Multiphase Soft-Switched DC-DC Converter With Interleaved Control
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Solution Overview
Problem
High-frequency DC-DC converters face challenges with significant switching losses, large component requirements, complex control circuitry, and inefficiency due to high switching frequencies, which are exacerbated by the need for large capacitors and precise timing in quasi-resonant and parallel converter topologies.
Innovation Solution
The solution involves operating multiple converter circuits in parallel with a staggered, multiphase sequencing that enables zero-current and zero-voltage switching without pre-setting timing, using capacitors, inductors, and semiconductor switches in a full bridge configuration, allowing for soft-switching and reduced switching losses, with smaller components and simplified control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switching frequency is increased to enable increased power transfer and reduce output filter size, then power transfer capability and filter size are improved, but switching losses in semiconductor switches increase significantly
Solution Approach 1:
The patent employs periodic switching action with controlled duty cycles to transfer energy in discrete packets through multiple converter slices. By periodically switching each slice on and off in sequence rather than continuous high-frequency switching, the system achieves effective power transfer while allowing each switch to operate at lower frequencies, thereby reducing switching losses while maintaining overall high power transfer capability
Solution Approach 2:
The converter is divided into multiple independent converter slices that operate in parallel but are switched sequentially. Each slice processes a portion of the total power, allowing the system to achieve high power transfer capability through parallel operation while each individual switch operates at lower frequency with reduced losses. The segmentation enables the system to combine the benefits of higher effective power transfer with lower individual switching losses
2Loss of energy
If quasi-resonant converter topology is used to achieve zero-current and zero-voltage switching, then switching losses are reduced and operating frequency can be increased, but relatively large capacitors are required and control becomes complex
Solution Approach 1:
The complex control requirements are segmented and distributed across multiple independent converter slices, each with its own simplified control logic. Rather than implementing complex centralized resonance control for the entire system, each slice operates with independent switching control, distributing the control complexity and reducing the burden on any single control unit while achieving soft-switching conditions
Solution Approach 2:
The patent employs dynamic switching sequences where the operation of each converter slice is adjusted based on the state of other slices. The switching timing and duty cycles are dynamically coordinated to ensure that when one slice is active, others are in appropriate states, enabling soft-switching conditions to be achieved through dynamic interaction rather than complex predetermined resonance control
3Productivity
If multiple converter circuits are operated in parallel to increase power transfer, then power capability is improved, but control complexity and component requirements increase
Solution Approach 1:
The parallel converter system is segmented into identical or similar modular slices that can be independently controlled. Each slice has the same basic structure and control logic, which simplifies the overall control architecture compared to managing fundamentally different parallel converters. The segmentation into standardized modules makes the system scalable while controlling complexity
Solution Approach 2:
The parallel converter slices operate with periodic switching sequences that are coordinated in time. By implementing periodic switching patterns with appropriate phase relationships between slices, the system achieves increased power transfer capability through parallel operation while the periodic nature of the control simplifies timing and coordination compared to arbitrary or continuously adjusted switching schemes
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
This approach results in high-efficiency energy transfer with low ripple voltage, reduced switching losses, simplified control, and smaller components, enabling operation at higher frequencies with reduced electromagnetic radiation and component size.
Implementation Method 1
Each converter circuit comprises a capacitor and an inductor, and a switching circuit for controlling the current flow through the converter circuit
Implementation Method 2
When the switch is closed, the circuit enters the energy transfer phase, during which energy is delivered from the capacitor to the output through the inductor
Implementation Method 3
resonant and quasi-resonant DC-to-DC converters were developed which permitted zero-current (ZCS) and zero-voltage (ZVS) switching
Data Source
AI summary
A high-frequency DC to DC converter comprising n transient converter circuits (1, 2...n) operating in parallel. The converter has constant transfer characteristics, and the transient converter circuits are operated phase-shifted by 360°/n and with interleaved duty cycles, which results in a continuous energy transfer through the circuit. The circuit is also soft-switched, with very low switching losses. In particular, the active semiconductors only switch off a relatively small magnetization current, during a recovery phase which can last as long as (n-1)/n of the switching phase period.