block diagram of voltage regulator
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In the current automotive electronics has become the measure of the international advanced level car under the premise of the important criteria, countries race to develop this industry, the continuous application of high technology to improve the electric performance car, in order to gain a larger market. It is in such an environment to stimulate and promote the automotive industry continues to move forward.
As we all know, poor stability and short life is the common problem of auto voltage regulator, regulator could lead to the instability of the generator output voltage, so that the vehicle electrical equipment, there is a big power supply voltage fluctuations, which on the whole vehicles is detrimental to the normal operation of the circuit, while also reducing power consumption did not prepare for life. Regulator short life will not only bring economic burden on the stability of the generator output voltage is negative.
The voltage regulator into a monolithic CMOS integrated circuit design, thus reducing the volume of the regulator, and alternator so that it can produce together. This will not only enhance the stability of the regulator to improve vehicle quality of power supply, effectively extending the service life of automotive electronic equipment, but also to adapt to the current size of small car alternator output power trends. At the same time the design is also adapted to the current regulator, "high-performance, multi-function, high power, long life," the pursuit of goals.
1 circuit and structure
Automotive regulator block diagram shown in Figure 1.
When the car started to join the input voltage, reference voltage source available to the internal reference voltage generating circuit; error amplifier receiving the output voltage signal; over-current protection circuit output current of power tube sampling; thermal protection circuit check circuit temperature; error amplifier, over- current protection and thermal protection safety zone together into the power tube circuit, when one of them as long as there is an unusual phenomenon, the regulator will be turned off, played to adjust the voltage and protection.
2 Circuit Design
2.1 front-end reference
The design of the chip front-end reference voltage circuit to provide a source of the power supply voltage and temperature are very stable in terms of follow-up reference voltage to the differential comparator circuit for comparing the difference with the sampling circuit output voltage from the generator compared to control the generator output, the circuit shown in Figure 2. Figure 2, M1, M2, M5 form current mirror, so that current flow through the three are equal, all I; M3, M4 formed voltage clamp circuit, so that A, B two voltage consistent. Mirror current source and voltage clamp circuit together form a PTAT source, with its positive temperature coefficient to compensate for the negative temperature coefficient of PN junction, resulting in essentially no change in reference voltage with temperature.
2.2 The differential comparator circuit
Differential comparator function is to control circuit voltage reference from the front-end reference voltage and the voltage generator to compare samples. When the generator output voltage below 14 V, the field current regulator to work properly, flow through the generator rotor winding excitation current rapid increase in generator output voltage is rapidly increased. When the generator output voltage reaches 14 V, the differential output voltage sufficient to drive the subsequent adjustment of the excitation current control circuit controls the gate control ground, its gate current points away, reducing the generator stator winding excitation current action, which reduces the power machine output voltage reaches the voltage regulation function. The circuit shown in Figure 3.
Output ripple voltage of the alternator has a more straight DC voltage pulse, shown in Figure 2 u. Figure 2 shows the three-phase full-wave rectified waveform and ABc overlapped each phase output waveform, is clear that the peak of the pulse of the mediums is the average voltage. Alternator alternator output voltage proportional to the induced electromotive force E, the induced emf E is proportional to the flux per pole and the generator speed, l 'is: E,. CE = Cr in, l so. When the generator speed n changes, corresponding changes in the magnetic circular per pole to achieve the purpose of maintaining the voltage constant, and each very much depends on the flux in the generator field winding current size, so the change in speed, as long as the automatic adjustment of the generator field winding current of the generator output voltage can be kept constant. Voltage regulator is to use the principle of generator voltage regulator. Voltage regulator works as a logical network 3 Gang box below. Alternator load and speed changes, etc. will cause the output voltage changes. Voltage regulator is off through the field winding current, adjust the excitation flux to compensate for the change, so that it can maintain the rating allows for fluctuations within the For example, 3.5%. 12V on all the systems. Generator power to the load requirements to maintain generator output voltage is 14v output characteristics, often used (13.5 ~ 14.5) V the voltage. If indiscriminately 4 shows, the voltage regulator is excitation current control to regulate the output voltage changes. However, even after the generator is rectified, "30, a cover 20 removed to find j leave 10O voltage regulator block diagram of Figure 3, n110" 120304050 100n (r / mirll Figure 4 straight generator power to the load curve of the DC output The role of regulators to make the actual output waveform shown in Figure 2. electromagnetic vibration mechanical voltage regulator, except bulky, contact Easy ablation, magnetic and mechanical inertia of inertia, the fatal drawback is that the output ripple voltage pulse peak amplitude large. To address and overcome these shortcomings. using non-contact, non-magnetic high-speed switching inertia and mechanical inertia of the electronic voltage regulator to reduce output ripple voltage alternator pulse peak amplitude. Figure 5 electronic voltage regulator Schematic electronic excitation coil voltage regulator basic circuit shown in Figure 5. When the AC generator speed to accelerate, the output value is higher than the default value. then connected through the hurricane transistors T: base, allowing all the excitation current is passed. Thus the output voltage to increase. when it reaches the preset voltage, the voltage regulator diode D. to turn, R. / R: is a simple voltage divider used to set the voltage for the diode. assumptions for voltage is 14.0V, the diode turns on, transistor T. turn, this product transistor T: on the Ground of the, T: is off, the magnetizing current will be cut off, the output voltage will drop. This in turn will diode D. stop conduction, T. deadline, T: another turn. so keep T as a switch, the diode absorbs the magnetic field from the excitation coil back EMF. ignored the plot is now widely used 6 IC (1c) voltage regulator circuit. with coating technology, will gather in a porcelain of different components, the core control part of an integrated circuit, the output common Darlington. While the overall principle and power regulator IC voltage regulator in Figure 6 Principle Figure 55 *