Low-temperature self-starting method, starting device and fuel cell system of hydrogen circulation pump

Abstract

The present invention relates to the technical field of hydrogen circulation pump control, and particularly to a low-temperature self-starting method, a starting device, and a fuel cell system for a hydrogen circulation pump; it includes: S1. Starting from power-on, entering the conventional starting mode, obtaining the ambient temperature around the motor stator or the pump head of the hydrogen circulation pump and determining whether the above temperature is lower than the melting point of water; if yes, entering S2; if no, starting normally; S2. The hydrogen circulation pump enters the low-temperature self-starting mode and executes the following steps S3-S5 in three stages; S3. The first stage of the low-temperature self-starting mode is the motor rotor position observation stage; S5. The third stage of the low-temperature self-starting mode is the low-speed lubrication stage; S6. Returning to execute S3; if the number of cycles reaches the preset upper limit, reporting a fault. In the present invention, since the initial position angle θ of the motor rotor has been estimated before the ice-breaking of the motor rotor vibration, the protection given current always acts on the Q-axis, and the maximum torque can be generated for ice-breaking under the same current, reducing the ice-breaking time and improving the ice-breaking ability.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen circulation pump control, and particularly to a low-temperature self-starting method, a starting device, and a fuel cell system for a hydrogen circulation pump. Background Art

[0002] A "hydrogen fuel cell" refers to a device that generates electrical energy through the chemical reaction of hydrogen with oxygen, and is used in fields such as automobiles, ships, or drones to replace traditional lithium batteries; traditional lithium batteries have problems such as environmental protection, slow charging speed, and a decrease in battery capacity at low temperatures, and the advantages of hydrogen fuel cells are gradually emerging. Hydrogen fuel cells can not only be used as a green power source for automobiles, but also as a large-scale hydrogen fuel power station in industry, and the prospects are self-evident. The stack is the "heart" of the fuel cell, providing electrical energy to ensure the normal operation of the entire system; hydrogen is the "blood" of the fuel cell; the hydrogen circulation system is the "strong myocardium" to ensure the smooth circulation of the "blood". Therefore, the hydrogen circulation system is also one of the key technologies of the fuel cell engine.

[0003] Since the hydrogen circulation pump is arranged in the hydrogen-side circulation loop of the fuel cell system, its inlet is connected to the outlet of the fuel cell. When the fuel cell system is working, the gas entering the inlet of the hydrogen circulation pump from the outlet of the fuel cell is generally in a saturated humidity state. If the hydrogen circulation pump is in a non-operating state, in a low-temperature environment, the water vapor in the gas circuit of the fuel cell system will easily condense and freeze on the surface of the hydrogen circulation pump after entering the hydrogen circulation pump. Also, due to the very small gap between the pump head and the housing of the hydrogen circulation pump, when the ambient temperature is lower than the melting point of water, the water vapor entering the hydrogen circulation pump will freeze at this gap, resulting in a jamming phenomenon between the pump head and the housing of the hydrogen circulation pump when the hydrogen circulation pump is started next time, causing the hydrogen circulation pump to be unable to start normally in a low-temperature environment and realize the circulation of hydrogen, and may even damage the impeller of the hydrogen circulation pump and requires ice breaking to operate normally. The current technology is to preheat the hydrogen circulation pump by heating with an electric heating wire to melt the internal ice for starting, which increases the cost and takes a relatively long time to melt the ice. Summary of the Invention

[0004] The object of the present invention is to provide a low-temperature self-starting method, a starting device, and a fuel cell system for a hydrogen circulation pump to solve the problem in the prior art that the hydrogen circulation pump is preheated by heating with an electric heating wire to melt the internal ice for starting, which increases the cost and takes a relatively long time to melt the ice.

[0005] The technical solution of the present invention is: A low-temperature self-starting method, a starting device, and a fuel cell system for a hydrogen circulation pump, comprising:

[0006] S1. At power-on start, enter the normal startup mode, obtain the ambient temperature around the motor stator or the pump head of the hydrogen circulation pump, and determine whether the above temperature is lower than the melting point of water; if yes, enter S2; if no, start normally;

[0007] S2. The hydrogen circulation pump enters the low-temperature self-start mode and executes the following steps S3 - S5 in three stages;

[0008] S3. The first stage of the low-temperature self-start mode is the motor rotor position observation stage; obtain the initial position angle θ of the motor rotor of the hydrogen circulation pump;

