Coil protection circuit and method for electric vehicle wireless charging system

Abstract

The invention discloses a coil protection circuit and method of a wireless charging system for an electric vehicle, which includes a coil current detection circuit for obtaining the current in the coil to be detected, converting it into a DC voltage and outputting it through the first output terminal, and the second The output terminal is used to output the voltage after the DC voltage is stepped down in equal proportion; the reference voltage generation circuit is used to generate the reference voltage and input it to the comparison output circuit; the comparison output circuit is used to compare the DC voltage with the reference voltage, if the DC voltage is high If it is lower than the reference voltage, then output an alarm signal; the processor is used to periodically obtain the voltage output by the second output terminal, and adjust the reference voltage generating circuit according to the currently obtained voltage so that the difference between the generated reference voltage and the currently obtained voltage is The value is the preset voltage value. The reliability and accuracy of the alarm of the present invention are high, and compared with the prior art in some cases, the trigger time of the alarm is shorter.

Description

technical field [0001] The invention relates to the technical field of wireless charging protection, in particular to a coil protection circuit and method for a wireless charging system of an electric vehicle. Background technique [0002] Wireless power supply applications have gradually emerged, and there are more and more products that are close to the daily life of ordinary people. Because the wireless power supply is a resonance method, the voltage and current are particularly large during operation. The coil part is exposed for a long time, and the risk of damage to the short circuit is also higher. Therefore, reliable circuit protection is required. [0003] Conventional circuit protection is to set a threshold voltage. When the external short circuit of the coil or the overcurrent and overload signal voltage exceeds the set threshold voltage, the protection circuit will work, output a signal, and control the shutdown of the equipment. This solution needs the signa...

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Problems solved by technology

This solution needs the signal to exceed the preset threshold to trigger the alarm. If the preset threshold is set too high, it will take a long time from overload to alarm; in addition, in practical applications, the time for the signal to exceed the preset threshold is not Certainly, if the signal exceeds the preset threshold after a long time, it indicates that the rate of change of the signal is very slow. In this case, the coil is generally not short-circuited or overloaded, so the alarm at this time is actually a misjudgment and the reliability is low.

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