Hi Partner,
It's true you can move to HR from sales, though you may have to start from the basics. With the sales experience in place, you could opt for a business line HR position focusing mainly on areas such as performance management, counselling and grievance handling as well as exit interviews. The rest would be the general HR basics.
Another option for you in HR would be recruitment, especially with focus on sales positions. The money in the short term is good, though the work would be hectic if you have to recruit sales personnel on a large scale with minimal recruitment fee margins.