Hybrid electric vehicle power supply system based on three-port DC/DC converter
阅读说明：本技术 一种基于三端口dc/dc变换器的混合动力汽车供电系统 (Hybrid electric vehicle power supply system based on three-port DC/DC converter ) 是由 吴晓刚 张磊 于 2021-08-13 设计创作，主要内容包括：一种基于三端口DC/DC变换器的混合动力汽车供电系统,属于电动汽车供电技术领域。本发明解决了燃料电池混合动力汽车在低温环境下,动力电池将面临无法充电,放电能力差的问题。本发明包括三端口DC/DC变换器、动力电池、电池加热膜、燃料电池Uin和变换器控制电路；三端口DC/DC变换器的三个端口分别连接电池加热膜的供电端、燃料电池的电源端和驱动电机控制器的供电端；变换器控制电路用于控制三端口DC/DC变换器中开关管的开关,使三端口DC/DC变换器处于不同的工作模式；所述电池加热膜设置在动力电池的外侧,用于为动力电池加热；本发明适用于混合动力汽车供电。(A hybrid electric vehicle power supply system based on a three-port DC/DC converter belongs to the technical field of electric vehicle power supply. The invention solves the problems that the power battery of the fuel cell hybrid electric vehicle can not be charged and has poor discharging power in a low-temperature environment. The invention comprises a three-port DC/DC converter, a power battery, a battery heating film, a fuel battery Uin and a converter control circuit; three ports of the three-port DC/DC converter are respectively connected with a power supply end of a battery heating film, a power supply end of a fuel battery and a power supply end of a driving motor controller; the converter control circuit is used for controlling the switch of a switch tube in the three-port DC/DC converter to enable the three-port DC/DC converter to be in different working modes; the battery heating film is arranged on the outer side of the power battery and used for heating the power battery; the invention is suitable for power supply of hybrid electric vehicles.)
1. The hybrid electric vehicle power supply system based on the three-port DC/DC converter is characterized by comprising a three-port DC/DC converter, a power battery, a battery heating film UO2, a fuel battery Uin and an converter control circuit;
three ports of the three-port DC/DC converter are respectively connected with a power supply end of a battery heating film, a power supply end of a fuel battery and a power supply end of a driving motor controller;
the converter control circuit is used for controlling the switch of a switch tube in the three-port DC/DC converter to enable the three-port DC/DC converter to be in different working modes;
the battery heating film UO2 is arranged on the outer side of the power battery and used for heating the power battery;
the three-port DC/DC converter includes: the Buck-Boost converter comprises a front-end Buck chopper circuit, a rear-end Buck-Boost chopper circuit and an input capacitor Cin;
the front-end Buck chopper circuit includes: a switching tube Q2, a diode D2, an inductor L2 and a capacitor C2;
the back-end Buck-Boost chopper circuit comprises: a switching tube Q1, a diode D1, a capacitor C1 and an inductor L1;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of the input capacitor Cin is connected with the drain electrode of the switching tube Q2, and the other end of the input capacitor Cin is connected with the anode of the diode D2;
the source of the switching tube Q2 is connected with the cathode of the diode D2;
the drain of the switching tube Q2 is further connected with the drain of the switching tube Q1, the source of the switching tube Q1 is connected with the cathode of the diode D1, the cathode of the diode D1 is further connected with one end of the inductor L1, the other end of the inductor L1 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with one end of the inductor L2, and the other end of the inductor L2 is connected with the source of the switching tube Q2;
two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
the anode of the diode D1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is connected with the other end of the inductor L1;
one end of the capacitor C2 is also connected with the anode of the diode D2;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller.
2. The three-port DC/DC converter based hybrid vehicle power supply system according to claim 1, wherein the operation mode of the three-port DC/DC converter includes: a single-input single-output mode and a single-input dual-output mode.
