Polyphase Motor Control via Dynamic Current Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyphase brushless actuators, such as stepper motors, face high current consumption and inefficient energy use due to the inability to dynamically adjust the current supplied to the stator based on the instantaneous load, leading to increased energy consumption and self-heating, especially when the actuator is stationary or at reduced speed.
Innovation Solution
A method where a microcontroller determines the mechanical position of the actuator's rotor and calculates a coefficient k to adjust the amplitude of the voltage supplied to each phase, using pulse width modulation (PWM) to dynamically modify the current, ensuring efficient energy use regardless of speed or load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the actuator supplies constant current to the stator coils, then the motor maintains sufficient torque, but energy consumption increases and self-heating occurs
Solution Approach 1:
The patent applies dynamics by making the current supply adjustable rather than constant. The control system dynamically modifies the current amplitude based on the instantaneous load conditions, using a coefficient k that varies with load detection. This allows the motor to maintain sufficient torque when needed while reducing current and energy consumption when the load is light, directly resolving the contradiction between maintaining power and reducing energy use.
Solution Approach 2:
The patent changes the electrical parameter (current amplitude) based on operating conditions. By detecting the load and calculating a adjustment coefficient k, the system modifies the current supplied to the stator coils in real-time. This parameter change enables the motor to adapt its power consumption to the actual torque requirements, reducing energy waste while maintaining adequate torque output.
2Speed
If the actuator runs at reduced speed or stationary, then energy saving is needed, but torque maintenance becomes difficult with constant current
Solution Approach 1:
The system dynamically adjusts current based on speed and load conditions. When the motor operates at reduced speed or remains stationary, the control system detects these conditions and reduces the current amplitude accordingly, rather than maintaining constant current. This dynamic adaptation allows energy saving during low-speed or stationary operation while ensuring sufficient torque is available when the load requires it.
Solution Approach 2:
The patent modifies the electrical parameters (current amplitude and potentially frequency) according to the operating speed and load. By changing these parameters in real-time based on detected conditions, the system achieves energy efficiency at reduced speeds while maintaining the capability to deliver required torque when needed, resolving the contradiction between speed reduction and energy consumption.
3Force
If the actuator increases current to handle higher load, then torque increases, but self-heating increases
Solution Approach 1:
The patent changes the current parameter dynamically based on actual load requirements rather than using a fixed high current setting. By detecting the instantaneous load and adjusting the current amplitude with coefficient k, the system supplies only the necessary current to generate required torque. This prevents excessive current that would cause unnecessary self-heating, while still providing sufficient torque when the load demands it.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for dynamic control of the actuator, reducing energy consumption by adjusting the current based on real-time position and load, maintaining performance even at zero or reduced speed, and minimizing self-heating.
Implementation Method 1
using pulse width modulation (PWM) to dynamically modify the current
Implementation Method 2
the rotor is moved by the magnetic field created by a set of coils controlled by power electronics
Data Source
AI summary
A method for controlling a polyphase actuator includes supplying each phase with a periodically varying voltage having a periodic sequence of steps Pi that have a constant duration and an amplitude An,i, where n corresponds to the rank of the phase and i to the rank of the step. The method further includes determining a target position PCi of a rotor of the actuator, in order to define a sinusoidal voltage envelope. The actuator further includes a movable member, a stator equipped with electrical coils and a sensor detecting the mechanical position of the movable member with respect to the stator, as well as a microcontroller. The microcontroller determines, at times Tcapteur, a mechanical position of a mechanical member, the microcontroller calculates, at each of the times Tcapteur, a difference between the mechanical position and a target position PCi corresponding to the step Pi and the microcontroller calculates a coefficient k as a function of the difference. The microcontroller also weights the amplitude of a power supply applied to the phases by a coefficient k in order to supply the phases with weighted amplitude voltages An,i*k.