Refresh Excel connections using Powershell - excel

Question

I have the below code that opens a spreadsheet, deletes all connections and "Saves" a new file.
$a = New-Object -COM "Excel.Application"
$a.Visible = $false
$b = $a.Workbooks.Open("F:\Scripts\All Users.xlsx")
do
{
$b.Connections.Item(1).Delete()
$Count = $b.Connections.Count()
} until($Count -eq 0)
$b.SaveAs("F:\Scripts\Users Home Drive Search.xlsx")
$b.Close()
I would like to know two things:
How do I get the sheet to RefreshAll connections? I've tried "$b.Connections.refreshall()" but the refreshall() doesn't exist.
How do I quit Excel application? I ran "New-Object -COM "Excel.Application" | Get-Member -MemberType Methods" and I don't see a quit or exit method.

Answer 1

RefreshAll() is a method of the WorkBook object, so use that to refresh the external connections:
$b.RefreshAll()
To exit Excel and remove the used COM objects from memory, use
$a.Quit()
$null = [System.Runtime.Interopservices.Marshal]::ReleaseComObject($b)
$null = [System.Runtime.Interopservices.Marshal]::ReleaseComObject($a)
[System.GC]::Collect()
[System.GC]::WaitForPendingFinalizers()
BTW, I would use more descriptive variable names, so $excel instead of $a and $workbook instead of $b to avoid confusion later on.