Process for operation of a PEM fuel cell unit

• US 6,110,611 A
• Filed: 04/01/1999
• Issued: 08/29/2000
• Est. Priority Date: 10/02/1996
• Status: Expired due to Term

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Keim, Martin, Stenger, Herbert, Stuhler, Walter
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US09/283,904
• Time in Patent Office: 516 Days
• Field of Search: 429/13, 429/22, 429/23
• US Class Current: 429/431
• CPC Class Codes: B60L 58/30 for monitoring or controlling fuel cells
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A process for operating a PEM fuel cell unit containing at least one PEM fuel cell block and a speed-controlled compressor connected upstream. To control changing an electrical current I of the PEM fuel cell block to a new reference value I_SN, a speed n of the compressor is set in a first step to a maximum value n_M and in a second step is reduced to a speed n_SN corresponding to the new reference value I_SN. By this expedient improved dynamics for brief and rapid load changes are achieved.

Claims

1. An improved process for operating a polymer electrolyte membrane (PEM) fuel cell unit with at least one PEM fuel cell block and a speed-controlled compressor connected upstream of the at least one PEM fuel cell block, the improvement which comprises:

controlling a change of an electrical current of the PEM fuel cell block from a value I to a new larger reference value I_SN in a first step by setting a speed n of the speed-controlled compressor to a stipulated maximum value n_M in the first step, the stipulated maximum value n_M of the speed n being greater than a value n_SN of the speed n corresponding to the new larger reference value I_SN of the electrical current; and

reducing the speed n of the speed-controlled compressor in a second step to the value n_SN of the speed corresponding to the new larger reference value I_SN.

2. The process according to claim 1, which comprises recording continuously the electrical current of the at least one PEM fuel cell block as a control quantity with a current actual value sensing and recording device.

3. The process according to claim 2, which comprises stipulating the new larger reference value I_SN of the electrical current of the at least one PEM fuel cell block as a reference quantity by a set-point adjuster.

4. The process according to claim 3, which comprises comparing continuously the electrical current as the control quantity with the new larger reference value I_SN of the electrical current I as the reference quantity.

5. The process according to claim 4, which comprises influencing the electrical current of the at least one PEM fuel cell block in dependence on the speed n of the speed-controlled compressor.

6. The process according to claim 1, which comprises setting an air valve connected downstream of the at least one PEM fuel cell block so that, at the stipulated maximum speed nm of the speed-controlled compressor and at a maximum electrical current Imax of the at least one PEM fuel cell block, a volumetric air flow rate through the at least one PEM fuel cell block corresponds to a stipulated air ratio λ

.