JP3399162B2 - Discharge circuit of main circuit capacitor in sine wave converter with regenerative function - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a main capacitor discharge circuit in a sine wave converter with a regenerative function.

[0002]

Background of the Invention to the conventional regeneration function with a sine wave converter
The discharge circuit of the main capacitor in the following will be described with reference to the first and second conventional examples shown in FIGS. First conventional example: FIG. 3 shows a main capacitor in a sine wave converter with a regenerative function.
FIG. 7 is a circuit diagram showing a first conventional example in the case where there is no discharge circuit for the sensor . In the figure, 1 is a three-phase AC power supply, and its U phase 1
AC power is supplied to each part described below by a, V-phase 1b, and W-phase 1c electric paths. 2a to 2c are AC reactors, and 3 is a main switch. 4a and 4b are switches for initial charging, 5a and 5b are initial charging resistors, respectively, and an initial charging circuit is formed by the switches for initial charging 4a and the initial charging resistor 5a, the switches for initial charging 4b and the initial charging resistor 5b. is doing. Reference numeral 6 denotes a three-phase bridge circuit, which includes a U-phase upper element 6Up, a U-phase lower element 6Un, a V-phase upper element 6Vp, and a V-phase lower element 6Vn, each of which is composed of six unit elements each including a transistor and a diode connected in parallel. , W
The phase upper side element 6Wp and the W phase lower side element 6Wn are included. Reference numeral 7 is a main capacitor. N and P are connection points of the main capacitor 7 to the output circuit, respectively. In the above configuration, when the main switch 3 is turned on (ON) while the main capacitor 7 is not charged at the start of operation, the rush current may damage the main switch 3 or the diode of the three-phase bridge circuit, or not shown. The fuse on the input side is blown,
Since the input side breaker may trip, the initial charging switches 4a and 4b are turned on (ON) before the main switch 3 is turned on (ON), and the main capacitor 7 is turned on via the initial charging resistors 5a and 5b. Is charged and the voltage of the main capacitor 7 reaches a certain level, the main switch 3 is closed (O
N) Further, when the circuit is stopped from the operating state, the main switch 3 is opened (OF
F) However, the voltage charged in the main capacitor 7 was not discharged just by opening (OFF) the main switch 3, and was still charged. Therefore, it was dangerous because the voltage remained charged during maintenance and inspection. The second conventional example: Fig. 4 is a sine wave converter with regeneration function including discharge circuit
It is a circuit diagram which shows the 2nd prior art example of the discharge circuit of the main capacitor in . In the figure, the same components as those in the first conventional example are designated by the same reference numerals as those in FIG. 3, and the description thereof will be omitted. Reference numeral 8 is a discharging resistor, and 9 is a discharging switch, which are connected in series and in parallel with the main capacitor 7 to form a discharging circuit. In the above configuration, at the start of operation, the same method as in the first conventional example is performed to prevent damage to the main switch 3 and the diode. At this time, the discharge switch 9 remains open (OFF). Here, in the second conventional example, when the circuit is stopped from the operating state, the main switch 3 is opened (OFF).
At the same time, the discharge switch 9 was turned on (ON) to discharge the voltage charged in the main capacitor 7 via the discharge resistor 8.

[0003]

By the way, the discharge of the main capacitor in the conventional sine wave converter with a regenerative function is performed.
Since the circuit is configured as described above, there are the following problems. (1) In the first conventional example, since the main capacitor was still charged with the voltage when the operation was stopped, there was a danger of electric shock during maintenance and inspection, which was dangerous. (2) In the second conventional example, since the discharge circuit is provided, there is no fear of electric shock during maintenance / inspection. However, since the discharge circuit is provided separately, the circuit becomes large and the cost is increased accordingly. The utilization efficiency of was extremely low. (3) Further, in each of the conventional examples, the initial charging resistance and the utilization efficiency of the initial charging switch were low. An object of the present invention is to provide a discharge circuit for a main circuit capacitor in a sine wave converter with a regenerative function, which solves the above problems (problems) of the conventional one.

