JP3680631B2 - 5-phase stepping motor drive unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a driving device for a five-phase stepping motor in which excitation windings are connected to a pentagon, and in particular, to reduce variations in the rotational speed of the rotor when performing half-step control, The present invention relates to a drive device for a five-phase stepping motor capable of making the rotational accuracy as uniform as possible.
[0002]
[Prior art]
  A five-phase stepping motor is generally composed of a stator on which five excitation windings are wound and a rotor having permanent magnet poles, and has a smaller step angle than a two-phase stepping motor. It is an excellent stepping motor in that it can reduce torque fluctuation and improve vibration characteristics. However, in the case of a five-phase stepping motor, the number of excitation windings and driver circuits are increased compared to a two-phase stepping motor, resulting in an increase in cost.
  There are five types of 5-phase stepping motors, such as standard connection and pentagon connection, depending on the connection method of the excitation winding. In general, twice as many switching transistors are required for the standard connection as compared to the pentagon connection. It is. In addition, a large number of amplifiers necessary for constant current control must be provided, which increases the cost.
  Further, as a driving method of the five-phase stepping motor, there is a half-step driving method that sequentially switches between four-phase excitation and five-phase excitation, in addition to the full-step driving method of five-phase excitation. This half-step drive system is often used for measures against vibration and noise because it has the effect of reducing fluctuations in generated torque compared to full-step drive.
[0003]
[Problems to be solved by the invention]
  However, when half-step driving is performed using a 5-phase stepping motor connected with the Pentagon, when switching from 4-phase excitation to 5-phase excitation, the rotor does not rotate sufficiently and no particular problem occurs. When switching to four-phase excitation, there is a problem that the rotation of the rotor is insufficient, the rotational speed varies, and the rotational accuracy of the rotor in a state where a load is connected deteriorates.
  An object of the present invention is to solve the above-described problems, and when a half-step drive is employed using a pentagon-connected five-phase stepping motor, variation in the rotational speed of the rotor is reduced. An object of the present invention is to provide a drive device for a five-phase stepping motor that can make the rotational accuracy of a rotor in a state where a load is connected as uniform as possible.
[0004]
[Means for Solving the Problems]
  In order to achieve this object, according to the first aspect of the present invention, the respective phase windings of the five-phase stepping motor are sequentially connected to form a pentagon connection, and the switching means is connected to the connection point of these respective phase windings. In the driving device for a five-phase stepping motor that enables half-step control for sequentially switching between four-phase excitation and five-phase excitation by switching control of the ON / OFF state of the switching means, When switching to the four-phase excitation, there is provided a current attenuation rate increasing means for quickly attenuating the regenerative current flowing in the phase winding connected to the switching means that is newly turned on.,  The switching means is configured to perform DC chopper control that repeats an on state and an off state, and the current decay rate increasing means is newly turned on when switching from the five-phase excitation to the four-phase excitation. The DC chopper control performed for the switching means that has become the stop means, and holding means for holding the high current decay state for a predetermined time only, the smaller the duty of the DC chopper control, or the phase winding The holding time of the high current attenuation state by the holding means is shortened as the flowing current is smaller, the voltage applied to the phase winding is larger, or the inductance of the phase winding is smaller. Features.
[0005]
  As a result, when switching from the five-phase excitation to the four-phase excitation, a regenerative current flows through the phase winding connected to the switching means that is newly turned on, the regenerative current has a low decay rate, and the rotational speed of the rotor However, since the current decay rate increasing means quickly attenuates the regenerative current flowing through the phase winding, the adverse effect on the rotation of the rotor can be prevented, and the rotor in a state where the load is connected. Make the rotation accuracy as uniform as possible.
[0006]
[0007]
  Also,When the holding means switches from the five-phase excitation to the four-phase excitation, the holding means stops the DC chopper control performed for the switching means that is newly turned on, and maintains the high current attenuation state. When the regenerative current flowing through the wire flows in a state where the potential difference is large, the regenerative current flowing through the phase winding is quickly attenuated and serves as a means for increasing the current attenuation rate. Thereby, the adverse effect on the rotation of the rotor is prevented, and the rotational accuracy of the rotor in a state where the load is connected is made uniform compared to the conventional case.
[0008]
[0009]
  Furthermore,The high current attenuation state is maintained for a predetermined time to attenuate the regenerative current flowing in the phase winding, and when the regenerative current is sufficiently attenuated, the high current attenuation state is released, and as a means for increasing the current attenuation rate End the function.
  In addition, when the regenerative current flowing through the phase winding attenuates within a predetermined time for performing the four-phase excitation, the four-phase excitation is continued, and during the time for attenuating the regenerative current flowing through the phase winding. In addition, when it is time to switch from four-phase excitation to five-phase excitation, a mode of immediately switching from four-phase excitation to five-phase excitation may be employed. The reason for carrying out such control is that the four-phase excitation and the five-phase excitation are performed according to the control command of the driving device for the five-phase stepping motor, depending on whether the rotation speed of the rotor is increased or decreased. This is because the drive time consumed varies and the drive time is not always constant. As a result, even if the drive time spent for the four-phase excitation and the five-phase excitation varies, the drive device for the five-phase stepping motor of the present invention is the four-phase excitation at the stage when the function as the current decay rate increasing means is completed. Smooth switching control from 5 to 5 phase excitation can be performed.
