Fuel cell stack voltage sensing system and method

Abstract

This invention discloses a voltage sensing system and method for a fuel cell stack. According to a preferred embodiment of the present invention, the voltage sensing system for a fuel cell stack includes: a stack sensing unit, which compares the input voltage with a reference voltage when a voltage is input to the fuel cell stack, and outputs a comparison result; and a determination unit, which determines whether a negative voltage is generated in the fuel cell stack based on the output voltage of the stack sensing unit and a reference duty cycle used to generate the reference voltage.

Description

Technical Field

[0001] This invention relates to a voltage sensing system and method for a fuel cell stack. Background Technology

[0002] In recent years, fuel cell vehicles have been increasingly developed as a solution to global environmental problems.

[0003] Fuel cell vehicles use fuel cell stacks to power electric motors to drive.

[0004] The fuel cell stack installed on fuel cell vehicles uses the chemical reaction between hydrogen fuel and oxygen to generate electricity.

[0005] When a fuel cell stack fails to generate electricity, it may carry a negative voltage, which could lead to malfunction or permanent damage.

[0006] Therefore, there is a need for a device that can take appropriate measures by sensing the negative voltage of the fuel cell stack.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Korean Patent No. 10-1592768 Summary of the Invention

[0010] The present invention is proposed in view of the above-mentioned problems, and its purpose is to provide a voltage sensing system and method for fuel cell stacks, which senses negative voltage by measuring the cell voltage of the fuel cell stack, thereby ensuring the stability of the fuel cell stack.

[0011] To achieve the aforementioned objective, a voltage sensing system for a fuel cell stack according to a preferred embodiment of the present invention includes: a stack sensing unit that compares the input voltage with a reference voltage when the voltage of the fuel cell stack is input, and outputs a comparison result; and a determination unit that determines whether a negative voltage is generated in the fuel cell stack based on the output voltage of the stack sensing unit and a reference duty cycle used to generate the reference voltage.

[0012] The stack sensing unit may include: an oscillation unit that outputs the reference voltage considering the reference duty cycle; a comparison unit that compares the reference voltage with the input voltage; and an adjustment unit that adjusts the voltage level based on the comparison result of the comparison unit.

[0013] The oscillation unit can generate the reference voltage based on a positive voltage source and a negative voltage source.

[0014] The oscillation unit can generate the reference voltage in the form of a triangular wave or a sine wave with a predetermined period according to the reference duty cycle.

[0015] The comparison unit can output a high-level comparison result when the input voltage is greater than the reference voltage, and can output a low-level comparison result when the input voltage is less than the reference voltage.

[0016] The determination unit can determine that a negative voltage has been generated in the fuel cell stack when the duty cycle of the output voltage is less than the reference duty cycle.

[0017] To achieve the aforementioned objective, a voltage sensing method for a fuel cell stack according to a preferred embodiment of the present invention includes: an input step, wherein a voltage of the fuel cell stack is input; a comparison step, wherein the input voltage is compared with a reference voltage; and a determination step, wherein a negative voltage is generated in the fuel cell stack based on the comparison result of the comparison step and a reference duty cycle used to generate the reference voltage.

[0018] Prior to the input step, an oscillation step may also be included, which takes into account a positive voltage source, a negative voltage source, and the reference duty cycle to output the reference voltage.

[0019] In the comparison step, when the input voltage is greater than the reference voltage, a high-level comparison result can be output; when the input voltage is less than the reference voltage, a low-level comparison result can be output.

[0020] In the judgment step, when the duty cycle of the comparison result is less than the reference duty cycle, it can be determined that a negative voltage has been generated in the fuel cell stack.

[0021] It may also include an adjustment step to adjust the voltage level of the comparison result.

[0022] Invention Effects

[0023] According to a preferred embodiment of the present invention, a voltage sensing system and method for a fuel cell stack can take appropriate measures by sensing the negative voltage of the fuel cell stack.

[0024] In addition, it has the effect of preventing fuel cell stacks from failing due to negative voltage. Attached Figure Description

[0025] Figure 1 This is a block diagram of a voltage sensing system for a fuel cell stack according to a preferred embodiment of the present invention.

