Current Transformer Circuit for Bidirectional Current Detection
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Solution Overview
Problem
Existing current detecting circuits based on current transformers are limited to unidirectional current detection, which is inadequate for bidirectional energy transmission applications, such as on-board chargers, where they fail to accurately detect currents flowing in both directions.
Innovation Solution
A current detecting circuit with a current transformer, demagnetizing circuit, chip selection circuit, sampling circuit, and clamping circuit that can switch between modes to detect currents flowing in both directions, allowing bidirectional current detection by controlling the chip selection circuit between a first mode for one direction and a second mode for the opposite direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional current detecting circuit based on current transformer is used, then unidirectional current detection is achieved, but bidirectional current detection capability is lost
Solution Approach 1:
The patent applies dynamics by making the circuit configuration changeable through switching elements. The chip selection circuit switches between different connection modes (first mode and second mode) to adapt the current detection direction, enabling bidirectional detection without requiring two separate fixed circuits. This dynamic reconfiguration allows the same hardware to serve multiple detection directions.
Solution Approach 2:
The patent implements universality by designing a single current detecting circuit that can perform both unidirectional and bidirectional detection functions. Through the chip selection circuit and switching elements, the same circuit structure achieves multiple detection modes (first direction detection, second direction detection, and bidirectional detection), eliminating the need for separate circuits for each direction.
2Adaptability or versatility
If the chip selection circuit switches between modes for bidirectional detection, then bidirectional current detection is enabled, but switching control complexity increases
Solution Approach 1:
The patent applies self-service by designing the chip selection circuit to automatically select the appropriate detection mode based on the operating conditions. The circuit autonomously determines whether to operate in first mode or second mode according to the current flow direction requirements, reducing the burden on external control systems and simplifying the overall control architecture.
3Reliability
If demagnetizing circuit is added to prevent magnetic bias, then transformer saturation is avoided, but circuit complexity increases
Solution Approach 1:
The patent applies merging by integrating the demagnetizing function into the existing current detection circuit structure. The demagnetizing circuit shares components with the detection circuit, such as using the same transformer and incorporating demagnetizing resistors that also serve as part of the detection pathway. This combination avoids adding completely separate demagnetizing hardware and reduces overall circuit complexity.
Solution Approach 2:
The patent implements universality by designing circuit components that serve multiple functions. The demagnetizing resistors not only provide the demagnetizing function to prevent transformer saturation but also participate in the current detection process. The same circuit pathway is used for both protection and detection purposes, reducing the need for additional dedicated components.
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
Enables accurate bidirectional current detection, supporting peak current control and maintaining detection accuracy during bidirectional energy transmission, thereby addressing the limitations of existing unidirectional detection circuits.
Implementation Method 1
a current transformer (CT) with a peak current control mode... the detecting circuit based on the CT converts a current signal into a voltage signal
Data Source
AI summary
The application provides a current detecting circuit, including a current transformer having a primary winding for receiving a current to be detected and a secondary winding for generating a sampling current; a demagnetizing circuit for demagnetizing the current transformer; a chip selection circuit electrically connected to the demagnetizing circuit, and operably switched between a first mode and a second mode; a sampling circuit electrically connected to the chip selection circuit to sample the sampling current, and outputting a sampling signal to a controller; and a clamping circuit electrically connected between the sampling circuit and the controller, and configured for providing a reference potential. The application further provides a converter including the current detecting circuit.