Control systems for stepper drives

Abstract

The present invention relates to a control system for a stepping drive device. According to one embodiment, a control system for a stepping drive device is provided, the stepping drive device includes a piezoelectric ceramic module for driving, and the control system includes: a charging circuit connected to the piezoelectric ceramic module through a first switch to charge it; a discharging circuit connected to the piezoelectric ceramic module through a second switch to discharge it; and a switch control unit connected to the first and second switches, configured to control the conduction and cutoff of the first and second switches to switch between charging and discharging. The control system of the present invention can improve the driving efficiency of the piezoelectric ceramic module and realize fast and stable driving control, so it can be applied to various types of stepping drive devices including piezoelectric ceramic modules.

Description

Technical Field

[0001] The present invention generally relates to the field of drive devices, and more particularly, to a control system for a stepping drive device, which can charge and discharge a piezoelectric ceramic module in the stepping drive device through two separate channels, thereby greatly improving the drive efficiency. Background Art

[0002] Common stepping drive devices include stepping motors, piezoelectric ceramic drive devices, etc. Among them, piezoelectric ceramic drive devices use the deformation of piezoelectric ceramics to achieve drive, and have the characteristics of small step size and high precision. Therefore, they are often used in applications that require precise stepping drive, and can be used in special environments such as low temperature, magnetic field or vacuum.

[0003] Chinese utility model patent application 201721879297.9, entitled “Stepping drive device and strain applying device including the same”, filed on December 28, 2017 by the same applicant, discloses a stepping drive device including a piezoelectric ceramic module, which can realize continuous driving of a specific step length in the positive and negative directions, and has the advantages of high precision and large driving distance. In such a system, the piezoelectric ceramic module needs to be continuously charged and discharged to achieve continuous movement. The charging process can be carried out slowly so that the piezoelectric ceramic module deforms slowly and drives the mover to move together; the discharging process needs to be carried out quickly so that the piezoelectric ceramic module quickly returns to its original shape or even deforms in the opposite direction, and the mover basically does not withdraw. In this way, continuous movement in one direction can be achieved.

[0004] In conventional control circuits, the piezoelectric ceramic module is charged and discharged using the same power supply and circuit path. When performing a rapid discharge operation, the circuit needs to withstand a large discharge current, but due to the influence of the maximum carrying current of the circuit, it is difficult to perform the discharge operation at the desired speed, resulting in low discharge efficiency. This problem becomes more serious when the capacitance of the piezoelectric ceramic module is large, and the driving efficiency is greatly reduced.

[0005] Therefore, there is still a need for a control system that can improve the driving efficiency of a stepping driving device including a piezoelectric ceramic module. Summary of the invention

[0006] One aspect of the present invention is to provide a control system for a stepping drive device including a piezoelectric ceramic module, which can improve the driving efficiency of the piezoelectric ceramic module and achieve fast and stable driving control.

[0007] According to an exemplary embodiment, a control system for a stepping drive device is provided, the stepping drive device including a piezoelectric ceramic module for driving, the control system including: a charging circuit connected to the piezoelectric ceramic module through a first switch to charge the piezoelectric ceramic module; a discharging circuit connected to the piezoelectric ceramic module through a second switch to discharge the piezoelectric ceramic module; and a switch control unit connected to the first switch and the second switch, the switch control unit being configured to control the conduction and cutoff of the first switch and the second switch to switch between charging and discharging.

[0008] In some examples, the switch control unit is configured to: turn on the first switch and turn off the second switch so that the charging circuit charges the piezoelectric ceramic module; and turn off the first switch and turn on the second switch so that the discharge circuit discharges the piezoelectric ceramic module.

[0009] In some examples, the charging circuit includes a charging power source connected to the piezoelectric ceramic module through the first switch, and the discharging circuit includes a discharging power source connected to the piezoelectric ceramic module through the second switch.

[0010] In some examples, the charging power source includes an analog signal generator that generates an analog charging signal to charge the piezoelectric ceramic module.

[0011] In some examples, the discharge power source includes ground or a constant voltage source.

[0012] In some examples, the analog charging signal is a sawtooth wave signal.

[0013] In some examples, the sawtooth wave signal includes a low level holding interval, a rising edge, a high level holding interval, and a falling edge, and the slope of the rising edge is smaller than the slope of the falling edge.

[0014] In some examples, during the rising edge of the sawtooth wave signal, the first switch is turned on and the second switch is turned off, so that the piezoelectric ceramic module is charged by the sawtooth wave signal. During the falling edge of the sawtooth wave signal, the first switch is turned off and the second switch is turned on, so that the piezoelectric ceramic module is discharged by the discharge power supply.

[0015] In some examples, the charging power supply also includes a synchronization signal generator that generates a synchronization trigger signal based on the analog charging signal, and the switch control unit controls the conduction and cutoff of the first switch and the second switch based on the synchronization trigger signal to switch between charging and discharging.

[0016] In some examples, the charging circuit further includes a signal amplifier to amplify the charging signal from the charging power source.

[0017] In some examples, the piezoelectric ceramic module includes a plurality of piezoelectric ceramic modules.

