JP5097922B2 - Method for synchronous detection of amplitude modulation signal and rotation signal processor - Google Patents

Description

  The present invention provides an amplitude modulation signal in a signal processing process for obtaining an angle output φ from first and second amplitude modulation signals sin θ · sin (ωt−α) and cos θ · sin (ωt−α) output from a rotation detector. An amplitude modulation signal synchronous detection method and a rotation signal processor for performing synchronous detection of f (θ) · sin (ωt−α), in particular, the first and second amplitude modulation signals sinθ · sin (ωt−α) ), Cos θ · sin (ωt−α) extracted from the carrier phase component ωt−α as an excitation phase reference, and synchronous detection of the amplitude modulation signal f (θ) · sin (ωt−α) is performed, thereby achieving synchronous detection. The present invention relates to a novel improvement for enabling the influence of the phase difference α of the signal to be suppressed to a small level and improving the accuracy of synchronous detection.

  As this type of rotation signal processor conventionally used, for example, the method shown in Non-Patent Document 1 or the like is used. FIG. 9 is a block diagram showing a conventional rotation signal processor 100 of the tracking system. In the figure, an excitation signal source 3 is connected to a rotation detector 1 such as a resolver via an excitation amplifier 2. An excitation signal sin ωt from the excitation signal source 3 is amplified by the excitation amplifier 2 and applied to the rotation detector 1. For convenience of explanation, the amplitude of the excitation signal sin ωt is set to 1, but actually an arbitrary coefficient is multiplied. An excitation coil (not shown) of the rotation detector 1 is excited by the excitation signal sinωt. The excitation signal sin ωt is amplitude-modulated by the input angle θ, and from the output coil (not shown) of the rotation detector 1, a first amplitude modulation signal sin θ · sin (ωt−α) and a second amplitude modulation signal cos θ · sin ( ωt−α) is output as a rotation signal. Α indicates a phase difference (phase shift / phase error) caused by the rotation detector 1 itself, the sensor cable, and the like.

  A rotation signal processor 100 (R / D converter) is connected to the output terminal of the rotation detector 1. The rotation signal processor 100 includes first and second multipliers 101 and 102, a subtractor 103, synchronous detection means 104, an in-loop amplifier 107, a voltage controlled oscillator 109, a counter 110, and a P-ROM 111. It consists of and. The rotation signal processor 100 forms a negative feedback control system (tracking loop) in which the control deviation ε is zero as a whole.

  The first and second amplitude modulation signals sinθ · sin (ωt−α) and cosθ · sin (ωt−α) are subjected to signal processing by the first and second multipliers 101 and 102 and the subtractor 103. It is converted into an amplitude modulation signal f (θ) · sin (ωt−α). In this example, the amplitude modulation signal f (θ) · sin (ωt−α) becomes sin (θ−φ) · sin (ωt−α). θ) is arbitrarily modified.

  The synchronous detection means 104 performs synchronous detection of the amplitude modulation signal f (θ) · sin (ωt−α) using the excitation signal sinωt, and outputs the synchronous detection signal f (θ) · | sin (ωt−α) | obtain. The synchronous detection signal f (θ) · | sin (ωt−α) | becomes the control deviation ε of the tracking loop described above.

  The voltage controlled oscillator 109 outputs a pulse signal dφ / dt having a frequency corresponding to the magnitude of the control deviation ε. The counter 110 outputs an angle output φ by counting the pulses of the pulse signal dφ / dt. This angle output φ is a digital signal corresponding to the input angle θ of the rotation detector 1. The angle output φ is input to the P-ROM 111 and converted into sin φ and cos φ by the P-ROM 111. The sin φ and cos φ are fed back to the first and second multipliers 101 and 102 and used for signal processing in the first and second multipliers 101 and 102.

Figure 1 on page 10 of JEM-187 (issued by the Japan Electrical Manufacturers' Association, December 20, 1993)

In the conventional rotation signal processor as described above, since the synchronous detection of the amplitude modulation signal f (θ) · sin (ωt−α) is performed using the excitation signal sin ωt, the phase difference α exists as a value that cannot be ignored. This is an obstacle to accurate synchronous detection.
When the phase difference α increases, the loop gain of the tracking loop is equivalently reduced in the rotation signal processor 100, and as a result, the dynamic characteristics deteriorate. For this reason, in the conventional processor, the allowable range of the phase difference α is set to ± 10 ° or less, for example, and is defined to be used within this allowable range. Further, the phase difference α is detected, and the phase of the excitation signal sin ωt is adjusted by an external circuit so as to coincide with the phase of the carrier wave sin (ωt−α) or fall within the allowable range. However, since the allowable range of the phase difference α is so narrow as to impede practical use, the adjustment of the phase difference α is very complicated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an amplitude-modulated signal that can suppress the influence of the phase difference α on the synchronous detection to a small extent and improve the accuracy of the synchronous detection. The synchronous detection method and the rotation signal processor are provided.

