Brushed DC Motor Voltage Limiting via Brush Voltage Drop
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Solution Overview
Problem
Existing methods for controlling brushed DC motors do not effectively address operating constraints such as maximum available voltage, supply current limits, and motor current limits, leading to inefficiencies and potential computational burdens.
Innovation Solution
A method and system for determining brush voltage drop across the DC motor to set voltage limits based on motor current and supply current, using anti-windup control strategies to ensure the motor operates within these constraints, thereby enhancing torque output while reducing computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If voltage limiting is not implemented, then motor torque output is maximized, but operating constraints such as supply current limits and maximum available voltage are violated
Solution Approach 1:
The controller pre-calculates voltage limits based on operating constraints (supply current limits, maximum available voltage) before applying voltage to the motor. This preliminary determination of safe operating boundaries allows the system to maximize torque output within constrained limits, preventing constraint violations while maintaining optimal performance.
Solution Approach 2:
The voltage limit is dynamically adjusted based on real-time operating conditions. The controller continuously monitors supply current and available voltage, adjusting the voltage command to the motor accordingly. This dynamic adaptation allows the system to maintain maximum permissible torque output while satisfying time-varying operating constraints.
2Ease of operation
If traditional voltage control methods are used, then control simplicity is maintained, but computational burden increases due to iterative solving requirements
Solution Approach 1:
The patent extracts the iterative solving step from the voltage control process and replaces it with direct algebraic calculations. By formulating voltage limits through closed-form equations based on operating constraints, the system eliminates computational iteration while maintaining control accuracy, thereby reducing processor burden and simplifying implementation.
Solution Approach 2:
The patent replaces the mechanical iterative solving process with direct mathematical computation. Instead of using iterative numerical methods to determine voltage limits, the system employs closed-form algebraic solutions that directly compute the appropriate voltage command, significantly reducing computational complexity while preserving control precision.
Data Source
AI summary
Technical solutions are described for controlling a brushed direct current (DC) motor, including: determining, based on one of a motor current command or an actual motor current, a brush voltage drop across a set of brushes of the brushed DC motor; determining, based on the brush voltage drop, at least one of: a first voltage limit based on a supply current value not exceeding a supply current limit, and a second voltage limit based on a controller supply voltage value not exceeding a maximum available voltage; determining a final voltage limit based on the at least one of the first voltage limit and the second voltage limit; determining a final voltage command based on an initial voltage command and not to exceed the final voltage limit; and applying a DC voltage to the brushed DC motor based on the final voltage command.