JP2010124588A - Dc-dc converter unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC-DC converter unit capable of achieving, e.g. scale-down of the entire DC-DC converter unit and cost saving by increasing the variety of methods for detecting an abnormality of switching operation. <P>SOLUTION: When detecting an abnormality of any one of upper arm switching elements 81u-81w and lower arm switching elements 82u-82w, a converter control section 48 stops a phase arm having the switching element in which the abnormality is detected, and causes the other phase arms to alternately switch. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a DC / DC converter apparatus in which a plurality of phase arms having switching elements are connected in parallel between a primary side and a secondary side. More specifically, the present invention relates to a DC / DC converter device that detects an abnormality in a switching operation of a plurality of the switching elements.

  A vehicle in which a DC / DC converter is disposed between a charging device and a traveling motor, and the output voltage of the charging device is boosted and supplied to the traveling motor, and the regenerative voltage from the traveling motor is stepped down and supplied to the charging device. Known (Patent Document 1). In the DC / DC converter of Patent Document 1, a disconnection detection circuit is connected between the drive circuit and the switching element, and the disconnection detection circuit detects a disconnection between the drive circuit and the switching element (summary of Patent Document 1). reference).

JP 2007-295687 A

  In the DC / DC converter described in Patent Document 1, since a circuit dedicated to disconnection detection is provided between the drive circuit and the switching element, various restrictions arise accordingly. For example, the DC / DC converter is increased in size and the design freedom is reduced.

  The present invention has been made in consideration of such problems. For example, the DC / DC converter apparatus can be reduced in size and cost can be reduced by diversifying a method for detecting an abnormality in the switching operation. An object is to provide a DC converter device.

  In the DC / DC converter device according to the present invention, a plurality of phase arms having switching elements are connected in parallel between a primary side and a secondary side, and a plurality of the phase arms are driven by a drive signal. A control unit that performs switching alternately, a temperature sensor that detects an element temperature of the switching element, and an abnormality detection unit that detects an abnormality of the switching operation of the switching element based on the detected element temperature, When the abnormality detection unit detects an abnormality in the switching operation of the switching element, the control unit stops the phase arm having the switching element in which the abnormality is detected, and switches the remaining phase arm to switch. To do.

  According to the present invention, the abnormality of the switching operation can be detected from the element temperature of the switching element. As a result, it is possible to diversify the method for detecting an abnormality in the switching operation. In particular, in the case of a configuration in which a temperature sensor is provided to determine overheating of the switching element, the entire DC / DC converter can be reduced in size and cost can be achieved by using the temperature sensor for detecting an abnormality of the switching element. .

  Further, when an abnormality of any of the switching elements is detected, the remaining phase arms are switched and switched. Thereby, the difficulty of the transformation control by the switching element from which abnormality was detected not switching can be avoided. Furthermore, even when an abnormality occurs in the switching operation of any of the switching elements, it is possible to maintain the advantage (for example, excellent heat dissipation) of switching the phase arms by switching.

  The control unit sets a limit value of power passing through the DC / DC converter device when the remaining phase arm is switched and switched, and when the remaining phase arm is switched and switched, the DC The power passing through the DC converter device may be controlled so as not to exceed the limit value.

  The control unit determines the maximum temperature from the element temperature of each switching element, and the switching element has an error in switching operation in which a deviation from the maximum temperature exceeds a deviation threshold set in advance to determine an abnormality in the switching operation. It may be determined that has occurred.

  According to the present invention, the abnormality of the switching operation can be detected from the element temperature of the switching element. As a result, it is possible to diversify the method for detecting an abnormality in the switching operation. In particular, in the case of a configuration in which a temperature sensor is provided to determine overheating of the switching element, the entire DC / DC converter can be reduced in size and cost can be achieved by using the temperature sensor for detecting an abnormality of the switching element. .

  Further, when an abnormality of any of the switching elements is detected, the remaining phase arms are switched and switched. Thereby, the difficulty of the transformation control by the switching element from which abnormality was detected not switching can be avoided. Furthermore, even when an abnormality occurs in the switching operation of any of the switching elements, it is possible to maintain the advantage (for example, excellent heat dissipation) of switching the phase arms by switching.

