JPH063563B2 - Amplifier element parallel operation circuit - Google Patents

Description

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

Conventionally, for example, when controlling a large amount of power with a transistor, it is often done by connecting in series or in parallel, but in either case, there is a problem in averaging the loss of each transistor. In particular, it is necessary to connect in parallel if high current processing is required, but since the temperature coefficient of the transistors is negative, if the temperature difference between the transistors occurs for some reason, the current of the transistor whose temperature has risen It causes a so-called runaway that becomes concentrated and out of control. As a result, the transistor may be destroyed. In order to prevent this, conventionally, for example, as shown in FIG. ₁ , resistors r _{1 to} r _n are inserted on the emitter side of the transistors Q _{1 to} Q _n , and the voltage across these resistors is used as a negative feedback voltage to generate a current. A common solution is to prevent the concentration of

However, in order to sufficiently obtain the effect of negative feedback, it is necessary to increase the resistance. If the resistance is increased, the resistance heat generation becomes large, and it is necessary to consider the heat dissipation. Further, when the voltage across the resistor increases, the sum of the collector-emitter voltage V _CE and the minimum voltage of the circuit determines the minimum voltage of the circuit, which makes it extremely difficult to distribute the current in the constant voltage large current circuit.

Figure 2 shows different lot number 2 for power transistors.
The experimental values obtained when four SD-555s were taken out without selection and a circuit as shown in FIG. 1 was constructed are shown. Curves A and B show emitter resistances r _{1 to} r ₄ in FIG.
The maximum deviation from the average value of the emitter current when Ω is shown. As is clear from the curves A and B, a large emitter resistance is required in order to suppress the current variation to be small. When used for an electronic load or a power source, it is necessary to change the emitter current.
A resistor of 12Ω is required to suppress the error between A and 2% at all times, and it is not practical in view of the voltage across the resistor (120 V) and the loss in the resistor (1200 W).

In view of the above point, the present invention has as its main object to propose this kind of amplifier element parallel operation circuit capable of solving both current balance and heat loss at once.

FIG. 3 is a circuit diagram for explaining the principle of the present invention. This circuit includes power transistors Q _{1 to} Q _n that operate in parallel,
Resistor r ₁ ~r _n and deviation amplifier the base to the transistor and the input connection points V _A1 ~V _An between each resistor and the emitter and the output for detecting the emitter current of each power transistor separately Composed of Ad. The deviation amplifier Ad outputs the deviation of each input voltage from the average value of the input voltage by one stage or two.
Each output is obtained by inverting and amplifying by an amplifier of more than stages.

FIG. 4 is a diagram showing an example of the deviation amplifier Ad. The input terminals e _i1 to e _i1 are connected to each other through the resistors ra ₁₁ ~ra _1n, to the connection point with the M. From point M, resistor ra ₂₁ ~ ra
It is connected to the positive input terminal of each operational amplifier A _{1 to} A _n through _2n . Further the input terminals e _i1 to e _i1 is connected through a resistor rf ₁₁ ~rf _1n to the negative input terminal of the operational amplifier A ₁ to A _n. Further resistor rf ₂₁ ~rf _2n is connected to the negative input terminal and an output terminal eo ₁ ~eo _n of the operational amplifiers A ₁ to A _n, resistor ra ₁₁ to Ra amplification factor of the operational amplifier A ₁ to A _n with _1n Has been decided. In this case, if the resistors ra _{11 to} ra _1n are all equal in value, the input e
The average value of _{i1 to} e _in appears, and the average value is the operational amplifier A ₁
~ A _n positive input voltage. On the other hand, each operational amplifier A _{1 to} A _n
The negative input voltage of is e _i1 to e _in , and 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 Tr _{1 to} Tr _n are common, connected to the negative terminal of the power supply through the common emitter resistance R _EE , and the collectors are connected to the positive power supply terminal through the resistors R _{L1 to} R _Ln , respectively. An input is given to the bases of the transistors Tr _{1 to} Tr _n , and an output is formed as a collector voltage of the transistors Tr _{1 to} Tr _n .

In this case, a circuit having two elements (n = 2) is known as a balanced amplifier and has been analyzed, but it is not clear about a circuit having three or more terminals. Therefore, the following results were obtained as a result of performing an analysis with each constant being arbitrary for a circuit having three or more terminals.

