PFC Power Converter Burst Control for Light-Load Driving Loss
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Solution Overview
Problem
Conventional power converters with power factor correction functions experience increased power consumption and reduced efficiency under no-load or light-load conditions due to the need for frequent pulse generation to stabilize output voltage, leading to increased driving loss.
Innovation Solution
A power converter with a controller that enables a burst mode operation, controlling the conduction phase angle interval of the input current to minimize switching of power switches when the input current is low, transferring energy stored in the inductor only when the current exceeds a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power converter outputs more pulses to stabilize the output voltage when the instantaneous value of the input voltage is low, then the output voltage stability is improved, but the driving loss increases
Solution Approach 1:
The patent implements burst mode operation where the power converter operates in periodic cycles, alternating between active switching periods and idle periods. During burst mode, the converter processes input voltage in concentrated bursts rather than continuous operation, reducing the total number of switching pulses needed while maintaining output voltage stability through energy accumulation in the inductor during active periods.
2Reliability
If the power converter outputs more pulses when the instantaneous value of the input voltage is low, then the output voltage stability is improved, but the conversion efficiency deteriorates
Solution Approach 1:
The converter operates in periodic burst cycles, concentrating energy transfer operations into specific time windows when input voltage conditions are favorable, rather than continuously operating at low efficiency points. This periodic operation allows the system to recover and accumulate energy during idle periods, maintaining output stability while improving overall conversion efficiency.
Solution Approach 2:
The patent dynamically changes operational parameters including switching frequency, duty cycle, and burst duration based on input voltage conditions. When input voltage is low, the system adjusts by extending the burst duration or increasing the number of pulses within the burst, rather than maintaining constant switching frequency, thereby optimizing conversion efficiency across varying input conditions.
3Reliability
If the power converter operates continuously to maintain output voltage, then the output voltage stability is improved, but the power consumption increases
Solution Approach 1:
The power converter implements burst mode operation where continuous operation is replaced by periodic active periods followed by idle periods. During active burst periods, the converter actively switches power devices to transfer energy and maintain output voltage. During idle periods between bursts, the converter reduces or stops switching operations, significantly reducing power consumption while the output capacitor maintains voltage stability.
Solution Approach 2:
The output capacitor serves a dual function: it smooths output voltage during active switching periods and maintains output voltage stability during idle burst periods without requiring active converter operation. This self-service capability of the capacitor allows the converter to enter low-power states while maintaining reliable output voltage.
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
This approach reduces driving loss and increases efficiency by minimizing power consumption and enhancing conversion efficiency under no-load or light-load conditions.
Implementation Method 1
The power converter includes at least one inductor... transferring energy stored in the inductor only when the current exceeds a predetermined threshold
Implementation Method 2
The driver circuit drives the switching of the at least one power switch based on the PWM signal so as to control the power factor correction circuit to convert the input voltage into the output voltage
Implementation Method 3
The power converter includes at least one inductor, at least one power switch, and an output capacitor... to stabilize the output voltage
Data Source
AI summary
A power converter with reduced power consumption receives an input voltage and provides an output voltage to supply power to a load. The power converter includes a power factor correction circuit, a driver circuit, and a controller. The power factor correction circuit includes at least one inductor and an output capacitor. When the controller determines that an effective value of an input current is correspondingly lower than a current lower limit, a specific time period starts based on the output voltage reaching a voltage lower limit, and the specific time period ends based on the output voltage reaching a voltage upper limit. In the specific time period, the controller enables the driver circuit based on the input current being correspondingly greater than a predetermined threshold so as to continuously transfer the energy stored in the at least one inductor to the output capacitor.