JP2004266974A - Micro step method for stepping motor and stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel micro step method using a conventionally used circuit, and a stepping motor driven by this micro step method. <P>SOLUTION: All the three phases U to W are constantly kept in excited state at least when the stepping motor is driven. The rate of output of the excitation pattern in a basic step and the excitation pattern in the next basic step is varied by gradually increasing or decreasing it on a step-by-step basis. The portions between the basic steps are segmented. The PWM frequency from a constant-current control circuit 2 and the excitation pattern outputted from an excitation pattern generation circuit 1 are synchronized with each other. The number of times of the output of excitation pattern from the excitation pattern generation circuit 1 is controlled to carry out micro step driving. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a microstepping method in which microstep driving (multi-division driving) in a radially connected N-phase stepping motor is always performed with all N phases in an excited state when the stepping motor is driven, and stepping driven by the microstepping method. Motor related.
[0002]
[Prior art]
The stepping motor has a plurality of phases (windings), and by exciting each phase with an excitation pattern corresponding to the basic step, a combined torque vector corresponding to the basic step is obtained. By changing the excitation pattern to the excitation pattern of another basic step, the resultant torque vector can be advanced to a position corresponding to the new basic step, thereby rotating the stepping motor by a predetermined rotation angle. It has become.
[0003]
The stepping motor is basically driven to a predetermined angular position by an excitation pattern of a basic step repeatedly output until the next pulse is input and the step is advanced. Each time the next pulse is input and the step advances one step, the step is driven to the angular position by the excitation pattern of the new basic step. This drive is called full-step drive.
[0004]
The step driving of the radially connected three-phase stepping motor will be briefly described below with reference to FIGS. FIG. 1 shows a motor connection diagram showing the coil windings of the radially connected three-phase stepping motor, the direction of the exciting current and the torque vector, and FIG. 2 shows the torque vector diagram in FIG. In FIG. 1, the arrows of each phase represent the direction of the current, and are shown corresponding to U, V, W, u, v, w on the torque vector diagram.
[0005]
Now, when the U-phase terminal is connected to the positive electrode and the V-phase and W-phase terminals are connected to the negative electrode, a current indicated by a solid arrow flows in the U phase, and a torque vector U is generated. The current shown flows and a torque vector v is generated, and also in the W phase, the current shown by the dotted arrow flows and a torque vector w is generated. When the torque vectors U, v, w generated in each phase are represented on the torque vector diagram of FIG. 2, the resultant torque vector of the generated torque vectors U, v, w is a vector in the U direction of FIG.
[0006]
A torque vector generated in each phase according to the direction of the current flowing in each phase at this time is expressed as vUw or the like, and is called an excitation pattern. Driving the combined torque vector step by step at every adjacent basic step, for example, U → w → V → u → W → v → U, is called full-step driving. In each of the intermediate angles, in the above example, the intermediate angle position between U and w is set next to U for each step, and the half-step drive of half the basic step is performed so that the position becomes w in the next step. Called driving. In addition, a method in which the basic steps are divided into multiple divisions at each step is referred to as micro-step driving (multi-division driving). It is about.
[0007]
Conventionally, there have been various proposals for micro-step driving by multi-division driving more than half-step driving. Each phase current detection circuit, pulse width modulation pattern generation circuit, voltage instruction pattern generation circuit, PWM pulse generation circuit, current command circuit, output Micro-step driving is performed by adding a stage switching duty correction circuit and the like to a conventional circuit.
[0008]
Generally, as a micro-step drive in a three-phase or five-phase stepping motor, a method of individually detecting a current flowing in each phase and controlling the current of each phase has been conventionally performed (for example, see Patent Document 1). . Also, when switching from the previous excitation pattern to the next excitation pattern at each step, the excitation current of a certain excitation phase among the five phases is output duty controlled at each step to gradually increase or decrease, so that the output vector of the excitation phase is obtained. (See, for example, Patent Document 2) and a micro-step drive in which a single phase is reversely excited as a combination of excitation patterns in a five-phase stepping motor (for example, see Patent Document 2). 3) has been proposed.
[0009]
Conventionally, as disclosed in Patent Document 1 as a conventional example, a method of controlling a current of each phase by individually detecting a current flowing in each phase is performed. In this method, the number of the current detection circuits and the number of the control circuits are required by the number of phases, which not only complicates the circuit but also makes it difficult to adjust the variation of the current detection circuits of each phase. Also, since the number of current detection circuits and control circuits is required by the number of phases, various problems such as an increase in cost have been encountered.
[0010]
Also, the one described in Patent Document 2 will be described with reference to FIGS. 15 and 16. As shown in FIG. 15, A-phase, C-phase, and E-phase phase coils 21, 23, 25, and B-phase, The phase coils 22 and 24 of the D phase are in opposite phases to each other and one ends thereof are commonly connected to form a radial connection. The other ends of the phase coils 21, 23, 25, 22, and 24 of the A phase, the C phase, the E phase, the B phase, and the D phase are connected to the positive electrode of the power supply 27 via transistors TAP, TCP, TEP, TBP, and TDP respectively. + And the negative electrode − of the power supply 27 via the transistors TAN, TCN, TEN, TBN, and TDN respectively.
[0011]
For each step, a series circuit of a first phase coil group for exciting two or three phase coils in parallel and a second phase coil group for exciting other phase coils in parallel are formed, as shown in FIG. Duty control is performed on the current of one of the three phase coils excited in parallel.
That is, assuming that the “ON” period in FIG. 16 is 1, k is turned on in the period of 0 <k <1.
