Abstract:
This invention provides a kind of mixed power supply energy management method for fuel battery, including the following steps: initialization; control the output current of DCDC converting unit according to the measured energy storage device voltage and the actual current outputted by the DCDC converting unit, respond to the energy need resulting from load condition change and at the same time ensure the energy storage device to be in a best charge state; send a current setting instruction to the DCDC converting unit. This invention does not adopt the SOC calculation mode any more, the system no longer relies on the accuracy, reliability of current sensor; and this invention is strongly compatible, highly reliable, strongly practical and stable in output voltage, with the same system being applicable to more vehicles of different models (forklift) and parameter correction being unnecessary. By correcting battery capacity decrease in advance through setting up parameters in advance, the long-term reliability of the system is ensured.

Description:
PRIORITY 
     The present invention claims priority to PCT patent application PCT/CN2013/083379, which has a filing date of Sep. 12, 2013. The present invention claims priority to Chinese patent application 201210375871, which has a filing date of Sep. 28, 2012. 
     FIELD OF THE INVENTION 
     This invention relates to fuel cell mixed power supply energy management method. 
     BACKGROUND 
     Through retrieving existing technologies, the following literatures are retrieved: 
     The fuel cell power supply control principle publicized by the invention patent application of China called “power distribution method for fuel cell mixed power system” with application number “200310103253.3”: Adopt SOC calculation to control according to measurement load control signal (such as throttle signal) and power cell SOC (state of charge) the output of the fuel cell DCDC to satisfy the energy demands of the load system, fuel cell system and power cell pack under the state of charge. 
     The fuel cell power supply control method publicized by the invention patent application of China called “fuel cell based mixed power device energy management system” with application number “201010108281.4” also adopts SOC calculation, where, 
     Here is the calculation formula for the state of charge (SOC):
 
soc( k )=( BC ×soc( k− 1)−∫ k-1   k   i   out   dt+∫   k-1   k   i   out   dt )/ BC  
 
     In the above calculation formula, BC represents cell capacity, soc(k) represents the SOC value of cell at current moment, soc(k−1) represents the SOC value at the previous moment, i out  represents cell discharging current and i in  represents cell charging current. 
     It is known from the above formula that the SOC calculation is a kind of algorithm to obtain the state of charge (SOC) of battery according to the battery current data collected, the cell capacity data set, based on the integration algorithm and by correcting according to the actual cell capacity, cell voltage, temperature at the time of actual use. That invention application has the following disadvantages: 
     1. All the above control method relies on SOC calculation; and the SOC calculation relies on accurate current data, the accuracy of current data depends on the accuracy, sensitivity, stability of current measurement device; however, the current measurement device also has an error; therefore, the SOC calculation method can only be an approximate estimation of the state of charge of the energy storage device. The existing fuel cell system on board vehicle using the SOC calculating method adopts a dual-range current sensor in order to obtain a relatively accurate current value; however, a dual-range current sensor is unable to cover the whole range and at the same time is also unable to avoid the zero drift that the current sensor has, therefore, the current sensor has to be calibrated frequently. In this circumstance, a fuel cell company, after selling a fuel cell system on board vehicle, has to calibrate regularly the current measurement device sensor. The product immaturity will directly influence the mercerization progress of fuel cell vehicles. 
     2. The capacity of the energy storage device (battery) may reduce with use gradually. It is known from the formula that in order to obtain SOC accurately, it is imperative to have an accurate capacity value of the energy storage device. Therefore, it is imperative to calibrate the capacity of the energy storage device (battery), which can only be a vague estimation. Therefore, it is unable to accurately conduct the fuel cell system energy management by adopting the SOC calculation method. 
     3. The current output fluctuation amplitude is large when a forklift is working. 
     The voltage of the energy storage device (battery) used on fuel cell bus, fuel cell car as auxiliary power is often hundreds of volts, the current range is from negative tens of amperes to positive tens of amperes; under the circumstance that the current range is small, the accuracy of battery current value is relatively high, under this working condition, though the use of the SOC calculation method is not so good as the said fuel cell mixed power supply energy management method, it is barely satisfactory. 
     The voltage of the energy storage device (battery) used on fuel cell forklift as auxiliary power is often tens of volts, but the current range fluctuates largely. For example, the common nominal voltage 24V corresponds to a working current range −500˜500 A; the nominal voltage 36V corresponds to a working current range −800˜1000 A, the nominal voltage 48V corresponds to a current range −600˜800 A. This is because when a fuel cell forklift is working, it constantly lifts loads, drives at an accelerated speed, brakes, etc. that result in the output current of the battery increasing from several amperes gradually to hundreds of amperes and even a thousand amperes and turning from outputting a thousand amperes to inputting hundreds of amperes. As the current range is large, it is very difficult to measure the current value accurately; at the same time, that the current output fluctuation frequency is high when a forklift is working further makes real-time and accurate current measurement become very difficult; and SOC integration algorithm can also amplify the deviation constantly. Therefore, it is unable to realize an accurate fuel cell system energy management by adopting the SOC calculation method on a fuel cell forklift. 
     4. Energy recovery issue, protection issue. 
     When a fuel cell vehicle with an energy recovery system (such as the invention patent application called “power distribution method for fuel cell mixed power system” with application number “200310103253.3”) brakes for energy recovery, the energy resulting from braking is input in the energy storage device with a current being often as high as hundred of amperes and even up to 1000 A in some cases, then the voltage of the energy storage device will increase sharply, at the same time, the internal resistances of cables, connections, relays, etc. in the circuits through which current passes at recovery braking can all cause the vehicle voltage to rise; if the battery voltage exceeds the protection voltage of the energy storage device, or the vehicle voltage exceeds the protection voltage of the vehicle, the system or vehicle may disconnect the relay making external connection to realize equipment protection. As a result of disconnecting the relay, the energy storage device is unable to continue to absorb the braking energy and braking can not proceed normally. The vehicle may be out of control and even have an accident. In order that at energy recovery, the voltage of the energy storage device does not exceed the protection voltage of the energy storage device, or the vehicle voltage does not exceed the protection voltage of the vehicle, it is imperative to control the actual state of charge (SOC) of the energy storage device to be a right or a lower value. 
     However, as the SOC calculation is based on the measured battery current value and the actual battery capacity and as the battery current data, the actual battery capacity can not be measured accurately, it results in the SOC calculation method being unable to obtain the actual SOC values. When the SOC measurement value is lower than the actual value, the actual state of charge (SOC) of the energy storage device is at a high value, the voltage of the energy storage device will exceed the protection voltage of the energy storage device or the protection voltage of the vehicle; this will constitute a safety hazard to the fuel cell vehicle. 
     The said fuel cell mixed power supply energy management method is to control the output current of the DCDC converting unit, respond to the energy demand resulting from load condition change and at the same time ensure the energy storage device to be in a best state of charge according to the measured voltage of the energy storage device and the actual current output by the DCDC converting unit under the circumstance without connecting the vehicle operation input signal (throttle, brake) and calculating SOC. 
     SUMMARY 
     The said fuel cell mixed power supply energy management method includes the following steps: 
     Step S 201 : Initialize, specifically, obtain the following parameter values first:
     The first current setting of DCDC Isetmin,   The first voltage setting of energy storage device Umax,   The second voltage setting of energy storage device Umin,   The permissible DCDC current deviation value Ipermissible,   The maximum current setting that DCDC allows to output Imax,
 
