非继电器式全电子雨刷控制器设计

非继电器式全电子雨刷控制器设计 No Relay Type Full Electronic Wipers Controller Design Abstract The relay control methods what the wiper was controlled were commonly used in the past. In this paper, the wiper control was designed from the angle of the control. we use a unique digital circuit To achieve a full digital control, rather than relays, simple and reliable, long life. Two different control methods were given, the control method of integrating into the central control node and independent control methods. The strategic priorities of the program of two independent control were compared on the basis. A relatively simple and effective control program was obtained. A series of power-homing function implemented more accurately and simply based on wiper control was completed. Key word word文档格式规范word作业纸小票打印word模板word简历模板免费word简历 s Wiper control, relay, digital circuit, Independent control 1 Introduction Nowadays most of the automotive wiper controllers are made by relay control accomplished, and due to the inherent disadvantages as poor reliability of relay, easy wear and slow reaction etc, relays were replaced [1]intelligent switch gradually currently. For auto production companies, vehicle systems of automotive network [2][3]design were used by the overall, the cost is high, so it is necessary for intermediate product as an alternative. In this paper according to the characteristics of wiper motor, the control method integrated into the central control node and freestanding control method were put forward, and a independent wipers controller was designed on the basis, the controller was in low cost, and replaced mechanical relay control mode, is a marching forward to electronic mode. 2 Wipers controller hardware and software design Aimed at the defects controller has, we propose some changes : 2.1 PWM(Pulse Width Modulation)driver To reduce the dimensions of the Wipers controller, we use the function of the PWM just to drive the -speed coil of the wiper motor and cancel low-speed coil driver.Meanwhile,the drive mode of PWM can also easily change the pulse length and duty cycle to achieve the purpose of regulating the voltage of the motor coil to achieve real-time adjustment the speed of the wiper motor . Because in practical application , the speed of the wipers and rainwater gathered should adjust appropriate, too fast brush will not only interfere with sight but with produce a dry brush to scratch sight glass, too slow the rain will be too much to affect the line of sight. Therefore, to adjust the speed of he wiper speed does not affect the line of sight for the benefit. 2.2 Intelligent Protection In winter, due to frost the wiper arms have an possible to be frozen in glass .In this case,open the wiper controller Likely causes that wiper motor increases to run,long time of increasing turn can destroy the wiper motor.We use the intelligent units (Hardware schematic of the protection network)that have the function of overload protection, short circuit protection, overvoltage protection and overtemperature protection.Micro real-time detects the working statues of the intelligent units,if the intelligent units is abnormal ,we should shut off it promptly to protect and prevent the spread of failure. 2.3 Intermittent time to adjust In accordance with the standards, the auto windshield is prohibited to open wiper in case of no water.In a rain, if the intermittent stall is inappropriate,there will be too fast or continuous blow brush.There are 30 to 40 is in anhydrous cases of scraping brush ,for a lot of cars set the four batch files, there have complex structure,the highly cost and difficult operation , but it can not solve the problem.We use the current combination of the two switches closed intermittently stall time as the memory of the microcontroller in the node, the time interval between two nodes can work as the intermittent windshield wiper controller, time, time can be controlled in the range 3-60seconds, simple, effective way to avoid dry brush. 3 Central control integrated motor control 3.1 Integrated wiper control hardware Owing to wiper motor was most recent from the position of the master node, the wiper control module was integrated into the wiper motor from the nearest central control node. MC33486 was used in the wiper control module, output is up to 10 A stably, especially for electric window motor, wiper motor and power like the pros and cons associated with the impact of the current phase control requirements. MC33486 has two power output based on VMOS, in the control of windshield wiper motor control program, two different control power output control high-speed wiper motor coil and low-speed coil respectively. MC33486 hardware logic diagram was shown in figure 1. VBATI/O1 I/O2MCUMC33486 Status Level high gearlow gearconversioMn Motor zero feedback signalsFigure 1 Hardware logic