JP2017103949A - Power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply system including: a fuse for separating a step-up switching element from a circuit when the element is shorted; and a mechanism for melting down the fuse using a voltage converter, reading for the event of the fuse not melting down at a shorting.SOLUTION: A power supply system 2 includes a first voltage converter 10 that has a low-voltage terminal 3 and a high-voltage terminal 4 respectively connected to a main battery 12 and an inverter 14a. A second voltage converter 21 has a low-voltage terminal and a high-voltage terminal respectively connected to a sub-battery 25 and the first voltage converter 10. The first voltage converter 10 includes a fuse 19 that is serially connected to a step-up switching element 7b. In a case where the fuse 19 is not melted down when a shorting failure occurs to the step-up switching element 7b, a controller 11 activates a second voltage converter 21 to supply the first voltage converter 10 with power of the sub-battery 25, thus melting down the fuse 19.SELECTED DRAWING: Figure 1

Description

  The technology disclosed in this specification relates to a power supply system suitable for an automobile including a traveling motor. Typical examples of automobiles equipped with a traveling motor are electric cars, hybrid cars, fuel cell cars, and the like.

  The electric vehicle described in Patent Document 1 includes a power supply system including a battery and a boost converter. The boost converter boosts the electric power of the battery and supplies the electric power to the inverter of the traveling motor. The step-up converter has a step-up switching element connected between the positive and negative electrodes at its high voltage end, one end connected to the high potential side of the step-up switching element, and the other end connected to the positive end at the low voltage end. A reactor, a capacitor connected between a positive electrode and a negative electrode at a low voltage end, and a circuit breaker connected in series with the step-up switching element. The controller of the boost converter activates the circuit breaker and disconnects the boost switching element from the circuit when a short circuit failure of the boost switching element is detected. By disconnecting the step-up switching element and eliminating the short circuit, the voltage converter can supply the battery power to the inverter even if it cannot perform the step-up operation, and can continue running. In Patent Document 1, an explosive type circuit breaker is recommended. The explosive circuit breaker has a quick response and can reliably disconnect the step-up switching element.

JP 2014-54102 A

  Explosive-type circuit breakers or high-performance circuit breakers using solenoids or mechanical relays are expensive. In order to reduce the cost of the power supply system, it is preferable to use an inexpensive thermal fusing type fuse instead of the circuit breaker. However, compared with a high-performance circuit breaker, the fuse is inferior in reliability and may not be quickly blown when a short circuit occurs. Incidentally, a power supply system for an electric vehicle may be equipped with a battery (sub battery) for a low voltage device (auxiliary machine) in addition to a battery (main battery) for a driving motor. In that case, the power supply system involves another voltage converter that steps down the power of the main battery and charges the sub-battery. The present specification includes a fuse for disconnecting a boost switching element from a circuit, and a mechanism for forcibly blowing a fuse using another voltage converter in preparation for a case where the fuse is not blown at the time of a short circuit failure of the boost switching element A power supply system including

  The power supply system disclosed in this specification is a device suitable for an automobile including a driving motor. The power supply system includes a main power supply that outputs DC power, a sub-power supply that outputs DC power having a voltage lower than that of the main power supply, a first voltage converter, a second voltage converter, and a controller. The first voltage converter corresponds to the boost converter described above. Hereinafter, for convenience of explanation, the low voltage end and the high voltage end of the first voltage converter are referred to as the first low voltage end and the first high voltage end, respectively, and the low voltage end and the high voltage end of the second voltage converter are referred to as the first low voltage end and the first high voltage end, respectively. These are referred to as a second low voltage end and a second high voltage end, respectively. The first voltage converter has a first low-voltage end connected to the main power supply, and a first high-voltage end connected to an inverter that drives the traveling motor, and boosts the power of the main power supply and supplies it to the inverter To do. The second voltage converter has a second low voltage end connected to the sub power supply, a second high voltage end connected to the first low voltage end or the first high voltage end, and boosts the power of the sub power supply. To the first voltage converter. The second voltage converter may have a step-down function for stepping down the power of the main power source and outputting it to the second low voltage end. The first voltage converter includes a step-up switching element, a reactor, a capacitor, and a fuse. The step-up switching element is connected between the positive electrode and the negative electrode at the first high voltage end. One end of the reactor is connected to the high potential side of the step-up switching element, and the other end is connected to the positive electrode of the first low voltage end. The capacitor is connected between the positive electrode and the negative electrode at the first low voltage end. The fuse is connected in series with the step-up switching element. The fuse has a specification that blows when an overcurrent flows due to a short circuit of the step-up switching element, but may not blow due to a malfunction. Therefore, when the fuse is not blown, the controller activates the second voltage converter, applies the fuse voltage (flows current), and blows the fuse. An example of determining whether or not the fuse has blown will be described in the section of the embodiment.

