JPH01318562A - Snubber energy regenerative circuit - Google Patents

Abstract

PURPOSE:To make the efficiency of an apparatus higher and to miniaturize the apparatus by temporarily storing the surplus energy of the AC side inductance component of a rectifier in a snubber capacitor and thereafter by regenerating energy on the inverter side. CONSTITUTION:A snubber energy regeneration circuit is furnished with a voltage-type inverter 1 as AC voltage generator, a rectifier circuit 100 composed of diodes 2-5, and a transformer 30. A parallel circuit of capacitor 10 and resistor 11 is connected with the DC output terminal of the rectifier circuit 100 via DC reactor 8, and a snubber circuit 102 by snubber capacitor 6 and snubber diode 7 is further connected therewith. Then, the neutral point M of the tertiary winding of transformer 30 is connected with the snubber capacitor 7 and the winding tap X of the winding, with a transistor 12, etc. Also, the winding tap Y and transistor 13 of the tertiary winding, diode 15, etc., are connected in a like manner. Thus, when voltage is generated in the second and third windings of transformer 30, the transistors 12, 13 turn conductive to regenerate the energy of the snubber capacitor 7 on the inverter side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a snubber energy regeneration circuit capable of regenerating energy absorbed by a snubber circuit.

[Conventional technology]

FIG. 3 shows a conventional snubber circuit, in which the output of an inverter 1, which is an AC voltage source, is connected to the primary winding of a transformer 20, and the secondary winding is connected to diodes 2 and 3 as semiconductor elements. , 4.5, are connected to AC input terminals (U) and (V) of a rectifier circuit 100 composed of a bridge connection circuit of 4.5. DC output terminals (P), (N) of this rectifier circuit 100
A parallel circuit of a capacitor 10 and a resistor 11 is connected via a DC reactor 8 .

Furthermore, a DC output terminal (P) of the rectifier circuit 100.

A snubber circuit 101 consisting of a diode 6, a capacitor 7, and a resistor 9 is connected to (N).

In such a circuit configuration, the inverter output voltage V
It is assumed that ab is a square wave voltage having a voltage Ov period as shown in FIG. 4, and at this time, the voltage (2) of the reactor 8 is such that the current is not intermittent as shown in the figure.

When a positive voltage is generated in the output voltage Vab of the inverter 1, the output terminal (a) of the inverter 1 - the leakage inductance of the transformer 21 -> the diode 2 -> the reactor 8 - the capacitor 10 and the resistor 11 - the diode 5 - the inverter 1 A current flows through the path of the output terminal (b).

Next, when the output voltage Vab of the inverter 1 reaches a period of Ov, the diode 2 → reactor 8 → capacitor 10,
Resistor 11-diode 4 path and diode 3-reactor 8 capacitor 10, resistor 11-diode 5
Current flows through this path, resulting in a so-called free circulation mode. At this time, the DC output voltage VPN of the rectifier circuit is O as shown in Figure 4.
Therefore, the charge in the snubber capacitor 7 is discharged via the resistor 9 and released as thermal energy.

Next, when a negative voltage occurs in the output voltage Vab of the inverter 1, the inverter 1
terminal (b) → diode 5 - diode 4 → leakage inductance 21 - terminal (a) of inverter l and terminal (b) of inverter 1 → diode 3 → diode 2 -
A reverse recovery current flows through the path from leakage inductance 21 to terminal (a) of inverter 1, and diode 5 and diode 2 undergo reverse recovery. After that, the portion of the current flowing through the leakage inductance 21 that exceeds the current of the reactor 8 is
Since it is absorbed by the snubber circuit 101, overvoltage applied to the diode 2 and the diode 5 can be prevented.

The above operation constitutes a half cycle of operation, and the same applies to the remaining half cycles.

[Problem to be solved by the invention]

In the snubber circuit 101, the snubber capacitor 7 is charged via the snubber diode 6 and discharged via the snubber resistor 9 every half cycle of the inverter operation. For this reason, as the operating frequency and voltage value of the inverter increase, the loss generated in the resistor 9 and the capacitor 7
There are problems such as an increase in charge/discharge losses, a need to increase the size of the resistor 9 and the capacitor 7, a decrease in device efficiency, and a rise in manufacturing costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a snubber energy regeneration circuit which can efficiently regenerate the snubber energy absorbed by the snubber capacitor and which can be made small and inexpensive as a snubber circuit. be.

[Means for Solving the Problems] In order to achieve the above object, the present invention connects the AC output end of a voltage source inverter to the primary winding of a transformer, and connects a rectifier circuit to the winding of the transformer. , in a circuit that connects a snubber circuit consisting of a snubber diode and a snubber capacitor for suppressing overvoltage of a semiconductor element constituting the rectifier circuit between DC output terminals of the rectifier circuit, both ends of the snubber capacitor are connected to the terminal of the transformer. The gist is that a semiconductor switch is connected between the tertiary windings and is turned on and off using the electromotive force of the tertiary winding between this snubber capacitor and the tertiary winding of the transformer. It is.

[Effect]

According to the invention, a voltage source inverter produces an output voltage;
Moreover, the second part of the transformer. When a voltage is developed across the tertiary winding, the semiconductor switch between the snubber capacitor and the tertiary winding becomes conductive.

