JPS60237881A - Controlling method of motor - Google Patents

Abstract

PURPOSE:To obtain a controlling method for reducing fifth and seventh harmonic waves by switching the output polarity of a bridge of drive switching elements on the basis of a variation in the induced voltage at nonenergizing time and setting a nonenergizing zone to approx. 30 deg. of electric angle. CONSTITUTION:In a commutatorless motor having a semiconductor commutator including a plurality of switching elements 6-11 connected in a bridge, a data generator 14 which produces an output signal at every 30 deg. of electric angle on the basis of an output signal output from a position detector 5. When the output polarity of one phase of a bridge is switched between positive and negative, and a drive signal is supplied from a controller 15 to the elements 6-11 to set the nonenergizing zone of approx. 30 deg. of an electric angle. Further, a position detection signal is formed from a variation of an induced voltage generated when the stator windings 2-4 of the motor 1 is deenergized.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for driving an electric motor, and in particular, a control method when converting DC power into AC power and supplying the AC power to the electric motor. 1
-F7q i (7') f & /! -, - (b) Prior Art General Department As a conventional control method for electric motors,
There was a method as described in Japanese Patent No. 5038.

This publication describes [armature winding with neutral point non-contact drawing connection and 6
In a commutatorless motor having a semiconductor commienator device formed by three-phase bridge connection of semiconductor switching elements with control electrodes, the armature winding is located at a point other than the neutral point of the armature winding with reference to the negative power supply side. The magnet rotor is rotated by controlling the switching element group of the semiconductor communitator device based on three comparison signals whose phases are shifted by 120 degrees, which are obtained by comparing the magnitudes of the three terminal voltages. The energization waveform of the motor thus obtained was as shown in FIG.

In other words, of the three phases (U phase, The energized section, the next 120° section was energized in the negative direction, and the next 60° section M was a 5 Y me song, 1 thunderstorm, 1 E circle round day, a punishment.Other V The same waveforms are also configured for the phase and W phase, but the phases are shifted by 120° between each phase.

When such a three-phase alternating current is supplied to an electric motor, the harmonic components of the fundamental wave generated by such a waveform are such that the third harmonic is 0'', the fifth harmonic is approximately 20%, and the seventh harmonic is approximately 20%. The harmonics were approximately 14%, which caused problems such as vibrations in the motor, reduced efficiency, and torque pulsations.

(c) Purpose of the Invention In view of the above problems, the present invention provides a method of controlling a motor in which the waveform of current applied to the motor is changed to reduce the fifth harmonic and the seventh harmonic.

B) Structure of the Invention The motor control method of the present invention connects a plurality of switching elements in a bridge configuration, and drives the motor with the output of this bridge. The non-energized section when switching from energization or negative direction energization to positive direction energization is set to the front edge of 30 degrees in electrical angle, and the switching of the energization direction is based on the induced voltage change that occurs in the stator winding when the motor is not energized. By doing so, vibrations and noise of the motor caused by the fifth harmonic and the seventh harmonic are prevented.

(e) Examples Examples of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a schematic diagram showing an embodiment of the present invention,
In the figure, (1) is a three-phase DC brushless motor, and detects the U-phase, ■phase, and W-phase stator windings), (3), and (4) as well as the rotational position (electrical angle) of the rotor. It consists of a position detector (5). (6) to 0D are switching transistors (switch elements) and constitute a three-phase bridge. The outputs of this three-phase bridge are respectively connected to the stator windings (2), (31, (4)) of the motor (1).

a';t, a'a are DC power supplies, each with E(V)
It has a voltage of . (14) is a data generator,
Based on the output of the position detector (5) (details will be described later), that is, the rotational position (electrical angle) of the rotor of the motor (1), the output is sequentially switched from 61″ to 12″ every 30° electrical angle. It is. a9 is a transistor (6) to υ
It is a control unit that controls ON or OFF of the terminal ■
, (2), (to), (to), (Z), and ω are connected to the base terminals of transistors (6) to (IIJ), respectively,
The ON or OFF states of the transistors (6) to aD are controlled based on the output of the data generator. The ON or OFF states of the transistors (6) to (7) for the outputs "1" to "12" of the data generator (14) are set as shown in FIG.

This is when the non-energized section of the output waveform obtained from the three-phase bridge when switching from positive direction energization to negative direction energization or from negative direction energization to positive direction energization is divided by 300" in electrical angle. By setting the non-energized section to 30°, the theoretical harmonics, especially the 3rd harmonic, are reduced to 0" and the 5th harmonic.
The harmonics can be set to about 5% and the 7th harmonic to about 4%.

The electric motor and control device configured as described above are equipped with transistors (6
) to the ON or OFF states of the rings are sequentially switched to maintain the rotation of the rotor. Is the rotational position of the rotor between 0 and 30 degrees in electrical angle? r pattern turning 1. Data of 61" is output to IKI (Iggy Maro A Miko II jl Kiyoshi) 1 1 1 nail bowl IKI, and based on this data, the transistor (6
) to circle are respectively ON, OFF, OFF, ON, ON, O
It becomes FF state and V-U voltage is 2E [V], W-Vtt
JE bar 2 E [: V ), U - W voltage is O [
v]. Next, when the rotor rotates and the output data of the data generator 04) switches to 2", the transistors (6) to α
1) are ON, OFF, OFF, ON, OFF, OFF respectively.
It is in the F state, the V-U voltage is 2E [v], the W-V voltage is the stator winding (41 (W phase) is de-energized, and the stator windings (2), (3), (4) Since it has the same potential as the neutral point of , this voltage becomes -E [■].

