GCT drive circuit

Abstract

The utility model provides a GCT drive circuit, which is used for driving a gate commutated thyristor, and comprises a rectification circuit, a turn-off power supply circuit connected with the rectification circuit, and a turn-off capacitor connected to the output end of the turn-off power supply circuit. The rectifying circuit is used for rectifying an input voltage, and the turn-off power supply circuit is used for providing a turn-off voltage for the gate commutated thyristor based on the voltage rectified by the rectifying circuit; the turn-off power supply circuit also includes a buck-boost circuit having a first controllable switch, where the duty cycle of the first controllable switch is adjustable. According to the driving circuit provided by the invention, by adjusting the duty ratio of the controllable switch, the step-up and step-down circuit can be enabled to boost or step down, so that the input voltage range is effectively increased, and the problem that the IGCT cannot be reliably turned off is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of power electronic devices, and in particular to a GCT drive circuit. Background Art

[0002] Integrated Gate Commutated Thyristors (IGCTs) are high-power power electronic devices with advantages such as high reliability and large voltage and current capacity. IGCTs consist of gate-commutated thyristors (GCTs) and a matching gate drive unit. Due to their special operating principle, the GCT drive circuit has a significant impact on the reliable operation of the IGCT.

[0003] like Figure 1 As shown in FIG, the driving circuit of the existing GCT is mainly divided into three parts: the first part is a shutdown power supply circuit composed of a Buck step-down converter, which is used to provide a shutdown voltage for turning off the GCT; the second part is a turn-on power supply circuit composed of a DC-DC boost converter, which is used to provide a turn-on voltage for turning on the GCT; the third part is composed of a circuit driving unit Trig and a switch tube S that switches between on and off, which is used to control the conduction and shutdown of the GCT.

[0004] The problem with the above circuit is that the voltage range is relatively narrow. When the input voltage is lower than , it is easy to cause the IGCT to be unable to reliably turn on or off. Utility Model Content

[0005] The present application provides a GCT driving circuit to solve the problem that the IGCT cannot be reliably shut down due to limited input voltage.

[0006] On one hand, the present application provides a GCT driving circuit for driving a gate-commutated thyristor, the driving circuit comprising a rectifier circuit, a shutoff power circuit connected to the rectifier circuit, and a shutoff capacitor connected to an output end of the shutoff power circuit;

[0007] The rectifier circuit is used to rectify the input voltage, and the shutdown power supply circuit is used to provide a shutdown voltage for the gate-commutated thyristor based on the voltage rectified by the rectifier circuit;

[0008] The shutdown power supply circuit further comprises a buck-boost circuit having a first controllable switch, wherein a duty cycle of the first controllable switch is adjustable.

[0009] In one example, the rectifier circuit includes a diode uncontrolled rectifier bridge and a filter capacitor connected to an output end of the diode uncontrolled rectifier bridge.

[0010] In one example, the buck-boost circuit includes a flyback switching power supply circuit composed of a transformer, a first diode, and the first controllable switch;

[0011] One end of the primary winding of the transformer is connected to the rectifier circuit, the other end of the primary winding of the transformer is connected to the first electrode end of the first controllable switch, the second electrode end of the first controllable switch is grounded, one end of the secondary winding of the transformer is connected to the anode of the first diode, the other end of the secondary winding of the transformer is grounded, the cathode of the first diode is connected to one end of the turn-off capacitor, and the other end of the turn-off capacitor is grounded.

[0012] In one example, the driving circuit further includes a second controllable switch;

[0013] The first electrode terminal of the second controllable switch is connected to the gate terminal of the gate-commutated thyristor, and the second electrode terminal of the second controllable switch is grounded; the cathode terminal of the gate-commutated thyristor is connected to the cathode of the first diode.

[0014] In one example, both the first controllable switch and the second controllable switch are NMOS transistors.

[0015] In one example, the buck-boost circuit includes a BUCK-BOOST circuit consisting of a first inductor, a second diode, and the first controllable switch;

[0016] The first electrode end of the first controllable switch is connected to the rectifier circuit, the second electrode end of the first controllable switch is connected to the cathode of the second diode and one end of the first inductor, the other end of the first inductor is grounded, the anode of the second diode is connected to one end of the turn-off capacitor, and the other end of the turn-off capacitor is grounded.

