Current Sensing

Current sensing closes power control loops, triggers overcurrent protection, and feeds fleet telemetry. WPT systems sense DC bus input, resonant tank current, and output charge current — each with different bandwidth and common-mode requirements.

Wrong sense placement or layout makes control unstable or protection blind.

01Methods

• Shunt resistors with differential amplifiers — simple, accurate at DC and low frequency.
• Rogowski or current transformers for high-frequency tank current without insertion loss.
• Hall sensors for galvanic isolation — watch offset drift and bandwidth.

02Layout rules

Kelvin connection to shunt. Filter noise without killing phase margin in current loop. Separate analog ground return from power switch return except at defined star point.

03Fleet use

• Calibrate offset and gain in production — log serial correlation.
• Use charge current accuracy for billing or SOC estimation disclaimers.
• Detect abnormal tank current patterns indicating misalignment or foreign objects.