JPH05184158A - Inverter unit - Google Patents

Abstract

PURPOSE:To produce regenerative brake force and to make it possible to store regenerated power in a battery or the like by providing means for storing regenerated power in a battery or the like in order to apply regenerative brake on an AC motor. CONSTITUTION:Power regenerated from an AC motor 5 is stored in a capacitor 3 through a transistor bridge 4 functioning as a converter. A voltage detecting circuit 6 detects terminal voltage rise of the capacitor 3 and a controller 9 actuates a transistor 13 in a charging means 10 to charge a battery 1 with regenerated power. A current detector 14 detects current flowing into the battery 11 and the controller 9 disables the transistor 13 to protect the battery 11 and the transistor 13 against breakdown. In other words, terminal voltage rise of the capacitor 3 is suppressed by charging the battery 11 with regenerated power to obtain regenerative brake force and to make it possible to store regenerated power in the battery 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for performing variable speed control of an AC motor.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional inverter device having a resistor and a transistor for performing regenerative braking of an AC motor. In the figure, 1 is an AC power supply, 2 is a diode bridge for converting the AC supplied from the AC power supply 1 into DC, 3 is an electrolytic capacitor for smoothing, 4 is a transistor for inversely converting DC into AC and supplying the AC motor. The bridge 5 is an AC motor as a load of the inverter device,
6 is a voltage detection circuit for detecting the voltage across the capacitor 3, 7 is a resistor for consuming regenerative electric power, 8 is a transistor for supplying a current to the resistor 7, and 9 is a control device for the inverter device. It is a control device.

Next, the operation will be described. The alternating current supplied from the alternating current power supply 1 is converted into direct current by the diode bridge 2, and the capacitor 3 is charged and smoothed. Further, it is converted back into an alternating current of an arbitrary voltage and frequency by the transistor bridge 4 and supplied to the alternating current electric motor 5 as a load.

FIG. 4A shows the terminal voltage v1 of the capacitor 3 during regenerative braking. The regenerative power from the AC motor 5 causes the transistor bridge 4 to operate as a forward converter to charge the capacitor 3. At the point A in FIG.
The voltage detection circuit 6 detects that the terminal voltage has risen, and the control device 9 turns on the transistor 8 so that the resistor 7 consumes the regenerative power. The control device 9 keeps the transistor 8 on until the terminal voltage of the capacitor 3 is lower than v3 until point B in FIG. 4 (a). That is, by consuming the regenerative power in the resistor 7, it is possible to suppress the rise of the terminal voltage v1 of the capacitor 3 and obtain the regenerative braking force.

[0005]

Since the conventional inverter device is constructed as described above, the temperature of the resistor 7 rises due to the ON period of the transistor 8 as shown in FIG. 5, and the resistor 7 is ignited. Transistor 8 at point E to prevent
Has to be turned off (prohibited to be turned on), the terminal voltage v2 of the capacitor 3 exceeds the protection level of the inverter device at point F, and the variable speed control of the AC motor must be stopped. Further, there is a problem that the regenerative power is consumed as heat by the resistor 7.

The present invention has been made in order to solve the above problems, and an object thereof is to provide an inverter device which is provided with charging means for charging a storage battery or the like with regenerative electric power and which performs regenerative braking. To do.

[0007]

In order to obtain a regenerative braking force, an inverter device according to the present invention comprises a charging means for charging regenerative power to a storage battery or the like.

[0008]

The charging means according to the present invention makes it possible to obtain regenerative braking force by charging regenerative power to a storage battery or the like and store the regenerative power in the storage battery or the like.

[0009]

EXAMPLES Example 1. FIG. 1 is a diagram showing an embodiment of the present invention. In FIG. 1, 10 is a charging means for charging the storage battery or the like with regenerative power, 11 is a storage battery charged by the charging means 10, 13 is a transistor for supplying a current to the storage battery 11 in the charging means 10, and 14 is a storage battery 11. It is a current detector that detects the current flowing through the device. In the other figures, the components denoted by the same reference numerals as those of the conventional example are the same as or equivalent to those of the conventional example.

