Three-Phase Rectifier with Independent Smoothing Coils
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Solution Overview
Problem
Existing three-phase AC/DC conversion systems using autotransformers with 20° phase shift between output systems suffer from increased residual ripples in DC voltage and harmonic reinjections into the network, leading to higher mass and inefficiency, particularly when power is not balanced.
Innovation Solution
A device with independent smoothing means for each three-phase system, comprising a rectifying bridge and smoothing coils connected in common mode, reduces the mass of the magnetic circuit by limiting common and differential mode voltages through capacitors and leakage inductance, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If an autotransformer with 20° phase shift is used to reduce power through the magnetic circuit, then the mass of the magnetic circuit is reduced, but the residual ripples of DC voltage increase
Solution Approach 1:
The patent divides the smoothing function into three independent segments, one for each rectifier bridge output. Each segment has its own smoothing means (inductor and capacitor), allowing independent optimization of ripple reduction for each phase while maintaining overall system balance and reducing total magnetic circuit mass.
Solution Approach 2:
The patent changes the phase shift parameter from the conventional 40° to 20°, which reduces the power flowing through the magnetic circuit and thereby reduces the mass of the magnetic circuit. This parameter change is compensated by adding independent smoothing means to each output to maintain voltage stability.
2Object-generated harmful factors
If the number of rectifier bridges is increased to reduce harmonic reinjections, then the residual ripples and harmonic reinjections are reduced, but the device complexity and mass increase
Solution Approach 1:
The patent merges the smoothing functions for all three rectifier bridge outputs into a single autotransformer structure with 20° phase shift. Instead of using separate smoothing chokes for each bridge (which would require multiple magnetic circuits), the invention uses one shared magnetic circuit with independent smoothing means, reducing overall complexity and mass.
3Reliability
If smoothing chokes are added to reduce residual ripples, then the voltage stability improves, but the overall mass of the device increases
Solution Approach 1:
The autotransformer structure serves multiple functions simultaneously: it provides the 20° phase shift to reduce magnetic circuit power, acts as a common magnetic circuit for all three rectifier bridges, and incorporates independent smoothing means for each output. This multi-functionality eliminates the need for separate smoothing chokes, reducing overall mass while maintaining voltage stability.
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 configuration effectively reduces the mass of the device while minimizing residual ripples and harmonic reinjections, improving the efficiency and performance of the AC/DC conversion process.
Implementation Method 1
an autotransformer supplied with three-phase voltage and delivering several three-phase systems
Implementation Method 2
rectifying means for three-phase systems, characterized in that the rectifying means comprise, specific to each system, a rectifying bridge
Implementation Method 3
smoothing means associated with each system are independent of one another
Implementation Method 4
limiting common and differential mode voltages through capacitors and leakage inductance
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a device for rectifying a three-phase alternating voltage. The invention relates to the conversion of alternating electric power (AC) into direct power (DC). The inventive device includes an autotransformer (AT) which is supplied with three-phase voltage and delivers several three-phase systems (S1, S2, S3). The device also includes means (R) for rectifying the three-phase systems (S1, S2, S3). Each system includes three phases which are phase-shifted by 120° in relation to one another. According to the invention, the rectifying means (R) include a bridge rectifier (P1, P2, P3) and smoothing means (L1, L2, L3) which are specific to each system.