[0009] S4. The second stage of the low-temperature self-start mode is the motor rotor vibration ice-breaking stage; there is a current closed-loop and a speed open-loop in the software control of the hydrogen circulation pump; among them, in the speed open-loop, the rotor set angle Setφ is equal to the initial position angle θ of the motor rotor; and in the current closed-loop, a current with a preset frequency is injected into the motor stator of the hydrogen circulation pump to generate a torque for ice-breaking, so that the motor rotor generates vibration to reduce the starting torque;

[0010] S5. The third stage of the low-temperature self-start mode is the low-speed lubrication stage; accelerate the motor of the hydrogen circulation pump to the lowest operating speed at a preset acceleration, and at the same time monitor the current torque of the motor of the hydrogen circulation pump; if the current torque of the motor of the hydrogen circulation pump is less than a certain multiple of its normal rated torque within the specified time, end the low-speed lubrication stage and enter the normal working mode; if the current torque of the motor of the hydrogen circulation pump is greater than or equal to a certain multiple of its normal rated torque within the specified time, enter S6;

[0011] S6. Return to execute S3; if the number of cycles reaches the preset upper limit, report a fault.

[0012] Preferably, in the above S4, the method of injecting a current with a preset frequency into the motor stator of the hydrogen circulation pump to generate a torque for ice-breaking is:

[0013] After being transformed by the IQ symbol converter, the output is the alternately positive and negative Iq_ref; among them, the input value Set_IQ of the IQ symbol converter is the maximum torque value that the motor rotor can withstand;

[0014] The I a 、I b currents are sampled through the current sensor, and the I a 、I b currents in the conventional three-phase coordinate system are transformed into the I α 、I β currents in the two-phase stationary coordinate system through the Clarke coordinate transformation;

[0015] The I α, I β I transformed into the two-phase rotating coordinate system d , I q current;

[0016] I d , I q The I and I currents and the d-axis set current Id_ref and q-axis set current Iq_ref pass through a PI regulator to output V in the two-phase rotating coordinate system d and V q voltage;

[0017] For V d and V q Perform the inverse Park coordinate transformation to obtain V in the two-phase stationary coordinate system α and V β ;

[0018] For V α and V β Perform the inverse Clarke coordinate transformation to transform V in the two-phase stationary coordinate system α and V β into the conventional three-phase coordinate system to obtain V r 1, V r 2, V r 3;

[0019] Modulate V r 1, V r 2, V r 3 into a space vector pulse width modulation signal, and control the turn-off and turn-on of the three-phase inverter connected to the motor according to the space vector pulse width modulation signal to control the rotation of the motor.

[0020] Preferably, the established multiple is 1 - 1.5 times, the preset frequency is 200 - 1000 Hz, and the preset acceleration range is 10 - 500 rpm / s.

[0021] The present invention also provides a starting device for a hydrogen circulation pump. The starting device for the hydrogen circulation pump starts by using the above-mentioned low-temperature self-starting method for a hydrogen circulation pump. The starting device for the hydrogen circulation pump includes a temperature sensor and a control element. Among them, the temperature sensor is used to detect the ambient temperature around the motor stator or the pump head of the hydrogen circulation pump;

[0022] The control element is used to control the hydrogen circulation pump to start through the low-temperature self-starting mode when the internal temperature of the motor of the hydrogen circulation pump is lower than the melting point of water; when the internal temperature of the motor of the hydrogen circulation pump is not lower than the melting point of water, control the hydrogen circulation pump to start through the conventional starting mode.

[0023] The present invention also provides a fuel cell system, comprising: a fuel cell, a hydrogen circulation pump, an air outlet passage located between the fuel cell and the hydrogen circulation pump, an air inlet passage located between the hydrogen circulation pump and the fuel cell, and a starting device for the hydrogen circulation pump; wherein, the hydrogen circulation pump is configured to transport the gas output from the air outlet of the fuel cell to the air inlet of the fuel cell through the air inlet passage via the air outlet passage; the starting device of the hydrogen circulation pump is started by using the above-mentioned low-temperature self-starting method for a hydrogen circulation pump, and the starting device of the hydrogen circulation pump includes a temperature sensor and a control element, wherein the temperature sensor is used to detect the ambient temperature around the motor stator or the pump head of the hydrogen circulation pump;

[0024] The control element is configured to control the hydrogen circulation pump to start through a low-temperature self-starting mode when the internal temperature of the motor of the hydrogen circulation pump is lower than the melting point of water; when the internal temperature of the motor of the hydrogen circulation pump is not lower than the melting point of water, the control element controls the hydrogen circulation pump to start through a conventional starting mode.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] In the present invention, since the initial position angle θ of the motor rotor has been estimated before the ice breaking by the vibration of the motor rotor, the protection given current always acts on the Q axis, and the maximum torque can be generated for ice breaking under the same current, reducing the ice breaking time and improving the ice breaking ability.

