JPH0419512A - Rotational angle detector - Google Patents

Abstract

PURPOSE:To attain inexpensive, fast high-accuracy measurement by non-sine wave driving by supplying a pulse signal to the other stator coil in response to the discriminator output of a decision means which indicates that a stable state is entered. CONSTITUTION:A CPU 1 applies the stators A and B of a resolver 4 with two pulses which have no overlap of ON time through driver circuits 2 and 3 and pulse signals EA and EB are inputted. Then pulse outputs eR1 and eR2 corresponding to the input pulses EA and EB are outputted from the rotor of the resolver 4 while having an amplitude corresponding to the angle of the rotor and inputted to the CPU 1 through an output circuit 5 and an A/D converter 6. The CPU 1 supplies the pulse signal EA to the stator A first, finds the difference between the last and current outputs of the rotor 4 at intervals of sampling, and supplies the pulse signal to the stator B through the driver 3 when the difference decreases below a specific value and the stable state is discriminated. The CPU 1 calculates the angle theta of rotation of the rotor 4 from the amplitudes of the pulse signals eR1 and eR2 and outputs angle data.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application This invention relates to a rotation angle detection device using a rotation angle detection resolver having one rotor winding and two stator windings.

(B) Prior Art Conventionally, when a resolver is used as an angle detector, it is provided with two stator windings 13.14 as shown in FIG. 90° electrical angle
An excitation current is supplied by supplying two-phase sine waves with different phases, and the phase difference θ between the output induced in one rotor winding 15 and the excitation signal is determined, and this phase angle θ is taken as the rotation angle. There is. A conventional rotation angle detection device that employs sine wave excitation is shown in FIG. This rotation angle detection device uses an oscillator 2
1, a frequency dividing circuit 22 which divides the frequency in response to a pulse from the oscillator 21, a start timing generation circuit 23, and an S signal in synchronization with the signal from the start timing generation circuit 23.
A SIN wave generation circuit 24, a cosine wave generation circuit 25, and a driver circuit 26, each generating an IN wave and a CO3 wave.
27, a resolver 28, an output circuit 29 that derives the rotor output of the resolver 28, a low-pass filter 30 that removes harmonic components of the output, a comparator 31 that detects the zero cross point, and a , a counter 32 that counts pulse signals from the frequency dividing circuit 22 until a stop signal is input by detecting a zero cross point, and a CPU 33.

(c) Problems to be Solved by the Invention The conventional rotation angle detection device described above uses a sine wave excitation signal and therefore requires a SIN wave generation circuit and a CO3 wave generation circuit. In order to generate a sine wave, a large number of components are required, resulting in an expensive device.

If a non-sinusoidal wave that is easily generated, such as a square wave, is used as the excitation current source, the measurement error will increase due to the harmonics contained in it.In order to eliminate this harmonic error, - Low-pass filter for boat fishing use. However, in order to pass the fundamental wave and sufficiently cant the third harmonic (approximately 40 dB in terms of voltage ratio), it is necessary to use a multi-stage active filter or LC filter with a large cutoff slope, resulting in a complicated configuration. Furthermore, considering the temperature characteristics, the temperature characteristics of the phase change at the fundamental frequency are also within the operating temperature range (for example, 0°C to 50°C).
``C) requires a design that suppresses the angle measurement accuracy to less than 0.5 degrees, and since the filter is configured with elements with very little temperature change, the device becomes expensive.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a rotation angle detection device that is inexpensive and capable of high-speed, high-precision measurement in non-sinusoidal drive.

(d) Means and operation for solving the problems The rotation angle detection device of the present invention includes a rotation angle detection resolver having one rotor winding and two stator windings, and a rotation angle detection resolver having one rotor winding and two stator windings. a pulse generator that supplies pulse signals whose ON times do not overlap with each other; an A/D converter that converts the output of the rotor winding into a digital signal; and a pulse signal that corresponds to the pulse signal from the A/D converter. and a calculation means for calculating the rotation angle of the resolver from the amplitude value of the output pulse, in which the output of the rotor winding is controlled while the pulse signal is energized from the pulse generator to one of the stator windings. A determining means is provided for determining whether the stator has reached a stable state, and a pulse signal is supplied to the other stator winding based on the determination output of the determining means indicating that the stable state has been reached.

