JPS6029360Y2 - Plasticless DC motor - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a brushless DC motor, and more specifically, each armature winding of a plurality of phases, for example, three phases, connected to a DC power supply via a separate control circuit, for example, a transistor type control circuit, and a permanent magnet. The present invention relates to a brushless DC motor that has a rotor and is configured to start and rotate the motor without having a rotor position detection mechanism.

As a conventional DC motor of this type, one shown in FIG. 3, for example, is known.

That is, 12
PNP type transistors TI, T2 . It is connected to the switch 14 through a control circuit including T3, and the positive pole of the DC power supply B is connected to the switch 14, and each of the armature windings 11, 12, 1
3 includes diodes D1, D2, . D3 is connected, and the anodes of these diodes D1 to D3 are both guided to a rotation speed detection circuit 15, and a rotation speed control circuit 16 is connected to the output stage of the circuit 15, while the output side of the circuit 16 is connected to a speed control circuit. It is known that the control circuit is connected to the control circuit through resistors R4, R5, and R6.

Here, the control circuit forms a circular chain circuit.

Further, the resistor R1 and the capacitors C1, R2 and C2, and R3 and C3 are used to delay the phase of the preceding stage, specifically, the phase of the AC voltage induced in each winding of the preceding stage by about 60 degrees.

Furthermore, C4, C5, and C6 are capacitors for cutting the direct current component in the previous stage.

When the switch 14 shown in FIG.
A current is cascaded through each armature winding 11, 12, 13 of the phase, which excites the permanent magnet rotor, causing it to oscillate.

When the rotor vibrates, the induced voltages α, β, γ (fourth
(see figure) is generated in each armature winding 11, 12, 13, and this induced voltage causes the rotor to rotate in a certain direction.
The rotational speed is detected by peak detection by the diodes D1 to D3, and the rotational speed of the rotor is controlled by the rotational speed control circuit 16 at the next stage.

However, in the conventional brushless DC motor described above, when the rotating shaft of the motor and a load with inertia (for example, the flywheel of a tape recorder, etc.) are connected to each other with a belt, the excitation of the motor and the load are balanced against each other. However, there is a problem in that the motor does not start if the motor does not match.

However, the present invention includes a permanent magnet rotor and multiple phase armature windings that are sequentially operated by output transistors, and while the rotor is rotated by the induced electromotive force caused by the application of an induced current to each winding, the rotor is rotated by each winding. A rotational speed control circuit is connected through the speed detection circuit, and a switching control circuit is connected to any one of the output transistors through a switching circuit, and the switching control circuit is connected to the rotational speed control circuit based on the output of the rotational speed detection circuit. The circuit is configured to control the operation of an output transistor connected to a switching control circuit via a switching control circuit.

Therefore, according to the present invention, at startup, the power to the output transistor for one phase is cut off until the rotor reaches a certain rotation speed, thereby accurately forcing a balance between the rotor rotational axis and the inertial load. This allows the rotor to start reliably.

Hereinafter, in order to further deepen the understanding of the present invention, the present invention will be described in detail based on illustrated embodiments.

Figure 1 is an electric circuit diagram of a brushless DC motor according to the present invention, in which 1 is the first phase armature winding, 2 is the second phase armature winding, and 3 is the third phase electric motor. The armature windings 1, 2.3 are child windings arranged at equal intervals of 120 degrees around the outer periphery of a permanent magnet rotor (not shown).

Further, one side of the armature winding 1.2.3 is connected to PNP type output transistors Q1, Q2. Q3
The other side is connected to each collector electrode, and the other side is connected to ground.

Furthermore, the emitter electrodes of the transistors Qlt, Q2t, and Q3 are all connected to a DC power source B via a switch 4.

The transistors Ql, Q2. Each base electrode of Q3 is connected to a PNP type front transistor Q4. Connect the emitter electrodes of Q5 and Q6, connect the collector electrode of transistor Q2 and the base electrode of transistor Q4 with capacitor C4 and resistor R1, and connect the collector electrode of transistor Q3 and the base electrode of transistor Q5 with capacitor C5 and resistor R2. Further, the collector electrode of the transistor Q1 and the base electrode of the transistor Q6 are connected through a capacitor C6 and a resistor R3 to form a circular chain circuit.

Also, the emitter common line of the output transistor /! 1 and each pre-transistor Q4. Q5. Capacitors C1, C2, and C3 are connected between the base electrode of Q6, and the resistance is Each winding in the previous stage 3. The phase of the AC voltage induced within 1.2 is delayed by about 60 degrees.

Each of the transistors Q4. Each collector electrode of Q5 is connected together to 2 by a line 12 and each point PI, P2 .
Resistors R4 and R for speed control are connected to P3.
5 and R6 are connected to each other.

On the other hand, on one side of each of the armature windings 1.2.3, there are diodes DI, D2. The cathode of D3 is connected, and the anodes of these diodes D1 to D3 are both connected to the rotational speed detection circuit 5.

A rotation speed control circuit 6 and a switching control circuit 7 are connected to the output stage of the circuit 5, and the output side of the speed control circuit 6 is connected to the line 12.

Moreover, a switching circuit 8 is incorporated in the third phase control circuit to turn off the circuit at startup.

