CN101219664A - Fuel cell hybrid power energy control method - Google Patents

Abstract

The invention relates to a method for controlling a fuel cell hybrid power energy, belonging to a controlling technical field of multi-energy power assembly. An SOC value, a rotate speed Omega<m> of a motor, and a voltage of a bus U<bus> are obtained from a CAN network; a throttle opening Psi is obtained from a throttle pedal of the driver; a target torque T<m> and a target power of the entire vehicle P<com> are calculated according to the rotate speed of the motor and the throttle pedal; a target current I<bat><*> of a storage cell is calculated; a target current I<com><*> of the entire vehicle is calculated; a steady target current I<*>dc of DCDC is calculated; the target torque of the motor and the target current of DCDC are sent to a motor controller and a DCDC controller through the CAN network, and the corresponding torque and current are outputted. Aims at Alpha and Tau, the invention also discloses a parameter optimization method of the method for controlling hybrid energy of the fuel cell, From the aspect of entire vehicle controlling, the invention discloses a controlling hybrid energy method which can both improve the system durability and considerate economical efficiency. Through optimization of parameter matching, the variable load of the fuel cell is prevented from being too intense, and no frequent starting and stopping is required during running process of the vehicle.

Description

A kind of fuel cell hybrid power energy control method

Technical field

A kind of fuel cell hybrid power energy control method, be particularly related to a kind of fuel cell hybrid power energy control method of taking into account economy and improving fuel cell durability, be applicable to the fuel cell hybrid vehicle system integration, coupling and optimization, also be applicable to the ordinary hybrid vehicle system integration and coupling; Belong to multipotency driving source assembly control technology field.

Background technology

Fuel cell hybrid vehicle is one of important directions of following development of automobile, also is the important component part of national development battery-driven car " three vertical three horizontal strokes " strategy.The fuel-cell vehicle cost is too high at present, the life-span is too short, from large-scale promotion distance is arranged still.How improving fuel cell durability, is to develop the matter of utmost importance that fuel-cell vehicle need solve at present.

Fuel cell can pass through motor independent drive vehicle, also can pass through a Ni-MH battery in parallel or the super capacitor form powered vehicle with hybrid power.Pure fuel-cell vehicle system economy is good, but power pulses is bigger, and attenuation ratio is very fast.Fuel cell hybrid reclaims by energy control method and braking energy, can obtain to be better than the economy of pure fuel-cell vehicle, and can improve fuel cell output power by algorithmic match, and then improve system durability.

Because domestic fuel cell cause is started late, each parts quality also has much room for improvement, and present domestic fuel-cell vehicle mainly is the motor vehicle driven by mixed power that adopts fuel cell and Ni-MH battery; External relevant enterprise is its technical merit of demonstration, and strengthens the research to fuel cell durability, and pure fuel-cell vehicle is arranged, and fuel cell hybrid vehicle is also arranged.

In " 15 " national 863 developments in Hi-Tech in the works, be that core has been developed fuel cell hybrid motorcoach and small passenger car separately by Tsing-Hua University and Tongji University.By Tsing-Hua University is the fuel cell hybrid motorcoach of main exploitation, and it drives power and is provided by fuel cell, Ni-MH battery.Entire car controller is according to energy control method, and control motor horsepower output and fuel cell output power reach the requirement of optimization system economy and raising fuel cell durability.

The measure that improves fuel cell durability by external control mainly contains following several:

High potential: help prolonging its life-span if the fuel cell monolithic voltage always works in upper zone.

Circulation variable load: reduce variable load speed as far as possible.

Frequent start-stop: fuel cell is not shut down during the car idling, carries out start-stop protection control, avoids producing infringement.

Summary of the invention

The purpose of this invention is to provide a kind of fuel cell hybrid power energy control method of taking into account economy and improving fuel cell durability.

A kind of fuel cell hybrid power energy control method is characterized in that, this method may further comprise the steps:

Step 1: obtain SOC value, motor speed ω from the CAN network _m, bus voltage U _Bus, obtain accelerator open degree ψ from driver's Das Gaspedal;

Step 2: calculate target torque T according to motor speed and Das Gaspedal _mAnd car load target power P _Com,

$P_{\mathrm{com}}={\mathrm{\&omega;}}_m{T}_m^{*}({\mathrm{\&omega;}}_m,\mathrm{\&psi;})/{\mathrm{\&eta;}}_m---\left(1\right)$

According to the SOC value, calculating accumulator target current I _Bat ^*,

$I_{\mathrm{bat}}^{*}=a(\mathrm{SOC}-{\mathrm{SOC}}_0)---\left(2\right)$

Consider current battery-operated range of current,

$\min \left(I_{\mathrm{bat}}^{*}\right)=I_{\mathrm{bat},\min }---\left(3\right)$

$\max \left(I_{\mathrm{bat}}^{*}\right)=I_{\mathrm{bat},\max }---\left(4\right)$

According to target power and bus voltage U _BusCalculate car load target current I _Com ^*,

