JPH0528486Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a resolver-type rotation angle detection device that detects a rotation angle using a resolver.

[Prior Art] In recent years, resolvers have been widely used as devices that simultaneously detect rotational angle and rotational speed, especially for servo motors, and are said to be cheaper and more robust than conventional rotary encoders (pulse pickups). has advantages.

The principle of such a resolver will be briefly explained. In other words, a resolver has a stator and a rotor, and when a two-phase alternating current with a phase difference of 90° is passed through the two-phase windings of the stator, a phase-modulated sin (θ + θr) is induced in the rotor winding. Voltage is generated. Here, θr is the rotor rotation angle.

Then, by extracting the phase signal θr from this voltage signal sin(θ+θr), the rotor rotation angle θr can be detected, and by further differentiating this with time, dθr/dt
Therefore, the rotor rotation speed can be detected.

FIG. 3 shows an example of a conventional resolver type rotation angle detection device. In FIG. 3, 1 is a clock oscillator, 2 is a counter, and 3 is a circuit that generates two-phase AC outputs of sin θ and cos θ based on the incremental data (or decremental data) of the counter output. The switch pattern corresponding to the digital signal from counter 2 is pre-recorded in the form of a two-phase pulse width modulation (PWM) sine wave signal, and a decoder operates at high speed using PWM signals equivalent to sinθ and cosθ to form a PWM waveform. It consists of a switch circuit that outputs two-phase alternating current with a 90° phase difference. In this way, the two-phase AC generating circuit 3 consisting of the oscillator 1, the counter 2, and the decoder and switch circuit generates a two-phase AC current having a phase difference of 90° to excite the resolver. Configure the excitation circuit.

In addition, in FIG. 3, 5 is the resolver rotor 4.
This is an induced voltage signal detection line that detects a phase-modulated voltage induced in B (this resolver rotor 4B includes a rotating transformer).A waveform shaping circuit 6 is connected to this induced voltage signal detection line 5. There is. This waveform shaping circuit 6 shapes the phase-modulated sine wave sin (θ+θr) into a rectangular wave. A latch circuit 7 for detecting rotation angle θr information by latching the output digital value of is connected.

Note that 4A is a stator of a two-phase excitation type resolver.

Further, 8 is a microcomputer that takes in the rotation angle θr data from the latch circuit 7, takes out the rotation angle θr information as it is, and differentiates it with respect to time to obtain the rotation speed.

With the above configuration, from the two-phase AC generating circuit 3
When a two-phase alternating current (excitation wave) with a 90° phase difference is supplied to the resolver stator 4A, the resolver rotor 4
B is a signal sin whose phase is modulated by the rotation angle of the rotor.
(θ+θr) is induced as a feedback signal. Thereafter, the counter output θ is latched at the zero-crossing point of the feedback signal of this resolver, and the phase difference θr between the excitation waves sinθ, cosθ and the feedback wave sin (θ+θr) is converted into digital data from the latch circuit 7. Served. This θr data is taken in and differentiated by the microcomputer 8 to obtain the rotational speed, and is used as is for feedback of the rotational angle θr. For reference, the relationship between .theta., the edge of each wavelength of the feedback signal, and .theta.r is shown in time charts as shown in FIGS. 4a to 4c.

[Problems to be solved by the invention] However, in such a conventional resolver-type rotation angle detection device, only one wavelength of the feedback signal is detected.
The feedback data of rotation angle θr cannot be updated. Therefore, by increasing the excitation frequency,
It is conceivable to increase the feedback frequency, but this poses a problem in that the resolution of data obtained by counting the time width of the phase difference using a clock decreases.

The present invention was developed to solve these problems, and it is possible to increase the sampling frequency and improve control responsiveness and accuracy without reducing the resolution of the rotation angle of the resolver rotor. An object of the present invention is to provide a resolver type rotation angle detection device.

