JP7251751B2 - Electrical angle acquisition system, electrical angle acquisition method, electrical angle acquisition program, electrical angle acquisition characteristic measurement system, electrical angle acquisition characteristic measurement method, and electrical angle acquisition characteristic measurement program - Google Patents

Description

The present invention relates to technology for obtaining an electrical angle based on an output signal from a rotation detector.

Conventionally, a resolver/digital converter is known that outputs digital data indicating an electrical angle of a resolver based on an output signal of the resolver. For example, Patent Document 1 discloses a tracking loop type digital angle converter.
Further, various methods are known for resolvers, and a phase modulation method is known in addition to the amplitude modulation method as disclosed in Patent Document 1. For example, Patent Document 2 is known as a phase modulation type resolver.

Japanese Patent No. 4226044 JP-A-4-16712

In the prior art such as the above-mentioned Patent Document 1, complicated signal processing is performed by many analog circuits, and it is difficult to obtain an accurate electrical angle. Further, the analysis method of the phase modulation type resolver as disclosed in Patent Document 2 cannot be applied to the amplitude modulation type that analyzes the amplitude of the output signal.
SUMMARY OF THE INVENTION It is an object of the present invention to obtain an accurate electrical angle.

In order to achieve the above object, the electrical angle acquisition system includes an excitation signal acquisition unit that acquires an excitation frequency component of an excitation signal of a rotation detector with 1-phase excitation and 2-phase output by Fourier transform; An output signal acquisition unit that acquires the excitation frequency component of the output signal of by Fourier transform, and the excitation signal and the two-phase output signal based on the excitation frequency component of the excitation signal and the excitation frequency component of the two-phase output signal an amplitude acquisition unit for acquiring the amplitude of the two-phase output signals based on the excitation frequency components of the two-phase output signals; and the phase relationship and the two-phase output signals. an electrical angle acquisition unit that acquires the electrical angle of the rotation detector based on the amplitude of

That is, in the electrical angle acquisition system, the excitation signal and the output signal of the rotation detector are taken in, and the electrical angle is acquired based on these signals. An electrical angle is obtained based on the amplitude of the signal. Then, in the electrical angle acquisition system, the excitation frequency component is extracted from the excitation signal and the output signal by Fourier transform, and the electrical angle is acquired based on the extracted signal. According to this configuration, it is possible to reduce the influence of noise and the like, and to accurately acquire the electrical angle.

1 is a block diagram showing a first embodiment of an electrical angle acquisition system; FIG. 2A is a diagram showing an ideal example of the excitation signal, the SIN signal and the COS signal, FIG. 2B is a diagram showing the phase relationship between the excitation signal and the output signal, and FIG. 2C is a diagram showing the relationship between the amplitude and the electrical angle. be. FIG. 4 is a diagram for explaining analog-to-digital conversion and sampling; FIG. 4A is a diagram showing rotation of the coordinate axes of the complex plane, and FIG. 4B is a flow chart of electrical angle calculation processing. FIG. 3 is a block diagram showing a second embodiment of an electrical angle acquisition system; FIG. FIG. 10 is a diagram showing an example of acquisition of a phase relationship; FIG. 11 is a block diagram showing a third embodiment of an electrical angle acquisition system; FIG. 4 is a diagram for explaining analog-to-digital conversion and sampling; FIG. 11 is a block diagram showing a fourth embodiment of an electrical angle acquisition system; FIG. 11 is a block diagram showing a fifth embodiment of an electrical angle acquisition system; FIG. 11 is a block diagram showing a sixth embodiment of an electrical angle acquisition system; FIG. 11 is a block diagram showing a seventh embodiment of an electrical angle acquisition system; FIG. 11 is a block diagram showing an eighth embodiment of an electrical angle acquisition system; FIG. 21 is a block diagram showing a ninth embodiment of an electrical angle acquisition system; FIG. 10 illustrates elliptic correction when the amplitudes of the output signals are mismatched;

Here, embodiments of the present invention will be described according to the following order.
(1) Configuration of electrical angle acquisition system:
(2) Second embodiment:
(3) Third embodiment:
(4) Fourth to Eighth Embodiments:
(5) Ninth Embodiment:
(6) Other embodiments:

(1) Configuration of electrical angle acquisition system:
FIG. 1 is a block diagram showing the configuration of an electrical angle acquisition system 10 according to one embodiment of the present invention. In this embodiment, the electrical angle acquisition system 10 includes an excitation signal acquisition section 20, an output signal acquisition section 30, a phase relationship acquisition section 40, an amplitude acquisition section 50, an electrical angle acquisition section 60, and a parameter setting section 70. . The electrical angle acquisition system 10 also includes an excitation signal generator 13 and amplifiers 13a to 13c. The excitation signal generator 13 and the amplifiers 13 a to 13 c may be provided outside the electrical angle acquisition system 10 . In FIG. 1 , the dashed line indicates the state where the excitation signal generator 13 exists outside the electrical angle acquisition system 10 .

The electrical angle acquisition system 10 is a system for acquiring the electrical angle of a resolver 11 which is an example of a rotation detector, and is connected to the resolver 11 . That is, the excitation signal generated by the excitation signal generator 13 is input to the amplifier 12 , and the amplified excitation signal is input to the resolver 11 . Also, the signal output from the resolver 11 is taken into the electrical angle acquisition system 10 . Note that, in the present embodiment, the excitation signal amplified by the amplifier 12 is also taken into the electrical angle acquisition system 10 . Of course, when the excitation load of the resolver 11 is small, the amplifier 12 may not be provided.

The resolver 11 is a one-phase excitation two-phase output resolver, and in this embodiment, the resolver 11 is of an amplitude modulation type. That is, the resolver 11 includes a one-phase excitation winding, two-phase output windings, and a rotor. The excitation windings and the output windings are arranged in a predetermined relationship, and when the excitation signal amplified by the amplifier 12 is supplied to the excitation windings, the output windings will change according to the mechanical angle of the rotor and the shaft angle multiple (number of pole pairs). An output signal modulated by the power is output from the two-phase output windings.

An ideal correspondence relationship between the mechanical angle and the electrical angle is determined by the configuration of the resolver 11 . If the shaft angle multiplier of the rotor is 2 or more, the rotor rotates at an electrical angle of 0° to 360° by the same number as the shaft angle in the process of making one rotation of the mechanical angle of 0° to 360°. Although the present embodiment can be applied to any shaft angle multiplier, for the sake of simplicity, the following description will be given as an example of a configuration in which the shaft angle multiplier is 1, that is, the mechanical angle makes one revolution in the process of making one revolution.

In this embodiment, the two-phase output windings are arranged so that the output signals of each winding are orthogonal. In this embodiment, one of the signals output from the two-phase output windings is also called a SIN signal, and the other is called a COS signal. The excitation signal is a sine wave signal, and in this embodiment, it is taken into the electrical angle acquisition system 10 as R1-R2 shown in FIG. Output signals from the output windings are taken into the electrical angle acquisition system 10 as S2-S4 and S1-S3 shown in FIG. Here, S2-S4 are SIN signals, and S1-S3 are COS signals.

The excitation signal taken into the electrical angle acquisition system 10 is amplified by the amplifier 13a. In this embodiment, the excitation signal after being amplified by the amplifier 13a is expressed as Esin(2πf _r t). Here, E is the amplitude of the excitation signal after amplification, f _r is the frequency of the excitation signal (excitation frequency), and t is time (seconds). Further, when the excitation signal is Esin (2πf _r t), the signal after the SIN signal is amplified by the amplifier 13b is expressed as Ksinθe·sin (2πf _r t), and the COS signal after being amplified by the amplifier 13c is expressed as Kcos θe·sin(2πf _r t). Here, K is the amplitude of the output signal after amplification, .theta.e is the electrical angle, _f.sub.r is the excitation frequency, and t is the time.

FIG. 2A is a diagram showing ideal examples of an excitation signal, a SIN signal, and a COS signal. In FIG. 2A, the excitation signal, the SIN signal and the COS signal are shown side by side. Also, FIG. 2A shows an example of signals when the rotor is fixed and the electrical angle θe is a specific value (135°). The excitation signal, the SIN signal, and the COS signal all contain a component sin(2πf _r t). In the excitation signal, the amplitude E of the sin(2πf _r t) component is a constant value, whereas in the SIN signal and the COS signal, the amplitude of the sin (2πf _r t) component varies according to sin θe or cos θe.

Therefore, when the rotor rotates, the amplitudes of the SIN signal and the COS signal as shown in FIG. 2A change at the excitation frequency f _r and at the frequency of the electrical angle θe. In an actual resolver, the excitation frequency f _r (eg, 10 kHz) is higher than the frequency of the electrical angle θe (eg, several Hz to several hundred Hz). While frequently changing at f _r , it also changes slowly at the frequency of the electrical angle θe, resulting in a signal such that sin θe and cos θe of the electrical angle θe appear on the envelope. In this embodiment, the fact that the frequency of the electrical angle .theta.e is lower than the excitation frequency _fr is used to obtain the current electrical angle .theta.e based on the signal within a predetermined period prior to the current time. For example, in the example shown in FIG. 2A, if the current time is t ₀ , the electrical angle θe at time t ₀ is obtained based on the signal for the period T.

That is, the phase relationship between the excitation signal and the output signal at a certain electrical angle θe and the amplitude relationship of the output signal depend on the characteristics of the resolver 11 (configuration of windings, etc.). Therefore, when using a specific resolver 11, if the combination of the phase relationship between the excitation signal and the output signal and the amplitude of the two-phase output signal is associated with the electrical angle θe, the phase relationship and the relationship between the combination of the amplitudes and the electrical angle θe, the electrical angle θe can be obtained.

For example, the example shown in FIG. 2A is an excitation signal, a SIN signal, and a COS signal when the electrical angle θe in a certain resolver 11 is 135°. When the electrical angle θe is 135°, sin θe included in the SIN signal is 1/2 ^1/2 and cos θe included in the COS signal is -1/2 ^1/2 . Therefore, the SIN signal has a waveform in phase with sin(2πf _r t) that changes at the excitation frequency f _r . On the other hand, the COS signal has a waveform that is opposite in phase to sin (2πf _r t) that changes at the excitation frequency f _r . Furthermore, since sin θe is 1/2 ^1/2 and cos θe is -1/2 ^1/2 , the absolute values are equal and the amplitudes of the SIN signal and the COS signal are equal. Thus, if the phase relationship between the excitation signal and the SIN signal and the phase relationship between the excitation signal and the COS signal are specified, and the amplitudes of the SIN signal and the COS signal are specified, the electrical angle θe can be specified from the combination of these. it becomes possible to

FIG. 2B is a diagram showing changes in the phase relationship between the excitation signal and the output signal depending on the electrical angle θe in the resolver 11 according to this embodiment. FIG. 2B shows the phase relationship between the excitation signal and the COS signal and the phase relationship between the excitation signal and the SIN signal when the electrical angle θe of the resolver varies from 0° to 360°. For example, in the range where the electrical angle θe is 135°, the excitation signal and the COS signal are out of phase, and the excitation signal and the SIN signal are in phase. This situation is consistent with FIG. 2A.

FIG. 2C is a diagram showing changes in the amplitudes of the SIN signal and the COS signal depending on the electrical angle θe in the resolver 11 according to this embodiment. The amplitudes of the SIN signal and the COS signal are positive when they are in phase with the excitation signal, and negative when they are in opposite phase. In FIG. 2C, the horizontal axis represents the amplitude of the COS signal, the vertical axis represents the amplitude of the SIN signal, and the coordinates represented by (amplitude of the COS signal, amplitude of the SIN signal) are plotted on a plane defined by the axes. Points are indicated by a dashed line. Since the amplitude of the COS signal is Kcos θe and the amplitude of the SIN signal is Ksin θe, the plot on the plane shown in FIG. 2C is circular as indicated by the dashed line. Also, the electrical angle θe is the angle between the positive direction of the COS axis and a line extending from the origin to the coordinates on the circle, as shown in FIG. 2C. When the electrical angle θe is 135°, sin θe is 1/2 ^1/2 and cos θe is -1/2 ^1/2 , so the amplitude of the SIN signal is K/2 ^1/2 and the amplitude of the COS signal is - K/2 ^1/2 . Therefore, when the coordinates represented by (COS signal amplitude, SIN signal amplitude) are specified, the electrical angle θe can be specified.

