Frequency converter inversion IGBT short circuit detection protection system based on differentiating circuit

Abstract

The invention provides a frequency converter inversion IGBT short circuit detection protection system based on a differentiating circuit. The frequency converter inversion IGBT short circuit detectionprotection system comprises a detection device, a signal conditioning circuit, a first signal judgment circuit, a second signal judgment circuit, an OR operation circuit and a processing circuit, wherein the first signal judgment circuit and the second judgment circuit output fault signals to the OR operation circuit, the OR operation circuit judges whether any one of the first signal judgment circuit and the second signal judgment circuit has fault signal output, if so, a fault determination signal is outputted to the processing circuit, the processing circuit receives the fault determination signal outputted by the OR operation circuit and outputs a turn-off control signal to turn off an IGBT inverter bridge of the frequency converter, the short-circuit fault of the IGBT of the frequency converter can be rapidly and accurately detected, therefore, the IGBT overcurrent protection can be quickly and effectively executed, the service life of the whole frequency converter is effectivelyprevented from being influenced by burning loss of the IGBT, the heat capacity of the IGBT does not need to be improved, and the frequency converter is ensured to have higher heat efficiency.

Description

technical field [0001] The invention relates to a detection and protection system, in particular to a frequency converter inverter IGBT short-circuit detection and protection system. Background technique [0002] IGBT (Insulated Gate Bipolar Transistor) is an important device in the inverter bridge of the inverter. It has the characteristics of high voltage, high current, high frequency, and small on-resistance; however, IGBT also has the ability to withstand overcurrent And the ability to withstand overvoltage is poor, once overcurrent and overvoltage occur, it will be easily damaged. [0003] The short-circuit current is the most serious overcurrent of the IGBT, which may be as high as 10 times the rated current of the IGBT or even higher. Under this current, the IGBT will burn out within a few microseconds. In the prior art, in order to protect the IGBT, the capacity of the IGBT is enlarged when the frequency converter selects the IGBT. On the other hand, a current detec...

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Problems solved by technology

[0004] In the current detection, the Hall element is used to detect the instantaneous value of the current. When the detected current is greater than the set reference value, it is judged as a short-circuit fault and protection is implemented. However, the existing technical means have the following technical defects: First, increase the The capacity of the IGBT is to increase the allowable heat generation of the IGBT, thereby reducing the thermal efficiency of the inverter, so that it is necessary to increase the radiator of the inverter (especially the explosion-proof inverter), the volume and weight of the box, which is not easy to use. More importantly: the current output by the inverter bridge of the frequency converter is a sinusoidal current with variable frequency, and the current detected by the Hall element is an instantaneous value. Therefore, the current value output by the Hall element may be at the peak of the sinusoidal current The position may also be near the zero point. When the short-circuit fault occurs, the current rises rapidly with a high slope. When the short-circuit fault occurs near the zero point of the normal sine wave current, the detected current I rises from the zero point to the set value. The time will be significantly longer than the time required to rise from the peak position to the set value, resulting in a longer delay in fault determination, and failure to output fault signals in time, and this delay may cause serious heating or even burning of the IGBT

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