Variable Inductor DC-to-DC Converter for Zero Voltage Switching
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Solution Overview
Problem
Conventional DC-to-DC converters face inefficiencies due to hard switching at light loads and reduced maximum output voltage at heavy loads, requiring complex circuit configurations and load detection for phase-shift control.
Innovation Solution
A DC-to-DC converter employing a variable inductor with inductance that decreases with current, enabling zero voltage switching at light loads and shortening the commutation overlap period at heavy loads, thus increasing maximum transmission power without additional complex circuit elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If phase-shift control is performed to enable zero voltage switching, then switching loss is reduced and conversion efficiency is improved, but the circuit complexity increases due to the need for load detection and additional control mechanisms
Solution Approach 1:
The magnetic core automatically adjusts the inductance based on the current flowing through it, eliminating the need for external load detection circuits or additional control mechanisms. The inductance changes self-regulatingly in response to current variations, enabling the system to adapt to different load conditions without additional complexity.
Solution Approach 2:
The inductance parameter of the magnetic core is changed dynamically based on current magnitude. At light loads, the inductance is larger to enable zero voltage switching; at heavy loads, the inductance decreases automatically to reduce commutation overlap period. This parameter change is achieved through the inherent magnetic characteristics of the core rather than external control.
2Reliability
If a large inductance is used for the primary resonance inductor, then zero voltage switching is achieved at light load, but the commutation overlap period increases and maximum output voltage decreases at heavy load
Solution Approach 1:
The inductance is made dynamic rather than fixed. The magnetic core's inductance automatically adjusts according to the current flowing through it, being larger at light loads to enable zero voltage switching and smaller at heavy loads to reduce commutation overlap period and increase maximum output voltage. This dynamic adaptation resolves the contradiction between the two operating conditions.
Solution Approach 2:
The inductance characteristic is segmented into different effective values based on current magnitude. The magnetic core provides different inductance levels automatically: a larger effective inductance at light loads and a smaller effective inductance at heavy loads, allowing the system to optimize performance for each operating regime without compromising the other.
3Productivity
If the inductance is decreased to reduce commutation overlap period, then maximum output voltage increases, but zero voltage switching cannot be achieved at light load
Solution Approach 1:
The inductance dynamically adapts to current conditions, being smaller at heavy loads to reduce commutation overlap and increase power transmission, and larger at light loads to enable zero voltage switching and reduce energy loss. This dynamic behavior eliminates the need to compromise between the two opposing requirements.
Solution Approach 2:
The inductance parameter changes automatically with current magnitude. The magnetic core's inherent characteristics cause the inductance to be larger when current is small (enabling zero voltage switching) and smaller when current is large (reducing commutation overlap), thus optimizing both energy efficiency and power transmission capability across different operating conditions.
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 allows for efficient zero voltage switching at light loads and increased maximum transmission power at heavy loads, improving control response speed and reducing waiting time for voltage stabilization without the need for complex circuitry or load detection.
Implementation Method 1
ZVS is attributed to the resonance between the parasitic capacitance between both ends of the switching element and the leakage inductance LIk1, i.e., the exchange of energy stored in the inductor with the capacitance
Implementation Method 2
the leakage inductance LIk1 tends to hold current, and the current held by this inductor charges or discharges the parasitic capacitances
Implementation Method 3
a variable inductor with inductance that decreases with current
Data Source
AI summary
A DC-to-DC converter includes a voltage converter having: a capacitance; at least one inductor configured to store energy and exchange stored energy with the capacitance; and a switching element configured to switch on and off a current flowing through the inductor and change direction of the current at each switching. The inductor includes a variable inductor whose inductance decreases with increase in the current.