[0026] Figure 2 It is shown Figure 1 A diagram of the circuit structure of the voltage sensing system for a fuel cell stack.

[0027] Figure 3 This is a diagram showing the various signals of the voltage sensing system of a fuel cell stack.

[0028] Figure 4 This is a flowchart of a voltage sensing method for a fuel cell stack according to a preferred embodiment of the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 100: Voltage sensing system; 110: First switching unit; 120: Stack sensing unit; 121: Oscillation unit; 123: Comparison unit; 125: Adjustment unit; 130: Second switching unit; 140: Judgment unit; 200: Fuel cell stack. Detailed Implementation

[0031] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that when labeling the constituent elements of each drawing, the same reference numerals should be used as much as possible for the same constituent elements, even in different drawings. Furthermore, when describing the present invention, detailed descriptions of related well-known structures or functions will be omitted if it is determined that such detailed descriptions would obscure the essence of the invention. Preferred embodiments of the present invention will be described below; however, the technical spirit of the present invention is not limited or restricted by these preferred embodiments and can be modified and implemented in various forms by those skilled in the art.

[0032] Figure 1 This is a block diagram of a voltage sensing system for a fuel cell stack according to a preferred embodiment of the present invention.

[0033] Reference Figure 1 The voltage sensing system 100 of the fuel cell stack uses an oscillation circuit to generate a reference voltage, outputs a digital value based on the difference between the voltage of the fuel cell stack and the reference voltage, and senses the voltage of the fuel cell stack based on the output digital value.

[0034] The voltage sensing system 100 for a fuel cell stack may include: a first switching unit 110, a stack sensing unit 120, a second switching unit 130, and a judgment unit 140.

[0035] The first switch section 110 can connect the fuel cell stack 200 and the stack sensing section 120 according to the turn-on operation. The first switch section 110 can maintain the insulation state between the fuel cell stack 200 and the stack sensing section 120 according to the turn-off operation. The first switch section 110 can be composed of various switching devices such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and transistors.

[0036] The stack sensing unit 120 can sense the state of the fuel cell stack 200. The stack sensing unit 120 can be disposed in the insulating block. The stack sensing unit 120 may include an oscillation unit 121, a comparison unit 123, and an adjustment unit 125.

[0037] The oscillation unit 121, in order to measure the voltage of the fuel cell stack 200, can output a reference voltage that is input to the comparator unit 123. The output waveform of the reference voltage can be in the form of a sine wave or a triangular wave. The oscillation unit 121 can input the reference voltage generated based on the (+) voltage and (-) voltage of the power supply divided in the insulating block to the comparator unit 123.

[0038] The comparator 123 uses the reference voltage output from the oscillation unit 121 as a reference comparison voltage. The comparator 123 can compare the voltage of the fuel cell stack 200 with the reference comparison voltage. The comparator 123 outputs a high-level or low-level comparison result based on the difference between the voltage of the fuel cell stack 200 and the reference comparison voltage.

[0039] The adjustment unit 125 can convert the comparison result of the comparison unit 123 into a voltage level recognizable by a low-voltage system. The output voltage output by the adjustment unit 125 can be a value that adjusts the voltage level relative to the comparison result.

[0040] The second switch unit 130 can maintain the insulation state between the stack sensing unit 120 and the low-voltage system. The second switch unit 150 can perform the function of connecting the stack sensing unit 120 and the low-voltage system judgment unit 140.

[0041] The determination unit 140 can determine whether a negative voltage has been generated in the fuel cell stack 200 based on the output voltage of the stack sensing unit 120. When the duty cycle of the output voltage is less than the reference duty cycle, the determination unit 140 can determine that a negative voltage has been generated in the fuel cell stack 200. Here, the reference duty cycle can be set based on grounding.

[0042] Figure 2 It is shown Figure 1 A diagram of the circuit structure of the voltage sensing system for a fuel cell stack.

[0043] Reference Figure 2 The first switch unit 110 may include a first switch sw1 and a second switch sw2.

[0044] The first switch sw1 can be set between the positive voltage terminal of the cell in the fuel cell stack 200 and the input terminal IN of the comparator 123. When it is necessary to sense the voltage of the fuel cell stack 200, the first switch sw1 can be turned on.

