Self-adaptive voltage stabilization method and system for electronic load special for fuel cell

Abstract

The invention provides a self-adaptive voltage stabilization method of a special electronic load for a fuel cell, and belongs to the field of fuel cells. The method comprises the following steps: S1, setting a required voltage instruction Uref; s2, the voltage loop works, the output voltage U0 detected in real time is compared with the output voltage Uref, the difference value delta U is worked out, a control current signal is output after PID adjustment, and an input instruction value I * of the current loop is obtained; s3, the current loop works, the output current I0 detected in real time is compared with I *, the difference value delta I is calculated, a current control signal is output after PID adjustment, and the input instruction value # imgabs0 of the inductive current loop is obtained; S4, the inductive current loop works, the detected inductive current IL is compared with # imgabs1 #, the difference value delta IL is calculated, a PWM duty ratio signal is output after PID adjustment, and the PWM duty ratio signal is output after PID adjustment. And the conduction time of the load equipment power tube is controlled. The voltage of the fuel cell reactor is stabilized in real time by using the load equipment control loop, a current instruction does not need to be input manually, the voltage stabilization efficiency is improved, the personnel safety is guaranteed, and the method has the advantages of being environmentally friendly, high in timeliness and high in applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to an adaptive voltage stabilization method and system for an electronic load dedicated to a fuel cell. Background Art

[0002] In the field of hydrogen fuel cells, electronic load equipment is one of the indispensable test equipment. According to the fuel cell activation process, different current instructions are dynamically output to promote the activation of the fuel cell stack. In the process of fuel cell stack R&D and testing, various boundary experiments to expand the reaction conditions need to be done. For example, the voltage of a normal reactor will decrease as the hydrogen concentration decreases. When it decreases to a certain level, the reactor will be shut down for protection due to a fault. Since the reactor will be purged with nitrogen and cooled after each protection shutdown, the reactor needs to be preheated again to start the reactor again. Frequent protection shutdowns and restarts lead to low R&D efficiency; and when hydrogen increases, the voltage of the reactor will increase accordingly. When the single cell voltage is high to a certain level, it will cause carbon corrosion of the reactor, causing irreversible damage to the reactor. At the same time, changes in the reactor peripheral conditions, such as excessive or low temperatures caused by the management of the cooling system, may lead to changes in the electrochemical reaction rate, thereby affecting the stability of the voltage. Therefore, the fuel cell stack R&D test needs to stabilize the voltage of the reactor through changes in the current of the load.

[0003] Some prior arts use resistors as reactor loads. When different formulas are changed, different resistors are connected in series and in parallel to achieve different load currents. This operation is complicated and costly on the one hand, and is not environmentally friendly on the other hand. The energy of the load is consumed in vain, resulting in a waste of resources. Some also use feedback electronic loads. Although they are environmentally friendly, they require people to manually operate the human-machine interface next to the equipment to modify the current command. This is not only inefficient but also unsafe. Alternatively, the current command is modified by communicating between the system integration host computer and the load device. Although it can be kept away from the equipment to ensure safety compared to manual operation, due to the limitation of the shortest communication time, timeliness is difficult to guarantee, and timely control of the current when the voltage changes cannot be guaranteed.