$I_{\mathrm{com}}^{*}=P_{\mathrm{com}}/U_{\mathrm{bus}}---\left(5\right)$

Step 3: according to car load target current I _Com ^*With storage battery target current I _Bat ^*Calculate DCDC steady-state target electric current

${\tilde{I}}_{\mathrm{dc}}^{*}=I_{\mathrm{com}}^{*}-I_{\mathrm{bat}}^{*}---\left(6\right)$

Consider dynamic compensation, calculate DCDC target current I _Dc ^*

$\mathrm{\&tau;}\frac{d{I}_{\mathrm{dc}}^{*}}{\mathrm{dt}}+I_{\mathrm{dc}}^{*}={\tilde{I}}_{\mathrm{dc}}^{*}---\left(7\right);$

Step 4: motor target torque and DCDC target current are sent to electric machine controller and DCDC controller by the CAN network, make it to export corresponding torque and electric current.

Wherein, I _Bat ^*Be the storage battery target current under the stable state allocation strategy, I _Com ^*Be car load demand current, P _ComBe car load target power, U _BusBe system bus voltages,

Be DCDC steady-state target electric current, I _Dc ^*Be the DCDC target current, τ is the dynamic compensation time constant.Wherein the stable state allocation strategy is suc as formula (1-6), and the dynamic compensation function is suc as formula (7).

A kind of fuel cell hybrid power energy control method parameter optimization method, at a and τ, this method may further comprise the steps:

Step 1: determine best stable state bus voltage according to motor characteristic.Determine motor best effort bus voltage U according to electrical efficiency characteristic and output torque characteristic _{Bus, best}

Step 2: determine the best steady-state value SOC of SOC according to bus voltage and Ni-MH battery characteristic ₀SOC ₀Definite needs take all factors into consideration electrical efficiency characteristic, output torque characteristic and Ni-MH battery open circuit voltage characteristic.

Step 3: according to principle of least square identification hybrid power system model.

Step 4: with the research object that is distributed as of fuel cell monolithic voltage and voltage change ratio, hybrid power system model based on step 3 identification, change the value of energy control method parameter a and τ, study the distribution of voltage u under the typical public transport operating mode and voltage change ratio du/dt, therefrom choose optimum value a and τ.

Reduce a and increase τ, to improve fuel cell durability;

Increase a and reduce τ, to improve system economy.

The final optimization pass target can be:

The maxim that guarantees monolithic voltage change ratio absolute value is in 5mV/s, and the monolithic operating voltage range is 0.6～0.85V;

Do not optimize algorithm relatively, system economy is unlikely to descend too big.

The present invention at first chooses best stable state bus voltage according to the machine operation characteristic, and determines Ni-MH battery SOC (StateOf Charge) equilibrium point in view of the above, guarantees system economy with this; Secondly reduce fuel cell monolithic voltage rate of change by the correlation parameter of optimizing in the energy management method, to improve fuel cell durability.

The selection of Ni-MH battery SOC equilibrium point has guaranteed that motor is in service and has possessed enough dynamic property and economy; Provide correlation parameter optimization to take all factors into consideration the contradiction of durability and economy, taked corresponding halfway measures.

The present invention is from the angle of car load control, proposed a kind of practicality, can improve system durability to a certain extent, and take into account the method for system economy.By parameter matching optimization, can guarantee that in most of the cases the fuel cell monolithic voltage works in high potential, it is too fierce that the fuel cell variable load is unlikely to, and do not need frequent start-stop in the vehicle operating process.

Description of drawings

Fig. 1 fuel cell hybrid structural representation.

Fig. 2 is a kind of fuel cell hybrid power energy control method parameter optimization method diagram of circuit.

The distribution schematic diagram of Figure 33 80V bus voltage electrical efficiency figure and operating mode commonly used.

Fig. 4 Chinese city public transport standard condition scheme drawing.

Fig. 5 fuel cell monolithic voltage distribution probability is with the variation of a.Wherein, abscissa: fuel cell monolithic voltage/V; Ordinate: the voltage distribution probability/(1/V).

Fig. 6 fuel cell monolithic voltage rate of change distribution probability is with the variation of a.Wherein, abscissa: the fuel cell monolithic voltage/(V/s); Ordinate: the voltage distribution probability/(s/V).

Fig. 7 fuel cell monolithic voltage rate of change distribution probability is with the variation of τ.Wherein, abscissa: fuel cell monolithic voltage/V; Ordinate: the voltage distribution probability/(1/V).