In this rotation angle detection device, a pulse generated by a pulse generator is supplied to one stator winding, and the stator winding is energized. Then, an output voltage corresponding to the amplitude of the pulse and the angle of the rotor is derived to the rotor, converted into a digital signal by the A/D conversion means, and taken into the calculation means and discrimination means.

For example, the determining means determines whether the difference between the previous value and the current value has become less than a predetermined value, and when the difference has become less than the predetermined value, it is assumed that the output has reached stability, and the pulse generator outputs the second pulse signal. , which is now supplied to the other stator. As a result, an output voltage corresponding to the amplitude of the pulse to the stator and the angle of the rotor is similarly derived to the rotor, and the A/D
After passing through the conversion means, it is taken into the discrimination means and the calculation means,
When the determining means determines that the output has reached a stable state, the calculating means calculates the rotation angle by inverse trigonometric calculation based on the amplitude value of the pulse signal and the like.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 2 is a block diagram of a rotation angle detection device showing an embodiment of the present invention. In the same figure, ON from the CPUI
Two pulses whose times do not overlap are applied to stator A (stator) and stator B of resolver 4 through driver circuits 2.3, respectively. The pulse signals EA and Es inputted to the stators A and B are as shown in FIG. 3, and the pulse outputs e1 and eR2 corresponding to the input pulses Ea-Es from the rotor of the resolver 4 are It is output with an amplitude according to the angle, and the output circuit 5, A
/D converter 6 and is taken into the CPUI.

In the CPU, first, a pulse signal Ea is applied to the stator A, and the difference between the previous and current outputs of the captured rotor output is determined for each sampling. When the difference is less than a predetermined value and it is determined that the output is stable, the driver 3 It has a function of supplying a pulse signal to stator B via. This will be discussed later. The CPUI receives the captured pulse signal eRI
It has a function of calculating the rotation angle θ of the rotor from the amplitude of seRZ, and outputs angle data.

In this embodiment of the rotation angle detection device, when a pulse waveform of amplitude eA is applied to the stator A of the resolver 4, the output voltage E of the rotor synchronized with this input pulse changes with the amplitude of eu+=k HeAHsinθ・(1) Similarly, when a pulse with an amplitude e is applied to the stator B of the resolver 4, the output voltage ER of the rotor changes with an amplitude of eiz=kHeH-CO3θ-(2) (see FIG. 4). Here, k is the coupling coefficient of the resolver.

Therefore, the output E,l of the rotor is el due to the angle θ.
It becomes lls eRZ. These pulse outputs are
ea+□ is sampled by the A/D converter 6, converted into a digital signal, and taken into the CPUI.

From the captured data eR1 and eRZ, the CPUI
Calculate θ by performing the following calculation.

-eA ke-e.

Calculating the angle θ can be done using either equation (3) or (4) above, but if only one is calculated, A/
It is necessary to make the resolution of the D converter 60 very fine. Therefore, the angle θ is O~π/4.3π/4~5π/4.7π
/4~2π is equation (3), and the angle θ is π/4~3π/
If 4.5π/4 to 7π/4 is calculated using formula (4), A
Even if the resolution of the /D converter 6 is relatively low, a highly accurate angular output can be obtained.

In addition to the above equations (3) and (4), the calculation of the following equation can be performed using C
The angle θ can be determined by using the PUI.

al12'eA In this embodiment of the rotation angle detection device, before calculating the angle using the above formula (3) or (4)2, for example, sampling is performed several times to capture the rotor output.
11 and e□7. The difference is calculated each time, and when the difference value becomes less than a predetermined value, it is assumed that the output is stable, and the captured value is used for angle calculation. This is because it is better to consider the time required for the rotor output to stabilize due to the inductance of the resolver, the capacitance component of the resolver cable, etc. This is because, particularly when measuring angles with high precision, it is necessary to measure while the rotor output is sufficiently stable.

However, if you take the time to stabilize more than necessary when measuring, the measurement time will become longer.

