Resonant Half-Bridge DC/DC Frequency Control Across Input Voltage Range
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Solution Overview
Problem
Isolated voltage converters face challenges in maintaining adequate output power at low input voltage levels while preventing excessive power delivery at high input voltage levels, which can lead to component damage due to short-circuits.
Innovation Solution
A primary-side control and power circuit that inversely varies the switching frequency with respect to input voltage, incorporating a voltage-controlled oscillator and over-power protection circuit to manage the duty cycle and limit maximum output power, thereby ensuring safe operation across varying input voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the switching frequency is increased to enhance output power at low input voltages, then the output power is improved, but the risk of component damage increases at high input voltages
Solution Approach 1:
The patent implements dynamic switching frequency adjustment where the frequency varies inversely with input voltage. At low input voltages, the switching frequency is increased to maintain adequate output power. At high input voltages, the switching frequency is decreased to prevent excessive power delivery and component damage. This dynamic adaptation resolves the contradiction by making the system flexible rather than fixed.
Solution Approach 2:
The patent changes the switching frequency parameter based on input voltage conditions. A voltage-controlled oscillator (VCO) generates clock signals whose frequency is controlled by the input voltage level, creating an inverse relationship. This parameter change strategy allows the system to optimize output power at low voltages while limiting power at high voltages, resolving the technical contradiction.
2Device complexity
If a fixed switching frequency is used, then the circuit design is simplified, but the output power cannot be adequately maintained across varying input voltage ranges
Solution Approach 1:
The patent employs feedback mechanisms where the input voltage level is sensed and used to control the switching frequency through a VCO. The system continuously monitors input voltage conditions and adjusts the frequency accordingly, ensuring adequate output power across varying input ranges while maintaining manageable circuit complexity through integrated control.
Solution Approach 2:
The voltage-controlled oscillator serves multiple functions: it generates the switching clock signal, provides frequency modulation based on input voltage, and enables adaptive power control. This multi-functionality reduces overall circuit complexity while achieving the goal of maintaining consistent output power across varying input conditions.
3Reliability
If the duty cycle is increased to prevent excessive power delivery, then component protection is improved, but the output power capability is reduced
Solution Approach 1:
The patent dynamically adjusts both duty cycle and switching frequency based on input voltage conditions. At high input voltages, the duty cycle is limited and switching frequency is reduced to prevent excessive power delivery and protect components. At low input voltages, the duty cycle can be increased to maintain output power capability. This dynamic coordination resolves the contradiction between protection and power capability.
Solution Approach 2:
The patent uses periodic switching action with variable frequency and duty cycle to control power delivery. By modulating the switching waveform characteristics according to input voltage levels, the system achieves both component protection at high voltages and adequate output power at low voltages, resolving the technical contradiction.
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 low input voltages and prevents dangerous power levels at high input voltages, ensuring safe and efficient converter operation by dynamically adjusting the switching frequency and duty cycle.
Implementation Method 1
A voltage-controlled oscillator (VCO) has a VCO control input and a VCO clock output. The VCO control input is coupled to the control circuit output. 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.