Fig. 8 fuel cell monolithic voltage rate of change distribution probability is with the variation of τ.Wherein, abscissa: the fuel cell monolithic voltage/(mV/s); Ordinate: the voltage distribution probability/(s/mV).

Different acceleration pedal aperture (the representing acceleration pedal aperture 60%) diagram of curves of Fig. 9 as 60%, wherein, coordinate: motor speed/(rpm); Ordinate: the motor target torque/(N.m).

A kind of fuel cell hybrid power energy control method diagram of circuit of Figure 10.

The specific embodiment

Further specify the present invention below in conjunction with accompanying drawing.

Fig. 1 is the fuel cell hybrid structural representation.As shown in the figure, two propulsions source, fuel battery engines and storage batterys are arranged in the system.Fuel battery engines is connected with storage battery by DC-DC converter, then drives asynchronous dynamo by DC-AC inverter.

Fig. 2 is a kind of fuel cell hybrid power energy control method parameter optimization method diagram of circuit.At first determine best stable state bus voltage, and determine the best steady-state value SOC of SOC according to bus voltage and Ni-MH battery characteristic according to motor characteristic ₀Under this bus voltage, operating mode major part commonly used is distributed in＞85% zone.Therefore selecting 380V for use is bus voltage.Figure 3 shows that certain model electrical efficiency figure under the 380V bus voltage.As certificate, corresponding Ni-MH battery characteristic curve, selecting best stable state SOC value is 0.8.Once more according to principle of least square identification hybrid power system model.The research object that is distributed as with fuel cell monolithic voltage and voltage change ratio, based on the hybrid power system model, change the value of energy control method parameter a and τ, study the distribution of voltage u under the typical public transport operating mode and voltage change ratio du/dt, therefrom choose optimum value a and τ, Fig. 4 Chinese city public transport standard condition scheme drawing.

Fig. 5～Fig. 8 is according to least-squares algorithm identification system model, the distribution of voltage u and voltage change ratio du/dt under typical case's public transport operating mode when changing different a and τ parameter on this basis.Parameter a represents the slope of stable state partition function (1).The a value is big more, and after storage battery SOC departed from steady state point, accumulator cell charging and discharging was big more, the fast more recovery of storage battery SOC equilibrium value.Therefore, a is big more, and bus voltage is stable more.At this moment, the accumulator cell charging and discharging electric current is in state of equilibrium substantially, and the dynamic horsepower output of motor is provided by fuel cell, and fuel cell output power changes greatly, and voltage distributes also relatively evenly.As Fig. 5, shown in 6, increase with a, the fuel cell monolithic voltage distributes even more, and the distribution curve peak of voltage change ratio moves to right, and the average voltage rate of change increases.Parameter τ is the dynamic compensation time parameter.Its value is big more, and the dynamic delay time is long more, and fuel cell output power changes mild more.Therefore, with the increase of τ, fuel cell monolithic voltage probability distribution is concentrated more, and monolithic voltage rate of change probability distribution curve moves to left, and the average rate of change reduces.The fuel cell output power rangeability reduces, and will cause storage battery horsepower output rangeability to increase.The accumulator cell charging and discharging number of times is many more, and system economy is poor more.(as Fig. 2, Fig. 2 fuel cell hybrid power energy control method parameter optimization method diagram of circuit.) therefore, need take all factors into consideration the contradiction of economy and durability when optimizing parameter, according to the actual conditions compromise.For this system, the parameter value after the optimization is as follows:

a＝200，SOC＜0.8

a＝1200，SOC≥0.8

τ＝5sec

I _bat，min＝-160A

I _bat，max＝240A。

Figure 10 is a kind of fuel cell hybrid power energy control method diagram of circuit.At first obtain SOC value, motor speed ω from the CAN network _m, bus voltage U _Bus, obtain accelerator open degree ψ from driver's Das Gaspedal; Then calculate target torque T according to motor speed and Das Gaspedal _mWith car load target power P _Com, as formula (8), Fig. 9 is with acceleration pedal aperture (representing acceleration pedal aperture 60% as 60%) diagram of curves, wherein, coordinate: motor speed/(rpm); Ordinate: the motor target torque/(N.m), motor target torque T _m ^*(ω _m, ψ) can determine according to Fig. 9; According to the SOC value, use formula (9) calculating accumulator target current I once more _Bat ^*, and consider current battery-operated range of current, as formula (10,11); Then according to target power and bus voltage U _BusCalculate car load target current I _Com ^*, as formula (12); Afterwards according to car load target current I _Com ^*With storage battery target current I _Bat ^*Calculate DCDC steady-state target electric current

Suc as formula (13); According to formula (14), consider dynamic compensation, calculate DCDC target current I _Dc ^*At last motor target torque and DCDC target current are sent to electric machine controller and DCDC controller by the CAN network, make it to export corresponding torque and electric current.

