[Technical Talk] Electric vehicle application—OBC, DC/DC, PDU all-in-one product solution
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Brief discussion on technology
Techtalk
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The explosive growth of electric vehicle market demand has also brought about the blooming of various component suppliers. This chapter mainly shares all-in-one application solutions such as OBC, DC/DC, PDU and electric drive for electric vehicles, which can optimize product performance to a certain extent. structural size and improved reliability.
As a relatively complete component supplier, Littelfuse covers product lines such as protection, power semiconductors, sensing, and switches, and can provide relatively complete solutions for all-in-one applications.
BMS , domain controllers, entertainment audio and video, etc. in cars will all need to use TVS and ESD as surge and electrostatic protection. The control board will also add PTC as overcurrent protection. It will also involve many low-voltage regulation circuits, which will not be detailed here. introduce.
Both low-voltage power distribution and high-voltage power distribution in automobiles require fuses and relays for overcurrent protection. The electrical framework of the vehicle in the figure below briefly describes the fuses involved in each position. With the vigorous promotion of high-voltage platforms now, copper rows are being reduced. At the same time as the wire size, the cost has also been saved, and the voltage resistance requirements for DC fuses have also been increased. The current mainstream voltage is 750-1000V, and locking bolts are used in the distribution box.
PDU application
High-voltage power distribution boxes have also been introduced in the previous chapters. Here we re-list cost-effective fuse products suitable for 500-1000V applications and comply with AEC-Q200 certification.
OBC application
The commonly used power of vehicle charger OBC is 3.3kw, 6.6kw, 11kw and 22kw. Since the all-in-one requires a more integrated structure, the OBC also needs to be made thinner. The fuse installation methods include horizontal and vertical, so it needs Higher energy density and smaller size fuses to meet the needs of structural installation.
fuse
The varistor and solid discharge tube solution has actually been introduced in many chapters, which can effectively reduce the residual voltage of lightning surges and improve the long-term reliability of the varistor, especially for increasingly thinner OBCs and busbars. With the reduction of capacitance, the surge absorption capacity becomes weaker, and the silicon carbide solution is used, which weakens the ability to withstand surge impacts. The use of pressure-sensitive and solid discharge tubes can reduce the residual voltage and reduce the damage to power devices caused by surge current.
Varistor MOV
Solid discharge tube SIDACtor
The essence of the solid discharge tube is a thyristor. By integrating the gate level into the interior and using the principle of high dv/dt to trigger it, the two-pin package of the solid discharge tube is realized. It is the main SMD product in OBC. The package is SMC, with a withstand current of 3kA for 8/20us, and the on-voltage Vt is low voltage 4V, which can be ignored after surge action.
Active clamping has also been introduced in many chapters before . It is a small thing with great functions, and it is the most cost-effective surge absorption solution.
gate driver
Gate drivers usually add a voltage regulator tube and TVS as drive overvoltage protection. Since the gate resistor has current limiting capability, the actual TVS usually does not work to the peak Vc after action, and the actual clamping voltage depends on the operating current. , between breakdown voltage Vbr and clamping voltage Vc.
The new solution for precharging relays in distribution boxes uses semiconductor MOSFET or IGBT , which can increase the service life of the relay. High-power TVS can be connected in parallel to both ends of IGBT CE , which is an effective measure to avoid IGBT overvoltage. SMD installation on PCB can also reduce Requirements for size and space.
CAN communication is used in automotive applications . The following common ESD materials are used as a reference. There are also 12V and 36V products available.
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