JP5601339B2 - Position detection device - Google Patents

Description

  The present invention relates to a position detection device including a resolver that detects a rotational angle position of a motor.

  The position detection device converts a three-phase current signal output from a resolver supplied with an excitation signal (carrier signal) into a voltage signal by a current / voltage converter, converts the voltage signal into a sin signal and a cos signal, The device further converts the digital angle signal, supplies the digital angle signal to a CPU to calculate a position detection value, and outputs a drive signal (PWM drive signal) to the electric motor to drive the electric motor.

By the way, the above-described position detection device has noise generated by the PWM drive signal input to the electric motor and noise generated by interference between the PWM drive frequency of the PWM drive signal and the resolver excitation frequency of the resolver excitation signal input to the resolver. And superimposed on the position detection value.
In order to prevent interference noise between the PWM drive frequency and the resolver excitation frequency, the current technology requires that the PWM drive frequency and the resolver excitation frequency be separated from each other.

In general, it is necessary to set the band of current control to flow for rotating the electric motor sufficiently higher than the band of position control based on the position information obtained from the resolver. In order to increase the current control band, it is necessary to set the PWM drive frequency high. In order to prevent interference noise, the resolver excitation frequency is decreased.
However, when the resolver excitation frequency is lowered, there is a problem that the speed at which position detection is possible decreases. That is, since the resolver modulation frequency is proportional to the rotation speed, when the rotation speed increases, the resolver modulation frequency approaches the resolver excitation frequency, and normal position detection cannot be performed.

  Here, a method of preventing the interference noise by raising the resolver excitation frequency above the PWM drive frequency is also conceivable. However, when the resolver excitation frequency is increased, the impedance of the resolver composed of the coil is increased, and the resolver current is decreased. There is concern about the decline. In order to avoid this, it is necessary to increase the excitation voltage, and additional components such as a booster circuit are required. Furthermore, there is a demerit that the power consumption increases as a result of increasing the excitation voltage.

On the other hand, as a technique for removing noise superimposed on a position detection value without changing the PWM drive frequency and the resolver excitation frequency, for example, an apparatus of Patent Document 1 is known. The device disclosed in Patent Document 1 includes a filter circuit that removes noise at the driving frequency of the illumination unit.
The device of Patent Document 1 does not take into consideration variations in the driving frequency of the illumination means, and the stop band of the filter circuit must be set wide.

JP-A-5-274085

When the filter circuit of Patent Document 1 is applied to the position detection device described above, a filter circuit having a wide stop band including the frequency range of the PWM drive signal and the frequency range of the excitation signal is provided.
When the position detection value passes through such a wide stop band filter circuit, a signal delay occurs in the position detection value, which may affect the response of the motor control.
Therefore, the present invention has been made paying attention to the unsolved problems of the above conventional example,
An object of the present invention is to provide a position detection device that can remove noise superimposed on a position detection value without affecting the responsiveness of motor control and can normally perform position detection during high-speed rotation. .

  In order to achieve the above object, a position detection device according to claim 1 of the present invention is an excitation signal generating means for outputting a resolver excitation signal to a resolver for detecting a rotational angle position of a motor, and output from the resolver. A resolver / digital signal conversion means for converting an analog position detection signal into a digital position detection value, a filter means for removing noise of the position detection value output from the resolver / digital signal conversion means, and a motor driven A drive signal output means for outputting a signal, a drive frequency acquisition means for acquiring a drive frequency of the drive signal generated by the drive signal output means, and a noise frequency caused by the drive frequency. A noise frequency calculating means for calculating, and a filter function of the filter means so as to prevent the noise frequency. A noise rejection band setting means for setting a an apparatus and a filter coefficient output means for outputting said filter coefficient to the filter circuits setting mechanism by the noise rejection band setting means.

  According to a second aspect of the present invention, there is provided the position detection apparatus according to the first aspect, further comprising excitation frequency acquisition means for acquiring a resolver excitation frequency of the resolver excitation signal generated by the excitation signal generation means, and the noise frequency calculation. The means also calculates a noise frequency resulting from interference between the drive frequency and the resolver excitation frequency in addition to the noise frequency due to the drive frequency, and the noise prevention band setting means is configured to reduce the noise frequency due to the drive frequency. The filter coefficient of the filter circuit is set using the noise frequency generated by the interference between the drive frequency and the resolver excitation frequency and the higher harmonic frequency thereof.

