DE1917105A1 - Rectification by pnp or npn transistors - Google Patents

Description

Rectification by pnp or npn transistors The invention relates rely on rectification by pnp or npn transistors.

In control technology, certain semiconductor components always win more important. To rectify an alternating voltage and control it continuously can use the specially developed thyristors, notor speed, light and temperature regulation are controlled and regulated in this way, power thyristors from Siemens already control large ship engines.

The area of application extends and much more. on consumer electronics for the rectification of the mains alternating voltage by means of transistors in the broadcasting t Tape-1 phono-, television and telecommunication technology as well as other facilities. In the rule.

technology are transistor current switches with high performance in energy supply systems and used for continuously variable rectifier control. Used in industry you can use the half-wave control for example for motor speed control of portable Tools and machines, light or temperature control, e.g. hall darkeners or Tilermostat regulation, light-controlled switches or twilight switches.

The specially developed thyristors and triacs have the important Disadvantage that they have to be supplied with an external control voltage. These Control voltage (square, sawtooth or phase-shifted sinusoidal voltage) must extra in one pulse stage through inductances, capacitances and active components are generated before they can be used for controllable control. she cannot be tapped directly from the supply voltage. Thus the circuitry is Effort much greater, including the additionally required Components. The control voltage could be taken directly from the supply voltage a resistor are tapped, the use of such a circuit would be essential more effective.

The invention is based on the task: the circuitry To reduce the cost of electronic components; 2. Find out if the original tasks of thyristors can also be transferred to transistors can; 3. to prove that the transistor is suitable for forward and reverse operation and 4. to investigate whether the transistor can be used to rectify an alternating voltage can.

According to the invention, the problem posed is a rectification by symmetrical pnp or npn transistors characterized by the controllable Bridge rectifier control of an alternating voltage through the emitter diode and the Collector diode of two symmetrical pnp or npn transistors in emitter or Collector circuit with the possibility of combining the two positive half-waves or to regulate separately, while the rectification by asymmetrical pnp or NPN transistors are characterized by the controllable bridge rectifier control an alternating voltage through the emitter or collector diodes of two asymmetrical pnp or nph transistors.

The following description is for the sake of simplicity only on symmetrical pnp transistors. Of course, all circuits can be also perform with npn transistors. Since their description is analogous, you can do without them ozone, you can also do all circuits also perform with asymmetrical pnp or npn transistors; what else is explained.

The mode of operation of the pnp transistor in AC operation and effener base.

About the mode of operation of the transistor when applying an alternating voltage To be able to understand bass, one initially only looks at the positives. Half waves the alternating voltage (current direction) from plus to minus). You put on the emitter @ and at the collector C an alternating voltage source (10 V 50 Hz).

From this point of view, there is a "direct voltage" at the emitter with the plus potential and at the collector there is minus potential. Thus is the emitter diode something, depending on the collector reverse current, in the forward direction and the collector diode switched in blocking direction. The amount of direct current depends on the size of the junction resistance depends on the collector diode. So only the reverse current of the collector diode flows (also collector residual current with effener base) The externally applied direct voltage (Emitter plus: collector minus) takes effect immediately at the barrier layer ##, because it lacks movable load carriers. Those outside the barrier free charge carriers (holes +) are opposed due to their polar properties driven the space charge layer. This is traversed by charge carriers, so that the diffusion voltage UDiff ## somewhat, depending on the collector reverse current, gets smaller. The potential threshold becomes a little smaller and the emitter diode is switched a little more in the forward direction (Fig.2) With the opposite "Incorrect polarization" of the current source at the collector diode will increasingly be pelled Charge carriers sucked off the space charge layer #####, whereby the space charge and the diffusion voltage UDiff ##### become somewhat larger. The potential shaft increases and prevents the charge exchange: The collector reverse current is thus of depending on the size of the potential threshold and the UDiff di. negative half-waves of the 50 Hz generator, there is a "direct voltage" at the emitter with the minus potential and the plus potential on the collector. In this way the emitter diode is in the reverse direction and the collector diode is somewhat dependent from the emitter reverse current, switched in the forward direction: The amount of the reverse current depends on the size of the junction resistance of the emitter diode. It flows so only the reverse current of the emitter diode: the externally applied direct voltage (Emitter minus; collector plus) takes effect directly at the barrier layers.

