JP6022817B2 - Variable reluctance resolver and rotation angle detector - Google Patents

Description

  The present invention relates to a variable reluctance resolver, and more particularly to a variable reluctance resolver having two excitation coils and one detection coil, and a rotation angle detection device using the resolver.

  As a resolver having two excitation coils and one detection coil, a two-phase excitation one-phase output type resolver is generally used. In a conventional two-phase excitation one-phase output type resolver, two excitation coils are spatially separated. (Mechanically) are wound around teeth that are 90 ° out of phase, and the respective excitation coils are excited by excitation signals of Vsin ωt and V cos ωt (V: amplitude). The phase difference between the output signal output from the detection coil and the excitation signal is detected, and the rotor angle is calculated from the phase difference (see, for example, Patent Documents 1 and 2).

Japanese Examined Patent Publication No. 62-58445 JP 2009-156852 A

  As described above, the conventional two-phase excitation and one-phase output type resolver calculates the rotor angle (resolver angle) from the phase difference, and therefore detects the phase difference with high resolution in order to detect the rotor angle with high accuracy. For this purpose, there is a problem that a high-speed clock or counter is required.

  On the other hand, since the resolver is generally used for motor control, the influence of leakage magnetic flux from the motor is a main factor of disturbance noise. Since noise due to the influence of leakage magnetic flux from the motor is applied at a frequency lower than the frequency of the excitation signal, this noise acts as offset noise when one period of the excitation signal is viewed, for example.

  FIG. 6 exemplifies the relationship between the excitation signal and the output signal output from the detection coil. The phase difference between the excitation signal and the output signal is Δθ in the case of an ideal output signal, while offset noise. The output signal that is offset due to the influence of Δθ ′ becomes Δθ ′ that is significantly different from Δθ. Therefore, the deterioration of detection accuracy cannot be avoided, and the detection angle varies greatly, leading to erroneous detection.

  In view of these problems, the object of the present invention is to detect the rotor angle accurately without requiring a high-speed clock or counter as in the prior art, and is not affected by offset noise. The object of the present invention is to provide a variable reluctance resolver that is strong against disturbance noise, and to provide a rotation angle detection device equipped with the resolver.

According to the first aspect of the present invention, in the variable reluctance resolver having two excitation coils and one detection coil, the two excitation coils are respectively excited by the first excitation signal and the second excitation signal having different frequencies. is a shall, the number teeth n, a tooth number i (i = 1,2, ..., n) when the number of turns n _x1i two excitation coils for each tooth of the stator, n _x2i and one detection coil The number of turns N _si is
N _x1i = N _x1max · cos (m _x1 Ψ _i + θ _x1 )
_{N x2i = N x2max · cos (} m x2 Ψ i + θ x2)
N _si = N _smax {r _s1 · cos (m _s1 ψ _i + θ _s1 ) + r _s2 · cos (m _s2 ψ _i + θ _s2 )}
However, N _x1max , N _x2max : Maximum number of excitation coil turns
N _smax : Maximum number of detection coil turns
m _x1 , m _x2 : Excitation coil pole pair number m _s1 , m _s2 : Detection coil pole pair number
θ _x1 , θ _x2 : Excitation coil phase θ _s1 , θ _s2 : Detection coil phase
Ψ _i : Teeth angle r _s1 , r _s2 : Coefficient of detection coil, m _x1 , m _x2 , m _s1 , m _s2 and the number of pole pairs m _{r of the} rotor are m _x1 ± m _s1 = ± m _r or m _{x1 Satisfies} one of eight conditions of ± m _s2 = ± m _r and further satisfies one of eight conditions of m _x2 ± m _s1 = ± m _r or m _x2 ± m _s2 = ± m _r The excitation coil is set so that the phase difference between the frequency component of the first excitation signal and the frequency component of the second excitation signal included in the output signal of the detection coil with respect to the rotor angle θ is −90 ° or + 90 °. And the phase of the detection coil are set, and the maximum number of turns of the excitation coil, the coefficient of the detection coil, the first coil coefficient so that the amplitude of the frequency component of the first excitation signal and the frequency component of the second excitation signal included in the output signal are equal. The amplitudes of the first and second excitation signals are set.