Then let the current setting of DCDC Iset equal to the said first current setting of DCDC Isetmin;
   

     Step S 202 : Obtain the energy storage device voltage Ustorage and the actual output current of DCDC converting unit Idcdc, calculate according to the following formula (1) DCDC current deviation value Ideviation:
 
 I deviation= I set− Idcdc   Formula (1);
 
     Step S 203 : in case of meeting the following circumstances, enter into Step S 204 , Step S 205  or Step S 206 :
     If the energy storage device voltage Ustorage is greater than or equal to the first voltage setting of energy storage device Umax, then enter into Step S 204 ,   If the energy storage device voltage Ustorage is less than or equal to the first voltage setting of energy storage device Umin, then enter into Step S 205 ,   If the energy storage device voltage Ustorage is less than the first voltage setting of energy storage device Umax and greater than the first voltage setting of energy storage device Umin, and the DCDC current deviation value Ideviation is greater than or equal to the permissible DCDC current deviation value Ipermissible, then enter into Step S 206 ,   If the energy storage device voltage Ustorage is less than the first voltage setting of energy storage device Umax and greater than the first voltage setting of energy storage device Umin, and the DCDC current deviation value Ideviation is less than the permissible DCDC current deviation value Ipermissible, then enter into Step S 207 ;   

     Step S 204 : If the current setting of DCDC Iset is greater than the first current setting of DCDC Isetmin, then gradually reduce the current setting of DCDC Iset, and then enter into Step S 207 ; if the current setting of DCDC Iset is less than or equal to the first current setting of DCDC Isetmin, then let the current setting of DCDC Iset is equal to the said first current setting of DCDC Isetmin and then enter into Step S 207 ; 
     Step S 205 : If the current setting of DCDC Iset is less than the maximum current setting that DCDC allows to output Imax, increase the current setting of DCDC Iset and then enter into Step S 207 ; if the current setting of DCDC Iset is greater than or equal to the maximum current setting that DCDC allows to output Imax, let the current setting of DCDC Iset equal to the maximum current setting that DCDC allows to output Imax and then enter into Step S 207 ; 
     Step S 206 : If the current setting of DCDC Iset is greater than the first current setting of DCDC Isetmin, reduce at a fastest speed the current setting of DCDC Iset and then enter into Step S 207 ; if the current setting of DCDC Iset is less than or equal to the first current setting of DCDC Isetmin, let the current setting of DCDC Iset equal to the said first current setting of DCDC Isetmin and then enter into Step S 207 ; 
     Step S 207 : Send a current setting instruction to DCDC converting unit, in which the said current setting instruction is used to set the output current of the DCDC converting unit as the current setting of DCDC Iset and then return to Step S 202 . 
     Preferably, before the said Step S 201 , the following steps executed in proper order are also included: 
     Step A 1 : Determine the limit voltage Ulim, specifically, judge if the highest limit of load protection voltage is greater than the charging protection voltage of the energy storage device; if the judgment result is positive, set the limit voltage Ulimit as equal to the charging protection voltage of the energy storage device; if the judgment result is negative, set the limit voltage Ulimit as equal to the highest limit of load protection voltage; 
     Step A 2 : Determine the expected DCDC converting unit output current Iexpect according to the following formula (2): 
     
       
         
           
             Iexpect 
             = 
             
               
                 Irated 
                 · 
                 Edcdc 
               
               
                 U 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 lim 
               
             
           
         
       
     
     Where Irated is the rated output power of the fuel cell, Edcdc is the efficiency of the DCDC converting unit; 
     Step A 3 : 
     On the current curve using expected DCDC converting unit output current as a constant charging value, obtain the corresponding charging capacity as 50%˜90% of the voltage interval, select any voltage value in the voltage interval as the first voltage setting of energy storage device Umax. 
     Preferably, in the said Step A 3 , from the corresponding charging capacity being any voltage value or voltage interval below, set the said voltage value as or select any voltage value in the said voltage interval as the first voltage setting of energy storage device Umax:
         The corresponding charging capacity is the voltage value at 90%, determine the voltage value at the said 90% as the first voltage setting of energy storage device Umax,   The corresponding charging capacity is 60%˜80% voltage interval, select any voltage value in the said 60%˜80% voltage interval to be determined as the first voltage setting of energy storage device Umax,   The corresponding charging capacity is 80%˜90% voltage interval, select any voltage value in the said 80%˜90% voltage interval to be determined as the first voltage setting of energy storage device Umax,   The corresponding charging capacity is 50%˜60% voltage interval, select any voltage value in the said 50%˜60% voltage interval to be determined as the first voltage setting of energy storage device Umax.       

     Preferably, before the said Step S 201 , the following steps executed in proper order are also included: 
     Step B 1 : Determine the system limit charging current, specifically, 
     Under the working condition in which the system uses medium limit energy recovery, first use battery to make a braking action and obtain the system current, time data from braking to the end, the negative current of that system is the charging current, calculate the average of that charging current as the system limit charging current; 
     Step B 2 : Determine the limit voltage Ulim, specifically, judge if the highest limit of load protection voltage is greater than the charging protection voltage of the energy storage device; if the judgment result is positive, set the limit voltage Ulimit as equal to the charging protection voltage of the energy storage device; if the judgment result is negative, set the limit voltage Ulimit as equal to the highest limit of load protection voltage; 
     Step B 3 : Determine the expected DCDC converting unit output current Iexpect according to the following formula (2): 
     
       
         
           
             Iexpect 
             = 
             
               
                 Irated 
                 · 
                 Edcdc 
               
               
                 U 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 lim 
               
             
           
         
       