  The above power supply system employs an inexpensive fuse and has means for forcibly blowing the fuse if the fuse is not blown when the boost switching element is short-circuited. Make up. Details and further improvements of the technology disclosed in this specification will be described in detail in the section of Detailed Description.

It is a block diagram of the electric system of the hybrid vehicle containing the power supply system of an Example. It is a skeleton figure of a power split mechanism. It is a flowchart of the process at the time of a short circuit failure (short circuit countermeasure process). It is a block diagram of the electric system of the hybrid vehicle containing the power supply system of a 1st modification. It is a block diagram of the electric system of the hybrid vehicle containing the power supply system of a 2nd modification. It is a block diagram of the electric system of the hybrid vehicle containing the power supply system of a 3rd modification.

  A power supply system according to an embodiment will be described with reference to the drawings. The power supply system of the embodiment is applied to a hybrid vehicle. FIG. 1 shows a block diagram of an electric system of a hybrid vehicle 100 including the power supply system 2 of the embodiment. The hybrid vehicle 100 includes an engine 16 and two motors (a first motor 15a and a second motor 15b) for traveling. The first motor 15a mainly performs power generation and engine cranking. The first motor 15a does not directly output the driving force of the vehicle, but contributes to transmitting a part of the engine torque to the axle in the power split mechanism 30 described later. Therefore, the first motor 15a is also regarded as a traveling motor. In the technical field of electric vehicles and hybrid vehicles, a motor that contributes to the driving torque of the vehicle often serves as a generator. Although the first motor 15a and the second motor 15b of the present embodiment may generate electric power, they are also referred to as “motors” including the function of generating electric power in this specification.

  The power supply system 2 according to the embodiment includes a main battery 12, a sub battery 25, a system main relay 13, a first voltage converter 10, a second voltage converter 21, and a controller 11. The power supply system 2 supplies power to the inverter 14a that drives the motor 15a and the inverter 14b that drives the motor 15b, and also supplies power to the auxiliary machine 26. The auxiliary machine 26 is a generic name for devices that operate at a low voltage, such as room lamps and car audio. The power supply system 2 will be described in detail later.

  The output torque of the engine 16 and the output torque of the first motor 15a and the second motor 15b are appropriately divided and combined by the power split mechanism 30. Here, the power split mechanism 30 will be described with reference to FIG.

  FIG. 2 is a skeleton diagram of the power split mechanism 30. The power split mechanism 30 is a gear set having a planetary gear 31 as a main component. The sun gear 31a of the planetary gear 31 is engaged with the first motor 15a, the carrier 31b is engaged with the engine 16, and the ring gear 31c is engaged with the axle 17 via the idle gear 32. A differential gear 34 is connected to the tip of the axle 17 and a driving wheel 35 is attached to the tip of the differential gear 34. A second motor 15 b is engaged with the axle 17 via a reduction gear 33. Note that another gear may be interposed between the sun gear 31a and the first motor 15a, or between the engine 16 and the carrier 31b. A gear different from the reduction gear 33 may be interposed between the second motor 15 b and the axle 17.

  The hybrid vehicle 100 stops the engine 16 and travels by the second motor 15b at the time of start-up and in a vehicle speed range where the engine efficiency is low in the middle / low speed range. The engine 16 is operated in a vehicle speed range where the engine efficiency is high in the middle and high speed range. When traveling by the engine 16, the first motor 15a supports the reaction force that appears in the sun gear 31a so that the engine torque is transmitted to the ring gear 31c connected to the axle 17. At this time, the first motor 15a generates power with a reaction force that appears in the sun gear 31a. The second motor 15b is driven with the electric power obtained by the power generation to assist the driving force of the vehicle. The torque of the first motor 15a that supports the reaction force that appears in the sun gear 31a is referred to as negative torque.

  If the sun gear 31a is unloaded, due to the characteristics of the planetary gear 31, the engine speed increases without torque being transmitted to the ring gear 31c. That is, the engine blows up. The first motor 15a applies a negative torque opposite to the output torque of the engine 16 to suppress the engine blow-up and transmit a part of the engine torque to the ring gear 31c (that is, the axle 17). To assist.

  The negative torque provided by the first motor 15a means that the first motor 15a is driven from the output shaft side, and the first motor 15a is rotated by negative torque (that is, torque driven from the output shaft side) to generate electric power. The magnitude of the negative torque of the first motor 15a depends on the electromotive force of the first motor 15a, and the electromotive force is adjusted by the switching operation of the first inverter 14a. The first motor 15 a is also used for cranking the engine 16. The positive torque output from the first motor 15a is also adjusted by the first inverter 14a. In other words, whether the first motor 15a outputs a positive torque or a negative torque is controlled by the first inverter 14a.

