Method for detecting faults of heating switch circuit

Abstract

The invention discloses a method for detecting faults of a heating switch circuit. The method includes: power on, namely controlling upper bridges and lower bridges to be disconnected; current detecting; namely if the current is not zero, judging that the upper bridges are damaged, judging short circuit of the upper bridges and the lower bridges by detecting currents of the lower bridges, or otherwise controlling the upper bridges to be disconnected while the lower bridges to connected; current detecting, namely, if the current is not zero, judging that the short circuit of the upper bridges is damaged, judging fault of the upper bridges and the lower bridges by detecting the current of the lower bridge, or otherwise, controlling the upper bridge and the lower bridge to be connected; current detecting, namely, if the current is zero, judging open-circuit fault of the upper bridges or open-circuit fault of all the lower bridges, or otherwise, judging the upper bridges to be normal, and judging open-circuit or short-circuit fault of the lower bridges by detecting the current of the lower bridges. When one switching tube fails and in short circuit and a heating element corresponding to the branch can still operate normally, the fault of switches can be detected and replaced through the fault detecting method.

Description

technical field [0001] The invention relates to an air heating device used in automobiles, in particular to a detection method for a heating switch circuit fault. Background technique [0002] The prior art heating switch circuit such as figure 1 As shown, the heating switch circuit is formed by connecting switch tubes Q1, Q2, Q3, Q4, Q5, Q6, heating elements A, B, C, and resistors R1, R2, R3. The heating switch circuit has three heating elements, and can also have two heating elements in the actual application process. When working, the G poles of the switch tubes are controlled by the control chip to control the operation of the switch tubes Q1, Q2, Q3, Q4, Q5, and Q6, and then control the working states of the heating elements A, B, and C. The heating switch circuit with the above structure has the following disadvantages: when one switch tube fails and short-circuits, since there is another switch tube connected in series in the same branch, the heating element corresp...

AI Technical Summary

Problems solved by technology

The heating switch circuit with the above structure has the following disadvantages: when a switch tube fails and short-circuits, since there is another switch tube connected in series in the same branch, the heating element corresponding to the branch can still be controlled.

More importantly, since the failure of the above-mentioned switch tube cannot be detected independently, when another switch tube in series is damaged, the heating switch circuit may lose control and may continue to work, which will not only lead to waste of electric energy, but also cause safety accidents

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