  According to the position detection apparatus of the first aspect of the present invention, the position detection value output from the resolver / digital signal conversion means is a value from which noise generated by the drive signal is removed by passing through the filter means. Therefore, highly accurate position detection can be performed. And since a position detection value passes a filter means with a narrow stop band, the signal delay of a position detection value can be eliminated, and the influence on control responsiveness can be reduced.

  According to the position detection device of the second aspect of the present invention, the position detection value output from the resolver / digital signal conversion means passes through the filter means, so that the noise generated by the drive signal, the drive signal, Since the noise resulting from the interference with the resolver excitation signal is also removed, the position can be detected with higher accuracy. In addition, it is not necessary to greatly reduce the resolver excitation frequency with respect to the drive frequency in order to reduce noise due to interference, and since the resolver excitation frequency can be received as much as possible, the position detection during high-speed rotation of the motor can be performed normally. it can.

It is a block diagram which shows the position detection apparatus of 1st Embodiment which concerns on this invention. It is a flowchart which shows the noise cut process which the position detection apparatus of 1st Embodiment which concerns on this invention performs. It is a block diagram which shows the position detection apparatus of 2nd Embodiment which concerns on this invention. It is a flowchart which shows the noise cut process which the position detection apparatus of 2nd Embodiment which concerns on this invention performs.

DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a position detection apparatus according to a first embodiment mounted on, for example, a positioning motor / actuator. The position detection apparatus includes an electric motor 1, a resolver 2, and a drive unit 3. The drive unit 3 includes a resolver / A digital signal conversion circuit (RDC) 4, a motor drive circuit 5, an excitation signal generation circuit 6, and a CPU 7 are provided.

The CPU 7 includes a PWM signal generation unit 8, a PWM drive frequency measurement unit 9, a resolver excitation frequency measurement unit 10, a noise frequency estimation unit 11, a noise stop band setting unit 12, and a notch filter circuit 13. Yes.
The excitation signal generation circuit 6 of the drive unit 3 generates a resolver excitation signal V _C (t). When this resolver excitation signal V _C (t) is output to the resolver 2, the rotational angle position of the electric motor 1 is determined from the resolver 2. The position detection signals V _cos (t) and V _sin (t) shown are input to the RDC 4 of the drive unit 3 via the current / voltage conversion circuits 15 and 16.

The RDC 4 is a device that converts an analog signal (position detection signals V _cos (t), V _sin (t)) into a digital signal (position detection value φ).
The PWM signal generator 8 of the CPU 7 generates a drive signal (PWM signal) based on the position detection value φ, and the PWM signal input to the motor drive circuit 5 is output to the electric motor 1.
The PWM drive frequency measuring unit 9 measures the PWM drive frequency ω _pwm of the PWM signal generated by the PWM signal generating unit 8.

Further, the resolver excitation frequency measurement unit 10 measures the resolver excitation frequency omega _C of the resolver excitation signal generated by excitation signal generating circuit 6.
Further, the noise frequency estimation unit 11 estimates the noise frequency based on the PWM drive frequency ω _pwm and the resolver excitation frequency ω _C.
The noise stop band setting unit 12 sets a filter coefficient for setting a stop band corresponding to the noise frequency estimated by the noise frequency estimation unit 11.
The notch filter circuit 13 to which a predetermined filter coefficient is input from the noise stop band setting unit 12 removes noise from the input position detection value φ and outputs it.

Next, before explaining the operation of the present embodiment, the principle of noise superimposed on the position detection value φ will be described with reference to FIG.
The resolver excitation signal V _C (t) generated by the excitation signal generation circuit 6 is input to the resolver 2 and position detection signals V _cos (t) and V _sin (t) including position information are output.
These signals V _C (t), V _cos (t), and V _sin (t) are expressed by the following Expression 1, Expression 2, and Expression 3.

The PWM drive signal (rectangular wave) V _pwm (t) generated by the PWM signal generation unit 8 is output from the motor drive circuit 5 to the electric motor 1. This PWM drive signal V _pwm (t) is expressed by the following Equation 4.

From Equation 4, the noise component generated from PWM drive signal V _pwm (t) is approximated by Equation 5 below.

The interference noise V _noise (t) generated by the resolver excitation signal and the PWM drive signal generated in the electric motor 1, on the cable, and in the drive unit 3 can be expressed by the following Expression 7 and Expression 9.
Here, there are the following two cases depending on the conditions of the PWM drive frequency ω _pwm and the resolver excitation frequency ω _C.
Case (1): ω _C ≦ ω _pwm

Case (2): ω _C > ω _pwm

Therefore, from the above formulas 6 and 7, it can be seen that the frequency components of the interference noise are composed of ω _center and ω _noise and their harmonics.
That is, in addition to V _noise (t), noise V _pwmnoise (t) generated from the PWM drive signal V _pwm (t) shown in Expression 5 is superimposed on the position detection signal. When all these noises are expressed by the following expression 10, the position detection signal including the noise is expressed by the following expressions 11 and 12.

