JP5266783B2 - Rotation angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To absorb the variation of hardware while suppressing the increase in table capacity or arithmetic load. <P>SOLUTION: Detected signals sin &theta; and cos &theta; output from a resolver 13 are sampled at a period odd times that of the half wavelength &lambda;/2 of an excitation signal sin &omega;t (step S12). By the moment, based on the previous values sin &theta;<SB>(n-1)</SB>and cos &theta;<SB>(n-1)</SB>of the detected signal and the present values sin &theta;<SB>(n)</SB>and cos &theta;<SB>(n)</SB>, an intermediate rotation angle &phiv;<SB>(n)</SB>corresponding to an intermediate position between the rotation angle &theta;<SB>(n-1)</SB>at the previous sampling time and the rotation angle &theta;<SB>(n)</SB>at the present sampling time is calculated (step S15). By adding to the present value &phiv;<SB>(n)</SB>one half of the difference between the previous angle &phiv;<SB>(n-1)</SB>and the present value &phiv;<SB>(n)</SB>at the intermediate angle, the present rotation angle &theta;<SB>(n)</SB>is calculated (steps S23-S29). <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle by a one-phase excitation two-phase output type resolver.

Detects the rotor's sinθ and cosθ, which are the output signals of the resolver, and repeatedly executes the convergence calculation, and detects the rotation angle corresponding to the convergence value while referring to the pre-stored search table of sinθ / (sinθ + cosθ) (See Patent Document 1).
In addition, the reference signals sinθ and cosθ are generated from the output signal of the resolver by least square approximation, and the sampling timing of the output signal is controlled so that the sum of sinθ × cosθ becomes 0, and the amplitude of the reference signals sinθ and cosθ is set. Based on this, there is one that calculates the phase shift amount of the output signal (see Patent Document 2).
JP-A-9-14906 JP 2003-97974 A

However, due to variations in hardware, an error may occur in the amplitude center of sinθ and cosθ (reference voltage division), and in order to absorb this, in the case of the conventional technique described in Patent Document 1, search is performed. Since a high resolution is required for the table, the storage capacity is increased.
On the other hand, in the prior art described in the above-mentioned Patent Document 2, the control of the sampling timing and the calculation of the amplitude are complicated, so that the calculation burden increases.

  An object of the present invention is to absorb hardware variations while suppressing an increase in table capacity and calculation burden.

According to a first aspect of the present invention, there is provided a rotation angle detecting device that outputs a detection signal corresponding to a sine and a cosine according to a rotation angle of a rotating body when an excitation signal is input, and an output from the resolver. A rotation angle detection device comprising: a calculation means for calculating a rotation angle of the rotating body based on a detected signal, wherein the calculation means detects the detection at an odd multiple of a half wavelength of the excitation signal. Based on the difference between the current value and the previous value of the detection signal corresponding to the sine and the difference between the current value and the previous value of the detection signal corresponding to the cosine among the extracted detection signals. And calculating the rotation angle.

In the rotation angle detection device according to claim 2 of the present invention, each time the calculation means extracts the detection signal at an odd multiple of a half wavelength of the excitation signal, the current value of the detection signal corresponding to the sine is calculated. Based on the difference between the previous value and the difference between the current value of the detection signal corresponding to the cosine and the previous value , the rotation angle at the time of extracting the previous value and the rotation angle at the time of extracting the current value An intermediate rotation angle corresponding to the intermediate position is calculated.
In the rotation angle detection device according to claim 3 of the present invention, the calculation means calculates the rotation angle at the time when the current value is calculated based on the previous value and the current value at the intermediate rotation angle. And

In the rotation angle detection device according to claim 4 of the present invention, the calculation means calculates the current value by adding ½ of the difference between the previous value and the current value at the intermediate rotation angle to the current value. The rotation angle at the time of being calculated is calculated.
In the rotation angle detection device according to claim 5 of the present invention, the calculation unit calculates the current value when the difference between the previous value and the current value at the intermediate rotation angle is within a predetermined value. The rotation angle at the time is calculated.

  According to the present invention, the detection signal output from the resolver is extracted at an odd multiple of the half wavelength of the excitation signal, and the rotation angle is calculated based on the previous value and the current value of the extracted detection signal. It is possible to absorb hardware variations while suppressing an increase in table capacity and calculation burden.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration of a power steering apparatus. The steering wheel 1 is connected to a wheel 5 through a steering shaft 2, a rack and pinion 3, and a tie rod 4 in order, and an electric motor 7 is connected to the steering shaft 2 via a speed reducer 6. The electric motor 7 is configured by a brushless motor, and is driven and controlled by the control device 8 to apply a steering assist force to the driver's steering operation.

The control device 8 is supplied with electric power from a battery 11 connected via an ignition switch 9 and a fuse 10, and is supplied with a steering torque T detected by a torque sensor 12, detection signals sin θ and cos θ of a resolver 13, and a vehicle speed sensor 14. Is input.
As shown in FIG. 2, the resolver 13 generates two-phase detection signals sinθ and cosθ corresponding to the sine and cosine according to the rotation angle θ of the electric motor 7 when the one-phase excitation signal sinωt is input. Output.

The control device 8 includes a rotation angle detection unit 20 that detects the rotation angle θ of the electric motor 7, a command value calculation unit 30 that calculates voltage command values Va to Vc to the electric motor 7, and voltage command values Va to Vc. And a drive control unit 40 that controls the electric motor 7 based on the drive control unit 40.
The rotation angle detection unit 20 inputs a signal generation unit 21 that outputs an excitation signal sinωt to the resolver 13, a detection signal sinθ and cosθ of the resolver 13, and a rotation angle calculation unit 22 that calculates the rotation angle θ, and a rotation angle θ. And an angular velocity calculating unit 23 that calculates the angular velocity ω, and an abnormality detecting unit 24 that determines abnormality of the detection signals sinθ and cosθ and stops driving control of the electric motor 7 when the abnormality is detected. The excitation signal sin ωt output from the signal generator 21 is converted into an analog signal by the D / A converter 25a, amplified by the amplifier 26a, and input to the resolver 13. The detection signals sinθ and cosθ output from the resolver 13 are amplified by the amplifier 26b, converted into a digital signal by the A / D converter 25b, and input to the rotation angle calculation unit 22 and the abnormality detection unit 24. The The excitation signal sinωt amplified by the amplifier 26a is amplified by the amplifier 26c, converted to a digital signal by the A / D converter 25c, and input to the abnormality detection unit 24.

The command value calculation unit 30 is a current command value calculation unit 31 that calculates a current command value I to the electric motor 7 according to the steering torque T and the vehicle speed V, and the current command value I is a current command value in dq axis coordinates. A dq axis converter 32 for converting to Id and Iq, a three-phase converter 33 for converting the current command values Id and Iq into three-phase current command values Ij (j = u, v, w), and current detection A subtractor 34 that subtracts the motor current Imj detected by the circuit 15 from the current command value Ij and outputs a deviation ΔIj; and a deviation ΔIj
And a voltage command value calculation unit 35 that calculates a voltage command value Vj to the electric motor 7 by performing proportional / integral control processing (PI control processing).

The drive control unit 40 includes: a PWM control unit 41 that generates a pulse width modulation signal based on the voltage command value Vj; and an inverter circuit 42 that controls the switching element according to the pulse width modulation signal to control the motor current Imj. I have.
Next, a rotation angle calculation process executed by the rotation angle calculation unit 22 as a timer interruption process every predetermined time (for example, 1 msec) will be described with reference to the flowchart of FIG.