A. Explanation of overall configuration [Overall configuration]
FIG. 1 shows a schematic overall configuration diagram of a fuel cell vehicle 10 equipped with a DC / DC converter device 50 according to this embodiment.

  The fuel cell vehicle 10 basically includes a battery 12 as a first DC power supply device that generates a primary voltage V1 on the primary side 1S and a second DC power supply that generates a secondary voltage V2 on the secondary side 2S. A hybrid DC power supply device including a fuel cell 14 as a device and a traveling motor 16 that is a load supplied with electric power from the hybrid DC power supply device.

[Fuel cell and its system]
The fuel cell 14 has, for example, a stack structure in which cells formed by sandwiching a solid polymer electrolyte membrane between an anode electrode and a cathode electrode from both sides are stacked. A reaction gas supply unit 18 is connected to the fuel cell 14 through a pipe. The reactive gas supply unit 18 includes a hydrogen tank that stores hydrogen (fuel gas) that is one reactive gas, and a compressor that compresses air (oxidant gas) that is the other reactive gas. A power generation current generated by an electrochemical reaction in the fuel cell 14 of hydrogen and air supplied from the reaction gas supply unit 18 to the fuel cell 14 is supplied to the motor 16 and the battery 12.

  The fuel cell system 11 includes a fuel cell 14 and a reaction gas supply unit 18 and a fuel cell control unit (FC control unit) 44 that controls them.

[DC / DC converter]
The DC / DC converter 20 is a chopper type voltage converter in which one side is connected to the battery 12 and the other side is connected to the secondary side 2S that is a connection point between the fuel cell 14 and the motor 16.

  The DC / DC converter 20 converts the primary voltage V1 into a secondary voltage V2 (V1 ≦ V2) (boost conversion), and also converts the secondary voltage V2 into a primary voltage V1 (step-down conversion). This is a voltage conversion device.

[Inverter, motor and drive system]
The inverter 22 has a three-phase full-bridge configuration, performs DC / AC conversion, converts DC to three-phase AC, and supplies it to the motor 16, while DC after AC / DC conversion accompanying the regenerative operation. Is supplied from the secondary side 2S to the primary side 1S through the DC / DC converter 20, and the battery 12 is charged.

  The motor 16 rotates the wheels 26 through the transmission 24. In practice, the inverter 22 and the motor 16 are collectively referred to as a load 23.

[High voltage battery]
The high voltage battery 12 connected to the primary side 1S is a power storage device (energy storage), and for example, a lithium ion secondary battery or a capacitor can be used. In this embodiment, a lithium ion secondary battery is used.

[Various sensors, main switches and communication lines]
A main switch (power switch) 34 and various sensors 36 are connected to a communication line 38. The main switch 34 has a function as an ignition switch that turns on (starts or starts) and turns off (stops) the fuel cell vehicle 10 and the fuel cell system 11. Various sensors 36 detect state information, such as a vehicle state and an environmental state. As the communication line 38, a CAN (Controller Area Network) that is an in-vehicle LAN is used.

[Control unit]
The integrated control unit 40, the FC control unit 44, the motor control unit 46, the converter control unit 48, and the battery control unit 52 are connected to the communication line 38. A DC / DC converter device 50 is formed by the DC / DC converter 20 and the converter control unit 48 that controls the DC / DC converter 20.

  Each control unit 40, 44, 46, 48, 52 includes a microcomputer, detects state information of various switches such as the main switch 34 and various sensors 36, and also controls each of the control units 40, 44, 46, 48, 52. Each CPU implements various functions by inputting status information from these switches and sensors and information (commands, etc.) from other controllers, and executing programs stored in memory (ROM). It operates as a function realization unit (function realization means). The control units 40, 44, 46, 48, and 52 have an input / output interface such as a timer, an A / D converter, and a D / A converter, as necessary, in addition to the CPU and memory.

