Power Converter Control Device Over-Modulation Management
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Solution Overview
Problem
Existing electric power converters struggle with efficient over-modulation management, especially when dealing with unbalanced, dephased, or non-linear currents, leading to errors and limitations in high-performance modulation applications.
Innovation Solution
A control device and method that detect current signals in the outputs of the converter to select appropriate modulation signals for over-modulation, using detection signals to determine a common control component, which includes processing means for computing limit values and controlling limiting to prevent overshoot, allowing for efficient over-modulation even in unbalanced or non-linear conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If phase shift signals are used to determine the general control component, then modulation control is simplified, but over-modulation management becomes inefficient when loads are unbalanced or non-linear
Solution Approach 1:
The patent changes the parameter used for determining the general control component from phase shift angle to current amplitude. This parameter substitution allows the system to adapt to unbalanced and non-linear loads by using current magnitude information instead of phase information, thereby maintaining reliable over-modulation management under varying load conditions.
Solution Approach 2:
The patent applies over-modulation to the modulation signal corresponding to the phase with the highest current amplitude before the modulation process. This preliminary application of over-modulation based on current amplitude detection ensures that the control component is optimized in advance for the most demanding phase, improving overall system reliability under unbalanced conditions.
2Ease of operation
If a single phase shift signal is used for all three phases, then control is simplified, but errors increase when loads are unbalanced
Solution Approach 1:
The patent applies different control strategies to different phases based on their individual current amplitudes. Instead of using a uniform phase shift signal for all phases, the system identifies the phase with the highest current amplitude and applies over-modulation specifically to that phase's modulation signal, thereby achieving locally optimized control that improves measurement precision under unbalanced conditions.
3Adaptability or versatility
If over-modulation is applied without current-based selection, then modulation range is extended, but overshoot risks increase
Solution Approach 1:
The patent uses feedback from current amplitude detection to control the application of over-modulation. By continuously monitoring the current amplitudes in each phase and using this information to determine which modulation signal should receive over-modulation, the system extends the modulation range while preventing overshoot through adaptive, condition-based control.
Data Source
AI summary
The control device of an electric power converter comprises a control device controlling turn-on of semi-conductor legs. The converter comprises DC voltage supply lines, an inverter connected between said lines and outputs. The control device comprises a processing unit to supply modulation signals of control signals of said inverter legs. The control device comprises a module for determining a general control component. The module for determining detects a detection signal representative of a highest current signal in absolute value. The detection signal is used to select a modulation signal on which an over-modulation is applied via the general control component. In the method, the detection signal is used to determine a general control component.