JPS5934079B2 - Commutatorless motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a non-commutator motor, and more particularly, a control device for a non-commutator motor, in which an armature coil is arranged opposite to a rotor to which a field magnet is attached, and a hole for detecting the rotational position of the rotor is provided. A voltage proportional to the detected speed obtained by detecting the rotor speed and a reference corresponding to the reference speed are provided. This relates to a commutatorless motor control device that performs constant speed control by applying a voltage deviation from the voltage to each of the Hall elements as a drive voltage.In particular, it eliminates ripples in output torque during normal operation and also automatically starts the motor. This is intended to make it possible.

For example, very low rotational unevenness characteristics are required for audio equipment such as record players, but the torque ripple of the non-commutator motor used as the rotational drive source directly affects rotational unevenness, so there is no torque ripple. It is desired to realize a commutatorless motor.

The prior art and its problems will be explained using drawings. FIG. 1 is a diagram showing the general configuration of a commutatorless motor that performs constant speed control. Armature coils 3a and 3b are arranged facing the rotor 9 to which the field magnet is attached, and Hall elements 1a and Ib detect the magnetic pole position of the magnet rotor 9.
The outputs of the Hall elements 1a and Ib are input to the coil drive amplifiers 2a and 2b, respectively, and current is caused to flow through the armature coils 3a and 3b according to the output voltage (V), and constant speed control is performed. is carried out as follows. That is, the rotational speed of the magnet rotor 9 is detected by the speed detector 4, and the output of the speed detector 4 is converted into a voltage proportional to the rotational speed by the speed-to-voltage converter 5, which corresponds to the command speed. The reference voltage Es and the speed-to-voltage converter 5
A voltage comparator 6 calculates a voltage deviation from the output voltage of the magnet rotor 9, and the rotational speed of the magnet rotor 9 is controlled to match the command speed by applying this deviation voltage as a drive voltage to the Hall elements 1a and Ib. In FIG. 1, R1 and R2 are input resistances of the coil drive amplifiers 2a and 2b, respectively, and R3 and R4 are feedback resistances, respectively. With this configuration, an AC voltage of a certain frequency is generated in the Hall elements 1a, 1b according to the rotation of the magnet rotor 9, and this AC voltage is amplified by the coil drive amplifiers 2a, 2b. It is applied to armature coils 3a and 3b.

However, the offset amount of the Hall elements 1a, 1b is applied to the Hall elements 1a, 1b and the coil drive amplifier as a voltage multiplied by the gain of the amplifier. A voltage obtained by adding an AC voltage to the voltage is applied to the armature coils 3a and 3b. Due to this DC voltage, a deviation occurs between the position of the magnet rotor 9 and the direction of the current flowing through the armature coils 3a, 3b, and a reverse torque is generated. Further, torque ripple occurs every 90 degrees of rotation angle interval of the magnet rotor 9. Next, details of torque ripple generation will be described.
It is assumed that the magnet rotor 9 is magnetized into eight poles on the circumference. Assuming that the armature coils 3a and 3b are shaped like a flat star, when a sinusoidal current flows through either of the armature coils 3a or 3b, the torque T1 changes the rotation angle of the magnet rotor 9. As θ-! Since 1 current 1 is , (1) and (2) are obtained.

The above situation is as shown in FIG. 2 (1), (2), and (3), and clockwise rotation torque is generated.

Also, the armature coil is 2j. If you install another set with a 5 degree shift and shift the phase of the current flowing through the armature coils by 90 degrees, the current 12 flowing through the other armature coil will generate a torque T2 of b1(4), ( 5) It becomes better.

FIG. 3 shows the relationship between the current flowing through the two sets of armature coils 3a and 3b and the generated torque.

The total generated torque T is the addition of the torques T, , T2 generated in the two sets of armature coils.

As shown in Fig. 3 (2), it remains constant regardless of the rotation angle.

If an AC voltage with a DC component added to the armature coil 3a is applied, the DC voltage will be shifted by Δe as shown in FIG. 3(3).

Then, the current and torque are as follows. Assuming that the coil resistance is R, the total generated torque is F from (6) in armature coil 3b from (7) and (8).

As shown in Figure 3 (4), four torque ripples occur in one rotation.

This is the same for the armature coil 3b as well as for both 3a and 3b. For the above reasons, in order to eliminate torque ripple during constant speed rotation, the armature coil 3a,
An alternating current voltage that does not contain a direct component may be applied to 3b. Conventionally, in order to reduce torque ripple, a method as shown in FIGS. 4 and 5 has been adopted. The method shown in Fig. 4 is based on the human resistance Rl, R2 of the coil 1 drive amplifier 2a, 2b.
The capacitors 7A and 7b are connected in parallel to the coil 1 drive amplifiers 2a and 2b, respectively, compared to the method shown in FIG.
The DC gain is reduced by the increase in the AC gain, thereby reducing the DC shift voltage Δe applied to the armature coils 3a, 3b. However, even with this method shown in Figure 4, torque ripple still occurs because DC gain remains.The method shown in Figure 5 uses coil drive amplifiers 2a and 2b as DC amplifiers, The offset amount .DELTA.e is compensated for by the devices 8a and 8b. However, this compensation requires the Hall elements 1a, 1b and the coil drive amplifier 2.
Since the offset caused by both a and 2b must be compensated for, the compensation adjustment is troublesome and takes time. The torque ripple during constant speed rotation of the commutatorless motor has been described above, but the following problem occurs when starting the commutatorless motor.

