JPS6212383A - Protecting device of inverter - Google Patents

Abstract

PURPOSE:To suitably control the entire controller by turning OFF an electromagnetic contactor of AC power source side when the DC output voltage of an inverter is not established even if the prescribed time is elapsed after a control is started. CONSTITUTION:An inverter 2 is connected through an electromagnetic contactor 3 and a reactor 4 with an AC power source bus 1, and a 3-phase induction motor 7 is controlled to be drive through a bus 6 and a variable voltage variable frequency controller 5 by the DC output. The inverter 2 is controlled to be switched through a voltage controller 10, a voltage controller 14 and a PWM controller 16 by a detection signal 9a of a DC voltage detector 9 and a voltage reference signal 11a of a voltage reference setter 11. In this case, a voltage setter 17 for deciding the specified value of the DC output voltage of the inverter 2, a time calculating comparator 18 and an exciter 19 of the contactor 3 are provided. Thus, even if the inverter 2 is abnormal and the voltage of the bus 6 does not rise even after the prescribed time after a control is started, the contactor 3 is turned OFf to disconnect the inverter 2 from an AC power source.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention provides a power factor adjustable pulse width modulation (P) for a power supply device.
The present invention relates to an inverter protection device in which a WM) type inverter is arranged and the voltage is boosted to keep the DC output voltage constant.

[Technical background of the invention and its problems]

Generally, motor control devices such as thyristor Leonard devices and cycloconverter devices that adjust voltage by phase control have the following problems.

Since the control current relative to the power supply voltage is controlled with a delay of the phase control angle, the power factor decreases and the power supply must supply reactive power to the control device. Therefore, in such a control device, the power supply capacity must be set to a value that is the sum of the reactive power capacity. Therefore, if the power supply capacity is large, a large amount of cost is required for the power supply equipment.

Therefore, in recent years, in order to improve the above-mentioned problems, various motor control devices with a good power factor have been proposed.

FIG. 2 is a circuit diagram showing an example of the configuration of this type of control device. In FIG. 2, 1 is an AC power supply bus, 2 is an inverter device whose AC input terminal is connected to this AC power supply bus 1 via an electromagnetic contactor 3 and a reactor 4, and 5 is a DC output terminal of this inverter device 2. A variable voltage variable frequency control device connected via a DC power supply bus 6. This variable voltage variable frequency control device 5 is provided as a power conversion device for controlling a three-phase induction motor 7. 8 is a smoothing capacitor connected to the DC power supply bus 6 and constitutes the main circuit of the rough voltage source inverter. Furthermore, 9 is a DC voltage detector connected to the DC power supply bus 6. On the other hand, 10 is a voltage controller to which the detection signal 9a of the DC voltage detector 9 and the voltage reference signal 11a of the voltage reference setter 11 are input, and 12 is connected to the output signal 10a of this voltage controller 10 and the AC bus 1. Voltage signal 13a of AC voltage detector 13
14 is a current control reference signal 12a of this current reference command device 12 and an AC power supply bus 1.
This is a current controller to which a current signal 15a of a current detector 15 provided in the current detector 15 is input. 16 is this current controller 1
PWM to which the voltage command value 14a output from 4 is input.
This PWM control device 16 is a control device that controls switching of the inverter device 2 .

Now, in FIG. 2, the variable voltage variable frequency control device 5
For example, by pulse width modulation (PWM) control using self-extinguishing switching elements such as GTR + GTO), a sine wave current control method that controls the current in a sine wave shape, and the excitation current component ° and torque component of the induction motor 7. It is possible to perform excellent control using a vector control method or the like. Furthermore, as described above, the inverter device 2 is also an inverter device using self-extinguishing switching elements such as GTR and GTo, and this inverter device 2 changes the voltage of the DC power supply bus 6 and the The current in the power supply bus 1 is controlled by vA as follows.

For example, the voltage reference signal 11 of the voltage setting device 11 in FIG.
When the detection signal 9a of the voltage detector 9 provided on the DC power supply bus 6 is input to the voltage controller 510, the voltage controller 1
0 inputs the deviation output 10a to the current reference command device 12 together with the voltage signal 13a of the voltage detector 13 provided on the AC power supply bus 1. In this current reference command device 12, a current control reference signal 12 of the inverter device 2 is synchronized with the phase of the phase voltage of the AC power supply bus 1 based on the deviation output 10a.
a, and this current control reference signal 12a and the current signal 15a from the current detector 15 provided on the AC power supply bus 1.
is input to the current controller 14. This current controller 14 outputs a voltage command value 14a to the PWM control device 16 in response to input of the current signal 15a, and upon receiving this signal, outputs a voltage command value 14a to the PWM control device 16.
The WM control device 16 performs switching control of the inverter device 2.

In this way, by controlling the current of each phase using the current control reference signal 12a as a sine wave reference synchronized with the phase of the phase voltage of the AC power supply bus 1, operation with a good power factor is possible. In this case, the voltage signal 13a is used as a sinusoidal reference and the output of the voltage control circuit 10) 10a determines the amplitude of the current control reference signal 12a.

