Overcurrent protection device and method for inverter as well as inverter

Abstract

The embodiment of the invention provides an overcurrent protection device and method for an inverter as well as the inverter, which relate to the electrical and electronic field. The overcurrent protection device and method as well as the inverter are invented for efficiently improving overcurrent protection for the inverter at lower cost. The inverter comprises a power alternating circuit, a filtering circuit and the overcurrent protection device, and a change on output voltage of the filtering circuit exceeds the change on inductance current of the filtering circuit; and the overcurrent protection device comprises the following of: a voltage sampling unit which is used for sampling output voltage of the filtering circuit; a voltage comparison unit which is used for comparing the sampling output voltage sampled by the voltage sampling unit with preset voltage; and a current-limiting unit which is used for limiting current for the power alternating circuit when output voltage of the filtering circuit is reversed with theoretical output voltage and an absolute value of output voltage of the filtering circuit is larger than that of preset voltage. The overcurrent protection device and method for inverter as well as the inverter can be applied in a contravariant power supply.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to an overcurrent protection device and method of an inverter, and an inverter. Background technique [0002] The inverter is a device that converts direct current into alternating current. Generally, the principle of PWM (Pulse Width Modulation) is used to control the on or off of the semiconductor power switch, and then control the on or off of the output circuit and the DC circuit. After the output circuit is filtered by the filter circuit, the alternating current of the predetermined frequency can be obtained. [0003] Among them, the filter circuit is usually composed of filter capacitors and filter inductors. The load, especially the pure capacitive load, causes the output voltage to drop seriously at the moment of being connected to the inverter circuit, thus causing the circuit to generate a large surge current. In a short period of time (such as a few microsecond...

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Problems solved by technology

However, in the above process, since the current sampling and current comparison operations take a certain amount of time, there is a large delay between the moment when the inductor current sampling value is greater than the reference current value and the moment when the power switch tube is successfully turned off. In this way, Before the power switch tube is turned off, the actual inductor current will be much greater than the reference current value, which may still cause damage to the power switch tube

Therefore, the overcurrent protection effect of the inverter in the prior art is not ideal, and the reliability is not high

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