CN104734512A - Fuel battery DC/DC conversion device and control method thereof - Google Patents
Fuel battery DC/DC conversion device and control method thereof Download PDFInfo
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- CN104734512A CN104734512A CN201310716487.9A CN201310716487A CN104734512A CN 104734512 A CN104734512 A CN 104734512A CN 201310716487 A CN201310716487 A CN 201310716487A CN 104734512 A CN104734512 A CN 104734512A
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Abstract
The invention discloses a fuel battery DC/DC conversion device and a control method thereof. The device comprises a boost chopping circuit for boosting and a full-bridge DC converter for isolating and voltage reducing. The input end of the boost chopping circuit is connected to a fuel battery, and the output end of the boost chopping circuit is connected to the full-bridge DC converter. The output end of the full-bridge DC converter is connected to a load circuit. When the voltage output by the fuel battery is between the open circuit voltage of the fuel battery and a preset value, the boost chopping circuit stops working, and the full-bridge DC converter conducts electricity conversion for the load circuit; when the voltage output by the fuel battery is smaller than a preset value Vr1, the voltage output by the boost chopping circuit is increased to the preset value through the boost chopping circuit; when the voltage output by the fuel battery is smaller than a preset value Vr2, the output of the DC/DC conversion device is decreased so as to make the voltage of the fuel battery not smaller than the preset value Vr2.
Description
Technical field
The present invention relates to a kind of DC/DC converting means, particularly a kind of DC/DC converting means of fuel cell and control method thereof.
Background technology
Fuel cell is the chemical energy that will be stored in fuel and oxidant, is converted into the device of electric energy.When continuously externally to fuel cell supply fuel and oxidant, it can uninterruptable power generation.Fuel cell stand-by power supply has started to use in some industries are as the communications industry.Although what fuel cell produced is direct current, voltage change range is comparatively large with the fluctuation of load, so fuel cell is not generally powered directly to traffic load.The direct current of fuel cell generation is given traffic load by existing technology usually after DC/DC conversion.When fuel cell open circuit voltage is higher than communication power supply voltage, when rated operational voltage is lower than communication power supply voltage simultaneously, the direct current to fuel cell exports is needed to boost and make a price reduction conversion.Such as patent of invention 201110170153,5 boostings that can only realize fuel cell.Existing communication DC converting means can not meet the requirement being operated in pressure-increasning state and step-down state on a large scale under direct current input.Single DC converting or simple series connection with decompression DC device by voltage boosting dc converting means use, and the efficiency of integral transformation is difficult to reach pre-provisioning request.And fuel cell is along with the increase of service time, maximum power will slowly reduce.When the power limitation of maximum power lower than DC converter after fuel cell decay, load sudden change in short-term may make DC converter input terminal voltage enter under-voltage protection lower than under-voltage point, then restarts, and repeats this process.The normal work of back and forth restarting meeting influential system in short-term like this and system lifetim.
Summary of the invention
Main purpose of the present invention is to provide a kind of fuel cell DC/DC converting means, and it can realize boosting inverter also can realize decompression transformation, can ensure the fuel cell DC/DC converting means of system effectiveness simultaneously.
Another object of the present invention is to provide a kind of fuel cell DC/DC converting means, it comprises for realizing the boost chopper boosted, and realize the full-bridge direct current converter of isolation and step-down, input voltage can be transformed to a stable output voltage to described full-bridge direct current converter by described boost chopper, allow described full-bridge direct current converter circuit working in preferably working point, prevent the input of described full-bridge direct current converter from occurring wide fluctuations, thus the efficiency that improve total system while circuit can realize DC boosting and buck functionality is ensure that from hardware.
Another object of the present invention is to provide a kind of fuel cell DC/DC converting means, wherein said full-bridge direct current converter circuit adopts power transformer to realize the isolation of constrained input, prevents the interference between the load circuit of application and fuel cell.
Another object of the present invention is to provide a kind of fuel cell DC/DC converting means, wherein when described fuel cell output voltage is enough high, described boost chopper does not work, whole system carries out power converter by described full-bridge direct current converter to load circuit, decrease the link of conversion, the shortcoming that in customer service low-power situation, system effectiveness is low.
Another object of the present invention is to provide a kind of fuel cell DC/DC converting means, wherein when described fuel cell output voltage is lower than predetermined numerical value, described boost chopper carries out boosting and regulates, and makes operation of fuel cells on under-voltage point, thus improves the stability of system.
For reaching above object, the invention provides a kind of fuel cell DC/DC converting means, it comprises for realizing the boost chopper boosted, and realize the full-bridge direct current converter of isolation and step-down, the input of described boost chopper is connected to fuel cell, output is connected to described full-bridge direct current converter, the output of described full-bridge direct current converter is connected to load circuit, when the output voltage of described fuel cell is between the open circuit voltage and a preset value Vr1 of described fuel cell, described boost chopper quits work, carry out power converter to described load circuit by described full-bridge direct current converter, when the output voltage of described fuel cell is less than described preset value Vr1, the output voltage of described boost chopper is increased to described preset value by described boost chopper.