Next, the operation of the rotation angle detection device of the above embodiment will be explained according to the flowchart shown in FIG. At the start of operation, first, EA supplied to stator A is turned on [step ST (hereinafter abbreviated as ST) 1]. At that time, the output circuit 5, A/
The output eR1 of the rotor A taken in from the D converter 6 is
Store as e*xn-1 (Sr1). Next, the rotor output eRI taken in at the next sampling time is stored as e□(n) (5T3), and it is determined whether the absolute value of the difference between the two is smaller than a predetermined value (5T4). If it is not small, it is assumed that the output is unstable and the current rotor output e R1 (nl is changed to the previous value e
R1 (memorized as n-11, 5T5), at the next sampling time, captures the rotor output eR1 again, and eR
l (nl) (Sr3). Then, it is determined whether the absolute value of the difference value between this time and the previous time is smaller than a predetermined value (Sr1). If not, the output is still unstable and is stored as Sr3. - Repeat the process of ST5.

In Sr1, l eRl<n-1, eRl(++l l
If <D, assuming that the rotor output is stable, the EA applied to the stator A is turned on to 0FFL (Sr6), and the E applied to the stator B is turned on (Sr1). Next, measure the output eゎ of rotor B, and the previous measurement value eR□,
-1, (Sr1). The outputs e and l□ of rotor B measured at the arrival of the next sampling time are now:
This time value e RZ (remember as ++1 5T9)
, it is determined whether the absolute value of the difference between the previous and current values exceeds a predetermined value (STIO). If the absolute value of the difference value is larger than the predetermined value, it is assumed that the output is unstable, and the process moves to STI 1, where the current data eR2(n) is converted to the previous data eR(□
-1. Furthermore, when the next sampling time arrives, the current measurement value ERZ is obtained and stored as e RZ (+s) (5TII), and the processes of ST7 to STII are repeated. Regarding the output ei+z of rotor B, if the absolute value of the difference value is smaller than the predetermined value, this means that the output has stabilized, and if the judgment is YES in 5TIO, the process moves to 5T12.
e114(n) -ea is calculated, the angle θ is calculated, and the angle data is output to the outside (5T13) or displayed on a display.

(F) Effects of the Invention According to this invention, two pulse signals whose ON times do not overlap are applied to the stator windings of the resolver, and the angle is determined by the amplitude of each input pulse output to the rotor. Since the rotation angle is calculated by applying and exciting a sine wave to a resolver as in the past, an excitation wave with accurate timing is not required and the excitation wave can be easily generated. Even if harmonics are included in the rotor winding output, accuracy is not affected, so an expensive low-pass filter is not required, and the entire device can be realized easily and inexpensively.

Also, after it is determined that the output of the rotor winding has reached a stable state by applying a pulse signal to one of the stator windings,
Since the pulse signal is applied to the next stator winding, measurement can be performed at the optimum time even if the rotor output stabilization time changes due to cable extension, etc., making it possible to perform high-speed, high-precision measurements. Become.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram for explaining the operation of a rotation angle detection device according to an embodiment of the present invention, FIG. 2 is a block diagram of the rotation angle detection device according to the embodiment, and FIG. 3 is a rotation angle detection device according to the embodiment. An input/output waveform diagram for explaining the operation of the device, FIG. 4 is a waveform diagram showing the relationship between the rotation angle of the rotor and the output of the rotation angle detection device, and FIG. 5 shows the principle configuration of the resolver. figure,
FIG. 6 is a waveform diagram showing excitation signals and output signals of a conventional rotation angle detection device using the same resolver, and FIG. 7 is a block diagram showing the circuit configuration of the conventional rotation angle detection device. 1: CPU, 2/3: Driver circuit, 4:
Resolver, 6: A/D converter, 13/14:
Stator, 15: Rotor. Patent applicant OMRON Co., Ltd. agent
Patent Attorney Shigeru Nakamura

Claims (1)

[Claims] (1) a rotation angle detecting resolver having one rotor winding and two stator windings; a pulse generator supplying pulse signals whose ON times do not overlap with each other to the two stator windings; A/D conversion means for converting the output of the rotor winding into a digital signal, and calculation means for calculating the rotation angle of the resolver from the amplitude value of the output pulse corresponding to the pulse signal from the A/D conversion means. The rotation angle detection device includes a determining means for determining that the output of the rotor winding has reached a stable state while a pulse signal is being applied to one of the stator windings from the pulse generator. A rotation angle detection device comprising: a determination output of the determination means indicating that a stable state has been reached, and a pulse signal is supplied to the other stator winding.