[0004] Therefore, there are some other fuel cell voltage stabilization methods in the prior art, such as CN101593994A, which discloses a fuel cell voltage stabilization method and fuel cell system without a DC-DC converter, in which the output voltage of the stack is set within the voltage range required by the load, and the output power is set at the power value required by the workload for most of the time. The fuel cell stack is connected in parallel with at least two accumulators with charging and discharging functions; when the output power of the fuel cell stack is lower than the workload power, one of the accumulators containing saturated electricity discharges to the workload together with the stack to compensate for the insufficient output power of the stack; when the output power of the fuel cell stack is higher than the workload power, the stack supplies power to the workload while charging another non-saturated accumulator, so that the total power output of the entire fuel cell system matches the workload power, thereby ensuring the stability of the output voltage. Although this voltage stabilization method does not require different resistors in series and parallel, does not require manual modification of current instructions, and has a certain timeliness, it still has the following disadvantages: in order to adapt to various types of fuel cells, it is necessary to replace accumulators with charging and discharging functions of different capacities, especially when the accumulator cannot fully accept the additional power generated by the battery stack that exceeds the required amount, it is necessary to increase the accumulator or increase the variable load between the positive and negative poles of the battery, which will increase the cost accordingly and may cause waste of electric energy resources. Therefore, this voltage stabilization method cannot be simply and directly applied to different fuel cells and is not very applicable. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to solve the problem in the prior art that environmental protection, timeliness, safety, efficiency and applicability are difficult to ensure when performing fuel cell voltage stabilization.

[0006] The present invention solves the above-mentioned problem by the following technical means: an adaptive voltage stabilization method for a fuel cell dedicated electronic load, comprising the following steps:

[0007] S1: The load device is equipped with a human-machine interface that sets the required stable voltage command U in advance. ref ;

[0008] S2: The voltage loop works, and the load device detects the output voltage U0 in real time and compares U0 with U ref Compare and take the difference ΔU=U0-U ref After PID adjustment of ΔU, the output control current signal I1 is obtained. According to the output control current signal I1, the input command value I of the current loop is obtained. * ;

[0009] S3: The current loop works, and the load device detects the output current I0 in real time, which is consistent with the input command value I output by the voltage loop. * Compare and take the difference ΔI=I *-I0, after PID adjustment of ΔI, the output current control signal I2 is output. According to the output control current signal I2, the input command value I of the inductor current loop is obtained. L * ;

[0010] S4: The inductor current loop works, and the load device detects the inductor current I in real time. L , and the input command value I of the current loop output L * Compare and Difference ΔI L After PID adjustment, a PWM duty cycle signal Duty is output to control the on-time of the power tube of the load device.

[0011] The present invention detects the voltage of the fuel cell reactor in real time through an electronic load device, ensuring that the current can be controlled in time when the voltage changes, so as to achieve the timeliness of voltage stabilization of the load device control loop.

[0012] Preferably, the output end of the fuel cell is connected in parallel with the output end of the load device to obtain the output voltage U0 described in step S2.

[0013] Preferably, in step S2, the process of obtaining the control current signal I1 is: when ΔU>0, the output control current signal I1 is a current increase signal; when ΔU<0, the output control current signal I1 is a current decrease signal.

[0014] Preferably, when the output control current signal I1 is a current increase signal, the current loop input command value I * When the output control current signal I1 is a current reduction signal, the current loop input command value I * Reduce.

[0015] The present invention utilizes a voltage loop to obtain a current control signal by comparing the real-time voltage with a preset required voltage, and further obtains a current input command value of the current loop, without the need for manual input of the command value, thereby improving the efficiency of voltage stabilization and ensuring the safety of personnel.

[0016] Preferably, in step S3, the process of obtaining the control current signal I2 is: when ΔI>0, the output control current signal I2 is a current increase signal; when ΔI<0, the output control current signal I2 is a current decrease signal.

[0017] Preferably, when the output control current signal I2 is a current increase signal, the inductor current loop input command value I L * When the output control current signal I2 is a current reduction signal, the inductor current loop input command value IL * Reduce.

[0018] Preferably, in step S4, when ΔI L >0, the PWM duty cycle signal Duty becomes smaller; when ΔI L <0, the PWM duty cycle signal Duty becomes larger.

[0019] Preferably, when the PWM duty cycle signal Duty becomes smaller, the on-time of the power tube of the load device becomes shorter; when the PWM duty cycle signal Duty becomes larger, the on-time of the power tube of the load device becomes longer.

[0020] Preferably, when the conduction time of the power tube of the load device becomes shorter, the current of the load device becomes larger; when the conduction time of the power tube of the load device becomes longer, the current of the load device becomes smaller.