of MC33486 diagram The hardware design of wiper motor control to ensure this output was in a low when the power output of MC33486 is closed, otherwise the result will cause MC33486 protection so that all outputs were high impedance. The reverse voltage value of diode should not be less than 400V in the design. As the feedback signal of motor is generated by spring-loaded brush, so signal level is high level of VBAT with a large burr which makes the program may produce false positives. So the level conversion circuit was inserted between the fed back signal and the MCU, and a suitable capacitor was added. Level conversion can be completed by 78L05 or regulator diode, and select the appropriate capacitor through the measure of test. Wiper motor structure was shown in figure 2. Motor shaftBrushFeedback VBATsignal Homing position Figure 2 Wiper motor structure diagram When the wiper was at the start position, the wiper motor brush is in a Low level position, the feedback signal was 0V; when the wipers turned at an angle, the wiper motor brush in the level position of VBAT, feedback signal was VBAT. The sake of the brush, the feedback signal level is not very stable horizontal level. The capacitor and converter circuit were used to buck and smooth the feedback signal level in the hardware design. Two kinds connection way of feedback signal and MCU can be chose, one is the feedback signal was connected with the general I/O of MCU directly, the other is the feedback signal was connected with the MCU's [4] [5]IRQ interrupt pin. The two connection methods are feasible in principle. The electrical feedback signal was 0V about 350ms when the motor was rotating at low speed in 24V voltage, and the electrical feedback signal was 0V about 300ms when the motor was rotating at high speed in 24V voltage. Therefore, the time of the motor in the first test location is about between 300ms-350ms, as shown in figure 3, so the feedback signals do not have to reach the response time of interrupt level, as long as response bit processing of the wiper motor in less than 300ms can be normalized. A cycle of wiper motor Non zero position Figure 3 Normal waveform of motor feedback signal At the same time, due to differences in the production craft in the manufacture process of the motor, and some wiper motors may be defective, and the upward phenomenon may occur when the power brush was brushing power, which resulting in homing signal of upward wrong. If interrupt mode was used, the miscarriage of justice of homing may appear, as shown in fgure 4. Therefore, in this paper the method of connecting with the I / O port directly was used, and the rotating inertia of motor was used cleverly to resolve the wrong homing signal generated by the defective motor. A cycle of wiper motor Non-zero position 300-350ms false homing signal of zero positiondefective brush Figure 4 Waveform of defective electrical signal 3.2 False homing signal processing The of characteristic of the motor inertia was used to resolve the false homing signal generated by the [6]defective motor in this paper, a simple strategy was used: The motor output would be set to high impedance when levels was low, and, the motor output would open when levels was high. The level jumped from the high level to the low level when the motor rotation to the homing position, due to inertia when the motor rotation, so the motor would not stop immediately, but sliding a small distance. For true homing position, the small sliding distance did not make the motor slide off homing position. In the process, the feedback signal level is always in the low state, and as long as the read fed back level was low in programming, the electrical power output would be set to high impedance. Usually the signal the false homing signal generated by the defective motor must be less than 300ms, otherwise, this motor would own two or more homing signal, and this disability degree motor are not controllable in any kind of universal wiper control system. And measured by experiment, usually the motor's residual degrees lead to less than 10ms false homing signal generally. And by experimental test, the motor inertia is enough to go through such a false signal area. The way to read I/O port was used in hardware design. The motor homing began to be determined when the switch of wiper motor was turned off. If the motor homing, the output chip of the electrical power will be set to high impedance, or maintenance rotation of motor until the level of the feedback mouth jump into a low level. If low level was false homing signal at this time, although the chip that was used to control motor power had been set to high impedance, but motor inertia will make motor glide false homing signal area, making homing signal from the low level jumped to high level again, the feedback signal is high level in this time, which hit the motor power output once again. As the motor power for a short time, the phenomenon of visual pause would not be caused. However, such phenomenon was existent from the view of test results: For some wiper motors, the motor was no-load and in high gear at 24V, when motor was stopped, the motor may be over the normal homing signal due to the wiper motor inertia, which made the motor to re-enter non-homing state, the motor rotation non-stop in phenomenon. If the lower gears were used, the phenomenon would not appear that the motor glided the normal homing signal. Thus, homing need to adopt low speed gears for homing. 