JP2006158177A - Motor speed control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor speed control circuit of a polygon mirror scanner motor used for a copying machine or LBP which is simple and silent by solving the problem of noise generated at current re-feeding due to damping caused when bringing in from the start of a motor to a target number of rotations. <P>SOLUTION: A clamping means is provided which can arbitrarily set a clamp voltage for operation/non-operation connected parallel to an operation amplifier 12 of a control filter means 10, for a speed instruction signal 5 inputted from outside at starting a motor. So, an imaginary short state of the operation amplifier 12 is kept to smoothly bring to a target number of rotations, for eliminating noises. Controllability of rotational fluctuation characteristics caused by ripple of a torque instruction signal 6 at rated rotation of the motor is not degraded. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor speed control circuit for the purpose of noise countermeasures for OA equipment and a motor equipped with the same.

  Conventionally, the speed control of the motor is compared with the actual rotational speed and the set target speed, and feedback control is performed so that the error becomes zero. At this time, the gain and integral amount of the feedback control system described above are the rotational speed to be controlled. Depending on the load and the load, the response and rotation unevenness are set to the optimum values.In general, to reduce the rotation unevenness, the gain is set to be small or the integral amount is set to be large. In order to increase the gain, the gain is increased or the integral amount is decreased.

  FIG. 7 shows a configuration of a known motor speed control circuit. In FIG. 7, a low active acceleration command signal 101 and a low active deceleration command signal 102 are input to the speed command signal generating means 103, and the output speed command signal 104 is output to an operational amplifier 106 via a first resistor 105. Input to the inverting input side. A series connection of a second resistor 107 and a capacitor 108 is connected between the output side and the inverting input side of the operational amplifier 106. The torque command signal 109 is configured to be a high voltage when the motor is an acceleration command signal, and a low voltage is a deceleration command signal.

  In a known motor speed control circuit, the operation from the start of the motor to the drawing to the target rotational speed will be described with reference to FIG. FIG. 8 is a waveform diagram showing an acceleration command signal 101, a deceleration command signal 102, and a torque command signal 109 when the motor is started by a known motor speed control circuit.

  In the known motor speed control circuit shown in FIG. 7, when the motor is started, a long-term acceleration command signal 101 is input to the speed command signal generating means 103 as shown in section A of FIG. A full acceleration torque command signal is output as 109. As a result, the capacitor 108 is charged, but the imaginary short of the operational amplifier 106 is broken because the capacitor 108 has an infinite resistance value with respect to a DC voltage. After that, the target rotation speed is greatly exceeded, and as a next step, the long-term deceleration command signal 102 is input to the speed command signal generating means 103 as in the section B of FIG. Then, a full deceleration torque command signal is output from the operational amplifier 106 as the torque command signal 109. Then, the imaginary short of the operational amplifier 106 has collapsed, and this time will fall below the target rotational speed. As a result, the acceleration command signal 101 is again input to the speed command signal generation means 103 as shown in the section C of FIG. 8, and the acceleration torque command signal is output again as the torque command signal 109 from the operational amplifier 106, and finally reaches the target rotational speed. Be drawn. That is, as the imaginary short breaks, a current having a steep change due to the full deceleration torque command signal and the reacceleration command signal flows into the motor coil as shown in the sections D and E of FIG. 8, and as a result, the motor vibrates. It will appear as an unusual noise.

  As one method for solving this problem, a configuration has been proposed in which the voltage between both ends between the output side and the inverting input side of the operational amplifier 106 is clamped (see, for example, Patent Document 1).

FIG. 9A shows a configuration of a conventional motor speed control circuit described in Patent Document 1. In FIG. 9A, a low active acceleration command signal 110 and a low active deceleration command signal 111 are input to the speed command signal generating means 112, and the speed command signal 1 which is the output thereof is input.
13 is input to the inverting input side of the operational amplifier 115 through the first resistor 114. A second resistor 116 and a capacitor 117 are connected in series between the output terminal and the inverting input terminal of the operational amplifier 115, and a third diode 118 and a fourth diode 119 are connected in parallel at both ends. The output terminal of the operational amplifier 115 is connected to the anode side of the third diode 118 and the cathode side of the fourth diode 119. In this conventional motor speed control circuit, the operation from the start of the motor to the target rotational speed and the operation during the steady motor rotation will be described with reference to FIGS. 10 and 11, respectively.