     
     Where Irated is the rated output of the fuel cell, Edcdc is the efficiency of the DCDC converting unit; 
     Step B 4 : Inquire the testing curves of different charging currents and charging capacitances; according to the constant current charging curve that the system limit charging current corresponds to, obtain the corresponding charging capacitance when charging to the limit voltage; according to that charging capacity, look up the corresponding voltage value on the constant current charging curve that the expected DCDC converting unit output current Iexpect corresponds to, the said corresponding voltage value is the first voltage setting of energy storage device Umax; 
     Step B 5 : According to the energy recovery working condition when the system uses time limit, do actual testing by using the system controlled by the first voltage setting of energy storage device Umax, correct the first voltage setting of energy storage device Umax so that the actually measured highest voltage is slightly lower than the limit voltage Ulim; 
     Step B 6 : Correct the capacity of the energy storage device, specifically, according to the relational curve between energy storage device charging capacity/rated capacity and cycle times, or the relational curve between the discharging capacity/rated capacity and cycle times, inquire the charging capacity/rated capacity ratio after multiple cycles, and then take the product of the first voltage setting of energy storage device Umax and the charging capacity/rated capacity ratio as the corrected first voltage setting of energy storage device Umax. 
     Preferably, before the said Step S 201 , the following steps executed in proper order are also included: 
     Step C 1 : Determine the minimum consumption current of the auxiliary system Is, specifically, use the system controlled by the first voltage setting of energy storage device Umax to have the system be in an idle condition, after the system becomes stable, the consumption of the auxiliary system reduces to the minimum, measure the current of the auxiliary system at this time, which is the minimum consumption current; 
     Step C 2 : take the product of the minimum consumption current of the auxiliary system and the coefficient K as the first current setting of DCDC Isetmin, where the coefficient K is less than 1. 
     Preferably, the coefficient K is 0.6. 
     Preferably, before the said Step S 201 , the following steps executed in proper order are also included: 
     Step D 1 : Determine according to the follow formula (3) the maximum current setting that DCDC allows to output Imax: 
     
       
         
           
             
               I 
               ⁢ 
               
                   
               
               ⁢ 
               max 
             
             = 
             
               
                 Irated 
                 · 
                 Edcdc 
               
               
                 U 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 max 
               
             
           
         
       
     
     Preferably, before the said Step S 201 , the following steps executed in proper order are also included: 
     Step E 1 : Determine according to the following formula (4) the capacitance at the minimum load Cmin:
 
 C min= C −( Is−I   setmin )· T  
 
     Where, C is the charging capacity, Is is the minimum consumption current of the auxiliary system, T is time, the said charging capacity is the charging capacity that the first voltage setting of energy storage device Umax corresponds to inquired on the charging capacity and charging voltage curve with constant current charging taking the maximum current setting that DCDC allows to output Imax as the current, the said time is set according to the response speed that the system requires; 
     Step E 2 : According to the capacitance at minimum load Cmin, inquire the charging voltage that the capacitance at the minimum load Cmin corresponds to on the charging capacity and charging voltage curve with constant current charging taking the maximum current setting that DCDC allows to output Imax as the current, select that charging voltage as the second voltage setting of energy storage device Umin. 
     This invention provides a fuel cell mixed power supply energy management method. The said method is to control the output current of the DCDC converting unit, respond to the energy demand resulting from load condition change and at the same time ensure the energy storage device to be in a best state of charge according to the measured voltage of the energy storage device and the actual current output by the DCDC converting unit under the circumstance without connecting the vehicle operation input signal (throttle, brake) and calculating SOC. 
     In comparison with the existing technology, the said fuel cell mixed power supply energy management method has the following beneficial effects:
     1. Improve the fault-tolerant capability of the system. As the control method no longer adopts the SOC calculation mode, the system no longer relies on the accuracy, reliability of the current sensor.   2. Strong compatibility. By setting the charging current condition at a limit condition, the same system is applicable to more models of different vehicles (forklift) and no parameter correction is necessary.   3. High reliability. By setting parameters beforehand to correct in advance the reduction in batter capacity, the long-term system reliability is ensured. The said fuel cell mixed power supply energy management method also uses the data of the energy storage device in determining parameters. These data are that measured in laboratory under a stable working condition; and in the existing system using the SOC calculation mode, the data of the energy storage device is calculated on real-time basis when the system is working, which a kind of dynamic estimation with the accuracy is being not satisfactory.   4. Stable output voltage. The system controls the energy storage device voltage near the first voltage setting of energy storage device Umax, the second voltage setting of energy storage device Umin, this favors to extend the service life to use the vehicle equipment, the energy storage device.   5. Strong practicality. The said fuel cell mixed power supply energy management method is obtained by conducting a lot of actual tests and verifications on multiple models of forklift fuel cells and constant adjustment. A verification was also made on the fuel cell system of a tourist coach. It can not only be used on vehicles, but also adapts to a power supply system.   

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       By reading and referring to the detailed descriptions made to the non-restrictive embodiment examples by the following attached figures, other characteristics, purposes and advantages of this invention will become more evident: 
         FIG. 1  is the general framework flow chart of the first fuel cell mixed power supply energy management method; 
         FIG. 2  is the flow chart of the second type of fuel cell mixed power supply energy management method; 
         FIG. 3  is the flow chart of the third type of fuel cell mixed power supply energy management method; 
         FIG. 4  is the flow chart of the forth type of fuel cell mixed power supply energy management method; 
         FIG. 5  is the flow chart of the fifth type of fuel cell mixed power supply energy management method; 
         FIG. 6  is the schematic diagram of current curve of the DCDC converting unit output current with charging expected at a constant value; 
         FIG. 7  is the system limit current test curve; 
         FIG. 8  is the schematic diagram for selecting the first voltage setting of energy storage device Umax; 
         FIG. 9  is the schematic diagram for the process of correcting the first voltage setting of energy storage device Umax; 
         FIG. 10  is the curve for the relation between energy storage device charging capacity/rated capacity and cycle times; 
         FIG. 11  is the schematic diagram of the structure of the compact type fuel cell supply system of the first embodiment example provided according to this invention; 
         FIG. 12  is the specific structural schematic diagram of the DCDC converting unit in the compact type fuel cell supply system as shown in  FIG. 11 ; 
         FIG. 13  shows the schematic diagram of the high-power diode position in the compact type fuel cell supply system of a preferable case of the first embodiment example provided according to this invention; 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description to this invention is to be made below by combining with specific embodiment examples. The following embodiment examples will help the technical personnel in this field further understand this invention, but it does not limit this invention in any form. It should be pointed out that for ordinary technical people in this field, adjustments and changes can also be made under the prerequisite of not being divorced from the conceiving of this invention. All these belong to the protection scope of this invention. 
       FIG. 1  is the general framework flow chart of the first fuel cell mixed power supply energy management method; specifically, in this embodiment example, Step S 201  is executed first to initialize, more specifically, to obtain the parameters set by the system, such parameters include the first current setting of DCDC Isetmin, the first voltage setting of energy storage device Umax, the second voltage setting of energy storage device Umin, the permissible DCDC current deviation value Ipermissible, the maximum current setting that DCDC allows to output Imax, and then let the current setting of DCDC Iset equal to the said first current setting of DCDC Isetmin, where the said energy storage device can be a high energy lithium ion cell and a high capacity super capacitor, etc. 
     Next Step S 202  is executed to obtain the energy storage device voltage Ustorage and the actual output current of the DCDC converting unit Idcdc. The DCDC current deviation value Ideviation is calculated according to the following formula (1):
 
