JP2010101763A - Resolver signal processing device and steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resolver signal processing device capable of suppressing a decrease in detection accuracy of a rotation angle even when a voltage applied to an amplification means decreases, and to provide a steering device. <P>SOLUTION: An ECU 40 functioning as a resolver signal processing device reduces an amplitude of an exciting signal input to a resolver 33 for detecting a motor rotation angle θm of a motor 32 according to a decrease in a power supply voltage Vb of a battery B by reducing a gain G according to the decrease in the power supply voltage Vb when the power supply voltage Vb becomes a threshold voltage Vp or lower. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resolver signal processing device having a resolver for detecting the rotational position of a rotor and a steering device using the resolver signal processing device.

2. Description of the Related Art Conventionally, an angle detection device disclosed in Patent Document 1 is known as a resolver signal processing device having a resolver that detects a rotational position of a rotor. In this angle detection device, when the rotation angle θ is calculated based on the SIN phase amplitude and the COS phase amplitude, which are the amplitudes of two output signals (resolver signals) output from the resolver and amplified by the operational amplifier, the SIN phase amplitude The signal amplitude R is calculated based on / sin θ or COS phase amplitude / cos θ. Then, the next excitation amplitude is calculated by multiplying the value obtained by dividing the maximum signal amplitude that should be output by the signal amplitude R by the amplitude of the current excitation amplitude, and a voltage corresponding to the next excitation amplitude is applied to the resolver. To do. As a result, the ratio of the excitation signal to the output signal due to the ambient temperature and the temperature change of the excitation winding becomes constant, thereby suppressing a decrease in the calculation accuracy of the rotation angle.
JP 2004-177273 A

  FIG. 6 is a waveform diagram showing an example of the relationship between the excitation signal Sin and the resolver signal Sout according to the conventional example, and FIG. 6A is a waveform diagram in a state where the operational amplifier power supply voltage is larger than a threshold voltage described later. 6 (B) is a waveform diagram in a state where the operational amplifier power supply voltage has dropped below the threshold voltage. Note that the resolver signal Sout shown in FIG. 6 represents a sine wave signal output from the sine wave phase coil.

  By the way, the operational amplifier as an amplification means amplifies the input signal based on the applied voltage and outputs it. If the applied voltage (op-amp power supply voltage) drops below the threshold voltage for some reason, The output signal may be saturated, and in this case, there is a problem that the intended signal (voltage) cannot be output. A voltage at which the output signal from the operational amplifier is saturated is defined as a threshold voltage.

  For example, in a resolver that detects the rotation angle of a motor that assists in steering a vehicle, an operational amplifier power supply voltage supplied from a battery to an operational amplifier that amplifies an excitation signal and an operational amplifier that amplifies a resolver signal is larger than a threshold voltage (for example, In the case of 12V equal to the battery voltage), as shown in FIG. 6A, the amplified excitation signal Sin and resolver signal Sout are output in a sine wave form.

  On the other hand, when the battery voltage temporarily decreases due to sudden steering or the like, and the operational amplifier power supply voltage decreases below the threshold voltage, the amplified excitation signal Sin and resolver signal Sout are saturated as shown in FIG. A sine wave signal may not be output. When the excitation signal Sin and the resolver signal Sout are saturated as described above, there is a problem that it becomes impossible to detect an accurate rotation angle, and it becomes difficult to generate torque according to the steering situation by the motor.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to perform resolver signal processing capable of suppressing a decrease in rotation angle detection accuracy even when an applied voltage to an amplifying unit is decreased. It is in providing a device and a steering device.

  In order to achieve the above object, in the resolver signal processing device according to claim 1, the resolver signal (Sout) corresponding to the rotation angle (θm) of the rotor based on the input excitation signal (Sin). ) For generating and outputting the excitation signal, and a first amplification means for amplifying the excitation signal from the excitation means and inputting it to the resolver. 42a), second amplifying means (42b, 42c) for amplifying the resolver signal output from the resolver, and a rotation angle for calculating the rotation angle in accordance with the resolver signal amplified by the second amplifying means. Calculation means (41, 53) and voltage detection means (41, 5) for detecting an applied voltage (Vb) applied to the first amplification means and the second amplification means for amplifying the signals. The excitation means reduces the amplitude of the excitation signal in accordance with the applied voltage when the applied voltage detected by the voltage detecting means falls below a predetermined threshold voltage (Vp). Technical features.