[0018] In some examples, the charging circuit is connected to the plurality of piezoelectric ceramic modules through the first switch, or the plurality of charging circuits are respectively connected to the plurality of piezoelectric ceramic modules through corresponding plurality of first switches.

[0019] In some examples, the discharge circuit is connected to the plurality of piezoelectric ceramic modules through the second switch, or the plurality of discharge circuits are respectively connected to the plurality of piezoelectric ceramic modules through corresponding plurality of second switches.

[0020] In some examples, the plurality of charging circuits are respectively connected to the plurality of piezoelectric ceramic modules through corresponding plurality of first switches, the plurality of discharging circuits are respectively connected to the plurality of piezoelectric ceramic modules through corresponding plurality of second switches, and the switch control unit is configured to: in the low level holding interval of the sawtooth wave signal, turn off the plurality of second switches simultaneously or sequentially, and turn on the plurality of first switches simultaneously, so as to start charging the plurality of piezoelectric ceramic modules at the same time; and in the high level holding interval of the sawtooth wave signal, turn off the plurality of first switches simultaneously or sequentially, and turn on the plurality of second switches sequentially, so as to start discharging the plurality of piezoelectric ceramic modules sequentially.

[0021] In some examples, the first switch includes a first transistor and a second transistor, the drain of the first transistor is connected to the charging circuit, the source of the first transistor is connected to the source of the second transistor, the drain of the second transistor is connected to the piezoelectric ceramic module, the gates of the first transistor and the second transistor receive a first control signal from the switch control unit, the sources of the first transistor and the second transistor receive a second control signal from the switch control unit, and the second switch includes a third transistor and a fourth transistor, the drain of the third transistor is connected to the piezoelectric ceramic module, the source of the third transistor is connected to the source of the fourth transistor, the drain of the fourth transistor is connected to the discharge circuit, the gates of the third transistor and the fourth transistor receive a third control signal from the switch control unit, and the sources of the third transistor and the fourth transistor receive a fourth control signal from the switch control unit.

[0022] In some examples, the switch control unit includes: a control signal generator configured to generate a switch control signal for controlling the first switch and the second switch; and a signal repeater for amplifying the switch control signal to achieve a voltage sufficient to drive the first switch and the second switch.

[0023] The above and other features and advantages of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1A shows a side perspective view of a stepping drive device including a piezoelectric ceramic module;

[0025] Figure 1B Shows Figure 1A An end view of a stepping drive device;

[0026] Figure 2 A schematic functional block diagram of a control system for a stepping drive device according to an exemplary embodiment of the present invention is shown.

[0027] Figure 3 An operation timing diagram of a control system according to an exemplary embodiment of the present invention is shown.

[0028] Figure 4A and 4B Schematic circuit diagrams of a charging circuit switch and a discharging circuit switch in a control system according to an exemplary embodiment of the present invention are respectively shown.

[0029] Figure 5 A schematic functional block diagram of a switch control unit in a control system according to an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0031] Figure 1A shows a side perspective view of a stepping drive device including a piezoelectric ceramic module, Figure 1B An end view thereof is shown. Figure 1A and 1B As shown, the stepping drive device includes a stator 10 , a mover 20 , and at least one piezoelectric ceramic module 30 .

[0032] The stator 10 may include an opening, and the mover 20 is installed in the opening of the stator 10. In other embodiments, the stator 10 may also include a slide groove instead of the opening, such as a slide groove in an inverted trapezoidal shape or other shapes, and the mover 20 is installed in the slide groove of the stator 10. Thus, the mover 20 can slide relative to the stator 10 along the first direction X, that is, the axial direction of the mover 20. At least one piezoelectric ceramic module 30 ( Figure 1A and Figure 1B 3 are shown as examples in the figure) fixed to the stator 10 and in contact with the mover 20, and the surface of the piezoelectric ceramic module 30 in contact with the mover 20 is a friction surface 30', which extends along the axial direction X. When a voltage signal is applied, the piezoelectric ceramic module 30 can produce a deformation along the axial direction X, thereby driving the mover 20 to move stepwise in the axial direction X through the friction force between the friction surface 30' and the mover 20. It should be understood that when referring to the first direction, the axial direction or the X direction, unless the context clearly states otherwise, it includes both the positive direction and the reverse direction. Moreover, when referring to positive voltages and negative voltages, they are all relative and are not limited to positive and negative values.

