JPH01143916A - Automatic correction system for hall element unbalanced voltage of magnetic rotational angle sensor - Google Patents

Abstract

PURPOSE:To improve the accuracy of output waveform conversion for an angle of rotation by correcting the Hall element unbalanced voltage and variation in signal reference voltage automatically and using the voltage obtained by removing a sine wave signal component from an amplified signal voltage as a reference power source. CONSTITUTION:The output voltage (sine wave) of the Hall element 12 is amplified by an operational amplifier 13 and then inputted to a waveform converter 14 by DC coupling. The Hall element unbalanced voltage generated by this DC coupling and variation in the signal reference voltage due to the offset voltage of the amplifier 13 are detected and compared with a set DC reference voltage. Then a bias voltage applied to the amplifier 13 is corrected automatically and the reference potential of the output voltage is approximated to the set DC reference voltage. Further, the signal reference voltage obtained by removing the sine signal component from the signal voltage obtained by amplifying the waveform conversion reference voltage of a converter 14 is used as the reference power source. Thus, a phase shift at the time low-speed rotation of AC coupling and the problem that an output waveform setting time is required at the start are removed by the DC coupling between the amplifier 13 and converter 14 and the conversion accuracy of the waveform for the angle of rotation is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Hall element unbalance voltage automatic correction system in a magnetic rotation angle sensor using a multipolar permanent magnet rotor and a Hall element.

[Prior art]

FIG. 4 is a block diagram showing an example of a system configuration of a conventional magnetic rotation angle sensor for an internal combustion engine. In the same figure, 1
1 is a permanent magnet rotor having multiple poles, 1
2 is a Hall element, 13 is an operational amplifier, 14 is a waveform converter (comparator), 15 is an output section, and 16 is a reference voltage source that generates the first reference voltage Vrefl.

In the magnetic rotation angle sensor configured as described above, a rotating magnetic field by the permanent magnet rotor 11 is applied to the Hall element 12, the Hall output from the Hall element 12 is amplified by the amplifier 13, and the DC component is cut by the capacitor C. , by applying only the rotation signal to the waveform converter 14,
The sine wave is converted into a square wave and outputted from the output section 15.

The reference voltage Vrefl from the reference voltage source 16 is the reference potential when this circuit is operated with a single power supply (operated with a single-polarity power supply, either positive or negative).
. Bias power supply for C/3, waveform converter 14
It also serves as the waveform comparison voltage.

Further, the resistor R of the waveform converter 14 is a bias resistor for applying a DC reference voltage to the input signal.

FIG. 5 is a waveform diagram showing the waveforms of each part of the magnetic rotation angle sensor circuit, where (1) is the output voltage waveform of the Hall element 12, and 2) is the input waveform of the waveform converter 14 at high rotation. The output waveform of the output section 15, (3) shows the input waveform of the waveform converter 14 and the output waveform of the output section 15 at low rotation, respectively.

[Problem that the invention seeks to solve]

However, in the above circuit, when the permanent magnet rotor 11 is rotating at a low speed, -CR is compared with the signal period (period of the input voltage signal of the waveform converter 14) with a time constant,
If it is not made sufficiently large, a phase shift deviation Δt will occur as shown in FIG. 5(3), resulting in a situation where the crankshaft angle is deviated.

Also, at the time of starting, the reference potential of the input signal of the waveform converter 140 fluctuates due to the charging time of the capacitor C = C R, and the intervals of the output pulses are not aligned, so if angular accuracy at the time of starting is required, Since this charging time τ cannot be increased unnecessarily, there is a drawback that this conflicts with the desire that the time constant τ must be sufficiently large.

The present invention has been made in view of the above points, and is a waveform conversion method in which the output signal of the conventional Hall element is AC-coupled (C-coupled) to remove fluctuations in the signal reference potential due to unbalanced voltage and offset voltage of the amplifier. , we have developed a Hall element unbalanced voltage automatic correction method in a magnetic rotation angle sensor that eliminates the drawbacks of phase shift during low-speed rotation and the need for output waveform settling time at startup, and has high accuracy in output waveform conversion with respect to rotation angle. It is about providing.

[Means for solving problems]

In order to solve the above problems, the present invention provides a magnetic rotation angle sensor using a multipolar permanent magnet rotor and a Hall element, after amplifying the output voltage (sine wave) of the Hall element using an operational amplifier, is input as DC coupling to the signal reference voltage, and detects the fluctuation of the signal reference voltage due to the Hall element unbalanced voltage generated by the DC coupling and the offset voltage of the operational amplifier, compares it with the set DC reference voltage, and outputs the signal to the operational amplifier. A circuit that automatically corrects the applied bias voltage to approximate the reference potential of the output voltage to the set DC base q voltage, and a waveform conversion reference potential of the waveform converter that removes the sine wave signal from the amplified signal voltage. The present invention is characterized in that a circuit is provided that uses the signal reference voltage obtained as a reference power source.

