KR20010010408A - The power factor improvement and pulse amplitude modulation control circuit for inverter system - Google Patents

Abstract

PURPOSE: A power factor improvement and pulse amplitude modulation circuit of an inverter system is provided to simply embody a circuit by storing a sine wave with respect to an input power supply in a storage element. CONSTITUTION: A rectifier(61) rectifies an input AC power supply to obtain a DC voltage. A choke coil(62) and a smoothing capacitor(63) remove an AC component included in the DC voltage from rectifier(61). An inverter(64) converts the DC voltage outputted from the smoothing capacitor(63) into a three-phase AC power supply and supplies the three-phase AC power supply to a motor(M). A switching element(Q1) is connected to a front terminal of smoothing capacitor(63) in parallel and controls charge and discharge operations of smoothing capacitor(63) according to a switching signal. A zero voltage detector(65) detects a zero point of an input AC power supply. A voltage level detector(67) detects the voltage across smoothing capacitor(63). A ROM(66) stores data with respect to a sine wave. A controller(68) reads a pulse which corresponds to the detected zero voltage from ROM(66) according to a level of the voltage detected by the voltage level detector(67) and multiplies the pulse from ROM(66) by a predetermined factor to output a pulse width in which a power factor and a pulse amplitude modulation are controlled. A driver(69) controls an on/off operation of the switching element(Q1) according to the pulse from controller(68).

Description

Power Factor Correction and Palm Control Circuit of Inverter System {THE POWER FACTOR IMPROVEMENT AND PULSE AMPLITUDE MODULATION CONTROL CIRCUIT FOR INVERTER SYSTEM}

The present invention relates to a power factor correction and palm control circuit of an inverter system, which enables the power factor correction and palm function of the inverter system to be digitally controlled so that a simple circuit can be implemented without the need for a peripheral circuit. The present invention relates to a power factor improvement and palm control circuit of an inverter system that can be realized at a low price by making microcomputer and ASIC when implemented as a digital circuit.

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, 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, since the IC peripheral circuit is very complicated and requires an auxiliary winding, there is a problem in that it is very expensive in terms of cost, and there is a problem that it is impossible to make an IC into an analog chip by inserting an analog type dedicated IC into a microcomputer.

Accordingly, an object of the present invention for solving the conventional problems as described above is to implement a power factor improvement and palm control circuit of the inverter system that can be made in a digital circuit to make the semiconductor manufacturing process simple and low cost because there is no defect rate In providing.

Another object of the present invention is to provide a power factor improvement and palm control circuit of an inverter system in which a sine wave for an input power source is stored in a memory device in advance, so that a circuit is simply implemented without requiring a peripheral circuit.

It is still another object of the present invention to provide a power factor improvement and palm control circuit of an inverter system that can make a circuit for controlling power factor control and a palm function cheaper because it is easy to integrate with a microcomputer.

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 palm control circuit of the present invention inverter system.

***** 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 Q1 switching element

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 to provide a 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 detector for detecting a zero point of the commercial AC power supply, and the smoothing capacitor. A voltage level detection unit for detecting a voltage across both ends of the signal; and a pulse corresponding to the zero voltage detected by the zero voltage detection unit from a ROM storing data about a sine wave in advance, and detected by the voltage level detection unit. And a controller for multiplying the pulse by a predetermined coefficient according to a level to output a pulse width in which power factor control and palm functions are adjusted. It is characterized by one.

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 which remove the AC component contained in the voltage, and the DC voltage output from the smoothing capacitor 63 are converted into the three-phase AC power to the motor M. A switching element Q1 connected in parallel to the inverter 64 for supplying and the front end of the smoothing capacitor 63 to control charging and discharging operations of the smoothing capacitor 63 according to a switching signal, and A zero voltage detector 65 for detecting a zero point of a commercial AC power supply, a voltage level detector 67 for detecting a voltage across both ends of the smoothing capacitor 63, and data about a sine wave Rom 66 being stored and the zero war The pulse corresponding to the zero voltage detected by the detector 65 is read from the ROM 66 and a predetermined coefficient is applied to the pulse read from the ROM 66 according to the level detected by the voltage level detector 67. The controller 68 outputs a pulse width in which the power factor control and the palm function are adjusted by multiplying the FACTOR, and the driver controlling the on / off operation of the switching element Q1 according to the pulse output from the controller 68. It consists of 69.

