How to trigger change() in a angular form by a custom control without an input

Thanks for your replies.

Finally I found the following solution to this problem: As Claies mentioned in the comment, my custom component does not fire the change event. Therfore the form does never know about the change. This has nothing todo with angular, but as said is the expected behaviour of a input/form.

The easiest solution is to fire the change-event in the customcontrol when a change happens:

constructor(private element: ElementRef, private renderer: Renderer) {
}

public triggerChanged(){
    let event = new CustomEvent('change', {bubbles: true});
    this.renderer.invokeElementMethod(this.element.nativeElement, 'dispatchEvent', [event]);
}

That's it, whenever I called "onControlChange(..)" in my custom component, then I fire this event afterward.

Be aware, that you need the Custom-Event-Polyfill to support IE! https://www.npmjs.com/package/custom-event-polyfill