[0012]
The device described in Patent Document 2 controls the output vector of the excitation phase. However, since there is no method for forcibly canceling the current remaining in the excitation phase to be controlled, an expected value for the duty setting is not obtained. The above current continues to flow, and there is a problem that the multi-division driving becomes difficult due to the remaining current.
[0013]
Further, the one described in Patent Document 3 is a method in which, in a radially connected five-phase stepping motor, a current that continues to flow through a coil is canceled by using opposing excitations and controlled. However, not all of the five phases of the five-phase stepping motor are excited, but one phase is in a high impedance state and the remaining four phases are excited. Vibration may occur.
[0014]
[Patent Document 1]
Japanese Patent No. 3182325 (claims, paragraphs 0002 to 0007, 0012 to 0019, FIGS. 1 and 2)
[Patent Document 2]
JP-A-10-94291 (abstract, paragraphs 0014 to 0025, FIGS. 1 to 12, table 1)
[Patent Document 3]
Japanese Patent No. 3162862 (paragraphs 0012, 0033 to 0037, FIGS. 11 to 13)
[0015]
[Problems to be solved by the invention]
The present invention eliminates the above-described problems, and provides a novel micro-step driving method using a conventionally used circuit, in which at least at the time of driving the stepping motor, all N phases are always in an excited state. Another object of the present invention is to provide a stepping motor driven by the novel micro-step driving method.
[0016]
[Means for Solving the Problems]
The object of the present invention is achieved by the inventions described in claims 1 to 8 of the present application.
That is, the invention according to claim 1 includes a constant current control circuit and an excitation pattern generation circuit, and in a microstepping method of an N-phase stepping motor radially connected, at least when the stepping motor is driven, all N phases are always in an excited state. As the basic excitation pattern for generating a combined torque vector corresponding to each basic step, an excitation pattern based on at least one or more combinations is set in the excitation pattern generation circuit, and an intermediate of the basic steps is performed in one excitation sequence. An intermediate excitation pattern for generating a combined torque vector corresponding to a step is set in the excitation pattern generation circuit as an excitation pattern obtained by changing the output ratio of each of the basic excitation patterns in the basic steps before and after the intermediate step. , One excitation sequence The output ratio of each excitation pattern output from the excitation pattern generation circuit during the step is gradually increased and decreased for each step, and the basic excitation pattern in the next basic step is changed from the basic excitation pattern in the previous basic step. Wherein the combined torque vector in one excitation sequence is driven in multiple divisions between basic steps for each step.
[0017]
According to the present invention, at least at the time of driving the stepping motor, all the N phases are always in the excitation state, so that none of the phases is in the high impedance state. For this reason, the voltage applied to both ends of each coil winding as a phase can always be controlled. A sudden change in voltage caused by the high impedance state does not occur, and vibration during rotation of the stepping motor can be suppressed.
[0018]
In addition, since the constant current control circuit detects the total current and can perform control to keep the total current constant, the current flowing in each phase is individually detected, and the current control of each phase is individually performed. Eliminates the need. Therefore, microstep driving can be performed with an inexpensive basic circuit configuration for the basic step.
[0019]
Moreover, the intermediate excitation pattern is set by the combined excitation pattern by changing the output ratio of each of the front and rear basic excitation patterns, and the output ratio of each combined excitation pattern is gradually increased and decreased for each step, and Since the basic excitation pattern at the stage is continuously changed from the basic excitation pattern at the later stage, the function of performing the micro-step driving can be integrated in the logic unit in the excitation pattern generation circuit.
For this reason, microstep driving can be realized only by changing the logic unit without using a special driving circuit and using a conventional full-step driving circuit.
[0020]
Further, as a driving type of the stepping motor, a motor driving voltage control type and an output stage chopper type are generally used, but the micro step method of the present invention can be applied to the stepping motor driven by both types. .
In particular, when the micro step method of the present invention is applied to a motor drive voltage control type stepping motor, the resolution of the micro step can be made high, and when it is applied to an output stage chopper type stepping motor, the micro step can be performed at low cost. A step driving circuit can be configured.
[0021]
The invention according to claim 2 provides, in addition to the features described in claim 1, an output cycle of each excitation pattern output from the excitation pattern generation circuit and a PWM cycle output from the constant current control circuit. The excitation time of each excitation pattern output from the excitation pattern generation circuit in the step is made uniform, and the output ratio of each excitation pattern output from the excitation pattern generation circuit is gradually increased and decreased in each step. The present invention is directed to a microstep method in which the number of times of generation of an output cycle of each excitation pattern output from an excitation pattern generation circuit is gradually increased and decreased.
[0022]
According to the present invention, the output period of each excitation pattern output from the excitation pattern generation circuit is synchronized with the PWM period of the constant current control to make the excitation time of each excitation pattern uniform, By gradually increasing and decreasing the number of times that the output cycle of each excitation pattern is generated, the output ratio of each excitation pattern output from the excitation pattern generation circuit is gradually increased and decreased for each step.
[0023]
That is, since the switching between the PWM cycle and the output of each excitation pattern is synchronized, the output of each excitation pattern output from the excitation pattern generation circuit and the output of the constant current control can be in a one-to-one relationship.
[0024]
In addition, by gradually increasing and decreasing the number of times of generation of the output cycle of each excitation pattern output from the excitation pattern generation circuit, it becomes possible to perform multi-step microsteps. Since the output time of each excitation pattern is constant, the combined torque vector can be operated at the ratio of the combination of the excitation patterns.
