WO2011050551A1

WO2011050551A1 - Dirve circuit for silicon controlled rectifier, device and control method thereof

Info

Publication number: WO2011050551A1
Application number: PCT/CN2009/076211
Authority: WO
Inventors: 姜西辉; 刘建伟; 首召兵
Original assignee: 深圳和而泰智能控制股份有限公司
Priority date: 2009-10-30
Filing date: 2009-12-29
Publication date: 2011-05-05
Also published as: CN101729050B; CN101729050A

Abstract

A drive circuit for a silicon controlled rectifier (SCR), a device with the drive circuit for the SCR and a control method thereof. The drive circuit for the SCR includes a drive unit, the SCR (Q1) controlled by the drive unit, a control unit for providing a drive signal to the drive unit and a direct current (DC) power supply for providing power to the control unit. An alternating current (AC) is full-wave rectified after the alternating current is stepped down by a resistance-capacitance (RC) voltage-reducing circuit, so as to generate the DC power supply. One pin of the control unit is directly connected to an AC input terminal (CN1, CN2) of the full-wave rectification circuit so as to obtain an AC zero-crossing detection signal corresponding to the zero-crossing point of the alternating current. With the RC voltage-reducing circuits provided with the same circuit parameter, a higher load-carrying capability can be obtained with the drive circuit for the SCR than other drive circuits. The circuit parameters of the elements of the RC voltage-reducing circuit can be stepped down for energy saving. The zero-crossing detecting circuit is provided with a simple structure for cost reduction.

Description

Thyristor driving circuit, device and control method thereof

The present invention relates to the field of circuits, and more particularly to a thyristor driving circuit and a control method therefor. Background technique

In the field of existing applications to thyristors, especially in the field of small household appliances, due to cost and volume limitations, RC capacitors are usually used. However, when a RC-capacitor power supply circuit is used, a half-bridge rectified RC-capacitor power supply circuit is usually used to drive the thyristor (because the thyristor driver generally needs to connect the power line L to the VCC). The half bridge circuit can achieve this). The disadvantages of this circuit are: After the 220V AC mains is stepped down by capacitors and resistors, the AC mains supply is only half a cycle effective for supporting the power supply required for the entire control system. Apply the same capacity capacitor. Under the condition, if the full-bridge circuit is used, the load capacity of the power supply will be doubled, so that the capacity and volume of the original capacitor are reduced to half of the original, and the standby power consumption of the entire circuit is also reduced by half; In addition, another disadvantage of the semi-bridge RC power circuit driving the thyristor is that its zero-crossing detection circuit is more complicated and costly. Summary of the invention

The technical problem to be solved by the present invention is to provide a thyristor driving circuit, a device and a control method thereof with strong load capacity and low cost in view of the above-mentioned defects with poor load capacity and high cost in the prior art.

The technical solution adopted by the present invention to solve the technical problem thereof is: constructing a thyristor driving circuit, comprising: a driving unit, a thyristor controlled by the driving unit, a control unit for providing a driving signal to the driving unit, and The control unit provides a DC power source of electric power, and the DC power source is a DC power source obtained by AC voltage through a RC capacitor and full-wave rectification to obtain a DC voltage, and a pin of the control unit is directly connected to the full-wave rectification. An AC input receives the zero crossing detection signal of the AC.

In the thyristor driving circuit of the present invention, the RC capacitor of the DC power source is connected in series The alternating current phase line is located before the full-wave rectified AC phase line input end; the AC zero-crossing detection end of the control unit is connected to the full-wave rectified AC neutral line input end.

In the thyristor driving circuit of the present invention, the control unit comprises a single chip microcomputer or a programmable logic device or a programmable controller or an industrial computer, and the single chip microcomputer or the programmable logic device or the programmable controller or the industrial computer passes Its input/output port is connected to the driving unit and the AC neutral input.

In the thyristor driving circuit of the present invention, the thyristor comprises a unidirectional thyristor or a triac, the driving unit comprises one or two triodes or diodes; the control unit and the The drive unit is connected via one or two output ports.

In the thyristor driving circuit of the present invention, the control unit and the driving unit are connected through an output port, and the driving unit includes a transistor TR1, a transistor TR2, a resistor R4 and a resistor R5, wherein the transistor TR1 is a PNP transistor having an emitter connected to a DC voltage output terminal of the DC power source, a collector connected to a collector of the NPN transistor TR2, an emitter of the transistor TR2 being grounded, and a base of the transistor TR1 and the transistor TR2 After being connected, the resistor R4 is connected to the output port, and one end of the resistor R5 is connected to the thyristor control electrode, and the other end is connected to the collectors of the transistor TR1 and the transistor TR2.