B. Detailed configuration description [DC / DC converter device]
FIG. 2 shows a detailed configuration of the DC / DC converter 20. The DC / DC converter 20 includes three-phase phase arms UA, VA, WA arranged between the primary side 1S and the secondary side 2S, and a reactor 90.

  The U-phase arm UA includes an upper arm element (upper arm switching element 81u and diode 83u) and a lower arm element (lower arm switching element 82u and diode 84u).

  V-phase arm VA includes an upper arm element (upper arm switching element 81v and diode 83v) and a lower arm element (lower arm switching element 82v and diode 84v).

  W-phase arm WA includes an upper arm element (upper arm switching element 81w and diode 83w) and a lower arm element (lower arm switching element 82w and diode 84w).

  As the upper arm switching elements 81u, 81v, 81w and the lower arm switching elements 82u, 82v, 82w, for example, MOSFETs or IGBTs are employed.

  Reactor 90 is inserted between the midpoint (common connection point) of each phase arm UA, VA, WA and the positive electrode of battery 12, and is connected between primary voltage V1 and secondary voltage V2 by DC / DC converter 20. When the voltage is converted at, energy is released and stored.

  The upper arm switching elements 81u, 81v, 81w are turned on by the high level of the gate drive signals (drive voltages) UH, VH, WH output from the converter control unit 48, and the lower arm switching elements 82u, 82v, 82w are The gate driving signals (driving voltages) are turned on by the high levels of UL, VL, WL. The converter control unit 48 detects the primary voltage V1 by the voltage sensor 91 provided in parallel with the primary side smoothing capacitor 94, detects the primary current I1 by the current sensor 101, and detects the secondary side smoothing capacitor 96. The secondary voltage V2 is detected by a voltage sensor 92 provided in parallel with the current sensor 102, and the secondary current I2 is detected by a current sensor 102.

  A temperature sensor 69 is attached to each of the upper arm switching elements 81u, 81v, 81w and the lower arm switching elements 82u, 82v, 82w, and the upper arm switching elements 81u, 81v, 81w and the lower arm switching elements 82u, 82v, 82w The detected temperatures Tuh (81u), Tvh (81v), Twh (81w), Tul (82u), Tvl (82v), and Twl (82w) are detected by the converter control unit 48.

[Operation of DC / DC converter device]
(3-phase arm replacement drive operation: also called 3-phase operation)
The time chart of FIG. 3 is an explanatory diagram of the three-phase arm replacement drive operation of the DC / DC converter device 50.

  In the step-down chopper control related to the step-down operation (regeneration operation), the secondary current I2 flowing out from the load 23 and the fuel cell 14 passes through the DC / DC converter 20 and charges the battery 12 as the primary current I1. In the step-up chopper control related to the step-up operation (power running operation), the primary current I1 flowing out from the battery 12 passes through the DC / DC converter 20 and the load 23 including the motor 16 is driven as the secondary current I2.

Assuming that the switching period is 2π = T and the period during which a high-level drive signal is transmitted to the upper and lower arm switching elements 81 and 82 is Ton, the drive duty (ON duty) in the step-down chopper control is ignored if the dead time dt is ignored. ) Is expressed by equation (1), and the drive duty in boost chopper control is expressed by equation (2).
Ton / T = V1 / V2 (1)
Ton / T = (1−V1 / V2) (2)

  Among the waveforms of the drive signals UH, UL, VH, VL, WH, WL, the hatched period is an arm switching element (for example, drive signal) to which the drive signals UH, UL, VH, VL, WH, WL are supplied. The arm switching element corresponding to UH indicates a period during which the upper arm switching element 81u) is flowing (current is flowing).

  In any operation of the step-down chopper control and step-up chopper control of the DC / DC converter 20, the upper arm switching element 81 (81u to 81w) and the lower arm switching element 82 (82u) of the same phase every switching cycle 2π. To 82w), high level drive signals UH, UL, VH, VL, WH, WL are output. In addition, the drive signals UH, UL, VH, VL, WH, and WL are output by changing (rotating) the UVW phase. In the step-down chopper control, the upper arm switching element 81 (81u to 81w) is allowed to flow, and in the step-up chopper control, the lower arm switching element 82 (82u to 82w) is allowed to flow.