[0004]

A discharge circuit for a main circuit capacitor in a sinusoidal wave converter with a regenerative function according to the present invention is as described in claim 1 in order to solve the above problems.
Then, the initial charging circuit etc. in which the power of the AC power supply is inserted into the two-phase electric circuit through the AC reactor , the main switch and the closed circuit.
Via DC to the main capacitor side to convert to DC power for power supply ,
Further, the sine wave converter with regeneration function which is adapted to regenerate DC power to the AC power supply side, upon stopping Conde
Comprising a discharge switch of the capacitors, when you put the discharge switching device, the introduction of the discharge switching device, with the regeneration function
Switching element for regeneration that constitutes a sinusoidal wave converter
By the partial energization of the group, each different initial charging resistor 5 is inserted into each of the two-phase electric circuits forming the initial charging circuit.
Both a and b were connected so as to form an electric path used as a discharge resistance when the operation was stopped . Also, in claim 2.
Those in's, instead of the above-described configuration, AC re power of the AC power supply
Insert into the two-phase circuit through the actuator, main switch and closed circuit
Direct current to the main capacitor side through the initial charging circuit etc.
Converts to electric power and feeds it, and also turns DC power to the AC power supply side.
Sine wave converter with regenerative function
Equipped with a switch for discharging the capacitor when operation is stopped.
When the discharge switch is turned on, the discharge switch is turned on and the sine wave converter with the regenerative function is configured.
Initial charging resistance 5a inserted into each phase in the initial charging circuit by partial energization of the regenerative switching element group ,
Only one of the initial charging resistances of 5b was connected so as to form an electric circuit used as a discharging resistance when the operation was stopped .

[0005]

In the discharge circuit of the main circuit capacitor in the sine wave converter with the regenerative function of the present invention, the utilization efficiency of the initial charging resistance and the discharging resistance is extremely low and they are not used at the same time. To exchange (D
Economical compared to the conventional circuit because the circuit is designed so that the switching element that can be regenerated (as an A converter) is used, the same resistance as the initial charging resistance is also used for discharging, and the initial charging circuit also has the discharging function. With this, a discharge circuit can be created in a small space. Therefore, when the switch for discharging is turned on, both or one of the charging resistors separately inserted into each of the two-phase electric circuits can be inserted into the discharging circuit of the main capacitor.
If the latter is adopted, even if the initial charge switch and the discharge switch are accidentally turned on at the same time, the short-circuit current generated at that time is suppressed via the resistor to prevent a power supply short circuit, and the initial charge switch is opened. Prevents damage to the switch and discharge switch, fusing of the input fuse, and tripping of the input breaker.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment for specifically explaining the present invention with reference to the first and second embodiments shown in FIGS. 1 and 2 below. FIG. 1 is a first embodiment of the present invention. It is a discharge circuit diagram of the main circuit capacitor in the sine wave converter with a regeneration function shown. In the figure, the same components as those in the first conventional example are designated by the same reference numerals as those in FIG. 3, and the description thereof will be omitted. Reference numeral 10 denotes a discharging switch, which has a connection point D between the initial charging resistor 5a and the initial charging switch 4a and an initial charging resistor 5b.
When the connection point of the switch 4b for initial charging and E is E, the connection point D and E are connected. In the above configuration, at the start of operation, as in the case of the first conventional example, first, the initial charging switches 4a and 4b are turned on to set the voltage of the main capacitor 7 to a predetermined voltage, and then the main switch 3 Is turned on to charge the main capacitor, so that the main switch 3 and the diode are not damaged by the inrush current. In addition,
At this time, the discharge switch 10 remains open (OFF). Further, in the case of this embodiment, when the circuit is stopped (OFF) from the operating state, the main switch 3
Is opened (OFF), and the discharge switch 10 is turned on (ON) to connect the initial charging resistors 5a and 5b in series to the main circuit, and the elements 6Up and 6W in the three-phase bridge circuit 6 are connected.
By turning on (ON) n (or 6Un and 6Wp), the voltage charged in the main capacitor 7 is discharged. At this time, the initial charging switches 4a and 4b
Opens (OFF). This embodiment is characterized in that the initial charging resistors 5a and 5b are also used as discharging resistors, and the elements 6Un, 6Up, 6 in the three-phase bridge circuit 6 are used.
By utilizing regeneration of direct current to alternating current using Vn, 6Vp, 6Wn, and 6Wp, the initial charging resistors 5a and 5b, which have low utilization efficiency, are utilized.