[0025]
In addition, the logic circuit for controlling the micro-step is simplified, and the logic section in the excitation pattern generation circuit is changed while using the conventional full-step drive circuit, and the PWM cycle of the constant current control circuit and the excitation of the excitation pattern generation circuit are changed. The microstep can be performed by synchronizing the output cycle of the pattern. According to the present invention, an existing drive circuit can be effectively used, and microsteps can be performed at low cost.
[0026]
In particular, when the present invention is applied to a stepping motor driven by an output stage chopper type, the excitation pattern generation circuit receives the output of the constant current control circuit, and controls the ON / OFF of the current by the switching means in the output stage, thereby achieving stepping. The total current flowing through the motor can be controlled to be constant.
[0027]
Since the current flowing through the stepping motor is smoothed by the inductance of the coil winding in each phase, the current increases when the ratio of the time during which the current in the switching means is ON during the PWM cycle increases, and the current increases. The current can be reduced if the ratio of the time during which the current in the switching means is ON is reduced. Thus, both the constant current control and the excitation pattern output can be performed by the output stage.
[0028]
According to a third aspect of the present invention, in addition to the second aspect, while the signal for turning on the output of the excitation pattern from the constant current control circuit is input to the excitation pattern generation circuit, the excitation pattern is generated. While the signal for exciting each phase according to the basic excitation pattern or the intermediate excitation pattern output from the generation circuit and turning off the output of the excitation pattern from the identification current control circuit output is input to the excitation pattern generation circuit, the coil A microstep method in which all of the winding ends are connected to the same pole of the power supply voltage so that all ends of the coil winding are set to the same potential and the motor is de-energized.
[0029]
According to the present invention, when a command to turn off the excitation pattern output from the constant current control circuit is input to the excitation pattern generation circuit, the excitation pattern generation circuit turns on or off all the switching means on the upper side of the output stage, and By turning all the lower switching means of the output stage OFF or ON in reverse to the upper switching means, the terminal ends of the coil windings of each phase are set to the same potential, and each phase is in a non-excited state.
[0030]
Thus, when the output of the constant current control circuit outputs a command to turn off the output of the excitation pattern to the excitation pattern generation circuit, the potential of each phase can be stabilized by setting the same potential. In addition, even when switching to the next step, a rapid change in potential at the connection point of each phase does not occur. Even if an overshoot of the current occurs, its magnitude can be made very small, and the convergence can be made easy. For this reason, it is possible to flow a smooth phase current, and it is possible to reduce damping and suppress vibration at low speed.
[0031]
According to a fourth aspect of the present invention, in addition to the second aspect, the constant current control circuit detects a change in a total current due to a change in impedance of each phase of the stepping motor, and the total current is constant. Thus, there is a microstep method in which the control of the time during which the current of the switching means is turned on for the excitation pattern generating circuit is limited.
[0032]
According to the present invention, the current flowing in the stepping motor is smoothed by the inductance of the coil winding. Therefore, if the ratio of the current ON in the switching means in the output stage during the PWM cycle increases, the current increases and the current turns ON. The current can be reduced if the ratio of the time is reduced. By controlling the length of the current ON / OFF time in the switching means in the output stage, the total current flowing in each phase can be controlled to be constant.
[0033]
According to a fifth aspect of the present invention, in addition to the features of the first aspect, the output periods of the basic excitation pattern and the intermediate excitation pattern output from the excitation pattern generation circuit are made constant, and the excitation pattern generation circuit The microstep method is limited to gradually increasing and decreasing the output ratio of each excitation pattern to be output by changing the ratio of the excitation time of each excitation pattern output from the excitation pattern generation circuit.
[0034]
According to the present invention, the output ratio of each excitation pattern output from the excitation pattern generation circuit is gradually increased and decreased for each step while the output periods of the basic excitation pattern and the intermediate excitation pattern output from the excitation pattern generation circuit are kept constant. However, this is performed by changing the ratio of the excitation time of each excitation pattern output from the excitation pattern generation circuit.
[0035]
Therefore, the excitation time of each excitation pattern can be shortened to a time on the order of nanometers or less, and the resolution of microsteps can be increased as needed. In particular, when the present invention is applied to a stepping motor driven by a motor drive voltage control type, the total current can be detected and controlled by the constant current control without detecting the current of each phase. Can also be simplified.
[0036]
In the invention according to claim 6, in addition to the features described in claim 5, the constant current control circuit detects a change in total current due to a change in impedance of each phase of the stepping motor, and the total current becomes constant. As described above, a micro step in which the time for turning on the current of the power supply switching means for connecting and disconnecting the power supply voltage to the motor drive voltage provided in parallel with the power supply voltage between the power supply voltage and the output stage is limited. In the way.
[0037]
According to the present invention, the motor drive voltage can be made constant by controlling the current ON / OFF time of the power supply switching means provided between the power supply voltage and the motor drive voltage, and the total current supplied to each phase can be made constant. Can be controlled so that
[0038]
The invention according to claims 7 and 8 is characterized in that the stepping motor driven by the microstep method according to claims 1 to 6 is used as a positioning motor or an ultra-low speed constant speed motor. It is in.
[0039]
The stepping motor to which the micro-step method according to the present invention is applied can improve the division accuracy, and does not generate a high impedance state, and can suppress vibration at low speed rotation. It can be used as a high speed motor. The stepping motor of the present invention is applicable to various FA machines such as facsimile machines, copiers, printers, magnetic disk drives, OA machines, NC machine tools, robots, semiconductor manufacturing machines, stationery machines, food machines, and packaging machines. It can be used as a high-precision positioning motor for a computer-controlled mechanism such as a machine.
