JPS58127421A - Amplifier element parallel operating circuit - Google Patents

Abstract

PURPOSE:To decrease a voltage across an emitter resistor and to make each amplifier element current uniform, by connecting each input terminal of a bias amplifier to a connecting point between the emitter and a detection resistor, and connecting each output terminal to the base of each amplifier element. CONSTITUTION:A circuit consisting of power transistors Q1-Q3 of parallel operation, resistors r1-r3 individually detecting an emitter current of each power transistor (TR), and a bias amplifier Ad taking connecting point VA1- VA3 between each resistor and each emitter as inputs and taking the base of the TR as each input, is provided wih a resistor R for detecting the entire current and an error amplifier Aerr taking a reference voltage Vref and a voltage across the R. Thus, the weighted average value of the outputs of the amplifier Ad and the Aerr is applied to the base of the TRQ, and the current equalization and the total current control are done at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amplifier element parallel operation circuit suitable for application to a ζr constant current/constant voltage load and a DC stabilized power supply device.

Conventionally, for example, when controlling large amounts of power using transistors, it was often done by connecting them in series or in parallel, but in either case there was a problem in averaging the losses of the individual transistors. Particularly when large currents have to be handled, it is necessary to connect them in parallel, but since the temperature coefficient of transistors is negative, if a temperature difference occurs between transistors for some reason, current will flow to the transistor whose temperature has risen. This causes a so-called out-of-control situation where the person concentrates and becomes uncontrollable. As a result, the transistor may be destroyed.

To prevent this, conventionally, as shown in FIG.
A common solution is to prevent current concentration by inserting a resistor and making the voltage across this resistor a negative feedback voltage.

However, in order to fully obtain the effect of negative feedback, it is necessary to increase the resistance. Increasing the resistance increases resistance heat generation, and consideration must be given to heat dissipation. Furthermore, as the voltage across the resistor increases, the sum of the collector-emitter voltage VOE determines the minimum voltage of the circuit, making current distribution in a low-voltage, high-current circuit extremely difficult.

Figure 2 shows two different lot numbers as power transistors.
Experimental results are shown when four SD-555's were taken out at random and a circuit as shown in FIG. 1 was constructed. Curves A and B have emitter resistances r1 to r4 of 12Ω and 3Ω, respectively, in FIG.
．． It shows the maximum deviation from the average value of the emitter current when the resistance is 5Ω. As is clear from curves A and B, a large emitter resistance is required to keep the current variation small. Furthermore, when used as an electronic load or power source, it is necessary to make the emitter current variable;
To keep the error within 2% between IOAs, use 12Ω.
A resistor is required, and the voltage across the resistor (120V) at this time is
In view of the loss (1200 W) in the resistor, it is impractical.

In view of this point, the main object of the present invention is to propose this type of amplifier element parallel operation circuit that can solve both current balance and heat loss at once.

FIG. 3 is a circuit diagram for explaining the present invention in detail. This circuit uses power transistors QI-Q that operate in parallel.
n, a resistor r1-rn for detecting the emitter current of each power transistor separately, and a connection point between each resistor and each emitter ■A+~VAlv? It consists of a deviation amplifier Ad having each input and the base of a transistor as each output. The deviation amplifier Add generates each output by inverting and amplifying the deviation of each input voltage with respect to the average value of the input voltages using one or more stages of amplifiers.

FIG. 4 is a diagram showing an example of a deviation amplifier. Each person's power ei
I ” ein are connected to each other through each r8th~[81o, and this connection point is M. From the M point to r121~
",2n is connected to the positive input terminal of each operational amplifier A1~An. Also, each human power eil" ein is rf
11-rfln to the negative input terminal of each amplifier A1-80.

Further, rflll to rfin are connected to the negative input terminal and output terminal of each operational amplifier A1 to An, and 'all''aln
Together with this, the amplification factors of the operational amplifiers A and An are determined.

In this case, if 'a l l-'aln are all equal, then
The average value of the inputs eil-e, n appears at point M, and the average value becomes the positive input voltage of the operational amplifiers A, ~An. On the other hand, the negative input voltage of each operational amplifier A1 to An is eil”
It is clear that the above condition is satisfied.

FIG. 5 is a circuit diagram showing another example of the deviation amplifier Ad.

The emitters of the plurality of transistors Tr1-Trn are made common and connected to the negative terminal of the power supply through a common emitter resistor "EE," and the collectors are connected to the positive power supply terminal through resistors J, 1 to KL, respectively. transistor T
The circuit is configured such that r, % is given to the base of the Tr calculation, and the output is taken out as the collector voltage of each transistor 11r1 to Trz.