According to one embodiment of present invention, described fuel cell DC/DC converting means also comprises the first testing circuit of the output voltage for detecting described fuel cell output voltage and described boost chopper, and for detecting the described output voltage of fuel cell DC/DC converting means and the second testing circuit of electric current, and controller, the data that the first testing circuit described in described controller analyzing and processing and described second testing circuit detect also control the operation of described boost chopper and described full-bridge direct current converter.
According to one embodiment of present invention, described first testing circuit comprises the first voltage detecting circuit for detecting described fuel cell output voltage, and for the second voltage detecting circuit of the output voltage that detects described boost chopper, one end of described first voltage detecting circuit is connected between described fuel cell and described boost chopper, the other end is connected with described controller, described second voltage detecting circuit one end is connected to described boost chopper and described full-bridge direct current converter, and the other end is connected with described controller.
According to one embodiment of present invention, described second testing circuit comprises the current detection circuit of the output current detecting described fuel cell DC/DC converting means, and for the tertiary voltage testing circuit of the output voltage that detects described fuel cell DC/DC converting means, described current detection circuit one end is connected between described full-bridge direct current converter and described load circuit, the other end is connected with described controller, described tertiary voltage testing circuit one end is connected between described full-bridge direct current converter and described load circuit, and the other end is connected to described controller.
According to one embodiment of present invention, described controller comprises control chip, and for carrying out the pulse-width modulation driving isolation circuit of driving isolation to the field effect transistor control signal in described boost chopper and described full-bridge direct current converter, described control chip is connected with described first testing circuit and described second testing circuit, with the switching time that the field effect transistor calculated in described boost chopper and described full-bridge direct current converter controls, and signal is passed to described pulse-width modulation driving isolation circuit, the described signal of recruiting is carried out isolated variable by described pulse-width modulation driving isolation circuit.
According to one embodiment of present invention, described boost chopper comprises energy storage inductor, counnter attack diode, field effect transistor switch pipe and filter capacitor, described energy storage inductor one end is connected with described fuel cell, one end is connected between the drain electrode of described field effect transistor switch pipe and the anode of described counnter attack diode in addition, the negative electrode of described counnter attack diode is connected between the positive pole of described filter capacitor and the input of described full-bridge direct current converter, the gate pole of described field effect transistor switch pipe is connected with described pulse-width modulation driving isolation circuit, the source electrode of described field effect transistor switch pipe is connected between the negative pole of described fuel cell and described filter capacitor, the negative pole of described filter capacitor is connected with described full-bridge direct current converter.
According to one embodiment of present invention, described full-bridge direct current converter comprises the field effect transistor be operably connected, capacitance, power transformer, Half bridge rectifier diode, filter inductance, filter resistance, and filter capacitor.
According to one embodiment of present invention, the described field effect transistor of described full-bridge direct current converter comprises the first field effect transistor, second field effect transistor, 3rd field effect transistor and the 4th field effect transistor, described Half bridge rectifier diode comprises the first Half bridge rectifier diode, second Half bridge rectifier diode, 3rd Half bridge rectifier diode and the 4th Half bridge rectifier diode, described filter inductance comprises the first filter inductance and the second filter inductance, the drain electrode of the second described field effect transistor is between the positive pole and the drain electrode of described first field effect transistor of the filter capacitor of described boost chopper, the source electrode of described second field effect transistor is between described capacitance and the drain electrode of described 3rd field effect transistor, the source electrode of described second field effect transistor is between first pin and the drain electrode of described 4th field effect transistor of described power transformer, described 3rd field effect transistor source electrode is between the negative pole and the source electrode of described 4th field effect transistor of the filter capacitor of described boost chopper, described capacitance one end is between the source electrode and the drain electrode of described 3rd field effect transistor of described first field effect transistor, one end is connected with described power transformer crus secunda in addition, the negative electrode of described first Half bridge rectifier diode is connected with described power transformer the tenth pin, anode is between the anode and described second filter inductance of described second Half bridge rectifier diode, the negative electrode of described second Half bridge rectifier diode is connected with described power transformer the 7th pin, the negative electrode of described 3rd Half bridge rectifier diode is connected with described power transformer the 6th pin, anode is between the anode and described first filter inductance of described 4th Half bridge rectifier diode, the negative electrode of described 4th Half bridge rectifier diode is connected with described power transformer tripod, described second filter inductance one end is between the anode and the anode of described second Half bridge rectifier diode of described first Half bridge rectifier diode, one end is between the negative pole of the described filter capacitor of described first filter inductance and described full-bridge direct current converter in addition, one end of described filter resistance is between described first filter inductance and the described filter capacitor negative pole of described full-bridge direct current converter, one end is between the described filter capacitor and described power transformer the 4th pin of described full-bridge direct current converter in addition, described power transformer the 4th pin is between described power transformer the 5th pin and the described filter capacitor positive pole of described full-bridge direct current converter, described power transformer octal is between the positive pole of the described filter capacitor of described power transformer the 9th pin and described full-bridge direct current converter.