[0021] Corresponding to the above method, the present invention also provides an adaptive voltage stabilization system for a fuel cell dedicated electronic load, comprising the following modules:

[0022] Setting the required voltage module: used to set the required stable voltage command U in advance on the human-machine interface equipped with the load device ref ;

[0023] Voltage loop module: used to detect the output voltage U0 of the load device in real time and then compare U0 with U ref Compare and take the difference ΔU=U0-U ref , after PID adjustment of ΔU, the output control current signal I1 is output; and according to the output control current signal I1, the input command value I of the current loop is obtained * ;

[0024] Current loop module: used to detect the output current I0 of the load device in real time and compare it with the input command value I of the voltage loop output * Compare and take the difference ΔI=I * -I0, after PID adjustment of ΔI, output current control signal I2; and according to the output control current signal I2, obtain the input command value I of the inductor current loop L * ;

[0025] Inductor current loop module: used to detect the inductor current I in real time in the load device L After that, the input command value I of the current loop output L * Compare and take the difference ΔI L After PID adjustment, a PWM duty cycle signal Duty is output to control the on-time of the power tube of the load device.

[0026] The advantages of the present invention are: utilizing the load device control loop to stabilize the voltage of the fuel cell reactor in real time, without having to change the load current through continuous series and parallel resistance, low additional power consumption, and the ability to save fuel; utilizing the voltage loop to automatically adjust the load current command, without the need for manual input of current commands, thereby improving voltage stabilization efficiency and ensuring the safety of staff; requiring no integrated host computer operation, reducing software development costs; the load device control loop of the present invention has a wide range of applicability, can be simply applied to different fuel cells, and has good product performance and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the connection between the fuel cell and the electronic load device in Example 1 of the present invention;

[0029] Figure 3 4 is a block diagram of a control loop of an electronic load device in Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] like Figure 1 The flowchart of this embodiment is shown in FIG. 1 . The present invention provides an adaptive voltage stabilization method for a fuel cell dedicated electronic load, and the specific steps are as follows:

[0033] Step 1: The human-machine interface equipped with the load device sets the voltage command U that needs to be stable in advance ref , this voltage instruction can be adjusted to meet different needs for different fuel cells;

[0034] like Figure 3 As shown, it is a block diagram of the control loop of the electronic load device in this embodiment. The working principle of the control loop is described below in combination with steps 2-4:

[0035] Step 2: The voltage loop works. The specific process is as follows:

[0036] S201: Figure 2As shown, the output end of the fuel cell is connected in parallel with the output end of the load device to obtain the output voltage U0 detected in real time by the electronic load device, which is consistent with the voltage command U that needs to be stabilized set in advance in step 1. ref Make a comparison and find the difference ΔU = U0-U ref ;

[0037] S202: Perform PID adjustment on ΔU and output a current control signal, specifically: when ΔU>0, the output control current signal I1 is a current increase signal; when ΔU<0, the output control current signal I1 is a current decrease signal;

[0038] S203: Obtaining the input command value of the current loop according to the current control signal I1, specifically: if the output control current signal I1 is a current increase signal, the current loop input command value I * Increase; if the output control current signal I1 is a current reduction signal, the current loop input command value I * Reduce.

[0039] Step 3: The current loop works. The specific process is as follows:

[0040] S301: The electronic load device detects the output current I0 in real time and compares it with the current loop input command value I0 in step S203. * Make a comparison and find the difference ΔI=I * -I0;

[0041] S302: Perform PID adjustment on ΔI and output a current control signal, specifically: when ΔI>0, the output control current signal I2 is a current increase signal; when ΔI<0, the output control current signal I2 is a current decrease signal;

[0042] S303: Obtaining an input command value of the inductor current loop according to the current control signal I2, specifically: if the output control current signal I2 is a current increase signal, the inductor current loop input command value I L * If the output control current signal I2 is a current reduction signal, the inductor current loop input command value I L * Reduce.

