JPH0146884B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an output control method for a power supply device such as an arc power supply that supplies a stable output to a load whose load resistance tends to fluctuate.

Conventionally, in this type of stabilized power supply, as shown in Figures 1 and 2, the voltage V _T generated between the collector and emitter of the transistor section 1, which is a fine adjustment function section that finely adjusts the output, is detected. Then, the output voltage of the thyristor rectifier section 3, which is a coarse adjustment function section that roughly adjusts the output through the controller 2, is adjusted by feedback to keep it constant, and the load on the transistor section 1 is reduced with respect to fluctuations in the load 4. was controlled so as not to increase as much as possible. Here, FIG. 1 shows the case of a constant current power supply, in which the output current is detected by a current detector 5 such as a shunt, and the transistor section 1 is controlled through an amplifier 6 so that the current becomes constant. . Further, FIG. 2 shows the case of a constant voltage power supply. In this case, the output voltage is detected by the voltage detector 7, and the transistor section 1 is controlled through the amplifier 6 so that the voltage becomes constant. The device is expected to produce highly accurate and economical output over a wide output range by combining the quick response, efficiency, and economy of a thyristor rectifier with the advantages of accuracy and quick response of a transistor. It is used in cases.

The disadvantage of the conventional device is that the voltage across the filter 8 due to the output of the thyristor rectifier section 3 is usually quite large compared to the collector-emitter voltage V _T of the transistor section 1, so a relatively small voltage change across the filter 8 is required. appears as a large change in the voltage V _T , and this voltage change is fed back to the thyristor control unit 3 via the controller 2 for control, making the operation unstable and prone to hunting, and the transistor Another drawback was that the margin ratio had to be increased. In this way, the voltage V _T is easily affected by large changes in the load, and when adjusting the output of the thyristor rectifier section 3 using feedback, the filter 8, which is a time delay element, is also inserted, so the thyristor The area between the rectifier section and the filter tends to become unstable, and in order to absorb all of this, the thyristor rectifier section 3
response must be very slow. If the response of the thyristor rectifier section is made slow, the advantage of (1) the thyristor's quick response will not be exhibited. (2) During the transition period, the voltage V _T of the transistor section 1 becomes considerably large, or the load is concentrated on an absorber or the like (not shown) connected in parallel to the transistor section. (3) Therefore, it is difficult to achieve preferable control, as a large margin must be taken into account for transistors, absorbers, etc.

In order to solve the problems of the conventional method, the present invention detects the state of a load as a function of the resistance value of the load, and connects the voltage that is a function of the load resistance with a predetermined constant voltage. The synthesized voltage is used as the output voltage setting value of the thyristor rectifier section, and the thyristor rectifier section is controlled independently from the fine adjustment function section so that the output voltage of the thyristor rectifier section follows this output voltage setting value, thereby making fine adjustments. The present invention provides a method for controlling the output of a stabilized power supply that reduces the burden on a transistor section of a functional section and enables stable operation.

Examples according to the present invention will be described below.

FIG. 3 is a diagram showing an embodiment according to the present invention, which is a case of a constant current power supply.

First, to explain the outline of this embodiment, the output voltage setting value of the thyristor rectifier section 3, that is, the resistor 23
The voltage input to the controller 2 from the connection point between the resistor 24 and 24 is the constant voltage generated across the resistor 24 due to the constant current flowing through it, and the voltage generated there due to the current flowing through the resistor 19 which is a function of the load resistance. The voltage is the sum of The output voltage setpoint is therefore the sum of a constant voltage and a voltage that is a function of the load resistance. Here, the constant voltage is a voltage corresponding to the voltage drop in the main circuit excluding the voltage of the load 4, that is, the sum of the voltage drop of the inductor of the filter 8, the collector-emitter voltage of the transistor section 1, etc. This voltage can be considered to be almost constant because the current flowing through the main circuit is a constant current. Therefore, the thyristor rectifier section 3 is controlled independently of the fine adjustment function section consisting of the transistor section 1 and the like so as to follow the output voltage setting value of the sum of the constant voltage and the voltage proportional to the load resistance. Even if the resistance of the load 4 changes over a wide range or suddenly changes, the output voltage of the thyristor rectifier section 3 can be controlled according to the resistance of the load 4, and all the problems of the conventional methods can therefore be solved.

In FIG. 3, logarithmic converters 11 and 12, antilog converter 13, resistor 14, and voltage-current converter 18
constitutes an example of an arithmetic circuit that provides a current signal proportional to the resistance value of the load 4 to the resistor 19. Detected current I detected by load current detector 9 and voltage detector 1
By logarithmically converting the detected voltage V detected at 0 using logarithmic converters 11 and 12, respectively,
Forms logI and logV signals. By first subtracting these signals in the antilog converter 13 and then converting them into antilog, (logV−logI)=log(V/
A signal of I)=X, e ^x =V/I is formed. The detection current I and the detection voltage V are values proportional to the load current I _L and the load voltage V _L , respectively, so V=aV _L (a is a proportionality constant), I=bI _L (b is a proportionality constant), V/I =
aV _L /bI _L =a/b·R _L , and V/I has a value proportional to the load resistance R _L.

That is, the antilog converter 13 causes a current proportional to the load resistance to flow through the resistor 14, and forms a voltage proportional to the resistance value of the load 4 across the resistor 14. This voltage is input to the amplifier 15 of the voltage-current converter 18. Since the amplifier 15 produces an output such that the voltages applied to its respective input terminals are equal, if the voltages at its input terminals are approximately equal, the resistor 16
The voltage drop is approximately equal to the voltage across resistor 14. Therefore, for example, if the resistance value of the resistor 16 is selected to be 1/1000 of the resistance value of the resistor 14, the resistance value of the resistor 14
The value of the current flowing through resistor 16 and transistor 17 is approximately 1000 times greater than the current flowing through resistor 16 and transistor 17. Therefore, by appropriately selecting the constants of the circuit 18, a desired magnitude of current i proportional to the load resistance can be caused to flow from the circuit 18 to the output voltage setting variable resistor 19 for the thyristor rectifier section. By the way, since a constant voltage obtained by subtracting the base-emitter voltage of the transistor 22 from the voltage of the constant voltage diode 21 is applied to the resistor 20, a constant current i' flows through the resistor 20, the transistor 22, and the resistors 23 and 24. This constant current i' is set to be proportional to the constant current flowing through the main circuit including the transistor section 1, the load 4, etc. This setting is performed by setting the resistance value of the variable resistor 19 in conjunction with the adjustment of the output current setting variable resistor 27 of the current fine adjustment section including the transistor section 1.

Here, if the resistance values of the resistor 24 and the variable resistor 19 are R ₂₄ and R ₁₉ , respectively, then the output voltage setting signal V _R shown by the following equation (1) is input to the reference side input terminal of the controller 2. .

i′R ₂₄ +i′R ₁₉ +iR ₁₉ =V _R ...(1) Also, the output voltage of the thyristor rectifier section 3 is connected to the other input terminal of the controller 2 through resistors 25 and 26.
The detected voltage divided by is input. Here, the controller 2 is a conventional controller including a differential amplifier and a pulse generator that generates pulses having a phase corresponding to the output signal thereof. Therefore controller 2
applies a firing pulse to the thyristor rectifier section 3 with a phase corresponding to the magnitude of the difference between the output voltage setting signal and the output voltage detection signal of the thyristor rectifier section 3. As can be seen from the above explanation, the thyristor rectifier section 3 is controlled regardless of the magnitude of the voltage between the collector and emitter of the transistor section 1.
produces an output voltage proportional to the magnitude of the resistance.

Here, if the set current of the load 4 is I, the output voltage determined by the load resistance is V, the collector-emitter voltage of the transistor section 1 is V _T , and the circuit loss resistance is R, then the output of the thyristor rectifier section 3 is The voltage is E=V _T +IR+V (2).

By the way, since the thyristor rectifier section 3 is controlled by the controller 2 to produce an output voltage that follows the output voltage setting value shown by equation (1), equation (2) is naturally proportional to equation (1). Comparing equations (1) and (2), it can be seen that the output voltage E of the thyristor rectifier section 3 and the output voltage V across the load 4 are proportional, and the voltage
It is clear that V _R and voltage E are proportional, so
Voltage V and voltage V _R are proportional, and since (i′R ₂₄ + i′R ₁₉ ) is constant in equation (1), voltage V _R is proportional to voltage iR ₁₉ , so in the end, voltage V is Proportional to iR ₁₉ .

Further, since the resistors 19 and 27 are adjusted in conjunction with each other, the currents i' and I are proportional to each other, and since the circuit loss resistance R and the resistance _R19 are each constant, IR is proportional to _i'R19 .

Therefore, from the above, the voltages V _R and E are proportional;
Since iR ₁₉ and voltage V are proportional, and i'R ₁₉ and IR are also proportional, voltage V _T has a value proportional to i'R ₂₄ . Here, i′R ₂₄ is constant, so after all,
Collector-emitter voltage V _T of transistor 1
is held constant.

Note that the operation in the fine adjustment function section is similar to that of a normal constant current circuit, and the output current is detected by a voltage detector 5 such as a shunt, and the output current is detected by the amplifiers 28 and 29.
The transistor section 1 is controlled to have a constant current by.

FIG. 4 is a diagram showing another embodiment according to the present invention, in the case of a constant voltage power supply. In this figure, the output voltage is detected by the voltage detector 7, and the transistor section 1 is controlled by the amplifiers 28 and 29 so as to maintain a constant voltage.

Note that the arithmetic circuit consisting of a logarithmic converter, an antilog converter, a voltage-current converter, etc. is one example, and
Although this is based on analog calculation, it is also possible to use digital calculation using a counter or the like.

As explained above, in the present invention, the load condition is detected as a function of load resistance that is not affected by load current and voltage, and the output voltage setting value of the thyristor rectifier section is created by calculation. By following this and controlling the output voltage of the thyristor rectifier section, the roughly adjusted output voltage of the thyristor rectifier section is created in an open-loop manner, and a stable voltage with fast transient response is applied to the transistor section, resulting in the following effects.

(1) The thyristor rectifier section quickly responds to large or sudden changes in load resistance and applies an output voltage to the transistor section that is the opposite of the increase or decrease in load voltage. Despite large changes in resistance, the voltage between the collector and emitter of the transistor remains almost constant, reducing the load on the transistor.

(2) Since the load condition is detected as a function of the load resistance, the set value is not affected even if the load voltage or current changes slightly, and even if the load changes suddenly, the voltage or current remains steady. Even if you can't reach it,
The set value immediately indicates the target value and is not easily affected by load disturbances as it continues to maintain the set value proportional to the load resistance.

(3) The feedback system is small and does not include time delay elements (filters, etc.), so there is no reaction from them, and the response can be made that much faster.

(4) If the response is sufficiently fast, for example, even if the load becomes short-circuited, the set value will immediately go to the minimum, and the thyristor rectifier output will also respond accordingly, so the transistor section or an absorber connected in parallel to the transistor section will The capacitor is also economically advantageous because it only needs to bear the energy stored in the capacitor.

(5) The faster the response of the thyristor rectifier section, the better the transient characteristics of the output, and the more the transistor section is always working.

[Brief explanation of drawings]

Figure 1 is a diagram showing a conventional example of a constant current power supply.
Fig. 2 shows a conventional example of a constant voltage power supply, Fig. 3 shows an embodiment of a constant current power supply of the present invention, and Fig. 4 shows an example of a constant voltage power supply of the present invention. It is a figure showing an example. 1...Transistor part, 2...Controller,
3...Thyristor rectifier section, 4...Load, 5...
Current detector, 6...Amplifier, 7...Voltage detector,
8...Filter, 9...Load current detector, 10
... Voltage detector, 11, 12 ... Logarithmic converter, 1
3... True number converter, 14... Resistor, 15... Amplifier, 16... Resistor, 17... Transistor,
18... Voltage-current converter, 19... Variable resistor,
20... Resistor, 21... Constant voltage diode, 2
2...Transistor, 23, 24, 25, 26...
...Resistor, 27...Variable resistor, 28, 29...
amplifier.

Claims (1)

[Claims] 1. A coarse adjustment function section that rectifies and coarsely adjusts an AC voltage, and a controller that controls the coarse adjustment function section so that a detection signal of the DC output voltage of the coarse adjustment function section becomes equal to its output voltage setting signal. ,
In a stabilized power supply equipped with a fine adjustment function section that finely adjusts the DC output from the coarse adjustment function section according to a predetermined reference value, the load voltage and load current are detected and calculated together. Stabilization characterized in that the output voltage setting signal is a signal obtained by amplifying and obtaining a signal proportional to the magnitude of the resistance value of the load, and combining this signal with a signal having a predetermined magnitude. How to control power output.