KR100351140B1 - Power factor correction apparatus of inverter - Google Patents

Abstract

The present invention relates to a power factor correcting device for an inverter. In the related art, by using an analog-type power factor improving IC to improve the power factor, a large number of parts are required, so that a peripheral circuit is very complicated, and an auxiliary winding, etc. There was a problem that the cost burden is increased. Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and comprises a commercial AC power supply, a rectifying unit configured to rectify the commercial AC power by a bridge diode and a choke coil, and the output of the rectifying part. And a microcomputer for detecting a zero voltage (zero voltage) of a commercial AC power supply and outputting a pulse width modulated signal having a predetermined pulse width, and a pulse width modulated signal output from the microcomputer. A switching capacitor turned on / off by a smoothing capacitor, a smoothing capacitor for smoothing an output voltage of the rectifying part through a diode according to on / off of the switching element, and a direct current voltage of the smoothing capacitor. Provides a device consisting of an inverter that changes to a variable frequency and variable voltage through modulation (PWM), and a motor driven under the control of the inverter By integration on a micro-computer, thereby reducing the number of parts to simplify the construction of the circuit, without adding a separate device (the secondary windings, and so on) to the choke coil, there is an effect that the cost is reduced.

Description

Power factor correction device for inverters {POWER FACTOR CORRECTION APPARATUS OF INVERTER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power factor correcting device of an inverter, and in particular, an analog type for compensating power factor generated by using a smoothing capacitor having a large capacity due to the characteristics of an inverter used in a refrigerator and a washing machine. The power factor correction apparatus of the inverter which makes it possible to simply correct the power factor by adding a functional circuit to the microcomputer to increase the number of parts and increase the cost burden by using the power factor improvement integrated circuit (IC).

Currently, inverters are being rapidly promoted due to energy saving and ease of output control of home appliances, and washing machines and refrigerators using inverter driving motors have been developed and are coming to the market.

However, due to the characteristics of the device, the inverter first converts a commercial power supply (220V / 60Hz) into a desired voltage and frequency using a switching element, and then a capacitor having a large capacity Needed.

Figure 1 is an exemplary view showing a configuration of a conventional inverter device, a commercial AC power supply 100 as shown therein; A rectifier 110 comprising a bridge diode 111 and a choke coil 112 to rectify the commercial AC power supply 100; A smoothing capacitor 120 for smoothing the output voltage of the rectifier 110; An inverter 130 for converting the DC voltage of the smoothing capacitor 120 into a variable frequency and a variable voltage through a pulse width modulation (PWM); It is composed of a motor 140 driven according to the output power of the inverter 130, Figure 2 is a waveform diagram of the input voltage and current of the inverter device of Figure 1, the time t in the current waveform as shown It is determined by the time constant of the choke coil 112 and the smoothing capacitor 120, and is usually less than 1/5 of the commercial power cycle. In the case of the ideal power factor control, the current waveform has the same phase as the AC voltage and also has a peak current smaller than the maximum size of the commercial power supply. Thus, if the current waveform and the voltage waveform are the same, noise reduction and reactive power reduction are performed. Will bring the effect of.

3 is an exemplary view showing a configuration of an inverter device to which a power factor correction apparatus for conventional power factor correction is applied, and as shown therein, the commercial AC power supply 100 described with reference to FIG. 1; A bridge diode 111; A smoothing capacitor 120; An inverter 130; In the inverter device composed of the motor 140, the choke coil 220, the resistors R1 to R13, the diodes D1 and D2, the capacitors C1 to C3, the analog power factor improving integrated circuits IC and 210, and the switching elements ( Q1) and by varying the duty to switch the duty, further comprising a power factor improving unit 200 to equalize the waveform of the overall input current and voltage, the operation of the conventional device configured as described above is as follows. .

As shown in FIG. 3, the output voltage waveform of the bridge diode 111 has a sine wave form, and the waveform and the current flowing through the switching element Q1 are compared in the form of a sine wave as shown in FIG. 5A. That is, the gate waveform of the switching element Q1 is represented as shown in (b) of FIG. 5 by two input signals MO and CS of the comparator 216 of the power factor improving IC 210 shown in FIG. In the lower part of the switch, the duty is increased, and in the high sine wave, the duty is switched so that the duty is lowered to be equal to the overall input current and input voltage waveform.

