Adjustable Reference Voltage for Ripple Suppression in Power Supply
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Solution Overview
Problem
Conventional power supply apparatuses employing switching methods to generate DC voltage from AC power struggle to effectively suppress ripples in the output current, especially when there are offsets in the comparator and operational amplifier, leading to increased ripple rates or excessive suppression, particularly in regions with low dimming ratios.
Innovation Solution
A power supply apparatus with a voltage conversion circuit, a reference voltage generating circuit, a constant current control circuit, and a reference voltage adjustment circuit that includes a differential circuit, a pull-up circuit, and a pull-down circuit to adjust the reference voltage based on the output voltage and current detection voltage, ensuring the ripple in the output current is suppressed to a predetermined rate without increasing the ripple rate or causing excessive suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high limiting current value is set in the constant current circuit, then the output current can be maintained at higher levels, but excess loss occurs in the transistor for controlling the electric current
Solution Approach 1:
The patent applies dynamics by making the reference voltage adjustable rather than fixed. The reference voltage adjustment circuit dynamically changes the reference voltage value based on operating conditions, allowing the constant current circuit to adapt its current limiting behavior. This resolves the contradiction by enabling the system to operate at higher current levels when needed while minimizing transistor loss through optimized reference voltage settings.
Solution Approach 2:
The patent changes the parameter of reference voltage to resolve the contradiction. By adjusting the reference voltage value, the system can optimize the balance between output current level and transistor loss. The reference voltage adjustment circuit provides a mechanism to vary this critical parameter, allowing the system to achieve high productivity when required while maintaining energy efficiency under different operating conditions.
2Loss of energy
If the setting of the current value limited by the constant current circuit is too low, then transistor loss is reduced, but the transistor cannot absorb ripple voltage and ripple suppression becomes insufficient
Solution Approach 1:
The dynamic adjustment of reference voltage enables the system to maintain adequate ripple suppression capability while minimizing transistor loss. By adaptively changing the reference voltage based on operating conditions, the system ensures the transistor operates in an optimal region that provides both efficient loss characteristics and sufficient ripple absorption capability.
Solution Approach 2:
The patent uses parameter changes of the reference voltage to resolve this contradiction. By varying the reference voltage value, the system can optimize the transistor's operating point to achieve an balance between reducing transistor loss and maintaining adequate ripple suppression performance.
3Ease of manufacture
If simple methods such as one convertor method or constant-on method are used to suppress higher harmonic waves, then costs are not increased, but ripples relying on AC power supply frequency occur in the output voltage
Solution Approach 1:
The patent converts the harmful ripple voltage into a beneficial control signal. The ripple detection circuit detects the AC-powered ripple in the output voltage, and this detected ripple signal is then used by the reference voltage adjustment circuit to generate compensating adjustments. This transforms the harmful ripple into a useful feedback signal that drives the correction mechanism.
Solution Approach 2:
The patent implements feedback by detecting the ripple voltage and using this information to adjust the reference voltage. The ripple detection circuit continuously monitors the output voltage for ripple components, and this feedback information is fed to the reference voltage adjustment circuit, which modifies the reference voltage accordingly to suppress the ripple effect in the output current.
4Device complexity
If offset exists in comparator and operational amplifier, then circuit simplicity is maintained, but ripple rate increases or excessive suppression occurs
Solution Approach 1:
The patent uses feedback to compensate for offset in the comparator and operational amplifier. The ripple detection and reference voltage adjustment mechanism continuously monitors the actual output and makes corrections based on detected ripple, thereby compensating for the effects of component offsets. This feedback approach maintains circuit simplicity while improving ripple suppression accuracy.
Solution Approach 2:
The system performs self-correction by using its own output ripple as the basis for adjustment. The ripple detection circuit detects the actual ripple present in the system, and the reference voltage adjustment circuit uses this information to automatically adjust the reference voltage to compensate for offsets and other non-ideal characteristics, making the system self-correcting without requiring external calibration.
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
The solution effectively suppresses ripples in the output current, reducing losses in the transistor and ensuring stable operation even with offsets in the control circuit components, while maintaining efficient harmonic wave suppression and minimizing flickering in LED lighting.
Implementation Method 1
a voltage conversion circuit (DC/DC convertor) that generates DC voltage from an input power supply
Implementation Method 2
a current controller that is provided on a current path in which output current flows and that is controlled by voltage
Data Source
AI summary
A power supply apparatus includes a voltage conversion circuit, a reference voltage generating circuit, a constant current control circuit which includes a current controller and a differential circuit which controls the current controller based on the reference voltage and current detection voltage showing a size of the output current, and wherein an electric current on the current path is controlled by the current controller a reference voltage adjustment circuit which adjusts a first reference voltage generated by the reference voltage generating circuit to converge a ripple occurring in the output current to a predetermined ripple rate or less, based on a voltage of a first potential point set on the current path from an output portion on a high potential side of the voltage conversion circuit to the current controller and a control voltage of the current controller.