 I deviation= I set− Idcdc   Formula (1);
 
     Then Step S 203  is executed: enter into Step S 204 , Step S 205  or Step S 206  correspondingly if the following conditions are met:
     If the energy storage device voltage Ustorage is greater than or equal to the first voltage setting of energy storage device Umax, then enter into Step S 204 ,   If the energy storage device voltage Ustorage is less than or equal to the first voltage setting of energy storage device Umin, then enter into Step S 205 ,   If the energy storage device voltage Ustorage is less than the first voltage setting of energy storage device Umax and greater than the first voltage setting of energy storage device Umin, and the DCDC current deviation value Ideviation is greater than or equal to the permissible DCDC current deviation value Ipermissible, then enter into Step S 206 ,   If the energy storage device voltage Ustorage is less than the first voltage setting of energy storage device Umax and greater than the first voltage setting of energy storage device Umin, and the DCDC current deviation value Ideviation is less than the permissible DCDC current deviation value Ipermissible, then enter into Step S 207 ;   

     In which for Step S 204 : if the current setting of DCDC Iset is greater than the first current setting of DCDC Isetmin, reduce gradually the current setting of DCDC Iset and then enter into Step S 207 ; if the current setting of DCDC Iset is less than or equal to the first current setting of DCDC Isetmin, let the current setting of DCDC Iset equal to the said the first current setting of DCDC Isetmin and then enter into Step S 207 ; 
     Step S 205 : If the current setting of DCDC Iset is less than the maximum current setting that DCDC allows to output Imax, increase the current setting of DCDC Iset and then enter into Step S 207 ; if the current setting of DCDC Iset is greater than or equal to the maximum current setting that DCDC allows to output Imax, let the current setting of DCDC Iset equal to the maximum current setting that DCDC allows to output Imax and then enter into Step S 207 ; 
     Step S 206 : If the current setting of DCDC Iset is greater than the first current setting of DCDC Isetmin, reduce at the fastest speed the current setting of DCDC Iset and then enter into Step S 207 ; if the current setting of DCDC Iset is less than or equal to the first current setting of DCDC Isetmin, let the current setting of DCDC Iset equal to the said the first current setting of DCDC Isetmin and then enter into Step S 207 ; 
     Step S 207 : Send a current setting instruction to DCDC converting unit, where the said current setting instruction is used to set the output current of the DCDC converting unit as the current setting of DCDC Iset and then return to Step S 202 . 
       FIGS. 5 to 8  show the flow charts of type 1 to type 4 fuel cell mixed power supply energy management methods. The technical people in this field can understand the embodiment examples as shown in  FIGS. 5 to 8  as 4 preferable cases of the embodiment examples as shown in  FIG. 11 , specifically, such 4 preferable cases show 4 types of different embodiments of the said Step S 203  in  FIG. 11 . 
     For example, in  FIG. 12 , first judge if “the energy storage device voltage Ustorage is less than or equal to the first voltage setting of energy storage device Umin”, if the judgment result is negative, judge “if the energy storage device voltage Ustorage is greater than or equal to the first voltage setting of energy storage device Umax” next, if the judgment result is negative again, then judge “if the DCDC current deviation value Ideviation is greater than or equal to the permissible DCDC current deviation value Ipermissible”. In which, the technical people in this field understand that when the said energy storage device voltage Ustorage is greater than the first voltage setting of energy storage device Umax or less than the first voltage setting of energy storage device Umin, the DCDC current deviation value Ideviation is not greater than the permissible DCDC current deviation value Ipermissible. 
     Again for example, in  FIG. 13 , first judge “if the energy storage device voltage Ustorage is greater than or equal to the first voltage setting of energy storage device Umax”, if the judgment result is negative, then judge “if the energy storage device voltage Ustorage is less than or equal to the first voltage setting of energy storage device Umin” next, if the judgment result is negative again, then judge “if the DCDC current deviation value Ideviation is greater than or equal to the permissible DCDC current deviation value Ipermissible”. 
     Again for example, in  FIG. 4 , first judge “if the energy storage device voltage Ustorage is less than the first voltage setting of energy storage device Umax and greater than the first voltage setting of energy storage device Umin, and if the DCDC current deviation value Ideviation is greater than or equal to the permissible DCDC current deviation value Ipermissible”, if the judgment result is negative, then judge “if the energy storage device voltage Ustorage is less than or equal to the first voltage setting of energy storage device Umin” next, if the judgment result is negative again, then judge “if the energy storage device voltage Ustorage is greater than or equal to the first voltage setting of energy storage device Umax”. 
     Again for example, in  FIG. 5 , first judge “if the energy storage device voltage Ustorage is less than the first voltage setting of energy storage device Umax and greater than the first voltage setting of energy storage device Umin, and if the DCDC current deviation value Ideviation is greater than or equal to the permissible DCDC current deviation value Ipermissible”, if the judgment result is negative, then judge “if the energy storage device voltage Ustorage is greater than or equal to the first voltage setting of energy storage device Umax” next, if the judgment result is negative again, then judge “if the energy storage device voltage Ustorage is less than or equal to the first voltage setting of energy storage device Umin”. 
     In a preferable case of this embodiment example, before the said Step S 201 , parameters are determined in the following way: the first voltage setting of energy storage device Umax, the second voltage setting of energy storage device Umin, the permissible DCDC current deviation value Ipermissible and the maximum current setting that DCDC allows to output Imax. 
     A. In case of system having no energy recovery (adopt a mechanical brake, brake by using the friction between brake block and hub, consume the energy resulting from braking), the steps to determine the first voltage setting of energy storage device Umax are shown below: 
     Step A 1 : Determine the limit voltage Ulim, specifically, judge if the highest limit of load protection voltage is greater than the charging protection voltage of the energy storage device; if the judgment result is positive, set the limit voltage Ulimit as equal to the charging protection voltage of the energy storage device; if the judgment result is negative, set the limit voltage Ulimit as equal to the highest limit of load protection voltage; where, the load protection voltage is a range value, the charging protection voltage of the energy storage device is a numerical value, all of which are to be supplied by the supplier. 
     Step A 2 : Determine the expected DCDC converting unit output current Iexpect according to the following formula (2): 
     
       
         
           
             Iexpect 
             = 
             
               
                 Irated 
                 · 
                 Edcdc 
               
               
                 U 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 lim 
               
             
           
         
       
     
     Where, Irated is the rated output power of the fuel cell, Edcdc is the efficiency of the DCDC converting unit; 
     Step A 3 : 
     On the current curve using expected DCDC converting unit output current as a constant charging value, obtain the corresponding charging capacity as 50%˜90% voltage interval, select any voltage value in that voltage interval as the first voltage setting of energy storage device Umax. Where, (the current curve with the said expected DCDC converting unit output current as a constant charging value can be supplied by the cell supplier, If there is no right data, approximate currents can be used for replacement, or the curve can be obtained by fitting according to the data at other currents. For example, the curve as shown in  FIG. 6 ). 
     Further preferably, in the said Step A 3 , different charging capacities were selected according to different energy storage devices, different service life requirements. Specifically, from the corresponding charging capacity being as any following voltage value or voltage interval, determine the said voltage value as or select any voltage value of the said voltage interval as the first voltage setting of energy storage device Umax:
     For a system with a super capacitor and fuel cell, the corresponding charging capacity is the voltage value at 90%, determine the voltage value at the said 90% as the first voltage setting of energy storage device Umax,   For battery and fuel cell being used as a power system (for example, vehicle), the corresponding charging capacity is 60%˜80% voltage interval, select any voltage value of the said 60%˜80% voltage interval to be determined as the first voltage setting of energy storage device Umax;   For battery (with a poor high current discharging capacity) and fuel cell being used as a power system (for example, vehicle), the corresponding charging capacity is 80%˜90% voltage interval, select any voltage value of the said 80%˜90% voltage interval to be determined as the first voltage setting of energy storage device Umax,   For battery and fuel cell being used as a non-power system (for example, a power supply for communication base), the corresponding charging capacity is 50%˜60% voltage interval, select any voltage value of the said 50%˜60% voltage interval to be determined as the first voltage setting of energy storage device Umax to maintain a super long service life.   

     B. In case of a system with energy recovery, the steps to determine the first voltage setting of energy storage device Umax are shown below: 
     Step B 1 : Determine the system limit charging current, specifically, under the energy recovery working condition in which the system uses a medium limit (for example, a forklift brakes with the heaviest weight lifted, the highest slope (a permissible slope circumstance for forklift), accelerating down a slope to the end thereof), use batter first to make a braking action to obtain the system current, time data from braking until its end, as shown in  FIG. 7 , the negative current of that system is the charging current, calculate the average of that charging current as the system limit charging current; 
     Step B 2 : Determine the limit voltage Ulim, specifically, judge if the highest limit of load protection voltage is greater than the charging protection voltage of the energy storage device; if the judgment result is positive, then set the limit voltage Ulimit as equal to the charging protection voltage of the energy storage device; if the judgment result is negative, then set the limit voltage Ulimit as equal to the highest limit of load protection voltage; 
     Step B 3 : Determine according to the following formula (2) the expected DCDC converting unit output current Iexpect: 
     
       
         
           
             Iexpect 
             = 
             
               
                 Irated 
                 · 
                 Edcdc 
               
               
                 U 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 lim 
               
             
           
         
       
     
     Where, Irated is the rated output power of the fuel cell, Edcdc is the efficiency of the DCDC converting unit; 
     Step B 4 : Inquire the test curves with different charging currents and charging capacities; according to the constant current charging curve that the system limit charging current corresponds to, obtain the corresponding charging capacity when charging to the limit voltage; according to that charging capacity, find the corresponding voltage value on the constant current charging curve that the expected DCDC converting unit output current Iexpect corresponds to, the said corresponding voltage value is the first voltage setting of energy storage device Umax, as shown in  FIG. 8 ; in which, the technical people in this field understand that the test curves with different charging currents and charging capacities (AH) can be obtained from the manufacturer. 
     Step B 5 : According to the energy recovery working condition in which the system uses the time limit, conduct actual testing by using the system controlled by the first voltage setting of energy storage device Umax, correct the first voltage setting of energy storage device Umax so that the actually measured highest voltage is slightly lower than the limit voltage Ulim; 
     Step B 6 : Correct the capacity of the energy storage device, specifically, according to the relational curve between the charging capacity/rated capacity and cycle times of energy storage device, or the relational curve between the discharging capacity/rated capacity and cycle times thereof, inquire the charging capacity/rated capacity ratio after multiple cycles, and then take the product of the first voltage setting of energy storage device Umax and charging capacity/rated capacity ratio as corrected first voltage setting of energy storage device Umax, for example, as shown in  FIG. 9 . 
     Where, as a high current flows past, cable, contactor, cable connection, etc. may cause a voltage drop, which must be corrected. According to the energy recovery working condition in which the system uses time limit, conduct actual testing by using the system controlled by the first voltage setting of energy storage device Umax. 
     If the actually measured highest voltage is higher than the limit voltage, then a correction must be made. 
     If the actually measured highest voltage is much lower than the limit voltage, then a correction can also be made. 
     The correcting formula is:
 
Modified first voltage setting of energy storage device  U max=the first voltage setting of energy storage device  U max*before correction(limit voltage−the first voltage setting of energy storage device  U max before correction)/(actually measured highest voltage−the first voltage setting of energy storage device  U max).
 
     By using the approximation method, gradually change the first voltage setting of energy storage device Umax to conduct testing, after measurement, the corrected first voltage setting of energy storage device Umax is obtained. 
     As shown in  FIG. 10 , according to the relational curve between the charging capacity/rated capacity and cycle times of the energy storage device (that curve is provided by the supplier), inquire the charging capacity/rated capacity ratio after multiple cycles. As the discharging capacity is proportionate to the charging capacity, the relational curve between discharging capacity/rated capacity and cycle times can be used for replacement.
 
The corrected first voltage setting of energy storage device  U max=the charging capacity/rated capacity of the corrected first voltage setting of energy storage device  U max*obtained in Step B6.
 
