JPH02294263A - Phase controlling circuit - Google Patents

Abstract

PURPOSE:To stabilize phase controllability irrespective of input conditions by providing an offset voltage cancelling a specific voltage to be applied to positive input of a subtracting circuit until an input signal reaches a lower value when the input signal having a specific lower value is applied to an input signal circuit and the subtracting circuit. CONSTITUTION:An offset voltage circuit 164 is provided, and positive input potential of an operational amplifier 50 of an internal set circuit 161 is controlled by an offset voltage V2 which is the output of an operational amplifier 67 until a voltage that the output V1 of a buffer circuit 35 is divided by resistors 69 and 70 is in excess of a voltage that a constant voltage (0.8V) equivalent to such as 4mA is divided by resistors 68 and 71. A level of the output V3 which is the positive input of a subtracting circuit 59 is cancelled until current Iin in the event that a current input circuit 19 is used reaches 4mA of the lower value. Accordingly, the output V3 of the subtracting circuit 59 varies 4mA as a starting point by the offset voltage V2, and a threshold level of serrated voltage is properly controlled.

Description

[Detailed Description of the Invention] Field of the Invention This invention relates to a phase control circuit that controls the phase of power supplied to a load using a semiconductor switching element with a gate pole, such as a thyristor or a triac. Prior Art and Problems In general, in phase control circuits,
As shown in the publication, a trigger circuit is driven by a phase angle control pulse obtained from a sawtooth wave voltage synchronized with the zero crossing of the AC power supply voltage and a reference voltage from a human-powered circuit, and a semiconductor for switching loads such as a thalistor is driven. ignites the switching element,
The power supplied to the load is controlled in phase.

However, the conventional one has one human circuit, and 1 f
It is only compatible with ffi input signals and is less versatile. By the way, the phase angle control pulse that determines the firing time of the semiconductor switching element for switching the load is determined by comparing the sawtooth voltage from the sawtooth wave generation circuit and the reference voltage obtained from the human input signal as a threshold level. In other words, by changing the reference voltage level which is a threshold level with respect to the sawtooth voltage, the firing time of the semiconductor switching element is controlled.

When trying to obtain the reference voltage that determines the above threshold level by subtracting a specified voltage from the input signal using a subtraction circuit in the input circuit, the input signal applied to the subtraction circuit usually starts from the specified voltage τ. configured to do so.

However, depending on usage conditions, the input signal may have a predetermined lower limit value, and the threshold level may be changed from this lower limit value. In that case, when the input signal reaches the lower limit value, the output of the subtraction circuit will have fluctuated from the desired value, and the threshold level will also change.
Appropriate phase control becomes impossible.

Purpose of the Invention This invention was made in order to solve the problems of the above-mentioned conventional ones, and it improves the versatility and can be used regardless of the input conditions.
It is an object of the present invention to provide a phase control circuit that can stabilize phase controllability.

Structure and Effects of the Invention The phase control circuit according to the present invention generates a phase angle control pulse from a sawtooth voltage generated in synchronization with the zero crossing of an AC power supply voltage and a reference voltage from an input circuit according to a human input signal. The above human-powered circuit has a trigger current corresponding to the phase angle control pulse that controls the phase of the power supplied to the load by igniting a semiconductor switching element with a gate pole for opening and closing the load using a trigger current corresponding to the phase angle control pulse. A specified voltage variably set by a specified voltage level setting circuit is subtracted from the output of multiple types of input signal circuits having a common voltage generating element and a common buffer circuit of the input signal circuits, and the output is converted into a sawtooth waveform. A subtraction circuit that sends out a reference voltage to the phase control circuit as a reference voltage that determines the threshold level, and when a human power signal with a determined lower limit value is applied, this human power signal is applied to the positive human power of the subtraction circuit until it reaches the lower limit value. It is equipped with an offset voltage that cancels the specified voltage. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an example of a phase control circuit according to the present invention.

