JPS5976191A - Controller for inverter - Google Patents

Abstract

PURPOSE:To restart an inverter by rotating the phase of a rotary position signal in the prescribed amount when the demagnetization of a permanent magnet rotor is discriminated from the input side interline voltage detection value and rotating speed detection signal of a synchronous motor, thereby magnetizing a permanent magnet by the inverter. CONSTITUTION:An interline voltage detection value VM produced through a full-wave bridge having a transformer T and diodes D1-D6, resistors 29, 30 and a condenser 31 and a speed signal absolute value ¦omega¦ obtained from a resolver control circuit 9 through an absolute value converter 32 are inputted to a differential amplifier 33. When a load motor 5 is demagnetized, the VM becomes small, the output V0(=¦omega¦-VM) of the amplifier 33 becomes large, thereby discriminating the demagnetization. The output of a flip-flop 39 at the time of V0>V becomes ''1'' by the comparison of V0 with the set value V in the comparator 38, a rotary phase angle cnnverter 40 varies the rotary phase angle in the prescribed amount to set to the phase of the direction that the armature magnetomotive force becomes coincident to the rotor magnetomotive force to flow an armature current. Then, the permanent magnet is magnetized.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an inverter control device for driving an AC screw motor, and in particular to a device for detecting and promptly detecting demagnetization of the rotor of a synchronous motor having a permanent magnet rotor. The present invention relates to an inverter control device that can control magnetization.

[Prior art]

FIG. 1 is a diagram showing the configuration of a conventional three-phase inverter that performs instantaneous sine wave current value control and its control device. The inverter consists of six gate turn-off thyristors connected in series between the positive and negative buses P and N of the DC source 1, respectively.
Electric valves consisting of GTO) and giant transistors (GTR)
It is composed of VF L Gz.

Each of these electric valves has a rectifying element Du e Dz
vDy, Dr e DW, Dz are anti-parallel #C connected M6
Sa f'L tiru.

Further, each connection point of the electric valves connected in series receives a load of 1 g @ the U phase of the machine 5 via a current detector 2 t 3 t 4.

Connected to phase ■ and W phase. A resolver 8 is directly connected to the permanent magnet rotor 7 of the load motor 5 to detect its rotational position and rotational speed lK. In response to this signal from the resolver 8, the resolver control circuit 9 outputs an electrical rotational position signal θ and a rotational speed signal ω using a known control method.

The rotational position signal θ is 3 when outputting an 8-bit signal.
It can be obtained with an accuracy resolved into 60'1256.

On the other hand, the rotational speed summer signal ω is output as an analog quantity having positive and negative polarities. However, although the rotational speed signal ω does not necessarily need to be output as an analog quantity, it will be described here as an analog quantity for the convenience of the following explanation.

The inverter control circuit 1o controls the load motor 5 by manually inputting the rotational position signal θ and the rotational speed signal ω from the resolver control circuit 9.

Next, a general method of controlling the load motor 5 will be explained.

Each phase current command value of the load motor 5 is used as the output of the inverter control circuit IO. U phase, ■phase.

The phase-current command values 1uHIv, Iw of the W phase and the outputs of the current detectors for each phase Iu+IvvIw are compared by input to comparators 11, 12, and 13, respectively. When each phase current command value Iu-Iv, Iw is larger than each phase current detector output Iu+IV+IW, the comparator output becomes level 1", and when smaller, it becomes level "0".

The comparator outputs enter amplifiers 14, 15, 16, and the isolated and amplified outputs 14a, 15a,
16a are positive side electric valves Gu, Gv, G, respectively.
control w. The comparator output is positive when the level is ``1''.
If the valves GugGvtGw and 1 are turned on, they will be turned off if the level is OI+.

! , the comparator outputs are logic NOT circuits 17, 18, 19
The insulated and amplified output signals 20a, 21a, 22a are inputted to amplifiers 20, 21, and 22, respectively, and control the negative side electric valves Gxr, Gle, and Gz. Since there are logical negation circuits 17, 18, and 19, the positive side electric valves Gu,
Gv, Gw and negative 0111 wake-up valve GX, Gy
+ Gz and each operate in an inverted state.

Note that resistors 23, 24, 25, 26, 27, 2
8 is used to give each comparator 11°12.131 a hysteresis characteristic. Each phase current command value Iu”r
Iv'' and Iw'' are controlled so that the direction of the rotor magnetic flux of the load motor 5 and the direction of the screw thread composite magnetomotive force are perpendicular to each other.

