JP4704417B2 - Vehicle equipped with a DC / DC converter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To downsize a three-phase DC/DC converter. <P>SOLUTION: Three pieces of phaser arms UA-WA, consisting of series circuits composed of upper arm switching elements 81u-81w and lower arm switching elements 82u-82w in which diodes 83u-83w and 84u-84w are connected in parallel severally in reverse directions, are connected in parallel between a battery 24 and a fuel cell 22, and this converter is equipped with a reactor 90 between a common connection middle point of each phase arm UA-WA of the three-phase arms and the battery 24. By this configuration, the DC-DC converter 36, which can step up or step down a voltage with three-phase arms, can be materialized with one reactor 90. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

This invention relates to a vehicle equipped with a D C / DC converter apparatus that push elevating the DC voltage.

  Conventionally, DC / DC converter devices, which are switching power supplies using switching elements such as MOSFETs or IGBTs, have been widely used.

  For example, as one form of a vehicle using a motor as a travel drive source, a vehicle (herein referred to as an electric vehicle) in which a DC / DC converter device for stepping up / down a DC voltage is interposed between a power storage device and an inverter drive motor. Has been proposed. In this electric vehicle, when the motor is driven, the voltage of the power storage device is boosted by the DC / DC converter device and applied to the inverter, and during regeneration of the motor, the regenerative voltage generated in the inverter is stepped down by the DC / DC converter device. The battery is charged by being applied to the power storage device side.

  Further, as another form of vehicle using a motor as a travel drive source, a DC / DC converter device that directly connects a fuel cell and an inverter drive motor and steps up / down a DC voltage between the connection point and the power storage device is provided. There has also been proposed a vehicle (herein referred to as a fuel cell vehicle) in which a fuel cell is used as a main power supply device and a power storage device is a sub power supply device that assists the main power supply device.

  In this fuel cell vehicle, when the motor is driven, the voltage of the fuel cell and the voltage of the power storage device boosted by the DC / DC converter device are combined and applied to the inverter, and when the motor is regenerated, the regenerative voltage generated in the inverter is applied. The voltage is stepped down by the DC / DC converter device, applied to the power storage device side, and charged. Further, when there is a surplus in the generated power of the fuel cell, it is stepped down, applied to the power storage device side, and charged.

  FIG. 13 shows a DC / DC converter device 16 disclosed in Patent Document 1 applied to an electric vehicle. This DC / DC converter device 16 basically includes reactors 2A, 2B, 2C (2A to 2C) and diodes 7A, 7B, 7C (7A to 7C), 8A, 8B, and 8C (8A to 8C). A DC / DC converter 6 including a switching unit connected in reverse parallel to the transistors 3A, 3B, 3C (3A to 3C), 4A, 4B, and 4C (4A to 4C), and a control for driving and controlling the DC / DC converter 6 And means 5.

  The DC / DC converter device 16 boosts the voltage of the DC power supply 1 on the low-voltage side TL m times and converts it to a voltage to be applied to the load 11 on the high-voltage side TH. It has the function of stepping down to 1 and applying it to the DC power supply 1 of the low voltage side TL.

  As shown in FIG. 14, when the DC / DC converter device 16 is driven with a switching period of 2π, for example, with a duty of 1/3, during boosting, each transistor 4A of the lower arm switching element is driven in the three-phase arm. ˜4C is turned on in a state where the phase is shifted by 2π / 3 by the drive signals ULA, ULB, ULC (ULA to ULC) from the control means 5.

  When the transistors 4A to 4C are on, the transistors 4A to 4C side of the reactors 2A to 2C are grounded, so that current flows from the DC power source 1 to the reactors 2A to 2C toward the ground. . At this time, each reactor 2A-2C stores energy proportional to the product of the square of the flowing current and the inductance of each reactor 2A-2C.

  Next, when each of the transistors 4A to 4C is turned from on to off, a current corresponding to the energy stored in the reactors 2A to 2C flows to the high voltage side TH through the diodes 7A to 7C. At this time, the voltage of the high voltage side TH is monitored by the voltage detection circuit 6a.

  On the other hand, at the time of step-down, in the three-phase arm, the transistors 3A to 3C of the upper arm switching element are sequentially turned on with the phase shifted by 2π / 3 by the drive signals UHA, UHB and UHC (UHA to UHC) from the control means 5. Is done. When each of the transistors 3A to 3C is turned on, a current flows from the high voltage side TH to the DC power source 1 of the low voltage side TL through the transistors 3A to 3C and the reactors 2A to 2C, and energy is stored in the reactors 2A to 2C.

  Next, when each of the transistors 3A to 3C is sequentially turned off, the diodes 8A to 8C are turned on correspondingly, and a step-down circuit in which current flows from the ground to the DC power source 1 through the diodes 8A to 8C and the reactors 2A to 2C. Operate.

JP 2004-357388 A

  In a step-up / step-down DC / DC converter device, when an output current value exceeding the current rating of a switching element such as a MOSFET or an IGBT is required, a DC / DC converter having a multi-phase arm as described above instead of a single-phase arm The output current value is distributed to each phase arm. Therefore, in the DC / DC converter device of the multiphase arm according to the conventional technique, three reactors 2A to 2C for three phases are required in the example of FIG.

  By the way, since the impedance of the reactor increases in proportion to the frequency, a reactor having a larger inductance value is required as the frequency is lower at the same output current value. In order to reduce resistance loss, a reactor having a small Q is preferable, but a thick conductor is required to make a reactor having a small Q.

