Selling points and design challenges of automotive electronics in 2010
China's automotive industry is likely to touch or cross the threshold of annual production and sales of 10million vehicles this year. In fact, before achieving this goal, China has become the world's second largest automotive market after the United States. In the current automobile, the proportion of automotive electronic systems is increasing, and many characteristic functions are realized by automotive electronic technology. If we have occupied a very important position in the manufacturing quantity, how can we synchronize with our international counterparts in the automotive electronic industry? In the last two years of the first decade of this century, which automotive electronic applications will become hot spots, and what challenges will they face in realizing these applications? The author selected several hot applications on this issue and interviewed some relevant industry experts, hoping to help readers engaged in automotive electronic system design in China. These hot applications include adaptive automotive headlights, led taillights and hid headlights, intelligent keyless entry systems, visual and radar reverse systems, etc
afs adds weight to ensure driving safety
the role of lamps in ensuring driving safety is obvious, but in practical application, there are many problems in the traditional headlamp system. For example, the lighting effect of the existing low beam lamps at close range is poor; In addition, the existing headlamp system can not solve or improve the problems of dark lighting areas when the vehicle turns and the reflected glare of water on the ground when the vehicle is driving in rainy days. The changes brought about by adaptive front lighting system (AFS) can help drivers face these problems easily
AFS refers to a headlighting system that can automatically change more than two light types to adapt to changes in vehicle driving conditions. According to Steven Nelson, global automotive marketing director of Freescale, there are many types of AFS on the market at present, ranging from relatively cheap horizontal systems to so-called light "bending" applications. Horizontal systems, which regulate the vertical aiming of lights based on the load of the vehicle, are regulated in Europe. More advanced "bending" applications can dynamically change the light aiming or beam mode according to vehicle load, acceleration/deceleration, steering wheel angle, weather conditions and other information. Such systems are generally controlled by stepper motors. " For example, when driving in a corner, the light of traditional headlights is consistent with the direction of the vehicle, so it is inevitable that there are dark areas of lighting. Once there are obstacles on the bend, it is very easy to cause traffic accidents. At this time, AFS will produce rotating light to provide sufficient lighting for the bend
Mr. Horita Shenji, general manager of the automotive electronics market center of Renesas Electronics (Shanghai) Co., Ltd., said: "There are two kinds of controls that can change the direction of the headlights. One kind needs to really rotate the short focal length headlights, and the other kind is not to rotate the headlights, but to rotate the reflector. But in either case, it is necessary to increase the motor and gearbox. The input signals that determine the rotation angle are the steering angle, vehicle speed signal, direction light, reverse switch, etc." The processing of sensor signal, the calculation of headlamp angle and the control of motor are completed by MCU, sensor and motor driver. The existing automotive electronic system has been able to collect steering angle signal, vehicle speed and other information, and has devices such as direction lights and reverse switches, while the control of the motor is no different from other motors. Horita Shinji also said, "the design challenge of AFS mainly lies in defining the specifications, and then determining how AFS works and the design of MCU software. In terms of AFS, Renesas mcub0.81 has been used in many Japanese cars for five years. Renesas can provide 16 bit mcu/m16c series and R8C series to meet the different needs of customers."
for the next development trend of AFS, Morita believes that in the future AFS, some automobile manufacturers are considering integrating image recognition functions to detect pedestrians, vehicles and roadside obstacles. In this application, a 32-bit processor with image recognition function is required. Sh7774, which is suitable for adaptive cruise control (ACC) and lane departure warning system (LDWS), is also suitable for future AFS. Led turn signal lamps are also used in newer systems. In such systems, there are a series of operable LEDs to provide functions such as horizontal and bending, so motor support is no longer required
led and hid shine brightly in the application of automotive lamps
according to Tony Armstrong, market manager of power products of linglilte company, light emitting diodes (LEDs) have been used in automotive tail lamps for more than ten years. The automotive le of Anhua high tech optoelectronic products department is now combined with the packaging detection and utilization demand of cosmetics. Mr. boon hooi Lim, product marketing manager of D, said: "more and more cars have used LEDs in the whole rear combined lamps (RCL) (including parking lights, cornering lights, tail lights and reflective lights)." Tony Armstrong also introduced: "high intensity dischargelamp (HID) lamps include all high-intensity gas discharge lamps used in general lighting, while hid used in automobiles mainly refers to hid xenon lamps, which are usually used as automobile headlamps."
