CN105429506A - Multi-level piezoelectric ceramic driving circuit and its driving control method - Google Patents

Abstract

The invention provides a multilevel piezoelectric ceramics driving circuit suitable for large power and a driving control method thereof. The multilevel piezoelectric ceramics driving circuit comprises an n-grade multilevel cascade module, a fixed-voltage direct current module and a push-pull amplification module, wherein the n-grade multilevel cascade module comprises n multilevel units which are successively connected in series and bus voltages are E, 2E, 4E... 2n-1E, and the E is a resolving voltage; the fixed-voltage direct current module is connected in series to an output terminal of the n-grade multilevel cascade module; a high voltage side of the push-pull amplification module is connected to a high voltage output terminal UH of the fixed-voltage direct current module and a low voltage side is connected to a low voltage output terminal UL of the fixed-voltage direct current module. In the invention, through using an anisobaric multilevel cascade mode, a low voltage device is used to output a voltage in a high range; a working frequency of a switch tube can be decreased along with the decrease of a frequency of an output voltage so that switch losses of the switch tube are reduced; simultaneously, power consumption of the push-pull amplification module can be greatly reduced and efficiency is increased.

Description

Multi-level piezoelectric ceramic driving circuit and its driving control method

technical field

The invention relates to the field of driving, in particular to a multilevel piezoelectric ceramic driving circuit and a driving control method thereof.

Background technique

In recent years, the demand for high-precision positioning and drive technology in the fields of industry, aerospace, and biology has become more and more obvious, such as scanning probe microscopes, nano-positioning systems and vibration control systems, etc., especially for nano-positioning technology. One of the schemes of nanopositioning technology is to use piezoelectric ceramic actuators as actuators.

Drive circuits based on multi-level structures are also gradually applied to the high-voltage drive of piezoelectric ceramic actuators. At present, most of the multi-level drive circuits are equal-voltage multi-level units.

Contents of the invention

The present invention aims to provide a multi-level piezoelectric ceramic drive circuit suitable for high power and a drive control method thereof.

While ensuring the output voltage range of the multi-level drive circuit, the present invention can minimize the switching times of the multi-level unit switching tube when outputting low-frequency voltage or static output, so as to reduce the switching loss of the switching tube. And to make the modulation method simpler and more direct, a successive approximation multi-level high-voltage driving strategy is proposed. The driving strategy adopts unequal voltage multi-level structure and successive approximation modulation method, and the two output voltages supply power to the push-pull amplifier circuit.

The purpose of the present invention is achieved through the following technical solutions:

A successive approximation multilevel high-voltage driving strategy includes unequal voltage multilevel topology and successive approximation driving strategy. The output of the unequal-voltage multi-level topology is connected to the push-pull amplifier module to supply power for it; the push-pull amplifier circuit is driven by the drive signal, and the voltage generated directly drives the piezoelectric ceramic actuator to work; according to the successive approximation type The driving strategy controls the operation of the switching tubes of each multi-level circuit module, so that two desired output voltages can be obtained.

The unequal voltage multilevel topology includes a fixed voltage DC module and an n-level multilevel cascade module. The fixed voltage DC module is located at the output end of the unequal voltage multilevel topology and is connected in series with the n-level multilevel cascade module. way to connect. The voltage of the fixed voltage DC module is Ud, and its positive pole and negative pole are the high voltage output UH and low voltage output UL of the unequal voltage multi-level topology respectively. These two output voltages are connected to the high voltage side and the high voltage side of the push-pull amplifier module. The low-voltage side supplies power to it, which can greatly reduce the power loss of the push-pull amplifier module and improve its efficiency. The bus voltages of the n multi-level units of the n-level multi-level cascade module are E, 2E, 4E...2n-1E respectively, and they are connected in series in sequence, then the output voltage range of the n-level multi-level cascade module It is 0 to (2n-1)E. By adjusting the size of E, the resolution of the output voltage of the multilevel topology can be adjusted, and the range of the output voltage of the multilevel topology can be adjusted by selecting the size of the multilevel series n. In such an unequal voltage multi-level topology structure, the switching tube performs switching operation only when the output voltage needs to be changed. When outputting low-frequency voltage, the switching tube of the multi-level unit works at low frequency; Switching operation is required, which can reduce the switching loss of the switching tube.