  According to a second aspect of the present invention, a rotation angle detecting device includes a variable reluctance resolver according to the first aspect, a first excitation circuit that generates a first excitation signal, and a second excitation signal that generates a second excitation signal. Two excitation circuits, a signal separator that separates the output signal into frequency components of the first and second excitation signals, and an angle calculator that calculates the rotor angle θ using the components separated by the signal separator; It comprises.

  According to this invention, by separating the output signal obtained from the detection coil into the first and second excitation frequency components, the rotor angle can be obtained by the amplitude ratio of the two separated signals. Yes. Therefore, unlike the conventional method of calculating the rotor angle from the phase difference between the excitation signal and the output signal, the rotor angle can be detected with high accuracy without requiring a high-speed clock or counter.

  In addition, since the amplitude does not change even if the output signal is offset, the detection accuracy does not deteriorate due to the influence of the offset noise, and a variable reluctance resolver that is strong against disturbance noise can be obtained in that respect. .

The table | surface which shows the relationship between the setting conditions of the number of pole pairs, and the output signal obtained by it. The block diagram which shows the structure of one Example of the rotation angle detection apparatus by this invention. The graph which shows an example of an output signal and its excitation frequency ((omega) ₁ , (omega) ₂ ) component. The block diagram which shows the structure of the other Example of the rotation angle detection apparatus by this invention. The figure for demonstrating the structural example of the rotation angle detection apparatus at the time of using CPU. The graph for demonstrating the influence of the offset noise in the resolver of the conventional 2 phase excitation 1 phase output system.

  First, the principle of the variable reluctance resolver according to the present invention will be described.

  Two excitation coils and one detection coil are wound around each tooth of the stator of the resolver. The number of turns of each excitation coil and detection coil is as follows.

Exciting coil turns _{N x1i = N x1max · cos (} m x1 Ψ i + θ x1) ... exciting first coil _{N x2i = N x2max · cos (} m x2 Ψ i + θ x2) ... exciting second coil detecting coil turns N _si = N _smax { r _s1 · cos (m _s1 ψ _i + θ _s1 ) + r _s2 · cos (m _s2 ψ _i + θ _s2 )}
Where i = 1, 2,..., N (n: number of teeth)
N _x1max , N _x2max : Maximum number of excitation coil turns
N _smax : Maximum number of detection coil turns
m _x1 , m _x2 : Excitation coil pole pair number m _s1 , m _s2 : Detection coil pole pair number
θ _x1 , θ _x2 : Excitation coil phase θ _s1 , θ _s2 : Detection coil phase
Ψ _i : Teeth angle r _s1 , r _s2 : Coefficient of detection coil The degree of rotor modulation (rotor shape) is expressed as follows.

Rotor modulation degree S _ri = (1 / R ₀ ) · {1 + α cos (m _r (θ + Ψ _i ))}
Where R ₀ : gap reluctance average value α: gap change rate
m _r : rotor pole pair number (= shaft double angle) θ: rotor angle The first excitation signal V _x1 and the second excitation signal V _x2 supplied to the excitation 1 coil and the excitation 2 coil, respectively, are as follows.

V _x1 = V ₁ sin (ω ₁ t)
V _x2 = V ₂ sin (ω ₂ t)
ω ₁ and ω ₂ are excitation signal frequencies, and ω ₁ ≠ ω ₂ . V ₁ and V ₂ are amplitudes.

At this time, the output signal V _s of the detection coil is as follows.

V _s = V _x1 · K _C · Σ _i (N _x1i · N _si · S _ri ) + V _x2 · K _C · Σ _i (N _x2i · N _si · S _ri )
However, K _C : Magnetic flux-voltage conversion coefficient When the above is calculated, the output signal V _s of the detection coil is as follows.

Since ψ _i is distributed over 360 ° at equal intervals, when integrated with i, cos with ψ _i becomes zero. Therefore, selecting the pole pairs _{m x1, m x2, m s1} , m s2, m r to a predetermined relationship, the output signal V _s of the detection coil is as shown in Table 1 of FIG. In Table 1, the output signal V _s is shown separately for the ω ₁ component and the ω ₂ component. As shown in Table 1, there are eight predetermined relationships (combinations) of the number of pole pairs for each of the ω ₁ component and ω ₂ component.

First, omega ₁ component, from the combinations of omega ₂ components pole pairs each eight, omega ₁ component, as is any one omega ₂ components respectively _{hold, m x1, m x2, m} s1, m s2, m Select _r .

