KR890002168Y1 - Drive circuit of using semiconductor devices - Google Patents

Abstract

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Description

Drive Control Circuit of Pulse Width Modulated Chopper Circuit

1 is a power conversion circuit of a pulse width modulation chopper circuit.

2 is a control circuit of a conventional pulse width modulation chopper circuit.

3 is a circuit diagram of the present invention.

4 is a waveform diagram of each part of the circuit diagram of FIG.

5 is a waveform diagram of each part of the present invention circuit diagram.

* Explanation of symbols for main parts of the drawings

CP ₁ -CP ₆ : Comparator B ₁ -B ₃ : Buffer

I ₁ -I ₃ : Inverter N ₁ -N ₃ : NAND Gate

A ₁ , A ₂ : Endgate PC: Photocoupler

T: Trans VR _1- VR ₃ : Variable resistor

C ₁ -C ₃ : Capacitor R ₁ -R ₆ : Resistance

D ₁ -D ₃ : Diode 5: Delayed Square Wave Generator

6: zero crossing square wave generator

7: lead square wave generator

8: base drive 10: pulse width modulated wave generator

20: base drive driving circuit

The present invention relates to a drive control circuit of a pulse width modulated chopper circuit for improving the power factor of an inductive load.

Conventionally, in order to improve the load power factor of the induction motor, the power conversion circuit is configured as shown in FIG. 1 and the control circuit of the pulse width modulation chopper circuit of FIG. 2 is used to drive the digital signal. Because of the phase difference with the voltage, back electromotive force is generated in the power conversion circuit, causing the power conversion element to be destroyed.

The present invention is to provide a drive control circuit capable of driving the power conversion element at the moment when the AC power passes the zero crossing point in view of the above point, and a zero crossing square wave generator having the same output as the phase of the AC power. And the outputs of the lead square wave generation unit that precedes the phase of the AC power source and the delayed square wave generation unit of the phase retardation are configured to control the base drive circuit through the logic element.

This will be described in detail with reference to FIG. 3 as follows.

The third turning a circuit diagram of the subject innovation transformer (T) 2 primary inductance coil (L ₁₎ (L ₂₎ for the variable resistor in the selected phase _{(L 3) (VR 1 -VR} 3) and a condenser (C ₁ -C ₃₎ It is configured to be applied to the comparator (CP ₁ ) (CP ₃ ) (CP ₅ ) to which both power sources (V _CC ) (-V _CC ) are applied, and resistors (R ₁ -R ₆ ) and diodes (D ₁ -D ₃₎ The delayed square wave generator 5, the zero crossing square wave generator 6, and the lead square wave generator 7 are configured to be connected to the comparator CP ₂ (CP ₄ ) (CP ₆ ) through the buffer B _1. -O ₃ connected to the NAND gates (N ₁ -N ₃ ) and the end gates (A ₁ ) (A ₂ ) and the pulse width modulated wave generator 10 through the inverters I ₁ -I ₃ . ₁ ) the control circuit 8 of the power conversion unit is configured and then applied to the base drive 9 through the base drive composition circuit 20 composed of each photocoupler PC, thereby converting the power conversion circuit of FIG. 1) is configured to control.

The power conversion circuit of FIG. 1 configures diodes D ₁₁ -D ₁₄ on the collector side of each transistor Q ₁ -Q ₄ , and then the base side T ₁ -T ₄ of the transistors Q ₁ -Q ₄ . ) Is a state signal applied to the drive to control the drive of the motor (M) connected to the current transformer (CT), and the analog switch (SW) is configured in parallel to the transistor (Q ₁ ) (Q ₂ ) SW) is connected to the output of the microcomputer when the initial power is applied and blocks the initial driving state, and after a few seconds, the analog switch is opened to perform normal operation.

In comparison with the conventional circuit, the current induced by the current transformer CT in FIG. 2 is converted into a constant voltage by the voltage converter 11 of the pulse width modulated wave generator 4 and then the analog digital converter 12. ) Is converted into a constant DC voltage and applied to the reference voltage control unit 13, and the output of the reference voltage control unit 13 is applied to the PWN generation unit 15 through the reference voltage generation unit 14. The modulated wave generated according to the output of is applied to one side of the NAND gates N ₄ -N ₇ of the control circuit 2 of the power converter.

In addition, the control circuit 2 of the power converter has a power source induced to the transformer (T) secondary side to the NAND gate (N ₄ -N ₇ ) through a comparator (CP ₇ ), a resistor (R ₇ ), and a zener diode (ZD). And an output through the inverter I ₇ is applied to the NAND gate N ₅ so that an output signal T ₁ -T ₄ is applied to the power conversion circuit 1 of FIG. The motor M is driven according to the output applied to the base side of Q ₁ -Q ₄ ).