[0040]
Furthermore, since the stepping motor of the present invention can further enhance the positioning accuracy and suppress vibration at low rotation speed, the stepping motor of the positioning device such as the optical fiber field, the nanotechnology field, the electron microscope or the like can be used. It can be used as a drive motor for a low-speed constant-speed drive member.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings.
In the first embodiment, an output stage chopper type radial connection three-phase stepping motor will be described. As a second embodiment, a motor drive voltage control type radial connection three-phase stepping motor will be described. As a third embodiment, a radial connection will be described. 5 stepping motor. The present invention is not limited to these embodiments, but is applicable to an N-phase stepping motor having three or more N-phases in radial connection.
[0042]
FIG. 3 is a configuration diagram of a microstep circuit of an output stage chopper type in the first embodiment of the present invention, and FIG. 4 shows a state of an excitation output when outputting an excitation pattern vUw and an excitation pattern UwV. I have. FIG. 5 shows the relationship between the PWM circuit and the excitation output. FIG. 6 is a diagram showing an excitation pattern generation ratio and a combined torque vector at the time of full step and half step when the basic step is divided into 10 from the start position to the next basic step. 3 shows an excitation pattern in a full step and a half step state in the three-phase stepping motor of FIG.
[0043]
FIGS. 3, 8, and 12 show examples in which a transistor is used as the switching means. However, the switching means is not limited to a transistor, and a field effect transistor (FET) or the like can be used. Things.
[0044]
As shown in FIG. 3, the starting points of the W-phase coil winding 5, the U-phase coil winding 6, and the VW-phase coil winding 7 are connected at one point and are radially connected. The terminal end of the W-phase coil winding 5 is connected to the positive (+ Vc) side of the power supply voltage 17 via a transistor T1 and connected to the ground potential (GND) side via a transistor T4. A phase current is supplied to the W-phase coil winding 5 by turning on / off these transistors T1 and T4.
[0045]
Similarly, the terminal of the U-phase coil winding 6 is connected to the positive (+ Vc) side of the power supply voltage 17 via the transistor T2 and connected to the ground potential (GND) side via the transistor T5. Further, the terminal of the V-phase coil winding 7 is connected to the positive electrode (+ Vc) side of the power supply voltage 17 via a transistor T3, and is connected to the ground potential (GND) side via a transistor T6.
[0046]
That is, by turning on / off each of the transistors T1 to T6 in the output stage 4, the terminals of the coil windings 5 to 7 of each phase are connected to the positive or negative electrode of the power supply voltage 17, that is, the ground potential. A voltage can be applied to 5 to 7 to flow an exciting current.
[0047]
A wire connecting the terminal of the coil windings 5 to 7 of each phase and the middle point of the pair of transistors (T1, T4), (T2, T5), (T3, T6), the positive (+ Vc) side of the power supply voltage 17, and ground Diodes D1 to D6 are respectively installed between the potential (GND) side and these diodes, but these diodes are not necessarily required to be installed, and can be appropriately installed as necessary. .
[0048]
The excitation pattern generation circuit 1 has a built-in excitation pattern, selects excitation pattern data to be output from step position information by a command pulse and output order information of the excitation pattern, and outputs it as a gate signal in the output stage 4. The ON / OFF control of the corresponding transistor is performed. In addition, an output process at the time of non-excitation is also performed by an OFF command from the constant current control circuit 2, that is, a command not to output the excitation pattern.
[0049]
As the output processing at the time of non-excitation, the excitation pattern generation circuit 1 turns off all the transistors T1 to T3 in the output stage 4 and turns on all the transistors T4 to T6 in the output stage 4; Are turned on and all the transistors T4 to T6 in the output stage 4 are turned off, so that the ends of the coil windings 5 to 7 of the respective phases U to W of the stepping motor are set to the same potential, and each phase is set to the non-excited state. Is performed.
[0050]
Thus, the potential of each phase U to W can be stabilized by the OFF command from the constant current control circuit 2. Even when switching to the next step, abrupt potential change does not occur at the connection point of each phase U to W, and even if an overshoot of current occurs, it can be made very small, and it is easy to converge. Can be. For this reason, it becomes possible to flow a smooth phase current, and it is possible to reduce the damping and suppress the vibration at low speed.
[0051]
That is, the constant current control circuit 2 amplifies the error between the voltage detected by the sensing resistor 3 of the total current and the reference voltage, and the amplified comparison voltage and the inside of the constant current control circuit 2 as shown in FIGS. By comparing with the generated ramp wave, the time for turning on each of the transistors T1 to T6 in the output stage 4, that is, the ON width can be controlled by the PWM control.
[0052]
The constant current control circuit 2 amplifies the error between the voltage detected by the total current sensing resistor 3 and the reference voltage, for example, when the rotational speed of the stepping motor increases and the impedance of each phase U to W increases. The comparison voltage is obtained, and as shown in FIG. 5, from the intersection of the height of the comparison voltage and the ramp wave, the time during which the current in the switching means of the output stage 4 is ON, that is, the control for expanding the ON width is controlled by the excitation pattern generation circuit 1. , The current flowing through the phase can be kept constant. Conversely, when the rotational speed of the stepping motor decreases and the impedance of each phase U to W decreases, the excitation pattern generation circuit 1 performs control to narrow the ON width, so that the current flowing through the phase can be kept constant. it can.
[0053]
In the output stage chopper type shown in the first embodiment, the output of the constant current control circuit 2 is received by the excitation pattern generation circuit 1, and the ON / OFF control of the transistors T1 to T6 in the output stage 4 is performed, whereby the stepping motor is controlled. , The total current supplied to the coil windings 5 to 7 of each phase U to W can be controlled to be constant.
