Polyphase Inverter Control Reducing Switching Losses
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Solution Overview
Problem
Current control techniques for polyphase inverters face challenges in minimizing switching losses and reducing the effective current in decoupling capacitors, leading to increased complexity and space requirements, especially in applications like the automobile and aeronautic sectors.
Innovation Solution
A method of controlling a power bridge that reduces switching losses by minimizing the use of freewheeling vectors and optimizing the generation of control vectors, using a double carrier system to inhibit bridge arms and reduce the effective current in decoupling capacitors, thereby stabilizing voltage and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If discontinuous PWM control techniques are used to control the power bridge, then switching losses are reduced, but the effective current in decoupling capacitors increases and voltage stability deteriorates
Solution Approach 1:
The patent applies periodic action by using discontinuous PWM control where bridge arms are inhibited during specific intervals of the electrical period. The control technique periodically inhibits bridge arms based on modulant saturation, creating a rhythmic switching pattern that reduces switching losses while maintaining voltage stability through controlled periodic action.
2Reliability
If a high capacitance decoupling capacitor is used to stabilize the input voltage, then voltage stability is improved, but the physical size and space requirements increase
Solution Approach 1:
The patent extracts the voltage stabilization function from the decoupling capacitor by implementing active control of the power bridge. The control technique compensates for current discontinuities through intelligent switching control, thereby reducing the capacitor's role in voltage stabilization and allowing for a smaller capacitance value.
Solution Approach 2:
The patent changes the operating parameters of the power bridge control to reduce current ripple and discontinuities. By optimizing the switching patterns and inhibition strategies, the effective current in the decoupling capacitor is reduced, allowing for a smaller capacitor size while maintaining voltage stability.
3Measurement precision
If the quantity of neutral is calculated in line to maintain accurate control, then control precision is improved, but the calculation time increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and tabulating the quantity of neutral for different operating conditions. Instead of calculating in real-time, the control technique uses pre-computed values stored in lookup tables, which are selected based on the current operating state, thereby maintaining control precision while avoiding lengthy real-time calculations.
4Loss of time
If tabulated values of neutral quantity are used, then calculation time is reduced, but memory consumption increases
Solution Approach 1:
The patent applies local quality by creating specialized lookup tables tailored to specific operating modes (motor mode, alternator mode, starter mode). Instead of storing comprehensive tables for all possible conditions, the control technique uses mode-specific tables with only the relevant data, reducing memory consumption while maintaining fast access times.
5Measurement precision
If voltage-current phase difference measurement is implemented, then control accuracy is improved, but the implementation complexity increases
Solution Approach 1:
The patent extracts the need for complex phase difference measurement by reformulating the control technique to rely on simpler quantities. The control method uses modulants and their saturation states directly, eliminating the requirement for explicit voltage-current phase difference calculation and measurement, thereby reducing implementation complexity.
Data Source
AI summary
A method for driving a power bridge (1) which is used for controlling a multiphase electric load (3), connectable to said electric load (3) via several arms and drivable by switching functions which determine free wheel controlling vectors and are active for controlling the load. The inventive method consists in selecting a first switching function production method which produces a reduced number of combinations of switching functions corresponding to the free wheel control vectors or a second switching function production method which produces combinations of switching functions corresponding only to the active control vectors, wherein said method are defined according to a given reference voltage vector and in applying said selected for producing a sequence of control vectors from the produced combinations of switching functions.