KR20010010410A - The power factor control apparatus and method - Google Patents

Abstract

PURPOSE: A device and a method for controlling power factor are provided to generate an optimum sine wave when a source voltage frequency or a load is changed and to correct a sine waveform table using an option resistor. CONSTITUTION: A power factor control device comprises a zero voltage detector(21), a power factor control and inverter controller(25), an option resistor(23), a microcomputer(22) and a sub memory(24). The detector(21) detects a zero point of input source voltage and generates interrupt when detected the zero point. The controller(25) controls an inverter driving a motor and controls the voltage to the inverter to execute a power factor control function. The resistor(23) checks the frequency of input source voltage or externally applied operation frequency. The microcomputer(22) senses the interrupt from the detector(21) to decide the source frequency or calculates the size of a sine wave table corresponding to the external operation frequency.

Description

Power factor control device and method {THE POWER FACTOR CONTROL APPARATUS AND METHOD}

The present invention relates to a power factor control apparatus and method for power factor control that can generate the lowest sine wave even when power frequency fluctuations and load fluctuations occur. The present invention relates to a power factor control apparatus and method that can flexibly cope with system control by creating and using a new sine wave table.

Inverters are rapidly being promoted due to energy saving and ease of output control of home appliances.

Washing machines, refrigerators, air conditioners and the like are on the market as home appliances to which a motor driven by the inverter (INVERTER) is applied.

1 is a block diagram of a conventional inverter system. As shown in FIG. 1, the rectifier 11 rectifies the commercial AC power input to a DC voltage through a bridge diode, and the choke coil 12 outputs the smoothed output therefrom. And the smoothing capacitor 13, the choke coil 12 and the smoothing capacitor 13 converts the DC voltage smoothed through the pulse width modulation (PWM) into a three-phase AC power source motor (M). It is composed of an inverter 14 to be provided to drive.

The operation of the inverter system configured as described above will be described based on FIG. 2. First, an AC power source having a commercial AC power voltage waveform as shown in FIG. 2A and a commercial AC power current waveform as shown in FIG. 2B is rectified. ), The rectifier 11 rectifies a DC voltage using a bridge diode and outputs the same to the choke coil 12.

Then, the choke coil 12 and the smoothing capacitor 13 are smoothed to remove the AC component included in the DC voltage of the rectifier 11, and the DC voltage from which the AC component is removed is output to the inverter 14. do.

At this time, the DC voltage input to the inverter 14 becomes a voltage larger than the peak value of the input AC power supply.

Accordingly, the inverter 14 converts the three-phase AC power by the on / off operation of the switching element to the DC voltage input from the smoothing capacitor 13 to provide the motor M to drive the motor.

In FIG. 2 (b), time t is a time determined by the time constants of the choke coil 12 and the smoothing capacitor 13, and is usually 1/5 or less of a commercial AC power supply.

Assuming that the power factor is 1, the current waveform flowing through the inverter is in phase with the commercial AC power input and has a peak current much smaller than the maximum current, as shown in FIG.

Thus, if the ideal current waveform as shown in Fig. 2 (c) is made, the advanced countries such as noise reduction and reactive power reduction are legalized to produce the waveform as shown in Fig. 2 (c).

A power factor correction circuit is used to make a waveform as in FIG. 2 (c), the configuration of which is as shown in FIG.

Figure 3 is a detailed view of the power factor correction circuit of the conventional inverter system, as shown here, the rectifier 31 for rectifying the commercial AC power input to the DC voltage through the bridge diode, and outputs the smoothed output from the above The DC voltage smoothed through the choke coil 32 and the smoothing capacitor 33, and the choke coil 32 and the smoothing capacitor 33 are converted back into three-phase AC power through pulse width modulation (PWM). And a comparator, a multiplexer, a NAND gate, a noah gate, and the like, for the inverter 36 for supplying and driving the motor M, and the output voltage of the rectifier 31 and the voltage across the smoothing capacitor 33. By using the analog power factor improving unit 34 for varying the pulse width duty so that the overall input current and voltage are equal to each other and the pulse width duty varied in the analog power factor improving unit 34. It is composed of a switching element Q1 for controlling the charging and discharging operation of the utilization capacitor 33 and is composed of a power factor correcting unit 35 for correcting the power factor.

