Power Pulsation Buffer for Stable DC-Link Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional single-phase AC-connected power supplies face limitations in power density, efficiency, and cost due to the need for large DC-link capacitors and redundant regulation in both PFC and DC-DC converter stages, which also increase system size and complexity.
Innovation Solution
A power supply incorporating a power pulsation buffer (PPB) that regulates the DC-link voltage, allowing the DC-DC converter to be unregulated, thus reducing the size of the DC-link capacitor and simplifying control, while maintaining a stable output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large DC-link capacitor is used to limit voltage ripple and provide energy storage during line dropout, then the power supply reliability is improved, but the device size and cost increase
Solution Approach 1:
The energy storage function is segmented between two components: the DC-link capacitor handles high-frequency voltage ripple, while the power pulsation buffer capacitor handles low-frequency power pulsation and line dropout energy storage. This segmentation allows each capacitor to be optimized for its specific function, reducing the total capacitance required.
Solution Approach 2:
The power pulsation buffer is introduced as an intermediary component between the PFC stage and the DC-DC converter. It absorbs power pulsations and provides energy during line dropout, mediating the energy transfer and allowing the DC-link capacitor to be smaller while maintaining reliability.
2Stability of the object's composition
If both PFC rectifier and DC-DC converter are fully regulated with independent controllers, then the output voltage stability is improved, but the device complexity and cost increase
Solution Approach 1:
The regulation function is extracted from the DC-DC converter and relocated to the power pulsation buffer. The DC-DC converter operates in simple fixed conversion mode without active control, while the PPB's control system performs the regulation function, simplifying the overall control architecture.
Solution Approach 2:
The control functions of the PFC stage and the regulation function are merged into a coordinated control system. The PPB switch arrangement is controlled based on the output voltage feedback, combining the regulation task with the existing PFC control infrastructure, reducing the need for separate independent controllers.
3Stability of the object's composition
If both PFC rectifier and DC-DC converter process full power with independent regulation, then the output voltage control is improved, but the system efficiency decreases
Solution Approach 1:
The regulation task is extracted from the DC-DC converter, allowing it to operate in a simpler, more efficient fixed conversion mode. The regulation function is performed by the PPB control system, which operates at lower power levels, reducing overall system losses.
4Reliability
If a large DC-link capacitor is used to maintain voltage during line dropout, then the power supply reliability is improved, but the power density decreases
Solution Approach 1:
The energy storage requirement is segmented between the DC-link capacitor and the power pulsation buffer capacitor. The PPB is specifically designed to provide energy during line dropout events, allowing the DC-link capacitor to be smaller and not dominate the overall power supply size, thus improving power density.
Solution Approach 2:
The power pulsation buffer acts as an intermediary energy storage element that specifically addresses line dropout conditions. It mediates the energy transfer during transient events, allowing the main DC-link capacitor to be reduced in size, improving power density while maintaining reliability.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The disclosed concepts relate to a power supply incorporating a power pulsation buffer (PPB). The power supply comprises a power factor correction (PFC) stage including a DC-link capacitor, and an unregulated DC-DC converter that receives the DC-link voltage across the DC-link capacitor and generates an output voltage. The PPB is connected between the PFC stage and unregulated DC-DC converter, and comprises a buffer capacitor. The PFC stage is configured to regulate a voltage across the buffer capacitor, and the PPB is configured to regulate the DC-link voltage across the DC-link capacitor. As a result, the voltage across the DC-link capacitor may be maintained at a near-constant value, whilst the voltage across the buffer capacitor varies. This means that the DC-DC converter may be unregulated, efficient and highly compact, as an input voltage is closely regulated.