JPH0318414B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply device, and more particularly to a power supply device that switches and adjusts the output voltages of a plurality of power supply units connected in parallel and operated.

When performing a required characteristic test by variably applying a voltage at a predetermined level to the test equipment, it is necessary to connect multiple power supply units in parallel due to the current capacity of the power supply.
It is necessary to supply power to a common load, and FIG. 1 shows two power supply units U ₁ and U ₂ connected in parallel and connected to the device under test R. In Figure 1, T ₁ is a control transistor, S ₁ is a drooping circuit, and A ₁
is the error detection circuit, R ₁₀ is the output resistance, R ₁₁ , R ₁₂ ,
_R13 is an output detection resistor, and is connected to the power supply unit _U1 .
A resistor circuit is formed at the output part of , E ₁ is a reference voltage source, and M ₁ is a voltage supply source. The power supply unit _U2 is also similar to the power supply unit _U1 , and the same parts are given the same reference numerals with only the subscripts changed.

The resistors R ₁₂ and R ₂₂ are variable resistors for adjusting the output voltage. P ₁ and P ₂ are a pair of output terminals. In addition, Figure 2 represents the load straight line of the circuit in Figure 1, the horizontal axis represents the current value I _R supplied to the load, the vertical axis represents the voltage V _R applied to the load, and the straight line l represents the load straight line. represent. L ₁ indicates the output characteristics of the power supply unit U ₁ . Until the output current value reaches I 1 , the output voltage value of the power supply unit U ₁ is V ₁ , and when the output current value exceeds _{I 1 ,} it becomes a constant current characteristic. Become. _L2 indicates the output characteristic _of the power supply unit _U2 , and the output current region _I1IRI2 is a constant voltage region where the output voltage is a constant value _V2 , and the output current value _I2 is a constant current region _.

Therefore, as is clear from Fig. 2, when the load R is connected to the power supply units U ₁ and U ₂ connected in parallel,
The voltage supplied to the load R is from the power supply unit U ₂
V ₂ is determined from the output characteristics of , and the current supplied to the load is I ₃ .

Power supply units U ₁ and U ₂ connected in parallel in this way
The reason _{why the respective} output characteristics _of
This is caused not only by adjustment errors but also by non-uniformity in the circuit constants of each power supply unit.

If the output characteristics of such power supply units differ, for example, when a load fluctuation occurs, that is, when the load becomes a straight line as shown by the dashed line l' in Fig. 2, the voltage applied to the load R will be different from that of the power supply unit _U1. It is determined by the output characteristic L ₁ of , which is V ₁ in the case of Fig. 2. In this way, when two power supply units (more than one at a time) are connected in parallel, in order to adjust the output voltage, it is necessary to adjust the output voltage adjustment variable resistor of each power supply unit one by one. It is necessary to set these variable resistors so that the output characteristics of each power supply unit are uniform, and thus adjustment has conventionally required a lot of time and effort.

The present invention has been made in view of the above, and an object of the present invention is to provide a new power supply device in which the output voltage of a power supply device in which a plurality of power supply units are connected in parallel can be easily switched and set. A plurality of power supply units are equipped with a resistor circuit in the section, and the voltage value proportional to the output voltage at the dividing point of the resistor circuit is compared with a reference voltage, and the output voltage level is adjusted by reducing the difference. In a power supply device connected in parallel between a pair of common output terminals, a resistance circuit including a changeover switch is provided between the pair of output terminals, and a voltage value at a dividing point of the resistance circuit of the output section of the power supply unit is changed by the changeover. The feature is that the settings can be changed using a switch.

FIG. 3 is a configuration diagram of an embodiment of the power supply device according to the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

In FIG. 3, S is a changeover switch, which has switch terminals T 1 and T 2 connected to two relays RL _{1 and} RL ₂ connected in parallel, and _a neutral terminal T _{3 .}
It has a switch section P which is switched and connected to. _D1 ,
D ₂ is a reverse voltage absorbing diode connected in parallel to the relays RL ₁ and RL ₂ , and E ₃ is a reverse voltage absorbing diode connected to the relays RL ₁ and RL ₂ .
This is a power source for excitation. Relay contacts rl ₁ and rl ₂ are excited by the relays RL ₁ and RL ₂ to open and close, respectively, and RV ₁ and RV ₂ are output voltage setting resistors, and variable resistors are used.