The operation of the power factor correction configured as described above will be described with reference to FIGS. 3 and 4.

When a commercial AC power is applied, the rectifier 31 rectifies the DC voltage and outputs the rectified DC voltage.

The DC voltage outputted in this way is input to the terminal ③ VM1 of the analog power factor improving unit 34 by the voltage divided by the resistors R1 and R2 of the power factor correcting unit 35 and the choke coil 32. The induced voltage is input to terminal ⑤ of the analog power factor improving unit 34 through the resistor R5, and the induced voltage of the choke coil 32 is connected to the resistor R4, the diode D1, and the like. The voltage adjusted by the capacitor C3 and the voltage adjusted by the resistor R3 are added, and the added voltage is input to the ⑧ terminal VCC of the analog power factor improving unit 34.

The reason why the input voltage is continuously received through the terminal VCC of the above is to be the same as the waveform of the input voltage during power factor control.

A voltage obtained by dividing the DC voltage of the rectifier 31 through the choke coil 32 and the diode D2 to the inverter 36 by the resistors R11-R13 is the analog power factor improving unit 34. Input voltage is input to the terminal (INV) of ①, and the voltage divided by the time constants of the capacitor (C2) and the resistors (R7, R8) is divided into the terminal (②) of the analog power factor improvement unit 34. A voltage corresponding to the current supplied to the (COMP) and supplied to the inverter 36, that is, the voltage determined by the capacitor C3 is input to the terminal ④.

The input voltage is inputted through the comparators 341, 347, and 349, the multiplexer 347, the NAND gates 343 and 344, the self-stacker 342, and the noah gate 345 shown in FIG. 4 and the output of the inverter 36. The pulses are output by comparing the voltages so that the two voltages are the same. As a result, as shown in (a) and (b) of FIG. Output pulse through ⑦.

The pulse output through terminal ⑦ Vout of the analog power factor improving unit 34 is input to the gate of the switching element Q1, and the switching element Q1 is turned on or off in accordance with the pulse to input the input current and the input. Correct the power factor by making the voltage waveforms the same.

However, in the prior art as described above, when the input power voltage frequency fluctuates (from 50 Hz to 60 Hz, or from 60 Hz to 50 Hz), the sine wave waveform table of the memory device must be modified or, if necessary, the sine wave waveform table. There is a problem that occurs when you need to modify the size of.

Accordingly, an object of the present invention to solve the conventional problems as described above is to provide a power factor control apparatus and method for power factor control to generate an optimal sine wave during power voltage frequency fluctuations and load fluctuations.

Another object of the present invention is to provide a power factor control apparatus and method for power factor control that calculates the size of a sine wave waveform table by using an option resistor when the power supply voltage frequency is changed to modify the size of the table.

Another object of the present invention is to check the power supply voltage frequency, calculate the sine wave waveform table accordingly to be stored in the auxiliary memory device to be used when performing the main program power factor for power factor control to flexibly cope with system control The present invention provides a control apparatus and method.

1 is a block diagram of a general inverter system.

FIG. 2 is an input / output waveform diagram of each part shown in FIG. 1. FIG.

3 is a detailed view of a power factor improvement circuit of the conventional inverter system.

4 is a detailed view of an analog power factor improving unit in FIG. 3.

5 is an input / output waveform diagram of each part in FIG. 4;

Figure 6 is a block diagram for the power factor control device of the present invention.

7 is an operation flowchart for the power factor control method of the present invention.

