JPH0789067B2 - Resolver / digital converter - Google Patents

Description

The present invention relates to a resolver-to-digital converter that converts an angle detection output signal based on a trigonometric function value of a resolver into a digitally displayed angle value.

[Conventional technology]

Resolvers are widely used as rotation amount detection devices for motors, machine tools, and various measuring devices. A resolver is a device that is attached to a rotating shaft and converts the mechanical rotation amount of the rotating shaft into an electric signal. Since the output signal of the resolver has a trigonometric function value according to the rotation angle, when the resolver is used as an actual rotation angle measuring device or a machine position control device, an analog output signal based on the trigonometric function value of the resolver is used as a resolver digital value. Conversion to digitally displayed angle data is performed by a converter.

FIG. 3 is a circuit diagram showing an example of a conventional resolver / digital converter, and shows an example in which an inductive type of 1-phase excitation 2-phase output is used as a resolver.

In the figure, 1 is a resolver and 2 is a resolver / digital converter. The resolver-to-digital converter 2 comprises an oscillator circuit (OSC) 5 and a PLL circuit 6, and the resolver 1
Comprises a primary winding 3 provided on the stator and secondary windings 4a and 4b provided on the rotor.

In such a configuration, E = co output from the oscillation circuit 5
When an alternating current excitation of sω t is performed on the resolver 1, S ₁ = E sin θ and S ₂ on the output side according to the rotation angle θ of the rotor.
= Ecos θ is obtained, and these output signals are input to the PLL circuit 6 of the resolver / digital converter 2. In the PLL circuit 6, the output signal E of the oscillation circuit 5 is input as a synchronous rectification signal, and the output signal of the resolver 1 is synchronously rectified by this synchronous rectification signal to remove the carrier component E and obtain the rotation angle data θ of the rotor. .

FIG. 4 is a block diagram showing a general configuration of the PLL circuit 6. Reference numerals 33 and 34 denote amplifiers, which amplify the signals S ₁ and S ₂ input to the input terminals 30 and 31, respectively. 35 and 36 are multipliers.
35 multiplies the signal S ₁ by cos φ output from the function generator 43, and the multiplier 36 si outputs the signal S _{2 from} the function generator 43.
Multiply by nφ. 37 is a subtractor, and the output of the multiplier 35 is S ₁ cos
φ (= E sin θcos φ) to output of multiplier 36 S ₂ sin φ (= Ec
osθsinφ) is reduced. That is, the subtractor 37 outputs E = (sin θcos φ−cos θ sin φ) = E (sin θ−φ). A synchronous rectification circuit 38 synchronously rectifies the output E (sin θ−φ) of the subtractor 37 with the synchronous rectification signal input from the terminal 32 to take out θ−φ. 39 is a low pass filter, 40 is a voltage controlled oscillator (VCO), and the VCO 40 outputs a signal f having a frequency corresponding to the output of the low pass filter 39. Reference numeral 41 is an up / down counter, and a polarity determination circuit 42
The count-up or the count-down is selected according to the output of the signal, and the pulse input of the signal f is counted. In addition,
The polarity discriminating circuit 42 corresponds to the polarity of the low pass filter 39.
Output a value signal. Reference numeral 43 is a function generator in which sin φ and cos φ are stored, and the count value φ of the up / down counter is used as an address input.

Since the PLL circuit 6 configured in this way operates so that φ = θ, the output φ of the up / down counter 41 is
This indicates the rotation angle θ of the rotor to be detected.

By the way, the output signal of the resolver S ₁ = E sin θ and S ₂ =
Ecos θ is just a theoretical value, and in reality, the sin wave and the cos wave include harmonics depending on the influence of the mechanical shape of the resolver 1 and the winding condition. Then, this harmonic appears as an error of the detection angle θ as a function error. In order to solve this problem, the resolver 1 is processed with high accuracy, and the use of the winding is carefully examined to remove the harmonic component from the output of the resolver 1 and bring it closer to the theoretical value. I was trying.

[Problems to be Solved by the Invention] However, high-precision processing and careful assembly will significantly raise the cost of the resolver, in other words, a problem that an inexpensive resolver cannot provide sufficient accuracy. was there.

[Means for solving problems]

The resolver-digital converter of the present invention has been made in view of the above problems, and has a signal S _{1 including} a function Fs (θ) in which sin θ is a fundamental wave and harmonic components are added to this fundamental wave. And a resolver that outputs a signal S ₂ that has a function Fc (θ) in which cos θ is the fundamental wave and harmonic components are added to this fundamental wave, the functions Fs (φ) and Fc (φ) With a built-in function generator for storing
A calculation is performed on S ₁ and S _{2 as} S ₁ · Fc (φ) −S ₂ · Fs (φ), and a PLL circuit is provided to change the value of φ so that the calculation result becomes zero. The angle φ output from the PLL circuit is used as the detection angle.

