Class D Amplifier Ramp Current Tank Circuit for Zero Voltage Switching
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Solution Overview
Problem
Conventional voltage mode class D amplifiers in wireless energy transfer systems face high losses due to output capacitance and leakage inductance, leading to reduced efficiency and sensitivity to load resistance variations, requiring complex matching networks and cooling systems.
Innovation Solution
A high efficiency VMCD power amplifier design featuring a pair of transistors connected in series with a ramp current tank circuit, comprising an inductor and capacitor, operating at a low resonant frequency to minimize losses and enable zero voltage switching, and utilizing GaN FETs for improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If resonance is used to increase voltage across leakage inductance, then power delivery increases, but system complexity increases due to matching networks
Solution Approach 1:
The patent combines the resonant tank circuit with the output stage, merging the power delivery function and the impedance matching function into a single integrated structure. This eliminates the need for separate matching networks while maintaining resonant operation for enhanced power delivery.
Solution Approach 2:
The second stage is designed to perform multiple functions: it handles output capacitance management, provides impedance transformation, and enables resonant operation for enhanced power delivery. This multi-functionality reduces overall system complexity by eliminating dedicated matching networks.
2Loss of energy
If inductor size is reduced to minimize losses, then efficiency improves, but inductance value decreases affecting power delivery
Solution Approach 1:
The patent changes the operating parameters by using very small inductors (e.g., 100 nH or less) in conjunction with a resonant tank circuit operating at specific frequencies. This parameter change allows the system to achieve both low inductor losses and adequate power delivery capability through resonant enhancement rather than relying on large inductance values.
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 achieves high efficiency with minimized inductor sizes and reduced losses, maintaining efficiency across varying load conditions without the need for forced air cooling, and allows for discrete programmability of zero voltage switching current.
Implementation Method 1
a ramp current tank circuit, comprising an inductor and capacitor, operating at a low resonant frequency to minimize losses and enable zero voltage switching
Implementation Method 2
As the electromagnetic waves pass by and sweep the receiving coil, a current is induced in the receiving coil that is proportional to the energy that the antenna captures
Data Source
AI summary
A high efficiency voltage mode class D amplifier and energy transfer system is provided. The amplifier and system includes a pair of transistors connected in series between a voltage source and a ground connection. Further, a ramp current tank circuit is coupled in parallel with one of the pair of transistors and a resonant tuned load circuit is coupled to the ramp current tank circuit. The ramp current tank circuit can include an inductor that absorbs an output capacitance COSS of the pair of transistors and a capacitor the provides DC blocking.