  When the position detection signal (analog) is converted into a position detection value (digital) by the RDC 4, the position detection value φ is expressed by the following Expression 15. In addition, the following formula | equation 13 and formula | equation 14 have shown the arithmetic expression inside RDC4.

From Expression 15, it can be seen that when the _{RDC 4} converts the position detection signal into the position detection value φ, the noise V noise is superimposed.
Therefore, it is estimated from the above-described Expressions 4, 7, and 9 that noise including frequency components (1) and (2) shown below is superimposed on the position detection value φ.
(1) Noise frequency ω _pwmnoise caused by PWM drive frequency ω _pwm
(2) Noise frequencies ω _center and ω _noise resulting from interference between PWM drive frequency ω _pwm and resolver excitation frequency ω _C

Therefore, the CPU 7 of the position detection apparatus according to the present embodiment executes a noise cut process shown in the flowchart of FIG.
First, in step ST1, the resolver excitation frequency measurement unit 10 measures the resolver excitation frequency ω _C of the resolver excitation signal V _C (t) generated by the excitation signal generation circuit 6.
Subsequently, the process proceeds to step ST2, and the PWM drive frequency measurement unit 9 measures the PWM drive frequency ω _pwm of the PWM drive signal V _pwm (t) generated by the PWM signal generation unit 8.
Next, the process proceeds to step ST3, and the noise frequency estimation unit 11 calculates the noise frequency ω _pwmnoise resulting from the PWM drive frequency ω _pwm using the above-described equation 5.

Next, the process proceeds to step ST4, where the noise frequency estimation unit 11 calculates noise frequencies ω _center and ω _noise resulting from interference between the PWM drive frequency ω _pwm and the resolver excitation frequency ω _C. In this step, as described above, when ω _C ≦ ω _pwm , the above-described equation 6 is referred to, and when ω _C > ω _pwm , the above-described equation 8 is referred to.
Next, the _{process proceeds} to step ST5, where the noise stop band setting unit 12 _calculates a filter coefficient for narrowing the stop band of the notch filter circuit 13 based on the noise frequencies ω _pwmnoise , ω _center , ω _noise and their high frequency frequencies. Set.

Next, the process proceeds to step ST6, and the filter coefficient set by the noise stop band setting unit 12 is output to the notch filter circuit 13.
The electric motor 1 corresponds to the motor, the excitation signal generation circuit 6 corresponds to the excitation signal generation means, the RDC 4 corresponds to the resolver / digital signal conversion means, the notch filter circuit 13 corresponds to the filter means, and PWM drive The frequency measurement unit 9 and step ST2 correspond to the drive signal acquisition unit, the noise frequency estimation unit 11 and step ST3 correspond to the noise frequency calculation unit, and the noise stop band setting unit 12 and step ST5 correspond to the noise stop band setting unit. Step ST6 corresponds to the filter coefficient output means, and the resolver excitation frequency measurement unit 10 and step ST1 correspond to the excitation frequency acquisition means.

Therefore, the position detection value φ output from the RDC 4 passes through the notch filter circuit 13 that has been changed to the _noise coefficients ω _pwmnoise , ω _center , ω _noise, and filter coefficients based on these high frequency frequencies in the noise cut processing. noise _{V Pwmnoise} generated by PWM driving signal _{V pwm (t) (t)} , the resolver excitation signal _V C (t) and the noise _{V noise} (t) due to interference with the PWM driving signal _{V pwm} (t) is removed Is output as the detected position value φ.

Since the position detection value φ from which noise is removed is used as the position feedback value of the positioning control loop, it is possible to provide a highly accurate positioning motor / actuator and to detect and position weak vibrations. It can also be applied to.
Further, by performing the noise cut processing of the present embodiment to form the notch filter circuit 13 having a narrow stop band, the signal delay of the position detection value φ can be eliminated, thereby reducing the influence on the control responsiveness. Can do.

In the noise cut processing of the present embodiment, the resolver excitation frequency ω _C of the resolver excitation signal generated by the excitation signal generation circuit 6 is measured instead of calculating the noise frequency from the position detection value of the rotation state of the electric motor 1. Then, the PWM drive frequency ω _pwm of the PWM signal generated by the PWM signal generator 8 is measured, and the noise frequency is calculated based on the measured PWM signal, so that the noise is removed even when the electric motor 1 is rotating. The position detection value φ can be obtained accurately.