[0027] The present invention can make the motor rotor generate vibration to break ice, and synchronize the rotor position to generate the maximum torque to start the motor during startup. Compared with the method of heating the pump head by an electric heating wire in the prior art, the present invention does not require adding additional devices and can complete ice breaking startup within a few seconds, reducing costs while having a higher ice breaking efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the drawings and embodiments:

[0029] Figure 1 is the control flow chart of the low-temperature self-starting method for the hydrogen circulation pump in this embodiment;

[0030] Figure 2 is the control block diagram of the current closed-loop and speed open-loop in the software control of the hydrogen circulation pump in this embodiment;

[0031] Figure 3 is the schematic diagram of the injection of a voltage pulse with a constant amplitude in the method of obtaining the initial position angle θ of the motor rotor in this embodiment;

[0032] Figure 4 、 Figure 5It is the positive and negative alternating Iq_ref vector diagram output by the IQ symbol converter in this embodiment. Detailed implementation manners

[0033] The following further describes the content of the present invention in detail with reference to specific embodiments:

[0034] In the description of the invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0035] As Figure 1 shown, the low-temperature self-starting method, starting device, and fuel cell system of the hydrogen circulation pump include:

[0036] S1. When power is on, enter the normal start mode, obtain the ambient temperature around the motor stator or the pump head of the hydrogen circulation pump, and determine whether the above temperature is lower than the melting point of water; if yes, enter S2; if no, start normally; specifically, the ambient temperature around the motor stator or the pump head can be obtained through a motor temperature sensor or an ambient temperature sensor;

[0037] S2. The hydrogen circulation pump enters the low-temperature self-start mode and executes the following steps S3 - S5 in three stages;

[0038] S3. The first stage of the low-temperature self-start mode is the motor rotor position observation stage; obtain the initial position angle θ of the motor rotor of the hydrogen circulation pump;

[0039] In the above S3, the method for obtaining the initial position angle θ of the motor rotor of the hydrogen circulation pump is: at zero speed, by injecting voltage pulses with a constant amplitude into any two of the three-phase windings (as Figure 3 shown), using a current sensor to sample the three-phase current of the motor stator to obtain six current values i ab , i ba , i bc , i cb , i ca , i ac . Given that Δi AB = i ab - i ba , Δi BC = i bc - i cb , ΔiCA = i ca -i ac , Therefore, the initial position angle θ of the motor rotor can be obtained; the initial position angle θ of the motor rotor can also be obtained through the motor encoder or the resolver;

[0040] S4. The second stage of the low-temperature self-starting mode is the ice-breaking stage of the motor rotor vibration; a current closed-loop and a speed open-loop are provided in the software control of the hydrogen circulation pump; as Figure 2 shown, where the set angle Setφ of the rotor in the speed open-loop is equal to the initial position angle θ of the motor rotor; and in the current closed-loop, a current with a preset frequency is injected into the motor stator of the hydrogen circulation pump to generate a torque for ice-breaking, so that the motor rotor generates vibration to reduce the starting torque; in this embodiment, the preset frequency is 200Hz - 1000Hz, that is, to make the motor rotor generate the maximum vibration so as to achieve the purpose of reducing the starting torque after ice-breaking;

[0041] The method of injecting a current with a preset frequency into the motor stator of the hydrogen circulation pump to generate a torque for ice-breaking is: after being transformed by the IQ symbol converter, the output is the alternately positive and negative Iq_ref, and the purpose of the alternately positive and negative Iq_ref is to make the rotor of the motor generate greater vibration; among them, the input value Set_IQ of the IQ symbol converter is the maximum torque value that the motor rotor can withstand;

[0042] The current I a , I b is sampled through the current sensor, and the I a , I b current in the conventional three-phase coordinate system is converted into the I α , I β current in the two-phase stationary coordinate system through the Clarke coordinate transformation;

[0043] The I α , I β in the two-phase stationary coordinate system is converted into the I d , I q current in the two-phase rotating coordinate system through the Park coordinate transformation;

[0044] The I d , I q current and the d-axis set current Id_ref, q-axis set current Iq_ref pass through the PI regulator to output the V d and V q voltages in the two-phase rotating coordinate system;

[0045] The V d and V q are subjected to the inverse Park coordinate transformation to obtain the V αand V β ;

[0046] For V α and V β perform the inverse Clarke coordinate transformation to transform V α and V β in the two-phase stationary coordinate system into the conventional three-phase coordinate system to obtain V r 1, V r 2, V r 3;

[0047] Modulate V r 1, V r 2, V r 3 into a space vector pulse width modulation signal, and control the turn-off and turn-on of the three-phase inverter connected to the motor according to the space vector pulse width modulation signal to control the rotation of the motor.