[0054]
When the constant current control circuit 2 outputs an ON command, the excitation pattern generation circuit 1 performs ON / OFF control on the transistors T1 to T6 of the output stage 4 in accordance with the excitation pattern stored in the excitation pattern generation circuit 1. Output a signal. As a result, an exciting current can be supplied to each of the phases U to W of the stepping motor, and the direction of the resultant torque vector can be moved to drive the stepping motor.
[0055]
Next, as an example of micro-step driving, a case in which a basic step (full step) is divided into 10 parts will be described. The radially connected three-phase stepping motor forms a torque vector for every 60 electrical degrees as shown in FIGS.
[0056]
As shown in FIG. 7, the excitation pattern in each basic step is set by two sets of excitation patterns that output evenly, and the excitation pattern in the intermediate stage between the basic steps is changed in the output ratio of the excitation pattern in the preceding and succeeding basic steps. Can be set.
[0057]
For example, as shown in FIG. 7, regarding the excitation pattern in the half step, the excitation pattern before and after the half step can be added, and the half of the excitation pattern can be used as the excitation pattern.
In other words, considering a state in which N / 2 vUw and UwV are alternately output as excitation patterns in a basic step which is a start position, UwV and wVu are set to N / 2 in the next basic step as excitation patterns. A state in which the output is performed alternately for each is set. The excitation pattern in the half step between these two basic steps is obtained by adding Vww and UwV, which are output alternately by N / 2, to UwV and wVu, which are also output alternately by N / 2, and halving each. (N / 2) / 2 vUw, N / 2 UwV, and (N / 2) / 2 wVu are set by a combination of three excitation patterns that are alternately output at the ratio of the respective output numbers. Can be.
[0058]
Note that the excitation pattern in the basic step is not limited to that shown in FIG. 7, and can be set by another excitation pattern.
[0059]
Assuming that the resultant torque vector at the start position is Uw, the electrical angle 60 degrees up to the resultant torque vector wV in the next basic step is divided into ten, and the torque vector is output with twenty excitation pattern outputs that are twice the number of divisions (10). Looking at the case of combining, the excitation pattern in the full step of the basic step and the excitation pattern in the half step at this time can be the excitation pattern shown in FIG. 7 as described above.
[0060]
FIG. 6 shows the state of the excitation output when the excitation pattern vUw and the excitation pattern UwV are output, and the output stage 4 performs the “vUw excitation and the "Excitation" and "UwV excitation and non-excitation" are repeated. As a result, the resultant torque vector due to the excitation is such that V and v cancel each other at the same ratio, and are in the direction of Uw.
[0061]
The excitation pattern generation circuit 1 changes the output ratio of the 20 excitation patterns each time the sequence advances according to the command pulse. When a command pulse is first input from the start position to the excitation pattern generation circuit 1, the excitation sequence advances by "+1". At this time, the excitation pattern generation circuit 1 sets the output ratio of the 20 excitation patterns to “vUw: UwV: wVu = 9: 10: 1”.
[0062]
Next, when a command pulse is input to the excitation pattern generation circuit 1, the output ratio of the 20 excitation patterns is set to “vUw: UwV: wVu = 8: 10: 2”.
[0063]
Thus, the excitation pattern vUw decreases by one and the excitation pattern wVu increases by one at each step while the excitation pattern UwV remains constant at each step. That is, the output ratio of the excitation pattern can be gradually reduced and increased for each step.
[0064]
In the intermediate half step (+ 5th step), the excitation pattern generation ratio is “vUw: UwV: wVu = 5: 10: 5”, and the resultant torque vector is in the direction of w. Further, as can be seen from FIG. 6, a torque vector can be synthesized with 20 excitation patterns at any step position.
[0065]
In this manner, the excitation pattern generation circuit 1 can switch the 20 excitation patterns in synchronization with the PWM cycle of the constant current control circuit 2 at each step in which the sequence proceeds by the command pulse.
[0066]
The twenty excitation patterns can be output in a predetermined order in the excitation pattern generation circuit 1. Unless a command pulse is input, the step is not performed, and the excitation pattern at that position is repeatedly output in order.
[0067]
Assuming that the PWM cycle is 10 μs, the resultant torque vector based on the excitation pattern can be controlled at a cycle of 200 μs (10 μs × 20 patterns).
[0068]
The case where the number of divisions between the basic steps is 10 and the torque vector is synthesized with the output of 20 excitation patterns and the PWM cycle is 10 μs has been described. The present invention is not limited to this, and can set an arbitrary number of divisions, the number of outputs of the excitation pattern, and the PWM cycle.
[0069]
Next, a description will be given of a micro step method of a motor drive voltage control type according to a second embodiment of the present invention. FIG. 8 shows a microstep circuit configuration diagram in the second embodiment, and FIG. 9 shows a case where the output period of the excitation pattern is fixed, and the output time of each excitation pattern vUw, UwV and wVu and its output for each step. The percentage is shown. FIG. 10 shows the relationship between the excitation pattern output cycle and the excitation pattern output time, and FIG. 11 shows the excitation patterns in the full step and half step states.
[0070]
The motor drive voltage control type micro-step circuit configuration diagram in the second embodiment basically has the same circuit configuration as the output stage chopper type micro-step circuit configuration diagram in the first embodiment. Since the configuration has the same function, the description of the members will be omitted by using the same reference numerals as those used in the first embodiment.
