A high-precision wide-voltage constant current source suitable for voice coil motor drives on a three-dimensional platform

Abstract

A high-precision, wide-voltage constant-current source suitable for voice coil motor drives on a three-dimensional platform includes a composite operational amplifier module, a negative feedback proportional module, a positive feedback proportional module, an inverting proportional module, a non-inverting proportional module, a first protection module, a frequency compensation module, a voltage expansion module, a second protection module, a sampling resistor, a reference voltage source, and a load. The inverting and non-inverting proportional modules are used to attenuate the negative and positive feedback signals, respectively, to ensure they meet the maximum input common-mode voltage range of the composite operational amplifier, achieving high-precision error correction and output voltage expansion. The voltage expansion module doubles the voltage across the load, further expanding the output voltage.

Description

Technical Field

[0001] This invention relates to a high-precision wide-voltage constant current source suitable for driving voice coil motors on a three-dimensional platform, belonging to the field of constant current driving. Background Technology

[0002] Ultra-high precision, ultra-high stability, and ultra-high agility (referred to as "triple-high") control is the future development trend of high-performance satellite platforms. The triple-high platform control system uses a voice coil motor as the actuator. Its control precision and response speed directly affect the control precision and agility of the control system. The control precision and response speed of the voice coil motor, in turn, directly depend on the control precision and response speed of the constant current source. With a fixed equivalent inductance of the voice coil motor, the current response speed of the constant current source is proportional to the driving voltage. Therefore, improving the current precision and driving voltage capability of the constant current source is key to improving the performance indicators of the triple-high platform.

[0003] In existing technologies, voice coil motors can be driven using a power operational amplifier (op-amp) configured as a Howland constant current source. To improve voltage drive capability, a bridge-type Howland constant current source is typically used. In the diagram, power op-amp PA1, four external resistors R11, R12, R21, and R22, and a sampling resistor RS constitute the Howland constant current source. Power op-amp PA2, along with external resistors R8 and R9, constitutes an inverting amplifier. The load RL is connected between the sampling resistor RS and the output of power op-amp PA2. Since the output voltage of power op-amp PA2 is always equal in amplitude but opposite in phase to the output voltage of power op-amp PA1, theoretically, the maximum voltage across the load RL is twice the maximum output voltage of the power op-amp. This constant current source has sufficient current and voltage drive capability; however, due to the low open-loop gain and large offset temperature drift of the power op-amp, the output current is severely affected by temperature. This makes it difficult to achieve high precision in harsh temperature environments, failing to meet the ultra-high precision requirements of the Three-U platform for voice coil motors.

[0004] In existing technologies, to improve current accuracy while maintaining current drive capability, a composite operational amplifier (op-amp) can be used to construct a composite op-amp power Howland constant current source. A precision op-amp (OP) and a power op-amp (PA) constitute the composite op-amp, which, along with its four external resistors R11, R12, R21, and R22, and a sampling resistor RS, forms the composite op-amp power Howland constant current source. Since the open-loop gain and offset temperature drift of the composite op-amp are primarily determined by the precision op-amp (OP), high accuracy can be achieved. However, limited by the supply voltage, input common-mode voltage, and output voltage of the precision op-amp (OP), the maximum output voltage of this constant current source is determined by the maximum output voltage of the precision op-amp, which is much smaller than the maximum output voltage capability of the power op-amp. This results in insufficient voltage drive capability of the constant current source, failing to meet the ultra-high agility requirements of the voice coil motor on the Sanchao platform. Summary of the Invention

[0005] The technical problem solved by this invention is: in the existing technology, the small open-loop gain of the power operational amplifier and the large offset temperature drift cause the bridge power Howland constant current source to be unable to achieve high precision, and the limitation of the supply voltage, input common-mode voltage and output voltage range of the precision operational amplifier causes the composite operational amplifier power Howland constant current source to have insufficient voltage driving capability. Therefore, a high-precision wide-voltage constant current source suitable for voice coil motor driving of the three-super platform is proposed.

