JPS62285680A - Power unit operating method for driving hysteresis motor - Google Patents

Abstract

PURPOSE:To simplify operation such as the restart of service interruption by closing a switchgear for an inverter and a hysteresis motor by the result of the comparison of the output frequency of the inverter and the rotational frequency of the hysteresis motor. CONSTITUTION:When a commercial power supply 1 gives out, an opetation command and the closing signal of a switchgear 3 reach '0', and a hysteresis motor HM4 is brought to the state of free-running. When the commercial power supply 1 is recovered, the operation command reaches '1', and an output from a rate-of-change limiter 9 rapidly increases toward fHM+ f under the state in which the closing signal of the switchgear 3 reaches '0'. An output from a frequency comparator 8 reaches '1' under the state in which the output frequency fINV of an inverter 2 reaches fINV>=fHM, and the switchgear 3 is closed. Since the changeover signal of a changeover switch 11 reaches '1' at the same time as the closing of the switchgear 3, the inverter 2 subsequently operates at the fixed rate of change in response to a frequency command fref.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Object of the Invention] (Field of Industrial Application) The present invention relates to a method of operating a power supply device that drives a hysteresis motor.

(Prior Art) When driving a hysteresis motor (hereinafter referred to as HM) with a variable voltage variable frequency inverter (hereinafter referred to as VVVF), as shown in FIG.
2 to convert the desired voltage to 1 frequency and use that power to convert HM
4 is moving yjA.

As a conventional power supply device, Tokoku No. 111 [56-98187] and the like have been proposed. Note that 3 is a switching device, which is closed when the input command is "1" and opened when the input command is "0".

Further, 5 is a speed detector for detecting the rotational frequency of HM 4, and VVVF2 is a generally well-known inverter, so a description thereof will be omitted.

(Problems to be Solved by the Invention) The commercial AC power supply 1 includes an energy storage element such as a large capacity capacitor inside the VVVF 2 as a countermeasure against short-term power loss, that is, momentary power failure is unavoidable. There is a problem in that this increases the size of VVVF2. In particular, VVVF of several KVA or less
And so on.

In many cases, the control power supply for the control circuit is branched off from the main circuit, requiring a large capacitor not only in the main circuit but also in the control circuit to prevent momentary power outages, and requiring uninterruptible control power supply. Met.

Also, due to the energy storage element inside VVVF2, V
Commercial AC power supply 1 for longer than the time that the output of VVF2 can be maintained
If there is a power outage, the switchgear 3 is opened and VVVF2
8M4 will be in a free running state. Then, after the power is restored to the commercial AC power supply 1, the VVVF2 will be restarted, but when the switching device 3 is opened, the output frequency fXNV of the VVVF2 must be higher than the rotational frequency f)18 of 8M4.

Power regeneration occurs from 8M4 to VVVF2, damaging VVVF2. In order to avoid this, the rotational frequency of 1(M4 should be measured by the speed detector 5 -fINV≧
f) The switchgear 3 must be closed after the IM. VV of HM during free running, not only during power outage
When rebooting with VF, all of the above problems arise.

The present invention has been made in view of the above, and it is an object of the present invention to provide a method of operating a power supply device for driving a hysteresis motor that does not require an energy storage element or the like as a countermeasure against instantaneous power outages.

[Structure of the invention]

(Means and actions for solving the problem) Before closing the switchgear 3, measure its rotation frequency fHM from the back electromotive force of 8M4, and set the frequency command input of VVVF2 to a frequency higher than fHP, so that f□NV≧fHM In this state, the switchgear 3 is closed, and the operation is thereafter performed according to a frequency command from the outside. This allows the commercial AC power supply 1 to be restored after a power outage.

Continuous operation is possible simply by inputting an operation command, eliminating the need for measures against instantaneous power outages.

(Embodiment) An embodiment of the present invention is shown in FIG. 1, where 6 is VVVF2
A frequency detector detects the output frequency f INV, 7 is a rotation speed detector that detects the rotation frequency of 8M4, 8 is f
A frequency comparator that compares INV and fHM and outputs “1” if f INV≧fHM, and outputs “uO” if f xNv< f HV, and 9 is a change that limits the rate of change of the signal. In the rate limiter, when the switching signal is 1'', it operates at the normal rate of change, and when it is 11011, the rate of change is large. 10 is a maximum value detector that outputs the larger of the two inputs; is a changeover switch and the changeover signal is LL I
11, select frequency command f PbO side, II
When O++, the output side of the maximum value detector is selected and output.

A time chart according to this embodiment is shown in FIG.

