JPH0449890B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resolver type position detector with improved detection accuracy.

[Prior Art] Generally, for positioning control of machine tools, robots, etc., an optical pulse encoder is used as a position detector, which outputs a two-phase pulse example signal having a frequency corresponding to changes in mechanical rotation angle. It is well known that However, optical pulse encoders have low mechanical and thermal strength, so there are problems with environmental resistance, mechanical installation, and handling.

Therefore, it is well known that resolvers are widely used as position detectors, which are electromagnetic devices that have high mechanical and thermal strength, are brushless rotating machines, and have high reliability. A typical conventional position detector using such a resolver is shown in FIG.

In the figure, 1 is a resolver with a number of magnetic pole pairs P,
Two-phase excitation windings 2 and 3 are wound around the stator, and a detection winding is wound around the rotor and outputs a detection signal e ₀ in response to changes in the mechanical rotation angle θ _n of the rotating shaft 4. 5. 6 is an excitation circuit which receives two-phase sine wave signals e _x (=cos ωt) and e _y (=
sin ωt), (here ω=2πf, the voltage value is a single value), and the excitation windings 2 and 3 are excited with these two-phase sinusoidal signals e _x and e _y , respectively. Both 7a and 7b are multipliers, and 8a and 8b are both low-pass filters.

In the above configuration, the detection signal e ₀ output from the detection winding 5 of the resolver 1 is expressed by the following equation with respect to a change in the rotation angle θ _n .

e ₀ =cos(ωt±0) =cos(ωt±P· _θn )...(1) Here, θ is the electrical phase angle, and the relationship with the rotation angle _θn is given by the following equation.

θ=P·θ _n (2) Therefore, the output signals e _x0 and e _y0 of the multipliers 8 and 9 are given by the following equations.

e _x0 = e _x・e ₀ = 1/2 {cos (2ωt±P・θ _n ) + cos
(±P・θ _n )}……(3) e _y0 = e _y・e ₀ = 1/2 {sin (2ωt±P・θ _n ) + sin
(±P・θ _n )}...(4) These output signals e _x0 and e _y0 are the respective outputs of the low-pass filters 8a and 8b after the harmonic component (2ωt) is removed by the low-pass filters 8a and 8b, respectively. signal
E _x0 and E _y0 are given by the following equations.

E _x0 = 1/2・cos (±P・θ _n ) ...(5) E _y0 = 1/2・sin (±P・θ _n ) ...(6) Equations (5), (6) and ( From equation 2), the two-phase signals E _x0 and E _y0 are two-phase signals of P cycles per rotation of the rotation angle θ _n . FIG. 9 shows the operating waveforms of the two-phase signals E _x0 and E _y0 that change according to changes in the rotation angle θ _n .

[Problems to be Solved by the Invention] In this type of conventional position detector, only two-phase signals E _x0 and E _y0 of P cycles per rotation of the rotation angle θ _n can be obtained depending on the number of magnetic pole pairs P of the resolver. do not have. In other words, since the resolution of position detection is low, when trying to use a resolver to detect rotational position in a control system using a brushless motor, for example, two resolvers are required, one for detecting the magnetic pole position of the brushless motor and the other for detecting the mechanical position of the rotating shaft. I have a problem that requires a resolver. Also,
In order to increase the accuracy of mechanical position detection, the number of magnetic pole pairs P of the resolver must be increased, for example, P = 16, but there is a limit to this, so it is not possible to sufficiently increase the resolution of position detection. In addition, there is a drawback that increasing the number of magnetic pole pairs P increases the size of the resolver body.

An object of the present invention is to generate a detection signal of a resolver having a magnetic pole pair _P by 2 ⁿ P (n
An object of the present invention is to provide a resolver-type position detector with high position detection accuracy that converts the signal into a two-phase signal of (positive integer) cycles and outputs the signal.

[Means for Solving the Problems] The configuration of the present invention for solving the above problems will be explained below using FIGS. 1 to 7 corresponding to embodiments.