[0071]
The excitation pattern described in the second embodiment uses the same excitation pattern as the excitation pattern in the first embodiment, but the excitation pattern that can be used in the second embodiment is limited to the excitation pattern described below. Instead, any other excitation pattern that can achieve the present invention can be used.
[0072]
Although the diodes D1 to D6 are provided in the output stage 4, these diodes D1 to D6 are not necessarily required to be set, and can be appropriately set as needed.
[0073]
As shown in FIG. 8, in the motor drive voltage control type, the power supply voltage 17 is not directly applied from the output stage 4 to the coil windings 5 to 7 of each phase U to W of the stepping motor as in the output stage chopper type. After the power supply voltage 17 is once converted to the motor drive voltage 18, the power supply voltage 17 is applied to the coil windings 5 to 7 of each phase U to W of the stepping motor.
[0074]
A motor drive voltage 18 and a diode 10 are respectively arranged in parallel between the power supply voltage 17 and the output stage 4, and a power supply switching means 8 and a coil 9 are arranged in series between the power supply voltage 17 and the motor drive voltage 18. I have. Although a transistor using a transistor as the power supply switching means 8 is shown, the power supply switching means 8 is not limited to a transistor, and a field effect transistor (FET) or the like can be used.
[0075]
The constant current control circuit 2 compares the voltage detected by the total current sensing resistor 3 with a reference voltage, detects a change in impedance in the coil winding of the stepping motor, and controls ON / OFF of the power supply switching means 8. Is performed to control the motor driving voltage 18 so that the total current supplied to the stepping motor from the motor driving voltage 18 is controlled to be constant.
[0076]
The comparison voltage obtained by amplifying the error between the voltage detected by the total current sensing resistor 3 and the reference voltage is compared with the ramp wave generated inside the constant current control circuit 2 to determine the stepping motor voltage as shown in FIG. When it is detected that the impedance in the coil windings 5 to 7 is high, the time during which the current is turned on by the power supply switching means 8, that is, the ON width is increased, and the motor drive voltage 18 is increased. When it is detected that the impedance is low, the ON width of the power supply switching means 8 is reduced to lower the motor drive voltage 18.
By controlling the power supply switching means 8, the total current flowing in each phase of the stepping motor can be controlled to be constant.
[0077]
The excitation pattern generation circuit 1 only outputs the excitation pattern to the output stage 4 as a gate signal, and does not perform excitation / non-excitation as in the case of the output stage chopper type, and always keeps the stepping motor in the excitation state. Can be. Since the total current is controlled by the constant current control circuit 2, there is no need to perform excitation / non-excitation switching between the excitation pattern generation circuit 1 and the output stage 4.
[0078]
Further, in the output stage chopper type, the PWM cycle is synchronized with the cycle of the basic excitation pattern or the intermediate excitation pattern output from the excitation pattern generation circuit 1, so that the number of excitation patterns that can be divided between the basic steps is Naturally, there are restrictions. On the other hand, in the motor drive voltage control type, since the excitation pattern can be output from the excitation pattern generation circuit 1 independently of the constant current control circuit 2, the number of excitation patterns that can be divided between the basic steps is It can be set freely, and it is possible to perform much more divisions as microsteps as compared with the output stage chopper.
[0079]
Next, a multi-division method in the second embodiment for performing the micro-step driving will be described.
As shown in FIG. 11, in the excitation in the basic step, a combined torque vector based on the excitation pattern is created by combining two types of three-phase excitation patterns as in the first embodiment.
[0080]
In the excitation other than the basic steps, a combined torque vector based on the excitation pattern is created by combining three types of three-phase excitation patterns. At this time, the output cycle of the basic excitation pattern and the intermediate excitation pattern is fixed, and the ratio of the output time of each excitation pattern within the same constant output cycle is changed, so that the combined torque vector at each step in the sequence is obtained. To operate.
[0081]
FIG. 9 shows the output time and output period of each individual excitation pattern in each step when the output period of the basic excitation pattern and the intermediate excitation pattern is 100 μs, and the period from the start position (full step) to the next full step is divided into 100. The ratio with respect to 100 μs is shown.
[0082]
Each time a command pulse is input to the excitation pattern generation circuit 1, the stepped individual excitation pattern vUw is reduced by 0.5 μs and the excitation pattern wVu is increased by 0.5 μs. This operation can be configured by a logic circuit in all the excitation pattern generation circuits 1.
[0083]
Note that the output period and the basic step from 100 μs to the next basic step are divided into 100, and the output time to be increased or decreased for each step is set to 0.5 μs. However, the present invention is not limited to the above numerical value, but can be performed with an arbitrary value and unit such as an output cycle and an output time in the order of nanoseconds (ns).
[0084]
FIG. 10 shows the output period of the basic excitation pattern and the intermediate excitation pattern and the ratio of the output time of each individual excitation pattern. At this time, the output periods of the basic excitation pattern and the intermediate excitation pattern are always constant.
[0085]
Each time a command pulse is input to the excitation pattern generation circuit 1, the output time of the excitation pattern vUw is gradually reduced by 0.5 μs, and the output time of the excitation pattern wVu is gradually increased by 0.5 μs. The output time is fixed.
[0086]
As a result, by changing the ratio of the individual excitation pattern output time, the resultant torque vector is changed, and thereby the stepping motor can be advanced. That is, the composite vector is Uw in the basic step at the start, but becomes w in the half step, and can be wV in the next basic step.
[0087]
Unless a command pulse is input to the excitation pattern generation circuit 1, the output time ratio of each excitation pattern at that position does not change, and the output is repeated. , And the output of the individual excitation pattern is repeated at the new output time.