As described above, in the conventional technology, by using an analog-type power factor improvement IC to improve the power factor, the number of parts is large, the peripheral circuit is very complicated, and the auxiliary coil or the like is required for the choke coil, thereby increasing the cost burden. There was a problem.

Accordingly, the present invention has been made to solve the above-mentioned problems, and by using a microcomputer to perform the function of the power factor improving IC, to reduce the number of parts and the cost burden, to improve the reliability and productivity It is an object to provide a device.

1 is an exemplary view showing a configuration of a conventional inverter device.

FIG. 2 is a waveform diagram of input voltage and current of the inverter device of FIG. 1. FIG.

3 is an exemplary view showing the configuration of an inverter device to which a power factor correction device for improving power factor in the related art is shown.

4 is an exemplary view showing the configuration of the analog power factor improving IC in FIG.

FIG. 5 is an operational waveform diagram of the analog power factor improving IC of FIG. 3. FIG.

Figure 6 is an exemplary view showing the configuration of the power factor correction device of the inverter of the present invention.

7 is an exemplary view showing input and output waveforms of the microcomputer in FIG.

8 is an exemplary view briefly showing the configuration of a microcomputer in FIG.

*** Description of the symbols for the main parts of the drawings ***

100: commercial AC power supply 110: rectifier

111: bridge diode 112: choke coil

120: smoothing capacitor 130: inverter

140: motor 210: analog power factor improvement IC

217: Mute 218: OP amplifier

300: microcomputer 211,216,219,310: comparator

320: Interrupt Timer 330: Stack Pointer

340: ROM 350,360: Upper and lower registers

370: off-timer 380: on-timer

390: flip flip flop R20 to R23: resistance

The power factor correction device of the inverter of the present invention for achieving the above object comprises a commercial AC power supply; A rectifier comprising a bridge diode and a choke coil to rectify the commercial AC power; A microcomputer that receives the output of the bridge diode of the rectifier through a voltage dividing resistor, detects a zero voltage (zero voltage) of a commercial AC power supply, and outputs a pulse width modulated signal having a predetermined pulse width accordingly. Wow; A switching element connected in parallel to the output of the choke coil and turned on / off by a pulse width modulation signal output from the microcomputer; A smoothing capacitor which receives the output voltage of the rectifying part according to on / off of the switching element through a diode and smoothes it; An inverter for converting the DC voltage of the smoothing capacitor into a variable frequency and a variable voltage through pulse width modulation (PWM); Characterized in that the motor is driven according to the output power of the inverter.

The microcomputer includes: a comparator for receiving the output of the bridge diode through a voltage divider resistor and detecting a zero point of an AC voltage; An interrupt timer for outputting an interrupt signal at regular intervals in synchronization with the reference clock; A stack pointer for specifying an address by an output of the comparator and an output of an interrupt timer; A ROM for outputting data of an address designated by the stack pointer; An upper register configured to receive an upper value among data output from the ROM and determine a pulse width modulation off-time; A lower register configured to receive a lower value among data output from the ROM to determine a pulse width modulation on time; An off-timer that outputs a pulse width modulation off-time value determined by the upper register in synchronization with a reference clock; An on-timer for outputting a pulse width modulation on-time value determined by the lower register in synchronization with a reference clock; And an RS flip-flop for outputting a pulse width modulated waveform according to a value output from the on-timer and off-timer.

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

Figure 6 is an exemplary view showing the configuration of the power factor correction device of the inverter of the present invention, as shown therein commercial AC power supply (100); A rectifier comprising a bridge diode 111 and a choke coil 112 to rectify the commercial AC power supply 100; The output of the bridge diode 111 of the rectifying unit is input through the voltage dividing resistors R20 and R21 to detect a voltage (zero voltage) at the zero point of the commercial AC power supply 100 and accordingly, a predetermined pulse width. A microcomputer 300 for outputting a pulse width modulated signal having a; A switching element Q2 connected in parallel to an output terminal of the choke coil 112 and turned on / off by a pulse width modulation signal output from the microcomputer 300; A smoothing capacitor 120 which receives the output voltage of the rectifying part according to on / off of the switching element Q2 through a diode D10 and smoothes it; An inverter 130 for converting the DC voltage of the smoothing capacitor 120 into a variable frequency and a variable voltage through a pulse width modulation (PWM); It consists of a motor 140 driven according to the output power of the inverter 130.

