Ecu With Three Crowns

I can only guess:
This is the last Ecu type minted under Louis XIV. He was king of France and Navarra. He managed to secure the Spanish crown for one of his relatives (of the Bourbon family). Under his reign, much of the Spanish Netherlands was conquered by the french (Artois, Burgundy, Lorraine...). The Dukes of Burgundy had been powerful and rivalling with the french kings centuries before. So the three crowns should symbolize uniting the power of three differnt monarchs (be it Kings or Dukes).