Output e _ol (l = 1, 2, ... n) of the circuit as shown in FIG.
Is However _{B l = (1-α l} ) r bl + r el α l = common base current gain of the transistor T _rl r _bl = transistor Tr _l internal base resistance r _el = where internal emitter resistance of the transistor Tr _l of each transistor Tr _l ~ Tr _n constants and R _L1 ~ R _Ln
Assuming that are all equal, then equation (1) becomes However the _{A = αR L / B R EE} »B.

Therefore, it is clear that the example of FIG. 5 satisfies the equation (2). Therefore, by using the circuit of the example of FIG. 3, the voltage across the emitter resistors r _{1 to} r _n has the same effect as that of the voltage across the emitter resistor shown in FIG. Therefore, if the emitter resistances r _{1 to} r _n are smaller than 1 / A as compared with the emitter resistance in the example of FIG. 1, the accuracy of the homogenization becomes better than that in the example of FIG. _{1, and} the loss in the emitter resistances r _{1 to} r _n is If it is small, the heat loss can be suppressed, and it is possible to simultaneously satisfy the uniform accuracy improvement of the current distribution of the power transistors Q1 to Qn and the reduction of the resistance loss.

FIG. 6 is a circuit diagram showing a specific example of the transistor parallel operation circuit. For simplification of explanation, the power element is 3
The case of individual pieces will be described. This example is of a type used for a power load or a constant current circuit, in which a deviation amplifier as shown in FIG. 4 is used and a circuit for controlling the entire current is added. That is, a resistor R for detecting the total current,
An error amplifier A _err that _receives V _ref as a reference voltage V _ref and the voltage generated across the resistor R and V _ref is added. Error amplifier A
The output of _err, through a resistor r ₂₁ ~r _23, and the output of the deviation amplifier Ad is connected to the base of each power transistor Q ₁ to Q ₃ through r ₁₁ ~r _13. Therefore, the deviation amplifier Ad and the error amplifier are provided at the bases of the respective transistors Q _{1 to} Q _3.
A weighted average value of the output of A _err is added, and current equalization and total current control are performed at the same time.

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

For simplification, an example using the example of FIG. 5 as the deviation amplifier will be described, but it goes without saying that it can be replaced with the example of FIG.

In FIG. 8, a current control element (transistor) Tra is inserted in place of the emitter resistance R _{EE in} the example of FIG. 7, and the output end of the error amplifier A _err is connected to the base of the current control terminal of Tra. In this case, since the weighted average value is not added to the bases of the transistors Q _{1 to} Q ₃ as in the example of FIG. 7, the output of the deviation amplifier is added to the bases of the transistors Q _{1 to} Q ₃ without being attenuated, The accuracy of equalizing the current distribution is improved. Further, the output of the error amplifier A _err is amplified by the current amplification factor of Tra, and the deviation amplifier Ad
Since the emitter input of the elements of the product of the amplification factor of the amplification factor and the error amplifier is applied to the base of each transistor Q ₁ to Q ₃ without attenuation. Therefore, the feedback amplification factor of the total current control is remarkably increased as compared with the example of FIG. 7, and the control accuracy is remarkably improved.

FIG. 9 is a circuit diagram showing still another example of the present invention. This example is a transistor Tr ₁ of the deviation amplifier Ad in the example of FIG.
Replacing to Tr ₃ to the PNP type, the added emitter follower to the output shows an example that enables shifting the output level. Emitter follower has performed impedance conversion is provided two-stage prior to the transistor Q ₁ to Q _3. The same transistor as shown in FIG. 1 is used as the emitter resistances r _{1 to} r ₃ = 0.1Ω, and the relationship between the emitter current and the maximum deviation is shown as a curve C in FIG. As a result, the error of the emitter current is extremely small, and the error is always less than 2% with respect to the current fluctuation. Therefore, as is apparent from FIG. 2, the effect of the present invention is remarkable as compared with the example of FIG.