[0088]
As shown in FIG. 11, the state of the excitation pattern in the basic step and the half step in the second embodiment, the output time of PT2 is constant between the basic steps, and the output time of PT1 is 0.5 μs per step. , And PT3 increases by 0.5 μs for each step.
In the next basic step, the output time of the excitation pattern of PT1 becomes zero in the previous stage, and the excitation pattern which was PT2 in the previous stage becomes a new PT1 instead. PT2 is replaced by the one that was PT3 in the previous stage, and PT3 is replaced by PT2 that becomes PT2 in the next basic step.
[0089]
In the second embodiment, the total current is detected by the constant current control circuit 2 without detecting the current of each phase, and the motor driving voltage is controlled by controlling the switching means 8 for the power supply. The current can be controlled to be constant. Also, in the excitation in the basic step, a combined torque vector can be created from two individual excitation patterns by combining two types of three-phase excitation patterns.
[0090]
Further, in the excitation in steps other than the basic steps, a combined torque vector can be created by individual excitation patterns by combining three types of three-phase excitation patterns. Moreover, two types of individual excitation patterns can be created by changing the combination ratio of the excitation patterns in the preceding and following basic steps.
[0091]
In addition, the output periods of the basic excitation pattern and the intermediate excitation pattern are kept constant, and the ratio of the output time of the individual excitation patterns to be output within the period is changed for each step. The resultant torque vector can be manipulated and microsteps can be performed that divide the basic step into multiples.
[0092]
Next, a description will be given of a radially-connected 5-phase stepping motor according to a third embodiment. The third embodiment can also be applied to a stepping motor driven by an output stage chopper type and a motor drive voltage control type. FIG. 12 shows the relationship between the output stage and the connection diagram as a part of the microstep circuit configuration of the five-phase stepping motor of the output stage chopper type and the motor drive voltage control type.
[0093]
In the output stage 4 of FIGS. 3 and 8 showing the output stage chopper type and the motor drive voltage control type in three phases, respectively, three pairs of transistors are arranged in parallel. As shown in FIG. 4, two pairs of transistors are further arranged, and the midpoint of each pair of transistors is separately connected to the ends of the five-phase A to E coil windings. The other configuration is the same as the configuration shown in FIG. 3 for the output stage chopper type and the configuration shown in FIG. 8 for the motor drive voltage control type, and the description of each member will be omitted.
[0094]
Although an example in which a transistor is used as the switching means in the output stage 4 is shown, the switching means is not limited to a transistor, and a field effect transistor (FET) or the like can be used. Further, although the diodes D1 to D10 are provided in the output stage 4, these diodes D1 to D10 are not necessarily required to be set, and can be appropriately set as needed.
[0095]
FIG. 13 shows an excitation pattern in the output stage chopper type as an excitation pattern in three phases, and FIG. 14 shows an excitation pattern in the basic step and half step as an excitation pattern in the motor drive voltage control type. On the other hand, in the case of five phases, unlike the case of three phases, the excitation pattern in the basic step can be performed by one type, and the excitation patterns in the middle are two types of excitation patterns which are the basic excitation patterns before and after. Can be obtained by changing the output ratio.
[0096]
The method of changing the output ratio of the basic excitation pattern before and after is similar to that performed in the output stage chopper type and the motor drive voltage control type in the case of three phases, and the basic excitation pattern in the basic step and the basic excitation pattern in the next basic step. By gradually decreasing and gradually increasing the output ratio of each step, the excitation pattern of the basic step can be continuously changed to the excitation pattern of the next basic step.
[0097]
Further, as in the case of the three-phase, the output stage chopper type also synchronizes the PWM cycle from the constant current control circuit 2 with the output of the excitation pattern output from the excitation pattern generation circuit 1 in each of the five phases. The microstep drive can be performed by gradually decreasing and gradually increasing the number of times to output the output cycle of each excitation pattern.In the motor drive voltage control type, the time of the output cycle of the individual excitation pattern for each step can be set. The micro-step drive can be performed by gradually decreasing and gradually increasing the ratio.
Therefore, a specific description of the case of five phases is omitted.
[0098]
Also in the case of the five phases, when driving the stepping motor, all five phases can be excited, and the stepping motor can be driven without causing a high impedance state. In addition, in the case of the output stage chopper type, the excitation pattern can be controlled in the same manner as in the output stage chopper type in the case of three phases, and the coil winding of all five phases can be performed in the non-excited state as in the case of the three phases The ends of the lines are at the same pole.
[0099]
In the case of the motor drive voltage control type, the excitation pattern can be controlled in the same manner as in the case of the three-phase motor drive voltage control type.
[0100]
Although the three-phase and five-phase radially connected stepping motors have been described above, the present invention is not limited to the three-phase and five-phase stepping motors. Applicable. Moreover, the stepping motor to which the micro-step method according to the present invention is applied can improve the division accuracy, does not cause a high impedance state, and can suppress the vibration at low speed rotation. It can be used as a constant speed motor.
[0101]
The stepping motor of the present invention is applicable to various FA machines such as facsimile machines, copiers, printers, magnetic disk drives, OA machines, NC machine tools, robots, semiconductor manufacturing machines, stationery machines, food machines, and packaging machines. It can be used as a high-precision positioning motor for a computer-controlled mechanism such as a machine.
[0102]
Further, the stepping motor of the present invention can further improve the positioning accuracy and suppress vibration at low rotation speed, so that the motor for positioning devices such as optical fiber field, nanotechnology field, electron microscope, etc. It can be used as a constant speed motor.