  FIG. 10 is a waveform diagram showing an acceleration command signal 110, a deceleration command signal 111, and a torque command signal 120 when the motor is started by a conventional motor speed control circuit. FIG. 11 is a waveform diagram showing a coil current 121, a diode clamping voltage 122, and a torque command signal 123 during steady motor rotation during steady motor rotation by a conventional motor speed control circuit.

  In the conventional motor speed control circuit shown in FIG. 9A, when the motor is started, a long-term acceleration command signal 110 is input to the speed command signal generating means 112 as shown in section F of FIG. A full acceleration torque command signal is output as the command signal 120. When the potential of the output terminal of the operational amplifier 115 rises, the third diode 118 is turned on, a current flows through the third diode 118 and the second resistor 116, and a change in voltage can be quickly fed back. That is, by maintaining the imaginary short state with respect to the speed command signal 113 input from the outside, the response to the output voltage of the operational amplifier 115 is improved and the undershoot amount can be suppressed. Thereafter, the target rotation speed is slightly exceeded, and as a next step, a long-term deceleration command signal 111 is input to the speed command signal generating means 112 as shown in the section G of FIG. As a result, a full deceleration torque command signal is output from the operational amplifier 115 as the torque command signal 120. At this time, the output voltage of the operational amplifier 115 is clamped by a voltage that is about 0.7 V lower than the voltage output from the reference voltage output means 124 by the fourth diode 119, and the amount of undershoot can be suppressed. As a result, the amount below the target rotational speed is suppressed and quickly pulled into the target rotational speed, so that the abnormal noise of the motor can be eliminated as can be determined from the waveform shown in the section H of FIG.

  Further, as shown in FIG. 9B, the third diode 125 and the fourth diode 126 are connected in parallel to the capacitor 117, and the anode of the third diode 125 and the cathode of the fourth diode 126 are connected to the operational amplifier 115. A configuration connected to the output terminal is also proposed as another method for solving this problem (see, for example, Patent Document 2).

The above-described configuration shown in FIG. 9B can provide substantially the same effect as the configuration shown in FIG. 9A described above.
Japanese Utility Model Publication No. 6-74094 (2nd page, FIG. 1) Japanese Examined Patent Publication No. 52-10997 (page 4, Fig. 1)

However, in the conventional motor speed control circuit configuration described above, at the moment when the voltage level of the torque command signal 123 during steady motor rotation shown in FIG. 11 exceeds about 0.7 V which is the clamp voltage 122 of the third diode 118, When the third diode 118 is turned on and the third diode 118 is turned on, a current flows through the third diode 118 and the second resistor 116, and the output voltage of the operational amplifier 115 is immediately fed back. The voltage at the inverting input terminal of the operational amplifier 115 increases. As a result, as the next state, the output voltage of the operational amplifier 115 is lowered and the third diode 118 is turned off. That is, since it is impossible to arbitrarily set a clamp voltage for operating or inactivating the clamp means with respect to the output voltage of the operational amplifier 115, a ripple of the torque command signal 123 occurs during steady motor rotation of FIG. Rotational unevenness was caused by the coil current 121 flowing into the motor coil during steady motor rotation.

  The present invention solves such a conventional problem, and constitutes a clamping means capable of arbitrarily setting a clamp voltage to be operated and deactivated, regardless of an output voltage of an operational amplifier. A simple motor speed control circuit that smoothly pulls in the target rotation speed without losing characteristics at startup, eliminates abnormal noise, and does not impair controllability such as uneven rotation characteristics due to torque command signal ripple during steady motor rotation The purpose is to provide.