The successive approximation driving strategy is to convert the expected output voltage Uexp into an n-bit binary number, the i-th bit of the n-bit binary number corresponds to the working state of the switching tube of the i-th multi-level unit, and 0 means that the upper tube is turned off and the lower 1 means that the upper tube is on and the lower tube is off. In the first step, the value of Uexp/E is calculated to obtain an integer Sint, and Sint represents that the n-level multi-level cascaded modules need to output Sint*E in total to match the expected output voltage Uexp. The second step is to perform binary conversion on Sint to obtain n-bit binary number Sbit. According to the 0th to n-1 bits of Sbit correspondingly controlling the operation of the switching tubes of the 0th to n-1 multi-level circuit modules, the desired output voltage can be obtained, so that the modulation method becomes simpler and more direct.

Description of drawings

The accompanying drawings constituting a part of this application are used to provide further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 is the schematic diagram of unequal voltage multi-level high-voltage drive circuit of the present invention;

Fig. 2 is the block diagram of successive approximation type driving strategy of the present invention;

Fig. 3 is a schematic diagram of the output voltage of the present invention.

detailed description

The specific implementation manner of the present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the present invention discloses an unequal-voltage multi-level high-voltage driving circuit of a successive approximation type unequal-voltage multi-level high-voltage driving strategy. The unequal-voltage multi-level high-voltage driving circuit includes a fixed voltage DC module, n-level multilevel cascade module and push-pull amplifier module. Among them, the n-level multi-level cascade module and the fixed voltage DC module are connected in series, the two voltage outputs of the fixed voltage DC module are connected to the push-pull amplifier module, and the push-pull amplifier module is used as an unequal voltage multi-level high-voltage output of the drive circuit.

The voltage of the fixed voltage DC module is Ud, and its positive pole and negative pole are the high voltage output UH and the low voltage output UL of the unequal voltage multi-level topology respectively, and these two output voltages are connected to the high voltage of the push-pull amplifier module side and the low voltage side to power it.

The push-pull amplifying module is driven by the driving signal V _dr to generate an output voltage UO to directly drive the piezoelectric ceramic actuator. The voltage of UO changes with the change of driving signal V _dr , but the output power is amplified. The output voltage UO of the push-pull amplifier module can be adjusted by adjusting the voltage of V _dr .

The bus voltages of the n multi-level units of the n-level multi-level cascade module are respectively E, 2E, 4E...2n-1E, and they are connected in series in sequence, then the output of the n-level multi-level cascade module The voltage range is 0~(2n-1)E.

The minimum voltage at which the output voltage can be changed is E. By adjusting the size of E, the resolution of the output voltage of the multilevel topology can be adjusted, and the range of the output voltage of the multilevel topology can be adjusted by selecting the size of the multilevel series n. Take E=5V, n=8 as an example, the range of output voltage is 0V～1275V, and the resolution is 5V.

As shown in FIG. 2 , in the successive approximation driving strategy disclosed in the present invention, in order to convert the expected output voltage Uexp into a control signal for controlling each multi-level unit switch tube, the successive approximation driving strategy is performed according to the following steps.

In the first step, the value of Uexp/E is calculated to obtain an integer Sint, and Sint represents that the n-level multi-level cascaded modules need to output Sint*E in total to match the expected output voltage Uexp.

The second step is to perform binary conversion on Sint to obtain n-bit binary number Sbit.

In the third step, 0 to n-1 control signals g are respectively generated according to bits 0 to n-1 of the Sbit, and g[i]=Sbit[i].

