KR20010108737A - Dc link voltage control circuit - Google Patents

Abstract

The present invention relates to a DC link voltage control circuit, comprising: rectification means for rectifying a voltage supplied to an AC power source; First and second charging means for charging the voltage output through the rectifying means; Switching means for causing the first and second charging means to operate as a double voltage charging means for an arbitrary set time when charging the output of the rectifying means to the first and second charging means by inputting a control signal; And control means for outputting a control signal to the switching means.

According to the present invention as described above through the triac control can be used properly mixed with the general rectification method and the double voltage method has an effect that can improve the efficiency and control of the motor.

Description

DC link voltage control circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC link voltage control circuit. In particular, the DC link voltage is controlled by applying the principle of a double voltage circuit to obtain an effect such as phase altitude modulation (PAM) in driving a motor, thereby obtaining higher speed and superior efficiency. And a DC link voltage control circuit.

1 is a view showing the configuration of a double voltage circuit used for driving a conventional motor.

Referring to FIG. 1, a voltage divider circuit used for driving a conventional motor includes a plurality of diodes D1 and D2 (101, 102) connected to one terminal of an AC power supply, and two capacitors C1 and C2 (103, 104) connected in series. The midpoints of the two capacitors C1 and C2 103 and 104 connected in series are connected to the other terminal of the AC power source.

In addition, the DC link voltages across the two capacitors C1 and C2 (103, 104) are configured to be applied to the inverter 105 which drives the motor 106 by being composed of a plurality of transistors and diodes connected in parallel to these transistors. .

Hereinafter, the operation of the conventional double voltage circuit having the configuration as described above will be described in detail.

First, according to the polarity of the AC power supply capacitor C1 (103), the first pass through the D1 101, C1 (103), and the second pass through the C2 (102), D2 (104) C2 104 is to be charged.

In this case, since the AC power charges each capacitor, it has twice the voltage of the normal AC charging of the entire DC Link voltage.

In some countries, a voltage of 110V is used as an AC power source, and thus, the above double voltage method is basically used to use a higher voltage when driving a motor. In the case of such a double voltage method, since each capacitor is charged at a cycle of 60 Hz (cycle of AC power), the charge cycle is reduced in half compared to the conventional method.

2 is a view showing the configuration of a rectifier circuit used for driving a conventional motor.

Referring to FIG. 2, the conventional rectifier circuit includes a full-wave rectifier circuit unit 200 having two terminals of an AC power supply configured with four rectifier diodes 201, 202, 203, and 204, and two capacitors 205, 206 connected in series to the output terminal of the full-wave rectifier circuit unit 200. ) And the DC link voltage across the capacitors 205 and 206 is configured by a plurality of transistors and a diode in which the DC link voltages across the two capacitors C1 and C2 (205 and 206) are connected in parallel to each other to drive the motor 208. It is configured to be applied to the inverter 207.

Hereinafter, the operation of the conventional rectifier circuit having the above configuration will be described in detail with reference to FIG. 2.

The full-wave rectifying circuit unit 200 consisting of the four rectifying diodes is used two during each half cycle of the AC power supply. That is, diodes D1, D3 (201, 203), D2, D4 (202, 204) operate for half a period of AC power, respectively, to charge capacitors C1 (205) and C2 (206).

Therefore, regardless of the polarity of the AC power supply, the capacitors C1 205 and C2 206 are always charged at the same time, and the period becomes 120 Hz for a 60 Hz power supply.

In addition, when using the conventional rectifier circuit having the above configuration, the DC Link voltage is It is doubled. For example, when a 200V AC power is applied, the voltage of the DC link is about 310V.

When using 220V, the DC link voltage is 620V when using the double voltage circuit. However, in such a case, since the voltage rating of the power device must be increased, it is impossible to apply a double voltage method in Korea.

In driving a motor, it is advantageous to have a high DC link voltage. If the applied voltage is low, the rising speed of the current is slowed, so there is a problem that a method such as flux-weakening must be used while losing efficiency when increasing the rotation speed of the motor.

The present invention has been created to solve the above-mentioned problems, DC link voltage control circuit that can improve the efficiency and controllability of the motor by using a combination of the rectification method and the double voltage method through the control of Triac The purpose is to provide.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing the configuration of a double voltage circuit used for driving a conventional motor.

2 is a view showing the configuration of a rectifier circuit used for driving a conventional motor.

3 is a diagram showing a configuration of a DC link voltage control circuit of the present invention.

4A and 4B are views showing a charge path by on and off operations of a triac constituting the DC link voltage control circuit of the present invention.

5 is a view showing a control signal for triac control of the present invention.

6 is a flowchart showing a control process of a triac constituting the DC link control circuit of the present invention.

