JPS62457B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed detection device using a resolver.

In the resolver, two-phase excitation sources sin ωt, cos
For ωt, the resolver output becomes sin(ωt±Θ). Θ is expressed as pω _M t, where p is the number of resolver pole pairs and ω _M is the mechanical angular frequency of the motor. To detect the motor speed ω _M , the differential of Θ is obtained as dΘ/
All that is required is to find dt, and a signal proportional to the motor speed ω _M can be obtained.

To calculate this dΘ/dt, the excitation source sin ω
It is sufficient to obtain the differential angular frequency signal sin Θ between t and the resolver output sin (ωt±Θ), and differentiate the periodic function sin Θ with respect to this Θ once to obtain the signal waveform of dΘ/dt・cos Θ. As is clear from the equation, the amplitude is proportional to dΘ/dt.

Methods to obtain a differential angular frequency signal between two periodic functions include the sample-and-hold method, in which one signal samples and holds the other signal;
There are two methods: synchronous rectification, which inverts the other signal every 180 degrees to smooth it. Compared to the sample-and-hold method, the synchronous rectification method has larger ripples.
It becomes necessary to arrange a smoothing circuit with a large time constant before the differentiation, which poses a problem in quick response.

The differential angular frequency signal is a periodic function (Θ) regarding Θ, and no matter what waveform it is, if you differentiate it, d(Θ)/dt = d(Θ)/dΘ・dΘ/dt
If d(Θ)/dΘ is constant, d(Θ)/dt is proportional to dΘ/dt. In other words, if (Θ) is sin Θ as in the example above, then when d(Θ)/dt is calculated, d(Θ)/dΘ becomes cos Θ and is expressed as a periodic function, so this cos Θ The amplitude of is d
It corresponds to Θ/dt, and if we focus on the amplitude of the obtained differential signal waveform, this becomes the motor speed signal to be detected.

Next, consider the waveform of the periodic function (Θ). That is, the ideal motor speed signal is an instantaneous detection value without time delay, and of course it is necessary to be able to detect it continuously. In other words, the periodic function of Θ obtained by differentiating (Θ) (d(Θ)/dΘ)・(dΘ/
dt), the amplitude (dΘ/dt) corresponding to the velocity signal can be converted into a continuous linear height signal waveform using some means (Θ).

By the way, the resolver is two-phase excitation, and the differential angular frequency signal obtained by sampling and holding the excitation source at the resolver output is two signals with a phase difference of 90 degrees. Therefore, this differential signal waveform also has a phase difference of 90 degrees. Two identical waveform signals are obtained,
There are two differential waveforms d(Θ)/dt of (Θ), and it is conceivable to use these two differential waveforms when converting the differential waveform amplitude into a continuous height signal.

That is, in this invention, in view of the fact that the resolver has two-phase excitation and the differential signals of the differential angular frequency signal are two identical waveform signals with a phase difference of 90 degrees, the present invention A simple method of adding and combining signals is used to obtain a continuous height signal that matches the amplitude of the differential waveform signal. Two differential waveform signals with a phase difference of 90 degrees are treated as a triangular waveform. When one waveform is zero, the other waveform is at its maximum value, and while the former increases as the phase progresses, the latter decreases with the same slope, and the summed value of both is the maximum value of the triangular waveform amplitude. This does not change at all even when the former reaches its maximum value and the latter is zero, and in the end, the 90° phase difference between the two
Additive synthesis of the two triangular waveforms yields a signal with a constant value as a height signal that matches the amplitude value of the triangular waveforms.

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments. As for the drawings, FIG. 1 is a configuration diagram of the resolver, FIG. 2 is a block diagram of a speed detection device using the resolver, and FIG. 3 is a time chart for explaining the operation.

