Servo motor driving system

Abstract

The invention provides a servo motor driving system. The input impedance of the feedback sensor is modulated by using the chopper circuit, the operational amplifier loop, the ripple suppression capacitor and the corresponding feedback electric loop, the modulation output of the input signal of the feedback sensor is realized, the PWM modulation amplifier is driven to correspondingly adjust the servo motor driving signal output by the PWM modulation amplifier, the driving efficiency of the servo motor is improved, and the service life of the servo motor is prolonged. And the stability and the driving accuracy of the system are improved. On the premise of keeping low power consumption, the equivalent input noise of the amplifier at the input end of the sensor can be effectively fed back, and electrode offset is restrained.

Description

Technical Field

[0001] The present application relates to the field of electromechanical circuit technology, and in particular to a servo motor drive system. Background Art

[0002] Servo motors used in precision systems need to accurately execute drive instructions while also providing feedback on the actual drive status of the gear mechanism through a more compact feedback sensor. The feedback sensor is usually implemented in the form of a potentiometer, which can generate a voltage corresponding to the absolute angle of the motor shaft through the gear mechanism, thereby applying the feedback voltage value to the input error comparator amplifier, and comparing the voltage generated by the current motor position generated by the potentiometer feedback with the voltage generated by the desired motor position to reduce the error.

[0003] However, due to the limitations of installation and driving requirements, the potential feedback from the potentiometer is usually a low-frequency, low-amplitude signal with a frequency of several Hz to several hundred Hz and an amplitude of tens of microvolts to several millivolts. The low-frequency characteristics usually overlap with 1 / f noise, which greatly affects the stability of the system and the accuracy of the drive. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present application provides a servo motor drive system, which adopts chopping technology to reduce the noise of the instrument amplifier, and improves the input impedance of the amplifier through a feedback loop, reduces the equivalent input noise, and suppresses electrode offset.

[0005] This application specifically adopts the following technical solutions.

[0006] Firstly, to achieve the above-mentioned purpose, a servo motor drive system is proposed, which includes a feedback sensor and a feedback amplification module arranged between a servo motor and a PWM modulation amplifier circuit; wherein the feedback amplification module includes: a capacitor chopper circuit, which includes a front and rear two-stage chopper regulator, their respective feedback circuits, a ripple suppression capacitor connected between the two-stage chopper regulator, and an intermediate operational amplifier, wherein the first-stage chopper regulator is used to modulate the input signal of the feedback sensor into a high-frequency signal, and the second-stage chopper regulator is used to modulate the high-frequency signal into a low-frequency signal, and the low-frequency signal finally outputs a sensing signal to the PWM modulation amplifier circuit through an output operational amplifier; an impedance adjustment circuit, which is connected between the PWM modulation amplifier circuit and the first-stage chopper regulator, and is used to modulate the feedback circuit of the first-stage chopper regulator; wherein the feed frequency of the feedback circuit is a preset chopping frequency fCH; the feed frequencies of the first-stage chopper regulator and the second-stage chopper regulator are two-phase non-overlapping clock signals f1 and f2 generated by the chopping frequency fCH; and the feed frequency of the frequency regulator is a frequency signal f4 generated by the non-overlapping parts of f1 and f2.

[0007] Optionally, a servo motor drive system as described in any of the above, wherein the feedback circuit of the first-stage chopper regulator includes: a first feedback power amplifier, which amplifies the signal output by the first-stage chopper regulator and passes through a ripple suppression capacitor; and a first feedback frequency modulator, which frequency-modulates the amplified signal of the first feedback power amplifier and feeds it into the input of the first-stage chopper regulator.

[0008] Optionally, a servo motor drive system as described in any of the above, wherein the feedback circuit of the second-stage chopper regulator includes an amplifying branch and an impedance branch connected in parallel with each other; the impedance branch is connected between the output end of the output operational amplifier and the input end of the intermediate operational amplifier; the amplifying branch is connected in reverse parallel at both ends of the impedance branch, and based on the equivalent impedance of the impedance branch, the input impedance of the second-stage chopper regulator is adjusted and amplified to match the equivalent output impedance of the first-stage chopper regulator and its feedback circuit.

[0009] Optionally, in any of the above servo motor drive systems, the feedback circuit of the first-stage chopper regulator and the feedback circuit of the second-stage chopper regulator are isolated from each other.

[0010] Optionally, a servo motor drive system as described in any of the above, wherein the impedance adjustment circuit includes an impedance adjustment operational amplifier, a frequency regulator and an impedance adjustment capacitor which are reversely connected in parallel between the PWM modulation amplifier circuit and the first-stage chopper regulator, and the impedance adjustment operational amplifier receives the sensor signal output to the PWM modulation amplifier circuit, modulates it to a preset frequency through the frequency regulator, and drives the impedance adjustment capacitor to charge and discharge accordingly to adjust the equivalent impedance of the first-stage chopper regulator feedback circuit.