[0043] Step 4: The inductor current loop works. The specific process is as follows:

[0044] S401: The electronic load device detects the inductor current I in real time L , and the inductor current loop input command value I in step S303 L * Compare and find the difference

[0045] S402: ΔI L Perform PID adjustment and output PWM duty cycle signal Duty, specifically: if ΔI L >0, the PWM duty cycle signal Duty becomes smaller, at this time the main power tube conduction time of the load device becomes shorter, and the current transmitted to the load becomes larger; if ΔI L <0, the PWM duty cycle signal Duty becomes larger, at this time the main power tube of the load device is turned on for a longer time, and the current transmitted to the load becomes smaller.

[0046] To better explain the above method, this embodiment further describes the change of the output voltage U0 detected by the load device:

[0047] (1) When the output voltage U0 increases upward and exceeds the preset required voltage U ref When U0 and U ref The difference between ref >0, then voltage reduction is required, and the output current increase signal I1 is output after PID adjustment of ΔU, and an increased input command value I is obtained. * Input current loop;

[0048] At this time, the current target value in the current loop increases. Compared with the real-time detected output current I0, the output current is usually less than the current target value in the current loop, that is, ΔI=I * -I0>0, so the current needs to be increased, the output control current signal I2 is the load current increase signal, and an increased input command value I is obtained. L * Input inductor current loop;

[0049] At this time, the current target value in the inductor current loop increases, which is consistent with the real-time detected inductor current I L By comparison, the inductor current is usually less than the target current value in the inductor current loop, that is, At this time, the PWM duty cycle signal Duty becomes smaller, the conduction time of the main power tube of the load device becomes shorter, and the current transmitted to the load becomes larger. The current at this time has a current target value that meets the voltage reduction requirement; that is, after adjustment, the current output by the load device follows and becomes larger, so the voltage of the peripheral electronic load device increases synchronously, causing the reactor voltage to decrease and return to the preset expected value U ref , which meets the need to reduce the voltage when the output voltage U0 increases upward.

[0050] (2) When the output voltage U0 decreases downward and is lower than the preset required voltage U ref When U0 and U ref The difference between ref<0, then a voltage boost is required, and the output current reduction signal I1 is output after PID adjustment of ΔU, and a reduced input command value I is obtained. * Input current loop;

[0051] At this time, the current target value in the current loop decreases. Compared with the real-time detected output current I0, the output current is usually greater than the current target value in the current loop, that is, ΔI=I * -I0<0, so the current needs to be reduced, the output control current signal I2 is the load current reduction signal, and a reduced input command value I is obtained. L * Input inductor current loop;

[0052] At this time, the current target value in the inductor current loop decreases, which is consistent with the real-time detected inductor current I L By comparison, the inductor current is usually greater than the target current value in the inductor current loop, that is, At this time, the PWM duty cycle signal Duty becomes larger, the conduction time of the main power tube of the load device becomes longer, and the current transmitted to the load becomes smaller. The current at this time has a current target value that meets the boost demand, that is, the current output by the load device becomes smaller after adjustment, so the voltage of the peripheral electronic load device becomes smaller synchronously, that is, the voltage consumed by the load device becomes less, so that the reactor voltage rises back to the preset expected value U ref , which meets the need to boost the output voltage U0 when it decreases downward.

[0053] This embodiment automatically adapts to the changes in the peripheral voltage by adjusting the current through the electronic load device to achieve voltage stability of the fuel cell reactor, with high timeliness, clear logic and simple algorithm. There is no need for manual input of current instructions, which improves the voltage stabilization efficiency and ensures personnel safety. It does not require the operation of an integrated host computer, reduces development costs, and has good product performance and high reliability.

