Miniaturized High-Density Hall-Effect Low Voltage Current Transformer (LVCT) Solution
I. Technical Challenges & Objectives
Traditional current transformers (CTs) suffer from large size, AC-only measurement limitations, and magnetic saturation risks. Addressing the needs of modern compact electronic systems (e.g., battery management, servo drives, compact inverters) for space savings, lightweight design, DC detection, and high-frequency response, this solution offers a miniaturized, high-density, AC/DC-compatible Hall-effect current sensing approach.
II. Core Technology: Closed-Loop Flux-Balance Hall Sensor + ASIC Integration
- Miniature Magnetic Circuit & Sensing Core
- Closed-Loop Flux-Balance Architecture: Micro silicon-based Hall chip embedded within a specially designed annular flux-concentrating core (high-permeability material).
- Magnetic Field Cancellation Principle:
- Primary current-generated magnetic field detected by the Hall chip.
- High-gain feedback circuit drives secondary coil to generate counteracting field, achieving real-time "zero-flux" state.
- Feedback current precisely mirrors primary current, eliminating nonlinearity and temperature drift inherent to open-loop designs.
- Highly Integrated Signal Processing
- Dedicated ASIC Integration:
- Low-noise amplification of Hall signals
- Dynamic offset cancellation circuitry
- High-precision temperature compensation algorithm (mitigating silicon thermal drift)
- Adjustable low-pass filtering (typical: 100–250 kHz)
- Integrated voltage reference and output driver
- Ultra-Compact Structural Design
- Miniaturized Core: Optimized magnetic circuit with apertures as small as Ø5mm (standard through-hole) or rectangular surface-mount openings.
- SMD/Through-Hole Packaging:
- Surface-mount packages (e.g., SMD-8) for direct PCB assembly, height ≤ 10mm.
- Through-hole design (leadless structure) allows direct conductor routing through core aperture, enabling galvanically isolated installation.
III. Key Advantages & Value Proposition
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Dimension |
Advantage |
Value Proposition |
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Physical |
- >70% size reduction |
High-density PCB compatibility |
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- Ultralight weight (<5g) |
Ideal for drones/handheld devices |
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- SMD/through-hole structures |
Simplified installation |
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Electrical |
- AC/DC current measurement (DC–100kHz) |
EV powertrain monitoring |
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- Galvanic isolation (>2.5kV) |
Solar inverter OCP/PV leakage detection |
|
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- Virtually immune to saturation |
High-accuracy battery SOC estimation |
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- Low thermal drift (<0.05%/°C) |
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System Cost |
- Microamp-level quiescent current |
Extended battery life in portable devices |
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- Zero external compensation components |
Reduced BOM & calibration costs |
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- Full SMT automation compatibility |
Scalable for million-unit production |
IV. Target Applications
- Battery Management (BMS): High-precision DC current detection (±1%) for EV/ESS charge-discharge cycles.
- Compact Inverters: Phase current control in IGBT modules (100A-range SMD solutions).
- Servo Drives: Multi-axis motor current sampling (parallel SMD CT arrays).
- Smart Meters: DC-component metering (tamper/theft prevention).
- Data Center PSUs: Rack-level current monitoring (high-density through-hole integration).
V. Scalability & Future Roadmap
- Multi-Range Coverage: Single package supports 20A–500A ranges (via core/coil ratio optimization).
- Digital Interface: Optional I²C/SPI output variants (ADC-integrated ASIC).
- High-Precision Tier: Closed-loop achieves 0.5% linearity (25°C), meeting Class 1 metering standards.
