Inverter Control Device for Electric Rotating Machine
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Solution Overview
Problem
Conventional control devices for electric rotating machines face challenges in precisely controlling currents due to increased harmonic waves in the output voltage when operating in excessive modulation regions, leading to suboptimal response characteristics and high computational loads in prediction models.
Innovation Solution
A control device with a first and second predicting unit, a state determining unit, and a control unit that predicts and adjusts the controlled state of the power inverting circuit to apply corresponding voltages, using initial values from previous predictions to refine future predictions, thereby reducing computational load and improving precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If model prediction control is used to improve current control precision, then current control precision is improved, but computational load increases extremely
Solution Approach 1:
The prediction process is segmented into two distinct units: a first predicting unit that performs comprehensive multi-step predictions for multiple controlled states, and a second predicting unit that performs refined single-step predictions using results from the first unit. This segmentation divides the computational workload into manageable stages, reducing the overall computational burden while maintaining prediction accuracy.
Solution Approach 2:
The first predicting unit performs preliminary predictions of the controlled variable for multiple future control periods and multiple controlled states before the final control decision is made. These preliminary results serve as initial values for the second predicting unit, which then performs the final precise prediction. This preliminary action allows the system to prepare prediction data in advance, reducing real-time computational requirements.
2Measurement precision
If multiple operating states are predicted for future control periods to improve precision, then prediction precision is improved, but calculation time increases
Solution Approach 1:
The prediction task is divided between two specialized units: the first predicting unit handles the computationally intensive multi-state, multi-period predictions, while the second predicting unit focuses on the final precise prediction for the next control period. This time segmentation allows complex calculations to be performed in advance without delaying the real-time control decision.
Solution Approach 2:
Predictions for multiple controlled states and multiple future control periods are performed in advance by the first predicting unit before the control period begins. These preliminary predictions are stored and then used as initial values by the second predicting unit to generate the final prediction, eliminating the need to recalculate all possibilities in real-time.
3Device complexity
If PWM control is used to simplify the control structure, then control structure is simplified, but harmonic waves increase in excessive modulation region
Solution Approach 1:
The control device uses feedback from the actual controlled variable measurements to update and refine the prediction models. By continuously comparing predicted values with actual measurements and adjusting subsequent predictions accordingly, the system compensates for the harmonic distortions introduced by PWM control in excessive modulation regions, maintaining accurate current control despite the simplified control structure.
Data Source
AI summary
A control device has a unit for selecting each of states of an inverter applying a voltage to a generator, a unit for predicting a first current of the generator, flowing at a second time elapsed by one control period from a first time, from a detected current and the state of the inverter at the first time, a unit for predicting a second current of the generator at a third time elapsed by one control period from the second time while using the first current as an initial value of the second current, from information indicating one selected state set at the second time, for each selected state, a unit for determining one state corresponding to the second current nearest to instruction, and a unit for setting the inverter in the determined state at the second time to control current of the generator.