3. The hybrid electric vehicle power supply system based on the three-port DC/DC converter according to claim 2, characterized in that the three-port DC/DC converter has a single input and a single output mode, including a mode a and a mode b, in which the fuel cell individually supplies power to the battery heating film in the mode a and individually supplies power to the motor controller in the mode b;
in the mode a: the switching tube Q2 is controlled by the PWM signal, and the switching tube Q1 is kept off;
tonthe state is as follows: the switching tube Q2 is in a conducting state, and the equivalent circuit comprises: the input capacitor Cin, the switching tube Q2, the inductor L2 and the capacitor C2;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of an input capacitor Cin is connected with the drain electrode of the switch tube Q2, the other end of the input capacitor Cin is connected with one end of a capacitor C2, the other end of a capacitor C2 is connected with one end of an inductor L2, the other end of the inductor L2 is connected with the source electrode of a switch tube Q2, and two ends of a capacitor C2 are connected with two ends of a battery heating film UO 2;
toffthe state is as follows: the switching tube Q2 is in the off state, and the equivalent circuit includes: an input capacitor Cin, an inductor L2, a diode D2 and a capacitor C2;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
the anode of the diode D2 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with one end of the inductor L2, and the other end of the inductor L2 is connected with the cathode of the diode D2; two ends of the capacitor C2 are respectively connected with two power supply ends of the battery heating film;
mode b:
the switching tube Q1 is controlled by the PWM signal, and the switching tube Q2 is kept off;
tonthe state is as follows: the switching tube Q1 is in a conducting state, and the equivalent circuit comprises: the input capacitor Cin, the switching tube Q1, the inductor L1 and the capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
one end of the input capacitor Cin is also connected with the drain electrode of the switching tube Q1, the source electrode of the switching tube Q1 is connected with one end of the inductor L1, and the other end of the inductor L1 is connected with the other end of the input capacitor Cin; two ends of the capacitor C1 are respectively connected with two power supply ends of the motor controller;
toffthe state is as follows: the switching tube Q1 is in the off state, and the equivalent circuit includes: input capacitor Cin, diode D1, inductorL1 and capacitance C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
one end of the inductor L1 is connected with the cathode of the diode D1, the anode of the diode D1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is connected with the other end of the inductor L1; two ends of the capacitor C1 are also respectively connected with two power supply ends of the motor controller.
4. The hybrid electric vehicle power supply system based on the three-port DC/DC converter according to claim 2, characterized in that when the three-port DC/DC converter is in a single-input dual-output mode, the fuel cell simultaneously supplies power to the battery heating film and the motor controller;
the switch tube Q1 and the switch tube Q2 are controlled by PWM signals;
t0in the state: the switching tube Q1 and the switching tube Q2 are in a conducting state;
the equivalent circuit includes: the input capacitor Cin, the switching tube Q1, the switching tube Q2, the inductor L2, the capacitor C2, the capacitor C1 and the inductor L1;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of the input capacitor Cin is connected with the drain electrode of the switching tube Q2, and the other end of the input capacitor Cin is connected with one end of the capacitor C2; the other end of the capacitor C2 is connected with one end of an inductor L2, and the other end of the inductor L2 is connected with the source electrode of a switching tube Q2;
the drain of the switching tube Q2 is further connected with the drain of the switching tube Q1, the source of the switching tube Q1 is connected with one end of an inductor L1, and the other end of the inductor L1 is connected with one end of a capacitor C2; two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller;
t1in the state: when the switch tube Q1 is in the off state and the switch tube Q2 is in the on state, the equivalent circuit includes: the circuit comprises an input capacitor Cin, a switching tube Q2, an inductor L2, a capacitor C2, an inductor L1, a capacitor C1 and a diode D1;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of the input capacitor Cin is connected with the drain electrode of the switching tube Q2, the source electrode of the switching tube Q2 is connected with one end of an inductor L2, the other end of the inductor L2 is connected with one end of a capacitor C2, and the other end of the capacitor C2 is connected with the other end of the input capacitor Cin;
two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
the anode of the diode D1 is connected with one end of the capacitor C1, the other end of the capacitor C1 is connected with one end of the inductor L1, the other end of the inductor L1 is connected with the cathode of the diode D1, and the two ends of the capacitor C1 are also connected with two power supply ends of the motor controller;
t2in the state: when the switch tube Q1 is in the on state, the switch tube Q2 is in the off state;
the equivalent circuit includes: an input capacitor Cin, a switching tube Q1, a diode D2, an inductor L2, a capacitor C2, an inductor L1 and a capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
one end of an input capacitor Cin is connected with the drain electrode of a switch tube Q1, the source electrode of a switch tube Q1 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a capacitor C2, the other end of the capacitor C2 is connected with one end of an inductor L2, the other end of the inductor L2 is connected with the cathode of a diode D2, and the anode of a diode D2 is connected with the other end of the inductor L1;
the anode of the diode D2 is also connected to the other end of the input capacitor Cin;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller;
t3in the state: the switching tube Q1 and the switching tube Q2 are in an off state;
the equivalent circuit includes: an input capacitor Cin, a diode D1, a diode D2, an inductor L2, a capacitor C2, an inductor L1 and a capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
the cathode of the diode D2 is connected with one end of the inductor L2, the other end of the inductor L2 is connected with one end of the capacitor C2, and the other end of the capacitor C2 is connected with the anode of the diode D2;
two ends of the capacitor C2 are respectively connected with two power supply ends of the battery heating film UO 2;
one end of the inductor L1 is connected with the cathode of the diode D1, the anode of the diode D1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is connected with the other end of the inductor L1;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller.
