President Barack Obama’s likely nomination of three Federal Reserve governors will help Chairman Ben S. Bernanke plan an exit from record monetary stimulus and strengthen banking supervision and consumer protection. Janet Yellen, an economist who heads the Fed Bank of San Francisco, is Obama’s choice for central bank vice chairman in Washington. The administration has also approached Sarah Bloom Raskin, Maryland’s commissioner of financial regulation, and Peter Diamond, an economics professor at the Massachusetts Institute of Technology, to fill two vacancies on the Board of Governors. The appointments would complete the Federal Reserve’s seven-member board for the first time since April 2006. Yellen, former chief economist under President Bill Clinton, and Diamond could help Bernanke determine when to raise interest rates from record lows, while Raskin brings expertise in regulatory issues. “Does Bernanke need help in navigating the exit strategy? He sure does,” said former Fed Governor Lyle Gramley, senior economic adviser at Potomac Research Group in Washington. “The board has a lot of work to do in a variety of areas, even under normal circumstances.”