Rectifier Circuit With Active Current Injection
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Solution Overview
Problem
Existing rectifier circuits with current injection suffer from high mains reactions, require large magnetic components and filter capacitors, and have reduced efficiency due to non-sinusoidal input currents and harmonic distortions.
Innovation Solution
A three-phase six-pulse rectifier circuit with a three-pole control circuit using controllable semiconductor valves, where the injection current is selectively fed into the phase that remains currentless, allowing for active regulation of control currents and injection current to generate sinusoidal input currents, reducing the need for large magnetic components and filter capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If current injection is used to reduce mains reactions and achieve sinusoidal input currents, then input current quality is improved, but the circuit requires additional switching elements and control complexity increases
Solution Approach 1:
The patent employs dynamic switching elements (IGBTs or MOSFETs) in the three-pole circuit that can be actively controlled to inject currents dynamically into the rectifier circuit. This dynamic control allows the circuit to adaptively compensate for harmonic distortions and mains reactions in real-time, achieving sinusoidal input currents while managing the added complexity through intelligent switching strategies
Solution Approach 2:
The control unit receives feedback signals from the rectifier circuit's input currents and voltages, processes this information, and generates appropriate control signals for the switching elements. This closed-loop feedback mechanism enables the system to automatically adjust the injection currents to maintain sinusoidal waveforms and minimize mains reactions, resolving the contradiction between improved current quality and increased control complexity
2Stability of the object's composition
If large magnetic components and filter capacitors are used to smooth rectifier output and reduce current distortion, then output voltage stability is improved, but device size and weight increase
Solution Approach 1:
The patent replaces traditional passive mechanical filtering components (large inductors and capacitors) with an active electronic control system consisting of switching elements and a control unit. This electronic substitution achieves voltage stabilization and current waveform improvement through active current injection and PWM control, eliminating the need for bulky magnetic components and large filter capacitors while maintaining output stability
Solution Approach 2:
The control unit dynamically adjusts switching parameters (duty cycle, frequency, and timing) of the switching elements to optimize the injection current characteristics. By changing these electrical parameters in real-time based on load conditions and input voltage variations, the system achieves stable output voltage without requiring oversized passive components, thus reducing device weight and size
3Shape
If injection current is supplied to all three phases simultaneously, then mains current sinusoidality is improved, but transformer size and weight increase due to low-frequency loading
Solution Approach 1:
The patent applies current injection selectively to specific phases rather than all three phases simultaneously. The control unit identifies which phases require current compensation based on instantaneous current measurements and injects currents only into those phases needing correction. This localized approach achieves sinusoidal mains currents while avoiding the low-frequency loading that would require large, heavy transformers
Solution Approach 2:
The system dynamically determines and adjusts which phases receive injection currents based on real-time operating conditions. The switching elements are controlled to inject currents phase-specifically and time-variably, adapting to load changes and voltage imbalances. This dynamic, selective injection achieves waveform improvement without the need for oversized transformers designed for continuous three-phase low-frequency loading
4Device complexity
If rectifier circuit operates with non-sinusoidal input currents, then circuit simplicity is maintained, but efficiency decreases due to harmonic content and power losses
Solution Approach 1:
The patent replaces the passive, lossy rectifier operation with an active controlled system using switching elements (IGBTs or MOSFETs) and PWM control. This substitution enables the circuit to draw sinusoidal currents from the mains by actively managing the switching timing and duration, significantly reducing harmonic content and associated power losses while maintaining relatively simple circuit topology through the use of modern power semiconductor devices
Solution Approach 2:
The control unit dynamically adjusts switching parameters (frequency, duty cycle, and phase timing) to optimize power factor and minimize harmonic distortion. By changing these parameters in real-time based on load conditions, the system maintains high efficiency across varying operating points while keeping the circuit structure relatively simple, achieving low power losses without complex passive filtering components
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 low mains reactions, sinusoidal input currents in phase with mains voltages, improved efficiency, and the ability to operate with variable loads without large magnetic or filter components, enhancing the rectifier circuit's performance.
Implementation Method 1
a rectifier circuit with a three-phase six-pulse rectifier arrangement of semiconductor valves, preferably a bridge rectifier circuit of diodes
Implementation Method 2
In typical rectifier circuits, the rectifier current is routed through a choke connected to an output capacitor in parallel with the output to reduce distortion in the mains currents, smooth the rectifier current waveform
Implementation Method 3
a rectifier arrangement of diodes downstream of the bridge (the so-called DC side of the rectifier circuit)
Data Source
Figure 1~2
Figure 3~4
Figure 4a~4h
AI summary
The present invention relates to a rectifier circuit with a three-phase rectifier arrangement (1) of semiconductor valves (2), preferably a bridge rectifier circuit of diodes, wherein said rectifier arrangement (1) has a three-phase mains input (3) and a direct current output (4), and at least one of three phases (U,V,W) at the mains input (3) is connected to a first pole connection (A) of a three-pole circuit (5) for diverting an injection current (ih3) into the three-pole circuit (5). The invention proposes that each phase (U,V,W) can be connected with a respective switch element (S1; S2, S3) to the first pole connection (A) of the three-pole circuit (5), and a second and third pole connection (B,C) of the three-pole circuit (5) is connected to a respective output line (PDC,NDC) of the direct current output (4) for control currents (icp,icn), wherein the three-pole circuit (5) has controllable semiconductor valves (Scp+,Scp-,Scn+,Scn-), preferably IGBTs, for active regulation of the control currents (icp,icn) and/or of the injection current (ih3), and at least one choke (7) is arranged on one of the output lines (PDC,NDC) on the direct current output (4), and a load (6) which can changed over time is provided at the direct current output (4).