JPH0556530B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a voltage control device that can efficiently control and output a wide range of DC voltages from low voltage to high voltage stably with low ripple. .

[Conventional technology]

For example, in a standard voltage generator or the like that generates a wide range of DC voltages from low to high voltages, it is necessary to control the DC voltages in a highly stable and wide range. As such a voltage control device, conventional series and
Regulator or DC/DC converter systems are known. However, with the series regulator method, it is not possible to obtain an output voltage higher than the driving source. On the other hand, with the DC/DC converter method, it is possible to obtain a voltage higher than that of the driving source, but the ripple is large, the response is slow, and the stability is insufficient for the level required as a standard voltage generator. .

[Problem that the invention seeks to solve]

The present invention has been made in order to solve the above-mentioned problems that conventional devices have, and provides a voltage control device with a simple configuration that can efficiently generate a wide range of DC voltage from low voltage to high voltage at high speed. It is intended to.

[Means for solving problems]

In order to achieve the above object, the present invention includes a series regulator type voltage control circuit having an error amplifier and a DC voltage generation circuit using a DC/DC converter type, and the output of this DC voltage generation circuit is used for driving. DC power supply voltages are added, and the added voltage is taken out as an output voltage via a series regulator transistor controlled by the output of the error amplifier. Examples will be described in detail below.

〔Example〕

FIG. 1 is a connection diagram of an embodiment of a voltage control device according to the present invention. In the figure, VB is a DC power supply (battery) as a driving source, H and L are output terminals that take out the DC output voltage Eo, and there is no load between these terminals.
LO is connected. COP increases its hysteresis.
The comparator eh and Ec indicate the set voltage of this comparator. OSC is square wave pulse fo
G is a gate. The input terminal of the gate G is connected to the comparator COP and the output terminal of the pulse generator OSC. The comparator COP compares the output voltage Eo input to it with the set voltage Ec, and when Eo>Ec, the output is “H”
level, and at this time the square wave pulse fo passes through the gate G. Q1 is a transistor that is turned on and off at the repetition period of the square wave pulse fo that has passed through gate G, and PT is a transformer that boosts the on/off signal. The primary winding n1 of the transformer PT and the transistor Q1 are connected in series, and this series circuit is connected between the output terminals of the DC power supply VB. The transformer PT is connected to one end of the primary winding n1 and the other end of the secondary winding n2 by a connecting wire 1, so that the output of the DC power supply VB is added to the secondary output of the transformer PT. It's summery.

D1 and C1 are the diodes and capacitors that constitute the filter FL, and the secondary winding n2 of the transformer PT.
It is connected to the. Q2 is a transistor for the series regulator, and is connected between the filter FL and the output terminal H. RD is a voltage dividing resistor that divides the output voltage Eo, A1 is an error amplifier, and Er is a variable reference voltage source. The positive side of the reference voltage source Er and the voltage dividing point of the voltage dividing resistor RD are connected to the input terminal of the error amplifier A1, and the output terminal of A1 is connected to the transistor Q2.
connected to the base electrode of. Reference voltage source Er
The negative side of is connected to the output terminal L, which is connected to the common COM. The operation of the device having such a configuration will be explained as follows when the output voltage Eo is controlled below the comparator level (Ec+eh/2) and when the output voltage Eo is controlled above the level.

Regarding the case where the output voltage Eo is controlled below the comparator level.

The pulse generator OSC, transistor Q1, transformer PT, and filter FL constitute a DC-DC converter type DC voltage generation circuit. Here, the output voltage Eo is added to the comparator COP, and the COP compares this voltage Eo with the set voltage Ec, and Eo is the comparator level (Ec + eh/2).
In the following cases, the output level of COP becomes "L", and as a result, the DC-DC converter (DC voltage generation circuit) section does not operate. In this case, the output of DC power supply VB is applied to one end of secondary winding n2 of transformer PT via connection line 1, and then applied to transistor Q2 via diode D1. On the other hand, the output voltage Eo is divided by the voltage division ratio β in an output circuit including a voltage dividing resistor RD, and the divided voltage βEo is applied to the error amplifier A1. The error amplifier A1 detects and amplifies the difference between the reference voltage source Er set to an arbitrary value and the divided voltage βEo, and drives the transistor Q2 so that the difference becomes zero to reduce the direct current applied to this transistor. Controls the output of power supply VB. As a result, a constant voltage is applied between output terminals H and L according to the reference voltage source Er.
Eo is taken as output. That is, in this case, transistor Q2 operates as a series regulator, and therefore the output of battery VB is controlled to a constant value at extremely high speed and with high precision.

Regarding the case where the output voltage Eo is controlled above the comparator level.

When it is desired to obtain a voltage Eo of a magnitude greater than a certain certain value, the reference voltage source Er of the error amplifier A1 is set according to the voltage of the magnitude desired to be extracted.
In that case, when the output voltage Eo is higher than the comparator level (Ec + eh/2) of the comparator COP, the state of the comparator COP is reversed and the output becomes "H" level, and the square wave pulse fo
passes through gate G, turning transistor Q1 on and off. As a result, the DC power supply VB is turned on and off with the repetition period of the square wave pulse fo,
This on/off voltage is boosted by transformer PT and then rectified and filtered by filter FL. Thus, the pulse generator OSC, transistor Q1,
The transformer PT and the filter FL operate as a DC-DC converter, and as a result, a high DC voltage Vh is generated at the output end of the filter FL. The output voltage of the DC power supply VB mentioned above is added to this high voltage Vh, and the sum voltage is applied to the transistor Q2 constituting the series regulator. On the other hand, the error amplifier A1 has an output voltage of
A voltage βEo that is obtained by dividing Eo by a voltage dividing resistor RD is applied, and A1 amplifies the difference between this divided voltage and the reference voltage source Er and applies it to transistor Q2, and transistor Q2 has this difference voltage of zero. (Vh + VB). As a result, the output voltage
Eo is similarly controlled as Eo=(1/β)·Er (1).

Figure 2 shows VB depending on the setting status of the reference voltage source Er.
This is a diagram showing how the voltage of the sum of and Vh and the output voltage Eo change, where A is the setting value of the reference voltage source Er, and B is the sum of the output of the DC power supply VB and the DC/DC converter voltage Vh. Voltage C indicates the output voltage Eo. 0 to S1 and S2 and above on the horizontal axis indicate the above cases, and the range of S1 to S2 indicates the state in the case. Even when the DC/DC converter method is adopted, the series regulator method is also used, so there is less ripple as shown in Figure C.
It can be seen that the control operation is performed with a fast response.

Note that the transition between operation modes → and → is based on the transistor Q that constitutes the series regulator.
Since the two inputs are connected to be (VB+Vh), there is no need to perform any special switching operations, and the transition occurs automatically and continuously. In particular, if the gain of the error amplifier A1 is sufficiently large, the continuity can be maintained sufficiently.

[Effects of the present invention]

For example, as mentioned above, a standard voltage generator stably outputs a desired value of DC voltage from low voltage to high voltage, but it rarely generates high voltage all the time, and in many cases generates low voltage, It is designed to generate high voltage as needed. In the present invention, in a device using a DC power source as a drive source, in a range that can be directly controlled from the drive voltage (i.e., output below the battery voltage, for example), the series regulator method is used without operating the DC/DC converter. The output is controlled most efficiently by operating the voltage control circuit. For example, if a high voltage output higher than the battery voltage is required, a DC high voltage obtained by a DC voltage generation circuit using a DC/DC converter method is added to the battery voltage to generate the voltage. Since the voltage is controlled by the voltage control circuit, a wide range of voltages from low voltage to high voltage can be controlled efficiently and at high speed.
In addition, even when the DC/DC converter system operates, wideband control is performed by the direct-connected loop of the error amplifier and the transistors that make up the series regulator, so the output voltage is sufficiently stabilized, making it possible to use a voltage control device with low ripple. Obtainable.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram of an embodiment of the apparatus according to the present invention, and FIG. 2 is a waveform diagram for explaining the operation of FIG. 1. VB...DC power supply, COP...comparator,
OSC...Pulse generator, PT...Transformer, Q2...
…Series regulator transistor, A1
...Error amplifier, Er...Reference voltage source.

Claims (1)

[Claims] 1. An error amplifier that uses a DC power source as a driving source to amplify the difference between a variable reference voltage and a feedback voltage obtained in response to an output voltage, and controls the output voltage in proportion to the reference voltage. a voltage control circuit having a series regulator transistor; an output of the voltage control circuit as an input to a comparator; and a switch that opens and closes when the input exceeds a set voltage of the comparator to turn on and off the output of the DC power supply; means for rectifying the secondary side output of a step-up transformer whose primary side is connected to the switch and adding the rectified output and the output of the DC power supply; A voltage control device that obtains the output voltage through the series regulator transistor controlled by the output of the error amplifier.