Motor Phase Voltage Modulation for EMC and Switching Loss Balance
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Solution Overview
Problem
Existing motor control systems face challenges in balancing electro-magnetic compatibility (EMC) and switching losses, as signals with high EMC often result in high switching losses, and those with low losses may not provide sufficient EMC.
Innovation Solution
The proposed solution involves control circuitry generating a switching signal that couples a motor phase to a first terminal for a significant portion of switching cycles corresponding to specific electrical angles, reducing switching losses while maintaining high EMC by minimizing unnecessary switching occurrences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching signals are designed with high electro-magnetic compatibility (EMC), then EMC is improved, but switching losses increase
Solution Approach 1:
The patent applies periodic action by implementing discontinuous PWM schemes where switching occurs only during specific intervals (e.g., 0 to 60 electrical degrees) while remaining idle during other intervals. This periodic switching pattern reduces the total number of switching events per electrical cycle, thereby lowering switching losses while maintaining sufficient EMC performance for the motor control application.
Solution Approach 2:
The patent implements partial action by applying PWM switching only to specific portions of the electrical cycle rather than continuously. By limiting switching activity to necessary intervals and leaving other intervals idle, the system achieves the minimum required switching action to maintain motor control and EMC, thereby reducing overall switching losses.
2Loss of energy
If switching signals are designed with low switching losses, then energy efficiency is improved, but electro-magnetic compatibility may be insufficient
Solution Approach 1:
The patent implements periodic switching patterns where PWM signals are applied during specific electrical angle intervals (e.g., 60 degrees) and remain idle during other intervals. This periodic approach reduces the total switching frequency and losses while concentrating switching activity during intervals that are sufficient to maintain the required EMC performance for motor control.
Solution Approach 2:
The patent changes the switching parameters by implementing discontinuous PWM schemes with variable duty cycles and switching intervals. By optimizing the switching window duration and positioning within the electrical cycle, the system achieves the minimum necessary switching action to maintain EMC while minimizing total switching losses.
Data Source
AI summary
A circuit for controlling a motor that includes control circuitry configured to generate, for a phase of the motor, a switching signal indicating to couple the phase to a first terminal of a supply for an entire portion of each switching cycle of a first plurality of switching cycles corresponding to a first range of electrical angles for the rotor and to couple the phase to a second terminal of the supply for a portion of each switching cycle of a second plurality of switching cycles corresponding to a second range of electrical angles for the rotor. The control circuitry is further configured to control the motor based on the switching signal.