A power converter for a fuel cell, the power converter comprising: - a boost converter (L 1, Q 1) connected to the fuel cell and configured to control a load voltage at a predetermined magnitude in a normal operation mode and to induce an output response by applying a predetermined perturbation current to the fuel cell in a diagnosis mode, wherein the normal operation mode is configured to supply a voltage in response to a change of a load (R load) and the diagnosis mode is configured to predict the lifespan of the fuel cell; - a digital signal processor configured to extract an impedance parameter by detecting the output response of the fuel cell in the diagnosis mode, and predict a lifespan of the fuel cell according to the impedance parameter; wherein - an auxiliary energy storage device connected between the boost converter (L 1, Q 1) and the load (R load), configured to be charged by power from the fuel cell and to discharge power from the auxiliary energy storage device to the load (R load) in addition to the power from the fuel cell; and - a bidirectional converter (Q 2, Q 3, L 2) connected to the auxiliary energy storage device, and configured to be switched so as to handle an abrupt change or a transient overload of the load (R load); wherein the bidirectional converter (Q 2, Q 3, L 2) is configured to control an output voltage of the load (R load) in order to generate a perturbation current signal for a diagnosis by the boost converter (L 1, Q 1) in the diagnosis mode; characterized in that - the boost converter (L 1, Q 1) is configured to induce the perturbation current having a constant direct current level in the diagnosis mode, and the bidirectional converter (Q 2, Q 3, L 2) is configured to be switched and to control the load voltage by charging or discharging the auxiliary energy storage device; - a boost converter (L 1, Q 1) connected to the fuel cell and configured to control a load voltage at a predetermined magnitude in a normal operation mode and to induce an output response by applying a predetermined perturbation current to the fuel cell in a diagnosis mode, wherein the normal operation mode is configured to supply a voltage in response to a change of a load (R load) and the diagnosis mode is configured to predict the lifespan of the fuel cell; - a digital signal processor configured to extract an impedance parameter by detecting the output response of the fuel cell in the diagnosis mode, and predict a lifespan of the fuel cell according to the impedance parameter; wherein - an auxiliary energy storage device connected between the boost converter (L 1, Q 1) and the load (R load), configured to be charged by power from the fuel cell and to discharge power from the auxiliary energy storage device to the load (R load) in addition to the power from the fuel cell; and - a bidirectional converter (Q 2, Q 3, L 2) connected to the auxiliary energy storage device, and configured to be switched so as to handle an abrupt change or a transient overload of the load (R load); wherein the bidirectional converter (Q 2, Q 3, L 2) is configured to control an output voltage of the load (R load) in order to generate a perturbation current signal for a diagnosis by the boost converter (L 1, Q 1) in the diagnosis mode; characterized in that - the boost converter (L 1, Q 1) is configured to induce the perturbation current having a constant direct current level in the diagnosis mode, and the bidirectional converter (Q 2, Q 3, L 2) is configured to be switched and to control the load voltage by charging or discharging the auxiliary energy storage device;