  Even when the engine 16 is stopped and the second motor 15b travels, the first motor 15a is rotated by a part of the output torque of the second motor 15b due to the characteristics of the power split mechanism 30 (particularly the planetary gear 31) of FIG. And generate electricity. The electric power obtained by the power generation of the first motor 15a is used to drive the second motor 15b.

  The hybrid vehicle 100 operates the engine 16 when a large acceleration force is required, and also uses the power of the main battery 12 to increase the output of the second motor 15b. When the brake pedal is depressed, the hybrid vehicle 100 stops the engine 16 and generates power by the first motor 15a and the second motor 15b that are reversely driven by the inertia force of the vehicle. The electric power obtained by power generation is used for charging the main battery 12 and driving the auxiliary machine 26 (see FIG. 1).

  The output torque of the second motor 15b is adjusted by the second inverter 14b. As described above, when the brake pedal is depressed, the second motor 15b also generates power. The generated power of the second motor 15b depends on the electromotive force of the second motor 15b, and the electromotive force is adjusted by the switching operation of the second inverter 14b. That is, the second motor 15b is also controlled by the second inverter 14b regardless of the positive torque output and the negative torque output.

  As described above, the first motor 15 a and the second motor 15 b rotate in conjunction with the engine 16 via the planetary gear 31. Both motors contribute mechanically and electrically to obtaining the driving torque of the vehicle. Therefore, as described above, both the first motor 15a and the second motor 15b are called traveling motors. In the following, traveling using mainly the engine 16 without using the power of the main battery 12 is referred to as battery-less traveling. In battery-less travel, the main battery 12 is not used, but the second motor 15b may be driven using regenerative power from the first motor 15a to assist the propulsive force of the vehicle.

  Returning to FIG. 1, the description returns to the electric system of the hybrid vehicle 100. The hybrid vehicle 100 includes a first inverter 14a, a second inverter 14b, a power supply system 2, and an auxiliary machine 26. The power supply system 2 includes a main battery 12, a sub battery 25, a system main relay 13, a first voltage converter 10, a second voltage converter 21, and the like. The first voltage converter 10 boosts the voltage of the main battery 12 and supplies it to the first and second inverters 14a and 14b, and reduces the regenerative power output from the first and second inverters 14a and 14b. It has both a step-down function for supplying to the main battery 12. That is, the first voltage converter 10 is a bidirectional DC-DC converter. The low voltage end 3 of the first voltage converter 10 is connected to the main battery 12 via the system main relay 13. The high voltage terminal 4 of the first voltage converter 10 is connected to the first and second inverters 14a and 14b. The first inverter 14a supplies AC power to the first motor 15a. The second inverter 14b supplies AC power to the second motor 15b.

  A second voltage converter 21 is further connected to the low voltage end 3 of the first voltage converter 10. The second voltage converter 21 is also a bidirectional DC-DC converter. For convenience of explanation, the low voltage end and the high voltage end of the first voltage converter 10 are referred to as a first low voltage end 3 and a first high voltage end 4, respectively, and the low voltage end and the high voltage end of the second voltage converter 21 are respectively referred to as a first low voltage end 3 and a first high voltage end 4. The second low voltage end 24 and the second high voltage end 23 are referred to. The low voltage end (second low voltage end 24) of the second voltage converter 21 is connected to the sub-battery 25 (and auxiliary machine 26), and the high voltage end (second high voltage end 23) is connected to the first voltage converter 10. Is connected to the first low-voltage end 3 of the circuit. Note that the negative electrode of the low voltage end (second low voltage end 24) of the second voltage converter 21 is connected to the negative electrode of the sub-battery 25 via the body ground G. The negative electrode of the auxiliary machine 26 is also connected to the negative electrode of the sub battery 25 via the body ground G.

  The output voltage of the main battery 12 is about 300 volts, and the output voltage of the sub battery 25 is about 12 volts. That is, the sub battery 25 outputs DC power having a lower voltage than the main battery 12. The main battery 12 is, for example, a lithium ion battery, and the sub battery 25 is, for example, a lead battery. Both batteries are rechargeable batteries that can be charged. The sub battery 25 may be a capacitor. The electric power of the main battery 12 is mainly used for driving the first and second motors 15a and 15b, and the electric power of the sub battery 25 is mainly used for driving the auxiliary machine 26.