FIG. 10 shows still another example, in the case of a large current load, one load is divided into parallel small loads from the configuration of the load itself. Z _{1 to} Z ₃ indicate divided small loads.
Incidentally, if the small loads have the same impedance, it can be controlled by the method of the above example. If when the impedance of Z ₁ to Z ₃ are equal current of the transistor Q ₁ to Q ₃ are equal, the voltage drop caused by the impedance are equal, the connecting line a (broken line shown) except the transistors Q ₁ be ~ Equalization of the power consumption of Q ₃ can be achieved.

FIG. 11 is a circuit diagram showing an example applied to a high voltage power load. In the case of a high voltage load, it is an example that control is performed via the power vacuum tubes V _{1 to} V ₃ in consideration of the risk that the collector voltages of the transistors Q _{1 to} Q ₃ become abnormally high. By grid G ₁ ~G ₃ of V ₁ ~V ₃ is added the same bias voltage, the cathode voltage is substantially equal, thus can be the similar to the above configuration example. However, in reality, V ₁
Need to adjust the grid voltage from the difference in the individual constants of ~V _3, the bias voltage applied to the G ₁ ~G ₃ is supplied from a power source which is adjusted to the collector voltage of the transistors Q ₁ to Q ₃ is equal To be done. The illustrated example shows a discharge tube having a plurality of poles as a high-voltage power load. Therefore, the total current can be controlled and the respective electrode currents can be equalized with high accuracy, and the applied voltage and power consumption of the transistors Q _{1 to} Q ₃ can be equalized and protected. When the mismatch of the cathode voltages of the vacuum tubes V _{1 to} V ₃ is not easily corrected, each cathode voltage is input to another deviation amplifier, and the output is fed back to each power source of the grid bias.
Stable homogenization can be achieved.

FIG. 12 is a circuit diagram showing still another example of the present invention. In this example, even if the emitter currents are equalized with high accuracy, the temperature of the transistors Q _{1 to} Q ₃ is not uniform due to the difference in the mounting position or the air permeability. The figure shows the arrangement of elements. As the temperature detecting element, there are an element having a positive temperature characteristic and an element having a negative temperature characteristic, and either one can be used. An example using a diode as the two-terminal element will be described below. Supply power V _DA to diodes D _{1 to} D ₃
The voltage obtained by subtracting the forward voltage is used as the input of the deviation amplifier Ad '. Since the forward voltage of the diode has a negative temperature coefficient, the cathode potential of the diode closely attached to or built in the transistor having a high temperature, that is, the deviation amplifier Ad '.
Input potential rises and the operation of the deviation amplifier Ad 'causes
The base potential of the transistor is lowered, and the temperature is equalized.

In FIG. 13, since both the current distribution and the temperature distribution are mixed and controlled in a ratio according to the application, the deviation amplifier Ad for temperature distribution is used.
The output of (T) coupled to the output of the series resistor r ₃₁ ~r ₃₃ through current sharing for deviation amplifier Ad '(I), and those configured to supply to the base of the transistor Q ₁ to Q ₃ . The other structure is the same as that of the example shown in FIG.

FIG. 14 shows the power supply V _{DA in} FIG. 13 as V _A1 -V
FIG. 9 is a circuit diagram in which one deviation amplifier Ad ′ performs the same control as the above two deviation amplifiers by replacing with _A3 . Input voltage V _in of the deviation amplifier Ad 'is calculated by the well-known approximate equation (the following equation (3)). Here, the emitter current of the power transistor Q _n is I _n , the emitter resistance is r _n , the temperature coefficient of the diode D _n is α _n , the ambient temperature is T, and the voltage drop of the diode D _n at T = 25 ° C.
If V _{nT = 25} , V _in = I _n r _n + V _{nT = 25} {1 + α _n (T-25)} ………
(3) It is expressed as n = 1, 2, 3.

When a two-terminal element such as a diode having a negative temperature coefficient is used, both V _{nT = 25} and α _n are negative. In fact, as shown in the equation (2), it is understood that the temperature distribution control is added at the same time as the emitter current distribution control. When an element having a positive temperature characteristic is used, the same operation can be obtained by setting the supply voltage V _An to the opposite polarity.

