JPH0591772A - Inverter device - Google Patents

Abstract

PURPOSE:To reduce the size of an inverter device as a whole and increase the braking force of the device by forming a braking resistance for absorbing regenerated power of a meandering-shaped resistance wire, cooling the braking resistance with a cooling fan which is also used for cooling an exothermic body, such as a main circuit switching element, etc., and housing them in the enclosure of the inverter device. CONSTITUTION:This inverter device is constituted of a rectifying section, smoothing capacitor, inverter section, braking resistance for absorbing regenerated power from a load induction motor, switching element, etc. In this inverter device, the resistance 4 is formed of a meandering-shaped resistance wire and housed in the enclosure of the inverter device together with its cooling fan 11. In addition, the fan 11 is arranged in the enclosure so that the fan 11 can be used for cooling a heating element 12, such as a main circuit switching element, etc., also. Therefore, an inverter device which is increased in the braking force against the load induction motor by increasing the regenerated power absorbing capacity and, at the same time, which is reduced in size as a whole can be constituted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device in which the absorption capacity of regenerative electric power from a load induction motor is increased to enhance the braking force for the electric motor.

[0002]

2. Description of the Related Art The capacity of a braking resistor in an inverter device is determined by the total inertia constant of a load rotating system including the motor and a required deceleration characteristic in order to obtain a required braking force for the load induction motor. Is determined as a value that can absorb the regenerative power of the maximum value. Therefore, the resistance capacity is generally large, but the required capacity is large particularly when the induction motor driving a heavy inertia load such as a centrifugal separator or a turbo pump is targeted. Therefore, as a conventional inverter device of this type, there is known a device in which the braking resistor is separately provided outside the box body of the inverter device for heat radiation.

[0003]

However, in the conventional inverter device as described above, in which the braking resistance is externally installed, the braking resistance is of large capacity and large size and requires a large installation space. The entire device had to be large and expensive. In view of the above, the present invention changes the shape of the braking resistor and stores it in a box of an inverter device together with its cooling fan, thereby enhancing the braking force for the load induction motor and increasing the regenerative power absorption capacity. It is an object of the present invention to provide an inverter device which is compact and inexpensive as a whole device.

[0004]

In order to achieve the above object, an inverter device of the present invention comprises a rectifying unit for rectifying an AC input, a capacitor for smoothing a rectified voltage of the rectifying unit, and a smoothing voltage by the capacitor. And a switching resistor that is connected in series to the resistor and a braking resistor for absorbing regenerative electric power from the load induction motor of the inverter, and a switching element that connects and disconnects the energization path. In an inverter device comprising a braking circuit in which a series connection of both is connected in parallel to the capacitor, the braking resistor is composed of a meandering resistance wire, and is arranged in the box of the inverter device together with its cooling fan. Then
Further, the braking resistor is arranged on the discharge side or the suction side of the cooling fan, and the cooling fan is also used for cooling a heating element such as a main circuit switching element in the inverter device.

[0005]

With respect to the miniaturization of the inverter device which enhances the braking force of the inverter device, which converts the regenerative electric power from the induction motor into heat by its braking resistance and absorbs it to give the braking force to the motor, the heat capacity of the braking resistor is reduced. It is necessary to reduce the size with increase and store it in the inverter device box. The present invention aims to reduce the size and increase the heat capacity of the cooling fan by air-cooling with a cooling fan while forming the braking resistance with a resistance wire having a meandering shape, and further to the discharge side and the suction side of the cooling fan. By accommodating both the braking resistor and the cooling fan in the inverter device box so that the braking resistor and the heating element such as the inverter main circuit switching element are arranged in the inverter device box, respectively, downsizing and control of the entire inverter device can be achieved. It is intended to increase power.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIG. 1 (a), which shows a layout of devices in an inverter device box, FIG. 1 (b) is a perspective view of a braking resistor assembly, and FIG. It will be described with reference to a circuit diagram. First, in FIG. 2, 1 is an AC input rectifying unit, 2 is a rectifying voltage smoothing capacitor, 5 is an inverter unit having a bridge structure in which a switching transistor having an antiparallel diode is an arm element, and 6 is an output AC of the inverter unit. Is an induction motor that is operated at a variable speed by. Further, 4 is a braking resistor, which absorbs regenerative electric power that is regenerated from the electric motor 6 during deceleration control via the inverter unit 5 and accumulated in the smoothing capacitor 2 to increase its terminal voltage by heat consumption. 3 more
Is a transistor that performs a switching operation, receives a command signal from a voltage detection unit (not shown) that detects the terminal voltage of the capacitor 2, conducts when the terminal voltage increases, and energizes the resistor 4 to supply the regenerative power. It is something that consumes.