[0011] Optionally, in any of the above servo motor drive systems, wherein the chopping frequency fCH is at least 512 kHz.

[0012] Optionally, in any of the above described servo motor drive systems, the feedback circuit of the first-stage chopper regulator and the feedback circuit of the second-stage chopper regulator are respectively connected to two mutually isolated pins of the output operational amplifier.

[0013] Optionally, in a servo motor drive system as described above, the impedance adjustment circuit and the feedback circuit of the first-stage chopper regulator are respectively connected to the front and rear pins of the post-stage ripple suppression capacitor of the first-stage chopper regulator output.

[0014] Beneficial effects: The servo motor drive system provided by the present application utilizes a chopper circuit, an operational amplifier circuit, a ripple suppression capacitor, and a corresponding feedback circuit to modulate the input impedance of the feedback sensor, and realizes the modulated output of the feedback sensor input signal, driving the PWM modulation amplifier to correspondingly adjust the output servo motor drive signal, thereby improving the driving efficiency of the servo motor, and enhancing the stability of the system and the driving accuracy. The present application can effectively feedback the equivalent input noise of the sensor input amplifier and suppress electrode offset while maintaining low power consumption.

[0015] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or may be understood by practicing the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings: Figure 1 It is a schematic diagram of the principle of the servo motor drive system of the present application.

[0017] Figure 2 It is a schematic diagram of the circuit principle of the feedback amplifier unit of the present application.

[0018] Figure 3 This application Figure 2 Waveform diagram of each frequency signal in . DETAILED DESCRIPTION

[0019] In order to make the purpose and technical solution of the embodiment of the present application clearer, the technical solution of the embodiment of the present application will be clearly and completely described in conjunction with the drawings of the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, not all of the embodiments. Based on the described embodiment of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0021] The term “connection” as used in this application may mean a direct connection between components or an indirect connection between components via other components.

[0022] Figure 1 A servo motor drive system according to the present application includes a feedback sensor and a feedback amplification module arranged between the servo motor and the PWM modulation amplification circuit; Among them, the feedback sensor detects the output state of the servo motor and can usually be set as an integrated potentiometer. The feedback amplification module receives the input signal of the potentiometer and amplifies it to an appropriate size through several stages of operational amplifiers in the capacitor chopper circuit to drive the PWM modulation amplifier to adjust the servo motor drive signal output accordingly, thereby improving the driving efficiency of the servo motor.

[0023] Specific reference Figure 2 In this application, the feedback amplification module includes: A capacitor chopper circuit, comprising two stages of chopper regulators, their respective feedback circuits, a ripple suppression capacitor connected between the two stages of chopper regulators, and an intermediate operational amplifier A1, wherein the first stage chopper regulator CH1 is used to modulate the input signal of the feedback sensor into a high-frequency signal, and the second stage chopper regulator CH2 is used to modulate the high-frequency signal into a low-frequency signal, and the low-frequency signal finally outputs a sensing signal to the PWM modulation amplifier circuit through the output operational amplifier A2; The impedance adjustment circuit is connected between the PWM modulation amplifier circuit and the first-stage chopper regulator CH1 and is used for modulating the feedback circuit of the first-stage chopper regulator CH1.

[0024] Wherein, the feedback circuit of the first-stage chopper regulator CH1 includes: A first feedback power amplifier A5, which amplifies the signal output by the first-stage chopper regulator CH1 and passes through the ripple suppression capacitor; The first feedback frequency modulator CH5 performs frequency modulation on the amplified signal of the first feedback power amplifier A5 and feeds the frequency into the input end of the first-stage chopper regulator CH1.

[0025] The feedback circuit of the second-stage chopper regulator CH2 includes an amplifying branch and an impedance branch connected in parallel with each other, wherein the impedance branch is connected between the output end of the output operational amplifier A2 and the input end of the intermediate operational amplifier A1; the amplifying branch is connected in reverse parallel at both ends of the impedance branch, and the input impedance of the second-stage chopper regulator CH2 is adjusted and amplified based on the equivalent impedance of the impedance branch to match the equivalent output impedance of the first-stage chopper regulator CH1 and its feedback circuit.

