JPH0462027B2 - - Google Patents

Description

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

[Prior art]

Fig. 3 is a block diagram showing a conventional analog speed detection method using a resolver, which has been proposed in, for example, Japanese Patent Application No. 58-243233. , 2 is a resolver phase shifter (hereinafter referred to as resolver), 11 is a position command, 13 is a speed control unit that controls the speed of the motor 1 with a signal from the position command 11, and 14 is an excitation reference circuit that generates a reference signal for excitation of the resolver. ,1
5 is a resolver excitation circuit for exciting the resolver 2, 16 is a feedback signal obtained by shaping the resolver output, and 31 is an excitation reference wave with twice the frequency of the excitation reference wave, which is halved by a frequency dividing circuit 32. The output signal is input to the resolver excitation circuit 15 to excite the resolver 2. 34 is a change detection pulsing 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, and 35 is a sample circuit that is slightly delayed from the rise of the feedback signal 16. 36 is the change detection pulse generation circuit 34 which outputs a pulse signal.
an inverter that converts the output of “H” and “L”;
37 is a falling pulse generation circuit that uses the falling edge of the output pulse of the sample pulse generation circuit 35 to generate a subsequent pulse, and 38 is configured to prevent the output pulse from being output when the phase discrimination circuit 33 changes. AND circuit that takes logical product for , 3
9 is a positive/inversion switching circuit that changes the phase of the excitation reference wave 31 by 180 degrees according to the output of the phase discrimination circuit 33; 40 is a rising pulse generator that outputs a pulse at the rise of the output of the positive/inversion switching circuit 39; circuit,
41 is zero volts from the center of the stepped part of the signal (sawtooth waveform) created by the sample and hold circuit 42 to just before the voltage changes, and when the voltage changes, the voltage that has changed is A voltage reset circuit 42a is a sample and hold circuit that always outputs zero volts, and the pulsed output voltage of the voltage reset circuit 41 is converted to a DC voltage by sampling the voltage other than zero volts. 43 is a voltage amplifier that amplifies the DC voltage to the voltage required for speed control. 44
numeral 45 is an integrating circuit with a reset function, and 45 is a waveform shaping circuit which outputs a feedback signal 16. As above, above 3
3 to 45 constitute a speed detection circuit.

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 from the "H" position of the excitation reference wave 31 to the "L" position. The output signal has a waveform D in FIG. The determined signal is sent to two places: a change detection pulse generation circuit 34 and a positive/inversion switching circuit 39. In the positive/inverse switching circuit 39, the phase of the excitation reference wave 31 is set to 0° by the signal sent from above.
180° (In Figure 4, all switches are turned on when set to "H" and turned off when set to "L".
"H" indicates that a voltage is output, and "L" indicates that the 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 input of an integrating circuit 44, which receives a constant DC voltage, to zero volts. As a result, the output of this circuit is the excitation reference wave 31
This results in a sawtooth wave like waveform F shown in FIG. 4, which is synchronized with . 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 a sample hold circuit 42 and sampled using a sample signal. The sample signal at that time is the feedback signal 16 which is sent to the sampling pulse generation circuit 35.
Put it in and make it. 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 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. In addition, the output voltage of the voltage reset circuit 41 (waveform I)
is the same value as the amount of change in the input, and the rate of change in the phase of the feedback signal 16, that is, the excitation frequency and the feedback signal 16
It is proportional to the frequency difference between

The rectangular wave signal thus obtained is input to the sample hold circuit 42a and sampled.
Create a straight line like 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 when the output of the phase discrimination circuit 33 changes. A pulse signal for one cycle of the feedback signal 16, such as the waveform J in FIG.
The logical product of this signal and the output pulse of the falling pulse generating circuit 37 mentioned earlier is generated through the AND circuit 38. Sample hold circuit 42a
The voltage generated is amplified to an appropriate voltage by a 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, since the voltage still goes in the opposite direction only once at the point of switching like waveform I shown in FIG. 4, the change detection pulse circuit 34 is used to prevent the sample and hold circuit 42a from sampling that point. That's why.

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), F _p (Hz), the output voltage is V _p (V), the input voltage of the integrating circuit 44 is V _I (V),
Let the capacitor be C (F) and the resistor be R (Ω).

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

On the other hand, the amount of change ΔV (V) of the reference signal of the sample and hold circuit 42 per cycle is ΔV=D・Δt=V _I・±F _p /C・R・F ² =±F _p・V _I /C・It becomes R・F ² (V). The output voltage V _p is V _p =ΔV・K = ±F _p・K・V _I /C・R・F ² (V), and C (F), R (Ω), F (Hz), K, _V1 (V)
is always constant, so V _p (V) is proportional to F _p (Hz). Since F _p (Hz) is proportional to the motor rotation speed, V _p 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 conventional analog speed detection method having the above configuration, a highly accurate output voltage can be obtained when the frequency change of the feedback signal 16 is small compared to the excitation reference frequency. When the frequency change increases during operation (at a similar speed), the error in the approximation formula F±F _p ≈F increases, resulting in a decrease in output voltage accuracy.

