JP2003344106A - Rotation angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rotation angle detector capable of detecting the rotation angle at a high accuracy even when using a resolver in an environment involving leaking fluxes. <P>SOLUTION: The displacement detector comprises signal generating means 10, 11 for outputting signals synchronous with an exciting period of a resolver having a one-phase excited two-phase output, a first transforming means for Fourier-transforming each output of the resolver in a one-period section of the exciting period, a second transforming means for Fourier-transforming each output of the resolver in a one-period section with a 1/2-period shift from the exciting period of the first transforming means, and an operational means for adding or subtracting an output signal of the first transforming means to or from that of the second transforming means, respectively. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detecting device using a resolver capable of accurately detecting a rotation angle even when there is a leakage magnetic flux from a rotary electric machine or the like.

[0002]

2. Description of the Related Art It is known that a resolver is used as an angle detector to detect the rotational position of a rotating body, and the output of the resolver is Fourier-transformed to extract a specific frequency component to calculate an angle. For example, Japanese Patent Laid-Open No. 11-1
In Japanese Patent No. 18520, in a digital angle conversion method in which a two-phase resolver output having a 90-degree phase difference of a one-phase excitation two-phase output is converted into a digital angle, Fourier output is performed after A / D conversion of the resolver output. There is disclosed a technique of a digital angle conversion method in which a phase of a constant frequency component included in an output waveform is converted to calculate a digital angle.

Further, Japanese Patent Laid-Open No. 4-16712 discloses that
In a method for detecting a rotation angle using a resolver having one rotor winding and two stator windings, the output of the rotor winding is A / D converted and then Fourier-transformed to be included in an output waveform. A technique of calculating the rotation angle by calculating the phase of a constant frequency component is disclosed. Both technologies use Fourier transform to greatly simplify the hardware required to obtain a digital angle from the resolver output.By performing Fourier transform, DC offset components and harmonic components are removed. , Active filters and LC
It eliminates the use of filters.

[0004]

However, when the resolver is used in an atmosphere in which leakage magnetic flux from the rotating electric machine exists, such as when the resolver is used for angle detection of the rotating electric machine, the resolver changes due to the change in the leakage magnetic flux. Low-order noise with a frequency lower than the excitation frequency of is superimposed on the output waveform,
This low-order noise cannot be removed by Fourier transform. For example, when the resolver 3 is attached to the rotary shaft 2 of the claw pole type synchronous machine 1 as shown in FIG. 5, the field coil 4 is provided concentrically with the rotary shaft 2, and therefore the axis of the synchronous machine 1 is reduced. A magnetic flux as indicated by an arrow is generated in the direction, and this magnetic flux induces a voltage synchronized with the rotation speed of the synchronous machine 1 in the output coil of the resolver 3 as the rotor 5 rotates.

An ideal output signal in a resolver with one-phase excitation and two-phase output is: SIN signal = k sin θ · sin ωt COS signal = k cos θ · sin ωt. However, various noises are added to this signal, and The noise due to the leakage magnetic flux is a noise component having a frequency lower than the excitation frequency f = 2πω of the resolver. Therefore, the output signal of the resolver is as follows: SIN signal = ksin θ · sin ωt + a + bt + ct
² + ··· COS signal = kcos θ · sin ωt + a + bt + ct
It becomes a value including noise such as ² +.

When this signal is subjected to Fourier transform in the section of one period of excitation of the resolver, ignoring the second-order component or more of noise, ksin θ-b (2π / ω ² ) cosωt0 becomes a value including the noise component, When the predicted movement data and the absolute position data include an error, the error is accumulated in the obtained rotational position data, and the angle detection accuracy deteriorates.

The present invention has been made in order to solve such a problem, and it is possible to detect a rotation angle with high accuracy even when a resolver is used in an atmosphere in which leakage magnetic flux exists. It is intended to obtain a rotation angle detection device having high noise resistance.