5. The hybrid electric vehicle power supply system based on the three-port DC/DC converter according to claim 2, characterized in that the specific control method of the converter control circuit is as follows:
s1, collecting real-time output voltage Uo2 of a front-stage Buck chopper circuit and real-time current of an inductor L2;
step S2, comparing the output voltage Uo2 with a reference voltage UrefComparing to obtain a voltage error signal e1, performing PI calculation on the voltage error signal e1 by using a voltage loop PI controller to obtain an expected inductor L2 current IL2ref；
Step S3, obtaining the expected current I of the inductor L2L2refComparing the current with the current of the inductor L2 acquired in the step one to acquire a current error signal e2, performing PI calculation on the current error signal e2 by adopting a current loop PI controller, and summing the current error signal with a feedforward controller k/Uin to acquire a duty ratio signal d; wherein k is a constant.
Technical Field
The invention belongs to the technical field of electric automobile power supply.
Background
The fuel cell hybrid electric vehicle is powered by mixing a fuel cell and a power cell. Compared with the traditional pure electric vehicle, the service life of the battery and the endurance mileage of the vehicle are prolonged; compared with a pure fuel cell automobile, the dynamic response speed of the system is improved, and power supply can be rapidly obtained when high power is needed for starting, accelerating rapidly, climbing steep slopes and the like. In addition, fuel cell hybrid power systems are adopted in fuel cell passenger cars, logistics cars, passenger cars and the like developed by the current mainstream whole-vehicle factories. Therefore, in the current new energy vehicle configuration, the fuel cell hybrid vehicle is an important development route.
When the fuel cell hybrid electric vehicle runs in a low-temperature environment, the power cell can not be charged, the discharging capability is poor, and the use is influenced.
Disclosure of Invention
The invention aims to solve the problems that a power battery of a fuel cell hybrid electric vehicle cannot be charged and has poor discharging capacity in a low-temperature environment, and provides a hybrid electric vehicle power supply system based on a three-port DC/DC converter.
The invention relates to a hybrid electric vehicle power supply system based on a three-port DC/DC converter, which comprises the three-port DC/DC converter, a power battery, a battery heating film UO2, a fuel battery UO and a converter control circuit;
three ports of the three-port DC/DC converter are respectively connected with a power supply end of a battery heating film, a power supply end of a fuel battery and a power supply end of a driving motor controller;
the converter control circuit is used for controlling the switch of a switch tube in the three-port DC/DC converter to enable the three-port DC/DC converter to be in different working modes;
the battery heating film UO2 is arranged on the outer side of the power battery and used for heating the power battery;
the three-port DC/DC converter includes: the Buck-Boost converter comprises a front-end Buck chopper circuit, a rear-end Buck-Boost chopper circuit and an input capacitor Cin;
the front-end Buck chopper circuit includes: a switching tube Q2, a diode D2, an inductor L2 and a capacitor C2;
the back-end Buck-Boost chopper circuit comprises: a switching tube Q1, a diode D1, a capacitor C1 and an inductor L1;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of the input capacitor Cin is connected with the drain electrode of the switching tube Q2, and the other end of the input capacitor Cin is connected with the anode of the diode D2;
the source of the switching tube Q2 is connected with the cathode of the diode D2;
the drain of the switching tube Q2 is further connected with the drain of the switching tube Q1, the source of the switching tube Q1 is connected with the cathode of the diode D1, the cathode of the diode D1 is further connected with one end of the inductor L1, the other end of the inductor L1 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with one end of the inductor L2, and the other end of the inductor L2 is connected with the source of the switching tube Q2;
two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
the anode of the diode D1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is connected with the other end of the inductor L1;
one end of the capacitor C2 is also connected with the anode of the diode D2;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller.
Further, in the present invention, the operation modes of the three-port DC/DC converter include: a single-input single-output mode and a single-input dual-output mode.