Next, the operation of the circuit shown in FIG. 3 will be explained.

First, when the changeover switch S is in the neutral state, that is, the switch section P is connected to the neutral terminal _T3 , the relays R _L1 and R _L2 are both connected to the power supply _E3.
No current is supplied from the relay contacts rl ₁ , rl ₂
are in a closed state and an open state, respectively, as shown in FIG. In this case, the first and second power supply units
One end of the resistors R ₁₆ and R ₂₆ of the output section of U ₁ and U ₂ is led to the ground level via the relay contact rl ₁ , so
Error detection circuit A ₁ of these power supply units U ₁ , U ₂ ,
The voltages V _AN1 and V _AN2 applied to the negative input terminal of A ₂ are:
If the voltage applied to the load R is V _R , then V _AN1 = R ₁₅ + R ₁₆ / R ₁₄ + R ₁₅ + R ₁₆ V _R V _AN2 = R ₂₅ + R ₂₆ / R ₂₄ + R ₂₅ + R ₂₆ V _R , and these voltages are The error detection circuits A ₁ and A ₂ control the transistors T ₁ and T ₂ so that the output voltage values of the power supply units U ₁ and U ₂ become the specified values when compared with the reference voltage Vref of the power supply units U ₁ and U ₂ . Control.

The voltage between the output terminals P ₁ and P ₂ when the switch S is in the neutral "NORMAL" state, that is, the output voltage value V _R is represented by the output characteristic curves L _1N and L _2N in FIG. 4.

The output voltage appearing between output terminals P ₁ and P ₂ differs depending on the slope of the load line. In the case of the load line l' shown by the chain line in Fig. 4, the output voltage V _R becomes V _N1 , which is equal to the load line l'. In this case, the output voltage V _R becomes V _N2 .

However, V _N1 = R ₁₄ + R ₁₅ + R ₁₆ /R ₁₅ + R ₁₆ Vref V _N2 = R ₂₄ + R ₂₅ + R ₂₆ / R ₂₅ + R ₂₆ Vref.

Next, when the changeover switch S is in the "LOW" state, that is, the switch intercept P is connected to the switch terminal T ₁
When the relay R _L1 is connected to the relay R L1, the excitation current is supplied from the power source _E3 , so that the relay contact R _L1 changes from the closed state to the open state. On the other hand, relay R _L2 is not supplied with excitation current from power supply E ₃ , so relay contact rl ₂
remains open. Therefore, the resistance R ₁₆ of the output section of the first and second power supply units U ₁ and U ₂ ,
Since variable resistors R _V1 and R _V2 are connected in series between R ₂₆ and ground, these power supply units
The voltages V _AL1 and _{V AL2 applied} to the negative input terminals of the error detection circuits A ₁ and A ₂ of U 1 and U ₂ are V _R
Then, V _AL1 = R ₁₅ + R ₁₆ + 2R _V1 /R ₁₄ +R ₁₅ +R ₁₆ +R2R _V1 V _R V _AL2 = R ₂₅ +R ₂₆ +2R _V1 /R ₂₄ +R ₂₅ +R ₂₆ +R2R _V1 V _R , and these voltages is compared with the reference voltage Vref of the power supply unit, and these power supply units U ₁ ,
Error detection circuit so that the output voltage of U ₂ is the specified value
A ₁ and A ₂ control transistors T ₁ and T ₂ .

Note that the voltage V _AL1 is obtained as follows.

If R ₁₄ = R ₂₄ , R ₁₅ = R ₂₅ , and R ₁₆ = R ₂₆ , the voltage V _E at the connection point of resistors R ₁₆ and R ₁₅ is V _E = V _R (R ₁₆ /2 + R _V1 ) / (R ₁₄ + _R15 )/2+ _R16 /
2R _V1 = V _R (R ₁₆ + 2R _V1 ) / R ₁₄ + R ₁₅ + R ₁₆ + 2R _V1 ...(1).

Next, find the voltage V _AL1 applied to the negative input terminal of the error detection circuit _A1 .