[0010]
[0011]
  Also, the smaller the DC chopper control duty is, or the smaller the current flowing through the phase winding is,AppliedThe larger the applied voltage or the smaller the inductance of the phase winding, the shorter the regenerative current that flows through the phase winding. As a result, the holding time of the high current decay state can be shortened, the function as the current decay rate increasing means can be completed quickly, and smooth switching control from five-phase excitation to four-phase excitation can be performed.
[0012]
  Claims2According to the invention described in claim1In the drive device for the five-phase stepping motor described in the above, a measuring means for measuring the time of the DC chopper control OFF state is provided, and the high current attenuation state is maintained based on the measured value of the measuring means. And
  As described above, when the DC chopper control is stopped and held in a high current attenuation state, the regenerative current flowing through the phase winding flows in a state with a large potential difference. The DC chopper control OFF state time that is held in the state is measured, the OFF state time is adjusted based on the measured value, and when the regenerative current is attenuated, the high current attenuation state can be terminated.
[0013]
  Claims3According to the invention described in claim1In the drive device for the five-phase stepping motor described in the above, the detecting means for detecting the regenerative current flowing in the phase winding connected to the switching means that is newly turned on when switching from the five-phase excitation to the four-phase excitation. And the high current attenuation state is maintained based on a detection value of the detection means.
  As a result, the high current decay state can be maintained until the detected regenerative current becomes substantially zero, for example.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a drive device for a 5-phase stepping motor according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an overall outline of a driving device 1 for a five-phase stepping motor M according to the present embodiment. FIG. 2 is a timing chart for performing half-step control for sequentially switching between four-phase excitation and five-phase excitation for the five-phase stepping motor M. 3 to 7 are circuit diagrams showing the five-phase stepping motor M and the motor drive circuit 2. FIG. 3 shows a current flow in the five-phase excitation state, and FIG. 4 shows the four-phase excitation state. FIG. 5 shows the current flow during a transient phenomenon when all of the transistor elements T1 to T10 as switching means are turned off from the four-phase excitation state, and FIG. 6 shows the four-phase current flow. The flow of current when only the transistor element T5 of the transistor elements T1 to T10 is turned on from the excited state is shown. FIG. 7 shows the current flow during the next five-phase excitation.
  The five-phase stepping motor M of this embodiment is driven in the X-axis direction to move the cloth support frame for supporting the work cloth of the sewing machine in the XY directions with respect to the sewing needle of the sewing machine that moves up and down exclusively. It can be used for motors and Y-axis direction drive motors.
[0015]
  As shown in FIGS. 3 to 7, the driving device 1 for the five-phase stepping motor M includes first, second, third, fourth, and fifth excitation windings (hereinafter referred to as A phase, B phase, C phase, D-phase and E-phase windings are sequentially connected to form a Pentagon connection, and ten transistor elements T1 to T10 in the motor drive circuit 2 are connected to connection points of these phase windings.
  Specifically, the phase windings of the A phase and the E phase of the five-phase stepping motor M are electrically connected at the connection point S1. Similarly, the phase windings of the A phase and the B phase are connected at the connection point S3, the phase windings of the B phase and the C phase are connected at the connection point S5, and the phase windings of the C phase and the D phase are connected at the connection point. Connected at S7, D-phase and E-phase windings are connected at connection point S9.
  In the motor drive circuit 2, the emitter terminals of the transistor elements T1, T3, T5, T7, and T9 are connected to the high voltage terminal side of the power source V, and the emitter terminals of the transistor elements T2, T4, T6, T8, and T10 are connected. It is connected to the 0V (low voltage) terminal side of the power supply V.
[0016]
  The collector terminal of the transistor element T1 and the collector terminal of the transistor element T2 are connected at the connection point S2, and the connection point S1 and the connection point S2 are connected. Similarly, the collector terminal of the transistor element T3 and the collector terminal of the transistor element T4 are connected at the connection point S4, and the connection point S3 and the connection point S4 are connected. Further, the collector terminal of the transistor element T5 and the collector terminal of the transistor element T6 are connected at the connection point S6, and the connection point S5 and the connection point S6 are connected.
  Further, the collector terminal of the transistor element T7 and the collector terminal of the transistor element T8 are connected at the connection point S8, and the connection point S7 and the connection point S8 are connected. Further, the collector terminal of the transistor element T9 and the collector terminal of the transistor element T10 are connected at the connection point S10, and the connection point S9 and the connection point S10 are connected. A drive signal DS (described later) output from the motor drive circuit 2 is input to the base terminals of the transistor elements T1 to T10.
  Further, diodes D1 to D10 are connected to the ten transistor elements T1 to T10 between the emitter terminals and the collector terminals, respectively. These diodes D1 to D10 are turned off from the on state of the transistor elements T1 to T10. It works to flow a regenerative current when switching to a state.
