KR100339540B1 - Drive control circuit and method of step-up active filter for power factor control - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control circuit and a method of a step-up active filter for power factor control. In the related art, when a periodic cycle of an input voltage is interrupted by a momentary power failure, the voltage of the filter capacitor drops rapidly as the load increases. When power is supplied again in this process, an active filter consisting of a reactor, a diode, and a switching element causes an error to increase with respect to a predetermined target voltage, thereby causing an overcurrent to flow. At this time, if the current exceeds the rating of the switching device there is a problem that the switching device is broken. Accordingly, the present invention provides an active filter driving circuit including a rectifier 21, a boost converter 22, and an inverter 23 and a filter controller 20 for controlling the operation of the boost converter. The first comparison unit for generating an interrupt by comparing the switch unit 31 for intermitting the power supplied to the control unit 20 with the output voltage Vo of the boost converter 22 and a predetermined value α. And a second comparing unit 33 for comparing the output voltage Vo of the boost converter unit 22 with a predetermined value β and outputting a result. As a result of the comparison with the output interrupt signal, it determines the normal operation mode or the instantaneous power failure mode and configures the system driving control unit to control the operation accordingly, so that the safe operation can be performed by preventing the damage of the switching element for power factor control. will be.

Description

Drive Control Circuit and Method of Step-up Active Filter for Power Factor Control

The present invention relates to a drive control circuit and a method of a step-up active filter for power factor control, which can be operated safely even in case of a power failure or an abnormal voltage input. In particular, when the output voltage drops due to an instantaneous power failure or a large voltage drop, The drive control circuit of the step-up active filter for power factor control, which detects this, and when the power is returned after a predetermined time, prevents damage of the switching element for power factor control by operating in the same manner as the initial operation of the system. It is about a method.

FIG. 1 is a block diagram of a drive control circuit of a boost active filter for power factor control. As shown in FIG. 1, the rectifier 11 rectifies an input commercial power and outputs the rectified DC voltage, and the rectifier 11. In the step-up converter unit 12 performing an operation for improving the power factor by the switching signal when the DC voltage is supplied from the motor, and the voltage output from the step-up converter unit 12 to the AC power by the switching drive signal to the motor An inverter current 13 for supplying to M, an input current detector 18 for detecting an input current by detecting a current flowing through the reactor L of the boosted converter 12, and the boosted converter (12) an input voltage detector (17) for detecting a voltage supplied to the reactor (L) to find an input voltage, a current detector (16) for detecting a current flowing through the inverter (13), and the boost type In the capacitor C1 of the converter section 12 The output voltage detection unit 15 detects the voltage and detects the output voltage supplied to the motor M, and the switching for adjusting the power factor using the current and voltage detected by the detection unit 15-18. A control signal processor 14 for outputting a drive signal to the gate of the power factor control switching element Q1 of the boost converter 12, and a system drive for outputting a system drive signal for varying the speed of the motor M; A control unit 20 and an inverter drive unit 19 for outputting a switching control signal for turning on or off the switching element in the inverter unit 13 according to a system drive signal output from the system drive control unit 20. do.

The control signal processor 14 and the detectors 15-18 are the filter controller 10.

Looking at the prior art configured in this way in detail as follows.

When the commercial power is supplied to the rectifier 11, the rectifier 11 rectifies the commercial power using a diode and outputs the rectified voltage to the boost converter 12, wherein the rectified voltage is input power. The voltage comes with a frequency twice the frequency (50/60 Hz).

When the switching element Q1 of the step-up converter section 12 is switched using this voltage, a current in phase with the input voltage flows to the reactor L, and a sign in phase with the input voltage of 50/60 Hz is seen from the commercial power supply. The wave current flows to bring the power factor closer to 1.0.

The reactor L and the diode D and the filter capacitor C1 of the boost converter 12 are filtered to remove the AC component included in the DC voltage of the rectifier 11. ) Is output to the inverter unit 13.

At this time, the output voltage Vo becomes a voltage larger than the peak value of the input voltage.

When the system driving control unit 20 provides a pulse width modulation (PWM) pulse corresponding to a system driving signal for driving the motor M to the inverter driving unit 19, the inverter driving unit 19 corresponds to the PWM pulse. The switching signal is provided to the switching element of the inverter unit 13.

Accordingly, the switching element of the inverter unit 13 performs a switching operation to convert the DC voltage provided from the rectifying unit 11 and the boost type converter unit 12 into an AC power supply to the motor M to control the rotation speed. do.

