Voltage Support Circuit for Power Converter Load Transients
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Solution Overview
Problem
Power converters experience significant output voltage drops during sudden increases in load current due to slow transient responses, which can be problematic for devices with specific USB PD requirements.
Innovation Solution
A voltage support circuit is integrated with the power converter, utilizing a transconductance amplifier and capacitors to rapidly increase the output voltage in response to load changes, thereby minimizing voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional power converter is used, then the device structure is simple, but the output voltage drops significantly during sudden load current increases
Solution Approach 1:
The patent introduces a voltage support circuit as an intermediary component between the power converter and the load. This circuit includes a buffer amplifier and capacitor that act as a mediator to rapidly supply charge during load transients, preventing output voltage droop without requiring fundamental changes to the power converter architecture.
Solution Approach 2:
The voltage support circuit performs preliminary action by pre-charging the capacitor during normal operation and being ready to immediately discharge it when a load transient occurs. This preliminary preparation allows the circuit to respond instantaneously to load changes, maintaining output voltage stability before the main power converter can react.
2Speed
If the power converter responds slowly to load changes, then the circuit is simpler, but the transient response time is too long
Solution Approach 1:
The patent segments the voltage regulation function into two parts: the main power converter handles steady-state regulation, while the voltage support circuit with buffer amplifier and capacitor handles transient response. This segmentation allows each part to be optimized for its specific function, achieving fast transient response without overcomplicating the entire system.
Solution Approach 2:
The voltage support circuit changes the effective output impedance parameter dynamically. During normal operation, the buffer amplifier maintains high output impedance for stability. During transients, the capacitor discharge provides low impedance current supply, effectively changing the circuit's response characteristics without physical reconfiguration.
3Reliability
If no voltage support circuit is used, then the device is simpler, but the voltage droop magnitude and duration are problematic
Solution Approach 1:
The capacitor in the voltage support circuit provides beforehand cushioning by being pre-charged during normal operation. When a load transient causes voltage droop, this pre-charged capacitor immediately discharges to cushion the voltage drop, preventing it from exceeding acceptable limits. This is analogous to having a safety buffer ready in advance.
Solution Approach 2:
The buffer amplifier in the voltage support circuit operates with feedback from the output voltage node. This feedback mechanism allows the circuit to continuously monitor output voltage and automatically activate the capacitor discharge when voltage droop is detected, providing automatic correction without external intervention.
Data Source
AI summary
An apparatus includes a power converter having a first voltage terminal and a second voltage terminal and including a voltage divider coupled between the second voltage terminal and a voltage supply terminal. The voltage divider has an output. A transconductance amplifier has a first input, a second input, and an output. The first input is coupled to the output of the voltage divider. The second input is coupled to a reference voltage circuit. A first capacitor is coupled between the output of the transconductance amplifier and the voltage supply terminal. A buffer has an input coupled to the output of the transconductance amplifier and has an output. A second capacitor is coupled between the output of the buffer and the second voltage terminal.