Second Embodiment: FIG. 2 is a discharge circuit diagram of a main circuit capacitor in a sine wave converter with a regenerative function according to a second embodiment of the present invention. In the figure, the same components as those in the first embodiment are designated by the same reference numerals as those in FIG. 3, and the description thereof will be omitted. Reference numeral 11 denotes a discharge switch, which is connected between a point F and a connection point E of the electric path of the initial charging resistor 5a on the three-phase bridge circuit 6 side. In the above structure, the operation is started by the same method as in the first embodiment to prevent damage to the main switch 3 and the diode due to the inrush current. At this time, the discharge switch 11 is opened (O
FF). In addition, in the case of the present embodiment, when the circuit is stopped (OFF) from the operating state, the main switch 3 is opened (OFF) and the discharge switch 11 is closed (ON), For example, elements 6Up and 6Wn in the three-phase bridge circuit 6 through the initial charging resistor 5b.
By turning on (or 6Un and 6Wp),
The voltage charged in the main capacitor 7 is discharged. At this time, the initial charging switches 4a and 4b are opened (O
FF) By the way, the switches for initial charging 4a and 4b
If the discharge switch 11 and the discharge switch 11 are mistakenly turned on at the same time (ON), a power supply short-circuit accident may occur or the initial charge switch 4
Although a, 4b and the discharge switch 11 may be damaged, the fuse on the input side may be blown, and the trip of the breaker on the input side may occur, in this embodiment, one connection point F of the switch 11 for discharge is Since the initial charging resistor 5a is removed and the three-phase bridge circuit 6 is present, a discharging circuit is formed through the initial charging resistor 5a. Therefore, even when such a situation occurs and a short-circuit current flows, this short-circuit current is The initial charging resistor 5a is always used for suppression. As described above, this embodiment has the same effect as that of the first embodiment, and in comparison with the first embodiment, both the initial charging switches 4a and 4b and the discharging switch 11 are operated due to the operation error described above. Input at the same time (ON)
Even if it is done, a large short-circuit current does not flow, and there is a structural feature in suppressing it.

[0008]

The discharge circuit of the main circuit capacitor in the sine wave converter with the regenerative function of the present invention is constructed as described above, and therefore has the following excellent effects. (1) A part of the initial charging circuit can be effectively used as a discharging circuit. (2) By making the initial charging resistor, which has conventionally been low in utilization efficiency, also serve as the discharging resistor, the manufacturing cost of the circuit can be reduced,
A discharge circuit can be manufactured in a small space. (3) With the configuration of the second embodiment, the short-circuit current due to an operation error or the like is also suppressed, the power supply short-circuit accident is prevented, and the initial charging switch and the discharging switch are prevented from being damaged. You can drive safely.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a converter with a regenerative function including a discharge circuit of a main circuit capacitor in a sine wave converter with a regenerative function according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a converter with a regenerative function including a discharge circuit of a main circuit capacitor in a sine wave converter with a regenerative function according to a second embodiment of the present invention.

[Figure 3] regenerative function converter showing a first conventional example
It is a circuit diagram when there is no discharge circuit of the main capacitor in .

FIG. 4 is a circuit diagram of a discharge circuit of a main capacitor in a converter with a regenerative function including a discharge circuit showing a second conventional example.

[Explanation of symbols]

5a, 5b: Initial charging resistance 6: Three-phase bridge circuit 6Un, 6Up, 6Vn, 6Vp, 6Wn, 6Wp: Elements 10, 11: Discharge switch

Claims (2)

(57) [Claims] 1. The AC power source is an AC reactor main opening.
The main capacitor side is converted into DC power and fed through an initial charging circuit or the like inserted in a two-phase electric circuit via a closure and a closed circuit , and the DC power is regenerated to an AC power source side. in the sine wave converter with regeneration function which is adapted to, when the operation is stopped
When the discharge switch is turned on, the discharge switch is turned on and the discharge switch is turned on.
Regenerative switch that constitutes a sine wave converter with raw function
Both of the different initial charging resistors (5a) and (5b), which are respectively inserted into the two-phase electric circuits forming the initial charging circuit by the partial energization of the charging element group, are used as the discharge resistance when the operation is stopped. A discharge circuit for a main circuit capacitor in a sine wave converter with a regenerative function, characterized in that it is connected so as to form an electric circuit to be used. 2. The AC reactor main power is supplied from the AC power source.
The main capacitor side is converted into DC power and fed through an initial charging circuit or the like inserted in a two-phase electric circuit via a closure and a closed circuit , and the DC power is regenerated to an AC power source side. in the sine wave converter with regeneration function which is adapted to, when the operation is stopped
When the discharge switch is turned on, the discharge switch is turned on and the discharge switch is turned on.
Regenerative switch that constitutes a sine wave converter with raw function
Only one of the initial charging resistances (5a) and (5b) inserted into each phase in the initial charging circuit by partially energizing the switching element group is used as the discharge resistance when the operation is stopped. A discharge circuit for a main circuit capacitor in a sine wave converter with a regenerative function, characterized in that they are connected so as to form an electric circuit.