Inverter Control via Delay-Compensated State Vectors
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Solution Overview
Problem
Existing converter control methods face challenges in achieving rapid and stable control due to time delays and the need for simultaneous current and energy control, leading to potential instabilities and inefficiencies.
Innovation Solution
A method that combines state current and intermediate circuit energy values into vectors, using an observation unit to account for delay effects and an estimator unit to model energy dynamics, enabling a holistic control approach with minimal control differences and fast response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cascaded control structure is used for current and energy control, then both current control and energy balancing can be performed, but control stability deteriorates due to time delays and interaction between control loops
Solution Approach 1:
The control system is segmented into independent current control and energy control loops. Each loop processes its respective control variables separately, avoiding the instability caused by cascaded control interactions while maintaining the ability to perform both current and energy control functions.
Solution Approach 2:
A delay compensation mechanism acts as an intermediary between the measured current values and the control calculations. This intermediary component compensates for time delays in the control electronics and measurement systems, providing corrected current values that maintain control stability without sacrificing control capability.
2Ease of operation
If control electronics and measurement systems are used, then current and energy values can be controlled, but time delays occur in control electronics and measurement systems leading to control inaccuracies
Solution Approach 1:
The delay compensation mechanism performs preliminary correction of measured current values before they are used in control calculations. By compensating for time delays in advance, the system eliminates control inaccuracies without adding latency, maintaining both control functionality and timing accuracy.
3Device complexity
If measured current values are used directly for control, then control structure is simple, but control accuracy deteriorates due to delay effects in control electronics
Solution Approach 1:
A delay compensation mechanism serves as an intermediary between the measured current values and the control calculations. This intermediary corrects the measured values by compensating for time delays in the control electronics and measurement systems, providing accurate current values without significantly increasing control structure complexity.
4Adaptability or versatility
If simultaneous current control and energy control are implemented, then comprehensive control is achieved, but control instabilities occur due to interaction between control loops
Solution Approach 1:
The control system is divided into independent current control and energy control segments that operate separately. This segmentation eliminates the harmful interactions between control loops that cause instability, while still allowing both current and energy control functions to be performed comprehensively through coordinated operation of the independent segments.
Data Source
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AI summary
The invention relates to a method wherein state current values (formula I) and state intermediate circuit energy values are summarized in a state vector describing the state of the inverter (1), and target current values and target intermediate circuit energy values are summarized in a target vector, in order to create a clear control structure for efficient and stable control. The state vector and the target vector are compared, obtaining control differential values that are fed into a control unit (14, 16), generating such set voltage values u(k) at the output thereof that the control differential values are as low as possible. Control electronics (19) provide control signals as a function of the set voltage values u(k) and transfer the same to the power semiconductor (S1, S2) of the inverter (1), wherein the state current values (Formula I) are calculated by an observation unit (21) starting from the set voltage values u(k) from measured current values, and wherein the observation unit (21) models the inverter (1) and considers delay effects, so that the state current values (Formula I) correspond to the undelayed, measured current values stripped of the delay effects. The state intermediate circuit energy values (w(k)) are determined by means of an estimating unit (21A) from measured intermediate circuit energy values utilizing a signal model of the intermediate circuit energy values, wherein the estimating unit (21A) calculates the parameters of the signal model of the intermediate circuit energy values (w(k)), each determining an identical magnitude representing a state intermediate circuit energy value (w(k)) of the positive side and negative side AC voltage source of the inverter (1). The state intermediate circuit energy values (w(k)) are fed into the control unit (14, 16) in addition to the state current values (Formula II). The invention further relates to an arrangement for controlling an inverter.