  In order to solve the above problems, the present invention provides a reference voltage output means for outputting a reference voltage, a torque control means for inputting a speed command signal from the outside and outputting a torque command signal, and a motor for inputting the torque command signal. Drive means for driving the operational amplifier, the torque control means having an output terminal connected to the drive means, an output of the reference voltage output means connected to a first input terminal, a speed command signal, and the Control filter means configured by a first resistor connected to the second input terminal of the operational amplifier, a parallel connection between the second input terminal and the output terminal of the operational amplifier, and a second resistor and a capacitor connected in series. And a clamp means connected in parallel to the control filter means and capable of arbitrarily setting a clamp voltage. That.

  According to the present invention, when a speed command signal input from the outside at the time of starting the motor is input as an acceleration command, a clamp voltage that can be arbitrarily set to operate and not operate is set in the control filter unit. Since the imaginary short of the operational amplifier is maintained, the amount of undershoot caused by the capacitor charging voltage can be significantly reduced regardless of the output voltage of the operational amplifier, and the target rotation speed is smoothly drawn. It will be resolved.

  In addition, the clamping voltage of the clamping means can be set arbitrarily during normal motor rotation. Since the clamping means is turned off, no ripple is generated by the torque command signal regardless of the output voltage of the operational amplifier. The motor characteristics such as are not impaired. Furthermore, it is possible to easily adjust the amount of undershoot caused by the charging voltage of the capacitor caused by the speed command signal input from the outside, and it is possible to perform optimum voltage conversion for the speed command input from the outside.

  In the embodiment of the present invention, reference voltage output means for outputting a reference voltage, torque control means for inputting a speed command signal from the outside and outputting a torque command signal, and driving the motor by inputting the torque command signal Drive means, the torque control means having an output terminal connected to the drive means, an output of the reference voltage output means connected to the first input terminal, a speed command signal, and a second of the operational amplifier. A first resistor connected to two input terminals, a control filter means connected in parallel to a second input terminal and an output terminal of the operational amplifier, and configured by a series connection of a second resistor and a capacitor; A motor speed control circuit comprising a clamp means connected in parallel to the control filter means and capable of arbitrarily setting a clamp voltage. .

With the above configuration, when a speed command signal input from the outside at the time of motor start-up is input as an acceleration command, it is possible to arbitrarily set a clamp voltage for operation and non-operation in the torque control means. A voltage change can be quickly fed back by a certain clamping means. In other words, the responsiveness to the output voltage of the operational amplifier is improved by keeping the imaginary short state for the speed command signal input from the outside, the amount of undershoot due to the capacitor charging voltage can be significantly reduced, and the target rotation The number is smoothly pulled into the number, and as a result, the abnormal noise at the start of the motor is eliminated.

  During normal motor rotation, the clamping voltage of the clamping means can be set arbitrarily. Since the clamping means is turned off, no ripple is generated due to the torque command signal regardless of the output voltage of the operational amplifier. The motor characteristics such as characteristics are not impaired.

  Furthermore, it is possible to easily adjust the amount of undershoot caused by the charging voltage of the capacitor caused by the speed command signal input from the outside, and it is possible to perform optimum voltage conversion for the speed command input from the outside.

  In the motor speed control circuit, even if the clamp means is connected in parallel to both ends of the capacitor, the same effect can be obtained.

  Further, according to the present invention, the clamping means connected in parallel to the control filter means is composed of a PNP transistor and third and fourth resistors connected to the base terminal thereof, and the other ends of the two resistors are respectively The motor speed control circuit is connected to a power supply line and a ground line, and an emitter terminal of the transistor is connected to an output terminal of the operational amplifier, and a speed command signal input from the outside when the motor is started is accelerated. When input as a command, the potential of the emitter of the PNP transistor in the clamping means exceeds the potential of the base of the PNP transistor divided by the third resistor and the fourth resistor in the power line and the ground line by about 0.7V. The PNP transistor is turned on at the moment, current flows through the collector of the PNP transistor, and the voltage changes quickly. It can be fed back. In other words, the responsiveness to the output voltage of the operational amplifier is improved by keeping the imaginary short state for the speed command signal input from the outside, the amount of undershoot due to the capacitor charging voltage can be significantly reduced, and the target rotation Smoothly pulls into the number, and as a result, the abnormal noise at the start of the motor is eliminated.

