1. Field of the Invention
The invention is directed to a power conversion technique and more particularly to an inverter and an over current protection method thereof.
2. Description of Related Art
In order to protect the operational stability of the entire circuit, a designer of an inverter generally adds an over current protection circuit into the inverter. In this way, a corresponding over current protection mechanism will be enabled to protect the entire circuit form being damaged when a large current flows through a circuit of the inverter.
The prior art of the over current protection circuit typically performs a current sampling operation at an output side of the inverter so as to determine whether an over current occurs in the inverter according to the sampled current. Due to the output of the inverter commonly includes DC current, in the conventional over current protection circuit, a Hall sensor is typically required and serves as a current sampling circuit. Nevertheless, the Hall sensor has defects of high latency and high loss, which leads the over current protection circuit incapable of enabling the over current protection mechanism immediately when the over current occurs in the inverter.
Moreover, the output side of the inverter is commonly connected with a filter circuit composed of a capacitor and an inductor. In such configuration, an AC output voltage of the inverter will have a serious inverse drop at the instant of the inverter being connected to a pure capacitive load. As a results, the inverter will generate a larger surge current and the current flows through the inductor will increase significantly (e.g., hundreds of amperes) within a short period (e.g., in a few microseconds). Accordingly, the conventional over current protection circuit can not effectively perform over current protection to improve the aforementioned situation.