[0033] like Figure 1B As shown in the end view of FIG. 1 , the stator 10 is formed with a cylindrical cavity 10' extending in the axial direction X in the middle. The mover 20 is disposed in the cylindrical cavity 10' of the stator 10 and can move in the axial direction X along the cylindrical cavity 10' of the stator 10. A plurality of piezoelectric ceramic modules 30 are disposed between the inner wall of the cylindrical cavity 10' of the stator 10 and the mover 20 and are fixed to the stator 10. Figure 1B In the example, the mover 20 has a triangular prism shape, and each prism face is a plane, which serves as a sliding surface 20'. Accordingly, three piezoelectric ceramic modules 30 are respectively arranged between the inner wall of the columnar opening of the stator 10 and the mover 20 opposite to the three sliding surfaces 20', so that the friction surface 30' of the piezoelectric ceramic module 30 is in contact with the sliding surface 20' of the mover 20 but not fixed. The three sliding surfaces 20' of the mover 20 intersect each other to form a cross-sectional shape of a triangular prism. Accordingly, the columnar cavity 10' of the stator 10 can also be a roughly triangular prism cross-sectional shape, so as to be arranged one by one with the three sliding surfaces 20' of the mover 20, thereby forming a space for accommodating three piezoelectric ceramic modules 30. However, it can be understood that the cross-sectional shape of the mover 20 or the columnar cavity 10' of the stator 10 is not limited to this. Under reasonable shape matching, as long as the stable axial movement of the mover can be maintained without circumferential rotation, it can be used. In other words, in order to prevent the mover 20 from rotating, the cross-sectional shape perpendicular to the axial direction is preferably not a circle, but may be, for example, a circle with a portion cut off or other polygonal shapes.

[0034] Further, in the radial direction, since the piezoelectric ceramic module 30 contacts and presses against the stator 10 to press the mover 20, the mover 20 cannot shake radially, so that the moving direction of the mover 20 is always along the axial direction during the operation of the entire device, and it remains stable in the circumferential and radial directions without shaking, so as to achieve precise and stable unidirectional stepping drive. In addition, although the figure does not show the fixed connection details of the mover 20, it can be understood by those skilled in the art that the mover 20 can be limited to the starting position of its axial movement in addition to being limited by the stator 10 and the piezoelectric ceramic module 30 in the circumferential and radial directions. For example, in some embodiments, the columnar cavity 10' of the stator 10 may include a limit portion (not shown) at one end for limiting the axial movement of the mover 20, and the limit portion can limit the starting position of the axial movement of the mover 20.

[0035] The following briefly describes the principle of the step-by-step driving process in which the piezoelectric ceramic module 30 drives the mover 20 forward. Initially, the piezoelectric ceramic module 30 contacts the mover 20. At this time, a voltage can be gradually applied to the piezoelectric ceramic module 30, that is, the piezoelectric ceramic module 30 is charged, so that it gradually generates a first direction (i.e., Figure 1A The piezoelectric ceramic module 30 drives the mover 20 to move forward along the axial direction X by a step distance L through friction. During the charging process, there may be substantially static friction between the piezoelectric ceramic module 30 and the mover 20, that is, there may be almost no relative movement between the friction surfaces 30' and 20' of the two. It can be understood that the step distance L can be determined according to the material and size of the piezoelectric ceramic stack and the magnitude of the applied voltage.

[0036] Then, the piezoelectric ceramic module 30 can be driven to generate a second deformation in the opposite direction of the first direction relative to the first deformation state. The magnitude of the second deformation can be arbitrarily selected. For example, the magnitude of the second deformation can be equal to the magnitude of the first deformation, so that the piezoelectric ceramic module 30 is restored to its original shape from the first deformation state (e.g., Figure 3As shown); or, the size of the second deformation can be smaller than the size of the first deformation, so that the piezoelectric ceramic module 30 partially recovers from the state of the first deformation to its original shape; or, the size of the second deformation can be larger than the size of the first deformation, so that after the piezoelectric ceramic module 30 recovers from the state of the first deformation to its original shape, it further produces deformation in the opposite direction. It can be understood that this can be achieved by reducing the driving voltage and discharging the piezoelectric ceramic module 30, for example, the driving voltage can be partially reduced, the driving voltage can be reduced to zero, or even changed to an inverted voltage, and the reduction amplitude of the driving voltage corresponds to the size of the second deformation. During the discharge process, the voltage applied to the piezoelectric ceramic module 30 can be rapidly reduced, that is, the speed at which the piezoelectric ceramic module 30 produces the second deformation is faster than the speed at which the first deformation is produced above. Preferably, the speed at which the piezoelectric ceramic module produces the second deformation is much faster than the speed at which the first deformation is produced. In this way, since the piezoelectric ceramic module 30 quickly retreats, sliding friction occurs between it and the mover 20, and the retreat distance d of the mover 20 is less than the forward distance L, so that the mover 20 completes a step forward movement. By repeating the above process, the mover 20 can be continuously moved forward. In addition, by driving the piezoelectric ceramic module 30 in reverse phase to the above process, for example, applying reverse voltage to the piezoelectric ceramic stack, the mover 20 can be continuously moved in the opposite direction, thereby achieving, for example, a backward process.