Next, the operation will be described. AC motor 5
The regenerative power from the transistor bridge 4 operates as a forward converter to charge the capacitor 3. The change in the terminal voltage of the capacitor 3 at this time is the same as that in the conventional example shown in FIG. 3, and at the point A in FIG. 4A, the voltage detecting circuit 6 detects that the terminal voltage of the capacitor 3 has risen, The control device 9 operates the transistor 13 of the charging means 10 to charge the storage battery 11 with regenerative power. The control device 9 controls the charging means 1 to the point B in FIG. 4A where the terminal voltage of the capacitor 3 is lower than v3.
0 is operating. Further, the current detector 14 detects the current flowing through the storage battery 11, and the controller 9 stops the operation of the transistor 13 of the charging means 10 to cause the storage battery 11 to operate.
Also, the transistor 13 is prevented from being damaged. That is, by charging the storage battery 11 with regenerative power, the terminal voltage v
This has the effect of suppressing the increase of 1 and obtaining the regenerative braking force. In addition, regenerative power can be stored in the storage battery 11.

In the first embodiment, the transistor 13 is used as the element of the charging means 10 for supplying a current to the storage battery 11, but other semiconductor switches such as thyristors may be used as the element, and the same effect as in the first embodiment is obtained. can get.

Example 2. FIG. 2 is a diagram showing another embodiment of the present invention. In FIG. 2, 12 is a storage battery connecting means, 1
Reference numeral 5 is a connection contact for connecting the storage battery 11 to the terminal of the capacitor 3 in the storage battery connecting means 12, and reference numeral 16 is a backflow prevention diode for preventing current from flowing into the storage battery 11 when the storage battery 11 is connected to the terminal of the capacitor 3. In the other figures, the components denoted by the same reference numerals as those of the conventional example are the same as or equivalent to those of the conventional example.

FIG. 4B shows the terminal voltage v4 of the capacitor 3 when the voltage of the inverter device is insufficient. When the voltage of the inverter device is insufficient due to a power failure or the like, it is necessary to stop the variable speed control of the AC motor by lowering the terminal voltage of the capacitor 3 and lowering the protection level of the inverter device at point D as shown by v5 in FIG. 4 (b). It was Therefore, at the point C, the voltage detection circuit 6 detects that the terminal voltage of the capacitor 3 has dropped, and the control device 9 causes the connection contact 15 of the storage battery connection means 12 to connect.
Is operated to connect the storage battery 11 to the terminal of the capacitor 3. By connecting, it becomes possible to use the electric power charged in the storage battery 11 and suppress the drop of the terminal voltage v4 of the capacitor 3 to continue the operation of the inverter device. In addition, the backflow prevention diode 16 prevents a current from flowing into the storage battery 11 in reverse and enters a charging state.

[0014]

As described above, according to the present invention, since the inverter device has the charging means, the regenerative electric power is charged in the storage battery or the like to obtain the regenerative braking force and the regenerative electric power is stored in the storage battery or the like. The effect is that it becomes possible.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an inverter device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of an inverter device according to another embodiment of the present invention.

FIG. 3 is a circuit diagram of a conventional inverter device.

FIG. 4 is an explanatory diagram showing a terminal voltage of a conventional inverter device and a capacitor of the inverter device according to the present invention and other embodiments.

FIG. 5 is an explanatory diagram showing a temperature rise of a resistor in a conventional inverter device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Diode bridge 3 Capacitor 4 Transistor bridge 5 AC motor 6 Voltage detection circuit 7 Resistor 8 Transistor 9 Control device 10 Charging means 11 Storage battery 12 Storage battery connecting means 13 Charging transistor 14 Current detector 15 Connection contact 16 Reverse current prevention diode

Claims (1)

[Claims] 1. An inverter device for performing variable speed control of an AC motor, comprising: a charging means for charging a storage battery or the like with regenerative power for performing regenerative braking of the AC motor.