Measuring and Separating Conducted Three-Wire Emissions From a Fault-Tolerant, NPC Propulsion Inverter With a Split-Battery Using Hardware Separators Based on HF Transformers

Abstract

Conducted emissions on the traction battery's power cables in EVs must be limited to avoid unwanted EMI. When designing an EMI filter, it is advantageous to have information of the Common Mode (CM) and Differential Mode (DM) noise levels. This paper deals with the measurement and separation of the DC side's three-wire DM/CM noise of a fault-tolerant threelevel NPC inverter with a split-battery system. Two hardware separators, based on small circuit High Frequency transformers, were developed to identify the DC side's CM, line-DM and phase-DM noise levels. Their characterized CM and DM rejection ratios for the frequency range from 150 kHz to 110 MHz are at least -33 dB and -21 dB, respectively. The separated noise of the NPC inverter was measured, using an inductive load, when operating the inverter with three-level and two-level modulation, resembling normal operation and a possible operation under fault, respectively. A simple three-wire CM model of the used testbed and the DM power module oscillation were derived to validate the separated noise's resonance peaks/valleys. It has been seen that the CM noise is dominant, especially below 10 MHz, except for the power module oscillations. Furthermore, when using the two-level modulation, in case of a clamping diode fault, the noise levels are increased by about 3 dB.

Review of Technical Design and Safety Requirements for Vehicle Chargers and Their Infrastructure According to National Swedish and Harmonized European Standards

“…According to the SS-EN 55025 [61], the test-bench used for the measurements shall be in compliance with the CISPR series 16 [63],"Specification for radio disturbance and immunity measuring apparatus and methods". For example, as shown in [64], the surface of the test-bench shall be covered by a copper sheet (ground plate), spacers shall be used to have a separation of 5 cm to the ground plate and, further, a certain distance must be kept between the LISNs and the power electronics circuitry. The measurement of conducted emissions according to the SS-EN 55025 [61] is a typical pre-compliance test used for individual components, such as the power electronics converter of a charging station.…”

Battery Modeling and Parameter Extraction for Drive Cycle Loss Evaluation of a Modular Battery System for Vehicles Based on a Cascaded H-Bridge Multilevel Inverter

“…for Vehicles Based on a Cascaded H-Bridge Multilevel Inverter multilevel inverters (MLI) are gaining interest in the field of vehicle propulsion applications [5]- [7], such as the neutral point clamped (NPC) and the cascaded H-bridge (CHB) inverter, referred to as modular battery systems [8]. These inverter topologies have several advantages compared to the classical two-level inverter, for example, possible fault tolerant operation [9]- [11], efficiency enhancement [11]- [14], and especially, low output voltage harmonic and electromagnetic emissions [15], [16]. In [6], [11], and [14], the CHB topology utilizing low voltage MOSFETs is considered.…”

Hybrid Output Voltage Modulation (PWM-FSHE) for a Modular Battery System Based on a Cascaded H-Bridge Inverter for Electric Vehicles Reducing Drivetrain Losses and Current Ripple

“…For each small battery pack, passive balancing should be applied. Additionally, using a multilevel converter topology reduces the conducted emissions [13,15] and allows for a limp home mode [16,17]. A major drawback of MLI topologies is that these increase the ohmic battery losses, since the battery packs are stressed with strong current pulses ranging from DC up to a couple of kHz.…”