[0017] In one example, the driving circuit further includes a third controllable switch;

[0018] The first electrode terminal of the third controllable switch is connected to the anode of the second diode, the second electrode terminal of the third controllable switch is connected to the gate terminal of the gate-commutated thyristor, and the cathode terminal of the gate-commutated thyristor is grounded.

[0019] In one example, both the first controllable switch and the third controllable switch are NMOS transistors.

[0020] In one example, the driving circuit also includes a conduction power circuit connected to the shutdown power circuit and a conduction capacitor connected to the output end of the conduction power circuit, and the conduction power circuit is used to provide a conduction current for the gate-commutated thyristor based on the output voltage of the shutdown power circuit.

[0021] In one example, the conductive power circuit includes a BOOST circuit consisting of a second inductor, a third diode, and a fourth controllable switch.

[0022] The GCT drive circuit provided above can make the buck-boost circuit boost or buck the voltage by adjusting the duty cycle of the controllable switch, thereby effectively increasing the input voltage range and avoiding the problem that the IGCT cannot be reliably shut down. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of an existing GCT driving circuit;

[0024] Figure 2 A schematic diagram of a GCT driving circuit provided in an embodiment of the present application;

[0025] Figure 3 This is a schematic diagram of another GCT driving circuit provided in an embodiment of the present application.

[0026] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application clearer and more understandable, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0028] In the description of this application, it should be understood that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "front," "back," "left," and "right" are based on the directions or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] like Figure 2 As shown, a GCT driving circuit provided in one embodiment of the present application is used to drive a gate-commutated thyristor (GCT). The driving circuit includes a rectifier circuit, a shutdown power circuit connected to the rectifier circuit, a shutdown capacitor connected to the output end of the shutdown power circuit, a conduction power circuit connected to the shutdown power circuit, and a conduction capacitor connected to the output end of the conduction power circuit.

[0030] The rectifier circuit is used to rectify the input voltage. The rectifier circuit includes a diode uncontrolled rectifier bridge and a filter capacitor connected to the output end of the diode uncontrolled rectifier bridge.

[0031] like Figure 2 As shown in FIG, diodes D1 to D4 form a diode uncontrolled rectifier bridge, and a filter capacitor Cvin is connected between two output terminals of the diode uncontrolled rectifier bridge.

[0032] The shutdown power supply circuit is used to provide a shutdown voltage for the gate-commutated thyristor based on the voltage rectified by the rectifier circuit; the conduction power supply circuit is used to provide a conduction current for the gate-commutated thyristor based on the output voltage of the shutdown circuit.

[0033] like Figure 2 As shown in , the shutdown power supply circuit further includes a buck-boost circuit having a first controllable switch, and the buck-boost circuit includes a flyback switching power supply circuit composed of a transformer T1, a first diode D5 and a first controllable switch Q1;

[0034] One end of the primary winding of the transformer T1 is connected to the rectifier circuit, the other end of the primary winding of the transformer T1 is connected to the first electrode end of the first controllable switch Q1, the second electrode end of the first controllable switch Q1 is grounded, one end of the secondary winding of the transformer T1 is connected to the anode of the first diode D5, the other end of the secondary winding of the transformer T1 is grounded, the cathode of the first diode D5 is connected to one end of the turn-off capacitor Coff, and the other end of the turn-off capacitor Coff is grounded.

[0035] like Figure 2 As shown in , the conductive power circuit includes a BOOST circuit consisting of a second inductor L1, a third diode D6 and a fourth controllable switch Q2.

[0036] One end of the second inductor L1 is connected to the cathode of the first diode D5, the other end of the second inductor L1 is connected to the anode of the third diode D6 and the first electrode end of the fourth controllable switch Q2, the second electrode end of the fourth controllable switch Q2 is grounded, the cathode of the third diode D6 is connected to one end of the conduction capacitor Con, and the other end of the conduction capacitor Con is connected to the cathode of the first diode D5.

[0037] like Figure 2 As shown in , the driving circuit further includes a second controllable switch Q3;

[0038] The first electrode of the second controllable switch Q3 is connected to the gate terminal (G terminal) of the gate-commutated thyristor, and the second electrode of the second controllable switch Q3 is grounded; the cathode terminal (K terminal) of the gate-commutated thyristor is connected to the cathode of the first diode D5.

[0039] like Figure 2 As shown in , the first controllable switch Q1 and the second controllable switch Q3 are both NMOS transistors. The first electrode terminal of the first controllable switch Q1 or the second controllable switch Q3 is the drain of the NMOS transistor, and the second electrode terminal of the first controllable switch Q1 or the second controllable switch Q3 is the source of the NMOS transistor.

