Half-Bridge Support Circuit for Zero-Voltage Wireless Power Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inductive power transmission systems face challenges in maintaining zero-voltage switching and reducing electromagnetic interference (EMI) due to variations in resonant frequency and coil alignment, leading to increased heat development and losses.
Innovation Solution
A support circuit with an energy storing element, such as an inductor, is connected in parallel to the inverter circuit to provide additional current during transient phases, ensuring zero-voltage switching by charging and discharging parasitic capacitances, and a Y-capacitor is used to ground high-frequency signal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If resonant power transfer is used to reduce switching losses and EMI, then power losses and electromagnetic interference are reduced, but maintaining zero-voltage switching becomes difficult when resonant frequency mismatches occur due to coil alignment variations
Solution Approach 1:
A support circuit is introduced as an intermediary component between the inverter circuit and the resonant circuit. This support circuit includes an energy storing element (inductor) connected in parallel to the inverter circuit, which acts as a mediator to provide additional current during transient phases. The support circuit ensures that zero-voltage switching conditions are maintained even when the resonant frequency of the resonant circuit deviates from the power transfer frequency, thereby resolving the contradiction between reducing switching losses and maintaining switching reliability.
2Reliability
If the power transfer frequency is adjusted to match resonant frequency variations, then zero-voltage switching can be maintained, but the complexity of frequency control increases
Solution Approach 1:
The support circuit is designed to automatically detect and respond to transient phases in the inverter circuit without requiring external frequency adjustment controls. The energy storing element in the support circuit self-regulates by charging during half-cycles and discharging during transient phases, providing the necessary current to maintain zero-voltage switching conditions. This self-service mechanism eliminates the need for complex frequency control systems while ensuring reliable zero-voltage switching.
3Reliability
If additional support circuits are added to ensure zero-voltage switching, then switching reliability is improved, but the device complexity increases
Solution Approach 1:
The support circuit is merged with the existing inverter circuit topology by connecting the energy storing element in parallel to the inverter circuit at the half-bridge node. This integration allows the support circuit to share the same physical space and electrical nodes as the inverter circuit, minimizing additional component count and simplifying the overall device structure. The merged design provides zero-voltage switching support without significantly increasing device complexity.
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 reduces power losses and EMI by ensuring zero-voltage switching even when resonant frequencies are mismatched, improving efficiency and reducing electromagnetic interference.
Implementation Method 1
A support circuit with an energy storing element, such as an inductor, is connected in parallel to the inverter circuit to provide additional current during transient phases
Implementation Method 2
ensuring zero-voltage switching by charging and discharging parasitic capacitances
Implementation Method 3
a Y-capacitor is used to ground high-frequency signal components
Implementation Method 4
a voltage and current are induced in a receiving coil and a belonging resonant circuit
Implementation Method 5
Inductive power transmission systems consist of a stationary and a mobile side... a transmission coil (sending coil)... a receiving coil
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention is concerned with a method for operating an inverter circuit (23) in a wireless power transmission device (11), wherein the inverter circuit (23) comprises at least one half-bridge (29A, 29B) with two switching units (35H, 35L, 36H, 36L) that each have a parasitic capacitance (65). In the respective half-bridge (29A, 29B) the first switching unit (35H, 36H) links a plus potential (V+) of a DC source (31) to a half-bridge node (A, B) and the second switching unit (35L, 36L) links the half-bridge node (A, B) to a minus potential (V-) of the DC source (31). A resonant circuit (21) for the wireless power transmission is connected as a load (22) to the respective half-bridge node (A, B), wherein the resonant circuit (21) comprises a transmission coil (27) and at least one capacitive element (27'). An additional support circuit (37) is connected in parallel to the load (22), wherein the support circuit (37) comprises at least one energy storing element (40) that is charged with energy by a charging current (50A) during a respective half-cycle (42) of the switching cycles of the inverter circuit (23) and in a respective transient phase (43) between the half-cycles (42) the support circuit (37) drives a support current (50B) using the stored energy from its at least one energy storing element (40), wherein the support current (50B) adds to the load current (26) in the inverter circuit (23) and by this supports zero-voltage switching, ZVS.