Isolated Multi-Phase SMPS for High Power With Lower EMI Ripple
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Solution Overview
Problem
Conventional isolated switched-mode power supplies (SMPS) face challenges in increasing output power while maintaining effective electromagnetic interference (EMI) shielding, reducing system size, and lowering costs.
Innovation Solution
The proposed solution involves an isolated SMPS system with N primary and secondary side circuits, an isolated control module, and N transformers. The system employs staggered phase control of power switches and synchronous rectifiers, utilizing an optocoupler for communication between the primary and secondary sides, to achieve multi-phase control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If higher output power is required, then power output is improved, but system size increases
Solution Approach 1:
The power supply system is divided into multiple parallel primary side circuits and secondary side circuits, each with its own transformer. By segmenting the total power output across multiple smaller transformer branches operating in staggered phases, the patent achieves higher total output power while each individual transformer maintains a compact size, thus resolving the contradiction between output power and system size.
Solution Approach 2:
The patent employs staggered phase control where multiple power switches and synchronous rectifiers operate at different phases. This periodic staggered operation allows multiple transformer branches to collectively deliver high power output while distributing the thermal and magnetic loading over time, enabling higher total power without proportionally increasing the size of each transformer branch.
2Power
If higher output power is required, then power output is improved, but EMI shielding capability deteriorates
Solution Approach 1:
By dividing the power conversion function across multiple independent transformer branches with staggered phase operation, the patent reduces the switching frequency and current stress on each individual branch. This segmentation lowers the electromagnetic interference generated by each branch, making EMI shielding more effective even at higher total power outputs.
Solution Approach 2:
The staggered phase control creates periodic, distributed switching events across multiple branches rather than simultaneous switching. This temporal distribution of switching actions reduces peak EMI emissions and allows for more effective EMI shielding design, as the interference is spread out in time and space rather than concentrated.
3Power
If higher output power is required, then power output is improved, but cost increases
Solution Approach 1:
The patent uses multiple smaller transformer branches instead of one large transformer. Each branch uses standard, off-the-shelf components that can be mass-produced, reducing the cost compared to a custom large transformer design. The modular segmented architecture allows for economies of scale in component procurement and simplifies manufacturing.
Solution Approach 2:
By changing the operating parameters of multiple smaller transformers (staggered phase control, distributed switching frequencies) rather than scaling up a single transformer, the patent achieves higher power output using cost-effective, standardized components. This parameter-based approach avoids the need for expensive custom-designed high-power components.
4Power
If higher output power is required, then power output is improved, but device complexity increases
Solution Approach 1:
The control function is segmented into a primary side control module and a secondary side control module, each managing specific circuits. This modular control architecture, coordinated through an optocoupler, distributes the control complexity across separate manageable units rather than requiring a single complex control system, making the overall high-power system easier to design and maintain.
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 reduced size and cost of each transformer branch, optimized EMI shielding, balanced thermal distribution, less output ripple, smaller required output capacitance, and improved cost effectiveness of the system.
Implementation Method 1
the optocoupler connected between the secondary side control module and the primary side control module. The secondary side control module generates optocoupler drive signals based on the output voltage signal from the isolated SMPS and the respective winding voltage signals, and the optocoupler receives the optocoupler drive signals and outputs optocoupler signals to the primary side control module.
Data Source
AI summary
The present invention relates to an isolated switched-mode power supply (SMPS) and an SMPS system. The isolated SMPS includes N (≥2) primary side circuits, N secondary side circuits, an isolated control module and N transformers. Each primary side circuit includes a power switch, and each secondary side circuit includes a synchronous rectifier. The isolated control module includes a primary side control module, an optocoupler and a secondary side control module, and is adapted to generate, based on output voltage signal and winding voltage signals from secondary windings, N PWM signals staggered in phase from one another and transmit them to control terminals of power switches, enabling staggered control of N power switches. This multi-phase control provided by the isolated control module in the isolated SMPS allows for optimized EMI shielding performance, a balanced thermal distribution, less output ripple, smaller required output capacitance and significantly improved cost effectiveness of isolated SMPS.