Three-Phase PWM Signal Generation Using Vector Segmentation
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Solution Overview
Problem
Conventional three-phase PWM systems face limitations in holding time width and efficiency due to restricted voltage command vector range and increased harmonics, noise, and vibration, especially when using three kinds of basic voltage vectors with a phase difference of 120 degrees or 60 degrees.
Innovation Solution
A three-phase PWM signal generating apparatus that combines three basic voltage vectors with a zero vector, allowing for high percentage modulation and reduced current detection limitations without adding new devices, by redistributing production time ratios to enhance switching mode holding time and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If three kinds of basic voltage vectors with a phase difference of 120 degrees or 60 degrees are used, then the voltage command vector range is restricted, but the holding time width of switching modes is reduced and efficiency deteriorates
Solution Approach 1:
The patent segments the voltage command vector range into multiple regions, each region being controlled by a specific combination of basic voltage vectors. By dividing the overall control space into manageable segments, the system can optimize the holding time width within each segment while maintaining comprehensive voltage command coverage across all regions.
Solution Approach 2:
The patent dynamically selects and combines different basic voltage vectors based on the current operating conditions and voltage command requirements. This dynamic approach allows the system to adaptively adjust the holding time width of switching modes for each basic voltage vector, optimizing efficiency across the entire voltage command vector range rather than using a fixed configuration.
2Adaptability or versatility
If three kinds of basic voltage vectors with a phase difference of 120 degrees or 60 degrees are used, then the voltage command vector range is restricted, but harmonics, noise, and vibration increase
Solution Approach 1:
The patent changes the parameters of the basic voltage vectors by adjusting their phase differences and combining them in different ratios. By varying these parameters dynamically, the system can minimize harmonics, noise, and vibration across the entire voltage command vector range, rather than being constrained by a fixed vector configuration that generates excessive harmful factors.
Solution Approach 2:
The patent creates a composite control strategy by combining multiple basic voltage vectors with different phase relationships (120 degrees and 60 degrees). This composite approach allows the system to leverage the advantages of each vector type while canceling out their individual disadvantages, resulting in reduced harmonics, noise, and vibration across the full operating range.
3Adaptability or versatility
If conventional PWM signal generation methods are used, then the percentage modulation range is limited, but additional hardware is required to expand it
Solution Approach 1:
The patent makes the existing basic voltage vectors and switching elements perform multiple functions by dynamically reconfiguring their combinations and phase relationships. This multi-functional approach allows the system to achieve an expanded percentage modulation range using the same hardware components, eliminating the need for additional devices while increasing adaptability.
Solution Approach 2:
The patent expands the percentage modulation range by changing the operational parameters of the existing hardware, specifically by adjusting the phase differences and time ratios of the basic voltage vectors. This parameter-based expansion allows the system to achieve wider modulation capabilities without adding new hardware, maintaining simplicity while increasing versatility.
Data Source
AI summary
An apparatus for generating a three-phase pulse-width-modulation signal for a three-phase voltage inverter employing a semiconductor switching element includes a generating unit that generates the three-phase pulse-width-modulation signal based on at least one combination of three basic voltage vectors and at least a zero vector.