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 the DC voltage back into a three-phase AC power and supply it to the motor M. FIG.

Accordingly, the motor M starts to drive.

At this time, to change the level of the DC voltage supplied to the inverter 64 to change the speed of the motor (M) by using the inverter 64, to adjust the palm (PAM) function, the power factor for efficient operation Control is performed, which is performed as follows.

First, a zero point of a commercial AC power input from the zero voltage detector 65 is detected and output to the controller 68.

In this case, data corresponding to sine waves 0 to 90 degrees synchronized with the zero point is stored in the ROM 66, which is a memory element.

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.

Accordingly, when the controller 68 detects and provides a zero point at the zero voltage detector 65, the controller 68 is a data and pulse width determination factor of address '0' from the ROM 68. The pulse multiplied by the value is stored in an internal register.

Then, while counting the value stored in the internal register and outputs the pulse counted to the driver (69).

Then, the driver 69 outputs a high signal to the switching element Q1 while the pulse counted from the controller 68 is output, and turns on the value of the internal register of the controller 68. Turn it on until it reaches 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 above operation, the voltage level detecting unit 67 detects the DC voltage applied across the smoothing capacitor 63 supplied to the inverter 64 and compares it with a preset reference value. One 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 to drive a pulse whose pulse width is adjusted. Will 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.

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

As described above, by controlling digitally instead of analogically, the semiconductor manufacturing process is simple when the digital circuit is implemented and there is no defect rate, so it can be made at a low price.

In addition, since the information on the sine wave is stored in advance in the memory device, a separate circuit for receiving feedback of the input voltage is not required, and thus a simple circuit can be realized.

In addition, the zero voltage detector 65, the ROM 66, the voltage level detector 67, the controller 68, etc., which are made of digital, can be made inexpensively because they can be easily converted to a microcomputer.

As described in detail above, the present invention stores the sine wave for the input power in a memory device in advance, so that the circuit can be easily implemented without the need for a peripheral circuit, and can be made cheap because it is easy to integrate with a microcomputer. It has one effect.

Claims (4)

The rectifier unit rectifies the AC power input to make a DC voltage, the choke coil and the smoothing capacitor to remove the AC component included in the DC voltage of the rectifying unit, and the DC voltage output from the smoothing capacitor to the three-phase alternating current. Zero point of the inverter to convert the power supply to the motor, the switching element connected in parallel to the front end of the smoothing capacitor to control the charging and discharging operation of the smoothing capacitor in accordance with the switching signal, and the commercial AC power input A zero voltage detector for detecting a voltage, a voltage level detector for detecting a voltage across the smoothing capacitor, a ROM storing data about a sine wave in advance, and a zero voltage signal detected by the zero voltage detector. The sine wave data is read from the relevant address from the ROM, and the level detected by the voltage level detector is And a control unit for outputting a pulse whose pulse width is adjusted by multiplying the pulse width determination coefficient determined by the sine wave data, and a driving unit controlling an on / off time of the switching element according to the pulse output from the control unit. Power factor improvement and palm control circuit of inverter system. The power factor improvement and palm control circuit of the inverter system according to claim 1, wherein the voltage level detection unit is implemented as an analog / digital converter. The power factor improvement and palm control circuit of claim 1, wherein the voltage level detector is implemented as a comparator. The power factor improvement and palm control circuit of the inverter system according to claim 1, wherein the ROM stores sine wave data of 0 to 90 degrees.