Simulation Current Signal Generation Circuit for Power Converters
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Solution Overview
Problem
Conventional power converter technologies face challenges in sensing real-time output current waveforms, especially in high voltage-converting ratio and high-speed switching applications, due to the limitations of existing current sensing methods which either fail to provide real-time data or require additional components and increased complexity.
Innovation Solution
A power conversion circuit with a simulation current signal generation circuit that includes a PWM circuit, impedance component, and switching circuit, which selectively outputs current signals based on PWM signals to simulate the output current waveform without additional components, allowing for real-time sensing and reduced circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EA sensing method or sample-and-hold sensing method is used, then current sensing is performed, but real-time output current waveform cannot be obtained
Solution Approach 1:
The patent uses a current mirror circuit to create a copy of the output current waveform. The current mirror circuit replicates the current flowing through the output inductor, allowing the controller to sense the copied current signal without interfering with the actual power conversion process. This enables real-time current waveform acquisition while maintaining measurement accuracy.
2Loss of time
If DCR sensing method is used, then real-time output current waveform can be sensed, but additional components and pins are required resulting in complicated circuit and increased cost
Solution Approach 1:
The patent leverages existing components in the power conversion circuit to perform current sensing. The output inductor that is already part of the power conversion process serves dual purposes: it performs its primary function of energy storage and transfer, and simultaneously enables current sensing through the current mirror circuit. This eliminates the need for additional dedicated sensing components and reduces circuit complexity.
Solution Approach 2:
The output inductor is made multi-functional by using it both for power conversion and as the basis for current sensing. The same physical component (output inductor) serves both the power transfer function and the sensing reference function, allowing the system to achieve real-time current waveform sensing without adding separate sensing components.
3Measurement precision
If conventional current sensing methods are used in high voltage-converting ratio applications, then current sensing is attempted, but sensing fails when on-time is very short
Solution Approach 1:
The current mirror circuit is configured to capture and hold the current waveform information during the entire switching cycle, not just during the brief on-time period. By using the off-time period to replicate and process the current information, the system prepares the current waveform data in advance for controller processing, enabling accurate sensing even when the actual on-time is very short.
Data Source
AI summary
A simulation current signal generation circuit applied to a power conversion circuit is disclosed. The power conversion circuit has an output terminal and includes an output stage, a PWM circuit and an impedance component. One terminal of impedance component is coupled to the output terminal. The generation circuit includes a first current signal circuit, a second current signal circuit and a switching circuit. The first current signal circuit, coupled to another terminal of impedance component, provides a first current signal. The second current signal circuit, coupled to the output stage, senses a current of a power switch in the output stage to provide a second current signal. The switching circuit, coupled to the first current signal circuit, second current signal circuit and PWM circuit respectively, selectively outputs the first current signal or second current signal according to a PWM signal provided by the PWM circuit.