JP2013127409A - Waveform measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waveform measuring instrument capable of directly measuring a waveform of an angle of rotation on the basis of a measurement result of a resolver.SOLUTION: The waveform measuring instrument includes a zero-cross detection unit which detects a rising zero crossing of an excitation signal input to the resolver, a holding unit which holds an angle detection signal varying in amplitude with an angle of rotation output by the resolver after Δt, which is a quarter as large as a period of the excitation signal, after the zero crossing is detected, and an angle arithmetic unit which calculates the angle of rotation on the basis of the held angle detection signal.

Description

  The present invention relates to a measuring instrument, and more particularly, to a waveform measuring instrument that measures a rotational angle waveform based on a detection signal output from a resolver.

  As represented by hybrid vehicles and electric vehicles, motors are widely used as drive sources. Since it is necessary to detect the rotation angle for controlling the motor, a rotation angle sensor has been conventionally used.

  The types of rotation angle sensors include optical and magnetic rotary encoders, resolvers that use electromagnetic induction, etc., but they are environmentally resistant in environments where dust or oil mist is bad or where the environment changes greatly. Conventionally, many resolvers characterized by excellent and stable high reliability have been used. In particular, in recent years, resolvers have been adopted as in-vehicle rotation angle sensors under severe environments such as temperature, humidity, vibration, and impact.

  FIG. 5 is a diagram for explaining the principle of the resolver. As shown in the figure, the resolver 200 includes a rotating excitation coil (rotor) 211 and two fixed detection coils (a first detection coil 230 and a second detection coil 240). The coil 230 and the second detection coil 240 are arranged so that the directions with respect to the excitation coil 211 are different by 90 degrees.

With this configuration, as shown in FIG. 7, when a sinusoidal excitation voltage signal _VE is applied to the excitation coil 211, when the rotation angle of the rotor (excitation coil) 211 is θ, the amplitude of the first detection coil 230 is It changes with sin θ, and the amplitude of the second detection coil 240 changes with cos θ shifted by 90 degrees. Therefore, the rotation angle θ of the rotor (excitation coil) 211 can be obtained by calculating the arc tangent of the value of sin θ obtained from the first detection signal and the value of cos θ obtained from the second detection signal.

  An apparatus for performing this calculation is called by various names such as “resolver-digital converter” and “angle converter”, but is hereinafter referred to as “resolver angle detection signal converter”. The resolver angle detection signal converter applies an excitation signal to the resolver 200, inputs the first detection signal and the second detection signal from the resolver 200, calculates the rotation angle θ, and outputs the rotation angle signal.

  The resolver angle detection signal converter drives the resolver 200 by outputting an excitation signal. The first detection signal is detected by synchronously detecting the first detection signal and the second detection signal using the excitation signal. In addition, the sin θ waveform and the cos θ waveform can be accurately extracted from the second detection signal.

JP 2007-315856 A

  When performing inspections or tests related to motor control, there are cases where it is desired to display the waveform of the rotation angle θ measured by the resolver 200 and calculated by the resolver angle detection signal converter. In order to display the waveform of the rotation angle θ, the rotation angle signal generated by the resolver angle detection signal converter may be input to the waveform measuring device.

  However, in recent years, an in-vehicle resolver angle detection signal converter 310 is often incorporated in an ECU (Engine Control Unit) 300 together with a motor controller 320 as shown in FIG. It has become difficult to take out. Moreover, the resolver angle detection signal converter 310 is often built in a chip such as a CPU other than the vehicle-mounted one, and it is difficult to take out the rotation angle signal alone.

  For this reason, it is desirable that the waveform measuring device can directly measure the waveform of the rotation angle based on the measurement result of the resolver 200. However, since the first detection signal and the second detection signal, which are measurement results of the resolver 200, include the excitation signal component that is a carrier wave, the waveform data of the rotation angle θ with high accuracy can be obtained simply by calculating the arc tangent. You can't get it.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a waveform measuring instrument that can directly measure a rotational angle waveform based on a measurement result of a resolver.

  In order to solve the above problems, the waveform measuring instrument of the present invention includes a zero-cross detection unit that detects a zero-cross of an excitation signal input to a resolver, and a rotation angle output by the resolver after Δt after the zero-cross is detected. And a holding unit that holds an angle detection signal whose amplitude changes in response, and an angle calculation unit that calculates the rotation angle based on the held angle detection signal.

  Here, the angle detection signal can be two signals whose amplitude changes by 90 degrees. At this time, the angle calculation unit can calculate the rotation angle by the arc tangent of the two held signals.

  The zero cross detector may detect a rising zero cross of the excitation signal, and the Δt may be 1/4 of the period of the excitation signal.

  At this time, a timing generation unit that calculates the period of the excitation signal based on the detected zero cross and sets the Δt may be further provided. The Δt may include an amount of phase shift between the excitation signal and the angle detection signal as an offset.