3.3 The software design of integrated wiper control The flow diagram of software design showed in figure 5, the length of the timer time equal to 3s, in line with the national standard for not less than 15 times frequency per minute. Then the stall judgment was entered, stall switch state was read in by the MC33993, and would set a priority to switch, that high gear priority and lower gears, lower gears priorities in batch files, batch files prior to a file, this kinds of arrangements of priority order and auto combination switch is the same. MC33486 InitializationTimer initialization 其它任务处理低速电机归位Judge stallsNfirstRegular filecloseHigh speedLow speedHigh power low power Motor low power outputTime flag is set?outputoutputhoming? YYLow power output Low-speed, high-speed Clear timer flagoutput high impedanceNClear timer flagTroubleshootinMC33486 failure YgHandle other tasksNEndMotor YHandle homing? other tasksMaintenance of motor rotation Figure 5 flow chart of wiper control software As for MC33486 chip is concerned, with a short circuit, open circuit, over temperature protection function, when the failures above appeared, fault accumulative counter was accumulated, when the failures is cleared, the fault accumulate counter was reset. When the fault counter accumulated to 10, which is the real failure, then the fault flag is set. This treatment could avoid false positives caused by the short-term failure (such as MC33486 temporary failure caused by voltage spikes produced by the motor in the rotation process). Once the fault happened, all wipers switch should be closed, and the failure was discharged, then the switch was turned on, fault flag is cleared when t the switch was turned on again. 4 Independent wiper controller design 4.1 plans one of independent wiper controller design Assuming the motor does not leave the defects false homing phenomenon mentioned above. The homing control triggered by down jump edge of the motor feedback signal could be considered, and some inertia problems that motor works in high gear could be solved. Here in high speed control part of the wiper motor as an example to illustrate. Table 1 input and output logic of motor control Logic input logic output Switch Motor Timing output signals feedback feedback signal Input IN Signal C Signal Q0 Q1 0 0 0 0 1 X X 1 0 0 1 0 0 1 1 1 The logic state transition diagram above was shown in figure 6: IN,C=1,*IN&C=1IN,C=0,0 Q=1Q=0 IN&C=0Figure 6 the diagram of wiper motor control state transition The output logic expression that was drawn from logic truth table above was shown in formula 1. Q,IN，C&Q (1) 10 INQC Figure 7 the logic circuit of wiper motor In formula 1, Q was a logic output, Q0 was the current state, Q1 was the second state. So a logic circuit was shown in figure 7. The input IN is high when the switch was on, Q output is high, the high speed gear of the motor was started. When the motor is turned off, the input IN went low, then if the feedback signal C is low, the motor homing, the C&Q term as the output Q1 is 0, then high speed gear of the motor was turn off. If IN went low, C is 0 high, the motor did not homing, Since Q0 and C is 1, so Q&C is 1, the output of Q1 is high, the motor rotation 0 was maintained. Suppose when the motor wais closed, the motor had turned homing position due to inertia, by just logic, if the motor turned to homing, C=0,Q,1, but C&Q,0, then the output is 0, the motor was closed. 00 When the motor turned homing position due to inertia, at this time although the C=1, but at this time Q0 was 0, so C&Q,0, output is still 0. 