DC-DC Converter Low-Voltage Startup Duty Cycle Control
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Solution Overview
Problem
Conventional DC-DC converters cannot efficiently convert very low input voltages into output voltages sufficient to power electronic circuits without the use of expensive transformers and require a minimum input voltage of 0.6 V, limiting their ability to operate at low power and voltage conditions.
Innovation Solution
A low-power, low-voltage start-up DC-DC converter with an adaptive input impedance, utilizing a simple inductor and a controller powered directly by the input voltage, which adjusts the duty cycle to increase input impedance and convert input voltages as low as 200 mV into output voltages of 1.5 V to 3 V, suitable for powering electronic circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a traditional Boost type DC-DC converter is used, then the converter can provide output voltage higher than input voltage, but the input voltage cannot be very low (must be greater than 0.6 V) unless an input transformer is used
Solution Approach 1:
The patent changes the operating parameters of the DC-DC converter by implementing a duty cycle control mechanism that adapts to very low input voltages (down to 200 mV). The controller adjusts the switching duty cycle to maintain proper operation at voltages below the traditional 0.6 V threshold, eliminating the need for transformers while extending the usable input voltage range.
Solution Approach 2:
The patent implements dynamic adaptation of input impedance through controller-based duty cycle adjustment. The converter dynamically modifies its operating characteristics in response to varying input voltage conditions, allowing it to maintain stable operation across an extended voltage range without requiring static components like transformers.
2Power
If the input voltage is very low (around 200 mV), then the converter can operate at ultra-low voltage, but the input impedance is not controlled which causes too high voltage drop at the output of the energy source
Solution Approach 1:
The patent implements a feedback control mechanism where the controller monitors the operating conditions and adjusts the duty cycle accordingly. This feedback loop enables the converter to maintain appropriate input impedance even at very low voltages, preventing excessive voltage drops at the energy source output by continuously adapting to the operating point.
Solution Approach 2:
The input impedance is dynamically controlled through duty cycle adjustment based on the input voltage level. At ultra-low voltages around 200 mV, the controller increases the duty cycle to maintain proper power transfer and minimize voltage drops, ensuring reliable operation across the extended voltage range.
3Power
If a transformer is used to enable very low input voltage conversion, then the converter can operate at low voltage, but the production is significantly complicated and cost increases
Solution Approach 1:
The patent extracts and eliminates the transformer component from the DC-DC converter architecture. By removing this complex magnetic component, the design achieves very low input voltage operation (down to 200 mV) through purely electronic means using a controller and switching mechanism, significantly simplifying the overall structure and manufacturing process while maintaining the desired voltage conversion capability.
Solution Approach 2:
The patent replaces the mechanical/magnetic transformer system with an electronic control-based solution. The controller uses switching devices and duty cycle modulation to achieve voltage transformation without mechanical or magnetic components, eliminating the complexity associated with transformer design, winding, and magnetic material selection while enabling operation at ultra-low input voltages.
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 the conversion of low input voltages into usable output voltages for electronic circuits, allowing operation at very low power and voltage conditions without the need for transformers, ensuring reliable power supply even under low illumination or thermal conditions.
Implementation Method 1
An inductive DC-DC converter of the Boost type... comprises an inductor connected to a power source
Implementation Method 2
a diode element linked to a connection node of the inductor and the switch to provide an output voltage
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A low-power, low-voltage DC-DC converter (1) comprises an inductor (3) connected to an input voltage source (2), a switch (11) connected to the inductor and controlled by a controller (10), and a diode (12) connected to a node connecting the inductor and the switch to provide an output voltage (Vout). The controller includes an oscillator and a monostable element, which are powered by the input voltage (Vin). The oscillator provides an oscillation signal (OSC) at a period T of a switching cycle of the switch. The monostable element is controlled by the oscillation signal to determine a conduction time Tn of the switch, during which an increasing current (IL) flows through the inductor. The input impedance of the DC-DC converter increases when the input voltage (Vin) falls below a first voltage threshold and with a decreasing duty cycle d = Tn/T.