  The first voltage converter 10 boosts the output voltage of the main battery 12 to a voltage required by the first and second inverters 14a and 14b (that is, the first and second motors 15a and 15b). The boosted voltage is about 600 volts, for example. The second voltage converter 21 steps down the output power of the main battery 12 to about 12 volts and supplies it to the sub battery 25 and the auxiliary machine 26.

  The second voltage converter 21 can also boost the power of about 12 volts of the sub-battery 25 and output it to the second high voltage terminal 23 (first low voltage terminal 3). The second voltage converter 21 boosts the power of the sub battery 25 and supplies it to the first voltage converter 10 when the main battery 12 cannot be used. When the main battery 12 cannot be used and the engine 16 is also stopped, the second voltage converter 21, the first voltage converter 10, and the first inverter 14a are operated, and the first motor 15a is driven by the power of the sub battery 25. Crank the engine 16. When the engine 16 is started, battery-less travel is possible.

  A circuit of the first voltage converter 10 will be described. The first voltage converter 10 includes two switching elements 7a and 7b, two diodes 8a and 8b, a filter capacitor 5, a current sensor 28, a voltage sensor 29, and a reactor 6. The two switching elements 7 a and 7 b are connected in series between the positive electrode 4 a and the negative electrode 4 b at the high voltage end (first high voltage end 4) of the first voltage converter 10. Since the switching element 7a located on the high potential side of the series connection is mainly involved in stepping down, it may be referred to as step-down switching element 7a. Since the switching element 7b located on the low potential side of the series connection is mainly involved in boosting, it may be referred to as the boosting switching element 7b. When both of the two switching elements are shown, they are called switching elements 7a and 7b. The two switching elements 7a and 7b are, for example, insulated gate bipolar transistors (IGBT). The two diodes 8a and 8b are respectively connected in antiparallel to the switching elements 7a and 7b. The diodes 8a and 8b are also called free-wheeling diodes. The diode 8a is mainly involved in boosting, and the diode 8b is mainly involved in stepping down.

  One end of the reactor 6 is connected to the midpoint of the series connection of the two switching elements 7 a and 7 b, and the other end is connected to the positive electrode 3 a of the first low voltage end 3. The filter capacitor 5 is connected between the positive electrode 3 a and the negative electrode 3 b of the first low voltage end 3. The negative electrode 3 b of the first low voltage end 3 is directly connected to the negative electrode 4 b of the first high voltage end 4. The voltage sensor 29 is connected between the positive electrode 3 a and the negative electrode 3 b of the first low voltage end 3. The current sensor 28 measures the current flowing through the reactor 6. The voltage sensor 29 measures the voltage between the positive electrode 3 a and the negative electrode 3 b of the first low voltage terminal 3, that is, the voltage of the electric power supplied from the main battery 12. The measurement results of the current sensor 28 and the voltage sensor 29 are transmitted to the controller 11.

  The circuit configuration of the first voltage converter 10 can be stated differently as follows. The step-up switching element 7 b is connected between the positive electrode 4 a and the negative electrode 4 b of the first high voltage end 4. The reactor 6 has one end connected to the high potential side of the step-up switching element 7 b and the other end connected to the positive electrode 3 a of the first low voltage end 3. The filter capacitor 5 is connected between the positive electrode 3 a and the negative electrode 3 b of the first low voltage end 3. The step-down switching element 7 a is connected between a connection point between the step-up switching element 7 b and the reactor 6 and the positive electrode 4 a of the first high voltage end 4. Diodes 8a and 8b are connected to the switching elements 7a and 7b, respectively. A fuse 19 is connected in series with the step-up switching element 7b. The fuse 19 will be described later.

  A smoothing capacitor 9 is connected between the positive electrode 4 a and the negative electrode 4 b of the first high voltage terminal 4 of the first voltage converter 10. The smoothing capacitor 9 is inserted to suppress pulsation of current supplied from the first voltage converter 10 to the first and second inverters 14a and 14b.

  As described above, the first voltage converter 10 is a bidirectional DC-DC converter. The first voltage converter 10, the first and second inverters 14 a and 14 b, and the second voltage converter 21 are controlled by the controller 11. The symbols CMD_d1 and CMD_d2 in FIG. 1 mean command signals to the first and second voltage converters 10 and 21, respectively. Symbols CMD_i1 and CMD_i2 in FIG. 1 mean command signals to the first and second inverters 14a and 14b, respectively. Symbol CMD_r means a command signal to the system main relay 13. That is, the controller 11 also controls opening and closing of the system main relay 13. When the vehicle main switch is turned on, the controller 11 closes the system main relay 13 and electrically connects the main battery 12 and the first voltage converter 10.