In this case, a circuit with two elements (n=2) is known as a mosiliary amplifier and has been analyzed, but the circuit with three or more terminals is not clear. Therefore, we set arbitrary constants for circuits with three or more terminals and analyzed them, and as a result, we obtained the following results.

Output e of a circuit as shown in FIG. e (1-112...
・n) is, αl : common base current gain r of transistor Try, : ) internal base resistance 'ei of transistor Tri
:') Internal emitter resistance of transistor Ill, , Here, assuming that the constants of each transistor '■'1 to T ro and "L I" - RLn are all equal, the formula (1) becomes in eot -To one (ell --Σe1k)...
・・・・・・・・・ (2) ■Rice. 〉B.

Therefore, it is clear that the example shown in FIG. 5 satisfies equation (2). Therefore, by using the circuit of the example in FIG. 3, the voltage across the emitter resistors r, to r2 has the same effect as the voltage across the emitter resistor shown in the example of FIG. 1 at about 1/A. Therefore, if the emitter resistances r1 to rn are larger than l/A compared to the emitter resistance in the example in Figure 1, the accuracy of uniformization will be better than in the example in Figure 1, so the loss in the emitter resistances r1 to r will be smaller. By suppressing the reduction to some extent, it is possible to simultaneously improve uniform accuracy and reduce resistance loss.

FIG. 6 is a circuit diagram showing a specific example of a transistor parallel operation circuit. In addition, for the sake of simplicity, the number of power elements is 3.
I will explain this in detail. This example is of a type used in electronic loads or constant current circuits, etc., and uses a deviation amplifier as shown in FIG. 3, and adds a circuit for controlling the overall current. In other words, the resistor ■(
, standard appropriate pressure V? The voltage generated across ef and R and Vle
An error amplifier Aeir whose input is f is added. The output of the error amplifier Aerr is connected through the resistor 'U~r23, while the output of the error amplifier Ad is connected through r2+~r23 to the bases of the power transistors Q1-Q3, respectively. is added with the weighted average value of the outputs of the deviation amplifier Ad and the error amplifier A, =, and current equalization and total current control are performed simultaneously.

The configuration in FIG. 7 is almost the same as that in the example in FIG. 6 except that the circuit in the example in FIG. 5 is used as the deviation amplifier Ad.

For the sake of simplicity, an example will be described in which the example shown in FIG. 6 is used as the deviation amplifier, but it goes without saying that the example shown in FIG. 4 can be replaced.

In FIG. 8, a current control element (transistor) Tra is inserted in place of ■tEEO in the example in FIG. 7, and the output terminal of Aerr is connected to the current control terminal of Tra.

In this case, since the weighted average value is not applied to the bases of transistors Q1 to Q3 as in the example in FIG.
Q, is added to the base of Q, and the accuracy of equalization of current distribution is improved. The output of the deviation amplifier Aerr is still amplified by the current amplification factor of Tra, and becomes the emitter input of each element of the deviation amplifier, so the product of this amplification factor and the amplification factor of the error amplifier is not attenuated and is applied to each transistor Q1 to Q. , added to the base of. Therefore, the feedback amplification factor of the total current control is dramatically increased compared to the example shown in FIG. 7, and the control accuracy is therefore significantly improved.

FIG. 9 is a circuit diagram showing still another example of the present invention. In this example, the transistor Tr of the deviation amplifier Ad in the column of FIG.
, ~ shows an example in which Tr3 is replaced with a PNP type, an emitter follower is added to its output, and the output level is made shiftable. Eminotahohoroa is transistor Q
, ~Q3 are provided in two stages to perform impedance conversion. Using the same transistor as shown in the example of FIG. 1 with emitter resistances r1 to r3=0.1Ω, the relationship between the emitter current and the maximum deviation is shown as curve C in FIG. As a result, the error in the emitter current is extremely small, and even with respect to current fluctuations, the error is always less than 2 inches. Therefore, as is clear with reference to FIG. 2, it can be seen that the effects of the present invention are more significant than the example shown in FIG.

FIG. 10 shows yet another example in which, in the case of a large current load, one load is divided into parallel small loads based on the structure of the load itself. Z1 to Z3 indicate divided small loads.

Note that if the small loads have the same impedance, they can be controlled using the method described in the above example. When the impedances of Z1 to Z are equal, if the currents of transistors Q and Q are equal, the voltage drops caused by the impedances are equal, so even if connection line a (shown with a broken line) is excluded, each transistor Q1 to Q3 The collector voltages of are equal, so it is possible to equalize the power consumption of Q and -Q3.

