JPS5837790B2 - Rotor position detection circuit for commutatorless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotor position detector and a detection sensor circuit using an AC magnetic coupling method for a two-phase non-commutator motor.
The aim is to provide simpler detectors and circuits.

Conventionally, the minimum number of phases for a non-commutated motor is three, and if the number of phases is smaller than that, there will be a rotational position where the torque is zero, and self-starting may not be possible.

However, by setting the positive voltage period of the induced voltage waveform generated in the motor windings to 180 degrees or more in electrical angle, it is already possible to create a two-phase commutatorless motor that eliminates the rotational position where the generated torque is zero. .

The principle of this two-phase motor will be explained using FIGS. 1 to 3.

In FIG. 1, reference numeral 1 denotes a rotor magnet, which is magnetized such that it has an N pole, a S pole, and an unmagnetized portion at intervals of 120°.

2a and 2b are an A-phase stator winding and a B-phase stator winding, respectively, and the coil pitch is 120°.

Furthermore, both windings are arranged at 180° relative to each other.

Figure 2 shows the A-phase stator winding 2 when the rotor magnet 1 is rotated in the direction of the arrow with the positional relationship shown in Figure 1 as θ20.
Fig. 3 illustrates a magnetic flux linkage diagram of a.

Between θ=0 and 1200, the change in dφ/dθ is twice as large as that between θ2120° and 3600, and the sign is opposite.

Therefore, the waveform of the voltage ea induced in the A-phase stator winding 2a during constant rotation is as shown by the solid line in FIG.

Further, the waveform of the voltage eb induced in the B-phase stator winding 2b is as shown by the dotted line in the figure.

As can be seen from Figure 3, there is no period in which both ea and eb are negative, and therefore, as shown in Figure 3, the winding of the phase that is always generating a positive induced voltage is energized. This makes it possible to create a two-phase motor that always generates positive torque at any rotational position.

Next, a conventional rotor drinking device detector and circuit for a two-phase motor using an AC magnetic coupling method will be briefly described with reference to drawings.

FIG. 4 shows the structure of a conventional rotor position detector,
FIG. 5 shows the circuit.

First, in Fig. 4, 3a and 35 are sensor coils arranged at 18 electrical degrees, 4 is a sensor coil holder made of a magnetic material, and 5 is a magnetic material or conductive non-magnetic material. It is a convex polar disk consisting of a body and having a convex pole of 180 degrees in electrical angle.

Next, in Fig. 5, 6 is a sine wave oscillator with a frequency of several tens of Kflz to several hundred Kflz, 7 is an oscillation transformer with a neutral point tap on the secondary side, 8 and 9 are bias resistors, and 10 ,1
1, 12 and 13 are dividing resistors, 14 and 15 are diodes for half-wave rectification, 16 and 17 are smoothing capacitors, 1
8 is a waveform shaping circuit for obtaining a driving waveform, and 19 and 20 are output terminals.

Here, as shown in FIG. 4, a convex polar disk 5 is attached to the sensor coil 3a.
The voltages at various parts in FIG. 5 in a state where the convex poles are close to each other are explained in FIG. 6 using a vector diagram.

However, here, it is assumed that the convex polar disk 5 is made of a magnetic material.

If the convex pole disc 5 is made of a conductive non-magnetic material, the effect of the high frequency eddy current flowing in the convex pole disc 5 will cause the disc 5 to become smaller than when the convex pole disc 5 is made of a magnetic material. The effects of the convex portion and the concave portion are reversed.

The sine wave oscillator 6 causes the secondary winding of the transformer 7 to have a sixth
Voltages VA and vB as shown in the vector diagram in the figure are induced.

Furthermore, the voltages applied to the inductance and resistance of the sensor coil 3a are 1 and 2, respectively, and the voltage due to the inductance and resistance of the sensor coil 3b is 2
3 and v4, ■22v4, ■1+■3=constant, and when the convex pole portion of the convex pole disk 5 is close to the coil 3a, ■1>v3.

(If the convex pole is close to the coil 3b,
It becomes 3.

)The ratio between ■1 and ■3 is the ratio of the tonductance of the coils 3a and 3b.

Considering the above, if we draw a vector diagram of v1, v2, v3, ■4, it will look like Figure 6? Therefore, the potential at point E exists on the g line in the figure.

(When the convex pole portion of the convex pole disc 5 is close to 3b, the electric shock at point E comes to point E'.

) Furthermore, here, dividing resistors 10, 11 and 12, 13
Considering the potentials at the division points F and G, if the division ratio is appropriately selected, the voltage OF can be made much smaller than OG.

(When the convex pole portion of the convex pole disc 5 is close to the coil 3b, the voltage OG becomes much smaller than the OF.

