Bootstrap Switching Circuit for Synchronous Series Switch Control

The patent divides the single bootstrap capacitor into multiple separate bootstrap capacitors (first bootstrap capacitor and second bootstrap capacitor), each associated with a specific switching element. This segmentation allows each capacitor to independently maintain the required voltage for its corresponding switching element's drive circuit, enabling reliable synchronous operation while maintaining high voltage capability through series connection of the switching elements.

The patent introduces transfer capacitors (first transfer capacitor and second transfer capacitor) as intermediary elements that facilitate voltage transfer between the bootstrap capacitors and the drive circuits. These transfer capacitors act as mediators to ensure that each drive circuit receives the necessary high voltage from its corresponding bootstrap capacitor, enabling simultaneous turn-on of series-connected switching elements without overvoltage breakdown.

The single bootstrap capacitor is segmented into multiple bootstrap capacitors, each dedicated to a specific switching element. Although this increases the number of components, it enables each capacitor to maintain the required voltage level independently, ensuring that the drive circuits for series-connected switching elements receive sufficient voltage for simultaneous operation without element breakdown.

The patent implements preliminary charging of each bootstrap capacitor through dedicated charging circuits before the switching elements are operated. This preliminary action ensures that each bootstrap capacitor is pre-charged to the necessary voltage level, enabling the drive circuits to immediately control the switching elements simultaneously when required, without voltage dropout or element breakdown.

By segmenting the bootstrap capacitor into multiple independent capacitors, each associated with a specific switching element, the patent ensures that each switching element has dedicated voltage support during simultaneous turn-on. This segmentation prevents overvoltage conditions that would occur with a single shared capacitor, thereby enabling efficient simultaneous switching without element breakdown.

The patent implements prior cushioning by pre-charging each bootstrap capacitor to the necessary voltage level before the switching elements are operated. This preliminary voltage preparation cushions against voltage drops that would occur during simultaneous turn-on, preventing overvoltage stress on the switching elements while maintaining high switching efficiency.