KR100585684B1 - The power factor improvement and pam control circuit according to supply voltage frequency for inverter system - Google Patents

Abstract

The present invention relates to a power factor improvement and a palm control circuit according to a power supply voltage frequency of an inverter system. In the related art, since an analog power factor improvement unit does not store a waveform of an input voltage, there is a problem of continuously receiving an input voltage. In this case, analog IC is used to improve power factor, but the IC peripheral circuit is very complicated, and the auxiliary winding, etc. requires a very expensive price. There is a problem that it is impossible to make one chip into a computer. Therefore, in the present invention, the rectifying unit 61 rectifies the input AC power to make a DC voltage, the choke coil 62 and the smoothing capacitor 63 for removing the AC component from the DC voltage of the rectifying unit 61, and the flat Inverter 64 for converting the DC voltage output from the utilization capacitor 63 into three-phase AC power and supplying it to the motor M, and a switching element for controlling charging and discharging operations of the smoothing capacitor 63; Q1), a zero voltage detector 65 for detecting a zero point of the input AC power supply, a voltage level detector 67 for detecting a voltage across both ends of the smoothing capacitor 63, and The ROM 66 storing data about a sine wave of an input AC power source, the pulse data of the ROM 66 corresponding to the zero voltage detected by the zero voltage detector 65, and the voltage level detector 67 Multiply the pulse width determination coefficient (FACTOR) according to the detection level The control unit 68 outputs a pulse width in which the power factor control and the palm function are adjusted, and the drive unit 69 controls the on / off operation of the switching element Q1 according to the pulse output from the control unit 68. By implementing the circuit, the sine wave for the input power source is stored in advance in the memory device, so that the circuit can be easily implemented without the need for peripheral circuits, and can be made cheap because it is easy to integrate with a microcomputer.

Description

Power factor improvement and palm control circuit according to the frequency of power supply voltage of inverter system {THE POWER FACTOR IMPROVEMENT AND PAM CONTROL CIRCUIT ACCORDING TO SUPPLY VOLTAGE FREQUENCY FOR INVERTER SYSTEM}

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 detailed view of the power factor improvement and the palm control circuit according to the power supply voltage frequency of the inverter system of the present invention.

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

61: rectifier 62: choke coil

63: smoothing capacitor 64: inverter

65: zero voltage detector 66: ROM

67: voltage level detection unit 68: control unit

69 drive unit 70 power supply voltage frequency determination unit

Q1: switching element

The present invention enables digital power control to adjust the power factor correction and palm function of the inverter system so that a simple circuit can be implemented without the need for peripheral circuits. In particular, by determining the frequency of the input power supply voltage, and by determining the operating frequency of the switching device in accordance with the determined frequency, by reading the frequency commonly stored in the memory device and using the different period, the memory device The power factor improvement and the palm control circuit according to the power supply voltage frequency of the inverter system to reduce the size of the.

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 a commercial AC power input to a DC voltage through a bridge diode, and smoothes an output from the rectifier 11. The three-phase AC power supply is further controlled through the control of the pulse width modulation (PWM) of the DC voltage smoothed through the choke coil 12 and the smoothing capacitor 13, and the choke coil 12 and the smoothing capacitor 13. Inverter 14 is converted to the motor provided to the motor (M) to drive.

Referring to the operation of the inverter system configured as described above with reference to Figure 2, first supplying the AC power having a commercial AC power voltage waveform and a commercial AC power current waveform as shown in Figure 2 to the rectifier 11, the rectifier 11 is The bridge diode is rectified to a DC voltage and output 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 DC voltage input from the smoothing capacitor 13 into the three-phase AC power by the on / off operation of the switching element and provides the motor M to drive the motor M. FIG.

In FIG. 2, 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 one cycle 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, which is shown in the current waveform when the power factor of FIG. same.

Thus, when the power factor in FIG. 2 is 1, an ideal current waveform such as a current waveform is made, and in the advanced countries such as noise reduction and reactive power reduction, the current law as in FIG. 2 is legalized.

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 in this, the rectifier 31 for rectifying the commercial AC power input to the DC voltage through the bridge diode, and smoothing the output in the above The output of the choke coil 32 and the smoothing condenser 33 and the DC voltage smoothed through the choke coil 32 and the smoothing condenser 33 are three-phase alternating current again under the control of the pulse width modulation (PWM). Inverter 36, which is converted into a power source, is provided to the motor M to be driven, and the output voltage of the rectifier 31 and the voltage across the smoothing capacitor 33 are compared with a comparator, multiplexer, NAND gate, and NOA. An analog power factor improving unit 34 for varying the pulse width duty to make the overall input current equal to the voltage by using a gate or the like, and the pulse power duty varied by the analog power factor improving unit 34 to be turned on or off. The power factor correction unit 35 is composed of a switching element Q1 for controlling the charging and discharging operation of the smoothing capacitor 33.