[0006] The present invention solves the above-mentioned technical problem through the following technical solution:

[0007] A high-precision wide-voltage constant current source suitable for voice coil motor drive on a three-dimensional platform includes a composite operational amplifier module, a negative feedback proportional module, a positive feedback proportional module, an inverting proportional module, a non-inverting proportional module, a first protection module, a frequency compensation module, a voltage extension module, a second protection module, a sampling resistor, a reference voltage source, and a load.

[0008] The composite operational amplifier module corrects the error signals generated by the positive feedback proportional module and the negative feedback proportional module, and outputs the drive current and drive voltage to the load; the negative feedback proportional module is used to set the negative feedback coefficient and generate the negative feedback signal, and the positive feedback proportional module is used to set the positive feedback coefficient and generate the positive feedback signal; the inverting input proportional module is used to attenuate the negative feedback signal, and the non-inverting input proportional module is used to attenuate the positive feedback signal.

[0009] The voltage extension module enhances the driving capability of the drive voltage output by the composite operational amplifier module; the first protection module provides a discharge path for the back electromotive force generated when the current of the load and sampling resistor changes suddenly; the frequency compensation module provides frequency compensation for the load to prevent self-oscillation; the second protection module provides a discharge path for the back electromotive force generated when the current of the voltage extension module and the load changes suddenly; the load operates according to the received drive current and drive voltage.

[0010] The reference voltage source provides a reference voltage signal for the wide voltage constant current source.

[0011] The negative feedback proportional module includes a first negative feedback proportional resistor R11 and a second negative feedback proportional resistor R12, connected in series; the positive feedback proportional module includes a first positive feedback proportional resistor R21 and a second positive feedback proportional resistor R22, connected in series; the inverting input proportional module includes a first inverting input proportional resistor R13 and a second inverting input proportional resistor R14; the non-inverting input proportional module includes a first non-inverting input proportional resistor R23 and a second non-inverting input proportional resistor R24; the first protection module includes a first diode D1 and a second diode D2; the frequency compensation module includes a frequency compensation resistor RC and a frequency compensation capacitor CC, wherein:

[0012] One end of the negative feedback first proportional resistor R11 is connected to the inverting reference input terminal INN. The other end of the negative feedback first proportional resistor R11 is simultaneously connected to one end of the negative feedback second proportional resistor R12 and one end of the inverting terminal second proportional resistor R14. The other end of the inverting terminal second proportional resistor R14 is simultaneously connected to the inverting input terminal of the composite operational amplifier module and one end of the inverting terminal first proportional resistor R13. The other end of the inverting terminal first proportional resistor R13 is grounded. The other end of the negative feedback second proportional resistor R12 is simultaneously connected to the output terminal of the composite operational amplifier module, the anode of the first diode D1, the cathode of the second diode D2, and the upper end of the sampling resistor RS. The lower end of the sampling resistor RS is simultaneously connected to the frequency compensation resistor. The upper end of capacitor CC, the upper end of load RL, and one end of the positive feedback second proportional resistor R22 are connected; the other end of the positive feedback second proportional resistor R22 is simultaneously connected to one end of the positive feedback first proportional resistor R21 and one end of the non-inverting second proportional resistor R24; the other end of the positive feedback first proportional resistor R21 is connected to the non-inverting reference input INP; the other end of the non-inverting second proportional resistor R24 ​​is simultaneously connected to the non-inverting input of the composite operational amplifier module and one end of the non-inverting first proportional resistor R23, the other end of the non-inverting first proportional resistor R23 is grounded, the lower end of frequency compensation capacitor CC is connected to the upper end of frequency compensation resistor RC, and the lower end of frequency compensation resistor RC and the lower end of load RL are simultaneously grounded.

[0013] The composite operational amplifier module includes a first operational amplifier OP1, a second operational amplifier OP2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The first operational amplifier OP1 is used to achieve precision error correction. The second operational amplifier OP2 and its peripheral fifth resistor R5, sixth resistor R6, and seventh resistor R7 constitute a non-inverting amplifier, which is used to amplify the output voltage of the first operational amplifier OP1 to improve the voltage drive capability.

