Resonant Half-Bridge DC/DC Burst Control for Input Voltage Range
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Solution Overview
Problem
Isolated voltage converters face challenges in maintaining adequate output power at lower input voltage levels while preventing excessive power delivery at higher levels, which can lead to component damage during short-circuits.
Innovation Solution
A primary-side control and power circuit that inversely varies the switching frequency with input voltage, incorporating a voltage-controlled oscillator and over-power protection circuit to manage duty cycle and limit maximum output power, using a transformer for isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching frequency is kept constant, then the converter operates simply, but the output power becomes excessive at higher input voltages causing component damage
Solution Approach 1:
The patent implements dynamic switching frequency adjustment where the VCO continuously varies the switching frequency based on the control voltage. As input voltage increases, the control voltage changes to reduce switching frequency, thereby preventing excessive power delivery while maintaining circuit protection
Solution Approach 2:
The control circuit receives feedback about input voltage conditions and adjusts the control voltage accordingly. This feedback mechanism ensures that the switching frequency is automatically reduced when input voltage rises, preventing over-power conditions without requiring complex external protection circuits
2Power
If the switching frequency is reduced at lower input voltages, then output power is enhanced, but the converter becomes more complex
Solution Approach 1:
The patent changes the switching frequency parameter dynamically based on input voltage levels. At lower input voltages, the control voltage maintains higher switching frequency to optimize power transfer and enhance output power, while the VCO circuit implements this parameter change without requiring additional external components
3Power
If fixed frequency switching is used, then the control circuit is simple, but adequate output power cannot be maintained at lower input voltage levels
Solution Approach 1:
The system transitions from fixed frequency to dynamic frequency adjustment. The VCO circuit enables the switching frequency to adapt to varying input voltage conditions, maintaining adequate output power at lower input voltages by optimizing the frequency based on real-time voltage levels
Solution Approach 2:
The control circuit performs multiple functions: it regulates output power, protects against over-power conditions, and adapts to varying input voltage levels. The VCO integrates these functions by generating a single control signal that simultaneously manages switching frequency for both power optimization and protection
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
Enhances output power at lower input voltages and prevents excessive power delivery at higher voltages, ensuring safe operation and efficient energy transfer.
Implementation Method 1
A galvanic isolation barrier is a transformer, which has two inductors—a primary coil for the input side of the converter and a secondary coil for the output side of the converter—and there is no direct electrical connection between the primary and secondary coils
Implementation Method 2
The VCO is configured to produce a VCO clock on the VCO clock output having a frequency that is a function of the control voltage
Data Source
AI summary
A system includes a control circuit having a voltage input and a control circuit output. The control circuit produces a control voltage at the control circuit output having a magnitude inversely related to a magnitude of an input voltage at the input voltage input. A VCO has a VCO control input and a VCO clock output. The VCO control input is coupled to the control circuit output. The VCO produces a VCO clock on the VCO clock output having a frequency that is a function of the control voltage. A protection circuit has a first clock input, a second clock input, and a protection circuit output. The second clock input is coupled to the VCO clock output. The protection circuit generates a protection circuit output signal at the protection circuit output based on a difference in frequency between a clock signal at the first clock input and the VCO clock.