In the figure, 1 is a power transformer that steps down the AC power supply voltage to a predetermined value, 2, 3.4 are AC power input terminals on the primary side of the power transformer 10, and 5 is a rectifier circuit connected to the secondary side of the power transformer 1. , for example, a bridge rectifier circuit for full-wave rectification, and 6 a reference voltage circuit connected to the rectifier circuit 5 to create a predetermined voltage to each circuit. 7 is a zero cross detection circuit connected to the output terminal of the bridge rectifier circuit 5; 8 is a sawtooth wave generation/detection circuit connected to the zero cross detection circuit 7 and outputs a sawtooth wave voltage synchronized with the zero cross of the AC power supply voltage. It is. Reference numeral 9 denotes a phase angle control circuit that outputs a phase angle control pulse using the sawtooth wave voltage using the input signal from the input circuit IO as a reference voltage;
1 is a trigger circuit connected to the phase control circuit 9, and is adapted to control the load switching circuit 12. 13
, 14 are a pair of load terminals. The input circuit 10 has an input signal circuit 15 and a specified voltage level setting circuit 16, and the human input signal circuit 15 has a plurality of types of circuits, such as a Uiro main setting circuit 17, a current input circuit 18, and a voltage ON/O FF circuit. It consists of 19 mag.

21. 22 is an input terminal of the external main setting circuit 17; 23.
25 is an input terminal of the voltage ON/OFF circuit 19, 24 is an input terminal of the current input circuit 18, and 21+ and 27 are input terminals of the specified voltage level setting circuit 16.

In the above configuration, the AC power supply voltage shown in FIG. 2(A) is full-wave rectified by the bridge rectifier circuit 5 as shown in FIG. 2(B). This full-wave rectification is compared with a constant voltage E (for example, 1.2V) by a zero-cross detection circuit 7, thereby detecting a zero-cross. That is, the zero-cross detection circuit 7 outputs a detection pulse corresponding to the zero-cross as shown in FIG. 2(C). This zero-cross detection pulse is applied to the sawtooth wave generation/detection circuit 8, thereby creating the sawtooth wave voltage shown in FIG. 2CD).

The phase angle control pulse shown in FIG. 2(D) is outputted from the phase angle control circuit 9 by this sawtooth wave voltage and the input signal V from the human power circuit IO. In response to this pulse, a trigger current shown in FIG. 2(F) is created in the trigger circuit l1. This trigger current ignites a gated semiconductor switching element (not shown) such as a triac in the load switching circuit 12, so that a load current shown in FIG. 2(G) flows through a load (not shown).

Next, a specific configuration of the input circuit IO will be explained with reference to FIG.

In the figure, the external main setting circuit l7 includes, for example, the input terminals 21. 22, a variable resistor 3l, an input resistor 32. 33. Resistor 3 as a voltage generating element
4 and an operational amplifier 35 constituting a buffer circuit.

The current input circuit 18, for example,
Current output 4 of a temperature controller (not shown) connected between
Current input 36, input resistor 37.
38. Protection diode 39. 40, the resistor 34
and the buffer circuit 35 described above.

The voltage/voltage ON/O FF circuit 19 is connected to, for example, the human power terminal 23. 25, a 5-15V DC power supply 41, a switch 42, an input resistor 43, protection diodes 44, 45, and a switching transistor 46. 4
7, consisting of a resistor 48, the resistor 34, the buffer circuit 35, etc. The specified voltage level setting circuit l6 includes an internal setting circuit 16l.
It is composed of an external setting circuit 162, a final output circuit 163, and an offset voltage circuit 164.

The internal setting circuit 161 includes, for example, a variable resistor 49 and an operational amplifier 50, and the external setting circuit 162 includes, for example, the input terminals 26. 27, a variable resistor 51, input resistors 51, 52, and a protective diode 53.
56, a resistor 57, an operational amplifier 58, and the like.

The final output circuit 163 includes a subtractor circuit 59 consisting of an obeamp that subtracts a specified voltage of 4.0, each output of an internal setting circuit 161, and an external setting circuit 182 from the output of the puffer circuit 35 and outputs the result, and resistors 60 to 66. Become,
The output of the subtraction circuit 59 is applied to the negative input of the comparison circuit 9l in the phase angle control circuit 9 to which the sawtooth wave voltage is applied to the positive input.

The offset voltage circuit 164 includes an operational amplifier 67 that compares the output v1 of the buffer circuit 35 with a constant voltage (0.8V), resistors 68 to 72, a diode 73, etc., and the current input value from the current input circuit 18 is Until the lower limit value, for example 4mA is reached, the voltage level setting circuit 16
1,162 is set to cancel the positive input of the subtraction circuit 59.

