Power Pulsation Buffering for Stable DC-Link Voltage
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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 an unregulated DC-DC converter, thereby 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 volume and power density are reduced
Solution Approach 1:
The power pulsation buffering function is segmented from the DC-link capacitor and assigned to a dedicated power pulsation buffer module. This separation allows the DC-link capacitor to be reduced in size while the PPB handles the pulsation energy, resolving the contradiction between reliability and volume.
Solution Approach 2:
The power pulsation buffer acts as an intermediary component between the PFC stage and DC-DC converter. It absorbs the double-line frequency power pulsations that would otherwise require a large DC-link capacitor, enabling a compact design while maintaining reliable operation during line dropout.
2Stability of the object's composition
If both PFC rectifier and DC-DC converter are fully regulated with dedicated controllers, then the output voltage stability is improved, but the device complexity and cost increase
Solution Approach 1:
The regulation function for DC-link voltage is extracted from the DC-DC converter control and assigned to the power pulsation buffer. This allows the DC-DC converter to operate in a simpler unregulated mode while the PPB maintains stable DC-link voltage, reducing overall control complexity.
Solution Approach 2:
The control functions of the PFC stage and power pulsation buffer are merged into a coordinated control system. The PFC regulates buffer capacitor voltage while the PPB regulates DC-link voltage, achieving output voltage stability through combined operation rather than dual independent regulation.
3Adaptability or versatility
If both PFC and DC-DC stages process full power with independent control, then the adaptability is improved, but the energy efficiency is reduced
Solution Approach 1:
The power pulsation buffer serves multiple functions: it buffers power pulsations, regulates DC-link voltage, and enables the DC-DC converter to operate in an efficient unregulated mode. This multi-functionality improves overall energy efficiency while maintaining system adaptability.
Solution Approach 2:
Instead of fully regulating both PFC and DC-DC stages, the system applies partial regulation through the PPB for DC-link voltage while allowing the DC-DC converter to operate without active regulation. This reduces redundant control actions and improves energy efficiency.
Data Source
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.