First, in step S1, the excitation signal sin ωt is read.
In subsequent step S2, it is determined whether or not the extraction flag indicating the timing of the sampling period is reset to F = 0. Here, if F = 1, it is determined that it is a sampling period, and the process proceeds to step S7 described later. On the other hand, if F = 0, it is determined that it is not a sampling period, and the process proceeds to step S3.

In step S3, it is determined whether or not the excitation signal sinωt has reached a peak value (maximum value or minimum value). Here, if the excitation signal sinωt does not reach the peak value, the process returns to the predetermined main program as it is. On the other hand, if the excitation signal sinωt has reached the peak value, the process proceeds to step S4.
In step S4, the count value N indicating the number of times that the excitation signal sinωt has reached the peak value is incremented by one. The count value N is set to a value smaller by 1 than the following set value Ns in the initial setting when the ignition is ON.

  In a succeeding step S5, it is determined whether or not the count value N has reached the set value Ns. This set value Ns is set to an odd number (for example, Ns = 3) in order to sample the detection signals sinθ and cosθ at an odd multiple of the half wavelength λ / 2 of the excitation signal sinωt. Here, if N <Ns, it is determined that the sampling period is not reached, and the process returns to the predetermined main program as it is. On the other hand, if N = Ns, it is determined that it is a sampling period, and the process proceeds to step S6.

In step S6, the count value is reset to N = 0.
In the subsequent step S7, the extraction flag is set to F = 1, and then the process returns to the predetermined main program.
On the other hand, in step S8, the count value M for counting the phase delay of the detection signals sin θ and cos θ with respect to the excitation signal sin ωt is incremented by one.

In a succeeding step S9, it is determined whether or not the count value M has reached the set value Ms. Here, if M <Ms, it is determined that the detection signals sinθ and cosθ have not reached the peak values, and the process returns to the predetermined main program as it is. On the other hand, if M = Ms, it is determined that the detection signals sinθ and cosθ have reached peak values, and the process proceeds to step S10.
In step S10, the count value is reset to M = 0.

In the subsequent step S11, the extraction flag is reset to F = 0.
In the subsequent step S12, the current values sin θ _(n) and cos θ _(n) of the detection signal are read.
In a succeeding step S13, it is determined whether or not the previous values sin θ _(n−1) and cos θ _{(n−1) of} the detection signal are stored. Here, if the previous values sinθ _(n−1) and cosθ _(n−1) are not stored, it is determined that the sampling is the first time, and the process proceeds to step S14. On the other hand, if the previous values sinθ _(n−1) and cosθ _(n−1) are stored, it is determined that the sampling is performed for the second time and thereafter, and the process proceeds to step S15.

In step S14, the current values sinθ _(n) and cosθ _(n) of the detection signal are stored as previous values sinθ _(n-1) and cosθ _(n-1) , and then the process returns to a predetermined main program.
In step S15, according to the following equation (1), the rotation angle θ _(n-1) at the time when the previous values sinθ _(n-1) and cosθ _(n-1) are extracted and the current values sinθ _(n) and cosθ ₍ An intermediate rotation angle φ _(n) corresponding to an intermediate position with respect to the rotation angle θ _(n) at the time _n) is extracted is calculated. This calculation principle will be described later.
φ _(n) = (θ _(n-1) + θ _(n) + π) / 2 ……… (1)

In a succeeding step S16, it is determined whether or not the previous value φ _{(n−1) of} the intermediate rotation angle is stored. Here, if the previous value φ _(n−1) is not stored, it is determined that the sampling is the second time, and the process proceeds to step S17. On the other hand, if the previous value φ _(n−1) is stored, it is determined that the sampling is performed for the third time and thereafter, and the process proceeds to step S18.

In step S17, the current value φ _(n) of the intermediate rotation angle is stored as the previous value φ _(n−1) and then the process returns to the predetermined main program.
In step S18, it is determined whether or not the difference between the current value φ _(n) and the previous value φ _(n−1) of the intermediate rotation angle is within a predetermined value and is approximately the same. Here, if the difference exceeds the predetermined value, it is determined that the electric motor 7 is in a rotating state, and the process proceeds to step S23 described later. On the other hand, if the difference is within the predetermined value and φ _(n) ≈φ _(n−1), it is determined that the electric motor 7 is in a non-rotating state, and the process proceeds to step S19.

