Dynamic DC Bus Voltage Control in Vienna Rectifier Systems
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Solution Overview
Problem
High-voltage DC bus systems in industrial applications face increased switch failure rates and reduced capacitor lifetime due to high voltage stresses, necessitating a method to maintain DC bus voltage at a lower level for improved system reliability.
Innovation Solution
A voltage-adjusting device and method within a power conversion system, comprising a Vienna rectifier, DC bus, and inverter, utilize a grid voltage sampling module, voltage-adjusting module, current control module, and pulse width modulation module to limit the DC bus voltage within a stable range, preventing high voltage levels during light or empty load operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-voltage DC bus system is used to meet power requirements, then power capability is improved, but switch failure rate increases and capacitor lifetime decreases
Solution Approach 1:
The patent implements dynamic DC bus voltage adjustment by detecting load conditions and actively controlling the rectifier to maintain voltage within an optimal range. The system transitions from static high-voltage operation to dynamic voltage regulation, adjusting the voltage reference based on load current to prevent excessive voltage buildup during light-load conditions while ensuring sufficient voltage for power delivery during heavy-load conditions.
Solution Approach 2:
The patent changes the operating parameter of DC bus voltage from a fixed high value to a dynamically adjusted value within an optimal range. By modifying the voltage reference through load-dependent control and actively regulating the rectifier output, the system optimizes the voltage parameter to balance power delivery capability with component stress reduction, thereby improving reliability.
2Power
If high-voltage DC bus system is used to meet power requirements, then power capability is improved, but capacitor lifetime is shortened
Solution Approach 1:
The system dynamically adjusts DC bus voltage based on real-time load conditions, preventing the capacitor from being subjected to excessive voltage stress during light-load or no-load conditions. The active control mechanism ensures voltage remains within an optimal range that extends capacitor lifetime while maintaining sufficient power capability when needed.
Solution Approach 2:
The patent optimizes the DC bus voltage parameter by implementing load-dependent voltage regulation. The voltage reference is adjusted according to load current, and the rectifier is actively controlled to maintain voltage within an optimal range, thereby reducing voltage stress on capacitors and extending their operational lifetime while preserving power delivery capability.
3Reliability
If DC bus voltage is reduced to improve reliability, then hardware stress is reduced, but power delivery capability may be compromised
Solution Approach 1:
The patent implements dynamic voltage adjustment that adapts to load conditions. During light-load conditions, voltage is maintained within an optimal range to reduce hardware stress and improve reliability. During heavy-load conditions, the system ensures sufficient voltage is maintained to preserve power delivery capability. This dynamic adaptation resolves the contradiction by optimizing voltage based on real-time requirements.
Solution Approach 2:
The system optimizes the DC bus voltage parameter through load-dependent control. The voltage reference is dynamically adjusted according to load current magnitude, and the rectifier is actively regulated to maintain voltage within an optimal range. This parameter optimization ensures voltage is low enough to reduce hardware stress during normal operation but sufficient to maintain power delivery capability when required.
4Reliability
If voltage-adjusting control is implemented to maintain optimal DC bus voltage, then hardware stress is reduced and lifetime is extended, but device complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the DC bus voltage is continuously detected and compared against an optimal voltage reference. The rectifier is actively controlled based on this feedback to maintain voltage within the optimal range. This feedback loop automatically adjusts voltage to reduce hardware stress and extend lifetime, achieving reliability improvement through a systematic control approach.
Solution Approach 2:
The system performs self-regulation by automatically detecting load conditions and adjusting its own operating voltage. The control mechanism uses built-in voltage detection and active rectifier control to maintain optimal voltage without requiring external intervention or complex external control systems. This self-service approach extends hardware lifetime through automated voltage optimization.
Data Source
AI summary
The present disclosure provides a voltage-adjusting device applied in a power conversion system including a Vienna rectifier, a direct current (DC) bus, and an inverter. The voltage-adjusting device includes a grid voltage sampling module for sampling a grid voltage, a given bus voltage calculation module, a voltage-adjusting module, a current control module and a pulse width modulation module. The given bus voltage calculation module calculates a given value of the DC bus voltage based on the grid voltage. The current control module receives a three phase AC current from the grid, the active current given signal and the reactive current given signal to output a three phase control voltage. The pulse width modulation module outputs a pulse control signal to the Vienna rectifier.