THE CHALLENGE
Design a high-efficiency three-phase AC front-end for a 150kW DC fast charger meeting IEC 61000 harmonic requirements and CE marking.
THE SOLUTION
Three-Phase Vienna Rectifier topology with DSP-based control. Active power factor correction, THD < 5%, full compliance with IEC 61000-3-12.
RESULTS & OUTCOMES
> 97% power factor achieved
THD < 3.8% at full load
CE marking successfully obtained
IEC 61000-3-12 Class A compliance
The Vienna Rectifier is a three-level boost topology well suited to high-power AC–DC conversion where low harmonic distortion and high power factor are mandatory. This engagement delivered a 150kW front-end for a European OEM's fast-charging platform.
Topology Selection
The Vienna Rectifier was chosen over a conventional two-level boost PFC for its reduced switch voltage stress (half the DC bus voltage per device), lower switching losses at 150kW power levels, and inherently lower THD due to three-level PWM switching.
DSP-Based Control
A Texas Instruments C2000 DSP implements the current control loop with a sampling rate of 40kHz. Symmetrical space-vector PWM with per-phase duty cycle injection achieves unity displacement power factor while keeping THD below 3.8% at full load — comfortably within IEC 61000-3-12 Class A limits.
EMC and Certification
The EMC filter was designed and tuned in simulation before PCB layout, with differential-mode and common-mode stages sized for both conducted and radiated limits. CE marking was completed through an accredited European test laboratory, covering the Low Voltage Directive and EMC Directive requirements.
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