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 C1 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 ⑧ terminal Vcc of the analog power factor improving unit 34 is to be equal to 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, 346, and 349, the multiplexer 347, the NAND gates 343 and 344, the self-stagger 342, and the noah gate 345 shown in FIG. By comparing the voltages and outputting the combined pulses so that the two voltages are the same, as shown in FIG. Output via Vout).

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, so that the switching element Q1 is turned on or off in accordance with the pulse to input the input current. Correct the power factor so that the waveform of the input voltage is the same.

However, as described above, the analog power factor improving unit of the related art does not store the waveform of the input voltage, so there is a problem of continuously receiving the input voltage, and an analog type IC is used to improve the power factor. However, the IC peripheral circuit is very complicated, and there is a problem in terms of price due to the need for auxiliary windings.

An object of the present invention for solving the conventional problems as described above is to store the sine wave for the input power supply voltage in advance in the storage device, so that the circuit is easily implemented without the need for a peripheral circuit. The present invention provides a power factor improvement and a palm control circuit.

Another object of the present invention is to determine whether the input power voltage frequency is 50Hz or 60Hz, and then read the switching frequency stored in the storage device in advance, and output the data of the storage device by varying the period of the read switching frequency. The present invention provides a power factor improvement and a palm control circuit according to a power supply voltage frequency of an inverter system that can be used in common to reduce a table size of a memory device.

The present invention for achieving the above object is a smoothing capacitor for removing the AC component contained in the DC voltage obtained by rectifying the input AC power from the rectifier, and an inverter for converting the DC voltage into a three-phase AC power supply to the motor And a switching element connected in parallel to the front end of the smoothing capacitor to control charging and discharging of the smoothing capacitor, a zero voltage detecting unit detecting a zero point of the commercial AC power supply, and the zero voltage detecting unit. A power supply voltage frequency determining unit for determining an input power supply voltage frequency by measuring the time between the zero point and the zero point detected by the?, A voltage level detecting unit detecting a voltage across the smoothing capacitor, and a zero voltage detecting unit The voltage level is detected by reading from a ROM storing data about a sine wave in advance from the detected zero point. The pulse width is determined by multiplying the data by a pulse width determination coefficient determined in accordance with the level detected by the signal, and the operating frequency of the switching element is determined according to the frequency determined by the power supply voltage frequency determining unit. It characterized in that it comprises a control unit for outputting the pulse in a cycle according to.

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

6 is a detailed view illustrating the power factor improvement and the palm control circuit of the inverter system according to the present invention. As shown in FIG. 6, the rectifying unit 61 rectifies the input AC power to make a DC voltage, and the DC of the rectifying unit 61. The choke coil 62 and the smoothing capacitor 63 for removing the AC component contained in the voltage, and the inverter converting the DC voltage output from the smoothing capacitor 63 back into a three-phase AC power supply to the motor. 64 and a switching element Q1 connected in parallel to the front end of the smoothing capacitor 63 to control the charging and discharging operations of the smoothing capacitor 63 according to a switching signal, and an input commercial AC power source. A zero voltage detector 65 that detects a zero point of the controller and a time between the zero point and the zero point detected by the zero voltage detector 65 to determine whether the input power voltage frequency is 50 Hz or 60 Hz. Power supply voltage main A number determination unit 70, a voltage level detection unit 67 that detects a voltage across the smoothing capacitor 63, a ROM 66 storing data on a sine wave of an input power supply voltage, The sine wave data is read from the corresponding address of the ROM 66 by the zero point detected by the zero voltage detector 65 and multiplied by a pulse width determination coefficient determined according to the level detected by the voltage level detector 67. When outputting a pulse of which the width is adjusted, the control unit 68 to adjust the period according to the frequency determined by the power supply voltage frequency determination unit 70 and to output in accordance with the period output from the control unit 68 The driver 69 controls the on / off operation of the switching element Q1.

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

When a commercial AC power is input, it is received from the rectifying unit 61 and rectified to a DC voltage using a bridge diode and output.

The DC voltage thus output is smoothed by the choke coil 62 and the smoothing capacitor 63, and removes the AC component included in the DC voltage and supplies it to the inverter 64.

Then, the switches of the inverter 64 perform an on / off operation to convert a DC voltage back into a three-phase AC power and supply it to the motor.

Accordingly, the motor starts to drive.

At this time, in order to change the speed of the motor using the inverter 64, the PAM function is adjusted to change the level of the DC voltage supplied to the inverter 64, and power factor control is performed for efficient operation. In this case, the process of adjusting the frequency of the input power supply voltage is performed.

First, a zero point of a commercial AC power input from the zero voltage detection unit 65 is detected and output to the power supply voltage frequency determination unit 70, respectively.

At this time, the memory 66 stores data corresponding to sine waves 0 to 90 degrees synchronized with the zero point.

Therefore, as in analog, the input voltage is not continuously received, but is stored in the ROM 66 in advance, and the stored data is read and used.

Then, the power supply voltage frequency determination unit 70 measures the time between the zero point and the zero point to determine whether the input power supply voltage frequency is 50Hz or 60Hz.

After determining the power supply voltage frequency, the operating frequency of the switching element Q1 is determined and outputted to the controller 68.