  Then, during steady motor rotation, the PNP transistor is turned off by adjusting the resistance values of the third resistor and the fourth resistor. In other words, it is possible to arbitrarily set the clamp voltage that does not operate the clamp means regardless of the output voltage of the operational amplifier at the time of steady motor rotation. Various properties are not impaired.

  Further, the base potential of the PNP transistor divided by the third resistor and the fourth resistor is adjusted in the clamp means regardless of the degree of gain adjustment performed by the control filter means and the operating voltage range of the torque command signal. Thus, the amount of undershoot caused by the charging voltage of the capacitor caused by the speed command signal input from the outside can be easily adjusted, and optimum voltage conversion can be performed for the speed command input from the outside.

  In the above clamping means, the same effect can be obtained even if the collector terminal of the transistor is connected to the second resistor of the control filter means and the relay point of the capacitor.

Further, according to the present invention, the clamp means connected in parallel to the control filter means is composed of first and second diodes, fifth and sixth resistors, and the fifth diode is disposed on the anode side of the first diode. A motor speed control circuit, wherein the anode side of the second diode and the sixth resistor are connected to the resistor side and the cathode side, respectively, and the other end of the fifth resistor is connected to the output terminal of the operational amplifier. The fifth resistor connected to the output terminal of the operational amplifier increases when the potential of the output terminal of the operational amplifier rises by about 1.4 V when the speed command signal input from the outside at the time of starting the motor is input as the acceleration command. Current flows through the first diode connected in series to the fifth resistor and the second diode connected in series to the first diode, and the voltage change is fed quickly. Can back. In other words, the responsiveness to the output voltage of the operational amplifier is improved by keeping the imaginary short state for the speed command signal input from the outside, the amount of undershoot due to the capacitor charging voltage can be significantly reduced, and the target rotation Smoothly pulls into the number, and as a result, the abnormal noise at the start of the motor is eliminated.

  Then, at the time of steady motor rotation, the resistance values of the fifth resistor and the sixth resistor are adjusted, and the relay point of the first diode and the second diode is connected to the ground line via the sixth resistor, By actively lowering the potential on the anode side of the second diode, the second diode is turned off. In other words, it is possible to arbitrarily set the clamp voltage that does not operate the clamp means regardless of the output voltage of the operational amplifier in the steady state, ripples due to the torque command signal do not occur, and various motor characteristics such as rotation unevenness characteristics Will not be damaged.

  Further, the number of first diodes in the clamp means is increased or decreased regardless of the degree of gain adjustment performed by the control filter means and the operating voltage range of the torque command signal, or the fifth resistor and the sixth resistor By adjusting the resistance value, it is possible to easily adjust the amount of undershoot caused by the capacitor charging voltage caused by the speed command signal input from the outside, and it is possible to perform optimum voltage conversion for the speed command input from the outside It is.

  In the above clamping means, even if the cathode side of the second diode is connected to the second resistor of the control filter means and the relay point of the capacitor, the same effect can be obtained.

  Furthermore, the present invention is a motor equipped with the above-described motor speed control circuit. According to this invention, the amount of undershoot caused by the charging voltage of the capacitor caused by the speed command signal input from the outside can be easily adjusted. Because it is possible to perform optimal voltage conversion for the speed command input from the motor, abnormal noise can be solved by smoothly pulling in the target rotational speed when the motor is started, and the torque command signal ripple during steady motor rotation It is possible to provide a motor having a simple speed control circuit that does not impair controllability such as uneven rotation characteristics.

  Embodiments of the present invention will be described below with reference to the drawings.

Example 1
In FIG. 1A, a motor speed control circuit includes a reference voltage output means 1 for outputting a reference voltage, a torque control means 4 for inputting a speed command signal 2 from the outside and outputting a torque command signal 3, and the torque command. Drive means 6 for inputting the signal 3 and driving the motor 5. The torque control means 4 has an output terminal connected to the drive means 6 and a non-inverting input terminal connected to the reference voltage output means 1. An operational amplifier 7, a first resistor 8 having both ends connected to the speed command signal 2 and the inverting input terminal of the operational amplifier 7, a inverting input terminal and an output terminal of the operational amplifier 7 connected in parallel, and a second resistor 9 Control filter means 11 constituted by series connection with a capacitor 10 and a clamp voltage connected in parallel to the control filter means 11 to operate and deactivate are arbitrarily set. Bets is constituted by the clamping means 12 as possible.