In the synchronous detection method of the amplitude modulation signal according to the present invention, the amplitude modulation signal f (θ) · sin (ωt−) generated in the signal processing process of the rotation signal from the rotation detector in which the excitation signal sinωt is amplitude-modulated with the input angle θ. a synchronous detection method alpha), the amplitude-modulated signal f (θ) · sin (ωt -α) and the excitation signal sinωt and the amplitude modulation signal f to perform synchronous detection to eliminate the phase difference alpha (theta) It is a synchronous detection method of sin (ωt−α),
The first and second amplitude modulation signals sinθ · sin (ωt−α) and cosθ · sin (ωt−α), which are the rotation signals, are input to an excitation phase reference extraction unit, and the excitation phase reference extraction unit outputs an angle. Using φ, a signal having a large amplitude is selected from the first and second amplitude modulation signals sinθ · sin (ωt−α) and cosθ · sin (ωt−α), and a carrier phase component ωt−α is selected. As an extraction signal,
In the excitation phase reference extraction means, the extracted signal is compared with the phase ωt of the excitation signal sin ωt that becomes a reference phase, and when the phase difference α is less than ± 90 °, the extraction signal is output as an excitation phase reference. When the phase difference α is ± 90 ° or more, the excitation signal phase component ωt of the excitation signal sin ωt is output as the excitation phase reference,
The excitation phase reference is input to synchronous detection means, and the synchronous detection means uses the excitation phase reference as a polarity switching signal for demodulation of the modulation signal f (θ) of the amplitude modulation signal f (θ) · sin (ωt−α). Using the phase reference, the synchronous detection signal f (θ) · | sin (ωt−α) | is output.

  The rotation signal processor according to the present invention obtains an angle output φ from the first and second amplitude modulation signals sin θ · sin (ωt−α) and cos θ · sin (ωt−α) output from the rotation detector. A rotation signal processor for performing synchronous detection of an amplitude modulation signal f (θ) · sin (ωt−α) in a signal processing process, wherein the first and second amplitude modulation signals sinθ · sin (ωt−α), excitation phase reference extraction means for extracting the carrier phase component ωt-α from cos θ · sin (ωt-α) as an excitation phase reference; and the excitation phase reference extraction means connected to the excitation phase reference extraction means, and the input from the excitation phase reference extraction means And synchronous detection means for performing synchronous detection of the amplitude modulation signal f (θ) · sin (ωt−α) using an excitation phase reference.

  Further, the excitation phase reference extraction means is provided with an extraction signal selection unit, which extracts the first amplitude modulation signal sin θ · sin (ωt−α) based on the angle output φ. And the second amplitude modulation signal cos θ · sin (ωt−α), and selects either one of the larger amplitudes, and the selected first amplitude modulation signal sinθ · sin (ωt−α) or the second amplitude modulation. The carrier phase component ωt-α is extracted from the signal cos θ · sin (ωt−α). The extraction signal selection unit determines the quadrant of the input angle θ using the angle signals φ1 to φ3, and inverts the digital signals SIN and COS and the digital signals SIN and COS according to the determined quadrant of the input angle θ. By outputting one of the signals -SIN and -COS, the first amplitude modulation signal sinθ · sin (ωt−α) and the second amplitude modulation signal cosθ · sin (ωt−α) having a large amplitude can be used. The carrier phase component ωt-α is extracted as a pulse train having the frequency ωt-α.

  Further, the excitation phase reference extraction unit is provided with a phase difference determination unit, and the phase difference determination unit has a phase difference α between the carrier phase component ωt-α and the excitation signal sin ωt of less than ± 90 °. When the phase difference α is determined to be less than ± 90 °, the carrier phase component ωt-α is used as the excitation phase reference, and the phase difference α is determined to be ± 90 ° or more. In this case, the excitation signal phase component ωt of the excitation signal sin ωt is used as the excitation phase reference.

  Furthermore, the synchronous detection means performs synchronous detection of the amplitude modulation signal f (θ) · sin (ωt−α) by switching the polarity of the demodulation switch using the excitation phase reference, and performs synchronous detection. The signal f (θ) · | sin (ωt−α) | is output.