The resolver type position detector of the present invention has a frequency f
_an excitation circuit ₁₀ that outputs ^two _- ^phase _sinusoidal signals e The electrical phase angle θ corresponding to the change in the rotation angle θ _n of the rotating body to be detected when excited by the phase sine wave signals e _x , e _y
(=P・θ _n ) and a resolver 1 that outputs a position detection signal e ₀ of frequency f±Δf, and the position detection signal
A pulse train signal E _2a of frequency ²ⁿ・(f±Δf) is generated by performing phase synchronization operation to track the phase of e ₀ .
and a pulse train signal with frequency 2 ⁿ⁺¹・(f±Δf)
a phase-locked loop circuit 20 that outputs E _2b ;
a first signal conversion circuit 30 that receives pulse train signals E _1a and E _1b from the excitation circuit 10 and outputs two-phase sine wave signals e ₁₁ and e ₁₂ with a frequency of 2n ^· f; and the phase-locked loop circuit. Pulse train signal E _2a from 20,
A second signal conversion circuit 40 receives E _2b and outputs two-phase sine wave signals e ₂₁ and e ₂₂ with a frequency of 2 ⁿ ·(f±Δf).
Then, by receiving the two-phase sine wave signals e ₁₁ , e ₁₂ and the two-phase sine wave signals e ₂₁ , e ₂₂ and performing a predetermined calculation, an electrical phase angle that changes according to a change in the rotation angle θ _n is obtained.
It is equipped with an arithmetic circuit 50 that outputs two-phase signals E _x1 and E _y1 having 2 ⁿ ·P·θ _n .

[Operation of the Invention] In the above means, the present invention provides a position detection signal e ₀ with a frequency f±Δf having a phase angle P·θ _n corresponding to a change in the rotation angle θ _n of the rotating body from the resolver 1 with the number of magnetic pole pairs P. In response to this signal, the phase-locked loop circuit 20 outputs a pulse train signal E _2a with a frequency of 2 ⁿ ·(f±Δf) and a pulse train signal E _2b with a frequency of 2 ⁿ⁺¹ ·(f±Δf). Ru. These pulse train signals are passed through the second signal conversion circuit 40 to
2 ⁿ ·(f±Δf) two-phase sine wave signals e ₁₂ and e ₂₂ .

On the other hand, a pulse train signal _1a with a frequency of 2 ⁿ ·f and a pulse train signal E _1b with a frequency of 2 ⁿ⁺¹ ·f from the excitation circuit 10
is converted to a frequency ^2n· through the first signal conversion circuit 30.
f into two-phase sine wave signals e ₁₁ and e ₁₂ .

Then, based on the two-phase sine wave signals e ₂₁ , e ₂₂ and the two-phase sine wave signals e ₁₁ , e ₁₂ , the arithmetic circuit 50 outputs an electrical phase angle 2 ⁿ · that changes in accordance with a change in the rotation angle θ _n .
Two-phase signals E _x1 and E _y1 having P·θ _n are output.
These two-phase signals E _x1 and E _y1 are generated per rotation of the rotation angle θ _n .
Since the change occurs in 2 ⁿ ·P cycles, if the position is detected based on this two-phase signal, the detection accuracy of the magnetic pole pair P by the resolver 1 will be improved by 2 ⁿ times. This allows for multi-pole, large resolvers and two
There is no need to use multiple resolvers.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 shows an embodiment of the present invention.
The same part (resolver part) corresponding to Fig. 8 of the same figure
are given the same reference numerals.

