JPH04340398A - Inverter - Google Patents

Abstract

PURPOSE:To properly control a braking means provided to a load regardless of the kind and the capacitance of a connected load by such a control that the action of a load braking means is released in a predetermined time after a stall preventing means is actuated. CONSTITUTION:A frequency command f* accelerates to a frequency setting f* by input of RUN signal. When the frequency command exceeds fLOW, LOW(L) is outputted from a low speed signal generator 11. Braking is still in a restriction; when an inverter carries constriction current to make the output of a current detector 13 exceed STL(L), stall functions and results in a deceleration control of a frequency. When it falls below STL (L) from a current level, it accelerates again. When a time T elapses after operation starts and during stall, braking control signal outputs release command. This process enables a proper control of the brake 6.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device.

0002

2. Description of the Related Art A conventional inverter device will be explained with reference to FIG.

As shown in FIG. 5, an AC power source 1 is connected to a rectifier 2.
The DC power is rectified by the smoothing capacitor 3, and the DC power output from both ends of the smoothing capacitor 3 is sent to the inverter section 4.
The AC power is converted into AC power to drive an AC motor (hereinafter referred to as a motor) 5. A brake 6 is added to the motor 5.

The inverter section 4 is controlled by a frequency setter 7.
According to the frequency reference from
The acceleration/deceleration control circuit 8 outputs the frequency command f, and PW
The M generation circuit 9 converts it into a PWM switching pattern, and the drive circuit 10 controls the inverter section 4. The low speed signal generator 11 is connected to the acceleration/deceleration control circuit 8.
receives the frequency command f from
Outputs LOW (L) when . The brake control section 12 is
Control is performed such that the brake is turned on by the LOW (H) signal input thereto, and the brake is turned off by the same LOW (L) signal.

FIG. 6 shows a control time chart. As shown in FIG. 6, the frequency command f is changed by inputting the RUN signal.
According to the acceleration/deceleration time setting, it accelerates toward the frequency setting f*. When the frequency command f exceeds fLOW, the low speed signal generator 11 outputs LOW (L), and upon receiving this output signal, the brake control section 12 releases the brake.

[0006] Next, the time of stopping will be explained. STOP
When (RUN(L)) is input, the vehicle decelerates according to the acceleration/deceleration time setting. When the frequency command f becomes smaller than fLOW, the low speed signal generator 11 outputs LOW (H
) level is output, and upon receiving this signal, the brake control unit 12 drives the brake. At this time, the motor 5 is in a free running state.

[0007]

[Problem to be Solved by the Invention] In this way, the motor 5
When controlling the brakes added to the
Depending on the settings, the motor 5's restricted current may flow too much.
There are problems such as tripping due to overcurrent or insufficient torque when the brake is released, and that it is necessary to adjust the fLOW setting depending on the type and capacity of the motor 5 connected to the inverter section 4.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an inverter device that can appropriately control a braking means provided on a load, regardless of the type and capacity of the connected load. be. [Structure of the invention]

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a converter means for converting an AC power source into a DC power source, and converts the DC power source converted by the converter means into an AC power source having an arbitrary frequency. In an inverter device for driving and controlling a load having a braking means using AC power from the inverter means, the inverter device has a current detecting means for detecting a current flowing through the inverter means, and a preset reference value. and the detection value from the current detection means, and depending on the comparison result, a stall prevention means for reducing the speed standard for the load and a stall prevention means for reducing the speed standard for the load, and a stall prevention means for reducing the speed standard for the load, and a stall prevention means for reducing the speed standard for the load, and a stall prevention means for reducing the speed standard for the load, and control means for controlling the operation of the braking means for the load so as to release the brake means after a predetermined time elapses after the stall prevention means operates.

0010

[Operation] According to the inverter device of the present invention configured as described above, the timing for releasing the braking means provided on the load can be obtained regardless of the type and capacity of the connected load. After releasing the means, an appropriate torque can be output.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an AC power source 1 is connected to a rectifier 2.
The DC power is rectified by the smoothing capacitor 3, and the DC power output from both ends of the smoothing capacitor 3 is sent to the inverter section 4.
The AC power is converted into AC power to drive an AC motor (hereinafter referred to as a motor) 5. A brake 6 is added to the motor 5.

