Wireless Power Transmitter Phase Shift Control
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Solution Overview
Problem
Conventional wireless power transmission systems experience overvoltage and overcurrent issues during the transient state before power transmission begins, and emit high-frequency noise due to duty control methods, which can damage circuit elements and interfere with surrounding electronic devices.
Innovation Solution
A power transmitting apparatus that employs phase control by adjusting the phase shift amount of pulse signals to the switching elements in the oscillation circuit, setting an initial phase shift value when the current exceeds a predetermined level, reducing it incrementally, and maintaining the voltage at a fixed phase shift once the power receiving device is activated, thereby avoiding the time when both positive and negative connections are disconnected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If duty control method is used to control the oscillation circuit, then power transmission can be controlled, but overvoltage and overcurrent occur during transient state and high-frequency noise is emitted
Solution Approach 1:
The patent changes the control parameter from duty cycle to phase shift amount. By controlling the phase shift between pulse signals supplied to switching elements, the system achieves power transmission control while avoiding the transient overvoltage, overcurrent, and high-frequency noise issues associated with duty cycle control methods.
2Object-affected harmful factors
If phase shift amount is reduced incrementally from initial value, then overvoltage and overcurrent are reduced to one-third, but control complexity increases
Solution Approach 1:
The patent applies preliminary action by setting an initial phase shift amount before power transmission begins, then gradually reducing it to the target value. This staged approach prevents sudden voltage and current spikes during the transient state, reducing overvoltage and overcurrent to one-third of duty control levels while maintaining manageable control complexity through a systematic reduction process.
3Device complexity
If both positive and negative connections are disconnected simultaneously, then circuit simplification is achieved, but high-frequency noise is emitted that interferes with surrounding devices
Solution Approach 1:
The patent uses periodic action by controlling the phase shift of pulse signals to timing that prevents simultaneous disconnection of both positive and negative connections. This timing control ensures continuous connection to either positive or negative terminal, eliminating the high-frequency noise generated by simultaneous disconnection while maintaining circuit simplicity.
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 the magnitude of overvoltage and overcurrent to about one-third of that in duty control methods and significantly decreases high-frequency noise emission, preventing damage to the power transmitting apparatus and minimizing interference with other devices.
Implementation Method 1
an oscillator that includes i) a first switching element group connected to a high potential terminal of DC power supply and ii) a second switching element group connected to a low potential terminal of the DC power supply, and the oscillator converts DC power of the DC power supply into the AC power by using the first and second switching element groups
Implementation Method 2
a power transmitting antenna that transmits AC power wirelessly to the power receiving antenna of a power receiving device
Data Source
AI summary
A control method for a power transmitting device is provided, the power transmitting device including a power transmitting antenna, which transmits AC power wirelessly to the power receiving antenna of a power receiving device, and an oscillator. The method includes supplying pulse signals that control first and second switching element groups to the oscillator, and changing a phase shift amount between a first pulse signal and a second pulse signal. The method also includes causing the oscillator to change the voltage of the AC power output and to set an initial value of the phase shift amount. The method further includes causing the oscillator to output preliminary AC power of a voltage to reduce the phase shift amount from the initial value, fixing the phase shift amount, and causing the oscillator to output the AC power while maintaining the voltage corresponding to the fixed phase shift amount.