[0017]
  Then, the motor drive circuit 2 appropriately applies an excitation current to the phase windings of the A phase, the B phase, the C phase, the D phase, and the E phase based on the driving / non-driving of the transistor elements T1 to T10 in the driving device 1. To control the rotor to rotate by a predetermined amount. In this case, the driving device 1 of the five-phase stepping motor M enables half-step control that sequentially switches between four-phase excitation and five-phase excitation by appropriately controlling driving / non-driving of the transistor elements T1 to T10.
[0018]
  As shown in FIG. 1, in addition to the motor drive circuit 2, the driving device 1 further includes an excitation phase counter 3, an excitation phase decoder 4, an excitation control logic 5, an output control logic 6, a current detection unit 7, a constant current control. Section 8 and a set time counter 9.
  The excitation phase counter 3 is connected to a CPU 10 as a control circuit. The excitation phase counter 3 receives the clock signal CLK output from the CPU 10 and the direction signal DIR indicating the rotation direction of the rotor, and thereby outputs the phase count signal SR indicating the excitation phase to the excitation phase decoder 4 and the excitation control. Can be output to logic 5.
[0019]
  The excitation phase counter 3 counts up at the edge of the rising edge of the clock signal CLK input from the CPU 10 when the direction signal DIR input from the CPU 10 is in a low state (eg, forward rotation), whereas the direction signal DIR Is in a high state (for example, reverse rotation), it counts down at the edge of the rising signal of the clock signal CLK.
  The excitation phase decoder 4 outputs an excitation phase signal RS to the output control logic 6 based on the phase count signal SR input from the excitation phase counter 3. This excitation phase signal RS is for switching the excitation phase of each phase winding of A phase, B phase, C phase, D phase, and E phase.
[0020]
  The control logic 6 that has received the excitation phase signal RS from the excitation phase decoder 4 outputs a drive signal DS corresponding to the excitation phase signal RS to the motor drive circuit 2, and therefore, ten transistor elements T 1 in the motor drive circuit 2. The drive signal DS is input to the base terminals of T10 to T10.
  Accordingly, the drive circuit 2 controlled by the output control logic 6 performs, for example, five-phase excitation at time Q1 in FIG. 2 (see FIG. 3), and excitation current is applied to the C-phase phase winding at time Q2 in FIG. After performing the four-phase excitation without flowing (see FIG. 4), the mode of repeating the five-phase excitation again (see FIG. 7) at time Q3 in FIG. 2 is repeated, and as time advances from time Q4 to time Q7, 5 Switch sequentially between phase excitation and four-phase excitation.
[0021]
  The current detection unit 7 is for detecting the current flowing through the A-phase, B-phase, C-phase, D-phase, and E-phase windings. The detected current is supplied to the constant current control unit 8. Output. Thus, based on the current detected by the current detector 7, the constant current controller 8 is turned on (on time for supplying voltage from the power supply V) and off (off time when no voltage is supplied from the power supply V). ) Is performed (see FIG. 2).
  The reason for such constant current chopper drive control is that the inductance of each phase winding
Due to the influence of this, a delay time occurs at the rise of the excitation current, so that a shortage of torque associated with an increase in the motor drive frequency is prevented to withstand high-speed rotation drive, which is supplied during the on-time. By supplying energy to each phase winding by voltage and releasing energy from each phase winding during off-time, the magnetic flux generated from each phase winding is adjusted, and the rotor is rotated by a predetermined amount. To do.
  Therefore, the constant current control unit 8 outputs the switching signal ST based on the current detected by the current detection unit 7 to the output control logic 6, and the output control logic 6 outputs the drive signal DS to the motor drive circuit 2. Output to. In this case, the motor drive circuit 2 performs DC chopper control that repeats an ON state and an OFF state as shown in FIG. 2, but based on the current detected by the current detection unit 7, the duty of the constant current DC chopper control (The ratio of the ON time in the drive signal) is changed. That is, when the current detected by the detection unit 7 is large, the duty of the direct current chopper control is reduced, whereas when the current detected by the detection unit 7 is small, the duty of the direct current chopper control is increased.
[0022]
  Further, since the excitation control logic 5 inputs the phase count signal SR, the clock signal CLK, and the direction signal DIR output from the excitation phase counter 3, the designation signal SD is created based on these signals. The designation signal SD is output to the output control logic 6. The designation signal SD is for designating the transistor elements T1 to T10 that hold the DC chopper control of the transistor elements T1 to T10 for a predetermined time and maintain the high current attenuation state.
  Specifically, with respect to the DC chopper control shown at time Q2 in FIG. 2, for example, the DC chopper control performed on the transistor element T5 is stopped for a predetermined time QA and connected to the collector terminal side of the transistor element T5. S5 and S6 are held in a high potential state.
[0023]
  A set time counter 9 is connected to the excitation control logic 5, and the set time counter 9 is a DC chopper control stop time (for example, 1.5 ms) for any one of the designated transistor elements T1 to T10. Can be set).
  In this case, the set time counter 9 starts counting the stop time of the DC chopper control of about 1.5 ms, for example, by inputting the clock signal CLK from the excitation phase counter 3, and counts the stop time of the DC chopper control. When is finished, the end signal SY is output. As a result, the excitation control logic 5 sends to the output control logic 6 a designation signal SD indicating that the designated transistor elements T1 to T10 start holding the on state and release (end) the holding of the on state. Output.
