| 摘要 |
When current flowing through all electrical terminals of an alternating-current electric motor (21) is near zero, an operation is performed to set the electrical terminals of the alternating-current electric motor (21) in an open state, or to set the electrical terminals to a state allowing conduction via a reflux diode inside an inverter (11). Here, as the operation for setting the current flowing through all electrical terminals near zero, all of the switching elements of the upper and lower arms of the inverter (11) are set to on, causing a short circuit of the electrical terminals. In this manner, when operation of the inverter (11) is stopped, electromagnetic energy having a reactance component, such as from the alternating-current electric motor (21) or the like, is prevented or inhibited from flowing from the alternating-current electric motor (21) to the inverter (11) side. As a result, the occurrence of excess voltage or excess current is prevented and the power source is protected for the inverter (11), the main capacitor (50), and the like, and the safety of the alternating-current electrical device system is increased. |
