PFC Controller Dynamic Switching Frequency for Power Supply Efficiency
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Solution Overview
Problem
Power supply devices with power factor correction circuits face inefficiencies due to switching losses, which are exacerbated by lower switching frequencies, leading to increased component sizes and area requirements.
Innovation Solution
A power supply device with a PFC controller that includes an error amplifier, oscillation frequency control circuit, and PWM control circuit, utilizing a triangular wave generating circuit with current mirror circuits and a comparator to optimize switching frequency based on load conditions, thereby reducing switching losses and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching frequency is reduced to decrease switching loss, then power conversion efficiency is improved, but inductor and capacitor sizes must be enlarged leading to increased die area and packaging area
Solution Approach 1:
The patent implements dynamic switching frequency adjustment by introducing an oscillation frequency control circuit that varies the switching frequency based on operating conditions. The frequency is dynamically changed according to the output voltage error signal, allowing the system to operate at lower frequencies when needed to reduce switching losses, while maintaining higher frequencies when compact component sizes are required, thus resolving the contradiction between switching loss and die area.
Solution Approach 2:
The patent changes the switching frequency parameter dynamically based on operating conditions. By adjusting the oscillation frequency control circuit's output, the system can modify the switching frequency to optimize performance. This parameter change allows the system to achieve lower switching losses at reduced frequencies without permanently increasing component sizes, as the frequency is adaptively controlled rather than fixed.
2Loss of energy
If switching frequency is reduced to decrease switching loss, then power conversion efficiency is improved, but inductor and capacitor sizes must be enlarged leading to increased packaging area
Solution Approach 1:
The patent implements dynamic switching frequency adjustment by introducing an oscillation frequency control circuit that varies the switching frequency based on operating conditions. The frequency is dynamically changed according to the output voltage error signal, allowing the system to operate at lower frequencies when needed to reduce switching losses, while maintaining higher frequencies when compact component sizes are required, thus resolving the contradiction between switching loss and packaging area.
3Area of stationary object
If switching frequency is increased to maintain compact component sizes, then die area and packaging area are reduced, but switching loss increases decreasing power conversion efficiency
Solution Approach 1:
The patent implements dynamic switching frequency adjustment by introducing an oscillation frequency control circuit that varies the switching frequency based on operating conditions. The frequency is dynamically changed according to the output voltage error signal, allowing the system to operate at lower frequencies when needed to reduce switching losses, while maintaining higher frequencies when compact component sizes are required, thus resolving the contradiction between switching loss and die area.
Solution Approach 2:
The patent changes the switching frequency parameter dynamically based on operating conditions. By adjusting the oscillation frequency control circuit's output, the system can modify the switching frequency to optimize performance. This parameter change allows the system to achieve lower switching losses at reduced frequencies without permanently increasing component sizes, as the frequency is adaptively controlled rather than fixed.
4Area of stationary object
If fixed high switching frequency is used to maintain compact component sizes, then die area and packaging area are reduced, but power conversion efficiency deteriorates under light load conditions
Solution Approach 1:
The patent implements dynamic switching frequency adjustment by introducing an oscillation frequency control circuit that varies the switching frequency based on operating conditions. The frequency is dynamically changed according to the output voltage error signal, allowing the system to operate at lower frequencies when needed to reduce switching losses, while maintaining higher frequencies when compact component sizes are required, thus resolving the contradiction between switching loss and die area.
Solution Approach 2:
The patent changes the switching frequency parameter dynamically based on operating conditions. By adjusting the oscillation frequency control circuit's output, the system can modify the switching frequency to optimize performance. This parameter change allows the system to achieve lower switching losses at reduced frequencies without permanently increasing component sizes, as the frequency is adaptively controlled rather than fixed.
Data Source
AI summary
Switching loss is reduced by decreasing the switching frequency of a PFC power supply in light load condition, whereas the switching frequency is maintained high in heavy load operation. Efficiency in light load operation is thus improved without enlarging a boosting inductor and an output smoothing capacitor. A capacitor is provided in a triangular wave generating circuit and the triangular wave generating circuit outputs a triangular wave by charging and discharging this capacitor. Charging and discharging of the capacitor are controlled by an oscillation frequency control circuit output current which is input to a comparator.