JPS6113163A - Apparatus for detecting speed of resolver - Google Patents

Abstract

PURPOSE:To enable the speed control of an electric motor with high accuracy, by making the amplitude of a resolver detection signal constant by changing the gain of an amplifier corresponding to the amplitude of said resolver detection signal while reducing the speed ripple of a speed detection means. CONSTITUTION:An exciting circuit 5 imparts two-phase magnetic signals alpha, beta of 90 deg. phase difference to a resolver 6. The resolver 6 generates a detection signal theta wherein a phase is shifted by the rotary angle of a shaft with respect to the exciting signal of the resolver 6 and amplitude is changed by said angle. An amplitude constant circuit 7 makes the amplitude of theta, which receives amplitude modulation by the rotation of the shaft, constant and shaping circuits 8, 9 converts sine waves alpha, theta to rectangular waves Palpha, Ptheta through a comparator. When an exciting signal of alpha is imparted to the resolver 6 at first from the circuit 5, the detection signal theta is obtained. The amplitude of this signal is changed by the rotary angle of the shaft. Therefore, speed ripple is reduced and a resolver speed can be detected with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus using a resolver as speed detection means in an electric motor speed control system.

[Conventional technology and problems]

FIG. 5 is a block diagram of a speed control system of a general electric motor.

/ is a dry nozzle for driving the electric motor, ko is an electric motor, 3 is a speed detection device for the electric motor, and gu is a controller for the dry nozzle.

When a resolver is used as a speed detector in this speed control system, the resolver detection signal depends on the shape of the iron core of the resolver body, the material properties of the iron core, -! Due to the influence of windings, gaps, etc., the amplitude of the detection signal changes depending on the rotation angle of the shaft.

When this signal is waveform-shaped by a comparator and the speed is detected, the amplitude change is detected as a speed ripple.

Figure 6 shows the results during waveform shaping.

0LLH2CLHL is the conomilate level of the comparator, and CLLH changes from low level to 0 to 0.
LHI is a level that changes from Ha High Re 4 to Loan 4 Ru.

Conohysteresis prevents the comparator from generating a false i signal.

In FIG. 6, α represents the excitation waveform of the resolver, θ represents the detected waveform, and θ' represents the waveform with the same amplitude as the point Pn-1.

The waveform of α is shaped by Pa, and the waveform of θ is shaped by Pa.

When the amplitude at point Pn becomes smaller than the amplitude at point Pn-□, P
The rise of Pa at point n is delayed by Δt.

If the speed N is calculated from Pa and P, it will be as follows.

However, P is the number of poles and Ta is the excitation period.

! (7) When Δt changes depending on the rotary table, the change causes ripples in the speed detection signal.

[Purpose of the invention]

SUMMARY OF THE INVENTION The present invention provides a highly accurate resolver speed detection device that overcomes the drawbacks of conventional devices, makes the amplitude of the detected waveform of the resolver constant, eliminates Δt, and thereby reduces the speed ripple of the speed detection means. is its purpose.

[Summary of the invention]

In a motor speed control system using a resolver as a speed detector, the present invention provides means for correcting a resolver detection signal to a constant amplitude, such as an analog multiplier that is an amplifier whose gain can be electrically changed. This is a resolver speed detection device that fixes the amplitude of the detection waveform, shapes the resolver detection signal, measures the period, and detects the speed signal. A block diagram is shown in FIG.

j is a co-phase excitation signal α with a 90 degree phase difference to the resolver.

This is an excitation circuit that provides β. Reference numeral 6 denotes a resolver which generates a detection signal θ whose phase is shifted by the rotation angle φ of the shaft with respect to the excitation signal and whose amplitude further changes according to φ. Reference numeral 7 denotes a circuit that keeps the amplitude of θ modulated by the rotation of the shaft constant. r
, the sine wave α and θ are used as comparators, and the rectangular wave P is
a, a shaping circuit to set Pa; 10 is a high frequency oscillator;
l/ is a counter.