In this embodiment, a configuration is adopted in which the amplitudes (absolute values) of two-phase output signals are obtained, and four candidates for the electrical angle θe are generated when the absolute values of the amplitudes are obtained. For example, in the example shown in FIG. ^2C , there are four points (45°, ¹³⁵ ° , 225°, 315°) are present. Therefore, in the present embodiment, the range of the electrical angle θe is specified based on the phase relationship between the excitation signal and the COS signal and the phase relationship between the excitation signal and the SIN signal (the four quadrants shown in FIG. 2C). By specifying which one it is, the electrical angle θe is specified.

As described above, the electrical angle θe of the resolver 11 can be obtained by analyzing the excitation signal and the output signal. However, the relationship of signals as in FIG. 2A described above is an idealized state, and actual signals may change more complicatedly. For example, the excitation signal, SIN signal, and COS signal to be analyzed in the electrical angle acquisition system 10 are signals amplified by amplifiers (amplifier 12 and amplifiers 13a to 13c). These amplifiers are analog amplifier circuits and generally include resistance elements, capacitor elements, inductance elements, and the like, so the phase of the signal after amplification may change. In addition, noise is included due to various factors.

For this reason, the ideal relationship shown in FIG. 2A is not necessarily the case, and when the output signal is out of phase with the excitation signal as shown in FIG. Frequency components other than the frequency f _r may be included. Therefore, when the electrical angle θe is obtained based on the analog signals output from the amplifiers 13a to 13c, an error occurs in the electrical angle θe. Therefore, in this embodiment, a configuration is adopted in which the excitation signal, the SIN signal, and the COS signal output from the amplifiers 13a to 13c are subjected to Fourier transform, and the excitation frequency component is extracted and analyzed.

The excitation signal acquisition unit 20 includes a circuit for acquiring the excitation frequency component of the excitation signal by Fourier transform. Specifically, the excitation signal acquisition unit 20 includes an analog-to-digital conversion unit 21a and a Fourier transform unit 22a. The analog-to-digital converter 21a is a circuit that converts the analog excitation signal output from the amplifier 13a into digital data. That is, the analog-to-digital converter 21a has a function of sampling the analog excitation signal at the sampling frequency _fs and outputting it as a digital data string.

FIG. 3 is a diagram for explaining analog-to-digital conversion and sampling, and shows analog-to-digital conversion and sampling using the signal shown in FIG. 2A as an example. In FIG. 3, the sampling period (1/f _s ) defined by the sampling frequency f _s is indicated by a dashed line. As shown in FIG. 3, the analog-to-digital converter 21a converts the analog excitation signal into a digital value every sampling period (1/f _s ) to generate a digital data string. In FIG. 3, white circles indicate examples of sampled data.

The Fourier transform unit 22a is a circuit that Fourier transforms the digital data string output from the analog-to-digital converter 21a. Fourier transform can be implemented by, for example, FFT (Fast Fourier Transform). That is, the Fourier transform unit 22a has a function of receiving a digital data string output from the analog-to-digital converter 21a, performing a Fourier transform based on the digital data string of N sampling numbers, and outputting it as a digital data string. . Here, the excitation signal after the Fourier transform is called an excitation Fourier signal. When the sampling number N is 16, the digital data strings to be Fourier transformed are p(0) to p(15). FIG. 3 shows the beginning and end (p(0), p(15)) of a digital data string when the sampling number N is 16. In FIG.

The Fourier transform unit 22a Fourier transforms the N pieces of digital data sampled in this manner using equation (1).

When the excitation Fourier signal is generated by the above equation (1), the Fourier transform section 22a selects and outputs the excitation frequency component from the excitation Fourier signal. That is, when the excitation Fourier signal is obtained by the transformation according to the equation (1), X(k) is obtained for each of k=0 to N−1. If the frequency resolution of the Fourier transform is f ₀ (f ₀ =f _s /N), then k×f ₀ corresponds to the frequency, so X(k) can be regarded as a signal of frequency k×f ₀ .

Therefore, in the present embodiment, the Fourier transform unit 22a acquires the excitation frequency component by selecting k such that k×f ₀ is the excitation frequency f _r or k×f ₀ that is closest to the excitation frequency f _r . . Here, it suffices if the excitation frequency component can be obtained from the Fourier-transformed excitation Fourier signal, and various modes can be adopted for the selection of k. In this embodiment, N, f _r , and f _s are determined in advance by the parameter setting unit 70 to be described later so that k×f ₀ is always equal to the excitation frequency f _r . That is, in the present embodiment, N, f r _and f _s are determined in advance so that m is an integer when m=N×f _r /f _s .

With N, f _r and f _s determined in this way, we can have m×f _s /N=f _r (i.e., m×f ₀ =f _r ), where m×f ₀ is the excitation frequency It becomes possible to choose m to be f _r . However, according to the Fourier transform sampling theorem, f _s >2f _r . In this embodiment, m=N×f _r /f _s is thus set to be an integer, and the Fourier transform unit 22a selects m such that m×f ₀ is the excitation frequency _fr . Then, by selecting X(m) from the excitation Fourier signals X(k) (k=0 to N−1) obtained by Fourier transform, the excitation frequency component of the excitation signal is obtained.

Hereinafter, the excitation frequency component extracted from the excitation Fourier signal obtained by Fourier transform will be expressed as P(m)=Pr+iPi. where Pr is the real part obtained by the Fourier transform, Pi is the imaginary part obtained by the Fourier transform, and i before Pi is the imaginary unit.

The output signal acquisition unit 30 includes a circuit for acquiring the excitation frequency components of the two-phase output signals by Fourier transform. Specifically, the output signal acquisition unit 30 includes analog-to-digital conversion units 31b and 31c and Fourier transformation units 32b and 32c. The analog-to-digital converters 31b and 31c are circuits for converting analog SIN signals and COS signals output from the amplifiers 13b and 13c into digital data. That is, the analog-to-digital converters 31b and 31c have a function of sampling the analog output signal at the sampling frequency _fs and outputting it as a digital data string. In the example shown in FIG. 3, the analog-to-digital converters 31b and 31c convert analog output signals sampled at each sampling period (1/f _s ) into digital values, which are indicated by white circles. there is

The Fourier transform units 32b and 32c are circuits that Fourier transform the digital data strings output from the analog-to-digital converters 31b and 31c. That is, the Fourier transform units 32b and 32c have the function of receiving the digital data strings output from the analog-to-digital converters 31b and 31c, performing Fourier transform based on the digital data strings of N sampling numbers, and outputting them as digital data strings. have. Here, the output signal after Fourier transform is called an output Fourier signal. Also, let s(0) to s(15) be the digital data string of the SIN signal to be subjected to the Fourier transform when the sampling number N is 16. FIG. Let c(0) to c(15) be a digital data string of a COS signal to be subjected to Fourier transform when the sampling number N is 16. FIG.

The Fourier transform units 32b and 32c Fourier transform the N pieces of digital data sampled in this way according to the above equation (1). When the output Fourier signal is generated by the above equation (1), the Fourier transform units 32b and 32c select and output the excitation frequency component from the output Fourier signal. In other words, when the conversion according to equation (1) is performed and the output Fourier signal is obtained, X(k) is obtained for each of k=0 to N−1. Also, as described above, N, f r and f _s are determined in advance so _that m is an integer when m=N×f _r /f _s . Therefore, the Fourier transform units 32b and 32c select m such that m×f ₀ is the excitation frequency f _r , and convert the output Fourier signal X(k) (k=0 to N−1) obtained by the Fourier transform to X Select (m).

By performing such selection in each of the Fourier transform units 32b and 32c, the excitation frequency component of the SIN signal as the output signal and the excitation frequency component of the COS signal as the output signal are acquired. Hereinafter, the excitation frequency component extracted from the SIN signal, which is the output Fourier signal obtained by Fourier transform, is expressed as S(m)=Sr+iSi. where Sr is the real part obtained by the Fourier transform, Si is the imaginary part obtained by the Fourier transform, and i before Si is the imaginary unit. Also, the excitation frequency component extracted from the COS signal, which is the output Fourier signal obtained by Fourier transform, is expressed as C(m)=Cr+iCi. where Cr is the real part obtained by the Fourier transform, Ci is the imaginary part obtained by the Fourier transform, and i before Ci is the imaginary unit.

In the present embodiment, the analog-to-digital conversion unit 21a of the excitation signal acquisition unit 20 samples the analog excitation signal, and the analog-to-digital conversion units 31b and 31c of the output signal acquisition unit 30 output signals (SIN signal, COS signal) are sampled at the same time. That is, in the electrical angle acquisition system 10 according to the present embodiment, as shown in FIG. 1, analog-to-digital converters 21a, 31b, and 31c are provided in parallel. A signal is input. Then, as shown in FIG. 3, sampling is performed simultaneously at the sampling frequency _fs in each conversion unit. According to the above configuration, the relationship between the excitation signal and the output signal can be analyzed without considering the phase shift due to the sampling timing shift. It should be noted that it is sufficient here that the sampling timings match to the extent that it is not necessary to consider the phase shift, and that the sampling timings are allowed to shift within this range.

Furthermore, in this embodiment, Fourier transform units 22a, 32b, and 32c are provided for Fourier transforming the excitation signal, the SIN signal, and the COS signal, respectively, and the three types of signals are Fourier transformed in parallel. However, if it is permissible for the Fourier transform to take a long time, one or two Fourier transform units may be provided, and at least two signals, the excitation signal, the SIN signal, and the COS signal, may be combined into one Fourier transform. A configuration may be employed in which Fourier transform is performed by the transform unit (the same applies to other embodiments below).

The phase relationship acquisition unit 40 includes a circuit for acquiring the phase relationship between the excitation signal and the two-phase output signal based on the excitation frequency component of the excitation signal and the excitation frequency component of the two-phase output signal. ing. That is, the phase relationship acquisition unit 40 identifies whether the excitation signal and the SIN signal are in phase or out of phase, and identifies whether the excitation signal and the COS signal are in phase or out of phase.

Acquisition of the phase relationship may be performed in a variety of ways. In the present embodiment, the phase relationship is acquired using rotation of the coordinate axes of the complex plane that allows plotting of the real and imaginary parts after the Fourier transform. do. FIG. 4A shows a complex plane, in which the horizontal axis is the real axis Re and the vertical axis is the imaginary axis Im. In the present embodiment, the phase relation acquisition unit 40 identifies the rotation angle of the coordinate axis based on the plotted position of the excitation frequency component P(m)=Pr+iPi of the excitation signal on the complex plane.

That is, the phase relationship acquisition unit 40 acquires the phase angle α of the excitation frequency component P(m) of the excitation signal as the rotation angle of the coordinate axis. The phase angle α is arctan (Pi/Pr), but when calculating the phase angle α, it is calculated by a method that does not become indefinite even if Pr is 0 (for example, atan2 (Pi , Pr), etc.) preferably. To simplify the explanation below, the atan2(y, x) function that is commonly used in the fields of science and engineering will be used. Note that there is the following relationship with the standard arctan(y/x).
if x > 0 then atan2(y,x) = arctan(y/x)
If y≧0, x<0, then atan2(y,x)=arctan(y/x)+π
If y<0, x<0, then atan2(y,x)=arctan(y/x)−π
If y>0, x=0 then atan2(y,x)=π/2
If y<0, x=0, then atan2(y,x)=−π/2
When y = 0 and x = 0, atan2 (y, x) = undefined When the coordinate axis is rotated by the phase angle α, the coordinate axis rotates as indicated by the dashed line in FIG. 4A, and the real axis Re Re', and the imaginary axis Im becomes the imaginary axis Im'. As a result, in the real axis Re' and the imaginary axis Im' after rotation, only the real part of the excitation frequency component P(m) of the excitation signal remains (denoted as Pr'), and the imaginary part becomes zero. It should be noted that Pr′=Pr×cosα+Pi×sinα.