Furthermore, in the invention, the three-port DC/DC converter has a single-input single-output mode comprising a mode a and a mode b, wherein in the mode a, the fuel cell independently supplies power for the battery heating film, and in the mode b, the fuel cell independently supplies power for the motor controller;
in the mode a: the switching tube Q2 is controlled by the PWM signal, and the switching tube Q1 is kept off;
tonthe state is as follows: the switching tube Q2 is in a conducting state, and the equivalent circuit comprises: the input capacitor Cin, the switching tube Q2, the inductor L2 and the capacitor C2;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of an input capacitor Cin is connected with the drain electrode of the switch tube Q2, the other end of the input capacitor Cin is connected with one end of a capacitor C2, the other end of a capacitor C2 is connected with one end of an inductor L2, the other end of the inductor L2 is connected with the source electrode of a switch tube Q2, and two ends of a capacitor C2 are connected with two ends of a battery heating film UO 2;
toffthe state is as follows: the switching tube Q2 is in the off state, and the equivalent circuit includes: an input capacitor Cin, an inductor L2, a diode D2 and a capacitor C2;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
the anode of the diode D2 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with one end of the inductor L2, and the other end of the inductor L2 is connected with the cathode of the diode D2; two ends of the capacitor C2 are respectively connected with two power supply ends of the battery heating film; in the mode b, the switch tube Q1 is controlled by the PWM signal, and the switch tube Q2 is kept off;
tonthe state is as follows: the switching tube Q1 is in a conducting state, and the equivalent circuit comprises: the input capacitor Cin, the switching tube Q1, the inductor L1 and the capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
one end of the input capacitor Cin is also connected with the drain electrode of the switching tube Q1, the source electrode of the switching tube Q1 is connected with one end of the inductor L1, and the other end of the inductor L1 is connected with the other end of the input capacitor Cin; two ends of the capacitor C1 are respectively connected with two power supply ends of the motor controller;
toffthe state is as follows: the switching tube Q1 is in the off state, and the equivalent circuit includes: an input capacitor Cin, a diode D1, an inductor L1, and a capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
one end of the inductor L1 is connected with the cathode of the diode D1, the anode of the diode D1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is connected with the other end of the inductor L1; two ends of the capacitor C1 are also respectively connected with two power supply ends of the motor controller.
Further, in the invention, when the three-port DC/DC converter is in a single-input double-output mode, the fuel cell simultaneously supplies power for the battery heating film and the motor controller;
the switch tube Q1 and the switch tube Q2 are controlled by PWM signals;
t0in the state: the switching tube Q1 and the switching tube Q2 are in a conducting state;
the equivalent circuit includes: the input capacitor Cin, the switching tube Q1, the switching tube Q2, the inductor L2, the capacitor C2, the capacitor C1 and the inductor L1;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of the input capacitor Cin is connected with the drain electrode of the switching tube Q2, and the other end of the input capacitor Cin is connected with one end of the capacitor C2; the other end of the capacitor C2 is connected with one end of an inductor L2, and the other end of the inductor L2 is connected with the source electrode of a switching tube Q2;
the drain of the switching tube Q2 is further connected with the drain of the switching tube Q1, the source of the switching tube Q1 is connected with one end of an inductor L1, and the other end of the inductor L1 is connected with one end of a capacitor C2; two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller;
t1in the state: when the switch tube Q1 is in the off state and the switch tube Q2 is in the on state, the equivalent circuit includes: the circuit comprises an input capacitor Cin, a switching tube Q2, an inductor L2, a capacitor C2, an inductor L1, a capacitor C1 and a diode D1;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of the input capacitor Cin is connected with the drain electrode of the switching tube Q2, the source electrode of the switching tube Q2 is connected with one end of an inductor L2, the other end of the inductor L2 is connected with one end of a capacitor C2, and the other end of the capacitor C2 is connected with the other end of the input capacitor Cin;
two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
the anode of the diode D1 is connected with one end of the capacitor C1, the other end of the capacitor C1 is connected with one end of the inductor L1, the other end of the inductor L1 is connected with the cathode of the diode D1, and the two ends of the capacitor C1 are also connected with two power supply ends of the motor controller;
t2in the state: when the switch tube Q1 is in the on state, the switch tube Q2 is in the off state;
the equivalent circuit includes: an input capacitor Cin, a switching tube Q1, a diode D2, an inductor L2, a capacitor C2, an inductor L1 and a capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
one end of an input capacitor Cin is connected with the drain electrode of a switch tube Q1, the source electrode of a switch tube Q1 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a capacitor C2, the other end of the capacitor C2 is connected with one end of an inductor L2, the other end of the inductor L2 is connected with the cathode of a diode D2, and the anode of a diode D2 is connected with the other end of the inductor L1;
the anode of the diode D2 is also connected to the other end of the input capacitor Cin;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller;
t3in the state: the switching tube Q1 and the switching tube Q2 are in an off state;
the equivalent circuit includes: an input capacitor Cin, a diode D1, a diode D2, an inductor L2, a capacitor C2, an inductor L1 and a capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
the cathode of the diode D2 is connected with one end of the inductor L2, the other end of the inductor L2 is connected with one end of the capacitor C2, and the other end of the capacitor C2 is connected with the anode of the diode D2;
two ends of the capacitor C2 are respectively connected with two power supply ends of the battery heating film UO 2;
one end of the inductor L1 is connected with the cathode of the diode D1, the anode of the diode D1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is connected with the other end of the inductor L1;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller.
