Modulation Control for Dual Active Bridge Converters in High Voltage PV Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MPPT charge controllers for photovoltaic systems are limited to low input voltages, making them unsuitable for high voltage grid-connected photovoltaic systems, as they incur high peak currents and power losses, and face control challenges with increasing input voltages.
Innovation Solution
A modulation control scheme for a dual active bridge (DAB) DC to DC converter that minimizes conduction and switching losses by employing MOSFETs, synchronous rectification, and achieving soft switching operations, allowing bidirectional power flow with reduced RMS current and circulating energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional MPPT charge controllers are used for high voltage photovoltaic systems, then the system can operate with simple control, but the system incurs high peak currents and power losses
Solution Approach 1:
The patent implements a dynamic modulation control scheme that adjusts switching patterns and duty cycles in real-time based on operating conditions. The control scheme dynamically transitions between different operating modes (PWM, CCM, DCM) to optimize performance across varying voltage and power levels, thereby reducing power losses while maintaining operational simplicity.
Solution Approach 2:
The patent changes key operating parameters including switching frequency, duty cycle, and modulation depth to optimize converter performance. By dynamically adjusting these parameters based on input voltage and power level, the system minimizes conduction and switching losses without requiring complex hardware modifications.
2Device complexity
If conventional MPPT charge controllers are used for high voltage photovoltaic systems, then the system structure remains simple, but the controllers face control challenges with increasing input voltages
Solution Approach 1:
The patent segments the control strategy into distinct operating modes (PWM mode, CCM mode, DCM mode) that are activated based on specific voltage and power thresholds. This segmentation allows the controller to handle high voltage conditions through appropriate mode selection rather than requiring a completely redesigned control architecture, maintaining structural simplicity while improving reliability.
Solution Approach 2:
The control scheme dynamically adapts to varying input voltages by transitioning between different operating modes. The controller monitors voltage levels and automatically adjusts its control strategy, ensuring reliable operation across the full voltage range without increasing hardware complexity.
3Adaptability or versatility
If the dual active bridge converter operates in high voltage mode, then it can handle high voltage photovoltaic systems, but it incurs high conduction and switching losses
Solution Approach 1:
The patent employs periodic pulse-width modulation to control the dual active bridge converter. By using high-frequency switching with optimized duty cycles and phase shifts, the system achieves soft switching conditions that minimize both conduction and switching losses while maintaining high voltage handling capability.
Solution Approach 2:
The control scheme dynamically adjusts switching frequency, duty cycle, and phase shift parameters to optimize efficiency at different operating points. By changing these parameters in response to voltage and power conditions, the converter minimizes losses while maintaining adaptability to high voltage photovoltaic systems.
4Ease of operation
If standard PWM control is used in the dual active bridge converter, then the control implementation is straightforward, but the converter experiences high RMS current and circulating energy
Solution Approach 1:
The patent introduces an intermediate control layer that sits between the standard PWM generator and the power switches. This intermediary control stage optimizes the switching patterns by introducing phase shifts and adjusting duty cycles, thereby reducing RMS current and circulating energy while keeping the overall control implementation straightforward.
Solution Approach 2:
The control scheme modifies key PWM parameters including duty cycle, switching frequency, and phase shift angle to optimize converter performance. By dynamically adjusting these parameters, the system reduces RMS current and circulating energy without requiring a complete redesign of the control implementation.
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 enables efficient operation of the dual active bridge converter in high voltage photovoltaic systems, reducing power losses and improving control accuracy, thus enhancing the overall efficiency and suitability for high voltage applications.
Implementation Method 1
A modulation control scheme for a dual active bridge (DAB) DC to DC converter that minimizes conduction and switching losses by employing MOSFETs, synchronous rectification, and achieving soft switching operations
Implementation Method 2
The cases or main operating regions are selected according to power levels and values of voltage differential, as well as the provision of appropriate transition or border operating regions between adjacent cases or main operating regions
Data Source
AI summary
A modulation control scheme for a series-connected dual active bridge (DAB) DC to DC converter in a maximum power point tracking charge controller used in a photovoltaic system controls operation of the converter in a forward direction power flow mode to control charging of a battery bank with electricity produced by the photovoltaic array. The modulation control scheme is also capable of operating the converter in a reverse direction power flow mode to control the flow of electricity from the battery bank to a DC load. The modulation control scheme divides the converter's operating range in each mode into five main cases of minimum root mean square (M-RMS) operating regions and seven main cases of full zero-voltage switching (F-ZVS) operating regions, as well as transition operating regions between adjacent main cases, based on applicable power level and value of voltage differential.