Selection of electric vehicle 48V power supply system, wide voltage input DC/DC converter
Time:2023-02-26
Views:1231
In the automotive field, with the introduction of 48V light hybrid system and the increasing popularity of electric vehicles, DC/DC converter has become an indispensable part of the automotive power system. In electric vehicles, DC/DC converter can be used as the bridge between the power battery and the motor system to convert the power battery voltage into the voltage required by the motor to provide power for the vehicle. At the same time, the DC/DC converter can also adjust the battery output to the voltage required by various applications to supply power for low-voltage electrical equipment of the vehicle.
ROHM can be applied to DC/DC converter of 48V power supply system
After the 48V light hybrid system was proposed, it was recognized by many car companies and used in Audi SQ7, Porsche Cayenne, Bentley Benz and other models. The introduction of 48V light hybrid system can provide higher power, power and save system energy consumption for vehicles. Compared with the 12V system, the 48V light hybrid system has only 1/4 of the working current and 1/16 of the loss of the 12V system at the same power, which also helps to reduce the engine volume and carbon emissions.
With the improvement of energy conservation awareness and the transformation of 12V power supply system to 48V, ROHM, based on its technical advantages in the field of power supply, introduced a DC/DC converter BD51180 TL that can be applied to 48V power supply system to improve the conversion efficiency of vehicle power system.
BD51180 TL has a built-in 80V MOSFET, which can easily deal with the problem of high transient response voltage when the car starts. At the same time, the converter adopts a unique pulse control technology. The switching response operation can be completed within 20ns, and the fixed switching frequency is 2MHz, thus avoiding the problem of frequency interference. In addition, the output voltage of 48V battery can be reduced to 3.3V or 5V for use by on-board MCU and other control systems through primary conversion, which greatly simplifies the development process of terminal applications, avoids the power loss caused by secondary conversion, and is conducive to the realization of miniaturized and efficient product design. The unique pulse control technology mainly plays the role of phase compensation in BD51180 TL. The current is controlled by narrow pulse width to realize the phase compensation of current mode control.
BD51180 TL conforms to the application standard of vehicle specification grade AEC-Q100. The device also integrates a series of protection functions such as current protection, temperature protection, load short circuit protection, etc. The product specification is 4 * 4 * 1mm, which reduces the volume by 54% compared with products with similar performance.
TI supports DC/DC converter with 6V to 120V wide voltage input
LM5169-Q1 is a DC/DC converter introduced by TI that meets the stringent requirements of vehicle specification products and can be adjusted in a wide voltage dynamic range of 6V to 120V. The wide dynamic range of input voltage can reduce the design of surge suppression circuit to a certain extent, thus reducing the complexity of product design.
Source: TI
The minimum controllable turn-on time of LM5169-Q1 is 50ns, and the adjustable switching frequency is 1MHz. The extremely short turn-on time of the switch is conducive to improving the step-down conversion ratio of the DC/DC step-down converter and the conversion efficiency of the 48V power supply system when the voltage is reduced. At the same time, the converter also integrates the constant on-time control function to provide the system with stable switching frequency and excellent load and line transient response.
In terms of control, the converter is mainly controlled by FPWM mode and automatic mode. In the FPWM mode, the fly-buck function is supported. The FPWM mode can ensure that the CCM is forced to operate within the entire load range. In automatic mode, ultra-low Iq and diode simulation mode operation can be realized to achieve higher light load efficiency.
A MOSFET with high side and low side output channels is integrated inside the converter, with the output current up to 0.65A. At the same time, 1.9 Ω NFET step-down switch, 0.71 Ω NFET synchronous rectifier, VCC bias regulator and bootstrap diode are also integrated, which not only realizes the miniaturization of the scheme design, but also reduces the BOM cost of the circuit.
In terms of product reliability, LM5169-Q1 has passed the certification of AEC-Q100 standard, which can ensure the stability of the working performance of components between - 40 ℃ and 125 ℃, and meet the temperature requirements of the vehicle operating environment. In order to further improve the reliability of the converter, TI has integrated peak/valley current limit protection, input UVLO and thermal shutdown protection for it to avoid irreversible damage to the peripheral circuit due to the failure of the converter, Resulting in an increase in maintenance costs.
epilogue
Driven by automobile electrification, DC/DC converter has become the core component of electric vehicles and the "bridge" between high-voltage and low-voltage applications. The realization of many functions of electric vehicles requires the assistance of DC/DC converter. Nowadays, the popularity of electric vehicles is growing rapidly, and the DC/DC converter of electric vehicles will have high market value.
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