Three-energy-source fuel cell vehicle integrated DC-DC converter

Abstract

The invention provides a three-energy-source fuel cell vehicle integrated DC-DC converter which comprises a forward bootstrap boost module, an input energy source control module, an auxiliary energy source charging module, a braking energy feedback module and a converter controller. The forward bootstrap boost module is connected with output terminals O3, O4 and O5 of the input energy source control module through input terminals I1, I2 and I3, and is connected with a high-potential line H and a low-potential line L of a high-voltage direct-current bus through output terminals O1 and O2; the integrated DC-DC converter with a unique layout is adopted, an isolation transformer with high cost does not need to be used, and at least three isolation transformers and 11 power switch tubes can be reduced, so that the weight and the size are reduced, the cost of the electric driving system of the fuel cell automobile is effectively reduced, the energy consumption is reduced, and the power consumption is reduced. Meanwhile, the functions of power supply, charging, braking energy feedback and the like are achieved.

Description

Technical Field

[0001] The present invention relates to the field of power systems for new energy vehicles, and in particular to an integrated DC-DC converter for a three-energy source fuel cell vehicle. Background Art

[0002] Fuel cells generate electricity directly through electrochemical reactions. The reaction process produces almost no other harmful reaction products. They have high energy density and conversion efficiency. As the main energy source (main power source) of new energy vehicles, they have great development potential. However, the chemical reaction process of fuel cells is affected by mechanical devices and physical environment, resulting in low dynamic performance, output characteristics and response speed. Moreover, as a unidirectional energy flow system, it cannot recover braking energy. The power system with fuel cells as the only energy source cannot fully meet the needs of vehicle driving. It is usually equipped with power batteries or supercapacitors to form a fuel cell hybrid power system (FCHPS), and the DC-DC converter is a key component of fuel cell hybrid vehicles to achieve vehicle power flow control and improve vehicle power performance. In the traditional fuel cell hybrid electric vehicle multi-energy source structure, the energy transmission circuit is usually composed of multiple dual-port DC-DC converters. The fuel cell serves as the main energy source and is connected to the vehicle's high-voltage DC bus through a unidirectional dual-port DC-DC converter to provide power for the motor drive system and for the power battery and / or supercapacitor; the power battery and / or supercapacitor serve as auxiliary energy sources and are connected to the high-voltage DC bus through a bidirectional dual-port DC-DC converter to provide power for the motor drive system or recover braking energy.

[0003] In the existing document 202111111945.7, the automobile power system needs to be separately configured with 3 or 4 DC-DC converters. Obviously, the more DC-DC converters there are, the more power switching tubes and other devices are used, the higher the loss will be during the power conversion process, and the large volume and weight are not conducive to the integration and miniaturization of vehicle components, and the cost is also higher. Therefore, the present invention proposes a three-energy source fuel cell vehicle integrated DC-DC converter to solve the problems existing in the prior art. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention proposes an integrated DC-DC converter for a three-energy source fuel cell vehicle. The integrated converter for a three-energy source fuel cell vehicle can power the automobile motor drive system or recover braking energy, or the fuel cell can charge the power battery and supercapacitor; the converter adapts to the output voltage change requirements of the fuel cell, has a wide input voltage range, high conversion efficiency, realizes the integration of hardware and control methods, reduces costs, and has good application prospects.

[0005] The technical solution of the present invention is implemented as follows: a three-energy source fuel cell vehicle integrated DC-DC converter, including a forward bootstrap boost module, an input energy source control module, an auxiliary energy source charging module, a braking energy feedback module and a converter controller, wherein the forward bootstrap boost module is connected to the output terminals O3, O4, and O5 of the input energy source control module through input terminals I1, I2, and I3, and is connected to the high potential line H and the low potential line L of the high voltage DC bus through the output terminals O1 and O2; the input energy source control module is connected to the output terminals I4, I5, and I6 of the input energy source control module through the input terminals I6, I7, and I8. They are respectively connected to the positive electrodes of the fuel cell, the power battery and the supercapacitor, and are connected to the input terminals I1, I2 and I3 of the forward bootstrap boost module through the output terminals O3, O4 and O5; the input terminal I7 of the auxiliary energy source charging module is connected to the positive electrode of the fuel cell, I8 is connected to the positive electrode of the power battery, the output terminal O6 is connected to the positive electrode of the power battery, and O7 is connected to the positive electrode of the supercapacitor; the input terminal I9 of the braking energy feedback module is connected to the high potential line H of the high-voltage DC bus, the input terminal O6 is connected to the positive electrode of the power battery, and O7 is connected to the positive electrode of the supercapacitor.

[0006] Further improvements are as follows: the forward bootstrap boost module includes a Boost converter 1, a Boost converter 2, a storage capacitor, a negative temperature coefficient thermistor, a diode 1, a diode 2 and a filter capacitor; the Boost converter 1 includes an inductor 1 and a power switch tube 1; the Boost converter 2 includes an inductor 2 and a power switch tube 2.