  In this case, in order to prevent the secondary voltage V2 from being short-circuited simultaneously between the upper and lower arm switching elements 81 and 82, each of the drive signals UH, UL, VH, VL, WH, WL has a dead time dt. It is trying to make it high level across. That is, so-called synchronous switching is performed with the dead time dt interposed therebetween.

  In the step-down chopper control, first, the secondary current I2 flows as the primary current I1 to the reactor 90 through the upper arm switching element 81u during a period in which only the upper arm switching element 81u (U phase) is passed by the drive signal UH. The energy is accumulated in the reactor 90 and the battery 12 is charged.

  Next, during a period in which only the drive signal UL is at a high level, the lower arm switching element 82u does not flow, and the diodes 84u, 84v, 84w are turned on to release the energy accumulated in the reactor 90. The battery 12 is charged. Hereinafter, similarly, the V phase and the W phase are repeated.

  In the step-up chopper control, first, energy is accumulated in the reactor 90 by the primary current I1 from the battery 12 during a period in which only the drive signal UL (U phase) is at a high level (a period indicated by hatching). At this time, a current is supplied from the secondary side smoothing capacitor 96 to the load 23.

  Next, during a period in which only the drive signal VH (V phase) is at a high level, the upper arm switching element 81v does not flow, and the diodes 83u, 83v, 83w are conducted and accumulated in the reactor 90. The energy is released, the primary current I1 from the reactor 90 passes through the DC / DC converter 20, charges the secondary-side smoothing capacitor 96 as the secondary current I2, and is supplied to the load 23. Hereinafter, the V phase and the W phase are similarly repeated.

  That is, in the three-phase arm replacement drive operation, the U-phase arm UA, the V-phase arm VA, and the W-phase arm WA are switched and switched.

[Detection of gate disconnection abnormality]
FIG. 4 shows a flowchart for detecting a gate disconnection abnormality of each phase in the present embodiment.

  In step S1, converter control unit 48 determines whether primary current I1 is greater than zero. When the primary current I1 is greater than zero (that is, when it takes a positive value), current flows from the primary side 1S to the secondary side 2S, and power is supplied from the battery 12 to the motor 16. When primary current I1 is larger than zero (S1: Yes), converter control unit 48 stops detecting the abnormality of the upper arm element in step S2. That is, the flags FLGuh, FLGvh, and FLGwh related to the upper arm element of each phase are set to “0”. Flags FLGuh, FLGvh, and FLGwh indicate whether or not a gate disconnection abnormality is detected for the upper arm element of each phase. When the flag FLGuh, FLGvh and FLGwh is “0”, it indicates that no gate disconnection abnormality is detected. Indicates that an abnormal gate disconnection is detected. In subsequent step S3, converter control unit 48 performs a lower arm element abnormality detection process.

  When primary current I1 is zero or less in step S1 (S1: No), converter control unit 48 stops detecting an abnormality of the lower arm element in step S4. That is, the flags FLGul, FLGvl, and FLGwl related to the lower arm element of each phase are set to “0”. Flags FLGul, FLGvl, and FLGwl indicate whether or not a gate disconnection abnormality is detected for the lower arm element of each phase. When “0”, it indicates that no gate disconnection abnormality is detected, and “1”. Indicates that an abnormal gate disconnection is detected. In subsequent step S5, converter control unit 48 performs an abnormality detection process for the upper arm element of each phase.

  After step S3 or step S5, converter control unit 48 performs abnormality determination processing for the U phase, the V phase, and the W phase in steps S6 to S8.

  FIG. 5 shows a flowchart of the abnormality detection process (S3 in FIG. 4) of the lower arm element of each phase.

  In step S11, converter control unit 48 determines the maximum temperature (lower arm maximum temperature Tal_max) [° C.] among the detected temperatures Tul, Tvl, Twl of lower arm switching elements 82u, 82v, 82w.

