes referred to as a lower arm transistor.

  Further, diodes 8a and 9a are connected in antiparallel to the transistors 6a and 7a. That is, a diode 8a is connected in parallel in the forward direction from the emitter to the collector of the transistor 6a, and a diode 9a is connected in parallel in the forward direction from the emitter to the collector of the transistor 7a. . The diodes 8a and 9a constitute a bypass path for releasing a current flowing in the reverse direction from the reactor 5a to the transistors 6a and 7a when the transistor 6a and the transistor 7a shift from the on state to the off state. Sometimes referred to as a diode or flywheel diode.

  The basic configuration of the second voltage converter 19b is the same as that of the first voltage converter 19a. That is, the second voltage converter 19b includes a reactor 5b, two transistors 6b and 7b, two diodes 8b and 9b, and a current sensor 10b, which are included in the first voltage converter 19a. , Transistors 6a and 7a, diodes 8a and 9a, and current sensor 10a, respectively. Therefore, description of the basic configuration of the second voltage converter 19b is omitted here, and a configuration different from the first voltage converter 19a will be described.

  In the second voltage converter, the positive terminal on the low voltage side (one end side of the reactor 5b) is connected to the positive terminal on the low voltage side (one end side of the reactor 5a) of the first voltage converter 19a via the switch 13. ing. The switch 13 is connected to a control signal line wired from the controller 50, and is configured so that on / off can be controlled by a switch control signal Sc output from the controller 50. Further, a switch 14 and a resistor 15 connected in series are connected between the positive terminal on the low voltage side of the second voltage converter 19b (one end side of the reactor 5b) and the common negative terminal. The switch 14 is also connected to a control signal line wired from the controller 50, and is configured to be able to be controlled on / off by a switch control signal Sd output from the controller 50. As will be described later, the resistor 15 is used to set a current value flowing in a predetermined current path to a predetermined value when determining the failure of the current sensors 10a and 10b. The controller 50 controls the switch 13 to an on state (connected state) and controls the switch 14 to an off state (released state). Conversely, the controller 50 controls the switch 13 to an off state and turns on the switch 14. There is a case to control to the state. The controller 50 normally maintains the former state. In the former state, the second voltage converter 19b has the same configuration as the first voltage converter 19a, and the first voltage converter 19a and the second voltage converter 19b are connected in parallel between the battery 3 and the inverter 20. It will be. The latter state is a state selected at the time of failure diagnosis of the current sensors 10a and 10b, as will be described later. When one of the switch 13 and the switch 14 is on, the other is controlled to be off. That is, since the switches 13 and 14 are controlled as a pair, these two switches may be collectively referred to as a bypass switch.

  These two voltage converters 19a and 19b are voltage converters capable of bidirectional voltage conversion between the low voltage side and the high voltage side. In this embodiment, the low voltage side and the high voltage side are parallel to each other. Are connected (in this case, the switch 13 is controlled to be on and the switch 14 is controlled to be off). That is, as described above, the positive terminal on the low voltage side is connected to the positive terminal of the battery 3 via the switch 4a, and the common negative terminal is connected to the negative terminal of the battery 3 via the switch 4b. Yes. The high voltage side of the two voltage converters 19 a and 19 b is connected to the inverter 20. Then, each voltage converter boosts the DC voltage of the battery 3 and supplies it to the inverter 20 (boosting operation). When regenerative power is input from the inverter 20, the voltage is stepped down by each voltage converter to charge the battery 3 (step-down operation). The voltage converters 19a and 19b are also referred to as bidirectional DC-DC converters. The battery 3 is a rechargeable battery such as a lithium ion battery or a nickel metal hydride battery.

  The switches 4a and 4b are, for example, system main relays. The system main relay is interlocked with a main switch (not shown) of the electric vehicle, but is configured to be capable of on / off control by the controller 50. In the present embodiment, the switch 4a and the switch 4b are configured to be able to be controlled on and off independently. A control signal line wired from the controller 50 is connected to the switch 4a, and the switch 4a can be controlled to be turned on and off by a switch control signal Sa output from the controller 50. Similarly, the switch 4b can be controlled to be turned on / off by a switch control signal Sb output from the controller 50. Filter or smoothing capacitors 11 and 12 are connected between the low voltage positive terminal and the common negative terminal, and between the high voltage positive terminal and the common negative terminal, respectively.

