JPH0236090Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a load position detection device using a resolver. When the load is connected to the electric motor via a reducer,
If the reduction ratio is N, one revolution of the load is N of the motor.
This corresponds to rotation, and in order to detect the load position (rotation angle of the load), it is necessary to detect the rotation number as well as the rotation angle of the electric motor. To detect the motor rotation angle using a resolver, there is a method of obtaining resolver rotation angle information θ by synchronously rectifying the output signal of the resolver with an excitation signal, but this method uses a filter to remove harmonic components. However, there are drawbacks such as a delay in detection, and detection of the number of rotations of an electric motor using a resolver has not yet been carried out. This device uses a resolver to determine the motor rotation angle and number of rotations and detects the load position.This device eliminates the need for a filter, detects the rotation angle without any detection delay, and obtains accurate load position information. For the purpose of providing. In the drawings, FIG. 1 shows a block diagram of the embodiment, and FIG. 2 shows a time chart. In FIG. 1, 1 is a reference oscillator that outputs a constant frequency reference signal, and 2 is a frequency divider that divides this constant frequency reference signal into an appropriate frequency and supplies an input signal to a two-phase oscillator 3 for exciting the resolver. , two-phase oscillator 3
is an oscillator that outputs a two-phase sine wave that excites the two-phase excitation windings 4a and 4b of the resolver 4, respectively, and an output corresponding to the two-phase excitation windings 4a and 4b of the resolver 4 and the rotation angle of the rotor. Detection winding 4 that generates a signal
c and is connected to the electric motor 5. 6 is a speed reducer, and as mentioned earlier, the load according to the present invention is driven at a speed that is significantly reduced compared to the speed of the electric motor.If the speed reduction ratio is N, then N rotations of the electric motor 5 corresponds to one rotation of the load. Equivalent to. That is, in order to detect the rotational position of the load, it is necessary to detect the rotation angle and number of rotations of the motor, and the former motor rotation angle is extracted from the phase modulation force of the rotation angle θ generated in the resolver detection winding 4c. The number of rotations in the latter can be determined by first detecting the rotation angle θ.
It can be detected by monitoring the transition of , for example, from 2π phase to zero phase, or conversely from zero phase to 2π phase, as one rotation in the positive or reverse direction and incrementing or decrementing the counter. . First, detection of the rotation angle θ will be explained. Resolver 2
The phase excitation windings 4a and 4b are sine wave excitation signals.
coswt and sinwt are input, and if the rotor position is at the illustrated rotation angle θ, the detection winding 4c outputs a sine wave sin (wt + θ) corresponding to the rotation angle θ, and if this phase difference θ is extracted, the rotation The child rotation angle θ will be detected. 8 is a waveform conversion circuit that converts the resolver detection winding output signal sin (wt + θ) into a rectangular wave, and as the rotation angle θ of the rotor changes, the zero cross point of this phase-modulated sine wave output sin (wt + θ) As the waveform shifts, the timing of the rise and fall of the rectangular wave changes. 9 is a first latch circuit that latches the inverted output Q of the counter value from the frequency divider 2 at the rising edge of the rectangular wave output from the waveform conversion circuit 8, and outputs the phase difference θ between the excitation signal and the output signal, that is, the rotation angle θ. do. Of course, the inverted output Q is synchronized with the excitation signal,
When the phase difference θ is 2π or zero, the latch output is either the maximum value or zero. Therefore, if the starting point of the load is set to zero of the rotation angle θ, the latch output will change from 2π to zero. Or conversely, it can be determined that one revolution has occurred by transitioning from zero to 2π. That is, the number of rotations is detected by the first latch circuit 9 that outputs rotation angle information of the resolver detection winding.
The second one stores the rotation angle output of the previous latch.
The rotation angle outputs of the previous and current latches of the first and second latch circuits 9 and 10 are compared, and the difference, including positive and negative signs, is close to a predetermined value of 2π. Depending on whether the value of . This will be explained in detail below. The first latch circuit 9 latches the counter value inversion output Q of the frequency divider 2 at the zero cross point of the phase modulation output of the resolver detection winding to obtain a rotation angle output, but the latch timing is determined by the phase modulation of the sine wave. The output is converted to a rectangular wave and the rising edge of the wave is used. In other words, in order to memorize the previous rotation angle output, the previous first
It is sufficient to latch the rotation angle output of the second latch circuit 9 at the falling edge of the rectangular wave after half a cycle.
0, inputs the rotation angle output of the first latch circuit 9, latches it at the fall timing of the rectangular wave synchronized with the phase modulated resolver output waveform, and outputs it as the rotation angle information of the previous latch. Therefore, by comparing the rotational angle outputs of the first and second latch circuits 9 and 10 and taking the difference, it is possible to determine whether or not it is one rotation by checking the transition state of the difference, and the rotational direction is also the same as above. Depending on whether the difference is positive or negative, it is easy to distinguish between cases where the previous latch output was close to 2π and the current latch output is close to zero, and vice versa. can. Therefore,
It is equipped with two comparison circuits 11 and 12, and one comparison circuit 11 outputs a pulse signal when the difference between the outputs of the latch circuit exceeds a certain positive value, and is used as an increment signal for the subsequent counter. The comparator circuit 12 outputs a pulse signal when the output difference of the latch circuit exceeds a certain negative value, and is used as a decrement signal for the counter.