[0008]

SUMMARY OF THE INVENTION A rotation angle detecting device according to the present invention includes a signal generating means for outputting a signal synchronized with an excitation cycle of a resolver having a one-phase excitation and two-phase output, and an excitation cycle for each output of the resolver. Fourier transform is performed by shifting the output of the resolver by ½ cycle of the excitation cycle with respect to the first conversion means for performing Fourier transform for one cycle section of the resolver and the first conversion means for each cycle of the excitation cycle. The second conversion means and the calculation means for adding or subtracting the output signal of the first conversion means and the output signal of the second conversion means are provided.

Further, the first conversion means performs the Fourier transform by detecting the rising edge of the signal synchronized with the excitation period, and the falling edge is detected by the second converting means. Is. Furthermore, the rotation angle calculated from the combined value of the output signal of the first conversion means and the output signal of the second conversion means is the latest rotation angle,
The rotation angle 1/2 cycle before the excitation cycle is detected, and the detection time delay of the latest rotation angle is corrected by the rotation angle 1/2 cycle before.

Furthermore, the rotation angle calculated from the combined value of the output signal of the first conversion means and the output signal of the second conversion means is the latest rotation angle and 1/2 cycle before the excitation cycle. The rotation angle is detected, and the change in the rotation angle after the latest rotation angle is detected by multiplying the difference between the latest rotation angle and the rotation angle 1/2 cycle before by the elapsed time after the latest rotation angle is detected. It is an estimate.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a block diagram showing a configuration of a rotation angle detection device according to a first embodiment of the present invention, and FIGS. 2 to 4 are characteristic diagrams for explaining the effect. FIG. 2 shows that the resolver output has no noise superimposed. If
FIG. 3 is a characteristic example when high-order noise is superimposed, and FIG. 4 is a characteristic example when high-order noise and low-order noise are superimposed. In addition, the block diagram of FIG. 1 includes four series of processing circuits, and the same portions are denoted by reference numerals such as 15a, 15b, and 15c, and the operation description will be performed on behalf of one series of operations. To do.

In FIG. 1, 10 is a signal generator for generating sin ωt synchronized with the excitation period of the resolver, 11 is a signal generator for similarly generating cos ωt, and SIN signal is the SIN signal or COS signal of the resolver output. There is a COS signal at the resolver output. 12a to 12d are multipliers, 13a to 13d are integrators, 14a to 14d are rising and falling detectors, 15a to 15d, 16a to.
Reference numerals 16d, 17a to 17d and 18a to 18d denote sample and hold circuits, 19a to 19d and 20a to 20d denote subtractors, and 21a to 21d denote adders. Also, 22 and 23
Is a calculator for calculating the square root of the sum of squares by inputting the signals U1 and U2, 24 is an angle calculator for calculating an angle from SINθ and COSθ, 25 is a zero-cross detector, 26 and 27 are sample and hold circuits, and 28 is Subtractor, 29 is an adder,
Reference numeral 30 is a multiplier, and 31 is a counter that is reset by the zero crossing of sin ωt of the signal generator 10.

In the rotation angle detecting device having such a structure, the SIN signal which is the output signal of the resolver and the CO
The S signal is input to each of the multipliers 12a to 12d, and sin ωt and cos ω generated by the signal generators 10 and 11 are input.
Each is multiplied by t and input to the integrators 13a to 13d. The outputs of the signal generators 10 and 11 are also input to the rising and falling detectors 14a to 14d,
The rising and falling detectors 14a to 14d detect the rising and falling of each signal and give them to the sample and hold circuits 15a to 18d as sample and hold signals. The device operates as follows by this signal, but the operation will be described below by taking the Fourier sine transform part by the SIN signal of the resolver and sinωt of the signal generator 10 as an example.

Resolver S multiplied by the multiplier 12a
The IN signal and the sinωt signal of the signal generator 10 are integrated in time by the integrator 13a. The rising / falling detector 14a detects the zero-crossing rising of the sinωt signal from the signal generator 10 and detects the sample-hold circuit 1
A signal is given to 5a, and the integrated value of the integrator 13a at that time is held in the sample hold circuit 15a. At this time, since the sin ωt signal from the signal generator 10 uses a signal synchronized with the excitation cycle of the resolver, an accurate conversion cycle can be obtained.