[0024]
  Therefore, in this embodiment, the designation signal SD is a direct current chopper control for predetermined transistor elements T1 to T10 (for example, transistor element T5) that are turned on when switching from five-phase excitation to the next four-phase excitation. This function notifies the start time and end time of the stop time and instructs to perform DC chopper control after the stop time.
[0025]
  Accordingly, the output control logic 6 functions as a holding unit that stops the direct current chopper control and maintains the high current decay state, and outputs the drive signal DS to the ten transistor elements T1 to T10 of the motor drive circuit 2. In this case, when switching from the five-phase excitation to the next four-phase excitation, the predetermined transistor elements T1 to T10 (for example, the transistor element T5 at time Q2) are switched from the off state to the on state. At that time, for example, the DC chopper control is stopped for about 1.5 ms and the ON state is continued, and then the DC chopper control is started, and the ON state transistor elements T1 to T10 (in this case, T1 to T4, T6). With respect to .about.T10), the direct current chopper control is started immediately after switching from the off state to the on state. Thereby, at the connection point S5, the high potential state is maintained only for a predetermined time (for example, about 1.5 ms), and the four-phase excitation is continued when the regenerative current flowing through the phase winding is attenuated within the predetermined time. The
[0026]
  Next, the current flowing through the phase windings of the A phase, B phase, C phase, D phase, and E phase will be described. Here, the vertical axis of FIG. 2 shows the driving states of the ten transistor elements T1 to T10 in order to pass the exciting current through the phase windings of the A phase, B phase, C phase, D phase, and E phase. That is, the upper side of the horizontal axis of each phase indicates the ON state of the upper transistor elements T1, T3, T5, T7, T9, and the lower side of the horizontal axis of each phase indicates the lower transistor elements T2, T4, T6. , T8, and T10 are turned on. The horizontal axis indicates time, and indicates that the excitation current flowing through the phase winding is switched over time.
  For example, at time Q1 in FIG. 2, the excitation phase signal RS output from the excitation phase decoder 4 to the output control logic 6 is for five-phase excitation, so the drive signal DS is the transistor elements T1, T4, T7. , A drive signal for controlling the DC chopper is output to the base of T10, the transistor elements T1, T4, T7, T10 are turned on, and the other transistor elements T2, T3, T5, T6, T8, T9 are turned off. And
[0027]
  Thereby, the high voltage terminal side of the power source V is connected to the connection point S2 and the connection point S8 via the transistor elements T1 and T7 as shown in FIG.AppliedAs a result, the connection point S1 and the connection point S7 become high potential, and the 0V terminal side of the power source V is connected to the connection point S4 and the connection point S10 via the transistor elements T4 and T10.AppliedAs a result, the connection point S3 and the connection point S9 become low potential.
  Therefore, the motor drive circuit 2 applies an excitation current to the E-phase phase winding from the connection point S1 to the connection point S9 and excites the A-phase phase winding from the connection point S1 to the connection point S3. Apply current. Similarly, an exciting current is passed through the D-phase phase winding from the connection point S7 to the connection point S9, and the C-phase and B-phase phases are passed from the connection point S7 to the connection point S3 via the connection point S5. Apply exciting current to the winding.
[0028]
  Thereafter, the excitation phase decoder 4 outputs the next excitation phase signal RS to the output control logic 6, and the control logic 6 outputs a drive signal DS corresponding to the excitation phase signal RS to the motor drive circuit 2. In this case, at the time Q2 in FIG. 2, the five-phase excitation is switched to the next four-phase excitation. The excitation phase signal RS is a signal for switching only the transistor element T5 from the off state to the on state among the transistor elements T1 to T10 and maintaining the other transistor elements T1 to T4 and T6 to T10 in the previous state.
  Accordingly, when only the transistor element T5 is switched from the off state to the on state, the high potential state is maintained at the connection point S1 and the connection point S7, and the low potential state is maintained at the connection point S3 and the connection point S9. In this state, the high voltage terminal side of the power source V is connected to the connection point S6 via the transistor element T5.AppliedAs a result, the potential at the connection point S5 becomes high.
[0029]
  In this case, as in FIG. 3, a regenerative current like a dotted line transiently flows in the C-phase phase winding from the connection point S7 to the connection point S5. It stops flowing and becomes 4-phase excitation. Therefore, as shown in FIG. 4, the motor drive circuit 2 causes an excitation current to flow through the E-phase phase winding from the connection point S1 to the connection point S9, and also from the connection point S1 to the connection point S3. An excitation current is passed through the phase winding of the phase, and an excitation current is passed through the phase winding of the D phase from the connection point S7 to the connection point S9. Similarly, an exciting current is passed through the B-phase winding from the connection point S5 to the connection point S3.
[0030]
  Thereafter, the excitation phase decoder 4 outputs the next excitation phase signal RS to the output control logic 6, and the control logic 6 outputs a drive signal DS corresponding to the excitation phase signal RS to the motor drive circuit 2. In this case, at time Q3 in FIG. 2, the four-phase excitation is switched to the next five-phase excitation. As shown in FIG. 7, the excitation phase signal RS is a signal for switching only the transistor element T7 from the on state to the off state and maintaining the other transistor elements T1 to T6 and T8 to T10 in the previous state.