[Action]

Even if the resolver output information Fs (θ) and Fc (θ) include harmonic components, when the calculation result of S ₁ · Fc (φ) −S ₂ · Fs (φ) becomes zero, θ = φ Therefore, the value of the detected angle φ output from the PLL circuit accurately indicates the value of θ.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples. FIG. 1 is a block diagram showing an embodiment of the resolver / digital converter of the present invention, and the internal configuration of the PLL circuit 10 is different from that of the conventional PLL circuit 6 shown in FIG. Figure 2 shows the PLL circuit.
10 is a block diagram showing the configuration of 10, in which the function stored in the function generator 11 is different from the function stored in the function generator 43 of FIG. 4. FIG.

In FIG. 1, the resolver 1 is a conventional conventional one which is the same as that shown in FIG.
The sin wave and the cos wave each include a harmonic component as described above. For the sake of simplicity, assuming that only the double harmonic is included, the output signals S ₁ and S _{2 of the} resolver 1
Respectively, S ₁ = E · Fs (θ) = E (sinθ + a sin2θ) = cosωt (sinθ + a sin2θ) S ₂ = E · Fc (θ) = E (cosθ + b cos2θ) = cosωt (cosθ + b cos2θ).

On the other hand, the function generator 11 provided in the PLL circuit 10 stores the function Fs (φ) = (sinφ + a sin2φ) Fc (φ) = (cosφ + b cos2φ), and the multiplier 35 stores Fs (θ ) × Fc (φ) is executed, and in the multiplier 36
The calculation Fc (θ) × Fs (φ) is executed. Therefore, the output A of the multiplier 35 is A = Fs (θ) × Fs (φ) = E (sinθ + a sin2θ) (cosφ + a cos2φ) = E {sinθcosφ + b sinθcos2φ + a sin2θcosφ + a b sin2θcos2φ}, and the output B of the multiplier 36 is , B = Fc (θ) × Fs (φ) = E (cosθ + a cos2θ) (sinφ + a sin2φ) = E {cosθsinφ + b cosθsin2φ + a cos2θsinφ + a b cos2θsin2φ}.

The output signals A and B of the multipliers 35 and 36 are input to the subtractor 37, respectively, and the operation AB is executed. Therefore, the subtractor
The output C of 37 is Becomes

In the above equation, if φ = θ, then sin (θ−φ) = 0 and C = 0.

On the other hand, the PLL circuit 10 has C =
Since it works so as to be 0, θ = φ when the PLL operation is stationary.

In the description of the present embodiment, the proof of the second harmonic is performed, but in general, the same is true for the nth harmonic (n is a natural number).

Since an inductive type resolver is used in this embodiment, the output signal of the resolver is the signal component Fs in the carrier E.
(Θ), Fc (θ) are listed, but the signal component Fs such as optical type, magnetic type or resistance type
The present invention can be similarly applied to the case where (θ) and Fs (θ) are output signals as they are. This can be similarly proved only by removing the carrier component E in the above proof formula.

Further, the detected angle does not necessarily mean mechanical rotation. For example, in the case of a linear resolver,
Although the linear position is output by a trigonometric function, the resolver-digital converter of the present invention can be applied to such a resolver.

〔The invention's effect〕

As described above, according to the resolver / digital converter of the present invention, even if the harmonic components are included in Fs (θ) and Fc (θ), S ₁ · Fc (φ) −S ₂ · Fs When the calculated result of (φ) becomes zero, θ = φ. That is, the angle θ can be accurately detected even with respect to the resolver output containing the harmonic. Therefore, the resolver does not require high-precision processing or precise assembly, and the angle θ is sufficiently accurate even when an inexpensive resolver is used.
Can be detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a PLL circuit 10 in the present embodiment,
FIG. 3 is a block diagram showing a conventional resolver / digital converter, and FIG. 4 is a block diagram showing a configuration of a PLL circuit 6 used therein. 1 ... resolver, 2 ... resolver / digital converter, 5
...... Oscillation circuit, 10 …… PLL circuit, 11 …… Function generator.

Claims (1)

[Claims] _{1. A} signal S ₁ having a function Fs (θ) in which sin θ is a fundamental wave and a harmonic component is added to this fundamental wave, and co
Stores the functions Fs (φ) and Fc (φ) for a resolver that outputs a signal S ₂ that has a function Fc (θ) in which sθ is the fundamental wave and harmonic components are added to this fundamental wave. With a built-in function generator for inputting the signals S ₁ and S ₂
S ₁ · Fc (φ) − S ₂ · Fs (φ) is applied to the output, and the output of the PLL circuit is equipped with a PLL circuit that changes the value of φ so that the result of this operation becomes zero. Resolver / digital converter with angle φ as detection angle.