Next, the phase θ of the excitation coil and the detection coil is set so that the phase difference (phase term in Table 1) with respect to θ of the output signal of the ω ₁ component and ω ₂ component of the combination of the number of pole pairs selected is −90 °. Set _x1 , _θx2 , _θs1 , and _θs2 .

Further, the amplitudes of the ω ₁ component and the ω ₂ component of the selected combination of pole pairs are equal, that is, k ₁₁ · V ₁ or k ₁₂ · V ₁ and k ₂₁ · V ₂ or k ₂₂ · V _{2. Are set} so that the maximum number of turns N _x1max and N _x2max of the exciting coil, the coefficients r _s1 and r _s2 of the detection coil, and the amplitudes V ₁ and V ₂ of the first and second exciting signals V _x1 and V _x2 are set. . By doing so, it is possible to generate a signal having a cos component and a sin component with respect to the rotor angle θ.

  An example is shown below.

For example, if m _x1 = m _x2 and r _s2 = 0, and m _x1 −m _s1 −m _r = 0 and m _x2 −m _s2 −m _r = 0, then the output signal V _s is

It becomes. Further, assuming that −θ _x1 + θ _s1 = 0, −θ _x2 + θ _s2 = −90 °, and k = k ₁₁ · V ₁ = k ₂₂ · V ₂ , the output signal V _s is as follows.

This is the output signal of the resolver according to the present invention, and the output signal V _s is a signal in which the cos component and the sin component are superimposed. Since the cos component and the sin component have different excitation frequencies, they can be separated by using synchronous detection processing or a filter.

  Next, a rotation angle detection apparatus using a resolver that outputs the above output signal will be described.

  FIG. 2 shows a functional configuration of an embodiment of a rotation angle detection device according to the present invention. The rotation angle detection device includes a resolver 10, first and second excitation circuits 21, 22, an amplifier 31, and an A / D. The converter 32, the signal separator 33, and the angle calculator 34 are comprised.

  The detailed illustration of the resolver 10 is omitted, and only two excitation coils (excitation 1 coil, excitation 2 coil) and a detection coil are shown.

The excitation circuit 21 generates an excitation signal V _x1 = V ₁ sin (ω ₁ t) and supplies it to the excitation 1 coil 11, and the excitation circuit 22 generates an excitation signal V _x2 = V ₂ sin (ω ₂ t). Supply to excitation 2 coil 12.

The output signal of the detection coil 13 is amplified by the amplifier 31, A / D converted by the A / D converter 32, and input to the signal separator 33. The signal separator 33 includes synchronous detection circuits 33a and 33b. The synchronous detection circuit 33a performs synchronous detection at the excitation signal frequency ω ₁ with respect to the output signal of the detection coil, and the synchronous detection circuit 33b outputs the output signal of the detection coil. On the other hand, synchronous detection is performed at the excitation signal frequency ω ₂ . Thereby, the following components can be extracted from the output signal of the above expression (1).

  These extracted components are input to the angle calculator 34, and the angle calculator 34 calculates and obtains the rotor angle θ by the following equation.

Thus, in this example, the rotor angle θ is obtained from the amplitude ratio of the cos component and the sin component separated from the output signal of the detection coil. Note that the phase difference (the phase term in Table 1) with respect to θ of the output signals of the ω ₁ component and the ω ₂ component may be + 90 °. In this case, since the calculation result of equation (2) is negative, the rotor angle θ is obtained by multiplying the calculation result by -1.

  Next, specific numerical examples are shown.

  For example, in order to construct a resolver having a shaft angle multiplier of 2 with a 16-tooth stator, winding is performed under the following conditions.

m _x1 = 4, m _x2 = 4, m _s1 = 2, m _s2 = 2, m _r = 2
If the rotational speed of the resolver is 30,000 rpm, and the excitation signal frequencies are ω ₁ = 10 kHz and ω ₂ = 20 kHz, the output signal V _s of the detection coil is as shown in FIG. 3B and 3C show the output signal V _s divided for each excitation frequency (ω ₁ , ω ₂ ) component.

FIG. 4 shows a functional configuration of another embodiment of the rotation angle detecting device according to the present invention. Although the rotation angle detecting device shown in FIG. 2 is a signal separator 33 had become a separated into omega ₁ component and omega ₂ components by synchronous detection, omega ₁ components by the filter in the rotation angle detecting device shown in FIG. 4 And ω ₂ components. In FIG. 4, the signal separator 35 has filters 35a and 35b. In this case, since the excitation frequency component remains, synchronous detection is required in the subsequent angle calculator 34 '.

