Medium High Voltage Energy Conversion Modular Control
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Solution Overview
Problem
Conventional medium and high voltage energy conversion systems for photovoltaic power generation have complex control strategies, high costs, and poor stability and reliability due to the need for coupling control in high-voltage isolated DC/DC converters.
Innovation Solution
A medium and high voltage energy conversion system with a system controller implementing a voltage-current double loop control strategy, using open-loop or closed-loop control for high-voltage isolated DC/DC converters, allowing modular control and current sharing without coupling, and including a filter module, cascade modules, and a common DC bus for grid-connected control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coupling control is performed on high-voltage isolated DC/DC converters to achieve current sharing, then current sharing is achieved, but the control strategy becomes complicated and system cost increases
Solution Approach 1:
The patent divides the control system into independent modules: each high-voltage isolated DC/DC converter operates independently with its own control unit, while a separate central controller coordinates between modules. This segmentation allows current sharing without complex coupling control, as each module can be controlled independently based on its own operating conditions while the central controller balances the overall system.
Solution Approach 2:
The patent introduces a central controller as an intermediary between the independent DC/DC converter modules. This intermediary coordinates current sharing by receiving status information from each module and distributing control instructions, thereby achieving current balance without requiring direct complex coupling control between converters.
2Reliability
If coupling control is performed on high-voltage isolated DC/DC converters, then current sharing is achieved, but system cost increases
Solution Approach 1:
By segmenting the control architecture into independent converter modules with standardized control units and a separate central controller, the system becomes more manufacturable. Each module can be produced independently using standardized designs, reducing overall system cost while maintaining current sharing capability through the centralized coordination.
Solution Approach 2:
The patent employs universal control units that can be applied to each DC/DC converter module independently. These standardized control modules perform multiple functions including local voltage regulation, current measurement, and communication with the central controller, thereby reducing overall system cost through component reuse and standardization.
3Reliability
If coupling control is performed on high-voltage isolated DC/DC converters, then current sharing is achieved, but stability and reliability of system output deteriorate
Solution Approach 1:
The patent segments the control function into local independent control units and a central coordinating controller. Each local control unit maintains stable operation of its associated DC/DC converter independently, while the central controller provides high-level coordination for current sharing. This segmentation isolates stability issues to individual modules, preventing propagation of disturbances across the entire system.
Solution Approach 2:
The patent implements feedback mechanisms at two levels: local feedback in each DC/DC converter control unit for immediate voltage and current regulation, and central feedback from the main controller for overall system balance. This multi-level feedback ensures stable operation by continuously monitoring and adjusting system parameters, maintaining reliability while achieving current sharing.
Data Source
AI summary
A medium and high voltage energy conversion system is provided. An input terminal of each of high-voltage isolated DC/DC converters in a phase circuit of the system is connected to a common DC bus. Each of the high-voltage isolated DC/DC converters converts, based on an open-loop control strategy or a closed-loop control strategy, a DC input voltage of a cascade module connected to the high-voltage isolated DC/DC converter into an instruction value related to a voltage of the common DC bus. A system controller of the system calculates, based on at least a voltage-current double loop control strategy, a three-phase modulation instruction to be sent to the cascade modules in three phases according to a parameter related to the voltage of the common DC bus, to implement grid-connected control on three phase circuits.