A soft-start method and system for vehicle-mounted power supply charging

Abstract

The invention discloses a soft start method and system for charging a vehicle-mounted power supply, comprising: obtaining a sampling voltage of the mains; determining the moment when the mains crosses positive and negative zero points according to the positive and negative values ​​of the sampling voltage; When the instantaneous value of the sampling voltage is less than the voltage threshold, the CLLC is driven at the highest frequency in the first power frequency cycle; after the second positive zero-crossing moment, the wave frequency is decreased and the CLLC is driven; when the wave frequency decreases Start the delay counting after reaching the resonant frequency; when the delay counting time reaches the threshold value, the soft start is completed. The present invention starts soft start when inputting low voltage and at the same time soft starts according to the sinusoidal slope of the mains voltage, without overcharge voltage, and avoids the loss of electronic devices caused by the large impact current caused by high voltage; in addition, the lower setting of the highest switching frequency improves Driver reliability and anti-interference.

Description

technical field [0001] The invention relates to the field of electronic power, in particular to a soft-start method and system for vehicle-mounted power supply charging. Background technique [0002] Slow charging is to connect alternating current (AC) directly to the electric vehicle, and then convert the alternating current into direct current through the on-board charger, and then charge the battery pack. The on-board charger is provided with a power factor correction (PFC) module and a direct current-direct current converter (DC-DC) converter. After the PFC module converts the connected alternating current into a DC bus voltage, the DC- The DC converter converts the DC target voltage into high-voltage DC to charge the battery pack. [0003] The DC-DC converter works at the resonant frequency to obtain the best efficiency. However, when starting, if it starts directly at the resonant frequency, since the resonant impedance is 0 and the filter capacitor on the output sid...

AI Technical Summary

Problems solved by technology

In the traditional CLLC topology charging circuit, the input is the DC bus voltage. When the DC bus voltage is relatively high (390Vdc-680Vdc) input, the soft-inspired wave frequency is designed to be the highest frequency at 3 times the resonance frequency. However, the higher start-up frequency It will bring the following problems: First, to realize high-frequency pulse width modulation (Pulse Width Modulation, PWM), the requirements for the reliability and anti-interference of the drive circuit are high, which increases the cost; second, the time from the starting frequency to the resonance frequency longer, resulting in longer start-up times

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