Boost Rectifier Soft Switching for 800 Hz Aviation Power Factor
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Solution Overview
Problem
Conventional single-phase power-factor correction (PFC) rectifiers face challenges in achieving low total harmonic distortion (THD) at high line frequencies, such as 800 Hz, due to limitations in current sensing techniques and the inability to deliver a good power factor without a neutral connection, leading to poor performance in aviation industry applications.
Innovation Solution
A boost rectifier with a non-linear compensation circuit that combines feedforward and output voltage feedback signals to achieve zero-voltage switching (ZVS) and low input-current THD, suitable for high-frequency line voltage applications, without requiring an additional wide-bandwidth active current-shaping control scheme.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional hard-switching CCM PFC boost rectifier is used, then efficiency and thermal performance are maintained, but current-shaping control bandwidth cannot reach 50 kHz required for 800 Hz line frequency
Solution Approach 1:
The patent changes the switching frequency parameter to 1 MHz (from conventional 100 kHz or lower), enabling the system to achieve the required 50 kHz current-shaping control bandwidth for 800 Hz line frequency applications while maintaining efficiency through soft-switching operation
Solution Approach 2:
The patent replaces conventional hard-switching control with soft-switching control using wide-bandgap devices, eliminating the need for complex wide-bandwidth current-shaping control schemes while achieving both high switching frequency and low THD
2Measurement precision
If conventional current sensing techniques are used, then simple implementation is achieved, but THD cannot be reduced below 5% at 800 Hz line frequency
Solution Approach 1:
The patent replaces conventional current sensing techniques with voltage sensing across the switch, eliminating propagation delay and processing time limitations of commercial gate drivers and digital controllers, thereby achieving accurate zero-crossing detection at 800 Hz with THD < 5%
3Ease of operation
If single-phase PFC rectifier operates without neutral connection, then power delivery is enabled, but triplen harmonic currents cannot flow resulting in poor power factor
Solution Approach 1:
The patent changes the operating frequency parameter to 1 MHz, which fundamentally alters the harmonic current behavior, enabling triplen harmonic currents to flow through the capacitor rather than requiring a neutral connection, thereby achieving both power delivery and good power factor without neutral wire
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 enables high power-factor efficiency with reduced common-mode noise and low THD, making it suitable for aviation industry applications, while eliminating the need for an active current-shaping control scheme.
Implementation Method 1
A boost rectifier with a non-linear compensation circuit that combines feedforward and output voltage feedback signals to achieve zero-voltage switching (ZVS)
Implementation Method 2
The switching converter stage includes a rectification and inductor circuit
Implementation Method 3
The switching converter stage includes series-connected first and second switches providing a common terminal therebetween, and a phase output capacitor connected between the first and second phase terminals
Implementation Method 4
Boost rectifier with soft switching and reduced common-mode noise
Data Source
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AI summary
A boost rectifier (300) that operates with a single-phase input voltage (VAC) includes (i) an input stage (305) receiving the single-phase input voltage (YAC) and including first and second input filter capacitors (C1, C2), (ii) a switching converter stage (310) coupled to the input stage (305) and including a rectification circuit and an inductor circuit, series-connected first and second switches (S1, S2) providing a common terminal (N) therebetween, and a phase output capacitor (CR), (iii) an output stage (320) that transfers energy stored in the phase output capacitor (CR) to an output load, (iv) a decoupling stage (315) that provides high-impedance decoupling between the switching converter stage (310) and the output stage (320), and (v) a control circuit (350) configured to operate the first and second switches (S1, S2) according to an output signal of a non-linear compensation circuit (355) that combines a feedforward signal derived from both the input and output voltages of the boost rectifier (300) with an output voltage feedback control signal.