However, in such a circuit, at the time of zero crushing of the AC power source AC, transistors Q ₁ and Q ₂ , which are power conversion elements, are driven and transistors Q ₃ and Q ₄ are driven to operate the motor. Since the current and voltage flowing in the load have a phase difference θ as shown in the waveform diagram AC of FIG. 5, back electromotive force is generated when they cross each other, causing a power conversion element to be destroyed. However, the present invention can prevent the power conversion element from being destroyed in this way. The AC power source AC crosses the zero crossing square wave generator 6, the delayed square wave generator 5, through the secondary side of the transformer T. When applied to the lead square wave generator 7, the zero crossing square wave generator 6 outputs a zero crossing signal in phase with the AC power source AC (FIG. 5 a). ) Outputs a delayed square wave (Fig. 5b) delayed from the phase of the AC power supply (Fig. 5B), and the lead square wave generator 7 outputs a square wave preceding the phase of the AC power supply (θ). C) The phase constants of the variable resistors VR _{1 to} VR ₃ and the capacitor C _{3 of} each of the zero crossing square wave generators 6, the delayed square wave generators 5, and the lead square wave generators 7 possible to obtain a square wave, and a comparator _{(CP 1) (CP 3)} (CP 5) it is yangjeonwon (V _CC) of each circuit - buy (V _CC) To make possible to accurately detect the zero-crossing point, the response speed at the same time to reduce the minimum time, and each resistance (R ₁ -R ₆₎ and diode comparator (CP ₂₎ (CP ₄₎ to (D ₁ -D ₃₎ ( CP ₆ ) is connected so that the zero crossing output is passed so that a negative voltage (-) is not generated at the output side. This output is then passed through the buffers B _1- B ₃ and the buffer inverters I _1- I ₃ of the control circuit 8 of the power converter to the angle ac of FIG. NAND gate (N ₁ ) by outputting a waveform such as) synthesizes the output of the buffer (B ₁ ) and inverter (I ₂ ) output (d in Fig. 5), NAND gate (N ₂ ) is the inverter (I ₁₎ ) And the output of the buffer B ₂ form a synthesized waveform (e of FIG. 5), and the NAND gate N ₃ forms the synthesized waveform of the NAND gate N ₁ (N ₂ ) (f of FIG. 5). ) Is applied to one side of the oragate (OR ₁ ).

The OR gate OR ₁ has an output g obtained by combining the modulated signal PWM of the pulse width modulated wave generator 10 and the output of the NAND gate N ₃ , with the AND gate A ₁ and A ₂ . applied on one side and the buffer (B ₃₎ and an inverter (I ₃₎ and outputs a composite of buffer (B ₂₎ and an inverter (I ₃₎ of claim 5 degrees hk and the output 20 to the base drive driver circuit with the output of The control signal T ₁ -T ₄ is applied to each photo coupler PC and is applied to the transistor base side of FIG. 1 through the base drive 9 to drive the amount of AC power (+). Transistor Q ₂ , a power conversion element that passes the sacrificial power in the section, conducts as early as phase (θ), bypasses the AC power when it passes zero crossing, and negative power (-) section of AC power. in the power conversion device is a transistor (Q ₂₎ of the phase (θ) as a phase difference of voltage and current to the main meurosseo early conduction Which it will be to prevent the AC power supply due to a counter electromotive force which the animation control the power conversion device is destroyed in the zero-crossing point.

As described above, according to the present invention, the power conversion element is destroyed by the phase difference of voltage and current in the load of the induction motor by controlling the power conversion element through the logic element by using the same phase and phase or the same output as the AC power source. There is an effect that can be prevented.

Claims (1)

The positive power supply (V _CC ) () through the variable resistance (VR _1- VR ₃ ) and the capacitor (C ₁ -C ₃ ) for phase selection in the transformer (T) secondary inductance coil (L ₁ ) (L ₂ ) (L ₃ ). -V _CC) the comparator (CP ₁₎ which is applied (CP ₃₎ (a comparator (CP ₂₎ configured to be applied to the CP ₅₎ and resistance (R ₁ -R ₆₎ and via a diode (D ₁ -D ₃₎ ( The delayed square wave generator 5, the zero crossing square wave generator 6, and the lead square wave generator 7 are configured to be connected to the CP ₄ ) (CP ₆ ) to form a buffer B _{1 to} B ₃ and an inverter I _1. The control circuit of the power converter to an oragate (OR ₁ ) connected to the NAND gate (N ₁ -N ₃ ), the end gate (A ₁ ) (A ₂ ), and the pulse width modulated wave generator (10) through -I ₃ ) A drive control circuit of a pulse width modulation type chopper circuit configured to be applied to the base drive 9 through a base drive drive circuit 20 composed of respective photocouplers (PCs) after configuring (8).