In the thyristor driving circuit of the present invention, the control unit and the driving unit are connected by two output ports, and the driving unit includes a transistor TR1, a transistor TR2, a resistor R4, a resistor R5, and a resistor R6. The transistor TR1 is a PNP transistor having an emitter connected to a DC voltage output terminal of the DC power source, a collector connected to a collector of the NPN transistor TR2, an emitter of the transistor TR2 being grounded, and one end of the resistor R5 Connected to the thyristor control electrode, the other end is connected to the collector of the transistor TR1 and the transistor TR2, the base of the transistor TR1 is connected to an output port through a resistor R4, and the base of the transistor TR2 passes Resistor R6 is connected to another output port.

The invention further relates to a device comprising a thyristor drive circuit, the thyristor drive circuit being the thyristor drive circuit of any of the above.

The invention also relates to a controllable driving method, a thyristor driving method, which is used for resisting the power supply of a buck power supply, comprising the following steps: A) directly connecting a pin of the control unit Connected to an AC input terminal of the full-wave rectification to obtain a zero-crossing signal of the alternating current;

B) obtaining an actual state of the alternating current from the zero-crossing signal of the alternating current, and outputting a corresponding driving signal to the thyristor driving unit according to the actual state of the alternating current to control the conduction of the thyristor.

In the thyristor driving method of the present invention, in the step A), the alternating current state is judged whether the alternating current is in its positive half cycle or in its negative half cycle.

In the thyristor driving method of the present invention, the AC actual state start time is the zero-crossing time of the AC power plus a delay time; and the delay time is related to the device parameters of the resistor-capacitor step-down.

The thyristor driving circuit, the device and the control method thereof embodying the invention have the following beneficial effects: Since the full bridge rectification is adopted in the case of the power supply with the RC voltage reduction, the RC is used in the same parameter. Under the condition, it has strong load capacity, and can reduce the parameters of the RC device and save energy. At the same time, because its zero-crossing detection circuit is relatively simple, its cost is low. DRAWINGS

1 is a circuit diagram of a driving circuit in a first embodiment of a thyristor driving circuit, apparatus, and control method thereof according to the present invention;

2 is a diagram showing a relationship between a zero-crossing signal and an alternating current in the first embodiment;

Figure 3 is a flow chart of the method of the first embodiment;

Figure 4 is a circuit diagram of a second embodiment of the present invention;

Figure 5 is a circuit diagram of a third embodiment of the present invention;

Figure 6 is a circuit diagram of a fourth embodiment of the present invention. detailed description

The embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in FIG. 1, in the first embodiment of the present invention, the thyristor driving circuit includes a driving unit, a thyristor controlled by the driving unit, a control unit that provides a driving signal to the driving unit, and The control unit provides a DC power source of electric power, and the DC power source is a DC power source obtained by AC power through a RC resistor and a full-wave rectification to obtain a DC voltage, and the AC zero-cross detection terminal of the control unit is directly Connected to an AC input of the full-wave rectification. The RC capacitor of the DC power source is connected in series on the AC line, which is located before the full-wave rectified AC phase line input. The AC zero-crossing detection terminal of the control unit is connected to the full-wave rectified AC neutral input terminal. Specifically, the alternating current is input by two alternating current input terminals CN1 and CN2, and the load LOAD is connected in series with the switching end of the thyristor Q1, and is connected to the two alternating current input terminals CN1 and CN2. The phase end of the AC input (ie CN1) is connected to an AC terminal of the bridge rectifier through the fuse FUSE and the RC, and the neutral terminal of the AC input (ie CN2) is directly connected to the other of the bridge rectifiers. At the AC end, the DC voltage outputted from the DC terminal of the bridge rectifier is stabilized and filtered to obtain a DC power supply voltage. In the first embodiment of the present invention, the control unit is a single chip microcomputer, and is connected to external components through its I/O interface, such as the above-mentioned driving unit and the AC neutral terminal. Of course, in other embodiments, the control unit may not be a single chip microcomputer, and may be, for example, a programmable logic device (PLD), a programmable controller (PLC), an industrial computer, or the like. Although the MCU has some shortcomings, it is low in cost, flexible in use, and has a short development cycle.