  Thereby, the high voltage terminal side of the power supply V is connected to the connection point S2 and the connection point S6 via the transistor elements T1 and T5.AppliedThen, the connection point S1 and the connection point S5 are at a high potential, and the 0V terminal side of the power supply V is connected to the connection point S3 and the connection point S9 via the transistor elements T4 and T10.AppliedTherefore, the connection point S3 and the connection point S9 are at a low potential.
[0031]
  Therefore, the motor drive circuit 2 causes the exciting current to flow through the phase winding of the E phase from the connection point S1 to the connection point S9 as shown in FIG. An exciting current is passed through the phase winding of the A phase toward the connection point S3. Similarly, the motor drive circuit 2 causes an excitation current to flow through the B-phase phase winding from the connection point S5 to the connection point S3, and from the connection point S5 to the connection point S9 via the connection point S7. And an exciting current is passed through the phase winding of the D phase.
  Hereinafter, the mode in which the five-phase excitation is switched to the next four-phase excitation by the excitation phase signal RS and the excitation current is supplied to the predetermined phase winding is similarly repeated.
[0032]
  Here, a transient phenomenon when the DC chopper control is turned off will be described. When all of the ten transistor elements T1 to T10 are turned off from the state of FIG. 4, that is, the off signal side of the DC chopper control is connected to the base terminals of the transistor elements T1 to T10.AppliedIn this case, the coils of the A-phase to E-phase windings generate an electromotive force based on the inductive reactance so that the regenerative current flows in the direction in which the excitation current that has flown so far continues. First to fourth current routes (A) to (D) are formed (see FIG. 5).
[0033]
  That is, (A) From the 0V terminal side of the power supply V to the diode D8, the connection point S8, the connection point S7, the phase winding of the D phase, the connection point S9, the connection point S10, the diode D9, and the high voltage terminal side of the power supply V (B) Current from the 0V terminal side of the power supply V to the diode D8, the connection point S8, the connection point S7, the phase winding of the C phase, the connection point S5, and the 0V terminal side of the power supply V To the diode D6, the connection point S6, and the current to the connection point S5 are combined with the B-phase phase winding, the connection point S3, the connection point S4, the diode D3, and the second current to the high voltage terminal side of the power source V. Route, (C) From the 0V terminal side of the power source V to the diode D2, the connection point S2, the connection point S1, the phase winding of the A phase, the connection point S3, the connection point S4, the diode D3, and the high voltage terminal side of the power source V (D) From the 0V terminal side of the power supply V, De D2, connection point S2, the connection points S1, E-phase phase windings, connection points S9, the connection point S10, diode D9, a fourth current route to the high voltage terminal side of the power source V is formed. The current flowing through the first to fourth current routes flows back to the power source V by passing through the phase windings and the diodes D2, D3, D6, D8, and D9, and is attenuated.
[0034]
  Thereafter, the state returns to the state shown in FIG. 4, and a DC chopper control ON signal is applied to the bases of the transistor elements T1, T4, T5, T7, and T10.AppliedIn this case, the transistor elements T1, T4, T5, T7, and T10 are turned on, and the other transistor elements T2, T3, T6, T8, and T9 remain in the off state. As a result, as shown in FIG. 4, an exciting current flows through the phase winding of the E phase from the connection point S1 toward the connection point S9, and the phase winding of the A phase proceeds from the connection point S1 toward the connection point S3. Excitation current is supplied, excitation current is supplied to the D-phase phase winding from the connection point S7 to the connection point S9, and excitation current is supplied to the B-phase phase winding from the connection point S5 to the connection point S3. .
[0035]
  Here, comparing FIG. 4 with FIG. 5 (transient state immediately after switching from five-phase excitation to four-phase excitation), in FIG. 5, the phase winding of the C phase from connection point S7 to connection point S5. On the other hand, at the end of the transient phenomenon in FIG. 4, no exciting current flows through the C-phase phase winding. The regenerative current that flows through the C-phase winding as shown by the dotted line adversely affects the rotation of the rotor when switching from five-phase excitation to four-phase excitation, and the rotor does not rotate quickly. Variations in the rotational speed of the rotor occur between when switching to five-phase excitation, causing problems such as poor rotor rotational accuracy when a load is connected.
[0036]
  FIG. 8 is an explanatory diagram showing the rotation of the rotor (not shown) of the 5-phase stepping motor M, and graph a (showing an example with good rotational accuracy) and graph b (showing an example with poor rotational accuracy) The horizontal axis shows the amount of rotation of the rotor as time passes.
  In the case of graph b, when switching from four-phase excitation to five-phase excitation (from state b2 to state b3), the rotor rotates sufficiently and there is no particular problem, but when switching from five-phase excitation to four-phase excitation (from state b1 to state) b2) It can be seen that the rotation of the rotor is insufficient. On the other hand, in the case of graph a, when switching from 4 phase excitation to 5 phase excitation (state a2 to state a3) and when switching from 5 phase excitation to 4 phase excitation (state a1 to state a2), the rotor rotates sufficiently. You can see that
[0037]
  Next, a current decay rate increasing means for quickly attenuating the regenerative current flowing through the C-phase phase winding will be described.