Furthermore, increased without the need to lower the resolver excitation frequency omega _C the PWM driving frequency omega _pwm to reduce noise due to interference, can be received as much as possible the resolver excitation frequency omega _C, during high-speed rotation of the electric motor 1 Can be normally detected.
Next, FIG. 3 is a block diagram showing a position detection apparatus according to a second embodiment mounted on a positioning motor / actuator. The same components as those of the position detection device of the first embodiment shown in FIG.

The position detection device of the present embodiment includes an electric motor 1, a resolver 2, and a drive unit 3, and the drive unit 3 includes a motor drive circuit 5, a CPU 7, and an excitation amplifier 19.
The CPU 7 includes a resolver / digital signal conversion circuit (RDC) 4, an excitation signal generation circuit 6, a PWM signal generation unit 8, a resolver excitation frequency setting unit 17, a PWM drive frequency setting unit 18, and a noise frequency estimation unit 11. And a noise stop band setting unit 12 and a notch filter circuit 13.

The resolver excitation frequency setting unit 17 of the CPU 7 sets the resolver excitation frequency ω _C for generating the resolver excitation signal V _C (t) to the excitation signal generation circuit 6.
Further, the PWM drive frequency setting unit 18 of the CPU 7 sets the PWM drive frequency ω _pwm for generating V _pwm (t) to the PWM signal generation unit 8.
Further, the PWM signal generation unit 8 of the CPU 7 generates V _pwm (t) based on the PWM drive frequency ω _pwm input from the PWM drive frequency setting unit 18.

The excitation amplifier 19 of the drive unit 3 amplifies the resolver excitation signal V _C (t) generated by the excitation signal generation circuit 6.
The CPU 7 of the position detection apparatus according to the present embodiment executes a noise cut process shown in the flowchart of FIG.
First, in step ST11, the resolver excitation frequency setting unit 17 outputs the resolver excitation frequency omega _C against noise frequency estimation unit 11.
Subsequently, the process proceeds to step ST <b> 12, and the PWM drive frequency measurement unit 9 outputs the PWM drive frequency ω _pwm to the noise frequency estimation unit 11.
Next, the process proceeds to step ST13, and the noise frequency estimation unit 11 calculates the noise frequency ω _pwmnoise caused by the PWM drive frequency ω _pwm using the above-described equation 5.

Next, the process proceeds to step ST14, where the noise frequency estimation unit 11 calculates noise frequencies ω _center and ω _noise resulting from interference between the PWM drive frequency ω _pwm and the resolver excitation frequency ω _C. In this step, as described above, when ω _C ≦ ω _pwm , the above-described equation 6 is referred to, and when ω _C > ω _pwm , the above-described equation 8 is referred to.
Subsequently, the process proceeds to step ST15, where the noise stop band setting unit 12 _calculates a filter coefficient for narrowing the stop band of the notch filter circuit 13 based on the noise frequencies ω _pwmnoise , ω _center , ω _noise and their high frequency frequencies. Set.
Next, the process proceeds to step ST <b> 16, and the filter coefficient set by the noise stop band setting unit 12 is output to the notch filter circuit 13.

  The electric motor 1 corresponds to the motor, the excitation signal generation circuit 6 corresponds to the excitation signal generation means, the RDC 4 corresponds to the resolver / digital signal conversion means, the notch filter circuit 13 corresponds to the filter means, and PWM drive The frequency setting unit 18 and step ST12 correspond to the drive signal acquisition unit, the noise frequency estimation unit 11 and step ST13 correspond to the noise frequency calculation unit, and the noise stop band setting unit 12 and step ST15 correspond to the noise stop band setting unit. Step ST16 corresponds to the filter coefficient output means, and the resolver excitation frequency setting unit 17 and step ST11 correspond to the excitation frequency acquisition means.

Therefore, the position detection value φ output from the RDC 4 passes through the notch filter circuit 13 that has been changed to the _noise coefficients ω _pwmnoise , ω _center , ω _noise, and filter coefficients based on these high frequency frequencies in the noise cut processing. noise _{V Pwmnoise} generated by PWM driving signal _{V pwm (t) (t)} , the resolver excitation signal _V C (t) and the noise _{V noise} (t) due to interference with the PWM driving signal _{V pwm} (t) is removed Is output as the detected position value φ.