[0048] S5. The third stage of the low-temperature self-start mode is the low-speed lubrication stage; the motor of the hydrogen circulation pump is accelerated to the lowest operating speed at a preset acceleration, and at the same time, the current torque of the motor of the hydrogen circulation pump is monitored; if the current torque of the motor of the hydrogen circulation pump is less than a predetermined multiple of its normal rated torque within a specified time, the low-speed lubrication stage ends and the normal operating mode is entered; if the current torque of the motor of the hydrogen circulation pump is greater than or equal to a predetermined multiple of its normal rated torque within a specified time, enter S6; in this embodiment, the preset acceleration range is 10 - 500 rpm / s; preferably, within 5 seconds, the motor is accelerated to 500 rpm at an acceleration of 50 rpm / s, and it is judged whether the current torque of the motor of the hydrogen circulation pump is less than a predetermined multiple of its normal rated torque; the low-speed lubrication stage ensures that the magnetic field formed by the three-phase current in the motor stator and the rotor are as synchronous as possible, so as to generate the maximum torque to drive the rotor to rotate; in this embodiment, the predetermined multiple is 1 - 1.5 times, preferably 1.3 times; in this embodiment, the setting of each parameter can not only ensure the maximum torque to drive the rotor to rotate, but also ensure that the control elements of the hydrogen circulation pump will not be overcurrent.

[0049] S6. Return to execute S3; if the number of cycles reaches the preset upper limit, report a fault.

[0050] The present invention also provides a starting device for a hydrogen circulation pump. The starting device for the hydrogen circulation pump is started by using the above-mentioned low-temperature self-start method for a hydrogen circulation pump. The starting device for the hydrogen circulation pump includes a temperature sensor and a control element. Among them, the temperature sensor is used to detect the ambient temperature around the motor stator or the pump head of the hydrogen circulation pump;

[0051] The control element is used to control the hydrogen circulation pump to start through the low-temperature self-start mode when the internal temperature of the motor of the hydrogen circulation pump is lower than the melting point of water; when the internal temperature of the motor of the hydrogen circulation pump is not lower than the melting point of water, the control element is used to control the hydrogen circulation pump to start through the conventional start mode.

[0052] The present invention also provides a fuel cell system, including: a fuel cell, a hydrogen circulation pump, an air outlet passage located between the fuel cell and the hydrogen circulation pump, an air inlet passage located between the hydrogen circulation pump and the fuel cell, and a starting device for the hydrogen circulation pump; wherein, the hydrogen circulation pump is used to convey the gas output from the air outlet of the fuel cell to the air inlet of the fuel cell through the air inlet passage.

[0053] The starting device of the hydrogen circulation pump is started by using the above-mentioned low-temperature self-start method for the hydrogen circulation pump. The starting device of the hydrogen circulation pump includes a temperature sensor and a control element. Among them, the temperature sensor is used to detect the ambient temperature around the stator of the motor of the hydrogen circulation pump or the pump head.

[0054] The control element is used to control the hydrogen circulation pump to start through the low-temperature self-start mode when the internal temperature of the motor of the hydrogen circulation pump is lower than the melting point of water; when the internal temperature of the motor of the hydrogen circulation pump is not lower than the melting point of water, the control element is used to control the hydrogen circulation pump to start through the conventional start mode.

[0055] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims within the present invention.

