Power Converter Controller Using Correction Vector for Stable Current Detection
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Solution Overview
Problem
In power conversion systems, stable current detection is challenging when voltage vectors are output for very short times due to difficulties in accurately detecting current during brief output periods.
Innovation Solution
A power conversion apparatus with a controller that generates a synthetic vector by synthesizing a correction vector with a voltage command vector, adjusts the output time of voltage vectors, and uses a correction vector generator to adjust the output time ratios, ensuring stable current detection by preventing output times from falling below a certain threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the duty ratio of the PWM signal is corrected to enable current detection in one carrier period, then current detection stability is improved, but the output time of voltage vectors becomes extended
Solution Approach 1:
The patent applies preliminary action by calculating and storing the minimum output time requirements for each voltage vector in advance. The correction vector generator uses these pre-calculated minimum times to adjust the output time ratios, ensuring that current detection stability is maintained without unnecessarily extending the output time. This resolves the contradiction by preparing the necessary correction data beforehand rather than calculating it in real-time during operation.
Solution Approach 2:
The patent changes the parameter of output time ratio for each voltage vector by introducing a correction vector that adjusts the original time ratios. The correction vector modifies the output time parameters based on pre-calculated minimum times, allowing the system to maintain stable current detection while minimizing the extension of output time. This parameter adjustment resolves the contradiction by optimizing the balance between detection stability and time efficiency.
2Measurement precision
If the output time of voltage vectors is extended to ensure stable current detection, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent uses preliminary action by pre-calculating the minimum output time requirements for stable current detection for each voltage vector and storing them in a lookup table. During operation, the correction vector generator quickly retrieves these pre-calculated values and applies the necessary corrections, avoiding unnecessary time extensions while ensuring detection accuracy. This resolves the contradiction by having the optimal time parameters ready in advance.
Solution Approach 2:
The patent implements feedback by using the correction vector to adjust the output time ratios based on the actual operating conditions. The correction vector generator continuously monitors the voltage vector output times and applies corrections to maintain the minimum required output times for accurate current detection. This feedback mechanism ensures that the system maintains measurement precision while minimizing the impact on productivity by only extending times when necessary.
3Reliability
If a correction vector is synthesized with the voltage command vector to adjust output times, then current detection stability is improved, but device complexity increases
Solution Approach 1:
The patent reduces device complexity by applying preliminary action - all the complex calculations for determining minimum output times are performed in advance and stored in a lookup table. The correction vector generator simply retrieves pre-calculated correction values based on the current voltage vector and applies them, avoiding the need for complex real-time calculations. This resolves the contradiction by moving the computational complexity to the initialization phase rather than the operational phase.
Solution Approach 2:
The patent introduces an intermediary element - the correction vector - that mediates between the voltage command vector and the final PWM signal generation. The correction vector acts as a intermediary that carries the necessary time adjustment information without requiring complex real-time processing. This intermediary approach simplifies the controller structure by decoupling the complex calculation requirements from the real-time control path.
Data Source
AI summary
A power conversion apparatus includes: a power converter that includes a plurality of switching elements; and a controller that controls the plurality of switching elements. The controller includes: a command generator that generates a voltage command vector; a synthesizer that synthesizes a correction vector with the voltage command vector to generate a synthetic vector; an adjuster that adjusts an output time of a plurality of voltage vectors from the power converter, the output time being corresponding to the synthetic vector; and a correction vector generator that generates the correction vector on the basis of an adjustment result of the adjuster.