JP2012154890A - Resolver abnormality detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resolver abnormality detector having a simple and low-cost configuration, in which rotation angle detection and malfunction detection do not have an influence on each other.SOLUTION: An AC component of a substantially sinusoidal test signal with the higher harmonic wave component removed at a zero-cross timing that the voltage differences across detection coils 12, 13 of a resolver 1 become zero is added to one ends of the detection coils 12, 13 via resistors Rs1, Rs2. Inductance values of the detection coils 12, 13 are obtained from the values at the zero-cross timing of the output obtained by differential amplification of the voltage differences across the detection coils 12, 13, and malfunction of the resolver 1 is detected from these inductance values.

Description

  The present invention relates to a resolver abnormality detection device that detects an abnormality of a resolver used as a rotation angle detection sensor of a rotor such as a brushless motor.

  In general, a resolver is known as a sensor for detecting a rotation angle of a rotor such as a brushless motor. Hereinafter, the general configuration and operation of this resolver will be outlined according to the block diagram of FIG. 4 and the timing chart of FIG.

  As shown in FIG. 4, the resolver 1 includes an excitation coil 11, a SIN detection coil 12 that detects a SIN value (sine value) of a rotation angle, and a COS detection coil 13 that detects a COS value (cosine value) of the rotation angle. And a rotor 14 that rotates integrally with a shaft of a brushless motor (not shown). The excitation coil 11, the SIN detection coil 12, and the COS detection coil 13 are transformer-coupled via a rotor 14. When the excitation signal Ve of AC voltage shown in FIG. An alternating current signal having an amplitude corresponding to the transformer-coupled transformation ratio is output to both ends of 12 and the COS detection coil 13. Therefore, by making the outer periphery of the rotor 14 have a predetermined shape corresponding to the rotation angle of the brushless motor, the SIN value of the rotation angle is output to both ends of the SIN detection coil 12 as shown in FIG. A COS value of the rotation angle is output to both ends of the detection coil 13 as shown in FIG.

  If the voltage difference between both ends of the SIN detection coil 12 is differentially amplified by the SIN differential amplifier 2, the SIN value of the rotation angle of the brushless motor can be obtained by subtracting the valley value from the peak value of the output. If the voltage difference between both ends of the detection coil 13 is differentially amplified by the COS differential amplifier 3 and the valley value is subtracted from the peak value of the output, the COS value of the rotation angle of the brushless motor can be obtained. The rotation angle is obtained from an inverse function (arcTAN) of TAN (tangent) obtained by dividing the SIN value by the COS value. Note that the peaks and valleys of the output are indicated by circles in FIG.

  Next, general current control of a brushless motor using the resolver 1 will be outlined according to the block diagram of FIG. In the figure, reference numeral 4 denotes a brushless motor, and reference numeral 5 denotes a control device thereof. The control device 5 includes an inverter circuit 51 that drives the brushless motor 4, a gate drive circuit 52 that drives the gate of an FET (field effect transistor) that constitutes the inverter circuit 51, and a current detection resistor R provided in the inverter circuit 51. The current detection circuit 53 detects the current of each phase of the brushless motor 4 and the microcomputer 54 controls the energization current of the brushless motor 4.

  The microcomputer 54 reads the current of each phase of the brushless motor 4 detected by the current detection circuit 53 by the A / D converter B1, and detects the rotation angle of the brushless motor 4 provided in the brushless motor 4. The output of the resolver 1 is read, and the rotation angle is calculated by the rotation angle calculation means B2. The calculation method of the rotation angle is as described above with reference to FIGS.

  Next, the q-axis current calculation means B3 calculates the q-axis current based on a predetermined arithmetic expression from the current value and rotation angle of each phase read in advance. Here, the q-axis current is a current obtained by combining the currents of the respective phases based on the rotation angle, and the output torque of the brushless motor 4 is proportional to the q-axis current.

Next, in the current control means B4, a voltage command for driving the brushless motor 4 so that the set target current input from the outside matches the q-axis current previously obtained by the q-axis current calculation means B3. Calculate the value. Next, the three-phase voltage command calculation means B5 calculates a three-phase voltage command value to be added to each phase of the brushless motor 4 from the voltage command value and the rotation angle.

  Next, the PWM pulse generating means B6 generates a PWM pulse to be applied to the three phases according to the three-phase voltage command value. The inverter circuit 51 is driven by this PWM pulse through the gate drive circuit 52 and energizes the brushless motor 4. As described above, the brushless motor 4 is energized with a current according to the target current set from the outside.

