Closed-loop DPWM Control for Three-phase Inverter Switching Losses
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Solution Overview
Problem
Existing three-phase inverter control techniques for electrified vehicles are inefficient due to open-loop discontinuous pulse-width modulation (DPWM) methods, which result in increased switching losses and decreased efficiency, as they do not adapt to changing power factors and rely on predefined zero-voltage vectors.
Innovation Solution
Implementing closed-loop DPWM control for three-phase inverters in electrified vehicles, utilizing real-time feedback from electric motor current and position to select one of two zero-voltage vectors, thereby optimizing switching patterns and reducing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If open-loop discontinuous pulse-width modulation (DPWM) methods are used for three-phase inverter control, then the control implementation is simple, but switching losses increase and efficiency decreases
Solution Approach 1:
The patent implements closed-loop control by continuously monitoring the output voltage vector and using this feedback to dynamically select the optimal zero-voltage vector. The controller compares the actual output voltage with reference values and adjusts the switching strategy in real-time based on the power factor conditions, thereby minimizing switching losses while maintaining simple implementation through automated feedback-based decision making.
Solution Approach 2:
The patent transitions from static open-loop DPWM to dynamic closed-loop control where the zero-voltage vector selection changes dynamically based on real-time power factor conditions. The controller adapts the switching strategy by selecting between different zero-voltage vectors (V0 or V7) depending on the instantaneous power factor, optimizing efficiency across varying operating conditions while keeping the control structure relatively simple.
2Ease of operation
If predefined zero-voltage vectors are used in open-loop DPWM control, then the control strategy is straightforward, but the system cannot adapt to changing power factors
Solution Approach 1:
The system uses feedback from the output voltage vector to dynamically determine which zero-voltage vector to apply. By continuously monitoring the power factor conditions and comparing actual output with reference values, the controller automatically adapts its switching strategy to changing load conditions, maintaining both simplicity and adaptability through intelligent feedback-based selection.
Solution Approach 2:
The patent changes the operating parameters of the inverter control by dynamically switching between different zero-voltage vectors (V0 and V7) based on power factor conditions. This parameter change allows the system to adapt to varying load characteristics while maintaining a straightforward control structure that selects from predefined vector options based on real-time conditions.
3Loss of energy
If closed-loop DPWM control with real-time feedback is implemented, then switching losses are reduced and efficiency improves, but the control complexity increases
Solution Approach 1:
While implementing feedback-based closed-loop control to reduce switching losses, the patent maintains relatively simple control logic by using the feedback primarily for zero-voltage vector selection rather than complete control restructuring. The feedback mechanism compares output voltage with reference values and triggers simple switching decisions, thereby reducing energy losses without proportionally increasing control complexity.
Solution Approach 2:
The patent introduces dynamic adaptation through real-time power factor monitoring and conditional zero-voltage vector selection. This dynamic approach reduces switching losses by adapting to changing conditions, while the control complexity remains manageable because the system only adjusts specific switching parameters (zero-voltage vector selection) rather than overhauling the entire control architecture.
4Productivity
If dynamic selection of zero-voltage vectors based on output voltage vector is implemented, then inverter efficiency is optimized across varying power factors, but the control algorithm becomes more complex
Solution Approach 1:
The patent optimizes inverter efficiency by dynamically changing the zero-voltage vector parameter based on power factor conditions. The control algorithm monitors the output voltage vector and switches between V0 and V7 to minimize switching losses. This parameter-based optimization approach improves productivity (inverter efficiency) while keeping the algorithm complexity relatively low by focusing changes on a specific control parameter rather than the entire control system.
Solution Approach 2:
The control algorithm becomes dynamically adaptive by selecting zero-voltage vectors based on real-time power factor measurements. This dynamic selection optimizes inverter efficiency across varying operating conditions. The algorithm complexity increases only moderately because the system uses simple conditional logic based on power factor thresholds to determine vector selection, rather than implementing complex optimization algorithms.
Data Source
AI summary
Techniques are presented for more efficient three-phase inverter control for electrified vehicles (EVs). The techniques can be executed by a controller of an EV that includes one or more processors. Specifically, the techniques include closed-loop discontinuous pulse-width modulation (DPWM) control of a three-phase inverter based on electric motor current feedback. The three-phase inverter control techniques can be further based on electric motor/rotor position feedback. Based on the feedback, the techniques can select one of a plurality of zero-voltage vectors in real-time. The selected zero-voltage vector can be used when generating duty cycles for switching of the three-phase inverter, which can result in decreased switching losses and increased efficiency of the three-phase inverter.