[Means for Solving the Problems] Therefore, the resolver-type rotation angle detection device of the present invention converts the AC voltage signal from the signal detection line for detecting the phase-modulated AC voltage induced in the resolver rotor into a rectangular shape. A waveform shaping circuit that shapes the wave signal is provided, and a trigger signal generation circuit that generates a trigger signal at each rise and fall of the rectangular wave signal from the waveform shaping circuit is provided, and the trigger signal is output. Calculating means is provided for calculating the rotation angle of the resolver rotor by taking in data every time the trigger signal is output, and the calculating means is provided with a pair of latching means that alternately latches data each time the trigger signal is output, and each of the above-mentioned latching means. error calculation means for calculating the rotation angle error of the resolver rotor from the data latched by the latch means; and subtracting the rotation angle error calculated by the error calculation means from one of the stored values of the latch means and outputting the result. It is characterized by comprising an error correction means and a switching means for alternately switching and outputting the output of the error correction means and the other output of the latch means.

[Operation] In the above-described resolver-type rotation angle detection device of the present invention, two-phase AC is supplied from the two-phase excitation circuit to the stator of the resolver, thereby outputting an induced AC voltage having rotor rotation angle information to the resolver rotor. However, this AC voltage is shaped into a rectangular wave signal by a waveform shaping circuit, and then this rectangular wave signal is input to a trigger signal generating circuit, and from this trigger signal generating circuit, a signal is generated at each rise and fall of the above rectangular wave signal. A trigger signal is output. The calculating means takes in data every time a trigger signal is issued and calculates the rotation angle of the resolver.

At this time, since there is a possibility that the output of the waveform shaping circuit and the output of the trigger signal generation circuit include a rotation angle error of the resolver rotor, the calculation means removes this rotation angle error. That is, the rotation angle error is calculated by the error calculation means from the data latched by a pair of latch means that alternately latches data each time a trigger signal is output, and the rotation angle error is calculated by the error correction means. minutes are subtracted from the stored value of one of the latching means. Thereafter, the switching means alternately outputs the output from the error correction means and the other output from the latch means.

[Embodiments of the Invention] The present invention will be specifically described below with reference to illustrated embodiments. Figures 1 and 2 show a resolver type rotation angle detection device as an embodiment of the present invention.
The figure is an electric circuit diagram showing the main part of the calculation means,
The figure is an electrical circuit diagram showing the overall configuration. First, in Figure 2, 1 is an oscillator, 2 is a counter, and 3
is a two-phase AC generation circuit, 4A is a resolver stator,
4B is a resolver rotor, 5 is an induced voltage signal detection line, and 6 is a waveform shaping circuit, which are similar to those explained in FIG. 3.

Incidentally, this device includes a trigger signal generation circuit 9 that generates a trigger signal (rising edge signal) at each rise and fall of the rectangular wave signal from the waveform shaping circuit 6. As the trigger signal generation circuit 9, for example, a combination of a differentiation circuit that differentiates the signal from the waveform shaping circuit 6 and an absolute value circuit that converts a negative signal into a positive signal is used.

Further, a latch circuit 10 is provided which latches the output data of the counter 2 every time the trigger output (rising edge output) of the trigger signal generation circuit 9 is generated. ) can be detected. Furthermore, the output of this latch circuit 10 is received and the latched data is θr or θr+π.
In order to recognize whether the rotation The speed dθr/dt is calculated, θr is calculated from rotation angle information θr + π, and this rotation angle θr
(This θr includes the rotation angle θr inputted from the latch circuit 10 and not subjected to calculation) is outputted as a feedback for the speed control system of the servo motor. That is, the latch circuit 10 and the microcomputer 11 constitute a calculation means that takes in data every time a trigger signal is output and calculates the rotation angle θr of the resolver rotor 4B.

By the way, the microcomputer 11 constituting the calculation means
As shown in FIG. 1, the latch means alternately latches the angle data A (θr, θr+π) from the latch circuit 10 every time the rectangular wave signal rises and falls, that is, every time the trigger signal is output. 1
2.13. Note that this latch means 1
The latch timings 2 and 13 are controlled by a timing signal from a delay means 20 that slightly delays the phase data B from the waveform shaping circuit 6.
As a result, the latch means 12 receives data θr+π.
Data θr is latched in the latch means 13, respectively.

Here, due to the offset of the waveform shaping circuit input, the difference in sensitivity between the rise and fall of the waveform shaping circuit 6, etc., the output of the waveform shaping circuit is accurately set at high level and low level every 180°, although it is actually very small. It may not be a square wave that corresponds to the level. In other words, the data latched at the edges of this waveform shaping circuit 6 is 360 degrees that is 180 degrees off from the true value θr, assuming that the data obtained at one edge every 360 degrees is the true value θr.
The data latched at each edge is θr + π + Δθr
It includes a rotation angle error Δθr expressed as .