  In step S12, converter control unit 48 determines whether or not the difference between lower arm maximum temperature Tal_max and detected temperature Tul exceeds a threshold temperature (lower arm threshold temperature THal_tem) [° C.] for determining a gate disconnection abnormality of the lower arm element. Determine. When the difference is equal to or lower than the lower arm threshold temperature THal_tem (S12: No), the process proceeds to step S14. When the difference is larger than the lower arm threshold temperature THal_tem (S12: Yes), in step S13, converter control unit 48 starts detecting a gate disconnection abnormality of lower arm switching element 82u. That is, the flag FLGul related to the lower arm switching element 82u is set to “1”. After step S13, the process proceeds to step S14.

  The processes of steps S14 and S15 and steps S16 and S17 are the same as steps S12 and S13. That is, in step S14, converter control unit 48 determines whether or not the difference between lower arm maximum temperature Tal_max and detected temperature Tvl exceeds lower arm threshold temperature THal_tem. When the difference is equal to or lower than the lower arm threshold temperature THal_tem (S14: No), the process proceeds to step S16. When the difference is larger than the lower arm threshold temperature THal_tem (S14: Yes), in step S15, converter control unit 48 starts detecting a gate disconnection abnormality of lower arm switching element 82v. That is, the flag FLGvl related to the lower arm switching element 82v is set to “1”. After step S15, the process proceeds to step S16.

  In step S16, converter control unit 48 determines whether or not the difference between lower arm maximum temperature Tal_max and detected temperature Twl exceeds lower arm threshold temperature THal_tem. When the difference is equal to or lower than the lower arm threshold temperature THal_tem (S16: No), the current process is terminated. When the difference is larger than the lower arm threshold temperature THal_tem (S16: Yes), in step S17, converter control unit 48 starts detecting the gate disconnection abnormality of lower arm switching element 82w. That is, the flag FLGwl related to the lower arm switching element 82w is set to “1”. After step S17, the current process is terminated.

  FIG. 6 shows a flowchart of the abnormality detection process (S5 in FIG. 4) of the upper arm element of each phase. Steps S21 to S27 in FIG. 6 are the same as steps S11 to S17 in FIG. In FIG. 6, instead of “lower arm maximum temperature Tal_max”, “lower arm threshold temperature THal_tem” and “flags FLGul, FLGvl, FLGwl” in FIG. 5, “upper arm maximum temperature Tah_max”, “upper arm threshold temperature THah_tem”. And “flags FLGuh, FLGvh, FLGwh” are used.

  FIG. 7 shows a flowchart of the U-phase abnormality confirmation process (S6 in FIG. 4).

  In step S31, converter control unit 48 determines whether or not a U-phase gate disconnection abnormality has been established. Specifically, it is determined whether or not the flag FLGu regarding the U phase is “1”. The flag FLGu indicates whether or not the U-phase gate disconnection abnormality has been confirmed. When the flag FLGu is “0”, the U-phase gate disconnection abnormality has not been confirmed. When the flag FLGu is “1”, Indicates that the U-phase gate disconnection abnormality has been confirmed. The initial value of the flag FLGu is “0”. When the U-phase gate disconnection abnormality has not been determined (S31: No), the process proceeds to step S32. If the U-phase gate disconnection abnormality is confirmed (S31: Yes), the current process is terminated.

  In step S32, converter control unit 48 determines whether an abnormal gate disconnection is detected in any of the upper arm element and the lower arm element of the U phase. Specifically, the U-phase lower arm element flag FLGul based on steps S12 and S13 in FIG. 5 and the U-phase upper arm element flag FLGuh based on steps S22 and S23 in FIG. 6 are both “0”. Determine if it exists.

  When the flags FLGuh and FLGul are both “0” (S32: Yes), no gate disconnection abnormality is detected in either the upper arm element or the lower arm element of the U phase. Therefore, in step S33, converter control unit 48 resets the value of U-phase counter CNTu (CNTu ← 0). The value of the U-phase counter CNTu indicates the time during which the gate disconnection abnormality of the upper arm element or the lower arm element of the U phase continues.

