Online Identification Technology of DC-Link Capacitor Parameters Based on Ripple

The DC-link capacitor is the core component of the converter, responsible for balancing the power on both AC and DC sides, absorbing overvoltage, and reducing output voltage ripple. Generally, the larger the capacitance value, the smaller the output voltage ripple. Once the capacitance is damaged, it can cause the rectifier to collapse. The commonly used pulse width modulation strategy for inverters is SVPWM. Based on the three-phase rectifier circuit under the SVPWM strategy, this paper derives the relationship between capacitance and ripple voltage, and verifies it through simulation. Due to the fluctuation frequency of the ripple voltage caused by SVPWM being twice the switching frequency, this paper proposes a new method based on the capacitance calculation formula—using neural network method to establish a correlation model between the second harmonic of the voltage switch and the capacitance value, in order to achieve the purpose of calculating the capacitance value.