[0054] Example 2

[0055] Corresponding to Embodiment 1, this embodiment provides an adaptive voltage stabilization system for a fuel cell dedicated electronic load, comprising the following modules:

[0056] Setting the required voltage module: used to set the required stable voltage command U in advance on the human-machine interface equipped with the load device ref ;

[0057] Voltage loop module: used to detect the output voltage U0 of the load device in real time and then compare U0 with U ref Compare and find the difference ΔU = U0-U ref , after PID adjustment of ΔU, the output control current signal I1 is output; and according to the output control current signal I1, the input command value I of the current loop is obtained* , specifically including the following units:

[0058] The voltage difference solving unit is used to compare U0 with the voltage command U0 that needs to be stabilized in advance in the setting required voltage module after the electronic load device detects the output voltage U0 in real time. ref Make a comparison and find the difference ΔU = U0-U ref ;

[0059] Output current control signal first unit: used to perform PID adjustment on ΔU and output current control signal, specifically: when ΔU>0, the output control current signal I1 is a current increase signal; when ΔU<0, the output control current signal I1 is a current decrease signal;

[0060] The current loop command value acquisition unit is used to obtain the input command value of the current loop according to the current control signal, specifically: if the output control current signal I1 is a current increase signal, the current loop input command value I * Increase; if the output control current signal I1 is a current reduction signal, the current loop input command value I * Reduce.

[0061] Current loop module: used to detect the output current I0 of the load device in real time and compare it with the input command value I of the voltage loop output * Compare and find the difference ΔI=I * -I0, after PID adjustment of ΔI, output current control signal I2; and according to the output control current signal I2, obtain the input command value I of the inductor current loop L * , specifically including the following units:

[0062] The current difference solving unit is used to compare I0 with the current loop input command value I0 in the current loop command value obtaining unit after the electronic load device detects the output current I0 in real time. * Make a comparison and find the difference ΔI=I * -I0;

[0063] Output current control signal second unit: used to perform PID adjustment on ΔI and output current control signal, specifically: when ΔI>0, the output control current signal I2 is a current increase signal; when ΔI<0, the output control current signal I2 is a current decrease signal;

[0064] The inductor current command value acquisition unit is used to obtain the input command value of the inductor current loop according to the current control signal. Specifically, if the output control current signal I2 is a current increase signal, the inductor current loop input command value I L *If the output control current signal I2 is a current reduction signal, the inductor current loop input command value I L * Reduce.

[0065] Inductor current loop module: used for real-time detection of inductor current I of load equipment L , and the input command value I of the current loop output L * Compare and find the difference Then ΔI L After PID adjustment, the PWM duty cycle signal Duty is output to control the on-time of the power tube of the load device. Specifically, it includes the following units:

[0066] Solving the inductor current difference unit: used to detect the inductor current I in real time in the electronic load device L After that, I L The inductor current loop input command value I in the inductor current command value acquisition unit L * Compare and find the difference

[0067] Output PWM duty cycle signal unit: used to adjust ΔI L Perform PID adjustment and output PWM duty cycle signal Duty, specifically: if ΔI L >0, the PWM duty cycle signal Duty becomes smaller, at this time the main power tube conduction time of the load device becomes shorter, and the current transmitted to the load becomes larger; if ΔI L <0, the PWM duty cycle signal Duty becomes larger, at this time the main power tube of the load device is turned on for a longer time, and the current transmitted to the load becomes smaller.