  The current sensors 10a and 10b are DC current detection elements configured to be able to measure a DC current value flowing through the reactors 5a and 5b. In this embodiment, the current sensors 10a and 10b are electrically connected to the controller 50, and the current sensor signal Ia output from the current sensor 10a and the current sensor signal Ib output from the current sensor 10b are It is configured to be input to the controller 50. As a result, the controller 50 can acquire the current values measured by the current sensors 10a and 10b based on the current sensor signals Ia and Ib. The measured values of the current sensors 10a and 10b (current values flowing through the reactors 5a and 5b) are used for current monitoring when each voltage converter performs a step-up operation or a step-down operation.

  The inverter 20 is a device that converts DC power supplied from the battery 3 into, for example, three-phase AC power suitable for the motor 30 (three-phase AC motor) and supplies it to the motor 30. In the present embodiment, the inverter 20 mainly includes an inverter circuit that converts a DC voltage into an AC voltage, and switching such as an IGBT that is switching-controlled corresponding to each phase of the U, V, and W of the motor 30. It has an element. In this embodiment, the inverter 20 is configured such that the switching element is controlled by a control signal output from the controller 50, and three-phase AC power corresponding to each of U, V, and W phases can be generated.

  The controller 50 is a control device including a semiconductor memory such as a RAM, a ROM, or an EEPROM, an input / output interface, and the like centering on a microcomputer. The controller 50 controls the step-up operation and step-down operation of the two voltage converters 19 a and 19 b, and controls the output torque of the motor 30 for the inverter 20. Further, as will be described later, the switches 4a, 4b, 13, and 14 are controlled to detect a failure of the current sensors 10a and 10b. Therefore, the input / output interface includes transistors 6a, 7a, 6b, 7b of the respective voltage converters 19a, 19b, switches 4a, 4b, 13, 14, current sensors 10a, 10b, an inverter 20 and a rotation sensor of the motor 30 ( (Not shown) is connected.

  The controller 50 executes a process by expanding a control program or the like stored in the ROM or EEPROM into the RAM. In addition, a program for current sensor failure detection processing described later is also stored in the ROM or EEPROM of the controller 50. The controller 50 is also connected to an in-vehicle network such as CAN or LIN, and the accelerator opening information based on the depression amount of the accelerator pedal by the driver, the brake depression amount information based on the depression amount of the brake pedal, etc. It can be obtained in real time via In FIG. 1, the controller 50 is represented by one rectangle, but the function is realized in cooperation with a plurality of microcomputers.

  The current sensors 10a and 10b measure current values flowing through the reactors 5a and 5b and output current sensor signals Ia and Ib as information necessary for the voltage converters 19a and 19b to perform step-up and step-down operations. . Therefore, when a failure or the like occurs and normal current sensor signals Ia and Ib cannot be output, it is necessary to detect the abnormality. Therefore, in this embodiment, the controller 50 detects the abnormality of the current sensors 10a and 10b by performing the current sensor failure detection process shown in FIG. This process is executed by being incorporated into a predetermined failure diagnosis program that is executed immediately after a main switch (not shown) of the electric vehicle is turned on, for example.

  As shown in FIG. 2, in the current sensor failure detection process, first, a process of controlling each switch to a predetermined state is performed in step S2. The switches are the switches 4a, 4b, 13, and 14 described above. In the present embodiment, the controller 50 controls the switches 4a, 4b, and 14 to be on and controls the switch 13 to be off. Subsequently, in step S3, a process for controlling the transistors 6a, 7a, 6b, and 7b to a predetermined state is performed. In the present embodiment, the controller 50 controls the transistor 6b to be on and controls the transistors 6a, 7a, and 7b to be off.