[Effect]

By configuring as described above, the operational amplifier and the waveform converter are coupled to each other by direct current coupling, so that the conventional alternating current coupling (
This eliminates the problems of the phase shift during low-speed rotation and the need for output waveform settling time at startup, which are disadvantages of the C-coupled method, and eliminates the problem of the Hall element that occurs when waveform conversion is performed using the DC coupling method. By automatically correcting fluctuations in the signal reference potential due to unbalanced voltage and operational amplifier offset voltage, and by removing the sine wave signal component from the amplified signal voltage to create a signal reference voltage, the conversion accuracy of the output waveform with respect to the rotation angle is improved. can be improved.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Fig. 1 is a block diagram showing the system configuration of a magnetic rotation angle sensor according to an embodiment of the present invention, Fig. 2 is a waveform diagram of each part thereof, and Fig. 3 is a circuit diagram embodying the block diagram of Fig. 1. It is.

1 and 3, 11 is a permanent magnet rotor, 12 is a Hall element, 13 is an operational amplifier, and 14 is a permanent magnet rotor.
15 is a waveform converter (comparator); 15 is an output section; 16 is a reference voltage source that generates the first reference voltage vrefl; 17
is a buffer amplifier, 18 is a correction amplifier, R, Rs, R+~
R0 is resistance, C, C.

is a capacitor, and Q is an output transistor.

In FIG. 2, (1) is the output voltage waveform of the Hall element 12, and (2) is the output of the operational amplifier 13, that is, the waveform converter 14.
The input voltage waveform of (3) is the reference voltage of each part, that is, the first to
Voltage level values (4) of the fourth reference voltage Vrefl~3 indicate the output waveforms of the waveform converter 14, respectively.

Before explaining the operation of the magnetic rotation angle sensor shown in FIGS. 1 and 3, first, based on FIG.
The reason why an unbalanced voltage occurs at the output of the amplifier stage will be explained.

Based on its principle, the Hall element 12 can be considered as a bridge resistor with equal resistance values on each side, and in the circuit shown in FIG.
When the direct current potential between the output terminals and the alternating signal voltage due to the rotating magnetic field are separated and converted into an equivalent circuit, the result is shown in FIG.

Here, the resistances are R, -R, ,R, -R, and the operational amplifier 1
If the gain of 3 is A1, then AI-R1/R1-RA/R.

Therefore, the output voltage V of the operational amplifier 13. A4 is VOAI''-A1・eolHsinθ+Vref
1+ ((1+AI)-(V,-V-))
−・・−(1) Here, −At・e, □sinθ is the alternating signal voltage term, Vreft is the DC reference potential term, ((1+
A1)-(V, -V-)) is an unbalanced voltage amplification component term of the Hall element 12, and (V or -V-) is an unbalanced voltage term of the Hall element 12. Further, V, and V- are the voltage at the ten input terminal and the voltage at the - input terminal of the operational amplifier 13, respectively.

In the above equation (1), if (V, -V-) -±Vu, VOAI = -AI' e out! 3inθ+(Vr
efl+(±Vu)+(Al・±Vu))
...(2). Here -A1・
e, □sinθ is the alternating voltage term, (Vrefl+(SatV
u ) + (A1·±Vu)) becomes a DC reference potential term, and this DC reference potential term serves as a reference potential for the alternating voltage term, which varies depending on the unbalanced voltage Vu of the Hall element 12. FIG. 8 is a waveform diagram showing the waveform, and (1) in the same figure shows that when the DC reference potential fluctuation in equation (2) is -Vu,
(2) in the same figure shows the case where the DC reference potential variation in equation (2) is +Vu.

Next, the operation of the magnetic rotation angle sensor shown in FIG. 1, which is an embodiment of the present invention, will be explained. The DC potential applied to the operational amplifier 13 is the output voltage of the correction amplifier 18 VOA t = v r
Since it is ef3 (third reference voltage), the output voltage V of the operational amplifier 13. AI is similar to equation (2) above, VOAI = -A1・e oH! 1 sin θ+(Vre
f3+(±■u)+(A1・±Vu))
...(3). Here A1・e o
M, 1 sin θ is the alternating voltage term, (Vref3+ (±V
u)+(Al·±Vu)) is a DC reference potential term.

On the other hand, the input signal of the buffer amplifier 17 is ■゛. 1 is the output voltage V of the operational amplifier 13. From AI to resistor R8 and capacitor C8
It is a DC voltage from which the alternating signal voltage component is almost removed by a signal filter consisting of )+(Al・±V
u)), so Vref2=Vref3+(±Vu)+(At-±V
u) −・<4).

Furthermore, since the correction amplifier 1B operates as an inverting amplifier that uses the DC reference voltage as the first reference voltage Vrefl, if the resistor RI3=R14, its gain A2 is A2=R
Is/R14. Output voltage V of correction amplifier 18.