Since the position detection value φ from which noise is removed is used as the position feedback value of the positioning control loop, it is possible to provide a highly accurate positioning motor / actuator and to detect and position weak vibrations. It can also be applied to.
Further, by performing the noise cut processing of the present embodiment to form the notch filter circuit 13 having a narrow stop band, the signal delay of the position detection value φ can be eliminated, thereby reducing the influence on the control responsiveness. Can do.

In the noise cut processing according to the present embodiment, the noise frequency is not calculated from the position detection value of the rotation state of the electric motor 1, but the resolver excitation frequency ω _C set by the resolver excitation frequency setting unit 17 and the PWM drive frequency. Since the noise frequency is calculated based on the PWM drive frequency ω _pwm set by the setting unit 18, it is possible to accurately obtain the position detection value φ from which the noise is removed even when the electric motor 1 is in a rotating state. .
Also, increased without the need to lower the resolver excitation frequency omega _C the PWM driving frequency omega _pwm to reduce noise due to interference, can be received as much as possible the resolver excitation frequency omega _C, during high-speed rotation of the electric motor 1 Can be normally detected.

Further, in this embodiment, the resolver excitation frequency setting unit 17 in the CPU 7 sets the resolver excitation frequency ω _C and outputs it to the noise frequency estimation unit 11, and the PWM drive frequency setting unit 18 in the CPU 7 sets the PWM drive frequency ω _pwm. And output to the noise frequency estimator 11. Compared with the first embodiment, the resolver excitation frequency measurement unit 10 measures the resolver excitation frequency ω _C from the excitation signal generation circuit 6 and the PWM drive frequency. The measurement of the PWM drive frequency ω _pwm from the PWM signal generation unit 8 by the measurement unit 9 is not necessary, and the number of components required for the measurement of the resolver excitation frequency ω _C and the PWM drive frequency ω _pwm is reduced and the arithmetic processing of the CPU 7 is reduced. Can do.
In the first and second embodiments described above, the position detection device mounted on the positioning motor / actuator has been described. However, the gist of the present invention is not limited to this, and for example, a controller for a servo motor, You may apply to the position detection apparatus of an encoder and an electric power steering device.

DESCRIPTION OF SYMBOLS 1 ... Electric motor, 2 ... Resolver, 3 ... Drive unit, 5 ... Motor drive circuit, 6 ... Excitation signal generation circuit, 7 ... CPU, 8 ... Signal generation part, 9 ... PWM drive frequency measurement part, 10 ... Resolver excitation frequency measurement 11, noise frequency estimator 12, noise stop band setting unit 13, notch filter circuit 15, 16 current / voltage conversion circuit 17, resolver excitation frequency setting unit 18, PWM drive frequency setting unit V _C (t) ... resolver excitation _{signal, V cos} (t) ... position detection _{signal, V sin} (t) ... position detection _{signal, V pwmnoise (t), V} noise (t), V noisetot (t) ... noise, V _pwm (t) ... _PWM driving signal, phi ... position detection value, omega _C ... resolver excitation frequency, ω _pwm ... _PWM driving _frequency, ω pwmnoise _... noise The wave _{number, ω pwmnoise, ω center, ω} noise ... noise frequency

Claims (2)

An excitation signal generating means for outputting a resolver excitation signal to a resolver for detecting a rotational angle position of the motor; a resolver / digital signal converting means for converting an analog position detection signal output from the resolver into a digital position detection value; In the position detection apparatus comprising: filter means for removing noise of the position detection value output from the resolver / digital signal conversion means; and drive signal output means for outputting a drive signal to the motor.
Drive frequency acquisition means for acquiring the drive frequency of the drive signal generated by the drive signal output means;
Noise frequency calculation means for calculating a noise frequency resulting from the drive frequency;
Noise blocking band setting means for setting a filter coefficient of the filter means so as to be able to block the noise frequency;
And a filter coefficient output means for outputting the filter coefficient set by the noise stop band setting means to the filter circuit. An excitation frequency acquisition means for acquiring a resolver excitation frequency of the resolver excitation signal generated by the excitation signal generation means;
The noise frequency calculation means calculates a noise frequency resulting from interference between the drive frequency and the resolver excitation frequency in addition to the noise frequency due to the drive frequency,
The noise stop band setting means uses the noise frequency resulting from the drive frequency, the noise frequency resulting from the interference between the drive frequency and the resolver excitation frequency, and the harmonic frequency thereof, and the filter coefficient of the filter circuit The position detection device according to claim 1, wherein:

Images