  Next, the PWM pulse generation method in the PWM pulse generation means B6 will be outlined according to the timing chart of FIG. The microcomputer 54 includes a PWM timer that generates a triangular wave, and generates a PWM pulse by comparing the generated value of this PWM timer with the voltage command value obtained by the three-phase voltage command calculation means B5. By increasing or decreasing the voltage command value, the duty of the PWM pulse applied to the brushless motor 4 is controlled, and a desired current is supplied to the brushless motor 5. Here, the frequency of the PWM timer, that is, the frequency of the PWM pulse is set to 20 KHz, for example.

  As described above, the resolver 1 detects the rotation angle of the brushless motor 4 and is used for current control of the brushless motor 4.

  By the way, the technique disclosed in Patent Document 1 is known as an apparatus that detects an abnormal state when a disconnection or a short circuit of a detection coil occurs in a resolver that detects a rotation angle of a brushless motor.

JP 2009-162670 A

  The technique disclosed in the above-mentioned Patent Document 1 superimposes an AC signal for abnormality detection on one end of a detection coil and observes this AC signal at the other end of the detection coil, thereby disconnecting or short-circuiting the detection coil of the resolver. It is intended to detect abnormal states such as. That is, when an abnormality occurs in the detection coil of the resolver, the AC signal superimposed on one end of the detection coil is not normally transmitted to the other end. It is to detect.

  However, in this conventional technique, an alternating current signal for detecting an abnormality is constantly superimposed, so that there is a problem that it is difficult to completely separate an alternating excitation signal for detecting a rotation angle and an alternating current signal for detecting an abnormality. . Further, if measures are taken to stop the AC signal for abnormality detection in a specific section in order to avoid this, the circuit configuration becomes complicated and the signal processing becomes complicated.

  Further, according to this prior art, since an AC signal for detecting an abnormality is observed at the other end of the coil, there is a problem that a new input unit is required in addition to the input unit necessary for detecting the rotation angle.

  The present invention has been made to eliminate these problems of the prior art, and an object of the present invention is to provide a resolver in which rotation angle detection and abnormality detection do not affect each other with a simple and inexpensive circuit configuration. An object of the present invention is to provide an abnormality detection device.

A resolver abnormality detection device according to the present invention is a resolver abnormality detection device for detecting an abnormality of a resolver that detects a rotation angle of a rotor, and a test pulse at a timing when a voltage difference between both ends of a detection coil of the resolver becomes zero. A test pulse generating means for generating a test signal, a filter for removing harmonic components from the test pulse generated by the test pulse generating means to generate a substantially sinusoidal test signal, and an AC component of the test signal generated by the filter Is applied to one end of the detection coil via a predetermined resistor, a differential amplifier that differentially amplifies the voltage difference between both ends of the detection coil, and the output of the differential amplifier is matched to the timing of the test pulse. The A / D converter for A / D conversion and the resolution when the conversion value of the A / D converter is not within a predetermined range of a predetermined value. In which is provided with, abnormality detecting means for judging as abnormal.

  According to the present invention, the abnormality is detected from the value at the timing of the zero crossing of the output of the differential amplifier for detecting the rotation angle, so there is no need for a new input means for detecting the abnormality, A simple and inexpensive circuit can be configured, and a substantially sinusoidal test signal from which harmonic components have been removed at the timing of zero crossing when the voltage difference across the detection coil is zero is added via a predetermined resistor in an alternating manner. Therefore, it is possible to provide a resolver abnormality detection device in which the detection of the rotation angle and the abnormality detection do not affect each other.

It is a block diagram which shows the structure of the resolver abnormality detection apparatus which concerns on Embodiment 1 of this invention. It is a timing chart which shows operation | movement of the resolver abnormality detection apparatus which concerns on Embodiment 1 of this invention. It is a block diagram explaining the abnormality detection method of the solver by the resolver abnormality detection apparatus concerning Embodiment 1 of this invention. It is a block diagram which shows the general structure and operation | movement of a resolver. It is a timing chart which shows the general operation | movement of a resolver. It is a block diagram which shows the current control of the brushless motor by a conventional apparatus. It is a timing chart which shows the operation | movement of the PWM pulse generation by a conventional apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a resolver abnormality detection device according to the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to this embodiment, and includes various design changes.