On the other hand, FIG. 5 shows a configuration example of a rotation angle detection device in the case of using a CPU. The resolver is generally used for motor control. A CPU is usually used for motor control. As described above, two excitation signals are supplied to the resolver. These excitation signals can be easily generated by using the CPU used for motor control. In the explanation of the principle described above, the excitation signal is a sine wave, but this may be a rectangular wave. For example, if ω ₁ = 10 kHz and ω ₂ = 20 kHz, 10 kHz and 20 kHz rectangular waves are generated using the timer function of the CPU 40 as shown in FIG.

  An excitation current of about several tens mA to several hundred mA is generally applied to the excitation 1 coil 11 and the excitation 2 coil 12 of the resolver 10, but such current cannot be supplied to the output signal of the CPU 40. 24 is used. The excitation amplifiers 23 and 24 are circuits for switching current, and can be easily configured by using switching elements such as FETs.

An A / D converter with a built-in CPU 40 can be used to detect an output signal from the detection coil 13. When the output signal is small, the amplifier 31 may be inserted so as to have a prescribed amplitude before the A / D converter. The signal digitized by the A / D converter is synchronously detected by software, and the rotor angle θ is calculated by calculating the angle by calculating the arc tangent.
As described above, since the present invention does not require a high-speed clock or counter, the rotor angle θ can be calculated by capturing a signal with an A / D converter mounted on a CPU or the like and processing it with software.

DESCRIPTION OF SYMBOLS 10 Resolver 11 Excitation 1 coil 12 Excitation 2 coil 13 Detection coil 21 and 22 Excitation circuit 23 and 24 Excitation amplifier 31 Amplifier 32 A / D converter 33 Signal separator 33a, 33b Synchronous detection circuit 34, 34 'Angle calculator 35 Signal separation 35a, 35b Filter 40 CPU

Claims (2)

A variable reluctance resolver having two excitation coils and one detection coil,
The two excitation coils are respectively excited by a first excitation signal and a second excitation signal having different frequencies.
The number of teeth n, a tooth number i (i = 1,2, ..., n) when the number of turns N _x1i of the two excitation coils for each tooth of the stator, N _x2i and turns N of the one detection coil _si
N _x1i = N _x1max · cos (m _x1 Ψ _i + θ _x1 )
_{N x2i = N x2max · cos (} m x2 Ψ i + θ x2)
N _si = N _smax {r _s1 · cos (m _s1 ψ _i + θ _s1 ) + r _s2 · cos (m _s2 ψ _i + θ _s2 )}
However, N _x1max , N _x2max : Maximum number of excitation coil turns
N _smax : Maximum number of detection coil turns
m _x1 , m _x2 : Excitation coil pole pair number m _s1 , m _s2 : Detection coil pole pair number
θ _x1 , θ _x2 : Excitation coil phase θ _s1 , θ _s2 : Detection coil phase
Ψ _i : Teeth angle r _s1 , r _s2 : Coefficient of detection coil,
m _x1 , m _x2 , m _s1 , m _s2 and the number of pole pairs m _r satisfy one of eight conditions: m _x1 ± m _s1 = ± m _r or m _x1 ± m _s2 = ± m _r Furthermore, m _x2 ± m _s1 = ± m _r or m _x2 ± m _s2 = ± m _r is set to satisfy one of eight conditions,
The excitation coil and the phase difference between the frequency component of the first excitation signal and the frequency component of the second excitation signal contained in the output signal of the detection coil with respect to the rotor angle θ are −90 ° or + 90 °. The phase of the detection coil is set,
The maximum number of turns of the excitation coil, the coefficient of the detection coil, the first and second coefficients so that the amplitude of the frequency component of the first excitation signal and the frequency component of the second excitation signal included in the output signal are equal. A variable reluctance resolver, wherein the amplitude of the excitation signal of 2 is set. The variable reluctance resolver according to claim 1,
A first excitation circuit for generating the first excitation signal;
A second excitation circuit for generating the second excitation signal;
A signal separator for separating the output signal into frequency components of the first and second excitation signals;
An angle calculator that calculates the rotor angle θ using the components separated by the signal separator.

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