  In the case of this embodiment, when switching from 5-phase excitation to 4-phase excitation, the DC chopper control performed on the transistor element T5 that is newly turned on is stopped for a predetermined time and held in a high potential state. Thus, the regenerative current flowing through the phase winding of the C phase is quickly attenuated.
  Specifically, at the time QA in FIG. 2, all of the ten transistor elements T1 to T10 are not turned off when the DC chopper control is turned off, and as shown in FIG. DC chopper control ON signal only for a predetermined timeAppliedIn this case, the transistor element T5 is turned on, and the other transistor elements T1 to T4 and T6 to T10 are turned off.
[0038]
  Then, as in FIG. 5, the coils of the A-phase to E-phase phase windings are based on their inductive reactances, so that an electromotive force that causes the regenerative current to flow in the direction in which the excitation current that has flown so far continues to flow. In addition to the formation of the first, third and fourth current routes as shown in FIGS. 6A, 6C and 6D, the transistor element T5 is turned on. (B ′) From the 0V terminal side of the power supply V, from the diode D8, the connection point S8, the connection point S7, the phase winding of the C phase, the current to the connection point S5, and the high voltage terminal of the power supply V , The transistor element T5, the connection point S6, and the current up to the connection point S5, the B-phase phase winding, the connection point S3, the connection point S4, the diode D3, the fifth current toward the high voltage terminal side of the power source V A route is formed. Here, since the transistor element T5 is turned on, as a result, the connection point S6 and the connection point S5 are held in a high potential state, and a large potential difference is generated between the connection point S7 and the connection point S5.
[0039]
  In this case, the regenerative current that flows in the C-phase phase winding from the connection point S7 toward the connection point S5 flows toward the high potential state at the connection point S5. It decays quickly. This is because when the regenerative current that flows in the C-phase winding flows toward the high potential state, the coil of the C-phase winding loses a large amount of energy. This is because the flowing regenerative current decays rapidly.
  When performing the four-phase excitation after performing the five-phase excitation in this way, the transistor elements T1, T4, T7, T10 shown in FIG. 4 are turned on (transistor elements T2, T3, T5, T6, T8, and T9 are turned off) and the transistor element T5 shown in FIG. 6 is turned on (the other transistor elements T1 to T4 and T6 to T10 are turned off). The regenerative current that flows is rapidly attenuated to improve the interruption of the regenerative current, and the rise of the excitation current that flows in the B-phase winding based on the ON state of the transistor element T5 is accelerated. Here, since the regenerative current flowing through the phase winding of the B phase is at a high potential together with the connection points S5 and S3, the current decay rate with respect to time is low, and as a result, the rise of the excitation current is accelerated.
[0040]
  Then, after the time QA at time Q2 in FIG. 2 has elapsed and the regenerative current flowing through the C-phase phase winding is sufficiently attenuated, the transistor elements T1, T4, T7, and T10 shown in FIG. T2, T3, T5, T6, T8, and T9 are in the OFF state) and DC chopper control that repeats all the transistor elements T1 to T10 shown in FIG. 5 in the OFF state is performed, and the A phase, B phase, D phase, Control is performed so that the rotor is rotated by a predetermined amount by appropriately applying an exciting current to the phase winding of the E phase.
  Here, the current decay rate of the regenerative current flowing in the C-phase winding immediately after the transistor element T5 shown in FIG. 3 is switched from the OFF state to the ON state of the transistor element T5 shown in FIG. It is preferable in terms of control that the current attenuation rate of the current flowing in the phase B phase winding immediately after the transistor element T5 shown in FIG. 6 is switched from the OFF state to the transistor ON state shown in FIG. Similarly, the current decay rate of the current flowing in the C-phase winding immediately after the transistor element T5 shown in FIG. 3 is switched from the OFF state to the ON state of the transistor element T5 shown in FIG. 6 is shown in FIG. It is preferable that the rate of increase in current flowing through the B-phase winding immediately after the transistor element T5 is switched from the off state to the on state of the transistor element T5 shown in FIG.
[0041]
  In the case of the 5-phase excitation shown in FIG. 3, the excitation current flows from the connection point S7 to the connection point S3 through the connection point S5 to the B-phase and C-phase windings. The current value of the exciting current of the wire is about half that of the exciting current flowing in the other phase windings of the A, D, and E phases. As a result, when the duty of the pulse width modulation method (PWM control method) is 0.5, the time until the current flowing through the C-phase winding becomes zero and the current flowing through the B-phase winding are The time for which the current value of the exciting current flowing in the phase windings of the other A, D, and E phases is equal is substantially the same. Therefore, it is desirable to set conditions such as the magnitude of the drive voltage so that the duty of the pulse width modulation method (PWM control method) is 0.5 or less.
  Also, the smaller the DC chopper control duty is, or the smaller the current flowing through the phase winding is,AppliedThe larger the applied voltage or the smaller the inductance of the phase winding, the shorter the time for the regenerative current to become zero, so the holding time of the high current decay state can be shortened.