According to one embodiment of present invention, when the output voltage of fuel cell is less than pre-set value Vr2, reduction exports and makes the voltage of fuel cell be not less than pre-set value Vr2 by DC/DC converting means.。
According to one embodiment of present invention, described preset value Vr1 is between 42 ~ 50V, and described preset value Vr2 is between 26 ~ 30V, and described minimum operating voltage Vr3 is between 23 ~ 25V.。
The present invention also provides a kind of control method of fuel cell DC/DC converting means, described fuel cell DC/DC converting means comprises for realizing the boost chopper boosted, and realizing the full-bridge direct current converter of isolation and step-down, described method comprises the steps:
A (), when detecting that the output voltage Ve of described fuel cell is between the open circuit voltage and a preset value Vr1 of described fuel cell, described boost chopper quits work, carry out power converter to described load circuit by described full-bridge direct current converter; And
B (), when detecting that the output voltage Ve of described fuel cell is less than described preset value Vr1, the output voltage of described boost chopper is increased to described preset value by described boost chopper.
According to one embodiment of present invention, in above-mentioned control method, described full-bridge direct current converter comprises the field effect transistor be operably connected, capacitance, power transformer, Half bridge rectifier diode, filter inductance, filter resistance, and filter capacitor, the described field effect transistor of described full-bridge direct current converter comprises the first field effect transistor, second field effect transistor, 3rd field effect transistor and the 4th field effect transistor, described Half bridge rectifier diode comprises the first Half bridge rectifier diode, second Half bridge rectifier diode, 3rd Half bridge rectifier diode and the 4th Half bridge rectifier diode, described filter inductance comprises the first filter inductance and the second filter inductance, the drain electrode of the second described field effect transistor is between the positive pole and the drain electrode of described first field effect transistor of the filter capacitor of described boost chopper, the source electrode of described second field effect transistor is between described capacitance and the drain electrode of described 3rd field effect transistor, the source electrode of described second field effect transistor is between first pin and the drain electrode of described 4th field effect transistor of described power transformer, described 3rd field effect transistor source electrode is between the negative pole and the source electrode of described 4th field effect transistor of the filter capacitor of described boost chopper, described capacitance one end is between the source electrode and the drain electrode of described 3rd field effect transistor of described first field effect transistor, one end is connected with described power transformer crus secunda in addition, the negative electrode of described first Half bridge rectifier diode is connected with described power transformer the tenth pin, anode is between the anode and described second filter inductance of described second Half bridge rectifier diode, the negative electrode of described second Half bridge rectifier diode is connected with described power transformer the 7th pin, the negative electrode of described 3rd Half bridge rectifier diode is connected with described power transformer the 6th pin, anode is between the anode and described first filter inductance of described 4th Half bridge rectifier diode, the negative electrode of described 4th Half bridge rectifier diode is connected with described power transformer tripod, described second filter inductance one end is between the anode and the anode of described second Half bridge rectifier diode of described first Half bridge rectifier diode, one end is between the negative pole of the described filter capacitor of described first filter inductance and described full-bridge direct current converter in addition, one end of described filter resistance is between described first filter inductance and the described filter capacitor negative pole of described full-bridge direct current converter, one end is between the described filter capacitor and described power transformer the 4th pin of described full-bridge direct current converter in addition, described power transformer the 4th pin is between described power transformer the 5th pin and the described filter capacitor positive pole of described full-bridge direct current converter, described power transformer octal is between the positive pole of the described filter capacitor of described power transformer the 9th pin and described full-bridge direct current converter
According to one embodiment of present invention, described preset value Vr1 is between 42 ~ 50V, and described preset value Vr2 is between 26 ~ 30V, and described minimum operating voltage Vr3 is between 23 ~ 25V.。
According to one embodiment of present invention, detect that the output voltage of described boost chopper is Vb, and in such a way by the output voltage Vb of boost chopper described in the duty cycle adjustment that changes the field effect transistor switch pipe control signal of described boost chopper:
C (), as Ve>Vr1, the controller of described fuel cell DC/DC converting means is 0 to the duty ratio of described field effect transistor switch pipe control signal, all should quit work by switching tube to make described field; And
D (), as Ve≤Vr1, described controller, by changing the duty ratio of described field effect transistor switch pipe control signal, regulates the output voltage Vb of filter circuit, makes Vb equal described preset value Vr1.
According to one embodiment of present invention, in described full-bridge direct current converter described first and the conducting simultaneously of the 4th field effect transistor turn off simultaneously, the duty ratio of the control signal pulse-width modulation of its correspondence is Ton, described second and the 3rd field effect transistor simultaneously conducting turn off simultaneously, the pulse width modulation duty of the control signal of its correspondence is 1-Ton-Td, wherein Td is Dead Time, and described controller can control output voltage and the electric current of described full-bridge direct current converter by the size of control Ton.