In the first embodiment, the control unit and the driving unit are connected by an output port including a transistor TR1, a transistor TR2, a resistor R4 and a resistor R5, and the transistor TR1 is a PNP transistor and an emitter thereof. Connected to the DC voltage output terminal of the DC power source, the collector is connected to the collector of the NPN transistor TR2, the emitter of the transistor TR2 is grounded, and the base of the transistor TR transistor TR2 is connected and passed through the resistor R4 is connected to the output port, and one end of the resistor R5 is connected to the thyristor control electrode, and the other end is connected to the collectors of the transistor TR1 and the transistor TR2.

In FIG. 1, when the voltage of CN1 is higher than the voltage of CN2, it is the positive half cycle of the AC mains, and vice versa. When the mains input is half a week, the current flows from the AC phase line terminal CN1 through the fuse FUSE, the capacitor Cl, the resistor Rl, the rectifier diode Dl, the Zener diode Z1 and the rectifier diode D4 back to the AC neutral terminal CN2. At this time, the rectifier diode D4 has a cathode breaking voltage of -0.7 V (relative to the ground of the control system). When the mains input is negative for half a cycle, the current flows from the AC neutral terminal CN2 through D2, Zl, D3, Rl, CI, and FUSE back to the AC phase line terminal CN1. At this time, the cathode voltage of D4 is VCC+0. 7V, that is, It is said that the cathode voltage waveform of D4 is a square wave of the same frequency as the commercial power, the positive half cycle is -0.7, and the negative half cycle is VCC+0.70V. In this embodiment, it is the use of this point to realize the thyristor. Driven under the full bridge. When the mains is being input for half a week, 1/01 output low level (the output of 1/01 is controlled by the MCU through software), the transistor TR1 is turned on, because the cathode voltage of D4 is -0.7V (the same voltage as CN2), so the thyristor Q1 The driving current is returned to CN2 through VCC through TR1, R5 and Q1, so that Q1 is turned on. When the mains input is negative for half a cycle, 1/01 outputs a high level, and the transistor TR2 is turned on. Since the cathode voltage of D4 is VCC at this time. +O.7V (same voltage as CN2), so the drive current of thyristor Q1 is turned on by CN2 through Ql, R5 and TR2 and to the ground of the system, so that Q1 is turned on. In addition, in Figure 1, the cathode of diode D4 is directly connected to the 1/02 port of the MCU, and the other functions of the rectifier diodes D2 and D4 are clamped to protect the 1/02 port of the MCU, so the rectifier diode D4 can be directly connected. The cathode is connected to the 1/02 of the single-chip microcomputer and used to detect the positive and negative half-cycle inputs of the mains. Its function is equivalent to the zero-crossing detection circuit. It can be seen that in this embodiment, no need for any power supply circuit. Other devices can achieve zero-crossing detection, which is much less expensive than existing zero-crossing detection circuits. When 1/02 detects positive half-cycle input, if it needs to turn on Q1 at this time, the MCU will output low level to 1/01 to make Q1 turn on. When 1/02 detects that the mains supply is negative half-cycle input, if At this time, it is necessary to turn on Q1, and the MCU outputs a high level to 1/01 to make Q1 turn on. No matter whether the mains is positive half-cycle input or negative half-cycle input, if it is not required to turn on Q1, it will be 1/1 of the MCU. 01 is placed in a high-impedance state, so that TR1 and TR2 are not turned on, thus achieving the purpose of turning off Q1.

In actual use, due to the presence of capacitors Cl, C2 and C3, the zero-crossing signal at 1/02 leads the AC mains for a certain time. In this embodiment, the lead time is 3.3mS, as shown in Figure 2. Diagram of zero-crossing signals and AC mains. As can be seen from Figure 2, when the zero-crossing signal starts to change to a low level (the microcontroller thinks that the positive half-cycle is detected), in fact, the commercial power is not half a week, and it needs to go through the above-mentioned advanced time to exchange the mains. In the positive half cycle, in the present embodiment, this lead time is 3.3 mS; in the case of the negative half cycle of the alternating current, as in the case of the positive half cycle described above, the alternating current also lags the above-mentioned zero-cross detection signal by 3.3 mS.