According to the synchronous detection method and the rotation signal processor of the amplitude modulation signal of the present invention, the excitation phase reference extraction means includes the first and second amplitude modulation signals sinθ · sin (ωt−α), cosθ · sin (ωt− The carrier wave phase component ωt−α is extracted from α) as the excitation phase reference, and the synchronous detection means uses the excitation phase reference input from the excitation phase reference extraction means to use the amplitude modulation signal f (θ) · sin ( Since synchronous detection of (ωt−α) is performed, the phase difference between the excitation phase reference and the amplitude modulation signal f (θ) · sin (ωt−α) can always be made zero. As a result, the influence of the phase difference α on the synchronous detection can be kept small, and the accuracy of the synchronous detection can be improved.
In other words, by suppressing the influence of the phase difference α to a small value, it is possible to more reliably prevent the loop gain of the tracking loop from being lowered, and to more reliably prevent the deterioration of the dynamic characteristics. Further, the phase adjustment of the excitation signal sin ωt using the phase difference α can be made unnecessary.
Further, signal processing can be realized with a simpler circuit, and the circuit scale can be reduced. In addition, when the monolithic IC is made, the chip area can be kept small, and commercialization (mass production) with high reliability, small size, and low price can be realized.

  Further, the extracted signal selection unit uses the angle output φ to generate an amplitude from the first amplitude modulation signal sin θ · sin (ωt−α) and the second amplitude modulation signal cos θ · sin (ωt−α). The carrier phase component ωt-α is selected from the first amplitude modulation signal sin θ · sin (ωt-α) or the second amplitude modulation signal cos θ · sin (ωt-α). Since it is extracted, the carrier phase component ωt-α can be extracted more reliably in response to the change in the input angle θ, and the accuracy of synchronous detection can be improved.

  Further, when the phase difference determination unit determines that the phase difference α is less than ± 90 °, the carrier phase component ωt-α is used as the excitation phase reference for the synchronous detection, so that the extraction reliability is improved. The carrier wave phase component ωt-α can be used as the excitation phase reference in a high range, and the accuracy of synchronous detection can be improved. When the phase difference α is determined to be ± 90 ° or more, the excitation signal phase component ωt of the excitation signal sin ωt is used as the excitation phase reference. Therefore, even if the phase difference α becomes large, the tracking loop And the reliability of the operation as a whole can be improved.

  Furthermore, the synchronous detection means performs synchronous detection of the amplitude modulation signal f (θ) · sin (ωt−α) by switching the polarity of the demodulation switch using the excitation phase reference, and performs synchronous detection. Since the signal f (θ) · | sin (ωt−α) | is obtained, synchronous detection can be performed more reliably, and the accuracy of synchronous detection can be improved.

The best mode for carrying out the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a main part of a rotation signal processor according to Embodiment 1 of the present invention, and shows a rotation signal processor to which a synchronous detection method of an amplitude modulation signal of the present invention is applied. The entire configuration of the rotation signal processor of FIG. 1 is the same as that of the conventional rotation signal processor (see FIG. 9), and FIG. 9 is used to describe the configuration of the embodiment. Note that the same or equivalent parts as those of the conventional processor are described using the same reference numerals.
In FIG. 1, the excitation phase reference extraction unit 115 includes an excitation signal sin ωt, first and second amplitude modulation signals sin θ · sin (ωt−α), cos θ · sin (ωt−α), which are rotation signals, and an angle. The output φ is input. As shown in FIG. 9, the excitation signal sin ωt is a signal input to the rotation detector 1 (resolver) via the excitation amplifier 2. The first and second amplitude modulation signals sinθ · sin (ωt−α) and cosθ · sin (ωt−α) are signals obtained by amplitude-modulating the excitation signal sinωt with the input angle θ by the rotation detector 1. α indicates a phase difference (phase shift / phase error) caused by the rotation detector 1 itself, the sensor cable, and the like. As is well known, the angle output φ is a digital signal obtained by performing signal processing on the first and second amplitude modulation signals sin θ · sin (ωt−α), cos θ · sin (ωt−α), and rotates. This corresponds to the input angle θ of the detector 1.

  The excitation phase reference extraction means 115 is based on the excitation signal sin ωt, the first and second amplitude modulation signals sin θ · sin (ωt−α), cos θ · sin (ωt−α), and the angle output φ. Thus, the excitation phase reference 116 is generated. The excitation phase reference 116 will be described in detail later.

  Synchronous detection means 104 is connected to the excitation phase reference extraction means 115. For example, the amplitude detection signal f (θ) · sin (ωt−α) from the subtractor 103 (see FIG. 9) is input to the synchronous detection means 104. In the example of FIG. 9, the amplitude modulation signal f (θ) · sin (ωt−α) becomes sin (θ−φ) · sin (ωt−α). F (θ) is arbitrarily changed by the method.