In step S19, as shown in the following equation (2), the current value φ _(n) is calculated as the current rotation angle θ _(n) .
θ _(n) = φ _(n) (2)
In subsequent step S _< b _> 20, the current rotation angle θ _(n) is output to the angular velocity calculation unit 23.
In the subsequent step S21, the current values sinθ _(n) and cosθ _(n) of the detection signals are stored as previous values sinθ _(n-1) and cosθ _(n-1) .

In the subsequent step S22, the current value φ _(n) of the intermediate rotation angle is stored as the previous value φ _(n−1) and then the process returns to the predetermined main program.
On the other hand, in step S23, it is determined whether or not the electric motor 7 is rotating in the forward direction. Here, if it is rotating in the negative direction, the process proceeds to step S27 described later. On the other hand, if it is rotating in the forward direction, the process proceeds to step S24.

In step S24, it is determined whether or not the current value φ _{(n) of} the intermediate rotation angle is greater than the previous value φ _(n−1) . Here, if φ _(n) > φ _(n−1), it is determined that the rotation in the positive direction does not cross 0 ° (= 360 °), and the process proceeds to step S25. On the other hand, if φ _(n) <φ _(n−1) , it is determined that the rotation in the positive direction has crossed 0 ° (= 360 °), and the process proceeds to step S26.

In step S25, the current rotation angle θ _(n) is calculated according to the following equation (3), and then the process proceeds to step S20.
θ _(n) = φ _(n) + (φ _(n) −φ _(n−1) ) / 2 (3)
In step S26, the current rotation angle θ _(n) is calculated according to the following equation (4), and then the process proceeds to step S20.
θ _(n) = φ _(n) + (φ _(n) −φ _(n−1) + 2π) / 2 (4)

On the other hand, in step S27, it is determined whether or not the previous value φ _{(n−1) of} the intermediate rotation angle is greater than the current value φ _(n) . Here, if φ _(n-1) > φ _(n), it is determined that the rotation in the negative direction does not cross 0 ° (= 360 °), and the process proceeds to step S28. On the other hand, if φ _(n−1) <φ _(n) , it is determined that the rotation in the negative direction has crossed 0 ° (= 360 °), and the process proceeds to step S29.

In step S28, the current rotation angle θ _(n) is calculated according to the following equation (5), and then the process proceeds to step S20.
θ _(n) = φ _(n) + (φ _(n) −φ _(n-1) ) / 2 (5)
In step S29, the current rotation angle θ _(n) is calculated according to the following equation (6), and then the process proceeds to step S20.
θ _(n) = φ _(n) + (φ _(n) −φ _(n−1) −2π) / 2 (6)

Next, the calculation principle of the rotation angle θ _(n) will be described.
In FIG. 4, the electric motor 7 is in a non-rotating state, and the amplitudes of the detection signals sinθ and cosθ output from the resolver 13 are constant. By the way, due to variations in the hardware of the resolver 13, an error may occur in the amplitude centers of sin θ and cos θ. Therefore, as shown in the following equation (7), the detection signals sin θ and cos θ are related to the true rotation angle ψ. Have some errors Δsin and Δcos.

sinθ = sinψ + Δsin
cosθ = cosψ + Δcos (7)
Therefore, when there is an error due to the variation in hardware, even if θ = tan ⁻¹ [sin θ / cos θ] is solved based on sin θ and cos θ, an accurate rotation angle θ cannot be calculated.

