无法从Angularjs组件访问Popover模板上的变量

angular.module('myApp').component('myComponent', {
  controller: function() {
    var ctrl = this;
    ctrl.myVariable = 'Hello World';
  },
  template: '<button ng-click="$ctrl.openPopover()">Open Popover</button>',
  bindings: {
    // 组件的绑定属性
  }
});

<div>
  <input type="text" ng-model="$ctrl.myVariable">
  <button ng-click="$ctrl.closePopover()">Close Popover</button>
</div>