[0007] Further improvements are as follows: the input terminal I1 is a terminal of the inductor 1, the other terminal of the inductor 1 is connected to the drain of the power switch tube 1 and one end of the switch capacitor, and the other end of the switch capacitor is connected to the positive electrode of the diode 1; the input terminal I2 is a terminal of the inductor 2, the other terminal of the inductor 2 is connected to the drain of the power switch tube 2 and the positive electrode of the diode 5, the negative electrode of the diode 5 is connected to one end of the negative temperature coefficient thermistor, and the other end of the negative temperature coefficient thermistor is connected to the positive electrode of the diode 1; the input terminal I3 is connected to the positive electrode of the supercapacitor. The output terminal O1 is the negative terminal of the diode 1; the output terminal O2 is a terminal connected to the negative electrode of the fuel cell, the negative electrode of the power battery, the negative electrode of the supercapacitor, the source of the power switch tube 1, and the source of the power switch tube 2, and is connected to the low potential line L of the DC high voltage bus; one end of the filter capacitor is connected to the output terminal O1, and the other end is connected to the output terminal O2.

[0008] A further improvement is that the auxiliary energy source charging module includes an inductor 2, an inductor 3, a power switch tube 2, a power switch tube 3, a power switch tube 6, a power switch tube 8, a diode 4, and a diode 3.

[0009] Further improvements are as follows: the input terminal I7 is the source terminal of the power switch tube 9, the drain of the power switch tube 9 is connected to the drain of the power switch tube 8, the source of the power switch tube 8 is connected to the positive electrode of the diode 3, and the negative electrode of the diode 3 is connected to one end of the inductor 3; the input terminal I8 is the drain of the power switch tube 7, and the source of the power switch tube 7 is connected to the drain of the power switch tube 8 and one end of the inductor 2. The output terminal O6 is the source of the power switch tube 2, and the output terminal O7 is the other end of the inductor 3.

[0010] A further improvement is that the input energy source control module includes a power switch tube 4 , a power switch tube 7 , a power switch tube 9 , and a diode 2 .

[0011] Further improvements are as follows: the input terminals I4, I5, and I6 are respectively the positive electrode of the diode 2, the drain of the power switch tube 7, and the drain of the power switch tube 4, the negative electrode of the diode 2 is connected to the source of the power switch tube 9, and the drain of the power switch tube 9 is connected to the source of the power switch tube 7 and one end of the inductor 2; the output terminals O3, O4, and O5 are respectively the negative electrode of the diode 2, the source of the power switch tube 7, and the drain of the power switch tube 4.

[0012] Further improvements are as follows: the converter controller includes a hardware part and a software part; the hardware part generally includes a microprocessor, a signal detection circuit and a power switch tube trigger circuit; the software part mainly includes a data detection processing module, a working mode judgment selection module, an input energy source selection control module, a control algorithm module and a trigger pulse output module.

[0013] Further improvements are as follows: the basic steps of the software part are: the data detection processing module processes the signals detected by the hardware part, the current, the voltage and the energy distribution provided by the upper energy management system accordingly; the working mode judgment and selection module determines that the working mode of the integrated DC-DC converter is mainly divided into three categories, including power supply to the load, power supply to the load and energy, and load feedback. Among them, the power supply mode for the load includes: 1. The fuel cell supplies power alone; 2. The power battery supplies power alone; 3. The fuel cell and the power battery supply power together; 4. The fuel cell and the supercapacitor supply power together; 5. The power battery and the supercapacitor supply power together; 6. The three energy sources supply power together. Supplying power to the load and the energy together includes: 1. The fuel cell supplies power to the load and the supercapacitor at the same time; 2. The fuel cell supplies power to the load and the power battery at the same time; 3. The fuel cell supplies energy to the three at the same time; 4. The power battery supplies energy to the load and the supercapacitor at the same time; 5. The fuel cell and the power battery supply energy to the supercapacitor and the load together; the load feedback category includes: 1. The load feeds back to the supercapacitor alone; 2. The load supplies energy to the supercapacitor and the power battery together; 3. The load supplies energy to the power battery alone. There are 14 working modes in total.

[0014] A further improvement is that the converter controller realizes integrated control of the forward bootstrap boost module, the input energy source control module, the auxiliary energy source charging module, and the braking energy feedback module, thereby realizing integrated control of the integrated DC-DC converter, without the need to switch between the control strategies of the independent DC-DC converters as in the traditional way, and there is no situation where the dynamic response of the converter may be deteriorated or even worsened due to switching.

[0015] Compared with the prior art, the present invention has the following advantages: the present invention adopts an integrated DC-DC converter with a unique layout, which does not require the use of a costly isolation transformer and can reduce at least 3 isolation transformers and 15 power switch tubes, thereby reducing both weight and volume, effectively reducing the cost of the fuel cell vehicle electric drive system and energy consumption. At the same time, it has the functions of power supply, charging, and feedback of braking energy, provides 14 different working modes, and can adapt to a variety of vehicle operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1A schematic diagram of the structure of an integrated DC-DC converter for a three-energy-source fuel cell hybrid vehicle provided by an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of an integrated DC-DC converter circuit for a three-energy-source fuel cell hybrid vehicle provided by an embodiment of the present invention;

[0019] Figure 3 A flowchart for determining the operating mode of an integrated DC-DC converter of a three-energy source fuel cell hybrid vehicle provided in an embodiment of the present invention, wherein (a) is a flowchart when the bus power is negative, (b) is a flowchart when the bus power is zero, and (c) is a flowchart when the bus power is positive.

