Rectifier Cross Connector for Parasitic Capacitance Discharge
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Solution Overview
Problem
Conventional rectifiers experience switching loss due to delayed discharge of parasitic capacitance in switching devices, leading to inefficiencies as the size of the switching device increases, resulting in a blunt falling edge and prolonged switching time.
Innovation Solution
Incorporating a cross connector that allows parasitic capacitance of high side switches to flow to ground when turned off, and using level shifters to adjust gate voltages for uniform gate-source voltages, thereby facilitating quicker discharge of parasitic capacitance and minimizing switching loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large switching device is used to supply sufficient current, then the current supply capability is improved, but the discharge time of parasitic capacitance is prolonged
Solution Approach 1:
The patent extracts the parasitic capacitance discharge function from the main switching device by introducing a separate discharge switch connected in parallel with the switching device. This discharge switch is specifically dedicated to discharging the parasitic capacitance of the switching device, allowing the main switching device to focus on current supply while the discharge switch handles capacitance discharge, thereby resolving the contradiction between current supply capability and switching time.
Solution Approach 2:
The patent introduces a discharge switch as an intermediary element between the parasitic capacitance and ground. This discharge switch acts as a mediator that provides a dedicated discharge path for the parasitic capacitance, enabling fast discharge without affecting the main switching device's current supply capability. The intermediary discharge switch resolves the time delay issue while preserving the power supply capability.
2Power
If the switching device size is increased, then the current handling capacity is improved, but switching loss increases due to delayed capacitance discharge
Solution Approach 1:
The patent extracts the capacitance discharge function from the main switching device's operation by introducing a separate discharge switch. This separation allows the main switching device to maintain large size for high current handling capacity while the dedicated discharge switch rapidly discharges parasitic capacitance, preventing energy loss during switching transitions and resolving the contradiction between power capacity and switching loss.
Solution Approach 2:
The discharge switch is activated in advance or simultaneously with the main switching device to pre-establish a discharge path for parasitic capacitance. This preliminary action ensures that capacitance discharge begins before or during the main switching event, reducing the overall switching time and minimizing energy loss while allowing the main device to operate at full power capacity.
3Power
If a large switching device is used, then sufficient current can be supplied, but the falling edge becomes blunt requiring a predetermined period for discharge
Solution Approach 1:
The patent extracts the fast discharge function from the main switching device by introducing a dedicated discharge switch with low on-resistance. This discharge switch is specifically designed to rapidly discharge parasitic capacitance, providing a sharp falling edge. The main switching device can thus be large for sufficient current supply while the discharge switch ensures fast edge transition, resolving the contradiction between power capability and edge speed.
Solution Approach 2:
The patent changes the resistance parameter of the discharge path by introducing a discharge switch with deliberately low on-resistance. This parameter change enables rapid capacitance discharge and sharp falling edge generation. The discharge switch's low resistance compensates for the larger size of the main switching device, maintaining fast edge speed while allowing high current supply capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in a more linear falling edge and reduced switching loss, even with increased switch capacity, maintaining efficiency during high voltage AC input.
Implementation Method 1
a cross connector configured to allow parasitic capacitance of the first high side switch or the second high side switch to flow to a ground when the first high side switch or the second high side switch is turned off
Data Source
AI summary
A rectifier includes: first and second high side switches including source terminals connected to an alternating current input terminal and drain terminals connected to one end of an output capacitor; first and second low side switches including drain terminals connected to the alternating current input terminal and source terminals connected to a ground terminal and another end of the output capacitor; and a cross connector configured to allow parasitic capacitance of the first high side switch or the second high side switch to flow to a ground when the first high side switch or the second high side switch is turned off.