Further, in the present invention, a specific control method of the converter control circuit is:
s1, collecting real-time output voltage Uo2 of a front-stage Buck chopper circuit and real-time current of an inductor L2;
step S2, comparing the output voltage Uo2 with a reference voltage UrefComparing to obtain a voltage error signal e1, performing PI calculation on the voltage error signal e1 by using a voltage loop PI controller to obtain an expected inductor L2 current IL2ref；
Step S3, obtaining the expected current I of the inductor L2L2refComparing the current with the current of the inductor L2 acquired in the step one to obtain a current error signal e2, and performing PI (proportional integral) measurement on the current error signal e2 by adopting a current loop PI controllerCalculating, and summing with a feedforward controller k/Uin to obtain a duty ratio signal d; wherein k is a constant.
The invention can realize power management and control among the fuel cell, the cell heating film and the motor controller by adopting a single converter, single-stage power conversion is adopted between the input port and the two output ports, and centralized control and higher conversion efficiency can be realized. The two output ports of the invention can respectively realize the voltage boosting and reducing functions, namely the output voltage of the port of the motor controller has wide regulating range, can realize both voltage boosting and voltage reducing, and can better deal with the voltage drop phenomenon of the fuel cell under the complex working condition; the output port of the battery heating film can realize the voltage reduction function, the number of required devices is small, the electromagnetic interference is small, and the efficiency is high. The input port can be respectively for two output port power supplies, also can be simultaneously for two output port power supplies, and is not influenced each other, can guarantee the stable output of electric energy. The three-port DC/DC converter can provide power for the normal running of the automobile by a simple structure, can provide power for the temperature rise of the power battery, is convenient to integrally control, and ensures the stability of power charging and battery discharging in a low-temperature environment.
Drawings
FIG. 1 is an overall block diagram of a fuel cell hybrid vehicle power system according to the present invention;
FIG. 2 is a topology diagram of a non-isolated three-port DC/DC converter for a fuel cell hybrid vehicle;
FIG. 3 shows a non-isolated three-port DC/DC converter mode a for a fuel cell hybrid vehicleonEquivalent circuit and energy flow diagrams at state;
FIG. 4 shows a non-isolated three-port DC/DC converter mode a for a fuel cell hybrid vehicleoffEquivalent circuit and energy flow diagrams at state;
FIG. 5 shows a non-isolated three-port DC/DC converter in a single-input single-output mode b for a fuel cell hybrid vehicleonEquivalent circuit and energy flow diagrams at state;
FIG. 6 is a non-isolated three terminal for a fuel cell hybrid vehicleT under single-input single-output mode b of DC/DC converteroffEquivalent circuit and energy flow diagrams at state;
FIG. 7 shows a non-isolated three-port DC/DC converter single-input dual-output mode t for a fuel cell hybrid vehicle0Equivalent circuit and energy flow diagrams at state;
FIG. 8 shows a non-isolated three-port DC/DC converter single-input dual-output mode t for a fuel cell hybrid vehicle1Equivalent circuit and energy flow diagrams at state;
FIG. 9 shows a non-isolated three-port DC/DC converter single-input dual-output mode t for a fuel cell hybrid vehicle2Equivalent circuit and energy flow diagrams at state;
FIG. 10 shows a non-isolated three-port DC/DC converter single-input dual-output mode t for a fuel cell hybrid vehicle3Equivalent circuit and energy flow diagrams at state;
FIG. 11 is a control block diagram of a non-isolated three-port Buck chopper converter for a fuel cell hybrid vehicle
Fig. 12 is a block diagram of the main circuit and control circuit of the non-isolated three-port DC/DC converter for a fuel cell hybrid vehicle.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The first embodiment is as follows: the present embodiment will be described with reference to fig. 1, and the hybrid vehicle power supply system based on a three-port DC/DC converter according to the present embodiment includes a three-port DC/DC converter, a power battery, a battery heating film Uo2, a fuel cell Uin, and an converter control circuit;
three ports of the three-port DC/DC converter are respectively connected with a power supply end of a battery heating film, a power supply end of a fuel battery and a power supply end of a driving motor controller;
the converter control circuit is used for controlling the switch of a switch tube in the three-port DC/DC converter to enable the three-port DC/DC converter to be in different working modes;
the battery heating film UO2 is arranged on the outer side of the power battery and used for heating the power battery;
the three-port DC/DC converter includes: the Buck-Boost converter comprises a front-end Buck chopper circuit, a rear-end Buck-Boost chopper circuit and an input capacitor Cin;
the front-end Buck chopper circuit includes: a switching tube Q2, a diode D2, an inductor L2 and a capacitor C2;
the back-end Buck-Boost chopper circuit comprises: a switching tube Q1, a diode D1, a capacitor C1 and an inductor L1;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of the input capacitor Cin is connected with the drain electrode of the switching tube Q2, and the other end of the input capacitor Cin is connected with the anode of the diode D2;
the source of the switching tube Q2 is connected with the cathode of the diode D2;
the drain of the switching tube Q2 is further connected with the drain of the switching tube Q1, the source of the switching tube Q1 is connected with the cathode of the diode D1, the cathode of the diode D1 is further connected with one end of the inductor L1, the other end of the inductor L1 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with one end of the inductor L2, and the other end of the inductor L2 is connected with the source of the switching tube Q2;
two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
the anode of the diode D1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is connected with the other end of the inductor L1;
one end of the capacitor C2 is also connected with the anode of the diode D2; two ends of the capacitor C1 are also connected with two power supply ends of the motor controller.