  As a result, as shown by the broken line in FIG. 1, from the positive terminal of the battery 3, the switch 4a → the positive terminal on the low voltage side of the first voltage converter 19a → the reactor 5a → the current sensor 10a → the diode 8a → the positive terminal on the high voltage side. Terminal → transistor 6b → current sensor 10b → reactor 5b → positive terminal on the low voltage side of the second voltage converter 19b → switch 14 → resistor 15 → common negative terminal → current path returning to the negative terminal of the battery 3 via the switch 4b (Sensor check current path) is formed. At this time, the same current flows through reactors 5a and 5b. The current value at this time is preset by, for example, the resistance value of the resistor 15. If the current sensors 10a and 10b are normal, the measured values of the current sensors are the same value.

  In step S4, processing for acquiring current data from each of the current sensors 10a and 10b is performed. The controller 50 obtains measured values (current values) of both the current sensors 10a and 10b based on the current sensor signal Ia output from the current sensor 10a and the current sensor signal Ib output from the current sensor 10b. In step S5, it is determined whether each current value is within a predetermined range.

  For example, the controller 50 determines whether or not the measured values (current values) of the current sensors 10a and 10b exceed a predetermined upper limit reference value (predetermined threshold value) set in advance, or a predetermined predetermined value. The determination is made based on whether or not the measured values (current values) of the current sensors 10a and 10b are lower than the lower limit reference value (predetermined threshold value). When the measured value of at least one of the current sensors 10a and 10b exceeds a predetermined upper limit reference value or falls below a predetermined lower limit reference value, each measured value is predetermined. It is determined that it is not within the range (S5: NO). Further, when the measured values of both current sensors 10a and 10b are between the predetermined upper limit reference value and the predetermined lower limit reference value, it is determined that each measured value is within the predetermined range. (S5: YES).

  Further, for example, the difference between the measured values of the two current sensors 10a and 10b may be calculated and the determination may be made based on whether or not the difference exceeds a predetermined threshold value. In this case, it is determined that each measured value is not within the predetermined range when the difference between the measured values exceeds a predetermined threshold (S5: NO), and each measurement is performed when the measured value difference is equal to or smaller than the predetermined threshold. It is determined that the value is within a predetermined range (S5: YES). This determination method is characterized in that it can be configured with a simple algorithm as compared with the case where each measured value of the current sensors 10a and 10b is compared with a predetermined upper limit reference value and a predetermined lower limit reference value. When it is determined that each measured value is not within the predetermined range (S5: NO), it is difficult to specify the current sensors 10a and 10b suspected of malfunctioning.

  When it is determined by the determination process in step S5 that each measurement value is within the predetermined range (S5: YES), the current sensor failure detection process is highly likely because the current sensors 10a and 10b are all normal. Finish. On the other hand, when it is determined by the determination process in step S5 that each measurement value is not within the predetermined range (S5: NO), there is a possibility that a failure has occurred in any of the current sensors 10a and 10b. is there. In this case, a process of outputting failure information of the current sensor is performed in step S6.

  Specifically, for example, the controller 50 represents a sensor ID and a failure content for specifying the current sensor 10a or the current sensor 10b suspected of failure with respect to another controller or a higher-level controller connected via the in-vehicle network. Send the code together. Thereby, for example, the failure of the power conversion device 2 including the current sensors 10a and 10b is displayed on the instrument panel of the electric vehicle.

  In the power conversion device 2 of FIG. 1, the second voltage converter 19 b disconnects the connection between the reactor 5 b and the positive terminal of the battery 3 and also connects a bypass switch (switch) between the reactor 5 b and the negative electrode of the battery 3. 13 and 14). In Steps S2 and S3 of FIG. 2, the controller 50 controls the high-potential side transistor 6a of the first voltage converter 19a to be in an on state and controls all the remaining transistors 7a, 6b, and 7b to be in an off state. The bypass switch (switches 13 and 14) is controlled so that the reactor 5b of the second voltage converter 19b is disconnected from the positive terminal of the battery 3 and connected to the negative terminal. By doing so, a sensor check current path through which the same current flows in the current sensors 10a and 10b of the two voltage converters 19a and 19b is formed.