Subsequently, after t = π / ω, the rising / falling detector 14a detects the zero-crossing falling of the sinωt signal, and this falling signal is given to the sample / hold circuit 17a and the sample / hold circuit 17a.
Holds the integrated value at that time. Furthermore, t =
After π / ω, a zero-cross rising signal of the sinωt signal is output, and the integrated value held in the sample hold circuit 15a is transferred to the sample hold circuit 16a and held by the rising signal, and the sample hold The circuit 15a holds the new integrated value at that time.

Further, after t = π / ω, the zero crossing falling signal of the sinωt signal is output, the integrated value held in the sample hold circuit 17a is transferred to and held in the sample hold circuit 18a, and at the same time, the sample hold operation is performed. The circuit 17a holds the new integrated value at that time. Then, the new integrated value held in the sample hold circuit 15a and the sample hold circuit 16a
Is subtracted by the subtractor 19a, and the new integrated value held in the sample hold circuit 17a and the integrated value transferred in the sample hold circuit 18a are subtracted by the subtractor 20a. Each subtracted value is an adder 21a
Will be added at.

Here, the sample-hold circuit 15a, the sample-hold circuit 16a, and the subtractor 19a constitute the first conversion means of the Fourier transform, and the sample-hold circuit 17a, the sample-hold circuit 18a, and the subtractor 20a. Represents the second transform means of the Fourier transform. Therefore, the rotation angle detection device of FIG. 1 has four sets of the first conversion means and the second conversion means.

The output of the first conversion means (subtractor 1
The subtraction value by 9a) is Ss1 of the Fourier sine conversion result of the SIN signal x sinωt, and the output of the second conversion means (the subtraction value by the subtractor 20a) is the SIN signal x sinωt.
The result is the Fourier sine transformation result of Ss2. Also, Ss2
Indicates that the conversion section is delayed by π in the excitation period with respect to Ss1. The Ss1 and Ss2 are resolver signals S
The SINωt component of the IN signal has the same sign, but SIN
Since the time primary component noise (low frequency noise) on the signal has the opposite sign, Ss1 + Ss2 added by the adder 21a cancels the low frequency noise of the SIN signal and only the SINωt component of the SIN signal. Becomes If the sign of the SINωt component is opposite and the sign of the noise component is the same, a subtracter is used instead of the adder 21a.

As mentioned in the above description of the prior art,
The DC offset component and the harmonic noise component are removed by performing the Fourier transform, but by the above processing, the low frequency component noise that cannot be removed only by the Fourier transform is also removed and output from the resolver. No noise from SI signal with noise
The component of Nωt can be extracted. The Fourier sine transform part using the SIN signal of the resolver and the sinωt signal of the signal generator 10 has been described above. The Fourier transform using the SIN signal and the cosωt signal of the signal generator 11,
Fourier transform by COS signal and sinωt signal of signal generator 10, COS signal and cosω of signal generator 11
The Fourier transform using the t signal is also the same, and the description thereof will be duplicated and therefore omitted.

The signal obtained by the Fourier sine transform and the Fourier cosine transform in this way is a signal obtained by removing the DC offset component, the high-order harmonic noise component, and the low-frequency noise component, and is the SIN signal. Signal generator 10 s
The conversion result based on the inωt signal is U1, and the conversion result based on the SIN signal and the cosωt signal from the signal generator 11 is input to U2, which is (U1 ² + U2 ² ).
^If the square root of the sum of squares is calculated as ^1/2 , the amplitude of the signal kSINθ in which the noise component of the SIN signal is eliminated can be obtained. The sign in this case may be determined by the sign of the Fourier sine transform or the sign of the Fourier cosine transform. In the case of the COS signal, kCOSθ can be similarly calculated.

S after noise elimination obtained as described above
By inputting the IN signal and the COS signal to the angle calculator 24, the rotation angle θ of the resolver can be calculated by θ = arctan (SINθ / COSθ).