[0026] The impedance adjustment circuit includes: an impedance adjustment operational amplifier A4, a frequency regulator CH4 and an impedance adjustment capacitor C4 which are connected in reverse parallel between the PWM modulation amplifier circuit and the first-stage chopper regulator CH1. The impedance adjustment operational amplifier A4 receives the sensing signal output to the PWM modulation amplifier circuit, modulates the sensing signal to a preset frequency through the frequency regulator CH4, and drives the impedance adjustment capacitor C4 to charge and discharge accordingly to adjust the equivalent impedance of the feedback circuit of the first-stage chopper regulator CH1.

[0027] In the above circuit, the frequency fed into CH5 and CH3 in the feedback circuit is a preset chopping frequency fCH, which is generally set above 512kHz according to the accuracy requirements of the system; The feed frequency of the first stage chopper regulator CH1 and the second stage chopper regulator CH2 is Figure 3 The two-phase non-overlapping clock signals f1 and f2 generated by the chopping frequency fCH are shown; The input frequency of the frequency regulator CH4 is a frequency signal f4 generated by the non-overlapping parts of f1 and f2, which can be obtained by performing an OR operation on the two-phase non-overlapping clock signals f1 and f2.

[0028] The potential signal of the real-time servo motor output terminal acquired by the feedback sensor is connected to the upper plate of the first ripple suppression capacitor C1 through CH1, and then sequentially passes through the intermediate operational amplifier A1 and the second ripple suppression capacitor C2, and is fed into the positive input terminal of the operational amplifier A2 after the second chopper regulator CH2. The inverting output terminal of the output operational amplifier A2 can be connected in series with a feedback resistor, or the potential signal can be modulated and output by integrating the differential output signal between the two operational amplifiers through the feedback loop between its subsequent stage and the intermediate operational amplifier A1.

[0029] In the feedback circuit of the second-stage chopper regulator CH2, the non-phase input terminal of the chopper regulator CH3 is connected to the non-phase output terminal of the operational amplifier A2, and the non-phase output terminal of the chopper regulator CH3 is connected to the non-phase input terminal of the intermediate operational amplifier A1 after being connected in series with a negative feedback capacitor C3. In the feedback circuit of the first-stage chopper regulator CH1, the first feedback power amplifier A5 and the output terminal of the feedback circuit of the second-stage chopper regulator CH2 are isolated from each other. The isolation method can be realized by connecting the feedback circuit of the first-stage chopper regulator CH1 and the feedback circuit of the second-stage chopper regulator CH2 to two mutually isolated pins of the intermediate operational amplifier A1. In the case of higher isolation requirements, it can also be realized by adding a special isolation module to the operational amplifier A2. High isolation can effectively avoid the interference of the tuning amount on the chopping, so as to effectively improve the processing accuracy of the system.

[0030] In the feedback circuit of the second-stage chopper regulator CH2, at this time, the inverting input terminal and the non-phase output terminal of the third operational amplifier A3 can be connected in series with the capacitor C3 of CH3 to form an integrator. According to the chopping frequency of the chopper regulator CH1, the error of the input signal is integrated and fed back to the inverting terminal of the previous stage A1 to achieve cancellation. VIN is modulated into a high-frequency signal by the first chopper regulator CH1 and then amplified by the operational amplifier A1, and at the same time, the integration of the high-frequency signal by A5 is used to achieve feedforward amplification. It is then demodulated into a low-frequency signal through another ripple suppression capacitor C2 and the second chopper regulator CH2, and finally amplified and output through the output operational amplifier A2. In the above circuit, the gain can be dynamically adjusted according to the frequency of the chopping signal and the accumulated error of the signal by integration.

[0031] However, due to the chopping modulation of the input terminal, the input impedance of the feedback amplifier circuit provided by the present application is reduced, and the error caused by the ripple voltage is introduced. Therefore, the present application also adds another positive feedback loop in the circuit to increase the impedance.

[0032] The impedance adjustment circuit and the feedback circuit of the first-stage chopper regulator CH1 are respectively connected to the front and rear pins of the output post-stage ripple suppression capacitor of the first-stage chopper regulator CH1, and are composed of a frequency regulator CH4, a feedback capacitor C4, and an operational amplifier A4. The frequency regulator CH4 modulates the output signal to a high frequency, which is then converted into a current by the feedback capacitor C4 and injected into the input terminal. The current can effectively compensate for the current drawn from the piezoelectric sensing signal source by the switch capacitor resistor formed by the first chopper regulator CH1 and the capacitor C1, thereby increasing the input impedance of the amplifier and reducing the input noise of the feedback amplifier module.

[0033] In addition, the input frequency f4 of the frequency regulator CH4 can also greatly increase the input impedance of the front end by pre-charging C4 and C1, and integrate into a triangular ripple voltage through CC, thereby limiting the swing of the amplifier output end and isolating the DC path between the first operational amplifier A1 and the second operational amplifier A2, so that the offset current has no effect on the subsequent stage and the generation of ripple voltage is suppressed.

