Power Factor Correction Circuit Transient Response
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Solution Overview
Problem
Previous power factor correction circuits have a limited bandwidth, resulting in a slow response to output voltage transients due to a low control loop bandwidth, which is typically about ten times less than the AC input frequency, leading to inefficient power utilization.
Innovation Solution
A power factor correction circuit with a wider loop bandwidth is achieved by using a sample and hold circuit with a transient detector to bypass the stored feedback signal directly to the amplifier, allowing rapid response to output voltage transients and increasing the loop bandwidth to at least 20 Hz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the bandwidth of the control loop is kept very low to reduce ripple in the output voltage, then the ripple is reduced, but the response time to transients becomes slow
Solution Approach 1:
The patent implements a dynamic bandwidth control mechanism where the control loop bandwidth is adjusted based on operating conditions. During transient events, the bandwidth is increased to improve response speed, while during steady-state operation, the bandwidth is reduced to minimize output voltage ripple. This dynamic adjustment resolves the contradiction by allowing the system to optimize for different performance requirements at different times.
Solution Approach 2:
The patent changes the bandwidth parameter of the control loop based on detected transient conditions. By monitoring the control signal and detecting transient events, the system modifies the bandwidth parameter dynamically - increasing it during transients to improve response time, and decreasing it during normal operation to reduce ripple, thus resolving the performance contradiction.
2Speed
If the bandwidth of the control loop is increased to improve response to transients, then the response time is reduced, but the ripple in output voltage increases
Solution Approach 1:
The control loop dynamically adjusts its bandwidth based on the detected operating state. When transients are detected through monitoring the control signal, the bandwidth is increased to improve response time. When the system is in steady-state, the bandwidth is reduced to minimize output voltage ripple. This dynamic behavior allows the system to achieve fast transient response without sacrificing steady-state stability.
Solution Approach 2:
The bandwidth parameter is changed dynamically based on transient detection. The system monitors the control signal for transient conditions and adjusts the bandwidth parameter accordingly - increasing it during transients to improve response speed, and decreasing it during normal operation to reduce output voltage ripple, thereby resolving the contradiction between speed and stability.
3Stability of the object's composition
If the loop bandwidth is limited to about ten to twelve Hz to reduce ripple, then the ripple is minimized, but the power factor correction efficiency is reduced
Solution Approach 1:
The patent implements dynamic bandwidth adjustment that adapts to transient conditions. During transient events, the bandwidth is increased beyond the traditional 10-12 Hz limit to improve power factor correction efficiency and response time. During steady-state operation, the bandwidth is maintained at the lower limit to minimize ripple. This resolves the contradiction by allowing higher efficiency when needed without compromising steady-state stability.
Solution Approach 2:
The loop bandwidth parameter is changed dynamically based on transient detection in the control signal. When transients are detected, the bandwidth is increased to improve power factor correction efficiency. During normal operation, the bandwidth is kept at the lower value to minimize ripple. This parameter change strategy resolves the contradiction between ripple minimization and correction efficiency.
Data Source
AI summary
In one embodiment, a power factor correction circuit is configured to use a stored value of a feedback signal to assist in regulating the value of an output voltage and to bypass the sample and hold circuit if the output voltage increase to an upper limit or decreases to a lower limit.