[0020] Figure 4 Schematic diagram of the topological structure of the integrated DC-DC converter in fourteen working modes provided by an embodiment of the present invention, wherein (a) is mode 1: the fuel cell supplies power to the load alone, (b) is mode 2: the power battery supplies power to the load alone, (c) is mode 3: the fuel cell and the power battery supply power to the load together, (d) is mode 4: the fuel cell and the supercapacitor supply power to the load together, (e) is mode 5: the power battery and the supercapacitor supply power to the load together, (f) is mode 6: the three energy sources supply power to the load together, (g) is mode 7: the fuel cell charges the supercapacitor, (h) is mode 8: the fuel cell charges the power battery, (i) is mode 9: the fuel cell charges the supercapacitor and the power battery, (j) is mode 10: the power battery supplies energy to the supercapacitor, (k) is mode 11: the fuel cell and the power battery supply energy to the supercapacitor and the load together, (l) is mode 12: the braking energy is fed back to the supercapacitor alone, (m) is mode 13: the braking energy is fed back to the supercapacitor and the power battery at the same time, and (n) is mode 14: the braking energy is fed back to the power battery;

[0021] Figure 5 This is the DC-DC topology diagram of a traditional three-energy fuel cell vehicle. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "installed" or "integrally connected" may refer to mechanical connection or electrical connection; it may refer to direct connection or indirect connection through an intermediate medium, or it may refer to the internal connection of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances. In addition, when the components and lines in the provided circuit diagram are gray, it indicates that the related circuit is blocked.

[0024] See also Figure 1 , Figure 2 , Figure 3 , Figure 4 The embodiment of the present invention discloses a three-energy source fuel cell vehicle integrated DC-DC converter, including a forward bootstrap boost module, an input energy source control module, an auxiliary energy source charging module, a braking energy feedback module and a converter controller. The forward bootstrap boost module is connected to the output terminals O3, O4, and O5 of the input energy source control module through input terminals I1, I2, and I3, and is connected to the high potential line H and the low potential line L of the high voltage DC bus through output terminals O1 and O2; the input energy source control module is connected to the fuel cell (U1) through input terminals I4, I5, and I6. FB )、Power battery (U B )、Supercapacitor(U UC ) is connected to the positive electrode of the high-voltage DC bus, and is connected to the input terminals I1, I2, and I3 of the forward bootstrap boost module through the output terminals O3, O4, and O5; the input terminal I7 of the auxiliary energy source charging module is connected to the positive electrode of the fuel cell, and I8 is connected to the positive electrode of the power battery, and the output terminal O6 is connected to the positive electrode of the power battery, and O7 is connected to the positive electrode of the supercapacitor; the input terminal I8 of the braking energy feedback module is connected to the high potential line H of the high-voltage DC bus, the input terminal O6 is connected to the positive electrode of the power battery, and O7 is connected to the positive electrode of the supercapacitor.

[0025] The forward bootstrap boost module includes Boost converter 1, Boost converter 2, BOOST converter 3, a switch capacitor (C1), a negative temperature coefficient thermistor (R1), a diode 1 (D1), a diode 5 (D5) and a filter capacitor (C0); Boost converter 1 includes an inductor 1 (L1) and a power switch tube 1 (S1); Boost converter 2 includes an inductor 2 (L2) and a power switch tube 2 (S2); Boost converter 3 includes an inductor 3 (L3) and a power switch tube 5 (S5).

[0026] The input terminal I1 is one terminal of the inductor 1 (L1), the other terminal of the inductor 1 (L1) is connected to the drain of the power switch tube 1 (S1) and one end of the switch capacitor (C1), and the other end of the switch capacitor (C1) is connected to the positive electrode of the diode 2 (D2); the input terminal I2 is one terminal of the inductor 2 (L2), the other terminal of the inductor 2 (L2) is connected to the drain of the power switch tube 2 (S2) and the positive electrode of the diode 1 (D1), the cathode of the diode 1 (D1) is connected to one end of the negative temperature coefficient thermistor (R1), and the other end of the negative temperature coefficient thermistor (R1) is connected to the diode 2 (D2) is connected to the positive electrode; the output terminal O1 is the negative terminal of the diode 2 (D2); the input terminal I3 is a terminal of the inductor 3 (L3), and the other terminal of the inductor 3 (L3) is connected to the drain of the switch tube 4 (S4) and the source of the switch tube S4; the output terminal O2 is a terminal connected with the negative electrode of the fuel cell, the negative electrode of the power battery, the source of the power switch tube 1 (S1), the source of the power switch tube 2 (S2), and the source of the power switch tube 4 (S4), and is connected to the low potential line L of the DC high voltage bus; one end of the filter capacitor is connected to the output terminal O1, and the other end is connected to the output terminal O2.

[0027] The auxiliary energy source charging module includes an inductor 2 (L2), an inductor 3 (L3), a power switch tube 2 (S2), a power switch tube 3 (S3), a diode 3 (D3), a diode 4 (D4), and a power switch tube 6 (S6).