10 is an excitation circuit that outputs a pulse train signal E _1a with a frequency of 2 ⁿ ·f and a pulse train signal E _1b with a frequency of 2 ⁿ⁺¹ ·f in addition to the two-phase sine wave signals e _{x and e y} of the frequency f; 20 performs a phase synchronization operation so as to track the electrical phase of the detection signal e ₀ of frequency f±Δf from resolver 1, and generates a pulse train signal E _2a of frequency 2 ⁿ ·(f±Δf), and a pulse train signal E 2a of frequency 2 ^{n+ This} is a phase-locked loop circuit (hereinafter referred to as a PLL circuit) that outputs a pulse train signal E2b of _1. (f±Δf). 30 uses the pulse train signals E _1a and E _1b from the excitation circuit 10 as input signals, and generates two-phase sine wave signals e _{11 and 30} with a frequency of ²ⁿ ·f.
a first signal conversion circuit that outputs e ₁₂ ; 40 is a pulse train signal E _2a output from the PLL circuit 20;
A second signal conversion circuit outputs two-phase sine wave signals e ₂₁ and e ₂₂ with a frequency of 2 ⁿ ·(f±Δf) using E _2b as an input signal; Using the phase sine wave signals e ₁₁ , e ₁₂ and the two-phase sine wave signals e ₂₁ , e ₂₂ from the second signal conversion circuit 40 as input _signals , 2 ⁿ・
This is an arithmetic circuit that outputs P-cycle two-phase signals E _x1 and E _y1 .

In the position detector shown in Fig. 1, the detection signal e ₀ of the resolver 1 and the rotation angle θ _n have the relationship shown in equation (1) above, but when the rotation angle θ _n changes with the rotation speed N _n The state of change of the detection signal e ₀ is given by the following equation (7).

e ₀ = cos[2π(f±Δf)t±θ _n0 ] ...(7) Here, Δf = (N _n /60)・P ...(8) θ _n0 is the initial condition of the rotation angle θ _n , sign (±) is a sign related to the rotation direction of the rotation angle θ _n , and is (+) when the rotation direction is opposite to the rotating magnetic field of the resolver, and (-) when the rotation direction is the same as the rotating magnetic field of the resolver.

As shown in equation (8), the frequency Δf increases in proportion to the rotational speed N _n , and when N _n = 0, Δf = 0, which means that the detection signal e ₀ has the phase of the rotation angle θ _n0 . Become.

Next, a specific example of the configuration of the above-mentioned excitation circuit 10 will be explained with reference to FIG. 2. This excitation circuit 10
is a constant frequency K・f (for example, 10M
Hz), an oscillator 11 that outputs a pulse train signal of 100 Hz), and an oscillator 11 that counts the pulse train signal and outputs a digital signal _D1 that repeats a digital value of ₀ to n bits with a period T0, and a pulse train that has a period _T0 / ²ⁿ . signal
E _1a and a pulse train signal E _1b having a period T ₀ /2 ⁿ⁺¹ . Memory circuit ₁ that outputs a sine wave digital signal D _2a or a cosine wave digital signal D _2b , respectively, in accordance with the address signal when the digital signal D 1 is input as an address signal.
_{3 and} 14, and a digital- _to -analog converter (hereinafter referred _to as D /A converter) 15 and 16.

3a to 3d show the digital signal D ₁ , the two-phase sinusoidal signals e _x , _ey , and the pulse train signals E _1a ,
E _1b etc., and FIGS. 3e and 3f are diagrams showing the relationship between the pulse train signal E _p3 and the two-phase sine wave signals e ₁₁ and e ₁₂ in a specific example of the signal conversion circuit 30, which will be described later. The horizontal axis represents time t, and the vertical axis represents digital value or voltage value.

In Figures 3 a to d, the digital signal D ₁ reaches the digital value D _a from zero during period T ₀ and repeats this every period T ₀ , and the two-phase sine wave signals e _x and e _y are at 90 degrees to each other. It has a phase shift and a period T ₀ (frequency f). Therefore, the digital signal D ₁ represents the phase state of the two-phase sinusoidal signals e _x and e _y . Furthermore, the pulse train signals E _1a and E _1b are shown in Fig. 3c and Fig. 3, respectively.
The signal is repeatedly output at the period shown in FIG. d (the figure shows the case of 2 ⁿ =2).

