Author:
Clayton Pillion, Vice President SiC business unit, and Joe Thomsen, Vice President Digital Signal Controller Business Unit, Microchip
Date
01/20/2025
PDF
Click image to enlarge
Figure 1: Totem-pole PFC demonstration application
An essential component for electric vehicles (EVs) is the On-Board Charger (OBC), which transforms alternating current (AC) into direct current (DC) to replenish the vehicle's high-voltage battery. The efficacy and dependability of OBCs significantly influence the entire performance and user experience of EVs, rendering them a critical focal point for EV makers.
At PCIM 2024 in Nuremberg, Germany, Microchip Technology unveiled an On-Board Charger (OBC) solution that incorporates a range of its automotive-qualified digital, analog, connectivity, and power devices in an industry-standard D2PAK-7L XL package. The company also released a white paper that offers additional details regarding the optimization of a design's performance and the acceleration of its time to market through the implementation of the OBC solution.
Through advanced control, high-voltage isolation, noise immunity, reduced switching losses, and enhanced thermal management, the new solution was designed to improve the efficiency and reliability of OBCs. Along with the hardware, the company provides software modules for power-factor correction (PFC), DC-DC conversion, communication, and diagnostics, which expedites system development and enables customization to satisfy OEM requirements. Figure 1 shows the totem-pole PFC demonstration application controlled by Microchip’s dsPIC33C.
The new solution aims to enhance the efficiency and reliability of an OBC system by utilizing the advanced control functions of the dsPIC33 DSC and the reduced switching losses and improved thermal management capabilities of the mSiC MOSFETs.
According to research undertaken by Microchip, the company anticipates a consistent expansion of the EV market in the next two to three years, despite the recent plateau in regions like the U.S. This trend underscores the necessity of enhancing charging infrastructure and mitigating range anxiety by using expedited charging cycles.
Higher power density redefines the end-user experience by enhancing the speed and convenience of charging. It is noticeable that EV charging infrastructure in China has up to ten times more EV chargers than the U.S. The voltages that the charging stations provide have also increased. And according to Ohm’s law, every time the voltage is doubled, the current is halved, making it a lot easier to transfer that energy into the vehicle.
Another interesting trend related to charging infrastructure is what some startups and universities research are doing - attaching the charging station directly to the high-voltage power lines from the power company. These high voltages require a solid-state transformer in the charger. This solution saves cost, weight, and efficiency, and ultimately it saves electricity.
Smart energy management and connectivity support vehicle-to-grid (V2G), vehicle-to-home (V2H), vehicle-to-load (V2L), and vehicle-to-vehicle (V2V) functionalities, enabling bi-directional power management of on-board chargers.
The emphasis on compact design and high integration in OBCs is essential for the efficacy and flexibility of EV charging systems. To effectively convert high-voltage power (400V or 800V) to low voltage (12V or 48V) and accommodate various AC inputs (single-phase or three-phase), the integration of low-voltage DC-DC converters is essential.
The future of EV charging infrastructure and the promotion of sustainable transportation practices on a global scale will be significantly influenced by the adoption of high-power, bi-directional, and integrated on-board chargers as EVs continue to acquire momentum in the automotive industry.
To ensure optimal performance and endurance in EVs, OBCs must provide high efficiency, compact physical dimensions, and high reliability ratings. Thermal management is essential for the correct operation and longevity of OBC systems, particularly at higher power levels.
Additionally, OBC systems must adhere to pertinent safety standards and regulations, including IEC 61851 and SAE J1772. To ensure seamless integration with the vehicle's onboard network and external charging infrastructure, OBC systems should support communication interfaces.
Microchip's new OBC solution facilitates the smooth integration of essential components, including the following:
· dsPIC33C Digital Signal Controller (DSC) – This DSC is AEC-Q100 qualified and is designed for power conversion applications. It includes a high-performance DSP core, high-resolution Pulse-Width Modulation (PWM) modules, and high-speed Analog-to-Digital Converters (ADCs). It is safety-ready, functional, and supports the AUTOSAR ecosystem
· mSiC MOSFET – The AEC-Q101-qualified D2PAK-7L XL surface mount package features five parallel source sense leads, which minimize switching losses, enhance current capacity, and reduce inductance. This apparatus accommodates battery voltages of 400V and 800V
Microchip’s dsPIC33 line of DSCs is equipped with a 100 MIPS dsPIC DSC core, which includes an integrated Digital Signal Processor (DSP) and advanced peripherals. The dsPIC33 series provides significant advantages in OBC applications. The high-performance core and high-speed peripherals collaborate effectively to satisfy the stringent demands of controllers in OBC applications.
The dsPIC33 product line possesses numerous capabilities that facilitate the simplification of functional safety certification for ASIL-B/C automotive safety-critical applications. The dsPIC33 device family encompasses ISO 26262 functional safety packages, FMEDA reports, safety manuals, and diagnostic libraries.
The dsPIC33CH series has a dual-core architecture, with one core assigned to high-performance signal processing and control duties, such as Power Factor Correction (PFC), while the second core oversees control and communication activities. This division of duties enhances system efficiency, enabling the dsPIC to manage intricate control algorithms and communication protocols concurrently without sacrificing speed.
Moreover, being equipped with sophisticated digital signal processing capabilities, the dsPIC can effectively execute intricate algorithms for power conversion, control, and modulation. High-speed signal processing facilitates accurate control of voltage and current waveforms, enhancing power quality and efficiency during the charging process.
SiC solutions in OBC systems provide multiple advantages compared to conventional silicon-based architectures. The recently launched surface mount SiC MOSFET alternatives are optimal for 400V and 800V electric vehicle applications, particularly in space-constrained scenarios like an OBC. The Microchip mSiC MOSFET in a D2PAK-7L XL surface mount package is AEC-Q101 approved, with five parallel source sense leads to minimize switching losses, enhance current capacity, and reduce inductance.
Figure 2 shows the DC-DC demonstration application. Besides the dsPIC33C board, there are four mSiC power MOSFETs, two on the primary side, and two on the secondary side, separated by the isolation transformer.
Click image to enlarge
Figure 2: DC-DC converter demonstration application
Microchip's configurable mSiC gate drivers enhance system power density and minimize switching losses. These digital gate drivers are entirely software configurable and prevent false faults, as well as mitigate ringing, EMI, overshoot, and undershoot in SiC and IGBT power modules integrating the patented Augmented Switching technology and robust short-circuit protection.
Microchip has implemented a digital strategy to regulate SiC devices while simultaneously guaranteeing the highest levels of reliability and efficiency. Analog control is unreliable for SiC devices and frequently experiences varying degrees of ringing, overshoots, and undershoots, despite the fact that standard analog solutions are excellent alternatives for Silicon devices.
Augmented Switching technology for digital programmable gate drivers offers accurate configurations for activating and deactivating devices, resulting in a smoothing effect on the edges of a gate's output. This technology effectively mitigates voltage overshoot and ringing, enhances system efficiency, and minimizes electromagnetic interference.
Microchip established E-Mobility as one of six key megatrends and has created a team with dedicated resources to support this growing market. Using the company's "dsPIC DSCs through mSiC solutions" as a whole, engineers developing OBC apps can cut down on design complexity and speed up time-to-market.