At this time, the input voltage detector 17 and the input current detector 18 of the filter controller 10 detect the input voltage and the input current supplied from the rectifier 11 to the reactor L of the boost converter 12. Provided to the control signal processor 14, the current detector 16 receives the current through the current transformer (CT) detects the amount of current and provides the detected current value to the control signal processor (14).

The output voltage detector 15 detects a voltage applied to the capacitor C1 of the boost converter 12 and provides the voltage to the control signal processor 14.

Then, the control signal processor 14 generates a switching signal for improving the power factor based on the input voltage and the input current and provides the switching signal to the switching element Q1 of the boost converter 12, and also the inverter unit 13. Control output voltage (Vo) to operate stably at set value.

Since the switching element Q1 operates at a high frequency of 50 KHz or more, the current of the reactor L acts as a current source during each switching.

For example, when the switching element Q1 of the boost converter unit 12 is turned on, the reactor L receives the rectified voltage Vin through the rectifying unit 11, and the reactor current IL increases linearly.

At this time, since the current IQ flowing to the switching element Q1 is bypassed to the (-) side through the conductive switching element Q1, the current ID flowing to the diode D gradually increases.

At this time, the filter capacitor C1 filters the voltage VQ1 supplied from the boost converter 12 and supplies the filtered voltage Vo to a load to operate the filter capacitor C1.

When the switching element Q1 of the boost converter 12 is turned off, the diode D is turned on, and the reactor L is subjected to a (Vo-Vin) voltage, and the reactor current IL is linearly reduced. do.

In this case, power is supplied from the input to the output to charge the filter capacitor C1.

At this time, the current IQ1 flowing to the switching element Q1 gradually rises and then decreases inversely when it exceeds a predetermined value, and maintains the value when the current reaches a predetermined value, and the current ID flowing to the diode D gradually decreases to zero. Keep the value.

By repeating the above operation, the power factor is improved so that the reactor current IL follows the shape of the input voltage.

In this way, the inverter can operate efficiently with a constant inverter input voltage regardless of voltage fluctuations, and its operating power factor is almost 1, and current harmonics can satisfy the international standard (IEC1000-3). .

However, in the prior art as described above, when the cycle of the input voltage is interrupted by a momentary power failure, the voltage of the filter capacitor drops rapidly as the load increases. When power is supplied again in this process, an active filter consisting of a reactor, a diode, and a switching element causes an error to increase with respect to a predetermined target voltage, thereby causing an overcurrent to flow. At this time, if the current exceeds the rating of the switching device there is a problem that the switching device is broken.

Accordingly, an object of the present invention for solving the conventional problems as described above is to immediately detect when the output voltage decreases due to a momentary power failure or a sudden sudden voltage drop, and to start the initial operation when the power is returned after a predetermined time. The present invention provides a drive control circuit and a method of a step-up active filter for power factor control that can operate in the same manner as the situation to prevent breakage of a switching element for power factor control.

Another object of the present invention is to provide a drive control circuit and method for a step-up active filter for power factor control, which prevents damage to a switching device so that a safe operation can be performed.

1 is a configuration diagram of a drive control circuit of a boost active filter for power factor control according to the related art.

2 is a block diagram of a drive control circuit of the boost active filter for power factor control of the present invention;

3 is an input / output waveform diagram of each part in FIG. 2;

4 is a flow chart showing an interrupt routine in FIG.

5 is an operation flowchart of a drive control method of a boost type active filter for power factor control according to the present invention;

*** Explanation of symbols for main parts of drawing ***

20: filter control unit 21: rectifier

22: step-up converter unit 23: inverter unit

24: control signal processor 25: output voltage detector

26: current detector 27: input voltage detector

28: input current detector 29: inverter drive unit

30: system drive control unit 31: switch unit

32: first comparison 33: second comparison

The present invention for achieving the above object is a step-up converter for performing an operation for improving the power factor by a switching signal when supplying a DC voltage from the rectifier for rectifying the commercial power input to the input voltage, and the output voltage of the step-up converter By providing a switching signal for controlling the power factor by detecting the inverter and the inverter to be supplied to the motor by the switching drive signal to the motor, the current and voltage input to the boost converter, and the output voltage of the boost converter. A filter control unit for controlling the output voltage of the boost converter unit to be constant, a system drive control unit for outputting a system driving signal for varying the speed of the motor, and a control signal for controlling the power supply of the filter control unit, and the system driving control unit Switching element in the inverter according to the output system drive signal An inverter driver which outputs a switching control signal for turning on or off, a switch unit which regulates power supplied to the filter control unit according to a control signal output from the system driving control unit, and an output output from the boost converter unit A first comparison unit for generating an interrupt signal to the system driving control unit by comparing a voltage with a predetermined value α, and comparing the output voltage output from the boost type converter unit with a predetermined value β to obtain a result. And a second comparing unit provided to the system driving control unit.

