Transformer Gate-Charge Recycling for High-Frequency Power Switches
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Solution Overview
Problem
Increasing commutation cycle rates in DC-DC power converters lead to increased gate charge losses due to the charging and discharging of gate capacitance in power switches, which becomes a significant issue as losses rise with higher frequencies.
Innovation Solution
A circuit arrangement and method that recovers the gate charge of power switches by using a transformer to bounce the gate charge between power switches, allowing efficient commutation between on-state and off-state, and distributing the recovered charge to multiple supplies, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the commutation cycle rate is increased to reduce the size of external components, then the integration density is improved, but the gate charge losses increase significantly
Solution Approach 1:
The patent recovers the gate charge energy that would otherwise be dissipated as loss. When the power switch turns off, the gate charge is discharged through a recovery circuit that captures the energy and stores it in a capacitor. This recovered energy is then reused to charge the gate for the next switching cycle, significantly reducing the energy losses associated with high-frequency commutation while allowing the use of smaller external components
2Productivity
If the commutation cycle rate is increased to improve power converter integration, then the clock rate is improved, but the power consumption increases due to gate charge
Solution Approach 1:
The patent implements a feedback mechanism where the energy consumed by gate charging is captured and fed back into the system. The recovery circuit monitors the gate discharge current and redirects it through a diode to charge a recovery capacitor, which then feeds energy back to the gate driver. This closed-loop energy feedback allows high clock rates to be sustained without proportional increases in power consumption
3Speed
If the gate capacitance is charged and discharged at high commutation rates, then the switching speed is improved, but the energy losses become significant
Solution Approach 1:
The patent employs periodic action by synchronizing the gate charge recovery with the switching cycle. The recovery capacitor is charged during the off-period of the switch and discharged during the on-period, creating a periodic energy transfer that matches the commutation frequency. This periodic energy recovery ensures that switching speed is maintained at high frequencies while energy losses are minimized through systematic reuse of gate charge energy
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
This approach enables power switches to be commutated in a power-efficient manner, reducing energy losses and allowing for smaller external components in DC-DC power converters, particularly in portable applications.
Implementation Method 1
coupling the gate of the first power switch with ground via a primary winding of a transformer to discharge the gate capacitor of the first power switch, thereby causing a discharge current through the primary winding
Data Source
AI summary
Power switches operate with reduced power consumption. A circuit controls a power switch via its gate having a gate capacitor. The circuit comprises an on-control switch coupling the gate of the power switch with a charge supply to provide a gate charge to the gate capacitor of the power switch, thereby putting the power switch to the on-state; a transformer and an off-control switch coupling the gate of the power switch with ground via a primary winding of the transformer to discharge the gate capacitor of the power switch, thereby causing a discharge current through the primary winding and thereby putting the power switch to the off-state; wherein a secondary winding is coupled to the charge supply, such that a current, which is induced in the secondary winding, recharges the charge supply.