By Guy Taylor Advanced Energy Industries has upped the stakes in its bid for the electronic component supplier XP Power after three prior offers were shunned. The Nasdaq-listed firm’s latest offer values Singapore-based XP Power, which holds a listing on London’s Main Market, at £571m. It had previously put forward three bids worth £339mm, £369m and £468m in October, November and early May, respectively. The latest offer, at a price of £19.50 per share, represents a 68 per cent premium to XP Power’s closing share price of £11.64 on May 20 and an 82 per cent premium on its 30-trading day averag…