PFC Voltage Controller With Dynamic Thresholds
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Solution Overview
Problem
In single-phase AC power supplies, the DC bus voltage fluctuations due to low frequency power signals lead to reduced capacitor utilization, increased costs, and power losses, as modern converters struggle to maintain a stable power factor during transients and perturbations.
Innovation Solution
A digital power factor correction voltage controller employing a linear PI compensator, non-linear gain, peak hysteretic control, and output power feedforward with a moving average filter, optimized to regulate DC bus voltage and maintain a high power factor by minimizing voltage excursions and optimizing energy storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the DC bus capacitance is limited due to size and cost constraints, then the converter is more effective at high frequency, but the capacitor utilization is reduced and voltage regulation becomes difficult
Solution Approach 1:
The patent implements dynamic voltage threshold adjustment where the minimum and maximum voltage thresholds are not fixed but adapt based on operating conditions. The controller dynamically modifies these thresholds to optimize capacitor utilization while maintaining stable regulation, allowing the system to respond flexibly to varying load and frequency conditions without requiring oversized capacitance.
Solution Approach 2:
The invention changes the parameter of voltage thresholds from static to dynamic values. By adjusting the minimum and maximum voltage thresholds based on real-time operating conditions, the system optimizes the utilization of limited capacitor energy storage while maintaining effective voltage regulation across different frequency ranges.
2Adaptability or versatility
If the DC bus voltage is allowed to swing over a wide band to accommodate energy storage variations, then the converter can handle low frequency power signals, but the power stages experience increased losses and the system efficiency decreases
Solution Approach 1:
The system dynamically adjusts voltage thresholds based on operating conditions rather than allowing uncontrolled voltage swings. This dynamic adaptation enables the converter to handle varying frequency signals while maintaining voltage within an optimized range that minimizes power stage losses.
Solution Approach 2:
The controller continuously monitors the DC bus voltage and adjusts the voltage thresholds and control parameters based on feedback from the actual voltage levels. This closed-loop control ensures that voltage excursions are minimized while still accommodating the energy storage variations, thereby reducing power losses in the power stages.
3Quantity of substance
If the input power is pulsed or modulated in amplitude to match output power variations, then the internal energy storage requirements are reduced, but the input power factor is severely affected and power losses increase
Solution Approach 1:
Instead of fully pulsing the input power to match output variations, the system applies partial modulation through dynamic voltage threshold adjustment. This partial action reduces the need for large energy storage capacitance while avoiding the severe power factor degradation that would result from complete power pulsing.
Solution Approach 2:
The invention changes the control parameter from direct power pulsing to voltage threshold modulation. By dynamically adjusting the voltage thresholds, the system achieves effective power factor correction and reduces the required internal energy storage without the harmful effects of severe input power pulsing.
4Device complexity
If a traditional control loop is used without dynamic threshold adjustment, then the system is simpler to implement, but the capacitor utilization is reduced and voltage regulation is insufficient during transients
Solution Approach 1:
The patent introduces dynamic voltage threshold adjustment to a control loop, adding adaptability while maintaining relative simplicity. The dynamic thresholds enable proper voltage regulation during transients and optimize capacitor utilization without requiring a completely complex control architecture.
Solution Approach 2:
The control loop incorporates feedback mechanisms that monitor voltage levels and dynamically adjust thresholds based on actual operating conditions. This feedback-based adaptation improves voltage regulation during transients and optimizes capacitor utilization while keeping the control structure manageable.
Data Source
AI summary
A power factor correction voltage controller is disclosed. In one embodiment, the controller has a linear PI compensator, a moving average filter, a non-linear error circuit, a hysteretic peak control, and an output power feedforward. The power factor correction voltage controller provides regulation of maximum and minimum voltage values but without allowing large periodic fluctuations in the input power/current.