Therefore, in reality, θr+π+Δθr including the rotational angle error Δθr is latched in the latch means 12.

The microcomputer 11 also includes an error calculation means 21 for calculating the rotation angle error Δθr of the resolver rotor 4B from the data θr, θr+π+Δθr latched by the latch means 12 and 13. This error calculation means 2
1 is data θr+π+Δθr from the latch means 12
(θr+π+Δθr)
It has an addition/subtraction means 22 that performs the calculation -θr-π, and the calculation result from this addition/subtraction means 22 is
The data is input to the primary storage means 18 via the sampler 17, stored in the primary storage means 18, and this stored value is updated as the latest value.

The sampler 17 is a determining means that determines that the speed is zero when the output from the differentiating means 15 that time-differentiates the data θr from the latch means 13 becomes less than a predetermined value in absolute value of the rotational speed, and outputs an output to that effect. When the sampler 17 closes, the data from the addition/subtraction means 22 is input to the primary storage means 18 and the data is input to the primary storage means 18.
The stored value of 8 is now updated.

Furthermore, the microcomputer 11 has an error correction means 24 which subtracts the rotational angle error Δθr calculated by the error calculation means 21 from the stored value θr+π+Δθr of the latch means 12 and outputs the result. This error correction means 24
is the addition means 2 which adds the data Δθr from the primary storage means 18 and the data π from the constant setting means 23.
5, and a subtraction means 26 for subtracting the output Δθr+π from the adding means 25 from the output θr+π+Δθr from the latch means 12 and outputting the result.

The microcomputer 11 also includes a switching means (sampler 19) that alternately switches the output θr from the error correction means 24 and the output θr from the latch means 13 to output it as θr ^* . from the sampler controller 14
The error correction means 24 side and the latch means 13 side are alternately switched by a switching signal every 180 degrees. The sampler controller 14 receives a signal from the delay means 20 and outputs a switching signal every 180 degrees.

The microcomputer 11 also includes a differentiator 27 for calculating the rotational speed by time-differentiating the output of the switching means 19 dθr ^* /dt.

With the above configuration, a two-phase AC current with a 90° phase difference is supplied to the resolver stator 4A from the two-phase AC generating circuit 3 shown in FIG. An AC voltage sin(θ+θr) is output, and this AC signal sin(θ+θr) is shaped into a rectangular wave signal by the waveform shaping circuit 6. After that, this rectangular wave signal is input to the trigger signal generation circuit 9 and this trigger signal is generated. A trigger signal (rising edge signal) is output from the generating circuit 9 at each rise and fall of the rectangular wave signal. This trigger signal is input to the latch circuit 10, and the latch circuit 10 latches the output data of the counter 2 for each rising edge signal (trigger signal). Upon receiving the output from the waveform shaping circuit 6, the rotational speed dθr/dt is calculated, and the rotational angle θr is determined from the rotational angle information θr+π. At this time, the microcomputer 11 can recognize the rotation angle θr data twice for each wavelength of the feedback signal, so
The feedback sampling frequency can be doubled without reducing the resolution of the single sample data, thereby improving the response of the servo motor control system by approximately twice. In addition, when calculating speed by taking the difference in rotation angle information θr, Δt of Δθr/Δt becomes 1/2, which equivalently doubles the speed resolution and improves control accuracy. I can do it. That is, a signal is input into the microcomputer 11 every half wave of the resolver feedback signal, and a recognition signal of either rotation angle information θr or θr+π is also input into the microcomputer 11, and θr+π is converted into θr using software, and as a result, the rotation angle is Since the angle θr data can be sampled every half wave, it is possible to double the response speed of the control system mentioned above and double the resolution when calculating rotational speed, improving control responsiveness and control accuracy. can be improved.

By the way, since there is a possibility that the output of the waveform shaping circuit and the output of the trigger signal generation circuit include the rotation angle error Δθr of the resolver rotor 4B, the microcomputer 11 removes this rotation angle error Δθr. It can be done. That is, phase data B
The error calculation means 21 calculates the angle data θr, θr+π+Δθr latched by the latching means 12 and 13, which alternately latches the angle data A every 180°.
The rotational angle error Δθr is calculated, and the error correction means 24 subtracts this rotational angle error Δθr from the value stored in the latch means 12.

