Feeding device of fuel cell system based on liquid feeding and control method thereof

Abstract

The invention provides a feeding device of a fuel cell system based on liquid feeding and a control method of the feeding device. The device comprises a gear pump, a main control system, a pressure sensor and a flow sensor, the main control system receives a feeding pressure signal sent by the pressure sensor, receives a real-time flow signal of feeding fuel sent by the flow sensor, and receives a rotating speed signal sent by the gear pump; the main control system calculates a control signal of the gear pump based on the feeding pressure signal, the real-time flow signal and the rotating speed signal; and the flow sensor sends a real-time flow signal of the fed fuel to the main control system. The input end of the gear pump is connected with the fuel barrel, the output end of the gear pump is connected with the flow sensor, and the output end of the flow sensor is connected with the fuel processor. The flow feeding precision is not affected by reaction pressure, the feeding flow fluctuation is continuous, the flow control precision is high, and the liquid stability is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cell, in particular, especially to a kind of feed device of fuel cell system based on liquid feed and control method thereof. BACKGROUND

[0002] Fuel cell is a kind of energy conversion device, for converting chemical energy in fuel into electric energy directly.Hydrogen fuel cell uses hydrogen or hydrogen-rich gas as fuel.Compared with internal combustion generator, hydrogen fuel cell has the advantages of high efficiency, environmental friendliness, strong reliability, high flexibility etc.But hydrogen is flammable and explosive, its explosion limit is very wide, when the volume concentration of hydrogen in air is between 4.0% and 75.6%, it will explode when encountering fire source.Moreover, hydrogen is very small in volume, and has strong permeability, which is easy to leak out from storage container and pipeline.Unfavorable for safe transportation and storage.Therefore, online hydrogen production fuel cell system emerges as the times require, and the fuel participating in the reaction is usually liquid fuel such as methanol, ethanol, gasoline and diesel, so the precision and stability of liquid feed can affect the reaction of the system, thereby affecting the hydrogen production quantity and quality.

[0003] Most of the traditional liquid feed devices adopt open-loop control, in order to reduce the influence of feed pressure, pump head with feed pressure much larger than required feed pressure is selected, this kind of feed mode is high in price and power consumption, another kind of electric injection constant pressure rail feed mode suitable for small pressure feed is also open-loop feed control, which cannot be found in time when feed blockage occurs.There is also a pure closed-loop control scheme, which feeds rapidly in a certain flow range, but feeds slowly in the whole flow range. SUMMARY

[0004] In order to solve the problems of accurate and rapid response and low power consumption of liquid feed, the present application provides a kind of feed device of fuel cell system based on liquid feed and control method thereof.Pressure sensor and flow sensor are used to feedback control the flow of liquid pump, compared with traditional open-loop control scheme, the flow feed precision is not affected by reaction pressure, and the flow fluctuation is continuous, the flow control precision is high and the liquid stability is good.

[0005] The technical means adopted by the present application are as follows:

[0006] A kind of feed device of fuel cell system based on liquid feed, comprising gear pump, main control system, pressure sensor and flow sensor;

[0007] The gear pump sends rotation speed signal to the main control system;

[0008] The master control system receives the feed pressure signal sent by the pressure sensor, the master control system receives the real-time flow signal of the feed fuel sent by the flow sensor, the master control system receives the rotating speed signal sent by the gear pump, and the master control system calculates the control signal of the gear pump based on the feed pressure signal, the real-time flow signal and the rotating speed signal;

[0009] The pressure sensor sends the feed pressure signal to the master control system.

[0010] The flow sensor sends the real-time flow signal of the feed fuel to the master control system.

[0011] The input end of the gear pump is connected with the fuel cylinder, the output end of the gear pump is connected with the flow sensor, and the output end of the flow sensor is connected with the fuel processor.

[0012] Further, the master control system comprises a flow control PID module and a rotating speed control PID module.

[0013] The flow control PID module receives the pulse signal sent by the flow sensor and calculates the real-time flow according to the pulse signal, and the flow control PID module calculates the gear pump pump control rotating speed signal through the flow PID controller in the flow control PID module.

[0014] The rotating speed control PID module receives the rotating speed signal and the gear pump pump control rotating speed signal and inputs the rotating speed signal and the gear pump pump control rotating speed signal to the rotating speed control PID controller, and the rotating speed control PID controller calculates the control gear pump signal.