Further, the configuration of the detector, controller, etc. differs depending on the number of phases of the AC bus 1. The inverter device 2 starts control after charging the smoothing capacitor 8 of the DC power bus 6 by turning on the electromagnetic contactor 3 provided on the AC power bus 1,
Due to the boosting action of the reactor 4 and the inverter device 2, the voltage of the DC power bus 6 is controlled to the value of the voltage reference signal 11a of the voltage setting device 11, and then, depending on the operating state of the load, the voltage of the DC power bus 6 is changed to the voltage reference signal 11a. The current of the AC power supply bus 1 is controlled so as to follow this.

By the way, in the motor control device as shown in FIG. 2, if the voltage of the DC bus 6 does not reach the specified value even after a certain period of time has passed after the inverter device 2 starts controlling, the inverter device 2 is in an abnormal state. Continuing control in this state is not desirable in terms of overall system control.

[Purpose of the invention]

The present invention was made to solve the above problems, and it checks the state of the DC output voltage from the AC power supply side inverter device over time, disconnects the power source side inverter device from the AC power source in the event of an abnormality, and An object of the present invention is to provide an inverter protection device that can appropriately protect the control device of the inverter.

[Summary of the invention]

The present invention provides a detector for detecting the establishment of voltage after starting voltage control on the DC output side of the inverter device on the AC power side, and when the DC voltage is not established even after a certain period of time has passed after starting voltage control, the AC power source Turn off the magnetic contactor on the side and disconnect the inverter from the AC power source.

[Embodiments of the invention]

Hereinafter, the present invention will be described with reference to an embodiment shown in the drawings. FIG. 1 shows an example of a circuit configuration of a control device that drives an induction machine as an electric motor.

Further, in FIG. 1, the same parts as in FIG. 2 are given the same reference numerals, and their explanations will be omitted.

In FIG. 1, 17 is a voltage setting device for determining the specified value of the DC output voltage of the inverter device 2, and 18 is a time calculation comparator that compares the signals 9a and 17a from the voltage detector 9 and the voltage setting device 17. be. If the signal 9a is smaller than the signal 17a even after a certain period of time has passed after the start of voltage control, a contactor off command signal 1 is sent to the excitation circuit 19 of the electromagnetic contactor 3 on the AC power supply side.
Comparator 18 provides 8a.

Next, the operation of the inverter protection device configured as described above will be described.

In FIG. 1, during normal operation, the inverter device 2 starts control after charging the smoothing capacitor 8 of the DC power bus 6 by turning on the electromagnetic contactor 3 provided on the AC power bus 1 as described above. , due to the boosting action of the reactor 4 and the inverter device 2, the voltage reference signal 11a of the voltage setting device 11
is controlled by the value of

That is, in FIG. 1, the setting value 17 of the voltage setting device 17
a is the DC bus 6'lt set by the normal charging voltage value of the DC bus 6 when the electromagnetic contactor 3 is turned on and the voltage reference signal 11a.
, is set at an intermediate value between the throne and the throne, so during normal operation, signal 9a
is larger than the signal 17a, the comparator 18 does not give the off command signal 18a to the electromagnetic contactor 3.

By the way, in the control of the inverter device 2, if the inverter device 2 enters an abnormal state due to a control malfunction or the like, the voltage of the DC bus 6 does not rise even after a certain period of time has passed after the start of control, and the signal 9a changes to the signal 17a. When the current is low, the comparator 18 gives a contactor off command signal 18a to the excitation circuit 19 of the electromagnetic contactor 3, turns off the electromagnetic contactor 3, and switches the inverter device 2 off from the AC power source. Release.

〔Effect of the invention〕

As described above, according to the present invention, in an inverter device in which a power factor adjustable pulse width modulation (PWM) inverter device is disposed in a power supply device, and the DC voltage is controlled to be constant by step-up control, If the DC output voltage of the inverter device is not established even after a certain period of time has passed after starting control, the inverter device on the power source side can be disconnected by turning off the electromagnetic contactor on the AC power source side. Even in the event of an abnormality in the power supply side inverter device, the entire control device can be appropriately protected.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an example of the configuration of a conventional inverter control device. 2...Power supply side inverter device 3...Magnetic contactor 8...Smoothing capacitor 9.
... Voltage detector 11 ... Voltage reference setting device 17 ... Voltage setting device 18 ... Time calculation comparator 19 ... Excitation circuit (7317) Attorney Noriyuki Chika (and 1 others)
name) Figure 1

Claims (1)

[Claims] A power factor adjustable pulse width modulation inverter device that is connected to an AC power source via a contactor and whose DC output voltage is controlled; a smoothing capacitor connected to the DC output side of this inverter device; An inverter protection device comprising: a time calculation comparator that compares a voltage at both ends with a set value for a predetermined time and outputs an off command to the contactor.