[0028] Input terminal I7 is the source terminal of power switch tube 9, the drain of power switch tube 9 is connected to one end of inductor 2, the other end of inductor 2 is connected to the drain of power switch tube 2 (S2) and the drain of switch tube 6 (S6), the source of power switch tube 6 (S6) is connected to the positive electrode of diode 4 (D4); input terminal I8 is the drain of power open tube 7 (S7), the source of open tube 7 is connected to the drain of open tube 8 (S8), the source of open tube 8 is connected to the positive electrode of diode 3 (D3), and the cathode of diode 3 is connected to one terminal of inductor 3; output terminal O6 is the other end of inductor 3 (L3); output terminal O7 is the cathode of diode D4.

[0029] The braking energy feedback module includes a power switch tube 3 (S3), a power switch tube 5 (S5), a diode 4 (D4), an inductor 2 (L2), an inductor 3 (L3), and a load capacitor (C0).

[0030] Input terminal I9 is ​​the drain terminal of power switch tube 5 (S5) and the drain terminal of switch tube 3 (S3). The source of power switch tube 5 (S5) is connected to the drain of power switch tube 2 (S2) and one end of inductor L2. The other end of inductor L2 is connected to the source of power switch tube 7 (S7); the source of power switch tube 3 (S3) is connected to the drain of inductor 3 (L3) and switch tube 4 (S4). Output terminal O6 is the drain of power switch tube 7 (S7); output terminal O7 is the other end of inductor L2.

[0031] The input energy source control module includes a power switch tube 4 (S4), a power switch tube 7 (S7), a power switch tube 9 (S9), and a power diode 2 (D2).

[0032] Input terminals I4, I5, and I6 are respectively the positive electrode of diode 2 (D2), the source terminal of power switch tube 7 (S7), and one end of inductor 3 (L3); diode 2 (D2) is connected to the drain of power switch tube 9 (S9), and the source of power switch tube 9 (S9) is connected to the source of power switch tube 7 (S7); the other end of inductor 3 (L3) is connected to the drain of power switch tube 4 (S4); output terminals O3, O4, and O5 are respectively the drain of power switch tube 1 (S1), the drain terminal of power switch tube 2 (S2), and the drain terminal of power switch tube 4 (S4).

[0033] The converter controller includes a hardware part and a software part; the hardware part generally includes a microprocessor, a signal detection circuit and a power switch tube trigger circuit; the software part mainly includes a data detection and processing module, a working mode judgment and selection module, an input energy source selection control module, a control algorithm module and a trigger pulse output module.

[0034] The basic steps of the software part are: the data detection and processing module processes the signals (current, voltage) detected by the hardware part and the energy distribution provided by the upper energy management system accordingly; the working mode judgment and selection module determines the working mode of the integrated DC-DC converter (14 working modes: mainly divided into three categories, including power supply to the load, power supply to the load and energy, and load feedback. Among them, the power supply mode for the load includes: 1. Fuel cell power supply alone; 2. Power battery power supply alone; 3. Fuel cell and power battery power supply together; 4. Fuel cell and supercapacitor power supply together; 5. Power battery and supercapacitor power supply together; 6. Three energy sources power supply together. Powering the load and energy together includes: 1. The fuel cell powers the load and the supercapacitor at the same time; 2. The fuel cell powers the load and the power battery at the same time; 3. The fuel cell powers all three at the same time ; 4. The power battery supplies energy to the load and the supercapacitor at the same time; 5. The fuel cell and the power battery jointly supply energy to the supercapacitor and the load; The load feedback category includes: 1. The load alone feeds back to the supercapacitor; 2. The load jointly supplies energy to the supercapacitor and the power battery; 3. The load alone supplies energy to the power battery); Then the input energy source selection control module sends a control signal according to the determined working mode, and the trigger circuit controls the gate of the power switch tube to implement corresponding on or off control on them to select the input energy source; The control algorithm module executes the corresponding control algorithm according to the detected signal and working mode to obtain the trigger pulse duty cycle, and the trigger pulse output module sends a control signal, and the trigger circuit controls the power switch tube 4 (S4), power switch tube 6 (S6) and power switch tube 7 (S7), and implements corresponding on or off control on them, so that the integrated converter runs the corresponding working mode. The converter controller realizes integrated control of the forward bootstrap boost module, the input energy source control module, the auxiliary energy source charging module, and the braking energy feedback module, thereby realizing integrated control of the integrated DC-DC converter. There is no need to switch between the control strategies of the independent DC-DC converters as in the traditional way, and there is no situation where the dynamic response of the converter may be deteriorated or even worsened due to switching.

[0035] Figure 2 The operation of the four power switch tubes S5, S6, S7, and S8 of the input energy source control module controls the fuel cell (main energy source, U FB Indicates), power battery (auxiliary energy source, U B Indicates), supercapacitor (auxiliary energy source, U UCTable 1 shows the working conditions of each energy source after controlling different switch combinations. Power switch tubes S6, S7, S8, and S9 can use IGBT power switch devices with lower switching frequency, higher power, and lower cost; power switch tubes S1, S2, S3, S4, and S5 can use silicon carbide MOSFET power switch devices with high switching frequency, high voltage and current resistance, low impedance, and low power consumption. Through the control of the power switch tube, the integrated converter has fourteen working modes, which are analyzed in detail as follows. Note: Figure 4 The gray lines and devices in the figure represent the disconnected state, with no current flowing.