[Summary of the invention]

This invention was made with the purpose of eliminating such drawbacks, and the output voltage obtained by the conventional method,
In other words, we propose an analog speed detection method using a resolver that corrects the speed feedback signal by dividing it by the frequency modulation of the resolver feedback signal to obtain an output voltage that is exactly proportional to the rotation speed at any rotation speed. .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In the figure, the same reference numerals as in FIGS. 3 and 4 indicate the same or equivalent parts, 37a is a falling pulse generation circuit that generates a pulse at the fall of the output of the rising pulse generation circuit 40, and 46 is a rising pulse generation circuit 40. 47 is a divider for dividing the output of the voltage reset circuit 41.

As shown in FIG. 2, the signal A in FIG. 1 has been changed to a frequency divided by 1/4 of the frequency of the signal A in FIG. In the figure, signal A and signal C in FIG. 3 have been exchanged.

Next, the effect will be explained.

In FIG. 1, the output V _p of the voltage amplifier 43 without the divider 47 is expressed as v _p =±F _p・K・V _I /C・R・F・(F±F _p )(V) It will be done.

Here, when rotating at low speed (i.e., speed close to motor stop), it can be approximated as F±F _p ≈F, so the output V _p of the amplifier 13 is V _p =±F _p・K・V _I /C・R・F ² (V), and it is possible to obtain an output proportional to the rotation speed. However, during high-speed rotation, F _p (Hz) increases, so the approximation error increases. That is, the output is F/(F±F _p ) times the ideal speed proportional voltage.

Therefore, if F/(F±F _p ) is corrected by some method, the number of rotations and the output voltage will be completely proportional.

Now, at the timing of the feedback signal 16, the integrating circuit 4
4, the peak voltage of the output
V _p (V) becomes V _p =V _I /C·R·(F±F _p )(V).

This peak voltage V _p is divided into 1/G by a resistor (G
(The size of the voltage is set so that the input of the amplifier 43 becomes an appropriate value) Then, the divided voltage V _B (V)
is V _B =V _I /C・R・(F±F _p )・G(V).

Here, if a divider 47 is inserted between the voltage reset circuit 41 and the sample hold circuit 42a, and the output of the voltage reset circuit 41 is divided by the divided voltage V _B , the output voltage V _p (V) is obtained as follows. V _p =±F _p・K・V _I /C・R・F・(F±F _p )÷
V _I /C・R・(F±F _p )・G = ±F _p・K・V _I /C・R・F (F±F _p )×C
・R・(F±F _p )・G/V _I =±F _p・K・G/F(V). That is, the output voltage V _p becomes an output that is accurately proportional to ±F _p .

Here, since ±F _p is proportional to the rotation speed, the output voltage V _p is also proportional to the rotation speed. Therefore, by adjusting the gain K or voltage division ratio G of the amplifier 43, a voltage proportional to the desired speed can be obtained.

In the above embodiment, the output peak voltage of the integrating circuit 44 is sampled and held, but it is also possible to create a differentiating circuit separately, sample and hold it, and use a multiplier instead of the divider 47. It is possible.

〔Effect of the invention〕

As explained above, this invention corrects the speed feedback signal obtained by the conventional method by dividing it by the frequency modulation of the resolver feedback signal. This has the advantage that an output voltage can be obtained and highly accurate speed detection can be performed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the analog speed detection method using a resolver according to the present invention, Fig. 2 is a time chart thereof, Fig. 3 is a diagram equivalent to Fig. 1 showing the conventional analog speed detection method, and Fig. 4 is FIG. 2 is a diagram corresponding to FIG. 2 showing the time chart. 1... Motor, 2... Resolver, 13... Speed control unit, 14... Excitation reference circuit, 16...
Feedback signal, 37a...Falling pulse generation circuit, 4
1... Voltage reset circuit, 42, 42a... Sample hold circuit, 44... Integrating circuit, 46...
Division signal generation circuit, 47...divider, and in each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1 In a device 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, the sawtooth wave created by the resolver feedback signal is used to excite the resolver. Sample and hold the pulse created by the reference signal, and connect the step-like signal created 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. The velocity feedback signal is generated by blocking the sampling and holding of the pulsed signal of the reverse voltage that occurs at the same time, and further sampling and holding the pulsed signal that occurs thereafter. An analog speed detection method using a resolver, which is characterized by performing correction by dividing based on the frequency modulation component of a signal.