SharePoint: Function to Add SiteAdmin

Function fAddSiteAdmin($SPWeb,$SPUser,$DisplayName)
{
Try
{
New-SPUser -UserAlias $SPUser -DisplayName $DisplayName -Web $SPWeb -ErrorAction SilentlyContinue | out-null
$usr = Get-SPUser $SPUser -Web $SPWeb -ErrorAction SilentlyContinue
$usr.IsSiteAdmin = $true
$usr.Update()
}
Catch {}
}