JP3583501B2 - Inverter device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a voltage-type inverter for driving an induction motor, and more particularly to an inverter device having a dynamic braking function.
[0002]
[Prior art]
FIG. 6 shows a conventional example of an inverter device having a dynamic braking function, and FIG. 7 shows the dynamic braking device, wherein 1 is a commercial power supply, 2 is an inverter unit, 3 is an induction motor (hereinafter simply referred to as a motor), 4 is a frequency setting device, 5 is a dynamic braking device, and 6 is a braking resistor.
[0003]
That is, in the inverter unit 2, a rectifier 21 for converting the commercial power supply 1 into a direct current, a closing current suppressing resistor 22, a contactor 23 for short-circuiting the closing current suppressing resistor 22, a filter contactor 24, A main circuit is configured by the inverter 25 that converts the DC voltage to the AC voltage and drives the electric motor 3.
The control unit 27 obtains a control power supply 26 to which the intermediate DC voltage A101 is input, and drives a transistor (switching element) in the inverter 25 through a driving unit 28 according to a command of the frequency setting unit 4 to drive the motor 3 To drive.
[0004]
In this type of inverter device, when the motor is decelerated for a predetermined time, a power generation braking device that absorbs energy is generally required.
In general, in an inverter device having a large capacity, a dynamic braking device 5 and a braking resistor 6 are provided outside as shown in the figure, and braking energy is absorbed by the resistor.
The dynamic braking device 5 uses the commercial power supply 1 as an input to generate a control power supply with the transformer 51 and the power supply unit 52, compares the output of the command unit 53 with the detected A101 by the comparator 54, and the driver 55 The arc extinguishing element) 56 is driven. Here, 57 is a snubber circuit for absorbing surge voltage.
Thus, in the prior art, the power braking unit is particularly arranged in the DC power supply unit of the inverter device.
[0005]
[Problems to be solved by the invention]
Such a conventional technique has the following problems.
(B) Since the control powers of the inverter unit and the dynamic braking device are separated and the holding times of the two are different and the inverter unit is longer, the gate command of the self-extinguishing element of the dynamic braking device is turned off when the input power is turned off. I am anxious and there is a problem in reliability.
(B) The dynamic braking device requires a transformer or a power supply unit as a control power supply to drive the self-extinguishing element, which has problems in cost and space.
[0006]
[Means for Solving the Problems]
In view of the above-mentioned points of the present invention, the power supply of the dynamic braking device is provided as one output of the control power supply of the inverter unit, and the brakes of the commander 53, the comparator 54, the driver 55, and the like are provided. The circuit portion is configured to be incorporated into the inverter unit, and the dynamic braking device itself is specially configured.
[0007]
[Action]
With such a solution, it is possible to operate as follows.
In other words, the control unit in the inverter unit obtains the drive power of the dynamic braking unit, and further obtains the signal output of the dynamic braking function. Therefore, the braking resistor and the self-extinguishing element as the dynamic braking device are provided outside the inverter unit. Is provided, and only the gate command is supplied from the inverter unit to the self-extinguishing element, whereby the power generation braking function can be achieved.
Hereinafter, the present invention will be described in detail with reference to the drawings.
[0008]
【Example】
FIGS. 1 and 2 show an embodiment of the present invention shown in FIGS. 6 and 7, wherein 2 'is an inverter unit and 5' is a dynamic braking device.
Here, the inverter unit 2 'is different from the inverter unit 2 in the control power supply 26 and the control unit 27', and is provided with a power generation braking control unit 29 comprising a command unit 291, a comparator 292, and a gate driver 293. .
FIG. 3 shows an example of the dynamic braking device 5 'of FIG. 1. The dynamic braking device 5' includes a transistor 56 as a self-extinguishing element and a snubber circuit 57 arranged in parallel with the transistor 56. It becomes.
[0009]
That is, in FIGS. 1 to 3, in addition to the inverter control circuit, the control unit 27 obtains the control power supply A102 from the control power supply 26 ′ which receives the intermediate DC voltage A101 and receives the detected intermediate DC voltage A101. It has a built-in dynamic braking control unit 29 that generates a braking command A103 at a predetermined voltage or higher and provides a gate driving signal A104 as a gate command to a dynamic braking device 5 'outside the inverter unit 2'.
