Motor Drive Controller With State Feedback for High-Speed Stability
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Solution Overview
Problem
Existing controllers for drive systems using inverters to convert DC power to AC power for rotating electric machines face instability and harmonic ripple issues, particularly at high rotation speeds due to slow control periods and dead time variations.
Innovation Solution
A controller that utilizes a rotation matrix to perform state feedback control, correcting d-axis and q-axis voltage commands based on the rotation speed and machine characteristics, stabilizing the control system and suppressing harmonic ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional feedback control is used to control motor rotation speed, then the control system is simple to implement, but the system becomes unstable at high rotation speeds due to slow control period
Solution Approach 1:
The control system is segmented into multiple independent controllers: a feedback controller for basic speed regulation and a state feedback controller for stability enhancement. Each controller operates with its own control period, allowing the state feedback controller to use a shorter period for high-speed stability while the feedback controller maintains overall system simplicity.
Solution Approach 2:
The state feedback controller acts as an intermediary that processes the output from the feedback controller and generates corrected voltage commands. This intermediary layer filters out harmonic ripples and stabilizes the system at high speeds without requiring complete redesign of the basic control architecture.
2Ease of manufacture
If conventional feedback control is used, then implementation is straightforward, but harmonic ripples occur due to inverter dead time variations
Solution Approach 1:
The state feedback controller implements a feedback mechanism that detects harmonic ripples generated by inverter dead time variations and generates correction signals to counteract these ripples. The controller uses the motor's state variables (current, speed, position) to calculate appropriate voltage corrections that eliminate the harmful harmonic components.
Solution Approach 2:
The controller dynamically changes control parameters based on operating conditions. The state feedback gain and rotation angle are adjusted according to motor speed and load conditions, allowing effective ripple suppression across different operating ranges while maintaining ease of implementation through pre-calculated gain schedules.
3Measurement precision
If state feedback control is implemented to suppress harmonic ripples, then control precision improves, but device complexity increases
Solution Approach 1:
The patent merges the feedback control and state feedback control into a unified control system where both controllers operate simultaneously. The feedback controller handles basic regulation while the state feedback controller provides precision enhancement, combining the advantages of both approaches without requiring separate independent systems.
Solution Approach 2:
The control system transitions from static to dynamic operation by adapting the state feedback parameters based on real-time motor conditions. The rotation angle and feedback gains are dynamically adjusted according to operating speed and load, enabling high precision control across varying conditions while keeping the controller structure manageable through systematic parameter adaptation.
Data Source
AI summary
A controller includes a feedback controller and a state feedback controller. The feedback controller performs feedback control using a d-axis current value and a d-axis current command value, and feedback control using a q-axis current value and a q-axis current command value, and calculates a d-axis voltage command value and a q-axis voltage command value. The state feedback controller calculates a d-axis voltage value and a q-axis voltage value, obtained by state feedback control of a d-axis current value and a q-axis current value, by performing rotational conversion at a rotation angle determined by the characteristics of the motor, which is correlated with a rotation speed of a motor using a rotation matrix, to calculate a d-axis voltage correction value and a q-axis voltage correction value.