JP2010164451A - Resolver digital converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve angle resolution while suppressing an increase in the amount of stored data. <P>SOLUTION: The resolver digital converter includes: a first conversion means converting a sin-phase signal input from a resolver into a bit stream signal; a first multiplication means multiplying an output of the first conversion means by cosine of the angle signal as a plurality of data in which time distribution ratio is determined; a first digital filter demodulating an output of the first multiplication means into a digital signal; a second conversion means converting a cos-phase signal input from the resolver into a bit stream signal; a second multiplication means multiplying an output of the second conversion means by sine of the angle signal as a plurality of data in which time distribution ratio is determined; a second digital filter demodulating an output of the second multiplication means into a digital signal; and an angle signal determination means determining the angle signal by a tracking system using the output of the first and second digital filters. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resolver / digital converter that outputs an angle signal based on a sin phase signal and a cos phase signal input from a resolver.

  Conventionally, a variable reluctance type (VR type) resolver that detects a rotation angle of a rotor by detecting a distance between a rotor having a non-circular portion and a stator by a magnetic method has been widely used. In a variable reluctance type (VR type) resolver, an exciting coil and a detecting coil are arranged on the stator so as to be aligned along the circumferential direction of the rotor, and a change in magnetic resistance caused by a change in the distance from the rotor is detected. By doing so, the rotation angle of the rotor is detected. The detection coil is a sin-phase detection coil wound so as to obtain an output (sin phase signal) proportional to the rotor rotation angle sin, and an output (cos phase) proportional to the rotor rotation angle cos. A cos phase detection coil wound so as to obtain a The application target of the present invention is not limited to a variable reluctance type (VR type) resolver, but can be applied to any resolver that outputs a sin phase signal and a cos phase signal.

  The sin-phase signal and the cos-phase signal output in this way are converted into angle signals by a resolver digital converter. An invention relating to a digital conversion method of an analog signal related to this is disclosed (for example, see Patent Document 1). In this method, a rotation angle detection signal (sin phase signal and cos phase signal) is introduced into a multiplying D / A converter and subjected to mutual detection with a cosine and a sine of a digital angle output, followed by synchronous detection and control deviation. Seeking. Then, the digital angle output is determined so that the control deviation approaches the value zero. Such a method is called a tracking method.

JP 2000-353957 A

  By the way, in the above conventional method, the cosine and sine of the digital angle output are read from the ROM data, and the 360 ° angle is divided into four to obtain the 12-bit angular resolution from the 10-bit data. . However, no consideration is given to further improving the angular resolution, and in order to improve the 1-bit resolution, the data amount is doubled.

  The present invention is intended to solve such problems, and a main object thereof is to provide a resolver / digital converter capable of improving angular resolution while suppressing an increase in the amount of data to be stored. .

In order to achieve the above object, the first aspect of the present invention provides:
First conversion means for converting a sin-phase signal input from a resolver into a bit stream signal;
First multiplication means for multiplying the output of the first conversion means by a cosine of an angle signal expressed by a plurality of data having a determined time distribution ratio;
A first digital filter that demodulates the output of the first multiplication means into a digital signal;
Second conversion means for converting a cos-phase signal input from the resolver into a bit stream signal;
Second multiplying means for multiplying the output of the second converting means by the sine of an angle signal represented by a plurality of data having a determined time distribution ratio;
A second digital filter for demodulating the output of the second multiplication means into a digital signal;
Angle signal determining means for determining and outputting an angle signal by a tracking method using outputs of the first digital filter and the second digital filter;
It is a resolver digital converter provided with.

  According to the first aspect of the present invention, the sine and cosine of the angle signal expressed by a plurality of data whose time distribution ratio is determined are demodulated by the digital filter, and linear interpolation is performed between the plurality of data. Since the same result is obtained, the angular resolution can be improved while suppressing an increase in the amount of data to be stored.

  ADVANTAGE OF THE INVENTION According to this invention, the resolver digital converter which can improve an angular resolution, suppressing the increase in the data amount to store can be provided.

