JPS6225266A - Brushless tachometer generator - Google Patents

Abstract

PURPOSE:To suppress ripple components of a signal voltage and to reduce the influence upon a control system by inputting a magnet position detection signal to logical processing circuits and rectifying an AC voltage across stator winding synchronously in full-wave basis by using the output signals of the logical processing circuits. CONSTITUTION:A brushless tachometer generator is constituted by arranging the stator winding and magnet position detectors HA-HC opposite a magnet rotor and magnetic pole position signals A-C obtained by the magnet position detectors HA-HC are inputted to the logical circuits respectively to generate doubled select signals D1-F2. Those select signals are used to rectify the AC voltage across the stator winding synchronously on full-wave basis, obtaining a DC voltage corresponding to the rotating speed of the rotor. Consequently, ripples of the DC voltage are reduced as compared with half-wave rectification in which the signals A-C are used as they are, and the whole control system in which the generator is incorporated is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a brushless co-generator that detects the rotational speed of a rotating body.

2. Description of the Related Art In recent years, devices for detecting the rotational speed of rotating bodies (such as motors) have become increasingly important. Servo motors and the like used in factory automation, office automation, etc. detect accurate rotational speeds and feed back signals to control devices to achieve highly accurate speed and position control. Therefore, DC tacho generators are widely used as means for detecting the rotational speed of motors and the like. A DC tacho generator uses a brushed DC motor as a generator. On the rotor side marked with a line, an AC voltage proportional to the rotation speed is generated, and this signal is converted to a DC signal by the brushes and commutator on the stator side, which is used as a rotation signal for the rotating body. It is.

7) of the mechanical structure such as the brush and commutator, there was a risk that the life of the brush would be shortened due to wear, and that stable contact between the commutator and the brush could not be obtained at high speed rotation. Therefore, in recent years, mechanical rectification using brushes and commutators has not been performed.
The rotor side is configured as a magnet, the stator side is provided with multiphase windings, and the alternating current voltage induced by rotation is detected by a device for detecting the magnetic pole position on the rotor side. Brushless tachometer generators that use signals to synchronously rectify the alternating current voltage to obtain a direct current signal proportional to the rotational speed have also become popular. FIGS. 3 and 4 show the configuration and signal relationships of a conventional brushless tacho generator.

In FIG. 3, 1.2.3 is a stator winding, 4 is a rotor magnet, 5 is a device for extracting the alternating current voltage of the stator winding, 7 is a magnetic pole position detection device, and 6 is an amplifier circuit.

FIG. 5 shows a configuration example of the magnetic pole position detection device shown in FIG. 3, and FIG. 6 shows position signals A and B from the magnetic pole position signals shown in FIG.

This is an example of the configuration of a logic circuit that generates C and selection signals D+, El, and Fl. The operation of the conventional brushless tacho generator will be described above with reference to FIGS. 3 to 7.

In the conventional example, the structure of the position detector 7 corresponding to the rotor magnet 4 of FIG. 3 is shown in FIG. The pole element 8 shown in FIG. 5 generates a voltage when the rotor magnet 4 rotates. Now, 3
Since the Hall elements 8 are installed at 120° intervals, the respective output voltages H1, H2, H3 are amplified by the amplifier circuit 10 shown in FIG. 6 to become HA, HB, HC. Thereafter, the comparator circuit 11 generates A, B, and C digital signals. The timings between the signals HA, HB, HC, A, B, and c are such that the phases are shifted by 12 degrees as shown in FIG. Next, A and B.

The logic circuit 9 shown in FIG.
, El, and Fl are generated. As shown in Fig. 3, the stator windings 1, 2.3, in which AC voltage is induced by the rotation of the rotor magnet 4, are also wound at 120° intervals, so the AC voltage generated in each winding is also , as shown by G, H, and J in FIG. 4, the voltage waveforms are different in phase by 120 degrees. The level of this alternating voltage is proportional to the rotational speed of the rotor. Further, the stator winding process is performed so that the AC voltage waveform is not a sine wave but a straight line after rectification, and a trapezoidal wave output is obtained. The top portion of the trapezoidal wave in this example is about 120°. The selection signals DI and El explained above
, Fl is G of this stator winding.

The three Hall elements 8 and the stator windings 1 and 2.degree. 3 are positioned so as to coincide with the peaks of the trapezoidal waves H and J. As a result, the selection circuit 5 in FIG.
Then, at AC voltages G, H, and J, the period of M is DI, and N
The period P is synchronously rectified by El, and the period P is synchronously rectified by Fl. The signal K is converted into DC by the downstream amplifier 6. The DC voltage level is E.

That is, a DC voltage proportional to the rotation speed can be obtained.