[0034] Therefore, the servo loop provided by the present application can convert the output voltage into current by integrating with the chopper regulator CH5 and the feedback circuit of the operational amplifier, which can effectively suppress the DC offset and suppress the feeding of clutter interference signals. At the same time, the integration process is not directly connected to the operational amplifier, and the current from the DC servo loop can be blocked by the isolation. As a result, the DC servo loop does not affect the operation of the positive feedback loop, thereby greatly improving the impedance of the amplifier at low frequency, reducing the equivalent input noise, suppressing electrode offset, and improving the stability of the servo system and the accuracy of the drive.

[0035] The above is only an implementation method of the present application, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application.

Claims

1. A servo motor drive system, characterized in that: It includes a feedback sensor and a feedback amplification module arranged between the servo motor and the PWM modulation amplification circuit; Wherein, the feedback amplification module comprises: A capacitor chopper circuit comprises a front and rear two-stage chopper regulator, their respective feedback circuits, a ripple suppression capacitor connected between the two-stage chopper regulator, and an intermediate operational amplifier (A1), wherein the first-stage chopper regulator (CH1) is used to modulate the input signal of the feedback sensor into a high-frequency signal, and the second-stage chopper regulator (CH2) is used to modulate the high-frequency signal into a low-frequency signal, and the low-frequency signal finally outputs a sensing signal to a PWM modulation amplifier circuit through an output operational amplifier (A2); An impedance adjustment circuit is connected between the PWM modulation amplifier circuit and the first-stage chopper regulator (CH1) and is used to modulate a feedback circuit of the first-stage chopper regulator (CH1); Wherein, the feed frequency of the feedback circuit is a preset chopping frequency fCH; The feed frequencies of the first-stage chopper regulator (CH1) and the second-stage chopper regulator (CH2) are two-phase non-overlapping clock signals f1 and f2 generated by the chopping frequency fCH; The input frequency of the frequency regulator (CH4) is the frequency signal f4 generated by the non-overlapping parts of f1 and f2.

2. The servo motor drive system according to claim 1, characterized in that: The feedback circuit of the first stage chopper regulator (CH1) includes: A first feedback power amplifier (A5) amplifies the signal output by the first-stage chopper regulator (CH1) and passing through the ripple suppression capacitor; The first feedback frequency modulator (CH5) performs frequency modulation on the amplified signal of the first feedback power amplifier (A5) and feeds the frequency into the input end of the first stage chopper regulator (CH1).

3. The servo motor drive system according to claim 1, characterized in that: The feedback circuit of the second-stage chopper regulator (CH2) includes an amplification branch and an impedance branch connected in parallel with each other; The impedance branch is connected between the output end of the output operational amplifier (A2) and the input end of the intermediate operational amplifier (A1); The amplifying branch is connected in reverse parallel at both ends of the impedance branch, and based on the equivalent impedance of the impedance branch, the input impedance of the second-stage chopper regulator (CH2) is adjusted and amplified to match the equivalent output impedance of the first-stage chopper regulator (CH1) and its feedback circuit.

4. The servo motor drive system according to claim 2-3, characterized in that: A feedback circuit of the first-stage chopper regulator (CH1) and a feedback circuit of the second-stage chopper regulator (CH2) are isolated from each other.

5. The servo motor drive system according to claims 1 to 4, characterized in that: The impedance adjustment circuit comprises an impedance adjustment operational amplifier (A4), a frequency regulator (CH4) and an impedance adjustment capacitor (C4) which are connected in reverse parallel between a PWM modulation amplifier circuit and a first-stage chopper regulator (CH1); the impedance adjustment operational amplifier (A4) receives a sensing signal output to the PWM modulation amplifier circuit, modulates the sensing signal to a preset frequency through the frequency regulator (CH4), drives the impedance adjustment capacitor (C4) to charge and discharge accordingly, so as to adjust the equivalent impedance of a feedback circuit of the first-stage chopper regulator (CH1).

6. The servo motor drive system according to claims 1-5, characterized in that: The chopping frequency fCH is at least 512 kHz.

7. The servo motor drive system according to claim 4, characterized in that: The feedback circuit of the first-stage chopper regulator (CH1) and the feedback circuit of the second-stage chopper regulator (CH2) are respectively connected to two mutually isolated pins of the intermediate operational amplifier (A1).

8. The servo motor drive system according to claims 1 to 7, characterized in that: The impedance adjustment circuit and the feedback circuit of the first-stage chopper regulator (CH1) are respectively connected to the front and rear pins of the output rear-stage ripple suppression capacitor of the first-stage chopper regulator (CH1).

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