As shown in Figure 1, the resolver is located on the stator side.
It is composed of phase excitation windings 1 and 2 and a one-phase output winding 3 on the rotor side. Excitation windings 1 and 2 are each
Two-phase sine wave signal sin ωt, cos with a 90° phase difference
The output winding 3 receives an output signal sin(ωt
±Θ) is generated and taken out to the outside via the rotary transformer 4. This rotation angle Θ changes with time, and if the motor speed is ω _M and the number of pole pairs is p, it can be expressed as pω M t, and the resolver output signal becomes sin(ωt± _{pω M} t). In other words, speed detection by a resolver involves how to obtain a phase differential signal dΘ/dt proportional to the motor speed ω _M from a phase modulation signal sin (ωt±Θ) of the resolver output. Obtain the difference angular frequency signal between the signal and the output signal, and this Θ
The differential signal d of Θ is obtained by differentiating the periodic function once with respect to
Θ/dt is extracted as the amplitude of this one-time differential Θ periodic function.

In the block diagram shown in Figure 2, 5 and 6 are circuits that form triangular waves synchronous with the resolver excitation source sin ωt and cos ωt, and 7 is the resolver output sin(ω
t±Θ) into a rectangular wave; 8 and 9 are integrating circuits that obtain a parabolic waveform by integrating the triangular wave synchronized with the excitation source output from the triangular wave forming circuits 5 and 6;
0 and 11 are sample and hold circuits that sample the parabolic waveform at the fall (rise) timing of a rectangular wave that is synchronized with the resolver output, and 12 and 13 are sample and hold circuits that sample the parabolic waveform at the fall (rise) timing of a rectangular wave that is synchronized with the resolver output. Filters 14 and 15 waveform-shape the differential angular frequency signal and remove the hold step of sampling, and filters 14 and 15 are periodic functions of Θ that differentiate the parabolic waveform of the waveform-shaped differential angular frequency signal and have the amplitude of the differential dΘ/dt of Θ. Differential circuit that converts into a triangular wave,
16 and 17 are this triangular wave (amplitude is motor speed ω _M
18 is an adder circuit that adds and synthesizes the two rectified triangular waves to obtain a height signal proportional to the motor speed ω _M.

The time chart in FIG. 3 shows the input and output waveforms of each circuit in the previous block diagram. From the top, triangular waves A and B resolver output signals sin(ωt) synchronized with resolver excitation signals sin ωt, cos ωt.
+Θ), parabolic waveforms D and E obtained by integrating the rectangular waves A and B, and the differential angular frequency signal obtained by sampling these parabolic waveforms D and E at the falling timing of the rectangular wave C. Sample and hold waveforms F and G, parabolic waveforms H and I of the difference angular frequency obtained by removing the hold step of these sample and hold waveforms F and G, and an amplitude proportional to the difference angular frequency obtained by differentiating the parabolic waveforms H and I. 2, waveforms L and M obtained by rectifying the triangular waves J and K, and a constant height signal N whose amplitude corresponds to the rectified triangular waves L and M are added and synthesized.

That is, in this invention, the resolver has two-phase excitation, and the difference angular frequency signal obtained by sampling and holding the output signal has two phases, and the differential waveform signal of this can also be obtained with two phases. It attempts to extract a constant height signal that matches the amplitude of the differential waveform by using the differential waveform of the phase difference, and is characterized in that the two differential signal waveforms are triangular waves.

As is clear from the time chart in Figure 3, if the rectified waveforms L and M of the triangular waves J and K are added and combined, a height signal N that matches the amplitude of the triangular waves J and K is obtained, and the motor speed ω _M is Phase differential dΘ/dt
signals can be detected. Therefore, in order for this differential waveform to become triangular waves J and K, the waveform obtained by integrating the J and K waveforms must be a parabolic waveform,
The resolver excitation signal before sample and hold must also be converted to a parabolic waveform.