[0037] It can be understood that the piezoelectric ceramic module 30 can be only one to achieve the above-mentioned driving process. In some embodiments, multiple piezoelectric ceramic modules 30 may also be included, and the multiple piezoelectric ceramic modules 30 can be driven simultaneously according to the above method to achieve the above-mentioned moving process. In this case, since the speed at which multiple piezoelectric ceramic modules 30 are withdrawn at the same time is very fast, the dynamic friction between the piezoelectric ceramic module 30 and the mover 20 is not enough to provide the mover 20 with the same backward acceleration, so that the withdrawal distance d of the mover 20 is less than the forward step L, and forward movement is achieved. In other embodiments, when withdrawing, each piezoelectric ceramic module 30 can be withdrawn one by one, or part of the piezoelectric ceramic module 30 can be withdrawn in sequence, so that the withdrawal distance d of the mover 20 can be reduced or even eliminated, and the moving efficiency of the mover 20 can be improved. Specifically, when the piezoelectric ceramic module 30 moves forward, it is preferably driven to deform all the multiple piezoelectric ceramic modules 30 at the same time, so that the multiple piezoelectric ceramic modules 30 generate a large static friction force, driving the mover 20 to move. Then, when retreating, each or a small number of piezoelectric ceramic modules 30 can be driven to retreat in sequence. In this way, since the friction force of a single or a small number of piezoelectric ceramic modules 30 is not enough to drive the mover 20 to move, the mover 20 will not retreat, but remain in its original position. At this time, the forward step length of the mover 20 in one cycle is equal to the step length L of the forward movement, thereby achieving a relatively large step length. The advantage of this control method is that the mover will no longer have any retreat behavior during the forward movement, ensuring the stability of the moving direction. In the scheme where multiple piezoelectric ceramic modules 30 retreat in sequence, there is no specific requirement for the retreat speed of the piezoelectric ceramic module 30, but preferably, each piezoelectric ceramic module 30 still retreats at a faster speed, that is, the retreat speed is greater than its forward speed, so as to achieve high driving efficiency.

[0038] The structure and operating principle of the stepping drive device including the piezoelectric ceramic module are briefly described above, and other embodiments of the stepping drive device are also described in the Chinese utility model patent application 201721879297.9 entitled "Stepping drive device and strain applying device including the drive device" filed by the applicant on December 28, 2017, which is incorporated herein by reference in its entirety. It should be understood that those skilled in the art can make many modifications in form and details to the stepping drive device, which does not require creative labor.

[0039] It can be understood from the above description that in the driving process of the stepping drive device, the piezoelectric ceramic module needs to be charged slowly, but the piezoelectric ceramic module needs to be discharged quickly. When a fast discharge operation is performed, a large discharge current will be generated. In a conventional drive control module, the same power supply and circuit path are used to charge and discharge the piezoelectric ceramic module. When charging, it is necessary to amplify the voltage signal, and generally amplify the voltage to more than 100 volts, such as a range of 200-400 volts, to charge the piezoelectric ceramic module. Therefore, the maximum current that the circuit can carry is limited, which limits the speed of the discharge operation, making it difficult to discharge at a desired speed, resulting in low discharge efficiency. When the capacitance of the piezoelectric ceramic module is large, this problem becomes more serious, and the driving efficiency is greatly reduced.

[0040] Therefore, the present invention also provides a control system, which can charge and discharge the piezoelectric ceramic module through a separate channel, greatly improving the discharge efficiency of the piezoelectric ceramic module, that is, improving the driving efficiency of the stepping drive device. Moreover, the control system can control the charging and discharging timing of each piezoelectric ceramic module, so that they are charged at the same time and discharged in sequence, thereby making the stepping motion more stable and the driving force stronger.

[0041] Figure 2 A structural block diagram of a control system according to an exemplary embodiment of the present invention is shown, which includes separate charging circuits and discharging circuits, which are respectively connected to the piezoelectric ceramic module through corresponding switches, so that the piezoelectric ceramic module can be charged and discharged using separate channels.

[0042] Specifically, if Figure 2 As shown, the charging circuit includes a charging power source 110, which is connected to the piezoelectric ceramic module 150 through a first switch 120; the discharging circuit includes a discharging power source 130, which is connected to the piezoelectric ceramic module 150 through a second switch 140. The switch control unit 160 can control the first switch 120 and the second switch 140 to switch the charging and discharging operations of the piezoelectric ceramic module 150, which will be described in further detail below.

[0043] The charging power supply 110 may be, for example, an analog signal generator, which may generate an analog charging signal such as a sawtooth wave signal. The rising edge of the sawtooth wave signal may be used to gradually charge the piezoelectric ceramic module 150, causing it to gradually produce a positive deformation. In some embodiments, the charging signal may be amplified by the signal amplifier 112 before being provided to the piezoelectric ceramic module 150. For example, the charging signal generated by the charging power supply 110 may be only a few volts or a dozen volts in size, which may be amplified by the signal amplifier 112 to hundreds or even hundreds of volts, typically in the range of 200 volts to 400 volts, and then provided to the piezoelectric ceramic module 150. Although not shown, the charging power supply 110 may also include a synchronization signal generator that generates a synchronization trigger signal, and the switch control unit 160 may control the operation of the first switch 120 and the second switch 140 according to the synchronization trigger signal. Specifically, during charging, the first switch 120 is turned on and the second switch 140 is turned off, so that the piezoelectric ceramic module 150 is charged by using the rising edge of the sawtooth wave signal generated by the charging power supply 110; during discharging, the first switch 120 is turned off and the second switch 140 is turned on, so that the discharging power supply 130 discharges the piezoelectric ceramic module 150. It should be understood that in order to avoid electrical connection between the charging power supply 110 and the discharging power supply 130, the first switch 120 and the second switch 140 cannot be turned on at the same time. Therefore, in practical applications, one switch can generally be turned off first, and then the other switch can be turned on after a predetermined time, such as several nanoseconds, to achieve safe switching between charging and discharging.