<Description of Symbols for Major Parts of Drawings>

101,102,201,202,203,204,301,302,303,304 ... diode

103,104,205,206,305,306 ... Capacitor

307 ... Triac 308 ... Micom

DC link voltage control circuit of the present invention for achieving the above object,

Rectifying means for rectifying a voltage supplied to an AC power source;

First and second charging means for charging the voltage output through the rectifying means;

Switching means for causing the first and second charging means to operate as a double voltage charging means for an arbitrary set time when charging the output of the rectifying means to the first and second charging means by inputting a control signal; And

And control means for outputting a control signal to the switching means.

Preferably, the switching means is such that the first and second charging means operate as full-wave rectifying charging means other than the predetermined time.

More preferably, the control signal output from the control means is characterized in that it has a predetermined delay time than the time of the generation of a fixed period interrupt signal of the AC power supply.

3 is a diagram showing the configuration of the DC link voltage control circuit of the present invention, an example of which is applied to driving a motor.

Referring to FIG. 3, the DC link voltage control circuit of the present invention includes a rectifier circuit part 300 including first, second, third, and fourth diodes 301, 302, 303, and 304 connected to both ends of an AC power source, and of the rectifier circuit part 300. Triac 307 connected to the first and second capacitors 305 and 306 connected to an output terminal, and one end thereof to an intermediate point of the first and second capacitors 305 and 306, and the other end connected to one end of the AC power source. And a microcomputer 208 for outputting a control signal to the triac 307.

In addition, the DC link voltages of the first and second capacitors 305 and 306 are configured to be applied to the inverter 309 which drives the motor 310 by being composed of a plurality of transistors and diodes connected in parallel to these transistors. .

4A and 4B are diagrams showing charge paths by on and off operations of the triac 307 constituting the DC link voltage control circuit of the present invention.

Hereinafter, the operation of the DC link voltage control circuit of the present invention will be described in detail with reference to FIGS. 3, 4A, and 4B.

First, FIG. 4A shows a charging pass when the triac 307 is turned off. Since the triac is turned off, the charging is performed in the same manner as the conventional full wave rectification method. In this case, the DC link voltage is 220 V AC. Approximately 310V.

4B shows two paths when the triac 307 is turned on and has the same configuration as a conventional double voltage circuit.

That is, a first pass through the first diode 301, the third diode 303, and the first capacitor 305, the second diode 302, the fourth diode 304, and the like according to the polarity of the AC power source. The first and second capacitors 305 and 306 are charged in two modes of the second pass through the second capacitor 306.

In this case, because the AC power charges each capacitor, it has twice the voltage of the typical AC voltage charge of the entire DC Link voltage.

5 is a view showing a control signal for triac control of the present invention.

Hereinafter, the triac control operation will be described in detail with reference to FIGS. 3 and 5.

If the triac 307 is turned on at the moment when the AC power source is Vt, the charging current flows when the first and second capacitors 305 and 306 are charged at a voltage lower than Vt. In this case, the DC link voltage is 2Vt. On the contrary, when the voltages of the first and second capacitors 305 and 306 are higher than Vt, the diodes are disconnected and thus are not charged.

Therefore, the DC voltage can be controlled depending on which voltage of the AC power supply the control signal of the triac is applied.

Most circuits are receiving a 60Hz interrupt using the Zero Crossing position of the AC supply. This is to measure whether the current power is properly applied. If a predetermined period of delay Dt is given from the interrupt and the triac is controlled by the microcomputer, the control signal shown in FIG. 5 can be applied at a desired moment.

In the present invention, the first and second capacitors are operated as a double voltage charging means or full wave rectifying charging means through the triac control as described above.

6 is a flowchart illustrating a control process of a triac constituting the DC link control circuit of the present invention.

Hereinafter, an operation process of the DC link control circuit of the present invention will be described in detail with reference to FIGS. 3 and 6.

First, when a 60 Hz interrupt signal is generated (step 601), the delay timer (Micro) in the microcomputer 308 is cleared (step 602), and it is determined whether the delay timer has reached a predetermined delay time in the system (step 603). ).

As a result of the determination in step 603, if the delay time determined by the system is reached, a triac control signal is generated (step 604).

At this time, the delay time can be moved according to the DC link voltage desired by the user.

According to the DC link voltage control circuit of the present invention described above, it is possible to use the common rectification method and the double voltage method properly mixed through the triac control, there is an effect that can improve the efficiency and control of the motor.

Claims (4)

Rectifying means for rectifying a voltage supplied to an AC power source; First and second charging means for charging the voltage output through the rectifying means; Switching means for causing the first and second charging means to operate as a double voltage charging means for an arbitrary set time when charging the output of the rectifying means to the first and second charging means by inputting a control signal; And And control means for outputting a control signal to said switching means. The method of claim 1, And said switching means causes said first and second charging means to operate as full-wave rectifying charging means except for said predetermined time. The method of claim 1, The switching device is a DC link voltage control circuit, characterized in that the device capable of bidirectional current control. The method of claim 1, And the control signal output from the control means has a predetermined delay time from a time point at which a predetermined period interrupt signal of an AC power source is generated.