[0014] The second operational amplifier, OP2, is a power operational amplifier used to provide the power required by the load, namely the drive current and drive voltage.

[0015] The voltage expansion module includes a third operational amplifier OP3, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10, which are arranged around the third operational amplifier OP3 to form an inverting amplifier. The third operational amplifier OP3 is the same model as the second operational amplifier OP2. The output voltage OUT2 of the inverting amplifier is equal in amplitude and opposite in phase to the output voltage VPA of the composite operational amplifier module.

[0016] The output modes of the motor drive current include in-phase output mode and out-of-phase output mode;

[0017] The reference voltage source includes a positive common terminal P and a negative common terminal N. When the non-inverting reference input terminal INP and the positive common terminal P are shorted, and the inverting reference input terminal INN and the negative common terminal N are shorted at the same time, the output mode is the non-inverting output mode.

[0018] When the non-inverting reference input terminal INP and the negative common terminal N are shorted, and the inverting reference input terminal INN and the positive common terminal P are shorted at the same time, the output mode is the inverting output mode.

[0019] In non-in-phase output mode, the load current IL and the reference voltage source VR are in phase, and the load current IL is:

[0020]

[0021] The constraints for the in-phase output mode are as follows:

[0022] R11=R21, R12=R22, R13=R23, R14=R24

[0023] In inverted output mode, the load current IL and the reference voltage source VR are out of phase, and the load current IL is:

[0024]

[0025] The constraints for the inverted output mode are as follows:

[0026]

[0027] The negative feedback first proportional resistor R11, negative feedback second proportional resistor R12, positive feedback first proportional resistor R21, positive feedback second proportional resistor R22, inverting terminal first proportional resistor R13, inverting terminal second proportional resistor R14, non-inverting terminal first proportional resistor R23, non-inverting terminal second proportional resistor R24, and sampling resistor RS are all high-precision resistors. The selection criteria for high-precision resistors are: initial accuracy ≤ 0.1% and temperature coefficient ≤ 10ppm / ℃.

[0028] The gain of the non-inverting amplifier is 1 + R6 / R5, and the values ​​of the fifth resistor R5 and the sixth resistor R6 are subject to the following constraints:

[0029]

[0030] In the formula, VOP is the maximum output voltage of the first operational amplifier OP1; VPA is the output voltage of the second operational amplifier OP2; under the constraints of the values ​​of the fifth resistor R5 and the sixth resistor R6, the maximum output voltage of the composite operational amplifier module is determined by the power operational amplifier in the subsequent stage and is not limited by the maximum output voltage of the precision operational amplifier in the preceding stage.

[0031] The constraint condition for the value of the seventh resistor R7 is:

[0032] To reduce the impact of power operational amplifier bias current and temperature drift on the accuracy of the output current, the values ​​of the fifth resistor R5 and the sixth resistor R6 are determined based on the constraints.

[0033]

[0034] The inverting input proportional module and the non-inverting input proportional module are used to attenuate the negative feedback signal and the positive feedback signal, respectively. The values ​​of the first negative feedback proportional resistor R11, the second negative feedback proportional resistor R12, the first inverting input proportional resistor R13, and the second inverting input proportional resistor R14 are subject to the following constraints:

[0035]

[0036] In the formula, Vn is the maximum common-mode voltage of the inverting input terminal of the first operational amplifier OP1, VPA is the output voltage of the second operational amplifier OP2, and VRN is the voltage signal of the inverting reference input terminal INN.

[0037] The constraints for the values ​​of the first proportional resistor R21, the second proportional resistor R22, the first proportional resistor R23 at the non-inverting input, and the second proportional resistor R24 ​​at the non-inverting input are as follows:

[0038]

[0039] In the formula, Vp is the maximum common-mode voltage at the non-inverting input of the first operational amplifier OP1, VL is the voltage between the upper end of the load RL and ground, and VRP is the voltage signal at the non-inverting reference input INP.