Even if the coordinate axes are rotated, the phase relationship between the excitation signal and the two-phase output signals remains unchanged. Therefore, the phase relationship can be identified by expressing the excitation frequency components of the SIN signal and the COS signal based on the real axis Re' and the imaginary axis Im' after rotation and identifying the relationship with Pr'. Therefore, the phase relationship acquisition unit 40 acquires the real part Sr′ when the excitation frequency component of the SIN signal is expressed by the rotated coordinate axes as Sr′=Sr×cosα+Si×sinα. The excitation frequency component of the SIN signal is originally synchronized with the excitation frequency component of the excitation signal, and the phase shift should be small, so the imaginary part Si' can be ignored.

Further, the phase relationship acquisition unit 40 acquires the real part Cr' when the excitation frequency component of the COS signal is represented by the rotated coordinate axes as Cr'=Cr*cosα+Ci*sinα. Note that the excitation frequency component of the COS signal is originally synchronous with the excitation frequency component of the excitation signal, and the phase shift should be small, so the imaginary part Ci' can be ignored.

When the above coordinate axis conversion is performed, the phase relationship between the excitation signal and the SIN signal can be identified by comparing the signs of Pr' and Sr', and the signs of Pr' and Cr' can be identified. can identify the phase relationship between the excitation signal and the COS signal. Therefore, the phase relation acquisition unit 40 compares the signs of Pr′ and Sr′, and if the signs are the same, the excitation signal and the SIN signal are in phase. do. The phase relation acquisition unit 40 compares the signs of Pr' and Cr', and determines that the excitation signal and the COS signal have the same phase if they have the same sign, and that the excitation signal and the COS signal have opposite phases if they have different signs.

As described above, according to the configuration in which the coordinate axis of the complex plane is rotated to acquire the phase relationship, there is no need to calculate the imaginary parts of the SIN signal and the COS signal, and the amount of calculation can be reduced. Of course, if the amount of calculation is not important, the configuration may be such that the imaginary part is calculated. Furthermore, in the method of obtaining the phase relationship as in the present embodiment, it is only necessary to be able to determine whether the phase is in-phase or anti-phase. Therefore, if the phase shift of the SIN signal and COS signal with respect to the excitation signal is smaller than ±90°, the phase relationship can be obtained accurately. The permissible range of the deviation is much wider than that of the conventional tracking loop type digital angle converter (the permissible range is ±10° or ±45°). Although the real axis Re is rotated so as to overlap P(m) here, the imaginary axis Im may be rotated so as to overlap P(m) and the imaginary part may be used for determination.

After performing the determination as described above, the phase relation acquisition unit 40 outputs a signal indicating the determination result. In the present embodiment, the phase relationship acquisition section 40 outputs a DirSin signal indicating the phase relationship between the excitation signal and the SIN signal, and a DirCos signal indicating the phase relationship between the excitation signal and the COS signal. When the excitation signal and the SIN signal are in phase, a signal indicating DirSin=1 is output, and when they are in opposite phase, a signal indicating DirSin=-1 is output. When the excitation signal and the COS signal are in phase, a signal indicating DirCos=1 is output, and when they are in opposite phase, a signal indicating DirCos=-1 is output.

The amplitude acquisition unit 50 is a circuit for acquiring the amplitude of the two-phase output signals based on the excitation frequency components of the two-phase output signals (SIN signal and COS signal). That is, the amplitude obtaining section 50 obtains the excitation frequency component S(m) of the SIN signal, and obtains the amplitude PwrSin=(Sr ² +Si ² ) ^1/2 based on the real part Sr and the imaginary part Si. Then, the amplitude acquisition section 50 outputs a signal PwrSin indicating the amplitude of the SIN signal. Further, the amplitude obtaining section 50 obtains the excitation frequency component C(m) of the COS signal, and obtains the amplitude PwrCos=(Cr ² +Ci ² ) ^1/2 based on the real part Cr and the imaginary part Ci. Then, the amplitude acquisition section 50 outputs a signal PwrCos indicating the amplitude of the COS signal.

The electrical angle acquisition unit 60 is a circuit for acquiring the electrical angle θe of the resolver 11 based on the phase relationship and the amplitudes of the two-phase output signals. That is, the electrical angle acquisition unit 60 acquires the electrical angle θe based on DirSin and DirCos indicating the phase relationship and PwrSin and PwrCos indicating the amplitude. The electrical angle θe may be acquired by various methods, and in the present embodiment, the electrical angle acquisition section 60 acquires the electrical angle by executing the electrical angle calculation process shown in FIG. 4B. Here, description will be made with reference to the relationship between the phases of the excitation signal and the output signal shown in FIG. 2B and the electrical angle θe for each amplitude shown in FIG. 2C. In FIG. 2C, the range of the electrical angle θe is divided by 90°, the range of 0° to 90° is the first quadrant Z1, the range of 90° to 180° is the second quadrant Z2, and the range of 180° to 270° The range will be described as the third quadrant Z3, and the range from 270° to 360° as the fourth quadrant Z4.

Specifically, the electrical angle acquisition unit 60 determines whether or not DirCos, which indicates the phase relationship between the excitation signal and the COS signal, is 1, that is, whether or not the excitation signal and the COS signal are in phase. (step S100). If it is determined in step S100 that DirCos is 1 (the excitation signal and the COS signal are in phase), the electrical angle θe is 0° to 90° or 270° to 360° as shown in FIG. 2B. Therefore, the electrical angle θe is included in either the first quadrant Z1 or the fourth quadrant Z4 shown in FIG. 2C.

When it is determined in step S100 that DirCos is 1, the electrical angle acquisition unit 60 determines whether DirSin, which indicates the phase relationship between the excitation signal and the SIN signal, is 1. are in phase (step S105). If it is determined in step S105 that DirSin is 1 (the excitation signal and the SIN signal are in phase), the electrical angle θe is 0° to 90° or 90° to 180° as shown in FIG. 2B. Therefore, the electrical angle θe is included in the first quadrant Z1 shown in FIG. 2C. Therefore, when it is determined in step S105 that DirSin is 1, the electrical angle obtaining unit 60 uses the above-described atan2 function to calculate the electrical angle θe by atan2(PwrSin, PwrCos) (step S110).

On the other hand, when DirSin is not determined to be 1 in step S105, the excitation signal and the SIN signal are in opposite phase. Therefore, the electrical angle θe is between 180° and 270° or between 270° and 360° as shown in FIG. 2B. Therefore, the electrical angle θe is included in the fourth quadrant Z4 shown in FIG. 2C. Therefore, if DirSin is not determined to be 1 in step S105, the electrical angle acquisition unit 60 calculates the electrical angle θe by atan2(−PwrSin, PwrCos) (step S115). As described above, in the present embodiment, since the amplitudes PwrSin and PwrCos are obtained as positive values, the electrical angle θe can be calculated by calculating atan2 while specifying the positive/negative relationship based on the phase relationship. get.

If DirCos is not determined to be 1 in step S100, the excitation signal and the COS signal are in opposite phase, so the electrical angle θe is 90° to 180° or 180° to 270° as shown in FIG. 2B. be. Therefore, the electrical angle θe is included in either the second quadrant Z2 or the third quadrant Z3 shown in FIG. 2C.

In step S100, if DirCos is not determined to be 1, the electrical angle acquisition unit 60 determines whether DirSin, which indicates the phase relationship between the excitation signal and the SIN signal, is 1. are in phase (step S120). If it is determined in step S120 that DirSin is 1 (the excitation signal and the SIN signal are in phase), the electrical angle θe is 0° to 90° or 90° to 180° as shown in FIG. 2B. Therefore, the electrical angle θe is included in the second quadrant Z2 shown in FIG. 2C. Therefore, when it is determined in step S120 that DirSin is 1, the electrical angle obtaining unit 60 calculates the electrical angle θe by atan2(PwrSin, -PwrCos) (step S125).

On the other hand, if DirSin is not determined to be 1 in step S120, the excitation signal and the SIN signal are in opposite phase. Therefore, the electrical angle θe is between 180° and 270° or between 270° and 360° as shown in FIG. 2B. Therefore, the electrical angle θe is included in the third quadrant Z3 shown in FIG. 2C. Therefore, if DirSin is not determined to be 1 in step S120, the electrical angle obtaining unit 60 calculates the electrical angle θe by atan2 (-PwrSin, -PwrCos) (step S130).

When the electrical angle θe is calculated by the above processing, the electrical angle obtaining section 60 outputs a signal indicating the electrical angle θe. Therefore, by obtaining the output signal of the electrical angle obtaining unit 60 outside the electrical angle obtaining system 10, the electrical angle can be specified. In the electrical angle calculation process described above, the phases of the excitation signal and the SIN signal are compared, and the phases of the excitation signal and the COS signal are compared. The determination may be made using this relationship. That is, the phases of the excitation signal and the SIN signal are compared, and the phases of the SIN signal and the COS signal are compared. Phase comparison configurations may also be used, and these examples are substantially equivalent to the example shown in FIG. 4B above.

The parameter setting section 70 is a circuit for inputting at least one of the sampling frequency f _s , the sampling number N, and the excitation frequency _fr . That is, the parameter setting unit 70 has an interface to which a signal line can be connected from the outside of the electrical angle acquisition system 10, and the user can set the sampling frequency f _s , the number of samples N, and the excitation frequency f _r through the interface. can be entered. Various specifications may be used for the interface. For example, a specification including at least one of an input by serial communication, an input by an I/O terminal, and an input by a voltage value, or the like can be adopted. Various standards such as an IIC bus can be assumed for serial communication. For input through the I/O terminal, it is possible to envision a mode in which voltages of different voltage values are applied to the terminals and information is input using a code indicated by one or more voltage values. For the input by voltage value, it is conceivable that the input information is designated by the level of the applied voltage. Moreover, it may be adjustable by a switch, a knob, or the like.

In any case, the parameter setting section 70 can receive information indicating at least one of the sampling frequency f _s , the sampling number N, and the excitation frequency f _r , and can operate each section according to the received parameters. . That is, the parameter setting section 70 is connected to the excitation signal generation section 13 via a signal line or the like, and outputs the excitation frequency f _r input by the user to the excitation signal generation section 13 . The excitation signal generator 13 can generate a sine wave at a frequency input via a signal line or the like. Therefore, the excitation signal becomes a sine wave of the excitation frequency f _r input by the user. The parameter setting unit 70 may be able to input all of the sampling frequency f _s , the number of samples N, and the excitation frequency f _r , or may be able to input some of them. If some are inputtable, the parameters that are not input are predetermined.

The parameter setting section 70 is also connected to the excitation signal acquisition section 20 and the output signal acquisition section 30 via signal lines and the like. The sampling frequency f _s input by the user is supplied to the analog-to-digital conversion section 21a of the excitation signal acquisition section 20 via a signal line or the like, and is supplied to the analog-to-digital conversion sections 31b and 31c of the output signal acquisition section 30. FIG. The analog-to-digital converters 21a, 31b, and 31c can generate digital data strings by sampling analog signals at frequencies input via signal lines or the like. Therefore, the analog-to-digital converters 21a, 31b, and 31c sample the analog signals input from the amplifiers 13a to 13c at the sampling frequency f _s to generate and output digital data strings.

Further, the sampling number N input by the user is supplied to the Fourier transform section 22a of the excitation signal acquisition section 20 via a signal line or the like, and is supplied to the Fourier transform sections 32b and 32c of the output signal acquisition section 30. FIG. The Fourier transform units 22a, 32b, and 32c can acquire digital data of the number of samples input via a signal line or the like and perform Fourier transform. Therefore, the Fourier transform units 22a, 32b, and 32c sample the digital data strings generated by the analog-to-digital converters 21a, 31b, and 31c at the sampling number N and perform Fourier transform to generate excitation Fourier signals and output Fourier signals. can be done.

As described above, in the present embodiment, the excitation signal having the excitation frequency f _r input by the user to the parameter setting unit 70 is generated, and the excitation signal and the output signal are sampled at the sampling frequency f _s with N samples. It can be sampled and Fourier transformed. Therefore, the user can easily set m=N×f _r /f _s to be an integer.

