Open-Winding Inverter Control With Rectangular Wave and Special PWM
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Solution Overview
Problem
Existing rotary electric machine control systems with two inverters connected to open windings face challenges in efficiently controlling both inverters under various operating conditions such as torque, rotation speed, and direct-current voltage, leading to increased switching losses and suboptimal performance.
Innovation Solution
Implementing rectangular wave control on one inverter and special pulse width modulation control on the other inverter, based on a difference in switching patterns, to reduce switching frequency and losses while ensuring smooth operation across different operating regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the same control method is applied to both inverters, then the control system is simple and easy to implement, but switching losses increase and performance becomes suboptimal under various operating conditions
Solution Approach 1:
The patent divides the control of two inverters into separate control schemes. One inverter is controlled by rectangular wave control while the other is controlled by special pulse width modulation control. This segmentation allows each inverter to be optimized independently, reducing overall switching losses while managing control complexity through structured separation of control functions.
Solution Approach 2:
The patent applies different control methods to different inverters based on their specific roles and operating conditions. By making the control quality local rather than uniform, the system achieves optimal performance for each inverter while maintaining overall system efficiency. This local differentiation reduces switching losses without requiring complete redesign of the entire control system.
2Loss of energy
If rectangular wave control is applied to one inverter, then switching frequency is reduced and switching losses decrease, but control precision and smooth operation may be compromised
Solution Approach 1:
The patent merges two different control methods (rectangular wave control and special pulse width modulation control) to control the two inverters. This combination allows the system to leverage the low switching loss advantage of rectangular wave control while compensating for its precision limitations through the complementary special PWM control applied to the other inverter, achieving both energy efficiency and control precision.
Solution Approach 2:
The patent introduces asymmetry in the control approach by applying rectangular wave control to one inverter and special pulse width modulation control to the other. This asymmetric control strategy allows each inverter to operate in its optimal control mode, reducing overall switching losses while maintaining the necessary control precision through the complementary nature of the two control methods.
3Productivity
If different control schemes are used for the two inverters, then system efficiency is optimized under various operating conditions, but the control system becomes more complex
Solution Approach 1:
The patent implements dynamic control by selecting different control schemes for the two inverters based on operating conditions such as torque, rotation speed, and direct-current voltage. This dynamic approach allows the system to adapt to varying operating conditions and optimize efficiency, while the structured framework of having one inverter on rectangular wave control and the other on special PWM control keeps the complexity manageable through clear role differentiation.
Data Source
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AI summary
A rotary electric machine control apparatus (1) suitably controls two inverters (10) connected to associated ends of open windings (8). The rotary electric machine control apparatus (1) performs target control involving: controlling a first one of the inverters (10), which is selected from a first inverter (11) and a second inverter (12), by rectangular wave control; and controlling a second one of the inverters (10) by special pulse width modulation control that is one type of pulse width modulation control. The special pulse width modulation control is a control method to produce a switching pattern (Su2+) that is based on a difference between a switching pattern resulting from the pulse width modulation control and a switching pattern (Su1+) resulting from the rectangular wave control when a target voltage is to be generated in the open windings (8).