  As will be described in detail later, the synchronous detection means 104 uses the excitation phase reference 116 input from the excitation phase reference extraction means 115 to synchronize the amplitude modulation signal f (θ) · sin (ωt−α). By performing the detection, the synchronous detection signal f (θ) · | sin (ωt−α) | is output. This synchronous detection signal f (θ) · | sin (ωt−α) | is a control deviation ε of the tracking loop of the rotation signal processor (see FIG. 9), and the rotation signal processor sets the control deviation ε to zero. The angle output φ is obtained by performing the process.

  2 is a block diagram showing in detail the excitation phase reference extraction means 115 of FIG. 1, and FIG. 3 is an explanatory diagram showing the digital signals SIN and COS of FIG. In FIG. 2, the excitation phase reference extraction unit 115 is provided with an angle signal generation unit 120, an extraction signal selection unit 121, and a phase difference determination unit 122.

  The angle output φ is input to the angle signal generation unit 120. The angle signal generation unit 120 is configured by, for example, an FPGA or the like, and generates angle signals φ1 to φ3 based on the angle output φ. The angle signals φ1 to φ3 are binary digital signals weighted by 180 °, 90 °, and 45 °, respectively, as will be described later with reference to the drawings. In general, the angle output φ is handled as an absolute value, and is a binary parallel digital signal composed of the number of bits based on its resolution. Therefore, even if the angle signal generator 120 is not provided, The upper 3 bits correspond to φ1 to φ3.

  The first and second amplitude modulation signals sinθ · sin (ωt−α) and cosθ · sin (ωt−α) are converted into digital signals SIN and COS by passing through the first and second comparators 125 and 126. Is done. The digital signal SIN is a signal having the same phase when 0 ° ≦ θ <180 ° as a whole, and the opposite phase when 180 ° ≦ θ <360 °. Similarly, the digital signal COS is a signal that is in phase when 0 ° ≦ θ <90 ° and 270 ° ≦ θ <360 ° as a whole, and is in reverse phase when 90 ° ≦ θ <270 °. As is well known, the frequency ωt-α of the carrier wave component of the amplitude modulation signal is sufficiently larger than the frequency θ of the modulation component. As shown in FIG. 3, the digital signals SIN and COS are signals in which a pulse train having a frequency ωt−α is changed between an H level and an L level. That is, the digital signal SIN, COS holds the carrier phase component ωt-α.

  The extracted signal selection unit 121 includes first and second amplitude modulation signals sin θ · sin (ωt−α), cos θ · sin (ωt−α) converted into the digital signals SIN and COS, and the angle. The angle output φ converted into signals φ1 to φ3 is input.

  The extracted signal selection unit 121 uses a logic circuit described later based on the angle output φ to generate the first amplitude modulation signal sin θ · sin (ωt−α) and the second amplitude modulation signal cos θ · sin (ωt−α). ) To select one with a larger amplitude. Further, the extraction signal selection unit 121 extracts the carrier phase component ωt-α from the selected first amplitude modulation signal sinθ · sin (ωt−α) or the second amplitude modulation signal cosθ · sin (ωt−α). To do.

  The excitation signal sinωt is converted into a digital signal REF by passing through the third comparator 128. The digital signal REF is a signal that is at an H level when 0 ° ≦ ωt <180 ° and is at an L level when 0 ° ≦ ωt <180 °. That is, the digital signal REF is a pulse train having a frequency ωt and holds the excitation signal phase component ωt.

  The excitation signal sinωt converted to the digital signal REF, the extraction signal 127 from the extraction signal selection unit 121, and the clock 129 are input to the phase difference determination unit 122.

  The phase difference determination unit 122 determines whether or not the phase difference α between the carrier phase component ωt−α and the excitation signal sin ωt is less than ± 90 ° by a logic circuit described later. When the phase difference determination unit 122 determines that the phase difference α is less than ± 90 °, the carrier phase component ωt-α is used as the excitation phase reference 116, and the phase difference α is ± 90 ° or more. When the determination is made, the excitation signal sin ωt is used as the excitation phase reference 116.

  Next, FIG. 4 is a circuit diagram showing a logic circuit of the extraction signal selector 121 of FIG. 2, and FIG. 5 is an explanatory diagram showing the relationship between the angle signals φ1 to φ3 and the extraction signal 127 of FIG. The logic circuit of the extraction signal selection unit 121 includes a quadrant determination circuit unit 130 and an extraction selection circuit unit 131. The quadrant determination circuit unit 130 receives angle signals φ1 to φ3. The angle signals φ1 to φ3 are signals weighted by 180 °, 90 °, and 45 ° as described above, and become H level or L level according to the input angle θ as shown in FIG. As shown in FIGS. 4 and 5, the quadrant determination circuit unit 130 is a circuit in which any one of the outputs A to D becomes H level every time the input angle θ changes by 90 °, and the quadrant of the input angle θ is determined. It is a circuit for determining.