[0042]
  As described above in detail, the A-phase to E-phase windings of the five-phase stepping motor M of the present embodiment are sequentially connected to form a pentagon connection, and the connection points of the A-phase to E-phase windings. Transistor elements T1 to T10 are connected to S1, S3, S5, S7, and S9, respectively, and the on / off state of the transistor elements T1 to T10 is controlled to be switched, thereby sequentially switching between four-phase excitation and five-phase excitation. In the driving device 1 of the five-phase stepping motor M that enables step control, when switching from five-phase excitation to four-phase excitation, the regenerative current that flows in the phase winding of the C-phase connected to the transistor element T5 that is newly turned on In order to attenuate the current quickly, the connection point S5 is set to a high potential state to increase the current attenuation rate. For example, the regenerative current flowing in the phase winding of the C phase is switched from the five-phase excitation to the four-phase excitation. When obtaining, thereby preventing an adverse effect on the rotation of the rotor. Thereby, there is no problem that the rotation of the rotor is insufficient and the rotation speed of the rotor varies, so that the rotation accuracy of the rotor with the load connected can be made as uniform as possible.
[0043]
  Although the present invention has been described with respect to the above-described embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be easily made without departing from the spirit of the present invention. It can be guessed.
  For example, in the present embodiment, the driving device 1 of the step motor M for moving the cloth support frame of the sewing machine has been described, but the step motor M of the present invention can also be applied to other uses. In addition, when the regenerative current flowing through the phase winding is attenuated within a predetermined time for performing the four-phase excitation, the four-phase excitation is continued, but during the time for attenuating the regenerative current flowing through the phase winding. In addition, when it is time to switch from four-phase excitation to five-phase excitation, a mode in which switching from four-phase excitation to five-phase excitation is performed immediately may be employed.
[0044]
  The reason why such control is performed is that the four-phase excitation and the five-phase excitation are performed according to whether the rotational speed of the rotor is increased to a high speed or a low speed according to a control command of the driving device of the 5-phase stepping motor M. This is because the driving time spent for the operation fluctuates and the driving time is not always constant. Therefore, even if the drive time spent for the four-phase excitation and the five-phase excitation varies, smooth switching control from the four-phase excitation to the five-phase excitation is completed at the stage when the time for maintaining the high potential state at the connection point S5 is completed. Can do.
  In addition, the pulse width modulation method (PWM control method) is adopted as the drive control of the five-phase stepping motor. However, if a half-step drive is adopted using a pentagon-connected five-phase stepping motor, other than this It is of course possible to apply control. Further, when switching from 5-phase excitation to 4-phase excitation as the current decay rate increasing means, a mode is adopted in which the DC chopper control performed on the newly turned on transistor is stopped and held at the high potential state. In addition, for example, a regenerative current flowing in a phase winding connected to a transistor that is newly turned on may be dropped to the negative potential side or may be passed through a resistor by using switching means.
[0045]
  Moreover, you may employ | adopt the following aspects as control of a current decay rate raising means.
  For example, by configuring the constant current control unit 8 that receives a signal from the current detection unit 7 shown in FIG. 1 to output an on signal / off signal at the time of DC chopper control to the set time counter 9. The set time counter 9 may measure the time when the DC chopper control is in the off state, and adjust the off time with this measured value. This is because, as described above, when the regenerative current flowing through the phase winding flows in a state where the potential difference is large in the state of maintaining the high current attenuation state due to the stop of the DC chopper control, the regenerative current is attenuated over time. This is because the time of the stop (off signal) state of the direct current chopper control is measured, and the off time is adjusted with this measured value so that the regenerative current approaches zero as much as possible.
  In this case, the set time counter 9 functions as a measuring means for measuring the time during which the DC chopper control is off, and when the duty of the DC chopper control varies, the DC chopper control off time is counted and the regenerative current is By adjusting the off time until attenuation, the excitation control logic 5 controls to maintain the high current attenuation state only for a necessary time.
[0046]
  In addition, a current sensor (not shown) for detecting the current flowing in each phase winding of the A phase, B phase, C phase, D phase, and E phase is provided as detection means, When switching to the four-phase excitation, a regenerative current flowing in a phase winding (for example, a C-phase phase winding) connected to the transistor elements T1 to T10 that are newly turned on is detected. Then, when the current sensor detects the timing when the regenerative current becomes zero, the excitation control logic 5 releases the stop of the direct current chopper control and releases the holding of the high current attenuation state. Also good. However, it is not necessary to directly detect the timing when the regenerative current becomes zero, and the regenerative current may be detected indirectly.
[0047]
【The invention's effect】
  As described above, according to the invention described in claim 1, the respective phase windings of the five-phase stepping motor are sequentially connected to form a pentagon connection, and the switching means is connected to the connection point of each of these phase windings. In the drive device of the 5-phase stepping motor that enables half-step control to sequentially switch between the 4-phase excitation and the 5-phase excitation by controlling the ON / OFF state of the switching means, When switching to phase excitation, there is provided a current decay rate increasing means for quickly attenuating the regenerative current flowing in the phase winding connected to the switching means that is newly turned on, so that the regenerative current flowing in the phase winding is faster As a result of the attenuation, it is possible to prevent the regenerative current from adversely affecting the rotation of the rotor and causing variations in the rotational speed. Thereby, the rotational speed of the rotor becomes uniform, and the rotational accuracy of the rotor in a state where the load is connected becomes uniform as compared with the conventional case.