FIG. 4 shows a specific example of the configuration of the PLL circuit 20. As shown in the figure, this PLL circuit 20 detects a phase difference between a detection signal e ₀ of the resolver 1 and a feedback analog sine wave circuit e _0a described later, and outputs a DC signal E _d proportional to the phase difference. A detector 21 and a DC signal amplified with proportional/integral operating characteristics using the DC signal E _d as an input signal.
An amplifier 22 that outputs E ₀ and _a frequency K (f±
A voltage-controlled oscillator 23 outputs a pulse train signal E _v having a pulse train signal E v ), and a voltage-controlled oscillator 23 that outputs a pulse train signal E _v having a pulse train signal E v and repeats a digital value at a period corresponding to the period T ₁ of the detection signal e ₀ to obtain the digital value. detection signal
_{2 which outputs a digital signal D 3} indicating the phase of e ₀ , and also outputs a pulse train signal E _2a with a period _{T 1 /} 2 ⁿ and a pulse train signal E _2b with a period T ₁ /2 ⁿ⁺¹ with respect to the period T 1. A base number counting circuit 24 and a memory circuit 25 in which a sine wave digital value is stored in advance in memory, and which uses the digital signal D ₃ as an address input signal and outputs a sine wave digital signal D ₄ in accordance with the address input signal. Then, using the sine wave digital signal D ₄ as an input signal, converting the digital signal D ₄ from digital to analog, the period T ₁ and the frequency f±Δf
and a D/A converter 26 which outputs an analog feedback sine wave signal _e0a .

In the PLL circuit 20 described above, when the detection signal e ₀ is input, the phase detector 21 detects the phase difference with the feedback analog sine wave signal e _0a , and the PLL circuit 20 adjusts the phase difference so that the phase difference becomes zero. Each part works,
The feedback analog sine wave signal e _0a performs an operation in phase synchronization with the detection signal e ₀ . Therefore, the digital signal D ₃
has a digital value indicating the phase of the detection signal _e0 .

Figures 5 a to d show the correlations among the digital signal D ₃ , the detection signal e ₀ , the feedback analog sine wave signal e _0a , and the pulse train signals E _2a , E _{2b ,} etc., and Figures 5 e, f are a pulse train signal E _p4 and a two-phase sine wave signal in a specific example of the signal conversion circuit 40, which will be described later.
It shows the relationship between e ₂₁ and e ₂₂ , where the horizontal axis shows time t and the vertical axis shows the digital value or voltage value. In Figures 5a and 5b, curve A (solid line) indicates that the rotation of the rotating shaft 4 is stopped at a certain point (the rotation angle θ _n is a certain constant value), and the signals e ₀ and e _0a are The curved line (dashed line) indicates that the signal has a period T ₁ (frequency f) under the condition that the rotating shaft 4 is rotating at a certain rotational speed in the opposite direction to the rotating direction of the rotating magnetic field of the resolver 1. e ₀ and e _0a are period T ₂ (frequency f±Δf)
Furthermore, curve C (dotted chain line) shows that under the condition that the rotating shaft 4 is rotating at a certain rotational speed in the same direction as the rotating direction of the rotating magnetic field of the resolver 1, the signals e ₀ and e _0a are It is shown that it has a period T ₃ (frequency f - Δf).

Note that the signal waveform diagrams in FIGS.
Only the state in which the rotation of is stopped at a certain point is shown.