     What the system uses is the charging capacity/rated capacity after the energy storage device makes 1000 times of rated cycles. 
     Through that step, the influence of reduction in battery capacity on the system is pre-corrected, as a result, it is ensured that it is not necessary to correct in long system service the control parameters (the first voltage setting of energy storage device Umax). But the existing system with a SOC calculation mode has to estimate regularly the actual energy storage device capacity, reset the BC (energy storage device capacity) value in the system to improve the accuracy of SOC calculation. 
     C. The steps to determine the first current setting of DCDC Isetmin are shown below: 
     Step C 1 : Determine the lowest consumption current of the auxiliary system Is, specifically, use the obtained system controlled by the first voltage setting of energy storage device Umax to make the system be in an idle condition, after the system becomes stable, the consumption of the auxiliary system reduces to the minimum value, measure the current of the auxiliary system at this time, which is the lowest consumption current; where the lowest consumption current of the auxiliary system means the current consumed by the auxiliary system to maintain the minimum output of the auxiliary system and at which the fuel cell can be maintained to work. 
     Step C 2 : take the product of the lowest consumption current of the auxiliary system and coefficient K as the first current setting of DCDC Isetmin, where coefficient K is less than 1. 
     Preferably, coefficient K is 0.6, the reason is that the following factors have to be considered in actual setup: 
     a. The coefficient is to be several times higher than the measurement accuracy of the DCDC current measurement device. 
     b. The problem of drifting of the current sensor in long-term operation is to be considered, that the measurement value of the current sensor is higher than the actual current will not influence system operation; that the measurement value of the current sensor is lower than the actual current will influence system operation. 
     By considering the above factors comprehensively, in the preferable cases, coefficient K=0.6. That method need not rely too much on the accuracy, zero point, reaction speed, etc. of the sensor. 
     D. The steps to determine the maximum current setting that DCDC allows to output Imax are shown below: 
     Step D 1 : Determine according to the following formula (3) the maximum current setting that DCDC allows to output Imax: 
     
       
         
           
             
               I 
               ⁢ 
               
                   
               
               ⁢ 
               max 
             
             = 
             
               
                 Irated 
                 · 
                 Edcdc 
               
               
                 U 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 max 
               
             
           
         
       
     
     E. The steps to determine the second voltage setting of energy storage device Umin are shown below: 
     Step E 1 : Determine according to the following formula (4) the minimum charge capacity Cmin:
 
 C min= C −( Is−I   set min )· T  
 
     Where C is charging capacity, Is is the minimum consumption current of the auxiliary system, T is time, the said charging capacity is on the charging capacity and charging voltage curve of constant current charging with the maximum current setting that DCDC allows to output Imax as the current, find that the charging capacity that the first voltage setting of energy storage device Umax corresponds to for the charging voltage, the said time is set according to the response speed required by the system; 
     Step E 2 : According to the minimum charge capacity Cmin, find the charging voltage that the minimum charge capacity Cmin corresponds to on the charging capacity and charging voltage curve of constant current charging with the maximum current setting that DCDC allows to output Imax as the current, select that charging voltage as the second voltage setting of energy storage device Umin. 
     Further, determine through the following method the permissible DCDC current deviation value Ipermissible:
 
 DCDC  current deviation value=the  DCDC  converting unit output current controlled by system controller−the actual output current of  DCDC  converting unit.
 