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

2 is a configuration diagram of a drive control circuit of a boost active filter for power factor control according to the present invention. As shown in FIG. 2, the rectifier 21 rectifies the input commercial power and outputs the rectified DC voltage. In step 21, the boost converter unit 22 performs an operation for improving the power factor by the switching signal when the DC voltage is supplied, and the voltage output from the boost converter unit 22 is converted into an AC power supply by a switching drive signal. To control the power factor by detecting the inverter unit 23, the current and voltage input to the boost converter unit 22, and the voltage output from the boost converter unit 22. A filter control unit 20 which provides a switching signal for the boost type converter unit 22 and controls the output voltage of the boost type converter unit 22 to be constant, and a system drive for varying the speed of the motor. Switching in the inverter unit 23 in accordance with a system drive control unit 30 for outputting a control signal for controlling the call and the power of the filter control unit 20, and the system drive signal output from the system drive control unit 30 Inverter driver 29 for outputting a switching control signal for turning on or off the device, and a switch unit for intermitting the power supplied to the filter control unit 20 according to the control signal output from the system drive control unit 30 And a first comparison unit 32 for generating an interrupt signal to the system driving controller 30 by comparing the output voltage Vo output from the boost type converter unit 22 with a predetermined value α. ) And a second comparison unit 33 which compares the output voltage Vo output from the boost type converter unit 22 with a predetermined value β and provides a result to the system driving controller 30. do.

Referring to the operation and effect of the present invention configured as described in detail as follows.

When the commercial power is supplied through the power stage, the rectification unit 21 receives the filtered power and provides the DC voltage obtained by the filtering to the boost type converter unit 22.

At this time, the operation of the boost type converter unit 22 first outputs a pulse width modulation (PWM) pulse for operating the inverter unit 23 when the system driving control unit 30 operates the system to the inverter driving unit 29.

Then, the inverter driver 29 supplies a switching drive signal for turning on or off the switching element of the inverter unit 23 by adjusting the pulse width to the inverter unit 23.

In addition, the system driving controller 30 supplies a high signal to the switch unit 31 so as not to perform the filtering operation.

Then, the transistor Q3 of the switch unit 31 is turned on so that the high potential of the power supply voltage terminal Vcc is bypassed to the ground side through the resistor R3 and the transistor Q3.

Therefore, the low potential signal is applied to the enable terminal (Enable) of the filter control unit 20 through the resistor R4 and the diode D1, so that the filter control unit 20 does not operate.

Then, the switching element Q2 of the boost converter section 22 is turned off.

Therefore, the initial current path is transmitted to the filter capacitor C2 through the reactor L and the diode D of the boost converter 22.

The transmitted current charges the filter capacitor C2 to increase the output voltage Vo and eventually increases to the peak value of the input voltage.

At this time, the system driving controller 30 outputs a low signal to the switch unit 31.

Then, the transistor Q3 of the switch unit 31 is turned off, and a high potential signal is applied to the enable terminal (Enable) of the filter control unit 20 through the resistors R3 and R4 and the diode D1. The filter control unit 20 is in an operable state.

When the filter control unit 20 is in an operable state, the output voltage detection unit 25 detects the output voltage Vo applied to the filter capacitor C2 of the boost type converter unit 22, and the current detection unit 26 The current flowing through the load is detected through the current detector CT between the rectifier 21 and the inverter unit 23, and the input voltage and the current detectors 27 and 28 are reactors of the boost converter unit 22. The input voltage and the input current flowing to L) are respectively detected and provided to the control signal processor 24.

Then, the control signal processing unit 24 supplies a signal for power factor control to the switching element Q2 of the boost type converter unit 22 by the current and voltage transmitted from each detection unit 25-28.

Accordingly, the power factor improving operation starts, and at this moment, since the voltage is already present in the filter capacitor C2 and the charging inrush current does not flow, there is no problem of loss or damage of the switching element.

However, if a momentary power failure or a large sudden drop in input voltage occurs during system operation, the charging energy cannot be transferred to the filter capacitor C2. As shown in FIG. 3B, the output voltage of the filter capacitor C2 ( Vo) is degraded.

This phenomenon decreases rapidly as the operation output increases.

At this time, the first comparison unit 32 and the second comparison unit 33 compare the output voltage Vo with its predetermined comparison value α and β, respectively.

In this case, the output voltage Vo of the filter capacitor C2 maintains a value greater than the comparison reference voltage α of the first comparator 32.