  The extraction / selection circuit unit 131 includes four AND circuits and one OR circuit. Each AND circuit receives the digital signals SIN and COS, the inverted signals -SIN and -COS, and the outputs A to D as inputs. The inverted signals -SIN and -COS are signals obtained by inverting the digital signals SIN and COS. That is, although it describes with -SIN etc. here,-such as -SIN means the bar (inversion) shown in FIG. The OR circuit receives the output of each AND circuit as an input. That is, the extraction selection circuit 131 is a circuit that outputs one of the digital signals SIN and COS and the inverted signals −SIN and −COS as the extraction signal 127 every time the input angle θ changes by 90 °. .

  In other words, when the extraction selection circuit unit 131 selects an output according to the output of the quadrant determination circuit unit 130, the first amplitude modulation signal sin θ · sin (ωt−α) determined to have a large amplitude or the The carrier phase component ωt-α is extracted from the second amplitude modulation signal cos θ · sin (ωt−α) as a pulse train having the frequency ωt−α. That is, the extraction signal selection unit 121 is configured to reliably output the extraction signal 127 regardless of the quadrant of the input angle θ. Note that the logic circuit of the extracted signal selection unit 121 does not cause a shift in the phase of the carrier component of the first and second amplitude modulation signals sin θ · sin (ωt−α) and cos θ · sin (ωt−α). It is configured on the assumption.

  Next, FIG. 6 is a circuit diagram showing a logic circuit of the phase difference determination unit 122 in FIG. 2, and FIG. 7 is a time chart showing each signal in the logic circuit in FIG. The logic circuit of the phase difference determination unit 122 includes a synchronization unit 140, a CLR signal generation unit 141, a selection timing signal generation unit 142, a phase difference signal generation unit 145, a phase difference counter 146, a phase difference holding unit 147, and an excitation phase reference selection unit. 148 and a function changeover switch unit 149.

  The synchronization unit 140 is a D-type flip-flop that receives a digital signal REF and a clock 129. The synchronization unit 140 outputs a synchronization REF signal 140a obtained by synchronizing the digital signal REF with the clock 129, and an inverted synchronization REF signal 140b obtained by inverting the synchronization REF signal 140a.

  The CLR signal generation unit 141 is a NAND circuit that receives the inverted synchronous REF signal 140b and the digital signal REF, and outputs an inverted CLR signal 141a. The selection timing signal generator 142 is an AND circuit that receives the synchronous REF signal 140a and a signal obtained by inverting the digital signal REF, and outputs a selection timing signal 142a. As shown in FIG. 6, the inverted CLR signal 141a is a pulse signal that becomes L level at the rising timing of the digital signal REF, and the selection timing signal 142a becomes H level at the falling timing of the digital signal REF. It is a pulse signal. That is, the timing when the inverted CLR signal 141a becomes L level and the timing when the selection timing signal 142a becomes H level are shifted from each other by a half cycle of the digital signal REF.

  The phase difference signal generation unit 145 is an AND circuit that receives the synchronous REF signal 140a and a signal obtained by inverting the extraction signal 127, and outputs a phase difference signal 145a. The phase difference signal 145a is a signal that is at the H level only during a period in which the synchronous REF signal 140a and the extraction signal 127 are shifted from each other, that is, during a phase difference α.

  The phase difference counter 146 is a counter that receives the phase difference signal 145a, the clock 129, and the inverted CLR signal 141a. The phase difference counter 146 counts the number of pulses of the clock 129 when the phase difference signal 145a is at the H level. The phase difference counter 146 clears the counted number of pulses of the clock 129 when the inverted CLR signal 141a becomes L level. The phase difference counter 146 detects the magnitude of the phase difference α by counting the number of pulses of the clock 129.

  The phase difference state signal 146a that is the output of the phase difference counter 146 is at the H level when the phase difference α is ± 90 ° or more, and is at the L level when the phase difference α is less than ± 90 °. . If the excitation frequency ωt is, for example, 10 kHz, the phase difference α is ± 90 ° in 25 μsec. At this time, assuming that the frequency of the clock 129 is 20 MHz, the phase difference state signal 146a is set to the H level when 500 counts are reached.

  The phase difference holding unit 147 is a D-type flip-flop that receives the phase difference state signal 146a, the constant voltage signal 150, and the CLR signal 141a. The phase difference holding unit 147 holds the constant voltage signal 150, that is, the H level state at the rising edge of the phase difference state signal 146a. Further, the phase difference holding unit 147 clears the holding state at the timing when the inverted CLR signal 141a becomes the L level (at the timing when the digital signal REF rises).