FIG. 2 is a waveform diagram showing the relationship between the rotational phase angle and each phase current command value. Rotational phase angle θ. At the position, the U-phase current command value Iu reaches the maximum V-phase and W-phase ball flow command value 1v', and I
w' is 1/2 of the U phase, i16, and the direction is negative. Therefore, the composite γL (first child magnetomotive force becomes Φa shown in FIG. 3, and the magnetic flux direction of the rotor at this time becomes Φ.

Next, a current control method using an inverter will be explained.

FIG. 4 is a diagram for explaining the state of DC control. The upper limit value of the hysteresis characteristic provided in the comparator 11 is assumed to be p, and the lower limit value is IB. The output 11a of the comparator 11 does not change when the output of the U-phase current detector 2 is between lp and IB. When the output 11a of the comparator 11 is at level "1", the electric valve Gu is turned on and the electric valve Gx is turned off. Comparator 1
When the output 11a of 1 is at level @071, the electric valve Gu is turned off and the drowsiness valve Gx is turned on.

A indicates the output screw pressure (phase voltage) of the inverter main circuit, which is 10E (V) when the electric valve Gu is on (Gx is off), and O when the electric valve Gu is off (Gx is on). (V).

Time t when the output Iu of the U-phase current detector 2 reaches the lower limit value In of the hysteresis of the comparator 11. The comparator output 11a is
becomes level “1” and electric valve Gu is on (Gx is off)
Therefore, the U-phase flow increases.

A time point t when the U-phase current increases and the output Iu of the U-phase magnetic current detector 2 reaches the lower limit of the hysteresis of the comparator 11, Ip,
The output 11a of comparator 1 becomes level ``0'', electric valve Gu is turned off, and GX is turned on, so the U-phase current decreases.The U-phase current decreases and the output of U-phase current detector 2 Iu
reaches the lower limit value III of the hysteresis of the comparator 11 at time t2. After that t. Repeat the same action as at point.

That is, magnetic current control with a constant ripple width is performed for the Giyodo command 1 dragon Iu1. Note that the same control is performed for the ■ phase and the W phase with a phase shift of 120 degrees, and a three-phase sinusoidal current having a constant ripple width is supplied to the load motor 5.

[Problems with conventional technology]

In an inverter control device using such a conventional three-phase current instantaneous value control method, there are problems such as inverter malfunction due to noise, etc., and demagnetization of the permanent magnet rotor when excessive current flows in the load motor (5). As a result, the torque of the Senkasha motive 5 may suddenly decrease and become unusable.

[Purpose of the invention]

An object of the present invention is to provide an inverter control device that can quickly magnetize a permanent magnet with an inverter and restart it even if a permanent magnet is demagnetized due to malfunction.

[Summary of the invention]

In order to achieve the above object, the present invention detects a rotational position signal and a rotational speed signal of a synchronous motor having a permanent magnet rotor, compares them with predetermined set values, and determines whether the inverter that drives the synchronous motor In an inverter control device equipped with an inverter control circuit that outputs a control command value, it is determined whether the permanent magnet rotor of the synchronous motor is demagnetized based on the detected value of the line voltage on the input side of the synchronous motor and the rotational speed signal. means for determining whether or not the permanent magnet rotor is demagnetized; and when it is determined that the permanent magnet rotor is demagnetized, the direction of the Nemiso magnetomotive force of the synchronous motor is made to match the direction of the magnetic flux of the permanent magnet rotor. and means for rotating the phase of the rotational position signal by a predetermined amount so that the rotational position signal is magnetized.

[Embodiments of the invention]

In the following drawings, the same parts as previously used are denoted by the same reference numerals, and the description thereof will be omitted.

FIG. 5 is a circuit diagram showing an embodiment of the present invention. The line voltage of the load (motor 5) is detected using a transformer T, and the secondary side of the transformer T is rectified by a full-wave bridge made up of diodes D and -D. Connect the output of the full wave bridge to resistor 2
9 and 30, and the ripple voltage is reduced by the capacitor 31 to obtain the ambient noise pressure detection value VM f. On the other hand, a speed signal absolute value 1ω1 is obtained from the speed signal ω of the resolver control circuit 9 via an absolute value conversion circuit 32. Next, the speed signal absolute value 1ω1 and the line voltage detection value VM are input to the fully differential amplifier 33, and the difference between the two is calculated. Furthermore, resistance: 34,
35, 36, and J7 are resistors for differential amplifier gain adjustment. Output V of the differential amplifier 33. is vo=lωl
-VM. Here, when the load motor 5 is not demagnetized, the output Vo of the differential amplifier 3 is adjusted to a very small value. However, when the load motor 5 is demagnetized, the line voltage detection value Vw becomes a small value for the same rotation speed, so the output voltage V of the differential amplifier 33. becomes larger. Therefore, this output voltage V
. By detecting the magnitude of , it is possible to determine whether or not the load motor 5 is demagnetized.