Each part constituting the electrical angle acquisition system 10 may be configured by a dedicated circuit (for example, an IC chip, etc.), or a general-purpose circuit (for example, a program execution environment such as a CPU, RAM, ROM, etc.) may be configured by a program. It may be realized by operating, and various configurations can be adopted. Of course, one or a plurality of functions may be configured with one chip, or may be configured with a plurality of chips. Also, an FPGA (Field Programmable Gate Array) that can be programmed after manufacturing or a reconfigurable processor (Reconfigurable Processor) that can reconfigure connections and settings of internal circuit cells may be used. Also, if a technology for integrating circuits to replace LSIs emerges due to advances in semiconductor technology or another technology derived therefrom, it is of course possible to integrate the functional blocks using that technology.

In the present embodiment as described above, the excitation frequency component is extracted by Fourier transform to analyze the phase relationship between the excitation signal and the output signal and the amplitude of the output signal. Therefore, it is possible to obtain the electrical angle θe accurately compared to a configuration that analyzes the phase relationship and amplitude without performing Fourier transform. In particular, since the excitation signal and the output signal are amplified by the amplifiers 13a to 13c as in the present embodiment, even if the phase differs from the ideal signal or noise is included, the electrical angle θe can be accurately calculated. can be obtained.

Further, in the conventional tracking loop type digital angle converter as mentioned in Patent Document 1, a SIN signal or a COS signal is multiplied by cos φ or sin φ, and the sum of the obtained signals is calculated as sin(θe−φ)sin (2πf _r t) is generated, synchronous detection is performed to extract the control deviation sin(θe−φ), and feedback control is performed so that the control deviation becomes 0, thereby generating a situation in which φ can be regarded as the electrical angle θe. . Therefore, it includes complicated analog circuits such as a circuit for multiplying cos φ and sin φ, a circuit for performing synchronous detection, and a circuit for feedback control (voltage controlled oscillator and counter).

Therefore, in the conventional configuration, it is difficult to simplify the overall configuration, and it is difficult to achieve cost reduction, high reliability, and convenience. However, in this embodiment, a complicated analog circuit is not required, and a simple amplifier may be provided as the analog circuit. Further, since the signal processing after the analog-to-digital conversion units 21a, 31b, and 31c is digital signal processing, the Fourier transformation units 22a, 32b, and 32c, the phase relationship acquisition unit 40, the amplitude acquisition unit 50, and the electrical angle acquisition unit 60 are It can be realized by a circuit with a simple configuration. In addition, since analog circuits have a larger circuit area than digital circuits, the chip area increases when integrated into an IC, resulting in an increase in cost. Therefore, this embodiment can be realized at a lower cost than the conventional technology.

Furthermore, since the characteristics of analog circuits change with temperature, a temperature correction circuit is required. It is realized by digital signal processing. Therefore, no temperature correction circuit is required, and a configuration for obtaining the electrical angle θe with high reliability can be easily realized.

Furthermore, when configuring an electrical angle acquisition system with a complicated analog circuit, it is necessary to adjust and build in the circuit characteristics in order to increase the accuracy of acquiring the electrical angle θe. For this reason, the change of the circuit constant is extremely restricted, and for example, the excitation frequency of the resolver is limited to 10 kHz. However, in this embodiment, the excitation frequency and the like can be adjusted, and the application is not limited to a specific application.

Furthermore, in the above-described prior art, since the feedback loop is constructed so that the control deviation ε=sin(θe−φ)=0, it takes time to stabilize and the operation slows down. In addition, if an attempt is made to speed up the operation, countermeasures against oscillation are required. However, in this embodiment, there is no feedback loop, and the electrical angle θe can be obtained immediately after N samplings. Therefore, it is possible to provide a system that outputs the electrical angle θe at high speed.

Furthermore, in the prior art, it is necessary to reduce noise in input signals such as excitation signals, SIN signals, and COS signals, and it is necessary to consider adding an analog noise filter circuit according to the degree of noise. However, in the present embodiment, since the excitation frequency component is obtained by Fourier transform, the electrical angle θe can be obtained with little influence of noise other than the excitation frequency component. Therefore, it is resistant to noise, and the need for noise countermeasures is low compared to the conventional technology. Therefore, in the present embodiment, the electrical angle θe can be obtained with high accuracy in a situation where noise such as leakage magnetic flux may be included, without taking advanced noise countermeasures.

Furthermore, in the prior art, a phase shift between the excitation signal, the SIN signal, and the COS signal leads to a deterioration in the accuracy of the output angle and a decrease in the response speed, so the phase shift must be reduced. Usually ±10 degrees or ±45 degrees or less is required. However, in this embodiment, the phase shift between the excitation signal, the SIN signal, and the COS signal should be less than ±90°. Therefore, in the present embodiment, the electrical angle θe can be obtained with high accuracy without taking advanced phase shift countermeasures.

(2) Second embodiment:
In the first embodiment described above, the phase relationship and the amplitude relationship are acquired based on the excitation Fourier signal and the output Fourier signal obtained by Fourier transform. A phase relationship may be obtained based on. FIG. 5 is a diagram showing a configuration example for obtaining a phase relationship based on a digital data string that has not undergone Fourier transform.

In FIG. 5, the same components as in FIG. 1 are denoted by the same reference numerals as in FIG. Here, the configuration different from that of FIG. 1 will be described, and the description of the configuration that is the same as that of FIG. 1 will be omitted. The electrical angle acquisition system 100 shown in FIG. 5 does not include the excitation signal acquisition section 20 that acquires the excitation frequency component by Fourier transform. Of course, the excitation signal may be input to the electrical angle acquisition system 100 for purposes other than the calculation of the electrical angle θe (for example, wire breakage detection).

However, in this embodiment, the excitation signal generator 130 and the phase relation acquisition unit 400 are connected. The excitation signal _generation unit 130 has a function of generating a sine wave signal at the excitation frequency f _r set by the parameter setting unit 70, and generates digital data of the sine wave signal at the excitation frequency f r . It has a function of outputting an analog wave signal to the amplifier 12 . In the present embodiment, the excitation signal generator 130 can output the amplitude at any timing of the sine wave signal output as the excitation signal based on the digital data of the sine wave signal. Therefore, the excitation signal generating section 130 can output to the phase relation acquiring section 400 a digital data string equivalent to that obtained by sampling a sine wave signal at the sampling frequency f _s . Based on this output, the phase relationship acquisition section 400 can acquire a digital data string of the excitation signal.

The output signal acquisition unit 300 has functions (analog-to-digital conversion units 31b and 31c and Fourier transform units 32b and 32c) equivalent to those of the output signal acquisition unit 30 in the above-described first embodiment, but signal wiring is different. there is That is, the outputs of the analog-to-digital converters 31b and 31c are supplied to the Fourier transformers 32b and 32c, and also supplied to the phase relationship acquisition section 400. FIG.

The phase relationship acquisition unit 400 is a circuit that acquires the phase relationship between the excitation signal and the output signal (SIN signal and COS signal). . In other words, the phase relation obtaining section 400 obtains the phase relation by multiplying the positive/negative value of the excitation signal by the output signal.

Specifically, while acquiring a digital data string p(n) indicating the excitation signal, the phase relationship acquisition unit 400 determines whether the value of p(n) is positive, negative, or 0. Convert (n) to p'(n). That is, if p(n)>0, p'(n)=1, if p(n)<0, p'(n)=-1, and if p(n)=0, Convert p'(n)=0. Here, n is 0 to N-1. FIG. 6 is a diagram showing an example of processing by the phase relationship acquisition unit 400, and an excitation signal p(n) similar to the excitation signal shown in FIG. 3 is shown at the top. A digital data string at the sampling timing is indicated by a white circle. In FIG. 6, p'(n) after conversion is also shown below the excitation signal p(n). As shown in these figures, p'(n) after conversion becomes a digital data string that takes either 1, -1, or 0 depending on whether the value of the excitation signal is positive or negative or 0. FIG. According to such conversion, the phase relationship can be evaluated while excluding the influence of the amplitude of the excitation signal. Note that p'(n) may be generated by a circuit instead of being converted from p(n).

The phase relation obtaining section 400 obtains the phase relation between the excitation signal and the SIN signal based on the sum of the products of p′(n) and the SIN signal s(n) thus obtained. That is, the phase relationship acquisition section 400 calculates the determination index Dis based on the following equation (2). If the determination index Dis is positive, the phase relation acquisition unit 400 determines that the excitation signal and the SIN signal are in phase, and if the determination index Dis is negative, the excitation signal and the SIN signal are out of phase. I judge.

Note that s(n) is a digital data string supplied from the analog-to-digital conversion unit 31b to the phase relationship acquisition unit 400. FIG. FIG. 6 also shows an example of the SIN signal s(n), and also shows the product of the SIN signal s(n) and p'(n). In this example, the product of the SIN signals s(n) and p'(n) is positive, so the determination index Dis is also positive, and it is determined that they are in phase. This determination result matches the phase relationship between the excitation signal and the SIN signal shown in FIG. As a result of the determination as described above, if the excitation signal and the SIN signal are in phase, the phase relation acquisition unit 400 outputs a signal indicating that DirSin=1. Also, if the excitation signal and the SIN signal are in opposite phases, the phase relation acquisition section 400 outputs a signal indicating DirSin=-1.

Further, the phase relation obtaining section 400 obtains the phase relation between the excitation signal and the COS signal based on the sum of the products of p′(n) and the COS signal c(n). That is, the phase relationship acquisition section 400 calculates the determination index Dic based on the following equation (3). If the determination index Dic is positive, the phase relation acquisition unit 400 determines that the excitation signal and the COS signal are in phase, and if the determination index Dic is negative, the excitation signal and the COS signal are out of phase. I judge.

Note that c(n) is a digital data string supplied from the analog-to-digital conversion unit 31c to the phase relationship acquisition unit 400. FIG. FIG. 6 also shows an example of the COS signal c(n) and the product of the COS signal c(n) and p'(n). In this example, since the product of the COS signals c(n) and p'(n) is negative, the determination index Dic is also negative, and it is determined that the phase is reversed. This determination result matches the phase relationship between the excitation signal and the COS signal shown in FIG. As a result of the above determination, if the excitation signal and the COS signal are in phase, the phase relationship acquisition section 400 outputs a signal indicating that DirCos=1. Also, if the excitation signal and the COS signal are in opposite phases, the phase relationship acquisition section 400 outputs a signal indicating that DirCos=-1. Note that the above calculation is an example, and for example, in formulas (2) and (3), p(n) instead of p'(n) is multiplied by s(n) or c(n). Also good.

The signals (DirSin, Dircos) output from the phase relationship acquisition unit 400 as described above are the same as in the first embodiment, and the amplitude acquisition unit 50 in the present embodiment is the same as in the first embodiment. . Therefore, the electrical angle acquisition unit 60 in this embodiment can acquire the electrical angle by performing the same processing as in the first embodiment based on the output signal of the phase relationship acquisition unit 400 and the output signal of the amplitude acquisition unit 50. can. Even in the above configuration, since the excitation frequency component of the output signal is obtained by Fourier transform, it is possible to obtain the electrical angle θe while excluding the effects of signals other than the excitation frequency component. Even if , the electrical angle θe can be obtained accurately.

(3) Third embodiment:
In the first embodiment described above, the timing at which the excitation signal is sampled and the timing at which the output signal is sampled are the same. The timings for sampling the two-phase output signals may be different timings. FIG. 7 is a diagram showing a configuration example in which the excitation signal and the two-phase output signal are sampled at different timings.

In FIG. 7, the same components as in FIG. 1 are denoted by the same reference numerals as in FIG. Here, the configuration different from that of FIG. 1 will be described, and the description of the configuration that is the same as that of FIG. 1 will be omitted. The electrical angle acquisition system 110 shown in FIG. 7 is realized by sharing some functions of the excitation signal acquisition section and the output signal acquisition section. In this sense, in FIG. 7, the excitation signal acquisition section and the output signal acquisition section are shown in one rectangle and indicated by one reference numeral 310 .

The excitation signal acquisition section and the output signal acquisition section indicated by reference numeral 310 include a multiplexer 211a, an analog-to-digital conversion section 210a, and Fourier transformation sections 22a, 32b, and 32c. The configurations of Fourier transform units 22a, 32b, and 32c are the same as in the first embodiment. The multiplexer 211a is a 3-input 1-output multiplexer to which the outputs of the amplifiers 13a to 13c are connected. That is, the multiplexer 211a is a circuit that switches the relationship between input and output at a constant timing. In this embodiment, the multiplexer 211a specifies the sampling period 1/f _s from the sampling frequency f _s set by the parameter setting section 70, and the input and the output at a period that is ⅓ of the sampling period 1/f _s . It has a function to switch relationships.

