JPH0228162B2 - REZORUBANYORUANAROGUSOKUDOKENSHUTSUHOHO - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an analog speed detection method using a resolver, in which a speed feedback signal of a positioning servo system using a resolver phase shifter is generated by an analog circuit. It is.

[Prior art]

A conventional device of this type is shown in FIG. In this figure, indicates the machine side, and indicates the control side, 1 is the motor, 2 is the resolver phase shifter (hereinafter simply referred to as resolver), 3 is the tachogenerator, 11 is the position command, and 12 is the speed control unit 13. 14 is an excitation reference wave for exciting the resolver 2, 15 is a resolver excitation circuit, and 16 is a feedback signal from the resolver 2.

In FIG. 2, the tachometer generator 3 is omitted, and 17 is a speed detection circuit that generates a speed feedback signal from a position feedback signal, the details of which are shown in FIG.

In FIG. 3, 21 is a phase discrimination circuit for determining the position of the feedback signal (also known as resolver feedback) 16 with respect to the reference position (here, the position signal is treated as a phase), and 22 is the feedback signal 16 is a waveform shaping circuit for transforming into a rectangular wave; 23a and 23b are rising pulse generation circuits that convert the rising edge of the signal into pulses; 24 is a falling pulse generation circuit that converts the falling edge of the signal into a pulse;
5 is an integrating circuit with a reset that creates a sawtooth wave by using the output pulse of the rising pulse generating circuit 23a as a voltage reset signal (setting it to zero volts); Or a sample hold circuit for sampling at falling timing,
27a and 27b are filters for smoothing signals created by sampling; 28a and 27b are filters for smoothing signals created by sampling;
28b is a differentiating circuit for detecting the amount of change in the output waveforms of the filters 27a and 27b, respectively;
9 is a differentiation circuit 28a, 28 based on the phase discrimination signal.
This is a changeover switch for changing the output of the motor b, and sends the output to the speed control unit 13 as a speed feedback signal.

Next, the operation will be explained. In Figure 1,
The excitation reference wave 14 is input to the resolver excitation circuit 15 to generate an excitation signal, which excites the resolver 2, and its output becomes the feedback signal 16. When the position command 11 is input to the position control circuit 12, a position error (phase difference) occurs between the position command 11 and the feedback signal 16. The error is converted into voltage and sent to the speed control unit 13 as a speed command. The speed control unit 13 is
The signal is compared with the output of the tachometer generator 3 (speed feedback signal), and the motor 1
to drive. As the resolver 2 coupled to the motor 1 rotates, the phase of the feedback signal 16 changes depending on the rotation angle. A position control loop is constructed by feeding back this feedback signal 16 to the position control circuit 12 as a position feedback signal. That is, while the position command 11 is issued, an error occurs in the position control circuit 12, and the motor 1 rotates so as to eliminate the error.

The tachogenerator 3 used in this control device rotates at the same rotational speed as the resolver 2, so if a signal equivalent to the output of the tachometer generator 3 can be obtained from the resolver 2, the tachometer generator 3 can be removed. Therefore, the system shown in FIG. 2 was considered, in which a speed detection circuit 17 is added in place of the tachometer generator 3 shown in FIG. The speed detection circuit 17 is shown in Fig. 3, and the configuration and operation of the circuit are shown in Fig. 4.
This will be explained with reference to the timing chart shown in the figure.