The rotation angle θ of the resolver thus obtained requires 1.5 times as long as the resolver excitation period for calculation. That is, when the sin ωt signal and the cos ωt signal are obtained by using the excitation output signal of the resolver for the signals from the signal generators 10 and 11, the zero cross is used four times, and therefore the first Resolver excitation period of 1.5 from rising to the last falling
Need a cycle. When the change of the rotation angle of the resolver is slow, this detection delay is not a problem, but when the change of the rotation angle is relatively fast, 1/2 of the time for converting the resolver signal into an angle, that is, t = (1.5 The detection time is delayed during / 2) × (2π / ω), and the past value is detected.

The present angle can be accurately estimated by correcting this detection delay as follows.
Since the angle is converted every zero cross, that is, every half cycle of the resolver excitation cycle, when the angle data obtained by this conversion is θ1 and the angle data obtained before the excitation half cycle is θ2, The angle θt can be estimated by calculating θt = θ1 + (θ1−θ2) = 2θ1−θ2. In this calculation, a zero-cross detector 25 that outputs a signal every excitation half cycle, sample hold circuits 26 and 27 that perform a holding operation by this signal, and both held data are subtracted to obtain θ1-
This is performed by a subtractor 28 that calculates θ2 and an adder 29 that adds θ1 to this, and the output of the adder 29 becomes the angle θt with the time delay corrected.

Further, after the angle conversion is performed, the next angle conversion is performed after the half cycle of the excitation, but the angle between the data can be estimated as follows. That is, when the current angle to be estimated is θt0 and the time after the calculation of θ1 is t0, the estimated calculation can be performed as θt0 = θ1 + (θ1-θ2) × (ω / π) × t0. Note that this subtraction is performed by the subtractor 28 (θ1-θ2).
Is a multiplier 30 that multiplies by t0, and a counter 31 that gives this t0.

In the above description, the rotation angle θ is defined as arctan.
Although calculated as (SIN θ / COS θ), the rotation angle θ can also be calculated by digital tracking.
Although the current angle was estimated using the angle data deviated by the excitation half cycle, SINθ and COSθ were estimated using the SIN signal deviated by the excitation half cycle and the COS signal deviated by the excitation half cycle, and the estimated SINθ and COSθ The angle can also be calculated using and. Further, the above calculation can be performed by an analog circuit, and it is also possible to convert an analog signal into a digital signal and perform digital calculation.

The results of signal processing performed by the rotation angle detecting device configured as described above are the characteristic diagrams shown in FIGS. 2 to 4. In each case, (a) is the resolver output waveform, and (b) is the same.
Is a waveform of only Fourier transform, and (c) is a waveform after signal processing by the rotation angle detecting device of the present invention. In FIG. 2, the output waveform of the resolver in (a) has no noise, and as a matter of course, neither (b) nor (c) has noise. FIG. 3 shows the output waveform of the resolver shown in FIG. 3A, in which high-order noise is superimposed. Since this high-order noise is canceled by Fourier transform, noise is eliminated in the waveform shown in FIG. There is no noise in the waveform of. Fig. 4 shows the output waveform of the resolver in (a) with high-order noise and low-order noise. This low-order noise does not disappear even if Fourier transform is performed as in (b) in the figure, and the angle Although the detection is adversely affected, if the signal processing by the rotation angle detection device of the present invention is performed, noise can be erased to a level having no influence as shown in FIG.

As described above, according to the rotation angle detecting apparatus of the present invention, the resolver is used in an atmosphere where there is a leakage magnetic flux, such as by providing the resolver coaxially with the rotating electric machine, and the leakage flux is used as the output of the resolver. This noise can be eliminated even when low-order noise is generated, and the rotation angle can be detected accurately without selecting the electromagnetic atmosphere, and the detection delay of the rotation angle can be corrected accurately. It is possible to do.

[0028]

As described above, in the rotation angle detecting device of the present invention, according to the invention of claim 1, a signal synchronized with the excitation cycle of the resolver having a one-phase excitation and two-phase output is output. Signal generating means, first converting means for Fourier-transforming each output of the resolver with respect to one period section of the excitation cycle, and the first converting means are ½ of the excitation cycle.
Since the second conversion means for performing Fourier transform in the same manner by shifting the cycle, and the operation means for adding or subtracting the output signal of the first conversion means and the output signal of the second conversion means are provided, It is possible to remove noise components with a frequency lower than the excitation frequency, and the rotation angle can be detected with high accuracy even when used to detect the rotation angle of a rotating electrical machine with a large axial magnetic flux leakage, such as a claw pole type synchronous machine. It is possible to obtain a rotation angle detection device that can do this.