FIG. 3 is a flow chart showing the control of the thyristor in the embodiment. In FIG. 3, the flow control is for the thyristor all-conduction. When the 斩 waveguide is required, it is assumed that the chopper is required. The conduction angle is τ. It is only necessary to define T>3.3+TmS in the flow shown in Figure 3, so that the waveguide can be realized and applied to products that need to adjust power or speed. However, it should be noted that the range of τ can only be 0-6.7mS selection (this is due to the zero-crossing signal leading, the reason is not detailed); When a large conduction angle is required (0-10mS), It is necessary to reduce the voltage across the load, so it can be compensated by loss of wave, that is, when a large conduction angle is required, the utility power of a certain cycle or half cycle is turned off to reduce the voltage applied to both ends of the load. .

In the method of this embodiment in FIG. 3, the following steps are included:

Step S11 Main program: In this step, the MCU executes its main program, which is no different from other MCUs for control purposes.

Step S12: Is it necessary to turn on Q1? It is judged whether or not the thyristor Q1 is required to be turned on, and if necessary, step S14 is performed; otherwise, step S13 is performed.

Step S13 sets the port 1/01 to a high-impedance state to turn off Q1: In this step, since it is determined that the thyristor Q1 does not need to be turned on, the driving circuit of the thyristor Q1 is connected in this embodiment. Setting the input/output port 1/01 to the high-impedance state causes the thyristor Q1 to be turned off, and returns to step S11.

Step S14 is half a week? In this step, since it is determined that the control thyristor Q1 needs to be turned on, the current state of the alternating current is determined, that is, whether it is in the positive half cycle, and if so, step S15 is performed; if not, it is judged to be in the negative half cycle. Step S18 is performed.

Step S15 Timing T: In this step, the counter in the microcontroller is started to start timing.

Step S16 T>3.3mS? Determine whether the timing exceeds 3.3mS. If not, return to step S15 and continue counting; otherwise, execute step S17.

Step S17 outputs 1lm port lmS low-level pulse to make Q1 turn on: In this step, the single-chip microcomputer outputs a low-level pulse on the input/output port 1/01, and the pulse duration is lmS, so that the thyristor Q1 is turned on during the positive half cycle of the alternating current, and then returns to step S14.

Step S18 Timing T: In this step, the counter in the microcontroller is started to start timing.

Step S19 T>3.3mS? Determine whether the timing exceeds 3.3mS. If not, return to step S18 and continue counting; otherwise, execute step S20.

Step S20 outputs a 1 m port lmS high-level pulse to turn on Q1: In this step, the MCU outputs a high-level pulse on the input/output port 1/01, and the pulse duration is lmS, so that the thyristor Q1 is turned on within a negative half cycle of the alternating current, and then returns to step S14.

In the first embodiment, there is further provided a device comprising a thyristor drive circuit, which is exactly the thyristor drive circuit previously described.

4 is a circuit diagram of a thyristor driving circuit according to a second embodiment of the present invention, and the second embodiment is in a single piece The scheme adopted when the I/O port of the machine cannot be placed in a high-impedance state. In the second embodiment, the control unit and the driving unit are connected by two output ports, and the driving unit includes a transistor TR1, a transistor TR2, a resistor R4, a resistor R5 and a resistor R6, and the transistor TR1 is a PNP transistor. The emitter is connected to the DC voltage output end of the DC power source, the collector is connected to the collector of the NPN transistor TR2, the emitter of the transistor TR2 is grounded, and one end of the resistor R5 is connected to the controllable On the silicon gate, the other end is connected to the collectors of the transistor TR1 and the transistor TR2, the base of the transistor TR1 is connected to an output port through a resistor R4, and the base of the transistor TR2 is output through the resistor R6 and the other. Port connection. That is, in the second embodiment, the driving mode of the dual I/O port is used, and when the thyristor needs to be turned off, the input/output port 1 /01 can be set to a high level, and the input/output port 1 / 03 Set to low level to turn off the thyristor. Except for the above differences, the second embodiment is substantially the same as the first embodiment.

Fig. 5 is a view showing a third embodiment of the present invention, in which a unidirectional thyristor is required to be controlled. The working principle of the circuit in Figure 5 is that when the input/output port 1 /02 of the MCU detects that the AC mains is positive half-cycle input, the input and output port 1 /01 is set to a high level, and the unidirectional thyristor is driven. The current flows from the input and output port 1 /01 through the diode D5, the resistor R6 and the unidirectional thyristor Q2 back to the AC neutral terminal CN2, so that the unidirectional thyristor Q2 is turned on, when the unidirectional thyristor needs to be turned off. In Q2, set I/O port 1 /01 to low level. Except for the above differences, the third embodiment is substantially the same as the first embodiment.