According to one embodiment of present invention, the input voltage of the measurement fuel cell that described controller receives is Ve, the output voltage Vo of described fuel cell DC/DC converting means and output current Io, according to the rated operational voltage set point Vr4 of load circuit setting, maximum output current limits value Ir1, operating voltage Vr2 preset by the fuel cell of fuel cell property settings, and its method controlling the pulse width modulation duty Ton in described full-bridge direct current converter is as follows:
(1) E1 (k)=Ve (k)-Vr2, EC1 (k)=(1-a1) * (E1 (k)-E1 (k-1))+a1*EC1 (k-1), wherein a1 is setting coefficient;
(2) error E 1 (k) obtained according to step (1) calculates output PID1 (k), if PID1 (k) >=Vr4, PID1 (k) equals Vr4 with error rate EC1 (k) by PID;
(3) E2 (k)=PID1 (k)-Vo (k), EC2 (k)=(1-a2) * (E2 (k)-E2 (k-1))+a2*EC2 (k-1), wherein a2 is setting coefficient;
(4) error E 2 (k) obtained according to step (3) calculates output PID2 (k), if PID2 (k) >=Ir1, PID2 (k) equals Ir1 with error rate EC2 (k) by PID;
(5) E3 (k)=PID2 (k)-Io (k), EC3 (k)=(1-a3) * (E3 (k)-E3 (k-1))+a3*EC3 (k-1), wherein a3 is setting coefficient;
(6) error E 3 (k) obtained according to step (5) calculates output PID3 (k) with error rate EC3 (k) by PID, and PID3 (k) is the PWM control duty ratio Ton that full-bridge direct current converter (3) exported to by controller (6); Wherein, k is this sub-value, and k-1 is last value.
Beneficial effect of the present invention is; by selectable two kinds of voltage-regulation modes; namely the boosting of boost chopper regulates; and separately by the adjustment of full-bridge direct current converter; the shortcoming that in described fuel cell DC/DC converting means customer service low-power situation, system effectiveness is low, and load sudden change in short-term can be avoided to make DC converter input terminal voltage enter under-voltage protection lower than under-voltage point then restart and repeat this process and cause shortening system lifetim.
Accompanying drawing explanation
Fig. 1 is the electrical block diagram of the DC/DC converting means of the fuel cell of a preferred embodiment of the present invention.Embodiment
The invention provides a kind of fuel cell DC/DC converting means, it comprises for realizing the Boost chopper circuit (2) boosted and the full-bridge direct current converter (3) realizing isolation and step-down; Also comprise the testing circuit (5) detecting fuel cell output voltage and Boost output voltage, the testing circuit (7) of detection system output voltage electric current, and the controller of system (6); The input of described Boost chopper circuit (2) is connected with the output DC bus (1) of fuel cell, and the output of Boost chopper circuit (2) is connected with full-bridge direct current converter (3); The output of described full-bridge direct current converter (3) is connected with traffic load (4), and the input of full-bridge direct current converter (3) is connected with Boost chopper circuit (2); Described testing circuit (5), comprises the voltage detecting I (5.1) for detecting fuel cell output voltage and the voltage detecting II (5.2) for detecting Boost chopper circuit (2) output voltage forms; Described voltage detecting I (5.1) one end is connected to fuel cell and exports bus (1) and between Boost chopper circuit (2) inputs, one end is connected with controller (6) in addition; Described voltage detecting II (5.2) one end is connected to Boost chopper circuit (2) and exports and between full-bridge direct current converter (3) inputs, one end is connected with controller (6) in addition; Described testing circuit (7) one end is connected to full-bridge direct current converter (3) and exports between traffic load (4), and one end is connected with controller (6) in addition.
After adopting above structure, the present invention plants fuel cell DC converting means compared with the prior art, have the following advantages: input voltage can be transformed to a stable output voltage to full-bridge direct current converter (3) by Boost chopper circuit (2) of the present invention, allow full-bridge direct current converter (3) circuit working in preferably working point, prevent the input of full-bridge direct current converter (3) from occurring wide fluctuations, thus ensure that the efficiency that improve total system while circuit can realize DC boosting and buck functionality from hardware.Full-bridge direct current converter (3) circuit adopts power transformer to realize the isolation of constrained input, prevents the interference between traffic load and fuel cell.
Described testing circuit (7) comprises the current detecting I (7.1) for detecting converting means output current and detects voltage detecting III (7.2) composition of output voltage; Described current detecting I (7.1) one end is connected to full-bridge direct current converter (3) and exports between traffic load (4), and one end is connected with controller (6) in addition; Described voltage detecting III (7.2) one end is connected to full-bridge direct current converter (3) and exports between traffic load (4), and one end is connected with controller (6) in addition;
Described controller (6) comprises the control chip MCU (6.1) realizing whole system control algolithm and the PWM driving isolation circuit (6.2) Boost chopper circuit (2) and the metal-oxide-semiconductor control signal in full-bridge direct current converter (3) being carried out to driving isolation, AD input and the voltage detecting I (5.1) of described control chip MCU (6.1), voltage detecting II (5.2), the current detecting I (7.1) of stream, be connected with the voltage detecting III (7.2) detecting output voltage, pass through control algolithm, calculate the switching time that Boost chopper circuit (2) controls with the metal-oxide-semiconductor in full-bridge direct current converter (3), and signal is passed to PWM driving isolation circuit (6.2), the signal of reception is carried out isolated variable by described PWM driving isolation circuit (6.2), pwm signal g1 is connected with the gate pole of metal-oxide-semiconductor (2.3) in Boost chopper circuit (2), pwm signal g2 is connected with the gate pole of metal-oxide-semiconductor (3.1) in full-bridge direct current converter (3), pwm signal g3 is connected with the gate pole of metal-oxide-semiconductor (3.3) in full-bridge direct current converter (3), pwm signal g4 is connected with the gate pole of metal-oxide-semiconductor (3.4) in full-bridge direct current converter (3), pwm signal g5 is connected with the gate pole of metal-oxide-semiconductor (3.2) in full-bridge direct current converter (3).
