Multi-Bus Power Converter Duty Control for Bus Voltage Balancing
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Solution Overview
Problem
Existing bus voltage balancing strategies for three-bus and multi-bus topologies in power converters, such as single-phase modular combined three-phase rectifiers, are inadequate, leading to voltage imbalances that can damage devices and degrade performance.
Innovation Solution
A software-based bus voltage balance regulation method that calculates the difference between the bus voltage of the main phase and the average voltage of all phases, determining a regulation direction for each phase to achieve balance, using a voltage balancing loop that adjusts the duty ratio of power switches without additional hardware, employing PI or PID controllers for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage balancing regulation is performed based on average voltage of all capacitors, then voltage balance can be maintained, but capacitor with highest voltage cannot be identified and regulated effectively
Solution Approach 1:
The patent divides the capacitor group into multiple series-connected units and identifies the specific capacitor with highest voltage through individual voltage detection. This segmentation approach allows precise identification of the target capacitor for regulation, rather than treating all capacitors uniformly.
Solution Approach 2:
The patent implements feedback control by continuously monitoring individual capacitor voltages, comparing them to reference values, and adjusting the switching states of power devices based on the voltage difference. This closed-loop feedback ensures reliable voltage balancing by regulating the highest-voltage capacitor.
2Speed
If switching frequency of power conversion device is increased, then voltage regulation response speed improves, but system loss increases
Solution Approach 1:
The patent dynamically adjusts the switching frequency based on voltage deviation magnitude. When voltage deviation is large, higher switching frequency provides faster response; when deviation is small, lower frequency reduces losses. This dynamic adjustment optimizes the trade-off between response speed and energy loss.
Solution Approach 2:
The patent changes the switching frequency parameter adaptively according to the voltage balancing needs. By modulating the switching frequency rather than maintaining a fixed high frequency, the system achieves effective voltage regulation while minimizing unnecessary energy losses during light-load or balanced conditions.
3Device complexity
If voltage balancing regulation is performed without considering individual capacitor voltages, then control complexity is reduced, but voltage balance cannot be achieved under light load conditions
Solution Approach 1:
The patent performs preliminary detection of individual capacitor voltages before executing regulation control. This preliminary action identifies which capacitor needs regulation and determines the appropriate switching strategy in advance, enabling effective light-load balancing without excessive complexity during actual control execution.
Solution Approach 2:
The patent applies different control strategies to different capacitors based on their individual voltage states. By focusing regulation effort on the specific capacitor with highest voltage rather than uniformly controlling all capacitors, the system achieves effective voltage balancing with reduced control complexity through localized, targeted regulation.
Data Source
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AI summary
A method for balancing regulation of a bus voltage for a power converter, and a power converter, a storage medium and an electronic apparatus are disclosed. The method may include: taking a difference between a bus voltage of a positive maximum phase and a negative maximum phase among phase voltages of the power converter as an error input of a voltage balancing loop to calculate a voltage balance regulation duty ratio of each phase (SI02); determining a regulation direction of a driving duty ratio of each phase according to a difference between a bus voltage of a main phase and an average value of bus voltages of all phases (S104); and conducting balance regulation on the bus voltage of each phase according to the regulation direction of the driving duty ratio of each phase and the voltage balance regulation duty ratio of each phase (S106).