KR101507412B1 - Power control system linked analog and digital feedback compensation scheme and power control method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control system and a method thereof linked to an analog and digital feedback compensation scheme, A CPU (2); A PWM generator 3; Phase detector 4; A control signal generator 5; SCR (SCR1, SCR2); A load 6; An AC / DC converter 7 (ADC); And a digital display device 8 to present a target value (step S1); A control value generating step (step S2); A duty generation step (S3 step); A reference signal generating step (S4); SCR control signal generation step (S5); An SCR control step (step S6); An analog signal feedback step (step S7); And the digital signal feedback step (step S8), thereby suppressing the generation of harmonics, enabling stable temperature control with high resolution, real-time compensation, which is an advantage of analog feedback, The control amount approaches the target amount, and the advantage of analog feedback and the advantage of digital feedback are combined, thereby remarkably improving the stability of the output and the precision of the target value.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control system and a power control system,

The present invention relates to a power control method, and more particularly, to a power control method in which an analog feedback compensation is combined with a digital feedback compensation to improve the stability of the output voltage, And a digital feedback compensation method, and a method thereof.

Generally, a conventional power control system uses a method of controlling the phase of an input AC voltage by using a SCR (Silicon Controlled Rectifier) device to stabilize the output power.

As shown in FIG. 1, the power control system used in the conventional power control system includes a reaction tube 11 having a tubular shape in which the heat treatment apparatus is made of quartz, (Not shown) that holds a plurality of semiconductor wafers are accommodated in the reaction tube 11 through the heater 12 and the heater 12 composed of the three zone heaters 12a, 12b, Surrounds the side (perimeter). The heating furnace 13 is formed by the reaction tube 11 and the heater 12 and the amount of heat generated by each of the zone heaters 12a, 12b and 12c is supplied to the zone heaters 12a, 12b and 12c And is regulated by a connected power control system.

The power control system is composed of a power transformer 15 of a fixed voltage and a power supply source 14 set on the primary side of the power transformer 15. The power is supplied from the power supply source 14 through the power transformer 15 And the electric power is distributed to the zone heaters 12a, 12b, and 12c. That is, the amount of power supplied to each zone heater 12a, 12b, 12c is controlled by controlling the timing of turning on or off the semiconductor switch in the switching unit 16 set on the secondary side of the power transformer 15, An overcurrent protection device (for example, a fuse) 17a, 17b, 17c is provided between the power transformer 15 and the switching unit 16.

A method of using a phase control SCR (Silicon Controlled Rectifier) for a semiconductor switch in the switching unit 16 and a method of using a zero cross control SCR for a semiconductor switch in the switching unit 16 are known. For example, the former method is used in the case where the heating furnace 13 is a high-temperature elevated-type furnace having a heating rate of about 100 캜 / minute. The latter is used when the heating furnace 13 is a generalization furnace.

In the phase control SCR, the switch switches ON / OFF of the power supply at any timing within one cycle of 360 degrees. Therefore, a high decomposition ability can be obtained. On the other hand, the zero-cross control SCR is a device for switching ON / OFF of the switch at the timing of a zero volt voltage state per cycle. If the power frequency is, for example, 50 Hz, the power supply amount turns on or off the switch for every cycle of the power supply according to class 50 for each cycle. For example, if the switch is turned on for the first cycle, the power is turned off in the second cycle and all the remaining cycles are turned off, so that the amount of power supplied is 2% (100% x 1/50) of the maximum output. If the switch is turned on, then by increasing the cycle of on, the power supply can be increased every 2% (2, 4, 6 ... 100%).

Generally, a heater used in a high-speed heating type has a large change in resistance value with respect to temperature. Therefore, phase control SCR with high resolution is suitable for stable temperature control of the heater. However, this phase control SCR has a problem that large harmonics of a level that can not be ignored are output. Therefore, in the conventional apparatus using the phase control SCR, a large-scale active filter or the like is used in combination to remove the harmonics, resulting in a cost problem due to an expensive harmonic elimination device.

