IEC PAS 63015: EMC Guidelines for Electric Vehicle Wireless Power Transfer

1. Scope of IEC PAS 63015

IEC PAS 63015 provides Electromagnetic Compatibility (EMC) guidelines for wireless power transfer (WPT) systems used for charging electric vehicles (EVs). It addresses the unique EMC challenges posed by inductive charging systems operating in the frequency range of 79–90 kHz (the band allocated for EV wireless charging under IEC 61980). Unlike conductive charging, where the galvanic connection inherently limits radiated emissions, WPT systems use strongly coupled magnetic resonators that can generate significant magnetic stray fields both inside and outside the vehicle.

The document covers both the ground-side (charging pad) and vehicle-side (receiver pad) assemblies, including their power electronics converters (DC–AC inverter on the ground side, AC–DC rectifier on the vehicle side). It applies to light-duty road vehicles (passenger cars, SUVs, light trucks) and provides emission limits, immunity requirements, and test methodologies specific to WPT systems operating in the 3–150 kHz range. The standard coordinates with CISPR 11 (industrial, scientific, and medical equipment) and CISPR 25 (vehicles, boats, and internal combustion engines) to ensure compatibility with both the grid-side environment and in-vehicle electronic systems.

2. Key EMC Requirements and Test Methods

2.1 Radiated Magnetic Field Limits

The central concern for WPT EMC is the magnetic stray field at the fundamental operating frequency (typically 85 kHz) and its harmonics. IEC PAS 63015 defines two zones: Zone 1 (inside the vehicle cabin) and Zone 2 (outside the vehicle, at a distance of 10 m). The limits are derived from the ICNIRP 2010 guidelines for general public exposure, with additional margin for multiple-vehicle scenarios in parking garages. Table 1 summarizes the limits.

2.2 Conducted Emissions on the Supply Mains

The ground-side inverter generates conducted common-mode and differential-mode noise that propagates back into the AC mains. IEC PAS 63015 applies the CISPR 11 Class B limits for residential environments at the AC input terminals of the WPT system. Special attention is given to the rectifier stage: active power factor correction (PFC) front ends must be designed such that the conducted emissions in the 150 kHz–30 MHz range do not exceed the quasi-peak limits of 66 dB(μV) decreasing to 56 dB(μV) at higher frequencies. The standard also addresses interharmonic emissions caused by the beat frequency between the mains (50/60 Hz) and the WPT switching frequency.

3. Engineering Design Insights for WPT EMC

3.1 Coil Geometry and Shielding Topology

From an engineering perspective, the magnetic stray field is primarily determined by the coil geometry (circular, rectangular, or double-D) and the shielding structure. The standard implicitly favors double-D (DD) coil topologies because their inherently directional magnetic flux pattern reduces stray fields by 40–60 % compared to simple circular coils at the same power level. Ferrite backing plates (typically Mn–Zn ferrite, initial permeability μ_r = 2300–3300) are used to confine the magnetic flux to the coil-coil path, while a conductive aluminum backplane serves as an additional eddy-current shield.

For the vehicle-side receiver, the shielding challenge is compounded by the presence of the steel chassis, which can distort the field pattern and create localized hot spots. Multi-layer shielding — a ferrite layer closest to the coil, followed by a 1–2 mm aluminum layer — is the recommended practice. The aluminum layer provides 15–25 dB of additional attenuation at 85 kHz through eddy-current cancellation, while the ferrite layer maintains coupling efficiency.

3.2 Active EMI Cancellation and Dead-Time Optimization

Conducted emissions are strongly influenced by the inverter’s switching characteristics. Soft-switching techniques (zero-voltage switching, ZVS) are widely adopted in WPT inverters to reduce di/dt and dv/dt at the switching edges, thereby lowering the high-frequency content of the output voltage waveform. IEC PAS 63015 provides guidance on dead-time optimization (typically 100–300 ns for SiC MOSFETs operating at 85 kHz) to balance efficiency (minimizing shoot-through losses) and EMC performance (minimizing switching harmonics). Active common-mode cancellation using a small auxiliary transformer winding or a balancing capacitor network can further reduce conducted emissions by 10–15 dB without significant cost or efficiency penalties.

4. Frequently Asked Questions