[0045] The second switch sw2 can be positioned between the negative voltage terminal of the fuel cell in the fuel cell stack 200 and ground. When it is necessary to sense the voltage of the fuel cell stack 200, the second switch sw2 can be activated.

[0046] The oscillation unit 121 can be composed of RC or LC oscillators, including operational amplifiers (OP-AMPs), and crystal oscillators. The oscillation unit 121 is not limited to the above example, and various oscillation circuits can be used.

[0047] The comparator 123 may have a reference input terminal REF for inputting the reference voltage of the oscillation unit 121 and a stack input terminal IN for inputting the input voltage of the fuel cell stack 200 that has passed through the first switch sw1.

[0048] The comparator 123 can output a high or low level comparison result based on the difference between the reference voltage and the input voltage. The comparison result can have a voltage range from a negative voltage source (-VDD / 2) to a positive voltage source (VDD / 2).

[0049] The adjustment unit 125 may include multiple resistors R1, R2, R3 and a MOSFET. The first resistor R1 may be connected between the output terminal of the comparator 123 and the gate terminal of the MOSFET. The second resistor R2 may be connected between the positive voltage source VDD and the drain terminal of the MOSFET. The third resistor R3 may be connected between the gate terminal of the MOSFET and ground.

[0050] MOSFETs can be replaced by various other switching devices such as transistors.

[0051] The adjustment unit 125 configured as described above can reduce the voltage level of the comparison result from the comparison unit 123 to 0 to VDD. The adjustment unit 125 can transmit the voltage-adjusted output voltage to the judgment unit 140. The output voltage of the adjustment unit 125 can be reversed according to the circuit structure.

[0052] The second switching unit 130 may include a third switch sw3 disposed between the drain terminal of the MOSFET and the judgment unit 140. When it is necessary to sense the voltage of the fuel cell stack 200, the third switch sw3 can be turned on.

[0053] The aforementioned first switch sw1, second switch sw2 and third switch sw3 can be switching devices such as photoMOS relays or photocouplers used for insulation purposes.

[0054] Figure 3 This is a diagram showing the various signals of the voltage sensing system of a fuel cell stack.

[0055] Reference Figure 3 The reference voltage is the output voltage of the oscillator 121, and it can exhibit a waveform with a predetermined period depending on the reference duty cycle. The reference voltage exhibits a waveform similar to a triangular waveform.

[0056] The input voltage is the voltage input to the fuel cell stack 200 of the first switching section 110.

[0057] To determine whether a negative voltage is generated in the fuel cell stack 200, a reference duty cycle can be set based on grounding. Here, the reference duty cycle can be set to approximately 50%.

[0058] The comparison result is the output voltage of the comparator 123 based on the difference between the reference voltage and the input voltage. When the comparison result input voltage is greater than the reference voltage, it has a high level. When the comparison result input voltage is less than the reference voltage, it has a low level.

[0059] The output voltage is the output value of the stack sensing unit 120. The output voltage can be a value that adjusts the voltage level relative to the comparison result. The output voltage is input to the judgment unit 140 through the second switching unit 130. The output voltage can be a state where a negative voltage is generated when the duty cycle is less than the reference duty cycle.

[0060] Figure 4 This is a flowchart of a voltage sensing method for a fuel cell stack according to a preferred embodiment of the present invention.

[0061] Reference Figure 1 and Figure 4 The voltage sensing method for a fuel cell stack according to a preferred embodiment of the present invention includes: an oscillation step (S410), an input step (S420), a comparison step (S430), an adjustment step (S440), and a judgment step (S450).

[0062] In the oscillation step (S410), the oscillation unit 121 can output a reference voltage based on a positive voltage source and a negative voltage source. The oscillation unit 121 can further consider outputting a reference voltage based on a grounded reference duty cycle.

[0063] In the input step (S420), the comparison unit 123 can receive the voltage of the fuel cell stack 200. At this time, the first switch unit 110 is in the ON state.

[0064] In the comparison step (S430), the comparison unit 123 compares the received input voltage with a reference voltage. When the input voltage is greater than the reference voltage, the comparison unit 123 can output a high-level comparison result. When the input voltage is less than the reference voltage, the comparison unit 123 can output a low-level comparison result.