6 is a fourth embodiment of the present invention for when the output current of the input/output port I/O of the single chip satisfies the driving current of the thyristor. The working principle of the circuit in Figure 6 is that when the input/output port 1 /02 detects that the mains is positive half-cycle input, if the thyristor Q1 needs to be turned on at this time, the MCU outputs a high level to the input/output port 1 /01 to make The thyristor Q1 is turned on. When the input/output port 1 /02 detects that the mains supply is a negative half-cycle input, if the thyristor Q1 needs to be turned on at this time, the microcontroller outputs a high level to the input/output port 1 / 03 to make The thyristor Q1 is turned on. When the mains is positive half-cycle input or negative half-cycle input, if the thyristor Q1 is not required to be turned on, the input/output port 1 /01 and the input/output port 1 / 03 of the MCU are both Set to low level to turn off the thyristor Ql. Except for the above differences, the fourth embodiment is substantially the same as the first embodiment. It is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims

Claim

A thyristor driving circuit comprising: a driving unit, a thyristor controlled by the driving unit, a control unit for providing a driving signal to the driving unit, and a DC power supply for supplying power to the control unit, characterized in that The DC power source is a DC power source that obtains a DC voltage by alternating current power through a full-wave rectification after RC, and a pin of the control unit is directly connected to an AC input terminal of the full-wave rectification to obtain an AC. Zero crossing detection signal.

2. The thyristor driving circuit according to claim 1, wherein the RC capacitor of the DC power source is connected in series on the AC line, and the AC phase line of the full-wave rectification is located Before the input end; the AC zero-cross detection end of the control unit is connected to the full-wave rectified AC neutral input.

3. The thyristor driving circuit according to claim 2, wherein the control unit comprises a single chip microcomputer or a programmable logic device or a programmable controller or an industrial computer, and the single chip microcomputer or the programmable logic device or the programmable The controller or the industrial computer is connected to the drive unit and the AC neutral input through its input/output port.

The thyristor driving circuit according to claim 3, wherein the thyristor comprises a unidirectional thyristor or a triac, and the driving unit comprises one or two triodes or diodes; The control unit is connected to the drive unit via one or two output ports.

The thyristor driving circuit according to claim 4, wherein the control unit and the driving unit are connected by an output port, and the driving unit comprises a transistor TR1, a transistor TR2, a resistor R4, and a resistor R5. The transistor TR1 is a PNP transistor having an emitter connected to a DC voltage output terminal of the DC power source, a collector connected to a collector of the NPN transistor TR2, an emitter of the transistor TR2 being grounded, and the transistor TR1 The base of the transistor TR2 is connected in parallel and connected to the output port through the resistor R4. One end of the resistor R5 is connected to the thyristor control pole, and the other end is connected with the transistor TR1 and the transistor TR2. Electrode connection.

The thyristor driving circuit according to claim 4, wherein the control unit and the driving unit are connected by two output ports, and the driving unit comprises a transistor TR1, a transistor TR2, a resistor R4, and a resistor. R5 and resistor R6, the transistor TR1 is a PNP transistor, the emitter thereof is connected to the DC voltage output end of the DC power source, and the collector and the set of the NPN transistor TR2 are An electrode is connected, an emitter of the transistor TR2 is grounded, one end of the resistor R5 is connected to the thyristor control electrode, and the other end is connected to the collector of the transistor TR1 and the transistor TR2, and the base of the transistor TR1 The pole is connected to an output port through a resistor R4, and the base of the transistor TR2 is connected to the other output port through a resistor R6.

A device comprising a thyristor driving circuit, wherein the thyristor driving circuit is the thyristor driving circuit according to any one of claims 1-6.

8. A thyristor driving method, wherein the method is used to resist a power supply of a step-down power supply, and the method comprises the following steps:

A) obtaining a zero-crossing signal of the alternating current by directly connecting a pin of the control unit to an alternating current input of the full-wave rectification;

The thyristor driving method according to claim 8, wherein the determining the alternating current state in the step A) is determining whether the alternating current is in its positive half cycle or in its negative half cycle.

The thyristor driving method according to claim 9, wherein the AC actual state start time is a zero crossing time of the alternating current plus a delay time; the delay time is