[0036] Table 1 Input energy source control switch combination

[0037]

[0038] Mode 1: When the power required by the vehicle is low and the fuel cell voltage is sufficient, the input energy control loop is configured to switch S A1 , S A2 and S UC1 and its anti-parallel diode are all turned off, S A2 The anti-parallel diode is turned on and the fuel cell is used to supply energy. The topology is as follows: Figure 4 (a) This working mode has three sub-modes:

[0039] Submode 1-1: Switch S FB Connected, but S B1 Close, inductor L FB Charging, while the inductor L B Discharge to capacitor C 1 , while C 0 Supply energy to the load. At this time:

[0040] U LB =U FB -U C1 -i R1 ·R 1

[0041] U LFB =U FB (1)

[0042] Among them U LB , U FB , U C1 , U LFB , respectively represent the inductance L B , fuel cell, capacitor C 1 、Inductance L FB The voltage across the two ends. R 1 is the thermistor, i R1 Represents the current flowing through the thermistor.

[0043] Submode 1-2: Switch S FB and S B1 Both are conducting, the inductor L FB and L B Charging, load R 0 Still by capacitor C 0 Energy supply. At this time:

[0044] U LB =U LFB =U FB (2)

[0045] Submode 1-3: Switch S FB Close, S B1 On, inductor L FB Give C 1 Power supply, inductor L B Charging, the load is R 0 By capacitor C 0 With capacitor C 1 Joint energy supply. At this time:

[0046] U LB =U FB

[0047] U LFB =U FB +U C1 -U 0 (3)

[0048] Among them, U 0 Indicates the output voltage, U LFB Indicates the inductance L FB The voltage across both ends.

[0049] Mode 2: Its topology is as follows Figure 4 As shown in (b), when the power required by the vehicle is low and the fuel cell voltage is insufficient, and the power battery has sufficient power, the input energy control loop is configured to set S A1 and S A2 All on, D FB The reverse voltage shuts down the system and the power battery supplies the system energy. This working mode has three working sub-modes:

[0050] Submode 2-1: Switch S FB Connected, but S B1 Close, inductor L FB Charging, while the inductor L B Discharge to capacitor C 1 , while C 0 Supply energy to the load. At this time:

[0051] ULB =U B -U C1 -i R1 ·R 1

[0052] U LFB =U B (4)

[0053] Among them, U B Indicates the voltage across the power battery.

[0054] Submode 2-2: Switch S FB and S B1 Both are conducting, the inductor L FB and L B Charging, load R 0 Still by capacitor C 0 Energy supply. At this time:

[0055] U LB =U LFB =U B (5)

[0056] Submode 2-3: Switch S FB Close, S B1 On, inductor L FB Give C 1 Power supply, inductor L B Charging, the load is R 0 By capacitor C 0 With capacitor C 1 Joint energy supply. At this time:

[0057] U LB =U B

[0058] U LFB =U B +U C1 -U 0 (6)

[0059] Mode 3: Its topology is as follows Figure 4 As shown in (c), when the power required by the car is high and the fuel cell and the power battery have sufficient power, both of them supply energy at the same time. By configuring the input energy control loop to turn on SA1 and turn off SA2, the fuel cell and the power battery supply energy at the same time. This mode has four working sub-modes:

[0060] Submode 3-1: S FB On, S B1 Turn off. Inductor L FB Charging, L B Discharge to C 1 , capacitor C0 To load R 0 Power supply, at this time:

[0061] U LB =U B -U C1 -i R1 ·R 1

[0062] U LFB =U FB (7)

[0063] Submode 3-2: S FB , S B1 Both are conducting, inductance L FB , L B Charge the capacitor C 0 To load R 0 Power supply, at this time:

[0064] U LB =U B

[0065] U LFB =U FB (8)

[0066] Submode 3-3: S FB , S B1 are all turned off, the inductor L FB With C 1 Connect in parallel to supply power to the load, L B Discharge the switched capacitor, then:

[0067] U LB =U B -U C1 -i R1 ·R 1

[0068] U LFB =U FB +U C1 -U 0 (9)

[0069] Submode 3-4: S FB Shutdown, S B1 On, inductance L FB With C 1 Connect in parallel to supply power to the load, inductor L B Charging, at this time:

[0070] U LB =U B

[0071] U LFB =UFB +U C1 -U 0 (10)

[0072] Mode 4: Its topology is as follows Figure 4 As shown in (d), when the power required by the car is high and the fuel cell and supercapacitor have sufficient power, they are both used to supply energy at the same time. By configuring the input energy control loop, S A1 and S A2 All are shut down, and the fuel cell is the only power supply. At the same time, control S UC1 Connect the supercapacitor and fuel cell in parallel to provide energy. B and inductor L FB The working mode in this mode is the same as that in mode 1, so it will not be described here. UC There are two working sub-modes in this mode:

[0073] Submode 4-1: S UC1 Open, V UC To inductor L UC Charging, at this time:

[0074] U LUC =U UC (11)

[0075] Among them, U LUC Indicates the inductance L UC The voltage across the terminals, U UC Represents the voltage across the supercapacitor.