On the other hand, when the zero cross control SCR is used, the harmonics generated in comparison with the case of using the phase control SCR described above are small. However, since the power supply switch controls the turn-on and turn-off of each cycle to adjust the power supply amount, the resolving power of the power supply amount depends on the power frequency, and fine power control can not be performed. Therefore, the zero-cross control SCR is difficult to employ in the heating furnace of the above-mentioned high-temperature elevation type.

Although the phase control SCR is used as described above, when the output form of the analog control elements determines the duty-off duty which is based on the starting point and uses it as the control output, The SCR can not be controlled to the inoperative state until the level of the SCR is reversed. As a result, hardware control using analog feedback is practically impossible, and a phase control method using a microcomputer or the like is implemented. In this case, since compensation according to real-time fluctuation is not performed, it is difficult to stabilize the system due to the real- .

SUMMARY OF THE INVENTION The present invention has been made to solve the various drawbacks and problems caused by the conventional power control system in consideration of the above-mentioned problems, and it is an object of the present invention to suppress generation of harmonics, And a method of controlling the power control system in which the analog and digital feedback compensation methods are combined.

Another object of the present invention is to provide a method and apparatus for compensating a deviation between a measured value and a control value by digital feedback compensation while performing real time compensation which is an advantage of analog feedback, System and method therefor.

It is still another object of the present invention to provide a power control system and a method thereof, which combine the advantages of analog feedback and the advantages of digital feedback to combine analogue and digital feedback compensation schemes that dramatically improve output stability and target value accuracy .

According to an aspect of the present invention, there is provided a power control system including a PLC (Programmable Logic Control) 1 for presenting a target value; A CPU (2) for calculating a target value and a digital feedback value, which are outputs of the PLC (1), as control values; A PWM generator 3 for generating and outputting a duty using a control value and an analog feedback value which are outputs of the CPU 2; A phase detector (4) for detecting the phase of the input AC voltage using a comparison element and outputting the detected phase as a reference signal; A control signal generator 5 for generating an SCR control signal by inputting a reference signal which is an output of the phase detector 4 and an inverse signal of a compensating signal and a compensation signal which are duty of the PWM generator 3; An SCR (SCR1, SCR2) connected to an output terminal of the control signal generator 5; A load 6 connected to the SCRs SCR1 and SCR2 via a transformer T; An AC / DC converter (ADC) 7 for converting an AC analog signal connected to the transformer T into a DC analog signal to provide an analog feedback signal; And a digital display device 8 connected to the load 6 to convert an analog signal inputted thereto into a digital signal and displaying the converted digital signal and providing a digital feedback signal.

The present invention suppresses the generation of harmonics, achieves a stable temperature control with a high decomposition ability, performs real-time compensation which is an advantage of analog feedback, compensates deviation of measured values and control values by digital feedback compensation, And it has a special advantage that the stability of the output and the accuracy of the target value are remarkably improved by combining the advantages of the analog feedback and the advantages of the digital feedback.

1 is a schematic diagram of a conventional power control system,
FIG. 2 is a block diagram of a power control system in which an analogue of the present invention is combined with a digital feedback compensation scheme;
3 is a flow chart of an execution of a power control method in which an analogue of the present invention is combined with a digital feedback compensation scheme,
4 is a flowchart of a compensation process using the digital display device according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a power control system and a method of combining the present invention with a digital feedback compensation scheme will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram of a power control system in which the present invention analogue and a digital feedback compensation method are linked. FIG. 3 is a flow chart of the execution of a power control method in which the present invention analogue is combined with a digital feedback compensation method. As a flowchart of a compensation process using a device, a power control system that combines analog and digital feedback compensation schemes includes a PLC (Programmable Logic Control) 1 for presenting a target value; A CPU (2) for calculating a target value and a digital feedback value, which are outputs of the PLC (1), as control values; A PWM generator 3 for generating and outputting a duty using a control value and an analog feedback value which are outputs of the CPU 2; A phase detector (4) for detecting the phase of the input AC voltage using a comparison element and outputting the detected phase as a reference signal; A control signal generator 5 for generating an SCR control signal by inputting a reference signal which is an output of the phase detector 4 and an inverse signal of a compensating signal and a compensation signal which are duty of the PWM generator 3; An SCR (SCR1, SCR2) connected to an output terminal of the control signal generator 5; A load 6 connected to the SCRs SCR1 and SCR2 via a transformer T; An AC / DC converter (ADC) 7 for converting an AC analog signal connected to the transformer T into a DC analog signal to provide an analog feedback signal; And a digital display device 8 connected to the load 6 to convert the inputted analog signal into a digital signal and display the digital signal and provide a digital feedback signal.