In this embodiment, the multiplexer 211a is configured to output the excitation signal, the SIN signal, and the COS signal in this order, and outputs the excitation signal again after the COS signal. Therefore, the multiplexer 211a repeats the operation of outputting the excitation signal, the SIN signal, and the COS signal in this order. Of course, the order of each signal is an example, and the order is arbitrary.

The analog-to-digital converter 210a is a circuit for generating a digital data string by sampling each of the excitation signal, the SIN signal, and the COS signal at the sampling frequency _fs . That is, the analog-to-digital conversion section 210a identifies the sampling period 1/f _s from the sampling frequency f _s set by the parameter setting section 70, and converts the analog signal input to the analog-to-digital conversion section 210a to the sampling period 1/f. It converts to a digital data string at a period of 1/3 of _s .

FIG. 8 is a diagram for explaining how the excitation signal, SIN signal, and COS signal are sampled. Each signal shown in FIG. 8 is equivalent to each signal shown in FIG. Here, an example of generating data of sampling number N=8 from each of such signals at sampling frequency f _s will be described. The analog-to-digital converter 210a samples the excitation signal, the SIN signal, and the COS signal in this order with a period of 1/3 of the sampling period 1/ _fs . An example is shown, where sampling produces digital data c(0) of the COS signal. After that, when ⅓ of the sampling period 1/ _fs has passed, the excitation signal is input to the analog-to-digital converter 210a by the multiplexer 211a. Therefore, when the analog-to-digital converter 210a performs the next sampling, digital data p(0) of the excitation signal is generated.

Further, when ⅓ of the sampling period 1/ _fs has elapsed, the SIN signal is input to the analog-to-digital converter 210a by the multiplexer 211a. Therefore, when the analog-to-digital converter 210a performs the next sampling, digital data s(0) of the SIN signal is generated. Since the analog-to-digital conversion unit 210a thereafter performs sampling at a period of 1/3 of the sampling period 1/f _s , the COS signals c(0) to c(7 ), excitation signals p(0) to p(7), and SIN signals s(0) to s(7).

Further, the analog-to-digital converter 210a is connected to the Fourier transform units 22a, 32b, and 32c, and switches the output destination at a period of ⅓ of the sampling period 1/ _fs . That is, when the analog-to-digital conversion unit 210a performs analog-to-digital conversion at the timing when the excitation signal is output from the multiplexer 211a, the analog-to-digital conversion unit 210a outputs the converted digital data to the Fourier transform unit 22a. When the analog-to-digital conversion unit 210a performs analog-to-digital conversion at the timing when the SIN signal is output from the multiplexer 211a, the analog-to-digital conversion unit 210a outputs the converted digital data to the Fourier transform unit 32b. When the analog-to-digital conversion unit 210a performs analog-to-digital conversion at the timing when the COS signal is output from the multiplexer 211a, the analog-to-digital conversion unit 210a outputs the converted digital data to the Fourier transform unit 32c.

In the present embodiment, the analog-to-digital conversion unit 210a repeats this switching at a period of ⅓ of the sampling period 1/f _s , so that the Fourier transform unit 22a receives an excitation signal as in the first embodiment. A digital data string p(n) representing a signal is input. Similarly, a digital data string s(n) representing a SIN signal is input to the Fourier transform unit 32b as in the first embodiment. Further, a digital data string c(n) representing a COS signal is input to the Fourier transform unit 32c as in the first embodiment.

The signals (p(n), s(n), c(n)) input to the Fourier transform units 22a, 32b, and 32c as described above are the same as those in the above-described first embodiment. The Fourier transform units 22a, 32b, and 32c, the phase relationship acquisition unit 40, the amplitude acquisition unit 50, and the electrical angle acquisition unit 60 are the same as those in the first embodiment. Therefore, the Fourier transform units 22a, 32b, and 32c, the phase relationship acquisition unit 40, the amplitude acquisition unit 50, and the electrical angle acquisition unit 60 operate in the same manner as in the first embodiment, so that the electrical angle can be acquired. Even in the above configuration, since the excitation frequency components of the excitation signal and the output signal are obtained by Fourier transform, it is possible to obtain the electrical angle θe in a state where the influence of signals other than the excitation frequency component is excluded. It is possible to obtain the electrical angle θe accurately even if there is a deviation of the electric angle θe.

In this embodiment, since the multiplexer 211a and the analog-to-digital converter 210a sequentially convert the excitation signal, the SIN signal, and the COS signal, digital data at different timings of each signal are captured. Therefore, the phases of the signals indicated by the digital data are out of phase. Therefore, in this embodiment, a configuration for compensating for the phase shift may be provided.

For example, in the expression of the excitation frequency component by the coordinate axes after rotation in the first embodiment, the real part Sr' of the excitation frequency component of the SIN signal is represented by Sr'=Sr×cos(). It can be realized by a configuration or the like obtained as α+β)+Si×sin(α+β). where β is the phase shift, ie, 2π/(3f _s ). In the COS signal, the real part Cr' of the excitation frequency component can be obtained as Cr'=Cr.times.cos(.alpha.-.beta.)+Ci.times.sin(.alpha.-.beta.). In the above configuration, if the phase shift between the SIN signal and the COS signal is less than ±90°, it is possible to accurately identify the phase relationship between the excitation signal, the SIN signal, and the COS signal. In the example of FIG. 8, f _s /f _r =8/3=2.667>2, which satisfies the sampling theorem f _s >2f _r , and the electrical angle θe can be obtained accurately. In addition, in a configuration using a multiplexer as in the third embodiment, for example, the number of analog-to-digital converters can be reduced compared to the first embodiment and the like. Therefore, the electrical angle acquisition system can be constructed at a lower cost.

(4) Fourth to Eighth Embodiments:
In addition, it is possible to construct any embodiment that combines the features of the embodiments described above. FIG. 9 supplies the digital data string of the excitation signal from the excitation signal generation unit to the phase relationship acquisition unit 400 without going through the amplifier as in the second embodiment shown in FIG. Fig. 3 shows an arrangement with a multiplexer as a form; Also in the fourth embodiment shown in FIG. 9, the same reference numerals are assigned to the same configurations as in the above-described embodiment.

In the configuration shown in FIG. 9, the multiplexer 221a has a 2-input 1-output configuration, and the single analog-to-digital converter 220a sequentially converts the SIN signal and the COS signal into digital data. Since the multiplexer 221a has two inputs, the sampling period of the analog-to-digital converter 220a is 1/(2f _s ). The SIN signal and the COS signal thus converted into a digital data string and the digital data string of the excitation signal output from the excitation signal generation section 130 are input to the phase relation acquisition section 400 . The SIN signal and COS signal converted into digital data by the analog-to-digital converter 220a are Fourier-transformed by the Fourier-transformers 32b and 32c, respectively, to obtain excitation frequency components.

FIG. 10 omits the amplifier 13a and the excitation signal acquisition unit 20 for amplifying and capturing the excitation signal from the first embodiment shown in FIG. An excitation signal is supplied from 130 to the phase relationship acquisition unit 40 . However, in the fifth embodiment shown in FIG. 10, the digital data of the excitation signal output by the excitation signal generation section 130 is Fourier transformed by the Fourier transformation section 240a. The excitation Fourier signal Fourier-transformed by the Fourier transform unit 240a is supplied to the phase relationship acquisition unit 40, and the phase relationship is acquired by the same processing as in the first embodiment.

FIG. 11 shows a configuration in which the configuration for performing Fourier transform for obtaining the phase relationship is omitted from the first embodiment shown in FIG. However, in the sixth embodiment shown in FIG. 11, since the excitation signal takes in the signal amplified by the amplifier 13a, the excitation signal is converted into digital data by the analog-to-digital converter 250a. The excitation signal converted to digital data by the analog-to-digital converter 250 a is input to the phase relationship acquisition section 400 . Also, the SIN signal and the COS signal converted into digital data by the analog-to-digital converters 31 b and 31 c are input to the phase relation acquisition section 400 . The phase relationship acquisition unit 400 acquires the phase relationship by the same processing as in the second embodiment.

FIG. 12 replaces the phase relationship acquisition unit 400 of the fourth embodiment shown in FIG. FIG. 12 is a diagram showing a seventh embodiment configured to In the seventh embodiment, a Fourier transform section 360a is provided to Fourier transform the digital data of the excitation signal output by the excitation signal generator 130. FIG.

FIG. 13 is a diagram showing an eighth embodiment in which the third embodiment shown in FIG. 7 is configured to obtain phase relationships from a digital data string that has not undergone Fourier transform. That is, the Fourier transform unit 22a is omitted in the third embodiment, and the phase relationship acquisition unit 40 is replaced with the phase relationship acquisition unit 400. FIG. The eighth embodiment can be configured by supplying the output signal of the analog-to-digital conversion section 210a to the phase relation acquisition section 400. FIG.

(5) Ninth Embodiment:
Furthermore, the electrical angle acquisition system can be used for various purposes other than the configuration for measuring the electrical angle of the resolver 11 during operation of the resolver. FIG. 14 is a diagram showing a configuration example of an electrical angle acquisition characteristic measurement system 190 that measures acquisition characteristics of an electrical angle acquired by the resolver 11. As shown in FIG. That is, in the manufacturing process of the resolver 11, it is often the case that the resolver 11 is shipped after the electrical angle acquisition characteristics of the resolver 11 are specified. In such a case, the electrical angle acquisition system can also be used when measuring the characteristics of the resolver 11 .

Furthermore, in the above-described first embodiment, the excitation signal acquisition unit 20 and the output signal acquisition unit 30 acquire the analog excitation signal and the output signal. The configuration may be such that An electrical angle acquisition characteristic measurement system 190 in FIG. 14 has a configuration for acquiring an excitation signal and an output signal converted into digital data.

In this embodiment, the data acquisition system 200 digitizes the excitation signal and the output signal. The data acquisition system 200 includes amplifiers 13a to 13c and analog-to-digital converters 21a, 31b, and 31c similar to those of the first embodiment. These functions are the same as those of the first embodiment. Therefore, the excitation signal amplified by the amplifier 12 is further amplified by the amplifier 13a and converted into a digital data string by the analog-to-digital converter 21a. Also, the SIN signal, which is the output signal from the resolver 11, is amplified by the amplifier 13b and converted into a digital data string by the analog-to-digital converter 31b. A COS signal, which is an output signal from the resolver 11, is amplified by the amplifier 13c and converted into a digital data string by the analog-to-digital converter 31c.

The data collection system 200 has a FIFO memory 201 . The data collection system 200 is also connected to the electrical angle acquisition characteristic measurement system 190 via a communication cable. The FIFO memory 201 records the digital data strings output from the analog-to-digital converters 21a, 31b, and 31c, and outputs the digital data strings to the electrical angle acquisition characteristic measurement system 190 in a first-in, first-out format. Various cables may be used as the communication cable connecting the data collection system 200 and the electrical angle acquisition characteristic measurement system 190. For example, a USB cable or the like may be used.

In this embodiment, the rotor of the resolver 11 and the encoder 15c are attached to the shaft of the motor 15a (or a portion that rotates in conjunction with the shaft). The motor 15a rotates the shaft by electric power supplied from the motor driver 15b. The encoder 15c outputs a signal (ABZ signal) corresponding to the rotation angle of the rotor. Of course, the output mode of the encoder 15c is an example, and a configuration or the like in which an absolute angle is obtained may be used. The output signal of encoder 15c is input to data acquisition system 200 and sampled simultaneously with other signals.

The data collection system 200 includes a mechanical angle converter 202 that takes in the output signal of the encoder 15c. The mechanical angle converter 202 is a circuit having a function of converting the output signal of the encoder 15c into a mechanical angle. That is, the mechanical angle converter 202 generates data indicating the mechanical angle (0° to 360°) of the rotor based on the output signal of the encoder 15c, and stores the data in the FIFO memory 201. FIG. Data indicating the mechanical angle is also output to the electrical angle acquisition characteristic measurement system 190 in a first-in, first-out format. In this embodiment, the mechanical angle obtained from the output signal of the encoder 15c serves as a reference.