  Further, as shown in FIG. 2, the clamping means 12 includes a PNP transistor 13, a base terminal 14 and a power supply line 15, and a base terminal 14 and a ground line 16. The emitter terminal 19 of the transistor 13 is connected to the output terminal of the operational amplifier 7, and the collector terminal 20 of the transistor 13 is connected to the inverting input terminal of the operational amplifier 7.

  The torque command signal 3 is configured to be an acceleration command for the motor 1 at a high voltage and to be a deceleration command at a low voltage.

  The operation during steady motor rotation will be described with reference to FIGS.

  FIG. 5 is a waveform diagram showing an acceleration command signal 21, a deceleration command signal 22, and a torque command signal 3 when the motor is started by the motor speed control circuit according to the embodiment of the present invention. FIG. 6 is a waveform diagram showing the coil current 23, the diode clamping voltage 24, and the torque command signal 25 during steady motor rotation during steady motor rotation by the motor speed control circuit according to the embodiment of the present invention.

  When the motor is started by using the motor speed control circuit of the present invention shown in FIGS. 1 and 2, the long-time acceleration command signal 21 is input to the speed command signal generating means 26 as shown in the section A1 of FIG. Then, a full acceleration torque command signal is output as a torque command signal 3 from the operational amplifier 7. When the potential of the output terminal of the operational amplifier 7 rises, the emitter potential of the PNP transistor 13 in the clamp means 12 is divided into the power line 15 and the ground line 16 by the third resistor 17 and the fourth resistor 18. The PNP transistor 13 is turned on at the moment when the potential at the base exceeds about 0.7 V, and a current flows through the collector of the PNP transistor 13 so that the voltage change can be fed back quickly. That is, by maintaining the imaginary short state with respect to the speed command signal 2 input from the outside, the responsiveness to the output voltage of the operational amplifier 7 is improved, and the amount of undershoot due to the capacitor charging voltage can be remarkably suppressed. As a result, as shown in the section B1 in FIG. 5, the startup time is short, and the abnormal noise of the motor can be eliminated by quickly drawing the target rotational speed.

  Further, during the steady rotation of the motor, the PNP transistor 13 is turned off by adjusting the resistance values of the third resistor 17 and the fourth resistor 18. That is, it is possible to arbitrarily adjust the clamp voltage 24 of the clamp means, and it is possible to arbitrarily set the clamp voltage 24 that does not operate the clamp means 12 regardless of the output voltage of the operational amplifier 7 at the time of steady motor rotation. As can be determined from the coil current 23 during steady motor rotation, no ripple is generated by the torque command signal 25 during steady motor rotation, and the motor characteristics such as rotation unevenness characteristics are not impaired. .

  Further, the PNP transistor 13 divided by the third resistor 17 and the fourth resistor 18 in the clamp unit 12 regardless of the degree of gain adjustment performed by the control filter unit 11 and the operating voltage range of the torque command signal 6. By adjusting the base potential, the amount of undershoot caused by the capacitor charging voltage caused by the speed command signal 2 input from the outside can be easily adjusted, and optimum voltage conversion is performed for the speed command 2 input from the outside. It becomes possible.

  As shown in FIG. 1B, in the motor speed control circuit, even if the clamping means 12 is connected in parallel to both ends of the capacitor 10, that is, the collector terminal 20 of the transistor is inverted of the operational amplifier 7. Even when connected to the relay point of the second resistor 9 and the capacitor 10 connected in series between the input terminal and the output terminal, the same effect as described above can be obtained.

  Further, as shown in FIGS. 4A and 4B, the reference voltage output means 1 is connected to the inverting input terminal via the first resistor 8 and the speed command signal 2 is connected to the non-inverting input terminal. Also, the same effect as described above can be obtained.