  The DC / DC converter device is desirably as small and light as possible. However, the number of reactors corresponding to the number of phases of the multiphase arm is one of the obstacles to reducing the size and weight of the DC / DC converter device. It has become.

The present invention has been made in consideration of such problems, a vehicle equipped with a D C / DC converter device you allow to reduce the size and weight of the DC / DC converter of the multi-phase arm The purpose is to provide.

In the present invention, a phase arm of three or more phases comprising a series circuit of an upper arm switching element and a lower arm switching element each having a diode connected in parallel in the opposite direction is a power storage device (hereinafter also referred to as a first power device). A multiphase arm connected in parallel between the traveling motor or the traveling motor and a fuel cell (hereinafter also referred to as a second electric power device), and a midpoint of each phase arm of the multiphase arm. A DC / DC converter capable of step-up / step-down , having a common connection, a commonly connected midpoint, and a reactor inserted and disposed between either the first power device or the second power device ; and the DC A DC / DC converter device equipped with a control unit for driving / controlling the DC / DC converter is mounted, and electric power is supplied from the power storage device to the traveling motor through the DC / DC converter. Both regenerative power of the traction motor is supplied to said power storage device side through the DC / DC converter.

  According to the present invention, the midpoints of the respective phase arms of the multiphase arm are commonly connected, and the reactor is inserted and disposed between the commonly connected midpoint and either the first power device or the second power device. By adopting a characteristic configuration, a DC / DC converter that can be stepped up and down with a polyphase arm can be realized with a single reactor.

In this invention , since only one reactor is required, the size and weight can be reduced.

  Further, since the number of reactors can be reduced to one, the smaller the number of phases of the multiphase arm, the smaller and lighter the weight can be achieved as compared with the DC / DC converter of the multiphase arm according to the prior art. .

By the DC / DC converter driving control to that control part, as well as turned on replacement before Symbol 3 phases or more phase arm 1 switching every cycle, when turning on the phase arms, said phase when the stepping down operation It turns on the upper arm switching element for each within one switching period constituting the arm, one switching cycle during the transition of the on and step-down operation and step-up operation of the lower arm switching element for each within one switching period when the boosting operation A DC / DC converter device capable of a step-up / step-down operation with a single reactor can be realized by outputting a drive signal for alternately turning on the upper and lower arm switching elements for each inside to drive the DC / DC converter.

  A DC / DC converter of a polyphase arm according to the prior art (a three-phase arm for ease of understanding) is provided for each of the three-phase upper arm (or the three-phase lower arm) in one switching cycle 2π. Although the reactor is energized once (see FIG. 14), in the present invention, during the step-up operation or step-down operation, the three-phase upper arm switching element (or) the three-phase lower arm switching element in one switching cycle 2π. The reactor is energized only once (see FIGS. 5 and 6). It is also included in the present invention that the reactor is energized once alternately by the three-phase upper arm switching element and the three-phase lower arm switching element within one switching period 2π (see FIG. 7).

  In this invention, since there is one reactor, the operating frequency of the reactor is substantially tripled. When the operating frequency is tripled, the inductance value may be reduced to 1/3, and the size of the reactor can be reduced accordingly.

In the present invention , the upper arm switching element and the lower arm switching element are not simultaneously turned on, and different phase arms are not simultaneously turned on. Therefore, at most one switching element is always turned on. Therefore, it has excellent heat dissipation (heat dissipation design is easy). As a result, the size of the DC / DC converter device can be reduced and the weight can be reduced.

  In this case, when the upper arm switching element or the lower arm switching element constituting the phase arm is alternately turned on, the control unit is alternately turned on with a dead time interposed therebetween, and the polyphase arm is constituted. By turning on the phase arm with the dead time interleaved, a short circuit between the upper arm switching element and the lower arm switching element and a short circuit between the phase arms can be prevented.

  Needless to say, if it is allowed that the heat radiation design is slightly difficult, the upper arm switching element is turned on at the same time on the condition that it is used within the rated current of the switching element (within the allowable element temperature). Thereafter, the present invention includes turning on the lower arm switching elements simultaneously for a plurality of phases with a dead time interposed therebetween. Furthermore, after turning on a plurality of upper arm switching elements at the same time, turning on a plurality of upper arm switching elements at the same time with a dead time interposed therebetween, or turning on a plurality of lower arm switching elements at the same time and then turning on a plurality of lower arm switching elements at the same time with a lower arm switching element interposed therebetween. It is also included in the present invention to turn on simultaneously (see FIG. 12). Even in this case, since the number of reactors is one, the size and weight can be reduced accordingly.

  According to the present invention, the midpoints of the respective phase arms of the multiphase arm are commonly connected, and the reactor is inserted and disposed between the commonly connected midpoint and either the first power device or the second power device. By adopting a characteristic configuration, a DC / DC converter that can be stepped up and down with a polyphase arm can be realized with a single reactor.

In this invention , since only one reactor is required, the size and weight can be reduced.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a vehicle or the like to which a DC / DC converter device that implements a method for driving a DC / DC converter device according to the present invention is applied will be described with reference to the drawings.

  A fuel cell vehicle 20 according to this embodiment shown in FIG. 1 basically includes a hybrid power source device including a fuel cell 22 and a power storage device (battery) 24 as energy storage, and the hybrid. A traveling motor 26 to which current (electric power) is supplied from a power supply device of a type through an inverter 34, a primary side 1S to which a battery 24 is connected, a fuel cell 22 and a motor 26 (inverter 34) are connected 2 DC / DC converter apparatus {VCU (Voltage Control Unit) that performs voltage conversion with the secondary side 2S. } 23.