A! is voA! =-A2・(■.-V-)+Vrefl=Vr
ef3...(5). In addition, V,,V
- are the voltages at the ten input terminals of the correction amplifier 18, -
This is the voltage at the input terminal. Here, (v and -) = ±V
If d is the correction voltage, this correction voltage ±Vd is ±vd=vref1−■ref2 (6), and from the above equations 5) and <6), it is the output of the correction amplifier 18. The third reference voltage Vref3 is Vref3--
A2・(+Vd)+Vrefl...
(7) Here, -A2·(±Vd) is a DC reference voltage term.

Substituting the above (7) into the equation (3), VoA+=-A1・e o)1wsinθ+(-(A2
・(±Vd)+Vrefl)+(±Vu)+(AI・
±Vu)) =-Al-e o,, sinθ+Vrefl+(±V
u)+(AI・±Vu)−(A2・±Vd)
...(8) In formula (8), A1・e
onasinθ is the alternating signal voltage term, Vrefl+(±
Vu) is the DC reference voltage term, (AI-±Vu)-(A2・
±Vd) is a correction term. In the above equation (8), if the correction term (At·±Vu) −(A2·±Vd) becomes zero, the fluctuation in the DC reference voltage term Vrefl+(±Vu) is only due to the unbalanced voltage of the Hall element 12. Therefore, the object of the present invention can be achieved.

Next, the fact that the correction term (A1·±Vu)−(A2−±Vd) becomes zero will be explained.

V d in the above equation (6) = Vrefl −Vref2
Substituting equation (4) into , Vd=Vrefl-(Vref3+(±Vu)+(A
t-±Vu))・(6)'(6)' By formula, Vref3= Vrefl-(±Vu)-(At-±V
u), so by equation 7), -A2-(±Vd)+Vrefl=Vrefl-(±V
u)-(Al-±Vu)-A2・(f Vd)=-(±
Vu) - (Al ・±Vu) Here, if the gain A1 of the operational amplifier 13 and the gain A2 of the correction amplifier 18 are made equal, -AI ・(±Vd) = -(Vu) - (At±Vu)
±Vd= (-(fVu)-(A1・±Vu)) /
-At-(±Vu)/A1+(±Vu)) Φ±Vu...(9) Therefore, the correction term (AI・±Vu)-(A2) in the above equation (8)
・±Vd) is AI・(±Vu)−(A2・±Vd)−Al・(±Vu
)−(Al·±Vu)±0, and the present invention is achieved.

〔Effect of the invention〕

As explained above, according to the present invention, after amplifying the output of the Hall element, fluctuations in the signal reference potential due to the Hall element unbalanced voltage and the offset voltage of the amplifier, which occur when performing waveform conversion in the DC coupling method, are automatically corrected. By using the signal reference voltage obtained by removing the sine wave signal from the corrected and amplified signal voltage as the reference power source of the waveform converter, an excellent effect of improving the output waveform conversion accuracy with respect to the rotation angle can be obtained. In addition, the circuit is composed of a single-power-operated operational amplifier, which reduces costs and can be used not only as an on-vehicle crank angle sensor, but also as a rotation angle sensor for all devices that have a rotating shaft. Excellent effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a Hall element unbalanced voltage automatic correction circuit in a magnetic rotation angle sensor according to the present invention, and FIG. 2 is a block diagram showing the operation of the Hall element unbalanced voltage automatic correction circuit of FIG. 1. Voltage waveform diagrams of various parts, Figure 3 is a circuit diagram embodying the Hall element unbalanced voltage automatic correction circuit of Figure 1, Figure 4 is a block diagram showing an example of the system configuration of a conventional magnetic rotation angle sensor for an internal combustion engine. Figure 5 is a voltage waveform diagram of each part to explain the operation of the magnetic rotation angle sensor in Figure 4, and Figure 6 is a diagram of the Hall element 12 and operational amplifier 1 in Figure 4.
3, and Figure 7 is the equivalent circuit of Figure 6. Figure 8 is the equivalent circuit of Figure 7.
It is a waveform chart of each part of a figure. In the figure, 11...Permanent magnet rotor, 1
2... Hall element, 13... operational amplifier, 14
... Waveform converter, 15... Output section, 16...
・Reference voltage source, 17...Buffer amplifier, 18...
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Claims (1)

[Claims] In a magnetic rotation angle sensor that includes a permanent magnet rotor with a plurality of poles or more and a Hall element, Hall element imbalance occurs when the output voltage of the Hall element is DC amplified by an operational amplifier. A circuit is provided to detect fluctuations in the reference voltage due to voltage and compare it with a set DC voltage, automatically correct the bias voltage of the operational amplifier, and maintain the output reference potential, and extract the sine wave signal from the amplified signal voltage. 1. A Hall element unbalanced voltage automatic correction system in a magnetic rotation angle sensor, comprising a circuit that uses the removed signal reference voltage as a reference power source for a waveform converter.