Transformer Tap Switching for Wide Input Voltage Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional switching mode power supplies face limitations in handling wide input voltage ranges due to constraints on duty cycle and turns ratio, leading to increased size and cost when trying to maintain efficient power conversion.
Innovation Solution
The solution involves controlling both the duty cycle and turns ratio of the power transformer, dividing the input voltage range into sub-ranges with a constant turns ratio, allowing for soft transitions between these ranges to maintain efficient power conversion without large transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the duty cycle range is increased to cover a wide input voltage range, then the input voltage range coverage is improved, but the minimum pulse width becomes excessively small and the switching transitions become unrealistic
Solution Approach 1:
The input voltage range is divided into multiple sub-ranges, with each power converter optimized for a specific sub-range. This segmentation allows each converter to operate with realistic duty cycles and pulse widths within its designated range, while the combination of multiple converters achieves wide overall voltage coverage.
Solution Approach 2:
The system dynamically selects which power converter to activate based on the current input voltage level. This dynamic operation ensures that the active converter always operates within its optimal duty cycle range, avoiding the unrealistic minimum pulse width problems that would occur with a single converter covering the entire voltage range.
2Adaptability or versatility
If multiple power converters are connected in parallel to cover a wide input voltage range, then the voltage range coverage is improved, but the number of power converters and system size increases
Solution Approach 1:
Each power converter is designed with specific local optimizations for its designated voltage sub-range, including tailored component values and characteristics. This allows each converter to be smaller and more efficient for its specific range, reducing the overall system size compared to using oversized converters that must handle the entire voltage range.
Solution Approach 2:
The overall power conversion function is segmented across multiple specialized converters rather than using a single general-purpose converter. This segmentation enables more efficient utilization of components and reduces redundant capacity in each individual converter, leading to a more compact overall system.
3Adaptability or versatility
If the switching frequency is reduced to handle wide input voltage range, then the voltage range coverage is improved, but the magnetic components and filter size increase
Solution Approach 1:
The wide voltage range handling function is segmented across multiple converters operating at high switching frequency, each optimized for its sub-range. This allows the use of smaller magnetic components and filters in each converter compared to a single converter operating at reduced frequency, while achieving the same overall voltage range coverage.
Solution Approach 2:
The system changes the operating parameters (switching frequency, duty cycle) of each converter based on the input voltage level. By maintaining high switching frequency across all converters and adjusting duty cycles according to voltage sub-range, the system avoids the need for large magnetic components that would result from frequency reduction.
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 extends the minimum duty cycle and pulse width, reduces RMS current and power losses, and lowers voltage stress on switches, resulting in higher efficiency and reduced converter size and cost.
Implementation Method 1
a power transformer with a primary winding and a secondary winding
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
A power conversion system (100) includes an input terminal that is arranged to be connected to a voltage source (Vin); a transformer (T1) having a first winding connected to the input terminal and a second winding connected to an output terminal of the power conversion system (100), either the first winding or the second winding is provided with at least three taps that are arranged to divide the first winding or the second winding into at least two sub-windings; at least one tap switch (Qi) connected to the at least two sub-windings; a control circuit (108) connected to the at least one tap switch (Qi); and at least one switch (Si) connected to the at least one tap switch (Qi). The control circuit (108) is arranged to control the at least one tap switch (Qi) to control the turns ratio of the transformer (T1).