The electrical angle acquisition characteristic measurement system 190 is a general-purpose computer, and includes a control unit (not shown) including a CPU and the like. The control unit can execute a program (not shown), and the program can use the memory 191 as appropriate to execute various functions similar to those of the first embodiment. That is, the control section functions as an excitation signal acquisition section 290 , an output signal acquisition section 390 , a phase relationship acquisition section 40 , an amplitude acquisition section 50 , an electrical angle acquisition section 60 and a parameter setting section 700 . Here, the same functions as in the first embodiment are denoted by the same reference numerals. Note that the control unit functions as the accuracy acquisition unit 800 in addition to these functions.

In the electrical angle acquisition characteristic measurement system 190, the acquisition of data in the memory 191 can be started or stopped in response to a trigger or the like given by the user. When the acquisition is started, the digital data of the excitation signal and the output signal output from the data acquisition system 200 and the data indicating the mechanical angle are recorded in the memory 191 .

The excitation signal acquisition unit 290 has a Fourier transform unit 22a, and can perform the same Fourier transform as in the first embodiment. That is, the excitation signal acquisition unit 290 acquires the excitation signal converted into digital data by referring to the memory 191, and acquires and outputs the excitation frequency component P(m) of the excitation signal by the function of the Fourier transform unit 22a. The output signal acquisition unit 390 has Fourier transform units 32b and 32c, and can perform the same Fourier transform as in the first embodiment. That is, the output signal acquisition unit 390 acquires the SIN signal converted into digital data by referring to the memory 191, acquires the excitation frequency component S(m) of the SIN signal by the function of the Fourier transform unit 32b, and outputs it. Also, the output signal acquisition unit 390 acquires the COS signal digitized by referring to the memory 191, and acquires and outputs the excitation frequency component C(m) of the COS signal by the function of the Fourier transform unit 32c.

The phase relation acquisition unit 40, the amplitude acquisition unit 50, and the electrical angle acquisition unit 60 have functions similar to those of the first embodiment. However, in this embodiment, these functions are realized by software. When the electrical angle acquisition unit 60 acquires the electrical angle θe, the accuracy acquisition unit 800 acquires and outputs information indicating the deviation between the electrical angle θe thus acquired and the reference.

The accuracy acquisition unit 800 has a function of acquiring the accuracy of the electrical angle acquired by the electrical angle acquisition unit 60 based on the mechanical angle of the rotor. That is, in the data acquisition system 200, the mechanical angle conversion unit 202 acquires the mechanical angle of the rotor based on the output signal of the encoder 15c and uses it as a reference. get.

Accuracy of the electrical angle may be specified by various indexes, and in the present embodiment, mechanical angle error=(electrical angle−(axis multiple angle×mechanical angle))/axis multiple angle is an indicator of accuracy. The accuracy acquisition unit 800 acquires the mechanical angle error based on the mechanical angle obtained from the output signal of the encoder 15 c and the electrical angle θe and the shaft angle multiplier obtained by the electrical angle acquisition unit 60 . In addition, if the shaft angle multiplier is 2 or more, the shaft angle multiplier x mechanical angle may be greater than 360°. Repeat the process of subtracting 360 degrees.

After obtaining the mechanical angle error, the accuracy obtaining unit 800 outputs the mechanical angle error. The output mode may be in various modes, for example, it may be a graph with the mechanical angle on the horizontal axis and the mechanical angle error on the vertical axis, or it may be a statistical value of the mechanical angle error. It is also possible to assume various aspects. Further, the accuracy of the electrical angle may be evaluated based on the mechanical angle of the rotor. Accuracy may be evaluated by a difference or the like, and various configurations can be adopted. Also, the output destination is not limited, and a database (not shown) for recording measurement data, a printer (not shown), etc., other than a display (not shown) may serve as an output destination.

In this embodiment, the parameter setting unit 700 can receive input of parameters based on user input through an input unit such as a keyboard. The parameter setting unit 700 can receive the number of samples N as in the first embodiment, and can cause the Fourier transform units 22a, 32b, and 32c to perform Fourier transform using the received parameters. Therefore, for example, when the excitation frequency f _r of the excitation signal in the excitation signal generator 13 is 10 kHz and the sampling frequency f _s in the analog-to-digital converters 21a, 31b, and 31c is set to 320 kHz, the user can , f _r /f _s being 1/32, it is possible to make m=N×fr/fs an integer by setting N to 32, 64, etc.

Of course, the parameter setting unit 700 may accept the sampling frequency f _s and the excitation frequency f _r to control the sampling frequency for analog-to-digital conversion in the data collection system 200, or the excitation signal generation unit 13 may be able to The frequency may be controllable.

In the present embodiment, the parameter setting unit 700 can further receive input of parameters for controlling the motor 15a, and can control the motor 15a with the parameters. In this sense, the parameter setting section 700 functions as a motor control section. That is, the parameter setting unit 700 can set parameters for operating the motor 15a, such as the rotation speed, and the period and angle for rotating the motor 15a by a certain angle at regular intervals.

When a parameter for operating the motor 15a is input, a control signal corresponding to the parameter is output from the parameter setting section 700 to the motor driver 15b. As a result, the motor driver 15b controls the motor 15a so that the motor 15a is driven by the operation indicated by the parameter.

In the above configuration, when a measurement start trigger is generated by a user's instruction or the like, the parameter setting section 700 functions as a motor control section and outputs a control signal corresponding to the operation parameter of the motor 15a to the motor driver 15b. As a result, the motor driver 15b drives the motor 15a to rotate according to the parameters.

Also, the electrical angle acquisition characteristic measurement system 190 starts taking data into the memory 191 in response to a measurement start trigger. As a result, digital data of the excitation signal and the output signal and data indicating the mechanical angle are recorded in the memory 191 . Thereafter, the electrical angle acquisition characteristic measurement system 190 periodically takes in the data in the FIFO memory 201 so that the FIFO memory 201 does not overflow.

When the digital data string corresponding to the mechanical angles of 0° to 360° is loaded into the memory 191, the parameter setting section 700 outputs a control signal to the motor driver 15b to stop the rotation of the motor 15a. Further, excitation signal acquisition section 290 and output signal acquisition section 390 start Fourier transform processing. Data to be included in the Fourier transform when calculating the electrical angle at the time when the mechanical angle is acquired based on the output signal of the encoder 15c may be specified by various methods. For example, it is possible to employ a configuration in which N sampling numbers of data are collected before and after the point in question and are included in the Fourier transform. It should be noted that samples may be collected as long as N samples are collected in periods before and after the time point.

As described above, when N samples are collected, the Fourier transform units 22a, 32b, and 32c perform Fourier transform, the phase relationship acquisition unit 40 acquires the phase relationship based on the result, and the amplitude is acquired. A unit 50 obtains the amplitude. Based on these results, the electrical angle acquisition section 60 acquires the electrical angle θe, and the accuracy acquisition section 800 acquires the mechanical angle error. Such processing is performed for a plurality of mechanical angles specified by the output signal of the encoder 15c, and a mechanical angle error is obtained for each of the plurality of mechanical angles. According to the above configuration, the mechanical angle error for each mechanical angle is obtained in several seconds. When constructing an electrical angle acquisition characteristic measurement system using a tracking loop type digital angle converter such as the above-mentioned Patent Document 1, it takes time for the measurement data to settle down and the rotor is not equipped with a FIFO memory. It is necessary to repeat the work of measuring while stopped, moving, stopping again, and measuring. For this reason, for example, it takes several minutes after the start of rotation to obtain 72 mechanical angle errors in one revolution. However, in this embodiment, it is not necessary to stop the motor 15a. It becomes possible to evaluate as a characteristic of Therefore, there is a great effect in judging whether the resolver 11 is good or bad in the manufacturing stage.

Various configurations other than the configuration shown in FIG. 14 can be employed for the configuration for acquiring the electrical angle in the electrical angle acquisition characteristic measurement system 190 . For example, the configuration for obtaining the electrical angle may be any one of the configurations of the second to eighth embodiments. Therefore, for example, the phase relationship between the excitation signal and the output signal may be obtained based on the digital data of the excitation signal and the output signal that are not Fourier transformed. Also, for example, a multiplexer may be used when acquiring excitation signals and output signals in the data acquisition system 200 . Furthermore, the rotor may be rotationally driven by power other than the motor 15a. For example, a configuration in which the rotor is rotationally driven by manual operation, air pressure, hydraulic pressure, elastic force such as a spring, or the like may be adopted. Further, the rotation of the motor 15a may be transmitted to the rotor via a gear or the like, or the shaft of the motor 15a may rotate via a gear.

(6) Other embodiments:
The above embodiment is an example for carrying out the present invention, and various other embodiments can be adopted without departing from the gist of the present invention. For example, the electrical angle acquisition system and the electrical angle acquisition characteristic measurement system may include a filter for noise reduction. Filters can be placed in various places. For example, if filtering is performed on a digital data string, the filters are placed between each of the analog-to-digital converters 21a, 31b, 31c and each of the Fourier transformers 22a, 32b, 32c. A configuration in which a digital filter is arranged or the like can be adopted. The digital filter may take various forms, such as FIR (Finite impulse response), IIR (Infinite impulse response), Butterworth low-pass filter, band-pass filter, and the like. Of course, the configuration may be such that the electrical angle θe is acquired, and further other values such as the rotational speed of the rotor are acquired.

Furthermore, the ellipse correction may be performed based on the SIN signal and the COS signal having different maximum amplitude values. That is, in the above embodiment, the amplitude of the SIN signal is Ksin θe and the amplitude of the COS signal is Kcos θe, so the maximum values of the amplitudes match. However, if it becomes necessary to finely adjust the amplification factors of the amplifiers 13b and 13c and the number of turns of the output windings in order to completely match the maximum values of the amplitudes of both signals, preparation may be complicated.

Therefore, measurement may be performed in a state where the maximum values of the amplitudes of the SIN signal and the COS signal do not match. That is, it is assumed that the SIN signal after being amplified by the amplifier 13b is b·sin θe·sin(2πf _r t), and the COS signal after being amplified by the amplifier 13c is a·cos θe·sin(2πf _r t). However, b≠a.

In this case, if a diagram showing changes in the amplitudes of the SIN signal and the COS signal with respect to the electrical angle θe as shown in FIG. 2C is created, the plot of the amplitude values will be an ellipse instead of a circle. FIG. 15 is a diagram showing changes in the amplitudes of the SIN signal and the COS signal depending on the electrical angle θe when a>b. In FIG. 15, the plot of amplitude values is indicated by a two-dot chain line, and the plot result is an ellipse as shown in FIG. On the other hand, when the SIN signal and the COS signal have the same maximum amplitude value, the plot of the amplitude value is circular as indicated by the dashed-dotted line.

Here, if the amplitude value when the amplitude value of the COS signal is x is y when the amplitude values do not match and y′ when the amplitude values match, then y′=(a/b)y. . Therefore, by using this relationship, it is possible to obtain the electrical angle θe when the amplitude values do not match. Specifically, for example, in the first embodiment, the amplitude acquisition unit 50 corrects the amplitude of the excitation frequency component of the SIN signal, which is one of the output signals, by a/b times, or It is possible to employ a configuration in which the amplitude of the excitation frequency component of a certain COS signal is corrected b/a times. That is, the amplitude acquisition unit 50 can employ a configuration for correcting PwrSin to (a/b)PwrSin, a configuration for correcting PwrCos to (b/a)PwrCos, or the like. In the case of the above configuration, correction may be performed once at the stage of obtaining the electrical angle θe, and the amount of calculation can be reduced. Further, when a data string obtained by digitizing the SIN signal is s(n) and a data string obtained by digitizing the COS signal is c(n), s(n) is represented by (a/b)s(n) and a configuration for correcting c(n) as (b/a)c(n). Note that in this configuration, correction is performed for each sampling. For a and b, a configuration obtained by measuring the maximum value of the amplitude in the output signals of the amplifiers 13b and 13c, a configuration set by the parameter setting unit 70, etc. can be adopted, and various configurations can be adopted. is. In the former case, a more accurate value can be obtained by rotating the rotor a plurality of times and measuring the maximum value of the amplitude.