In the fourth step, the control signal g[i] controls the operation of the switching tube of the multi-level unit i. When g[i]=1, the upper tube of the corresponding multi-level unit is turned on and the lower tube is turned off. On the contrary, when g[ When i]=0, the upper transistor of the corresponding multi-level unit is turned off and the lower transistor is turned on. In this way, the desired output voltage can be obtained.

As shown in Figure 3, it is a schematic diagram of the output voltage of the unequal voltage multi-level topology. The high voltage output UH and the low voltage output UL both gradually increase and decrease with the minimum change voltage E, and maintain a voltage of Ud at all times. Difference. Since the high voltage output UH and the low voltage output UL of the unequal voltage multi-level topology supply power for the high voltage side and the low voltage side of the push-pull amplifier module, it is necessary to ensure that UH and UL do not overlap in size at any time, and when When multiple switch tubes are switched together, it cannot be guaranteed that the switch tubes are turned on or off at the same time, so Ud>E is required. In order to make the push-pull amplifier module have sufficient margin voltage when controlling the output, when selecting E=5V and the margin voltage is 5V, you can choose Ud=10V.

From the above description, it can be seen that the above-mentioned embodiments of the present invention have achieved the following technical effects:

1. Using the unequal voltage multi-level cascading method, low-voltage devices can be used to output a high-range voltage, and the operating frequency of the switching tube can be reduced as the frequency of the output voltage decreases, reducing the switching loss of the switching tube.

2. Using two adjustable voltages with a fixed voltage difference to supply power to the push-pull amplifier module can greatly reduce the power loss of the push-pull amplifier module and improve its efficiency.

3. The successive approximation modulation method is adopted to make the modulation simpler and more direct.

4. During static output, because there is no switching operation of the switching tube, the output voltage has no high-frequency harmonics and no filtering is required.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (5)

1. A multilevel piezoelectric ceramic drive circuit, characterized in that, comprising, n-level multi-level cascade module, fixed voltage DC module and push-pull amplifier module; The n-level multi-level cascade module includes n multi-level units arranged in series in sequence, and the bus voltages are E, 2E, 4E... ^2n- 1E, E is the resolution voltage; The fixed voltage DC module is connected in series to the output end of the n-level multilevel cascade module; The high voltage side of the push-pull amplifier module is connected to the high voltage output terminal UH of the fixed voltage DC module, and the low voltage side is connected to the low voltage output terminal UL of the fixed voltage DC module. 2. The multilevel piezoelectric ceramic driving circuit according to claim 1, wherein: Each multi-level unit includes a first switch tube connected to the high-voltage side and a second switch tube connected to the low-voltage side, and the first switch tube and the second switch tube are respectively connected to the Low-voltage side connections for multilevel units; The first switch tube and the second switch tube of the multi-level unit at the first stage are respectively connected to the low-voltage side of the fixed-voltage DC module. 3. The multilevel piezoelectric ceramic drive circuit according to claim 1, characterized in that, The voltage of the fixed voltage DC module is Ud, where Ud>E. 4. The multilevel piezoelectric ceramic driving circuit according to claim 3, wherein Ud=2E. 5. A drive control method for a multilevel piezoelectric ceramic drive circuit, characterized in that the method comprises: Step S1, calculate Uexp/E and round to obtain an integer Sint, where Uexp is the expected output voltage, and E is the resolution voltage; Step S2, performing binary conversion of Sint to obtain n-bit binary number Sbit; Step S3, according to the 0th to n-1 bits of Sbit, correspondingly generate 0 to n-1 control signals g, and g[i]=Sbit[i]; Step S4, control the operation of the switching tube of the multi-level unit at the i-th stage through the control signal g[i], wherein, when g[i]=1, the first switching tube of the multi-level unit at the i-th level is turned on and the second switch is turned off; when g[i]=0, the first switch of the multilevel unit at the i-th stage is turned off and the second switch is turned on.