Method for generating injection current for fuel cell stack and apparatus for performing the same
An apparatus for generating injection current for a fuel cell stack includes a first converter configured to convert direct current of a voltage corresponding to a battery for a vehicle, into direct current of a predetermined voltage; a second converter configured to convert the converted direct current into alternating current; a filter configured to filter a signal of a predetermined frequency band from the converted alternating current; and a control unit configured to perform a feedback control to allow the filtered alternating current to be injected without being distorted when injecting the filtered alternating current into the fuel cell stack.
1. An apparatus for generating an injection alternating current for a fuel cell stack, comprising:
a first converter configured to convert direct current of a voltage corresponding to a battery for a vehicle, into direct current of a predetermined voltage, wherein the voltage corresponding to the battery for the vehicle is lower than a voltage of the fuel cell stack;
a second converter connected to the first converter and configured to convert the direct current output from the first converter into alternating current;
a filter connected to the second converter and configured to filter a signal of a predetermined frequency band from the alternating current output from the second converter to generate a filtered alternating current; and
a control unit connected to the fuel cell stack and the filter and configured to perform a feedback control according to difference between an actual alternating current of the fuel cell stack and the injection alternating current to allow the filtered alternating current output from the filter to be injected into the fuel cell stack without being distorted when injecting the filtered alternating current.
2. The apparatus according to claim 1 , further comprising:
a current sensor connected to the control unit and the filter and configured to sense and provide the filtered alternating current to the control unit to form the actual alternating current, wherein the filtered alternating current sensed by the current sensor is injected into the fuel cell stack to form the injection alternating current.
3. The apparatus according to claim 2 , wherein the control unit checks a difference between the actual alternating current received from the current sensor and the injection alternating current injected into the fuel cell stack.
4. The apparatus according to claim 3 , wherein the control unit controls an amplitude of the alternating current when the difference occurs between the actual alternating current and the injection alternating current as a result of checking.
5. The apparatus according to claim 4 , wherein the control unit increases the amplitude of the alternating current when a value of the actual alternating current is smaller than a value of the injection alternating current.
6. The apparatus according to claim 4 , wherein the control unit decreases the amplitude of the alternating current when a value of the actual alternating current is larger than a value of the injection alternating current.
7. The apparatus according to claim 1 , wherein the first converter boosts the direct current of the voltage corresponding to the battery for a vehicle, and converts the direct current to the direct current of the predetermined voltage.
8. The apparatus according to claim 1 , wherein the second converter converts the direct current into the alternating current by controlling a pulse width of the converted direct current.
9. The apparatus according to claim 1 , wherein the filter generates the alternating current in the form of a sine wave, by passing a region of the converted alternating current corresponding to a low frequency and blocking a region of the converted alternating current corresponding to a high frequency.