  The excitation phase reference selection unit 148 is composed of a plurality of AND circuits, S / R type flip-flops, and OR circuits, and as shown in FIG. This is a circuit that selects a signal to be output from the extraction signal 127 and the digital signal REF at the timing when the digital signal REF falls. That is, the excitation phase reference selection unit 148 outputs the extraction signal 127 when the phase difference α is less than ± 90 ° (when the inverted output −Q of the phase difference holding unit 147 is at the H level). Further, the excitation phase reference selection unit 148 outputs the digital signal REF (excitation signal phase component ωt) when the phase difference α is ± 90 ° or more (when the output Q of the phase difference holding unit 147 is H level). Output.

  Here, when the phase difference α is ± 90 ° or more, the digital signal REF is output as the excitation phase reference 116 because the reliability of the extraction signal 127 decreases when the phase difference α is ± 90 ° or more. This is because it may be difficult to maintain the tracking loop. Originally, in the synchronous detection, it is completely unexpected that the phase difference α is ± 90 ° or more, but the digital signal REF is used as the excitation phase reference 116 even if the phase difference α is ± 90 ° or more. For example, the polarity inversion, the decrease of the loop gain, and the deterioration of the dynamic characteristics cannot be prevented, but the tracking loop function can be maintained. That is, the reliability of the operation as a whole is improved by selecting a signal to be output as the excitation phase reference 116.

  The function changeover switch unit 149 is a switch for switching whether or not to invalidate the function of the entire phase difference determination unit 122. That is, it is a switch for switching whether the output of the excitation phase reference selection unit 148 is output as the excitation phase reference 116 or whether the digital signal REF is output as the excitation phase reference 116 as in the prior art. This is because it is assumed that the phase difference determination unit 122 does not function normally in a transient state such as when the operation system is turned on (started up) or when the resolver is disconnected, and is provided as a workaround. Is. That is, during normal times, the output of the excitation phase reference selection unit 148 is output as the excitation phase reference 116.

  Next, FIG. 8 is a circuit diagram specifically showing the synchronous detection means 104 of FIG. In the figure, the synchronous detection means 104 is a circuit composed of an inverter 155 and a demodulation switch 156. By switching the polarity of the demodulation switch 156 in accordance with the output level of the excitation phase reference 116, an amplitude modulation signal An inverted / non-inverted signal of f (θ) · sin (ωt−α) is output. That is, the non-inverted signal is output in a range of 0 ° ≦ ωt−α <180 ° where sin (ωt−α) takes a positive value, and 180 ° ≦ ωt where sin (ωt−α) takes a negative value. By outputting the inverted signal in the range of −α <360 °, the synchronous detection signal f (θ) · | sin (ωt−α) | is obtained. Thereby, synchronous detection can be performed more reliably and the accuracy of synchronous detection can be improved.

Therefore, in the synchronous detection method of the amplitude modulation signal in this embodiment, the amplitude modulation signal f (θ) · generated in the signal processing process of the rotation signal from the rotation detector 1 in which the excitation signal sinωt is amplitude-modulated at the input angle θ. This is a synchronous detection method for sin (ωt−α), in which the phase difference α between the amplitude modulation signal f (θ) · sin (ωt−α) and the excitation signal sinωt is eliminated to perform synchronous detection.
Further, the first and second amplitude modulation signals sinθ · sin (ωt−α) and cosθ · sin (ωt−α), which are the rotation signals, are input to the excitation phase reference extraction unit 115, and the excitation phase reference extraction unit 115. Is selected from the first and second amplitude modulation signals sinθ · sin (ωt−α) and cosθ · sin (ωt−α) using the angle output φ, and the carrier phase The component ωt−α is extracted as the extraction signal 127.
Further, in the excitation phase reference extraction means 115, the extraction signal 127 is compared with the phase ωt of the excitation signal sin ωt serving as a reference phase. When the phase difference α is less than ± 90 °, the extraction signal 127 is excited. When the phase difference α is ± 90 ° or more, the excitation signal phase component ωt of the excitation signal sin ωt is output as the excitation phase reference 116.
Furthermore, the excitation phase reference 116 is input to the synchronous detection means 104, and the synchronous detection means 104 is for demodulating the modulation signal f (θ) of the amplitude modulation signal f (θ) · sin (ωt−α). The excitation phase reference 116 is used as a polarity switching signal, and a synchronous detection signal f (θ) · | sin (ωt−α) | is output.

