Power Converter Pre-Charging With a Shared Inrush Current Limiter
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Solution Overview
Problem
Existing power converters require separate inrush current limiters for both the input capacitor and the charger capacitor, leading to an enlarged device size and increased manufacturing costs.
Innovation Solution
A power converter design that incorporates a single inrush current limiter connected in parallel to a switching unit, pre-charging both capacitors using a controller to manage switching states and perform step-down operations with the inverter, eliminating the need for separate limiters on each capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate inrush current limiters are provided for both the input capacitor and the charger capacitor, then inrush current is effectively limited for both capacitors, but the device size is enlarged
Solution Approach 1:
The patent merges the inrush current limitation function into a single shared inrush current limiter that serves both the input capacitor and the charger capacitor. The limiter is connected to detect inrush currents from both capacitors and activates a single switching element to limit current for either capacitor as needed, eliminating the need for separate limiters and reducing device size while maintaining effective inrush current protection for both capacitors
2Reliability
If separate inrush current limiters are provided for both capacitors, then inrush current protection is ensured, but manufacturing costs increase
Solution Approach 1:
The patent combines multiple inrush current limitation functions into a single limiter circuit with shared components including the limiting element and control logic. This consolidation reduces the total number of parts, simplifies assembly, and lowers manufacturing costs while maintaining comprehensive inrush current protection for both the input capacitor and charger capacitor through intelligent switching control
3Volume of stationary object
If a single inrush current limiter is used for both capacitors, then device size is reduced, but the complexity of controlling the limiter increases
Solution Approach 1:
The patent implements preliminary detection and control mechanisms that monitor the charging states of both capacitors before inrush current events occur. The control circuit continuously tracks voltage levels and charging progress, pre-positioning the switching element in optimal states to automatically limit inrush currents when needed, thereby simplifying the actual control operation during inrush events while maintaining reduced device size
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 design reduces the size and manufacturing costs of the power converter by integrating a single inrush current limiter, while effectively pre-charging both capacitors without the need for redundant components.
Implementation Method 1
The inrush current limiter is connected in parallel to the third switching unit and includes a resistance element and a fourth switching unit that is configured to be turned on to connect the battery via the resistance element to the second capacitor
Data Source
AI summary
A power converter includes a charger, a battery, a motor, an inrush current limiter, and processing circuitry. A first switching unit connects the charger to the battery. A second switching unit connects a positive conductor to the neutral point of the motor. A third switching unit connects the battery and the inverter. The inrush current limiter is connected in parallel to the third switching unit and includes a resistance element and a fourth switching unit. The controller pre-charges a second capacitor arranged between the battery and the inverter by turning off the third switching unit and turning on the fourth switching unit. The controller pre-charges a first capacitor arranged between the charger and the battery after pre-charging the second capacitor by performing a step-down operation with the inverter while turning on the second and third switching units and turning off the first and fourth switching units.