Embodiment 1.
The resolver abnormality detection apparatus according to Embodiment 1 of the present invention will be described below. FIG. 1 is a block diagram showing a configuration of a resolver abnormality detection device according to Embodiment 1, and FIG. 2 is a timing chart showing its operation. In FIG. 1, the same reference numerals as those in FIG. 4 or FIG. 6 describing the prior art indicate the same or corresponding parts.

The microcomputer 54 generates an excitation pulse with a duty ratio of 50% for exciting the excitation coil 11 of the resolver 1 at the excitation pulse generating means B7. The excitation pulse indicated by B in FIG. 2 is generated in synchronization with the output of the PWM timer B8, as described above with reference to FIG. FIG. 2 shows a case where an excitation pulse is obtained by dividing the period of the PWM timer B8 indicated by A by half. By removing harmonic components from the excitation pulse through a two-stage CR filter 20 composed of a resistor and a capacitor, a substantially sinusoidal excitation signal shown in FIG. 2D is generated. The AC component of this excitation signal is applied to the excitation coil 11 of the resolver 1 through a buffer circuit 21 composed of an operational amplifier and a capacitor. Thus, the influence of noise generated by the PWM pulse can be avoided by generating the excitation signal in synchronization with the PWM timer B8.

  Next, the test pulse generating means B9 of the microcomputer 54 generates a test pulse for detecting an abnormality of the resolver 1 as shown in FIG. 2C by the detection coil (SIN detection coil 12 and COS detection coil of the resolver 1). 13) is generated at the timing when the voltage difference between both ends becomes zero, that is, at the timing of zero crossing. Then, a harmonic signal is removed from the test pulse by the two-stage first CR filter 22 and the second CR filter 23 composed of a resistor and a capacitor to obtain a test signal indicated by E in FIG. The AC component is applied to the SIN detection coil 12 through the resistor Rs1, and is applied to the COS detection coil 13 through the resistor Rs2. Here, assuming that the width of the test pulse is Tp, the waveform of the test signal corresponds to a half of the waveform of a sine wave signal having a period of about twice the time Tp as one cycle as shown in E of FIG. It becomes the shape to do. That is, it has a shape corresponding to a waveform of a half section of a high-frequency sine wave signal whose frequency Ftp is the reciprocal of 2Tp.

  Here, the first CR filter 22 and the second CR filter 23 function in the same way, and are driven by one test pulse output from the microcomputer 54, and the first CR filter 22 detects the SIN. A test signal is applied to the coil 12, and the second CR filter 23 applies a test signal to the COS detection coil 13.

  Next, the output of the SIN differential amplifier 2 by adding the above test signal will be described. With reference to the negative input of the SIN differential amplifier 2, a voltage obtained by dividing the test signal by the resistor Rs1 and the inductance Ls1 of the SIN detection coil 12 is applied to the positive side. As described above, since the frequency of the test signal is equivalent to Ftp, the divided voltage Vs1 is given by the following equation.

  Since the voltage obtained by amplifying the divided voltage Vs1 by a predetermined factor is output to the output of the SIN differential amplifier 2, this output is proportional to the inductance Ls1 of the SIN detection coil 12.

  In the above description, the SIN detection coil 12 and the SIN differential amplifier 2 have been described. Similarly, the COS detection coil 13 and the COS differential amplifier 3 also include the inductance of the COS detection coil 13 at the output of the COS differential amplifier 3. A voltage proportional to Ls2 is obtained.

  2 is output to the output of the SIN differential amplifier 2 and the output of G in FIG. 2 is output to the output of the COS differential amplifier 3. The signal shown in FIG. The microcomputer 54 A / D-converts the output of the SIN differential amplifier 2 at the above-described peak timing to obtain the peak value of the SIN value, as indicated by a circle in F of FIG. A / D conversion is performed at the timing of the valley to obtain the valley value of the SIN value, and A / D conversion is performed at the timing of the zero crossing to obtain a result value by the test signal. Similarly, as indicated by a circle in G of FIG. 2, the output of the COS differential amplifier 3 is A / D converted at the above-described peak timing to obtain the peak value of the COS value. A / D conversion is performed at the timing to obtain a valley value of the COS value, and A / D conversion is performed at the timing of the zero cross to obtain a result value by the test signal.