1 is a system configuration example of a resolver / digital converter 1 according to a first embodiment of the present invention. It is a figure which shows together the time change of the signal input into the delta-sigma modulators 10 and 20, and the time change of the bit stream signal which the delta-sigma modulators 10 and 20 output. It is explanatory drawing for demonstrating the process which the data selector 11B outputs the signal which shows cos (phi).

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.

  Hereinafter, a resolver / digital converter 1 according to an embodiment of the present invention will be described. FIG. 1 is a system configuration example of a resolver / digital converter 1 according to an embodiment of the present invention. A resolver 100 is connected to the resolver / digital converter 1. The resolver / digital converter 1 is a device that outputs an angle signal φ based on a sin phase signal and a cos phase signal input from the resolver 100.

  First, the configuration and function of the resolver 100 will be outlined. The resolver 100 is a variable reluctance resolver, for example, and is attached to a rotating body such as an electric motor. The resolver 100 includes a rotor that rotates integrally with an attached rotating body, and a stator that is used while being fixed to a case or the like. The rotor is coupled to the stator by a bearing or the like so as to be relatively rotatable. The outer contour of the rotor is defined not by a constant diameter but by a periodically changing diameter. The stator is formed by laminating silicon steel plates, for example, has an annular shape facing the outer peripheral surface of the rotor, and is connected to the rotor so that the rotation center of the rotor coincides with the center of the stator.

A stator core (teeth) arranged along the circumferential direction of the rotor is formed on the stator so as to protrude on the side (inner side) facing the rotor. Each of the stator cores is wound with an excitation coil connected to the power supply device and a detection coil for converting the magnetic flux resistance to the generated magnetism into a voltage and outputting it to the resolver / digital converter 1. Thereby, a coil row in which a plurality of excitation coils and a plurality of detection coils are arranged along the circumferential direction of the rotor is arranged. An excitation coil and a detection coil are concentrically wound around each coil. The detection coil has a sin-phase detection coil wound so as to obtain an output proportional to sin θ (sin-phase signal) and an output proportional to cos θ (cos-phase A cos phase detection coil wound to obtain a signal. At both ends of the excitation coil, for example, several [kHz], the number [Vp _- p] of about AC is input. Each of the sin phase detection coil and the cos phase detection coil is connected to an input terminal of the resolver / digital converter 1.

When the excitation coil is excited and magnetism is generated, the detection coil generates electricity. When the rotor rotates due to an external force or the like, the interval between the detection coil and the rotor changes periodically, and accordingly, the magnetic flux resistance changes and the voltage induced in the detection coil changes. Assuming that the input voltage applied to both ends of the exciting coil is f (t), the output voltage E _SIN-GND of the sin phase detection coil is expressed by the following equation (1), and the output voltage of the cos phase detection coil: E _COS-GND is represented by the following formula (2), respectively. K is a constant, and α and β are phase differences. These parameters are determined by the number of exciting windings, the number of output windings, the shape and material of the rotor and stator, and the like. The input voltage f (t) is expressed as, for example, Esinωt.

E _SIN-GND = Ksinθ · f (t + α) (1)
E _COS-GND = K cos θ · f (t + β) (2)

  Hereinafter, the resolver / digital converter 1 will be described on the assumption of this. As shown in FIG. 1, the resolver / digital converter 1 includes, as main components, a delta-sigma modulator 10 and 20, a cosROM 11A and a data selector 11B, a sinROM 21A and a data selector 21B, multipliers 12 and 22, Filters 13 and 23, synchronous detection units 14 and 24, a subtractor 30, a counter circuit 32, and a detection signal generation unit 40 are provided.

  The delta sigma modulator 10 receives a sin phase signal sin θ · f (t + α), and the delta sigma modulator 20 receives a cos phase signal cos θ · f (t + β). Hereinafter, the aforementioned constant K is omitted. In addition, digital data is represented by {...} And bit stream data is represented by [.