Furthermore, in the electrical angle acquisition system, it is necessary to collect samples of the number of samplings N in order to acquire the electrical angle θe at a certain moment. An error may occur with the current value. Therefore, a configuration for correcting such errors may be employed. For example, the error characteristics can be specified by calculating the period required to collect the sampling number N from the rotor rotation speed, or by calculating the error characteristics with respect to the rotor rotation speed in advance by calculation, statistics, or the like. . Therefore, a configuration may be adopted in which a value obtained by subtracting the error specified based on the characteristic from the electrical angle θe is obtained as the electrical angle θe. It should be noted that the error characteristics can be specified by, for example, a function that indicates the relationship between the error and the rotational speed. In this case, it is possible to adopt a configuration in which the relationship between the rotor rotation speed and the error is set by the parameter setting unit 70, the error is specified according to the rotor rotation speed, and the electrical angle θe is corrected.

Furthermore, the parameter setting units 70 and 700 may be configured to be able to set various parameters other than the sampling frequency f _s , the number of samples N, and the excitation frequency f _r described above. For example, the shaft angle multiplier, connection information between the resolver 11 and the electrical angle acquisition system (the characteristics of FIGS. 2B and 2C may change depending on the connection), the amplitude E of the excitation signal, the center voltage of the amplitude of the excitation signal and the output signal (for example, , which can be used for abnormality detection), amplitudes a and b of the above-mentioned output signals, noise filter characteristics (for example, filtering characteristics can be specified by parameters, etc.), electrical angle output format (serial, parallel, voltage, A B Z, U V W, etc.), SIN signal with respect to the excitation signal, phase shift of COS signal (allows correction of known shift), mechanical angle, electrical angle origin shift (for example, resolver 11 is attached to the device at an arbitrary angle , and the position of mechanical angle 0 degree and electrical angle 0 degree can be adjusted later), deviation of electrical angle θe between N samplings (correction value of error due to rotor rotation speed ) etc. may be input.

The rotation detector may have a configuration of one-phase excitation and two-phase output. , and output signals from two-phase output windings. That is, it is sufficient that the output signal is modulated according to the rotation of the rotor, and the electrical angle can be specified based on the output signal and the excitation signal. The excitation windings, the output windings, and the rotor may take various forms.

The excitation signal acquisition unit may acquire the excitation frequency component of the excitation signal by Fourier transform. In other words, the excitation signal acquisition section only needs to be able to acquire the excitation signal and extract the excitation frequency component, which is the component required to acquire the electrical angle. The excitation signal acquisition section only needs to acquire the excitation frequency component of the excitation signal, and the excitation signal acquired by the excitation signal acquisition section may take various forms.

For example, an analog excitation signal may be input to the excitation signal acquisition section, or a digital excitation signal may be input to the excitation signal acquisition section. In the former case, digital-to-analog conversion is performed in the excitation signal acquisition section. In the latter case, it is sufficient that the excitation signal acquisition unit can acquire the excitation signal as digital data, and the excitation signal as digital data may be a signal generated based on parameters or supplied to the rotation detector. The analog excitation signal may be a digital-to-analog converted signal, and various configurations can be adopted. The excitation signal generation source may be provided in the electrical angle acquisition system, or may be provided outside the electrical angle acquisition system.

The excitation frequency is the frequency of the excitation signal, and various signals vibrating at the excitation frequency can be used as the excitation signal. The excitation signal is typically a signal represented by a trigonometric function such as a sine wave, and has a single frequency component when the excitation signal is generated.

The Fourier transform only needs to be able to convert the excitation signal, which is a signal in time space, into a signal in frequency space, and the conversion should be performed so that the excitation frequency component of the excitation signal can be extracted. Therefore, a digital data string indicating a plurality of frequency components may be generated, and an excitation frequency component may be selected from the digital data string, or data corresponding to the excitation frequency component may be calculated. .

Extraction of excitation frequency components may be performed in various manners. For example, in the Fourier transform, when a frequency component equal to the excitation frequency is obtained, the frequency component is acquired as the excitation frequency component. If the frequency component equal to the excitation frequency is not obtained, the frequency component closest to the excitation frequency or the frequency component within a predetermined range from the excitation frequency is selected from the multiple frequency component data obtained by Fourier transform. may be selected to be considered excitation frequency components. Such characteristics of the Fourier transform also apply to the output signal acquisition section. Therefore, the excitation signal acquisition section and the output signal acquisition section may be realized by the same Fourier transform section. In this case, the excitation signal and the output signal are subjected to Fourier transform in order.

The output signal acquisition unit only needs to be able to acquire the excitation frequency components of the two-phase output signals by Fourier transform. That is, the output signal is modulated according to the rotation of the rotor of the rotation detector. Since the output signal is a signal excited by the excitation signal, even if the amplitude or the like is modulated, the output signal is output as a signal that changes at the same frequency as that of the excitation signal. The excitation signal is the reference for specifying the state of the modulated output signal, and the excitation signal is a signal of the excitation frequency. Therefore, the component required to obtain the electrical angle in the output signal is the excitation frequency component. Therefore, the output signal acquisition unit only needs to be able to acquire the output signal and extract the excitation frequency component, which is the component required to acquire the electrical angle.

The two-phase output signals are signals output from the rotation detector, and it is sufficient if the electrical angle can be obtained based on these two-phase output signals. The form of the output signal acquired by the output signal acquisition section may be various forms. For example, an analog output signal may be input to the output signal acquisition section, or a digital output signal may be input to the output signal acquisition section. In the former case, digital-to-analog conversion is performed in the output signal acquisition section. In the latter case, the output signal is digital-analog converted outside the output signal acquisition unit.

The phase relationship acquisition unit only needs to be able to acquire the phase relationship between the excitation signal and the two-phase output signals based on the excitation signal and the two-phase output signals. That is, the phase relationship between the excitation signal and the two-phase output signals is fixed unless the characteristics of the rotation detector (such as the connection of windings) change. Therefore, if the phase relationship is found, the quadrant of the electrical angle (angle range to which the electrical angle belongs) is specified. The phase relationship acquisition unit only needs to be able to acquire the phase relationship as the information on which the electrical angle is acquired.

Various configurations can be adopted as the configuration for acquiring the phase relationship, and various methods other than the rotation of the coordinate axes as described above can be employed. For example, it is possible to employ a configuration in which the phase relationship between the excitation signal and the SIN signal is obtained by the inner product of the excitation signal and the SIN signal, and the phase relationship between the excitation signal and the COS signal is obtained by the inner product of the excitation signal and the COS signal. More specifically, the inner product of the excitation frequency component P(m) of the excitation signal and S(m), which is the output Fourier signal obtained by Fourier transforming the SIN signal, is calculated, that is, Sr·Pr+Si·Pi. It is possible to employ a configuration in which the phase is the same if the phase is negative, and that the phase is the opposite phase if the phase is negative. In addition, the inner product of the excitation frequency component P(m) of the excitation signal and C(m), which is the output Fourier signal obtained by Fourier transforming the COS signal, is calculated. , and a negative phase can be adopted.

The amplitude acquisition section only needs to be able to acquire the amplitude of the two-phase output signal based on the excitation frequency components of the two-phase output signal. That is, if the characteristics of the rotation detector do not change, the candidates for the electrical angle are identified by the amplitudes of the two-phase output signals. The amplitude obtaining section only needs to be able to obtain the amplitude as information on which such an electrical angle is obtained. Various configurations can be adopted as the configuration for acquiring the amplitude, and the amplitude may be acquired by a method other than the square root of the square of the real part and the imaginary part as described above. For example, a configuration may be adopted in which the real part after the coordinate axis rotation described above is regarded as the amplitude.

The electrical angle acquisition section may acquire the electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals. In other words, the electrical angle acquisition unit only needs to be able to select an angle included in the quadrant of the electrical angle specified based on the phase relationship from the angle candidates specified by the amplitude ratio, and obtain the electrical angle. .

Furthermore, when obtaining the excitation frequency component from the Fourier transform result X(k), it is preferable that k=m and m=N×f _r /f _s is an integer, but N×f _r /f Even if _s is not an integer value, m should be close to N×f _r /f _s . That is, if m is close to N×f _r /f _s , then the Fourier transform result X(m) can be regarded as the excitation frequency component. If there is a difference between m and N×f _r /f _s , the error in the electrical angle θe changes according to the difference. ) is regarded as the excitation frequency component.

The functions of each means described in the claims are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. Moreover, the functions of these means are not limited to those realized by physically independent hardware resources. Furthermore, the present invention is established as a method, a computer program, and a computer program recording medium. Of course, the recording medium for the computer program may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium that will be developed in the future.

DESCRIPTION OF SYMBOLS 10... Electrical angle acquisition system, 11... Resolver, 12... Amplifier, 13... Excitation signal generator, 13a... Amplifier, 13b... Amplifier, 13c... Amplifier, 15a... Motor, 15b... Motor driver, 15c... Encoder, 20... Excitation Signal acquisition unit 21a...Analog-digital converter 22a...Fourier transform unit 30...Output signal acquisition unit 31b...Analog-digital converter 31c...Analog-digital converter 32b...Fourier transform unit 32c...Fourier transform unit 40... Phase relationship acquisition unit 50... Amplitude acquisition unit 60... Electrical angle acquisition unit 70... Parameter setting unit

Claims (14)

An electrical angle acquisition system for acquiring an electrical angle of a rotation detector based on an excitation signal and an output signal of a one-phase excitation two-phase output rotation detector,
a parameter setting unit that receives at least one input or specification of the sampling frequency f _s , the number of samples N, and the excitation frequency f _r by the user and sets the received value;
converting the analog excitation signal into digital data by sampling N times at a sampling frequency f _s , obtaining an excitation Fourier signal by performing a Fourier transform;

From the excitation Fourier signal, X(m ₎ in equation (1), where m is an integer value equal to or closest to N× _{f r} / _fs , where N×f _r /f _s is not an integer value) and f _r is an excitation frequency) and acquires it as an excitation frequency component of the excitation signal;
The two-phase analog output signal is sampled N times at a sampling frequency f _s to be converted into digital data, Fourier-transformed to obtain an output Fourier signal, and from the output Fourier signal, X(m ) and acquires it as an excitation frequency component of the output signal;
a phase relationship acquisition unit that acquires a phase relationship between the excitation signal and the two-phase output signals based on the excitation frequency components of the excitation signal and the excitation frequency components of the two-phase output signals;
an amplitude acquisition unit configured to acquire amplitudes of the two-phase output signals based on excitation frequency components of the two-phase output signals;
an electrical angle acquisition unit configured to acquire an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
An electrical angle acquisition system comprising: The timing at which the excitation signal acquisition unit samples the excitation signal and the timing at which the output signal acquisition unit samples the two-phase output signals are the same.
The electrical angle acquisition system according to claim 1. The timing at which the excitation signal acquisition unit samples the excitation signal and the timing at which the output signal acquisition unit samples the two-phase output signals are different timings,
The excitation signal obtaining section and the output signal obtaining section obtain an excitation frequency component of the excitation signal after Fourier transform due to a difference between the timing of sampling the excitation signal and the timing of sampling the two-phase output signals. and obtaining the excitation frequency component of the excitation signal and the excitation frequency component of the output signal by compensating for the phase shift occurring in the excitation frequency component of the output signal.
The electrical angle acquisition system according to claim 1 or 2. An electrical angle acquiring method for acquiring an electrical angle of a rotation detector based on an excitation signal and an output signal of a one-phase excitation two-phase output rotation detector, comprising:
a parameter setting step of receiving input or designation of at least one of the sampling frequency f _s , the number of samples N, and the excitation frequency f _r by the user , and setting the received value;
converting the analog excitation signal into digital data by sampling N times at a sampling frequency f _s , obtaining an excitation Fourier signal by performing a Fourier transform;