  The controller 11 determines the torque (requested torque) that the vehicle should output from information on the accelerator pedal and the brake pedal, the speed, the remaining amount of the main battery 12, the remaining amount of engine fuel, and the like, and sends the requested torque to the engine and motor. Also determine the distribution. Then, the controller 11 controls the first and second voltage converters 10, 21, and 1st according to the torque to be output by the first and second motors 15 a and 15 b and the power to be supplied to the sub-battery 25. Then, an appropriate command is sent to the second inverters 14a and 14b.

  The power supply system 2 includes two fuses (fuse 18 and fuse 19). The fuse 18 is provided between the main battery 12 and the system main relay 13. The fuse 19 is connected in series with the step-up switching element 7b. Both fuses are of the thermal fusing type. The fuse 18 is provided to protect electronic devices such as the first voltage converter 10 when a failure such as a short circuit occurs in the main battery 12.

  The fuse 19 is provided to disconnect the boost switching element 7b and the diode 8b from the circuit when the boost switching element 7b or the diode 8b causes a short circuit failure. When the step-up switching element 7b or the diode 8b is short-circuited, the first voltage converter 10 cannot perform step-up or step-down. However, if the short circuit between the positive electrode 3a and the negative electrode 3b of the first low voltage terminal 3 (between the positive electrode 4a and the negative electrode 4b of the first high voltage terminal 4) of the first voltage converter 10 is resolved, the power of the main battery 12 is restored. Can be supplied to the inverters 14a and 14b without changing the output voltage. That is, the first and second motors 15a and 15b can be driven by the power of the main battery 12 to continue running. Alternatively, when the engine 16 is stopped, if the first voltage converter 10 loses the step-up function and the step-down function and the positive electrode and the negative electrode are not short-circuited, the second voltage converter 21 is used. The first motor 15a can be driven by electric power, and the engine 16 can be cranked. Alternatively, if the engine 16 is stopped, the second voltage converter 21 and the first inverter 14a are connected if the positive and negative electrodes are not short-circuited even if the first voltage converter 10 loses the step-up function and the step-down function. It is possible to drive the first motor 15a with the electric power of the sub battery 25 and crank the engine 16. If the engine 16 is started, battery-less traveling can be continued.

  As described above, the power supply system 2 can supply predetermined power to the first high-voltage end 4 by blowing the fuse 19 even if one of the step-up switching element 7b and the diode 8b causes a short circuit failure. However, as described above, the fuse 19 is a thermal fusing type, and is lower in cost than a gunpowder type breaker or the like, but is not highly reliable. If the fuse 19 is not blown when the step-up switching element 7b or the diode 8b is short-circuited, traveling cannot be continued.

  Therefore, in the unlikely event that the fuse 19 does not blow, the power supply system 2 uses the second voltage converter 21 to increase the voltage across the fuse 19 with the power of the sub-battery 25 and forcibly blows the fuse 19. Next, the process at the time of short circuit including the forced fusing of the fuse 19 is demonstrated with reference to the flowchart of FIG.

  FIG. 3 is a flowchart of countermeasure processing (short circuit countermeasure processing) when a short circuit failure is detected in the first voltage converter 10. The controller 11 executes the process of FIG. The controller 11 includes a voltage sensor 29 that measures the voltage across the first low voltage terminal 3, and if the measured value of the voltage sensor 29 falls below a predetermined threshold value close to zero, a short circuit failure occurs in the boost switching element 7b or the diode 8b. As a result, the processing of FIG. 3 is started. In FIG. 3, the symbol “SMR” means the system main relay 13, and “DDC2” means the second voltage converter 21. Further, the symbol “VL” means a voltage between the positive electrode 3 a and the negative electrode 3 b at the low voltage end (first low voltage end 3) of the first voltage converter 10. The symbol “Vth” means a predetermined voltage value (breakage determination threshold voltage) close to zero.

  In addition to the short circuit failure of the boost switching element 7b or the diode 8b, the measured value of the voltage sensor 29 falls below a predetermined threshold value, for example, when the filter capacitor 5 has a short circuit failure. The filter capacitor 5 short-circuit failure detection is performed by another process. For example, the controller 11 determines whether the filter capacitor 5 is short-circuited using information on both the measured value of the voltage sensor 29 and the measured value of the current sensor 28. This specification will focus on the processing at the time of a short-circuit failure of the step-up switching element 7b or the diode 8b.

  When a short circuit is detected, the controller 11 first opens the system main relay 13 and disconnects the main battery 12 from the first voltage converter 10 (S2). This is to prevent the main battery 12 from being affected by the short circuit of the first voltage converter 10. Specifically, the fuse 18 is prevented from being blown and the main battery 12 is prevented from being overdischarged.