  When two voltage converters are connected to the batteries 3 and 16 having different voltages, a circuit configuration as shown in FIG. 3 can be adopted. In FIG. 3, the circuit diagram of the power converter device 2a by the modification (the 1) of an Example is shown. In the case of this power conversion device 2a, the switches 13a and 18b that turn on and off the electrical connection between the second voltage converter 19c and the battery 16 are required instead of the switches 13 and 14 described above. The switches 18a and 18b are system main relays that are linked to a main switch (not shown) of the electric vehicle, similarly to the switches 4a and 4b. The switches 18a and 18b are configured to be able to be turned on / off by switch control signals Se and Sf from the controller 50. Similarly to the battery 3, the battery 16 is a rechargeable battery such as a lithium ion battery or a nickel metal hydride battery. The output voltage VB2 of the battery 16 is lower than the output voltage VB1 of the battery 3 (VB1> VB2). The first voltage converter 19a in FIG. 3 has the same configuration as the first voltage converter 19a in FIG.

  Even in this modified example (part 1), it is possible to determine the failure of the current sensors 10a and 10b by the current sensor failure detection process shown in FIG. For example, in step S2 shown in FIG. 2, the controller 50 controls the switches 4a, 4b, 16a, and 16b to be in an on state, and in subsequent step S3, the transistor 6b is controlled to be in an on state, so that the transistors 6a, 7a, and 7b To turn off.

  Thus, as shown by the broken line in FIG. 3, from the positive terminal of the battery 3, the switch 4a → the positive terminal on the low voltage side of the first voltage converter 19a → the reactor 5a → the current sensor 10a → the diode 8a → the positive terminal on the high voltage side. Terminal → transistor 6b → current sensor 10b → reactor 5b → positive terminal on the low voltage side of the second voltage converter 19c → current path (sensor check current path) returning to the positive terminal of the battery 16 via the switch 18a is formed. The Therefore, the failure determination of the current sensors 10a and 10b can be performed by step S4 and step S5, and the result can be output by step S6.

  As shown in FIG. 1, the switch 14 and the resistor 15 connected in series may be connected between the low voltage side positive terminal (one end side of the reactor 5b) and the common negative terminal of the second voltage converter 19a. Good. In this case, from the positive terminal of the battery 3, the switch 4a → the low voltage side positive terminal of the first voltage converter 19a → the reactor 5a → the current sensor 10a → the diode 8a → the high voltage side positive terminal → the transistor 6b → the current sensor. 10b → Reactor 5b → Low voltage side positive terminal of second voltage converter 19b → Switch 14 → Resistance 15 → Common negative terminal → Current path returning to the negative terminal of battery 16 via switch 18b (or switch 4b) (sensor A current path for checking) is formed.

  Further, when the three voltage converters 19a, 19d, and 19e are connected to the battery 3, a circuit configuration as shown in FIG. 4 can be adopted. In FIG. 4, the circuit diagram of the power converter device 2b by the modification (the 2) of an Example is shown. In the case of this power converter 2b, the above-described switch 14 is not necessary. In this modified example (No. 2), the third voltage converter is referred to as a “third voltage converter 19e”. In FIG. 4, the reference numeral “19d” is attached to the second voltage converter. The third voltage converter 19e is configured similarly to the first voltage converter 19a. That is, the third voltage converter 19e includes a reactor 5c, two transistors 6c and 7c, two diodes 8c and 9c, and a current sensor 10c, which are included in the first voltage converter 19a. , Transistors 6a and 7a, diodes 8a and 9a, and current sensor 10a, respectively. Therefore, description of the configuration of the third voltage converter 19e is omitted here.

  Note that control signal lines wired from the controller 50 are connected to the gates of the transistors 6c and 7c, respectively, and the switching can be controlled by the transistor drive signals C1 and C2 output from the controller 50. Has been. Further, the current sensor signal Ic output from the current sensor 10 c can be input to the controller 50. Thereby, the controller 50 can acquire the measured value (current value) of the current sensor 10c based on the current sensor signal Ic. The measured value of the current sensor 10c is used for current monitoring when the third voltage converter 19e performs a step-up operation or a step-down operation.