[0040] The output voltage OUT2 of the inverting amplifier has the same amplitude and opposite phase to the output voltage VPA of the composite operational amplifier module. The driving voltage across the load RL is doubled, and the gain of the inverting amplifier satisfies -(R9 / R8) = -1. The value of the tenth resistor R10 satisfies the constraint condition.

[0041]

[0042] Under the constraint of the tenth resistor R10, the bias current and temperature drift of the third operational amplifier OP3 are ignored.

[0043] The voltage extension module does not participate in the current closed-loop control and is unrelated to the load current IL; the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 around the third operational amplifier OP3 are ordinary precision resistors, selected based on the following criteria: initial accuracy ≤1% and temperature coefficient ≤100ppm / ℃.

[0044] The load RL is selected as a resistive load or an inductive load. When the load RL is an inductive load, the first protection module and the second protection module are used to provide a discharge path for the back electromotive force generated by the sudden change in load current. The first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 are selected as high-power Schottky diodes or high-power fast recovery diodes to improve the discharge speed. The frequency compensation module is used to compensate for the phase shift caused by the inductive load and prevent the circuit from self-excited oscillation. The value range of the compensation resistor RC is 2Ω≤RC≤10Ω.

[0045] When the driving voltage across the load RL does not need to be doubled, the voltage expansion module and the second protection module are not configured, and the lower end of the load RL is directly grounded.

[0046] The advantages of this invention compared to the prior art are:

[0047] (1) The present invention provides a high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform, which has the advantages of balancing high precision and wide voltage driving capability. The output current accuracy of the present invention is not affected by the poor current temperature stability caused by the small open-loop gain and large offset temperature drift of the power operational amplifier, thus ensuring high precision of the output current. At the same time, the voltage driving capability is not limited by the supply voltage of the precision operational amplifier, the input common-mode voltage, and the output voltage range, but only depends on the maximum output voltage of the power operational amplifier. Therefore, the output voltage range is greatly improved compared with the prior art, solving the contradiction between high precision and wide voltage.

[0048] (2) This invention establishes the relationship equation between the output current and the reference voltage source. In particular, it provides the value constraints of key components when the relationship equation is valid, so that the output current is not affected by the parameters of the non-inverting proportional module and the inverting proportional module designed in this invention, and the output voltage is not limited by the input common-mode voltage and output voltage range of the precision operational amplifier. At the same time, protection circuits and frequency compensation circuits are designed for the inductive load characteristics of the voice coil motor, which have higher reliability and stability compared with the prior art. Attached Figure Description

[0049] Figure 1 A schematic diagram of a conventional bridge-type Howland constant current source provided by this invention;

[0050] Figure 2 A schematic diagram of the Howland constant current source for the power of the composite operational amplifier provided by this invention;

[0051] Figure 3 A schematic diagram of the voltage extension module and the second protection module provided for this invention;

[0052] Figure 4 A schematic diagram of the present invention without a voltage extension module and a second protection module;

[0053] Figure 5 This is a schematic diagram comparing the output voltage ranges provided by the present invention.

[0054] Figure 6 A schematic diagram comparing the impact of the offset voltage of the power operational amplifier provided by this invention on the accuracy indicators of this invention and the prior art. Detailed Implementation

[0055] A high-precision, wide-voltage constant-current source suitable for voice coil motor drives on a three-dimensional platform includes a composite operational amplifier module, a negative feedback proportional module, a positive feedback proportional module, an inverting proportional module, a non-inverting proportional module, a first protection module, a frequency compensation module, a voltage expansion module, a second protection module, a sampling resistor, a reference voltage source, and a load. The inverting and non-inverting proportional modules are used to attenuate the negative and positive feedback signals, respectively, to ensure they meet the maximum input common-mode voltage range of the composite operational amplifier, achieving high-precision error correction and output voltage expansion. The voltage expansion module doubles the voltage across the load, further expanding the output voltage.

[0056] A high-precision wide-voltage constant current source suitable for voice coil motor drive on a three-dimensional platform includes a composite operational amplifier module, a negative feedback proportional module, a positive feedback proportional module, an inverting proportional module, a non-inverting proportional module, a first protection module, a frequency compensation module, a voltage extension module, a second protection module, a sampling resistor, a reference voltage source, and a load.