[0015] Further, the master control system is provided with a DA conversion module to convert the control gear pump signal into a corresponding control voltage.

[0016] The application also provides a control method of the feed device of the liquid feed-based fuel cell system, which is realized based on any one of the above-mentioned liquid feed-based fuel cell system feed devices and comprises the following steps.

[0017] S1, the master control system calculates the control signal of the gear pump by collecting the feed pressure signal sent by the pressure sensor, the real-time flow signal of the feed fuel sent by the flow sensor and the rotating speed signal sent by the gear pump.

[0018] S2, based on different control signals, the flow calibration of different control signals under the same feed pressure condition is carried out, and then the flow-pressure relationship is calibrated under different pressure conditions to make a control table.

[0019] S3. Collect pulse signals through magnetic flow sensor, calculate real-time flow, control the size of liquid feed flow according to the required liquid feed flow, combine the control parameters obtained from the control table, and obtain the gear pump control speed range from the control table. Add the obtained gear pump control speed range, the calculated real-time flow, and the required control flow to the PID controller to calculate and obtain the gear pump control speed signal.

[0020] S4. The speed signal measured by the Hall sensor of the gear pump and the speed signal output by the flow control PID module are input to the speed control PID controller. The calculation result is the control signal for the gear pump, and the control voltage is obtained through the DA conversion in the main control system.

[0021] S5. When the gear pump receives the control signal, it executes the control speed corresponding to the control signal, thereby changing the liquid flow rate.

[0022] Furthermore, the flow control PID module and the speed control PID module are each equipped with a limiting module.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] This invention provides a liquid feeding method that utilizes a closed-loop control system composed of a low-pressure liquid pump, a flow sensor, and a pressure sensor, combined with feedforward and feedback control techniques. This achieves more reliable feeding accuracy, faster response speed, and lower power consumption for liquid feeding. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a diagram of the liquid feeding device for the fuel cell system of the present invention.

[0027] Figure 2 This is a flow rate calibration curve diagram for the present invention.

[0028] Figure 3 This is a schematic diagram of the liquid feed control of the present invention.

[0029] Figure 4 This is a schematic diagram of the signal processing for the liquid feed path of the present invention.

[0030] In the diagram: 1. Gear pump; 2. Flow sensor; 3. Main control system; 4. Pressure sensor; 5. Fuel tank; 6. Fuel processor. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0034] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0035] like Figure 1 As shown, the present invention provides a feeding device for a fuel cell system based on liquid feeding, including a gear pump 1, a main control system 3, a pressure sensor 4 and a flow sensor 2;

[0036] The gear pump 1 sends a speed signal to the main control system 3;

[0037] The main control system 3 receives the feed pressure signal sent by the pressure sensor 4, the main control system 3 receives the real-time flow signal of the feed fuel sent by the flow sensor 2, and the main control system 3 receives the speed signal sent by the gear pump 1. The main control system 3 calculates the control signal of the gear pump 1 based on the feed pressure signal, the real-time flow signal and the speed signal.

[0038] The main control system 3 includes a flow control PID module and a speed control PID module;

[0039] The flow control PID module receives the pulse signal sent by the flow sensor 2 and calculates the real-time flow based on the pulse signal. The flow control PID module calculates the pump control speed signal of the gear pump 1 through the flow PID controller inside it.

[0040] The speed control PID module receives the speed signal and the speed control signal of gear pump 1, and inputs the speed signal and the speed control signal of gear pump 1 to the speed control PID controller. The speed control PID controller calculates the control signal of gear pump 1.

[0041] The pressure sensor 4 sends a feed pressure signal to the main control system 3;

[0042] The flow sensor 2 sends a real-time flow signal of the feed fuel to the main control system 3.

[0043] The input end of the gear pump 1 is connected to the fuel tank 5, the output end of the gear pump 1 is connected to the flow sensor 2, and the output end of the flow sensor 2 is connected to the fuel processor 6.

[0044] The present invention also provides a control method for a feeding device of a fuel cell system based on liquid feed, comprising the following steps:

[0045] S1. The main control system 3 calculates the control signal of gear pump 1 by collecting the feed pressure signal sent by pressure sensor 4, the real-time flow signal of feed fuel sent by flow sensor 2, and the speed signal sent by gear pump 1.