FIG. 6 shows a specific example of the configuration of the signal conversion circuit 30 (or 40). This signal conversion circuit 30 (or 40) includes an exclusive OR circuit 31
, inverter circuits 32 and 33, and amplifier circuit 3
4, 35, resistors R ₁ to R ₉ , and capacitors C ₁ to
_C4 is connected as shown in the figure.
Input signals E _2a , E _2b and output signals e ₂₁ , e ₂₂ of the signal conversion circuit 40 are respectively shown in parentheses in the figure.
This signal conversion circuit 30 (or 40) receives the aforementioned pulse train signals E _1a , E _1b (or E _2a , E _2b ) and converts the pulse train signal E as shown in FIG. 3 e [or FIG. 5 e]. The waveform is converted into a pulse train signal E _p3 (or E _p4 ) having a two-phase signal relationship with _1a (or E _2a ).
Then, these pulse train signals E _1a , E _p3 (or E _2a ,
E _p4 ) is waveform-shaped and amplified to
Two-phase sine wave signals e ₁₁ , e ₁₂ (or e ₂₁ , e ₂₂ ) as shown in Figure f] are output. This two-phase sine wave signal
e ₁₁ and e ₁₂ (or e ₂₁ and e ₂₂ ) are each given by the following equations. (Each voltage value is a single value.) e ₁₁ = sin ωnt ...(9) e ₁₂ = cos ω _o t ...(10) e ₂₁ = sin(ω _o t±θ _o ) ...( 11) e ₂₂ = cos (ω _o t±θ _o ) ...(12) where ω _o =2π・2 ⁿ・f ...(13) θ _o =2 ⁿ・P・θ _n ...(14) Next, a specific example of the configuration of the arithmetic circuit 50 consists of multipliers 51 to 54 and subtractors 55 and 56 connected as shown in FIG. Multipliers 51-5
The signals e ₅₁ to _{e 54} output from 4 are given by the following equations, respectively.

e ₅₁ = e ₁₁ × e ₂₁ = 1/2 {cos (2ω _o t±θ _o ) − cos (±θ _o )} ...(15) e ₅₂ = e ₁₂ × e ₂₂ = 1/2 { cos ( 2ω _o t±θ _o ) + cos (±θ _o )} ...(16) e ₅₃ = e ₁₂ × e ₂₁ = 1/2 {sin (2ω _o t±θ _o ) + sin (±θ _o )} ... (17) e ₅₄ = e ₁₁ × e ₂₂ = 1/2 {sin (2ω _o t±θ _o ) − sin (±θ _o )} ...(18) Each output signal E _x1 of the subtracters 55 and 56, E _y1 is given by the following formula.

E _x1 = e ₅₂ −e ₅₁ = cos (±θ _o ) ……(19) E _y1 = e ₅₃ −e ₅₄ = sin (±θ _o ) ……(20) (19), (20) and (14 ), the two-phase signals E _x1 and E _y1 show a change of 2 ⁿ ·P cycles in response to a change of the rotation angle θ _n of one rotation. FIG. 7 shows a signal waveform diagram of two-phase signals E _x1 and E _y1 when 2 ⁿ ·P=4.

As explained above, in this embodiment, two-phase sine wave signals e x and e y of excitation frequency f are applied from the excitation circuit 10 to the resolver 1 with the number of magnetic pole pairs P, and at the same time, the excitation circuit 10 applies the two-phase sine wave signals e _x and e _y of the excitation frequency _f・Output the pulse train signal E _1a of f and the pulse train signal E _1b of frequency 2 ⁿ⁺¹ ·f, and convert both pulse train signals into a two-phase sine wave signal of frequency 2 ⁿ ·f by the first signal conversion circuit 30. _e11 ,
Convert to e ₁₂ . In addition, the detection signal e ₀ of resolver 1
The frequency 2 ⁿ · which is output from the PLL circuit 20 in response to the
(f±Δf) pulse train signal E _2a and frequency 2 ⁿ⁺¹・(f
The second signal conversion circuit 40 converts the pulse train signal E _2b of ±Δf) into two-phase sine wave signals e ₂₁ and e ₂₂ of frequency 2 ⁿ ·(f±Δf). Then, the arithmetic circuit 50 performs signal calculation using the two-phase sine wave signals e ₁₁ , e ₁₂ and e ₂₁ , e ₂₂ . As a result, the arithmetic circuit 50
The two-phase signals E _x1 and E y1 outputted from the two-phase signal E x1 and E _y1 are signals that change by 2 ⁿ ·P cycles in response to a change in the rotation angle θ _n of one rotation.

