Multi-Phase DC/DC Converter Current Detection via Wiring Voltage Drop
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Solution Overview
Problem
Conventional DC/DC converters face challenges in current detection accuracy and efficiency due to manufacturing variations and temperature dependence in current sense resistors, leading to increased component count, cost, and reduced transient characteristics.
Innovation Solution
A multi-phase DC/DC converter design that eliminates current sense resistors by detecting coil current through voltage drops in branch portions of the output power supply wiring, which are positioned farther from heating elements, reducing temperature dependence and simplifying the detection circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sense resistors are used for current detection, then current detection accuracy is improved, but component count and cost increase
Solution Approach 1:
The invention extracts the current sensing function from dedicated current sense resistors and relocates it to the output power supply wiring. By utilizing the inherent resistance of the wiring itself, the patent eliminates the need for separate current sense resistor components while maintaining current detection capability through voltage drop measurement across the wiring.
Solution Approach 2:
The output power supply wiring is given a dual function: it serves both as the power delivery path and as the current sensing element. The wiring's resistance is utilized for both its primary purpose (power transmission) and an additional sensing function, thereby reducing component count while maintaining detection accuracy.
2Measurement precision
If current sense resistors are used for current detection, then current detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The invention removes the need for expensive current sense resistor components by extracting the sensing function to the existing output power supply wiring. This eliminates additional component costs and reduces manufacturing complexity while maintaining detection accuracy through the wiring's inherent resistance.
Solution Approach 2:
The patent utilizes the output power supply wiring, which is already present and inexpensive, as the current sensing element. This replaces expensive dedicated current sense resistors with a low-cost solution that leverages existing infrastructure.
3Measurement precision
If current sense resistors are used for current detection, then current detection accuracy is improved, but transient characteristics deteriorate
Solution Approach 1:
By extracting the sensing function from separate current sense resistors to the output power supply wiring, the invention reduces the number of components in the current detection path. This minimizes parasitic inductance and resistance, thereby improving transient response characteristics while maintaining detection accuracy.
4Device complexity
If inductor DC resistance is used for current detection, then component count is reduced, but current detection accuracy deteriorates due to manufacturing variations
Solution Approach 1:
The patent applies local quality by creating separate branch portions in the output power supply wiring, each with controlled and matched resistance characteristics. Instead of relying on the inductor's DC resistance which varies with manufacturing tolerances, the wiring branches are designed with consistent resistance values to ensure accurate current detection.
5Device complexity
If inductor DC resistance is used for current detection, then component count is reduced, but temperature dependence increases
Solution Approach 1:
The invention creates dedicated branch portions in the output power supply wiring with controlled resistance characteristics that are less sensitive to temperature variations. By positioning these sensing portions away from high-temperature areas and designing them with stable resistance properties, the patent reduces temperature dependence compared to using inductor DC resistance.
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 enables accurate and efficient current detection with reduced component count and cost, improved transient characteristics, and simplified signal processing, while minimizing temperature effects.
Implementation Method 1
a coil current flowing through the inductor of each phase is detected based on a voltage drop of a branch portion corresponding to the phase of the output power supply wiring
Data Source
AI summary
There is provided a DC/DC converter that can eliminate the necessity of current sense resistors to thereby reduce the mounting area, improve the efficiency, and realize favorable transient characteristics. A multi-phase DC/DC converter with N phases (N is an integer equal to or greater than 2) is provided. A high-side transistor MH, a low-side transistor ML, and an inductor L are provided for each phase φ. Output power supply wiring connects a load side end of each of N inductors L1 to LN and a load. The output power supply wiring is branched from the load toward the load side ends of the N inductors L1 to LN. A coil current flowing through an inductor Li of an ith phase φi (i=1, 2, . . . N) is detected based on a voltage drop Vsi of a branch portion bri corresponding to the phase φi of the output power supply wiring.