[0046] Traditional PID calculation

[0047] Gear pump speed control signal = K p ×error+K i ×Error integral + K d ×Error Differential

[0048] Where: K p It is the proportional gain, used to amplify error signals. K i It is the integral gain, used to integrate the error signal to eliminate steady-state error. K dIt is the differential gain, used to predict the trend of error changes in order to reduce overshoot and oscillation.

[0049] S2. According to the calibrated flow curve of the selected gear pump 1, as shown in... Figure 2 The specific method is based on different control signals (voltage, PWM). Under the same feed pressure, the flow rate of different control signals is calibrated, and then the relationship between flow rate and pressure is calibrated under different pressure conditions in the same way, and a control table is made.

[0050] S3. Collect pulse signals through magnetic flow sensor 2, calculate real-time flow, control the required liquid feed flow rate according to the required liquid feed flow rate, combine the control parameters obtained from the control table, and enter the flow PID controller for calculation. The calculation result is the speed control signal of gear pump 1.

[0051] The formula for calculating real-time traffic is as follows:

[0052] Flow velocity (V) = k * P / T

[0053] Where V is the flow velocity, k is the flow meter coefficient, P is the number of pulses, and T is the pulse time interval.

[0054] The formula for calculating the flow rate using a PID controller is as follows:

[0055] Traditional PID calculation

[0056] Gear pump speed control signal = K p ×error+K i ×Error integral + K d ×Error Differential

[0057] Where: K p It is the proportional gain, used to amplify error signals. K i It is the integral gain, used to integrate the error signal to eliminate steady-state error. K d It is the differential gain, used to predict the trend of error changes in order to reduce overshoot and oscillation.

[0058] S4. The speed signal measured by the Hall sensor of gear pump 1 and the speed signal output by the flow control PID module are input to the speed control PID controller. The calculation result is the control signal for gear pump 1, and the control voltage is obtained through the DA conversion in the main control system 3.

[0059] S5. Gear pump 1 receives a control signal and executes the control speed corresponding to the control signal, thereby changing the liquid flow rate.

[0060] Both the flow control PID module and the speed control PID module have amplitude limiting modules to avoid control signal saturation and other problems.

[0061] In this invention: pressure sensor 4 detects the feed pressure. One function of pressure sensor 4 is to determine whether the flow rate measured by flow sensor 2 is caused by liquid feed or air. Another function is to quickly find the control range of gear pump 1 based on the required flow rate and actual pressure.

[0062] The liquid flows out from gear pump 1 and then reaches liquid flow sensor 2. Pressure sensor 4 is added to liquid flow sensor 2 and gear pump 1. The sampling frequency of pressure sensor 4 and liquid flow sensor 2 is much greater than the pressure fluctuation of the liquid in the reactor.

[0063] The relationship between liquid flow rate, pressure, and control signal in this invention is similar. Figure 2 It's not all straight lines; it can also be a curve.

[0064] The liquid feed control of this invention adopts the following control scheme: Figure 3 The feature is that, based on the required liquid feed flow rate, the current feed pressure is collected, the range of the liquid pump control signal is found, and combined with the current flow rate, the required speed of gear pump 1 is calculated by the flow PID controller. The speed of gear pump 1 is fed into the speed PID controller through the limiting circuit, and the calculated output voltage signal is applied to gear pump 1, thereby affecting the output flow rate and achieving reliable flow control.

[0065] The control method used in this invention is to acquire data from pressure sensor 4 and use the pump curve as feedforward control, which can improve the response speed.

[0066] This invention employs dual closed-loop feedback control, with flow feedback serving as the outer loop control and speed feedback serving as the inner loop control, which can increase the reliability of the control.

[0067] The gear pump 1 selected in this invention is used as the liquid feed controller. Its advantages are that the liquid feed is stable and the flow rate fluctuates little, so the fuel processor 6 reacts evenly. Furthermore, the liquid flow rate is controlled at a small rate per revolution, so the liquid flow rate can be controlled more precisely.