In FIG. 3, every cycle (360°) of the excitation reference wave 14, the integral circuit 25 is reset with a pulse created by the rising pulse creation circuit 23a to create a sawtooth wave. On the other hand, from the feedback signal 16 shaped into a rectangular wave by the waveform shaping circuit 22, a rising pulse generating circuit 23b and a falling pulse generating circuit 2
4 to create rising and falling pulses, and the signals are sampled by sample and hold circuits 26a and 26b. As a result, a sawtooth wave having a frequency equal to the frequency difference between the feedback signal 16 and the reference signal is generated at the outputs of the sample and hold circuits 26a and 26b. When these waveforms are enlarged, they have a step-like shape with the same period as the feedback signal 16, and are made into a nearly straight waveform by passing through the filters 27a and 27b. As a result, waveforms B and C shown in FIG. 4 are obtained. Since the sample signals are shifted by 180 degrees, the output waveforms are also different from each other.
This means that it is shifted by 180°. Further, they are passed through differentiating circuits 28a and 28b to extract a voltage proportional to the amount of change. As a result, waveforms D and E shown in FIG. 4 are obtained. As shown in the figure, when the sawtooth waves (waveforms B and C) return to zero volts, the voltage changes suddenly, so it is necessary to avoid using this part. Therefore, the excitation reference wave 14 and the feedback signal 16
The phase discrimination circuit 21 discriminates the rising pulse (output of the rising pulse generation circuit 23b) from the rising pulse (output of the rising pulse generating circuit 23b), generates a signal at the timing of the waveform A shown in FIG. Switch between waveform D and waveform E signals. the result,
A linear output like waveform F shown in FIG. 4 can be obtained. This output is then sent to the speed control unit 13 as a speed feedback signal. That is, a change in the phase difference between the excitation reference wave 14 and the feedback signal 16 is converted into a sawtooth voltage, and this signal is differentiated to generate a speed feedback signal, which is sent to the speed control unit 13 instead of the tachometer generator 3 to control the motor 1. control.

Since the conventional analog speed detection method is configured as described above, it has the following problems.

(1) Since there are two differentiating circuits 28a and 28b,
If the offset voltages of this circuit are different, rectangular wave ripples will occur, especially at low speeds.

(2) Since the filters 27a and 27b are provided, there is a large delay in output with respect to changes in the feedback signal 16.

[Summary of the invention]

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional circuit, and by removing the differentiating circuit and replacing it with a circuit that resets the voltage using a capacitor and a switch, it eliminates the filter and eliminates signal delay, and also integrates the circuit. The present invention provides an analog speed detection method that eliminates the influence of offset.

[Embodiments of the invention]

FIG. 5 is a configuration block diagram showing an embodiment of the present invention. Reference numeral 31 denotes an excitation reference wave with twice the frequency of the excitation reference wave, and the output signal is halved by a frequency dividing circuit 32 to excite the resolver. into the circuit 15 to excite the resolver 2. Therefore, the combination of the excitation reference wave 31 and the frequency dividing circuit 32 is the same as the excitation reference wave 14 shown in FIGS. 1 and 3.
34 is a change detection pulse circuit that generates a pulse with a width of one cycle of the feedback signal 16 at the rise and fall of the output of the phase discrimination circuit 33; A sample pulse generation circuit that outputs a pulse signal; 36 is an inverter that converts the output of the change detection pulse generation circuit 34 between "H" and "L"; 37 is an inverter that converts the falling edge of the output pulse of the sample pulse generation circuit 35; 38 is an AND circuit that takes logic to prevent the output pulse from outputting only a pulse when the phase discrimination circuit 33 changes; 39 is an AND circuit that uses the phase discrimination circuit 33 to generate a pulse; a positive/inverse switching circuit that changes the phase of the excitation reference wave 31 by 180° by the output of the
40 is a rising pulse generating circuit that outputs a pulse at the rising edge of the output of the positive/inverting switching circuit 39; 41;
is zero volts from the center of the stepped portion of the signal (sawtooth waveform) created by the sample-and-hold circuit 42a to just before the voltage changes, and when the voltage changes, the changed voltage is A voltage reset circuit 43 ensures that the voltage always outputs zero volts, and a sample and hold circuit 42a samples the pulse-like signal generated by the voltage reset circuit 41 at voltages other than zero volts. This is a voltage amplifier that converts the DC voltage into a DC voltage and amplifies the DC voltage to the same voltage as the tachometer generator 3 in FIG. 44 is an integrating circuit with a reset function, and 45 is a waveform shaping circuit which outputs the feedback signal 16. Note that the speed detection circuit 170 is composed of the above-mentioned components 33 to 45.

Next, the operation will be explained using the time chart shown in FIG.