1 For the batch file, the intermittent timing was implemented by using the timing circuit. Timing circuit was shown in figure 8. The waveform diagram generated by circuit was shown in figure 9, the intermittent control wave could be gotten from this waveform that was inverted, the time 300ms of batch file was used to start the motor turning. When the motor turned homing position, this time the output logic was maintained by the logic of C&Q,1, when the motor turned to homing position again, the next start pulse had not come yet, so the output logic was 0. A file and lower gear controlled low-speed logic, low-speed logic and high-speed logic was the same. With this program was used in the design of the circuit, the competition and adventure of logic gates should be considered, a suitable capacitor should be added in the IN input, C inputs, Q outputs to eliminate the error condition caused by the time delay. Figure 8 Timing diagram 3.5s 300ms Figure 9 waveform output control of batch file This program above was implemented while false homing of wiper motor was not taken into account, but due to the problems of the motor manufacturing process in the actual testing process, some false motor homing signals were existent. So the problem of false homing had to be considered. The above circuit was improved in order to adapt to a certain incomplete motor. The program of adding a mono stable circuit to the feedback end could be used to skip the false homing signal. The signal waveforms before and after the mono stable circuit was used were 3.5scompared. The signal waveform after the mono stable circuit was used was shown in figure 10. 300msFalse homing signal 200ms 3.5sFigure 10 The signal waveform after the mono stable circuit was used号 Wiper control functions could be done in the program, but there are two problems: lack of the homing control of power wiper and the circuit is complex. So another program that was relatively simple was put forward in this paper and the homing power design could be done by it, which was the program 2. 4.2 Plans two of independent wiper controller design The low speed gear was used in homing control on plans two to avoid the problem that some of the motors in high gear did not stop due to inertia causes. Suppose high-speed switch input H, low-speed input L, intermittent iin stall switch input I, the feedback signal was C (high level and non-homing), the above logic signal is effective in in high level, the periodic signal of the control batch file was set F, the signal is effective in low level. Therefore the in high-speed output was H, the low output was L. The high gear priority is higher than the low gear, H,H. The outoutoutin low-speed coil was used in the low gear (a file) and the batch file, which was the control L. The logic truth table out of input and output was shown in table 2. The logic formula of low speed gear output was shown in formula 2. (2) L, H,(L，I,F，C)outinininin Table 2 the logic truth table of input and output of plans two HLIFC Lin in in in out 1 × × × × 0 0 1 × × × 1 0 0 1 0 × 1 0 0 1 × 1 1 0 0 1 1 0 0 0 0 0 × 1 1 0 0 0 × 0 0 The logic circuit was shown in figure 11. The output of Lis low when H is high in plans two. At this time H is high, high-speed gear was opened. out inout And when H is low, if one of the L, C, or I&，F was high, the low-speed gear was opened, L is high. The ininininout logic meaning is when the high gear switch was closed, low speed coil was blocked to open. When high gear switch is off, low-speed coil was just allowed to open. Lwas high that means the low-speed switch was closed, C in was high that means the motor did not homing, then the motor low speed operation. When the low speed and high gears were off, intermittent gear was used to drive motor. If Iwas high and F was low, coils of the low gear in in would be start; when the motor turned first test position, C was high, F turned into high level at some point of the in motor turned first test position, this time the low speed coil running of motor was maintained by the high level of C until the C jumped into a low level, which is that the wiper motor re-homing. As the next start pulse did not come yet, the motor was in a stopped state until the next start pulse. HinHout LoutLinC Iin FinFigure 11 input and output logic circuits 路 There was not sequential logic in the above plans, the circuit and program were relatively simple. And for the motor owned a false homing signal, also was passed through the inertia of the motor rotation. If the above two plans are completed by GAL programmable logic device, can the circuit will be streamlined 5 Conclusion In this paper the operating characteristics of wiper motor were full analyzed, the control methods integrated central control node and independent control method were detailed designed, and a independent wipers controller was designed on the basis of the two independent-type schemes, the controller was low cost, and replaced the previous mechanical relay control, not only the control functions of wiper were completed effectively, the shortcoming of the motor false homing signals was solved, but also the electronic homing function was completed more precisely and effectively. 6 Acknowledgements The research work of this paper was funded by the National Natural Science Foundation of China (No. 60903011); Natural Science Foundation of Zhejiang Province (No.Y1100689), Project of Science and Technology Department of Zhejiang Province (No. 2010C31122). 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