Motor Controller Reflux Switch Control for Heat Reduction
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Solution Overview
Problem
Motor controllers with multiple phase windings face challenges in managing reflux currents, which lead to increased heat generation and power consumption due to higher electrical resistance when switches are in an OFF state, potentially causing premature deterioration and inefficient energy use.
Innovation Solution
The motor controller incorporates a reflux-on control mechanism where the reflux switch is turned ON, allowing reflux currents to flow through with lower resistance, reducing heat generation and energy consumption by optimizing the reflux-on period based on current values and mask periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the reflux switch is kept OFF and reflux current flows through the body diode, then the device complexity is reduced, but the heat generation increases due to higher electrical resistance
Solution Approach 1:
The patent applies dynamics by making the reflux switch control state changeable over time. The reflux switch is turned ON during specific periods (reflux-on period) when reflux current flows, and OFF at other times. This dynamic control allows the system to optimize between low resistance (switch ON) and simple control (switch OFF) based on operational requirements, thereby reducing heat generation during critical reflux periods while maintaining overall system simplicity.
2Loss of energy
If the reflux switch is turned ON to reduce electrical resistance, then the heat generation is reduced, but the device complexity increases due to additional control requirements
Solution Approach 1:
The patent applies preliminary action by determining the reflux-on period in advance based on predetermined criteria such as current direction, current magnitude, and timing relative to the mask period. The control unit pre-calculates when the reflux switch should be turned ON and OFF, allowing the system to execute the control strategy without complex real-time decision-making, thus reducing the perceived control complexity while maintaining energy efficiency.
Solution Approach 2:
The patent applies feedback by using current detection results to dynamically adjust the reflux switch control. The control unit detects current flow direction and magnitude, and based on this feedback, determines the appropriate reflux-on period. This feedback mechanism allows the system to automatically optimize switch control based on actual operating conditions, reducing the need for complex manual control strategies.
3Loss of energy
If the reflux-on period is extended to maximize energy savings, then the heat generation is reduced, but the productivity decreases due to longer switch ON time
Solution Approach 1:
The patent applies partial action by turning on the reflux switch only for the necessary duration (reflux-on period) rather than keeping it ON continuously. The reflux-on period is carefully determined to cover only the critical period when reflux current flows and energy savings are most beneficial. This partial activation approach maximizes energy savings during critical periods while minimizing the impact on switching speed and overall productivity.
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 reduces heat generation and power consumption by ensuring reflux currents flow through the switch with lower resistance, enhancing the longevity of the switch and improving energy efficiency during motor operation.
Implementation Method 1
since the reflux current flows through the reflux switch in the ON state, the reflux current flows with a smaller electric resistance than an electric resistance of a body diode
Implementation Method 2
the heat generated by the switches is reduced
Data Source
AI summary
A motor controller for controlling a drive of a motor having plural phase windings includes upper and lower arm circuits and a control unit. The control unit switchingly controls ON/OFF of switches of the upper and lower arm circuits, for sequentially switching an energized phase of the motor. Then, from among the plural switches, a switch forming an energization path to the energized phase is designated as an energized phase switch with the others of the plural switches being designated as non-energized phase switches. Further, from among the non-energized phase switches, a switch forming a path of a reflux current that accompanies the switching of the energized phase is designated as a reflux switch. Then, the control unit performs an ON control of the energized phase switch in addition to performing an ON control of the reflux switch.