A position determining circuit 33 determines the position of the phase of the excitation reference wave 31 and the phase of the feedback signal 16. In this case, a D flip-flop is used to determine whether the rise of the feedback signal 16 is at the "H" position or the "L" position of the excitation reference wave 31. The output signal is waveform D in Figure 6.
become that way. The determined signal is sent to two places: a change detection pulse generation circuit 34 and a positive/inversion switching circuit 39. The positive/inverse switching circuit 39 changes the phase of the excitation reference wave 31 to 0° using the signal sent above.
Output either one of 180 degrees (in Figure 6, all switches are set to "H" for ON, "L" for all switches)
OFF・“H” indicates that voltage is output, “L” indicates that voltage is zero). Note that the reason for switching will be described later. The signal output from the positive/inverting switching circuit 39 is converted into a pulse signal by a rising pulse generating circuit 40, and the pulse signal resets the output of an integrating circuit 44, which receives a constant DC voltage as input, to zero volts. As a result, the output of this circuit becomes a sawtooth wave such as waveform F shown in FIG. 6, which is synchronized with the excitation reference wave 31. From the point in time when the output of the phase discrimination circuit 33 is switched, the phase changes by 180 degrees as shown in FIG. The sawtooth wave thus created is input to the sample hold circuit 42b and sampled using the sample signal. A sample signal at that time is generated by inputting the feedback signal 16 into a sample pulse generation circuit 35. The sample pulse generating circuit 35 consists of a falling pulse generating circuit and a rising pulse generating circuit, and the output thereof is a pulse signal slightly delayed from the falling edge of the feedback signal 16. The sampled signals become waveforms H and M shown in FIG.
Note that the waveform M has the time axis (horizontal axis) of the waveform H shortened and the voltage (vertical axis) approximately doubled. Then, the sampled and held signal is input to the voltage reset circuit 41. This circuit passes the input signal through a capacitor and then, at the "H" position of the feedback signal 16, is grounded by a switch to reset the voltage. Once reset, even if the reset signal is released, the output voltage of the voltage reset circuit 41 does not change and remains at zero volts until the input signal changes, but when the input signal changes, the output becomes the same voltage as the amount of change. changes from zero volts. Note that the output section is received by the voltage follower of the operational amplifier. As a result, a rectangular wave having the same period as the feedback signal 16 is obtained, as shown in waveform I shown in FIG. Further, the output voltage (waveform I) of the voltage reset circuit 41 has the same value as the amount of change in the input, and is proportional to the rate of change in the phase of the feedback signal 16, that is, the frequency difference between the excitation frequency and the feedback signal 16.

The rectangular waveform signal thus obtained is input to the sample-and-hold circuit 42a, where it is sampled and made into a straight line as shown in the waveform L shown in FIG. At this time, the pulse signal for the sample is generated by the falling pulse generation circuit 37 at the falling edge of the output signal of the sample pulse generation circuit 35, and further changes at the time when the output of the phase discrimination circuit 33 changes. It exits from the ground detection pulsing circuit 34. A pulse signal for one cycle of the feedback signal 16, such as waveform J shown in FIG. AND circuit 38
It was created through. Since the voltage generated by the sample and hold circuit 42b is too low in level, it is then amplified to an appropriate voltage by the voltage amplifier 43 and sent to the speed control unit 13 as a speed feedback signal.

Now, the reason why the phase of the sawtooth wave is switched by 180 degrees by the positive/inversion switching circuit 39 is that since an operational amplifier is used to create the sawtooth wave, the voltage from the highest level to zero volts is Since it takes time, if the sample pulse passes through that position, the output of the voltage reset circuit 41 will be a large voltage that is opposite to the actual voltage, and it is impossible to remove this, so the sample pulse is always This means that it must be located in the center of the sawtooth wave. However, the voltage still goes in the opposite direction by one at the time of switching as shown in the waveform I shown in FIG.
4 is used to prevent the sample hold circuit 42a from sampling that part.

Next, the relationship between the output voltage and the amount of change in the feedback signal will be described. Note that twice the excitation reference frequency is 2・F
(Hz), the excitation frequency is F (Hz), the difference between the frequency of the feedback signal 16 and the excitation frequency F (Hz) is F ₀ (Hz), the output voltage is V ₀ (V), the input voltage of the integrating circuit 44 is V _I
(V), the capacitor is C(F), and the resistor is R(Ω).

