JPS63316697A - Method for restarting inverter power source - Google Patents

Abstract

PURPOSE:To generate no excess current and restart a device quickly and smooth ly, by changing an inverter power-supply device restarting method, according to a case that there is induced voltage and a case that there is no induced voltage. CONSTITUTION:When a motor is re-operated (restarted)by a restarting voltage arithmetic circuit 15 and a re-starting frequency arithmetic circuit 16, then arithmetic is performed so that the output of an inverter power-supply device may be accommodated to the voltage and frequency of a connecting wire, and a PWM circuit 11 is controlled. After an accident happens on one of motors and it is separation-processed, the existence or non-existence of the induced voltage of the normal motors is detected by an output voltage detector 6. In case that there is the induced voltage, it is synchronized with the rotational frequency of the motors and the phase of the induced voltage to perform start ing. In the meantime, in case that there is no induced voltage, the output fre quency of an inverter 2 is set to be frequency stopped at the time of generating an accident, and output voltage is slowly heightened from 0V.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for restarting an inverter power supply, and more particularly to a method for restarting an electric motor subject to variable speed drive control when the load is temporarily stopped.

B1 Invention 1a Summary The present invention aims to improve the method of starting an inverter power supply in which an accident occurs in one of the electric motor groups that perform variable speed drive control, the accidental electric motor is separated from the control system, and then restarted. The induced voltage of the motor is measured, and if there is an induced voltage, the rotational frequency and induced voltage of the motor are synchronized with the output frequency and phase of the output voltage of the inverter power supply, respectively, and the restart is performed. If there is no voltage, set the output frequency of the inverter power supply to the frequency at stop and reduce the output voltage to O
By using a method of increasing from v.

This prevents the occurrence of overcurrent output from the inverter power source, and allows the disconnection of the accidental TM machine from the inverter power source and subsequent restart to be carried out safely and reliably.

C8 Prior Art Conventionally, various systems have been provided for applications in which electric motors are operated at variable speeds. In response to the demand for brushless motors in general industry and speed control comparable to 1M current motors,
The primary frequency control method, which performs speed control by combining a squirrel cage induction motor or synchronous motor with a static variable frequency power supply using a thyrisk inverter, has excellent control performance and efficiency, and is especially popular because it is easy to maintain. variable speed [1
! Seven machines are used, and the field of application is expanding to applications where maintenance is difficult due to poor atmosphere.

If an accident such as a short circuit or grounding occurs in 18 of the plurality of electric motors whose operation is controlled at variable speed by the inverter power supply device, an overcurrent will flow. The inverter power supply f detects this overcurrent and stops, but the inverter power supply does not.

Control of multiple electric motors that are under variable speed operation control stops, resulting in a system down state. As an improvement to this point, by blowing out the fuse installed in the motor that caused the accident, the motor in question is separated from the variable speed operation system, and the normal motor continues to operate.

FIG. 5 1al shows a method for disconnecting such an accidental motor M from the variable speed operation system of the inverter power supply. When the inverter power supply unit INV detects an overcurrent and stops, the normal electric motors M, . . . Mn continue to rotate due to inertia and generate electromotive force. This electromotive force causes a large current to flow into the failed motor M. Its magnitude is approximately the same as the full voltage starting current of the motor, and as shown in Figure 5, 1al, if the normal motor is n times, the current flowing into the fuse E will also be n times larger.
F is fused. On the other hand, an inverter power supply device restarts after a certain period of time after being stopped once, and current flows through all electric motors in the operating system. At this time, if the fuse EF had not blown, an overcurrent would flow again and the inverter power supply would stop! Motivation M,,M.

Current flows from the The above operation is caused by an accidental electric motor M.

This is repeated until the fuse RF is blown and disconnected from the inverter power supply. After the above fuse is blown, the inverter power supply is normal! Restart the engine for controlled operation.

D1 Problem to be Solved by the Invention However, by the above method, the faulty motor can be disconnected from the inverter power supply and controlled operation can be performed using the normal motor! When restarting, the inverter power supply may stop due to overcurrent again. The reason for this is that the output voltage and output frequency of the inverter power supply do not match the induced voltage and rotational frequency of the electric motor that continues to rotate due to inertia. In other words, there is a difference in frequency and phase between the induced voltage generated in the normal motor that remains after the fuse of the accident motor has blown and it has been disconnected from the inverter power supply and the output voltage of the inverter power supply. When restarting, an overcurrent flows, causing the inverter power supply to stop again.

In addition, when the motor M and the inverter power supply INV are controlled one to one by an individual control method as shown in Fig. 5 1bl, when the acceleration time of the motor is short, the output frequency of the inverter power supply is If the current becomes too large than the frequency, an overcurrent will flow in the same way as above, causing the inverter power supply to stop again.

