JPS631585Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Field of application of the invention] This invention is a gate turn-off thyristor (hereinafter referred to as
This invention relates to a gate circuit for a GTO (abbreviated as GTO), and in particular to a gate circuit for a GTO that uses a pulse transformer to control the GTO.

FIG. 1 shows the configuration of a conventional gate circuit.

In FIG. 1, 1 is the GTO, 2 is a DC power supply for supplying on-current to the gate of GTO1 during the on-period of GTO1, 3 is a transistor for adjusting the time to supply on-pulse current to the gate of GTO1, and 4 5 is a resistor that determines the magnitude of the on-gate current of GTO1, 5 is a DC power supply that supplies a current several times the normal on-pulse current (hereinafter referred to as overdrive current) to the gate of GTO1 when turning on GTO1, 6 is a transistor that adjusts the time for flowing overdrive current to GTO1, 7
is a resistor that determines the magnitude of the overdrive current, 8 is a DC power supply that supplies an off-pulse current to turn off GTO1, 9 is a transistor for adjusting the time to flow an off-pulse current to GTO1, and 10 is a transistor that supplies an off-pulse current to GTO1. A pulse transformer for transmission, with an intermediate tap on the primary winding. Reference numeral 11 denotes a thyristor for suppressing generation of a voltage having a polarity that causes GTO 1 to re-ignite in the pulse transformer 10 when the transistor 9 is off;
12 is the GTO polarity of the magnetic flux of the pulse transformer 10.
1 is a transistor for adjusting the reset time to the polarity opposite to the polarity when the transistor 9 is on; 13 is a resistor that determines the magnitude of the reset current of the pulse transformer 10; 14 is a resistor; This thyristor is used to prevent the on-pulse current flowing through the transistor 3 or transistor 6 from being shunted to the pulse transformer 10 when the GTO 1 is turned on. Further, 15 indicated by a dotted line is a capacitor for accelerating the rise of the overdrive current.

The operation shown in FIG. 1 will be explained with reference to FIG. 2.
In order to turn on GTO1, at time _t0 , a signal Son is applied to the base of transistor 3, and a signal Sov is applied to the base of transistor 6 to turn it on.
A current equal to the sum of the current (i _po ) determined by the resistor 4 and the current (i _pv ) determined by the resistor 7 flows through the gate of the GTO 1, and the GTO 1 is turned on. Since the overdrive current becomes unnecessary after the turn-on operation of GTO 1 is completed, transistor 6 is turned off at time _t1 . After time _t1 , a current ( _ipo ) determined by resistor 4 flows through the gate of GTO1.
Time t ₂ To turn off GTO1, transistor 3 is turned off, and an on signal (Soff) is applied to transistor 9 and thyristor 14. When the transistor 9 is turned on, an off-pulse current ( _ipff ) flows through the pulse transformer 10 to the GTO 1. Pulse current (i _pff )
When the amount of charge caused by the GTO1 exceeds the amount of charge required to cut off the anode current of the GTO1, the GTO1 turns off. After this, when the transistor 9 is turned off at time _t3 , the off-pulse current (i _pff ) changes at time _t4.
becomes zero. The thyristor 11 is turned on by applying a gate signal (Sf) at time _t3 when the transistor 9 is turned off. Turning on the thyristor 11 suppresses the induction of a voltage in the secondary winding of the pulse transformer 10 with a polarity that would cause the GTO 1 to restart. time t ₃
Thereafter, a current flows through the thyristor 11, and this current attenuates to zero, turning off the thyristor 11.
After that, at time _t5 , an on signal (Sres) is applied to the reset transistor 12 of the pulse transformer 10, and the polarity of the magnetic flux generated in the pulse transformer 10 is changed.
Current flows with the opposite polarity to that during GTO1 turn-off operation. Therefore, the pulse transformer 10 is reset and ready for the next OFF operation. When GTO1 is turned on again at time _t6 , the above-described operation is repeated.

As described above, the GTO is controlled on and off. In the case of Fig. 1, the power supply 5, transistor 6, and
Although not shown, a circuit for creating a control signal (Sov) for controlling the time during which the overdrive current flows, a circuit for controlling on/off of the transistor 6, etc. are required. In particular, since the power source is composed of a transformer for insulating it from the operating circuit, a rectifier circuit, a smoothing filter, etc., the necessity of the power source 5 complicates the circuit configuration.
As a result, the gate circuit of the GTO becomes more complex, and as a result, the device becomes larger and more expensive. Therefore, when configuring an inverter etc. using GTO,
Multiple GTOs (six for a three-phase inverter) are required, and each GTO requires an overdrive power transistor, etc.
Therefore, the entire device inevitably becomes larger and more expensive.

[Purpose of invention]

The purpose of this proposal is to eliminate the drawbacks of the above-mentioned prior art,
To provide a gate circuit for a gate turn-off thyristor which has a simple circuit configuration and can be miniaturized.

[Summary of the idea]

The feature of this proposal is that the pulse transformer is reset in synchronization with the GTO's on-pulse current supply, and when the pulse transformer is reset, the pulse current flowing through the secondary winding is superimposed on the on-pulse current and supplied as an overdrive current. west,
The reason is that the OFF power supply is also used as an overdrive current supply power supply.