Problems to be Solved by the Invention However, strictly speaking, the rip voltage △E of the alternating current voltage break occurs in the signal at the boundary of each selection signal D+, E+, F+, as shown in L in FIG. There is. This is because the voltage levels generated in each winding do not match completely, or the flat part of the trapezoidal wave voltage is narrower than the selection period M, N, P, or the stator winding is 1°2. This is caused by the position of the Hall element 3 not matching the position of the Hall element 8.

In order to reduce the influence of this ripple voltage △E, a filter circuit etc. is installed after the amplifier circuit 6 to get as close to complete direct current as possible. However, if a filter circuit is used, The entire control system is affected by the time constant of the filter circuit, causing a delay in the detection signal, making it difficult to improve system instability and transient response.Therefore, it is necessary to suppress the influence of the subsequent filter circuit as much as possible. There is a need.

The present invention provides a means for suppressing the ripple component of the signal voltage extracted by this brushless tacho generator and reducing its influence on the control system.

Means for Solving the Problems In order to solve the above problems, the present invention inputs a position signal to a logic processing circuit, and uses the output signal of the logic processing circuit to control the alternating current generated in the stator winding. It performs full-wave synchronous rectification of voltage.

Effect: According to the above configuration, it is possible to generate a selection signal twice as large as that of the conventional one from a position signal, and achieve full-wave synchronous rectification of an AC voltage.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows a logic circuit for generating selection signals D1 to F2 from position signals A, B, and C. The positional relationship between the solid electronic winding 1 and the Hall element 8 is the same as that described above in the conventional example using FIGS. 3 to 7. Therefore, the position signals A,,B
, C, the selection signals DI to F2, the alternating current voltages, and the timing relationships among G, H, and J are shown in FIG. In the conventional example described above, the selection signals DI, El, and Fl are used to select the AC voltage, G,
H.

Half-wave synchronous rectification is used to take out only one side (in this example, the (+) side) component of J, but in the present invention, selection signals D1 to F2
is used to extract the components on both sides of the AC voltage. That is, the selection signal DID2 selects the (+) side of the AC voltage G (-)
It looks like you can take out the side. That is, AC voltages G, H,
Full-wave synchronous rectification of J is performed. Therefore, the output voltage of amplifier 6 is 2E, which is twice that of half-wave synchronous rectification.
become.

In this case, strictly speaking, the DC output voltage is 1 and L+, but in the case of full-wave synchronous rectification, the AC electronic waveform induced in the stator winding is under the same conditions as in half-wave synchronous rectification. If so, the ratio of ripple components included in the DC signal is from △E/'EX100 (%) to △E/2EX100
(%), and at the same time the frequency of the ripple component has doubled.

Effects of the Invention As is clear from the above explanation, according to the present invention, a selection signal twice as large as that of the conventional one is created from a position signal, and full-wave synchronous rectification of the AC voltage is achieved, thereby eliminating the influence of signal delay. However, the stability of the entire control system is improved, and transient response can be improved more easily.

[Brief explanation of the drawing]

Fig. 1 is a logic circuit diagram for generating a selection signal from a magnetic pole position signal of a rotor magnet according to the present invention, Fig. 2 is a waveform diagram of each signal in the full-wave synchronous rectification circuit system according to the present invention, and Fig. 3
Figure 4 is a diagram of each signal waveform using the conventional half-wave synchronous rectifier circuit system, Figure 5 is a diagram of the configuration of the rotor magnet magnetic pole detection device shown in Figure 3, and Figure 6 is a diagram of the basic configuration of a conventional brushless tacho generator. The figure is a configuration diagram of a logic circuit that generates selection signals DI, El, and Fl from positions A, B, and C in a half-wave synchronous rectification system, and FIG. 7 is a waveform diagram showing the timing relationship of the respective signals. 1.2.3... Stator winding, 4... Magnet rotor, 9... Magnetic pole position detection signal, A, B,
C... Magnetic pole position signal of rotor magnet, D1 to F2
...Selection signal, G. 1-(, J... AC voltage signal induced in the stator winding, K1.L+... Signal after full-wave synchronous rectification and conversion to DC. Name of agent: Patent attorney Toshio Nakao Haka 1 person 1st plan, -1" 2-6 Kensawa signal No. 3, 5 Fig. 4 U Fig. 5 Fig. 6 δ Fig. 7 127!J

Claims (1)

[Claims] A magnet rotor that constitutes the generator part, a stator winding that generates an alternating current voltage proportional to the rotation speed of the magnet rotor,
A signal from a magnetic pole position detection device of a magnet attached to the rotor is input to a logic processing circuit, and the output signal of the logic processing circuit is used to generate an alternating current voltage proportional to the rotational speed generated in the stator winding. A brushless tacho generator featuring full-wave synchronous rectification.