The present invention has been made in view of the above-mentioned problems, and is a simple method for restarting an inverter power supply that can smoothly restart an inverter power supply connected to a load with an electric motor temporarily stopped due to overcurrent output. The purpose is to provide a method.

Means and operation for solving problem E1 The present invention measures the induced voltage and one rotation frequency of a normal motor after detecting a faulty motor, provides an output that matches the input conditions of the motor, and converts it into an inverter power supply device. This method measures the presence or absence of induced voltage in a normal motor, and if there is induced voltage, outputs the rotational frequency and induced voltage of the motor, respectively, from the inverter power supply. The restart is performed in synchronization with the frequency and the phase of the output voltage, and if there is no induced voltage, the output frequency of the inverter power supply is set to the frequency at the time of the stop, the output voltage is gradually increased from □V, and the restart is performed. It is characterized by starting by the above method.

What are the output voltage conditions provided by the inverter power supply?

Consistent with the input conditions of the π motor, the operation of the motor can be controlled, and the inverter power supply is prevented from generating overcurrent and restarted smoothly.

F. Embodiments Below, embodiments of the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows a circuit configuration diagram of an inverter power supply device according to an embodiment of the present invention. The main circuit of the inverter source device converts the DC power of the rectifier 1 into AC power using PWM control in the inverter main body 2, and supplies the AC power to the synchronous motor group 3 as a load. The control circuit is composed of circuits 5 to 13, which will be described later. That is, a cushion circuit 7 inputs a set frequency signal and makes the speed command signal at the start a gentle voltage value, and a function v/f pattern of the output frequency f of the inverter power supply and voltage V1 via the cushion circuit 7. Set and! a voltage pattern circuit 8 that controls the voltage to an optimum value according to the efficiency, starting characteristics, and load conditions of the motive group 3; an A4R circuit 9 that receives the output of the voltage pattern circuit 8 as input and controls the output voltage of the inverter power supply; A PWM circuit 11 which inputs the output signal of the R circuit 9 and a frequency setting signal via the cushion circuit 7 and performs pulse width control;
a pace driver circuit 12 that drives the power transistor of the main circuit 2 with the output signal of the M circuit 11;

It is provided between the input side of the pwM circuit 110 and the VR circuit 9 and the cushion circuit 7, and is controlled on/off by internal processing of the computer 14.

An output voltage detector 6 detects the voltage of the connection line l connecting the synchronous motor group 3 of the load and the inverter power supply, and outputs a voltage signal and frequency signals VM, MF proportional to this, and an output voltage detector 6 of the inverter power supply. Detect the output current Ia,
and an output current detector 5 equipped with a comparator for comparison with a set rated value.

The output of the detector 5 is input, and when the output current Xa exceeds 150% of the set value, a selection cutoff signal OCR is output to the PWM circuit 11 to stop the output from the PWM circuit 11 and cause a failure. It is composed of a detection circuit 13.

14 is a computer, and when the selection cutoff signal OC'R of the output current detector 5 is input, the internal processing shown in FIG. When a normal electric motor is restarted (picked up) by the process, the PWM circuit 11 is controlled by calculating to match the output of the inverter power supply to the voltage and frequency of the connection H.

Next, the operation of the above configuration will be explained based on FIGS. 2 and 3. FIG. 2 is a time chart for explaining this embodiment, and the horizontal axis shows time t1 to t, and the vertical axis shows the output current I of the inverter power supply, the voltage VM of the output line,
The output frequency fl and the output voltage VI are taken for 1 hour from t1 to 1.
The changes in each are feminized. FIG. 3 is a time chart for internal processing of the computer 14, in which the horizontal axis shows time t1 to t similar to that in FIG. 2, and the vertical axis shows processing contents. The operations within each time period from t1 to t will be explained separately.

11+ t l≦1<1. Now, if an accident such as an overload or a short circuit occurs in motor M in the synchronous motor group 3, and the output current increases, then the output current is increased.

is detected by the output current detector 5, and when it exceeds 150% of the large rated value, the fault detection circuit 13 outputs PWM times
A gate cutoff signal is issued at 1% 11, the gate of the inverter power supply device is cut off, and the inverter output voltage v of the inverter main body 2 becomes 0.

At the same time, an interrupt is generated in the computer 14 as shown in Fig. 3, and in this interrupt processing, the selected cutoff (hereinafter referred to as OCR) processing flag and OCR mode are set, and at the same time, the protection fuse 4a of the faulty motor M8 is blown. The time required for this (100 m5 in this embodiment) is set in a timer (not shown).

[In Figure 3, Min 1, (dl) 121 t
, ≦1<1. , then the timer set time [100mB]
When the time has elapsed, the first OCR flag is turned on [Figure 3 (b)
l:l0cR mode is cleared and normal motors M, other than the accident motor M,...Mfi are brought into the controllable operation system Processing to pick up residual voltage in order to enter C (hereinafter referred to as pick-up processing) to go into.