Further, described Boost chopper circuit (2) comprises energy storage inductor (2.1), counnter attack diode (2.2), MOS switching tube (2.3) and filter capacitor (2.4); Described energy storage inductor (2.1) one end is connected with the output (1) of fuel cell, and one end is connected between MOS switching tube (2.3) drain electrode and the anode of counnter attack diode (2.2) in addition; Described counnter attack diode (2.2) negative electrode is connected between filter capacitor (2.4) positive pole and full-bridge direct current converter (3) input; The described gate pole of MOS switching tube (2.3) is connected with the g1 signal of PWM isolated drive circuit, and the source electrode of MOS switching tube is connected between the output of fuel cell and filter capacitor negative pole; Described filtered electrical negative pole is connected with full-bridge direct current converter (3)
Further, full-bridge direct current converter (3) comprises metal-oxide-semiconductor (3.1), metal-oxide-semiconductor (3.2), metal-oxide-semiconductor (3.3), metal-oxide-semiconductor (3.4), capacitance (3.5), power transformer (3.6), Half bridge rectifier diode (3.7), (3.8), (3.9), (3.10), filter inductance (3.11), (3.12), filter resistance (3.13), filter capacitor (3.14); The drain electrode of described metal-oxide-semiconductor (3.2) is positioned between filter capacitor (2.4) positive pole and metal-oxide-semiconductor (3.2) drain, and the source electrode of metal-oxide-semiconductor (3.2) is positioned between the drain electrode of capacitance (3.5) and metal-oxide-semiconductor (3.3); The source electrode of described metal-oxide-semiconductor (3.2) is positioned between the drain electrode of power transformer 1. pin and metal-oxide-semiconductor (3.4); Described metal-oxide-semiconductor (3.3) source electrode is positioned between the source electrode of filter capacitor (2.4) negative pole and metal-oxide-semiconductor (3.4); Described capacitance (3.5) one end is positioned between metal-oxide-semiconductor (3.1) source electrode and metal-oxide-semiconductor (3.3) drain, and 2. one end is connected with power transformer in addition; Described Half bridge rectifier diode (3.7) negative electrode and power transformer 10. pin are connected, and anode is positioned between Half bridge rectifier diode (3.8) anode and filter inductance (3.12); The negative electrode of described Half bridge rectifier diode (3.8) and power transformer 7. pin are connected; Described Half bridge rectifier diode (3.9) negative electrode and power transformer 6. pin are connected, and anode is positioned between Half bridge rectifier diode (3.10) anode and filter inductance (3.11); The negative electrode of described Half bridge rectifier diode (3.10) and power transformer 3. pin are connected; Described filter inductance (3.12) one end is positioned between Half bridge rectifier diode (3.7) anode and Half bridge rectifier diode (3.8) anode, and one end is positioned between filter inductance (3.11) and filter capacitor (3.14) negative pole in addition; Described filter resistance, one end is positioned between filter inductance (3.11) and filter capacitor negative pole, and one end is positioned at filter capacitor in addition, and power transformer is 4. between pin.Described power transformer 4. pin at power transformer 5. between pin and filter capacitor positive pole; Described power transformer 8. pin at power transformer 9. between pin and filter capacitor positive pole
The control method of fuel cell DC converting means of the present invention, it comprises the steps.
(1) controller (6) receiver voltage detects I (5.1) output voltage measuring fuel cell is Ve, Boost chopper circuit (2) output voltage that voltage detecting II (5.2) detects is Vb and is Vr1(42<Vr1<50V according to the output voltage set point of ardware feature setting Boost chopper circuit (2)), by changing duty cycle adjustment Boost chopper circuit (2) output voltage of metal-oxide-semiconductor (2.3) control signal g1, specifically comprise:
1., as Ve>Vr1, the duty ratio of controller (6) given metal-oxide-semiconductor (2.3) control signal g1 is 0, and namely metal-oxide-semiconductor (2.3) quits work;
2. Ve≤Vr1, controller (6), by changing the duty ratio of g1 signal, regulates filter circuit (2) output voltage to be Vb, makes Vb equal setting voltage Vr1.