The physical semiconductor processes are now reversed than with the positive half-waves. The diffusion voltage UDiff #### increases somewhat (Fig. 3). The potential threshold also increases and the emitter diode blocks a bit more. The diffusion voltage UDiff ##### becomes somewhat smaller. The potential threshold also becomes smaller and maintains the minimal charge exchange. The emitter reverse current is therefore dependent on the size of the potential threshold and the UDiff ####: lets we now have both half-waves of the alternating voltage, the positive and the negative alternately act one after the other, a spinus voltage of 50 Hz is obtained.

This sinusoidal voltage causes the emitter diode in the case of the positive half-wave somewhat switched in the forward direction and that at the negative half-wave the collector diode something is switched in the forward direction. The respective forward currents of the emitter or collector diode can with different Different doping large v e It can happen that the positive amplitude is smaller than the negative Amplitude or vice versa. With the same doping of the p1, n and p2 layers, the Forward current, the size of which is determined by the reverse current, is the same: Both Amplitudes have the same height. The forward currents vary between 50-250 UA Alternating current: The following applies: Forward current = reverse current. With the help of two diodes and headphones one can prove that a small alternating current flows (Fig. 4), diode Df1 leaves only positive, diode Dz only negative half.

wave through. The sum of the positive and negative half-waves is together a detectable alternating voltage: An alternating current flows, composed from emitter and collector residual current.

Adjustable half-wave rectifier control of an alternating voltage the emitter diode of a pnp transistor in an emitter circuit.

An alternating voltage generator is also installed (f = 50 Hz Uoff = 10 V) to the emitter and to the collector. First, only look at the positive ones Half-waves of the generator (current direction from plus to minus). At the emitter So a DC voltage (plus) and at the collector minus). The emitter diode is through the correct pelung somewhat, depending on the collector reverse current, in the forward direction switched, in contrast only collector diode, which is polarized in the opposite direction and consequently the DC voltage blocks. The amount of direct current is from the collector junction resistance addicted.

Only the collector reverse current flows through the emitter diode when it is open Base. To reduce the collector blocking resistance so that a "direct current" that the potential at the base can flow through free negative electrons raise. This is done by adding an adjustable resistor EBi from the base switches to the negative pole of the generator (Fig. 5). The negative base tension can be a direct voltage or an alternating voltage with the same phase angle, the is rectified by the collector diode or emitter diode. Suddenly it is Collector barrier layer permeable to positive half-waves: in the semiconductor layer the following: The junction width of the emitter diode #### is due to the free electrons much narrower at the base. The emitter diode becomes more and more forward operated.

The junction width of the collector diode #### is due to the free Electrons much wider. Overall, an emitter stream flows, its positive Charge carriers (holes +) pierce the base enriched with free electrons and to a certain extent "injected" into the collector layer (injection current). In the base itself, the holes in the fold-free space move solely by diffusion forces driven. Once you get the right one Reach the barrier, see the voltage at the np2 junction accelerates the defect electrons considerably Further. In the field-free area of the collector layer they drift unaccelerated, So continue without the influence of an electric field and then recombine with the Electrons. With the controllable RB1 you can control the diffusion forces and thus control the permeability of the collector barrier to positive half-waves and thus regulate. An infinitely variable "DC voltage" is obtained: Then we now consider the negative half-waves of the generator. Now is on the emitter a DC voltage with the negative pole and the positive pole on the collector (Fig. 6). the Collector diode is due to correct polarity, depending on emitter reverse current, switched in the forward direction, in contrast to the emitter diode, the opposite is polarized and therefore blocks. By adding the base resistor RBi lay free electrons on the base and cause the barrier layer to Bn Dependent.

of the resistance value, increased. The counteracting diffusion tension UDiff #### gets bigger, prevents any charge exchange and the potential sinks. The emitter diode still blocks, so that the residual current is even smaller, than with an open base. The barrier layer area ##### can only narrow so much, as the reverse current of the emitter diode allows. There are free electrons on the base, but they come from the positive terminal of the battery. It arises between C and @ no great difference in charge, so that the collector diode also blocks than lets through. Nevertheless, it should be noted: The collector barrier layer ##### is narrower than with an open basis without RBi; the emitter barrier layer #### is wider than at open basis (without RBi). In this way the negative half-waves become perfect locked. The negative amplitude is almost absent.

handle: The extremely small residual current can be measured purely during operation hardly capture moor.

After the positive and negative half-waves have been separated.

one now leaves a pure sinusoidal alternating voltage at the Transistor act. As can be seen from both theoretical discussions Use the transistor as a half-wave rectifier: it lets the positive half-waves pass and block the negative half-waves. By regulating the basic resistance RBi controls the number of free electrons, the two diffusion voltages and can continuously regulate the positive amplitudes: Fractical experiments with a Philips oscillographs GM 5601 have subsequently proven that the amplitudes are not are impaired in their form and that the transistor as a controllable rectifier for di. Technology is suitable. Guts rule properties result if you all three layers (p1, n and p2) are equally heavily doped as you do this both amplitudes can be controlled electronically, as will be seen later.

Adjustable half-wave rectifier control of an alternating voltage the collector diode of a pnp transistor in a collector circuit.

After installing an alternating voltage generator (f = 50 Hz Ueff = 10 V ) has placed on the collector and ritter, one only looks at the positive ones at first Half waves. At the emitter there is a "direct voltage" (plus) and at the collector (minus) (Fig. 7).

The emitter diode is minimal in the forward direction and the collector diode switched completely in reverse direction. So only the collector reverse current flows through the itter diode. By adding the base resistor RB2 from the base to the Emitter (plus) the base potential is raised by free electrons. 11 semiconductors The following happens: Dt. free electrons at the base cause the barrier layer surface the collector diode ##### widens and builds up a larger space charge. Consequently there is a greater diffusion voltage UDiff ##### that affects the defect electrons counteracts. A large potential gradient is created and the collector diode blocks fully.

The junction area of the emitter diode can only be minimal, in Dependence on the collector reverse current, because the free base electrons decrease are directional. Because of their opposite polarity, they can reduce the diffusion voltage Do not reduce UDiff ####. Only the collector reverse current of the collector diode causes that the barrier layer area is reduced somewhat.

The potential difference is so small that only a very small reverse current can flow, which is smaller than the collector reverse current with an open base: The positive half-waves are therefore blocked.

Then we first consider the negative half-waves of the generator. The directional free base electrons cause the barrier layer area ##### to decrease and the diffusion voltage UDiff ##### also to decrease (Fig. 8). There is a small potential gradient from C - B and the collector diode is polarized in the forward direction. The opposite polarity of the emitter diode widens the junction area and the diffusion voltage UDiff #### increases. The potential gradient becomes greater and a large potential difference arises between the barrier layers, which enables a hole to flow. The negative half-waves are allowed to pass, in contrast to the positive half-waves, which are blocked. By changing the base resistor RB2 in advance, a controllable transistor half-wave rectification is obtained through the collector diode: Technical name: The controllable bridge rectifier control of an alternating voltage through the emitter and collector diodes of two pnp transistors in an emitter circuit with the option of regulating the two positive half-waves together or separately.

A bridge rectifier consists of four oppositely connected Diodes. The current flows through two of the diodes at the same time, while the other Diodes block the current.

As shown, the transistor can also be used as a controllable half-wave rectifier use. With an adjustable bridge rectifier, you replace two oppositely switched diodes by two pnp or npn transistors. The first transistor is allowed only let through positive half-waves and must negative half waves lock. The second transistor may only be permeable to negative half-waves and must block positive half-waves. The individual physical semiconductor processes have already been explained. To better understand the functioning of this circuit to be able to, one again only considers the positive half-waves of the alternator: The positive half-waves (arrows-) reach the diode D2 and are let through there, in contrast to the negative half-waves, which are blocked (Fig. 9). The positive ones Half-waves reach the emitter of the transistor via the load resistor RL (consumer) T1. Purely in terms of circuitry, transistor T1 only allows positive half-waves to pass and blocks the negative half-waves. With the base of T open, the emitter diode is somewhat in the forward direction, in contrast to the collector diode, which has the positive Half-wave blocks. When the base resistor RBl is added, free c Electrons (correct polarity) on the base. By changing the resistance value you can control the number of electrons at the base and in this way regulate the Permeability of the bollector diode for positive half-waves. A rectification occurs the emitter diode T1 and at the same time a control effect of the collector diode T1 without Falsification of the amplitudes in any way. Locks in the negative half-waves the transistor Tt, whose blocking characteristic is improved by the base resistor RBl will. The reverse current flowing now is smaller than with an open base. The reverse current is in turn caused by the positive half-waves of transistor T2 (reverse negative Half waves). The transistor T1 controls the positive half-waves from the phase angle o °> 1800 and the negative blocked half-waves from the phase angle 18Q - 3600 are generated by positive half-waves of transistor T2 from 1800 -0 360, which are opposed, canceled. The next thing to look at is the negative Half-waves (arrows) of the alternator. The negative half-waves arrive to diode D1 and are let through there, in contrast to the positive half-waves, which are blocked. The negative ones reach via the load resistance RL (consumer) Half waves the Collector of transistor T2. The transistor T2 is only permeable for 2 negative half-waves like the diode D2 and blocks the positive ones Half waves. With the base of the transistor T2 open, the collector diode is something for the negative half-waves switched in the forward direction, in contrast to the emitter diode, which blocks the negative half-waves and only allows positive half-waves to pass through is. When the base resistor RB 2 is switched on, free e electrons (correct Polarity) to the base. By changing the base resistance in its ohmic value you control the number of electrons at the base and thus regulate the permeability the emitter diode fir-negative half-waves. If you look at the mode of action very much exactly, so only the negative half-waves are let through at the collector of transistor T2, without any regulation of the negative amplitudes taking place. Only at the emitter barrier layer the negative amplitudes are regulated or controlled higher. On the collector base layer a rectification can be made, which at the base emitter junction in the negative Amplitude levels is regulated. There are two effects in one system. In the case of the positive half-waves, the transistor T2 blocks its blocking characteristic is improved by the basic resistance RB2.

The now flowing barrage is smaller than with an open base. The positive half-waves of the transistor T1 (phase angle 0 o - 1800) raised the negative half-wave blocking current (phase angle o0 - 180 °) from T2 to, so that no Reverse current flows more.

The transistor T2 regulates the positive, once negative half-waves, from phase angle 18o0 - 3600 and the transistor T1 regulates the positive half-waves from the phase angle o ° -180 °.

In this way you get a bridge rectification, its amplitudes are adjustable from o ° - 3600 phase angle. One can also steplessly from a one-way rectification switch to a bridge rectification, with the efficiency doubling.

Replace the two diodes dz and D2 (Fig. 9) with each other, you have to switch the circuit as shown in Fig. 10. It should be noted, that the transistors T1 and T2 also have to be exchanged for each other (Fig. 10) Fig. 11 and Fig. 12 show the basic structure as in Fig. 9 and Fig. 10, however, these formworks are designed with npn transistors an alternating voltage through the emitter diodes of two pnp transistors in emitter and collector circuit, with the possibility of combining the two positive half-waves or to be regulated separately.

Research has shown that due to the low demand, no longer produces symmetrical transistors. But to meet the requirements of the industry To be able to comply, it has been investigated whether on instead of the symmetrical transistors can also use asymmetrical transistors (inverse operation is not possible).

To better understand the functioning of such a circuit can, one looks at. initially only the positive half-waves of the AC voltage source. The positive half-waves reach the emitter of the transistor via the diode D2 T1 (Fig. 13). The transistor T1 and the diode. D2 are connected so that they only Allow positive half-waves to pass and block negative half-waves. With an open basis of T1, the emitter-base diode is transparent to positive half-waves, in contrast to the Iollektor-Basis-Diod., which blocks the positive half-waves. So it just flows a small residual current, the size of which is determined by the collector-base diode. If the base resistor RB1 is then added, negative charge carriers arrive on the base and cause the junction resistance of the collector-base diode degrades.

Thus, the transistor T1 is operated in the forward direction and it a current flow of positive half-waves is possible, which is controlled by the base current will. The transistor T1 is operated in the emitter circuit, since it is the best utilization of the transistor reached. In the case of the negative half-waves, the transistor T1 blocks completely, since it is operated inversely in this way. An inverse operation is however not possible and the blocking characteristic of the emitter-base diode is still through the base resistance improves, since positive charge carriers via the base resistance get to the base. The reverse current flowing in this way is even smaller than with Forward operation and open base! The transistor T1 is used to regulate the positive Half waves of the sinusoidal alternating voltage with a phase angle of o ° - 180 °. Considered next the negative half-waves of the AC voltage source. As with a bridge rectifier Both half-waves of the sinusoidal voltage are used, the negative half-wave must the alternating voltage can be converted into a positive half-wave Consideration cannot therefore be referred to as a negative half-wave (otherwise no direct current would flow through the load resistor N (Fig. 13)).

The newly gained positive half-wave is located at the emitter of the transistor T2 on. In this way, the positive pole is on the emitter and the negative pole is on the collector, so that the transistor T2 is operated forward and in collector connection. at open base of T2, the emitter-base diode is permeable for positive half-waves, in contrast to the collector-base diode, which blocks the positive half-waves. All in all only a small reverse current flows, which is due to the reverse characteristic of the collector-base-diode is determined. Only when the base resistor RB2 is switched on do negative ones arrive Charge carriers on the base and the barrier layer is broken down. The transistor T2 is operated in the forward direction and there is a current flow of positive half-waves possible. In the case of the negative half-waves, the transistor T2 blocks completely because it is inverse is operated. However, there is no inverse operation possible and the blocking characteristic of the emitter-base diode is determined by the base resistance improved, as positive charge carriers get to the base. With the transistor T2 you regulate the once negative half-waves, which are now positive from the phase angle 180 ° - 360 ° and the transistor T1 regulates the positive half-waves of phase angle 0 ° - 180 °.

In this way, lau receives a bridge rectification, its amplitudes are adjustable from 0 ° - 360 ° phase angle.

If the diodes D1 and D2 are exchanged for each other (Fig. 13), so that if they are connected as in Fig. 14, the two transistors must also be connected to one another exchange and you will find that the principle of this circuit is nothing has changed. The circuit in Fig. 14 is even in the k (copper-clad Pertinax technique) more cumbersome to manufacture.

Fig. 15 shows the principle of the bridge rectifier circuit in Fig. 13, but this circuit is equipped with npn transistors, in contrast to Fig. 13, in which PNP transistors are used.

In Fig. 16 the two diodes D1 and D2 from Fig. 15 are against each other been swapped. Thus, the transistors from Fig. 15 must also be against each other be replaced.

Achievable advantages: Circuit technology.R effort: No major circuit technology Effort, less than with thyristors.

Less electronic components; one saves capacities and inductances.

Much simpler circuit technology than with thyristors.

Small dimensions.

Control voltage.

Control voltage for regulating the supply voltage is taken directly from the Mains voltage obtained without special networks.

The control voltage can be an alternating, direct, sawtooth or square wave. or phase shifted sinusoidal voltage.

With a sinusoidal voltage, the control voltage is independent of the capacitive one or inductive load.

Universal applications in all technical areas. Series production is more profitable than with thyristors.

Higher switching frequency limits compared to the thyristors.

Claims (2)

Claims 1. Rectification characterized by symmetrical pnp or npn transistors through the adjustable bridge level. rectifier control of an alternating voltage through the emitter diode (E ) and the collector diode (C) of two symmetrical pnp or npn transistors in emitter or collector circuit with the option of the two positive half-waves to be regulated together or separately. 2. Rectification characterized by asymmetrical pnp or npn transistors through the controllable bridge rectifier control of an alternating voltage through the Emitter or collector diodes of two asymmetrical pnp or npn transistors. L e r s e i t e