SR Motor Control Device Switching Drive and Brake Torque
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Solution Overview
Problem
Conventional motor control devices for switched reluctance motors (SR motors) face issues with excessive current generation when switching between drive control and brake control, particularly due to unrecouped regenerative current and increased excitation current.
Innovation Solution
A motor control device that switches between drive control and brake control by ensuring a non-energized phase with no excitation current flowing through the winding wire, reducing the current to below a prescribed value, and selectively magnetically attracting salient poles to generate torque, avoiding magnetic attraction for the next salient pole during mode transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If drive control is started with regenerative current remaining in the SR motor, then drive torque can be generated, but excessive current is generated in the SR motor
Solution Approach 1:
The control unit provides a non-energized section before switching from brake control to drive control, during which excitation current does not flow through the winding wire. This preliminary action reduces the current to below a prescribed value, preventing excessive current generation when drive control starts while ensuring drive torque can be generated subsequently
2Power
If switching from drive control to brake control, then braking torque can be generated, but excitation current increases and regenerative current becomes excessive
Solution Approach 1:
The control unit provides a non-energized section before switching from drive control to brake control, during which excitation current does not flow through the winding wire. This preliminary action reduces the current to below a prescribed value, preventing excessive regenerative current when brake control starts while ensuring braking torque can be generated subsequently
3Power
If magnetic attraction is performed for all salient poles during mode switching, then torque generation is maintained, but current overlap occurs between regenerative and excitation currents
Solution Approach 1:
The control unit extracts or removes the magnetic attraction action for at least one salient pole during mode switching by providing a non-energized section. This selective removal prevents current overlap between regenerative and excitation currents while the patent ensures torque generation is maintained through appropriate control of other salient poles
Solution Approach 2:
The control unit provides a non-energized section before switching modes, during which excitation current does not flow. This preliminary action reduces current to below a prescribed value, preventing current overlap while allowing torque generation to resume after the transition
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 effectively suppresses excessive current generation in SR motors during mode switching, preventing regenerative current overlap and maintaining efficient control.
Implementation Method 1
The control unit enables the first salient pole to magnetically attract the second salient pole by selectively energizing the winding wires, to generate the drive torque or the braking torque in the rotor
Data Source
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AI summary
The invention suppresses the generation of an excessive current in a SR motor during switching between drive control and brake control. This motor control device is for controlling rotation of a multiphase SR motor, and is provided with a control unit that controls the rotational speed of the SR motor while switching between drive control for generating drive torque in the SR motor and brake control for generating braking torque in the SR motor, wherein the control unit performs switching from the drive control to the brake control or vice versa under the condition that the current flowing through a winding wire of an energized phase is less than a prescribed value.