(2) metal-oxide-semiconductor (3.1) in full-bridge direct current converter (3), (3.4) conducting simultaneously turns off simultaneously, its control signal g2, the duty ratio of the PWM of g4 is Ton, metal-oxide-semiconductor (3.2), (3.3) conducting simultaneously turns off simultaneously, its control signal g3, the PWM duty ratio of g5 is 1-Ton-Td, and wherein Td is Dead Time; Controller (6) can control full-bridge direct current converter (3) output voltage and electric current by the size of control Ton;
(3) controller (6) receiver voltage detects I (5.1) input voltage measuring fuel cell is Ve, the output current Io of the converting means that the output voltage Vo of voltage detecting III (7.2) converting means and current detecting I (7.1) are measured, according to the rated operational voltage set point Vr4 of traffic load setting, maximum output current limits value Ir1, operating voltage Vr2(26 ~ 30V preset by the fuel cell of fuel cell property settings); Its method controlling the PWM duty ratio Ton in full-bridge direct current converter (3) is as follows:
1. E1 (k)=Ve (k)-Vr2, EC1 (k)=(1-a1) * (E1 (k)-E1 (k-1))+a1*EC1 (k-1), wherein a1 is setting coefficient;
2. the error E 1 (k) 1. obtained according to step calculates output PID1 (k), if PID1 (k) >=Vr4, PID1 (k) equals Vr4 with error rate EC1 (k) by PID;
3. E2 (k)=PID1 (k)-Vo (k), EC2 (k)=(1-a2) * (E2 (k)-E2 (k-1))+a2*EC2 (k-1), wherein a2 is setting coefficient;
4. the error E 2 (k) 3. obtained according to step calculates output PID2 (k), if PID2 (k) >=Ir1, PID2 (k) equals Ir1 with error rate EC2 (k) by PID;
5. E3 (k)=PID2 (k)-Io (k), EC3 (k)=(1-a3) * (E3 (k)-E3 (k-1))+a3*EC3 (k-1), wherein a3 is setting coefficient;
6. the error E 3 (k) 5. obtained according to step calculates output PID3 (k) with error rate EC3 (k) by PID, and PID3 (k) is the PWM control duty ratio Ton that full-bridge direct current converter (3) exported to by controller (6).
Wherein, k is this sub-value, and k-1 is last value.
After adopting above control method, a kind of fuel cell for communication DC/DC converting means of invention compared with prior art, has the following advantages:
When the output voltage of fuel cell be Ve between fuel cell open circuit voltage and Vr1 voltage time, stop the work of Boost circuit, now operation of fuel cells is under a low load.Due to DC/DC converting means, efficiency is lower under a low load, by stopping the work of Boost circuit, carrying out power converter separately, decrease the link of conversion by full-bridge direct current converter to traffic load, the shortcoming that in customer service low-power situation, system effectiveness is low.Secondly by introducing the outer voltage control system based on fuel cell output voltage Ve; make operation of fuel cells on setting voltage Vr2; load sudden change in short-term can be avoided to make DC converter input terminal voltage enter under-voltage protection lower than under-voltage point, then restart, and repeat this process.Overcoming of these shortcomings, not only improves the efficiency of system, improves the stability of system simultaneously, extends system lifetim.
One skilled in the art will understand that the embodiments of the invention shown in foregoing description and accompanying drawing only limit the present invention as an example and not.Object of the present invention is complete and effectively realize.Function of the present invention and structural principle are shown in an embodiment and are illustrated, do not deviating under described principle, embodiments of the present invention can have any distortion or amendment.
Claims (16)
1. a fuel cell DC/DC converting means, is characterized in that, comprising:
For realizing the boost chopper boosted, and realize the full-bridge direct current converter of isolation and step-down, the input of described boost chopper is connected to fuel cell, output is connected to described full-bridge direct current converter, the output of described full-bridge direct current converter is connected to load circuit, when the output voltage of described fuel cell is between the open circuit voltage and a preset value Vr1 of described fuel cell, described boost chopper quits work, carry out power converter to described load circuit by described full-bridge direct current converter, when the output voltage of described fuel cell is less than described preset value Vr1, the output voltage of described boost chopper is increased to described preset value by described boost chopper, when the output voltage of fuel cell is less than pre-set value Vr2, reduction exports and makes the voltage of fuel cell be not less than pre-set value Vr2 by DC/DC converting means.。
2. fuel cell DC/DC converting means according to claim 1, it is characterized in that, also comprise the first testing circuit of the output voltage for detecting described fuel cell output voltage and described boost chopper, and for detecting the described output voltage of fuel cell DC/DC converting means and the second testing circuit of electric current, and controller, the data that the first testing circuit described in described controller analyzing and processing and described second testing circuit detect also control the operation of described boost chopper and described full-bridge direct current converter.
3. fuel cell DC/DC converting means according to claim 2, it is characterized in that, described first testing circuit comprises the first voltage detecting circuit for detecting described fuel cell output voltage, and for the second voltage detecting circuit of the output voltage that detects described boost chopper, one end of described first voltage detecting circuit is connected between described fuel cell and described boost chopper, the other end is connected with described controller, described second voltage detecting circuit one end is connected to described boost chopper and described full-bridge direct current converter, the other end is connected with described controller.
4. fuel cell DC/DC converting means according to claim 2, it is characterized in that, described second testing circuit comprises the current detection circuit of the output current detecting described fuel cell DC/DC converting means, and for the tertiary voltage testing circuit of the output voltage that detects described fuel cell DC/DC converting means, described current detection circuit one end is connected between described full-bridge direct current converter and described load circuit, the other end is connected with described controller, described tertiary voltage testing circuit one end is connected between described full-bridge direct current converter and described load circuit, the other end is connected to described controller.
5. according to described fuel cell DC/DC converting means arbitrary in claim 2 to 4, it is characterized in that, described controller comprises control chip, and for carrying out the pulse-width modulation driving isolation circuit of driving isolation to the field effect transistor control signal in described boost chopper and described full-bridge direct current converter, described control chip is connected with described first testing circuit and described second testing circuit, with the switching time that the field effect transistor calculated in described boost chopper and described full-bridge direct current converter controls, and signal is passed to described pulse-width modulation driving isolation circuit, the described signal received is carried out isolated variable by described pulse-width modulation driving isolation circuit.
