… then there could be a solution if your PC has a motherboard from Asus or Gigabyte. As the iPad does need more power than the 500 mA which a standard USB port provides, the iPad does only charge while in suspend mode if it is connected to a standard USB port and then only very slowly..
I found a software for my Asus motherboard and also for motherboards from Gigabyte which provides a solution for that. I just tried it with my PC and it really works. No experience yet if it does charge as fast as with the Apple charger but at least it charges while beeing used.