[0057] The composite operational amplifier module corrects the error signals generated by the positive feedback proportional module and the negative feedback proportional module, and outputs drive current and drive voltage to provide the power required by the load; the negative feedback proportional module is used to set the negative feedback coefficient and generate the negative feedback signal, and the positive feedback proportional module is used to set the positive feedback coefficient and generate the positive feedback signal; the inverting input proportional module is used to attenuate the negative feedback signal, and the non-inverting input proportional module is used to attenuate the positive feedback signal.

[0058] The voltage extension module enhances the driving capability of the drive voltage output by the composite operational amplifier module; the first protection module provides a discharge path for the back electromotive force generated when the current of the load and sampling resistor changes suddenly; the frequency compensation module provides frequency compensation for the load to prevent self-oscillation; and the second protection module provides a discharge path for the back electromotive force generated when the current of the voltage extension module and the load changes suddenly.

[0059] The reference voltage source provides a reference voltage signal for the wide voltage constant current source.

[0060] The negative feedback proportional module includes a first negative feedback proportional resistor R11 and a second negative feedback proportional resistor R12, connected in series; the positive feedback proportional module includes a first positive feedback proportional resistor R21 and a second positive feedback proportional resistor R22, connected in series; the inverting input proportional module includes a first inverting input proportional resistor R13 and a second inverting input proportional resistor R14; the non-inverting input proportional module includes a first non-inverting input proportional resistor R23 and a second non-inverting input proportional resistor R24; the first protection module includes a first diode D1 and a second diode D2; the frequency compensation module includes a frequency compensation resistor RC and a frequency compensation capacitor CC, wherein:

[0061] One end of the negative feedback first proportional resistor R11 is connected to the inverting reference input terminal INN. The other end of the negative feedback first proportional resistor R11 is simultaneously connected to one end of the negative feedback second proportional resistor R12 and one end of the inverting terminal second proportional resistor R14. The other end of the inverting terminal second proportional resistor R14 is simultaneously connected to the inverting input terminal of the composite operational amplifier module and one end of the inverting terminal first proportional resistor R13. The other end of the inverting terminal first proportional resistor R13 is grounded. The other end of the negative feedback second proportional resistor R12 is simultaneously connected to the output terminal of the composite operational amplifier module, the anode of the first diode D1, the cathode of the second diode D2, and the upper end of the sampling resistor RS. The lower end of the sampling resistor RS is simultaneously connected to the frequency compensation resistor. The upper end of capacitor CC, the upper end of load RL, and one end of the positive feedback second proportional resistor R22 are connected; the other end of the positive feedback second proportional resistor R22 is simultaneously connected to one end of the positive feedback first proportional resistor R21 and one end of the non-inverting second proportional resistor R24; the other end of the positive feedback first proportional resistor R21 is connected to the non-inverting reference input INP; the other end of the non-inverting second proportional resistor R24 ​​is simultaneously connected to the non-inverting input of the composite operational amplifier module and one end of the non-inverting first proportional resistor R23, the other end of the non-inverting first proportional resistor R23 is grounded, the lower end of frequency compensation capacitor CC is connected to the upper end of frequency compensation resistor RC, and the lower end of frequency compensation resistor RC and the lower end of load RL are simultaneously grounded.

[0062] The composite operational amplifier module includes a first operational amplifier OP1, a second operational amplifier OP2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The first operational amplifier OP1 is used to achieve precise error correction. The second operational amplifier OP2 and its peripheral fifth resistor R5, sixth resistor R6, and seventh resistor R7 constitute a non-inverting amplifier, which is used to amplify the output voltage of the first operational amplifier OP1 in front to improve the voltage drive capability.

[0063] The second operational amplifier, OP2, is a power operational amplifier used to provide the power required by the load, namely the drive current and drive voltage.

[0064] The voltage expansion module includes the third operational amplifier OP3, the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10. It is set around the third operational amplifier OP3 to form an inverting amplifier. The model of the third operational amplifier OP3 is the same as that of the second operational amplifier OP2. The output voltage OUT2 of the inverting amplifier is equal in amplitude and opposite in phase to the output voltage VPA of the composite operational amplifier module.

