JPS58384Y2 - pulse transformer - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an isolation transformer for transmitting gate pulses of a power converter using a thyristor, and aims to prevent erroneous firing due to gate noise.

In general, in a power converter using a thyristor, erroneous firing due to noise disturbs the power control function and, for example, in an inverter, etc., it leads to commutation failure and becomes a fatal defect.

Conventionally, this problem has been dealt with by adding constraints to the gate characteristics of the thyristor and adding a gate filter, but a large gate noise prevention filter reduces the di/dt of the rise of the gate pulse and reduces the responsibility of the thyristor. It had drawbacks such as making it harsh.

The present invention cuts gate noise by applying a reverse bias voltage within the permissible reverse bias voltage of the gate to the thyristor during a period when no gate pulse is applied to the thyristor.

Applying a gate reverse bias in this way will reduce the d of the thyristor.
It is also known that the v/dt withstand capacity is increased, and there is an advantage that the reliability of the inverter and the like is further increased.

Next, embodiments of the present invention will be described.

In FIG. 1, 1 is a DC power supply, 2 and 3 are switching elements (for example, transistors) that turn on and off the winning signal to the pulse transformation circuit 4, 5 is a transformer, 6.7 is a diode, and 8 and 9 are A thyristor is connected to the outputs GIK1, G2 and 2 with resistors (G1 and G2 to the gate, and K1 and 2 to the cathode).

Transistors 2 and 3 form a flip-flop and are conductive alternately, and when transistor 2 is conductive, 01 to 1
When the transistor 3 is conductive, a pulse such that 01 becomes positive is generated, and a pulse such that 02 becomes positive when the transistor 3 is conductive is generated to fire the thyristor.

The -/direction transformer 5 has two windings on the secondary side and is connected to each other via the iron core, so for example, when 2 is conducting, G2
At 2, a voltage is generated such that G2 becomes negative.

The diode 6 and γ discriminate the direction of this voltage, allowing only positive voltage to conduct and blocking negative voltage.

When resistors 8 and 9 are connected in parallel to this diode 6.1, a reverse voltage is divided between the reverse resistance of the thyristor gate and 8 and 9, and by appropriately selecting the values of resistors 8 and 9, A reverse voltage can be applied to the cyrisk.

FIG. 2 shows the relationship between the gate pulses, and since a reverse voltage is applied during the non-conducting period of the thyristor, very high protection performance against noise can be obtained.

Of course 1 in G1. Even when a filter consisting of a suitable resistance capacitor or the like is connected to G2, sufficient effects can be expected if the resistors 8 and 9 are appropriately selected.

FIG. 3 shows another embodiment of the present invention, according to which the first
A diode 10°11 is added to the same circuit as in the illustrated embodiment.

As a result, during the non-conducting period of the thyristor, a diode 10 or 11 is connected between the gate and cathode of the thyristor.
A constant reverse bias voltage corresponding to the weir layer voltage is applied.

[Brief explanation of drawings]

Fig. 1 is a connection diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing an example of a pulse waveform applied to the gate of a thyristor, and Fig. 3 is a connection diagram showing main parts of another embodiment of the invention. . 1...Power supply, 2,3...Transistor, 4...Pulse transformation circuit, 5...Transformer, 6,7... Diode, 8, 9...
·resistance.

Claims (1)

[Scope of utility model registration request] In a pulse transformer that is provided with a secondary winding attached to each thyristor in order to provide mutually insulated gate pulses to two thyristors that are to be made conductive alternately in a power conversion device, the primary side of the pulse transformer is The AC voltage of each secondary winding generated by AC excitation is applied to the gate of each thyristor via a diode so that the two thyristors can receive it as a gate pulse alternately in half-wave periods with different polarities. The appropriate secondary windings are connected, and one thyristor must remain non-conducting while receiving and receiving gate pulses, in such a way as to introduce a sustained reverse bias voltage at the gate of the other thyristor. , a pulse transformer characterized by having a resistor connected in parallel to each diode.