Figure 15 shows an example of using the temperature coefficient of the forward voltage of the PN junction in each transistor Tr ₁ to Tr ₃ in the deviation amplifier instead of the diode D ₁ to D _3. In the examples of FIGS. 12 to 15, the transistors Q _{1 to} Q ₃ and the diodes D _{1 to} D ₃ or the transistors Tr _{1 to} Tr ₃ are shown in broken lines to show the close contact state. According to the configuration of this example, the same effect can be obtained while being simpler than the configurations of the above-described examples of FIG. 8 and FIG.

It should be noted that although the description has been given using the transistor as each of the above-described embodiments, the use of an amplifying element such as a field effect transistor or a vacuum tube may be prevented. That is, in the above description, the amplification element is a transistor, the anode part thereof corresponds to the collector of the transistor, the cathode part of the amplification element corresponds to the emitter of the transistor, and the control electrode part of the amplification element corresponds to the base of the transistor. However, in the field effect transistor, the anode part corresponds to the drain, the cathode part of the amplifying element corresponds to the source, the control electrode part of the amplifying element corresponds to the gate, and in the vacuum tube, the anode part corresponds to the plate. However, the cathode part of the amplification element corresponds to the cathode, and the control electrode part of the amplification element corresponds to the grid. Although an example using a diode as the temperature detecting element is shown, other two-terminal elements such as a thermocouple can be used.

As described above, according to the present invention, in each of the three or more n amplifying element parallel operation circuits, the cathode portions are commonly connected through the detection resistor, and the anode portions are commonly connected directly or respectively through the load. , Having a plurality of input terminals and the same number of output terminals, and amplifying the deviation between the average value of the input voltage and each input voltage to each output, each input terminal of the deviation amplifier is the anode section and the detection resistor. Since each output terminal of the deviation amplifier is connected to the control electrode section of each amplification element, the voltage across the resistance of the cathode section becomes smaller and the current value flowing in each amplification element in the parallel circuit. Of course, even if the negative feedback resistance on the cathode side of the amplification element is small, current concentration is suppressed, so that heat loss is suppressed.

Further, in a parallel operation circuit of three or more n amplification elements in which each cathode section is commonly connected and each anode section is commonly connected, each temperature detection two-terminal element is arranged at a position affected by the temperature of each amplification element. , The anode side of the two-terminal element is connected to a positive supply voltage terminal, the cathode side is connected to a negative supply voltage terminal via a resistor, respectively, each connection point of the cathode side and the resistor, A control electrode unit of the amplification element, which has a plurality of input terminals and the same number of output terminals, is connected to each input terminal of a deviation amplifier that amplifies a deviation between an average value of the input voltage and each input voltage and outputs each output. Since the output terminals of the deviation amplifier are connected to each other, the output of the two-terminal element is applied to the input of the deviation amplifier even if the temperature varies due to the mounting position of the amplification element or the influence of air permeability. , The control electrode potential of the amplifier is lowered and the temperature is equalized To be done.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a conventional parallel operation circuit, FIG. 2 is a diagram for explaining operating characteristics, FIG. 3 is a diagram for explaining the principle of the present invention, and FIGS. 4 and 5 are respectively FIG. 6 is a diagram showing an example of a deviation amplifier, FIG. 6 is a circuit diagram showing an example of the present invention, and FIG.
FIG. 8, FIG. 9, FIG. 9, FIG. 9, FIG. 10, FIG. 11, FIG. 12, FIG. 12, FIG. 13, FIG. 14, and FIG. 15 are circuit diagrams showing other examples of the present invention. is there. Q _{1 to} Q ... Amplifying element, r _{1 to} r ... Detection resistor, Ad, A
d '... deviation amplifier, D ₁ ~D ₃ ... two-terminal elements.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuneo Ikegami 1-14-6 Ichibancho, Sendai City, Miyagi Prefecture (72) Inventor Keizo Onodera 3 Meijido, Nakameisei, Shibata-cho, Shibata-gun, Miyagi Prefecture 1 Tohoku Rico- Incorporated (72) Inventor Yoshitada Hata 2-9-13 Nakameguro, Meguro-ku, Tokyo Stanley Electric Co., Ltd. (72) Inventor Osamu Endo 2-9-18 Chidori, Ota-ku, Tokyo Micron Equipment Within the corporation (56) References Japanese Patent Publication Sho 52-17225 (JP, B2) Actual Publication 52-27356 (JP, Y1)