[0068] This embodiment utilizes the voltage loop module to automatically adjust the current instruction of the load without manual input, thereby improving the voltage stabilization efficiency and ensuring work safety.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An adaptive voltage stabilization method for a fuel cell dedicated electronic load, characterized in that: The following steps are involved: S1: The load device is equipped with a human-machine interface that sets the required stable voltage command U in advance. ref ; S2: The voltage loop works, and the load device detects the output voltage U0 in real time and compares U0 with U ref Compare and take the difference ΔU=U0-U ref After PID adjustment of ΔU, the output control current signal I1 is obtained. According to the output control current signal I1, the input command value I of the current loop is obtained. * ; S3: The current loop works, and the load device detects the output current I0 in real time, which is consistent with the input command value I output by the voltage loop. * Compare and take the difference ΔI=I * -I0, after PID adjustment of ΔI, the output current control signal I2 is output. According to the output control current signal I2, the input command value I of the inductor current loop is obtained. L * ; S4: The inductor current loop works, and the load device detects the inductor current I in real time. L , and the input command value I of the current loop output L * Compare and Difference ΔI L After PID adjustment, a PWM duty cycle signal Duty is output to control the on-time of the power tube of the load device.

2. The adaptive voltage stabilization method for a fuel cell dedicated electronic load according to claim 1, characterized in that: The output end of the fuel cell is connected in parallel with the output end of the load device to obtain the output voltage U0 described in step S2.

3. The adaptive voltage stabilization method for a fuel cell dedicated electronic load according to claim 1, characterized in that: In step S2 , the process of obtaining the control current signal I1 is as follows: when ΔU>0, the output control current signal I1 is a current increase signal; when ΔU<0, the output control current signal I1 is a current decrease signal.

4. The adaptive voltage stabilization method for a fuel cell dedicated electronic load according to claim 3, characterized in that: When the output control current signal I1 is a current increase signal, the current loop input command value I * When the output control current signal I1 is a current reduction signal, the current loop input command value I * Reduce.

5. The adaptive voltage stabilization method for a fuel cell dedicated electronic load according to claim 1, characterized in that: In step S3, the process of obtaining the control current signal I2 is: when ΔI>0, the output control current signal I2 is a current increase signal; when ΔI<0, the output control current signal I2 is a current decrease signal.

6. The adaptive voltage stabilization method for a fuel cell dedicated electronic load according to claim 5, characterized in that: When the output control current signal I2 is a current increase signal, the inductor current loop input command value I L * When the output control current signal I2 is a current reduction signal, the inductor current loop input command value I L * Reduce.

7. The adaptive voltage stabilization method for a fuel cell dedicated electronic load according to claim 1, characterized in that: In step S4, when ΔI L >0, the PWM duty cycle signal Duty becomes smaller; when ΔI L <0, the PWM duty cycle signal Duty becomes larger.

8. The adaptive voltage stabilization method for a fuel cell dedicated electronic load according to claim 7, characterized in that: When the PWM duty cycle signal Duty becomes smaller, the on-time of the power tube of the load device becomes shorter; when the PWM duty cycle signal Duty becomes larger, the on-time of the power tube of the load device becomes longer.

9. The adaptive voltage stabilization method for a fuel cell dedicated electronic load according to claim 8, characterized in that: When the conduction time of the power tube of the load device becomes shorter, the current of the load device becomes larger; when the conduction time of the power tube of the load device becomes longer, the current of the load device becomes smaller.

10. An adaptive voltage stabilization system for a fuel cell dedicated electronic load, characterized in that: Includes the following modules: Setting the required voltage module: used to set the required stable voltage command U in advance on the human-machine interface equipped with the load device ref ; Voltage loop module: used to detect the output voltage U0 of the load device in real time and then compare U0 with U ref Compare and take the difference ΔU=U0-U ref , after PID adjustment of ΔU, the output control current signal I1 is output; and according to the output control current signal I1, the input command value I of the current loop is obtained * ; Current loop module: used to detect the output current I0 of the load device in real time and compare it with the input command value I of the voltage loop output * Compare and take the difference ΔI=I * -I0, after PID adjustment of ΔI, output current control signal I2; and according to the output control current signal I2, obtain the input command value I of the inductor current loop L * ; Inductor current loop module: used to detect the inductor current I in real time in the load device L After that, the input command value I of the current loop output L * Compare and take the difference ΔI L After PID adjustment, a PWM duty cycle signal Duty is output to control the on-time of the power tube of the load device.

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