Bi-directional Buck-Boost DC-DC Converter with Center-Tapped Transformer
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Solution Overview
Problem
Conventional DC/DC converters for electric vehicles and hybrid systems have low efficiency due to all power being processed through inductor-switch-diode pairs, limiting flexibility and efficiency in providing a wide range of output voltages for energy storage and DC bus applications.
Innovation Solution
A bi-directional buck/boost DC-DC converter topology using a transformer with a center tap and two bridge circuits, each with switches capable of bidirectional operation, coupled with a resonant circuit for soft switching and PWM control, allowing partial power processing and efficient voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional DC/DC converter topology with inductor-switch-diode pairs is used, then the converter can transfer energy between energy storage device and DC bus, but all power must be processed through the converter leading to low efficiency
Solution Approach 1:
The converter is divided into two independent half-phase modules, each handling half of the total power. This segmentation allows only the necessary portion of power to be processed through the converter circuitry, while the other half is directly transferred, thereby improving efficiency while maintaining full power processing capability
Solution Approach 2:
Instead of processing all power through the converter, only half of the power is processed through the inductor-switch-diode pairs, while the other half is directly transferred. This partial action reduces losses in the power processing components while still achieving the required voltage conversion and power transfer
2Adaptability or versatility
If conventional DC/DC converter topology is used, then energy transfer is possible, but there is limited flexibility in providing wide range of output voltages
Solution Approach 1:
Each half-phase module is designed to be universal and can operate in multiple modes (buck, boost, or direct transfer) depending on the voltage requirements. This multi-functionality allows the converter to provide a wide range of output voltages while using the same basic circuit topology, reducing overall complexity
Solution Approach 2:
The converter dynamically switches between different operating modes (buck mode, boost mode, direct transfer mode) based on the real-time voltage requirements of the DC bus and energy storage device. This dynamic operation provides flexible voltage regulation without requiring multiple fixed-topology converters
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 achieves higher efficiency and flexibility in voltage regulation, enabling optimized DC bus voltage for motor speed and efficient charging during regenerative braking, with partial power processing and soft switching improving overall system efficiency.
Implementation Method 1
coupled with a resonant circuit for soft switching
Implementation Method 2
a transformer. The transformer includes a first winding coupled to the first bridge circuit and a second winding coupled to the energy storage device
Data Source
Figure 1
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AI summary
An electronic drive circuit is provided. The electronic drive circuit includes an energy storage device (102) and a first bridge circuit (106) coupled to the energy storage device (102). The first bridge circuit (106) includes at least one leg having two switches (108,110). The electronic drive circuit also includes a transformer (126). The transformer (126) includes a first winding (124) coupled to the first bridge circuit (106) and a second winding (136) coupled to the energy storage device (102) through a center tap (139). The electronic drive circuit further includes a second bridge circuit (138) coupled to the second winding (136) of the transformer (126). The second bridge circuit (138) includes a pair of switches (144,148) operable to conduct in both directions and block voltage in both directions. The electronic drive circuit additionally includes a DC bus (162) coupled to the second bridge circuit (138) and a controller (132), which is configured to buck or boost a DC voltage from the energy storage device (102) to supply to the DC bus (162) as well as buck or boost a DC voltage from the DC bus (162) to supply to the energy storage device (102).