$P_{\mathrm{com}}={\mathrm{\&omega;}}_m{T}_m^{*}({\mathrm{\&omega;}}_m,\mathrm{\&psi;})/{\mathrm{\&eta;}}_m---\left(8\right)$

$I_{\mathrm{bat}}^{*}=\left\{\begin{array}{c}200(\mathrm{SOC}-0.8),\mathrm{SOC}<0.8\\ 1200(\mathrm{SOC}-0.8),\mathrm{SOC}\&GreaterEqual;0.8\end{array}\right.---\left(9\right)$

$\min \left(I_{\mathrm{bat}}^{*}\right)=-160A---\left(10\right)$

$\max \left(I_{\mathrm{bat}}^{*}\right)=240A---\left(11\right)$

$I_{\mathrm{com}}^{*}=P_{\mathrm{com}}/U_{\mathrm{bus}}---\left(12\right)$

${\tilde{I}}_{\mathrm{dc}}^{*}=I_{\mathrm{com}}^{*}-I_{\mathrm{bat}}^{*}---\left(13\right)$

$5\sec \&CenterDot;\frac{d{I}_{\mathrm{dc}}^{*}}{\mathrm{dt}}+I_{\mathrm{dc}}^{*}={\tilde{I}}_{\mathrm{dc}}^{*}---\left(14\right)$

Claims (2)

1. a fuel cell hybrid power energy control method is characterized in that, this method may further comprise the steps:

Step 1: obtain SOC value, motor speed ω from the CAN network _m, bus voltage U _Bus, obtain accelerator open degree ψ from driver's Das Gaspedal;

Step 2: calculate target torque T according to motor speed and Das Gaspedal _mAnd car load target power P _Com,

$P_{\mathrm{com}}={\mathrm{\&omega;}}_m{T}_m^{*}({\mathrm{\&omega;}}_m,\mathrm{\&psi;})/{\mathrm{\&eta;}}_m---\left(1\right)$

According to the SOC value, calculating accumulator target current I _Bat ^*,

$I_{\mathrm{bat}}^{*}=a(\mathrm{SOC}-{\mathrm{SOC}}_0)---\left(2\right)$

Consider current battery-operated range of current,

$\min \left(I_{\mathrm{bat}}^{*}\right)=I_{\mathrm{bat},\min }---\left(3\right)$

$\max \left(I_{\mathrm{bat}}^{*}\right)=I_{\mathrm{bat},\max }---\left(4\right)$

According to target power and bus voltage U _BusCalculate car load target current I _Com ^*,

$I_{\mathrm{com}}^{*}=P_{\mathrm{com}}/U_{\mathrm{bus}}---\left(5\right)$

Step 3: according to car load target current I _Com ^*With storage battery target current I _Bat ^*Calculate DCDC steady-state target electric current

${\tilde{I}}_{\mathrm{dc}}^{*}=I_{\mathrm{com}}^{*}-I_{\mathrm{bat}}^{*}---\left(6\right)$

Consider dynamic compensation, calculate DCDC target current I _Dc ^*

$\mathrm{\&tau;}\frac{d{I}_{\mathrm{dc}}^{*}}{\mathrm{dt}}+I_{\mathrm{dc}}^{*}={\tilde{I}}_{\mathrm{dc}}^{*}---\left(7\right)$

Wherein, τ is the dynamic compensation time constant;

Step 4: motor target torque and DCDC target current are sent to electric machine controller and DCDC controller by the CAN network, make it to export corresponding torque and electric current.

2. a fuel cell hybrid power energy control method parameter optimization method at a and τ, is characterized in that, this method may further comprise the steps:

Step 1: determine best stable state bus voltage according to motor characteristic; Determine motor best effort bus voltage U according to electrical efficiency characteristic and output torque characteristic _{Bus, best}

Step 2: determine the best steady-state value SOC of SOC according to bus voltage and Ni-MH battery characteristic ₀SOC ₀Definite needs take all factors into consideration electrical efficiency characteristic, output torque characteristic and Ni-MH battery open circuit voltage characteristic;

Step 3: according to principle of least square identification hybrid power system model;

Step 4: with the research object that is distributed as of fuel cell monolithic voltage and voltage change ratio, hybrid power system model based on above-mentioned steps 3 identifications, change the value of energy control method parameter a and τ, study the distribution of voltage u under the typical public transport operating mode and voltage change ratio du/dt, therefrom choose optimum value a and τ;

Reduce a and increase τ, to improve fuel cell durability;

Increase a and reduce τ, to improve system economy.

Images