DC to DC Converter Soft Switching Control for High Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional DC to DC converters in marine power systems face efficiency losses due to high voltage operations, leading to lower frequency and power density designs, especially when using multiple semiconductor devices in series with conventional control methods.
Innovation Solution
A DC to DC power converter system that includes a resonant LLC dual active bridge converter with a controller that adjusts switching frequency and phase shift based on a reference output current, maintaining efficiency through soft switching techniques even with series connected semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If multiple semiconductor devices are connected in series to operate at high voltages, then the voltage handling capability is improved, but the switching losses increase and soft switching is lost
Solution Approach 1:
The patent divides the high voltage semiconductor device into multiple series-connected lower voltage devices. Each device is controlled independently with dedicated switching signals, allowing the high voltage block to achieve soft switching through coordinated control of individual segments, thereby reducing overall switching losses while maintaining voltage handling capability.
Solution Approach 2:
The patent employs dynamic control of switching frequencies and phase shifts for each semiconductor device in the series connection. By adjusting the switching parameters dynamically based on operating conditions, the system maintains soft switching operation across the entire high voltage block, optimizing efficiency while handling high voltages.
2Device complexity
If conventional control methods are used with series connected semiconductor devices, then the device complexity is reduced, but the converter efficiency decreases and power density is limited
Solution Approach 1:
The patent incorporates feedback control mechanisms that monitor the operating state of the DC-DC converter and adjust the switching signals accordingly. This feedback system enables the complex coordinated control of multiple series-connected devices, maintaining soft switching and high efficiency while providing adaptive optimization based on real-time conditions.
Solution Approach 2:
The patent changes multiple control parameters including switching frequencies, phase shifts, and pulse widths for each semiconductor device. By dynamically adjusting these parameters in a coordinated manner, the system achieves high efficiency and power density while managing the complexity through systematic parameter optimization rather than simplified conventional control.
3Loss of energy
If the switching frequency is reduced to maintain soft switching with conventional control, then the switching losses are reduced, but the power density decreases
Solution Approach 1:
The patent dynamically adjusts the switching frequency of each semiconductor device based on the load conditions and operating point. This dynamic frequency control allows the system to maintain soft switching at higher frequencies when needed, achieving both low switching losses and high power density by adapting the switching frequency rather than operating at a fixed reduced value.
Solution Approach 2:
The patent employs periodic switching patterns with coordinated phase shifts between multiple semiconductor devices. This periodic control structure enables high-frequency operation while maintaining soft switching through the resonant nature of the periodic excitation, thereby achieving high power density without incurring excessive switching losses.
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 system achieves high efficiency and power density by maintaining soft switching capabilities across varying load currents, reducing switching losses and enhancing overall converter performance.
Implementation Method 1
a resonant circuit for coupling the first bus converter and the second bus converter
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A direct current (DC) to DC power converter includes a first bus converter for converting a first DC bus voltage into a first high frequency AC voltage and a second bus converter for converting a second high frequency alternating current (AC) voltage into a second DC bus voltage. The DC to DC converter also includes a resonant circuit for coupling the first bus converter and the second bus converter and a controller for providing switching signals to the first bus converter and the second bus converter to operate the power converter in a soft switching mode. The controller includes a switching frequency controller for determining a switching frequency signal for the power converter based on a reference output current and a phase shift controller for determining a phase shift signal for the power converter. When the reference output current is lower than the a first load current value the switching frequency signal is maintained at a first switching frequency and the phase shift is determined according to the reference output current. Further, when the reference output current is above a second load current value the switching frequency signal is maintained at a second switching frequency and the phase shift is determined according to the reference output current. When the reference output current is between the first load current value and the second load current value, the switching frequency signal is adjusted according to a value of the reference output current and the phase shift is determined based on the switching frequency, the reference output current and perturbations in the output current.