In the above configuration, the variable resistor 3 of the external main setting circuit 17
By varying the voltage 1, a voltage obtained by dividing the constant voltage 12V is applied to the positive input of the buffer circuit 35, and in response, an output 1 is sent from the buffer circuit 35 to the subtraction circuit of the final output circuit 185. 59 is applied to the negative input. On the other hand, the output 3 of the operational amplifier 50 of the internal setting circuit 161 determined by the variable resistor 49, the output v4 of the operational amplifier 58 of the external setting circuit 162 determined by the variable resistor 51, and the constant voltage 4V are the positive inputs of the subtraction circuit 59. is applied to. The subtraction circuit 59 sends out an output VS obtained by subtracting the constant voltage 4V and the outputs v3 and v4 from the output (1). This output (2) is input to the operational amplifier 91 in the phase angle control circuit 9 as the threshold level of the sawtooth wave voltage.

When using the current input circuit 18, the output of a temperature regulator (not shown) is connected, for example, and a voltage generated in the resistor 34 is applied to the positive input of the buffer circuit 35 according to the current value at that time. That is, the output v1 of the buffer circuit 35 changes depending on the current value.

When performing linear control with voltage input, it is sufficient to apply a DC voltage of 1 to 5 V. In this case, the above 1 to 5 V is applied at 4 to 20 mA.
The resistance values of the resistors 37, 38 and 34 are set so as to be synchronized with the current input. Voltage ON/OFF
When using the F circuit 19, when the switch 42 is turned on, the output ■1 sent out from the operational amplifier 35 according to the voltage divided by the resistor 48 and the resistor 34 is output to the subtraction circuit 59.
is applied to the negative input of . A plurality of types of input signal circuits 17, 18 that share the voltage generation resistor 34. 19 can be used, which improves usability.

By the way, if the offset voltage circuit 164 is not provided,
In the relationship between the set voltage v3 applied to the positive input of the subtracting circuit 59 and the current value, the output (2) of the buffer circuit 35 changes with OmA as the starting point, as shown in FIG. For this reason, the temperature controller's output of 4 to 20 mA is the current input (I
In), at the above-mentioned 4 mA, the output V of the subtraction circuit 59 changes inconsistently for each set value of the set voltage (3). This means that even if controlled at the desired voltage level, a defined threshold level of the sawtooth voltage will not be obtained.

In this regard, if the offset voltage circuit 164 is provided, the voltage obtained by dividing the output vl of the buffer circuit 35 by the resistor 69.70 is a constant voltage (O.a.
V) is the resistor 68. The positive input potential of the operational amplifier 50 of the internal setting circuit 161 is regulated by the offset voltage v2, which is the output of the operational amplifier 67, until it exceeds the voltage divided by 71. That is, until the current Iin when using the current input circuit 19 reaches the lower limit of 4 mA, the level of the output V, which is the positive input of the subtraction circuit 59, is canceled. Therefore, due to the offset voltage (2), the output (2) of the subtraction circuit 59 changes starting from 4m8, and the threshold level of the sawtooth voltage can be appropriately controlled.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the phase control circuit according to the present invention, Figs. 2 (A) to (G) are signal waveform diagrams of each part of the in-phase control circuit, and Fig. 3 is the input of the in-phase control circuit. FIGS. 4 and 5, which show the specific configuration of the circuit, are explanatory diagrams of the operation when the input circuit is not provided with an offset voltage circuit and when the offset voltage circuit is provided, respectively. 7... Zero cross detection circuit, 8... Sawtooth wave generation circuit, 9... Phase angle control circuit, 10... Human power circuit, 1
l...Trigger circuit, 12...Load switching circuit, 16.
...Specified voltage level setting circuit, 17, 18.19...
Human power signal circuit, 34... Voltage generating element, 35... Buffer circuit, 59... Subtraction circuit, 164... Offset voltage circuit. Figure 1 Figure 2 Figure 4 Figure 5 fin (mA)

Claims (1)

[Claims] (1) A phase angle control pulse is created from the sawtooth wave voltage generated in synchronization with the zero crossing of the AC power supply voltage and the reference voltage from the input circuit according to the input signal, and a trigger corresponding to this phase angle control pulse is generated. In a phase control circuit that controls the phase of power supplied to a load by igniting a semiconductor switching element with a gate pole for switching the load using current, the input circuit has multiple types of voltage generating elements having a common voltage generating element at each output terminal. The specified voltage that is variably set by the specified voltage level setting circuit is subtracted from the output of the input signal circuit and the common buffer circuit of the input signal circuit, and the output is used as the reference voltage that determines the threshold level of the sawtooth voltage. When the subtraction circuit sends to the control circuit and the trigger signal with the lower limit value is applied,
A phase control circuit comprising: an offset voltage circuit that cancels a specified voltage applied to a positive input of a subtraction circuit until this signal reaches a lower limit value.