     Factors to be considered in actual setup: 
     a. The coefficient is to be several times higher than the measurement accuracy of DCDC current measurement device. 
     b. The problem of drifting of the current sensor in long-term operation is to be considered, that the measurement value of the current sensor is higher than the actual current will not influence system operation; that the measurement value of the current sensor is lower than the actual current will influence system operation. 
     Therefore, that value is preferably set as 5 A in this embodiment example. 
     Next, the specific applications of the said fuel cell mixed power supply energy management method is described through 4 different types of working conditions: 
     When the fuel cell power is used in vehicle work through the system that DCDC converting unit output is mixed with the energy storage device (the system as shown in  FIG. 1 ): 
     Working condition 1: When the connected load (vehicle) operates at certain conditions (such as high power, startup), the required system current is higher than the DCDC converting unit current output, the insufficient current part is obtained from the energy storage device, at this time, the energy storage device voltage will inevitably decrease gradually. To avoid that the energy storage device voltage is lower than the minimum working voltage of the energy storage device resulting in the system being unable to operate, when the energy storage device voltage is lower than a certain value (the second voltage setting of energy storage device Umin), the system controller gradually increases the DCDC converting unit output current to make the energy storage device output current reduce gradually and the energy storage device voltage increase gradually. When operating at a high power continuously, the DCDC converting unit output current will increase until reaching the maximum current setting that DCDC allows to output. 
     Thus, through changing the output current of the DCDC converter, the effective and rational distribution of the energy required by the system is accomplished between the fuel cell and energy storage device. 
     Working condition 2: When the operating condition is changed so that the connected load (vehicle) operates at certain conditions (such as low power operation, idle speed), the required system current is less than the current output of DCDC converting unit, the DCDC converting unit charges the energy storage device, at this time, energy storage device voltage will inevitably increase gradually. To avoid that the energy storage device voltage exceeds the charging protection voltage of the energy storage device resulting in system stopping operation, when the energy storage device voltage reaches the set value (the first voltage setting of energy storage device Umax), the system controller gradually reduced the DCDC converting unit output current to make the energy storage device output voltage reduce gradually; when the energy storage device voltage is lower than the set value (the first voltage setting of energy storage device Umax), the DCDC converting unit output current will no longer change. At this time, that DCDC converting unit output current may still be higher than the system current that the system requires to maintain operation at a low power or idle speed, then the system repeats the above step; until the DCDC converting unit output current is less than the system current, the insufficient current part is obtained from the energy storage device, at this time, enter again into the case of above working condition 1. 
     Thus, through changing the output current of the DCDC converter, the replenishment of the electric quantity lost by the energy storage device is accomplished. 
     Working condition 3: When the connected load (vehicle) changes suddenly in some condition (from operation at a high power to operation at a low operation), the required system current reduces, the DCDC converting unit output current also reduces with it, at this time, the DCDC converting unit output current controlled by the system controller is higher than the actual output current of the DCDC converting unit. When the DCDC current deviation value is greater than or equal to the permissible DCDC current deviation value, the system controller controls to reduce at a fastest speed the DCDC converting unit output current until that output current is the first current setting of DCDC Isetmin, what that first current setting of DCDC Isetmin is less than the minimum power consumption of the system auxiliary components, current is obtained from system; at this time, the system control jumps to the case of above working condition 1. When the DCDC current deviation value is less than the permissible DCDC current deviation value, at this time, the system control enters into the case of above working condition 2. 
     The purpose to set up working condition 3: When a vehicle operates practically, it may change back to operation at a high power after turning from operation at a high power to operation at low power, the system may suddenly output a high current again; at this time, if working condition 3 is not set up to reduce the DCDC converting unit output current controlled by the system controller, then when the system outputs a high current suddenly, as the DCDC converting unit output current controlled by the system controller is higher than the actual output current of the DCDC converting unit, power may be obtained first from the DCDC converting unit, resulting in an impact on the fuel cell. 
     In this way, by setting the output current of the DCDC converter, the distribution strategy at the time when the system adds load suddenly is ensured: the energy storage device outputs first, the fuel cell follows. 
     Working condition 4: When a vehicle brakes, the vehicle with an energy feedback function will turn the energy resulting from braking into electric energy and feed it back to the power supply system; for a fuel cell system, such a condition is external current input into it, that current is input into the energy storage device, at the same time, the current outputted by the DCDC converting unit is also input into the energy storage device, this may make the energy storage device voltage increase sharply to the protection voltage and trigger shutdown, as a result, the energy resulting from braking can not be recovered to lead to the vehicle being out of control; therefore, when braking, it is necessary to control and reduce the current outputted by the DCDC converting unit first. To avoid that the energy storage device voltage exceeds the protection voltage of the energy storage device, when the energy storage device voltage reaches the set value (the first voltage setting of energy storage device Umax), the system controller controls to reduce gradually the DCDC converting unit output current, until that output current is the current setting of DCDC 1 . When that value is less than the minimum power consumption of the system auxiliary components, current is obtained from the system. After braking is over, the system controls to jump to the case of working condition 1. 
     The reason that a compact structure as shown in  FIG. 1  can be designed for the said forklift fuel cell supply system is mainly due to adopting the compact type fuel cell supply system as shown in  FIG. 2 . 
       FIG. 2  is the schematic diagram of the structure of the compact type fuel cell supply system of the first embodiment example provided according to this invention, in this embodiment example, the said compact type fuel cell supply system consists of fuel cell  1 , DCDC converting unit  2 , contactor  3 , energy storage device  4 , power supply output end  5 , operation control unit  6 , controller  7 , auxiliary system  8 , in which the said contactor  3  is a normal open type high-current contactor, the said DCDC converting unit  2  includes DCDC converter  21  and high-power diode  22  connecting with it. 
     Specifically, the output end of the said fuel cell  1  connects the input end of the said DCDC converting unit  2 , DCDC converting unit  2  connects through the said contactor  3  the said energy storage device  4 , the output end of the said DCDC converting unit  2  also connects the said power supply output end  5  and the high-power auxiliary component  80  that the said auxiliary system  8  contains, the port of the said energy storage device  4  connects through the said contactor  3  the said power supply output end  5  and auxiliary system  8 , the said operation control unit  6  connects respectively the said energy storage device  4 , DCDC converting unit  2 , controller  7 , the said controller  7  connects respectively the said fuel cell  1 , DCDC converting unit  2 , the control end of contactor  3 , energy storage device  4  and auxiliary system  8 . 
     In this embodiment example, the positive pole of the output end of the said DCDC converting unit  2  connects through the said contactor  3  the positive pole of the said energy storage device  4 , the negative pole of the output end of the said DCDC converting unit  2  connects through the said contactor  3  the negative pole of the said energy storage device  4 , the positive pole of the said energy storage device  4  connects through the said contactor  3  the positive pole of the said power supply output end  5  and the positive pole of auxiliary system  8 , the negative pole of the said energy storage device  4  connects directly the negative pole of the said power supply output end  5  and the negative pole of auxiliary system  8 ; and in a variation of this embodiment example, the difference from the first embodiment example as shown in  FIG. 1  is that in this variation, the change of the said contactor  3  in connecting position is: the said contactor  3  is connected between the negative pole of the output end of the said DCDC converting unit  2  and the negative pole of the said energy storage device  4 , and the positive pole of the output end of the said DCDC converting unit  2  and the positive pole of the said energy storage device  4  are connected directly between them, correspondingly, the positive pole of the said energy storage device  4  connects directly the positive pole of the said power supply output end  5  and the positive pole of auxiliary system  8 , the negative pole of the said energy storage device  4  connects through the said contactor  3  the negative pole of the said power supply output end  5  and the negative pole of auxiliary system  8 . The technical people in this field understand that the two connection modes for contactor  3  as described in this natural paragraph can both realize “DCDC converting unit  2  connecting through the said contactor  3  the said energy storage device  4 ” and “the port of the said energy storage device  4  connecting through the said contactor  3  the said power supply output end  5  and auxiliary system  8 ”. 
     The said auxiliary system  8  consists of air supply system, cooling system, hydrogen system, hydrogen safety system, the said high-power auxiliary component  80  refers to a high-power component in the auxiliary system (for example, fan, pump, heat dissipation fan). The technical people in this field can refer to the existing technology to accomplish the said auxiliary system  8  and its high-power auxiliary component  80 . No unnecessary detail is to be given here. 