6. fuel cell DC/DC converting means according to claim 5, it is characterized in that, described boost chopper comprises energy storage inductor, counnter attack diode, field effect transistor switch pipe and filter capacitor, described energy storage inductor one end is connected with described fuel cell, one end is connected between the drain electrode of described field effect transistor switch pipe and the anode of described counnter attack diode in addition, the negative electrode of described counnter attack diode is connected between the positive pole of described filter capacitor and the input of described full-bridge direct current converter, the gate pole of described field effect transistor switch pipe is connected with described pulse-width modulation driving isolation circuit, the source electrode of described field effect transistor switch pipe is connected between the negative pole of described fuel cell and described filter capacitor, the negative pole of described filter capacitor is connected with described full-bridge direct current converter.
7. fuel cell DC/DC converting means according to claim 6, it is characterized in that, described full-bridge direct current converter comprises the field effect transistor be operably connected, capacitance, power transformer, Half bridge rectifier diode, filter inductance, filter resistance, and filter capacitor.
8. fuel cell DC/DC converting means according to claim 7, it is characterized in that, the described field effect transistor of described full-bridge direct current converter comprises the first field effect transistor, second field effect transistor, 3rd field effect transistor and the 4th field effect transistor, described Half bridge rectifier diode comprises the first Half bridge rectifier diode, second Half bridge rectifier diode, 3rd Half bridge rectifier diode and the 4th Half bridge rectifier diode, described filter inductance comprises the first filter inductance and the second filter inductance, the drain electrode of the second described field effect transistor is between the positive pole and the drain electrode of described first field effect transistor of the filter capacitor of described boost chopper, the source electrode of described second field effect transistor is between described capacitance and the drain electrode of described 3rd field effect transistor, the source electrode of described second field effect transistor is between first pin and the drain electrode of described 4th field effect transistor of described power transformer, described 3rd field effect transistor source electrode is between the negative pole and the source electrode of described 4th field effect transistor of the filter capacitor of described boost chopper, described capacitance one end is between the source electrode and the drain electrode of described 3rd field effect transistor of described first field effect transistor, one end is connected with described power transformer crus secunda in addition, the negative electrode of described first Half bridge rectifier diode is connected with described power transformer the tenth pin, anode is between the anode and described second filter inductance of described second Half bridge rectifier diode, the negative electrode of described second Half bridge rectifier diode is connected with described power transformer the 7th pin, the negative electrode of described 3rd Half bridge rectifier diode is connected with described power transformer the 6th pin, anode is between the anode and described first filter inductance of described 4th Half bridge rectifier diode, the negative electrode of described 4th Half bridge rectifier diode is connected with described power transformer tripod, described second filter inductance one end is between the anode and the anode of described second Half bridge rectifier diode of described first Half bridge rectifier diode, one end is between the negative pole of the described filter capacitor of described first filter inductance and described full-bridge direct current converter in addition, one end of described filter resistance is between described first filter inductance and the described filter capacitor negative pole of described full-bridge direct current converter, one end is between the described filter capacitor and described power transformer the 4th pin of described full-bridge direct current converter in addition, described power transformer the 4th pin is between described power transformer the 5th pin and the described filter capacitor positive pole of described full-bridge direct current converter, described power transformer octal is between the positive pole of the described filter capacitor of described power transformer the 9th pin and described full-bridge direct current converter.
9. fuel cell DC/DC converting means according to claim 1, is characterized in that, described preset value Vr1 is greater than preset value Vr2, and described preset value Vr2 is greater than the voltage value of the under-voltage point of the minimum operating voltage Vr3 of described fuel cell.
10. fuel cell DC/DC converting means according to claim 9, is characterized in that, described preset value Vr1 is between 42 ~ 50V, and described preset value Vr2 is between 26 ~ 30V, and described minimum operating voltage Vr3 is between 23 ~ 25V.
The control method of 11. 1 kinds of fuel cell DC/DC converting means, described fuel cell DC/DC converting means comprises for realizing the boost chopper boosted, and realize the full-bridge direct current converter of isolation and step-down, it is characterized in that, described method comprises the steps:
A (), when detecting that the output voltage Ve of described fuel cell is between the open circuit voltage and a preset value Vr1 of described fuel cell, described boost chopper quits work, carry out power converter to described load circuit by described full-bridge direct current converter;
B (), when detecting that the output voltage Ve of described fuel cell is less than described preset value Vr1, the output voltage of described boost chopper is increased to described preset value by described boost chopper.
