JP4470804B2 - Resolver / digital conversion circuit - Google Patents

Description

  The present invention relates to a resolver / digital conversion circuit suitable for a plurality of resolvers having different transformation ratios.

  When a resolver is used as a position detector, a resolver / digital conversion circuit using a tracking method is generally used, and the configuration is a sine wave excitation signal having a constant frequency and a constant amplitude A from an excitation circuit 212 as shown in FIG. Asinωt is output to the resolver 201 and the demodulator 207, and KAsinθ · sinωt and KAcosθ · sinωt corresponding to the transformer ratio of the resolver and the rotor angle θ of the resolver are output from the resolver 201 and amplified by the amplifiers 202 and 203. Here, K is a transformation ratio of the resolver. The sin φ generated by the inside of the converter is multiplied by KA sin θ · sin ωt by the multiplier 204, and cos φ is multiplied by KA cos θ · sin ωt by the multiplier 205, and subtraction is performed by the subtracter 206, whereby KA sin (θ−φ) · sin ωt is obtained. Then, sin ωt, which is an excitation component, is removed by the demodulator 207, and the harmonic component is removed by passing through the low-pass filter 208 to generate θ−φ.

  The θ-φ is input to the voltage controlled oscillator 209, and the voltage controlled oscillator 209 generates a pulse corresponding to the input voltage, and the pulse is input to the UP / DOWN counter 210. A kind of PLL servo loop in which sin φ and cos φ are generated by referring to the SIN and COS table 211 having the counter value of the counter 210 as an address, and the sin φ and cos φ are hooded back to the multipliers 204 and 205 is provided. Thus, the angle data φ can be obtained when θ−φ = 0 by operating θ−φ toward 0 (see, for example, Patent Document 1).

However, in the conventional method, when multiple resolvers with different transformation ratios are supported by the same resolver / digital conversion circuit, the number of resolver models has increased because it is necessary to adjust the gain of the resolver excitation circuit according to the resolver. In this case, adjustment on the circuit side or the number of circuit board models increases, and an increase in the number of management man-hours due to the increase in the model becomes a problem. As for a fail-safe function such as detection of resolver disconnection, a general method is to obtain KA from KA (sin θ · sin φ + cos θ · cos φ) · sin ωt and output an error flag when KA exceeds a certain threshold value. Although it is used, if the resolver's transformation ratio varies and the margin for the KA threshold varies, a phenomenon occurs in which the error sensitivity varies depending on the resolver model.
JP-A-63-71618

  The problem to be solved is that, when a conventional resolver / digital conversion circuit is applied to a plurality of resolvers having different transformation ratios, an error occurs in a calculation result, and error sensitivity varies.

  That is, the resolver / digital conversion circuit according to the conventional tracking method has a problem because the calculation result by the error calculator differs depending on the transformation ratio, and an error occurs in the calculation result.

SUMMARY OF THE INVENTION An object of the present invention is to provide a resolver / digital conversion circuit capable of configuring a system with a single circuit for resolvers having different transformation ratios.

  In order to solve the above-described problems, the present invention provides an excitation circuit for inputting an excitation signal Asinωt having an amplitude A to a resolver having a transformation ratio K of a single-phase excitation and two-phase output type, and sinθ corresponding to the rotation angle θ of the resolver. A first multiplier that multiplies KAsinθ · sinωt, which is an amplitude-modulated resolver output signal, by cosφ generated within the conversion circuit, and KAcosθ · sinωt, which is another output signal corresponding to the rotation angle θ of the resolver. And a second multiplier that multiplies sinφ generated in the conversion circuit, a subtracter that divides the operation results of the first and second multipliers, and the first and second multipliers and subtractors. A demodulator that removes the excitation signal component from the computed result, a low-pass filter that removes the harmonic component from the signal output from the demodulator, and a signal that has passed through the low-pass filter. In a resolver / digital conversion circuit of a tracking system, comprising: a voltage-controlled oscillator that outputs a pulse as an input signal; a counter that counts output pulses of the voltage-controlled oscillator; and a sin and cos reference ROM that has a counter value as an address. A third multiplier for multiplying the resolver output signal amplitude-modulated to sin θ corresponding to the rotation angle θ output from the output signal, and a resolver output signal amplitude-modulated to cos θ into the resolver output signal inside the conversion circuit From the signal calculated by the fourth multiplier that multiplies cosφ generated in step 3, the adder that adds the operation results of the third and fourth multipliers, and the signals calculated by the third and fourth multipliers and the adder. A second demodulator that removes the excitation signal component and a divider that removes the amplitude component of the excitation signal from the signal output from the second demodulator. Comprising a Luba transformation ratio detecting means, indexing the transformation ratio of the resolver, and fed back to the resolver excitation circuit, a resolver / digital converter circuit and wherein the adjusting the gain of the excitation signal.