  Moreover, you may make it further provide the smoothing part which smoothes the time change of the rotation angle obtained by the said angle calculating part.

  ADVANTAGE OF THE INVENTION According to this invention, the waveform measuring device which can perform the waveform measurement of a rotation angle directly based on the measurement result of a resolver is provided.

It is a block diagram which shows the structure of the waveform measuring device which concerns on this embodiment. It is a flowchart explaining operation | movement of a waveform measuring device. It is a wave form diagram which shows a waveform when the rising zero cross of an excitation waveform is detected and a delay timing pulse is output after Δt time. It is a wave form diagram which shows the relationship between an excitation signal waveform and each signal waveform. It is a figure explaining the principle of a resolver. It is a figure explaining a resolver and a recent resolver angle detection signal converter. It is a wave form diagram explaining the principle of a resolver.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the waveform measuring instrument according to this embodiment. The waveform measuring instrument 100 includes an excitation signal output to the resolver 200 by an IC chip 320 such as an ECU incorporating the resolver angle detection signal converter 310, and a first detection signal and a second detection signal output from the resolver 200 to the IC chip 320. And the waveform of the rotation angle θ measured by the resolver 200 is measured.

  As shown in the figure, the waveform measuring instrument 100 includes a zero cross detection unit 110, a delay timing generation unit 120, an A / D conversion unit 130, a hold unit 140, an angle calculation unit 150, a smoothing unit 160, a memory controller 170, a waveform. A memory 180 and a timing unit 190 are provided.

  The zero cross detection unit 110 receives an excitation signal input to the resolver 200, detects a rising zero cross of the excitation signal, and outputs a zero cross detection signal to the delay timing generation unit 120.

  When the zero cross detection signal is input from the zero cross detection unit 110, the delay timing generation unit 120 outputs a delay timing pulse to the hold unit 140 at a timing after a predetermined Δt time. Here, Δt is T / 4 when the period of the excitation signal is T. In general, since the period T of the excitation signal in which the resolver angle detection signal converter 310 drives the resolver 200 is known, the user sets T / 4 in advance as Δt.

  However, the delay timing generator 120 measures the period T of the excitation signal based on the continuously input zero-cross detection signal, and sets T / 4 as Δt based on the measured period T. Also good.

  The A / D converter 130 receives the first detection signal and the second detection signal output from the resolver 200 and converts them into digital data. Each digital data is output to the hold unit 140. The sampling frequency of the A / D conversion unit 130 is assumed to be sufficiently higher than the frequency (1 / T) of the excitation signal. For example, when the frequency of the excitation signal is 10 kHz, the sampling frequency of the A / D conversion unit 130 is desirably about 10 MHz.

  When the delay timing pulse is input from the delay timing generator 120, the hold unit 140 latches the digital data of the first detection signal and the digital data of the second detection signal, and holds them until the next latch timing. The first detection signal hold data and the second detection signal hold data are input to the angle calculation unit 150.

  The angle calculation unit 150 calculates the rotation angle θ by performing an arctangent calculation of the input first detection signal hold data and second detection signal hold data. Since the rotation angle θ is calculated from the hold data, it becomes stepped waveform data. The rotation angle θ waveform data that changes in a staircase pattern. The data is input to the smoothing unit 160.

  The smoothing unit 160 smoothes the rotation angle θ waveform data calculated stepwise in the time direction. Thereby, the resolution of the rotation angle θ waveform data can be increased. The smoothing unit 160 can be configured using a tracking loop circuit, for example. The tracking loop circuit includes an integrator, a low-pass filter, and the like, and is a circuit that performs smoothing by digital signal processing.

  The memory controller 170 stores the rotation angle θ waveform data smoothed by the smoothing unit 160 in the waveform memory 180. The rotation angle θ waveform data stored in the waveform memory 180 can be output as measurement data to the outside of the measuring instrument or displayed on a display device (not shown) provided inside or outside the waveform measuring instrument 100.

  The timing unit 190 controls operation timings of the A / D conversion unit 130, the hold unit 140, the angle calculation unit 150, the smoothing unit 160, and the memory controller 170.

  Next, the operation of the waveform measuring instrument 100 configured as described above will be described with reference to the flowchart of FIG. When the waveform measuring instrument 100 starts measuring the waveform of the rotation angle θ, the zero cross detector 110 inputs the excitation signal input to the resolver 200 (S101), and the A / D converter 130 is output from the resolver 200. The first detection signal and the second detection signal are input (S102). The A / D converter 130 converts the input first detection signal and second detection signal into digital data.

  When the zero cross detection unit 110 detects the rising zero cross of the excitation waveform (S103: Yes), the zero cross detection signal is output to the delay timing generation unit 120, and the delay timing generation unit 120 delays a delay timing pulse at a timing after a predetermined Δt time. Is output to the hold unit 140 (S104).