FIG. 8 is a schematic view showing the configuration of the microcomputer in FIG. 6. As shown in FIG. 6, the output voltage of the bridge diode 111 is input through the voltage divider resistors R20 and R21 to obtain a zero point of the AC voltage. A comparator 310 for detecting; An interrupt timer 320 for outputting an interrupt signal at regular intervals in synchronization with the reference clock; A stack pointer (330) for designating an address by an output of the comparator (310) and an output of an interrupt timer (320); A ROM 340 for outputting data of an address designated by the stack pointer 330; An upper register 350 that receives a higher value among data output from the ROM 340 and determines a pulse width modulation off time; A lower register 360 that receives a lower value among data output from the ROM 340 and determines a pulse width modulation on time; An off-timer 370 for outputting a pulse width modulation off-time value determined by the upper register 350 in synchronization with a reference clock; An on-timer 380 for outputting a pulse width modulation on-time value determined by the lower register 360 in synchronization with a reference clock; The RS flip-flop 390 outputs a pulse width modulated waveform according to values output from the on-timer 380 and the off-timer 370.

Referring to the operation process and effect of the embodiment according to the present invention configured as described above are as follows.

When the output voltage of the bridge diode 111 as shown in FIG. 7A is input to the microcomputer 300 through the voltage divider resistors R20 and R21, the comparator 310 in the microcomputer 300 is connected. 7B detects a zero voltage as shown in FIG. 7B and outputs it to the stack pointer 330, wherein the interrupt timer 320 outputs an interrupt signal at predetermined intervals in synchronization with a reference clock. The stack pointer 330 receives the output of the comparator 310 as a clear signal CLR and receives the output of the interrupt timer 320 as a clock signal CLK to designate an address. The pulse width modulation data of the corresponding address is outputted from the ROM 340, and the pulse width modulation data is divided into an upper value and a lower value and input to the upper and lower registers 350 and 360, respectively.

The upper register 350 receives an upper value and outputs it to the off-timer 370. The lower register 360 receives a lower value and outputs it to the on-timer 380. The on-timer 380 determines the pulse width modulation off-time and the pulse width modulation on-time according to the input upper and lower values, respectively, and outputs the results to the RS flip-flop 390 in synchronization with the reference clock. The flip-flop 390 outputs the load output (pulse width modulated waveform) of the off-timer 370 and the on-timer 380 shown in FIG. 7C to the gate of the switching element Q2, respectively. The switching element Q2 is driven until there is a carry output.

As described above, the power factor correcting device of the inverter of the present invention integrates an analog power factor improving IC into a microcomputer using a digital element that is easy to be one-chip, thereby simplifying the circuit configuration and reducing the number of parts. By not having to add a separate device (such as auxiliary winding) to the choke coil, the cost is reduced, and the reliability and productivity are improved.

Claims (2)

Commercial AC power supply; A rectifier comprising a bridge diode and a choke coil to rectify the commercial AC power; A comparator configured to detect the zero point of the AC voltage by receiving the output of the bridge diode of the rectifier through a voltage divider resistor; An interrupt timer for outputting an interrupt signal at regular intervals in synchronization with the reference clock; A stack pointer for specifying an address by an output of the comparator and an output of an interrupt timer; A ROM for outputting data of an address designated by the stack pointer; An upper register configured to receive an upper value among data output from the ROM and determine a pulse width modulation off-time; A lower register configured to receive a lower value among data output from the ROM to determine a pulse width modulation on time; An off-timer that outputs a pulse width modulation off-time value determined by the upper register in synchronization with a reference clock; An on-timer for outputting a pulse width modulation on-time value determined by the lower register in synchronization with a reference clock; An RS flip-flop for outputting a pulse width modulation signal according to a value output from the on-timer and off-timer; and a pulse-width modulation signal output from the flip-flop connected to an output terminal of the choke coil in parallel; A switching element turned on / off by; A smoothing capacitor which receives the output voltage of the rectifying part according to on / off of the switching element through a diode and smoothes it; An inverter for converting the DC voltage of the smoothing capacitor into a variable frequency and a variable voltage through pulse width modulation (PWM); The power factor correction device of the inverter, characterized in that consisting of a motor driven in accordance with the output power of the inverter. delete