/2 is a latch. 13 is a microprocessor that performs speed calculations. First, the excitation circuit! E as Yoshi α. s
When an excitation signal of 1lli(, cosωt is given to resolver B as inωt, β, E(φ) is
A detection signal θ of 's in (art+φ) is obtained.

The amplitude of this signal is a value E(φ) that changes depending on the rotation angle φ of the shaft for the reasons mentioned above.The amplitude-leg circuit 7 makes this amplitude-modulated signal have a constant amplitude. The details of the circuit configuration are shown in FIG.

In FIG. 2, /Hiro is an analog multiplier that performs the operation of AXB='O, with θ as the multiplicand A and the signal l as the multiplier B.

The multiplier B is a value that makes the amplitude of the output C of the analog multiplier lhiro constant, but its value is 15 absolute value circuits, /6
It's Notsuchi Filter! The deviation between the obtained amplitude value of C and the amplitude setting value is obtained from the subtracter /7, and it is determined by proportional + integrating it using the proportional and integral circuit lza.

FIG. 3 shows the input and output waveforms of an analog multiplier, ie, an amplitude-tooth circuit.

Even if the amplitude of A changes, a waveform with a constant amplitude can be output to C by changing the value of B. however,
The ratio between the excitation frequency and the amplitude modulation frequency is large, and the notch filter removes the excitation frequency component, allowing only the amplitude modulation frequency component to be obtained.

The constant C is shaped by the shaping circuit shown in FIG. 1, and the latch signal of latch/2 and the nine pulses generated by the zero oscillator 10, which is used as the speed calculation start timing pulse of the microprocessor 13, are counted as a counter. Count in l/.

P is a reset signal for this counter l/, and 12 latches hold the number of pulses of the oscillator 10 from the rising edge 9 of Pa to the rising edge of Pa.

The microprocessor 13 calculates the value Ln of this latch, the value Ln-0 of the previous latch, the number of poles P of the resolver, the excitation period Ta2, and the pulse period T of the oscillator 10. , l The speed N of the motor can be determined by the number of pulses of the oscillator 10 between samplings.

The flowchart of the microprocessor 13 at this time is shown in steps t/-IAB of FIG.

The speed signal obtained by this resolver speed detection device does not include speed ripples due to amplitude changes, resulting in a signal with few ripples.

〔Effect of the invention〕

Thus, according to the present invention, in a motor speed control system that uses a resolver as a speed detector, an amplifier whose gain can be changed depending on the voltage is used to change the gain of the amplifier according to the amplitude of the resolver detection signal to detect the resolver detection signal. By keeping the amplitude constant and reducing the speed ripple of the speed detection my, a highly accurate electric signal can be obtained. ! TII aircraft speed control can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the circuit configuration in an embodiment of the present invention, FIG. 2 is a detailed diagram of the constant amplitude circuit, FIG. 3 is an input/output waveform diagram, and FIG. v is a flowchart of the microprocessor. FIG. 3 is a block diagram of a speed control system of a general electric motor, and the second figure is a diagram of speed detection waveforms of resolvers. l... Dry nose, Ko... Electric motor, 3... Speed detection device, Hiro... Controller, j... Excitation circuit,
t... Resolvers, 7... Constant amplitude circuit, Zari...
... Shaping circuit, 10... Oscillator, //... Counter 1, /:2... Latte, /3... Microprocessor, /Hiro... Analog multiplier, /S... Absolute Value circuit, /6...notch filter, 17...subtractor, l
Well...proportional + precision circuit. Applicant's agent Kiyoshi Inomata Figure 1 Figure 6

Claims (1)

[Claims] 1. In a motor speed control system using a resolver as a speed detector, a means for correcting the resolver detection signal to a constant amplitude is provided, and after passing through the correction means, the resolver detection signal is shaped and A resolver speed detection device characterized by measuring a speed signal and detecting a speed signal.