The analog feedback signal which is the output of the AC / DC converter 7 is a SYNC signal and the operational amplifier OP AMP in the PWM generator 3 outputs the control value inputted from the CPU 2 and the analog feedback signal A signal having a duty width and a phase different from that of the signal having the control width (on-duty) converted (hereinafter referred to as "compensation signal"

The control signal generator 5 modifies the output signal of the PWM generator 3 by NOR GATE and transforms the inverse signal of the reference signal and the compensation signal into a logical product.

Meanwhile, a power control method in which the present invention is combined with a digital feedback compensation method includes a target value presenting step (S1 step) of presenting a target value by a programmable logic controller (PLC) 1; A control value generating step (S2) of calculating a target value and a digital feedback value, which are outputs of the PLC (1), to the CPU (2) as control values; A duty generation step (S3) of generating a duty to a PWM generator (3) using a control value and an analog feedback value which are outputs of the CPU (2); A reference signal generating step (S4) of detecting the phase of the input AC voltage with the phase detector (4) using a comparison element and outputting the detected phase as a reference signal; A control signal generator 5 generates an SCR control signal for generating an SCR control signal by inputting a duty signal of the PWM generator 3 and an inverse signal of the compensation signal and a reference signal which is an output of the phase detector 4, (S5); An SCR control step (S6) of controlling the SCR with the output of the control signal generator 5; An analog signal feedback step (S7) of converting an AC analog signal input from the transformer (T) into the AC / DC converter (7) into a DC analog signal and feeding back the analog signal; A digital signal feedback step of converting an analog signal input from the load 6 to the digital display device 8 into a digital signal and displaying the digital signal, and feeding back the digital signal (step S8).

Example

The power supplied to the load was controlled by a power control method in which the analog of the present invention shown in FIG. 3 and FIG. 4 is combined with the digital feedback compensation method.

The target value is presented to the PLC 1 in the target value presenting step S1 and the target value and the digital feedback value output from the PLC 1 are sent to the CPU 2 in the control value generating step S2, And the control value was generated by calculating with the control value.

Subsequently, in the duty generation step (S3), an operation amplifier (OP AMP) in the PWM generation unit 3 generates a duty by a control value output from the CPU 2 and an analog feedback value (SYNC) In the signal generation step (S4), the phase of the input AC voltage is detected by the phase detector 4 using a comparison element and output as a reference signal.

Subsequently, in the SCR control signal generating step (S5), the inverted signal of the compensating signal and the compensation signal, which are the duty of the PWM generating unit 3, is inverted to the NOR gate of the control signal generating unit 5, 4), generates a SCR control signal, and supplies the SCR control signal, which is the output of the control signal generation unit 5, to the CPU 1 (hereinafter referred to as a CPU 2), so that the control duty according to the variation of the load voltage is interlocked in real time and adjusted. Thereafter, an analog feedback signal (alternating voltage) that flows from the load 6 is utilized as a feedback signal of the PWM generation unit 3 by using an AC-to-DC converter 7, If the value is larger than the control value, the control value is set to be reduced. If the feedback amount is smaller than the control value, the control value is reset by adding the control value.