) This situation can be expressed as a voltage waveform as shown in Fig. 7.

In the figure, a period A is a period in which the convex pole portion is close to the coil 3a, and a period B is a period in which the convex pole portion is close to the coil 3b.

The subsequent signal processing method is to perform half-wave rectification with diodes 14 and 15, smoothing with capacitors 16 and 17, and then obtain a rectangular wave output at terminals 19 and 20 with waveform shaping circuit 18.

The outputs from these terminals 19 and 20 turn the semiconductor switching elements ON-OFF and energize the stator windings.

In the conventional example described above, it is necessary to integrate the rotor position detector shown in FIG. Therefore, it is also disadvantageous in terms of assembly man-hours.

Therefore, a rotor position detecting device according to the present invention, which eliminates the rotor position detector by using a stator winding instead of the sensor coil and doubling the function of the sensor coil, will be described below with reference to the drawings.

FIG. 8 shows an example of a motor according to the present invention.

However, in the conventional example shown in Fig. 1, a 2-pole motor was used for convenience, but in the case of a 2-pole motor, the magnetic attraction force of the rotor magnet becomes unbalanced, which causes vibration, so it is practically recommended to use a 4-pole motor or more. There is a need to do so.

Therefore, the present invention will be explained using a four-pole motor.

In FIG. 8, 21 is a C-shaped rotor magnet, and 180
Two are placed at the ° position.

Each C-shaped magnet is magnetized to N and S poles at 120 degrees in electrical angle (60 degrees in mechanical angle).

Then, the portion corresponding to the unmagnetized portion of the rotor magnet described in the conventional example of FIG. 1 is left in a state in which no magnet is present.

22a and 22a2 are motor A phase stator windings, 22b
1 and 22b2 are B-phase stator windings.

Since it is a 4-pole motor, are the windings of each phase connected in series? Terminals U and 2 are protruding from the 2F fixed coil, and further from the connection point of the 2F fixed coil.

Also, the width of each coil is 120° in electrical angle (60° in mechanical angle)
゜).

FIG. 9 shows a rotor position detection circuit according to the present invention.

6 to 20 are the same as the conventional example shown in FIG. In the figure, 23, 24, 25 are coupling capacitors for coupling the stator windings 22at and 225, which are used in place of the sensor coil, with the sensor signal circuit, and one end of the capacitors 23 and 24 is connected to the sensor signal circuit. are connected to the midpoints U and V of the stator winding, respectively.

26 is an inductance for blocking high frequency signals.

27 and 28 are drive transistors, and 29 and 30 are high frequency bypass capacitors.

Next, the function of the sensor circuit will be explained when the rotor is in the horizontal position shown in FIG.

In FIG. 8, stator windings 22a1 and 22a2 are opposite the magnet portion, so stator winding 22b1
and 22b are those 2 facing the part without magnets.

The function of the sensor circuit will be explained with reference to FIG.

The high frequency voltage generated by the high frequency sine wave oscillator 6 is applied between A-0-B of the secondary winding of the transformer 7 as in the conventional example.
It appears as voltages A and VB.

VA and VB are applied to stator windings 22a and 22b1 via capacitors 23 and 24.

Here, the stator windings 22a2 and 22b2 have an impedance corresponding to a very large inductance for each high frequency component.
It does not appear towards the point.

Further, the capacitor 250 connected between the Z point and the E point allows the stator windings 22a and 22b1 to transmit high frequency signals to the sensor circuit as a substitute for the sensor coils 3a and 3b shown in FIGS. 4 and 5 of the conventional example. This means that they are combined.

The inductance 26 acts as a blocker for some high frequencies,
If there is no inductance 26, the high frequency signal will flow from point Z to the waveform shaping circuit 18 and the resistor 8 without passing through the capacitor 25, and the high frequency voltage signal will become extremely small.

The capacitors 29 and 30 are high frequency bypass capacitors, and if these capacitors were not present, the high frequency voltage would be reduced every time the 1 drive transistors 27 and 28 were switched on. A spike voltage is generated as noise in the signal.

Generally, the magnetic permeability of magnets is greater than that of air, so when the rotor positional relationship is as shown in FIG. 8, the inductance of the stator winding 22a is greater than the inductance of the stator wire 22b1. Therefore, according to the principle explained in the voltage vector diagram of the conventional example in FIG. 6, the voltage between OF in FIG. 9 becomes smaller than the voltage between OG,
Also, the positional relationship of the rotors is 90 in mechanical angle from the state shown in Figure 8.
When moved by .degree., the voltage between OF becomes larger than the voltage between OG.

Therefore, the voltage between OF and OG in FIG. 9 when the rotor rotates at a constant rate has the same waveform as in FIG. 7 explained in the conventional example.