At this time, by making the semiconductor switch conductive only when the voltage of the snubber capacitor and the electromotive voltage of the tertiary winding have the same polarity, the voltage of the snubber capacitor becomes
It is discharged to the voltage of the tertiary winding.

Thereby, the energy absorbed by the snubber capacitor during reverse recovery of the semiconductor elements constituting the rectifier circuit can be regenerated to the inverter side through the tertiary winding of the transformer with low loss.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the snubber energy regeneration circuit of the present invention, and the same components as in FIG. 3 showing the conventional example are given the same reference numerals.

That is, in the figure, 1 is a voltage source inverter as an AC voltage source, 100 is a rectifier circuit composed of diodes 2 to 5 as semiconductor elements, and the primary winding of the transformer 30 is connected to the AC output terminal of the inverter 1, The secondary winding is connected to an AC input terminal of rectifier circuit 100.

Further, a parallel circuit of a capacitor 10 and a resistor 11 is connected to a DC output terminal of the rectifier circuit 100 via a DC reactor 8, and a series connection of a snubber capacitor 6 and a snubber diode 7 is connected to the DC output terminal of the rectifier circuit 100. The snubber circuit 102 consisting of a circuit is connected in the same manner as in the conventional circuit.

In the present invention, the neutral point (M) of the tertiary winding of the transformer 30 is
It is connected to one terminal (N) of the snubber capacitor 7, the emitter of a transistor 12 as a semiconductor switch is connected to the winding tap (X) of the tertiary winding, and the collector of this transistor 12 is connected to the diode 14. The cathode of the diode 14 is connected to the other terminal (d) of the capacitor 7, and the heath terminal of the transistor 12 is connected to the winding end (Xl) of the tertiary winding.
is connected to via a resistor 16.

Also, the winding tap (Y) of the tertiary winding and the transistor 13 as a semiconductor switch. diode 151
The winding end (Y l ) and the resistor 17 are also connected in the same manner as described above.

Next, the operation will be explained with reference to FIG.

In the circuit shown in FIG. 1, the output voltage V of the inverter 1
Consider a case where ab generates a positive voltage and diode 3.4 reversely recovers.

Of the current flowing through the leakage inductance 31 of the transformer 30, the portion exceeding the current flowing through the reactor 8 is absorbed by the snubber circuit 102, and the terminal voltage Vc of the capacitor 7 begins to rise.

Here, the voltage Vx between (X) and (M) of the tertiary winding is
The electromotive force of the secondary winding is set to be equal to ■,
Furthermore, if the voltage vI between (XI) and (X) of the tertiary winding and the resistor 16 are selected to sufficiently conduct the transistor 12, the transistor 12 becomes conductive, and the voltage across the capacitor 7 The energy of Vc is discharged along the path of capacitor 7→diode 14→transistor 12→inverter 1→capacitor 7, and the capacitor voltage Vc becomes equal to E.

The next half cycle of the operation of the inverter 1 can be considered in the same way.

In this way, the energy temporarily absorbed by the capacitor 7 is regenerated by the inverter 1, resulting in high efficiency.Moreover, since the range of change in the charging/discharging voltage of the capacitor 7 is smaller than that of the conventional circuit shown in FIG. 3, the capacitor 7 is small. , advantages such as lower loss can be obtained.

Further, the power regenerated through the tertiary winding of the transformer 30 is only the energy absorbed by the capacitor 7,
Its value is sufficiently small compared to the main circuit power and therefore the tertiary winding, transistor 12.13, diode 14.
15 is small compared to the main circuit components.

〔Effect of the invention〕

As described above, the snubber energy regeneration circuit of the present invention applies the AC output voltage of the voltage source inverter to the primary winding of the transformer, and converts the AC voltage generated in the secondary winding into DC voltage by the rectifier circuit. In a snubber capacitor that has the function of temporarily absorbing surplus energy accumulated in the inductance component on the alternating current side of the rectifier when the semiconductor elements constituting the rectifier circuit undergo reverse recovery, the inductance After the surplus energy of the components is temporarily stored in the snubber capacitor, it can be efficiently regenerated to the inverter side, which is the power source, so that high efficiency and miniaturization of the device can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the snubber energy regeneration circuit of the present invention, Fig. 2 is an operating waveform diagram of the same as above, Fig. 3 is a circuit diagram showing a conventional example, and Fig. 4 is an operating waveform diagram of the same as above. . 1... Inverter 2.3, 4, 5.6... Diode 7.10... Capacitor 8... DC reactor 9
, 11.16.17...Resistor 10...Capacitor 20.30...Transformer 2
L 31...Transformer leakage inductance 100...
Rectifier circuit 101, 102... snubber circuit 12,
13...Transistor 14, 15...Diode i11 Figure 2 ■ε- oV□ Figure 3 Figure 4

Claims (1)

[Claims] The AC output terminal of the voltage source inverter is connected to the primary winding of a transformer, a rectifier circuit is connected to the winding of the transformer, and the overvoltage of the semiconductor elements forming the rectifier circuit is removed between the DC output terminals of this rectifier circuit. In a circuit that connects a snubber circuit consisting of a snubber diode and a snubber capacitor for suppression, both ends of the snubber capacitor are connected to the tertiary winding of the transformer, and the snubber capacitor and the tertiary winding of the transformer are connected to each other. A snubber energy regeneration circuit characterized in that a semiconductor switch that is turned on and off using the electromotive voltage of the tertiary winding is inserted between the wires.