Induction Motor Dynamic Power Control via Winding Switching
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Solution Overview
Problem
Inductive motors waste energy due to excess current consumption when not under maximum load, as they are designed to operate under maximum anticipated load conditions, leading to inefficiency and energy loss as heat due to eddy currents and resistive heating.
Innovation Solution
An electric motor with a conductive winding and a controller that selectively energizes different portions of the winding based on load conditions, adjusting the magnetic field strength to match the required torque, using a switching device to manage power delivery efficiently by switching between multiple power levels or voltage sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor is designed to operate under maximum anticipated load conditions with oversized windings to provide voltage tolerance, then the motor can reliably operate under reduced AC voltage, but the motor consumes excess current and wastes energy when not under maximum load
Solution Approach 1:
The patent applies dynamics by making the magnetic field strength adjustable rather than fixed. The controller dynamically changes the RMS voltage applied to the conductive winding based on detected load conditions, switching between different voltage levels (e.g., 120VAC, 105VAC, 90VAC) to match the actual torque requirements. This resolves the contradiction by allowing the motor to maintain reliability at nominal voltage when needed while reducing energy consumption when full power is not required.
Solution Approach 2:
The patent changes the electrical parameter (RMS voltage level) applied to the motor winding based on operating conditions. The controller monitors load conditions and adjusts the voltage parameter dynamically, selecting from multiple predefined voltage levels. This parameter change allows the motor to operate efficiently across different load conditions rather than being locked into a single design-point optimization, thereby reducing energy waste while maintaining sufficient torque output.
2Reliability
If the conductive winding is formed with lower gauge wire to conduct sufficient current at reduced voltage, then the motor can operate reliably at 105VAC, but the winding conducts more current than necessary at nominal voltage, wasting energy
Solution Approach 1:
The system dynamically adjusts the applied voltage to match load requirements. When operating at reduced load, the controller applies a reduced RMS voltage (e.g., 105VAC or 90VAC instead of 120VAC), which automatically reduces the current through the winding according to Ohm's law. This dynamic adjustment eliminates the need for the winding to continuously conduct excess current, thereby reducing energy consumption while maintaining the ability to operate reliably at reduced voltage when needed.
Solution Approach 2:
The patent applies partial action by delivering only the necessary amount of voltage and current required for the current load condition. Rather than continuously applying full nominal voltage that would cause excessive current flow, the controller applies a scaled-down voltage level appropriate for the actual torque demand. This partial action principle allows the motor to maintain sufficient performance while avoiding the energy waste associated with oversized current conduction capability.
3Adaptability or versatility
If the motor operates at partial load, then the motor can adapt to varying demand conditions, but the motor dissipates excess energy as heat due to eddy currents and resistive heating
Solution Approach 1:
The controller dynamically adjusts the RMS voltage applied to the winding based on detected load conditions. By reducing the voltage during partial load operation, the system proportionally reduces the current and consequently the resistive heating losses (I²R losses) and eddy current losses. This dynamic adaptation allows the motor to maintain versatility in handling varying load demands while minimizing energy waste as heat during light-load operation.
Solution Approach 2:
The system changes the electrical operating parameters (voltage and current levels) to match the actual load requirements. During partial load conditions, the controller reduces the RMS voltage parameter, which automatically scales down the current parameter and the associated thermal losses. This parameter adaptation resolves the contradiction by allowing load versatility while reducing heat dissipation through optimized electrical parameter selection.
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 reduces energy wastage by optimizing power delivery according to load conditions, enhancing the motor's efficiency and reducing excess energy dissipation as heat, thereby improving overall energy conservation.
Implementation Method 1
An inductive motor converts electrical energy to mechanical energy via electromagnetic interactions that create torque on a shaft
Implementation Method 2
The stator and winding are configured such that a rotating magnetic field is created within the stator when AC current flows through the winding
Implementation Method 3
The switching device is configured to selectively energize, by an AC source, a first portion of the conductive winding in a first state and a second portion of the conductive winding in a second state
Implementation Method 4
The rotor magnetically interacts with the magnetic field such that a torque is applied to the rotor
Data Source
AI summary
An example electric motor including a conductive winding, a switching device, a rotor, and a controller is disclosed. The switching device is configured to selectively energize, by an AC source, a first portion of the conductive winding in a first state and a second portion of the conductive winding in a second state. The conductive winding generates a magnetic field having a first strength in the first state and a second strength in the second state. The rotor magnetically interacts with the magnetic field such that a torque is applied to the rotor. The amount of torque applied is related to the strength of the magnetic field. The controller is configured to: (i) determine a metric indicative of a load condition of the electric motor; and (ii) based on the determined metric, cause the switching device to switch between the first state and the second state one or more times.