  The VCU 23 includes a DC / DC converter 36 and a converter control unit 54 that drives and controls the DC / DC converter 36.

  The fuel cell 22 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 hydrogen tank 28 and an air compressor 30 are connected to the fuel cell 22 by piping. A generated current If generated by an electrochemical reaction of hydrogen (fuel gas), which is a reaction gas, and air (oxidant gas) in the fuel cell 22 is passed through a current sensor 32 and a diode (also referred to as a disconnect diode) 33. And supplied to the inverter 34 and / or the DC / DC converter 36.

  The inverter 34 performs DC / AC conversion and supplies the motor current Im to the motor 26, while the motor current Im after AC / DC conversion accompanying the regenerative operation is transferred from the secondary side 2 </ b> S to the primary side through the DC / DC converter 36. Supply to 1S.

  In this case, the primary voltage V1 obtained by converting the secondary voltage V2 which is the regenerative voltage or the generated voltage Vf into a low voltage by the DC / DC converter 36 is stepped down by the downverter 42 to be further reduced to a voltage such as a lamp. While being supplied to the auxiliary machine 44 as the auxiliary machine current Iau, if there is a surplus, the battery 24 is charged as the battery current Ibat.

  As the battery 24 connected to the primary side 1S, for example, a lithium ion secondary battery or a capacitor can be used. In this embodiment, a lithium ion secondary battery is used.

  The battery 24 supplies the auxiliary machine current Iau to the auxiliary machine 44 through the downverter 42 and supplies the motor current Im to the inverter 34 through the DC / DC converter 36.

  Smoothing capacitors 38 and 39 are provided on the primary side 1S and the secondary side 2S, respectively. A resistor 40 is connected to the secondary side 2S capacitor 39 in parallel, that is, in parallel to the fuel cell 22.

  The system including the fuel cell 22 is controlled by the FC controller 50, the system including the inverter 34 and the motor 26 is controlled by the motor controller 52 including the inverter driver, and the system including the DC / DC converter 36 includes the converter driver. Each of them is basically controlled by a converter control unit 54 including the above.

  The FC control unit 50, the motor control unit 52, and the converter control unit 54 are higher-level control units and are controlled by an overall control unit 56 that determines the total load amount Lt and the like of the fuel cell 22.

  The overall control unit 56, the FC control unit 50, the motor control unit 52, and the converter control unit 54 are respectively an input / output interface such as an A / D converter and a D / A converter in addition to a CPU, a ROM, a RAM, and a timer. In addition, a DSP (Digital Signal Processor) or the like is included as necessary.

  The overall control unit 56, the FC control unit 50, the motor control unit 52, and the converter control unit 54 are connected to each other through a communication line 70 such as a CAN (Controller Area Network) that is an in-vehicle LAN, and are connected to various switches and sensors. Input / output information is shared, and input / output information from these various switches and various sensors is input, and each CPU executes a program stored in each ROM to realize various functions.

  Here, as various switches and various sensors for detecting the vehicle state, in addition to the current sensor 32 for detecting the generated current If, the voltage sensor 61 for detecting the primary voltage V1 (equal to the battery voltage Vbat), the primary current. A current sensor 62 for detecting I1 and a secondary voltage V2 (a voltage sensor 63 for detecting a secondary voltage I2 when the disconnect diode 33 is conductive and substantially equal to the generated voltage Vf of the fuel cell 22) are detected. There are a current sensor 64, an ignition switch 65 connected to the communication line 70, an accelerator sensor 66, a brake sensor 67, a vehicle speed sensor 68, a temperature sensor 69 connected to the converter control unit 54, and the like.

  The overall control unit 56 determines the fuel cell vehicle based on inputs (load requests) from various switches and various sensors in addition to the state of the fuel cell 22, the state of the battery 24, the state of the motor 26, and the state of the auxiliary machine 44. From the total load requirement amount Lt of 20, the fuel cell shared load amount (required output) Lf to be borne by the fuel cell 22, the battery shared load amount (required output) Lb to be borne by the battery 24, and the regenerative power source The distribution (sharing) of the power regenerative power sharing load amount Lr is determined while arbitrating, and a command is sent to the FC control unit 50, the motor control unit 52, and the converter control unit 54.

  The DC / DC converter 36 includes an upper arm composed of a switching element such as an IGBT between the battery 24 (first power device) and the second power device {the fuel cell 22 or the regenerative power source (inverter 34 and motor 26)}. Three phase arms {U-phase arm UA (81u, 82u) comprising switching element 81 {81u, 81v, 81w (81u to 81w)} and lower arm switching element 82 {82u, 82v, 82w (82u to 82w)} ), V-phase arm VA (81v, 82v), W-phase arm WA (81w, 82w)} are configured as a three-phase arm connected in parallel.

  Diodes 83u, 83v, 83w, 84u, 84v, and 84w are connected in the opposite direction to the arm switching elements 81u, 81v, 81w, 82u, 82v, and 82w, respectively.

  When the voltage is converted between the primary voltage V1 and the secondary voltage V2 by the DC / DC converter 36, one reactor 90 for releasing and storing energy is provided for each phase arm (U phase). Arm UA, V-phase arm VA, W-phase arm WA) are inserted between the common connection point at the midpoint and battery 24.

