Abstract: Disclosed herein is a method for diagnosing a fault of a fuel cell stack, the method including: applying a summed current obtained by summing first and second frequencies to the fuel cell stack; diagnosing whether or not a fault has been generated in the fuel cell stack using a higher frequency of first and second frequencies of output voltages of the fuel cell stack; and reconfirming whether or not the fault has been generated in the fuel cell stack using the first and second frequencies in the output voltage of the fuel cell stack.

Abstract: Disclosed herein is a method for diagnosing a fault of a fuel cell stack, including: applying a summed current obtained by summing currents of different frequency regions to the fuel cell stack; passing output voltages of the fuel cell stack through each of the different frequency filters to extract the respective diagnosis data; and diagnosing whether or not a fault has been generated in the fuel cell stack using the respective diagnosis data. Therefore, it is possible to further improve diagnosis analysis capability by applying the summed current obtained by summing the currents of the different frequency regions to the fuel cell stack and then rapidly diagnosing the fault of the fuel cell stack using the diagnosis data obtained by filtering the output voltages of the fuel cell stack.

Abstract: A method and an apparatus using a power transistor in a fuel cell stack diagnostic system provides an apparatus using a power transistor in a fuel cell stack diagnostic system. The apparatus includes a regenerative braking detector that detects regenerative braking of a fuel cell vehicle equipped with a fuel cell stack diagnostic system; a voltage rise determiner that determines whether a voltage rise due to regenerative braking of a fuel cell vehicle is a predetermined value or more; and a power transistor controller that controls an AC signal generator so that the voltage due to the regenerative braking is discharged by the power transistor, when the voltage rise due to regenerative braking determined by the voltage rise determiner is a predetermined value or more.

Abstract: A diagnostic system and method for a fuel cell stack that diagnoses the state and/or failure of the fuel cell stack. More specifically, the diagnostic control analyzer diagnoses and analyzes the state of the fuel cell stack by measuring the voltage and the current received from the fuel cell stack. To do this, an AC signal generator cogenerates a diagnostic AC signal according to the control upon receiving a control command form the analyzer, and an AC component driving element is then driven upon receiving the AC signal that is output from the AC signal generator in order to include a diagnostic AC component within the current of the fuel cell stack. In particular, the diagnostic control analyzer diagnoses the fuel cell stack based on a voltage and a current received from the fuel cell stack that includes the AC component via a load.

Abstract: A failure diagnosis apparatus that includes an alternating current (AC) absorption unit that is connected to the fuel cell stack and switched based on an applied AC signal to enable a current from the fuel cell stack to flow. In addition, an AC signal generator is configured to generate the AC signal and supply the generated AC signal to the AC absorption unit. As the current from the fuel cell stack is absorbed by the AC absorption unit based on an alternating signal, a stack current input into a diagnosis processing unit includes an AC component, thus the diagnosis processing unit may diagnose fuel cell stack failure by analyzing a frequency of the AC component.

Abstract: Disclosed herein is a method for generating an injected current of fuel cell stack, including: generating a synthesized frequency current in a form in which a first frequency current is synthesized with a second frequency current; and applying the synthesized frequency current to the fuel cell stack, wherein the first frequency current and the second frequency current are each used to calculate at least one of total harmonic distortion and impedance. According to the embodiment of the present invention, a hardware configuration may be reduced by applying the synthesized frequency current of the AC current for calculating the total harmonic distortion (THD) and the AC current for calculating the impedance to the fuel cell stack, without generating the AC current for calculating the total harmonic distortion (THD) and the AC current for calculating the impedance, respectively, thereby reducing a price and a size of the fuel cell stack.

Abstract: To diagnose a fault of a fuel cell stack, an alternating current having a first optimal frequency of a first frequency domain to diagnose a drop in cell voltage and an alternating current having a second optimal frequency of a second frequency domain to diagnose a cause of the drop in cell voltage are supplied to the fuel cell stack are provided. A distortion rate is then calculated based on voltage of the fuel cell stack according to the alternating current of the first optimal frequency, and the drop in cell voltage is diagnosed based on the calculated distortion rate. Also, impedance is calculated based on voltage and a current of the fuel cell stack according to the alternating current of the second optimal frequency and amount of water is calculated based on the calculated in the fuel cell stack, and the cause of the drop in cell voltage is diagnosed based on the calculated impedance and amount of water.

Abstract: A method and an apparatus using a power transistor in a fuel cell stack diagnostic system provides an apparatus using a power transistor in a fuel cell stack diagnostic system. The apparatus includes a regenerative braking detector that detects regenerative braking of a fuel cell vehicle equipped with a fuel cell stack diagnostic system; a voltage rise determiner that determines whether a voltage rise due to regenerative braking of a fuel cell vehicle is a predetermined value or more; and a power transistor controller that controls an AC signal generator so that the voltage due to the regenerative braking is discharged by the power transistor, when the voltage rise due to regenerative braking determined by the voltage rise determiner is a predetermined value or more.