Claims (10)

[Claims] 1. A plurality of inputs in a parallel operation circuit of 3 or more n amplification elements in which each cathode portion is commonly connected through a detection resistor and each anode portion is commonly connected directly or through a load respectively. Each of the input terminals of the deviation amplifier, which has the same number of output terminals as the output terminals and which amplifies the deviation between the average value of the input voltage and each input voltage to obtain each output, is connected to the anode part of each amplification element and the detection resistor. An amplifier element parallel operation circuit, characterized in that each output terminal of the deviation amplifier is connected to a control electrode portion of each amplifier element. 2. A temperature detecting two-terminal element at a position affected by the temperature of each amplifying element in a parallel operation circuit of three or more n amplifying elements in which each cathode section is commonly connected and each anode section is commonly connected. , The anode side of the two-terminal element is connected to the positive supply voltage terminal, the cathode side is connected to the negative supply voltage terminal via a resistor, respectively, the cathode side and the resistor The connection point is connected to each input terminal of a deviation amplifier that has the same number of output terminals as the plurality of input terminals and amplifies the deviation between the average value of the input voltage and each input voltage to obtain each output, A parallel driving circuit for amplifying elements, characterized in that the control electrode portion of (1) and each output terminal of the deviation amplifier are connected. 3. The cathode parts are commonly connected via a resistor,
In three or more n amplifier element parallel operation circuits in which the respective anode parts are commonly connected, each of the amplifier elements has the same number of output terminals as the plurality of input terminals and amplifies the deviation between the average value of the input voltage and each input voltage. Each input terminal of the deviation amplifier for current distribution to be output is connected to each connection terminal of the cathode part and the resistor, and each temperature detection two-terminal element is arranged at a position where the temperature of each amplification element is affected. , The anode side of the two-terminal element is connected to a positive supply voltage terminal and the cathode side is connected to a negative supply voltage terminal via a resistor, respectively, and a connection point of the cathode side and the resistor, and a plurality of It has the same number of output terminals as the input terminals, and connects each input terminal of the temperature distribution deviation amplifier that amplifies the deviation between the average value of the input voltage and each input voltage to each output, and connects the current distribution and temperature. Each output terminal of the distribution deviation amplifier was connected to the control electrode section of the amplification element. Amplifying element parallel operation circuit characterized and. 4. Each cathode part is commonly connected through a resistor,
In three or more n amplification element parallel operation circuits in which each anode part is commonly connected, each temperature detection two-terminal element is arranged at a position affected by the temperature of each amplification element, and the anode side of the two-terminal element is arranged. Is connected to each connection point of the cathode portion of the amplification element and the resistor, the cathode side is connected through a resistor to a supply voltage end lower than the voltage generated at the anode portion of the amplification element, the cathode side and the above. An amplifier element parallel operation circuit characterized in that each connection point of a resistor is connected to each input terminal of a deviation amplifier, and a control electrode portion of each amplification element is connected to each output terminal of the deviation amplifier. 5. An error amplifier that receives the voltage across the current detection resistor of the amplifier element parallel operation circuit and a reference voltage as an input is added, and the output terminal of the error amplifier is the output terminal of the deviation amplifier and the amplifier. The amplifier element parallel operation circuit according to claim 1, which is connected between the element and the control electrode portion. 6. An error amplifier, which receives the voltage between both ends of a current detection resistor of the parallel operation circuit and a reference voltage, is added, and the output end of the error amplifier is each output end of the deviation amplifier and each amplification element. The amplifier element parallel operation circuit according to claim 1, which is connected between the control electrode section and the control electrode section. 7. The amplification element parallel operation circuit according to claim 2, 3, or 4, wherein the two-terminal element is an element having a negative temperature coefficient. 8. The amplifier element parallel according to claim 2, 3, or 4, wherein the two-terminal element is constituted by an element having a positive temperature coefficient, and the polarities of the supply voltages are reversed. Driving circuit. 9. The method according to claim 2, 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. Amplifier element parallel operation circuit. 10. The amplifying element comprises a transistor, a field effect transistor, or a vacuum tube.
The amplifier element parallel operation circuit according to item (2), item (3) or item (4).