  The upper arm switching elements 81 (81u to 81w) are turned on by gate drive signals (drive voltages) UH, VH, and WH (high levels thereof) output from the converter control unit 54, and the lower arm switching elements 82 ( 82u to 82w) are turned on by gate drive signals (drive voltages) UL, VL, and WL (high levels thereof), respectively.

  The primary voltage V1, typically the open circuit voltage OCV (Open Circuit Voltage) of the battery 24 when no load is connected, as shown on the fuel cell output characteristics (current voltage characteristics) 91 of FIG. The fuel cell 22 is set to a voltage higher than the minimum voltage Vfmin of the power generation voltage Vf. In FIG. 2, OCV≈V1.

  The secondary voltage V2 is set to a voltage equal to the power generation voltage Vf of the fuel cell 22 when the fuel cell 22 is generating power.

  However, when the power generation voltage Vf of the fuel cell 22 becomes equal to the voltage Vbat (= V1) of the battery 24, a direct connection state indicated by a thick dashed line in FIG. In the direct connection state, when the duty of the drive signals UH, VH, and WH supplied to the upper arm switching element 81 (81u to 81w) is set to 100 [%] and current flows from the secondary side 2S to the primary side 1S. When the upper arm switching element 81 (81u to 81w) is turned on and a current flows through the upper arm switching element 81 (81u to 81w), a current flows from the primary side 1S to the secondary side 2S. .About.83w conduct and current flows through the diodes 83u.about.83w. When the output is high, the secondary current I2 is supplied from the secondary side 2S of the DC / DC converter 36 to the inverter 34 side. } In the direct connection state (referred to as the high output direct connection state or the first direct connection state), the secondary voltage V2 becomes V2 = V1-Vd (Vd is the forward voltage drop of the diodes 83u, 83v, 83w).

  The direct connection state is used not only in the high output area but also when necessary for control. For example, the direct connection state can be used when the fuel cell vehicle 20 stops. When the fuel cell vehicle 20 is stopped (waiting for a signal or the like), the driving of the air compressor 30 is stopped and fuel gas supply from the hydrogen tank 28 is also stopped in order to save fuel consumption. In this case, the power generation voltage Vf (power generation current If) of the fuel cell 22 becomes zero when the residual fuel gas in the fuel cell 22 is exhausted by the discharge by the resistor 40 and the supply to the auxiliary equipment 44 such as an air conditioner. However, the supply of the auxiliary machine current Iau to the auxiliary machine 44 is continued by the battery 24.

  When the fuel cell vehicle 20 is stopped, that is, when the so-called idle stop is performed, the brake pedal operation is released, the accelerator pedal operation is performed to return the fuel cell 22 to the power generation state, and the output control of the fuel cell 22 by the VCU 23 is smoothly performed. In order to resume, the voltage on the secondary side 2S of the DC / DC converter 36 is kept at the voltage of the direct connection state. In this direct connection state (referred to as an idle stop direct connection state or a second direct connection state), the load is the resistor 40, and the voltage V2 on the secondary side 2S of the DC / DC converter 36 is held at V2 = V1-Vd. .

  Here, output control of the fuel cell 22 by the VCU 23 will be described.

  During power generation in which fuel gas from the hydrogen tank 28 and compressed air from the air compressor 30 are supplied, the power generation current If of the fuel cell 22 is referred to as a characteristic 91 {function F (Vf) shown in FIG. } Is determined by setting the secondary voltage V2, that is, the generated voltage Vf, through the DC / DC converter 36 by the converter control unit 54. That is, the generated current If is determined as a function F (Vf) value of the generated voltage Vf. If If = F (Vf) and the generated voltage Vf is set to Vf = Vfa = V2, for example, the generated current Ifa as a function value of the generated voltage Vfa (V2) is determined. {Ifa = F (Vfa) = F (V2)}.

  Since the fuel cell 22 determines the secondary voltage V2 (power generation voltage Vf) in this way, the power generation current If is determined. Therefore, when the fuel cell vehicle 20 is driven and controlled, the secondary voltage V2 (power generation voltage Vf) is determined. ) Is set to the target voltage (target value). However, in a special case where the battery 24 (first power device) is considered to be faulty, such as when the battery 24 is opened due to a disconnection fault of the wiring between the downverter 42 and the battery 24, the primary voltage V1 is The target voltage.

  In the system including the fuel cell 22 such as the fuel cell vehicle 20, the VCU 23 is controlled so that the secondary voltage V2 of the secondary side 2S of the DC / DC converter 36 becomes the target voltage, and the output (power generation) of the fuel cell 22 is controlled by the VCU 23. The current If) is controlled. The above is the description of the output control of the fuel cell 22 by the VCU 23.

  Next, the basic operation of the DC / DC converter 36 that is driven and controlled by the converter control unit 54 will be described with reference to the flowchart of FIG.

  As described above, the overall control unit 56 is based on inputs (load requests) from various switches and various sensors in addition to the state of the fuel cell 22, the state of the battery 24, the state of the motor 26, and the state of the auxiliary machine 44. From the determined total load request amount Lt of the fuel cell vehicle 20, a fuel cell shared load amount (request output) Lf that the fuel cell 22 should bear, a battery share load amount (request output) Lb that the battery 24 should bear, The distribution (sharing) of the regenerative power share load amount Lr to be borne by the regenerative power supply is determined while arbitrating, and a command is sent to the FC control unit 50, motor control unit 52, and converter control unit 54.

