Capacity detection circuit for DC bus capacitor of photovoltaic inverter

Abstract

The invention provides a capacity detection circuit for the DC bus capacitor of a photovoltaic inverter. The capacity detection circuit comprises a power supply circuit (102), a voltage sampling circuit (104), a comparator circuit (105), a micro-controller (106) and a communication circuit (107). The input end of the voltage sampling circuit (104) is connected with the positive and negative electrodes of the DC bus capacitor of the photovoltaic inverter. The output end of the voltage sampling circuit (104) is connected with the input end of the comparator circuit (105). The output end of the comparator circuit (105) is connected with the input end of the micro-controller (107). The output end of the micro-controller (107) is connected with a relay switch (109) and the communication circuit (107). The power supply circuit (102) is connected with the power supply ports of all the above parts. When the DC bus capacitor of the photovoltaic inverter is connected with a discharge resistor to realize the discharge process, the change of the voltage at the two ends of the capacitor is detected by the voltage sampling circuit. After the high-low level conversion treatment of the comparator circuit, the corresponding change value of the voltage is calculated by the microcontroller. Meanwhile, the reduction time of the fixed voltage range is calculated, and then the performance of the capacitor is evaluated.

Description

technical field [0001] The invention relates to a detection circuit of a photovoltaic inverter DC bus capacitance. Background technique [0002] The operating life of photovoltaic grid-connected inverters is the key to ensuring the long-term reliability of photovoltaic power plants. Grid-connected inverter life is usually affected by the life of its internal key components. Among them, the DC bus capacitance of the photovoltaic inverter is an important factor affecting the life of the inverter. Timely access to predictive information before the end of capacitor life is key to ensuring reliable operation of the inverter. Because there is a corresponding relationship between capacitance and life, the prediction of life is usually realized by monitoring the change of capacitance. [0003] Some domestic inverter manufacturers have corresponding photovoltaic inverter DC bus capacitor discharge circuits, but there is no independent circuit to detect the bus capacitor capacity t...

AI Technical Summary

Problems solved by technology

[0003] Some domestic inverter manufacturers have corresponding photovoltaic inverter DC bus capacitor discharge circuits, but there is no independent circuit to detect the bus capacitor capacity through capacitor discharge time

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