Thereafter, the switching means 19 alternately outputs the output of the error correction means 24 and the output of the latch means 13.

Note that the memory for the rotation angle error is updated in the primary storage means 18 of the error calculation means 21 when the rotation speed corresponds to zero speed, and Δθr is not updated during rotation and is stored. Correction is performed based on Δθr. That is, when the rotor 4B of the resolver is now stationary, the phase difference between the excitation signal and the feedback signal should be stationary and hold a constant value. Therefore, in a stationary state, if the feedback signal is an ideal sine wave alternating current (no offset) and the waveform shaping circuit 6 also operates in an ideal manner, the circuit shown in Fig. The angle data θr, θr+π, θr, θr+π, etc. detected in the above should correctly have an angular difference of π. In the circuit shown in FIG. 1, when the sampler 17 samples a sample value other than zero, it is nothing but the error angle Δθr generated by the offset delay of the circuit, etc., for the reason mentioned above. Therefore, this Δθr is memorized at zero speed, and this error angle Δθr is calculated as θr+π+ when rotating.
The data of Δθr, that is, the two latch means 12, 1
3, it becomes possible to correct the error angle Δθr.

Note that the error angle Δθr is unique to this hardware circuit, and includes factors that vary over time due to temperature, etc. Therefore, it is not 100% accurate to use Δθr at rest as Δθr at other times. do not have. However, since fixed error elements are dominant over time other than temperature fluctuations, it can be said that it is practically possible to sufficiently correct Δθr using such means. As a result, it is possible to accurately double the sampling frequency, resulting in improved response, improvement, and higher accuracy of the servo motor control system.

Note that it is of course possible to perform such software processing by the microcomputer 11 using appropriate hardware.

[Effects of the invention] As detailed above, according to the resolver-type rotation angle detection device of the invention, the sampling frequency can be accurately increased without reducing the resolution of the resolver rotor rotation angle, and thereby the control This has the advantage of greatly contributing to improved responsiveness and accuracy.

[Brief explanation of the drawing]

Figures 1 and 2 show a resolver-type rotation angle detection device as an embodiment of the present invention. Figure 1 is an electric circuit diagram showing the main part of its calculation means, and Figure 2 shows its overall configuration. This is an electrical circuit diagram, and Figures 3 and 4 show a conventional resolver type rotation angle detection device.
FIG. 3 is an electric circuit diagram thereof, and FIG. 4 is a time chart for explaining its operation. In the figure, 1...oscillator, 2...counter,
3... Two-phase AC generation circuit, 4A... Resolver stator, 4B... Resolver rotor, 5... Induced voltage signal detection line, 6... Waveform shaping circuit, 9... Trigger signal generation circuit, 10... Latch circuit , 11...
...Microcomputer, 12, 13...Latch means, 14...
...Sample controller, 15...Differentiating means, 1
6... Judgment means, 17... Sampler, 18... 1
Next storage means, 19...Switching means (sampler), 2
0... Delay means, 21... Error calculation means, 22...
... Addition/subtraction means, 23... Constant setting means, 24...
Error correction means, 25...addition means, 26...subtraction means, 27...differentiation means. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of utility model registration request] A resolver-type rotation angle detection device that detects a rotation angle using a resolver includes a two-phase excitation circuit that generates two-phase alternating current having a phase difference of 90 degrees to excite the resolver, and a phase modulation induced in the resolver rotor. A waveform shaping circuit is provided for shaping the alternating current voltage signal from the signal detection line into a rectangular wave signal. and a trigger signal generating circuit that generates a trigger signal every time the trigger signal falls, and calculating means that takes in data and calculates the rotation angle of the resolver rotor every time the trigger signal is output. However, a pair of latching means alternately latches data each time the trigger signal is output, and an error calculating means for calculating the rotation angle error of the resolver rotor from the data latched by each of the latching means. error correction means for subtracting the rotation angle error calculated by the error calculation means from the stored value of one of the latch means; and alternately switching between the output of the error correction means and the output of the other latch means. 1. A resolver-type rotation angle detection device comprising a switching means for outputting an output.