  In step S1, when the total load request amount Lt is determined (calculated) from the power request of the motor 26, the power request of the auxiliary device 44, and the power request of the air compressor 30, which are load requests, respectively, in the overall control unit 56. In step S2, the overall control unit 56 determines the distribution of the fuel cell shared load amount Lf, the battery shared load amount Lb, and the regenerative power source shared load amount Lr for outputting the determined total load request amount Lt. Here, when determining the fuel cell shared load Lf, the efficiency η of the fuel cell 22 is considered.

  Next, in step S3, the converter control unit 54 determines the power generation voltage Vf of the fuel cell 22, in this case, the secondary voltage V2, in accordance with the fuel cell shared load Lf.

  When the secondary voltage V2 is determined, in step S4, the converter control unit 54 drives and controls the DC / DC converter 36 so that the determined secondary voltage V2 is obtained.

  In this case, the converter control unit 54 drives the DC / DC converter 36 in a step-up operation, a step-down operation, or a direct connection operation according to the determined secondary voltage V2.

  In step S4, in the step-up operation in which the secondary current I2 is sourced from the secondary side 2S of the DC / DC converter 36 to the inverter 34 side, the converter control unit 54 turns on the lower arm switching element 82u (from the battery current Ibat to the reactance 90). Energy is accumulated by the primary current I1 obtained by subtracting the auxiliary machine current Iau, and at the same time, the secondary current I2 is sourced from the capacitor 39 to the inverter 34. The same applies to the diodes 83u to 83w. Energy is stored in the inverter 34, and is sourced as the secondary current I2 to the inverter 34. The same applies to the following) → lower arm switching element 82v on → diode 83u to 83w conduction → lower arm switching element 82w on → diode 83u to 83w conduction → lower Rotate the switching of the DC / DC converter 36 in the absence of the switching element 82u on ... order.

  The on-duty of the upper arm switching elements 81u to 81w and the lower arm switching elements 82u to 82w is determined so that the output voltage V2 is maintained.

  In step S4, in the high output direct connection operation in which the secondary current I2 is sourced from the secondary side 2S of the DC / DC converter 36 to the inverter 34 side, the diodes 83u to 83w are in a conductive state and the secondary voltage V2 is V2. = V1-Vd.

  Further, in step S4, the secondary current I2 is supplied from the secondary side 2S of the DC / DC converter 36 to the auxiliary device 44 and the battery 24 of the primary side 1S (sinking is performed on the secondary side 2S). ) In step-down operation, the upper arm switching element 81u is turned on (energy is accumulated in the reactance 90 by the secondary current I2 output from the capacitor 39, and the primary current I1 is supplied from the capacitor 38 to the auxiliary device 44 and the battery 24 as required. The diodes 84u to 84w are turned on (the diodes 84u to 84w are turned on as flywheel diodes, discharge energy from the reactance 90, store energy in the capacitor 38, and store the energy in the auxiliary unit 44 and the battery 24 as required. To the primary current I1. Rotation switching of the DC / DC converter 36 is performed in the order of turning on the chipping element 81v → conducting the diodes 84u to 84w → oning the upper arm switching element 81w → conducting the diodes 84u to 84w → oning the upper arm switching element 81u.

  When a regenerative voltage is present, the regenerative power source shared load Lr is added to the sinked secondary current during the step-down operation. The on-duty of the upper arm switching elements 81u to 81w and the lower arm switching elements 82u to 82w in the step-down operation is also controlled according to the determined output voltage V2.

  The secondary voltage V <b> 2 and the primary voltage V <b> 1 are controlled by the converter control unit 54 by PID control in which the DC / DC converter 36 is combined with feedforward control and feedback control.

  The above is the description of the basic operation of the DC / DC converter 36 that is driven and controlled by the converter control unit 54.

  As shown in FIGS. 4A and 4B, each of the arm switching elements 81u to 81w and 82u to 82w is a so-called 6-in-1 module 13 fixed on a heat radiating plate (heat spreader) 12 made of metal. A temperature sensor 69 is attached to each of the arm switching elements 81u to 81w and 82u to 82w. The gate terminals of the temperature sensors 69 and the arm switching elements 81u to 81w and 82u to 82w are connected to the converter control unit 54. Yes. The diodes 83u to 83w and 84u to 84w paired with the arm switching elements 81u to 81w and 82u to 82w are not shown.

  Since the fuel cell vehicle 20 according to this embodiment uses the 6-in-1 module 13 having the same configuration as the DC / DC converter 36 as the inverter 34 for driving the motor 26, the cost can be reduced.

  However, when the motor 26 is driven by the inverter 34, the midpoints of the three-phase arms of the inverter 34 are not commonly connected, and the midpoints are connected to the U-phase coil, V-phase coil, and W-phase coil of the motor 26. Full bridge configuration.

  The fuel cell vehicle 20 according to this embodiment is basically configured and operates as described above. Next, the rotation switching operation by the VCU 23 including the DC / DC converter 36 will be described in more detail.

  FIG. 5 shows a time chart during the step-down operation of the VCU 23 (when sinking the secondary current I2), and FIG. 6 shows a time chart during the step-up operation of the VCU 23 (when the secondary current I2 is sourced).

