public static void ConvertToCSV(string fileToConvertPath, string convertedFilePath = null)
        {
            System.Text.Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance); // Nécessaire pour la prise en charge de certains types d'encodage de fichier.

            FileStream fileToConvertStream = File.Open(fileToConvertPath, FileMode.Open, FileAccess.Read, FileShare.None);
            IExcelDataReader excelReader = ExcelReaderFactory.CreateReader(fileToConvertStream);
            DataSet xlsData = excelReader.AsDataSet();
            excelReader.Close();

            string csvData = "";
            for (int row = 0; row < xlsData.Tables[0].Rows.Count; row++)
            {
                for (int column = 0; column < xlsData.Tables[0].Columns.Count; column++)
                    csvData += xlsData.Tables[0].Rows[row][column].ToString() + ";";
                csvData += "\n";
            }

            StreamWriter convertedDataStream = new StreamWriter(
                string.IsNullOrWhiteSpace(convertedFilePath)
                    ? Path.GetDirectoryName(fileToConvertPath) + "\\" + Path.GetFileNameWithoutExtension(fileToConvertPath) + ".csv"
                    : convertedFilePath,
                false,
                Encoding.UTF8
            );
            convertedDataStream.Write(csvData);
            convertedDataStream.Close();
        }