  In the resolver signal processing apparatus according to claim 1, when the voltage applied to the first amplification means and the second amplification means detected by the voltage detection means is applied to a predetermined threshold voltage, for example, the amplification means, When the output voltage is equal to or lower than the voltage determined to be saturated, the amplitude of the excitation signal input to the resolver by the excitation means is reduced according to the applied voltage.

As described above, when the applied voltage to the first amplifying means and the second amplifying means is equal to or lower than the predetermined threshold voltage, the amplitude of the excitation signal is reduced according to the applied voltage, and then amplified from the first amplifying means. The saturation state of the excitation signal that is output can be eliminated. Since the amplitude of the resolver signal output from the resolver is reduced in accordance with the reduction in the amplitude of the excitation signal, the saturation state of the resolver signal that is amplified and output from the second amplification means can be eliminated. In particular, the resolver signal, specifically, the amplitude of both the sine wave signal and the cosine wave signal is similarly reduced, so that even if the amplitude of both signals is reduced, the rotation angle detected according to the amplitude of both signals. A decrease in detection accuracy is suppressed.
Therefore, even when the voltage applied to the amplifying means decreases, it is possible to suppress a decrease in the rotation angle detection accuracy.

  The resolver signal processing device according to claim 2 is provided with filter means for removing the vibration component of the rotation angle calculated by the rotation angle calculation means when the amplitude of the excitation signal is reduced by the excitation means.

  When the amplitude of the excitation signal is reduced by the excitation means, the amplitude of the resolver signal output from the resolver is also reduced, so that the rotation angle calculated according to the resolver signal may change suddenly. Therefore, by providing filter means for removing the vibration component of the rotation angle when the amplitude of the excitation signal is reduced, the vibration component of the rotation angle calculated by the rotation angle calculation means is removed. Thereby, even when the amplitude of the excitation signal is reduced, the rotation angle is calculated without abrupt change, so that the continuity of the rotation angle can be maintained.

  According to a third aspect of the present invention, a rotation angle of a motor that assists steering is calculated by the resolver signal processing device according to the first or second aspect, and the motor is controlled in accordance with the rotation angle. As a result, it is possible to realize a steering apparatus that enjoys the functions and effects of the inventions according to claim 1 or 2 such that a decrease in rotation angle detection accuracy can be suppressed even when the voltage applied to the amplifying means decreases. . Therefore, even when the battery voltage temporarily decreases due to sudden steering or the like, a decrease in detection accuracy at the rotation angle of the motor is suppressed, and therefore a steering device capable of generating torque according to the steering situation by the motor is provided. it can.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the configuration of the steering apparatus 10 that employs the resolver signal processing apparatus according to the present embodiment will be described with reference to the drawings. FIG. 1A is a configuration diagram showing the configuration of the steering apparatus 10 according to the present embodiment, and FIG. 1B is a circuit block diagram showing a configuration example of the ECU 40 and the like. FIG. 2 is a functional block diagram regarding control processing of the motor 32 according to the present embodiment.

  As shown in FIG. 1A, the steering device 10 mainly includes a steering wheel 12, a first steering shaft 14, a second steering shaft 16, a torque sensor 18, a pinion gear 20, a rack shaft 22, a rod 24, a transmission ratio. It is comprised from the variable apparatus 30, ECU40 grade | etc.,.

  The steering wheel 12 is fixed to the first steering shaft 14, the first steering shaft 14 is connected to the input side of the transmission ratio variable device 30, and the second steering shaft 16 is connected to the output side of the transmission ratio variable device 30. Has been.

  The torque sensor 18 includes a torsion bar (not shown) provided in the middle of the first steering shaft 14 and two resolvers attached to both ends of the torsion bar so as to sandwich the torsion bar. The torque sensor 18 detects a torsion bar twist amount or the like generated between input and output with one end of the torsion bar as an input and the other end as an output by the two resolvers, whereby the steering angle θs by the steering wheel 12 is detected. And steering torque is detected. Then, the torque sensor 18 generates detection signals corresponding to the steering angle θs and the steering torque and outputs them to the ECU 40.

  The pinion gear 20 at the tip of the second steering shaft 16 meshes with the rack shaft 22, and the rotational motion of the second steering shaft 16 is converted into the linear motion of the rack shaft 22. A rod 24 is connected to both ends of the rack shaft 22, and steering wheels FR and FL are connected to the end of the rod 24 via a knuckle (not shown). Thus, when the second steering shaft 16 rotates, the turning angle of the steered wheels FR, FL can be changed via the rack shaft 22, the rod 24, etc., so that the rotation amount and the rotation direction of the second steering shaft 16 can be changed. The steering wheels FR and FL can be steered according to the above.

  The transmission ratio variable device 30 can detect a differential mechanism 31 that connects the first steering shaft 14 and the second steering shaft 16, a motor 32 that drives the differential mechanism 31, and a motor rotation angle θm of the motor 32. And a resolver 33. The motor 32 rotates forward and backward by being controlled by the ECU 40, and the differential mechanism 31 transmits the rotation of the first steering shaft 14 to the second steering shaft 16 and decelerates the rotation of the motor 32 to perform the second steering. It is transmitted to the shaft 16.

  The resolver 33 is a one-phase excitation two-phase output type resolver, and includes an excitation coil, a sine wave phase coil, and a cosine wave phase coil, and the sine wave phase coil and the cosine wave phase coil are in phase with each other. It is arranged to deviate. When a predetermined excitation signal is input to the excitation coil, a sine wave signal and a cosine which are resolver signals corresponding to the motor rotation angle θm of the rotor (rotor) of the motor 32 from the sine wave phase coil and the cosine wave phase coil. A wave signal is output.

  As described above, the transmission ratio variable device 30 transmits the rotation by the motor drive to the rotation of the first steering shaft 14 that is input to the differential mechanism 31 and transmits the rotation to the second steering shaft 16. Then, the rotation of the rack shaft 22 is increased (or reduced). Note that “addition” in this case is defined to include not only addition but also subtraction, and so on.

  In other words, the transmission ratio variable device 30 is controlled by the ECU 40 and steers the steering angle θs by adding the steering angle of the steering wheels FR and FL based on the motor drive to the steering angle of the steering wheels FR and FL based on the steering operation. The transmission ratio of the wheels FR and FL is varied.

Next, the electrical configuration of the ECU 40 that controls the drive of the motor 32 will be described with reference to FIG.
As shown in FIG. 1B, the ECU 40 is mainly configured by an MPU 41, an I / F circuit 42, a motor drive circuit 43, and the like, and the I / F circuit 42 is centered on the MPU 41 via an input / output bus. And a motor drive circuit 43 and the like are connected. Reference numeral 44 shown in FIG. 1B is a current sensor 44 that can detect a motor current value that actually flows through the motor 32. Sensor information related to the motor current value detected by the current sensor 44 is motor current. A value signal can be input to the MPU 41 via the I / F circuit 42. The ECU 40, together with the resolver 33, constitutes an example of a “resolver signal processing device” described in the claims.

  The MPU 41 is composed of, for example, a microcomputer, a memory (ROM, RAM, EEPROM, etc.), etc., and has a function of executing drive control of the motor 32 of the transmission ratio variable device 30 by a predetermined computer program. Note that the DC voltage 12V supplied from the battery B is stepped down to 5V by the 5V power source 45 and supplied to the MPU 41 (see FIG. 2). The memory stores in advance the predetermined computer program, a power supply voltage-gain map, which will be described later, and the like.

  The I / F circuit 42 includes a plurality of operational amplifiers (only 42a to 42c are shown in FIG. 2), and amplifies the resolver signal from the resolver 33, the detection signal from the torque sensor 18 and the current sensor 44, etc. It has a function of outputting to a predetermined port of the MPU 41 via a / D converter or the like, and a function of amplifying an excitation signal input from the MPU 41 via a D / A converter or the like and outputting it to the resolver 33. is there. Each operational amplifier is supplied with the power supply voltage Vb from the battery B as an operational amplifier power supply voltage (see FIG. 2).

  The motor drive circuit 43 has a function of converting power supplied from the battery B into controllable three-phase AC power, and includes a PWM circuit and a switching circuit. The motor drive circuit 43 supplies a motor voltage corresponding to the drive signal input from the MPU 41 to the motor 32.

  Thus, the ECU 40 responds to a resolver signal corresponding to the motor rotation angle θm of the resolver 33, a detection signal corresponding to the steering angle θs of the torque sensor 18, and a motor current value of the current sensor 44 by motor drive control described later. Based on the detection signal or the like, drive control of the motor 32 is performed so that steering characteristics suitable for the vehicle state can be obtained.

  Next, the outline of the motor drive control process in the ECU 40 configured as described above will be described with reference to FIG.

  As shown in FIG. 2, the MPU 41 executes a predetermined computer program stored in its internal memory, whereby a drive signal generation unit 51, an excitation signal generation unit 52, a rotation angle calculation unit 53, a power supply It functions as a motor drive control unit including a voltage detection unit 54, a gain setting unit 55, and a filter unit 56.

  The drive signal generation unit 51 generates a drive signal for controlling the motor 32 based on the input motor rotation angle θm, steering angle θs, motor current value, and the like, and outputs the generated drive signal to the motor drive circuit 43. In FIG. 2, for the sake of convenience, only the motor rotation angle θm is described as being input to the drive signal generation unit 51. However, the detection signal corresponding to the steering angle θs of the torque sensor 18 and the motor current of the current sensor 44 are described. A detection signal corresponding to the value is also input to the drive signal generation unit 51 via the I / F circuit 42 and the like.

  The excitation signal generator 52 generates and outputs a predetermined sinusoidal excitation signal. This excitation signal is multiplied by a gain G, which will be described later, by a multiplier 57, and then input to an operational amplifier 42a of the I / F circuit 42 via a D / A converter or the like. The excitation signal generator 52 corresponds to an example of “excitation means” recited in the claims, and the operational amplifier 42a corresponds to an example of “first amplification means” recited in the claims.

  In the rotation angle calculation unit 53, the sine wave signal and the cosine wave signal from the resolver 33 are amplified by the operational amplifiers 42b and 42c of the I / F circuit 42 and then input via an A / D converter or the like. The motor rotation angle θm is calculated based on the amplitude of the signal and the cosine wave signal. The motor rotation angle θm is output to the filter unit 56. The rotation angle calculation unit 53 corresponds to an example of “rotation angle calculation means” described in the claims, and the operational amplifiers 42b and 42c are examples of “second amplification means” described in the claims. Equivalent to.

  In the power supply voltage detection unit 54, the power supply voltage Vb of the battery B is detected and output to the gain setting unit 55 and the filter unit 56. The power supply voltage detection unit 54 corresponds to an example of “voltage detection means” recited in the claims.

  In the gain setting unit 55, the gain G is set based on a power supply voltage-gain map described later. This gain G is output to the multiplier 57 described above. In the filter unit 56, the motor rotation angle θm calculated by the rotation angle calculation unit 53 is output to the drive signal generation unit 51 as it is, or is filtered and output to the drive signal generation unit 51. The gain G setting process and the motor rotation angle θm filtering process as described above will be described in detail with reference to the flowchart shown in FIG. The filter unit 56 corresponds to an example of “filter means” described in the claims.

  Hereinafter, the motor drive control process by the ECU 40 will be described in detail with reference to the flowchart shown in FIG. FIG. 3 is a flowchart showing the flow of the motor drive control process by the ECU 40. FIG. 4 is an explanatory diagram showing an example of a power supply voltage-gain map used for the motor drive control process.

  First, when the power supply voltage detection process is performed in step S101 of FIG. 3 and the power supply voltage detection unit 54 detects the power supply voltage Vb of the battery B, the gain setting process is performed in step S103. In this process, the gain setting unit 55 sets the gain G corresponding to the power supply voltage Vb based on the power supply voltage-gain map of FIG.

  Specifically, as shown in FIG. 4, when the power supply voltage Vb is greater than a threshold voltage Vp that is a voltage that is determined to be saturated when the output voltage from the operational amplifier is applied to the operational amplifier, the gain G is Set to 1. On the other hand, when the power supply voltage Vb is equal to or lower than the threshold voltage Vp, the gain G is set so as to decrease linearly as the power supply voltage Vb decreases. In the present embodiment, the threshold voltage Vp is set to 7 V, for example. Further, for example, the gain G may be set so as to decrease stepwise as the power supply voltage Vb decreases.

  When the gain G is set as described above, excitation signal output processing is performed in step S105. In this processing, the excitation signal generated by the excitation signal generation unit 52 and multiplied by the gain G by the multiplier 57 is output to the operational amplifier 42a of the I / F circuit 42 via a D / A converter or the like. . Here, when the gain G is set to 1, the excitation signal generated by the excitation signal generation unit 52 is output to the I / F circuit 42 as it is. On the other hand, when the gain G is set to decrease according to the power supply voltage Vb, the amplitude of the excitation signal generated by the excitation signal generation unit 52 is reduced according to the power supply voltage Vb. It is output to the F circuit 42. This excitation signal is amplified by the operational amplifier 42a and output to the excitation coil of the resolver 33.

  Next, in step S107, rotation angle calculation processing is performed. In this process, the rotation angle calculation unit 53 calculates the motor rotation angle θm based on the amplitude of the sine wave signal and the amplitude of the cosine wave signal amplified by the operational amplifier 42b and the operational amplifier 42c of the I / F circuit 42. . The sine wave signal and the cosine wave signal are resolver signals output from the sine wave phase coil and the cosine wave phase coil in accordance with the excitation signal input to the excitation coil of the resolver 33.

  In step S109, it is determined whether the power supply voltage Vb is equal to or lower than the threshold voltage Vp. Here, if the power supply voltage Vb is equal to or lower than the threshold voltage Vp (Yes in S109), that is, if the amplitude of the excitation signal is reduced, a filtering process is performed in step S111. In this process, the vibration component of the motor rotation angle θm is removed by the filter unit 56 and output to the drive signal generation unit 51. Thus, even when the resolver signal amplitude is reduced in accordance with the reduction of the excitation signal amplitude, the motor rotation angle θm is calculated without abrupt change, so that the continuity of the motor rotation angle θm can be maintained. .

  On the other hand, when the power supply voltage Vb is larger than the threshold voltage Vp (No in S109), the amplitude of the excitation signal is not reduced, so that the process in step S113 is performed without performing the filter process in step S111. That is, in the filter unit 56, the motor rotation angle θm calculated by the rotation angle calculation unit 53 is output to the drive signal generation unit 51 as it is.

  In step S113, drive signal generation processing is performed. In this process, the drive signal generation unit 51 generates a drive signal based on one of the filtered motor rotation angle θm and the unfiltered motor rotation angle θm, the steering angle θs, the motor current value, and the like. It is output to the motor drive circuit 43. As a result, the motor voltage corresponding to the drive signal is supplied from the motor drive circuit 43 to the motor 32, and a steering characteristic suitable for the vehicle state is obtained.

  Here, the effect of reducing the amplitude of the excitation signal in accordance with the reduction of the power supply voltage Vb will be described in detail with reference to FIG. FIG. 5 is a waveform diagram showing an example of the relationship between the excitation signal Sin and the resolver signal Sout according to the present invention, and FIG. 5A is a waveform diagram in a state where the operational amplifier power supply voltage is larger than the threshold voltage Vp. (B) is a waveform diagram in a state where the operational amplifier power supply voltage is lowered to a threshold voltage Vp or less. Note that the resolver signal Sout shown in FIG. 5 represents a sine wave signal output from the sine wave phase coil.

  When the operational amplifier power supply voltage (power supply voltage Vb) supplied from the battery B to the operational amplifier 42a for amplifying the excitation signal and the operational amplifiers 42b and 42c for amplifying the resolver signal is larger than the threshold voltage Vp (for example, 12V equal to the battery voltage) In this case, as shown in FIG. 5A, the amplified excitation signal Sin and resolver signal Sout are output in a sine wave form.

  On the other hand, when the power supply voltage Vb of the battery B temporarily decreases due to sudden steering by the steering wheel 12, the operational amplifier power supply voltage decreases below the threshold voltage Vp. At this time, as described above, the saturation state of the excitation signal Sin amplified and output from the operational amplifier 42a can be eliminated by reducing the amplitude of the excitation signal in accordance with the reduction of the power supply voltage Vb. Since the amplitudes of the sine wave signal and the cosine wave signal output from the resolver 33 are reduced in accordance with the reduction in the amplitude of the excitation signal, the sine wave signal and the cosine wave signal that are amplified and output from the operational amplifiers 42b and 42c. The saturation state of the (resolver signal) can be eliminated.

  As a result, as shown in FIG. 5B, the amplified excitation signal Sin and resolver signal Sout are output in a sine wave form without being saturated.

  As described above, in the ECU 40 that functions as the resolver signal processing device according to the present embodiment, when the power supply voltage Vb of the battery B becomes equal to or lower than the threshold voltage Vp, the gain G is reduced according to the reduction of the power supply voltage Vb. The amplitude of the excitation signal input to the resolver 33 is reduced according to the reduction of the power supply voltage Vb.

As a result, when the applied voltage to the I / F circuit 42 becomes equal to or lower than the threshold voltage Vp, the amplitude of the resolver signal output from the resolver 33 is reduced, so that it is amplified and output from the operational amplifier 42a of the I / F circuit 42. The saturation state of the excitation signal can be eliminated. Then, since the amplitude of the resolver signal output from the resolver 33 is reduced in accordance with the reduction in the amplitude of the excitation signal, the saturation state of the resolver signal that is amplified and output from the operational amplifiers 42b and 42c of the I / F circuit 42 is eliminated. be able to. In particular, since the amplitudes of both the sine wave signal and the cosine wave signal are similarly reduced, even if the amplitudes of both signals are reduced, the detection accuracy of the motor rotation angle θm detected in accordance with the amplitudes of both signals is reduced. It is suppressed.
Therefore, even when the applied voltage to each operational amplifier 42a-42c of I / F circuit 42 falls, the fall of detection accuracy of motor rotation angle thetam can be controlled.

  Further, in the ECU 40 that functions as the resolver signal processing device according to the present embodiment, the vibration component of the motor rotation angle θm is removed by the filter unit 56 when the amplitude of the excitation signal is reduced. As a result, even when the amplitude of the excitation signal is reduced, the motor rotation angle θm is calculated without abrupt change, so that the continuity of the motor rotation angle θm can be maintained.

  In the steering apparatus 10 according to the present embodiment, the ECU 40 and the resolver 33 functioning as a resolver signal processing apparatus calculate the motor rotation angle θm of the motor 32 that assists steering, and the motor according to the motor rotation angle θm. 32 is controlled. As a result, the steering device 10 is realized that enjoys the operation and effect such that the decrease in the detection accuracy of the motor rotation angle θm can be suppressed even when the applied voltage to the operational amplifiers 42a to 42c of the I / F circuit 42 is decreased. be able to. Therefore, even when the power supply voltage Vb temporarily decreases due to sudden steering or the like, a decrease in detection accuracy at the motor rotation angle θm of the motor 32 is suppressed, so that the steering device that can generate torque according to the steering situation by the motor 32. 10 can be provided.

In addition, this invention is not limited to the said embodiment, You may actualize as follows, and even in that case, an effect | action and effect equivalent to the said embodiment are acquired.
(1) The ECU 40 that functions as the resolver signal processing device described above is not limited to processing a signal related to the resolver 33 that detects the motor rotation angle θm of the motor 32 of the transmission ratio variable device 30, and is output from, for example, an assist motor. A signal relating to a resolver that detects a motor rotation angle of an assist motor in a so-called column-type electric power steering apparatus that can transmit the assist force to the pinion shaft via a reduction gear may be processed. The ECU 40 includes a so-called rack-type electric power steering system in which an assist motor and a speed reducer are incorporated in the rack and pinion, and the assist force output from the assist motor can be transmitted to the rack mechanism via the speed reducer. You may process the signal regarding the resolver which detects the motor rotation angle of the assist motor in an apparatus.

(2) The ECU 40 that functions as the resolver signal processing device described above is not limited to processing signals related to the resolver 33, and may process signals related to the two resolvers of the torque sensor 18 in the same manner as the resolver 33.

FIG. 1A is a configuration diagram illustrating a configuration of a steering apparatus according to the present embodiment, and FIG. 1B is a circuit block diagram illustrating a configuration example of an ECU and the like. It is a functional block diagram regarding the control processing of the motor which concerns on this embodiment. It is a flowchart which shows the flow of the motor drive control process by ECU. It is explanatory drawing which shows an example of the power supply voltage-gain map used for a motor drive control process. FIG. 5A is a waveform diagram showing an example of a relationship between an excitation signal and a resolver signal according to the present invention, FIG. 5A is a waveform diagram in a state where an operational amplifier power supply voltage is larger than a threshold voltage, and FIG. It is a wave form diagram in the state where the voltage fell below the threshold voltage. FIG. 6A is a waveform diagram showing an example of a relationship between an excitation signal and a resolver signal according to a conventional example, FIG. 6A is a waveform diagram in a state where an operational amplifier power supply voltage is larger than a threshold voltage, and FIG. It is a wave form diagram in the state where the voltage fell below the threshold voltage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Steering device 32 ... Motor 33 ... Resolver 40 ... ECU (resolver signal processing device)
41 ... MPU
42... I / F circuit 42 a... Operational amplifier (first amplification means)
42b, 42c... Operational amplifier (second amplification means)
51 ... Drive signal generator 52 ... Excitation signal generator (excitation means)
53. Rotation angle calculation unit (rotation angle calculation means)
54 ... Power supply voltage detection unit (voltage detection means)
55... Gain setting section 56... Filter section (filter means)
B ... Battery Sin ... Excitation signal Sout ... Resolver signal Vb ... Power supply voltage (applied voltage)
Vp: threshold voltage θm: motor rotation angle (rotation angle)

Claims (3)

A resolver that outputs a resolver signal corresponding to the rotation angle of the rotor based on the input excitation signal;
Excitation means for generating and outputting the excitation signal;
First amplification means for amplifying the excitation signal from the excitation means and inputting it to the resolver;
Second amplifying means for amplifying the resolver signal output from the resolver;
Rotation angle calculation means for calculating the rotation angle in accordance with the resolver signal amplified by the second amplification means;
Voltage detecting means for detecting an applied voltage applied to the first amplifying means and the second amplifying means for amplifying the signals;
With
The resolver signal processing apparatus according to claim 1, wherein the excitation means reduces the amplitude of the excitation signal in accordance with the applied voltage when the applied voltage detected by the voltage detecting means is equal to or lower than a predetermined threshold voltage.   The resolver according to claim 1, further comprising a filter unit that removes a vibration component of the rotation angle calculated by the rotation angle calculation unit when the amplitude of the excitation signal is reduced by the excitation unit. Signal processing device.   A steering device, wherein the resolver signal processing device according to claim 1 calculates a rotation angle of a motor that assists steering, and controls the motor according to the rotation angle.

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