     The said operation control unit  6  is used to receive operation signals and supplies power for the said controller  7  and DCDC converting unit  2 , the said controller  7  is used to receive the operation instructions generated by the said operation control unit  6  according to the said operation signals and control according to the said operation instructions the said contactor  3 , DCDC converting unit  2 , auxiliary system  8 , the said controller  7  is also used to measure the state parameters of the said fuel cell  1 , measure the state parameters of the said energy storage device  4 , measure the state parameters of the said auxiliary system  8  and receive the state data of the said DCDC converting unit  2 . The said DCDC converter  21  consists of CAN communication module, input voltage measurement module, input current measurement module, output voltage measurement module, output current measurement module. Preferably, DCDC converter  21  can control according to the communication data of the CAN communication module the specific numerical values of the output current, voltage; also outputs through the CAN communication module such data as input voltage, input current, output voltage, output current, etc. The state data of the said DCDC converting unit  2  includes DCDC input current, DCDC input voltage. 
     The said controller  7  is a controller with an integrated design, which is equivalent to the scattered fuel cell controller, whole vehicle controller, battery energy management system in the invention patent application of China with patent application number “200610011555.1”; further specifically, the said controller  7  can consist of energy management unit, fuel cell control unit, energy storage device monitoring unit, hydrogen safety monitoring unit, system failure monitoring unit and startup control unit. 
     More specifically, as shown in  FIG. 2 , the output end of the said fuel cell  1  connects the input end of the said DCDC converter  21 , the positive pole of the output end of the said DCDC converter  21  connects the positive pole of the said high-power diode  22 , negative pole of the said high-power diode  22  connects through the said contactor  3  the said energy storage device  4 , the said DCDC converter  21  connects the said controller  7  and is controlled by the said controller  7 , the said DCDC converter  21  connects the said operation control unit  6  and receives the power supplied by the said operation control unit  6 . And in a variation of this embodiment example, the difference from the first embodiment example as shown in  FIG. 2  is that in this variation, the positive pole of the output end of the said fuel cell  1  connects the positive pole of the said high-power diode  22 , the negative pole of the said high-power diode  22  connects the positive pole of the input end of the said DCDC converter  21 , the negative pole of the output end of the said fuel cell  1  connects directly the negative pole of the input end of the said DCDC converter  21 , the output end of the said DCDC converter  21  directly connects through the said contactor  3  the said energy storage device  4 . 
     Further, in this embodiment example, the said compact type fuel cell supply system also consists of monitoring display  91 , ON and OFF button  92 , remote control  93 , emergency stop button  94 , in which the said monitoring display  91  connects the said controller  7 , the said ON and OFF button  92  connects respectively the said operation control unit  6  and controller  7 , the said remote control  93  connects in a radio mode the said operation control unit  6 , the said emergency stop button  94  connects the said operation control unit  6 . As shown in  FIG. 1 , when the said ON and OFF button  92  or remote control  93  gives a startup signal, the said operation control unit  6  supplies power to the said controller  7 , the said controller  7  outputs a control signal to the contactor used as a switch to make it close, the said energy storage device  4  supplies power through the said contactor  3  to the said high-power auxiliary component  80 , in the said auxiliary system  8 , except the said high-power auxiliary component  80 , other devices (for example, hydrogen system, hydrogen safety system) are supplied by the said controller  7 , at the same time, the said controller  7  outputs signals to all modules constituting the said auxiliary system  8  to start the said fuel cell  1 ; after starting, the said contactor  3  maintains the state of connection at all times. By adopting this starting mode, it is not necessary to use additionally configured auxiliary battery and auxiliary DC/DC converter for charging, as a result, parts and components and corresponding lines are reduced, system reliability is improved, space is saved, system volume and costs are reduced. 
     In a preferable case of this embodiment example, as shown in  FIG. 3 , the said high-power diode  22  is placed on the heat dissipation passage of the said DCDC converter  21 , this can use the air discharged from the air duct  2101  by the heat dissipation fan  2102  contained by the said DCDC converter itself to dissipate heat from the said high-power diode  22 , as a result, the heat dissipation fan on the heat dissipater  2201  (i.e. aluminum fin) for the said high-power diode is saved, the volume of heat dissipater is reduced, energy is saved, at the same time, the line to supply power to that heat dissipation fan is also saved. The said operation control unit  6  changes the electric connection state with the said DCDC converting unit and controller  7  according to the startup operation signal received. Thus, the said controller  7  is in an operation condition only when the system is working and will not lead to the problem of high system energy consumption due to being always in an operation condition. 
     Next, the system working principle is described through a preferable embodiment of this invention. Specifically, When the system is not started, the said operation control unit  6  and the said controller  7 , DCDC converting unit  2  establish no electric connection state between them. When the button of the said remote control  93  or the said ON and OFF button  92  is depressed, the said operation control unit  6  and the said controller  7 , DCDC converting unit  2  establish an electric connection between them, the said energy storage device  4  supplies power through the said operation control unit  6  to the said controller  7 , the output signal of the said controller  7  drives the said contactor  3  to get connected, the said energy storage device  4  supplies power through the said contactor  3  to the said high-power auxiliary component  80 , in the said auxiliary system  8 , except the said high-power auxiliary component  80 , other devices (for example, hydrogen system, hydrogen safety system) are supplied by the said controller  7 , at the same time, the said controller  7  outputs working signals to all modules constituting the said auxiliary system  8  to start the said fuel cell  1 ; the said fuel cell  1  outputs power to the said DCDC converting unit  2 , the said controller  7  controls according to the received state data signals of the said fuel cell  1 , energy storage device  4 , DCDC converting unit  2  the said DCDC converting unit  2  output current; under the normal system working condition, the output voltage of the said DCDC converting unit  2  is higher than the output voltage of the said energy storage device  4 , the output current of the said DCDC converting unit  2  is output through the said power supply output end  5  to the small vehicle drive system carrying the said fuel cell supply system to drive the small vehicle to work, at the same time, the said DCDC converting unit  2  charges the said energy storage device  4 , supplies power to the said high-power auxiliary component  80 , operation control unit  6 ; when a small vehicle is in a high-power driving condition, the said power supply output end  5  needs to output high power, high currency, at this time, the said DCDC converting unit  2  output current is not sufficient to satisfy the requirements, the said energy storage device  4  will output current together with the said DCDC converting unit  2  to the small vehicle driving system carrying that fuel cell supply system through the said power supply output end  5  to drive that small vehicle to maintain the high-power driving condition; when the small vehicle is in a braking condition, the power energy recovered by the brake charges through the power supply output end the energy storage device. 
     When it is necessary to start the system, just depress the button of the said remote control  93  or the said ON and OFF button  92 , in the meantime that the said operation control unit  6  and the said controller  7 , DCDC converting unit  2  establish an electric connection, the said operation control unit  6  outputs a switch signal to the said controller  7 , the said controller  7 , after receiving the switch signal, outputs a signal to maintain power supply to the said operation control unit  6 , so that the said operation control unit  6  and the said controller  7 , DCDC converting unit  2  maintain an electric connection state; at the same time, the said controller  7  also drives the indicator light of the said ON and OFF button  92  to become on to prompt system starting; at this time, the button of the said remote control  93  or the said ON and OFF button  92  can be released. 
     When it is necessary to close the system, depress again the button of the said remote control  93  or the said ON and OFF button  92 , the said operation control unit  6  outputs a switch signal to the said controller  7 , the said controller  7 , after receiving the switch signal, controls the indicator light of the said ON and OFF button  92  to blink (prompting switching off, at this time, the button of the said remote control  93  or the said ON and OFF button  92  can be released), the said controller  7  simultaneously controls the said auxiliary system  8  to stop working, and then stops outputting the signal to maintain power supply to the said operation control unit  6 , so that the electric connection of the said operation control unit  7  and the said controller  7 , DCDC converting unit  2  is disconnected; the whole system stops working. 
     When the said emergency stop button  94  is depressed, the electric connection between the said operation control unit  6  and the said controller  7 , DCDC converting unit  2  get disconnected quickly to cut off the power supply to the whole system and make the system stop working. 
     The said monitoring display  91  gets power, communication data from the said controller  7 , displays the system condition, failure information, etc. on the screen. 
     The embodiment examples of this invention are described above. What needs understanding is that that this invention is not limited to above specific embodiments. The technical people in this field can make various variations or modifications with the Claim, and this does not influence the essential contents of this invention.