Claims

1. A low-temperature self-starting method for a hydrogen circulation pump, characterized in that, Including: S1. When powered on and starting, enter the normal startup mode, obtain the ambient temperature around the motor stator or the pump head of the hydrogen circulation pump, and determine whether the above temperature is lower than the melting point of water; if yes, enter S2; if no, start normally; S2. The hydrogen circulation pump enters the low-temperature self-start mode and executes the following steps S3 - S5 in three stages; S3. The first stage of the low-temperature self-start mode is the motor rotor position observation stage; obtain the initial position angle θ of the motor rotor of the hydrogen circulation pump; S4. The second stage of the low-temperature self-start mode is the motor rotor vibration ice-breaking stage; there is a current closed-loop and a speed open-loop in the software control of the hydrogen circulation pump; among them, the rotor set angle Setφ in the speed open-loop is equal to the initial position angle θ of the motor rotor; and in the current closed-loop, a current with a preset frequency is injected into the motor stator of the hydrogen circulation pump to generate a torque for ice-breaking, so that the motor rotor generates vibration to reduce the starting torque; S5. The third stage of the low-temperature self-start mode is the low-speed lubrication stage; accelerate the motor of the hydrogen circulation pump to the lowest operating speed at a preset acceleration, and at the same time monitor the current torque of the motor of the hydrogen circulation pump; if the current torque of the motor of the hydrogen circulation pump is less than a certain multiple of its normal rated torque within the specified time, end the low-speed lubrication stage and enter the normal operating mode; if the current torque of the motor of the hydrogen circulation pump is greater than or equal to a certain multiple of its normal rated torque within the specified time, enter S6; S6. Return to execute S3; if the number of cycles reaches the preset upper limit, report a fault.

2. The low-temperature self-starting method of a hydrogen circulation pump according to claim 1, characterized in that: In the above S4, the method of injecting a current with a preset frequency into the motor stator of the hydrogen circulation pump to generate a torque for ice-breaking is: After being transformed by the IQ symbol converter, the output is Iq_ref with positive and negative alternation; among them, the input value Set_IQ of the IQ symbol converter is the maximum torque value that the motor rotor can withstand; Obtain I by sampling through a current sensor a and I b currents. Transform the I a and I b currents in the conventional three-phase coordinate system into I α and I β currents in the two-phase stationary coordinate system; Transform I α and I β in the two-phase static coordinate system into I d and I q currents in the two-phase rotating coordinate system; I d 、I q The armature current and the d-axis reference current Id_ref and the q-axis reference current Iq_ref pass through a PI regulator to output the V d and V q voltages in the two-phase rotating coordinate system; Perform the inverse Park transformation on V d and V q to obtain V α and V β in the two-phase stationary coordinate system; For V α and V β perform the inverse Clarke coordinate transformation to transform V α and V β in the two-phase stationary coordinate system into the conventional three-phase coordinate system to obtain V r 1, V r 2, V r 3; Modulate V r 1. V r 2. V r 3 is modulated into a space vector pulse width modulation signal, and the turn-off and turn-on of a three-phase inverter connected to the motor are controlled according to the space vector pulse width modulation signal to control the rotation of the motor.

3. A low-temperature self-starting method for a hydrogen circulation pump according to claim 2, characterized in that: The certain multiple is 1 - 1.5 times, the preset frequency is 200 - 1000 Hz, and the preset acceleration range is 10 - 500 rpm / s.

4. A starting device for a hydrogen circulation pump, wherein the starting device for the hydrogen circulation pump is started by using the low-temperature self-starting method for a hydrogen circulation pump described in any one of claims 1-3, and is characterized in that: The starting device of the hydrogen circulation pump includes a temperature sensor and a control element, where the temperature sensor is used to detect the ambient temperature around the motor stator or the pump head of the hydrogen circulation pump; The control element is used to control the hydrogen circulation pump to start through the low-temperature self-start mode when the internal temperature of the motor of the hydrogen circulation pump is lower than the melting point of water; when the internal temperature of the motor of the hydrogen circulation pump is not lower than the melting point of water, control the hydrogen circulation pump to start through the normal startup mode.

5. A fuel cell system, characterized in that, Including: A fuel cell, a hydrogen circulation pump, an air outlet passage located between the fuel cell and the hydrogen circulation pump, an air inlet passage located between the hydrogen circulation pump and the fuel cell, and a starting device for the hydrogen circulation pump; wherein, the hydrogen circulation pump is configured to convey the gas output from the air outlet of the fuel cell to the air outlet passage through the air inlet passage to the air inlet of the fuel cell; the starting device of the hydrogen circulation pump is started by using a low-temperature self-starting method for a hydrogen circulation pump according to any one of claims 1-3, and the starting device of the hydrogen circulation pump includes a temperature sensor and a control element, wherein the temperature sensor is configured to detect the ambient temperature around the motor stator or the pump head of the hydrogen circulation pump; the control element is configured to control the hydrogen circulation pump to start through a low-temperature self-starting mode when the internal temperature of the motor of the hydrogen circulation pump is lower than the melting point of water; and when the internal temperature of the motor of the hydrogen circulation pump is not lower than the melting point of water, control the hydrogen circulation pump to start through a conventional starting mode.

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