[Example of idea]

FIG. 3 is a circuit configuration diagram showing a specific embodiment of the present invention. In the figure, 1 to 4, 8 to 12, and 14 are the same components as in Figure 1, 16 is a thyristor for passing overdrive current to GTO 1, and 17
is a resistor that determines the magnitude of the overdrive current of GTO1, and 18, indicated by a dotted line, is a capacitor that makes the rise of the overdrive current faster. Note that the thyristor 16 is used in
During turn-off operation of GTO1, when transistor 9 transitions from on to off state, a polarity voltage (flyback voltage) that re-ignites GTO1 is induced in the secondary winding of pulse transformer 10, and this flyback voltage turns GTO1 off. This is to prevent current from flowing that would cause restriking.

The operation shown in FIG. 3 will be explained with reference to FIG. 1 and 2, in order to turn on GTO1, at time _t0 , the signals Son and Sres are applied to the bases of transistor 3 and transistor 12 to turn them on, and the signal Sov is applied to the gate of thyristor 16.
Apply. The gate of GTO 1 has a current that is the sum of the current (i _po ) determined by resistor 4 and the current supplied from the secondary winding of pulse transformer 10 and determined by resistor 17, that is, the overdrive current (i _pv ). (i _G ) flows. At this time, the polarity of the magnetic flux of the pulse transformer 10 is opposite to the polarity during the turn-off operation of the GTO 1 (when the transistor 9 is turned on), which will be described later. That is, pulse transformer 1
0 will be reset in preparation for the turn-off operation of GTO1. Transistor 12 is GTO
The on state is maintained for the longer of the time required for one overdrive current or the time required to reset the pulse transformer 10. Fourth
In the figure, the period from time t ₀ to t ₁ is the required time. At time _t2 , the transistor 3 is turned off and the on-gate current i _po becomes zero. At this time, a signal (Soff) is applied to the base of the transistor 9 to turn it on, and at the same time, a gate signal (Soff) is applied to the thyristor 14 as well. An off-pulse current ( _ipff ) flows through the gate of GTO1. As a result, GTO1 is turned off, and thereafter, at time _t3 , transistor 9 is turned off. At the same time as the transistor 9 is turned off, the thyristor 11 is turned on to suppress the appearance of a voltage in the secondary winding of the pulse transformer 10 with a polarity that would cause the GTO 1 to re-ignite. At time _t4 , on-current and overdrive current flow through GTO1 as shown in the figure, and the above operation is repeated. According to the embodiment shown in FIG. 3, when the GTO is turned on, the turn-off pulse transformer is reset and the reset winding is used.
It becomes possible to flow the overdrive current that is essential for GTO turn-on operation. In this way, since the off power supply 8 is also used as a power supply for flowing an overdrive current, it is possible to omit an overdrive current supply power supply and a switching element such as a transistor for controlling this overdrive current.

[Effect of idea]

As described above, according to this proposal, the overdrive current that is essential for the turn-on operation of the GTO can be
Since the reset winding of the pulse transformer that transmits the off-gate current is used to flow it, a dedicated power supply for the overdrive current can be omitted, and this power supply is shared with the power supply for the off-gate current and the reset power supply for the pulse transformer. Moreover, since the switching element that controls the time during which the overdrive current flows can be omitted, the GTO
This simplifies the configuration of the gate circuit for controlling on/off of the gate, which allows the circuit to be made smaller and also has the effect of lowering the cost. In particular, when configuring a device using multiple GTOs, there is no need for a power supply for overdrive current corresponding to the number of GTOs required, making it possible to downsize the device as a whole, resulting in economical effects. is also large. For example, when configuring a three-phase inverter, at least six GTOs are required, so six overdrive current power supplies are unnecessary.
From this, it is clear that the above-mentioned effects are achieved.

In the explanation, the thyristor 14 and the thyristor 16 are connected to the secondary side of the pulse transformer, but the effect is the same even if these thyristors are replaced with switching elements such as transistors or GTOs.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing a conventional example, FIG. 2 is a time sequence diagram for explaining the operation of FIG. 1, and FIG. 3 is a circuit configuration diagram showing an embodiment of the present invention.
FIG. 4 is a time sequence diagram for explaining the operation of FIG. 3. 1...GTO, 2...DC power supply, 3...Transistor, 4...Resistor, 5...DC power supply, 6...
Transistor, 7...Resistor, 8...DC power supply,
9...transistor, 10...thyristor, 11
...Transistor, 12...Resistor, 13...Pulse transformer, 14...Thyristor.

Claims (1)

[Scope of utility model registration request] a first switching element that supplies an on-pulse current to the gate turn-off thyristor from an on-power source; a pulse transformer that has an intermediate tap on a primary winding and supplies a pulse current from a secondary winding to the gate turn-off thyristor; A turn-off power supply that applies a voltage between the middle tap and both ends of the primary winding of the pulse transformer, and a turn-off power supply that is connected to one end of the primary winding, and when turned on, turns the gate turn-off thyristor from the secondary winding. a second switching element that supplies an off-pulse current to the first switching element;
A third switching element connected to the other end of the secondary winding and resets the pulse transformer when turned on; and a third switching element connected to one end of the secondary winding and turned on and off in synchronization with the second switching element. a fifth switching element that is connected in parallel with the fourth switching element and turns on and off in synchronization with the third switching element, and synchronizes the first and third switching elements. A gate circuit for a gate turn-off thyristor, characterized in that a pulse current that is turned on and flows through the secondary winding is superimposed on the on-pulse current and supplied to the gate turn-off thyristor.