The frequency of the feedback signal 16 is modulated by the rotation speed and becomes F±F ₀ (Hz), so if the gain of the voltage amplifier 43 is K, the slope value of the sawtooth wave D (V/
sec) is D=V _I /C・R (V/sec), and the period T (sec) of the feedback signal 16 when the feedback signal 16 is changing at ±F ₀ (Hz) is T=1 /F±F ₀ (sec). Change amount Δt per cycle at that time
(sec) becomes Δt=1/F±F ₀ −1/F=〓F ₀ /F(F±F ₀ ). If the value of F is chosen to be sufficiently large compared to F ₀ , F±F ₀ ≒F, and as a result, Δt≒±F ₀ /F ² (sec).

On the other hand, the reference signal 1 of the sample hold circuit 42b
The amount of change ΔV (V) per cycle in 6 is ΔV=D・Δt=V ₁・(±F ₀ ) or ±F ₀・V ₁ /C・R・
F ² =±F ₀ ·V _I /C·R·F ² (V). The output voltage V ₀ is V ₀ = ΔV・K = ±F ₀・K・V _I /C・R・F ² (V), and C (F), R (Ω), F (Hz), K, V _I (V)
is always constant, so V ₀ (V) is proportional to F ₀ (Hz). Since F ₀ (Hz) is proportional to the motor rotation speed, V ₀ is also proportional to the motor rotation speed. In this way, an output proportional to the motor rotation speed can be obtained, and this output signal can be used as a speed feedback signal for the control system.

In the above embodiment, a sawtooth wave was created using the excitation reference wave 31, but the excitation reference frequency was changed to 2.F.
(Hz) but F/2 (Hz), and the feedback signal 16
Even if you create a sawtooth wave with , there is no harm in just reversing the positive and negative of the output voltage. However, in that case, the gain of the voltage amplifier 43 may be set to -K.

〔Effect of the invention〕

As explained in detail above, this invention removes the filter and differentiation circuit and outputs the amount of change directly, resulting in a high-speed response, and by integrating the circuit, a high-precision signal can be obtained even at low speeds. has advantages.

[Brief explanation of drawings]

Figure 1 is a block diagram of a position control system using a conventional tachometer generator, Figure 2 is a block diagram of a position control system using an analog speed detection circuit, and Figure 3 is a block diagram of a position control system using an analog speed detection circuit.
The figure is a configuration block diagram showing the conventional analog speed detection method, Figure 4 is the time chart of Figure 3, and Figure 5
The figure is a configuration block diagram showing one embodiment of the present invention.
FIG. 6 is a time chart of FIG. 5. In the figure, 1 is a motor, 2 is a resolver, 11 is a position command, 12 is a position control circuit, 13 is a speed control unit, 14 and 31 are excitation reference waves, 15 is a resolver excitation circuit, 16 is a feedback signal, 17, 170 2 is a speed detection circuit, 21 is a phase discrimination circuit, 22 is a waveform shaping circuit, 23a, 23b, 40 are rising pulse generation circuits, 24, 37 are falling pulse generation circuits, 2
5, 44 are integral circuits, 26a, 26b, 42a,
42b is a sample hold circuit, 27a, 27b
28a and 28b are filters, 28a and 28b are differentiating circuits, 29 is a changeover switch, 32 is a frequency dividing circuit, 33 is a phase discrimination circuit, 34 is a change detection pulse generation circuit, 35 is a sample pulse generation circuit, 36 is an inverter, 38
39 is an AND circuit, 39 is a positive/inverting switching circuit, 41 is a voltage reset circuit, 43 is a voltage amplifier, and 45 is a waveform shaping circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 In a positioning servo system that uses a resolver phase shifter and performs control by generating a position feedback signal and a velocity feedback signal based on the phase of the resolver feedback signal, a sawtooth wave created by a reference signal is generated by the feedback signal. Sample and hold the generated pulse, and connect the step-like signal generated by this to the ground using a switch so that the voltage from the center of the signal to just before the change is zero volts through a capacitor. An analog speed detection method using a resolver, characterized in that the speed feedback signal is generated by further sampling and holding the pulsed signal.