According to the second aspect of the invention, the first transforming means performs the Fourier transform by detecting the rising edge of the signal synchronized with the excitation period, and the falling edge is detected by the second transforming operation. Since the Fourier transform is performed by the means, an accurate conversion cycle can be obtained when performing the Fourier transform, and the detection accuracy of the rotation angle can be improved.

Further, according to the invention described in claim 3,
As the rotation angle calculated from the combined value of the output signal of the first conversion means and the output signal of the second conversion means, the latest rotation angle and the rotation angle ½ cycle before the excitation cycle are detected. ,
Since the latest detection time delay of the rotation angle is corrected by the rotation angle of 1/2 cycle before, it is possible to accurately correct the delay of the rotation angle detection time required for the Fourier transform, and with high accuracy. The rotation angle can be detected.

Further, according to the invention described in claim 4, the rotation angle calculated from the combined value of the output signal of the first conversion means and the output signal of the second conversion means is the latest rotation angle. And the rotation angle 1/2 cycle before the excitation cycle are detected, and the difference between the latest rotation angle and the rotation angle 1/2 cycle before is multiplied by the elapsed time after the latest rotation angle detection, Since the change in the rotation angle after the latest rotation angle detection is estimated, in addition to the effect of claim 3, data interpolation can be performed during data detection, and the rotation angle can be detected with high accuracy. is there.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a rotation angle detection device according to a first embodiment of the present invention.

FIG. 2 is an example of a characteristic diagram for explaining the effect of the rotation angle detection device according to the first embodiment of the present invention.

FIG. 3 is an example of a characteristic diagram for explaining the effect of the rotation angle detection device according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram example for explaining effects of the rotation angle detection device according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram illustrating a problem of a conventional rotation angle detection device.

[Explanation of symbols]

10, 11 Signal generator, 12a-12d, 30 Multiplier, 13a-13d Integrator, 14a-14d Rise / fall detector, 15a-18d, 26, 27
Sample hold circuit, 19a to 20d, 28 subtractor, 21a to 21d, 29 adder, 22, 23 calculator, 24 angle calculator, 25 zero cross detector, 31
counter.

Claims (4)

[Claims] 1. A signal generating means for outputting a signal synchronized with an excitation cycle of a resolver having a one-phase excitation two-phase output, and a first Fourier transform of each output of the resolver with respect to one cycle section of the excitation cycle. Conversion means, second conversion means for performing Fourier transform by shifting each output of the resolver with respect to one period section of the excitation cycle by ½ cycle of the excitation cycle with respect to the first conversion means, the first conversion means A rotation angle detecting device comprising a calculating means for adding or subtracting an output signal of the converting means and an output signal of the second converting means. 2. A rising edge of a signal synchronized with the excitation cycle is detected to perform a Fourier transform by the first converting means, and a falling edge is detected to perform a Fourier transform by the second converting means. The rotation angle detector according to claim 1. 3. The rotation angle calculated from the combined value of the output signal of the first conversion means and the output signal of the second conversion means is the latest rotation angle and 1/2 cycle of the excitation cycle. The previous rotation angle is detected, and the detection time delay of the latest rotation angle is corrected by the rotation angle before the 1/2 cycle, The rotation angle according to claim 1 or 2, Detection device. 4. The rotation angle calculated from the combined value of the output signal of the first conversion means and the output signal of the second conversion means is the latest rotation angle and 1/2 cycle of the excitation cycle. The previous rotation angle is detected, and the difference between the latest rotation angle and the rotation angle of the 1/2 cycle before is multiplied by the elapsed time after the latest rotation angle is detected to detect the latest rotation angle. The rotation angle detecting device according to any one of claims 1 to 3, wherein a change in the rotation angle is estimated.