FIG. 11 is a circuit diagram showing an example of application to a high voltage power load. In the case of high voltage loads, transistors (~Q
For example, control is performed via the power vacuum tubes v1 to V3 in consideration of the risk of the collector voltage of No. 3 becoming abnormally high. ■１
By applying the same bias voltage to the grids G and ~G of ~V3, the cathode voltages thereof become approximately equal, and therefore, the same configuration as the above example can be achieved. However, in reality, it is necessary to examine the grid Ichikawa due to the differences in the individual constants of ■1 to ■3. It is supplied from a regulated power source.The illustrated example shows a discharge tube with multiple poles as a high voltage power load.Therefore, the total current can be controlled and the current of each electrode can be equalized with high precision. At the same time, the applied voltage and power consumption of the transistors Q1 to Q3 are equalized and protected.If the discrepancy in the cand voltage of each vacuum tube V1 to V3 cannot be easily corrected, each cathode pressure is divided into a separate deviation amplifier. By feeding back the output to each grid bias power supply, stable uniformity can be achieved.

FIG. 12 is a circuit diagram showing still another example of the present invention. In this example, even if the emitter current is increased and equalized with high accuracy, the transistor Q
, ~Q3 are not uniform in temperature, a temperature detection element is shown disposed at a position affected by temperature. There are two types of temperature detection elements: elements with positive temperature characteristics and elements with negative temperature characteristics, and any of them can be used. An example in which a diode is used as the two-terminal element will be explained below. Diodes D1 to D from supply power VDA
The voltage obtained by subtracting the forward voltage of 3 is input to the deviation amplifier Ad'. Since the forward voltage of a diode has a negative temperature coefficient, the cathode potential of the diode that is closely attached to or built into a high-temperature transistor, that is, the deviation amplifier Ad
The input potential of / increases to 2, and the operation of the deviation amplifier Ad' lowers the base potential of the transistor, thereby equalizing the temperature.

Figure 13 shows a difference amplifier A for temperature distribution in order to mix and control both current distribution and temperature distribution at a ratio suitable for the application.
The output of d (T) is coupled to the output of the current distribution deviation amplifier Ad' (1) through series resistors r31 to ``33'', and is configured to be supplied to the bases of transistors Q1 to Q3. It is something. The rest of the configuration is the same as the example in FIG. 12, so the explanation will be omitted.

FIG. 14 shows the supply power VDA in the example of FIG.
, ~VA, to perform the same control as the two deviation amplifiers described above using one deviation amplifier Ad'. Input voltage v of deviation amplification 5 A d'
, n are calculated by a well-known approximate formula (formula (3) below). Here, the emitter current of the power transistor Qn is . , the emitter resistance is r. , α1, which is the temperature coefficient of the diode Dn.

Diode at ambient temperature T and r - 25 °C...
...(3) It is expressed as n=1.2.3.

When the two-terminal element uses an element with a negative temperature coefficient, such as a diode, ■nT-25. αn are both negative.

In reality, as shown in equation (2), it is understood that temperature distribution is controlled at the same time as emitter current distribution is controlled. When using an element with positive temperature characteristics, similar operation can be obtained by setting the supply power VDA to the opposite polarity.

FIG. 15 shows an example in which the temperature coefficient of the forward voltage of the PN junction in each transistor Tr, to Tr3 in the deviation amplifier is used instead of the diodes D1 to D3.

In the examples of FIGS. 12 to 13, each transistor Q, -Q3 and the diodes 1) I to D3 or the transistors Tr, to Tr3 are shown as broken lines b to represent a close contact state. According to the configuration of this example, the example in FIG. 8 and the example in FIG.
Although the configuration is simpler than the illustrated example, the same effect can be obtained.

Although the above-mentioned embodiments have been explained using transistors, the use of amplification elements such as field effect transistors or vacuum tubes is not prohibited. Furthermore, although a diode is used as the temperature detection element in the example shown, other two-terminal elements such as a thermocouple can also be used.

As described above, according to the present invention, in one (branch) path of parallel operation of amplifier elements in which each emitter is commonly connected via a detection resistor and each collector is commonly connected directly or through a load, a plurality of Each input terminal of a deviation amplifier has the same number of output terminals as input terminals, and amplifies the deviation between the average value of the input voltage and each input voltage and outputs each input terminal as a connection point between the emitter and the detection resistor. Since the configuration is such that each output terminal is connected to the base of each amplification element, the voltage across the emitter resistor is reduced, and the current value flowing through each amplification element in the parallel circuit is suppressed without variation. can.