[Brief description of the drawings]
FIG. 1 is a motor connection diagram of a radially connected three-phase stepping motor.
FIG. 2 is a torque vector diagram of a three-phase stepping motor.
FIG. 3 is a configuration diagram of a micro-step circuit of an output stage chopper type of a three-phase stepping motor.
FIG. 4 is a diagram showing an excitation output state in an output stage chopper type.
FIG. 5 is a diagram showing a relationship between a PWM circuit and an excitation output in an output stage chopper type.
FIG. 6 is a diagram showing combined vectors in a basic step and a half step in the output stage chopper type.
FIG. 7 is a diagram showing an excitation pattern in the output stage chopper type.
FIG. 8 is a block diagram of a micro step circuit in a motor drive voltage control type.
FIG. 9 is a diagram showing an output ratio of an excitation pattern in a motor drive voltage control type.
FIG. 10 is a diagram showing a relationship between an excitation pattern output cycle and an output time in a motor drive voltage control type.
FIG. 11 is a diagram showing an excitation pattern in a motor drive voltage control type.
FIG. 12 is a diagram illustrating an output stage of a five-phase stepping motor.
FIG. 13 is a diagram showing an excitation pattern in a 5-phase output stage chopper type.
FIG. 14 is a diagram showing an excitation pattern in a five-phase motor drive voltage control type.
FIG. 15 is a configuration diagram of a micro-step circuit in a conventional example.
FIG. 16 is a diagram showing duty control in an output stage in a conventional example.
[Explanation of symbols]
1 Excitation pattern generation circuit
2 Constant current control circuit
3 Sensing resistance
4 Output stage
5-7 coil winding
8 Switching means for power supply
9 coils
10 Diode
11-15 coil winding
17 Power supply voltage
18 Motor drive voltage
21 to 25 phase coil
+ Vc Positive potential of power supply voltage
+ Vm Positive potential of motor drive voltage
GND Ground potential
T1 to T10 Switching means
D1 to D10 Diode
A to E, a to e Torque vectors
U ~ W, u ~ w Torque vector
TAP to TEP transistor
TAN-TEN transistor

Claims (8)

A constant current control circuit and an excitation pattern generation circuit are provided. Each coil winding of the N-phase stepping motor is connected radially by connecting its starting end at a single point, and each of these phases is individually connected to an end as an output stage. In a micro-step method of a stepping motor that connects a switching means and connects a positive or negative power supply voltage to the switching means to excite each phase,
At least at the time of driving the stepping motor, all N phases are always in an excited state,
As a basic excitation pattern for generating a combined torque vector corresponding to each basic step, an excitation pattern by at least one or more combinations is set in the excitation pattern generation circuit,
An intermediate excitation pattern for generating a combined torque vector corresponding to an intermediate stage of the basic steps during one excitation sequence was combined by changing the output ratio of each of the basic excitation patterns in the basic steps before and after the intermediate stage. Set as the excitation pattern in the excitation pattern generation circuit,
The output ratio of each excitation pattern output from the excitation pattern generation circuit in one excitation sequence is gradually increased and decreased step by step, and the basic excitation pattern in the previous basic step is changed from the basic excitation pattern in the previous basic step to the next basic step. Continuously change to the basic excitation pattern,
A micro-stepping method for a stepping motor, characterized in that the combined torque vector in one excitation sequence is driven in multiple divisions between basic steps for each step. The output period of each excitation pattern output from the excitation pattern generation circuit is synchronized with the PWM period output from the constant current control circuit, and the excitation time of each excitation pattern output from the excitation pattern generation circuit in each step The uniform and none
The output ratio of each excitation pattern output from the excitation pattern generation circuit is gradually increased and decreased for each step, and the number of times of generation of the output cycle of each excitation pattern output from the excitation pattern generation circuit is gradually increased and decreased in each step. 2. The microstep method according to claim 1, wherein the method is performed. While the signal for turning on the output of the excitation pattern from the constant current control circuit is input to the excitation pattern generation circuit, each phase is excited according to the basic excitation pattern or the intermediate excitation pattern output from the excitation pattern generation circuit. ,
While a signal for turning off the output of the excitation pattern from the output of the identification current control circuit is being input to the excitation pattern generation circuit, any one of the coil winding ends is connected to the same pole of the power supply voltage, so that the same 3. The micro-step method according to claim 2, wherein all ends of the coil winding are set to the same potential to de-energize the motor. The constant current control circuit detects a change in total current due to a change in impedance of each phase of the stepping motor,
4. The micro-step method according to claim 2, wherein a time during which the switching means is turned on with respect to the excitation pattern generating circuit is controlled so that the total current is constant. Making the output cycle of the basic excitation pattern and the intermediate excitation pattern output from the excitation pattern generation circuit constant,
The output ratio of each excitation pattern output from the excitation pattern generation circuit is gradually increased and decreased at each step by changing the ratio of the excitation time of each excitation pattern output from the excitation pattern generation circuit. The microstep method according to claim 1, wherein The constant current control circuit detects a change in total current due to a change in impedance of each phase of the stepping motor,
Time for turning on the current of the power supply switching means for connecting and disconnecting the power supply voltage to and from the motor drive voltage provided between the power supply voltage and the output stage in parallel with the power supply voltage so that the total current is constant. 6. The microstep method according to claim 5, wherein is controlled. 7. A stepping motor, wherein a stepping motor driven by the microstep method according to claim 1 is used as a positioning motor. 7. A stepping motor, wherein the stepping motor driven by the micro step method according to claim 1 is used as a motor for an ultra-low speed constant speed.

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