  Next, the controller 11 checks whether or not the engine 16 is stopped (S3). When the engine 16 is not stopped (S3: NO), that is, when the engine 16 is operating, the controller 11 turns off the step-down switching element 7a and turns the first voltage converter 10 into the first inverter 14a (second inverter 14b). (S12). Then, the controller 11 sets the travel mode to the batteryless travel mode (S10). As described above, the battery-less traveling mode is a mode in which traveling is performed mainly using the engine 16 without using the power of the main battery 12.

  On the other hand, when the engine 16 is stopped in step S3 (S3: YES), the controller 11 starts a boost operation by the second voltage converter 21 (S4). When the second voltage converter 21 starts a boost operation, power is supplied between the second high voltage end 23 of the second voltage converter 21, that is, the low voltage end 3 of the first voltage converter 10.

  When the step-up switching element 7b or the diode 8b is short-circuited, normally, before the system main relay 13 is opened in step S2, an overcurrent flows through the fuse 19 and the fuse 19 is blown. If the fuse 19 is blown, the short circuit of the first voltage converter 10 is eliminated. If the fuse 19 is blown, when the step-up operation of the second voltage converter 21 is started in step S4, the first voltage is generated by the power output from the high voltage end (second high voltage end 23) of the second voltage converter 21. The voltage VL between the positive electrode 3a and the negative electrode 3b at the low voltage end 3 increases. If the voltage VL rises above a predetermined voltage (breakage determination threshold voltage Vth), it can be determined that the fuse 19 is blown (S5: YES). On the other hand, if the voltage VL does not exceed the rupture determination threshold voltage Vth (S5: NO), it can be determined that the fuse 19 is not normally blown and remains connected. A value close to zero is set for the breakage determination threshold voltage Vth. Although not shown, a wait time of several seconds is set to wait for the voltage VL to rise when the fuse 19 is not blown after the process of step S4.

  When the fuse 19 is not blown, that is, when the voltage VL does not exceed the breakage determination threshold voltage Vth even when the second voltage converter 21 starts the boosting operation (S5: NO), the controller 11 The output of the converter 21 is increased (S6). That is, a further voltage is applied across the fuse 19. The controller 11 increases the output of the second voltage converter 21 until the fuse 19 is blown, that is, until the determination in step S5 becomes “YES” (S5: NO, S6). If the fuse 19 is blown while repeating the loop of steps S5 and S6, the determination in step S5 is “YES”. If the fuse 19 is appropriately blown when either the step-up switching element 7b or the diode 8b is short-circuited, the determination is “YES” in the process of step S5 following the process of step S4. Become.

  When the determination in step S5 is “YES”, the controller 11 adjusts the output of the second voltage converter 21 so that the electric power sufficient for the motor 15a to crank the engine 16 is supplied to the first inverter 14a. (S7). When the output voltage of the second voltage converter 21 reaches an appropriate value for cranking, the controller 11 operates the first inverter 14a, that is, drives the first motor 15a and cranks the engine 16 (S8). When the engine 16 is started, the controller 11 stops the second voltage converter 21 (S9). Then, the controller 11 sets the travel mode to the batteryless travel mode, and ends the process (S10). The batteryless driving mode is as described above.

  The process of the flowchart of FIG. 3, particularly steps S <b> 5 and S <b> 6, correspond to the process of forcibly blowing the fuse 19. By including the processing of FIG. 3 including steps S5 and S6, the power supply system 2 forces the fuse 19 using the sub battery 25 and the second voltage converter 21 when the cheap fuse 19 does not normally blow out. Can be melted. That is, the power supply system 2 can reliably disconnect the step-up switching element 7b and the diode 8b from the circuit when one of the step-up switching element 7b and the diode 8b causes a short circuit failure, and can continue running.

  Although illustration is omitted, a process is separately provided when the voltage VL reaches the upper limit value without the fuse 19 being blown even if the loop of steps S5 and S6 is repeated.

  A modified power supply system will be described. FIG. 4 shows a block diagram of a hybrid vehicle 100a including the power supply system 2a of the first modification. In the block diagram of FIG. 4, the same components as those in the block diagram of FIG. The description of the same components as those in the first block diagram is omitted.

  The power supply system 2a of the first modification is different from the power supply system 2 of the embodiment in the connection destination of the high voltage end (second high voltage end 23) of the second voltage converter 21. In the power supply system 2 of the embodiment, the second high voltage end 23 is connected to the low voltage end (first low voltage end 3) of the first voltage converter 10, but in the first modification, the first voltage converter 23 It is different in that it is connected to 10 high voltage terminals (first high voltage terminal 4). In the case of the power supply system 2a of FIG. 4, in the process of FIG. 3, a process of turning on (stepping down) the step-down switching element 7a is added before step S4. By turning on the step-down switching element 7a, a voltage can be applied from the first high voltage end 4 to both ends of the fuse 19. Except for the process of turning on the step-down switching element 7a, the process of FIG. 3 can be used as it is.