This switching circuit 8 is configured by, for example, a PNP type transistor Q7.
The base electrode is connected to the switching control circuit 7, the collector electrode is connected to the line 2, and the emitter electrode is connected to the collector electrode of the above-mentioned front transistor Q6.

Here, when the rotor is stopped, the transistor Q7 maintains a non-conducting state because no output signal is obtained from the switching control circuit 7, and when the rotation speed of the rotor reaches a preset initial rotation speed, for example, 2000 rpm, the switching control circuit The conductive state is maintained by the output signal from the rotor 7 even when the rotor reaches a constant rotational speed, for example, 5000 rl)m.

In addition, each of the above elements R1 to R3, C1 to C3, R4 to R6
The oscillation frequency at startup can be determined by the total constant of C4 to C6.

The present invention is constructed as described above, and the operation will be described below when a belt connects the rotating shaft of the motor and a load having inertia (for example, a flywheel of a tape recorder, etc.).

Now, when switch 4 is turned on, conduction of transistor Q4 or Q5 is controlled.

For example, if the transistor Q5 is made conductive by turning on the switch 4, this causes the transistor Q5 to become conductive.
2 is turned on.

When the transistor Q2 becomes conductive, its collector potential rises, and the transistor Q4 becomes cut-off. However, when the base electrode of the transistor Q4 falls due to discharge due to the time constant of the control circuit, the transistor Q4 becomes conductive, and this As a result, transistor Q1 becomes conductive.

In this way, each armature winding 1 of the first phase to the second phase,
A current flows through 2.

Therefore, the permanent magnet rotor is excited and vibrates.

When the rotor vibrates, the induced voltage is applied to each armature winding 1.
, 2. 3, and this induced voltage causes the rotor to rotate in a fixed direction.

Since the excitation at this time is unbalanced, there is no balance between it and the inertial load.

Therefore, the rotor is reliably activated and begins to rotate in a predetermined direction.

When the rotational speed of the rotor thus started reaches a preset initial rotational speed, for example, 2000 rpm, the conduction of the transistor Q7 is controlled by the potential detected by the rotational speed detection circuit 5.

When the transistor Q7 is turned on in this way, a circular chain circuit is formed, so that the induced voltages a, b, and c (see Fig. 2) generated in each armature winding 1, 2, and 3 cause the permanent magnet rotor to rotates at a constant speed.

In other words, the plus side peak portion a of each induced voltage a, b, c
', b', C' rotate the rotor in a certain direction,
The output transistor Q3 is driven by the negative peak portion a'' of the induced voltage a generated in the armature winding 1 of the first phase through the front transistor Q6, and the induced voltage generated in the armature winding 2 of the second phase is The negative peak portion b" causes the output transistor Q to be
1, and the negative peak portion C'' of the induced voltage C generated in the third phase armature winding 3 drives the output transistor Q2 via the front transistor Q5.

In short, the output transistor Q3-Ql-Q2-Q3-Q
conduction in the order of l, each armature winding is 3-1-2-3-1
Current flows in the order of diodes D1 to D3.
The rotational speed is detected by peak detection, and the rotation of the rotor is controlled by the speed control circuit 6 at the next stage.

As is clear from the above embodiments, the present invention includes a permanent magnet rotor, output transistors Ql, Q2 . The rotor is rotated by the induced electromotive force caused by the application of an induced current in each winding 1.2.3, and each of the windings 1, 2. A rotation speed control circuit 6 is connected to the output transistor Q3 via a rotation speed detection circuit 5, and a switching control circuit 7 is connected to the output transistor Q3 via a switching circuit 8. Since the output transistor Q3 is configured to control the operation of the output transistor Q3 via the switching control circuit 7, at startup, the power supply to the output transistor Q3 for one phase is cut off until the rotational speed of the rotor reaches 2000 rpm, for example. This makes it possible to accurately forcibly break the balance between the rotor's axis of rotation and an inertial load (for example, when the flywheel of a tape recorder is connected with a belt), thereby ensuring that the rotor is This has remarkable effects such as being able to be started.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram of a brushless DC motor according to the present invention, Fig. 2 is a waveform diagram of induced voltages generated in each winding 1, 2, and 3 during rotor rotation, and Fig. 3 is a diagram of a brushless DC motor with a conventional structure. Electrical circuit diagram, Figure 4 shows each winding 11, 12
．． 13 is a waveform diagram of an induced voltage generated in FIG. 13. FIG. 1.2, 3... Armature winding, 8... Switching circuit, Q7... Transistor, B...
...DC power supply.

Claims (1)

[Scope of utility model registration request] Permanent magnet rotor and output transistors Ql, Q2, Q3
Each armature winding of multiple phases is activated sequentially by 1.2. 3
The rotor is rotated by the induced electromotive force caused by the application of an induced current in each winding 1.2.3, and a rotation speed control circuit 6 is connected to each winding 1, 2.3 via a rotation speed detection circuit 5. At the same time, a switching control circuit 7 is connected to the output transistor Q3 via a switching circuit 8, and the output transistor Q is connected to the output transistor Q3 via the switching control circuit 7 based on the output of the rotational speed detection circuit 5.
3. A brushless DC motor configured to control the operation of the motor.