That is, the comparator 32a of the first comparator 32 receives the output voltage Vo of the filter capacitor C2 as the non-inverting terminal (+) and sets the reference set by the resistors R7 and R8. The voltage α is input to the inverting terminal (-) and compared.

As a result of the comparison, when the output voltage Vo of the filter capacitor C2 becomes smaller than the reference voltage α, the comparator 32a outputs a low interrupt signal as shown in FIG. 30 interrupt terminal ( )

The comparator 33a of the second comparison unit 33 receives the output voltage Vo of the filter capacitor C2 as an inverting terminal (−) and sets the reference voltage set by the resistors R12 and R13. (β) is input to each of the non-inverting terminals (+) and compared.

The result to be compared is output to terminal b of the system driving controller 30.

At this time, the system driving control unit 30 receiving the low interrupt signal performs the interrupt routine shown in FIG. 4.

Looking at the execution of the interrupt routine, by outputting a high signal to the switch unit 31 through the output port (a) to cut off the power supplied to the filter control unit 20 to make a disabled state (S41).

Then set a flag bit (DIP flag) to indicate that a momentary power interruption occurred in the main routine (S42).

After that, the timer is operated to determine whether the power is returned within a predetermined time (S43).

When performing such an interrupt routine, the main routine shown in FIG. 5 determines whether the flag bit (DIP flag) is set or reset (S51).

As a result of the determination, when the DIP flag is reset, the normal operation is continued since there is no normal power failure.

If it is set in step S51, it is determined that a momentary power failure has occurred, and in this case, it is determined whether power is input by reading the value of the input port b.

If the value of the input port b read in step S52 is low, the power is not yet restored. At this time, it is determined whether to stop the operation by a power failure or to wait by the timer again (S53).

Like a certain amount of time If the elapsed time has not elapsed, the flow proceeds to step S52 to determine the input level of the input port b. If the elapsed time is passed, it is determined that the power failure has occurred and the processing routine for this is determined.

When the value of the input port b is high in step S52, a low signal is output to the output port a so that the high potential signal is turned on by the switch unit 31. Enable to enable the filter control unit 20 to operate (S54).

In this way, after enabling the filter control unit 20, the timer is stopped (S55), and the flag bit (DIP flag) is reset to perform normal operation.

If the output voltage drops due to momentary power interruption or large voltage drop due to the above operation, it is immediately detected and when the power is returned after a predetermined time, it can operate in the same way as the initial operation of the system. It is possible to prevent damage of the switching element for power factor control, and thus to allow safe operation to proceed.

Therefore, the present invention has the effect of improving the operation reliability by allowing to operate safely even when the input voltage, such as instantaneous power failure, without stopping.

Claims (4)

A boost converter unit comprising a reactor, a switching element, a diode, and a filter capacitor for performing an operation to improve power factor by using a switching element when supplying a DC voltage rectified with an input commercial power, and an output of the boost converter unit. Provides a switching device for controlling the power factor by detecting the input, output current and voltage of the inverter unit and the inverter unit for supplying the motor to the AC power by the switching drive signal to the switching element of the boost converter unit In addition, an active filter driving circuit comprising a filter control unit for regulating the output of the boost converter unit, the switch unit for controlling the power supplied to the filter control unit, and the output voltage of the boost converter unit to a predetermined value ( a first comparison unit for generating an interrupt signal in comparison with?) and the boost converter unit; A second comparison unit comparing the output voltage with a predetermined value β and outputting the comparison result; and controlling the driving of the inverter unit through an inverter driving unit, and an instantaneous power interruption by an interrupt signal output from the first comparing unit. A system driving control unit for controlling the switch unit to determine whether or not to generate power, and to monitor whether the power is returned based on the comparison result output from the second comparing unit and to operate the same as the initial operation start situation when the power is returned after a momentary power failure. And a drive control circuit for a boost type active filter for power factor control. 2. The drive control circuit of a boost active filter for power factor control according to claim 1, wherein predetermined values of the first comparator and the second comparator are configured to establish a relationship of α > In the first step of determining the state of the flag bit, and if the flag bit is in the reset state, it is determined to be in the normal operation mode. A second step of judging; a third step of judging whether to stop the operation due to a power failure or wait through a timer when the power is not restored; and a switch unit when the power is returned in the second step And a fourth step of operating the initial operation and resetting the timer stop and flag bits to proceed to the normal operation mode. The method of claim 3, wherein in the third step, the determination of the interruption and standby states is performed using a predetermined time (time of the timer). ), And if the predetermined time has not elapsed, and proceeds to the step of determining whether to return the power, and if the predetermined time has elapsed to determine the power failure to proceed to the instantaneous power failure mode. A drive control method for a step-up active filter for power factor control, characterized in that made.