  FIG. 5 shows a block diagram of a hybrid vehicle 100b including the power supply system 2b of the second modified example. In the block diagram of FIG. 5, the same components as those in the block diagram of FIG. The description of the same components as those in the first block diagram is omitted.

  In the power supply system 2b of the second modification, a third voltage converter 41 is added to the power supply system 2 of FIG. The third voltage converter 41 is a voltage converter that can perform only a step-down operation. The high voltage end (third high voltage end 42) is connected to the main battery 12, and the low voltage end (third low voltage end 43) is Connected to the sub-battery 25. The third high voltage terminal 42 is connected to the main battery 12 on the main battery side with respect to the system main relay 13. Further, the negative electrode of the third low voltage end 43 is connected to the negative electrode of the sub battery 25 via the body ground G. The third voltage converter 41 is also controlled by the controller 11. A symbol CMD_d3 in FIG. 5 means a command signal from the controller 11 to the third voltage converter 41. Note that another fuse 45 is provided between the third high voltage terminal 42 and the main battery 12.

  As described above, the third voltage converter 41 is connected to the main battery 12 on the main battery side with respect to the system main relay 13. Therefore, the power supply system 2b can charge the sub battery 25 using the main battery 12 even when the system main relay 13 is opened. When the power supply system 2 b is employed, the controller 11 charges the sub battery 25 using the third voltage converter 41 while traveling with the engine 16 in the battery-less travel mode.

  5, the high voltage end (second high voltage end 23) of the second voltage converter 21 is connected to the high voltage end (first high voltage end 4) of the first voltage converter 10. Also good.

  FIG. 6 shows a block diagram of a hybrid vehicle 100c including the power supply system 2c of the third modified example. In the block diagram of FIG. 6, the same components as those in the block diagram of FIG. The description of the same components as those in the first block diagram is omitted.

  The power supply system 2c of the third modification includes a multi-input voltage converter 50 instead of the second voltage converter 21 of the power supply system 2 of FIG. The multi-input voltage converter 50 is a voltage converter that converts a voltage between three input / output terminals. The multi-input voltage converter 50 includes a transformer 51 having three coils 51a, 51b, 51c, and a first circuit 52a, a second circuit 52b, and a third circuit 52c associated with each coil. The input / output terminal (first input / output terminal 53a) of the first circuit 52a is connected to the low voltage terminal (first low voltage terminal 3) of the first voltage converter 10. The input / output terminal (second input / output terminal 53b) of the second circuit 52b is connected to the sub-battery 25. The input / output terminal (third input / output terminal 53 c) of the third circuit 52 c is connected to the main battery 12. The input / output terminal (third input / output terminal 53c) of the third circuit 52c is connected to the main battery 12 on the main battery side with respect to the system main relay 13. Note that another fuse 45 is provided between the third input / output terminal 53 c and the main battery 12.

  Each circuit converts the DC power applied to the input / output terminals into AC and flows it to the corresponding coil. Each circuit can also convert the induced current flowing in the corresponding coil into a direct current and output it to the input / output terminal. In the transformer 51, the number of turns of each coil is determined so that the voltage at the first input / output terminal 53a is the highest, the voltage at the third input / output terminal 53c is the next highest, and the voltage at the second input / output terminal 53b is the lowest. It has been. The multi-input voltage converter 50 can step down DC power supplied to the first input / output terminal 53a and output it to the second input / output terminal 53b. With this step-down operation, the sub-battery 25 can be charged with the regenerative power generated by the first motor 15a. The multi-input voltage converter 50 boosts the power supplied to the second input / output terminal 53b and / or the power supplied to the third input / output terminal 53c and outputs the boosted power to the first input / output terminal 53a. Can do. That is, the multi-input voltage converter 50 can convert the power of the sub-battery 25 or the power of the main battery 12 and supply it to the low voltage end (first low voltage end) of the first voltage converter 10. Therefore, the power supply system 2c of the third modified example can also execute the process of FIG. Similarly to the power supply system 2b of the second modification, the power supply system 2c of the third modification uses the main battery 12 by the multi-input voltage converter 50 while running on the engine 16 in the battery-less running mode. The sub battery 25 can be charged.

  In the case of the modification of FIG. 6, the first input / output terminal 53 a of the multi-input voltage converter 50 may be connected to the high voltage terminal (first high voltage terminal 4) of the first voltage converter 10.

