Interphase Transformer Startup Control to Prevent Saturation
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Solution Overview
Problem
Interleaved switched mode power supplies experience saturation of the interphase transformer during startup due to high inrush currents, which is exacerbated by conventional 180° out-of-phase switching of power modules, leading to power supply faults and undesired discharge paths.
Innovation Solution
Implement a controller to synchronize the switching of power modules during startup by setting the phase difference between pulse trains to zero, followed by a gradual increase to 180°, ensuring concurrent switching and preventing transformer saturation, and transitioning to interleaved operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If 180° out-of-phase switching is applied to power modules during startup, then power quality of AC output waveform is improved, but interphase transformer saturation is aggravated
Solution Approach 1:
The patent applies preliminary action by implementing a startup mode that temporarily disables interleaved switching for a predetermined time period after power-on. During this startup period, only non-interleaved switching is permitted, preventing transformer saturation before the magnetic core is energized and stabilized. After the startup period expires, the controller transitions to normal interleaved switching operation.
Solution Approach 2:
The patent applies dynamics by making the switching phase relationship time-dependent. The phase difference between power module switching signals is dynamically adjusted: during startup, the phase difference is effectively 0° (non-interleaved), and after the startup period, the phase difference transitions to 180° (interleaved). This dynamic adjustment allows the system to adapt its switching strategy based on the operational state.
2Illumination intensity
If interleaved switching is implemented during startup, then power quality is improved, but inrush current causes transformer saturation and power supply faults
Solution Approach 1:
The patent applies preliminary action by implementing a startup mode that temporarily disables interleaved switching for a predetermined time period after power-on. During this startup period, only non-interleaved switching is permitted, preventing transformer saturation before the magnetic core is energized and stabilized. After the startup period expires, the controller transitions to normal interleaved switching operation.
Solution Approach 2:
The patent applies dynamics by making the switching phase relationship time-dependent. The phase difference between power module switching signals is dynamically adjusted: during startup, the phase difference is effectively 0° (non-interleaved), and after the startup period, the phase difference transitions to 180° (interleaved). This dynamic adjustment allows the system to adapt its switching strategy based on the operational state.
3Power
If conventional 180° interleaved switching is used, then power rating is increased through parallel power modules, but current distribution becomes unbalanced during startup
Solution Approach 1:
The patent applies preliminary action by implementing a startup mode that temporarily disables interleaved switching for a predetermined time period after power-on. During this startup period, only non-interleaved switching is permitted, preventing transformer saturation before the magnetic core is energized and stabilized. After the startup period expires, the controller transitions to normal interleaved switching operation.
Solution Approach 2:
The patent applies dynamics by making the switching phase relationship time-dependent. The phase difference between power module switching signals is dynamically adjusted: during startup, the phase difference is effectively 0° (non-interleaved), and after the startup period, the phase difference transitions to 180° (interleaved). This dynamic adjustment allows the system to adapt its switching strategy based on the operational state.
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
Prevents interphase transformer saturation during startup by evenly distributing currents, thereby avoiding power supply faults and ensuring smooth transition to steady-state interleaved operation.
Implementation Method 1
The IPT ensures equal sharing of current through parallel paths by providing a high impedance path for circulating currents between the power modules and a low impedance path for current leading to an AC output stage
Implementation Method 2
control a phase difference between the first pulse train and the second pulse train by, during a startup period of the power supply, setting the phase difference to zero
Data Source
AI summary
A power supply comprises: a first power module and a second power module each coupled to an interphase transformer; and a controller to: apply a first pulse train and a second pulse train to the first power module and the second power module to cause switching of the first power module and the second power module, respectively, to generate a current that flows through the interphase transformer to an output node; and control a phase difference between the first pulse train and the second pulse train by, during a startup period of the power supply, setting the phase difference to zero to cause concurrent switching of the first power module and the second power module that prevents an inrush of the current to the output node from saturating the interphase transformer.