Multiphase Inverter Circuit With Coupled ZVS Switching
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Solution Overview
Problem
Conventional inverter circuits with H4 topology suffer from high switching power consumption due to reverse recovery power consumption of body diodes, leading to low conversion efficiency and increased common-mode interference.
Innovation Solution
A multiphase inverter circuit with non-interleaved inverter circuits and an inverting coupling transformer, where power transistors are configured to form a current loop through their body diodes before conducting, achieving zero-voltage soft switching (ZVS) and reducing reverse recovery power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional bipolar high-frequency sinusoidal pulse width modulation (SPWM) method is used with H4 topology, then the inverter circuit can generate AC power, but the switching power consumption is large due to reverse recovery power consumption of body diodes
Solution Approach 1:
The patent applies preliminary action by configuring the switching sequence such that the body diode conducts before the corresponding power transistor conducts. This pre-positioning of current flow through the diode before transistor activation enables zero-voltage switching conditions to be established in advance, reducing the reverse recovery power consumption when the transistor subsequently switches
Solution Approach 2:
The patent changes the switching parameters by introducing a specific phase difference between bridge arm units that is greater than the dead time and less than half the switching period. This parameter adjustment optimizes the timing relationship to ensure body diode conduction precedes transistor conduction, achieving zero-voltage soft switching and reducing switching losses
2Loss of energy
If unipolar or hybrid modulation methods are used to improve conversion efficiency, then switching power consumption is reduced, but common-mode interference and leakage current increase
Solution Approach 1:
The patent introduces asymmetry through the inverting coupling transformer with its specific winding configuration (first winding and second winding with heteropolar and homopolar ends). This asymmetric transformer structure, combined with the phase-shifted bridge arm units, creates a switching pattern that reduces common-mode voltage fluctuations while maintaining the zero-voltage soft switching benefits, thereby reducing both switching losses and common-mode interference simultaneously
3Loss of energy
If body diode reverse recovery is minimized through switching sequence optimization, then switching power consumption is reduced, but the circuit complexity increases
Solution Approach 1:
The patent introduces the inverting coupling transformer as an intermediary element between the bridge arm units and the output. This transformer mediates the switching actions by providing galvanic isolation and voltage transformation while the controlled phase difference ensures that switching operations occur under zero-voltage conditions. The intermediary transformer simplifies the overall control complexity by providing natural isolation and transformation functions that would otherwise require additional control circuitry
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
The solution significantly reduces switching power consumption, enables higher switching frequencies, and improves conversion efficiency while minimizing common-mode interference and leakage current.
Implementation Method 1
the inverting coupling transformer is configured to form a current loop with the first bridge arm unit and the second bridge arm unit so that the body diode conducts before a corresponding power transistor conducts
Data Source
AI summary
A multiphase inverter circuit and a modulation method thereof. The multiphase inverter circuit is configured for generating a target alternating current power based on a direct current power provided by a DC power supply, and the multiphase inverter circuit includes at least one non-interleaved inverter circuit; the non-interleaved inverter circuit includes: a first bridge arm unit, a second bridge arm unit, and an inverting coupling transformer. When the first pulse signal and the second pulse signal with a phase difference pass through the inverting coupling transformer, a current loop can be formed within the non-interleaved inverter circuit so that the body diodes of the power transistors conduct before the power transistors conduct, thereby reducing the reverse recovery power consumption of the body diode of the corresponding power transistor and realizing zero-voltage soft switching.