  Points to be noted regarding the technology described in the embodiments will be described. When the determination in step S4 of the short circuit countermeasure process in FIG. 3 is NO, the fuse 19 is not forcibly cut. The technique disclosed in this specification is a mode in which the fuse 19 is not forcibly cut depending on other conditions even when a short circuit failure occurs in the step-up switching element 7b or the diode 8b and the fuse 19 is not cut. Including.

  The first voltage converter 10 may not have a step-down operation. For example, when a fuel cell is connected instead of the main battery 12, charging is not necessary, so that the step-down operation is unnecessary. In that case, the first voltage converter 10 does not require the step-down switching element 7a. Further, the diode 8b connected in antiparallel to the step-up switching element 7b is not required. The circuit configuration of the first voltage converter in that case is as follows. The first voltage converter includes a step-up switching element, a reactor, a capacitor, and a fuse. The step-up switching element is connected between the positive electrode and the negative electrode of the high voltage end (first high voltage end) of the first voltage converter. One end of the reactor is connected to the high potential side of the step-up switching element, and the other end is connected to the positive electrode of the low voltage end (first low voltage end) of the first voltage converter. The capacitor is connected between the positive electrode and the negative electrode at the first low voltage end. The fuse is connected in series with the step-up switching element. When the first voltage converter does not have a step-down function, the controller 11 activates the second voltage converter 21 when a short-circuit failure of the step-up switching element 7b is detected, and a voltage is applied to the fuse to blow the fuse. To do.

  In FIG. 1, the controller 11 is represented by one rectangle, but the function of the controller 11 in the embodiment may be realized by a plurality of processors in cooperation. In the power supply system of the embodiment, the fuse 19 is connected in series to the low potential side of the step-up switching element 7b. The fuse 19 may be connected in series to the high potential side of the step-up switching element 7b.

  The first inverter 14a and the first motor 15a in the embodiment correspond to examples of “inverter” and “motor” in the claims, respectively. The filter capacitor 5 of the embodiment corresponds to an example of a “capacitor” in the claims. The second voltage converter 21 and the multi-input voltage converter 50 of the embodiment correspond to an example of “second voltage converter” in the claims. The main battery 12 of the embodiment corresponds to an example of “main power source” in the claims, and the sub battery 25 corresponds to an example of “sub power source” in the claims. The main power source may be a fuel cell in addition to a chemical cell such as a lithium ion battery. In the technology disclosed in this specification, a large-capacity capacitor may be employed as the sub power source.

  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. The technical elements described in this specification or the 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. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2, 2a, 2b, 2c: power supply system 3: first low voltage end 4: first high voltage end 5: filter capacitor 6: reactor 7a: step-down switching element 7b: step-up switching element 8a, 8b: diode 9: smoothing capacitor 10: first voltage converter 11: controller 12: main battery 13: system main relay 14a: first inverter 14b: second inverter 15a: first motor 15b: second motor 16: engine 17: axles 18, 19, 45: Fuse 21: Second voltage converter 23: Second high voltage terminal 24: Second low voltage terminal 25: Sub battery 26: Auxiliary machine 28: Current sensor 29: Voltage sensor 30: Power split mechanism 31: Planetary gear 35: Drive wheel 41: third voltage converter 42: third high voltage terminal 43: third low voltage terminal 50: multi-input voltage converter Over data 51: transformer 100,100a, 100b, 100c: hybrid vehicles

Claims (2)

It is a power supply system for automobiles equipped with a traveling motor,
A main power supply that outputs DC power;
A sub power source that outputs DC power having a lower voltage than the main power source;
A first low voltage terminal is connected to the main power source, a first high voltage terminal is connected to an inverter that drives the traveling motor, and a first power source of the main power source is boosted and supplied to the inverter. One voltage converter;
A second low voltage end is connected to the sub power source, a second high voltage end is connected to the first low voltage end or the first high voltage end, and the power of the sub power source is boosted to increase the power A second voltage converter for supplying to the first voltage converter;
A controller,
With
The first voltage converter includes:
A step-up switching element connected between a positive electrode and a negative electrode of the first high-voltage end;
A reactor having one end connected to the high potential side of the step-up switching element and the other end connected to the positive electrode of the first low voltage end;
A capacitor connected between a positive electrode and a negative electrode of the first low voltage end;
A fuse connected in series with the step-up switching element;
With
The controller activates the second voltage converter when the fuse is not blown when a short circuit fault of the boost switching element is detected, and applies a voltage to the fuse to blow the fuse.
Power system. A diode connected in anti-parallel to the step-up switching element;
2. The controller according to claim 1, wherein the controller activates the second voltage converter and applies a voltage to the fuse to blow the fuse when a short circuit failure of one of the boost switching element and the diode is detected. Power system.

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