ImportExcel/ExportedCommands/ConvertFrom-ExcelSheet.ps1

function ConvertFrom-ExcelSheet {
    [CmdletBinding()]
    param
    (
        [Alias("FullName")]
        [Parameter(Mandatory = $true)]
        [String]
        $Path,
        [String]
        $OutputPath = '.\',
        [String]
        $SheetName = "*",
        [ValidateSet('ASCII', 'BigEndianUniCode', 'Default', 'OEM', 'UniCode', 'UTF32', 'UTF7', 'UTF8')]
        [string]
        $Encoding = 'UTF8',
        [ValidateSet('.txt', '.log', '.csv')]
        [string]
        $Extension = '.csv',
        [ValidateSet(';', ',')]
        [string]
        $Delimiter = ';'
    )

    $Path = (Resolve-Path $Path).Path
    $Stream = New-Object -TypeName System.IO.FileStream -ArgumentList $Path, "Open", "Read", "ReadWrite"
    $xl = New-Object -TypeName OfficeOpenXml.ExcelPackage -ArgumentList $Stream
    $workbook = $xl.Workbook

    $targetSheets = $workbook.Worksheets | Where-Object { $_.Name -like $SheetName }

    $params = @{ } + $PSBoundParameters
    $params.Remove("OutputPath")
    $params.Remove("SheetName")
    $params.Remove('Extension')
    $params.NoTypeInformation = $true

    Foreach ($sheet in $targetSheets) {
        Write-Verbose "Exporting sheet: $($sheet.Name)"

        $params.Path = "$OutputPath\$($Sheet.Name)$Extension"

        Import-Excel $Path -Sheet $($sheet.Name) | Export-Csv @params
    }

    $Stream.Close()
    $Stream.Dispose()
    $xl.Dispose()
}