Power Converter Control Using Shared Carrier Signal
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Solution Overview
Problem
Conventional direct power converter apparatuses face increased operational load and complex control circuitry due to the generation of trapezoidal waveform instruction signals and the need for separate carrier signals for PWM rectifiers and inverters, leading to complicated modulation waveform generation and circuit complexity.
Innovation Solution
A power converter apparatus with an instruction signal generating part that generates trapezoidal waveform instruction signals using prescribed expressions, a carrier signal generating part, and a converting section that converts three-phase AC voltage to DC or vice versa, utilizing a single carrier signal for both the converter and inverter sections to simplify the control circuit and reduce operational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the direct power converter apparatus generates the trapezoidal waveform instruction signal by calculation on the basis of an input current instruction, then the desired AC output can be obtained, but the operational load of the control section increases
Solution Approach 1:
The patent pre-calculates and stores the relationship between input current instructions and trapezoidal waveform instruction signals in a lookup table. During operation, the control section simply retrieves pre-computed values from the table rather than performing real-time calculations, significantly reducing operational load while maintaining output accuracy
Solution Approach 2:
The patent creates a simplified copy of the complex calculation process by storing pre-computed trapezoidal waveform data in a lookup table. This tabular copy replaces the need for real-time mathematical computations, reducing the control section's operational burden while preserving the desired waveform characteristics
2Manufacturing precision
If the direct power converter apparatus transforms the carrier waveform on the PWM inverter side, then the output voltage can be controlled, but the modulation waveform generation becomes complicated and the control circuit becomes complicated
Solution Approach 1:
The patent merges the carrier signal generation for the PWM rectifier and PWM inverter into a single shared carrier signal. This eliminates the need for separate carrier generators and their associated control circuits, simplifying the overall control architecture while maintaining precise output voltage control through unified modulation
Solution Approach 2:
The patent creates a universal carrier signal that serves dual purposes for both the PWM rectifier and PWM inverter sections. This single carrier signal enables both sections to perform their respective voltage control functions without requiring separate transformation circuits, reducing complexity while preserving control precision
3Adaptability or versatility
If separate carrier generator circuits are used for the PWM rectifier and the PWM inverter, then each section can be controlled independently, but the control section circuit becomes complicated
Solution Approach 1:
The patent combines the carrier signal generation function into a single shared circuit that serves both the PWM rectifier and PWM inverter sections. This merged approach maintains independent control capability through separate modulation index settings while eliminating redundant circuitry, thus reducing overall control section complexity
Data Source
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AI summary
A converter section 1 that converts a three-phase ac input voltage into a dc voltage, and an inverter section 2 that converts the dc voltage converted by the converter section 1 into a prescribed three-phase ac output voltage are provided. The converter section 1 converts the three-phase ac input voltage into the dc voltage on the basis of trapezoidal waveform voltage instruction signals Vr*, Vs*, Vt* from a trapezoidal waveform voltage instruction signal generating part 11 and a carrier signal from a carrier signal generating part 15. The inverter section converts the dc voltage converted by the converter section 1 into a prescribed three-phase ac output voltage on the basis of an inverter section instruction signal corrected by an instruction signal correcting part 14, 22, 23. The trapezoidal waveform voltage instruction signal generating part 11 generates sloped regions of the trapezoidal waveform voltage instruction signals Vr*, Vs*, Vt* by using a prescribed table.