  The calculated transformation ratio of the resolver is stored in the nonvolatile storage means via the CPU, and when the system power supply such as the servo amplifier is turned on, the transformation ratio stored in the nonvolatile storage means is stored in a register inside the CPU. The value is held, and the value is output to the gain adjusting means in the excitation circuit.

  According to the present invention, a resolver / digital conversion circuit can be configured with a single circuit for a plurality of resolvers having different transformation ratios.

An excitation circuit for inputting an excitation signal Asinωt having an amplitude A to a resolver having a transformation ratio K of a one-phase excitation and two-phase output type, and a resolver output signal KAsinθ · that is amplitude-modulated to sinθ corresponding to the rotation angle θ of the resolver. A first multiplier that multiplies sin ωt with cos φ generated inside the conversion circuit, and a second output signal KAcos θ · sin ωt corresponding to the rotation angle θ of the resolver is multiplied by sin φ generated inside the conversion circuit. Two multipliers, a subtracter that divides the calculation results of the first and second multipliers, and an excitation signal component from the calculation results calculated by the first and second multipliers and subtractors. A demodulator, a low-pass filter that removes harmonic components from the signal output from the demodulator, and a signal that outputs a pulse using the signal that has passed through the low-pass filter as an input signal. In a tracking type resolver / digital conversion circuit including a controlled oscillator, a counter for counting output pulses of the voltage controlled oscillator, and a sin and cos reference ROM having the counter value as an address, according to a rotation angle θ output from the resolver A third multiplier for multiplying the resolver output signal amplitude-modulated by sin θ by the sin φ generated in the conversion circuit, and a fourth multiplier for multiplying the resolver output signal amplitude-modulated by cos θ by the cos φ generated by the conversion circuit. A multiplier that adds the operation results of the third and fourth multipliers, and a second that removes excitation signal components from the signals calculated by the third and fourth multipliers and adders. A resolver transformer ratio detecting means comprising a demodulator and a divider for removing the amplitude component of the excitation signal from the signal output from the second demodulator; A resolver / digital conversion circuit characterized by determining a transformation ratio, feeding back to a resolver excitation circuit, and adjusting a gain of an excitation signal. The third and fourth multipliers convert sinφ into sinθ · sinωt, cosθ · By multiplying sinωt by cosφ and adding each by an adder, KA (sinθ · sinφ + cosθ · cosφ) · sinωt is generated, that is, KA · sinωt is generated, and KA obtained by multiplying the amplitude and the transformation ratio by the demodulator is divided. The transformer ratio K is determined by the device. The transformation ratio K is fed back to the resolver excitation circuit via the CPU, and the gain of the excitation circuit is automatically adjusted to a certain target value.

  The resolver / digital conversion circuit according to the first embodiment obtains a transformation ratio of a resolver using a multiplier, an adder, a demodulator, and a divider, and automatically adjusts the gain of the excitation circuit using the value.

  In FIG. 1, by inputting an excitation signal Asinωt having a constant frequency and a constant amplitude from an excitation circuit 112 to a resolver 101 having a single-phase excitation and two-phase output, output signals sinθ · sinωt and cosθ · sinωt are obtained from the resolver 101. Cos φ and sin φ generated from the angle φ generated in the conversion circuit in each output signal are multiplied by the multipliers 104 and 105 and the multipliers 114 and 115, respectively. (Sin θ · sin φ + cos θ · cos φ) · sin ωt is calculated.

  The signal output from the demodulator 107 that removes the excitation signal component from the signal KA (sin θ · cos φ−cos θ · sin φ) · sin ωt, the low-pass filter 108 that removes the harmonic component of the output signal from the demodulator 107, and the signal output from the low-pass filter 108 Refer to voltage controlled oscillator 109 that generates proportional pulses, UP / DOWN counter 110 that counts pulses output from voltage controlled oscillator 109, and sinφ and cosφ that are addressed by the count data of the UP / DOWN counter. SIN, COS table 111, demodulator 117 for removing excitation signal components from signals KA (sinθ · sinφ + cosθ · cosφ) · sinωt, and divider 118 for dividing the amplitude value of the excitation signal from KA output from the demodulator. Is done.