  5 and 6, the sign of the primary current I1 flowing through the reactor 90 is a boost current flowing from the primary side 1S to the secondary side 2S (source flowing out from the secondary side 2S of the DC / DC converter 23 to the inverter 34). (Current) is positive (+), and the step-down current flowing from the secondary side 2S to the primary side 1S (sink current flowing from the fuel cell 22 or the inverter 34 to the secondary side 2S) is negative (−).

  Further, in the waveforms of the drive signals UH, UL, VH, VL, WH, WL output from the converter control unit 54, the drive signals UH, UL, VH, VL, WH, WL are supplied during the hatched periods. It shows a period during which the arm switching element (for example, the arm switching element corresponding to the drive signal UH is the upper arm switching element 81u) is actually turned on (current is flowing). That is, even if the drive signals UH, UL, VH, VL, WH, WL are supplied, current does not flow to the corresponding arm switching element unless the corresponding parallel diodes 83u to 83w and 84u to 84w are OFF. Note that.

  As shown in FIGS. 5 and 6, the drive signals UH, UL, VH, VL, WH, WL output from the converter control unit 54 in both cases of the step-down operation and the step-up operation of the DC / DC converter 36. As can be understood from the waveform, the UVW phase arms UA, VA, WA (UA to WA) constituting the three-phase arm are set to drive signals UH, UL, VH, VL, WH, WL every switching cycle 2π. When the UVW phase arms UA to WA are turned on while being switched on (rotated) with the U phase, V phase, W phase, U phase,..., The UVW phase arms UA to The upper arm switching element 81 (81u to 81w) constituting the WA is turned on (FIG. 5) or the lower arm switching constituting the UVW respective phase arms UA to WA by the drive signals UL, VL, WL. Child 82 (82u to 82w) are turned on (Fig. 6).

  In this case, as can be seen from FIGS. 5 and 6 and FIG. 7 to be described later, the upper arm switching elements 81u to 81w are used to prevent the upper and lower arm switching elements 81 and 82 from being simultaneously turned on and the voltage V2 from being short-circuited. Alternatively, a dead time dt is interposed between the drive signal UH and the drive signal UL, the drive signal VH and the drive signal VL, and the drive signal WH and the drive signal WL for alternately turning on the lower arm switching elements 82u to 82w. When the phase arms UA to UW constituting the multi-phase arm are turned on and switched on, the drive signal UL is driven, the drive signal VH is driven, the drive signal VL is driven, and the drive signal WL is driven. Each signal UH is turned on with a dead time dt interposed therebetween. That is, so-called synchronous switching is performed with the dead time dt interposed therebetween.

  In FIG. 5 for explaining the step-down operation, for example, during the period in which the upper arm switching element 81u is turned on by the drive signal UH between time points t1 and t2, the secondary current I2 from the fuel cell 22 and / or the regenerative power source is supplied. Thus, energy is accumulated in the reactor 90 through the upper arm switching element 81u. The dead time dt from the time point t2 to the time point t5, the drive signal UL is on (however, no current flows through the lower arm switching element 82u), and the energy accumulated in the reactor 90 is the flywheel diode during the dead time dt period. Is discharged as the primary current I1 to the primary side 1S through the diodes 84u to 84w which are turned on. After time t5, the upper arm switching elements 81v, 81w, 81u,... Are turned on sequentially, and the same operation is repeated.

  In FIG. 6 for explaining the step-up operation, for example, during the period in which the lower arm switching element 82u is turned on by the drive signal UL between time points t13 and t14, energy is supplied to the reactor 90 by the primary current I1 from the battery 24. Accumulated. During the dead time dt from the time t14 to t17, the drive signal VH is ON (current does not flow through the upper arm switching element 81v), and the dead time dt, the energy accumulated in the reactor 90 is converted into a rectifier diode. It is discharged to the secondary side 1S through the diodes 83u to 83w that have been turned on. After time t17, the lower arm switching elements 82v, 82w, 82u,... Are turned on sequentially, and the same operation is repeated.

  In FIG. 7 for explaining the operation at the time of transition between the step-up operation and the step-down operation, for example, a period during which the upper arm switching element 81u is turned on by the drive signal UH between the time points t20 and t21 (shown by hatching). In the period), energy is accumulated in the reactor 90 through the upper arm switching element 81u by the secondary current I2 from the fuel cell 22 and / or the regenerative power source.

  During the period from time t21 to the time t22 when the direction of current flow is reversed (the sign is reversed from negative to positive), the energy stored in the reactor 90 is the diodes 84u to 84w that function as the turned-on flywheel diodes. To the primary side 1S.

  During a period in which the lower arm switching element 82u is turned on by the drive signal UL between time points t22 and t23, energy is accumulated in the reactor 90 by the primary current I1 from the battery 24. In the period from time t23 to the time t24 when the direction of current flow is reversed (the sign is reversed from positive to negative), the energy accumulated in the reactor 90 is transferred to the secondary side 2S through the diodes 83u to 83w that are turned on. Released. Thereafter, the same operation is repeated. Thus, in the three-phase rotation switching according to this embodiment, the operation smoothly changes between the step-up operation and the step-down operation.

  As described above, according to the embodiment described above, the DC / DC converter 36 includes the upper arm switching elements 81u to 81w and the lower arm switching elements in which the diodes 83u to 83w and 84u to 84w are connected in parallel in the opposite directions. Three phase arms UA to WA composed of a series circuit of 82 u to 82 w are arranged in parallel between the battery 24 as the first power device, the fuel cell 22 as the second power device and / or the inverter 34 and the motor 26. Inserted between the three-phase arm connected to each other, the common connection midpoint of the phase arms UA to WA of the three-phase arm, and the battery 24 (or the second power device) as the first power device. One reactor 90 is provided.

