Inverter inverter igbt short circuit detection and protection system based on differential circuit

Abstract

A kind of frequency converter inverter IGBT short-circuit detection and protection system based on the differential circuit provided by the present invention includes: a detection device, a signal conditioning circuit, a first signal judging circuit, a second signal judging circuit, or an arithmetic circuit and a processing circuit; The signal judging circuit and the second judging circuit output a fault signal to the OR computing circuit, or the computing circuit judges that any one of the first signal judging circuit and the second signal judging circuit has a fault signal output, then outputs a fault determination signal to the processing circuit, and the processing The circuit receives or calculates the fault determination signal output by the circuit and outputs a shutdown control signal to shut down the IGBT inverter bridge of the frequency converter, which can quickly and accurately detect the short-circuit fault of the IGBT of the frequency converter, greatly shortening the fault output time, so that it can be quickly and effectively Implement IGBT over-current protection, thereby effectively preventing IGBT from burning out and affecting the service life of the entire inverter, and without increasing the heat capacity of IGBT, ensuring that the inverter has high thermal 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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