V _AL1 = (V _R − V _E ) R ₁₅ / R ₁₄ + R ₁₅ V _E = (V _R − V _E ) R ₁₅ / R ₁₄ + R ₁₅ + V _E (R ₁₄ + R ₁₅ ) / R ₁₄ +
R ₁₅ = V _R R ₁₅ + V _E R ₁₄ /R ₁₄ + R ₁₅ ... (2) Substituting formula (1) into formula (2), V _AL1 = V _R R ₁₅ + (V _R R / R ₁₄ + R ₁₅ +R) _R14 / _R14 + _R15 = V _R ( _R14 + _R15 ) ( _R15 +R) / ( _R14 + _R15 ) ( _R14
+R ₁₅ +R) =V _R (R ₁₅ +R ₁₆ +2R _V1 )/R ₁₄ +R ₁₅ +R ₁₆ +2R _V1 (However, R≡R ₁₆ +2R _V1 ).

Voltage applied to the negative input terminal of error detection circuit _A2
V _AL2 can be found in the same way. When the switch S is in the LOW state, the voltage between the output terminals P ₁ and P ₂ , that is, the output voltage value, is the output characteristic curve in Figure 4.
In the case of the load line l′, as expressed by L _1L and L _2L ,
The output voltage V _R becomes V _L1 , and in the case of a load straight line l, the output voltage V _R becomes V _L2 . However, V _L1 =R ₁₄ +R ₁₅ +R ₁₆ +2R _V1 /R ₁₅ +R ₁₆ +2R _V1 V _ref V _L2 =R ₂₄ +R ₂₅ +R ₂₆ +2R _V1 /R ₂₅ +R ₂₆ +2R _V1 V _ref .

Next, when the changeover switch S is in the "HIGH" state, that is, when the switch contact P is connected to the switch terminal _T2 , the excitation current is supplied to the relay _RL2 from the power supply _E3 , so that the relay contact rL ₂ changes from the open state to the closed state, and the relay R _L1 is not supplied with excitation current from the power source E ₃ , so the relay contact rl ₁ is in the closed state. Therefore, since the variable resistor R _V2 is connected in parallel to the resistors R _{16 and} R ₂₆ of the output voltage section of the first and second power supply units U 1 and U ₂ , these power supply units U ₁ and U 2 The voltages V _AH1 and V _AH2 applied to the negative input terminals of the error detection circuits A ₁ and A ₂ in _{No. 2} are as follows: V _AH1 = _{R 15} + 2 (R _V2 (R ₁₆ /2), where VR is the voltage applied to the load. )/R ₁₄ +R ₁₅ +2
(R _V2 (R ₁₆ /2)) V _R V _AH2 = R ₂₅ +2 (R _V2 (R ₂₆ /2)) / R ₂₄ + R ₂₅ +2
(R _V2 (R ₂₆ /2)) V _R , and these voltages are the reference voltage of the power supply unit.
Compared to V _ref , these power supply units U ₁ , U ₂
The error detection circuit A ₁ ,
A ₂ controls transistors T ₁ and T ₂ .

Note that this term refers to a parallel circuit of resistors, and is a simplified version of the equation below.

The same applies to R ₁₂ /2R _V2 =R ₁₆ /2×R _V2 /R ₁₆ /2+R _V2 R ₂₆ /2R _V2 .

When the switch S is in the "HIGH" state, the output voltage value V _R of the power supply units U ₁ and U ₂ follows the load straight line as shown by the output characteristic curves L _1H and L _2H in Fig. 4.
l', the output voltage V _R is V _H1 , that is, V _H1 = R ₁₄ + R ₁₅ + 2 (R _V2 (R ₁₆ /2)) / R ₁₅ + 2 (
R _V2 (R ₁₆ /2)) V _ref , and in the case of load line l, the output voltage V _R is V _H2 ,
In other words, V _H2 = R ₂₄ + R ₂₅ + 2 (R _V2 (R ₂₆ /2)) / R ₂₅ + 2 (
R _V2 (R ₂₆ /2))×V _ref .

As is clear from FIG. 4, as the output voltage values are switched, the output voltage values V _1L , V _2L ; V _1H ,
V _2H are almost equal to each other, V _1L V _2L , V _1H V _2H , and the fluctuations in the voltage supplied to the load due to load fluctuations are slight. If the circuit constants of U ₁ and U ₂ are set to be extremely equal, the variable resistance of the output detection section is provided in common to these power supply units U ₁ and U ₂ , so that the output detection section This is because the voltage values at the dividing point of the dividing resistor are almost the same, and the output characteristics of these power supply units U ₁ and U ₂ are also almost the same.

