JPH02299459A - Amplifier - Google Patents

Abstract

PURPOSE:To use AC power to obtain polarity variable DC output with low output impedance by establishing either one of two triac surely in a continuity state, and deciding power phase to establish each triac in a continuity by positive or negative polarity of input signal voltage. CONSTITUTION:AC power 1 is rectified by a rectifier triac 3 inserted in load 6 in series, and it is supplied to the load 6 through an inductance 5. The other triac 4 is so inserted that it is in parallel with the load 6. An ignition control signal 11 having an ignition control characteristic reducing simply from pi to zero of the phase of AC power 1 within the limits of the voltage of an input signal 2 from zero to maximum positive value and an ignition control signal 12 having an ignition control characteristic increasing simply from -pi to zero of the phase of AC power 1 within the limits of the voltage of the input signal 2 from maximum negative voltage to zero are respectively generated.

Description

Detailed Description of the Invention Technical Field The present invention relates to an amplifier, and more particularly, the present invention relates to an amplifier, and in particular, conduction control of a triac inserted in series with a load using a firing angle according to an input voltage, thereby directing the rectified output of an AC power supply to the load. The present invention relates to an amplifier configured to supply power to

Prior Art In a conventional amplifier of this type, the conduction period of a triac connected in series with a load is controlled in accordance with the input voltage. In such conventional amplifiers, the load is connected to the power supply only during the conduction period of one triac connected in series with the load, so the load is in an open state during the rest of the time and the amplifier is in an open state. The disadvantage is that the output impedance is high.

Purpose of the Invention Therefore, the present invention was made to solve the drawbacks of the conventional ones, and its purpose is to obtain a variable polarity DC power supply with low output impedance using an AC power supply. Our goal is to provide an amplifier that can.

Structure of the Invention According to the present invention, the rectified output of the AC power source is supplied to the load by controlling the conduction of the first triac inserted in series with the load using a firing angle according to the input voltage. a second triac connected in parallel to the load; and a point at which the phase of the AC power source monotonically decreases from π to zero for the input voltage from zero to a maximum positive voltage. a first gate control circuit having an arc control characteristic; and a second gate control circuit having a firing control characteristic that increases from 1π to zero in the phase of the AC power source for the input voltage from a negative maximum voltage to zero. a control circuit, wherein a control output of the first gate control circuit is used as a gate control signal for the first triac, and a control output of the second gate control circuit is used as a gate control signal for the second triac. An amplifier characterized by the following can be obtained.

Example Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the invention.

The AC power source 1 is rectified by a rectifying triac 3 inserted in series with a load 6, and is supplied to the load 6 via an inductance 5. Further, another triac 4 is inserted in parallel with the load 6.

On the other hand, the polarity of the input voltage 2 is determined by a polarity determination circuit 7, and if the polarity is positive, it is input to the positive gate control circuit 8, and if it is negative polarity, it is input to the negative gate control circuit 9. The control outputs of both the positive and negative gate control circuits 8.9 are input to the ignition control circuit 10, and a control signal having ignition phase characteristics as shown in FIG. 3 is generated.

That is, in the range of the voltage of the input signal 2 from zero to the maximum positive value, the ignition control signal 11 has an ignition control characteristic that monotonically decreases from π to zero of the phase of the AC power supply 1;
When the voltage of the input signal 2 is in the range from the negative maximum voltage to zero, an ignition control signal 12 having an ignition control characteristic that monotonically increases from -π to zero of the phase of the AC power supply 1 is generated. .

FIG. 2 is a diagram showing the state in which the triac 3.4 is controlled to be conductive by the ignition control signal 11.12 in relation to the phase of the AC power supply 1. In this state, the voltage of input signal 2 ranges from 0 to its maximum positive value.

When the triac 3 is fired at the phase θ in FIG. 2 by the gate control signal, current will flow from the power source 1 through the triac 3 to the load 6 and the triac 4. At this time, the triac 4 is in a conductive state, and current is flowing through the inductance 5 and the load 6, and the current from the power source flows to the load due to the effect of the inductance 5.
The current flowing through the triac 4 is canceled out, and as a result, the triac 4 is extinguished. During the period 11 in FIG. 2, the current from the power supply continues to flow to the load 6.

Next, when the power supply phase passes π (or -π), the triac 3 is turned off and no power is supplied from the power supply.
Due to the effect of the inductance 5, the load current tends to continue flowing in the same direction. At this time, since the triac 4 is brought into conduction by the gate control signal 12 of the triac 4, current continues to flow through the load 6 until the next power supply phase reaches θ.

When the input signal voltage is between the negative maximum value and 0, the polarity judgment circuit 7 gives a human input signal to the negative gate control circuit 9, θ becomes a phase from 1 to 0, and the gate control circuit 10 The period between 0 and 0 is the conduction period of the triac 3. In the other phases, gate control signals are applied to the two triacs so that triac 4 becomes conductive.

As a result, for a negative signal input where θ is between 1π and 0, the additional current flows in the reverse direction.

FIG. 4 shows how the firing period of the triac 3 changes in response to changes in the voltage of the input signal 2. (A
) shows when the input voltage is positive and small, (B) shows when the input voltage is close to the maximum positive value, and (C) shows when the input terminal is negative and small. The load 6 is supplied with an average power proportional to the integral value of the square of the voltage during the conduction period of the triac 3. Then, DC voltages of positive and negative polarities are obtained corresponding to the positive and negative polarities of the input terminal 2.

Since one of the two triacs is controlled so that it is always in a conductive state, the power output to the load is low.

In order to generate the gate control signal having the characteristics shown in Fig. 3, the AC power supply waveform is converted into a rectangular wave by a zero level comparator, and this rectangular wave is integrated by an integrator to form a ramp waveform. generate. Then, this ramp waveform and the voltage level of input signal -2 are compared by a level comparator, and the comparison output is used to obtain a gate firing control signal.

Effects of the Invention According to the present invention, one of the two triacs is always in a conductive state, and the power supply phase in which each triac is conductive is determined by the positive or negative of the input signal voltage.
By using an AC power source, it is possible to obtain DC output with low output impedance and variable polarity.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between the power supply waveform and the conduction period of two triacs,
FIG. 3 is a diagram showing the relationship between the human power signal voltage and the control phase of the triac, and FIGS. 4 (A) to (C) are diagrams showing the relationship between the magnitude of each voltage of the human power signal and the conduction of the triac 3 with respect to the power supply. It is. Explanation of symbols for main parts 1...AC power supply 2...Human signal 3.4...Triac 6...Load

Claims (1)

[Claims] (1) An amplifier that supplies a rectified output of an AC power source to the load by controlling conduction of a first triac inserted in series with the load using a firing angle according to the input voltage. , a second triac connected in parallel to the load, and a second triac having an ignition control characteristic that monotonically decreases from π to zero of the phase of the AC power source for the input voltage from zero to a maximum positive voltage. a second gate control circuit having an ignition control characteristic that increases the phase of the AC power source from −π to zero for the input voltage from a negative maximum voltage to zero; An amplifier characterized in that the control output of the first gate control circuit is used as the gate control signal of the first triac, and the control output of the second gate control circuit is used as the gate control signal of the second triac. .