In addition, each two-terminal element is arranged at a position affected by the temperature of the amplification element, and the anode side is connected to the positive supply voltage terminal, and the cathode side is connected to the negative supply voltage terminal through the respective resistors. Each connection point between the cathode side and the resistor is connected to each input terminal of the deviation amplifier, and the base of the amplification element is connected to each output terminal of the deviation amplifier via a series impedance.

Even if the temperature varies due to the mounting position of the amplification element or the ventilation, the output of the two-terminal element is applied to the input of the deviation multiplier, so the base potential of the amplification element decreases and the temperature decreases. Equalized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a conventional parallel operation circuit, FIG. 2 is a diagram for explaining the operating characteristics, FIG. 3 is a diagram for explaining the present invention in detail, and FIGS. 4 and 5 are respectively 6 is a circuit diagram showing an example of the present invention, FIG. 7, FIG. 8, FIG. 9, FIG. 9, FIG. 10, FIG.
2, FIG. 13, FIG. 14, and FIG. 15 are circuit diagrams showing other examples of the present invention, respectively. Q1-Q...amplification element, r1-r...detection resistor, Ad, Ad'...deviation amplifier, D1-D3...
Two terminal element. Agent Analyst Aki Yama Takashi 1st cause 2nd figure Emi, /y1 to rA) Average 41 1st theta figure P' Figure 11

Claims (1)

[Claims] 1. In an amplifying element parallel operating circuit in which emitters are commonly connected via a detection resistor and collectors are commonly connected directly or through respective loads, the same number of output terminals as a plurality of input terminals are provided. Each input terminal of a deviation amplifier is connected to each connection point between the emitter and the detection resistor, and each output terminal is connected to each connection point between the emitter and the detection resistor. An amplifier element parallel operation circuit characterized in that: is connected to the base of each amplifier element. 2. In an amplifying element parallel operation circuit in which each emitter is commonly connected and each collector is commonly connected, each two-terminal element is arranged at a position affected by the temperature of each amplifying element, and the anode side of the two-terminal element is connected to the positive supply voltage end and the cathode side connected to the negative supply voltage end through a respective resistor,
Each connection point between the cathode side and the resistor is connected to each input terminal of the deviation amplifier, and the base of the amplification element and each output terminal of the deviation amplifier are connected via a series impedance. Amplifying element parallel operation circuit. 3. In an amplification element parallel operation circuit in which each emitter is commonly connected via a resistor, connect each connection point between the emitter and the above resistor and each input end of the wing to the first deviation amplification, and Each two-terminal element is arranged at a position affected by the temperature of each amplifying element, and the anode side of the two-terminal element is connected to the positive supply voltage terminal, and the cathode side is connected to the negative supply voltage terminal through the respective resistors. A connecting point between the cathode side and the resistor is connected to each input terminal of the second deviation amplifier, and each output terminal of the first and second deviation amplifier is connected to the base of the amplifying element. A circuit for parallel operation of amplifier elements, characterized in that the amplifier elements are connected to each other through series impedances. 4. In an amplification element parallel operation circuit in which each emitter is commonly connected via a resistor, each two-terminal element is arranged at a position affected by the temperature of the amplification element, and the anode side of the two-terminal element is connected to the above emitter. A deviation amplifier is connected to each connection point between the cathode side and the resistor, and the cathode side is connected via a resistor to a supply voltage terminal lower than the voltage generated on the anode side. An amplification element parallel operation circuit characterized in that the base of each of the amplification elements is connected to each of the output ends of the deviation amplifier via a series impedance. 5. The amplification element parallel operation circuit according to claim 1, wherein each amplification element of the deviation amplifier is disposed at a position affected by the temperature of each amplification element operating in parallel. Amplifying element parallel operation circuit 7 according to claim 4, wherein the two-terminal element is constituted by an element having a positive temperature coefficient, and the polarity of the supply voltage is reversed.
4. Amplifying element parallel operation circuit according to item 1, 3, or 4. 8. Parallel amplifier elements according to claim 2, 3, or 4, wherein the two-terminal element is composed of a thermocouple, and the polarity of the supply voltage is adjusted according to the electromotive force of the thermocouple. driving circuit. 9. Claims 1, 2, 3, 4, 5, 6, 7, or 9, wherein the amplifying element is composed of a transistor, a field effect transistor, and/or a vacuum tube. The amplifier element parallel operation circuit according to item 8.