That is, it is equipped with a counter circuit 13, and uses pulse signals from the two comparison circuits 11 and 12 to increment or decrement the count value of the counter circuit 13 by using one of them as an increment signal and the other as a decrement signal, taking into account the direction of rotation. Find and output the number of rotations. In this way, the rotation angle is output from the first latch circuit 9 and the number of rotations is output from the counter circuit 13, but by adding these two pieces of information, ie, the motor rotation angle and the number of rotations, it is possible to calculate the load passing through the reducer. Position information can be obtained, and a third latch circuit 14 is provided to latch these two pieces of information and output it as load position information. The time chart in Figure 2 is a rectangular wave that shows the inverted output Q of the divider counter value synchronized with the resolver excitation signal (approximated by a triangular waveform) and the latch timing of the zero cross point of the resolver output signal (approximated by a triangular waveform). A, the rotation angle output waveform B of the current latch of the first latch circuit 9 which latches the count value Q at the rising edge of the square wave A, and the rotation angle output waveform B of the first latch circuit 9 at the falling edge of the square wave A. The rotation angle output waveform C of the previous latching of the second latch circuit 10 that latches, and these first and second latch circuits 9, 10.
This time, the rotation angle output waveforms B and C of the previous latch are compared, the difference is found, and the pulse waveforms D and E of the first and second comparison circuits 11 and 12 are output when the difference reaches the set value. , respectively, and the counter circuit 13
Using these pulse waveforms D and E as each increment and decrement signal, count the number of rotations,
The rotation angle of the first latch circuit 9 is added to obtain load position information. As described above, the present invention uses a resolver to detect the rotational angle of the electric motor in order to detect the rotational position of the load when the electric motor is connected to the load via the reducer. Observe the change over time, and when the rotation angle changes from a value close to 2π to a value close to zero, or vice versa, it is determined that it is one rotation in the forward or reverse direction.・Pulse signal is output and counted by a counter to determine the number of rotations.The method of obtaining load position information using a resolver has not yet been realized, and the method of detecting the motor rotation angle is also different from the conventional method. Compared to the detection delay using a filter, it has an extremely simple configuration that only includes a latch circuit that latches a sawtooth waveform synchronized with the resolver excitation signal at the zero-crossing point of the resolver output signal, contributing to cost reduction. It's a big deal. In the embodiment, the resolver is excited by a two-phase oscillator via a reference oscillator and a frequency divider, but if the reference oscillator and frequency divider are not used,
In order to obtain a signal with a frequency that is an integer multiple of the excitation signal of the phase oscillator, a PLL circuit or the like can be used, and its count inversion output can be used as the input signal of the counter circuit in place of the inversion output of the counter value of the frequency divider. As long as the sawtooth waveform is synchronized with the resolver excitation signal, there is no particular restriction on the form of the waveform.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the embodiment, and FIG. 2 is a time chart for explaining the operation. 1... Reference oscillator, 2... Frequency divider, 3... Two-phase oscillator, 4... Resolver, 8... Waveform conversion circuit,
9...First latch circuit, 10...Second latch circuit, 11...First comparison circuit, 12...Second comparison circuit, 13...Counter circuit, 14...Third
latch circuit.

Claims (1)

[Scope of utility model registration request] In a resolver equipped with one- and two-phase excitation windings and a detection winding that generates an output corresponding to the rotation angle of the rotor, a reference oscillator, a frequency divider that divides the output of the reference oscillator, and a frequency divider are used. a two-phase oscillator that outputs a two-phase resolver excitation signal after receiving the frequency-divided output from the resolver, a waveform conversion circuit that converts the phase modulation signal from the resolver detection winding into a rectangular wave, and an inversion of the counter value of the frequency divider. A first latch circuit that latches the output at the rising edge of the rectangular wave output of the waveform conversion circuit and outputs it as a rotation angle; and a first latch circuit that latches the output of the rotation angle of the first latch circuit at the falling edge of the rectangular wave output of the waveform conversion circuit. The second latch circuit that outputs the rotation angle of the previous latch is compared with the rotation angle output of the current and previous latch of the first and second latch circuits, and the difference is greater than a predetermined positive or negative value. If so, two comparison circuits each output a pulse signal, and one of the pulse signals of the two comparison circuits is used as an increment signal and the other as a decrement signal to determine one rotation in the forward or reverse direction and detect the number of rotations. Load position detection using a resolver, characterized in that it is equipped with a counter circuit that latches the number of rotations of this counter circuit and a rotation angle of the first latch circuit and outputs the load position. Device.