Here, the amplitude of the SIN value obtained by subtracting the valley value of the SIN value from the peak value of the SIN value changes in a SIN shape according to the rotation angle of the brushless motor (not shown), and the peak value of the COS value The amplitude of the COS value obtained by subtracting the COS value valley from the value changes in a COS shape according to the rotation angle of the brushless motor. The rotation angle of the brushless motor is calculated based on the above-mentioned graph based on the SIN value peak value, the SIN value valley value, the COS value peak value, and the COS value valley value acquired by A / D conversion. It is calculated by the procedure described in 4. FIG. 2 shows a state in which the positive and negative polarities of the amplitudes of the SIN value and the COS value are reversed, for example, when the rotation angle is 45 degrees.

  Next, the abnormality detection of the resolver 1 by the test signal will be described. Now, when an abnormality such as disconnection or short circuit occurs in the SIN detection coil 12 of the resolver 1 or its wiring, the inductance Ls1 of the SIN detection coil 12 viewed from the SIN differential amplifier 2 is different from the normal value. Become. For example, when the wire is broken as indicated by an X mark in FIG. 3A, the inductance viewed from the SIN differential amplifier 2 is in an open state, so that the SIN differential amplifier 2 has a zero cross timing. A larger voltage than normal is output. For example, as shown in FIG. 3B, when a short circuit occurs between both ends or a part of the SIN detection coil 12, the inductance viewed from the SIN differential amplifier 2 is smaller than that in a normal state. Therefore, a voltage smaller than that in the normal state is output to the output of the SIN differential amplifier 2 at the zero cross timing. In the above description, the SIN detection coil 12 has been described, but the same applies to the COS detection coil 13.

  The microcomputer 54 performs A / D conversion on the outputs of the SIN differential amplifier 2 and the COS differential amplifier 3 by the first and second A / D converters B10 and B11 at the timing of the zero crossing, and detects abnormality. In B12 or abnormality detection means B13, it is determined that the resolver 1 is abnormal when the value is not within the range of a predetermined value that can be taken at normal time, and the motor drive stop determination means B14 determines the subsequent brushless motor. Stop driving.

  In the above description, the conversion timing of the first and second A / D converters B10 and B11 is given by the A / D timing generation means B15. The A / D timing generation means B15 operates in synchronism with the PWM timer B8 described above, and A / D conversion is performed at the timing of the peak, the timing of the valley, and the timing of the zero cross, and in accordance with each timing. The outputs of the SIN differential amplifier 2 and the COS differential amplifier 3 are A / D converted and captured. As described above, the influence of noise caused by the PWM pulse can be avoided by performing the A / D conversion timing in synchronization with the PWM timer B8.

  In the description based on FIG. 1, only the abnormality detection of the resolver 1 has been described. However, the general current control of the brushless motor is as described in FIG. 6.

  As described above, the rotation angle is calculated from the A / D conversion value obtained at the peak timing and the A / D conversion value obtained at the valley timing, whereas the test signal is in a short interval of zero crossing. Therefore, this test signal does not affect the detection of the rotation angle.

  Conversely, the addition of the test signal and the abnormality determination of the resolver 1 based on the addition of the test signal are performed at the timing when the voltage difference between both ends of the SIN detection coil 12 and the COS detection coil 13 by the excitation signal becomes zero. It is not affected by the excitation signal for angle detection.

  As described above, according to the resolver abnormality detection device according to the first embodiment, harmonic components are removed at the timing of zero crossing when the voltage difference between both ends of the detection coils 12 and 13 of the resolver 1 becomes zero. An AC component of a substantially sinusoidal test signal is added to one end of the detection coils 12 and 13 via the resistors Rs1 and Rs2, and the output zero cross obtained by differentially amplifying the voltage difference between both ends of the detection coils 12 and 13 is obtained. Since the inductance of the detection coils 12 and 13 is obtained from the value at the timing of this, and the abnormality of the resolver 1 is detected from the value of this inductance, rotation angle detection and abnormality detection with a simple and inexpensive circuit configuration It is possible to provide a resolver abnormality detection device that does not affect each other.