Here, consider the case where the detection signals sinθ and cosθ are sampled at a period three times the half wavelength of the excitation signal sinωt, and the coordinates of timing A sampled last time are (cosθ _(n-1) , sinθ _(n-1) ). And the coordinates of the timing B sampled this time are (cos θ _(n) , sin θ _(n) ).
At this time, since the amplitudes of the detection signals sinθ and cosθ are constant, θ _(n) = θ _(n-1) + π, and the coordinates A and the coordinates B are aligned on a diagonal line that sandwiches the origin O. When the change amount (amplitude) of sinθ when moving from coordinate A to coordinate B is sinφ and the change amount (amplitude) of cosθ is cosφ, the respective change amounts sinφ and cosφ are expressed by the following equation (8). Is done.
sinφ = sinθ _(n) −sinθ _(n-1)
cosφ = cosθ _(n) −cosθ _(n-1) (8)

When the equation (7) is adapted to the above equation (8), the respective change amounts sinφ and cosφ are expressed by the following equation (9).
sinφ = (sinψ _(n) + Δsin) − (sinψ _(n-1) + Δsin)
cosφ = (cosψ _(n) + Δcos) − (cosψ _(n−1) + Δcos) (9)
As apparent from the above equation (9), the errors Δsin and Δcos cancel each other and are absorbed, so that φ = tan ⁻¹ [sinφ / cosφ] based on sinφ and cosφ according to the above equation (8). By solving the above, if the electric motor 7 is in a non-rotating state, an accurate rotation angle ψ can be calculated.

This is a case where the electric motor 7 is rotating.
FIG. 5 shows a state where the electric motor 7 is rotating, and the amplitudes of the detection signals sinθ and cosθ output from the resolver 13 are not constant. Therefore, since θ _(n) ≠ θ _(n−1) + π, when φ = tan ⁻¹ [sinφ / cosφ] is solved, the rotation angle θ _(n−1) at timing A and the rotation angle θ at timing B An intermediate rotation angle φ corresponding to an intermediate position (average value ₎ with _(n) is obtained. Here, the rotation angle θ _(n) at the timing B is a rotation angle obtained by replacing the coordinate B with a point-symmetrical position across the origin O, that is, a rotation angle obtained by inverting the coordinate B by π. Therefore, assuming that the change in rotational speed is sufficiently small, add 1/2 of the difference between the previous value φ _(n-1) and the current value φ _(n) at the intermediate rotational angle to the current value φ _(n) . By doing so, the rotation angle θ _(n) at the present time, that is, at the timing B can be calculated.

First, the equation (8) is transformed into the following equation (10) by a sum product formula based on the addition theorem.
sinφ = sinθ _(n-1) −sinθ _(n)
= 2 cos {(θ _(n-1) + θ _(n) ) / 2} × sin {(θ _(n-1) −θ _(n) ) / 2}
cosφ = cosθ _{(n -1)} −cosθ _(n)
= −2 sin {(θ _(n−1) + θ _(n) ) / 2} × sin {(θ _(n−1) −θ _(n) ) / 2}
……… (10)
Then, by substituting sinφ and cosφ in the above formula (10) into the following formula (11), and transforming the sinφ and cosφ according to the remainder angle formula, the above formula (1) is derived.

φ = tan ⁻¹ [sinφ / cosφ] (11)
= Tan ^-1 [2cos [(θ _(n-1) + θ _(n) ) / 2] × sin [(θ _(n-1) −θ _(n) ) / 2] /
-2sin [(θ _(n-1) + θ _(n) ) / 2] × sin [(θ _(n-1) −θ _(n) ) / 2]]
= Tan ^-1 [cos [(θ _(n-1) + θ _(n) ) / 2] / − sin [(θ _(n-1) + θ _(n) ) / 2]]
= Tan ^-1 [sin [(θ _(n-1) + θ _(n) + π) / 2] /
cos [(θ _(n-1) + θ _(n) + π) / 2]]
= Tan ^-1 [tan [(θ _(n-1) + θ _(n) + π) / 2]]
= (Θ _(n-1) + θ _(n) + π) / 2 (1)