In this way, if analog feedback control is performed, deviation between the target value and the digital display device 8 occurs, and even if the circuit time constant is optimized, it is difficult to reach the target value even if the real-time response is good depending on the surrounding environment. Thus, the deviation from the target value of the CPU 2 is obtained by taking the display data from the digital display device 8 connected to the system load 6 and optimizing the deviation correction value by the program operation of the CPU 2, ), That is, to the PWM generator 3 with the control value. At this time, by applying the differential data according to the deviation amount, if the deviation width is large, a large data change is given in a short time, It is possible to prevent the transient phenomenon or the target value from reaching the target value by applying the control time and width, and also to prevent the excessive change of the analog feedback, thereby preventing the sudden change (see FIG. 4 ).

While the present invention has been described with reference to the preferred embodiments, it is to be understood that the invention is not limited thereto and that various changes and modifications may be made without departing from the scope of the invention.

1: PLC (Programmable Logic Control) 2: CPU (Central Processing Unit)
3: PWM (Pulse Width Modulation) generator
4: phase detector 5: control signal generator
6: load 7: AC / DC converter (ADC)
8: Digital display
SCR1, SCR2: Silicon Controlled Rectifier (SCR)
T: Trans

Claims (4)

A power control system that combines analog and digital feedback compensation schemes includes a programmable logic controller (PLC) 1 for presenting a target value; A CPU (2) for calculating a target value and a digital feedback value, which are outputs of the PLC (1), as control values; A PWM generator 3 for generating and outputting a duty using a control value and an analog feedback value which are outputs of the CPU 2; A phase detector (4) for detecting the phase of the input AC voltage using a comparison element and outputting the detected phase as a reference signal; A control signal generator 5 for generating an SCR control signal by inputting a reference signal which is an output of the phase detector 4 and an inverse signal of a compensating signal and a compensation signal which are duty of the PWM generator 3; An SCR (SCR1, SCR2) connected to an output terminal of the control signal generator 5; A load 6 connected to the SCRs SCR1 and SCR2 via a transformer T; An AC / DC converter (ADC) 7 for converting an AC analog signal connected to the transformer T into a DC analog signal to provide an analog feedback signal; And a digital display device (8) for converting an analog signal inputted to the load (6) into a digital signal for display and providing a digital feedback signal. 2. The semiconductor device according to claim 1, wherein an operational amplifier (OP AMP) in the PWM generator (3) generates a signal having a control width (on duty) converted based on a difference between a control value input from the CPU And generating a signal having a duty width and a phase difference of 180 degrees at a position that is one-half of one-half of a cycle. The control signal generator (5) according to claim 1, wherein the control signal generator (5) modifies the output signal of the PWM generator (3) by NOR gate and transforms the inverse signal of the reference signal and the compensation signal into a logical product And a power control system that combines analog and digital feedback compensation methods. A target value presenting step (S1) of presenting a target value by a PLC (Programmable Logic Control) 1; A control value generating step (S2) of calculating a target value and a digital feedback value, which are outputs of the PLC (1), to the CPU (2) as control values; A duty generation step (S3) of generating a duty to a PWM generator (3) using a control value and an analog feedback value which are outputs of the CPU (2); A reference signal generating step (S4) of detecting the phase of the input AC voltage with the phase detector (4) using a comparison element and outputting the detected phase as a reference signal; A control signal generator 5 generates an SCR control signal for generating an SCR control signal by inputting a duty signal of the PWM generator 3 and an inverse signal of the compensation signal and a reference signal which is an output of the phase detector 4, (S5); An SCR control step (S6) of controlling the SCR with the output of the control signal generator 5; An analog signal feedback step (S7) of converting an AC analog signal input from the transformer (T) into the AC / DC converter (7) into a DC analog signal and feeding back the analog signal; And a digital signal feedback step (S8) for converting an analog signal input from the load (6) to the digital display device (8) into a digital signal for display and feeding back a digital signal The power control method comprising:

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