The output v0 of the differential amplifier 33 is set to the set voltage Vε by the comparator 38.
compared to ■When the relationship o>Vε is established, the output of the comparator 38 becomes level "1" and the flip-flop 39
7 and the output of flip-flop 39 is at level ''
1''.Here, when the output of the flip-flop 39 is at level ``0'', the rotation angles θ and θ' shown in FIG. The normal operation mode occurs when the magnetic force and the rotor magnetomotive force are perpendicular to each other.However, when the output of the flip-flop 39 reaches the level ``1'', the A permanent magnet can be magnetized by flowing an armature current in a phase that matches the magnetic force.

In this way, a rotational phase angle converter 40 is provided to change the rotational phase angle by a predetermined amount. A case where a ROM is used as a specific example of the rotational phase angle converter 40 will be described.

Input the rotational phase angle θ'& ROM address, and enter the upper address (if the rotational phase angle θ is composed of 8 bits, for example, A. Enter the conventional rotational phase angle θ in −A7, and enter the upper address is A8), that is, when the upper address A of the ROM is 0, it is sufficient to write the data of the rotational phase angle θ=θ'. When the upper address A of the ROM is I, it is sufficient to always write a rotational phase angle such that Kaiiso's magnetomotive force coincides with the direction of the rotor magnetomotive force.

Next, what kind of rotational phase angle should be written as data will be explained in more detail using FIGS. 6 and 7.

FIG. 6 is a waveform diagram showing the relationship between the rotational phase angle θ and each phase current command value. Phase angle θ. At the time of , the U phase current command value Iu is the maximum and the ■ phase, W @ Kamehara flow command ikIv, Iw
is the value of V2 and has a negative direction. Therefore, in the normal operation mode, the armature magnetomotive force shown in Fig. 7 is Φ8.The direction of the armature magnetomotive force that turns the demagnetized permanent magnet rotor into the magnetizing mode is shown in Fig. 7. In other words, in order to be in the direction of the ``Ul magnetic force 8'', the phase should be delayed by 90 degrees from the phase angle of the normal operation mode, so the phase angle θI
becomes θ-90°. That is, the output data of the rotary phase angle converter 40 may be written so that the phase angle is θ' (=θ−90°) when the most significant address is at the level “′1”.

[Effects of the Invention] As described above in detail based on the embodiments, in this invention, even if an excessive current flows through the load yt@4 due to a malfunction or the like and the permanent magnet rotor is demagnetized, the inverter can absorb it. Since the system is configured so that it can be magnetized, it is possible to resume operation within a short period of time, which has the advantage of reducing the impact on the load. In addition, there is no need to dismantle the load's vertical movement and re-do it again, and the labor-saving effect is extremely large.

When restarting the operation after magnetization, the flip-flop is reset to return the rotational phase angle to the original value, and the highest address input of the ROM of the rotational phase angle converter is set to level "'0".
'.

[Brief explanation of drawings]

Figure 81 is a circuit diagram showing the schematic configuration of a conventional synchronous drive inverter and its control device, and Figure 2 is a waveform diagram showing the relationship between the rotational phase angle and each phase current command value in the circuit of Figure 1. , Figure 3 is a diagram showing the phase relationship between the armature magnetomotive force and the rotor magnetomotive force, Figure 4 is a diagram explaining the relationship between current control by the inverter, and Figure 8 @ 5 is an example of this Hakumei. The circuit shown in FIG. It is a diagram showing the phase 1 male staff. 5...'fl load tJt m machine, 8...
9... Resol Reno (control circuit, 10... Inverter control circuit, 40... Phase conversion circuit. Applicant's attorney Kiyoshi Inomata 2 Figure; θ0 □θ Oval 3 Diagram 5'# Figure 16 (θo-90') Porridge 7 Figure 1

Claims (1)

[Claims] An inverter control circuit that detects a rotational position signal and a rotational speed signal of a synchronous motor having a permanent magnet rotor, compares them with predetermined set values, and outputs a control command value for an inverter that drives the synchronous motor. In the inverter control device, means for determining whether or not a permanent magnet rotor of the synchronous motor is demagnetized based on a detected value of an input side line voltage of the synchronous motor and the rotation speed signal; If it is determined that the synchronous motor is demagnetized, the rotational position signal is increased by a predetermined amount so that the direction of the armature magnetomotive force of the synchronous motor and the direction of the magnetic flux of the permanent magnet rotor are magnetized so as to match. An inverter control device characterized by comprising means for rotating a phase by .