[0040] like Figure 2 As shown in , the driving circuit further includes a circuit driving unit Trig, one end of the circuit driving unit Trig is connected to the cathode of the third diode D6, and the other end of the circuit driving unit Trig is connected to the gate terminal (G terminal) of the gate-commutated thyristor.

[0041] By adjusting the duty cycle of the controllable switch, the buck-boost circuit can be made to step up or step down the voltage, thereby effectively increasing the input voltage range and avoiding the problem that the IGCT cannot be reliably turned off or turned on.

[0042] The working principle of this circuit is roughly as follows:

[0043] When Q1 is turned on, the voltage ui rectified by the rectifier bridge circuit is stored in the primary winding of transformer T1. The output provides a turn-off voltage to GCT through capacitor Coff, and diode D5 is reverse biased and cut off. The conduction time of Q1 is recorded as ton, and the duty cycle is: Its forward volt-second is (assuming the primary-to-secondary turns ratio of transformer T1 is 1:1): ui*Don.

[0044] When Q1 is turned off, the energy of the primary side magnetizing inductance of transformer T1 is transferred to the secondary side, and diode D5 is forward biased and turned on, providing the required voltage for GCT to turn off. The off time of Q1 is recorded as toff, and the duty cycle is: Its reverse volt-second is (assuming the primary-to-secondary turns ratio of transformer T1 is 1:1): uo*(1-Don), so the relationship between uo and ui can be obtained as follows:

[0045]

[0046] When the primary-to-secondary turns ratio of transformer T1 is N, the relationship between uo and ui is:

[0047]

[0048] In summary, by adjusting the duty cycle of Q1, the input voltage range can be effectively increased compared to the current shutdown power supply composed of a buck circuit, avoiding the problem of the IGCT being unable to reliably turn on or off.

[0049] Figure 3 A GCT driving circuit is provided in another embodiment of the present application.

[0050] and Figure 2The difference is that the buck-boost circuit includes a BUCK-BOOST circuit consisting of a first inductor T1', a second diode D5' and a first controllable switch Q1';

[0051] A first electrode end of the first controllable switch Q1' is connected to the rectifier circuit, a second electrode end of the first controllable switch Q1' is connected to the cathode of the second diode D5' and one end of the first inductor T1', the other end of the first inductor T1' is grounded, an anode of the second diode D5' is connected to one end of the turn-off capacitor Coff, and the other end of the turn-off capacitor Coff is grounded.

[0052] and Figure 2 The difference is that the conductive power circuit includes a BOOST circuit consisting of a second inductor L1 ′, a third diode D6 ′ and a fourth controllable switch Q2 ′.

[0053] The second inductor L1' is grounded. The other end of the second inductor L1' is connected to the anode of the third diode D6 and the first electrode end of the fourth controllable switch Q2'. The second electrode end of the fourth controllable switch Q2' is connected to the anode of the second diode D5'. The cathode of the third diode D6 is connected to one end of the conduction capacitor Con. The other end of the conduction capacitor Con is connected to the anode of the second diode D5'.

[0054] and Figure 2 The difference is that the driving circuit includes a third controllable switch Q3';

[0055] A first electrode of the third controllable switch Q3 ′ is connected to the anode of the second diode D5 ′, a second electrode of the third controllable switch Q3 ′ is connected to the gate of the gate-commutated thyristor, and a cathode of the gate-commutated thyristor is grounded.

[0056] exist Figure 3 In the embodiment, the first controllable switch Q1' and the second diode D5' are both NMOS transistors. The first electrode of the first controllable switch Q1' or the second diode D5' is the drain of the NMOS transistor, and the second electrode of the first controllable switch Q1' or the second diode D5' is the source of the NMOS transistor.

[0057] Figure 3 The working principle of the circuit is roughly as follows:

[0058] When Q1' is turned on, the voltage ui rectified by the rectifier bridge circuit passes through Q1' and stores energy in the inductor L1'. The voltage direction on the inductor L1' is positive at the top and negative at the bottom. The conduction time of Q1' is recorded as ton, and the duty cycle is: The diode D5' is in reverse bias cut-off state. During the conduction period of Q1', the voltage on L1' is U L1’ =ui*Don, the capacitor Coff keeps the output voltage basically unchanged.