  In step S32, when the flag FLGuh or the flag FLGul is “1” (S32: No), a gate disconnection abnormality is detected in the upper arm element or the lower arm element of the U phase. Therefore, in step S34, converter control unit 48 increases the value of U-phase counter CNTu by one.

  In subsequent step S35, converter control unit 48 determines whether or not U-phase counter CNTu is equal to or longer than a threshold time for determining U-phase gate disconnection abnormality (disconnection determination threshold time THu_time) [s]. When the U-phase counter CNTu is less than the disconnection determination threshold time THu_time (S35: No), the converter control unit 48 ends the current process without determining the U-phase gate disconnection abnormality. When the U-phase counter CNTu is equal to or longer than the disconnection determination threshold time THu_time (S35: Yes), in step S36, the converter control unit 48 determines the U-phase gate disconnection abnormality and sets the flag FLGu to “1”. . When this process is completed, the process returns to step S31.

  FIG. 8 shows a flowchart of the V-phase abnormality confirmation process (S7 in FIG. 4). FIG. 9 shows a flowchart of the W-phase abnormality confirmation process (S8 in FIG. 4). Steps S41 to S46 in FIG. 8 and steps S51 to S56 in FIG. 9 are the same as steps S31 to S36 in FIG. In addition, instead of “flag FLGu”, “U-phase counter CNTu” and “disconnection determination threshold time THu_time” in FIG. 7, “flag FLGv”, “V-phase counter CNTv” and “disconnection determination threshold time THv_time” in FIG. In FIG. 9, “flag FLGw”, “W-phase counter CNTw”, and “disconnection determination threshold time THw_time” are used.

  FIG. 10 is a flowchart for controlling the output of the DC / DC converter 20 using the flags FLGu, FLGv, and FLGw specified in the processes of FIGS.

  In step S61, converter control unit 48 determines whether flags FLGu, FLGv, and FLGw are each “0”.

  When all of the flags FLGu, FLGv, and FLGw are “0” (S61: Yes), no gate disconnection abnormality is determined in any phase. Therefore, in step S62, the converter control unit 48 outputs drive signals to all the phase arms in order, and performs normal output by switching all the phase arms in order. On the other hand, when any of the flags FLGu, FLGv, and FLGw is “1” (S61: No), the gate disconnection abnormality is confirmed in any of the phase arms. In view of this, a process associated with the determination of the gate disconnection abnormality is performed after step S63.

  In step S63, converter control unit 48 determines whether or not the condition that flag FLGu is “1” and flags FLGv and FLGw are “0” is satisfied. When the condition is satisfied (S63: Yes), the gate disconnection abnormality is confirmed in the U-phase arm UA. Therefore, in step S64, converter control unit 48 alternately outputs a high-level drive signal to the remaining V-phase arm VA and W-phase arm WA to replace V-phase arm VA and W-phase arm WA. Switch. At that time, the converter control unit 48 limits the output of the DC / DC converter 20 to 2/3 of the normal output. Thereby, the heat generation in the V-phase arm VA and the W-phase arm WA can be suppressed to a level equivalent to that during normal output. In FIG. 11, when operating with the step-down chopper control, the gate disconnection abnormality is confirmed in the U-phase arm UA, and at time t1, the operation is switched from the normal operation (three-phase arm replacement drive operation) to the operation at the time of abnormality detection. A time chart is shown.

  Returning to FIG. 10, in step S63, when the condition that the flag FLGu is “1” and the flags FLGv and FLGw are “0” is not satisfied (S63: No), the process proceeds to step S65.

  In step S65, converter control unit 48 determines whether or not the condition that flag FLGv is “1” and flags FLGu and FLGw are “0” is satisfied. When the condition is satisfied (S65: Yes), the gate disconnection abnormality is confirmed in the V-phase arm VA. Therefore, in step S66, converter control unit 48 alternately outputs a high level drive signal to the remaining U-phase arm UA and W-phase arm WA to replace U-phase arm UA and W-phase arm WA. Switch. At that time, the converter control unit 48 limits the output of the DC / DC converter 20 to 2/3 of the normal output. Thereby, the heat generation in the U-phase arm UA and the W-phase arm WA can be suppressed to the same level as that during normal output.