A braking resistor 6 and a power braking device 5 'are provided outside the inverter unit 2', and the transistor 56 of the power braking device 5 'is driven by a gate drive signal A104 output from the power braking controller 29.
[0010]
FIG. 4 shows a dynamic braking device 5 '.
FIG. 4 shows an example of an assembling structure of the power generation braking device, in which 58 is a printed wiring board in which a snubber circuit 57 is housed, and 59 is a cooling fin to which a transistor 56 is attached.
That is, in the dynamic braking device 5 'shown in FIG. 4, the transistor 56 is arranged on the cooling fin 59 suitable for the braking capacity, and the printed wiring board 58 of the snubber circuit 58 is mounted.
As described above, the power generation braking device 5 'is a device having a simple configuration in which the gate drive signal A104 is transmitted from the inverter unit 2' and can be used.
[0011]
FIG. 5 shows another example of the dynamic braking device, wherein 5 "is a dynamic braking device, 57 'is a snubber circuit, and 58' is an integrated equipment mounting body.
In other words, it is apparent that the dynamic braking device 5 ″ has the transistor 56, the snubber circuit 57 ′, and the like mounted on the integrated mounting body 58 ′, and can be used similarly to the dynamic braking device 5 ′ shown in FIG. is there.
[0012]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(B) The gate power supply of the self-turn-off device for power braking when the inverter power is turned on and off has been stabilized, improving reliability.
(B) The dynamic braking control can be software-processed in the same place as the inverter control section, and the coordination between inverter overvoltage and regenerative stall prevention protection has been achieved, improving reliability.
(C) Since only one gate power supply is provided on the hardware, the cost of the inverter unit is little increased, and the cost is greatly reduced because only the self-extinguishing element is provided outside.
(D) The dynamic braking device can be selected according to the desired amount of braking, and the cost can be reduced in terms of application.
[Brief description of the drawings]
FIG. 1 is a system diagram showing one embodiment of the present invention.
FIG. 2 is a partial circuit diagram illustrating an example of a dynamic braking control unit in FIG. 1;
FIG. 3 is a partial circuit diagram illustrating an example of the dynamic braking device of FIG. 1;
FIG. 4 is a partial configuration diagram showing an example of the assembly structure of FIG. 3;
FIG. 5 is a partial circuit diagram illustrating another example of the dynamic braking device of FIG. 1;
FIG. 6 is a system diagram showing a conventional example.
FIG. 7 is a partial circuit diagram showing the dynamic braking device of FIG. 6;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Inverter unit 2 'Inverter unit 21 Rectifier 24 Filter capacitor 25 Inverter 26 Control power supply 26' Control power supply 27 Control unit 27 'Control unit 28 Drive unit 29 Power generation braking control unit 3 Induction motor (motor)
Reference Signs List 4 frequency setting device 5 dynamic braking device 5 'dynamic braking device 5 "dynamic braking device 6 braking resistor A101 intermediate DC voltage A102 control power supply A103 braking signal A104 gate drive signal

Claims (1)

In an inverter device for converting an AC power supply to DC and converting the DC voltage to an AC voltage by an inverter to drive an electric motor,
The inverter device controls at least a rectifier 21 for converting AC to DC, an inverter 25 for converting the converted DC voltage to AC voltage, a driving unit 28 for driving the inverter 25, and the driving unit 28. An inverter including a control unit 27 ′, a control power supply 26 ′ that supplies power to the drive unit 28 and the control unit 27 ′ from the DC voltage, and a power generation braking control unit 29 that functions when power generation braking is required. Unit 2 ′, and
It is configured to include a dynamic braking device 5 ′ provided outside the inverter unit 2 ′ and a braking resistor 6 connected in series with the dynamic braking device 5 ′.
The dynamic braking device 5 'and the braking resistor 6 are connected to the DC voltage of the inverter unit 2',
Power-generating braking device 5 'is composed of only the snubber circuit 57 for it self-turn-off devices 56,
The control power supply 26 'is provided with a control power supply A102 for the dynamic braking control unit 29,
When in need of dynamic braking, the inverter apparatus that transmits the gate drive signal A 104 'from the power generation braking control unit 29 in the power-generating braking device 5' the inverter unit 2 to the self-turn-off device 56.

Images