[0065] In the adjustment step (S440), the adjustment unit 125 can adjust the voltage level of the comparison result of the comparison unit 123. The adjusted voltage level comparison result can be used in low-voltage systems.

[0066] In the determination step (S450), the determination unit 140 determines whether a negative voltage has been generated in the fuel cell stack 200 based on the comparison result after voltage adjustment and the reference duty cycle used to generate the reference voltage. When the duty cycle of the comparison result after voltage adjustment is less than the reference duty cycle, the determination unit 140 can determine that a negative voltage has been generated in the fuel cell stack 200.

[0067] The above description is merely illustrative of the technical concept of the present invention. Those skilled in the art can make various modifications, variations, and substitutions without departing from the essential characteristics of the invention. Therefore, the embodiments and accompanying drawings disclosed in this invention are not intended to limit the technical concept of the invention, but rather to illustrate it. The scope of the technical concept of the invention is not limited to such embodiments and drawings.

[0068] As will be understood by those skilled in the art, the steps and / or operations according to the invention may be performed simultaneously in other embodiments in other orders, or in parallel, or for other specific times (epochs).

[0069] According to embodiments, some or all of the steps and / or operations may be completed or executed using instructions, programs, interactive data structures, driver clients, and / or servers stored on one or more non-transitory computer-readable media. One or more non-transitory computer-readable media, as an example, may be software, firmware, hardware, and / or any combination thereof. Furthermore, the functionality of the "modules" discussed herein may be constituted by software, firmware, hardware, and / or any combination thereof.

Claims

1. A voltage sensing system for a fuel cell stack, characterized by, include: The stack sensing unit compares the input voltage with a reference voltage when the voltage of the fuel cell stack is input, and outputs the comparison result. as well as The determination unit determines whether a negative voltage is generated in the fuel cell stack based on the output voltage of the stack sensing unit and the reference duty cycle used to generate the reference voltage. When the duty cycle of the output voltage is less than the reference duty cycle, the determination unit determines that a negative voltage has been generated in the fuel cell stack.

2. The voltage sensing system for a fuel cell stack according to claim 1, characterized in that, The stack sensing unit includes: The oscillation section outputs the reference voltage considering the reference duty cycle; A comparator unit is used to compare the reference voltage and the input voltage; and The adjustment unit adjusts the voltage level based on the comparison result from the comparison unit.

3. The voltage sensing system for a fuel cell stack according to claim 2, characterized in that, The oscillation unit generates the reference voltage based on a positive voltage source and a negative voltage source.

4. The voltage sensing system for a fuel cell stack according to claim 3, characterized in that, The oscillation unit generates the reference voltage in the form of a triangular wave or a sine wave with a predetermined period according to the reference duty cycle.

5. The voltage sensing system for a fuel cell stack according to claim 2, characterized in that, When the input voltage is greater than the reference voltage, the comparator outputs a high-level comparison result. When the input voltage is less than the reference voltage, the comparator outputs a low-level comparison result.

6. A method of sensing voltage of a fuel cell stack, characterized by, include: Enter the steps, including the voltage of the fuel cell stack; The comparison step compares the input voltage with a reference voltage; as well as The determination step, based on the comparison result of the comparison step and the reference duty cycle used to generate the reference voltage, determines whether a negative voltage is generated in the fuel cell stack. In the judgment step, if the duty cycle of the comparison result is less than the reference duty cycle, it is determined that a negative voltage has been generated in the fuel cell stack.

7. The voltage sensing method for a fuel cell stack according to claim 6, characterized in that, Prior to the input step, there is also an oscillation step that takes into account the positive voltage source, the negative voltage source, and the reference duty cycle to output the reference voltage.

8. The voltage sensing method for a fuel cell stack according to claim 6, characterized in that, In the comparison step, when the input voltage is greater than the reference voltage, a high-level comparison result is output; when the input voltage is less than the reference voltage, a low-level comparison result is output.

9. The method of sensing the voltage of a fuel cell stack according to claim 6, wherein It also includes an adjustment step for adjusting the voltage level of the comparison result.

Images