While the other two types are often referred to by a few different names, the mechanical AVR has a multitude, many of which indicate their purpose:. The mechanical automatic voltage regulator is the most popular for power quality applications in markets outside the United States.
Akin to the ferroresonant AVR, this type is being moved out by the electronic voltage regulator. The youngest AVR in the group is the electronic type of voltage regulator and has become the modern standard in most power quality applications. Its evolution has resulted from the advancements in power semiconductors over the last few decades. The speed and performance advantages of the electronic AVR over ferroresonant and mechanical options make it an ideal choice for electronics in industrial and commercial applications.
Although the electronic automatic voltage regulator is more expensive than the mechanical AVR, it has several advantages:. The primary function of an AVR is to prevent downtime and damage to your equipment caused by poor voltage levels from transient activity like power spikes and surges.
Spikes are momentary electrical disruptions from an increase in voltage that lasts less than three nanoseconds. Although categorized as an over-voltage, they are often undetectable and are not likely to cause harm to electronic devices. Spikes have numerous sources such as:. Thus the phase shifting circuit 44 merely serves as a delay circuit with the value of the signal from the error detector 29 changing the amount of the delay which may be from zero up to for each half cycle.
The zero delay adds the stepped alternating current in phase with the intermediate voltage while the delay subtracts the stepped alternating current from the inter-mediate voltage. Other phase delays between not only the two extremes mentioned but also for to result in changing the sum of the two voltages to produce the output voltage having the desired value. The wave forms 43 and 46 in FIG. Thus the voltage of the wave form 46 is indicated by the vector 46a while the voltage of the wave form 43 is indicated by the vector 43a and the resultant output voltage is indicated by the vector It will be thus understood that by changing the phase relationship between the wave forms 43a and 46a, the value of the output voltage may thus be changed even though there will also be a change between the phase of the output voltage and the phase of the input voltage except for the two conditions when the stepped wave 43 is exactly in phase or exactly out of phase with the intermediate voltage Moreover, by controlling the phase relationship, i.
It will accordingly be appreciated that there has been disclosed an automatic voltage regulator which regulates an alternating voltage applied to its input terminals to produce at its output terminals an alternating current which is maintained at a substantially constant value.
The regulation is achieved by producing an intermediate alternating voltage and then combining with it another voltage which consists of a stepped approximation of a sine wave.
By varying the amplitude or the phase of the stepped alternating current by sensing the actual value of the output voltage, the output voltage may thus be maintained at its desired value. Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others. An automatic voltage regulator comprising input terminals connectible to a source of alternating current, output terminals at which an output voltage having a substantially constant value appears, means connected to the input terminals for producing an intermediate alternating voltage, a source of direct current, means connected to the direct current source for producing an alternating voltage having for each half cycle a plurality of different voltage levels forming a stepped wave that approximates a sine wave, means for combining the alternating voltage with the intermediate voltage to produce the output voltage, means for sensing the deviation of the output voltage from a known value and producing a signal indicative of the deviation and means receiving the signal and operative to control the value of the alternating voltage added to the intermediate voltage, with the sum of the alternating voltage and intermediate voltage constituting the output voltage having the desired value.
The invention as defined in claim 1 in which the means for controlling the value includes means for adjusting the value of the direct current to control the amplitude of the alternating voltage. The invention as defined in claim 1 in which the means for controlling the value includes means for changing the phase relationship between the alternating voltage and the intermediate voltage.
The invention as defined in claim 4 in which the relative voltage values of each of the square waves and the phase therebetween is such that when algebraically added together they produce the alternating voltage by a step approximation of a sine wave. The invention as defined in claim 5 in which the means for controlling the value of the alternating voltage includes means for changing the amplitude of each square wave while maintaining the same relative voltage values therebetween.
The invention as defined in claim 5 in which the means for controlling the value of the alternating voltage includes means for shifting the phase of the alternating voltage with respect to the intermediate voltage while maintaining the same phase relationship between each of the square waves.
US USA en USA en. Voltage regulator with zero current static switching between tapped portions of the primary of a regulator transformer.
Voltage regulator with zero current static switching between taps for a regulator transformer. RF power supply for supplying a regulated power amplified unmodulated drive signal to an RF modulator.
When the output of the generator is short circuited, the voltage applied to the inverting input of the comparator 44 drops, resulting in maximum conduction demand on the power MOSFET 36 which now applies the rectified voltage from the auxilliary winding Z1, Z2 to the regulator output terminals F1, F2, and thus to the exciter field winding 26 in order to maintain excitation and provide a generator short-circuit current. Terminals L1,L2,L3 are normally connected to volt 3 phase tappings in the generator, referenced to L4, which is connected to neutral.
The exciter field is connected to F1, F2 and the triplidex auxilliary winding to Z1, Z2. VS and SO are normally linked which connects the internal voltage sensing network. Remote voltage trimming is possible by connecting a potentiometer across terminals R, RR. These terminals are normally linked if external trimming is not required. Under normal conditions the power supply for the exciter is provided by diodes DD21 which half wave rectifies the 3 phase supply.
Under generator short circuit conditions, voltage is available at terminals Z1, Z2 which is rectified by diodes DD The PWM waveform is obtained by using Schmitt trigger gates as level detectors and varying amplitude positive slope ramps. R11 C4 provide a filtered supply for this circuit. The main comparator 44 controls the amplitude of the ramp. IC3 pins 9 8 11 10 generate the PWM pulse by detecting any part of the ramp that exceeds 5 volts approximately.
The output of inverter 40 then, will be a varying pulse width depending on the output amplitude of comparator C19 is for local decoupling. The main comparator 44 has a negative temperature coefficient voltage reference on its non-inverting input, provided by R15, D4, ZD2.
During start up, this reference voltage charges exponentially across C6 R43 C8 to give a soft start characteristic on the generator voltage. The generator voltage sensing circuit is applied to the inverting input of the comparator Voltage is rectified, filtered and divided by components D, R, C The voltage applied to the comparator is adjustable through RV1 which is connected in a fail safe manner should the wiper go open circuit, i.
Further filtering is provided by R17 C7 before being applied to the comparator 44 through R Dynamic stability of the regulator 28 is controlled by an adjustable lag lead network 60 around the comparator 44 comprising of R20 C14 R19 RV2 C D5 limits the charge on C11 to guarantee fast recovery from overload conditions.
A protection circuit is included in the regulator to cut the excitation in event of severe overload. To sense the overload condition, IC2 pins 5 6 7 are used as a second comparator 62 with the non-inverting input being supplied from an adjustable reference voltage RV4. The inverting input senses the output amplitude of the main PWM generator. R23 and C9 integrating the detected signal. He too was a prolific inventor with many patents.
Not long ago you heard the story of the Auburn museum in Indiana and the remarkable Duesenberg automobile. Today we have another automobile story. It will be interesting for two reasons. One reason is that I played an important part in this story as did other local people, some of whom I have just mentioned.
Another reason is that, although you have lived with the automobile for many years, you will learn some things about it that few, if any, of you are familiar with. But after we finish I think you will understand them better. The modern automobile is a model of dependability. We step out of our homes at any hour of the day or night, in any kind of weather summer or winter, we turn the key. Immediately the engine goes into action and we are off to whatever mission we plan.
Few drivers today recall the hand crank era of the teens, or the problems of the early aware of the history of developments which brought electric starting to its present state of dependable performance. The electric starter was the brainchild of no less genious than Charles F. Kettering, famed inventor and for many years head of research for General Motors Corporation.
Electric starting was first introduced by Cadillac in Ford probably the last to replace the hand crank with the electric starter in the early 20's. Kettering's early concept of the electric system was a single unit doing double duty as starter and generator, the function of the generator being to keep the storage battery charged. Dodge Brothers used this system for many years. However the system which had become standard on almost all cars by the late teens or early 20's was a starting motor, geared to the flywheel during starting by a self engaging and disengaging Bendix gear, and a separate belt driven generator.
The generator was a self regulating "thurd brush" type unit which, after cut-in, produced nominally constant current regardless of car speed. The third brush, constant current generator dominated the automobile industry for more than 20 years, until about It had many problems.
For example in summer when driving on long trips the well informed driver would keep his lights on to avoid overcharging his batter. But the majority of drivers simply allowed battery life to be destroyed overcharging. The life of a battery was two years, if you were lucky. In winter there was a worse problem. Trips were much shorter and there was more need for headlights. The generator had a hard time keeping up with battery needs. Dead batteries on cold winter mornings were a common occurrence.
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