Electronic Pole Changing Induction Motor Control
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Solution Overview
Problem
Conventional induction motor control systems face challenges in providing large torque at low speeds and achieving a wide speed governing operation range, especially due to the limitations of mechanical pole-changing methods which require power cutoff and result in low control accuracy and efficiency.
Innovation Solution
An electronic pole-changing-based induction motor control system that uses multiple three-phase windings and inversion driving units, controlled by a unit that alters current directions or phase angles according to synchronous rotational speed, allowing the motor to form multiple pole-pair numbers without power cutoff, thereby enhancing control accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical speed regulation device and pole-changing control are used, then the speed governing operation range is broadened, but the control accuracy and operation efficiency decrease due to power cutoff requirement
Solution Approach 1:
The patent replaces the mechanical speed regulation device with an electronic pole-changing control system using an inverter. The inverter electronically switches the pole-pair number by controlling the switching states of inversion driving units, eliminating the need for mechanical wiring changes and power cutoff, thus maintaining both wide speed range and high control accuracy.
Solution Approach 2:
The patent changes the electrical parameters (pole-pair number) by controlling the inverter's switching states rather than mechanically reconfiguring the motor windings. This allows dynamic adjustment of pole-pair numbers during operation, achieving wide speed range while maintaining continuous power supply and high control accuracy.
2Productivity
If mechanical speed regulation device is used for pole-changing control, then variable speeds are achieved, but the number of variable speeds is limited making the speed governing operation range narrow
Solution Approach 1:
The patent implements dynamic pole-pair number switching through electronic control, allowing the motor to transition between multiple pole-pair numbers (e.g., 2/4/6/8 poles) based on real-time speed requirements. This dynamic control enables continuous speed adjustment across a wide range, overcoming the limited discrete speed steps of mechanical devices.
3Adaptability or versatility
If conventional frequency control is used, then the speed governing operation range is extended, but the requirement of providing large torque at low speed is not met
Solution Approach 1:
The patent segments the speed control range into multiple zones corresponding to different pole-pair numbers. By switching between 2/4/6/8 pole configurations, the system optimizes torque characteristics for each speed zone, ensuring large torque availability at low speeds while maintaining wide overall speed range.
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 solution enables the induction motor control system to achieve a wider speed governing operation range and increased low-speed torque, simplifying the peripheral transmission mechanism and improving energy-saving effects while maintaining high control accuracy and efficiency.
Implementation Method 1
the inverter is connected with the motor and the DC power supply respectively, for converting a direct current supplied by the DC power supply to an alternating current supplied to the motor
Implementation Method 2
the control unit alters current directions or phase angles of at least part of the three-phase windings according to a synchronous rotational speed of the motor, making said N three-phase windings form at least two pole-pair numbers
Data Source
AI summary
The present invention relates to an electronic pole changing-based induction motor control system and a control method thereof. Such induction motor control system comprises an induction motor, an inverter and a DC power supply. The inverter is connected with the motor and the DC power supply respectively, for converting a direct current supplied by the DC power supply to an alternating current supplied to the motor. The motor comprises N three-phase windings (11, 12; 31, 32). The inverter comprises N inversion driving units (21, 22; 41, 42) and at least one control unit. Each inversion driving unit is connected with one three-phase winding. The control unit controls the inversion driving unit to generate a current of the three-phase winding connected thereto, and frequency, amplitude and phase of the current can be controlled by the control unit. The control unit alters current directions or phase angles of at least part of the three-phase windings according to a synchronous rotational speed of the motor, making N three-phase windings form at least two pole-pair numbers. The induction motor control system enhances the low-speed torque and broadens the speed governing operation range, thereby enhancing the control accuracy and operation efficiency, and simplifying a peripheral transmission mechanism.