Multiple-Output Active Line Filter with Ripple Attenuation
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Solution Overview
Problem
Conventional active line filters are inadequate for systems requiring multiple output power forms and cannot regulate input current to a specific DC level, leading to excessive ripple current that exceeds the power source's capability, particularly in applications like cryocooler power systems and high-power diode drivers for laser pump arrays.
Innovation Solution
A multiple-output non-isolated active line filter with a current mode control continuous current boost converter, utilizing a very low bandwidth control loop with input voltage feedforward and output load feedforward, regulates input current to a set DC level, providing multiple output power forms while attenuating ripple current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional non-isolated converter active line filters are used, then input current regulation is achieved, but only a single output power form is provided
Solution Approach 1:
The inductive element is designed with multiple windings (first winding coupled to first output, second winding coupled to second output) that share a common core. This allows a single filter circuit to provide multiple output power forms simultaneously, making the device universal for systems requiring different voltage levels or power configurations without needing separate filters for each output.
Solution Approach 2:
Multiple output circuits are merged into a single integrated filter structure where the inductive element with multiple windings serves as the common filtering component for all outputs. The control circuitry and energy storage elements are also integrated to work together, reducing overall device complexity compared to using separate filters for each output.
2Object-affected harmful factors
If passive LC filters are used to attenuate time-varying current, then ripple current attenuation is achieved, but the filters are large and heavy
Solution Approach 1:
The patent replaces traditional passive mechanical LC filters with an active line filter that uses active electronic components (transistor, PWM controller, error amplifier, energy storage capacitors) to achieve current regulation and ripple attenuation. This electronic active system achieves the same filtering function with significantly reduced weight and size compared to passive LC components.
Solution Approach 2:
The filter operates by dynamically changing parameters through PWM control of the transistor switching, adjusting the duty cycle to regulate input current and attenuate ripple. This dynamic parameter control allows effective ripple current attenuation without requiring the large physical components needed for passive filters.
3Power
If pulsed current is drawn from power source, then high power delivery is achieved, but the pulsed currents exceed the capability of the power system
Solution Approach 1:
The error amplifier continuously monitors the output voltage and provides feedback to the PWM controller, which adjusts the transistor duty cycle to maintain stable operation. This feedback mechanism ensures that while high power is delivered to the load, the input current ripple is controlled and kept within the power system's capability limits.
Solution Approach 2:
The transistor switches periodically at high frequency, converting continuous input current into controlled pulsed current that delivers high power to the load while the average input current remains within system capabilities. The periodic switching action, controlled by PWM, allows power delivery exceeding instantaneous system limits while maintaining overall current within safe operating parameters.
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 achieves >30 dB ripple attenuation, maintains excellent output voltage regulation, and ensures input current never exceeds the set DC level, resulting in high efficiency (>90%) and reduced size and weight, suitable for applications with limited power source capabilities.
Implementation Method 1
an inductive element... a first winding on the inductive element; and a second winding on the inductive element
Implementation Method 2
a first energy storage capacitor... a second energy storage capacitor
Data Source
AI summary
An active line filter (ALF) with multiple outputs includes a first output providing a first output power form having a first output current, the first output power form being coupled to a first winding on an inductive element; and a second output providing a second output power form having a second output current, the second output power form being coupled to a second winding on the inductive element. An input receives an input power form having an input current and an input voltage. A pulse-width modulator (PWM) provides a PWM output signal controlling timing of switching of a transistor to control application of the input voltage of the input power form to the first winding of the inductive element. An error amplifier receives a signal indicative of the first output voltage and generating an error amplifier output signal.