The non-isolated three-port DC-DC converter is simultaneously connected with the fuel cell, the cell heating film and the motor controller, and has the advantages of compact structure, small volume and cost, convenience in centralized control of a power system and the like.
The low-temperature running method of the fuel cell hybrid electric vehicle, provided by the invention, comprises the following steps that under a low-temperature environment, before the fuel cell hybrid electric vehicle is started, the three-port DC/DC converter is controlled to work in a mode a, at the moment, the fuel cell directly provides power for a cell heating membrane, and power adjustment is carried out according to real-time temperature feedback of the power cell, so that the low-temperature preheating of the power cell is realized; when the fuel cell hybrid electric vehicle runs normally, the three-port DC/DC converter is controlled, the fuel cell hybrid electric vehicle is firstly enabled to work in a single-input single-output mode b, the fuel cell provides continuous power and adjusts according to the power of the whole vehicle, the power cell provides peak power for the conditions of rapid acceleration of the vehicle during starting, and meanwhile, the storage battery can provide a pure electric mode for the vehicle according to the requirements of working conditions, so that the economy of the vehicle is improved to a great extent; in addition, when the fuel cell hybrid electric vehicle normally runs in a low-temperature environment, the power cell can work in a single-input double-output mode by controlling the three-port DC/DC converter due to temperature reduction, the fuel cell simultaneously provides power for the motor controller and the battery heating film, and output power adjustment of the fuel cell is timely carried out according to the whole vehicle power and the temperature feedback of the power cell.
Further, in the present embodiment, the operation modes of the three-port DC/DC converter include: a single-input single-output mode and a single-input dual-output mode.
Further, in the present embodiment, the three-port DC/DC converter has a single input and single output mode, which includes a mode a and a mode b, in which in the mode a, the fuel cell individually supplies power to the battery heating film, and in the mode b, the fuel cell individually supplies power to the motor controller;
in the mode a: the switching tube Q2 is controlled by the PWM signal, and the switching tube Q1 is kept off;
as shown in FIG. 3, tonThe state is as follows: the switching tube Q2 is in a conducting state, and the equivalent circuit comprises: the input capacitor Cin, the switching tube Q2, the inductor L2 and the capacitor C2;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of an input capacitor Cin is connected with the drain electrode of the switch tube Q2, the other end of the input capacitor Cin is connected with one end of a capacitor C2, the other end of a capacitor C2 is connected with one end of an inductor L2, the other end of the inductor L2 is connected with the source electrode of a switch tube Q2, and two ends of a capacitor C2 are connected with two ends of a battery heating film UO 2;
as shown in fig. 4, toffThe state is as follows: the switching tube Q2 is in the off state, and the equivalent circuit includes: an input capacitor Cin, an inductor L2, a diode D2 and a capacitor C2;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
the anode of the diode D2 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with one end of the inductor L2, and the other end of the inductor L2 is connected with the cathode of the diode D2; two ends of the capacitor C2 are respectively connected with two power supply ends of the battery heating film;
in the mode b: the switching tube Q1 is controlled by the PWM signal, and the switching tube Q2 is kept off;
as shown in fig. 5, tonThe state is as follows: the switching tube Q1 is in a conducting state, and the equivalent circuit comprises: the input capacitor Cin, the switching tube Q1, the inductor L1 and the capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
one end of the input capacitor Cin is also connected with the drain electrode of the switching tube Q1, the source electrode of the switching tube Q1 is connected with one end of the inductor L1, and the other end of the inductor L1 is connected with the other end of the input capacitor Cin; two ends of the capacitor C1 are respectively connected with two power supply ends of the motor controller.