[0044] As described above, the piezoelectric ceramic module is charged and discharged through a separate circuit, and the charging and discharging are switched through the first switch 120 and the second switch 140. The discharge power supply 130 can be ground, or a constant voltage source, which provides a voltage smaller than the charging voltage, such as a ground voltage or a positive voltage or a negative voltage close to the ground voltage. By using this separate discharge circuit, a larger discharge current can be carried, thereby realizing rapid discharge of the piezoelectric ceramic module 150 and improving the driving efficiency.

[0045] It should be understood that the piezoelectric ceramic module 150 may include one or more of the piezoelectric ceramic modules 30 described above. When multiple piezoelectric ceramic modules 30 are included, the control system 100 may include one Figure 2 The charging circuit shown in FIG. 1 is connected to a plurality of piezoelectric ceramic modules 30 through a first switch 120 to charge them simultaneously. The control system 100 may also include a plurality of Figure 2 The charging circuit shown is connected to the plurality of piezoelectric ceramic modules 30 through the corresponding plurality of first switches 120. Of course, as mentioned above, preferably, the plurality of first switches 120 can be controlled to be turned on simultaneously to charge the plurality of piezoelectric ceramic modules 30 simultaneously, so that the plurality of piezoelectric ceramic modules 30 are deformed simultaneously, thereby increasing the driving force.

[0046] When the piezoelectric ceramic module 150 includes a plurality of piezoelectric ceramic modules 30, similarly, the control system 100 may include a Figure 2 The discharge circuit shown in FIG. 1 is connected to a plurality of piezoelectric ceramic modules 30 through a second switch 140 to discharge them simultaneously. The control system 100 may also include a plurality of Figure 2 The discharge circuit shown is connected to the plurality of piezoelectric ceramic modules 30 respectively through the corresponding plurality of second switches 140. Of course, as mentioned above, preferably, the plurality of second switches 140 can be controlled to be turned on in sequence to discharge the plurality of piezoelectric ceramic modules 30 in sequence, so that the plurality of piezoelectric ceramic modules 30 can be withdrawn in sequence, thereby reducing or avoiding the withdrawal of the mover 20.

[0047] It is understood that various arrangements of the charging circuit and the discharging circuit can be combined with each other. For example, it can include one charging circuit and one discharging circuit, one charging circuit and multiple discharging circuits, multiple charging circuits and one discharging circuit, or multiple charging circuits and multiple discharging circuits. Multiple charging circuits and multiple discharging circuits are preferred, which can realize flexible driving of multiple piezoelectric ceramic modules 30 in the piezoelectric ceramic module 150. For example, multiple second switches 140 can be turned off, and multiple first switches 120 can be turned on at the same time to charge multiple piezoelectric ceramic modules 30 at the same time, and multiple first switches 120 can be turned off, and multiple second switches 140 can be turned on in sequence to discharge multiple piezoelectric ceramic modules 30 in sequence.

[0048] Figure 3 FIG. 1 shows an operation timing diagram of the control system 100 according to an exemplary embodiment of the present invention. Figure 3 As shown, the charging signal Vc generated by the charging power supply 110 is a sawtooth wave signal, each cycle of which includes a low-level holding interval p1, a rising edge p2, a high-level holding interval p3, and a falling edge p4. As mentioned above, the rising edge p2 can rise slowly so that each piezoelectric ceramic module 30 gradually deforms in the positive direction. The falling edge p4 can be much steeper than the rising edge p2, or in other words, the slope of the falling edge p4 is much greater than the slope of the rising edge p2. The synchronization signal generator in the charging power supply 110 also generates a synchronization signal Vt based on the charging signal Vc. As mentioned above, the synchronization signal Vt is used to enable the switch control unit 160 to control the charging switch 120 and the discharging switch 140 synchronously with the charging signal Vc. In Figure 3 In the example shown, the synchronization signal Vt is triggered at the end of the low-level holding interval p1 of the charging signal Vc (i.e., the starting point of the rising edge p2), but it should be understood that the synchronization signal Vt can also be triggered at other times, such as during the low-level holding interval p1, at the end of the rising edge p2, during the high-level holding interval p3, etc.