why should LEDs be used in car lights, The expert of Shiqiang Telecom said, "compared with traditional vehicle signal lamps (such as incandescent lamps) In contrast, LED has the advantages of energy saving, long service life, maintenance free, explosion-proof, easy control and environmental protection. Coupled with the independent cold light characteristics of LED, the shape of the lamp will not be deformed due to long-term heating, so as to improve the service life of the whole set of lamps. Moreover, with the innovation of technology and the rise of the market, the two major bottlenecks that currently plague LED light-emitting power and cost will also be solved. "
according to Mr. Tony Armstrong, the LED used in car tail lights is mainly red LED, which has very high efficiency in converting electric energy into light output. Therefore, the heat dissipation that plagues LED applications is not a problem for red LEDs. Boon hooi Lim also said, "heat dissipation is no longer the biggest challenge in the design of LED tail lamp system. With more and more LEDs with power ranging from 0.25~1w or even higher pouring into the market, automotive tail lamp designers can easily make the right choice of LEDs according to their design style and available heat dissipation space." He also said: "most recently released LED tail lamp designs have shifted from 0.25W and 1W led to 0.5W, because 0.5W products provide a highly competitive cost to lumen performance ratio, which is very suitable for most automotive tail lamps." Anwarco released the super 0.5W plcc-4 surface mounted LED, which is very suitable for automotive tail lighting, in February 2008
the main difficulty in the application of LED tail lights is to maintain consistent brightness under all operating conditions. And continue to innovate and grow with customers in the future. Gary Wagner, product director of body electronics/intelligent switches of Fairchild Semiconductor, said: "In order to maintain consistent brightness, accurate current control is required. In order to provide flicker free operation, good line adjustment is also very necessary. The best way is to use current controlled boost converters to connect LEDs in series to form two or more parallel LED strings for redundant design. Fairchild Semiconductor provides a wide range of power components to meet the above challenges of automotive lighting design." Brian Blackburn, a senior application engineer of ansenmey semiconductor, said: "in order to obtain a wide range of applications of LED combined tail lights, appropriate driver design is very important, in which the use of linear drivers can limit power dissipation, and only led power dissipation is limited, the so-called long life can be achieved, ansenmey's drivers can well limit power dissipation."
for the application of headlights, according to the experts of Shiqiang Telecom, "hid has become the standard configuration of first-class famous cars such as Mercedes Benz and BMW because of its high brightness, long service life, energy saving, good color temperature, safety and reliability." Hid headlamp is composed of bulb itself, trigger unit and control unit or ballast. Because they are close to the hot bulb and have to withstand the vibration of the vehicle during driving, these components require temperature stability and mechanical stability. In this regard, Martina Auer, marketing manager of automotive thin film capacitor products of EPX, said: "EPX's thin film capacitor can withstand an operating temperature of up to 150 ℃ and a storage temperature of up to 170 ℃. And different pin layouts allow the system to be optimized to provide the highest mechanical stability. 6kV/μ S pulse width makes thin-film capacitors particularly suitable for trigger circuits. "
in addition, Gary Wagner of Fairchild said, "because the volume of the whole hid system needs to be reduced, how to deal with the power density and EMI requirements has become a design challenge." experts from Shiqiang Telecom also said: "There are two key problems to be solved when using HID lamps as automobile headlights: 1. The EMC problem of HID ballast; 2. The control part of HID ballast must have strong adaptability, which can adapt to cold lamps, hot lamps, and lamps of different brands, and have the intelligent protection function against some faults." Shiqiang Telecom has a single-chip full digital HID ballast solution based on silabs MCU. For the EMC problem, in addition to the traditional EMI suppression measures, the scheme also adopts advanced spread spectrum control technology (variable frequency and variable duty cycle), so that the energy of the interference signal in a certain frequency band cannot be accumulated, so as to reduce the impact of EMI. For the control part, the scheme adopts the high-speed MCU of silabs, and uses a single chip to realize the functions of hot and cold lamp recognition, lamp lighting, constant power control, PWM output, fault handling and so on, which has excellent adaptability
in addition to hid xenon lamps used in headlights applications, high brightness (HB) LEDs can also be used in such applications. Tony Armstrong said, "the manufacturing cost of HID xenon lamp is very expensive, so its use is limited to high-end vehicles. With the progress of technology, Hb LED has been introduced recently, so the use of HID xenon lamp will be reduced rapidly." Gary Wagner of Fairchild expressed a different view. He said: "in the future, LED headlights are likely to replace hid headlights, but it will take 5-10 years for LEDs used in headlights to be truly commercialized. At present, LED headlights still have the problem of cost, which is 4-5 times more expensive than hid headlights." It seems that both hid headlights and LED headlights are facing the problem of high cost. Therefore, at present, LED headlights are first used in high-end luxury vehicles, such as Lexus, Audi and Cadillac. Even so, LED headlights are mainly used as daytime running lights (DRL), and then as low beam lights for high-end vehicles, It will take some time to see the headlights using LED as high beam in more new cars. However, LED headlights can reduce the demand for electric energy and greatly reduce the power wattage required to operate the headlights from 120 watts to nearly 40 watts; In addition, LED can also be integrated into the very thin modeling lines, which are the driving forces for automobile manufacturers to use it in headlights
compared with the LED tail lamp application, the heat dissipation problem is still not completely solved for the front lamp application. Tony Armstrong of linglilte said, "the power supply of HB LED headlights really needs to pay special attention to the thermal design, because they usually need 50W power supply." Brian Blackburn, Senior Application Engineer of Anson semiconductor, revealed: "some systems use fans to cool LED headlights. But this kind of
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