That is, considering the time when the motor is started, the magnet rotor is stopped, and only a certain DC voltage determined by the stop position of the magnet rotor is output to the b1 Hall element, and there is no AC component output. The outputs of these Hall elements are taken out differentially and sent to coil drive amplifiers 2a, 2.
However, as mentioned above, when the motor is started, there is no AC component in the Hall element output, so if the coil drive amplifiers 2a and 2b are configured as AC amplifiers, it is not possible to automatically start the motor. Can not. An object of the present invention is to solve the above-mentioned problems with the prior art and automatically start the V1 motor by configuring the coil drive amplifier to operate as a DC amplifier when starting the motor and as an AC amplifier when the motor rotates at a constant speed. In addition to making it possible to
An object of the present invention is to provide a commutatorless motor control device that can eliminate torque ripple without requiring offset adjustment during constant speed rotation.

A feature of the present invention is that, in order to achieve the above object, each coil becomes conductive when a control voltage above a certain threshold is applied in parallel to the input capacitor of the drive amplifier. A switching element which becomes non-conductive is connected, and the deviation 5 voltage between a voltage proportional to the detected rotor speed and a command voltage corresponding to the reference speed is used as the control voltage of this switching element.

An embodiment of the present invention will be explained with reference to FIG.

In Fig. 6, 7a and 7a' are coil 1 drive amplifier 2.
A resistor R1 is an input resistor connected in series to the input capacitor 7a, and 110a and 10a' are analog switching elements connected in parallel to the input capacitors 7A and 7a', respectively. Similarly, 7b, 7b'
is the input capacitor of the coil 1 drive amplifier 2b, and the resistor R2 is the input resistor in series with the input capacitor 7b.
10b and 10b' are input capacitors 7B and 7b, respectively.
is an analog switching element connected in parallel with . And these switching elements 10a, 10a1
, 10b, 10b', the voltage comparator 6
output voltages are applied respectively. R9, R9', Rl
O and RlO' are current limiting protection resistors connected in series to each switching element. In the above configuration, when the motor is started, the switching element 1 is switched from the voltage comparator 6.
A voltage equal to or higher than the threshold voltage of 0a, 10a', 10b, 10b' is generated and each switching element becomes conductive.As a result, the coil 1 drive amplifiers 2a and 2b become DC amplifiers and the D1 motor starts.

When the motor rotates at a constant speed, the output voltage of the voltage comparator 6 is lower than the threshold voltage of the switching element b1 Each switching element is in a non-conducting state D1 Coil 1 Drive amplifier 2
a, 2b are AC amplifiers, Hall elements 1a, 1-b
The offset of input capacitors 7A, 7a', 7b, 7
It is cut at b'. Since 2a and 2b are AC amplifiers, the offset of the amplifiers themselves also becomes a very small value regardless of the amplifier gain.

When rotating at a speed matching the command speed, the coil drive amplifiers 2a and 2b become almost perfect AC amplifiers, and as a result, an AC signal containing almost no DC component is applied to the armature coils 3a and 3b. Torque ripple on the motor output is almost completely eliminated. As described above, according to the present invention, a DC voltage is applied to the armature coil of the motor at the time of startup, and the motor starts rotating thereby, and when the motor starts rotating at a constant speed, only an AC voltage is applied to the armature coil. This allows the motor to rotate stably without torque ripple.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional speed control block diagram of a non-commutated motor, Fig. 2 is a diagram showing the positional relationship between the rotor and armature coil in Fig. 1, and Fig. 3 is a diagram showing the resultant torque in the case of Fig. 1. The explanatory drawings, FIGS. 4 and 5, are block diagrams in which conventional countermeasures have been added, and FIG. 6 is a block diagram showing an embodiment of the present invention.

Claims (1)

[Claims] 1. A group of Hall elements for detecting the rotational position of the rotor, with an armature coil arranged opposite to the rotor to which the field magnet is attached, and a coil drive amplifier for amplifying the outputs of these Hall elements and sending them to the armature coil. and a non-commutator that performs constant speed control by applying a deviation voltage between a voltage proportional to the detected speed obtained by detecting the rotor speed and a reference voltage corresponding to the reference speed as a drive voltage to each of the Hall elements. In the motor control device, a switching element is connected in parallel to the input capacitor of the coil drive amplifier, and the switching element becomes conductive when a control voltage higher than a certain threshold is applied and becomes non-conductive when a control voltage lower than the threshold is applied. A non-commutator motor control device characterized in that, by using the deviation voltage as a control voltage of an element, the coil drive amplifier is operated as a DC amplifier when the motor is started and as an AC amplifier when the motor is rotating at a constant speed.