[0049] The switch control unit 160 controls the timing of the switch control signal based on the synchronization signal Vt. Figure 3 As shown, during the rising edge p2 of the charging signal Vc, the charging switch control signal Vcs is maintained at a high level to turn on the first switch 120, and the discharging switch control signal Vds1 is maintained at a low level to turn off the second switch 140, thereby charging the piezoelectric ceramic module 150. During the falling edge p4 of the charging signal Vc, the charging switch control signal Vcs is maintained at a low level to turn off the first switch 120, and the discharging switch control signal Vds1 is maintained at a high level to turn on the second switch 140, thereby discharging the piezoelectric ceramic module 150. It should be understood that the high and low levels here are only examples, and depending on the type and properties of the switch (high level conduction or low level conduction), the high and low levels of the switch control signal can be interchanged, or, when the types of the charging switch (first switch) 120 and the discharging switch (second switch) 140 are opposite to each other, the charging switch control signal Vcs and the discharging switch control signal Vds1 can be maintained at a high level or a low level at the same time. In addition, the high-low level conversion of the charging switch control signal Vcs and the discharging switch control signal Vds1 can be completed during the low level holding interval p1 and the high level holding interval p3 of the charging signal Vc, rather than being limited to the starting point and the end of the rising edge p2.

[0050] When the piezoelectric ceramic module 150 includes a plurality of piezoelectric ceramic modules 30, it may be necessary to discharge and withdraw the plurality of piezoelectric ceramic modules 30 in sequence, rather than discharge and withdraw at the same time. At this time, the switch control unit 160 may generate a plurality of discharge switch control signals, such as signals Vds1 and Vds2, whose rising edges may be at different times, so that the plurality of discharge switches 140 are opened in sequence, so as to start discharging the plurality of piezoelectric ceramic modules 30 in sequence. Figure 3 The falling edges of the multiple discharge switch control signals Vds1 and Vds2 are shown to be at the same time, but they can also be at different times within the low level holding interval p1, as long as all the discharge switches 140 are turned off when the rising edge p1 starts, that is, when charging starts. Figure 3 Although not shown, the switch control unit 160 may also generate a plurality of charging switch control signals Vcs. Preferably, the rising edges of the plurality of charging switch control signals Vcs are located at the same time at the end of the low level holding interval p1 to start charging the plurality of piezoelectric ceramic modules 30 at the same time, and the falling edges of the plurality of charging switch control signals Vcs may be located at the same or different times within the high level holding interval p3 to end charging the plurality of piezoelectric ceramic modules 30 at the same time or in sequence.

[0051] In short, during the low level holding interval p1 of the sawtooth wave signal, the multiple discharge switches 140 can be turned off simultaneously or sequentially, and after all the discharge switches 140 are turned off, the multiple charging switches 120 can be turned on simultaneously to simultaneously start charging the multiple piezoelectric ceramic modules 30. During the high level holding interval p3 of the sawtooth wave signal, the multiple charging switches 120 can be turned off simultaneously or sequentially, and the multiple discharge switches 140 can be turned on sequentially to sequentially start discharging the multiple piezoelectric ceramic modules 30.

[0052] Figure 4A and 4B Schematic circuit diagrams of a charging circuit switch 120 and a discharging circuit switch 140 in a control system 100 according to an exemplary embodiment of the present invention are shown respectively. Figure 4A As described above, the charging circuit switch 120 includes two transistors 121a and 121b, which may be, for example, triodes, field effect transistors, etc. The two transistors 121a and 121b are connected in reverse series to each other, the drain D of the first transistor 121a is used as the input terminal IN of the switch 120, the source S of the first transistor 121a is connected to the source S of the second transistor 121b, and the drain D of the second transistor 121b is used as the output terminal OUT of the switch 120. It should be understood that the input IN and the output OUT of the switch 120 can be used interchangeably. Figure 4A In the example, the input IN of the switch 120 can be used to receive the charging signal (amplified by the signal amplifier 112 ) from the charging power source 110 , and the output OUT of the switch 120 can be connected to the piezoelectric ceramic module 150 .

[0053] Continue to refer to Figure 4A, the switch 120 further includes a control bus 125 for controlling the first and second transistors 121a and 121b. An input wiring harness 126 of the control bus 125 can be connected to the switch control unit 160 to receive control signals therefrom, which are two control signals Vg and Vs, which are used to control the gate voltage Vg and source voltage Vs of the first and second transistors 121a and 121b, thereby controlling their conduction and cutoff. After the Vg signal line and the Vs signal line in the input wiring harness 126 pass through the optional hub 124, the Vs signal line can be directly connected to the source S of the first and second transistors 121a and 121b, and the Vg signal line can be divided into three paths through a node, one of which is connected to the control terminal, i.e., the gate G, of the first transistor 121a through the first resistor 122a, one is connected to the control terminal G of the second transistor 121b through the third resistor 122c, and one is connected to the source S of the first and second transistors 121a and 121b through the series-connected diode 123 and the second resistor 122b. The resistances of the first, second and third resistors 122a, 122b and 122c may be the same as or different from each other. The diode 123 may be a light emitting diode or a common diode, whose input is connected to one side of the switch control circuit 160 and whose output is connected to one side of the source S, so as to protect the switch control circuit 160. When a light emitting diode is used, it is also possible to judge whether the switch 120 is operating normally by its light emitting state.