[Fig. 3te)'1 +31 t, ≦1<14. Then, the residual load voltage (induced voltage caused by inertial rotation of the synchronous motor) is detected by the output voltage detector 6, and the arithmetic processing unit calculates the voltage vH and one frequency f that are synchronized with the synchronous motor group 3 at the time of pickup.
H calculation is performed, relays RY, , RY are turned ON on the calculation side, and inputted to the PWM circuit 11 as a setting condition. 1=
At 1m, relay RY,,RY.

is restored to its original state and picked up, the gate cut-off is released, and the voltage vH is gradually increased to the set V/f pattern. [Figure 3 tθ] +41 t, ≦1<1. , then the inverter output voltage v
If the OCR mode does not occur when the output is increased to 1 and output frequency f, this indicates that the fuse 4a of the faulty motor M8 has blown and selective disconnection from the inverter power supply has been completed. However, if the OCR mode occurs again due to an overcurrent before the output voltage (2) is reached (FIG. 3(d)), the same processing operation as +11 above is performed.

+51 t , ≦1<1. , when the timer set time elapses, the output voltage detector 6 detects the residual load voltage V.

is detected, and it is calculated whether the average value VM is 5% or more. If the calculated average value VM is 5% or more, it indicates that the faulty motor M is selectively disconnected, and the above (2)
Processing operations similar to those are performed [Fig. 3 rcl, (el)]
, when the one-way average value VM is less than 5%, the inverter power supply is stopped as a "failure".

(61t, ≦t<'we, the same processing operation as in (3) above is performed.

(7) t, ≦1<1. , then the inverter output voltage v
The above (
When the same processing operation as in 4) is performed and the OCR mode occurs again, a "failure" stop is performed as a pick-up processing failure. [FIG. 3(f)] (81t m≦t, if OCRC-motor generation does not occur, the pickup process is completed and the normal operation of the electric motor M before the accident occurs is resumed.

By carrying out the selective disconnection process for the faulty motor as described above and restarting the inverter power supply thereafter, the controlled operation of the synchronous motor, which is the load, is performed smoothly.

On the other hand, if the induced load voltage is not detected by the output voltage detector 6, the output voltage I is gradually increased from Ov while keeping the output frequency f set at the time when the inverter power supply stopped. To prevent the output current Ia of an inverter power supply device from becoming an overcurrent at the time of restart.

In addition, the load motor and inverter power supply are one-to-one.
When the inverter power supply is installed and controlled in accordance with However, as shown in Figure 4, by calculating the phase correction signal Δθ' from the signals during acceleration and deceleration and performing arithmetic processing, it is possible to instantaneously shift the current phase, and the synchronous motor is connected to the load. It becomes possible to carry out smooth acceleration and deceleration in this state.

In implementing the present invention, the present invention is not limited to the above-mentioned embodiments. For example, the load motor of an inverter power supply device is not limited to a synchronous motor, but may also be a groove motor, and various other embodiments may be adopted. .

As described in detail of the G0 invention, the present invention provides a method for restarting the inverter power supply after an accident occurs in the motor 18 driven at variable speed by the inverter power supply, and the induced voltage of the normal motor is If there is an induced voltage, the system starts in synchronization with the rotational frequency of the motor and the phase of the induced voltage, so the output current of the inverter power supply is quickly and smoothly without overcurrent. A restart will be performed. If there is no one-way induced voltage, the output frequency of the inverter power supply is set to the frequency that stopped at the time of the accident] 8 wave numbers, and the output voltage is gradually increased from □V, so the overcurrent of the output current is reduced. This ensures that the system can be restarted quickly and reliably.

Brief description of the front side FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, and FIG. 2 is a time chart showing the processing operation of this embodiment.

FIG. 3 is an internal processing time chart of the computer, FIG. 4 is a diagram showing phase correction during acceleration and deceleration, and FIG. 5 is a diagram showing disconnection processing of the failed motor.

3...Synchronous motor 5M1...Fault motor, 4...
Fuse, 5... Output current detector, 6... Output voltage detector.

11... PWM circuit, 12... pace driver,
Ia...Output current of the inverter power supply, v...Inverter power supply output voltage, f...in/<-ta power supply output frequency, va...residual load voltage, VM...
Average value of residual load voltage.

Claims (1)

[Claims] If an accident occurs in one of the electric motors whose variable speed drive is controlled by the inverter power supply, the inverter power supply is stopped and operated intermittently after a predetermined period of time to disconnect and restart the failed motor. In the method for restarting an inverter power supply, the presence or absence of induced voltage in a normal motor is measured, and if there is induced voltage, the rotational frequency and induced voltage of the motor are adjusted to the phase of the output frequency and output voltage of the inverter power supply, respectively. The restart is performed in synchronization, and when there is no induced voltage, the output frequency of the inverter power supply is set to the frequency at the time of the stop, and the output voltage is gradually increased from O^V to restart. How to restart the inverter power supply.