Considering the W-U voltage in the same way as the W-■ voltage, this voltage becomes -E[V]. , When the rotor further rotates and the output data of the data generator 04) switches to 3'', the transistors (6) to (iD turn ON, OFF, OFF, ON, respectively).
It becomes O'FF and ON state, and the V-U voltage is 2E (V),
The V-W voltage is o (the vlw-U voltage is -2E[:V:].Then, the data of the data generator I is sequentially changed from ``3' to ''4'' according to the rotational position (electrical angle).・→・・・１２
As shown in Fig. 2, the ON or OFF state of the transistor (6) to αυ and the UV voltage, V-W voltage, and W-U voltage change. It is something.

The rotor continuously rotates due to the magnetic field generated by such an applied voltage and the rotational inertia of the rotor.

The 3rd harmonic, 5th harmonic, and 7th harmonic that occur when driving the motor with such applied voltage are 0% each.
It is possible to suppress noise and vibration generated from the electric motor and improve operating efficiency.

As described above, the data of the data generator (14) may be sequentially switched in accordance with the rotation and position of the rotor.

The operation of the position detector (5) which detects the rotational position of the rotor and outputs a signal to the data generator α force will be described below with reference to FIGS. 3 and 4. This position detector (51) detects each transistor (6) to (1) based on the induced voltage (voltage change shown by the dotted line in FIG.
The ON or OFF state of 1) is output as a miscellaneous signal to the data generator α4. This change in induced voltage is “O(V)”
A signal is output based on the flowchart shown in FIG. 4. Furthermore, this change in induced voltage is
o(v)'' is detected by using a comparator to detect when the change in induced voltage switches from positive to negative or when the change in induced voltage switches from negative to positive. Therefore, measure the time (10) from when the data is switched until the change in induced voltage passes 'O[V]'', and when the change in induced voltage passes 0[V]''. The time measurement is started again from , and when t≧(1+A)to'' is reached, a signal is output to the data generator side. After this, time measurement is started again, and when "t≧2(1+k)to' is reached, a signal is outputted to the data generator α again. Next, 'to=Q' is performed and the process returns to the beginning of the flowchart. be. Incidentally, the above constants are set to arbitrary integers according to the load attached to the electric motor. To explain this operation again based on Fig. 3, first, the time (to) from when the output of the data generator I becomes 1" until the change in induced voltage passes 60 [■]" is measured. do. At the same time, a signal is output after (1+A) to time from the time when this change in induced voltage passes through "o(v)", and the output of data generator I is switched to ON or OFF of transistors (6) to (111). OFF
Switch the state of. Next, from the time the output of the data generator (141) becomes 92', 2(1+k)t.

Afterwards, the signal is output again and the data generator side output is switched from 2'' to 63''. Next, when the output of the data generator (14) reaches 3", time measurement starts, and the same operation as above is performed to determine the time it takes for the induced voltage to pass 1" (10CV). Repeat this to sequentially change the output of data generator I from ``4'' to 5''...12'' to 1''
...and so on.

As described above, if the motor is driven using the control method of the present invention, the ratio of the fifth harmonic and the seventh harmonic to the fundamental wave applied to the motor can be reduced. 630°'', but it is not limited to this, and a harmonic suppression effect can be obtained sufficiently if it is between about 20' and about 42°.This is due to the basic waveform as shown in Figure 5. The 5th harmonic and the 7th harmonic when
It can be understood from the value that harmonics occupy with respect to the fundamental wave. In other words, these values are within about 5%.

(f) Effects of the Invention In the motor control method of the present invention, a plurality of switching elements are connected in a bridge configuration, and the output of this bridge drives the motor. When switching from directional energization or negative direction energization to positive direction energization, the non-energized section is set at around 30 degrees in electrical angle, and the switching of the energized direction is based on the induced voltage change that occurs in the stator winding when the motor is not energized. By doing so, the seventh harmonic can be suppressed while obtaining the same output as the amplitude modulation method without changing the basic circuit configuration such as the bridge circuit, and the vibration and noise caused by this harmonic can be suppressed. At the same time, the rotational position of the rotor is detected based on the change in the induced voltage that occurs in the stator winding when it is not energized, and the direction of energization to the stator winding is switched, so there is no need for a special rotor position detector. Electric motors can be made smaller, lighter, and simpler.

That is, the number of vibration and noise generating parts of the motor is reduced, and together with the reduction of the fifth and seventh harmonics, it is possible to obtain a motor with less vibration and noise.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing an embodiment of a motor using the control method of the present invention, Fig. 2 is an explanatory diagram showing the applied voltage when using the embodiment of the present invention, and Fig. 3 is the same. A field diagram showing the applied voltage when using the embodiment of the present invention, Fig. 4 is a flowchart showing the operation of the position detector shown in Fig. 1, and Fig. 5 shows the basics when using the present invention. Fig. 6 is a waveform diagram showing the applied voltage when driving the motor using the conventional method. (11...Motor, (5)...Position detector , (6
) to αυ...Transistor, α...Data generator, (151...Control unit. Applicant: Sanyo Electric Co., Ltd. and one other representative Patent attorney: Yasuo Sano Figure 1 Figure 6

Claims (2)

[Claims] (1) Connect multiple switching elements in a bridge shape,
In a device that drives an electric motor with the output of this bridge,
When switching from positive direction energization to negative direction energization or from negative direction energization to positive direction energization with the output of one phase of this bridge, the non-energized section is approximately 30 degrees in electrical angle, and furthermore, this switching of the energization direction is done when the motor is de-energized. 5. A method for controlling an electric motor, characterized in that the control method is performed based on changes in induced voltage occurring in a stator winding at a time. (2) The method for controlling an electric motor according to claim 1, wherein the non-energized section is set at an electrical angle of about 20° to about 42°.