In this case, the power supply voltage frequency 50Hz is one cycle greater than 60 Hz, thereby increasing the output time.

When the operating frequency determined by the power supply voltage frequency determination unit 70 is transferred, the controller 68 waits for the zero voltage signal to be input from the zero voltage detection unit 65.

값을 곱한 펄스를 내부 레지스터에 저장한다.After waiting for the zero voltage signal, the zero voltage detector 65 detects a zero point and provides the zero voltage signal to the controller 68. And the pulse width factor

The pulse multiplied by the value is stored in an internal register.

Thereafter, the value stored in the internal register is counted, and a value corresponding to a pulse counted by the driver 69 and a period corresponding to an operating frequency determined by the power supply voltage frequency determination unit 70 are provided.

For example, when the frequency of the power supply voltage is 50 Hz, the pulse output time is longer than 60 Hz.

Then, the driving unit 69 outputs a high signal to the switching element Q1 during the output period while the pulse counted from the control unit 68 is output. This operation is turned on by the value of the internal register of the control unit 68. Turn it on until it is discounted and becomes zero.

Thereafter, after a predetermined time (i.e., 50 s at 20 KHz, which is the operating frequency of the switching element), the controller 68 reads data of +1 address into the address read from the ROM 66.

The read-out value is multiplied by the pulse width determination factor multiplied previously, and the multiplied value is stored in an internal register and then discounted, and the discounted value is outputted to the driver 69.

Subsequent operations repeat the previous operation.

When the sine wave data stored in the ROM 66 reaches 90 °, the address is again set by -1.

When performing the operation as described above, the voltage level detecting unit 67 detects the DC voltage across the both ends of the smoothing capacitor 63 supplied to the inverter 64 and compares it with a preset reference value. The comparison value is provided to the controller 68.

Then, when the zero voltage detection signal is generated from the zero voltage detector 65, the controller 68 accepts the comparison value provided by the voltage level detector 67.

If the comparison value received by the zero voltage detector 65 is greater than or equal to a predetermined value, the value of the pulse width determination coefficient is increased. If it is less than or equal to the predetermined value, the value of the pulse width determination coefficient is reduced.

For example, if the comparison value is greater than or equal to the predetermined value, the value of the pulse width determination coefficient is multiplied by 1.5 to increase the coefficient value. If the comparison value is less than or equal to the predetermined value, the coefficient value is reduced by multiplying the value of the pulse width determination coefficient by 0.1.

As a result, the controller 68 multiplies the sine wave data stored in the ROM 66 by a pulse width determination coefficient according to the voltage level detected by the voltage level detector 67, and transmits a pulse whose pulse width is adjusted to the driver 69. Output

Then, the driver 69 adjusts the voltage supplied to the inverter 64 by performing an on / off operation by the pulse width provided from the controller 68.

In this case, the voltage level detecting unit 67 may detect using an analog / digital converter or may detect using a comparator.

The ROM 66 stores sinusoidal data using 50 Hz and 60 Hz in common, and changes the operating frequency for switching the switching element Q1 every 50 Hz / 60 Hz, thereby reducing the table size of the ROM 66. do.

By the above operation, the power factor (PFC) is controlled and the palm (PAM) function can be performed.

As described above, since the information about the sine wave is stored in the memory device in advance during digital control, it is possible to implement a simple circuit by not requiring a separate peripheral circuit for receiving input voltage feedback.

In addition, by storing the sinusoidal data that can be used in common in the storage device, by using the operating frequency of the switching device for each input power voltage frequency 50Hz / 60Hz to reduce the table size.

As described in detail above, the present invention stores a sine wave for an input power supply in advance in a memory device, so that a circuit can be easily implemented without requiring a peripheral circuit, and sine wave data using 50 Hz and 60 Hz in common for the memory device. By storing the and operating frequency for switching the switching element every 50Hz / 60Hz, there is an effect to reduce the size of the memory element.

Claims (2)

Charging and discharging operation of choke coil and smoothing capacitor which removes AC component from rectified DC voltage of input AC power, inverter which converts the DC voltage into three-phase AC power and supplies it to motor, and smoothing capacitor A switching element for controlling a voltage, a zero voltage detector for detecting a zero point of the input AC power supply, a power supply voltage frequency determination unit for determining an input power voltage frequency by measuring a time between the detected zero points, and supplying to the inverter A voltage level detector for detecting a level of a DC voltage to be input, a ROM storing data about a sine wave of the input AC power supply, pulse data of the ROM corresponding to the detected zero point of the zero voltage detector, and the voltage level detector The pulse width is adjusted by multiplying the pulse width determination coefficient according to the detection level of the circuit. A power supply frequency of the inverter system, characterized in that it comprises a control unit for adjusting and outputting the period of the pulse width according to the number, and a driving unit for controlling the on / off operation of the switching element in accordance with the period output from the control unit. Power factor improvement and farm control circuit The power factor improvement and palm control circuit according to claim 1, wherein the ROM stores sine wave information about 0 to 90 ° commonly used at 50 Hz and 60 Hz.

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