While operating at fINV"fo, if 1=1.0 and the commercial AC power supply 1 is out of power, the operation command and switchgear 3 closing signal will become 110++, and 8M4 will be in a free run state. When 1=11, the commercial AC power supply 1 will be in a free run state. When power supply 1 is restored, operation command becomes 1
1111, and the closing signal of the switchgear 13 becomes 110 +
In the positive state, the rotational speed fHM of the 8M4 is detected by the rotational speed detector 7 using the back electromotive force of the HM4. A frequency of 61 minutes is added to this detection signal to obtain f, M+Δf. This is to satisfy f XNV≧fHM as described later, and Δf may be approximately equivalent to 1 to 3 Hz. Starting frequency f5tart and fH when starting HM by maximum value detector 10
The larger one of M+Δf is output, and in Fig. 2, fHM
This is the case when +Δf≧f 1 tart. At this time, selector switch 11. The switching signal of the rate of change limiter 9 is 110 +1
Therefore, the output of the rate of change limiter 9 rapidly increases toward fl-IN+Δf. VVVF2 output frequency f
INH also rises accordingly, and f engineering NV≧
In the state of fHM, the output of the frequency comparator 8 becomes 1'', and the switchgear 3 closes.At the same time, the switching signal of the changeover switch 11 and rate of change limiter 9 becomes "1", so After this, VVVF2 operates at a predetermined rate of change according to the frequency command fFQt and returns to normal operation.Therefore, even if an operation command is given, unless fINV≧fHM, opening/closing position 3 will not close. So HM 4 Kara V
There is no backflow of power to VVF2, and the output of VVVF2 is initialized according to the state of 8M4 just by giving an operation command, so after the commercial AC power supply 1 is out of power and the power is restored, 8M4 can be used at any frequency. Even if the VVVF2 is free-running, it is possible to easily continue operation with just an operation command, so there is no need to have an energy storage element inside the main circuit and control circuit of VVVF2 as a countermeasure against instantaneous power outages. It also makes the work easier. Note that a frequency detector 62, a rotation speed detector 71, a frequency comparator 8. Since the maximum value detector lO is a well-known circuit, details thereof will be omitted. Further, as the rate of change limiter 9, the circuit example shown in FIG. 3 can be used.

Furthermore, the present invention is also effective when a backup system is formed using at least two inverter devices 12 within the broken line area in FIG. 1 as shown in FIG. 4. That is,
If the inverter system 121 breaks down for some reason while the inverter system 122 is in standby mode and the 8M4 is being driven by the inverter system 121,
The 8M4 can continue to operate simply by giving an operation command to the inverter system 122. The operation at this time is exactly the same as the time chart in Figure 2, and 1=1. When the inverter system 121 fails, it can be replaced by assuming that the operation command is input to the inverter system 122 when 1=10. In addition, the inverter system 121 has many H
This is also valid when M is connected.

In FIG. 1, the opening/closing device 3 is used for ease of explanation, but it goes without saying that the opening/closing device can be omitted by operating and stopping the inverter, as in the above-mentioned Japanese Patent Application No. 56-98187.

Furthermore, the control method of the present invention can be easily created using a microcomputer.

〔Effect of the invention〕

According to the present invention, the output frequency of the VVVF and the rotational frequency of the HM are compared, and the switching devices for the VVVF and the HM are closed based on the result, so operations such as restarting after a power outage are extremely simple. Therefore, there is no need for an energy storage element inside the VVVF as a countermeasure against instantaneous power failure, and the device can be made smaller. Furthermore, the present invention has the advantage that it can be directly applied to a backup system, and is particularly effective in a system in which HMs are individually driven using a large number of inverters.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a time chart showing the operation of FIG. 1, FIG. 3 is a diagram showing an embodiment of the rate of change limiter of FIG. FIG. 4 is a diagram showing an applied example of the present invention, and FIG. 5 is a diagram showing a conventional example. 1...Commercial AC power supply 2...VVV F3...
Switchgear 4...HM5...Speed detector
6... Frequency detector 7... Rotation speed detector 8.
...Frequency comparator 9... Rate of change limiter 10...
Maximum value detector 11...changeover switch 12, 121.122...inverter system 13~
15...Operation amplifier 16-21...Resistor 22...
・Capacitor 23...Switch agent Patent attorney Nori Ken Chika Yudo Hirofumi Mitsumata Figure 1 e-ta ttt2 Figure 3 m-++ J Figure 4

Claims (1)

[Claims] 1. A hysteresis motor, a power supply device for driving this motor, a control circuit that temporarily stops the operation of this power supply device at a desired time, and a control circuit that controls the back electromotive force of the motor or its counter electromotive force while the power supply device is stopped. In a hysteresis motor drive device comprising a detection circuit that detects at least one of the frequencies, when the power supply device is operated, a rotation frequency is detected from a back electromotive voltage of the hysteresis motor prior to operation, and when the rotation frequency is lower than or equal to the starting frequency. A method of operating a power supply device for driving a hysteresis motor, characterized in that the power supply device is operated at a starting frequency if the frequency is found, and at a detection frequency or higher if the frequency is higher than the starting frequency.