Here, _assuming that the rotation amount of the electric motor 7 rotated from the timing A to the timing B is Δθ, the rotation angle θ _{(n) at the} timing B is expressed by the following equation (12).
θ _(n) + π = θ _(n-1) + Δθ
θ _(n) = θ _(n-1) −π + Δθ (12)
If the equation (12) is substituted into the equation (1), the following equation (13) is obtained.
φ _(n) = θ _(n-1) + Δθ / 2 (13)
That is, the intermediate rotation angle φ _(n) is _{equal to} the rotation angle θ _(n−1) at timing A plus 1/2 of Δθ rotated from timing A to timing B.

Therefore, if the change in the rotation speed is sufficiently small, the difference between the previous value φ _(n−1) and the current value φ _(n) at the intermediate rotation angle in accordance with the above-described equations (3) and (5). Is added to the current value φ _(n) , the rotation angle θ _(n) at the present time, that is, the timing B can be calculated.
At this time, when the intermediate rotation angle is rotated from φ _(n−1) to φ _(n) and crosses 0 ° (= 360 °), φ _(n−1) and φ _(n) Therefore, the rotation angle θ _(n) cannot be calculated from the equations (3) and (5). Therefore, if the rotation is in the positive direction when straddling 0 ° (= 360 ° ₎ , 2π is added to the intermediate rotation angle φ _(n) and the rotation in the negative direction as shown in the above-described equation (4). If so, as shown in the above-described equation (6), it may be calculated by subtracting 2π from the intermediate rotation angle φ _(n) to adjust the book bottom.

Since the calculation principle is based on the assumption that the change in rotational speed is sufficiently small in the period from timing A to timing B, it is necessary to sufficiently shorten the period from timing A to timing B, that is, the sampling cycle. is there.
From the above, the rotation angle calculation process of FIG. 3 corresponds to the “calculation means”.
Next, the operational effects of the one embodiment will be described.

  When the power is turned on by turning on the ignition, the control device 8 is activated and the rotation angle calculation process is started. At this time, only for the first time, the detection signals sinθ and cosθ are sampled when the excitation signal sinωt first reaches the peak value, and the subsequent sampling is performed at an odd multiple of the half wavelength of the excitation signal sinωt. That is, the peak value and peak value of the peaks of the detection signals sinθ and cosθ are sampled alternately (steps S1 to S12).

At the time of the first sampling, since the previous values sinθ _(n-1) and cosθ _(n-1) do not exist (“No” in step S13), the current values sinθ _(n) and cosθ _(n) are simply read. The timer interrupt process is terminated.
At the time of the second sampling, since the previous values sinθ _(n-1) and cosθ _(n-1) exist (“Yes” in step S13), the rotation angle θ _(n-1) at the time of previous sampling and the current sampling An intermediate rotation angle φ _(n) corresponding to an intermediate position with respect to the rotation angle θ _(n) at the time is calculated (step S15). However, since the previous value φ _{(n−1) of} the intermediate rotation angle does not exist (“No” in step S16), the timer interrupt process is terminated simply by calculating the current value φ _(n) .

At this time, as described above, the intermediate rotation angle φ _(n) calculated according to the equation (1) is a highly accurate value that absorbs errors caused by hardware variations.
At the time of the third sampling, since the previous value φ _(n−1) exists (“Yes” in step S16), based on the previous value φ _(n-1) and the current value φ _(n) , The rotation angle θ _(n) is calculated.
First, if the previous value φ _(n−1) and the current value φ _(n) substantially match (“Yes” in step S18), it is considered that the electric motor 7 is in a non-rotating state. The value φ _(n) is directly calculated as the current rotation angle θ _(n) (step S19).