In this embodiment, the capacitor C1 is connected to the two ends of the motor controller to achieve the purpose of filtering and stabilizing the output voltage, and the continuity of the current of the motor controller can be ensured.
As shown in fig. 6, toffThe state is as follows: the switching tube Q1 is in the off state, and the equivalent circuit includes: an input capacitor Cin, a diode D1, an inductor L1, and a capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
the input capacitor Cin realizes filtering, and the fluctuation of output voltage is effectively reduced;
one end of the inductor L1 is connected with the cathode of the diode D1, the anode of the diode D1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is connected with the other end of the inductor L1; two ends of the capacitor C1 are also respectively connected with two power supply ends of the motor controller.
Further, in the present embodiment, when the three-port DC/DC converter is in the single-input dual-output mode, the fuel cell simultaneously supplies power to the battery heating film and the motor controller; the switch tube Q1 and the switch tube Q2 are controlled by PWM signals;
as shown in fig. 7; t is t0In the state: the switch tube Q1, switch tube Q2 are in the conducting state, and the equivalent circuit includes: the input capacitor Cin, the switching tube Q1, the switching tube Q2, the inductor L2, the capacitor C2, the capacitor C1 and the inductor L1;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of the input capacitor Cin is connected with the drain electrode of the switching tube Q2, and the other end of the input capacitor Cin is connected with one end of the capacitor C2; the other end of the capacitor C2 is connected with one end of an inductor L2, and the other end of the inductor L2 is connected with the source electrode of a switching tube Q2;
the drain of the switch tube Q2 is further connected with the drain of the switch tube Q1, the source of the switch tube Q1 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a capacitor C2,
two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller.
In this embodiment, the capacitor C1 is connected to two ends of the motor controller to achieve the purpose of filtering and stabilizing the output voltage, and can also ensure the continuity of the current of the motor controller;
as shown in fig. 8, t1In the state: the switch tube Q1 is in the OFF state, and the switch tube Q2 is in the ON state, and the equivalent circuit includes: the circuit comprises an input capacitor Cin, a switching tube Q2, an inductor L2, a capacitor C2, an inductor L1, a capacitor C1 and a diode D1;
the input capacitor Cin is connected in parallel with the fuel cell Uin; one end of the input capacitor Cin is connected with the drain electrode of the switching tube Q2, the source electrode of the switching tube Q2 is connected with one end of an inductor L2, the other end of the inductor L2 is connected with one end of a capacitor C2, and the other end of the capacitor C2 is connected with the other end of the input capacitor Cin;
two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
the anode of the diode D1 is connected with one end of the capacitor C1, the other end of the capacitor C1 is connected with one end of the inductor L1, the other end of the inductor L1 is connected with the cathode of the diode D1, and the two ends of the capacitor C1 are also connected with two power supply ends of the motor controller;
as shown in FIG. 9, t2In the state: the switch tube Q1 is in the conducting state, and the switch tube Q2 is in the off state, and the equivalent circuit includes: an input capacitor Cin, a switching tube Q1, a diode D2, an inductor L2, a capacitor C2, an inductor L1 and a capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
one end of the input capacitor Cin is further connected with the drain of a switching tube Q1, the source of the switching tube Q1 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a capacitor C2, the other end of the capacitor C2 is connected with one end of an inductor L2, the other end of the inductor L2 is connected with the cathode of a diode D2, and the anode of a diode D2 is connected with the other end of the inductor L1; the anode of the diode D2 is also connected to the other end of the input capacitor Cin;
two ends of the capacitor C2 are respectively connected with two power supply ends of a battery heating film UO 2;
two ends of the capacitor C1 are also connected with two power supply ends of the motor controller.
As shown in fig. 10, t3In the state: the switch tube Q1, switch tube Q2 are in the off-state, and the equivalent circuit includes: an input capacitor Cin, a diode D1, a diode D2, an inductor L2, a capacitor C2, an inductor L1 and a capacitor C1;
the input capacitor Cin is connected in parallel with the fuel cell Uin;
the cathode of the diode D2 is connected with one end of the inductor L2, the other end of the inductor L2 is connected with one end of the capacitor C2, and the other end of the capacitor C2 is connected with the anode of the diode D2;
two ends of the capacitor C2 are respectively connected with two power supply ends of the battery heating film UO 2;
one end of the inductor L1 is connected with the cathode of the diode D1, the anode of the diode D1 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is connected with the other end of the inductor L1; two ends of the capacitor C1 are also connected with two power supply ends of the motor controller.