The inverter unit 4 is controlled by outputting a frequency command f by the acceleration/deceleration control circuit 8 in accordance with the frequency reference from the frequency setter 7 and by inputting the RUN signal.
The WM generation circuit 9 converts the frequency command f into a PWM switching pattern, and the drive circuit 10 converts it into a PWM switching pattern.
and outputs LOW (L) when f≧fLOW. Furthermore, a brake control section 12 that controls the brake 6;
A main circuit current detector 13 that detects the current flowing to the inverter section, a stall level switch 14 that switches and outputs the stall reference depending on the state of the brake 6, and the output of the stall level switch 14 and the current detector 13. When the outputs are compared and the output of the current detector 13 is larger, the stall level detector 15 outputs an STL (H) level (STL signal).

The brake control section 12 controls the brake 6 using the STL signal and the current state of the brake 6 as parameters. Specifically, the brake control section 12 includes a delay circuit 19, an inversion circuit 20, an AND circuit 21, and an OR circuit 22, as shown in FIG. The delay circuit 19 is a circuit that generates a rising edge after a time T has elapsed from the rise of the stall signal STL. A truth table of the brake control section 12 is shown in FIG. Next, the operation of the inverter device of this embodiment configured as described above will be explained using FIG. 4.

By inputting the RUN signal, the frequency command f is
From the starting frequency, it accelerates toward the frequency setting f* according to the acceleration/deceleration time setting. Frequency command f is fLOW
, the low speed signal generator 11 outputs a LOW (
L) is output. At this time, the brake is still in the locked state, so a locking current flows through the inverter device, and when the output of the current detector 13 exceeds STL (L), the stall functions and the frequency is controlled to decelerate. When the current level falls below STL (L) due to the stall function, acceleration is resumed. When a time T has elapsed since the stall functioned for the first time after the start of operation, the brake control signal outputs a release command. When the brake 6 is released at one end, the next LOW (H)
The STL signal has no effect on brake control until the brake 6 is turned on. Further, the stall level reference is switched to STL (H) by the brake release signal.

In this way, by releasing the brake 6 in response to the stall signal from the load current when the motor 5 is restrained by the brake 6, it is possible to obtain an appropriate timing for releasing the brake 6 and an appropriate torque at the time of release. Can be done.

When stopping, the motor 5 is restrained by the brake 6 in response to a LOW (H) signal, and at the same time, the output of the inverter section 4 is brought into a free run state. Note that although this embodiment is configured using hardware, it can also be implemented using software.

[0018]

[Effects of the Invention] As explained above, according to the present invention,
Regardless of the type and capacity of the load connected to the inverter device, it is possible to obtain an appropriate timing for releasing the braking means for the load, and furthermore, it is possible to obtain an appropriate torque when the braking means is released.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention.

FIG. 2 is a detailed configuration diagram showing each configuration of the brake control section shown in FIG. 1;

FIG. 3 is a truth table in the brake control section shown in FIGS. 1 and 2.

FIG. 4 is a time chart showing control operations in an embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a conventional inverter device.

FIG. 6 is a time chart showing control operations in a conventional inverter device.

[Explanation of symbols]

1...AC power supply,
2... Rectifier, 4... Inverter section,
5... AC motor (motor), 6... Brake,
7...Frequency setter, 8...Acceleration/deceleration control open circuit, 9...PWM generation open circuit, 10...Drive open circuit,
11...Low speed signal generator, 12...Brake control section,
13... Main circuit current detector, 14... Stall level switch, 15... Stall level detector, 19... Delay circuit,
20...inversion circuit, 21...AND circuit,
22...OR circuit

Claims (1)

[Claims] 1. A converter means for converting alternating current power into direct current, and an inverter means for converting the direct current power converted by the converter means into an alternating current power having an arbitrary frequency, and an alternating current power source from the inverter means. In an inverter device that drives and controls a load having a braking means, a current detecting means for detecting a current flowing through the inverter means compares a detected value from the current detecting means with a preset reference value, and this comparison is performed. Depending on the results,
a stall prevention means for reducing a speed standard for the load; and a stall prevention means for reducing the preset reference value when the load braking means is operating, and controlling the operation of the load braking means. An inverter device comprising: control means for controlling the inverter to be released after a predetermined period of time has elapsed after the inverter is activated.