  Even in this modified example (part 2), it is possible to determine the failure of the current sensors 10a and 10b by the current sensor failure detection process shown in FIG. For example, in step S2 shown in FIG. 2, the controller 50 controls the switches 4a and 4b to be in an on state, and in subsequent step S3, the transistors 6b and 7c are controlled to be in an on state, so that the transistors 6a, 7a, 7b and 6c are controlled. To turn off.

  As a result, as shown by a broken line in FIG. 4, from the positive terminal of the battery 3, the switch 4a → the positive terminal on the low voltage side of the first voltage converter 19a → the reactor 5a → the current sensor 10a → the diode 8a → the positive terminal on the high voltage side. Terminal → transistor 6b → current sensor 10b → reactor 5b → positive terminal on the low voltage side of the second voltage converter 19d → positive terminal on the low voltage side of the third voltage converter 19e → reactor 5c → current sensor 10c → transistor 7c → common negative electrode A current path (sensor check current path) is formed that returns from the terminal to the positive terminal of the battery 3 via the switch 4b.

  Therefore, at step S5 shown in FIG. 2, for example, the controller 50 sets the measured values (current values) of the current sensors 10a, 10b, and 10c with respect to a predetermined upper limit reference value (predetermined threshold value). The determination is made based on whether or not the measured value exceeds the predetermined lower limit reference value (predetermined threshold value), and whether or not the measured values of the current sensors 10a, 10b, and 10c are lower than each other. When the measurement value of at least one of the current sensors 10a, 10b, and 10c exceeds a predetermined upper limit reference value or falls below a predetermined lower limit reference value, each measurement value Is determined not to be within the predetermined range (S5: NO). In addition, when the measured values of these current sensors 10a, 10b, and 10c have respective current values between a predetermined upper limit reference value and a predetermined lower limit reference value, each measured value is within a predetermined range. (S5: YES).

  Further, for example, a difference between measured values of two current sensors determined in advance among these current sensors 10a, 10b, and 10c is calculated, and the determination is made based on whether or not the difference exceeds a predetermined threshold value. May be. For example, the difference between the measured value of the current sensor 10a and the measured value of the current sensor 10b, the difference between the measured value of the current sensor 10a and the measured value of the current sensor 10c, and the measured value of the current sensor 10b and the measured value of the current sensor 10c. The difference from the value. In this case, it is determined that each measured value is not within the predetermined range when the difference between the measured values exceeds a predetermined threshold (S5: NO), and each measurement is performed when the measured value difference is equal to or smaller than the predetermined threshold. It is determined that the value is within a predetermined range (S5: YES).

  When it is determined by the determination process in step S5 that each measured value is within the predetermined range (S5: YES), the current sensors 10a, 10b, and 10c are all likely to be normal. Finish the detection process. On the other hand, if it is determined by the determination process in step S5 that each measurement value is not within the predetermined range (S5: NO), a failure may have occurred in any of the current sensors 10a, 10b, and 10c. There is sex. In this case, a process of outputting failure information of the current sensor is performed in step S6. In the process of step S6, a sensor ID that identifies the current sensor 10a, current sensor 10b, or current sensor 10c suspected of failure and a code representing the failure content are transmitted to another controller connected via the in-vehicle network.

  Note that a current limiting resistor (for example, resistor 15) and a switch connected in parallel are a positive terminal on the low voltage side (one end side of the reactor 5b) of the second voltage converter 19d and a low voltage of the third voltage converter 19e. You may connect between the side positive terminal (one end side of the reactor 5c). When the failure of the current sensors 10a, 10b, and 10c is determined, this switch is controlled to be turned off by the controller 50, and at the time of step-up operation or step-down operation, this switch is controlled to be turned on by the controller 50. Thereby, it becomes possible to prevent a current exceeding a predetermined current from flowing in the current path formed at the time of failure determination. In this case, from the positive terminal of the battery 3, the switch 4a → the low voltage side positive terminal of the first voltage converter 19a → the reactor 5a → the current sensor 10a → the diode 8a → the high voltage side positive terminal → the transistor 6b → the current sensor. 10b → Reactor 5b → Positive terminal on the low voltage side of the second voltage converter 19d → Resistance for current limitation → Positive terminal on the low voltage side of the third voltage converter 19e → Reactor 5c → Current sensor 10c → Transistor 7c → Common negative terminal → A current path (sensor check current path) that returns to the positive terminal of the battery 3 via the switch 4b is formed.