Abstract: A diagnostic system and method for a fuel cell stack that diagnoses the state and/or failure of the fuel cell stack. More specifically, the diagnostic control analyzer diagnoses and analyzes the state of the fuel cell stack by measuring the voltage and the current received from the fuel cell stack. To do this, an AC signal generator cogenerates a diagnostic AC signal according to the control upon receiving a control command form the analyzer, and an AC component driving element is then driven upon receiving the AC signal that is output from the AC signal generator in order to include a diagnostic AC component within the current of the fuel cell stack. In particular, the diagnostic control analyzer diagnoses the fuel cell stack based on a voltage and a current received from the fuel cell stack that includes the AC component via a load.

Abstract: A diagnostic and heat management system for a fuel cell stack is provided herein that includes a diagnostic control analyzer that diagnoses and analyzes a state of the fuel cell stack by measuring a voltage and a current of the fuel cell stack. Also, an AC signal generator generates a diagnostic AC signal, and an AC component driving element that is included in an AC component in a current of the fuel cell stack. Additionally, a termoelement is driven as a heat absorbing device when a temperature of the AC component driving element is equal to or greater than a predetermined temperature and is driven as a heat emitting device when a temperature of the AC component driving element is less than a predetermined temperature, in order to manage heat generation in the AC component driving element.

Abstract: Provided is an apparatus and method for diagnosing a fault of a fuel cell stack based on measurement of a stack current. The apparatus includes an alternating-current (AC) generation circuit configured to apply an AC to a fuel cell stack driven by a basic operating current (direct-current: DC), a current measurement circuit configured to measure a current of the fuel cell stack caused by the DC applied to the fuel cell stack, and a Micom configured to diagnose a fault of the fuel cell stack on the basis of a current measurement result of the current measurement circuit.

Abstract: Disclosed herein is a method for generating an injected current of fuel cell stack, including: generating a synthesized frequency current in a form in which a first frequency current is synthesized with a second frequency current; and applying the synthesized frequency current to the fuel cell stack, wherein the first frequency current and the second frequency current are each used to calculate at least one of total harmonic distortion and impedance. According to the embodiment of the present invention, a hardware configuration may be reduced by applying the synthesized frequency current of the AC current for calculating the total harmonic distortion (THD) and the AC current for calculating the impedance to the fuel cell stack, without generating the AC current for calculating the total harmonic distortion (THD) and the AC current for calculating the impedance, respectively, thereby reducing a price and a size of the fuel cell stack.

Abstract: Disclosed herein is a method for diagnosing a fault of a fuel cell stack, the method including: applying a summed current obtained by summing first and second frequencies to the fuel cell stack; diagnosing whether or not a fault has been generated in the fuel cell stack using a higher frequency of first and second frequencies of output voltages of the fuel cell stack; and reconfirming whether or not the fault has been generated in the fuel cell stack using the first and second frequencies in the output voltage of the fuel cell stack.

Abstract: Disclosed herein is a method for diagnosing a fault of a fuel cell stack, including: applying a summed current obtained by summing currents of different frequency regions to the fuel cell stack; passing output voltages of the fuel cell stack through each of the different frequency filters to extract the respective diagnosis data; and diagnosing whether or not a fault has been generated in the fuel cell stack using the respective diagnosis data. Therefore, it is possible to further improve diagnosis analysis capability by applying the summed current obtained by summing the currents of the different frequency regions to the fuel cell stack and then rapidly diagnosing the fault of the fuel cell stack using the diagnosis data obtained by filtering the output voltages of the fuel cell stack.

Abstract: To diagnose a fault of a fuel cell stack, an alternating current having a first optimal frequency of a first frequency domain to diagnose a drop in cell voltage and an alternating current having a second optimal frequency of a second frequency domain to diagnose a cause of the drop in cell voltage are supplied to the fuel cell stack are provided. A distortion rate is then calculated based on voltage of the fuel cell stack according to the alternating current of the first optimal frequency, and the drop in cell voltage is diagnosed based on the calculated distortion rate. Also, impedance is calculated based on voltage and a current of the fuel cell stack according to the alternating current of the second optimal frequency and amount of water is calculated based on the calculated in the fuel cell stack, and the cause of the drop in cell voltage is diagnosed based on the calculated impedance and amount of water.

Abstract: A failure diagnosis apparatus that includes an alternating current (AC) absorption unit that is connected to the fuel cell stack and switched based on an applied AC signal to enable a current from the fuel cell stack to flow. In addition, an AC signal generator is configured to generate the AC signal and supply the generated AC signal to the AC absorption unit. As the current from the fuel cell stack is absorbed by the AC absorption unit based on an alternating signal, a stack current input into a diagnosis processing unit includes an AC component, thus the diagnosis processing unit may diagnose fuel cell stack failure by analyzing a frequency of the AC component.