  With this configuration, the DC / DC converter 36 that can be stepped up and down with a three-phase arm can be realized by a single reactor 90.

  That is, a converter control unit 54 that drives and controls the DC / DC converter 36 is provided. When the converter control unit 54 turns on the phase arms UA to WA, and turns on the phase arms UA to WA, for example, When the phase arm UA is turned on, one of the upper arm switching element 81u and the lower arm switching element 82u constituting the phase arm UA is turned on (FIGS. 5 and 6) or alternately turned on (FIG. 7). By outputting the UL and driving the DC / DC converter 36, a VCU (DC / DC converter device) 23 capable of a step-up / step-down operation with one reactor 90 can be realized.

  Since the DC / DC converter 36 and the VCU 23 need only have one reactor 90, they can be reduced in size and weight.

  Further, the DC / DC converter 6 of the polyphase arm according to the prior art shown in FIGS. 13 and 14 (referred to as a three-phase arm for ease of understanding) has three phases in one switching cycle 2π. Each of the reactors 2A to 2C of the arm is energized once. In the present invention, the three-phase arms UA to UA are switched in one switching cycle 2π during the step-up operation (FIG. 6) or the step-down operation (FIG. 5). Only one reactor 90 of WA is energized once. Therefore, in principle, in the present invention, the operating frequency of the reactor 90 is substantially tripled.

  When the operating frequency is tripled, the inductance value may be reduced to 1/3, so that the size of the reactor 90 can be reduced accordingly. Further, since the number of reactors 90 can be reduced to one, the smaller the number of phases of the multiphase arm, the smaller the size and weight of the multiphase arm DC / DC converter according to the prior art. it can.

  According to the present invention, the upper arm switching element 81 and the lower arm switching element 82 are not simultaneously turned on, and different phase arms are not simultaneously turned on. Therefore, at most one switching element is always turned on. Therefore, it has excellent heat dissipation (heat dissipation design is easy). As a result, the size of the VCU 23 can be reduced and the weight can be reduced.

  In this case, the converter control unit 54 configures the three-phase arm as described with reference to FIGS. 5 to 7 when turning on the phase arms UA to WA of the DC / DC converter 36 including the three-phase arm. When the UVW phase arms UA to WA are alternately turned on, and when the UVW phase arms UA to WA are alternately turned on, a certain phase arm, for example, the upper arm switching element 81u of the U phase arm UA is turned on (FIGS. 5 to 7), and then the dead time dt After turning on the lower arm switching element 82u of the U-phase arm UA across FIG. 7 (FIG. 7) and then turning on the upper arm switching element 81v of the V-phase arm VA which is the next phase across the dead time dt (FIG. 7) 5 to 7), the switching timing is rotated so that the lower arm switching element 82v is turned on in the order of the V-phase arm VA across the dead time dt (FIG. 7). ® are down.

  Thus, the converter control unit 54 turns on alternately with the dead time dt interposed between the upper arm switching element 81 and the lower arm switching element 82 constituting the phase arms UA to WA, and the multi-phase arm By switching the phase arms UA to WA constituting the slewing on with the dead time interposed therebetween, it is possible to prevent a short circuit between the upper arm switching element and the lower arm switching element and a short circuit between the phase arms.

  FIG. 8 shows a time chart of drive signals UH, UL, VH, VL, WH, WL according to another embodiment of three-phase rotation.

  In this other embodiment, rotation switching is performed in which the drive signal VL is stopped without rotating all the drive signals UH, UL, VH, VL, WH, and WL. As shown in FIG. 4A, since the temperature sensor 69 for measuring the element temperature of all the arm switching elements 81u, 81v, 81w, 82u, 82v, 82w is provided, the lower arm switching element 82v whose element temperature is higher than the threshold temperature. The driving is temporarily stopped, and the rotation switching is continued with the remaining arm switching elements 81u, 81v, 81w, 82u, and 82w. When the element temperature falls below the threshold temperature and returns to the normal range, the three-phase rotation switching drive by all the arm switching elements 81u, 81v, 81w, 82u, 82v, 82w is performed again. The driving signal to be paused is not limited to one arm. For example, the drive signals UH, VH, and VL may be paused.

  The intermittent rotation switching shown in the example in Fig. 8 is applied to the application in which switching is continued only with another phase arm without operating the failed phase arm when a failure such as opening occurs in a certain phase arm. can do. By having this operation, the reliability of the VCU 23, and hence the fuel cell vehicle 20, can be increased.

  As described above, in the present invention, the phase arms UA to WA are switched on and turned on. However, when the phase arms UA to WA are switched on, the upper arm switching elements 81 (81u, 81u constituting the phase arms UA to WA) are switched on. 81v, 81w) or the lower arm switching element 82 (any one of 82u, 82v, 82w) is controlled to be turned on.

  When the phase arms UA to WA constituting the multi-phase arm are switched on, the upper arm switching elements 81u to 81w and the lower arm switching elements 82u to 82w of a certain phase are alternately turned on regardless of the order. Thereafter, the upper arm switching elements 81u to 81w and the lower arm switching elements 82u to 82w of the next phase arm can be alternately turned on regardless of the order. Further, when the phase arms UA to WA are turned on alternately, the control is facilitated by performing control so that the phase arms UA to WA are alternately turned on every switching cycle 2π. Control may be made so that the phase arms UA to WA are alternately turned on every two switching cycles of 4π or more.

