JPS62148814A - Temperature compensating method for resolver - Google Patents

Abstract

PURPOSE:To perform high-accuracy position detection without lowering the position resolution of a resolver by adding a voltage corresponding to temperature to the comparison level of a comparator for shaping a detection signal into a rectangular wave and thus shifting the detection signal and shaped signal in phase. CONSTITUTION:When a position signal is detected from a resolver 2, a counter 8 is reset with the leading (trailing) edge of a pulse Pr obtained by synchronizing an exciting signal Vo sinomegat with pulses of an oscillator and the counted value of the counter is latched with the leading (trailing) edge of a pulse Ps obtained by synchronizing the detection signal Vo sin (omegat+theta) with the pulses of the oscillator 5. The pulse Pr and output Ps, however, become out of phase owing to variation in the temperature of winding in this state. For the purpose, the output of a thermistor linearizer 10 is offset to the comparison level of the comparator 11 and applied and resistance variation of a thermistor with temperature becomes offset variation in the comparison level of the comparator 11, thereby shifting the phase of the output waveform of a shaping circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for correcting position detection errors due to temperature changes in the windings of a resolver when a resolver is used as a position detector in positioning control of an electric motor.

[Conventional technology]

Conventionally, when correcting a position detection error due to resolver temperature, first the resolver winding IU degree is detected, the phase shift due to temperature change is measured, and a correction value for temperature is determined.

When correcting the position detection value of the resolver, it can be obtained by detecting the resolver winding temperature and subtracting the correction value for the temperature from the resolver position detection value.

[Problem that the invention seeks to solve]

However, in the conventional method, the minimum unit of the correction value is the same as the resolver resolution, so if the correction value changes by one due to a temperature change, the position detection value after correction will change by one even though the detection axis is stationary. It will change.

For this reason, the positional resolution used for control had to be lowered.

Here, an object of the present invention is to propose a method that can perform highly accurate positioning control by correcting without lowering the position resolution of the resolver.

[Means for solving problems]

The present invention provides a circuit that adds a two-phase sine wave with a 90 degree phase difference as an excitation signal to a resolver and measures the phase of a sine wave detection signal and an excitation signal that are phase-modulated according to the rotation angle of a detection shaft. By applying a voltage corresponding to the temperature to the comparator level of the comparator for shaping the detection signal into a square wave, the phases of the detection signal and the shaped signal are changed.

[For production]

As a result, the position is detected at a temperature level corresponding to the resolver winding temperature, so correction can be performed with a resolution higher than the position detection resolution of the resolver.

Therefore, it is possible to perform highly accurate position detection without lowering the position resolution of the resolver.

〔Example〕

FIG. 1 shows a block diagram showing a circuit configuration in an embodiment of the present invention.

1 is V. Sinωt, VoCO8ωt [V here.

is the voltage amplitude value, ω = 2πf, and f is the excitation frequency.

t is time] is a two-phase excitation signal generator that generates an excitation signal, 2 is a resolver, and the detection signal is a signal V that is phase-modulated with respect to the excitation signal according to the rotational position θ of the detection shaft.
'5in (ω = 10) [However, V. ° is the voltage amplitude value] is output.

3.4 is the excitation signal ■. sinωt, detection signal V'5
in (ω = 10) A shaping circuit that shapes these sine waves into square waves, 5 an oscillator that oscillates at a sufficiently fast frequency with respect to the excitation signal, and 6.7 an oscillator that receives the signal shaped by the shaping circuit 3.4. A synchronization circuit for synchronizing with the oscillation pulse of No. 5,
8 is a counter circuit that counts the clock of the oscillator 5, and 9 is the rise (or fall) of the output signal of the synchronization circuit 7.
This is a latch circuit that latches the count value of the counter 8 by etching.

10 is a thermistor linearizer that converts the resistance change of a thermistor embedded near the winding of the resolver 2 into a voltage proportional to temperature.

To detect the position signal from the resolver 2 using these,
Excitation signal ■. The counter circuit 8 is reset by the rising (or falling) edge of the pulse P, which synchronizes sjnωt with the pulse of the oscillator 5.

Then, the count value of the counter is latched by the rising (or falling) edge of the pulse PS synchronized with the pulse of the oscillator 5 with the detection signal V'5in (ω = 10).

From this latch value, the rotation angle θ can be determined using the following equation.

θ-2πx −(r a d ) where N is the excitation signal V. It represents the number of pulses output by the oscillator 5 in one period of sinωt.

However, if this continues, the phases of the pulses P and P will shift due to temperature changes in the windings even though the rotating shaft is stationary.

Therefore, perform the following operations.

FIG. 2 is a detailed wiring diagram of the shaping circuit 4.

The output of the thermistor linearizer 10 is the comparator 1
It is added as an offset to the comparator level of 1.

A time course diagram of each waveform of the shaping circuit 4 is shown in FIG.

Due to temperature change (resistance change of the thermistor causes an offset change in the comparator level of the comparator 11, and as a result, the phase of the output waveform of the shaping circuit 4 can be changed. When the comparator level is 1, fJ2.IJ3
Since it changes with temperature, the output P changes the phase as shown in 1.1.13.

By making adjustments so that the phase shift between pulses P and P8 due to temperature changes in the windings and the phase shift due to changes in the offset level to the comparator level are canceled out, temperature changes in the windings can be canceled out. It is possible to eliminate the phase shift caused by

〔Effect of the invention〕

Thus, according to the present invention, the temperature of the resolver winding m is detected;
By changing the offset level of the comparator level according to this temperature so that the phase shift due to winding temperature changes and the phase shift due to changes in the comparator level offset height cancel each other out, correction can be performed with high precision. , correction is possible without lowering the position resolution.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the circuit configuration of the present invention, FIG. 2 is a wiring diagram of the shaping circuit, and FIG. 3 is a time chart 1 of the output phase of the shaping circuit 4 corresponding to the comparator level. 1... Two-phase excitation signal generator 2... Resolver 3... Shaping circuit 4... Shaping circuit 5 which changes the comparator level in response to the thermistor linearizer output... Oscillator 6.7...・Synchronous circuit 8... Counter circuit 9... Latch circuit 10... Thermistor linear liner 1F-0 Applicant's representative Mr. Sato - Figure 2

Claims (1)

[Claims] 1. A position detection device using a resolver, comprising: a two-phase excitation signal generating means with a 90 degree phase difference; a comparator circuit for shaping the resolver detection signal into a square wave; means for measuring the phase difference with the square wave signal; and means for detecting the resolver winding temperature. A resolver temperature correction method that is characterized by canceling out a phase shift between an excitation signal and a detection signal due to a winding temperature change, and a phase shift caused by a change in a comparator level due to a change in winding temperature.