[0068] Example 1

[0069] The liquid pump control signal is selected as a PWM duty cycle, corresponding to a liquid feed pump flow rate of 0-100 mL / min (10%-90%) and a corresponding speed of 0-5000 rpm. The pump body can provide a maximum pressure of 1 MPa. The selected flow sensor corresponds to a flow rate measurement range of 0-100 mL / min, with a corresponding pulse value of 0.05 mL / p. The pressure sensor outputs 4-20 mA, corresponding to a pressure range of 0-600 kPa. The main control chip uses the AD interface of an STM32F4 series MCU. The 4-20 mA signal is acquired through a signal linear optocoupler HCNR201 for isolation, filtering, current-to-voltage conversion, and analysis of the system's liquid feed pressure. The PWM interface is configured for input capture. The flow rate and speed are calculated using a 6N137 optocoupler, which acquires the pulse frequency from the flow sensor and the Hall effect signal frequency from the liquid pump. After calculation in the main control chip, the output is isolated by the PWM signal and then output. See [link to relevant documentation]. Figure 4 .

[0070] Example 2

[0071] Based on the circuit in Example 1, the characteristic curve of the liquid pump is measured, and the characteristic table of the liquid pump flow rate with pressure and control signal is stored in the MCU memory in the form of a binary array. After receiving the control flow rate, the MCU looks up the table to obtain the coarse control range of the liquid pump and adjusts the basic control signal to that range. Then, by calculating the actual flow rate and the control flow rate, an incremental PID control result is obtained. After superposition, the required control speed of the liquid pump at this time is given. Then, combined with the calculated actual speed, PID calculation is performed to obtain the control signal. After signal modulation, the control signal is sent to the liquid pump control terminal. The step response time of the control flow rate is ≤200ms, and the flow control accuracy is ≤0.5mL / min. Within the application pressure range, the flow rate is basically unaffected by the pressure.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A feed device for a liquid feed based fuel cell system, characterized by The gear pump, the main control system, the pressure sensor and the flow sensor are included. The gear pump sends a rotating speed signal to the main control system. The main control system receives a feeding pressure signal sent by the pressure sensor, a real-time flow signal of the feeding fuel sent by the flow sensor, a rotating speed signal sent by the gear pump, and calculates a control signal of the gear pump based on the feeding pressure signal, the real-time flow signal and the rotating speed signal. The pressure sensor sends the feeding pressure signal to the main control system. The flow sensor sends a real-time pulse signal of the feeding fuel to the main control system. The input end of the gear pump is connected with the fuel cylinder, the output end of the gear pump is connected with the flow sensor, and the output end of the flow sensor is connected with the fuel processor.

2. A liquid feed based fuel cell system feed arrangement according to claim 1, characterised in that, The main control system includes a flow control PID module and a rotating speed control PID module. The flow control PID module receives a pulse signal sent by the flow sensor and calculates a real-time flow according to the pulse signal, and calculates a gear pump control rotating speed signal through a flow PID controller in the flow control PID module. The rotating speed control PID module receives a rotating speed signal and a gear pump control rotating speed signal and inputs the rotating speed signal and the gear pump control rotating speed signal to a rotating speed control PID controller, and the rotating speed control PID controller calculates a control gear pump signal.

3. The liquid feed based fuel cell system feed device of claim 1, wherein, A DA conversion module is arranged in the main control system to convert the control gear pump signal into a corresponding control voltage.

4. A control method of a feed device of a liquid-feed-based fuel cell system, implemented based on the feed device of the liquid-feed-based fuel cell system according to any one of claims 1 to 3, characterized by, The method includes the following steps: S1, the main control system calculates a control signal of the gear pump by collecting a feeding pressure signal sent by the pressure sensor, a real-time flow signal of the feeding fuel sent by the flow sensor and a rotating speed signal sent by the gear pump; S2, based on different control signals, the flow calibration of different control signals under the same feeding pressure condition is performed, and the relationship between the flow and the pressure under different pressure conditions is calibrated to make a control table; S3, a pulse signal is collected by a magnetic flow sensor to calculate a real-time flow, the required liquid feeding flow control size is controlled, the control parameters obtained from the control table are combined, the gear pump control rotating speed interval is obtained from the control table, the obtained gear pump control rotating speed interval, the calculated real-time flow and the required control flow are added to a PID controller to calculate a gear pump control rotating speed signal; S4, a rotating speed signal measured by a Hall sensor of the gear pump and a flow control PID module output rotating speed signal are input to a rotating speed control PID controller, and the calculation result is a control gear pump signal, and a control voltage is obtained through DA conversion in the main control system; S5, the gear pump receives the control signal and executes the control rotating speed corresponding to the control signal to change the liquid flow.

5. The control method of the feed device of the liquid feed-based fuel cell system according to claim 4, characterized by, An amplitude limiting module is arranged in each of the flow control PID module and the rotating speed control PID module.

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