Solar Power Detection Circuit Using Voltage-Time Conversion
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Solution Overview
Problem
Existing power detection circuits for low power energy harvesting systems, such as those used in solar cells, face challenges in minimizing power consumption while accurately detecting power, as they require both voltage and current detection, leading to high power consumption and inefficiency, especially in varying environmental conditions.
Innovation Solution
A power detection circuit that uses a direct power detecting method, extracting average and ripple voltage values through a low-pass filter and sample and hold circuit, converting these voltage values into time information using a voltage-time converter, and then multiplying this information to track the maximum power point without requiring current detection, thus reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage and current detection circuits are used to detect power, then measurement precision is improved, but use of energy increases due to high power consumption
Solution Approach 1:
The patent extracts only the voltage detection function from the traditional voltage-and-current detection approach. By removing the current detection circuitry and relying solely on voltage measurement combined with power model calculations, the system achieves adequate power detection precision while dramatically reducing power consumption in energy harvesting systems
Solution Approach 2:
The patent introduces a power model as an intermediary element that translates voltage measurements into power estimates. This mediator allows the system to infer power information without directly measuring current, thereby avoiding the high power consumption associated with precision current sensing circuits
2Measurement precision
If direct power detection method is used, then measurement precision is improved, but device complexity increases due to additional circuits
Solution Approach 1:
The patent extracts and eliminates complex current sensing circuits from the detection system. By focusing only on voltage measurement and using computational methods to derive power information, the system maintains measurement precision while significantly simplifying the hardware architecture
Solution Approach 2:
The patent replaces physical current measurement mechanisms with computational analysis of voltage waveforms. Instead of using complex electrical circuits to directly measure current, the system uses digital signal processing and power models to calculate power from voltage data alone
3Ease of operation
If time-domain technique with fixed voltage hysteresis window is used, then ease of operation is improved, but measurement precision deteriorates under varying environmental conditions
Solution Approach 1:
The patent transitions from static fixed hysteresis windows to dynamic adaptive detection thresholds. The system adjusts its detection parameters based on real-time environmental conditions and power model predictions, maintaining operational simplicity while achieving accurate power detection across varying operating conditions
Solution Approach 2:
The patent implements feedback mechanisms where power model predictions and actual measurements are continuously compared. This feedback loop allows the system to refine its detection accuracy by adjusting detection parameters based on observed performance, thereby maintaining precision under varying environmental conditions without complicating the operation
Data Source
AI summary
Provided is a power detection circuit for tracking a maximum power point of a solar cell. The power detection circuit includes: an average voltage extracting unit which extracts an average voltage VPV,LPF from an external voltage VPV input from an external energy source; a ripple voltage extracting unit which extracts a ripple voltage including current information of the external voltage VPV from the external voltage VPV; a voltage-time converter which generates a ramp voltage VRAMP changing at a predetermined rate and converts the average voltage VPV,LPF and the ripple voltage into corresponding time information Δt1 and Δt2 based on the ramp voltage VRAMP; a time-digital converter which converts the time information Δt2 for the ripple voltage into a digital code t2 [n:0]; and a time multiplier which multiplies the digital code t2 [n:0] and the time information Δt1 for the average voltage VPV,LPF to output a specific voltage value.