  In step S65, when the condition that the flag FLGv is “1” and the flags FLGu and FLGw are “0” is not satisfied (S65: No), the process proceeds to step S67.

  In step S67, converter control unit 48 determines whether or not the condition that flag FLGw is “1” and flags FLGu and FLGv are “0” is satisfied. When the condition is satisfied (S67: Yes), the gate disconnection abnormality is confirmed in the W-phase arm WA. Therefore, in step S68, converter control unit 48 alternately outputs a high-level drive signal to the remaining U-phase arm UA and V-phase arm VA to replace U-phase arm UA and V-phase arm VA. Switch. At that time, the converter control unit 48 limits the output of the DC / DC converter 20 to 2/3 of the normal output. Thereby, the heat generation in the U-phase arm UA and the V-phase arm VA can be suppressed to the same level as that during normal output.

  In step S67, when the condition that the flag FLGw is “1” and the flags FLGu and FLGv are “0” is not satisfied (S67: No), the gate disconnection abnormality is determined in two or more phase arms. ing. Therefore, in step S69, converter control unit 48 stops the control of DC / DC converter 20.

[Effect of this embodiment]
As described above, according to the present embodiment, an abnormality in the switching operation can be detected based on the detected temperatures Tuh, Tvh, Twh, Tul, Tvl, and Twl. As a result, it is possible to diversify the method for detecting an abnormality in the switching operation. In particular, when the temperature sensor 69 is provided to determine whether the upper arm switching elements 81u to 81w and the lower arm switching elements 82u to 82w are overheated, the temperature sensor 69 is replaced with the upper arm switching elements 81u to 81w and the lower arm switching elements. By using it for the abnormality detection of 82u-82w, size reduction and cost reduction of the whole DC / DC converter device 50 can be achieved.

  Further, when any one of the upper arm switching elements 81u to 81w and the lower arm switching elements 82u to 82w is detected, the remaining phase arms are switched and switched. Thereby, the difficulty of the transformation control by the switching element from which abnormality was detected not switching can be avoided. Furthermore, even when an abnormality occurs in the switching operation of any of the switching elements, it is possible to maintain the advantage (for example, excellent heat dissipation) of switching the phase arms by switching.

  In the present embodiment, the converter control unit 48 detects the gate disconnection abnormality of a specific phase arm, and when the remaining phase arm is switched and switched, the power passing through the DC / DC converter 20 is limited, and the phase control is performed. Limit arm switching. When the same power is supplied to the DC / DC converter 20 even though the number of usable phase arms is reduced due to the abnormal switching operation, the output per remaining phase arm is increased and the remaining phase arms are increased. The possibility that the arm is heated increases. However, according to the configuration of the present embodiment, the output per remaining phase arm can be suppressed, so that the possibility of such a temperature rise can be reduced.

  In the present embodiment, the upper arm maximum temperature Tah_max is determined from the detected temperatures Tuh, Tvh, Twh, and the upper arm switching in which the deviation between the detected temperatures Tuh, Tvh, Twh and the upper arm maximum temperature Tah_max exceeds the upper arm threshold temperature THah_tem. It is determined that an abnormality of the switching operation has occurred in the elements 81u, 81v, 81w. Similarly, the lower arm maximum temperature Tal_max is determined from the detected temperatures Tul, Tvl, Twl, and the lower arm switching element 82u in which the deviation between the detected temperatures Tul, Tvl, Twl and the lower arm maximum temperature Tal_max exceeds the lower arm threshold temperature THal_tem. , 82v, and 82w are determined to be abnormal in the switching operation. Thereby, abnormality of switching operation | movement can be determined by comparison with another switching element. Therefore, even when the detected temperature of the switching element changes depending on the usage state of the switching element, it is possible to determine the abnormality of the switching operation relatively easily.

C. Modifications It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the description in this specification. For example, the following configuration can be adopted.

