Converter Current Measurement Circuit Design
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Solution Overview
Problem
Existing electrical power converter systems face challenges in efficient current measurement, particularly for small voltages and power levels, due to high space and cost requirements, discontinuous current measurement, and inaccuracies in current detection, especially with high switching frequencies and sinusoidal current modulation.
Innovation Solution
A converter design that uses a single current measurement element to guide entire AC currents through a current measurement circuit, allowing quasi-continuous current measurement and reducing bandwidth filtering needs, enabling accurate peak current control and independent modulation schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple shunts and current sensors are used for current measurement, then measurement accuracy is improved, but space requirements and costs increase significantly
Solution Approach 1:
The patent merges multiple current measurement functions into a single shunt by routing currents from multiple bridge legs through one common measurement element. This consolidation reduces the number of shunts and current sensors needed, thereby reducing space requirements and costs while maintaining measurement capability across all phases.
Solution Approach 2:
The single shunt is designed to serve multiple measurement purposes simultaneously, measuring currents from different bridge legs by selectively routing them through the same measurement element. This multi-functional approach eliminates the need for dedicated shunts for each phase while preserving measurement accuracy.
2Area of stationary object
If a single shunt is arranged in the DC link, then space and cost are reduced, but current measurement becomes discontinuous during freewheeling intervals
Solution Approach 1:
The patent implements dynamic current routing where the measurement circuit can selectively connect to different bridge legs based on the switching state. During freewheeling intervals, the system dynamically routes the freewheeling current through the shunt by controlling the switching elements, ensuring continuous measurement capability despite changing operating conditions.
Solution Approach 2:
The patent introduces switching elements and control circuitry as intermediaries between the bridge legs and the single shunt. These intermediaries actively route currents from different bridge legs through the shunt at appropriate times, including during freewheeling intervals, thereby maintaining continuous measurement while using only one shunt.
3Productivity
If high switching frequency is used for small voltage converters, then productivity is improved, but high frequency disturbances make measurement difficult
Solution Approach 1:
The patent implements a control system that uses the shunt measurement feedback to adjust switching timing and duration. By measuring actual current through the shunt and comparing it with reference values, the system can optimize switching parameters to minimize high-frequency disturbances while maintaining high switching frequency operation for improved productivity.
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 approach reduces space and cost requirements, provides accurate quasi-continuous current measurement, and allows for efficient peak current control, even at high switching frequencies, improving overall converter performance.
Implementation Method 1
a current measurement circuit (3) configured to guide none, one, or more (in particular two) of the AC currents flowing through at least one of the at least three AC terminals through the current measurement element (9)
Data Source
Figure 1~4
Figure 5~6
Figure 7~10
AI summary
A converter (1) comprises a negative DC terminal (7) and a positive DC terminal (8); at least three AC terminals (11, 12, 13), each AC terminal being arranged for an associated AC current (iv, iu, iw) to flow through the terminal; a converter bridge (2) with at least three bridge legs (u, v, w), each bridge leg being associated with one of the at least three AC terminals (11, 12, 13) and being able to connect the associated AC terminal (11, 12, 13) to the negative DC terminal (7) or the positive DC terminal (8); a current measurement circuit (3) comprising a current measurement element (9), the current measurement circuit (3) being configured to guide either none or one or more of the AC currents (iv, iu, iw) flowing through one of the at least three AC terminals (11, 12, 13) through the current measurement element (9).