In addition, by using a motor equipped with a motor control circuit as described above, the amount of undershoot caused by the capacitor charging voltage caused by the speed command signal input from the outside can be easily adjusted. It is possible to perform optimal voltage conversion for the motor, so that abnormal noise can be solved by smoothly pulling in the target rotation speed when starting the motor, and control of rotation unevenness characteristics etc. due to torque command signal ripple during steady motor rotation It is possible to provide a motor having a simple speed control circuit that does not impair the performance.

(Example 2)
Another embodiment of the present invention is shown in FIG. The clamping means 12 of another embodiment has a configuration in which the fifth resistor 28 is connected to the anode of the first diode 27, and the sixth resistor 29 and the anode of the second diode 30 are connected to the cathode of the diode. is doing. The other end of the sixth resistor 29 is connected to the ground line 31, the other end of the fifth resistor 28 is connected to the output terminal of the operational amplifier 7 shown in FIG. 1, and the cathode of the second diode 30 is connected to the operational amplifier. 7 are respectively connected to the inverting input terminals.

  By using the motor speed control circuit of the present invention, as shown in FIG. 5, when the motor is started, a long-term acceleration command signal 21 is input to the speed command signal generating means 26, and the torque command signal 3 is fully output from the operational amplifier 7. An acceleration torque command signal is output. When the potential at the output terminal of the operational amplifier 7 rises by about 1.4 V, a fifth resistor 28 connected to the output terminal of the operational amplifier 7, a first diode 27 connected in series to the fifth resistor 28, A current flows through the second diode 30 and the voltage change can be fed back quickly. In other words, the responsiveness to the output voltage of the operational amplifier 7 is improved by maintaining the imaginary short state with respect to the speed command signal 2 input from the outside, and the amount of undershoot due to the charging voltage of the capacitor 10 can be significantly reduced. Then, the target rotational speed is smoothly drawn, and as a result, the abnormal noise at the start of the motor is eliminated.

  In addition, during steady motor rotation, the resistance values of the fifth resistor 28 and the sixth resistor 29 are adjusted, and the relay point of the first diode 27 and the second diode 30 is grounded via the sixth resistor 29. The second diode 30 is turned off by connecting to the line 31 and actively lowering the anode side potential of the second diode 30. That is, it is possible to arbitrarily set the clamp voltage 24 that does not operate the clamp means regardless of the output voltage of the operational amplifier 7 during steady rotation of the motor. The motor characteristics such as are not impaired.

  Further, regardless of the degree of gain adjustment performed by the control filter unit 11 and the operating voltage range of the torque command signal 3, the number of the first diodes 27 in the clamp unit 12 is increased or decreased, or the fifth resistor 28 and By adjusting the resistance value of the sixth resistor 29, the amount of undershoot caused by the charging voltage of the capacitor caused by the speed command signal 2 input from the outside can be easily adjusted, and the optimum for the speed command 2 input from the outside Voltage conversion can be performed.

  As in the first embodiment, as shown in FIG. 1B, the present clamping means is configured such that the cathode of the second diode 30 is connected in series between the inverting input terminal and the output terminal of the operational amplifier 7. Even when connected to the relay point of the second resistor 9 and the capacitor 10, the same effect as described above can be obtained.

  Further, as shown in FIGS. 4A and 4B, the reference voltage output means 1 is connected to the inverting input terminal via the first resistor 8 and the speed command signal 2 is connected to the non-inverting input terminal. Also, the same effect as described above can be obtained.

Further, the order of the first resistor 8 and the capacitor 10 configured in the control filter unit 11 in the torque control unit 4 is fixed, and the order in which the second resistor 9 and the capacitor 10 are connected is configured in reverse. Further, the control filter means 11 can be implemented in the same manner. Further, by adopting a motor equipped with the motor control circuit as described above, the capacitor charging voltage caused by the speed command signal input from the outside can be used. The amount of undershoot can be adjusted easily and optimal voltage conversion can be performed for the speed command input from the outside. Therefore, noise can be solved by smoothly pulling in the target rotation speed when starting the motor. A motor equipped with a simple speed control circuit that does not impair controllability such as uneven rotation characteristics due to ripples in the torque command signal during steady rotation Can be provided.

  The motor speed control circuit of the present invention can be used as a control circuit for a polygon mirror scanner motor for OA.