Next, in FIG. 1 (a), 10 is an inverter device box, 10a is a ventilation louver of the box, 11 is a cooling fan for the braking resistor 4 arranged on the discharge side,
Reference numeral 12 is a set of heating elements such as transistors and diodes of the inverter section 5, and reference numeral 12a is a cooling fin for the heating elements, which is arranged on the suction side of the cooling fan 11. Further, as shown in FIG. 1B, the braking resistor 4 is formed by a resistance wire which is stretched around the resistance mounting legs 4a so as to meander between a plurality of insulating struts and effectively radiates heat.
It is arranged as shown in FIG.

[0008]

According to the present invention, a rectifying unit for rectifying an AC input, a capacitor for smoothing a rectified voltage of the rectifying unit, and an inverter unit for receiving a smoothed voltage by the capacitor and outputting a required AC. A braking resistor for absorbing regenerative electric power from the load induction motor of the inverter section and a switching element connected in series to the resistor and connecting / disconnecting its energization path, and a series connection by both is connected in parallel to the capacitor. In an inverter device comprising a braking circuit, the braking resistor is formed of a meandering resistance wire, and is arranged in the box of the inverter device together with its cooling fan,
In addition, the braking resistor is arranged on the discharge side or the suction side of the cooling fan, and the cooling fan is also used for cooling a heating element such as a main circuit switching element in the inverter device, thereby making it compact and compact. It is now possible to store the resistance that has been increased and whose heat capacity has been increased in the inverter device box as a braking resistance, and by increasing the regenerative power absorption capacity, the braking force for the load induction motor can be strengthened and the entire device It is possible to obtain a small and inexpensive inverter device.

[Brief description of drawings]

FIG. 1 (a) is a layout view of devices inside an inverter device box showing an embodiment of the present invention, and (b) is a perspective view of a braking resistor assembly.

FIG. 2 is a block circuit diagram of an inverter device main circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rectifier 2 Smoothing capacitor 3 Transistor 4 Braking resistor 4a Resistor mounting leg 5 Inverter 6 Induction motor 10 Inverter device box 10a Louver 11 Cooling fan 12 Heating element 12a Cooling fin

Claims (2)

[Claims] 1. A rectifying unit for rectifying an AC input, a rectifying capacitor for smoothing a rectified voltage of the rectifying unit, an inverter unit for inputting a smoothed voltage by the capacitor and outputting a desired AC, and a load induction of the inverter unit. A braking resistor for absorbing regenerative electric power from an electric motor and a switching element connected in series to the resistor and connecting / disconnecting a current-carrying path, and a braking circuit in which a series connection by the both is connected in parallel to the capacitor. In the inverter device, the braking resistance is composed of a meandering resistance wire and is arranged in a box body of the inverter device together with a cooling fan thereof, and the braking resistance is arranged on a discharge side or a suction side of the cooling fan. An inverter device having a configuration. 2. The inverter device according to claim 1, wherein
An inverter device, wherein the cooling fan is also used for cooling a heating element such as a main circuit switching element in the inverter device.