Convertor Initial Charging Control via Dynamic Voltage Reference
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Solution Overview
Problem
Existing convertor apparatuses face inefficiencies in initial charging time optimization of DC link capacitors due to varying power supply impedance, leading to excessive in-rush currents and prolonged charging times when the impedance is high, as the voltage reference value is set assuming zero impedance.
Innovation Solution
A convertor apparatus with an alternating current voltage detection unit, DC link capacitor voltage detection unit, initial charging unit, current detection unit, and voltage reference value setting unit, which dynamically adjusts the voltage reference value based on detected current values to optimize the initial charging time, ensuring it is not excessively long or destructive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the voltage reference value is set assuming zero impedance to enable fast charging, then the initial charging time is reduced, but excessive in-rush currents occur when power supply impedance is high
Solution Approach 1:
The voltage reference value is changed from a fixed value (assuming zero impedance) to a dynamic value that varies based on detected power supply impedance. The control unit adjusts the voltage reference value according to the detected impedance level, enabling the system to adapt to different power supply conditions and avoid excessive in-rush currents while maintaining efficient charging.
Solution Approach 2:
The patent changes the parameter of voltage reference value from a constant to a variable parameter that depends on power supply impedance. By detecting the impedance and相应地 adjusting the voltage reference value, the system optimizes the charging process to prevent harmful in-rush currents while minimizing charging time.
2Reliability
If the voltage reference value is increased to reduce in-rush current, then the safety is improved, but the initial charging time becomes excessively long
Solution Approach 1:
The voltage reference value dynamically adapts to the actual power supply impedance conditions. When impedance is high, the reference value is appropriately increased to limit in-rush current while maintaining reasonable charging time. When impedance is low, the reference value can be lower to enable faster charging, thus balancing safety and efficiency.
Solution Approach 2:
The control unit detects the power supply impedance and uses this feedback information to adjust the voltage reference value. This closed-loop control ensures that the charging process maintains optimal parameters based on actual conditions, preventing both excessive in-rush currents and unnecessarily long charging times.
3Device complexity
If a fixed voltage reference value is used for all impedance conditions, then the device complexity is reduced, but the adaptability to different power supply conditions deteriorates
Solution Approach 1:
The control unit automatically detects the power supply impedance and self-adjusts the voltage reference value without requiring external intervention or complex manual configuration. This self-service approach maintains relatively simple device architecture while achieving high adaptability to different power supply conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution optimizes the initial charging time of the DC link capacitor by adjusting the voltage reference value according to current conditions, reducing in-rush currents and ensuring efficient charging regardless of power supply impedance, thereby enhancing the operational efficiency and safety of the convertor apparatus.
Implementation Method 1
a DC link capacitor provided to the DC link; the DC link capacitor having a function of restraining a ripple portion of a direct current output of the convertor apparatus and a function of storing a direct current power
Implementation Method 2
an initial charging unit including a switch and a charging resistor connected in parallel to the switch
Data Source
AI summary
A convertor apparatus includes: a main circuit unit which converts an alternating current to a direct current and outputs the same to a DC link; a DC link capacitor; an alternating current voltage detection unit which detects an alternating current voltage crest value of the main circuit unit; a DC link capacitor voltage detection unit which detects a DC link capacitor voltage value; an initial charging unit which includes a switch for opening and closing an electrical path between the main circuit unit and the DC link capacitor and a charging resistor; a current detection unit which detects a current value flowing into the main circuit unit or flowing out of the main circuit unit; and a voltage reference value setting unit which sets the voltage reference value in accordance with the current value when the switch is adapted from to be opened into to be closed.