[0054] Figure 4B The discharge circuit switch 140 is shown with Figure 4A The charging circuit switch 120 shown is basically the same. Specifically, the discharging circuit switch 140 includes third and fourth transistors 141a and 141b, which can be, for example, triodes, field effect transistors, etc. The third and fourth transistors 141a and 141b are connected in reverse series to each other, the drain D of the third transistor 141a is used as the input terminal IN of the switch 140, the source S of the third transistor 141a is connected to the source S of the fourth transistor 141b, and the drain D of the fourth transistor 141b is used as the output terminal OUT of the switch 140. It should be understood that the input IN and the output OUT of the switch 140 can be used interchangeably. Figure 4B In the example of FIG. 1 , the input IN of the switch 140 may be connected to the piezoelectric ceramic module 150 , and the output OUT may be connected to the discharge power source 130 .

[0055] Continue to refer to Figure 4B, the switch 140 further includes a control bus 145 for controlling the third and fourth transistors 141a and 141b. An input wiring harness 146 of the control bus 145 can be connected to the switch control unit 160 to receive control signals therefrom, which are two control signals Vg and Vs, which are used to control the gate voltage Vg and source voltage Vs of the third and fourth transistors 141a and 141b, thereby controlling their conduction and cutoff. After the Vg signal line and the Vs signal line in the input wiring harness 146 pass through the optional hub 144, the Vs signal line can be directly connected to the source S of the first and second transistors 121a and 121b, and the Vg signal line can be divided into three paths through a node, one of which is connected to the control terminal, i.e., the gate G, of the third transistor 141a through the fourth resistor 142a, one is connected to the control terminal G of the fourth transistor 141b through the sixth resistor 142c, and one is connected to the source S of the third and fourth transistors 141a and 141b through the series-connected diode 143 and the fifth resistor 142b. The resistances of the third, fourth and fifth resistors 142a, 142b and 142c may be the same as or different from each other. The diode 143 may be a light emitting diode or a common diode, whose input is connected to the switch control circuit 160 side and whose output is connected to the source S side, so as to protect the switch control circuit 160. When a light emitting diode is used, it is also possible to judge whether the switch 140 is operating normally by its light emitting state.

[0056] The specific circuit structure of the charging switch 120 and the discharging switch 140 is described above. As described above, in each of the charging switch 120 and the discharging switch 140, two transistors connected in reverse series are included. Through this circuit, the reverse conduction of each switch can be avoided, thereby completely isolating the charging circuit and the discharging circuit from each other, preventing the charging signal from reaching the discharging power supply 130, or preventing the discharging signal from reaching the charging power supply 110. Moreover, the switches 120 and 140 of the above structure can achieve high-speed operation, thereby switching between charging and discharging at a high speed, ensuring high driving efficiency.

[0057] Figure 5 FIG. 4 shows a schematic functional block diagram of a switch control unit 160 in a control system 100 according to an exemplary embodiment of the present invention. Figure 5As shown, the switch control unit 160 may include a control signal generator 161 and a signal relay module 162. The control signal generator 161 may receive a synchronization signal from the charging power supply 110 at the input port IN of the switch control unit 160, and generate control signals for each charging and discharging switch based on the synchronization signal. Here, taking a charging switch 120 and a discharging switch 140 as an example, only four control signals are shown, wherein each two control signals are used to control the conduction and cutoff of a switch. Each control signal from the control signal generator 161 is provided to the signal relay module 162 via a wiring harness. In the relay module 162, the wiring harness is dispersed into four paths after passing through the hub 163, and is respectively connected to the four input ports C1, C2, C3 and C4 of the signal repeater 164. The signal repeater 164 may receive a power supply Vcc from the outside, amplify the input signal to reach a voltage capable of driving each switch, and then output the amplified signal via each output port C5, C6, C7 and C8. The signal lines for controlling each switch are connected to the corresponding switch after forming a wire bundle through the hubs 165 and 166. It should be understood that in the above description, each hub is just an example, and the hub may not exist, but the signal lines are directly bundled and led out to each device.

[0058] As described above, the control system 100 can provide a separate charging circuit and a discharging circuit for each piezoelectric ceramic module 30 in the piezoelectric ceramic module 150, so that the discharge circuit can carry a larger discharge current, so that the discharge operation can be performed faster, thereby improving the driving efficiency. Moreover, by using the switch circuit of the present invention, it is possible to quickly switch between charging and discharging, and completely isolate the charging signal from the discharging signal, ensuring the normal and stable operation of the driving control.

[0059] It should also be understood that for the sake of thoroughness and completeness of disclosure, an embodiment of a stepping drive device including a piezoelectric ceramic module is described herein, but it should be understood that the control system of the present invention can be used not only in piezoelectric ceramic stepping drive devices of this structure, but can also be applied to stepping drive devices of piezoelectric ceramic modules of other structures, and both can improve the driving efficiency of the piezoelectric ceramic module by providing a separate charging and discharging path for the piezoelectric ceramic module.

[0060] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Therefore, the scope of protection of the present invention should be subject to the scope of protection of the claims.