  FIG. 3 is a waveform diagram showing waveforms when a rising zero cross of the excitation waveform is detected and a delay timing pulse is output after Δt time. As shown in this figure, when a rising zero cross of the excitation waveform is detected at time t0, a delay timing pulse is output at time t1 after Δt time.

  Since Δt is set to ¼ of the period T of the excitation waveform, the excitation waveform has a peak value at time t1 after Δt time from the rising zero cross. For this reason, at the time t1, both the value of the first detection signal and the value of the second detection signal become maximum values. That is, the values correspond to sin θ and cos θ.

  Based on the delay timing pulse output at time t1, the values of the first detection signal and the second detection signal corresponding to sin θ and cos θ are latched and held by the hold unit 140 (FIG. 2: S105). . Then, the angle calculator 150 calculates the rotation angle θ based on the values of the first detection signal and the second detection signal corresponding to sin θ and cos θ (S106).

  Since the calculated rotation angle θ becomes a stepped waveform held every time T, it is smoothed by the smoothing unit 160 (S107) and stored in the waveform memory 180 (S108). The waveform data of the rotation angle θ stored in the waveform memory 180 is read as necessary and displayed as a waveform.

  The process of detecting the rising zero cross of the excitation waveform (S103) and each process after detection (S104 to S108) are repeated until the waveform measurement is completed (S109: Yes). As a result, the values of the first detection signal and the second detection signal corresponding to sin θ and cos θ are held for each period of the excitation waveform, and the waveform data of the rotation angle θ is calculated based on these values. .

  FIG. 4 shows an excitation signal input to the resolver 200, a first detection signal and a second detection signal output from the resolver 200, a latched and held first detection signal and a second detection signal, and a stepwise rotation angle θ. It is a wave form diagram which shows the relationship between a waveform and the smoothed rotation angle (theta) waveform.

  As shown in the figure, since the first detection signal and the second detection signal are latched at the peak of the excitation waveform, the hold waveform represents a sin θ waveform and a cos θ waveform corresponding to the rotation angle θ. By calculating and smoothing the rotation angle θ based on the hold waveform, waveform data of the rotation angle θ can be obtained with high accuracy.

  Note that the zero-cross detection unit 110 may detect a falling zero-cross of the excitation waveform and output a zero-cross detection signal. Alternatively, both the rising zero cross and the falling zero cross may be detected and a zero cross detection signal may be output. In this case, the calculation rate of the rotation angle θ can be doubled, and the cutoff of the low-pass filter of the tracking loop circuit used as the smoothing unit 160 can be set on the high frequency side, so that the followability can be improved.

  In addition, Δt, which is the time from when the zero timing detection signal is input to when the delay timing generation unit 120 outputs the delay timing pulse, may not be exactly ¼ of the period T of the excitation signal.

  Further, when a phase shift occurs between the first detection signal and the second detection signal with respect to the excitation waveform, it is desirable to set Δt in consideration of the shift amount. In this case, the correction value for the deviation amount may be set as an offset, and ¼ of the period T may be set to Δt.

DESCRIPTION OF SYMBOLS 100 ... Waveform measuring device, 110 ... Zero cross detection part, 120 ... Delay timing generation part, 130 ... A / D conversion part, 140 ... Hold part, 150 ... Angle calculation part, 160 ... Smoothing part, 170 ... Memory controller, 180 ... Waveform memory, 190 ... Timing unit, 200 ... Resolver, 211 ... Excitation coil (rotor), 230 ... First detection coil, 240 ... Second detection coil, 300 ... ECU, 310 ... Resolver angle detection signal converter, 320 ... IC chip, 320 ... Motor controller

Claims (7)

A zero-cross detector that detects the zero-cross of the excitation signal input to the resolver;
A holding unit that holds an angle detection signal whose amplitude changes according to a rotation angle output by the resolver after Δt from the detection of the zero cross;
An angle calculator that calculates the rotation angle based on the held angle detection signal;
A waveform measuring instrument comprising:   The waveform measuring device according to claim 1, wherein the angle detection signal is two signals whose phases of amplitude change are shifted by 90 degrees.   The waveform measuring device according to claim 2, wherein the angle calculation unit calculates the rotation angle based on an arctangent of two held signals. The zero cross detector detects a rising zero cross of the excitation signal,
The waveform measuring instrument according to claim 1, wherein Δt is ¼ of the period of the excitation signal.   5. The waveform measuring instrument according to claim 4, further comprising a timing generator that calculates a period of the excitation signal based on the detected zero cross and sets the Δt.   6. The waveform measuring device according to claim 4, wherein the Δt includes an amount of phase shift between the excitation signal and the angle detection signal as an offset.   The waveform measuring device according to claim 1, further comprising a smoothing unit that smoothes a temporal change in the rotation angle obtained by the angle calculation unit.