Three-Phase Rectifier PWM Control for Small Passive Components
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional three-phase rectifiers require large capacity reactors and capacitors to reduce pulsation of DC voltage and harmonics in input current, leading to increased costs and complex control systems, while existing solutions do not effectively maintain constant DC voltage and minimize harmonic currents with small capacity components.
Innovation Solution
A three-phase rectifier system incorporating a full-wave rectifier circuit, a bidirectional switch circuit, and a controller that generates switching patterns based on detected phase voltages to control the bidirectional switch circuit, allowing for reduced pulsation of DC voltage and harmonics even with small capacity capacitors and reactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If reactors and capacitors of large capacity are used to store power and reduce non-conductive sections, then harmonic current is reduced and non-conductive sections are minimized, but cost increases and circuit size becomes larger
Solution Approach 1:
The patent employs PWM (Pulse Width Modulation) technology to dynamically control the switching of semiconductor devices, enabling the rectifier to actively manage power flow and minimize non-conductive sections. This dynamic control allows the system to achieve harmonic current reduction without requiring large capacity passive components, as the switching action actively compensates for power fluctuations.
Solution Approach 2:
The invention changes the operating parameters by using high-frequency switching of semiconductor devices instead of relying on low-frequency passive energy storage. By adjusting the switching frequency and duty cycle, the system achieves effective power compensation and harmonic reduction with much smaller capacitor and reactor capacities compared to conventional passive systems.
2Stability of the object's composition
If a capacitor of large capacitance is connected on the DC side to remove DC voltage ripple, then DC voltage stability is improved, but cost increases and circuit size becomes larger
Solution Approach 1:
The patent uses active PWM control to dynamically regulate DC voltage by adjusting the switching patterns of semiconductor devices. This active control mechanism compensates for voltage fluctuations in real-time, achieving stable DC voltage output without requiring large capacity capacitors that would be needed in passive systems.
Solution Approach 2:
The invention incorporates feedback control where the DC voltage is continuously monitored and used to adjust the switching patterns of the semiconductor devices. This closed-loop control ensures that DC voltage remains stable by automatically compensating for any deviations, eliminating the need for large capacity energy storage components.
3Stability of the object's composition
If DC voltage is detected to control input current in an active system, then stable DC voltage is achieved, but control becomes more complicated and high withstand voltage components are required
Solution Approach 1:
The patent simplifies control by changing the detection parameter from DC voltage to AC input voltage. By detecting the AC input voltage and using it to directly control the switching patterns, the system achieves effective power compensation without the complexity of DC voltage detection and control loops, reducing both control complexity and component withstand voltage requirements.
4Stability of the object's composition
If only voltage step-up function is provided in an active system, then DC voltage stability is maintained, but cost increases due to high withstand voltage components
Solution Approach 1:
The patent implements a dual-function rectifier system that can perform both voltage step-up and voltage step-down operations using the same semiconductor devices. This multi-functionality is achieved through configurable switching patterns that can operate in different modes, eliminating the need for separate high-voltage and low-voltage circuits and reducing overall component withstand voltage requirements.
Solution Approach 2:
The invention uses dynamically controllable semiconductor switching devices that can adapt their operating mode based on the required voltage transformation. By actively adjusting the switching patterns and duty cycles, the system can achieve both voltage elevation and reduction functions, replacing static high-voltage components with flexible, lower-voltage-rated active devices.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A three-phase rectifier converts three-phase alternating current (AC) power supplied from a three-phase AC power supply into direct current (DC) power. The three-phase rectifier includes a full-wave rectifier circuit, a bidirectional switch circuit, and a controller. The full-wave rectifier circuit rectifies three-phase AC power to DC power. The bidirectional switch circuit switches on and off inputs of respective phases from the three-phase AC power supply to the full-wave rectifier circuit. The controller detects voltages of the respective phases of the three-phase AC power supply, generates switching patterns for the respective phases to switch the bidirectional switch circuit on and off based on the detected voltages of the phases, and controls switching of the bidirectional switch circuit based on the switching patterns.