[Target]
In the above embodiment, the DC / DC converter device 50 is mounted on the fuel cell vehicle 10, but is not limited thereto, and may be mounted on another target. For example, the DC / DC converter device 50 can be used for a moving body such as a ship or an aircraft. Alternatively, the DC / DC converter device 50 may be applied to a household power system.

[DC / DC converter]
In the above embodiment, the DC / DC converter 20 is a step-up / step-down type, but is not limited thereto, and may be a step-up type or a step-down type.

  In the above embodiment, the number of the upper arm switching elements 81u to 81w and the lower arm switching elements 82u to 82w is three, but the number is not limited to this, and may be four or more.

[Abnormal judgment]
In the above embodiment, the gate arm disconnection abnormality occurs in the lower arm switching elements 82u to 82w in which the deviation between the lower arm maximum temperature Tal_max and the detected temperatures Tul, Tvl, Twl of the lower arm switching elements 82u to 82w exceeds the lower arm threshold temperature THal_tem. However, the determination method of the gate disconnection abnormality is not limited to this. For example, when any of the detected temperatures Tuh, Tvh, Twh, Tul, Tvl, and Twl after a predetermined time has elapsed from the start of the operation of the DC / DC converter 20 is equal to or lower than a predetermined temperature threshold, the detected temperature is handled. It is also possible to determine that a gate disconnection abnormality has occurred in the switching element.

1 is a schematic overall configuration diagram of a fuel cell vehicle equipped with a DC / DC converter device according to an embodiment of the present invention. It is a circuit diagram which shows the detailed structure of the DC / DC converter which concerns on this embodiment. It is a time chart used for description of a three-phase arm replacement drive operation. It is a flowchart which detects the gate disconnection abnormality of each phase. It is a flowchart of the abnormality detection process of the lower arm element of each phase. It is a flowchart of the abnormality detection process of the upper arm element of each phase. It is a flowchart of the abnormality confirmation process of a U phase. It is a flowchart of the abnormality confirmation process of V phase. It is a flowchart of the abnormality confirmation process of W phase. It is a flowchart which controls the output of a DC / DC converter using the flag specified by the process of FIGS. 7 is a time chart in which a gate disconnection abnormality is determined for the U-phase arm and the operation is switched from a normal operation (three-phase arm replacement drive operation) to an abnormality detection operation when operating with the step-down chopper control.

Explanation of symbols

20 ... DC / DC converter 48 ... Converter control unit (control unit, abnormality detection unit)
DESCRIPTION OF SYMBOLS 50 ... DC / DC converter apparatus 69 ... Temperature sensor 81, 81u, 81v, 81w ... Upper arm switching element 82, 82u, 82v, 82w ... Lower arm switching element Tuh, Tvh, Twh, Tul, Tvl, Twl ... Detection temperature Tah_max ... Upper arm maximum temperature Tal_max ... Lower arm maximum temperature THah_tem ... Upper arm threshold temperature THal_tem ... Lower arm threshold temperature
UA ... U phase arm VA ... V phase arm WA ... W phase arm UH, UL, VH, VL, WH, WL ... Drive signal 1S ... Primary side 2S ... Secondary side

Claims (3)

A DC / DC converter device in which a plurality of phase arms having switching elements are connected in parallel between a primary side and a secondary side,
A control unit that switches and switches the plurality of phase arms according to a drive signal;
A temperature sensor for detecting an element temperature of the switching element;
An anomaly detector that detects an anomaly in the switching operation of the switching element based on the detected element temperature;
When the abnormality detection unit detects an abnormality in the switching operation of the switching element, the control unit stops the phase arm having the switching element that has detected the abnormality, and switches the remaining phase arm to perform switching. DC / DC converter device. The DC / DC converter device according to claim 1, wherein
The control unit restricts power passing through the DC / DC converter device when the remaining phase arms are switched and switched. The DC / DC converter device. The DC / DC converter device according to claim 1 or 2,
The control unit determines the maximum temperature from the element temperature of each switching element, and the switching element has an error in switching operation in which a deviation from the maximum temperature exceeds a deviation threshold set in advance to determine an abnormality in the switching operation. A DC / DC converter device characterized in that it is determined that an error has occurred.

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