Follow [steps][1]:
- Download: http://www.microsoft.com/en-us/download/details.aspx?id=42497
- Open Powershell as administrator and run
Import-Module 'C:\Program Files\Microsoft Virtual Machine Converter\MvmcCmdlet.psd1'
- And after
ConvertTo-MvmcVirtualHardDisk -SourceLiteralPath d:\scratch\vmx\VM-disk1.vmdk -VhdType DynamicHardDisk -VhdFormat vhdx -destination c:\vm-disk1