If the file hasn't already been saved as a PSD, the script will prompt you to do that because it relies on that path for all the exports.

Save PNG next to PSD (Incremental numbers)

#target photoshop

var savePSD    = false; // If set true the psd document is saved every time the script runs...
var folderName = ' (Frames)';

try {

  var doc   = app.activeDocument;
	var fileExists = false;
	
	try { if ( savePSD ) doc.save(); } catch(e){}
	
	try {
		fileExists = doc.path;
	}
	catch(e){
		var idsave = charIDToTypeID( "save" );
		var desc50 = new ActionDescriptor();
		var idIn = charIDToTypeID( "In  " );
		desc50.putPath( idIn, new File( Folder.desktop.fullName ) );
		var idDocI = charIDToTypeID( "DocI" );
		desc50.putInteger( idDocI, 196 );
		var idsaveStage = stringIDToTypeID( "saveStage" );
		var idsaveStageType = stringIDToTypeID( "saveStageType" );
		var idsaveSucceeded = stringIDToTypeID( "saveSucceeded" );
		desc50.putEnumerated( idsaveStage, idsaveStageType, idsaveSucceeded );
		executeAction( idsave, desc50, DialogModes.ALL );
		fileExists = doc.path;
	}
	
	if ( fileExists ) {
		saveNewVersion( doc );
	}

}
catch( e ) {
  // remove comments below to see error for debugging
  // alert( e );
}

function saveNewVersion( doc, docName ) {

  var extension 	= '.png';
  var docName     = doc.name.substring(0, doc.name.lastIndexOf('.'));
  var docPath     = doc.path;
	
  var outputPath = docPath + '/' + doc.name + folderName;
	
  var outputFolder = new Folder( outputPath );
  if( !outputFolder.exists ) { outputFolder.create(); }
	
  var verisonsList = outputFolder.getFiles( '*' + extension );
	var versionsLength1 = verisonsList.length;
	var number = getVersionNumber( docName, verisonsList );
	
	var filename = number + extension;
	doc.exportDocument( File( outputPath + '/' + filename ), ExportType.SAVEFORWEB, exportOptions() );
  app.beep();

}

function getVersionNumber( docName, verisonsList ) {
	
	var number = 0;
	for ( var i = 0; i < verisonsList.length; i++ ) {
		
		var file = verisonsList[i];
		var fileName = File(file).displayName;
		fileName = fileName.substring(0, fileName.lastIndexOf('.'));
		
		// Start looking for the version number if PSD filename contains doc name...
		var versionNumber = fileName.match(/^[0-9]*/);
		
		if ( versionNumber ) {
			versionNumber = parseInt( versionNumber ,10);
			if ( number < versionNumber ) {
				number = versionNumber;
			}
		}
		
	}
	
	return number + 1;
	
}

function exportOptions() {
	
	var options = new ExportOptionsSaveForWeb();
	
	options.format = SaveDocumentType.PNG;
	options.quality = 100;
	
	return options;
	
}