  As described above, in the power converters 2 and 2a of the present embodiment, the controller 50 includes the second voltage converter 19a (of the two voltage converters (first voltage converter 19a and second voltage converter 19b (19c)). 19c), when the high potential side transistor 6b is controlled to be on and all the remaining transistors 6a, 7a and 7b are controlled to be off, a current path indicated by a broken line in FIG. A current of a predetermined measurement value flows through 10b. When the measured values of the two current sensors 10a and 10b respectively provided in the two voltage converters 19a and 19b have a difference exceeding a predetermined threshold, the controller 50 determines whether the two current sensors 10a and 10b have the difference. It is determined that at least one has failed (S5: NO). Thereby, it is not necessary to provide another current sensor other than the two current sensors 10a and 10b to be subjected to the failure determination. Therefore, it is possible to detect a failure of the current sensor while suppressing an increase in product cost due to provision of another current sensor.

  In the power converter 2b of the present embodiment, the controller 50 includes the second voltage converter 19d among the three voltage converters (first voltage converter 19a, second voltage converter 19d, and third voltage converter 19e). When the high-potential side transistor 6b and the low-potential side transistor 7c of the third voltage converter 19e are controlled to be in an on state and all the remaining transistors 6a, 7a, 7b, and 6c are controlled to be in an off state, FIG. A current path indicated by a broken line is formed, and a current of a predetermined measurement value flows through the current sensors 10a, 10b, and 10c. The controller 50 sets a predetermined threshold value for two measurement values out of the three measurement values output from the three current sensors 10a, 10b, and 10c provided in the three voltage converters 19a, 19d, and 19e, respectively. When there is a difference exceeding, it is determined that at least one of the three current sensors 10a, 10b, and 10c has failed (S5: NO). Thereby, it is not necessary to provide another current sensor other than the two current sensors 10a, 10b, and 10c to be subjected to failure determination. Therefore, it is possible to detect a failure of the current sensor while suppressing an increase in product cost due to provision of another current sensor.

  Points to be noted regarding the example technology will be described. The reactor 5b, the transistors 6b and 7b, and the diodes 8b and 9b constituting the second voltage converter 19b (19c and 19d) correspond to an example of one voltage converter. The reactor 5a, the transistors 6a and 7a, and the diodes 8a and 9a constituting the first voltage converter 19a correspond to an example of the other voltage converter. The transistors 6a, 6b, 7a, and 7b correspond to an example of a switching element.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. Further, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Moreover, the technique illustrated in this specification or the drawings achieves a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2, 2a, 2b: Power conversion device 3, 16: Battery 4a, 4b, 4c, 4d, 13, 14, 18a, 18b: Switch 5a, 5b, 5c: Reactor 6a, 6b, 6c, 7a, 7b, 7c: Transistors 8a, 8b, 8c, 9a, 9b, 9c: Diodes 10a, 10b, 10c: Current sensors 11, 12, 17: Capacitor 15: Resistors 19a-19e: Voltage converter 20: Inverter 30: Motor 50: Controller

Claims (1)

A power conversion device comprising two voltage converters capable of bidirectional voltage conversion and a controller for controlling these two voltage converters,
The two voltage converters are respectively
Two switching elements connected in series between the positive terminal and the negative terminal on the high voltage side;
A diode connected in antiparallel to each of the two switching elements;
A reactor connected between the midpoint of connection between the two switching elements and the low voltage side;
A current sensor for measuring a current flowing through the reactor;
And
The two voltage converters are connected in parallel on the high voltage side,
When the controller controls the switching elements on the high potential side of one of the two voltage converters to an on state and controls all the remaining switching elements to an off state, the one voltage The current sensor and the reactor of the converter and the switching element on the high potential side, and the current path through which the current flows through the diode, the reactor and the current sensor on the high potential side of the other voltage converter are formed. In the controller, when there is a difference exceeding a predetermined threshold value between the measured values of the two current sensors included in the two voltage converters, at least one of the two current sensors has failed. The power converter characterized by determining that it exists.

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