Contactless Power Supply Phase Control for Efficiency
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Solution Overview
Problem
Existing contactless power supply devices require higher Q factors, leading to larger receiver coils and increased device footprint, which complicates power transmission efficiency.
Innovation Solution
A contactless power supply device with a power transmitter and receiver that includes a variable capacitance circuit and control circuit to adjust electrostatic charge, allowing for optimal phase delay in switching elements and reducing switching and conduction losses without increasing the Q factor or coil size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the Q factor is increased to establish a suitable drive frequency, then the power transmission efficiency is improved, but the receiver coil size must increase leading to larger device footprint
Solution Approach 1:
The patent changes the operating parameters by controlling the phase angle of the drive current relative to the voltage phase, and by adjusting the Q factor to be at or equal to Q=2/k². This parameter optimization allows achieving suitable drive frequency and good power transmission efficiency without requiring excessively large receiver coils, thus resolving the contradiction between efficiency and device size.
2Power
If the receiver coil inductance is increased to increase the Q factor, then the drive frequency selection is improved, but the receiver coil physical size must increase
Solution Approach 1:
The patent optimizes the inductance value of the receiver coil to achieve the appropriate Q factor without excessive coil size. By carefully selecting and adjusting the inductance parameter along with capacitance, the system achieves suitable drive frequency selection while keeping the receiver coil physical dimensions reasonable.
3Reliability
If higher Q factors are required, then the resonant circuit performance is improved, but the overall device complexity increases
Solution Approach 1:
The patent establishes the Q factor at or equal to Q=2/k², which is an optimized parameter value that achieves good resonant circuit performance without requiring overly complex circuit configurations. This parameter optimization maintains reliability while avoiding excessive 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
Improves power transmission efficiency by minimizing switching and conduction losses, reducing the peak current in switching elements and RMS current in the auxiliary coil, thus maintaining efficient power transfer without the need for larger coils.
Implementation Method 1
a resonant circuit including a receiver coil and a resonant capacitor for resonating with the receiver coil and configured to receive power from the power transmitter
Implementation Method 2
a resonant circuit including a receiver coil and a resonant capacitor for resonating with the receiver coil
Implementation Method 3
an auxiliary coil configured for electromagnetic coupling with the transmitter coil
Data Source
AI summary
A contactless power supply device includes a power transmitter, and a power receiver. The power receiver includes: a resonant circuit including a receiver coil and a resonant capacitor; a rectifier circuit configured to rectify the power output from the resonant circuit; a voltage detection circuit configured to measure the output voltage from the rectifier circuit and obtain a measurement value for said output voltage; and a first communication device. The power transmitter includes: a transmitter coil; a power supply circuit including a power source and a plurality of switching elements between the power source and the transmitter coil; an auxiliary coil for electromagnetic coupling with the transmitter coil; a variable capacitance circuit configured to connect to the auxiliary coil and adjust the electrostatic charge therein; and a control circuit configured to control the electrostatic charge in the variable capacitance circuit in accordance with the measurement value for the output voltage.