Further, in the present embodiment, the present embodiment is described with reference to fig. 11, and a specific control method of the inverter control circuit is:
s1, collecting real-time output voltage Uo2 of a front-stage Buck chopper circuit and real-time current of an inductor L2;
step S2, comparing the output voltage Uo2 with a reference voltage UrefComparing to obtain a voltage error signal e1, performing PI calculation on the voltage error signal e1 by using a voltage loop PI controller to obtain an expected inductor L2 current IL2ref；
Step S3, obtaining the expected current I of the inductor L2L2refComparing the current with the current of the inductor L2 acquired in the step one to acquire a current error signal e2, performing PI calculation on the current error signal e2 by adopting a current loop PI controller, and summing the current error signal with a feedforward controller k/Uin to acquire a duty ratio signal d; wherein k is a constant.
Fig. 11 shows a schematic diagram of the present embodiment, fig. 11 is a mathematical model, PWM is generated by duty ratio d and carrier modulation (both in DSP), and two transfer functions in fig. 11Is the current I of the inductor L2L2A transfer function with the duty cycle d,is the voltage U across the capacitor C2c2With inductor L2 current IL2The transfer function of (a); k/UinIs a feedforward controller, where k is a constant, k/UinThe controller has the functions of acting the change of the input voltage on the duty ratio d in advance to offset the disturbance to the output when the input voltage changes, and acting the function of soft start because the duty ratio d is not zero when the converter is just started to protect the topology.
In a low-temperature environment, before a fuel cell hybrid electric vehicle is started, the three-port DC/DC converter is controlled to work in a mode a, at the moment, the fuel cell directly provides power for a cell heating film, and power adjustment is carried out according to real-time temperature feedback of the power cell, so that low-temperature preheating of the power cell is realized; when the fuel cell hybrid electric vehicle runs normally, the three-port DC/DC converter is controlled, the fuel cell hybrid electric vehicle is firstly enabled to work in a single-input single-output mode b, the fuel cell provides continuous power and adjusts according to the power of the whole vehicle, the power cell provides peak power for the conditions of rapid acceleration of the vehicle during starting, and meanwhile, the storage battery can provide a pure electric mode for the vehicle according to the requirements of working conditions, so that the economy of the vehicle is improved to a great extent; in addition, when the fuel cell hybrid electric vehicle normally runs in a low-temperature environment, the power cell can work in a single-input double-output mode by controlling the three-port DC/DC converter due to temperature reduction, the fuel cell simultaneously provides power for the motor controller and the battery heating film, and output power adjustment of the fuel cell is timely carried out according to the whole vehicle power and the temperature feedback of the power cell. The main focus is to design a functional three-port DC/DC topology capable of conveniently realizing low-temperature preheating of a power battery while the automobile normally runs according to the low-temperature running condition of the electric automobile.
As shown in connection with fig. 12, the converter control circuit includes a protection circuit, a DSP system, a voltage sensor, a current sensor, and a temperature sensor;
the voltage sensor collects voltage signals of ports Uin, Uo1 and Uo2 of the DC/DC converter; the collected voltage signals of the main circuit of the DC/DC converter are simultaneously output to a DSP system; the current sensor collects current signals of two ports of a Uin port and a Uo1 port and an inductor L2 and outputs the collected current signals to the DSP system;
the temperature sensor collects the temperature of the battery heating film, converts the temperature into a temperature signal and outputs the temperature signal to the DSP system;
inputting a target voltage at a target voltage signal input end of the DSP system; and the switch tube driving signal output end of the DSP system is connected with the switch tube driving signal input end of the protection circuit, and the switch tube driving signal output end of the protection circuit is the switch tube driving signal output end of the DC/DC converter control circuit.
The required power is calculated by adopting a formula P as UI, the required power of the whole vehicle is obtained from a whole vehicle controller, and the required power of the battery heating film is obtained from a temperature sensor;
when the power battery is preheated at low temperature before the electric automobile is started, the DSP (202) system outputs a PWM control signal to control the on and off of a corresponding switch tube, so that the system works in a mode a;
when the electric automobile normally runs, the DSP (202) system outputs a PWM control signal to control the on and off of a corresponding switch tube, so that the system works in a single-input single-output mode b;
when the temperature of the power battery is reduced to the warning temperature in the running process of the electric automobile, the DSP (202) system outputs a PWM control signal to control the on and off of a corresponding switch tube, so that the system works in a single-input double-output mode.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that features described in different dependent claims and herein may be combined in ways different from those described in the original claims. It is also to be understood that features described in connection with individual embodiments may be used in other described embodiments.