Therefore, by adjusting the resistance values of the variable resistors R _V1 and R _V2 common to the power supply units U ₁ and U ₂ ,
Since the resistance voltage division ratio in the output voltage detection section can be adjusted at the same rate for these power supply units U ₁ and U ₂ at the same time, the output voltage can be adjusted individually for each power supply unit U ₁ and U ₂ each time the output voltage value is changed. There's no need to do it.

In addition, although the above-mentioned embodiment described a series control type power supply unit, the present invention is not limited to this, and can be similarly applied to a switching regulator.

It goes without saying that the present invention can also be applied to output voltage control of three or more power supply units connected in parallel.

As is clear from the above description, the power supply device according to the present invention has the advantage that the output voltage of a power supply device in which a plurality of power supply units are connected in parallel can be set extremely easily, and is particularly useful for use in test equipment for electronic equipment. It is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a conventional power supply device, FIG. 2 is a diagram showing the output characteristics of a power supply unit, FIG. 3 is a block diagram of an embodiment of a power supply device according to the present invention, and FIG.
The figure is an output characteristic diagram of the power supply device according to the present invention. T ₁ , T ₂ ; Transistor, A ₁ , A ₂ ; Error detection circuit, S ₁ , S ₂ ; Drooping circuit, R ₁₄ - R ₁₆ , R ₂₄ - _{R 26} ;
Resistance, R _V1 , R _V2 ; Variable resistance, R _L1 , R _L2 ; Relay,
rl ₁ , rl ₂ ; relay contact; R; load; D ₁ , D ₂ ; diode; S: selector switch.

Claims (1)

[Claims] 1. An output resistor circuit is provided between the pair of output terminals P ₁ and P ₂ , and a voltage value proportional to the output voltage at the dividing point of the resistor circuit, and reference voltages E ₁ and E ₂ are provided. A plurality of power supply units U ₁ and U ₂ are provided, and the plurality of voltage units U ₁ and U ₂ are connected to a common pair of output terminals. In the power supply device connected in parallel between P ₁ and P ₂ , the output resistance circuit includes a first resistance circuit R ₁₄ ,
R ₁₅ , R ₂₄ , R ₂₅ , and a second resistance circuit connected in series to the first resistance circuits R ₁₄ , R ₁₅ , R ₂₄ , R ₂₅ , the second resistance circuit comprising: It is shared by the plurality of power supply units U ₁ and U ₂ and is connected in series with the intermediate level output voltage resistor circuits R ₁₆ and R ₂₆ and the intermediate level output voltage resistor circuits R ₁₆ and R ₂₆ . A switchable first variable resistor RV ₁ for adjusting the low-level output voltage connected thereto and a switchable first variable resistor RV ₁ for short-circuiting the connected variable resistor RV 1 for adjusting the low-level output voltage;
a high-level output connected in parallel to a series circuit of switching means RL ₁ , rl ₁ , resistor circuits R ₁₆ , R ₂₆ for the medium-level output voltage, and variable resistor RV ₁ for adjusting the low-level output voltage; It is equipped with a series connection circuit of a variable resistor RV ₂ for voltage adjustment and second switch means RL ₂ , RL ₂ that can be opened and closed, and when setting the output voltage to a medium level, the variable resistor for adjusting the high level output voltage is used. RV ₂ , said second
When disconnecting from the first resistor circuits R ₁₄ , R ₁₅ , R ₂₄ , R ₂₅ by the switch means RL ₂ , RL ₂ and setting the output voltage to the high level,
The variable resistor RV ₂ for adjusting the high level output voltage,
The second switch means RL ₂ , rl ₂ are connected to the first resistance circuits R ₁₄ , R ₁₅ , R ₂₄ , R ₂₅ and the variable resistor for adjusting the low level output voltage.
When short-circuiting both ends of RV ₁ by the switch means RL ₁ , rl ₁ and setting the output voltage to the low level, the variable resistor RV ₂ for adjusting the high level output voltage is connected to the switch means RL ₂ , rl ₂ , the first resistor circuit R ₁₄ , R ₁₅ , R ₂₄ , R ₂₅ is disconnected, and the short circuit of the low-level output voltage adjusting variable resistor RV ₁ by the switch means RL ₁ , rl ₁ is released. A power supply device characterized by: