JP2005227072A - Signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive signal processor capable of enhancing resolution for only a portion necessary for fine control to enhance control performance. <P>SOLUTION: This signal processor 1 for processing a voltage signal V0 output from a sensor 2 is provided with an amplifying means A2 for amplifying the voltage signal V0 to be output, when the voltage signal V0 is within a certain range, and an output means A1 for outputting the voltage signal V0 as it is. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an improvement in a sensor signal processing apparatus.

  In general, in a control device that detects current flowing in a circuit of a device equipped with a sensor with a sensor and performs feedback control based on this current value, only a digital signal can be processed, so an analog voltage output by the sensor In processing the signal, it must be converted into a digital signal via an A / D converter and processed.

  Here, if expensive A / D converters and arithmetic processing devices are used, the entire device including the signal processing device becomes expensive. From the viewpoint of cost, the costs for the A / D converter and arithmetic processing devices are as much as possible. If so, it is preferable to reduce it.

  Therefore, A / D converters and arithmetic processing devices with high resolution (reading voltage per bit) are very expensive. Therefore, it is desirable to use A / D converters and arithmetic processing devices with low resolution as much as possible.

  However, with an A / D converter or arithmetic processing device with low resolution, for example, when controlling a high-output motor, particularly when a minute current must be controlled, there is a risk that sufficient control cannot be performed. There is.

  Therefore, in order to increase the resolution of the sensor output, there is one in which a signal processing circuit is provided between the sensor and the A / D converter. Specifically, in this type of signal processing apparatus, for example, when a voltage signal detected by a sensor is converted into an analog signal and a digital signal by an A / D converter, the digital signal overflows or the voltage signal is in a full range. In the case of reaching the above, there is known an amplifier that outputs with a gain reduced by a voltage signal (see, for example, Patent Documents 1 and 2).

In addition, by switching the reference voltage of the amplifier in several steps according to the voltage signal output from the sensor and amplifying the voltage signal, the voltage signal is divided by dividing the detection range into multiple ones aimed at improving the resolution. There is also known one in which an amplifier circuit for amplifying the signal is provided for each divided range (see, for example, Patent Documents 3 and 4).
JP-A-4-291519 (page 3, left column, line 15 to page 3, right column, line 17, line 1) Japanese Patent Laid-Open No. 11-274930 (column of embodiment of the invention, FIG. 1) Japanese Patent Laid-Open No. 9-96651 (Example column, FIG. 1) JP-A-6-307911 (paragraph numbers 0009 to 0014, FIGS. 2 and 4)

  However, the signal processing apparatus described above does not only amplify the voltage signal but also changes the gain and the reference voltage, and therefore uses a dedicated circuit and element for that purpose. Becomes expensive.

  In addition, when an amplification circuit for amplifying a voltage signal is provided by dividing the detection range into a number of parts, the gain is determined in the divided range, and the resolution of only a part cannot be increased. If only the resolution is increased, the number of amplifier circuits increases correspondingly, resulting in an expensive signal processing apparatus.

  Therefore, the present invention was devised to improve the above-described problems, and the object of the present invention is to improve the control performance by increasing the resolution only for the parts that are inexpensive and necessary for precise control. It is providing the signal processing apparatus which can aim at.

  In order to achieve the above object, in a control device that controls a current flowing in a circuit by feeding back a voltage signal output from a sensor that detects a current flowing in the circuit, the voltage signal is output when the voltage signal is within a certain range. Amplifying means for amplifying and outputting, output means for outputting the voltage signal as it is, and control means for processing each signal output from the amplifying means and the output means to control the current, When the voltage signal corresponding to the command current to be supplied to the circuit is within a certain range, current control is performed based on the output signal of the amplification means, and when the voltage signal corresponding to the command current is not within the certain range, the output means The current control is performed based on the output signal.

  According to the present invention, it is possible to increase the resolution of only the part necessary for precise control.

  In addition, unlike the conventional signal processing device, when the gain is changed or the reference voltage is changed, the arithmetic processing device is not used, but a dedicated circuit is used. Therefore, it is necessary to control the signal processing device itself. There is no. In addition, since it is not necessary to change the gain and the reference voltage each time, it is not necessary to mount an element for changing the signal, so that the signal processing apparatus is inexpensive.

  Furthermore, since it is not necessary to change the gain and reference voltage each time as compared with the conventional signal processing device that makes the gain and reference voltage variable, it is not necessary to mount an element for changing the element, etc. As a result, the variation in products due to the accuracy of the signal processing device can be eliminated, so that the variation in products of the signal processing apparatus can be reduced.

  The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a block diagram in which a signal processing device according to an embodiment is applied to a motor. FIG. 2 is a block diagram conceptually showing the signal processing apparatus according to the embodiment. FIG. 3 is a diagram illustrating a relationship between a voltage output from the signal processing device and a voltage signal output from the sensor according to the embodiment. FIG. 4 is a circuit diagram of a signal processing device according to an embodiment. FIG. 5 is a conceptual diagram of an electromagnetic shock absorber to which the signal processing device according to one embodiment is applied.

  As shown in FIG. 1, the signal processing apparatus 1 in one embodiment is connected to a current sensor 2 that detects a current flowing in a coil of a motor M configured as a brushless motor, and A / D converters 3a and 3b. Then, the voltage signal output from the current sensor 2 is processed and output to the A / D converters 3a and 3b. The A / D converters 3a and 3b convert the analog voltage output from the signal processing device 1 into a digital signal and output the digital signal to the arithmetic processing device 4. Further, the arithmetic processing unit 4 is used for controlling the motor M. Although not specifically illustrated, the arithmetic processing unit 4 includes a CPU, a storage device such as a ROM and a RAM, and a control program for driving the motor M is Pre-stored in the storage device.

  Incidentally, the motor M is provided with U, V, and W three-phase coils, and a current sensor 2 is provided for each of the U, V, and W coils. In addition, the arithmetic processing unit 4 outputs a drive command to the drive circuit 5 so as to perform feedback control on the current flowing through each coil using the current value detected by each current sensor 2 as feedback. Therefore, current control is performed for each coil.

  The drive circuit 5 is for driving the motor M in accordance with a drive command output from the arithmetic processing unit 4. In the present embodiment, the drive circuit 5 is configured as a brushless motor. Is composed of, for example, a PWM circuit connected to a voltage source, a base drive circuit connected to the PWM circuit, a transistor inverter connected to the base drive circuit, and a rotation logic to which the Hall element H is connected. A well-known thing can be used.

  That is, the signal processing device 1 can be applied to a known motor control system. In the present embodiment, the voltage signal V0 of the current sensor 2 is set so as to be output within the range of 0v to 5v. When 2.5V is output, the voltage signal V0 flows to the coil of the motor M. The current is set to indicate zero.

  As shown in FIG. 2, the signal processing device 1 basically includes an output means A1 that outputs the voltage signal V0 output from the current sensor 2 as it is, and when the voltage signal V0 is within a certain range. Amplifying means A2 for amplifying and outputting the voltage signal V0 with a voltage having a median value in a certain range as a neutral point. The output terminals of the output means A1 and the amplification means A2 are connected to the A / D converters 3a and 3b.

  Therefore, when the gain of the amplification means A2 is 3, for example, and the neutral point is 2.5 v, the voltage signal V0 output from the current sensor 2, the voltage Va1 output from the output means A1 of the signal processing device 1, and the amplification means As shown in FIG. 3, the voltage Va1 output from the output means A1 takes a value equal to the voltage signal V0, and the voltage Va2 output from the amplification means A2 is about 1 when the voltage signal V0 is about 1, as shown in FIG. The value is three times the voltage signal V0 in the range of .67v to about 3.33v. That is, a certain range in this case is a range where the voltage signal V0 is about 1.67v to about 3.33v.

  Then, for example, if the A / D converter 3b has 10 bits, the A / D converters 3a and 3b convert the voltage signal output from the current sensor 2 into a power of 2 or a voltage step of 1024. However, if the voltage signal V0 is in the range from about 1.67v to about 3.33v in the present embodiment, as shown in FIG. Since the voltage Va2 output from the means A2 changes with a gain three times that of the voltage signal V0, when the voltage signal V0 is within this range, the resolution per bit of the A / D converter 3b is tripled. Is equal to

  Here, the specific control of the motor M will be described briefly. The arithmetic processing unit 4 determines that the voltage signal V0 is about 1.67v to about 3 from each digital signal transmitted from the A / D converters 3a and 3b. When it is within the range up to .33v, the digital signal output from the A / D converter 3b is adopted, and when it is outside the above range, the digital signal output from the A / D converter 3a is adopted, and the above-mentioned adoption is adopted. The motor M is controlled by issuing a drive command (current command) to control the current flowing in the coil of the motor M using the digital signal as feedback.

  Therefore, in the signal processing device 1 of the present embodiment, the current sensor 2 indicates that a relatively weak current is flowing through the coil of the motor M, that is, the current flowing through the coil of the motor M is near zero. It becomes possible to increase the resolution in the state, whereby the control performance of the motor M when the current flowing through the coil of the motor M is close to 0 is improved. In particular, when the motor M has a high output, the resolution of the A / D converters 3a and 3b deteriorates. Even in such a case, the resolution can be achieved by spot-zooming only when the current is near zero. Therefore, the control performance of the motor M is greatly improved. In other words, since the resolution in which the current flowing through the coil of the motor M is near zero is improved, it can be accurately determined whether or not the motor M is driven. Therefore, it is possible to increase the resolution of only the part necessary for precise control.

  When the voltage signal V0 is about 1.67v or less or about 3.33v or more, the voltage Va1 is controlled by the output means A1, and in this case, the A / D converter 3 is controlled. However, since the current supplied to the motor M is relatively large, it is necessary to perform more precise control than when controlling by determining whether or not the motor M is driven. There is no problem in practical use.

  Therefore, unlike the conventional signal processing apparatus, when the gain is changed or the reference voltage is changed, a dedicated circuit is used instead of the arithmetic processing apparatus, so that it is necessary to control the signal processing apparatus itself. There is no. In addition, since it is not necessary to change the gain and the reference voltage each time, it is not necessary to mount an element for changing the signal, so that the signal processing apparatus is inexpensive. And since the voltage signal of only the part necessary for control is amplified and outputted, the signal processing device is divided even when compared with the conventional signal processing device which divides the detection range into several and has an amplification circuit for amplifying the voltage signal Is cheaper.

  Furthermore, since it is not necessary to change the gain and reference voltage each time as compared with the conventional signal processing device that makes the gain and reference voltage variable, it is not necessary to mount an element for changing the element, etc. As a result, the variation in products due to the accuracy of the signal processing device can be eliminated, so that the variation in products of the signal processing apparatus can be reduced.

  Note that a plurality of certain ranges in the voltage signal V0 may be provided, and an amplifying unit may be provided for each certain range.

  Although the signal processing apparatus 1 in the present embodiment has been conceptually described above, the specific configuration will be described below.

  For example, as shown in FIG. 4, a specific signal processing apparatus 1 is produced by dividing a voltage of a follower circuit H1 to which a voltage signal V0 is non-inverted and a voltage source provided separately by a variable resistor VR1. A follower circuit H2 to which a voltage (hereinafter referred to as a reference voltage) having a median value in a range is input non-inverted, and an output of the follower circuit H1 is inverted and a first output of the follower circuit H2 is non-inverted. The operational amplifier OP1, the operational amplifier OP2 in which the output of the first operational amplifier OP1 is inverted and the output of the follower circuit H2 is non-inverted, and the output of the first operational amplifier OP1 is inverted and the output of the follower circuit H2 is non-inverted. Second operational amplifier OP3, a plurality of feedback amplification resistors R7 and R8 connected to the second operational amplifier OP3, the first operational amplifier OP1, and the operational amplifier OP2. Amplifying resistors R1, R2, R3, and R4 are connected to each other, and resistors R5, R6, and R9 are used for current offset. In this case, the output means A1 includes the first operational amplifier OP1, the operational amplifier OP2, and the like. The amplification means A2 includes a first operational amplifier OP1, a second operational amplifier OP3, feedback amplification resistors R7, R8, and amplification resistors R1, R2. It is configured.

  It is possible to change the reference voltage by adjusting the resistance value of the variable resistor VR1, and in this embodiment, the reference voltage is adjusted to 2.5V.

  In the present embodiment, as described above, since the gain in the amplification means A2 is 3, the resistance ratio of the feedback amplification resistors R7 and R8 is set to be R7: R8 = 1: 3. Since the amplification resistors R1, R2, R3, and R4 connected to the first operational amplifier OP1 and the operational amplifier OP2 output the voltage signal V0 as they are, their resistance ratios are R1: R2 = 1: 1, R3: R4. = 1: 1. The follower circuits H1 and H2 are provided for the buffer and may be omitted.

  The specific signal processing apparatus 1 is configured as described above, and the output means A1 outputs the voltage signal V0 as it is, while the amplifying means A2 has the reference voltage as a neutral point. The voltage signal V0 is tripled and output around 5v. Therefore, its output matches that shown in FIG.

  As described above, the signal processing device 1 can have a very simple configuration, and there is no need to receive control of the arithmetic processing device 4 or the like on the way, and the voltage output from the current sensor 2 within a necessary range. The gain for the signal can be set, and the signal processing apparatus can be manufactured at low cost. In the present embodiment, the voltage signal always passes through the operational amplifier until the signal processing device outputs it. Even if the current sensor 2 outputs an excessive voltage signal for some reason, On the operational amplifier side, output exceeding the bias voltage cannot be performed, so that an excessive voltage is not loaded on the A / D converter or the like connected to the signal processing device, and equipment damage is also prevented.

  In the above, the control of the motor M, particularly the control of the high-power motor, particularly when the current flowing through the coil of the motor M is used to improve the control near 0, the effect is high. In the signal processing apparatus 1, the reference voltage can be changed as appropriate, and the reference voltage and the amplification factor in the second operational amplifier OP3 are set so that the signal processing apparatus is optimal for a device that is actually used. It can also be set arbitrarily.

  Incidentally, the motor M is used as a damping force generating element of an electromagnetic shock absorber mounted on a vehicle, that is, as shown in FIG. 5, the electromagnetic shock absorber is converted into a motor M and a rotary motion into a linear motion. The ball screw nut 11 and the screw shaft 12 and a conversion mechanism 10 such as a rack and pinion are used to connect the motor M to one of the vehicle body side and the axle side and to connect the ball screw nut 11 to the other of the vehicle body side and the axle side. When the linear motion of the electromagnetic shock absorber is suppressed or controlled by the torque generated by the motor M, the vertical movement of the shock absorber may cause discomfort to the person riding in the vehicle, In particular, the movement of the shock absorber in the vertical direction has a large effect on the person riding in the vehicle, and the current flowing through the coil of the motor M is close to zero. When the resolution of the poor, without appropriate control is performed, as a result, ride comfort is deteriorated in a vehicle. Here, it is very important to determine whether or not the current flowing through the coil is 0. If the resolution is poor, current supply is performed when the actual current supply should not be performed, or vice versa. This is because humans are sensitive to the operation of the electromagnetic shock absorber caused by whether or not the slight current flows through the coil, and feel a sense of incongruity. Therefore, when the signal processing device 1 according to the present embodiment is applied to the electromagnetic shock absorber described above, the resolution of the current flowing through the coil of the motor M near 0 can be increased. The controllability when the current flowing in the vicinity of 0 is improved, so that the above-described adverse effects can be eliminated, and the motor M applied to the electromagnetic shock absorber as described above is optimal.

  In the present embodiment, the case where the sensor output of the current sensor is processed has been described. Needless to say, it is possible to process the signal output by the sensor that detects the state quantity.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is the block diagram which applied the signal processing device in one embodiment to the motor. It is a block diagram which shows notionally the signal processing apparatus in one embodiment. It is the figure which showed the relationship between the voltage which the signal processing apparatus in one Embodiment outputs, and the voltage signal which a sensor outputs. It is a circuit diagram of the signal processing device in one embodiment. It is a conceptual diagram of the electromagnetic buffer to which the signal processing device in one embodiment is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Signal processing apparatus 2 Current sensor 3a, 3b A / D converter 4 Arithmetic processing apparatus 5 Drive circuit 10 Conversion mechanism 11 Ball screw nut 12 Screw shaft A1 Output means A2 Amplifying means M Motor OP1 1st operational amplifier OP2 Operational amplifier OP3 2nd Operational amplifiers R1, R2, R3, R4 Amplifying resistors R5, R6, R9 Resistors R7, R8 Feedback amplifying resistors VR1 Variable resistors

Claims (4)

A signal processing apparatus for processing a voltage signal output from a sensor, comprising: an amplifying means for amplifying and outputting the voltage signal when the voltage signal is within a certain range; and an output means for outputting the voltage signal as it is. A signal processing apparatus characterized by comprising: 2. The signal processing apparatus according to claim 1, wherein the amplifying means amplifies the voltage signal with a voltage having a median value within a certain range as a neutral point. Amplifying means includes a first operational amplifier to which a voltage signal is non-inverted and inputted to a voltage having a median value within a certain range, and a voltage output from the first operational amplifier is inverted and inputted to a median value within a certain range. The signal processing device according to claim 2, comprising: a second operational amplifier to which the voltage is non-inverted and a plurality of feedback amplification resistors connected to the second operational amplifier. The sensor detects the current flowing through the coil in the motor of the electromagnetic shock absorber provided with the screw shaft and the motor that are rotatably screwed into the ball screw nut, and the sensor outputs when the current flowing through the coil is zero. 4. The signal processing apparatus according to claim 2, wherein a value of the voltage signal to be performed is a neutral point.

Images