Export Excel Worksheet to CSV

ConvertTo-CsvFromExcelWorksheet.ps1

function ConvertTo-CsvFromExcelWorksheet
{
    [cmdletbinding()]
    param
    (
        [Parameter(Mandatory=$true)][string]$ExcelFilePath,
        [Parameter(Mandatory=$true)][string]$CsvFilePath,
        [Parameter(Mandatory=$false)][string]$Worksheet = "Sheet1"
    )

    begin
    {
        $xlCSV = 6
        $ExcelApplication = New-Object -ComObject Excel.Application
    }
    process
    {
        if( $ExcelApplication )
        {
            $ExcelApplication.Visible       = $false
            $ExcelApplication.DisplayAlerts = $false

            $workbook = $ExcelApplication.Workbooks.Open($ExcelFilePath)

            try
            {
                $workbook.Worksheets($Worksheet).SaveAs( $CsvFilePath, $xlCSV )
            }
            catch
            {
                Write-Error "Failed to save worksheet '$Worksheet'. Error: $($_.Exception)"
            }
        }
        else
        {
            Write-Error -Message "Microsoft Excel could not be opened, please make sure that Microsoft Excel is installed on the local machine."
        }
    }
    end
    {
        if( $ExcelApplication )
        {
            $ExcelApplication.Quit()
        }
    }
}

ConvertTo-CsvFromExcelWorksheet -ExcelFilePath "C:\_temp\Excel.xlsx" -CsvFilePath "C:\_temp\data.csv"

ConvertTo-CsvFromExcelWorksheet -ExcelFilePath "C:\_temp\Excel.xlsx" -CsvFilePath "C:\_temp\data.csv" -Sheet "Sheet1"