Principle of phase modulator.
A phase modulator is a circuit in which the phase of the carrier is controlled by a modulated signal. There are two main methods of sine wave phase modulation: direct phase modulation and indirect phase modulation. Direct phase modulation is to directly change the parameters of resonant loop by modulating signal, so that phase shift is generated when the carrier signal passes through the resonant loop and form phase modulation wave. Indirect phase modulation is to first modulate the amplitude of the modulated wave, and then transform the amplitude change into the phase change, so as to achieve phase modulation.
The concrete realization of direct phase modulation and indirect phase modulation
Direct phase modulation: using the modulated signal to directly change the parameters of the resonant loop, so that the carrier signal through the resonant loop phase shift. This method is simple and direct, but requires precise control of the parameters of the resonant circuit.
Indirect phase modulation: the amplitude of the modulated wave is modulated first, and then the amplitude change is converted into a phase change. This method was created by Armstrong in 1933 and is called the Armstrong modulation method.
pulse phase modulator: The pulse phase modulator changes the output phase of the pulse phase modulator through the input pulse output of the numerical control device. When the CNC device outputs a forward or reverse feed pulse, the output of the pulse phase modulator will advance or lag the reference signal by a corresponding phase Angle.
MCU realizes digital phase converter: trigger counter by clock pulse, add or subtract additional pulse to change the output phase of counter, so as to realize phase transformation.
An application example of phase modulator
Variable valve timing system: The phase modulator is the key component of the variable valve timing system, optimizing engine performance by controlling the phase of the valve timing.
Reactive power compensation device: The adjusting camera is a reactive power compensation device used to maintain voltage balance in the power system.
automotive phase regulator fault is mainly manifested as the symptoms of automotive electronic regulator failure, these symptoms include:
voltage regulator breakdown : breakdown of the FET or Darlington transistor inside the voltage regulator, causing the excitation current to run out of control, causing the generator output voltage to rise, and the battery to overcharge.
generator damaged : If the generator is damaged, the output voltage decreases and the battery cannot be charged.
effector or Darlington tube open-circuit damage : If the effector or Darlington tube open-circuit damage, the generator excitation winding lead grounded.
Battery indicator is on when no electricity is generated : The battery indicator may be on because no electricity is generated, or it may be due to high power generation. When the battery voltage drops below 10 volts, the engine wobbles, is difficult to start, or cannot accelerate and stall.
These symptoms indicate a problem with the car's electrical system, which can negatively affect the car's performance. Therefore, timely diagnosis and repair of these failures is very important .
In addition, the fault symptoms of the automobile alternator also include no charging, charging current is too small or too large, and these faults may be related to the fault of the regulator. For example, the failure to charge may be caused by a broken generator belt, a broken generator excitation line or charging line, and poor contact between the brush and the slip ring. The charging current is too small may be due to poor contact of the charging line, slip of the drive belt, generator failure or the regulator regulation voltage is too low. The charging current is too large may be because the regulator regulation voltage value is too high .
In summary, the symptoms of vehicle phase modulator failure include battery overcharge, battery failure to charge, battery indicator light, etc., which may affect the normal operation of the car. Therefore, it is necessary to diagnose and repair the fault of automobile phase modulator in time.
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