[0059] When Q1' is turned off, the energy stored in the inductor L1' is released to the load. The current flows in the direction of: inductor L1' through capacitor Coff and diode D5'. The voltage direction of capacitor Coff is positive at the bottom and negative at the top, which is a negative polarity output. The off time of Q1' is recorded as toff, and the duty cycle is: During the off period of Q1', the voltage U on the inductor L1' L1’ =uo*Doff=uo*(1-Don), so the relationship between input ui and output uo can be obtained as follows:

[0060]

[0061] It can be seen from the relationship that by changing the duty cycle Don, the output voltage uo can be higher or lower than the input voltage ui. When the pressure is reduced, This effectively broadens the circuit's input voltage range. For example, when the input voltage ui is lower than the GCT's standard shutdown voltage of 20V, this circuit can perform a step-up conversion. When the input voltage ui is higher than the GCT's standard shutdown voltage of 20V, this circuit can perform a step-down conversion. Compared to the requirements of previous buck circuits and GCT manufacturers, the IGCT can still be reliably turned on and off when the input voltage Vin is lower than 20V.

[0062] The preferred embodiments of the present application are described above with reference to the accompanying drawings, but are not intended to limit the scope of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and essence of the present application shall fall within the scope of the present application.

Claims

1. A GCT drive circuit for driving a gate-commutated thyristor, characterized in that: The driving circuit includes a rectifier circuit, a shutoff power circuit connected to the rectifier circuit, and a shutoff capacitor connected to an output end of the shutoff power circuit; The rectifier circuit is used to rectify the input voltage, and the shutdown power supply circuit is used to provide a shutdown voltage for the gate-commutated thyristor based on the voltage rectified by the rectifier circuit; The shutdown power supply circuit further comprises a buck-boost circuit having a first controllable switch, wherein a duty cycle of the first controllable switch is adjustable.

2. The driving circuit according to claim 1, wherein: The rectifier circuit includes a diode uncontrolled rectifier bridge and a filter capacitor connected to the output end of the diode uncontrolled rectifier bridge.

3. The driving circuit according to claim 1, wherein: The buck-boost circuit includes a flyback switching power supply circuit composed of a transformer, a first diode and the first controllable switch; One end of the primary winding of the transformer is connected to the rectifier circuit, the other end of the primary winding of the transformer is connected to the first electrode end of the first controllable switch, the second electrode end of the first controllable switch is grounded, one end of the secondary winding of the transformer is connected to the anode of the first diode, the other end of the secondary winding of the transformer is grounded, the cathode of the first diode is connected to one end of the turn-off capacitor, and the other end of the turn-off capacitor is grounded.

4. The driving circuit according to claim 3, wherein: The driving circuit further includes a second controllable switch; The first electrode terminal of the second controllable switch is connected to the gate terminal of the gate-commutated thyristor, and the second electrode terminal of the second controllable switch is grounded; the cathode terminal of the gate-commutated thyristor is connected to the cathode of the first diode.

5. The driving circuit according to claim 4, wherein: The first controllable switch and the second controllable switch are both NMOS transistors.

6. The driving circuit according to claim 1, wherein: The buck-boost circuit includes a BUCK-BOOST circuit consisting of a first inductor, a second diode and the first controllable switch; The first electrode end of the first controllable switch is connected to the rectifier circuit, the second electrode end of the first controllable switch is connected to the cathode of the second diode and one end of the first inductor, the other end of the first inductor is grounded, the anode of the second diode is connected to one end of the turn-off capacitor, and the other end of the turn-off capacitor is grounded.

7. The driving circuit according to claim 6, wherein: The driving circuit further includes a third controllable switch; The first electrode terminal of the third controllable switch is connected to the anode of the second diode, the second electrode terminal of the third controllable switch is connected to the gate terminal of the gate-commutated thyristor, and the cathode terminal of the gate-commutated thyristor is grounded.

8. The driving circuit according to claim 7, wherein: The first controllable switch and the third controllable switch are both NMOS transistors.

9. The driving circuit according to claim 1, wherein: The drive circuit further includes a conduction power circuit connected to the shutdown power circuit and a conduction capacitor connected to the output end of the conduction power circuit. The conduction power circuit is used to provide a conduction current for the gate-commutated thyristor based on the output voltage of the shutdown power circuit.

10. The driving circuit according to claim 9, wherein: The conductive power supply circuit includes a BOOST circuit composed of a second inductor, a third diode and a fourth controllable switch.

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