Thin-film capacitor in three-phase alternating-current motor driving system

Abstract

The invention discloses a thin-film capacitor in a three-phase alternating-current motor driving system. The thin-film capacitor comprises capacitor cores, a first positive busbar, a second positive busbar, a first negative busbar, a second negative busbar, pouring sealant, a shell and insulating paper. The capacitor cores are arranged in rows, and the first positive busbar and the second negativebusbar are arranged on the top surfaces of the capacitor cores at intervals; the first negative busbar and the second positive busbar are arranged on the bottom surface of the capacitor core at intervals, metal spraying electrodes on the top surfaces of the capacitor cores are respectively connected with the first positive busbar or the second negative busbar, and the metal spraying electrodes onthe bottom surface of the capacitor cores are connected to the first negative busbar or the second positive busbar. Insulation paper is respectively arranged between the first positive busbar and thesecond negative busbar and between the first negative busbar and the second positive busbar, the first positive busbar and the second positive busbar are connected with each other, and the first negative busbar and the second negative busbar are connected with each other. The thin-film capacitor reduces stray inductance at the busbars and capacitor core metal spraying electrodes, improves motor control large-current and high-frequency switching characteristic performance, and ensures motor drive control reliability.

Description

technical field [0001] The invention relates to the technical field of motor control, in particular to a film capacitor in a three-phase AC motor drive system. Background technique [0002] In a three-phase AC motor drive system, a high-frequency carrier is usually used to drive high-speed switching tubes for power semiconductor devices, and a surge voltage proportional to the stray inductance of the main circuit of the motor drive will be loaded on the power semiconductor devices. The magnitude of the voltage is as formula (1), when the surge voltage V 1 If it is too large, it may cause the power semiconductor device to be broken down and damaged. It can be seen that minimizing the stray inductance of the loop can reduce the surge voltage V 1 . Especially in the field of motor controllers for new energy vehicles, the application trend of SiC and GaN power devices in new energy vehicles is becoming more and more obvious, and the requirements for the drive frequency of swi...

AI Technical Summary

Problems solved by technology

[0002] In a three-phase AC motor drive system, a high-frequency carrier is usually used to drive high-speed switching tubes for power semiconductor devices, and a surge voltage proportional to the stray inductance of the main circuit of the motor drive will be loaded on the power semiconductor devices. The magnitude of the voltage is as formula (1), when the surge voltage V 1 If it is too large, it may cause the power semiconductor device to be broken down and damaged

[0008] like figure 1 As shown, a film capacitor is usually composed of several capacitor cores 1 and positive and negative bus bars 2 and 3, wherein the gold-sprayed electrodes 11 of each capacitor core 1 and the positive and negative bus bars 2 and 3 are connected by welding to form a capacitive circuit. The negative busbar 3 and the positive busbar 2 are located on both sides of the capacitor core 1, the negative busbar 3 and the positive busbar 2 cannot be designed as laminated busbars, and the current loop area S flowing through the positive and negative busbars 2 and 3 is relatively large , it can be seen from formula (2) that the stray inductance L is larger

Due to the large stray inductance in the positive and negative busbars 2 and 3 of the film capacitor, it seriously affects the high-current and high-frequency switching characteristics of the inverter in the three-phase AC motor drive system, and reduces the reliability of the motor drive control.

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