[0048]
  Also,PreviousThe switching means is configured to perform direct current chopper control that repeats an on state and an off state, and the current decay rate increasing means is newly turned on when switching from the five-phase excitation to the four-phase excitation. Since there is a holding means for stopping the DC chopper control performed on the switching means that has become and maintaining a high current decay state, the regenerative current that flows in the phase winding flows in a state with a high potential difference, so that the phase winding The regenerative current flowing through the wire is quickly attenuated and serves as a means for increasing the current attenuation rate. Accordingly, the regenerative current flowing through the phase windings is prevented from adversely affecting the rotation of the rotor, and the rotational accuracy of the rotor with the load connected is made as uniform as possible.
[0049]
  Also, KeepSince the holding means holds the high current decay state only for a predetermined time, the function as the current decay rate increasing means can be terminated when the predetermined time has elapsed. Thereby, the regenerative current is attenuated within a predetermined time, and the rotation accuracy of the rotor can be improved when switching from the five-phase excitation to the four-phase excitation.
[0050]
  Also,PreviousThe smaller the DC chopper control duty is, or the smaller the current flowing through the phase winding is,AppliedThe higher the applied voltage or the smaller the inductance of the phase winding, the shorter the holding time of the high current decay state, and the smooth switching control from five-phase excitation to four-phase excitation is possible. Can do.
[0051]
  Claims2According to the invention described in (4), the measuring means for measuring the time of the off state of the DC chopper control is provided, and the high current attenuation state is maintained based on the measurement value of the measuring means, so the duty of the DC chopper control is When it fluctuates, the DC chopper control OFF state time is adjusted based on the measured value, and when the regenerative current is attenuated, the high current attenuation state can be terminated.
[0052]
  Further claims3According to the present invention, when switching from the five-phase excitation to the four-phase excitation, the detection means for detecting the regenerative current flowing in the phase winding connected to the switching means that is newly turned on is provided. Since the high current attenuation state is maintained based on the detected value of the means, the high current attenuation state can be maintained until the detected regenerative current becomes substantially zero, for example.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall outline of a drive device for a five-phase stepping motor according to this embodiment.
FIG. 2 is a timing chart showing half-step control for sequentially switching between four-phase excitation and five-phase excitation for a five-phase stepping motor.
FIG. 3 is a circuit diagram showing a five-phase stepping motor and a motor drive circuit, and shows a current flow in a five-phase excitation state.
FIG. 4 is a circuit diagram showing a current flow in a four-phase excitation state.
FIG. 5 is a circuit diagram showing a current flow when all transistor elements are turned off from a four-phase excitation state;
FIG. 6 is a circuit diagram showing a current flow when a part of the transistor elements are turned on and the remaining transistor elements are turned off from the four-phase excitation state.
FIG. 7 is a circuit diagram showing a current flow in the next five-phase excitation state.
FIG. 8 is an explanatory diagram showing the feeding of the rotor of this five-phase stepping motor.
[Explanation of symbols]
  M 5-phase stepping motor
  1 5-phase stepping motor drive device
  2 Motor drive circuit
  3 Excitation phase counter
  4 Excitation phase decoder
  5 Excitation control logic
  6 Output control logic
  7 Current detector
  8 Constant current controller
  9 Set time counter
  10 CPU
  QA stop time
  T1 to T10 transistor elements
  D1-D10 diode
  CLK clock signal
  DIR direction signal
  SR phase count signal
  RS excitation phase signal
  ST switching signal
  SD designation signal
  DS drive signal

Claims (3)

By connecting the respective phase windings of the five-phase stepping motor in order to form a Pentagon connection, switching means is connected to the connection points of these respective phase windings, and switching control of the on / off state of the switching means is performed. In the drive device for a 5-phase stepping motor that enables half-step control for sequentially switching between phase excitation and 5-phase excitation,
When switching from the five-phase excitation to the four-phase excitation, a current attenuation rate increasing means is provided for quickly attenuating the regenerative current flowing in the phase winding connected to the switching means that is newly turned on ,
The switching means is configured to perform direct current chopper control that repeats an on state and an off state,
When the current decay rate increasing means switches from the five-phase excitation to the four-phase excitation, the current decay rate increasing means stops the direct current chopper control for the switching means that is newly turned on, and sets the high current decay state for a predetermined time. Having only holding means,
The smaller the duty of the DC chopper control, the smaller the current flowing through the phase winding, the greater the voltage applied to the phase winding, or the smaller the inductance of the phase winding, 5. A driving device for a five-phase stepping motor, wherein a holding time of the high current decay state by the holding means is shortened. In the drive device of the 5-phase stepping motor according to claim 1,
  5. A driving device for a five-phase stepping motor, characterized in that measuring means for measuring the time during which the DC chopper control is off is provided, and the high current decay state is maintained based on the measurement value of the measuring means. In the drive device of the 5-phase stepping motor according to claim 1,
  When switching from the five-phase excitation to the four-phase excitation, a detection means for detecting a regenerative current flowing in the phase winding connected to the switching means that is newly turned on is provided, and based on the detection value of the detection means, A driving device for a five-phase stepping motor, characterized in that the high current decay state is maintained.

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