From the excitation Fourier signal, X(m ₎ in equation (1), where m is an integer value equal to or closest to N× _{f r} / _fs , where N×f _r /f _s is not an integer value) and f _r is an excitation frequency), and an excitation signal acquisition step of selecting data corresponding to and acquiring it as an excitation frequency component of the excitation signal;
The two-phase analog output signal is sampled N times at a sampling frequency f _s to be converted into digital data, Fourier-transformed to obtain an output Fourier signal, and from the output Fourier signal, X(m ) and acquiring it as the excitation frequency component of the output signal;
a phase relationship acquiring step of acquiring a phase relationship between the excitation signal and the two-phase output signals based on the excitation frequency components of the excitation signal and the excitation frequency components of the two-phase output signals;
an amplitude acquisition step of acquiring amplitudes of the two-phase output signals based on excitation frequency components of the two-phase output signals;
an electrical angle acquiring step of acquiring an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
including electrical angle acquisition method. a computer that acquires the electrical angle of the rotation detector based on the excitation signal and the output signal of the rotation detector with 1-phase excitation and 2-phase output;
a parameter setting unit that receives at least one input or designation of the sampling frequency f _s , the number of samples N, and the excitation frequency f _r by the user and sets the received value;
converting the analog excitation signal into digital data by sampling N times at a sampling frequency f _s , obtaining an excitation Fourier signal by performing a Fourier transform;

From the excitation Fourier signal, X(m ₎ in equation (1), where m is an integer value equal to or closest to N× _{f r} / _fs , where N×f _r /f _s is not an integer value) and f _r is an excitation frequency) and acquires it as an excitation frequency component of the excitation signal;
The two-phase analog output signal is sampled N times at a sampling frequency f _s to be converted into digital data, Fourier-transformed to obtain an output Fourier signal, and from the output Fourier signal, X(m ) and acquires it as the excitation frequency component of the output signal,
a phase relationship acquisition unit configured to acquire a phase relationship between the excitation signal and the two-phase output signal based on the excitation frequency component of the excitation signal and the excitation frequency component of the two-phase output signal;
an amplitude acquisition unit that acquires the amplitude of the two-phase output signal based on the excitation frequency component of the two-phase output signal;
an electrical angle acquisition unit configured to acquire an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
An electrical angle acquisition program that functions as An electrical angle acquisition system for acquiring an electrical angle of a rotation detector based on an excitation signal and an output signal of a one-phase excitation two-phase output rotation detector,
a parameter setting unit that receives at least one input or specification of the sampling frequency f _s , the number of samples N, and the excitation frequency f _r by the user and sets the received value;
converting the two-phase analog output signal into digital data by sampling N times at a sampling frequency f _s and performing a Fourier transform to obtain an output Fourier signal;

From the output Fourier signal, X(m ₎ in equation (1), where _m is an integer value equal to or closest to N*f _r /f _s , where N*f _r /f _s is not an integer value) and f _r is an excitation frequency) and acquires it as an excitation frequency component of the output signal;
a phase relationship acquisition unit that acquires a phase relationship between the excitation signal and the two-phase output signals based on the excitation signal and the two-phase output signals;
an amplitude acquisition unit configured to acquire amplitudes of the two-phase output signals based on excitation frequency components of the two-phase output signals;
an electrical angle acquisition unit configured to acquire an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
An electrical angle acquisition system comprising: An electrical angle acquiring method for acquiring an electrical angle of a rotation detector based on an excitation signal and an output signal of a one-phase excitation two-phase output rotation detector, comprising:
a parameter setting step of receiving input or designation of at least one of the sampling frequency f _s , the number of samples N, and the excitation frequency f _r by the user , and setting the received value;
converting the two-phase analog output signal into digital data by sampling N times at a sampling frequency f _s and performing a Fourier transform to obtain an output Fourier signal;

From the output Fourier signal, X(m ₎ in equation (1), where _m is an integer value equal to or closest to N*f _r /f _s , where N*f _r /f _s is not an integer value) and f _r is an excitation frequency) and acquiring it as an excitation frequency component of the output signal;
a phase relationship acquiring step of acquiring a phase relationship between the excitation signal and the two-phase output signals based on the excitation signal and the two-phase output signals;
an amplitude acquisition step of acquiring amplitudes of the two-phase output signals based on excitation frequency components of the two-phase output signals;
an electrical angle acquiring step of acquiring an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
including electrical angle acquisition method. a computer that acquires the electrical angle of the rotation detector based on the excitation signal and the output signal of the rotation detector with 1-phase excitation and 2-phase output;
a parameter setting unit that receives at least one input or specification of the sampling frequency f _s , the number of samples N, and the excitation frequency f _r by the user and sets the received value;
converting the two-phase analog output signal into digital data by sampling N times at a sampling frequency f _s and performing a Fourier transform to obtain an output Fourier signal;

From the output Fourier signal, X(m ₎ in equation (1), where _m is an integer value equal to or closest to N*f _r /f _s , where N*f _r /f _s is not an integer value) and f _r is an excitation frequency) and acquires it as an excitation frequency component of the output signal;
a phase relationship acquisition unit that acquires a phase relationship between the excitation signal and the two-phase output signals based on the excitation signal and the two-phase output signals;
an amplitude acquisition unit that acquires the amplitude of the two-phase output signal based on the excitation frequency component of the two-phase output signal;
an electrical angle acquisition unit configured to acquire an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
An electrical angle acquisition program that functions as An electrical angle acquisition characteristic measurement system for measuring electrical angle acquisition characteristics of a rotation detector based on an excitation signal and an output signal of a rotation detector with one-phase excitation and two-phase output,
a motor control unit that controls a motor having a shaft or a part that rotates in conjunction with the shaft attached to the rotor of the rotation detector;
memory;
an excitation signal acquisition unit that acquires an excitation frequency component of the excitation signal stored in the memory by Fourier transform;
an output signal acquisition unit that acquires excitation frequency components of the two-phase output signals stored in the memory by Fourier transform;
a phase relationship acquisition unit that acquires a phase relationship between the excitation signal and the two-phase output signals based on the excitation frequency components of the excitation signal and the excitation frequency components of the two-phase output signals;
an amplitude acquisition unit configured to acquire amplitudes of the two-phase output signals based on excitation frequency components of the two-phase output signals;
an electrical angle acquisition unit configured to acquire an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
Accuracy acquisition for acquiring the accuracy of the electrical angle of the rotation detector based on the mechanical angle of the rotor acquired based on the output of an encoder that outputs a signal corresponding to the rotation angle of the rotor and stored in the memory. and
taking in the excitation signal, the two-phase output signal, and the mechanical angle of the rotor to the memory without stopping the rotation of the motor;
Electrical angle acquisition characteristic measurement system. An electrical angle acquisition characteristic measuring method for measuring the electrical angle acquisition characteristic of a rotation detector based on an excitation signal and an output signal of a one-phase excitation two-phase output rotation detector, comprising:
a motor control step of controlling a motor having a shaft or a part that rotates in conjunction with the shaft attached to the rotor of the rotation detector;
an excitation signal acquisition step of acquiring the excitation frequency component of the excitation signal stored in the memory by Fourier transform;
an output signal acquisition step of acquiring excitation frequency components of the two-phase output signals stored in the memory by Fourier transform;
a phase relationship acquiring step of acquiring a phase relationship between the excitation signal and the two-phase output signals based on the excitation frequency components of the excitation signal and the excitation frequency components of the two-phase output signals;
an amplitude acquisition step of acquiring amplitudes of the two-phase output signals based on excitation frequency components of the two-phase output signals;
an electrical angle acquiring step of acquiring an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
Accuracy acquisition for acquiring the accuracy of the electrical angle of the rotation detector based on the mechanical angle of the rotor acquired based on the output of an encoder that outputs a signal corresponding to the rotation angle of the rotor and stored in the memory. and
taking in the excitation signal, the two-phase output signal, and the mechanical angle of the rotor to the memory without stopping the rotation of the motor;
Electrical angle acquisition characteristic measurement method. A computer for measuring the characteristics of obtaining the electrical angle of the rotation detector based on the excitation signal and the output signal of the rotation detector with 1-phase excitation and 2-phase output,
a motor control unit for controlling a motor having a shaft or a part that rotates in conjunction with the shaft attached to the rotor of the rotation detector;
an excitation signal acquisition unit that acquires the excitation frequency component of the excitation signal stored in the memory by Fourier transform;
an output signal acquisition unit that acquires excitation frequency components of the two-phase output signals stored in the memory by Fourier transform;
a phase relationship acquisition unit configured to acquire a phase relationship between the excitation signal and the two-phase output signal based on the excitation frequency component of the excitation signal and the excitation frequency component of the two-phase output signal;
an amplitude acquisition unit that acquires the amplitude of the two-phase output signal based on the excitation frequency component of the two-phase output signal;
an electrical angle acquisition unit configured to acquire an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
Accuracy acquisition for acquiring the accuracy of the electrical angle of the rotation detector based on the mechanical angle of the rotor acquired based on the output of an encoder that outputs a signal corresponding to the rotation angle of the rotor and stored in the memory. part,
function as
taking in the excitation signal, the two-phase output signal, and the mechanical angle of the rotor to the memory without stopping the rotation of the motor;
Electrical angle acquisition characteristic measurement program. An electrical angle acquisition characteristic measurement system for measuring electrical angle acquisition characteristics of a rotation detector based on an excitation signal and an output signal of a rotation detector with one-phase excitation and two-phase output,
a motor control unit that controls a motor having a shaft or a part that rotates in conjunction with the shaft attached to the rotor of the rotation detector;
memory;
an output signal acquisition unit that acquires excitation frequency components of the two-phase output signals stored in the memory by Fourier transform;
a phase relationship acquisition unit that acquires a phase relationship between the excitation signal and the two-phase output signals based on the excitation signal and the two-phase output signals;
an amplitude acquisition unit configured to acquire amplitudes of the two-phase output signals based on excitation frequency components of the two-phase output signals;
an electrical angle acquisition unit configured to acquire an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
Accuracy acquisition for acquiring the accuracy of the electrical angle of the rotation detector based on the mechanical angle of the rotor acquired based on the output of an encoder that outputs a signal corresponding to the rotation angle of the rotor and stored in the memory. Department and
, and
taking in the two-phase output signals and the mechanical angle of the rotor into the memory is performed without stopping rotation of the motor;
Electrical angle acquisition characteristic measurement system. An electrical angle acquisition characteristic measuring method for measuring the electrical angle acquisition characteristic of a rotation detector based on an excitation signal and an output signal of a one-phase excitation two-phase output rotation detector, comprising:
a motor control step of controlling a motor having a shaft or a part that rotates in conjunction with the shaft attached to the rotor of the rotation detector;
an output signal acquiring step of acquiring the excitation frequency components of the two-phase output signals stored in the memory by Fourier transform;
a phase relationship acquiring step of acquiring a phase relationship between the excitation signal and the two-phase output signals based on the excitation signal and the two-phase output signals;
an amplitude acquisition step of acquiring amplitudes of the two-phase output signals based on excitation frequency components of the two-phase output signals;
an electrical angle acquiring step of acquiring an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
Accuracy acquisition for acquiring the accuracy of the electrical angle of the rotation detector based on the mechanical angle of the rotor acquired based on the output of an encoder that outputs a signal corresponding to the rotation angle of the rotor and stored in the memory. process and
including
taking in the two-phase output signals and the mechanical angle of the rotor into the memory is performed without stopping rotation of the motor;
Electrical angle acquisition characteristic measurement method. A computer for measuring the characteristics of obtaining the electrical angle of the rotation detector based on the excitation signal and the output signal of the rotation detector with 1-phase excitation and 2-phase output,
a motor control unit for controlling a motor having a shaft or a part that rotates in conjunction with the shaft attached to the rotor of the rotation detector;
an output signal acquisition unit that acquires the excitation frequency components of the two-phase output signals stored in the memory by Fourier transform;
a phase relationship acquisition unit that acquires a phase relationship between the excitation signal and the two-phase output signals based on the excitation signal and the two-phase output signals;
an amplitude acquisition unit that acquires the amplitude of the two-phase output signal based on the excitation frequency component of the two-phase output signal;
an electrical angle acquisition unit configured to acquire an electrical angle of the rotation detector based on the phase relationship and the amplitudes of the two-phase output signals;
Accuracy acquisition for acquiring the accuracy of the electrical angle of the rotation detector based on the mechanical angle of the rotor acquired based on the output of an encoder that outputs a signal corresponding to the rotation angle of the rotor and stored in the memory. part,
function as
taking in the two-phase output signals and the mechanical angle of the rotor into the memory is performed without stopping rotation of the motor;
Electrical angle acquisition characteristic measurement program.

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