That is, this invention converts the resolver excitation signal into a rectangular wave, further integrates it to obtain a triangular wave, and also integrates this triangular wave to obtain a parabolic waveform.
This is sampled at the zero cross timing of the resolver output to obtain a differential angular frequency signal between the resolver excitation signal and the output signal in a parabolic waveform, and the parabolic waveform signal of this differential angular frequency is differentiated to calculate the amplitude. Convert these two phases into a triangular wave corresponding to the speed signal.
By adding and synthesizing the triangular waves with phase differences, a constant height signal matching the amplitude is obtained.

To explain the function using the block diagram in Fig. 2 and the time chart in Fig. 3, the triangular wave forming circuits 5, 6
As a result, triangular waves A and B having a phase difference of 90° are formed in synchronization with the excitation signal, and these triangular waves A and B are converted into parabolic waveforms D and E via integrating circuits 8 and 9. On the other hand, a rectangular wave C synchronized with the resolver output is output from the rectangular wave conversion circuit 7, and at this rising or falling timing, the sample and hold circuits 10 and 11 sample and hold the parabolic waveforms D and E, and the sample and hold waveform F , G are formed. The sample and hold waveforms F and G undergo step-shaped shaping through filters 12 and 13, and are converted into parabolic waveforms H and I of the difference angular frequency between the resolver excitation and output, and further pass through differentiating circuits 14 and 15 to form the difference angular frequency. It is converted into triangular waves J and K with amplitudes matching the angular frequency (velocity signal). The triangular waves J and K are rectified by rectifier circuits 16 and 17, converted into rectified waveforms L and M, and further summed and combined by an adder circuit 18 to obtain a continuous linear signal N that matches the amplitude of the triangular waves J and K.

As described above, the present invention is based on the fact that the resolver has two-phase excitation, and if the resolver output of the phase modulation signal is sampled and held, a two-phase differential angular frequency signal corresponding to the motor speed can be obtained. The waveform is a periodic function with an amplitude proportional to the differential angular frequency, and these two-phase periodic functions with a 90° phase difference are used to extract the amplitude as a continuous signal regardless of the period, and it has good quick response without time delay. A speed signal can be obtained, which is ideal as a feedback signal for the speed control loop. Note that the step height when shaping a parabolic sample-hold waveform is not so much a problem as the resolver excitation frequency is around 5KHz, but the motor speed is slow at around 150Hz, and it is around 1msec. A filter with a short time constant of 1 is sufficient, and there is no need to remove large ripples as in the conventional synchronous rectification method, and this filter has almost no effect on the quick response. In addition, the rotational configuration is a combination of components such as an OP amplifier, a resistor, a capacitor, and an FET, making it possible to provide an analog speed detector that is simple and inexpensive, and has high precision and excellent quick response.

[Brief explanation of the drawing]

As for the drawings, FIG. 1 is a configuration diagram of the resolver, FIG. 2 is a block diagram of the embodiment, and FIG. 3 is a time chart for explaining its operation. 1, 2... Resolver excitation winding, 3... Resolver output winding, 5, 6... Triangular wave generation circuit, 7... Rectangular wave generation circuit, 8, 9... Integrating circuit, 10, 11
...sample hold circuit, 12,13...filter, 14,15...differentiation circuit, 16,17...
... Rectifying circuit, 18... Adding circuit.

Claims (1)

[Claims] 1 In a resolver consisting of a two-phase excitation winding and a one-phase output winding, two triangular wave generation circuits that form a triangular wave in synchronization with the excitation signal of the two-phase excitation winding;
Two integrating circuits convert this triangular wave into a parabolic waveform, a rectangular wave generation circuit converts the phase modulation signal of the output winding into a rectangular wave, and the above two parabolic waveforms are generated at the rising or falling timing of the rectangular wave. Two sample and hold circuits that sample and hold, two filters that shape this sample and hold waveform, two differentiating circuits that differentiate this shaped sample and hold waveform and convert it into a triangular wave, two rectifier circuits that rectify this triangular wave, and this A speed detection device using a resolver, comprising an addition circuit that adds and synthesizes rectified triangular waves and outputs a continuous height signal that matches the amplitude.