  The present invention can be applied not to the three-phase DC / DC converter 36 but also to the fuel cell vehicle 20A as a two-phase DC / DC converter 36A as shown in FIG. If there are two or more phases, the present invention can be applied even if there are four or more phases.

  Further, the present invention can be applied not to the fuel cell vehicles 20 and 20A but to a battery driven vehicle (electric vehicle) 21 as shown in FIG. Of course, the present invention can also be applied to a so-called parallel or series-parallel hybrid vehicle equipped with an engine, a battery, and a motor.

  Furthermore, the motor 26 is not limited to the vehicle. For example, the present invention can also be applied to a motor for raising and lowering an elevator.

  Furthermore, as shown in FIG. 11, the inverter 34 is replaced with a single-phase load 35, the motor control unit 52 is replaced with a load control unit 53, the ignition switch 65 is replaced with a power switch 65a, and various sensors 66a. , 67a, 68a can be applied to the fuel cell system 20B. The overall control unit 56 controls the VCU 23 through the converter control unit 54, and as a result, controls the load current IL.

  The present invention is not limited to the above-described embodiment, and based on the description in this specification, for example, as shown in the waveform diagram of the step-down operation of FIG. 12 drawn corresponding to FIG. If it is used within the current (within the allowable element temperature), the upper arm switching elements 81u, 81v, 81w are simultaneously turned on by the drive signals UH, UV, UW after the time t31, and then the dead time dt is interposed therebetween. Various configurations can be adopted, such as the arm switching elements 81u, 81v, 81w being simultaneously turned on for three phases by drive signals UH, UV, UW. After time t41, the two-phase upper arm switching elements 81u and 81w are simultaneously turned on with the dead time dt interposed therebetween. In the step-up operation of FIG. 6 and the step-up / step-down alternating operation of FIG.

1 is a circuit diagram of a fuel cell vehicle according to an embodiment of the present invention. It is explanatory drawing of the current-voltage characteristic of a fuel cell. It is explanatory drawing of the basic control table | surface of the DC / DC converter apparatus mounted in the fuel cell vehicle. 4A is a plan view for explaining the arrangement of the upper and lower arm switching elements with respect to the heat radiating plate, and FIG. 4B is a side view thereof. It is a time chart used for operation | movement description of the pressure | voltage fall operation | movement of a DC / DC converter apparatus. It is a time chart used for operation | movement description of the pressure | voltage rise operation of a DC / DC converter apparatus. It is a time chart which shows the transition of the step-up / step-down operation of the DC / DC converter device. It is a time chart which shows the state of the drive signal UH, UL, VH, VL, WH, WL which concerns on the other Example of 3 phase rotation. It is a circuit diagram of a fuel cell vehicle provided with a two-phase DC / DC converter device. It is a circuit diagram of a battery drive vehicle. It is a circuit diagram of a fuel cell system. It is a time chart used for operation | movement description of the pressure | voltage fall operation | movement which concerns on other embodiment of a DC / DC converter apparatus. It is a circuit diagram of the DC / DC converter apparatus which has three reactors based on a prior art. 14 is a time chart used for explaining the operation of the example in FIG.

Explanation of symbols

20 ... Fuel cell vehicle 22 ... Fuel cell 23 ... DC / DC converter unit (VCU)
24 ... Power storage device (battery) 26 ... Motor 34 ... Inverter 36 ... DC / DC converter 54 ... Converter control unit 81 (81u-81w) ... Upper arm switching element 82 (82u-82w) ... Lower arm switching elements 83u, 83v, 83w, 84u, 84v, 84w ... Diode 90 ... Reactor 91 ... Fuel cell output characteristics (current-voltage characteristics)
UA ... U-phase arm VA ... V-phase arm WA ... W-phase arm UH, UL, VH, VL, WH, WL ... Drive signal

Claims (3)

A power storage device;
A traveling motor;
Three or more phase arms composed of a series circuit of an upper arm switching element and a lower arm switching element, each having a diode connected in parallel in the opposite direction, are connected in parallel between the power storage device and the traveling motor. A multi-phase arm and a central point of each phase arm of the multi-phase arm are connected in common, and a reactor that is inserted and arranged between the commonly connected mid-point and either the power storage device or the traveling motor; A DC / DC converter device comprising: a DC / DC converter capable of step-up / step-down and a control unit that drives and controls the DC / DC converter;
A vehicle in which electric power is supplied from the power storage device to the travel motor through the DC / DC converter, and regenerative power of the travel motor is supplied to the power storage device side through the DC / DC converter. There,
The controller is
While turned on alternating pre Symbol least three phases arms every switching period, the phase arm when checked, each within one switching period of the upper arm switching element constituting said phase arm when the stepping down operation turned on, turned on alternately the upper and lower arm switching element the lower arm switching element is turned on every inside one switching cycle, the each inside one switching period during the transition of the step-down operation and the step-up operation when the boosting operation drive signal A vehicle characterized by output of. The vehicle according to claim 1,
further,
A vehicle comprising: a fuel cell connected in parallel to the traveling motor. The vehicle according to claim 1 or 2,
The controller is
When alternately turning on the upper arm switching element or the lower arm switching element constituting the phase arm, the phase arm constituting the polyphase arm is turned on alternately with the dead time between the dead time. A vehicle characterized in that it is switched on and turned on.

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