Precharging Unit for Voltage Converter Current Control
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Solution Overview
Problem
Existing precharging devices for chopping converters are bulky and inefficient, as they require separate current-limiting units and power-dissipating means, leading to energy losses and potential overcurrent issues during capacitor charging.
Innovation Solution
A compact precharging device with a switching unit, such as an insulated-gate transistor, that operates in both a precharging state to limit current and a closed state to minimize energy losses, eliminating the need for separate current-limiting units and allowing for controlled charging and disconnection from the DC voltage supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate current-limiting unit (power resistor) is used during precharging, then the precharging current is limited to safe values, but the device becomes bulky and energy losses increase
Solution Approach 1:
The patent merges the current-limiting function and the switching function into a single precharging unit. The precharging unit has two states: a precharging state with limited current capability and a closed state with minimal resistance. This eliminates the need for separate current-limiting resistors and switching devices, reducing device complexity while maintaining reliable current control during precharging.
Solution Approach 2:
The precharging unit serves multiple functions: it limits current during precharging, acts as a switch to connect/disconnect the converter, and provides protection against overvoltage and overcurrent. This multi-functional design reduces the number of components needed and simplifies the overall device structure.
2Reliability
If a power resistor is used for current limiting, then overcurrent is prevented, but energy losses increase due to power dissipation
Solution Approach 1:
The precharging unit dynamically changes its resistance characteristic based on its state. In the precharging state, it exhibits limited current capability with higher effective resistance to protect against overcurrent. In the closed state, it transitions to minimal resistance to minimize power dissipation and energy losses during normal operation. This dynamic behavior eliminates the continuous power loss associated with fixed resistive current limiters.
3Reliability
If the precharging unit can disconnect from supply, then protection against overvoltage and defects is improved, but control complexity increases
Solution Approach 1:
The precharging unit serves as both a current limiter and a disconnect switch. By integrating the switching function into the precharging unit itself, the patent avoids adding separate switching devices and control circuits. The unit can be commanded to disconnect from the DC voltage supply to protect against overvoltage and converter defects, maintaining reliability while minimizing control complexity.
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
The device provides efficient, controlled precharging with reduced energy losses and enhanced safety by disconnecting from the supply when not in use, preventing overvoltage and protecting the converter and supply.
Implementation Method 1
Transistors are particularly suitable for dissipating the powers admissible for such converters
Data Source
AI summary
A device for precharging a voltage converter is provided with a precharging unit, capable of assuming a closed state, as well as with a control unit for the precharging unit, the precharging unit being capable of operating according to a precharging state limiting the value of the precharging current passing through it, the control unit being capable of commanding the operation of the precharging unit according to the precharging state and, once the precharging has been completed, of commanding the precharging unit to change over from the precharging state to the closed state. The assembly has a chopping voltage converter and such a device disposed at the input of the converter. The aircraft is equipped with such a device or with such an assembly.