As the "heart" of modern industry, the high-voltage inverter relies directly on the reliability of its power modules to ensure stable system operation. However, Partial Discharge (PD)—acting like an "invisible killer" lurking within the module—gradually erodes insulating materials under the repeated stress of high-voltage transients, ultimately leading to module failure. Consequently, anti-partial discharge encapsulation technology serves as a critical line of defense for guaranteeing the longevity and high reliability of power modules.

The occurrence of partial discharge stems from uneven electric field distribution or the presence of microscopic air gaps within the insulation structure. In a high-voltage environment, the gas within these air gaps is the first to undergo dielectric breakdown, generating tiny electrical sparks. Although this "silent discharge" does not immediately result in a short circuit, the energy it releases continuously erodes the surrounding epoxy resin and electronic components, forming irreversible "electrical treeing" channels that eventually lead to complete dielectric breakdown. Therefore, the core principle of partial discharge prevention lies in "eliminating air gaps" and "equalizing the electric field."

Advanced encapsulation technology leverages the synergistic effect of "vacuum degassing and low-pressure injection" to eliminate the formation of air gaps at the source. Prior to encapsulation, both the power module and the encapsulating resin are placed in a vacuum environment to thoroughly extract any air trapped within the materials or adsorbed onto their surfaces. Subsequently—while maintaining a negative pressure environment—a low-viscosity epoxy resin is slowly injected into every nook and cranny of the module. This "low-pressure penetration" process ensures that the resin fully fills the microscopic crevices between components, completely "expelling" air from the insulation system to form a dense, void-free protective insulating layer.

The selection of the encapsulating resin material is equally critical. Epoxy resins with a low dielectric constant not only minimize electric field concentration but also—thanks to their superior adhesion and low shrinkage rate—effectively dissipate thermal stress, thereby preventing micro-cracks caused by thermal cycling from becoming breeding grounds for partial discharge. Furthermore, the incorporation of specific nanofillers (such as surface-modified silicon dioxide) can serve to further "trap" free electrons, thereby inhibiting the initiation of electrical discharge. From precise resin injection in a vacuum environment to the synergistic protection afforded by high-performance materials, partial discharge-resistant potting technology effectively cloaks power modules in a layer of "invisible insulating armor." This enables them to maintain their "inner" tranquility amidst the "storms" of high voltage, thereby ensuring the absolute reliability of power transmission.