Converter Switching Current Detection at Phase Switching Points
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Solution Overview
Problem
Current methods for determining switching currents in converters for inductive power transfer systems are not precise, fast, or computationally efficient, leading to inefficiencies and power losses due to capacitive switching and high sampling frequencies required.
Innovation Solution
A method and device for determining switching currents in converters, specifically using a three-phase inverter with B6 bridge topology, where phase currents are measured at switching time points with high-bandwidth current sensors and A/D converters, allowing for precise and efficient determination of switching currents without sampling at all time points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high sampling frequency (>500 kHz) is used to measure phase current for determining switching currents, then measurement precision is improved, but computing power requirement increases and productivity decreases
Solution Approach 1:
The patent extracts only the essential information needed for switching current determination by measuring phase current at specific switching time points rather than continuously sampling at high frequencies. This selective extraction of critical data points maintains measurement precision for switching events while dramatically reducing the computational burden of processing continuous high-frequency signals.
Solution Approach 2:
Instead of implementing full continuous high-frequency sampling which would be excessive for the specific need of determining switching currents, the patent applies partial action by sampling only at the critical switching time points. This partial sampling approach provides sufficient precision for the intended purpose without the overhead of complete continuous measurement.
2Ease of operation
If capacitive switching occurs in converter switching elements, then switching operation is simplified, but power losses increase and efficiency decreases
Solution Approach 1:
The patent implements feedback by using the measured phase current values at switching time points to control the operation of switching elements. The control unit adjusts switching timing and duration based on real-time current measurements, ensuring that switching occurs when phase current is positive. This feedback mechanism prevents capacitive switching and its associated energy losses while maintaining ease of operation through automated current-based control.
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 method enables precise and computationally efficient determination of switching currents, reducing power losses and improving the efficiency of inductive power transfer by avoiding capacitive switching and minimizing the impact of high sampling frequencies.
Implementation Method 1
a current sensor (8) connected to said at least one AC phase line (U, V, W) for determining a phase current in said at least one AC phase line (U, V, W)
Implementation Method 2
and/or a digital value of the phase current at the switching time point is determined depending on a measured or calculated phase current
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method and a device for determining a switching current of at least one switching element (6) of a converter (5) of a system for inductive power transfer, wherein the method comprises the steps of - determine a phase current (IU, IV, IW) of at least one AC phase line of the converter (5), - determine at least one switching time point (SP, SP1, SP2, SP3) of the at least one switching element (6) and the phase current value at said switching time point (SP, SP1, SP2, SP3), - determine switching current of the at least one switching element (6) depending on the at least one phase current value as well as a method for controlling an operation of at least one switching element (6).