[0076] Submode 4-2: S UC1 Shutdown, V UC With inductance L UC The load is powered in series, at this time:

[0077] U LUC =U UC -U 0 (12)

[0078] Mode 5: Its topology is as follows Figure 4 As shown in (e), when the power required by the car is high and the power battery and supercapacitor have sufficient power, they both provide energy at the same time. By configuring the input energy control loop, S A1 and S A2 All are turned on, and the power battery is used to supply energy. UC1 The supercapacitor supplies energy. B and inductor L FB The operation mode in this mode is the same as that in mode 2. The inductor L UC There are two working sub-modes in this mode which are similar to Mode 4, so they will not be described here.

[0079] Mode 6: Its topology is as follows Figure 4 As shown in (f), when the car accelerates, and the fuel cell, power battery and supercapacitor have sufficient energy storage, the three are powered at the same time, and the input energy control loop is configured to control S A1 Open S A2 Shut down, the fuel cell and power battery are used for power supply at the same time. UC1 The supercapacitor supplies energy. B and inductor L FB The operation mode in this mode is the same as that in mode 3. UC The two working sub-modes in this mode are also similar to those in mode 4, so they will not be described in detail here.

[0080] Mode 7: Its topology is as follows Figure 4 As shown in (g), when the car is in standby mode and the fuel cell voltage is sufficient and the supercapacitor power is low, the input energy control loop is configured to A1 and S A2 All are shut down, powered by the fuel cell alone, and S CL loop, the inductor passes through S UC1 The BUCK circuit is formed to charge the supercapacitor. There are two sub-modes in this working mode:

[0081] Submode 7-1: S CL1 The fuel cell also supplies the inductor LU C and V UC Charging, at this time:

[0082] U LUC =U FB -U UC (13)

[0083] Submode 7-2: S CL1 Turn off, inductor L UC By S UC1 Continue to flow and charge the supercapacitor at the same time. At this time:

[0084] U LUC =U UC (14)

[0085] Mode 8: Its topology is as follows Figure 4 As shown in (h), when the car is in standby mode and the fuel cell voltage is sufficient and the power battery voltage is low, the input energy control loop is configured to A1 and S A2 All are shut down, powered by the fuel cell alone, and S CB loop, the inductor passes through S B1The BOOST circuit is constructed to charge the power battery. This working mode has the following two working sub-modes:

[0086] Submode 8-1: S UC1 The power battery charges the inductor LB. At this time:

[0087] U LB =U FB (15)

[0088] Submode 8-2: S UC1 Shut down, power battery in series L B At the same time, charge the power battery.

[0089] U LB =U FB -U B (16)

[0090] Mode 9: Its topology is as follows Figure 4 As shown in (i), when the car is in standby mode and the fuel cell voltage is sufficient and the power battery and supercapacitor voltage are low, the input energy control loop is configured to A1 and S A2 All are shut down, powered by the fuel cell alone, and S CB Loop and S CL Power supply circuit, inductor through S UC1 The BUCK circuit is formed to charge the supercapacitor through S B1 and L B The BOOST circuit is formed to charge the power battery. UC The working submode is the same as that in mode 7, L B The sub-mode of is the same as the working sub-mode of mode 8, so it will not be repeated here.

[0091] Mode 10: Its topology is as follows Figure 4 As shown in (j), when the car is in standby mode, and the fuel cell and supercapacitor have insufficient energy storage, but the power battery has sufficient energy, the input energy control loop is configured to switch S A1 and S A2 All are turned on, and the power battery is used alone for power supply. CL loop, the inductor passes through S UC1 The BUCK circuit is formed to charge the supercapacitor. Its working sub-mode is similar to that in mode 7, only the input source is different, so it will not be repeated.

[0092] Mode 11: Its topology is as follows Figure 4 As shown in (k), when the car is in idling state, and the fuel cell and power battery have sufficient energy storage, but the supercapacitor has insufficient energy storage, the input energy control loop is configured toA1 Open S A2 Close, and the power battery and fuel cell will be used together to supply energy. CL loop, the inductor passes through S UC1 The BUCK circuit is formed to charge the supercapacitor. This working mode has the following four sub-modes:

[0093] Submode 11-1: S FB On, S B1 While shutting down S CL Conductive. Inductor L FB Charging, L B Discharge to C 1 , the power battery also supplies L UC And super capacitor power supply, capacitor C 0 To load R 0 Power supply, at this time:

[0094] U LB =U B -U C1 -i R1 ·R 1

[0095] U LFB =U FB

[0096] U LUC =U B -U UC (17)

[0097] Submode 11-2: S FB , S B1 Both are conducting, S CL Turn off. Inductor L FB , L B Charge separately, L UC By S UC1 The diode freewheels, the capacitor C 0 To load R 0 Power supply, at this time:

[0098] U LB =U B

[0099] U LFB =U FB

[0100] U LUC =U UC (18)

[0101] Submode 11-3: S FB , S B1 All are turned off, S CLOn, inductance L FB With C 1 Connect in parallel to supply power to the load, L B Discharge to the switch capacitor, the power battery also discharges to L UC And super capacitor power supply, at this time:

[0102] U LB =U B -U C1 -i R1 ·R 1

[0103] U LFB =U FB +U C1 -U 0

[0104] U LUC =U B -U UC (19)

[0105] Submode 11-4: S FB Shutdown, S B1 On, S CL Turn off, inductor L FB With C 1 Connect in parallel to supply power to the load, inductor L B Charging, L UC By S UC1 The diode is freewheeling, at this time:

[0106] U LB =U B

[0107] U LFB =U FB +U C1 -U 0

[0108] U LUC =U UC (20)

[0109] Mode 12: Its topology is as follows Figure 4 As shown in (l), due to the fast charging and discharging characteristics of the supercapacitor, when the supercapacitor is not fully charged, the energy is fed back to the supercapacitor first. UC2 , S UC1 With L UC The BUCK circuit is formed to supply power to the supercapacitor. This working mode has two working sub-modes:

[0110] Submode 12-1: S UC2 When the brake is turned on, the feedback energy from braking is supplied to both the LUC and the supercapacitor. At this time:

[0111] U LUC =U C0 -U UC (twenty one)

[0112] Submode 12-2: S UC2 Shutdown, L UC By S UC1 The anti-parallel diode is freewheeling, at this time:

[0113] U LUC =U UC (twenty two)

[0114] Mode 13: Its topology is as follows Figure 4 As shown in (m), when the supercapacitor is not fully charged, the load supplies energy to the supercapacitor and the power battery at the same time. UC2 , S UC1 With L UC The BUCK circuit is formed to supply power to the supercapacitor. F and inductor L B The BUCK circuit is formed to charge the power battery. This working mode has two working sub-modes:

[0115] Submode 13-1: S UC2 On, S F Turn off, brake feedback energy to L UC And supercapacitor power supply, L B By S B1 The anti-parallel diode is freewheeling, at this time:

[0116] U LUC =U C0 -U UC

[0117] U LB =U B (twenty three)

[0118] Submode 13-2: S UC2 Shutdown, S F conduction, braking feedback capacity to L B And power battery, L UC By S CL1 The parallel diode of the rice is freewheeling, at this time:

[0119] U LUC =U UC

[0120] U LB =U C0 -U B (twenty four)

[0121] Mode 14: Its topology is as follows Figure 4 As shown in (n), when the supercapacitor is fully charged, the load is powered by the power battery alone. F and inductor L B The BUCK circuit is formed to charge the power battery. This working mode has two working sub-modes:

[0122] Submode 14-1: S F Shutdown, L B By S B1 The anti-parallel diode is freewheeling, at this time:

[0123] U LB =U B (twenty three)

[0124] Submode 14-2: S F conduction, braking feedback capacity to L B And power battery power supply, at this time:

[0125] U LB =U C0 -U B (twenty four)

[0126] Compared with traditional DC / DC converters such as Figure 5 As shown, this is a common independent configuration mode of DC-DC converters in fuel cell hybrid electric vehicles, that is, the main energy source is connected to a unidirectional DC-DC converter, and the auxiliary energy source is connected to a bidirectional DC-DC converter. The two converters are each configured with a controller. Its basic working mode is: through the control of the controller, the main and auxiliary energy sources supply power to the high-voltage DC bus load through the DC-DC converters connected to them respectively, or the main energy source or the auxiliary energy source can be independently powered, or the main energy source can charge the auxiliary energy source, or the braking energy can be fed back to the auxiliary energy source.

[0127] From the detailed analysis of the above embodiments of the present invention, it can be seen that the present invention has an equivalent effect as the comparative example in terms of the flow of electric energy in the vehicle power system, and has all the functions of a traditional commonly used DC-DC converter system, and has the following main advantages: a unique structural layout and design, forming an integrated converter of a non-isolated multi-port topology with high integration, high power density, and fewer power devices, having good high-gain output characteristics and low ripple current, without the need to use a costly isolation transformer, and being able to reduce at least 3 isolation transformers and 11 power switching tubes, with both weight and volume reduced, effectively reducing the cost of the fuel cell vehicle electric drive system and reducing energy consumption, while having the functions of power supply, charging, and feedback of braking energy, providing five different working modes, and being able to adapt to a variety of vehicle operating conditions.