In addition, the rotation signal processor in this embodiment is applied with the above-described synchronous detection method of the amplitude modulation signal, and the first and second amplitude modulation signals sin θ · sin (output from the rotation detector 1 are used. A rotation signal processor that performs synchronous detection of the amplitude modulation signal f (θ) · sin (ωt−α) in the signal processing process for obtaining the angle output φ from ωt−α), cos θ · sin (ωt−α). Excitation phase reference extraction means 115 for extracting the carrier phase component ωt-α as the excitation phase reference 116 from the first and second amplitude modulation signals sinθ · sin (ωt−α) and cosθ · sin (ωt−α); The amplitude modulation signal f (θ) · sin (ωt−α) is synchronously detected using the excitation phase reference 116 connected to the excitation phase reference extraction means 115 and input from the excitation phase reference extraction means 115. same And a detecting means 104.
In addition, the excitation phase reference extraction unit 115 is provided with an extraction signal selection unit 121, which extracts the first amplitude modulation signal sin θ · sin (ωt) based on the angle output φ. -Α) and the second amplitude modulation signal cosθ · sin (ωt-α), and selects one having a large amplitude, and the selected first amplitude modulation signal sinθ · sin (ωt-α) or the second amplitude modulation signal. The carrier phase component ωt-α is extracted from the two-amplitude modulation signal cos θ · sin (ωt-α).
Further, the extracted signal selection unit 121 has a signal obtained by converting the angle output φ and weighted 180 °, 90 °, and 45 °, and the first amplitude modulation signal. sin θ · sin (ωt−α) is a converted signal, and is in-phase when 0 ° ≦ θ <180 °, and is a pulse train of frequency ωt−α that is in reverse phase when 180 ° ≦ θ <360 °. Is a signal obtained by converting the digital signal SIN and the second amplitude modulation signal cos θ · sin (ωt−α), and is in phase when 0 ° ≦ θ <90 ° and 270 ° ≦ θ <360 °. , 90 ° ≦ θ <270 °, and a digital signal COS that is a pulse train having a frequency ωt−α that is in reverse phase is input, and the extraction signal selection unit 121 uses the angle signals φ1 to φ3 as input angles. Determine the quadrant of θ, and enter the quadrant of the determined input angle θ Accordingly, the digital signal SIN, COS and the inverted signal -SIN, -COS of the digital signal SIN, COS are output as the extraction signal 127, so that the first amplitude modulation signal sin θ · sin having a large amplitude is output. The carrier phase component ωt-α is extracted as a pulse train having a frequency ωt-α from (ωt-α) or the second amplitude modulation signal cosθ · sin (ωt-α).
Furthermore, the excitation phase reference extraction unit 115 is provided with a phase difference determination unit 122, and the phase difference determination unit 122 has a phase difference α between the carrier phase component ωt−α and the excitation signal sin ωt within ±. It is determined whether the phase difference α is less than 90 °, and when it is determined that the phase difference α is less than ± 90 °, the carrier wave phase component ωt-α is used as the excitation phase reference 116, and the phase difference α is ± 90. When it is determined that the angle is greater than or equal to °, the excitation signal phase component ωt of the excitation signal sin ωt is used as the excitation phase reference.
The synchronous detection means 104 performs synchronous detection of the amplitude modulation signal f (θ) · sin (ωt−α) by switching the polarity of the demodulation switch 156 using the excitation phase reference 116. The synchronous detection signal f (θ) · | sin (ωt−α) | is output.

It is a block diagram which shows the principal part of the rotation signal processor by Embodiment 1 of this invention. It is a block diagram which shows the excitation phase reference | standard extraction means of FIG. 1 in detail. It is explanatory drawing which shows the digital signals SIN and COS of FIG. FIG. 3 is a circuit diagram illustrating a logic circuit of an extraction signal selection unit in FIG. 2. It is explanatory drawing which shows the relationship between angle signal (phi) 1-phi3 of FIG. 4, and an extraction signal. FIG. 3 is a circuit diagram illustrating a logic circuit of a phase difference determination unit in FIG. 2. It is a time chart which shows each signal in the logic circuit of FIG. It is a circuit diagram which shows concretely the synchronous detection means of FIG. It is a block diagram which shows the rotation signal processor of the conventional tracking system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation detector 104 Synchronous detection means 115 Excitation phase reference extraction means 116 Excitation phase reference 121 Extraction signal selection part 122 Phase difference discrimination | determination part 127 Extraction signal 156 Demodulation switch

Claims (6)