On the other hand, if the current value φ _(n) has changed with respect to the previous value φ _(n−1) (“No” in step S18), the electric motor 7 is in a rotating state, so the rotation direction of the electric motor 7 is In addition, based on the magnitude relationship between the previous value φ _(n−1) and the current value φ _(n) , any one of the equations (3) to (6) is selected, and the current rotation angle θ _{(n )} Is calculated (steps S23 to S29).
At this time, the rotation angle θ _(n) calculated according to any one of the equations (3) to (6) is ½ of the difference between the previous value φ _(n−1) and the current value φ _(n) . It corresponds to a value added to the current value φ _(n) , and both the previous value φ _(n-1) and the current value φ _(n) are highly accurate values that absorb errors caused by hardware variations. As a result, the rotation angle θ _(n) is also a highly accurate value.

In this way, the current rotation angle θ _(n) can be detected with high accuracy by performing a simple calculation based on the geometric principle. Further, when calculating the intermediate rotation angle φ _(n) in step S15, a table corresponding to sin θ / cos θ is used to solve θ _(n) = tan ⁻¹ [sin θ _(n) / cos θ _(n) ]. Will refer to it. That is, since only a table corresponding to sin θ / cos θ needs to be prepared, an increase in table capacity and calculation burden can be suppressed.

1 is a schematic configuration of an electric power steering device. It is a block diagram of a control apparatus. It is a flowchart which shows a rotation angle calculation process. The calculation principle of the rotation angle θ when the electric motor is in a non-rotating state is shown. The calculation principle of the rotation angle θ when the electric motor is in a rotating state is shown.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering wheel, 2 ... Steering shaft, 3 ... Rack and pinion, 4 ... Tie rod, 5 ... Wheel, 6 ... Reduction gear, 7 ... Electric motor, 8 ... Control apparatus, 12 ... Torque sensor, 13 ... Resolver, 14 ... Vehicle speed sensor, 20 ... rotation angle detection unit, 21 ... signal generation unit, 22 ... rotation angle calculation unit, 23 ... angular velocity calculation unit, 24 ... abnormality detection unit, 30 ... command value calculation unit, 31 ... current command value calculation unit, 32 ... dq axis conversion unit, 33 ... three-phase conversion unit, 34 ... subtraction unit, 35 ... voltage command value calculation unit, 40 ... drive control unit, 41 ... PWM control unit, 42 ... inverter circuit

Claims (5)

When an excitation signal is input, the resolver outputs a detection signal corresponding to the sine and cosine according to the rotation angle of the rotating body, and the rotation angle of the rotating body based on the detection signal output from the resolver A rotation angle detecting device comprising: a calculating means for calculating
The calculation means extracts the detection signal at an odd multiple of a half wavelength of the excitation signal, and among the extracted detection signals, the difference between the current value and the previous value of the detection signal corresponding to the sine, A rotation angle detection device that calculates a rotation angle based on a difference between a current value and a previous value of a detection signal corresponding to a cosine . The calculation means extracts a detection signal corresponding to the cosine and a difference between a current value and a previous value of the detection signal corresponding to the sine each time the detection signal is extracted at an odd multiple of a half wavelength of the excitation signal. Based on the difference between the current value and the previous value, the intermediate rotation angle corresponding to the intermediate position between the rotation angle at the time of extracting the previous value and the rotation angle at the time of extracting the current value is calculated. The rotation angle detection device according to claim 1, wherein the rotation angle detection device is a rotation angle detection device.   The rotation angle detection device according to claim 2, wherein the calculation unit calculates a rotation angle at the time when the current value is calculated based on the previous value and the current value at the intermediate rotation angle.   The calculation means calculates the rotation angle at the time when the current value is calculated by adding ½ of the difference between the previous value and the current value at the intermediate rotation angle to the current value. The rotation angle detection device according to claim 3.   The calculating means, when the difference between the previous value and the current value at the intermediate rotation angle is within a predetermined value, calculates the current value as a rotation angle at the time of calculating the current value. Item 5. The rotation angle detection device according to any one of Items 2 to 4.

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