[0128] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-energy source fuel cell vehicle integrated DC-DC converter, comprising a forward bootstrap boost module, an input energy source control module, an auxiliary energy source charging module, a braking energy feedback module and a converter controller, characterized in that: The forward bootstrap boost module is connected to the output terminals O3, O4, O5 of the input energy source control module through the input terminals I1, I2, I3, and is connected to the high potential line H and the low potential line L of the high voltage DC bus through the output terminals O1 and O2; the input energy source control module is connected to the positive electrodes of the fuel cell, the power battery, and the supercapacitor through the input terminals I4, I5, I6, respectively, and is connected to the input terminals I1, I2, I3 of the forward bootstrap boost module through the output terminals O3, O4, O5; the auxiliary energy source The input terminal I7 of the charging module is connected to the positive electrode of the fuel cell, I8 is connected to the positive electrode of the power battery, the output terminal O6 is connected to the positive electrode of the power battery, and O7 is connected to the positive electrode of the supercapacitor; the input terminal I9 of the braking energy feedback module is connected to the high potential line H of the high-voltage DC bus, the input terminal O6 is connected to the positive electrode of the power battery, and O7 is connected to the positive electrode of the supercapacitor, and the converter controller integrates the control of the forward bootstrap boost module, the input energy source control module, the auxiliary energy source charging module, and the braking energy feedback module.

2. A three-energy source fuel cell vehicle integrated DC-DC converter according to claim 1, characterized in that: The forward bootstrap boost module includes Boost converter 1, Boost converter 2, Boost converter 3, diode 1, diode 5 and filter capacitor C1. The Boost converter 1 includes inductor 1 and power switch tube 1. The Boost converter 2 includes inductor 2 and power switch tube 2. The Boost converter 3 includes inductor 3, power switch tube 4 and power switch tube 5.

3. A three-energy source fuel cell vehicle integrated DC-DC converter according to claim 2, characterized in that: The input terminal I1 is a terminal of the inductor 1, and the other terminal of the inductor 1 is connected to the drain of the power switch tube 1 and one end of the energy storage capacitor; the input terminal I2 is a terminal of the inductor 2, and the other terminal of the inductor 2 is connected to the drain of the power switch tube 2 and the positive electrode of the diode 5; the input terminal I3 is a terminal of the inductor 3, and the other terminal of the inductor 3 is connected to the drain of the power switch tube 4 and the source of the power switch tube 5; the output terminal O1 is the parallel output end of the power switch tube 5 and the diode 1; the output terminal O2 is a terminal connected to the negative electrode of the fuel cell, the negative electrode of the power battery, the negative electrode of the supercapacitor, the source of the power switch tube 1, the source of the power switch tube 2, and the source of the power switch tube 4, and is connected to the low potential line L of the DC high-voltage bus; one end of the filter capacitor is connected to the output terminal O1, and the other end is connected to the output terminal O2.

4. The three-energy-source fuel cell vehicle integrated DC-DC converter according to claim 1, characterized in that: The use of the negative temperature coefficient thermistor effectively suppresses the surge current of the integrated converter during the transition process.

5. The three-energy-source fuel cell vehicle integrated DC-DC converter according to claim 1, characterized in that: The auxiliary energy source charging module includes an inductor 2, an inductor 3, a power switch tube 2, a power switch tube 3, a power switch tube 6, a power switch tube 7, a diode 3, and a diode 4.

6. The three-energy-source fuel cell vehicle integrated DC-DC converter according to claim 5, characterized in that: The input terminal I7 is the positive electrode of the diode 2, and the negative electrode of the diode 2 is connected to the source of the power switch tube 9 and one end of the inductor 1; the drain of the power switch tube 9 is connected to one end of the inductor 2, and the other end is connected to the drain of the power switch tube 2 and the positive electrode of the diode 5; the source of the power switch tube 7 is connected to the drain of the power switch tube 8, the drain of the power switch tube 8 is connected to the positive electrode of the diode 3, and the negative electrode of the diode 3 is connected to one end of the inductor 3; the output terminal O6 is the negative terminal of the diode 4, and O7 is the other end of the inductor 3.

7. The three-energy-source fuel cell vehicle integrated DC-DC converter according to claim 1, characterized in that: The braking energy feedback module includes a power switch tube 2 , a power switch tube 3 , a power switch tube 4 , a power switch tube 5 , a power switch tube 7 , an inductor 2 and an inductor 3 .

8. The three-energy-source fuel cell vehicle integrated DC-DC converter according to claim 1, characterized in that: The input terminal I9 is ​​the drain end of the power switch tube 3 and the power switch tube 5 in parallel, the source of the power switch tube 3 is connected to the inductor 2 and the drain of the power switch tube 2, and the other end of the inductor 2 is connected to the source of the power switch tube 7; the source of the power switch tube 5 is connected to the drain of the inductor 3 and the power switch tube 4 respectively; the output terminal O6 is the drain of the power switch tube 7; the output terminal O7 is the other side of the inductor 3.

9. The three-energy-source fuel cell vehicle integrated DC-DC converter according to claim 1, characterized in that: The input energy source control module includes a power switch tube 4 , a power switch tube 7 , a power switch tube 9 , and a diode 2 .

10. The three-energy-source fuel cell vehicle integrated DC-DC converter according to claim 1, characterized in that: The input terminals I4, I5, and I6 are respectively the positive electrode of the diode 2, the source of the power switch tube 7, and the source of the power switch 4; the source of the power switch tube 7 is connected to the drain of the power switch tube 9 and one end of the inductor 2, and the source of the power switch tube 9 is connected to the negative electrode of the diode 2; the output terminals O3, O4, and O5 are respectively the negative electrode of the diode 2, the source end of the power switch tube 7, and the drain end of the power switch tube 4.

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