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

21: zero voltage detector 22: microcomputer

23: optional resistance 24: auxiliary memory

25 power factor control and inverter control unit

The present invention for achieving the above object is to detect the zero point of the input power supply voltage, and to control the inverter to drive the motor by a zero voltage detection unit for generating an interrupt when detecting the zero point, and the output drive signal Power factor control and inverter controller which performs power factor control function, and detects the input interrupt when inputting the interrupt generated by the zero voltage detector to determine whether the power frequency is fluctuated. A microcomputer that sets the size of the wave waveform table, calculates the sine wave waveform table, and stores the calculated sine wave table data, and the sine wave waveform table calculated by the initialization program when the microcomputer is reset upon initial power-up. Remembers that when the main program of the microcomputer It is characterized by including auxiliary storage to read and use the value.

Hereinafter, with reference to the accompanying drawings in detail as follows.

FIG. 6 is a block diagram of the apparatus for controlling the power factor of the present invention. As shown therein, a zero voltage detector 21 for detecting a zero point of an input power supply voltage and generating an interrupt when detecting the zero point, and a motor A power factor control and inverter control unit 25 for controlling the inverter driving the power supply, and controlling the voltage supplied to the inverter to perform the power factor control function, and an operating frequency for checking the input power voltage frequency or arbitrarily setting by the outside. The option resistor 23 to check and the interrupt when the interrupt voltage generated by the zero voltage detector 21 detects the input interrupt to determine the power supply frequency or the operating frequency by external adjustment input through the option resistor 23. A microcomputer 22 for calculating the size of the sine wave table corresponding to the sine wave table and storing the calculated sine wave table data; It is composed of a computer 22. The initial power is on, the initialization program the auxiliary memory 24 to the sine wave waveform memory table and use the values read when executing the main program of the micro computer calculates from the reset on.

7 is an operation flowchart of the power factor control method of the present invention. As shown in the figure, it is determined whether the current waveform and the power factor change by detecting an input frequency and a load size through an interrupt and an option resistor caused by a zero point of the power supply voltage. In the first step, and if there is no current and frequency change according to the load in the first step, the second step to use the previously calculated value as it is, and the change frequency when the current and frequency change according to the load in the first step A third step of setting the size of the sine wave table according to the above-described method, calculating the sine wave waveform, and storing the sine wave table in the sine wave table having the size set above, and the sine wave table storing the sine wave waveform in the third step. It is characterized by consisting of a fourth step to be input to the device to read when needed.

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

When the power supply voltage is input, when the microcomputer 22 outputs a signal for driving the motor driven by the inverter to the power factor control and the inverter controller 25, the power factor control and the inverter controller 25 drives the motor through the inverter. The power factor control function is performed by adjusting the voltage supplied to the inverter.

At this time, when the power frequency is changed, there is a need to modify the sine wave table or modify the size of the sine wave table. In this case, the microcomputer 22 includes a zero voltage detector in order to deal more flexibly. Calculate the size of the sine wave table according to the operating frequency checked through (21) and the option resistor (23), obtain the sine wave waveform to be stored in the calculated sine wave table, and store it in the table. Remember it in 24) and use it.

That is, the zero point of the power supply voltage input from the zero voltage detector 21 is detected, and the zero voltage signal is provided to the interrupt input terminal INT of the microcomputer 22 at the time when this zero point is detected.

Then, the microcomputer 22 senses the input time of the interrupt (S11) and determines whether the power supply voltage is 50Hz or 60Hz (S12).

After determining the frequency of the power supply voltage in this way, the size of the sine wave table suitable for the determined frequency is set (S13).

After the size of the sine wave table is set, the sine wave waveform to be stored in the sine wave table having the set size is calculated and stored in the sine wave table (S14).

The sine wave table storing the sine wave waveform is input to the auxiliary memory 24 (S15).

After the input to the auxiliary memory 24, the microcomputer 22 executes a main program to read and use the data stored in the auxiliary memory 24 when necessary (S16).

If the operation frequency is arbitrarily changed from the outside while performing such an operation, the option resistor 23 detects it and provides it to the microcomputer 22 (S17).

Then, the microcomputer 22 checks whether there is a frequency change by inputting a frequency different from the power source frequency (S18).