The control method of 12. fuel cell DC/DC converting means according to claim 11, it is characterized in that, described full-bridge direct current converter comprises the field effect transistor be operably connected, capacitance, power transformer, Half bridge rectifier diode, filter inductance, filter resistance, and filter capacitor, the described field effect transistor of described full-bridge direct current converter comprises the first field effect transistor, second field effect transistor, 3rd field effect transistor and the 4th field effect transistor, described Half bridge rectifier diode comprises the first Half bridge rectifier diode, second Half bridge rectifier diode, 3rd Half bridge rectifier diode and the 4th Half bridge rectifier diode, described filter inductance comprises the first filter inductance and the second filter inductance, the drain electrode of the second described field effect transistor is between the positive pole and the drain electrode of described first field effect transistor of the filter capacitor of described boost chopper, the source electrode of described second field effect transistor is between described capacitance and the drain electrode of described 3rd field effect transistor, the source electrode of described second field effect transistor is between first pin and the drain electrode of described 4th field effect transistor of described power transformer, described 3rd field effect transistor source electrode is between the negative pole and the source electrode of described 4th field effect transistor of the filter capacitor of described boost chopper, described capacitance one end is between the source electrode and the drain electrode of described 3rd field effect transistor of described first field effect transistor, one end is connected with described power transformer crus secunda in addition, the negative electrode of described first Half bridge rectifier diode is connected with described power transformer the tenth pin, anode is between the anode and described second filter inductance of described second Half bridge rectifier diode, the negative electrode of described second Half bridge rectifier diode is connected with described power transformer the 7th pin, the negative electrode of described 3rd Half bridge rectifier diode is connected with described power transformer the 6th pin, anode is between the anode and described first filter inductance of described 4th Half bridge rectifier diode, the negative electrode of described 4th Half bridge rectifier diode is connected with described power transformer tripod, described second filter inductance one end is between the anode and the anode of described second Half bridge rectifier diode of described first Half bridge rectifier diode, one end is between the negative pole of the described filter capacitor of described first filter inductance and described full-bridge direct current converter in addition, one end of described filter resistance is between described first filter inductance and the described filter capacitor negative pole of described full-bridge direct current converter, one end is between the described filter capacitor and described power transformer the 4th pin of described full-bridge direct current converter in addition, described power transformer the 4th pin is between described power transformer the 5th pin and the described filter capacitor positive pole of described full-bridge direct current converter, described power transformer octal is between the positive pole of the described filter capacitor of described power transformer the 9th pin and described full-bridge direct current converter
The control method of 13. fuel cell DC/DC converting means according to claim 12, it is characterized in that, described preset value Vr1 is between 42 ~ 50V.
The control method of 14. fuel cell DC/DC converting means according to claim 12, it is characterized in that, detect that the output voltage of described boost chopper is Vb, and in such a way by the output voltage Vb of boost chopper described in the duty cycle adjustment that changes the field effect transistor switch pipe control signal of described boost chopper:
C (), as Ve>Vr1, the controller of described fuel cell DC/DC converting means is 0 to the duty ratio of described field effect transistor switch pipe control signal, all should quit work by switching tube to make described field; And
D (), as Ve≤Vr1, described controller, by changing the duty ratio of described field effect transistor switch pipe control signal, regulates the output voltage Vb of filter circuit, makes Vb equal described preset value Vr1.
The control method of 15. fuel cell DC/DC converting means according to claim 14, it is characterized in that, in described full-bridge direct current converter described first and the conducting simultaneously of the 4th field effect transistor turn off simultaneously, the duty ratio of the control signal pulse-width modulation of its correspondence is Ton, described second and the 3rd field effect transistor simultaneously conducting turn off simultaneously, the pulse width modulation duty of the control signal of its correspondence is 1-Ton-Td, wherein Td is Dead Time, and described controller can control output voltage and the electric current of described full-bridge direct current converter by the size of control Ton.
The control method of 16. fuel cell DC/DC converting means according to claim 15, it is characterized in that, the input voltage of the measurement fuel cell that described controller receives is Ve, the output voltage Vo of described fuel cell DC/DC converting means and output current Io, according to the rated operational voltage set point Vr4 of load circuit setting, maximum output current limits value Ir1, the fuel battery voltage set point Vr2 of fuel cell property settings,, its method controlling the pulse width modulation duty Ton in described full-bridge direct current converter is as follows:
(1) E1 (k)=Ve (k)-Vr2, EC1 (k)=(1-a1) * (E1 (k)-E1 (k-1))+a1*EC1 (k-1), wherein a1 is setting coefficient;
(2) error E 1 (k) obtained according to step (1) calculates output PID1 (k), if PID1 (k) >=Vr4, PID1 (k) equals Vr4 with error rate EC1 (k) by PID;
(3) E2 (k)=PID1 (k)-Vo (k), EC2 (k)=(1-a2) * (E2 (k)-E2 (k-1))+a2*EC2 (k-1), wherein a2 is setting coefficient;
(4) error E 2 (k) obtained according to step (3) calculates output PID2 (k), if PID2 (k) >=Ir1, PID2 (k) equals Ir1 with error rate EC2 (k) by PID;
(5) E3 (k)=PID2 (k)-Io (k), EC3 (k)=(1-a3) * (E3 (k)-E3 (k-1))+a3*EC3 (k-1), wherein a3 is setting coefficient;
(6) error E 3 (k) obtained according to step (5) calculates output PID3 (k) with error rate EC3 (k) by PID, and PID3 (k) is the PWM control duty ratio Ton that full-bridge direct current converter (3) exported to by controller (6); Wherein, k is this sub-value, and k-1 is last value.
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