Voltage Reservoir Power Supply for Pulsed Load RFI Reduction
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Solution Overview
Problem
Conventional switching mode power supplies for pulsed loads face challenges with high radio frequency interference (RFI) that require bulky and expensive RFI filters, especially when handling high power bursts, which can cause sudden voltage reductions on the line.
Innovation Solution
A power supply method and system that uses a voltage reservoir and a controlled DC/DC converter with a PWM switch to supply bursts of substantially constant voltage, computing and maintaining an average current to the reservoir during inactive cycles to ensure energy storage without draining it, and generating switching signals for the load switch to manage duty cycles, thereby reducing the need for a bulky RFI filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional switching mode power supply is used to supply high power bursts to a pulsed load, then the load can receive the required intermittent high power, but high radio frequency interference (RFI) is generated that reflects on the main supply source
Solution Approach 1:
The patent applies preliminary action by pre-charging a reservoir capacitor during the inactive portion of the switching cycle before the load requires power. This allows the capacitor to store energy in advance, which is then discharged to supply the pulsed load during the active portion, preventing RFI generation at the input while still delivering the required high power bursts to the load.
Solution Approach 2:
The reservoir capacitor serves as an intermediary energy storage element between the main power source and the pulsed load. It decouples the load switching operations from the input power source, absorbing the RFI-generating current variations and preventing them from reflecting on the main supply line while still providing the necessary power to the load.
2Object-generated harmful factors
If an RFI filter is added to suppress radio frequency interference on the main supply source, then RFI is reduced, but the filter becomes bulky and expensive
Solution Approach 1:
The patent converts the harmful RFI effect into a beneficial solution by using the reservoir capacitor to absorb the high-frequency switching currents locally. Instead of trying to filter out the RFI after it's generated, the design prevents RFI generation at the input by providing a local energy reservoir that handles the pulsed current demands, thereby eliminating the need for bulky RFI filters.
3Power
If the switch operates at low frequency to supply high amplitude current intermittently, then the load receives adequate power, but ripple current increases causing higher RFI
Solution Approach 1:
The patent segments the power delivery function into two separate components: the main power source provides continuous low-ripple power, while the reservoir capacitor handles the pulsed high-amplitude current delivery. This segmentation allows each component to operate in its optimal regime, with the capacitor absorbing the ripple current variations that would otherwise be generated by low-frequency switching.
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 allows for reduced RFI filter size or elimination, ensuring continuous energy supply to the load with minimal voltage fluctuations, thus maintaining stable line voltage and reducing conduction losses.
Implementation Method 1
providing bursts of substantially constant voltage from a voltage reservoir (18) to a switched load (12)
Implementation Method 2
a first DC/DC converter stage (14) converting the primary power source voltage to a voltage on the reservoir capacitor (18)
Implementation Method 3
The switch 'chops' a low voltage input DC source, thus converting it to a high-ripple pulsed AC voltage
Data Source
Figure 1
Figure 2
Figure 3a~4
AI summary
A method for supplying bursts of substantially constant voltage to a switched load via a voltage reservoir. Based on a predetermined current that is to be sourced by the load during an active portion of a switching cycle, computing an average current that should be fed to the voltage reservoir during an inactive portion of the switching cycle to ensure that sufficient energy will stored in the voltage reservoir to supply the load without completely draining the voltage reservoir. Supplying continuous energy to the voltage reservoir at a substantially constant current equal in magnitude to said average current.