A synchronous detection method of an amplitude modulation signal f (θ) · sin (ωt−α) generated in a signal processing process of a rotation signal from a rotation detector (1) in which an excitation signal sinωt is amplitude-modulated at an input angle θ, A method of synchronous detection of an amplitude modulation signal for performing synchronous detection by eliminating the phase difference α between the amplitude modulation signal f (θ) · sin (ωt−α) and the excitation signal sinωt ;
The first and second amplitude modulation signals sinθ · sin (ωt−α) and cosθ · sin (ωt−α), which are the rotation signals, are input to the excitation phase reference extraction means (115),
The excitation phase reference extraction means (115) uses the angle output φ to generate any amplitude from the first and second amplitude modulation signals sin θ · sin (ωt−α) and cos θ · sin (ωt−α). , A carrier phase component ωt-α is extracted as an extraction signal (127),
In the excitation phase reference extraction means (115),
The extracted signal (127) is compared with the phase ωt of the excitation signal sin ωt serving as a reference phase, and when the phase difference α is less than ± 90 °, the extracted signal (127) is output as the excitation phase reference (116). Let
When the phase difference α is ± 90 ° or more, the excitation signal phase component ωt of the excitation signal sin ωt is output as the excitation phase reference (116),
The excitation phase reference (116) is input to the synchronous detection means (104),
The synchronous detection means (104) uses the excitation phase reference (116) as a polarity switching signal for demodulation of the modulation signal f (θ) of the amplitude modulation signal f (θ) · sin (ωt−α), and performs synchronization. A synchronous detection method for an amplitude modulation signal, wherein the detection signal f (θ) · | sin (ωt−α) | is output . In the signal processing process for obtaining the angle output φ from the first and second amplitude modulation signals sin θ · sin (ωt−α) and cos θ · sin (ωt−α) output from the rotation detector (1), the amplitude modulation signal f A rotation signal processor that performs synchronous detection of (θ) · sin (ωt−α),
Excitation phase reference extraction means (115) for extracting the carrier phase component ωt-α as the excitation phase reference (116) from the first and second amplitude modulation signals sin θ · sin (ωt-α) and cos θ · sin (ωt-α). )When,
The amplitude modulation signal f (θ) · sin (ωt−α) is connected to the excitation phase reference extraction means (115) and uses the excitation phase reference (116) input from the excitation phase reference extraction means (115). And a synchronous detection means (104) for performing synchronous detection. The excitation phase reference extraction means (115) is provided with an extraction signal selection unit (121),
The extraction signal selection unit (121)
Based on the angle output φ, one of the first amplitude modulation signal sinθ · sin (ωt−α) and the second amplitude modulation signal cosθ · sin (ωt−α) is selected, and this claim 2, characterized in that extracting the carrier phase component .omega.t-alpha from the selected first amplitude modulation signal sinθ · sin (ωt-α) or the second amplitude modulation signal cosθ · sin (ωt-α) The rotation signal processor described. In the extraction signal selection unit (121),
A signal based on the angle output φ, which is weighted to 180 °, 90 °, 45 °, and angle signals φ1 to φ3;
The first amplitude modulation signal sin θ · sin (ωt−α) is a converted signal, and is in phase when 0 ° ≦ θ <180 ° and is out of phase when 180 ° ≦ θ <360 °. A digital signal SIN which is a pulse train of frequency ωt−α,
The second amplitude modulation signal cos θ · sin (ωt−α) is a converted signal, and is in phase when 0 ° ≦ θ <90 °, 270 ° ≦ θ <360 °, and 90 ° ≦ θ <270. And a digital signal COS, which is a pulse train having a frequency ωt−α that is in reverse phase in the case of °,
The extraction signal selection unit (121)
Determine the quadrant of the input angle θ using the angle signals φ1 to φ3,
Depending on the quadrant of the determined input angle θ, the digital signal SIN, COS and the inverted signal -SIN, -COS of the digital signal SIN, COS are output as the extraction signal (127), so that the amplitude is increased. The carrier phase component ωt-α is extracted as a pulse train having a frequency ωt-α from the large first amplitude modulation signal sinθ · sin (ωt-α) or the second amplitude modulation signal cosθ · sin (ωt-α). The rotation signal processor according to claim 3 . The excitation phase reference extraction means (115) is provided with a phase difference determination unit (122),
The phase difference determination unit (122)
It is determined whether or not the phase difference α between the carrier phase component ωt-α and the excitation signal sin ωt is less than ± 90 °, and when it is determined that the phase difference α is less than ± 90 °, the carrier phase component ωt−α is used as the excitation phase reference (116), and when it is determined that the phase difference α is ± 90 ° or more, the excitation signal phase component ωt of the excitation signal sin ωt is used as the excitation phase reference. The rotation signal processor according to any one of claims 2 to 4 . The synchronous detection means (104)
By switching the polarity of the demodulation switch (156) using the excitation phase reference (116), the amplitude modulation signal f (θ) · sin (ωt−α) is synchronously detected, and the synchronous detection signal f ( The rotation signal processor according to any one of claims 2 to 5, wherein θ) · | sin (ωt-α) | is output.

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