Synchronous Reluctance Motor Rotor Cage for Open-Loop V/Hz Control
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Solution Overview
Problem
Conventional synchronous reluctance motors require vector control and significant tuning for operation, necessitating a dedicated variable frequency drive for each motor, which is inefficient and costly.
Innovation Solution
A variable frequency drive system with a single controller controls synchronous reluctance motors in an open-loop mode using volts-per-Hertz control, incorporating a conductive cage with conductive rotor bars and end rings, allowing for efficient operation without the need for angular position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vector control with angular position sensors is used for synchronous reluctance motors, then stable operation is achieved, but device complexity and cost increase due to dedicated variable frequency drives and sensors for each motor
Solution Approach 1:
The patent removes the angular position sensor from the control system, extracting the sensing function and replacing it with sensorless estimation methods using voltage and current measurements. This eliminates the complexity and cost of physical sensors while maintaining stable operation through mathematical modeling of rotor position.
Solution Approach 2:
The patent enables a single variable frequency drive to control multiple synchronous reluctance motors simultaneously using open-loop volts-per-Hertz control. This universal controller replaces multiple dedicated vector controllers, reducing device complexity while maintaining reliable operation across multiple motors through simplified control architecture.
2Ease of operation
If dedicated variable frequency drives are used for each synchronous reluctance motor, then precise control is achieved, but cost and system efficiency worsen
Solution Approach 1:
The patent merges multiple dedicated variable frequency drives into a single controller that can manage multiple synchronous reluctance motors. This consolidation reduces the number of controllers from one per motor to one shared controller, decreasing device complexity and cost while maintaining operational precision through centralized control logic.
Solution Approach 2:
The single variable frequency drive controller is designed with universal functionality to control multiple motors simultaneously. It performs the functions of multiple dedicated controllers through a unified control algorithm that manages multiple motor loads, achieving both cost reduction and maintained control precision.
3Device complexity
If conventional synchronous reluctance motors are used without conductive cage, then motor structure is simpler, but starting performance and stability deteriorate
Solution Approach 1:
The patent combines conventional rotor structures with a conductive cage (squirrel cage) embedded in the rotor. This composite structure merges the simplicity of traditional synchronous motors with the robust starting characteristics of induction motors, achieving both structural simplicity and improved starting performance through the synergistic combination of rotor types.
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
Enables efficient and stable operation of synchronous reluctance motors across varying loads, replacing induction motors with increased efficiency and cost-effectiveness, suitable for applications like HVAC and pumping systems.
Implementation Method 1
The conductive cage may include conductive material located in at least some of the plurality of curved, spaced-apart barrier slots to create a plurality of curved, spaced-apart conductive rotor bars
Implementation Method 2
adjusting the voltage magnitude of an output of the inverter to each synchronous reluctance motor to match a required load torque in a volts-per-Hertz relationship
Data Source
AI summary
A variable frequency drive motor system and method with a single variable frequency drive controller controlling multiple synchronous reluctance motors in an open-loop mode using volts-per-Hertz control. Each motor includes a rotor including three or more curved, spaced-apart barrier slots extending longitudinally through each quadrant of the rotor. The rotor also includes a conductive cage including a plurality of conductive rotor bars contained within the barrier slots and also extending longitudinally through each quadrant, and conductive end rings located at opposite ends of the rotor and electrically connected to the respective ends of the rotor bars. The controller controls speed and torque by varying input frequency and voltage in an open-loop mode by adjusting the voltage magnitude of an inverter's output to each motor to match a required load torque in a volts-per-Hertz relationship. An operator interface allows for starting, stopping, adjusting, and otherwise controlling the operation of each motor.