As a result of the check, if there is no frequency variation, the process proceeds to step S16 to execute the main program. If there is a frequency variation, the size of the sine wave table is newly set (S19), and the sine wave waveform suitable for the changed frequency is calculated. It is stored in a sine wave table. (S20)

The sine wave table in which the sine wave waveform is stored is input to the auxiliary memory 24 so as to be read from the auxiliary memory 24 if necessary.

For example, the microcomputer 22 detects an interrupt input through its interrupt input terminal INT and stores it in the auxiliary memory 24 when the operating frequency checked and checked by the option resistor 23 is the same. Use the data as it is.

However, when the operating frequency detected by detecting the interrupt input through the interrupt input terminal INT of the microcomputer 22 and the operating frequency checked through the option resistor 23 are different, that is, when there is a frequency variation, the micro The computer 22 calculates the size of the sine wave table according to the operating frequency, calculates the sine wave waveform to be stored in the sine wave table, stores the sine wave waveform in the sine wave table, and stores it in the auxiliary memory 24. Use it when reading.

In this way, the size of the sine wave table and the sine wave waveform according to the frequency of the power supply voltage are calculated, and the calculated sine wave waveform is stored in the sine wave table, stored in the auxiliary memory 24, and used for reading whenever necessary. If the operating frequency adjusted from the outside through the resistor 23 is changed and the power voltage frequency is different, the size of the sine wave table and the sine wave waveform according to the changed frequency are calculated again, and the calculated sine wave waveform is converted into the sine wave table. After the memory is stored in the auxiliary memory 24, it can be stored and used.

In this case, the size of the sine wave waveform and the sine wave table according to the changed frequency through the option resistor 23 is newly calculated and stored in the auxiliary memory 24, and the frequency of the input power supply voltage is changed again. In the same manner, the same operation as in the case of variation through the option resistor 23 is performed to calculate the size of the newly obtained sine wave waveform and the sine wave table, and store the same in the auxiliary memory 24.

As a result, when the operating voltage of the power voltage frequency or the input of the optional function is changed, the size of the sine wave table and the sine wave waveform stored in the sine wave table are varied, and the variable values are input to the auxiliary memory device. If necessary, it can be read from the auxiliary memory and used.

As described in detail above, the present invention changes the size of the sine wave table and the sine wave waveform stored in the sine wave table when the operating voltage through the input of the power supply voltage frequency or the option function is changed, and the variable values are changed. Input to the auxiliary storage device to read from the auxiliary storage device when necessary, it is effective to generate the optimum sign wave even in the case of power frequency fluctuations and load fluctuations, and to cope with the system control more flexibly There is one effect.

Claims (4)

Power factor control and inverter controller for detecting the zero point of the input power supply voltage, and performing a power factor control function by controlling a zero voltage detector for generating an interrupt when the zero point is detected, and an inverter for driving the motor by the output drive signal. And, when the interrupt input generated by the zero voltage detection unit detects the input interrupt to determine whether the power frequency fluctuates, sets the size of the sine wave waveform table corresponding to the fluctuation frequency when the frequency fluctuation, and the sine wave waveform A microcomputer that calculates a table and stores the calculated sine wave table data, and a sine wave waveform table calculated by an initialization program when the initial power is applied to the micro computer are stored. Includes auxiliary storage that reads and uses the value. Power factor control device characterized in that. The power factor control device of claim 1, wherein the auxiliary memory device uses a flash memory. The power factor control apparatus according to claim 1, further comprising an option resistor for distinguishing the type according to the external load to control the power factor of the current waveform which changes according to the load. The first step of determining whether the current waveform and the power factor fluctuate by detecting the input frequency and the load size through the interrupt and the optional resistance caused by the zero point of the power supply voltage, and if there is no current and frequency fluctuation according to the load in the first step In the second step to use the previously calculated value as it is, and in the first step to set the size of the sine wave table according to the fluctuation frequency when the current and the frequency change according to the load, and calculate the sine wave waveform And a fourth step of storing the sine wave table in the set sine wave table, and a fourth step of inputting the sine wave table in which the sine wave waveform is stored in the auxiliary memory device to be read and used when necessary. Power factor control method.