  The transformation ratio information of the resolver 101 output from the divider 118 is output to the CPU 113, and is used as a control signal for gain adjustment of the excitation amplifier of the excitation circuit 112 after the arithmetic processing by the CPU 113.

  Further, the transformation ratio information of the resolver 101 is stored in the nonvolatile storage means 119 via the CPU 113, and the transformation ratio information of the resolver 101 is saved at the time of starting up the servo amplifier or the like on which the present system is mounted. From this, the gain of the excitation circuit 112 can be determined using the current transformation ratio information.

  Further, the output signal amplitude of the resolver 101 becomes constant regardless of the type of the resolver 101 based on the transformation ratio information calculated using the multiplier 114, the multiplier 115, the adder 115, the demodulator 117, and the divider 118. Therefore, even if the disconnection detection threshold value of the resolver 101 is a fixed value, the relationship between the output signal amplitude of the resolver 101 and the disconnection detection threshold value is always constant, so that the disconnection detection can be performed with high accuracy.

  The resolver / digital conversion circuit of the present invention is useful for standardization of motor control devices having different resolver transformation ratios that require high reliability under adverse environments such as robots.

Explanatory drawing of the resolver / digital conversion circuit in Example 1 of this invention Illustration of a conventional resolver / digital conversion circuit

Explanation of symbols

101, 201 Resolver 102, 202 First amplifier 103, 203 Second amplifier 104, 204 First multiplier 105, 205 Second multiplier 106, 206 Subtractor 107, 207 First demodulator 108, 208 Low pass filter 109, 209 Voltage controlled oscillator 110, 210 UP / DOWN counter 111, 211 SIN, COS table 112, 212 Excitation circuit 113, 213 CPU
114 Third multiplier 115 Fourth multiplier 116 Adder 117 Second demodulator 118 Divider 119 Non-volatile storage means

Claims (3)

An excitation circuit for inputting an excitation signal Asinωt having an amplitude A to a resolver having a transformation ratio K of a one-phase excitation and two-phase output type, and a resolver output signal KAsinθ · that is amplitude-modulated to sinθ corresponding to the rotation angle θ of the resolver. A first multiplier that multiplies sin ωt with cos φ generated inside the conversion circuit, and a second output signal KAcos θ · sin ωt corresponding to the rotation angle θ of the resolver is multiplied by sin φ generated inside the conversion circuit. Two multipliers, a subtracter that divides the calculation results of the first and second multipliers, and an excitation signal component from the calculation results calculated by the first and second multipliers and subtractors. A demodulator, a low-pass filter that removes harmonic components from the signal output from the demodulator, and a signal that outputs a pulse using the signal that has passed through the low-pass filter as an input signal. In a tracking type resolver / digital conversion circuit including a controlled oscillator, a counter for counting output pulses of the voltage controlled oscillator, and a sin and cos reference ROM having the counter value as an address, according to a rotation angle θ output from the resolver A third multiplier for multiplying the resolver output signal amplitude-modulated by sin θ by the sin φ generated in the conversion circuit, and a fourth multiplier for multiplying the resolver output signal amplitude-modulated by cos θ by the cos φ generated by the conversion circuit. A multiplier that adds the operation results of the third and fourth multipliers, and a second that removes excitation signal components from the signals calculated by the third and fourth multipliers and adders. A resolver transformer ratio detecting means comprising a demodulator and a divider for removing the amplitude component of the excitation signal from the signal output from the second demodulator; Indexing the transformation ratio, and fed back to the resolver excitation circuit, a resolver / digital converter circuit and wherein the adjusting the gain of the excitation signal. The calculated transformation ratio of the resolver is stored in the nonvolatile storage means via the CPU, and when the system power supply such as the servo amplifier is turned on, the transformation ratio stored in the nonvolatile storage means is held in a register inside the CPU. 2. The resolver / digital conversion circuit according to claim 1, wherein the value is output to a gain adjusting means in the excitation circuit. The resolver / digital conversion circuit according to claim 1, wherein a disconnection detection threshold value of the resolver is set in accordance with the transform ratio information of the resolver.

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