Soft Switching Power Inverter With Variable Phase Shift Control
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Solution Overview
Problem
Existing soft switching inverters have limited high-frequency operation due to restricted soft switching ranges and the need for large magnetic components, as well as switching losses associated with hard switching inverter controls, especially when the phase shift angle is fixed at 180 degrees.
Innovation Solution
A power inversion system with a control system that optimizes the phase shift angle based on the duty cycle, allowing for variable phase shift angles and switching configurations to maintain soft switching operations across a wider range, reducing switching losses and eliminating hard switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a fixed phase shift angle of 180 degrees is used in soft switching inverters, then zero voltage switching is achieved for some switches, but at least one switch operates under hard switching conditions causing large switching losses
Solution Approach 1:
The patent applies dynamics by making the phase shift angle variable rather than fixed. The control system dynamically adjusts the phase shift angle between bridge legs based on operating conditions to maintain soft switching for all switches across the entire duty cycle range, eliminating hard switching losses while adapting to different operational requirements.
Solution Approach 2:
The patent changes the parameter of phase shift angle from a fixed 180 degrees to a variable parameter that can be optimized. By adjusting this parameter based on duty cycle and operating conditions, the system achieves soft switching for all switches throughout the full duty cycle range, resolving the contradiction between energy loss and adaptability.
2Loss of energy
If the phase shift angle is reduced below 180 degrees to extend soft switching range, then more switches operate in soft switching mode, but large magnetic components are still required due to insufficient flux reduction
Solution Approach 1:
The system dynamically optimizes the phase shift angle to achieve soft switching for all switches across the full duty cycle range. This dynamic control eliminates the need for oversized magnetic components by ensuring complete soft switching operation, thereby reducing magnetic flux requirements and component weight.
Solution Approach 2:
By changing the phase shift angle parameter optimally based on operating conditions, the system achieves sufficient flux reduction without requiring large magnetic components. The optimized parameter adjustment ensures soft switching while minimizing magnetic component size.
3Ease of manufacture
If hard switching inverter control is used, then implementation is simpler, but switching frequency must be limited to avoid large switching losses
Solution Approach 1:
The patent implements a dynamic phase shift angle control that maintains soft switching for all switches across the entire duty cycle range. This dynamic approach enables high-frequency operation without the switching losses that would limit hard switching systems, achieving both high productivity and reasonable implementation complexity.
Solution Approach 2:
By optimizing the phase shift angle parameter dynamically, the system achieves soft switching operation that enables high switching frequencies. This parameter optimization resolves the contradiction by allowing high-frequency operation while maintaining implementation feasibility through a unified control approach.
4Loss of energy
If duty cycle is limited to maintain soft switching, then switching losses are reduced, but the soft switching range becomes restricted
Solution Approach 1:
The system uses dynamic phase shift angle adjustment to maintain soft switching across the full duty cycle range from 0 to 100%. This dynamic control eliminates the need to restrict duty cycle, achieving both low switching losses and complete adaptability across all operating conditions.
Solution Approach 2:
By optimally adjusting the phase shift angle parameter based on duty cycle, the system achieves soft switching for all switches throughout the entire duty cycle range. This parameter optimization resolves the contradiction by enabling full duty cycle operation while maintaining low switching losses.
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
Enables high-efficiency, high-frequency operation with an unlimited soft switching range, minimizing switching losses and magnetic component requirements, and preventing diode reverse recovery losses.
Implementation Method 1
Soft switching inverters help to alleviate switching losses by switching the transistor on when the voltage across it reaches zero (zero voltage switching) and/or switching the transistor off when the current flowing through it reaches zero (zero current switching)
Implementation Method 2
a plurality of inductors with at least one inductor coupled between a midpoint of each bridge leg and an LCL filter, the inductors in each phase leg being magnetically coupled
Data Source
AI summary
A power inversion system includes an input and output coupleable to a DC power and an AC load, respectively, and a power inverter including a plurality of phase legs each having two bridge legs coupled in parallel with at least two switch and antiparallel diode pairs coupled in series. The system also includes a plurality of inductors, with at least one inductor coupled between a midpoint of each bridge leg and an LCL filter, the inductors in each phase leg being magnetically coupled. The system further includes a control system to drive the power inverter in a soft switching configuration, the control system programmed to output a switching signal to the power inverter according to a duty cycle and a phase shift angle, determine a value of the duty cycle, and optimize the phase shift angle of the power inverter based on the value of the duty cycle.