Acceleration Estimator for Motor Speed Rate Control
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Solution Overview
Problem
Existing control systems for motors struggle to limit the rate of change of speed across different operating modes, particularly when operating parameters cannot be directly correlated with output values, leading to potential deceleration beyond acceptable limits.
Innovation Solution
A controller with an acceleration estimator that monitors motor output speed, provides an acceleration-limited speed set point, and overrides torque or power regulators when acceleration exceeds acceptable ranges, ensuring deceleration is within safe limits, regardless of operating mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a motor is controlled in torque or power mode without direct speed monitoring, then the motor can operate efficiently in those modes, but the acceleration and deceleration rates cannot be limited, leading to potential excessive deceleration beyond acceptable limits
Solution Approach 1:
The patent introduces an acceleration estimator as an intermediary component that indirectly measures acceleration by monitoring speed changes over time. This estimator acts as a mediator between the torque/power regulators and the acceleration limiting requirement, allowing the system to maintain torque or power mode operation while still enforcing acceleration limits through the estimated acceleration feedback
Solution Approach 2:
The acceleration estimator is designed to work universally across multiple operating modes (speed mode, torque mode, power mode) without requiring mode-specific implementations. The same estimator circuitry and algorithm provide acceleration limiting functionality regardless of which operating mode is active, eliminating the need for separate control paths for each mode
2Measurement precision
If complex modeling of system dynamics and load correlations is implemented to limit acceleration, then acceleration control precision improves, but device complexity increases significantly
Solution Approach 1:
The patent replaces complex, expensive system dynamic models with a simple, computationally inexpensive acceleration estimator that uses basic speed measurements and a first-order differential equation. This estimator provides sufficient accuracy for acceleration limiting without requiring detailed knowledge of system dynamics, load characteristics, or complex parameter identification
Solution Approach 2:
The patent changes the approach from using complex system parameters (moment of inertia, friction coefficients, load correlations) to using a simplified parameter-based estimator with a single time constant. This parameter change dramatically reduces computational complexity while maintaining adequate acceleration measurement accuracy for control purposes
Data Source
AI summary
Embodiments of the present invention are directed to a controller that is configured to limit the rate of change of speed of a motor (e.g., the acceleration or deceleration) regardless of the operating mode of the motor (e.g., speed, torque, or power control mode). The controller can include an acceleration estimator which monitors the output speed of a motor and provides an acceleration-limited speed set point. The output of the acceleration estimator may be limited to a range of acceptable acceleration values that correspond to the required limits of acceleration and deceleration. The acceleration estimator can be configured such that it causes the speed regulator to override the torque and/or power regulators when the acceleration range is exceeded.