  The delta-sigma modulators 10 and 20 perform pulse density modulation on the input signals and convert them into 1-bit bit stream signals [sin θ · f (t + α)] and [cos θ · f (t + β)], respectively. FIG. 2 is a diagram illustrating a time change of signals input to the delta sigma modulators 10 and 20 and a time change of the bit stream signal output from the delta sigma modulators 10 and 20 together. As illustrated, when pulse density modulation is performed, the higher the input signal value, the higher the Hi signal density, and the lower the input signal value, the higher the Lo signal density.

  The following configuration is for determining the angle signal by the tracking method using the outputs of the delta-sigma modulators 10 and 20.

  The output signal [sin θ · f (t + α)] of the delta sigma modulator 10 is multiplied by the output of the data selector 11B by the multiplier 12. The data selector 11B receives the angle signal φ output from the counter circuit 32 and the bit stream signal output from the delta sigma modulator 10, and receives a signal indicating cos φ with reference to the cos table stored in the cos ROM 11A. Output.

  In this embodiment, the cos table stored in the cos ROM 11A is stored as a combination of, for example, 10-bit label data and a cos angle corresponding to the label data. The angle signal φ output from the counter circuit 32 has a larger number of bits (for example, 12 bits) than the label data in the cos table. The data selector 11B uses the upper 10-bit value included in the angle signal φ as the search value of the cos table and the lower 2 bits as the time distribution ratio of the cos angle searched from the cos table.

  FIG. 3 is an explanatory diagram for explaining processing in which the data selector 11B outputs a signal indicating cos φ. The data selector 11B first calculates a value corresponding to the upper 10-bit value (data A) included in the angle signal φ and a value obtained by adding 1 to the value (data B; a value obtained by subtracting 1). Read from the table. Then, the data A and the data B are output to the multiplier 12 with the time distribution ratio indicated by the value of the lower 2 bits included in the angle signal φ. The time distribution ratio is realized by, for example, determining that one clock of the bit stream signal output from the delta-sigma modulator 10 is counted as one time, and outputting how many times the data A is output after the data A is output how many times. . In the example of FIG. 3, if the lower 2 bits are “01”, the use data ratio is “AAAB”, so that after data A is output three times, data B is output once.

  Accordingly, the multiplier 12 outputs a multi-bit bit stream signal [cos φ · sin θ · f (t + α)] in which data is selected by the time distribution ratio.

  The digital filter 13 applies a technique such as obtaining a moving average with respect to the output of the multiplier 12, and the output [cosφ · sinθ · f (t + α)] of the multiplier 12 is converted into digital data {cosφ · sinθ · f (t + α)}. Demodulate.

  By demodulating the bit stream signal controlled by the time distribution ratio by a method such as moving average, linear interpolation of data A and data B is performed at the ratio indicated by the value of the lower 2 bits included in the angle signal φ. Results similar to those performed are obtained. Therefore, 12-bit angular resolution can be obtained from 10-bit data. Further, if the number of lower bits included in the angle signal φ is increased, the angle resolution can be further improved without increasing the size of the cos table stored in the cos ROM 11A.

  On the other hand, the output signal [cos θ · f (t + β)] of the delta-sigma modulator 20 is multiplied by the output of the data selector 21B by the multiplier 22. The data selector 21B receives the angle signal φ output from the counter circuit 32 and the bit stream signal output from the delta-sigma modulator 20, and a signal indicating sin φ with reference to the sin table stored in the sin ROM 21A. Output.

  Similar to the cos table stored in the cos ROM 11A, the sin table stored in the sin ROM 21A is stored as a combination of, for example, 10-bit label data and a sin angle corresponding to the label data. The angle signal φ output from the counter circuit 32 has a larger number of bits than the label data of the sin table (for example, 12 bits). The data selector 21B uses the upper 10 bits included in the angle signal φ as the search value of the sin table, and uses the lower 2 bits as the time distribution ratio of the sin angle searched from the sin table.