DESCRIPTION OF SYMBOLS 1 Resolver 2 SIN differential amplifier 3 COS differential amplifier 4 Brushless motor 5 Control apparatus 11 Excitation coil 12 SIN detection coil 13 COS detection coil 14 Rotor 20 CR filter 21 Buffer circuit 22 1st CR filter 23 2nd CR filter 51 Inverter circuit 52 Gate drive circuit 53 Current detection circuit 54 Microcomputer B1 A / D converter B2 Rotation angle calculation means B3 q-axis current calculation means B4 Current control means B5 Three-phase voltage command calculation means B6 PWM pulse generation means B7 Excitation pulse generation Means B8 PWM timer B9 Test pulse generation means B10 First A / D converter B11 Second A / D converter B12, B13 Abnormality detection means B14 Motor drive stop determination means B15 A / D timing generation means R Current detection resistance

Claims (6)

A resolver abnormality detection device that detects an abnormality of a resolver that detects a rotation angle of a rotor,
Test pulse generating means for generating a test pulse at a timing when the voltage difference between both ends of the detection coil of the resolver becomes zero;
A filter that removes harmonic components from the test pulse generated by the test pulse generating means to generate a substantially sinusoidal test signal;
Means for applying an alternating current component of the test signal generated by the filter to one end of the detection coil via a predetermined resistance;
A differential amplifier for differentially amplifying a voltage difference between both ends of the detection coil;
An A / D converter for A / D converting the output of the differential amplifier in accordance with the generation timing of the test pulse;
An abnormality detecting means for determining that the resolver is abnormal when the conversion value of the A / D converter is not within a predetermined value range;
A resolver abnormality detection device comprising: A resolver abnormality detection device that detects an abnormality of a resolver that detects a rotation angle of a rotor,
Test pulse generating means for generating a test pulse at a timing when a voltage difference between both ends of the sine detection coil for detecting the sine value of the rotation angle and the cosine detection coil for detecting the cosine value becomes zero;
A filter that removes harmonic components from the test pulse generated by the test pulse generating means to generate a substantially sinusoidal test signal;
Means for applying an alternating current component of the test signal generated by the filter to one end of the sine detection coil via a predetermined resistance;
A sine differential amplifier that differentially amplifies the voltage difference between both ends of the sine detection coil;
An A / D converter for A / D converting the output of the sine differential amplifier in accordance with the generation timing of the test pulse;
An abnormality detecting means for determining that the resolver is abnormal when the conversion value of the A / D converter is not within a predetermined value range;
A resolver abnormality detection device comprising: A resolver abnormality detection device that detects an abnormality of a resolver that detects a rotation angle of a rotor,
Test pulse generating means for generating a test pulse at a timing when a voltage difference between both ends of the sine detection coil for detecting the sine value of the rotation angle and the cosine detection coil for detecting the cosine value becomes zero;
A filter that removes harmonic components from the test pulse generated by the test pulse generating means to generate a substantially sinusoidal test signal;
Means for applying an alternating current component of the test signal generated by the filter to one end of the cosine detection coil via a predetermined resistance;
A cosine differential amplifier for differentially amplifying a voltage difference between both ends of the cosine detection coil;
An A / D converter for A / D converting the output of the cosine differential amplifier in accordance with the generation timing of the test pulse;
An abnormality detecting means for determining that the resolver is abnormal when the conversion value of the A / D converter is not within a predetermined value range;
A resolver abnormality detection device comprising: A resolver abnormality detection device that detects an abnormality of a resolver that detects a rotation angle of a rotor,
Test pulse generating means for generating a test pulse at a timing when a voltage difference between both ends of the sine detection coil for detecting the sine value of the rotation angle and the cosine detection coil for detecting the cosine value becomes zero;
First and second filters for removing harmonic components from the test pulse generated by the test pulse generating means to generate a substantially sinusoidal test signal;
Means for applying an alternating current component of the test signal generated by the first filter to one end of the sine detection coil via a predetermined resistance;
Means for applying an alternating current component of the test signal generated by the second filter to one end of the cosine detection coil via a predetermined resistance;
A sine differential amplifier that differentially amplifies the voltage difference between both ends of the sine detection coil;
A cosine differential amplifier for differentially amplifying a voltage difference between both ends of the cosine detection coil;
A first A / D converter for A / D converting the output of the sine differential amplifier in accordance with the generation timing of the test pulse;
A second A / D converter for A / D converting the output of the cosine differential amplifier in accordance with the generation timing of the test pulse;
An abnormality detection means for determining that the resolver is abnormal when the conversion value of the first and / or second A / D converter is not within a predetermined value range;
A resolver abnormality detection device comprising:   The resolver abnormality according to any one of claims 1 to 4, wherein the rotor is a rotor of a brushless motor, and the test pulse is generated in synchronization with a PWM pulse applied to the brushless motor. Detection device.   The resolver abnormality detection device according to any one of claims 1 to 5, wherein the filter is a CR filter including two resistors and two capacitors.

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