DC-DC Chopper Control for Unequal Load Voltage Balance
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Solution Overview
Problem
Existing DC-DC power supply systems with chopper series topology struggle to maintain balanced operation when loads with different rated voltage parameters are connected, leading to reduced output power or hydrogen production rates.
Innovation Solution
A control method for DC-DC power supply apparatuses that performs closed-loop control on a target chopper unit's capacitor to adjust its voltage to a reference value, obtaining an output current difference reference value, and then controls the output current of each chopper unit based on this value, allowing for flexible application scenarios without requiring consistent load parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bus series capacitor half-voltage control method is adopted, then voltage rating of switching tubes is reduced and low-voltage switching tubes can be applied in high-voltage systems, but all parameters of two sets of loads must remain consistent and output power is reduced when loads have different rated voltage parameters
Solution Approach 1:
The patent changes the control parameters from fixed half-voltage control to dynamic capacitor voltage control. By adjusting the voltage of the first bus series capacitor away from half of the total input voltage based on the output voltage proportion of each chopper unit, the system can adapt to different load parameters while maintaining maximum output power. This parameter change enables the system to handle loads with different rated voltage parameters effectively.
Solution Approach 2:
The patent implements a feedback control mechanism where the actual output voltage of each chopper unit is monitored and used to adjust the voltage of the first bus series capacitor. The controller dynamically adjusts the capacitor voltage based on the proportion of output voltage from each chopper unit, creating a closed-loop control system that maintains optimal performance across varying load conditions and prevents capacitor voltage from going out of control.
2Reliability
If bus series capacitor half-voltage control method is adopted, then system efficiency is enhanced, but voltage of bus series capacitors goes out of control during operation when loads have different parameters
Solution Approach 1:
The patent implements a feedback control mechanism where the actual output voltage of each chopper unit is monitored and used to adjust the voltage of the first bus series capacitor. The controller dynamically adjusts the capacitor voltage based on the proportion of output voltage from each chopper unit, creating a closed-loop control system that maintains optimal performance across varying load conditions and prevents capacitor voltage from going out of control.
Solution Approach 2:
The patent transitions from static half-voltage control to dynamic capacitor voltage control. The voltage of the first bus series capacitor is no longer fixed at half of the total input voltage but is dynamically adjusted according to the output voltage proportion of each chopper unit. This dynamic control approach allows the system to adapt to changing load conditions while maintaining stability.
3Manufacturing precision
If two sets of chopper circuits are controlled with 1/2 bus voltage as target value, then bus voltage neutral-point balance is realized, but it is difficult to simultaneously maintain both loads operating at maximum rated current when loads have different rated voltage parameters
Solution Approach 1:
The patent changes the voltage reference from fixed half-bus voltage to a dynamic reference based on output voltage proportion. By allowing the first bus series capacitor voltage to deviate from half of the total input voltage and instead control it based on the actual output voltage proportion of each chopper unit, the system can maintain both loads at their maximum rated current while still achieving effective voltage balance.
Solution Approach 2:
The patent applies different control strategies to different parts of the system. Each chopper unit is controlled based on its specific output voltage proportion rather than using a uniform half-voltage control. This localized control approach allows each chopper unit to operate optimally according to its load requirements while maintaining overall system balance.
Data Source
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AI summary
Disclosed in the present invention are a control method and system for a DC-DC power supply apparatus, and a power supply apparatus. The control method comprises: after a controlled power supply is connected to an external input voltage, starting control; using one of chopping units as a target chopping unit, and using an input capacitor in the target chopping unit as a target capacitor, performing closed-loop control on the voltage of the target capacitor according to an acquired output voltage proportion state, so as to adjust the voltage of the target capacitor to a target reference value, and then obtaining an output current difference reference value according to a closed-loop control result of the voltage of the target capacitor; and performing closed-loop control on output currents of the chopping units according to the output current difference reference value and preset output current reference values of the chopping units. The present invention has flexible application scenarios, and it is not necessary to restrict the consistency requirement for parameters of loads connected to an output end, thereby expanding the application range of DC-DC power supply apparatuses and also ensuring a relatively high output capability of the DC-DC power supply apparatuses.