param(
    [int]$Min = 5,
    [string]$ExportPath
)

$logs = (Get-WinEvent -ListLog * | Where-Object {($_.IsEnabled) -and ($_.RecordCount -gt 0)}).LogName 2>$null
$last = (Get-Date).AddMinutes(-$Min)
$allEvents = @()
foreach ($log in $logs) {
  $events = Get-WinEvent -FilterHashtable @{
    LogName   = $log
    StartTime = $last
    #1 = Critical
    #2 = Error
    #3 = Warning
    #Level     = 1,2,3	
  } -ErrorAction SilentlyContinue
  if ($events) {
    $allEvents += $events
  }
}
$result = $allEvents |
    Sort-Object TimeCreated |
    Select-Object TimeCreated, LogName, Id, LevelDisplayName, Message
if ([string]::IsNullOrWhiteSpace($ExportPath)) {
    # 引数なし：画面表示
    $result | Format-Table -AutoSize
}
else {
    # 引数あり：CSV出力
    $result | Export-Csv -Path $ExportPath -NoTypeInformation -Encoding UTF8
}