Electric Rotary Machine Control Device Prediction Model
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Solution Overview
Problem
As the angular velocity of electric rotary machines increases, the accuracy of control devices in adjusting output torque and rotation speed decreases due to longer updating periods of operation states, leading to performance degradation.
Innovation Solution
A control device that uses a prediction mechanism to adjust the operation of an electric power conversion circuit with switching elements, predicting control values based on virtual operation states and adjusting the output voltage vector in the rotary coordinate system to minimize errors caused by discretization, using methods like forward difference or setting median values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the angular velocity of the electric rotary machine increases, then the rotation speed improves, but the control accuracy decreases due to longer updating periods
Solution Approach 1:
The patent applies preliminary action by predicting future control values before they are actually needed. The prediction unit calculates predicted values of control quantities (such as current or voltage) based on the relation model and current operation state, allowing the control system to prepare optimal control actions in advance. This predictive approach compensates for the longer updating periods caused by high angular velocities, maintaining control accuracy despite the increased rotation speed.
2Loss of time
If the updating period of operation state is extended, then the processing time per cycle increases, but the control accuracy decreases
Solution Approach 1:
The patent implements feedback through the relation model that continuously relates operation states to control quantities. The prediction unit uses this model to calculate predicted control values based on current operation state and history, creating a closed-loop predictive system. This feedback mechanism allows the control device to maintain accuracy over extended updating periods by continuously adjusting predictions based on the established relationship between operation state and control quantities.
3Measurement precision
If prediction model control is used to improve control accuracy, then the complexity of the control device increases
Solution Approach 1:
The patent applies parameter changes by utilizing the relation model that describes the relationship between operation state parameters and control quantity parameters. Instead of complex real-time calculations, the system changes approach by pre-establishing this relational model and using it for predictions. The prediction unit simply applies the model with current parameters to generate predicted values, maintaining accuracy while avoiding excessive computational complexity through this parameter-based relational approach.
Data Source
AI summary
A control device controls a power conversion circuit so as to adjust control values of a motor generator to optimum values. The power conversion circuit has switching elements for selectively connecting and disconnecting a battery and terminals of the motor generator. The control device sets a simulated voltage vector V(n+1) in one control-period forward to perform a prediction model control. On predicting a current, the control device uses a model in a rotary coordinate system, and sets the median value of the voltage vector V(n+1) in one control-period Tc to a value of the voltage vector V(n+1) in the rotary coordinate system. The control device sets, as the value of the voltage vector V(n+1) in the rotary coordinate system, the voltage vector V(n+1) when the half-time of the control-period Tc is elapsed from the time at the electric angle θ(n+1).