In this example, the resolver 1 with P=2 is used, the excitation frequency f=2KHz, and ²ⁿ =256 ( ²ⁿ・f=
512KHz), it was possible to obtain two-phase signals E _x1 and E _y1 of 2 ⁿ ·P=256×2=512 cycles corresponding to the change in rotation angle θ _n per rotation. In addition, another set of circuits corresponding to the signal conversion circuits 30 and 40 and the arithmetic circuit 50 is provided, and 2 ⁿ = 2 (2 ⁿ f =
4KHz), a two-phase signal of 2 ⁿ P = 2 x 2 = 4 cycles was obtained, and the two-phase signal could be used to detect the magnetic pole position of a synchronous motor with 4 magnetic pole pairs. In other words, one resolver can generate two-phase signals E _x1 and E _y1 as position signals corresponding to changes in the rotation angle θ _n and two-phase signals for detecting the magnetic pole position of a brushless motor, without increasing the size of the resolver. can be obtained.

Also, using a resolver with P = 16, the excitation frequency f
= 2KHz, 2 ⁿ = 256 (2 ⁿ f = 512KHz),
Corresponding to the change in rotation angle θ _n per rotation, 2 ⁿ・P
Two-phase signals E _x1 and E _y1 of =256×16=4096 cycles can be obtained.

[Effects of the Invention] As explained above, the resolver type position detector according to the present invention generates a position detection signal having a phase angle P·θ _n corresponding to a change in the rotation angle θ _n output from the resolver with the number of magnetic pole pairs P. Based on this, we used a PLL circuit, a signal conversion circuit, an arithmetic circuit, etc. to obtain a two-phase signal with a phase angle of ²ⁿ , P, and _θn that changes according to changes in the rotation angle _θn . There is no need to make the resolver large with multiple poles or use two resolvers, and the number of magnetic poles is P.
It is possible to improve the position detection accuracy of the resolver by ²ⁿ times, which is extremely effective in practice.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an example of the configuration of an excitation circuit in the embodiment of FIG. 1, and FIGS. Signal waveform diagram to explain circuit operation,
FIG. 4 is a block diagram showing an example of the configuration of the PLL circuit in the embodiment of FIG. 1, and FIG.
6 is a block diagram showing a configuration example of the signal conversion circuit in the embodiment of FIG. 1, and FIG. 7 is a final output signal of the embodiment of FIG. 1. FIG. 8 is a block diagram showing an example of a conventional resolver type position detector, and FIG. 9 is a signal waveform diagram for explaining the operation of the position detector shown in FIG. 1... Resolver, 10... Excitation circuit, 20...
Phase locked loop circuit (PLL circuit), 30...
...First signal conversion circuit, 40...Second signal conversion circuit, 50...Arithmetic circuit.

Claims (1)

[Claims] 1. Two-phase sine wave signals e _x , e _y with frequency f and frequency
an excitation circuit that outputs a pulse train signal E _1a with a frequency of 2 ^n· f (n is a positive integer) and a pulse train signal E _1b with ^a frequency of 2 n+1 _·f ; A _resolver that outputs a position detection signal e ₀ of a frequency f±Δf having an electrical phase angle θ (=P・θ _n ) corresponding to a change in the rotation angle θ _n of the rotating body to be detected by being excited by e y. , receives the position detection signal e ₀ and performs a phase synchronization operation to track the phase of the position detection signal e 0 to obtain a frequency of 2 ⁿ (f±
Δf) pulse train signal E _2a and frequency 2 ⁿ⁺¹・(f±
A phase-locked loop circuit outputs a pulse train signal E _2b of Δf), and receives pulse train signals E _1a and E _1b from the excitation circuit and outputs two-phase sine wave signals e ₁₁ and e ₁₂ of a frequency of 2 ⁿ ·f. a first signal conversion circuit that receives the pulse train signals E _2a and E _2b from the phase-locked loop circuit and outputs two-phase sine wave signals e ₂₁ and e ₂₂ with a frequency of 2 ⁿ ·(f±Δf). a second signal conversion circuit; receiving the two-phase sine wave signals e ₁₁ , e ₁₂ and the two-phase sine wave signals e ₂₁ , e ₂₂ and performing a predetermined calculation according to the change in the rotation angle θ _n; Varying electrical phase angle 2 ⁿ・
A resolver type position detector comprising: an arithmetic circuit that outputs two-phase signals E _x1 and E _y1 having P·θ _n .