  The data selector 21B performs a process similar to the process of the data selector 11B described with reference to FIG. 3, and outputs a signal indicating sinφ. The data selector 21B first calculates a value corresponding to the upper 10-bit value (data A) included in the angle signal φ and a value obtained by adding 1 to this (data B; a value obtained by subtracting 1). Read from the table. Then, the data A and the data B are output to the multiplier 12 with the time distribution ratio indicated by the value of the lower 2 bits included in the angle signal φ. The time allocation ratio is realized by, for example, determining that one clock of the bit stream signal output from the delta-sigma modulator 20 is counted as one time, and outputting how many times the data A is output after the data A is output how many times. .

  Therefore, the multiplier 22 outputs a multi-bit bit stream signal [sinφ · cos θ · f (t + β)] in which data is selected by the time distribution ratio.

  The digital filter 23 applies a technique such as obtaining a moving average with respect to the output of the multiplier 22, and the output [sinφ · cos θ · f (t + β)] of the multiplier 12 is converted into digital data {sinφ · cos θ · f (t + β)}. Demodulate.

  By demodulating the bit stream signal controlled by the time distribution ratio by a method such as moving average, linear interpolation of data A and data B is performed at the ratio indicated by the value of the lower 2 bits included in the angle signal φ. Results similar to those performed are obtained. Therefore, 12-bit angular resolution can be obtained from 10-bit data. Further, if the number of lower bits included in the angle signal φ is increased, the angular resolution can be further improved without increasing the size of the sin table stored in the sin ROM 21A.

  The synchronous detection unit 14 approximately divides the digital data {cosφ · sin θ · f (t + α)} by the reference data {F (t + α)} input from the detection signal generation unit 40 to approximate the excitation component of the resolver 100. Remove and output to the subtractor 30. Similarly, the synchronous detection unit 24 divides the digital data {sinφ · cos θ · f (t + β)} by the reference data {F (t + α)} input from the detection signal generation unit 40 to obtain the excitation component of the resolver 100. Approximate removal and output to the subtractor 30. The reference data {F (t + α)} is, for example, a binary signal having a value X and a value −X. Originally, the digital data is divided by a sine wave to remove the excitation component of the resolver 100. The positive part of the sine wave is the value X (Hi signal) and the negative part is the value -X (Lo signal). Even if it replaces with, it can remove an excitation component approximately. As the value X, for example, a value obtained by dividing an integral value of a sine wave from zero to π by a period π can be used.

  The subtractor 30 calculates the difference between the outputs of the synchronous detectors 14 and 24 and outputs a control deviation ε = sin (θ−φ).

  In the counter circuit 32, the angle signal φ is increased or decreased so that the control deviation ε approaches zero. In the control of the angle signal φ, a proportional component, an integral component, a temporary delay component, and the like may be considered.

  According to the resolver / digital converter 1 of the present embodiment described above, the angular resolution can be improved while suppressing an increase in the amount of data stored in the cosROM 11A and the sinROM 21A.

  The best mode for carrying out the present invention has been described above with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the present invention. And substitutions can be added.

  The present invention can be used in the automobile manufacturing industry, the automobile parts manufacturing industry, and the like.

1 Resolver / Digital Converter 10, 20 Delta Sigma Modulator 11A cosROM
11B, 21B Data selector 21A sinROM
12, 22 Multipliers 13, 23 Digital filters 14, 24 Synchronous detection unit 30 Subtractor 32 Counter circuit 40 Detection signal generation unit 100 Resolver

Claims (1)

First conversion means for converting a sin-phase signal input from a resolver into a bit stream signal;
First multiplication means for multiplying the output of the first conversion means by a cosine of an angle signal expressed by a plurality of data having a determined time distribution ratio;
A first digital filter for converting the output of the first multiplication means into a digital signal;
Second conversion means for converting a cos-phase signal input from the resolver into a bit stream signal;
Second multiplying means for multiplying the output of the second converting means by the sine of an angle signal represented by a plurality of data having a determined time distribution ratio;
A second digital filter for converting the output of the second multiplication means into a digital signal;
Angle signal determining means for determining and outputting an angle signal by a tracking method using outputs of the first digital filter and the second digital filter;
Resolver digital converter with.