Claims

1. A control system for a stepping drive device, the stepping drive device comprising a piezoelectric ceramic module (150) for driving, the piezoelectric ceramic module (150) comprising a plurality of piezoelectric ceramic modules (30), the control system comprising: A charging circuit connected to the piezoelectric ceramic module (150) via a first switch (120) to charge the piezoelectric ceramic module; A discharge circuit connected to the piezoelectric ceramic module (150) via a second switch (140) to discharge the piezoelectric ceramic module; as well as a switch control unit (160), connected to the first switch (120) and the second switch (140), the switch control unit (160) being configured to control the on and off of the first switch (120) and the second switch (140) to switch between charging and discharging, The charging circuit comprises a charging power source (110), and the charging power source (110) comprises an analog signal generator, which generates a sawtooth wave signal to charge the piezoelectric ceramic module (150), so that the plurality of piezoelectric ceramic modules (30) in the piezoelectric ceramic module (150) generate a first deformation. The discharge circuit comprises a discharge power source (130), the discharge power source (130) comprises a constant voltage source, the constant voltage source discharges a plurality of piezoelectric ceramic modules (30) in the piezoelectric ceramic module (150) to a reverse voltage to generate a second deformation in a direction opposite to the first deformation, and The speed at which the discharging power source (130) causes the plurality of piezoelectric ceramic modules (30) to generate the second deformation is greater than the speed at which the charging power source (110) causes the plurality of piezoelectric ceramic modules (30) to generate the first deformation.

2. The control system according to claim 1, wherein: The switch control unit (160) is configured as follows: Turning on the first switch (120) and turning off the second switch (140) so that the charging circuit charges the piezoelectric ceramic module (150); as well as The first switch (120) is turned off and the second switch (140) is turned on, so that the discharge circuit discharges the piezoelectric ceramic module (150).

3. The control system according to claim 1, wherein: The sawtooth wave signal includes a low level holding interval, a rising edge, a high level holding interval, and a falling edge, and the slope of the rising edge is smaller than the slope of the falling edge.

4. The control system according to claim 3, wherein: During the rising edge of the sawtooth wave signal, the first switch (120) is turned on and the second switch (140) is turned off, so that the piezoelectric ceramic module (150) is charged by the sawtooth wave signal, and During the falling edge of the sawtooth wave signal, the first switch (120) is turned off and the second switch (140) is turned on, so that the piezoelectric ceramic module (150) is discharged by the discharge power supply (130).

5. The control system according to claim 1, wherein: The charging power supply (110) further comprises a synchronization signal generator, which generates a synchronization trigger signal based on the sawtooth wave signal, and The switch control unit (160) controls the on and off of the first switch (120) and the second switch (140) based on the synchronous trigger signal to switch between charging and discharging.

6. The control system of claim 1, wherein: The charging circuit also includes a signal amplifier (112) for amplifying the charging signal from the charging power source (110).

7. The control system of claim 1, wherein: The charging circuit is connected to the plurality of piezoelectric ceramic modules (30) via the first switch (120), or The plurality of charging circuits are respectively connected to the plurality of piezoelectric ceramic modules (30) via corresponding plurality of first switches (120).

8. The control system of claim 1, wherein: The discharge circuit is connected to the plurality of piezoelectric ceramic modules (30) via the second switch (140), or The plurality of discharge circuits are respectively connected to the plurality of piezoelectric ceramic modules (30) via a corresponding plurality of second switches (140).

9. The control system of claim 3, wherein: The plurality of charging circuits are respectively connected to the plurality of piezoelectric ceramic modules (30) via corresponding plurality of first switches (120), The plurality of discharge circuits are respectively connected to the plurality of piezoelectric ceramic modules (30) through corresponding plurality of second switches (140), and The switch control unit (160) is configured as follows: In the low level holding interval of the sawtooth wave signal, the plurality of second switches (140) are turned off simultaneously or sequentially, and the plurality of first switches (120) are turned on simultaneously, so as to start charging the plurality of piezoelectric ceramic modules (30) at the same time; and In the high level holding interval of the sawtooth wave signal, the plurality of first switches (120) are turned off simultaneously or sequentially, and the plurality of second switches (140) are turned on sequentially, so as to start discharging the plurality of piezoelectric ceramic modules (30) sequentially.

10. The control system of claim 1, wherein: The first switch (120) comprises a first transistor and a second transistor, the drain of the first transistor is connected to the charging circuit, the source of the first transistor is connected to the source of the second transistor, the drain of the second transistor is connected to the piezoelectric ceramic module (150), the gates of the first transistor and the second transistor receive a first control signal from the switch control unit (160), the sources of the first transistor and the second transistor receive a second control signal from the switch control unit (160), and The second switch (140) includes a third transistor and a fourth transistor, the drain of the third transistor is connected to the piezoelectric ceramic module (150), the source of the third transistor is connected to the source of the fourth transistor, the drain of the fourth transistor is connected to the discharge circuit, the gates of the third transistor and the fourth transistor receive a third control signal from the switch control unit (160), and the sources of the third transistor and the fourth transistor receive a fourth control signal from the switch control unit (160).

11. The control system of claim 1, wherein: The switch control unit (160) comprises: a control signal generator configured to generate a switch control signal for controlling the first switch (120) and the second switch (140); and A signal repeater is used to amplify the switch control signal to achieve a voltage sufficient to drive the first switch (120) and the second switch (140).

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