(A) is a circuit diagram showing a motor speed control circuit according to the first and second embodiments of the present invention, and (b) is a circuit diagram showing another motor speed control circuit according to the first and second embodiments of the present invention. The circuit diagram which shows the structure of the clamp means of the motor speed control circuit by Example 1 of this invention. The circuit diagram which shows the structure of the clamp means of the motor speed control circuit by Example 2 of this invention (A) is a circuit diagram showing a motor speed control circuit according to the first and second embodiments of the present invention, and (b) is a circuit diagram showing another motor speed control circuit according to the first and second embodiments of the present invention. Waveform diagrams showing an acceleration command signal, a deceleration command signal, and a torque command signal at the time of starting the motor according to the first and second embodiments of the present invention FIG. 4 is a waveform diagram showing a coil current, a clamp voltage of a clamp circuit, and a torque command signal during normal motor rotation during normal motor rotation according to the first and second embodiments of the present invention. Circuit diagram showing a known motor speed control circuit Waveform diagram showing acceleration command signal, deceleration command signal, and torque command signal when the motor is started by a known motor speed control circuit (A) is a circuit diagram showing a conventional motor speed control circuit, (b) is a circuit diagram showing another conventional motor speed control circuit Waveform diagram showing acceleration command signal, deceleration command signal, and torque command signal when the motor is started by a conventional motor speed control circuit Waveform diagram showing coil current, diode clamp voltage, and torque command signal at steady motor rotation during motor steady rotation by a conventional motor speed control circuit

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reference voltage output means 2 Speed command signal 4 Torque control means 3 Torque command signal 5 Motor 6 Drive means 7 Operational amplifier 8 1st resistance 9 2nd resistance 10 Capacitor 11 Control filter means 12 Clamp means 13 PNP transistor 14 Base terminal 15 Power line 16 Ground line 17 Third resistor 18 Fourth resistor 19 Emitter terminal 20 Collector terminal 24 Clamp voltage 27 First diode 28 Fifth resistor 29 Sixth resistor 30 Second diode

Claims (5)

Reference voltage output means for outputting a reference voltage, torque control means for inputting a speed command signal from the outside and outputting a torque command signal, drive means for driving the motor by inputting the torque command signal, The torque control means has an output terminal connected to the drive means, an output of the reference voltage output means connected to a first input terminal, an operational amplifier connected to a speed command signal, and a second input terminal of the operational amplifier. Control filter means connected in parallel to the first resistor, the second input terminal and the output terminal of the operational amplifier, and connected in series with a second resistor and a capacitor, and connected in parallel to the control filter means And the clamp means for setting the both ends of the control filter means to a constant potential when the output voltage of the operational amplifier becomes a voltage higher than a certain level. Motor speed control circuit according to claim. Reference voltage output means for outputting a reference voltage, torque control means for inputting a speed command signal from the outside and outputting a torque command signal, drive means for driving the motor by inputting the torque command signal, The torque control means has an output terminal connected to the drive means, an output of the reference voltage output means connected to a first input terminal, an operational amplifier connected to a speed command signal, and a second input terminal of the operational amplifier. Control filter means connected in parallel to a first resistor, a second input terminal and an output terminal of the operational amplifier, and connected in series with a second resistor and a capacitor, and connected in parallel to both ends of the capacitor. And a clamp means for setting the both ends of the capacitor to a constant potential when the output voltage of the operational amplifier becomes a predetermined voltage or higher. Motor speed control circuit for. The clamp means includes a PNP transistor and third and fourth resistors connected to the base terminal thereof, and the other ends of the resistors are connected to a power supply line and a ground line, respectively. 3. The motor speed control circuit according to claim 1, wherein a terminal is connected to an output terminal of the operational amplifier. The clamp means includes first and second diodes, and fifth and sixth resistors. The fifth resistor is on the anode side of the first diode, and the anode side of the second diode is on the cathode side. 3. The motor speed control circuit according to claim 1, wherein a second resistor and a sixth resistor are connected to each other, and the other end of the fifth resistor is connected to an output terminal of the operational amplifier. A motor equipped with the motor speed control circuit according to any one of claims 1 to 4.

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