Thereafter, this high frequency signal is half-wave rectified and shaped into a rectangular wave by the waveform shaping circuit 18, and then the driving transistor is energized.

(In the case of the positional relationship shown in FIG. 8, the transistor 28
All you have to do is energize it.

) Here, the values of capacitors 23, 24 and 25 are selected so that they have a small impedance for high frequency signals, and a large impedance for the switching frequency of the driving transistor (which is at most several kHz or less). By doing so, the influence of high frequency power on the circuit due to switching of the drive transistors 27 and 28 can be almost eliminated.

If the rotor is configured as shown in FIGS. 10 and 11, it is possible to obtain a higher frequency signal for detecting a locomotor position.

In FIG. 10, numeral 31 is a conductive non-magnetic material that is integrally attached to the rotor between two C-shaped magnets 21, and other parts are the same as those described in FIG.

Also, in Figure 11, 32 is an electrical angle of N at 1200 intervals.
It is a ring magnet with poles, S poles, and non-magnetized parts.
33 is a conductive non-magnetic plate pasted on the non-magnetized portion of the ring magnet 32.

If the rotor structure is as shown in FIGS. 10 and 11, the inductance of the stator windings 22a0 and 22a2 facing the magnet portion will be large and the conductivity will be The inductance of the stator windings 22b1 and 22b2 facing the non-magnetic material is
The effect of eddy current on the high frequency component of the conductive non-magnetic material reduces the inductance for the high frequency component.

Therefore, a larger rotor position detection signal can be obtained.

Furthermore, if a thin magnetic plate is attached to the magnet portion, the inductance of the stator windings 22a0 and 22b2 will further increase, and therefore a larger rotor position detection signal can be obtained.

According to the present invention described above, the stator winding also serves as a sensor coil, eliminating the need for a rotor position detector, which has great advantages in terms of motor configuration, space, assembly man-hours, and cost. has.

Furthermore, the circuit components that are increased by the present invention are only three small-capacity capacitors and an inductance with a small current capacity for blocking high-frequency signals, which hardly leads to an increase in the price of the circuit components.

In the description of the present invention, a four-pole motor was used as an example, but it goes without saying that such a configuration is possible even with four or more poles.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the basic principle of a two-phase commutatorless motor, Fig. 2 is a diagram of flux linkage change in the stator winding of the same motor, and Fig. 3 is an induced voltage waveform of the stator winding of the same motor. 4 is a sectional view showing the configuration of a conventional rotor position detector, FIG. 5 is a circuit diagram of the rotor position detection circuit, and FIG. 6 is a vector diagram of voltages at various parts of the rotor position detection circuit.
FIG. 7 is a voltage waveform diagram between OF and OG in FIG. 5, FIG. 8 is an explanatory diagram showing one embodiment of the rotor position detector in the two-phase non-commutated motor of the present invention, and FIG. 9 is The circuit diagram of the rotor position detection circuit, FIGS. 10 and 11 are explanatory diagrams showing other embodiments of the rotor position detector. 6...High frequency sine wave oscillator, 21...
Rotor magnet, 22a0, 22a2, 22b1, 22b2
...Stator winding, 23, 24, 25...
...Coupling capacitor.

Claims (1)

[Claims] 1. A magnetic rotor having a non-magnetic portion or a non-magnetic portion opposite to the magnetic poles of N and S poles, a two-phase stator winding connected in a star shape, and this tator winding attached. a high-frequency transformer having a primary coil excited by the output of the oscillator and a secondary coil whose neutral point is taken out; Four resistors R1, R2 + R3 + R4 are sequentially connected in series between both ends of the secondary coil, and one end of a bias resistor for giving DC pi and as to the neutral of the secondary coil of the high frequency transformer. and 1 of the stator winding. and a high frequency blocking reactor connected between the common connection point, and each of both ends of the secondary coil of the high frequency transformer is connected to the intermediate point of each phase winding of the stator winding via a coupling capacitor. ,
The common connection point of the stator windings and the connection point of the resistors R2 and R3 are connected via another coupling capacitor to superimpose a high frequency voltage on the stator windings, and the resistors R1 and R2 + The resistance values of R3+R4 are selected so that R1:R2=R4;R3, respectively, and the resistance R. 1. A non-commutator configured to use, as a rotor position detection signal, changes in the amplitude of the high frequency voltage generated between the connection points of R2, R3, and R4 and the neutral point of the secondary coil of the high frequency transformer. Motor rotor position detection circuit. 2. A rotor position detection circuit for a commutatorless motor according to claim 1, wherein a conductive non-magnetic material is attached to the non-magnetic portion or non-magnetic portion of the rotor magnet. 3. A rotor position detection circuit for a commutatorless motor according to claim 1, wherein a magnetic plate is attached to the magnetic pole portion of the rotor magnet.