[0065] The output modes of motor drive current include in-phase output mode and out-of-phase output mode;

[0066] The reference voltage source includes a positive common terminal P and a negative common terminal N. When the non-inverting reference input terminal INP and the positive common terminal P are shorted, and the inverting reference input terminal INN and the negative common terminal N are shorted at the same time, the output mode is the non-inverting output mode.

[0067] When the non-inverting reference input terminal INP and the negative common terminal N are shorted, and the inverting reference input terminal INN and the positive common terminal P are shorted at the same time, the output mode is the inverting output mode.

[0068] In non-in-phase output mode, the load current IL and the reference voltage source VR are in phase, and the load current IL is:

[0069]

[0070] The constraints for the in-phase output mode are as follows:

[0071] R11=R21, R12=R22, R13=R23, R14=R24

[0072] In inverted output mode, the load current IL and the reference voltage source VR are out of phase, and the load current IL is:

[0073]

[0074] The constraints for the inverted output mode are as follows:

[0075]

[0076] The negative feedback first proportional resistor R11, negative feedback second proportional resistor R12, positive feedback first proportional resistor R21, positive feedback second proportional resistor R22, inverting terminal first proportional resistor R13, inverting terminal second proportional resistor R14, non-inverting terminal first proportional resistor R23, non-inverting terminal second proportional resistor R24, and sampling resistor RS are all high-precision resistors. The selection criteria for high-precision resistors are: initial accuracy ≤ 0.1% and temperature coefficient ≤ 10ppm / ℃.

[0077] The gain of the non-inverting amplifier is 1 + R6 / R5. The constraints for the values ​​of the fifth resistor R5 and the sixth resistor R6 are as follows:

[0078]

[0079] In the formula, VOP is the maximum output voltage of the first operational amplifier OP1; VPA is the output voltage of the second operational amplifier OP2; under the constraints of the values ​​of the fifth resistor R5 and the sixth resistor R6, the maximum output voltage of the composite operational amplifier module is determined by the power operational amplifier in the subsequent stage and is not limited by the maximum output voltage of the precision operational amplifier in the preceding stage.

[0080] The constraint condition for the value of the seventh resistor R7 is:

[0081] To reduce the impact of power operational amplifier bias current and temperature drift on the accuracy of the output current, the values ​​of the fifth resistor R5 and the sixth resistor R6 are determined based on the constraints.

[0082]

[0083] The inverting input proportional module and the non-inverting input proportional module are used to attenuate the negative feedback signal and the positive feedback signal, respectively. The values ​​of the first negative feedback proportional resistor R11, the second negative feedback proportional resistor R12, the first inverting input proportional resistor R13, and the second inverting input proportional resistor R14 are subject to the following constraints:

[0084]

[0085] In the formula, Vn is the maximum common-mode voltage of the inverting input terminal of the first operational amplifier OP1, VPA is the output voltage of the second operational amplifier OP2, and VRN is the voltage signal of the inverting reference input terminal INN.

[0086] The constraints for the values ​​of the first proportional resistor R21, the second proportional resistor R22, the first proportional resistor R23 at the non-inverting input, and the second proportional resistor R24 ​​at the non-inverting input are as follows:

[0087]

[0088] In the formula, Vp is the maximum common-mode voltage at the non-inverting input of the first operational amplifier OP1, VL is the voltage between the upper end of the load RL and ground, and VRP is the voltage signal at the non-inverting reference input INP.

[0089] The output voltage OUT2 of the inverting amplifier has the same amplitude and opposite phase to the output voltage VPA of the composite operational amplifier module. The load RL is achieved by doubling the driving voltage across its two ends. The gain of the inverting amplifier satisfies -(R9 / R8) = -1. The value of the tenth resistor R10 satisfies the following constraints:

[0090]

[0091] Under the constraint of the tenth resistor R10, the bias current and temperature drift of the third operational amplifier OP3 are ignored.

[0092] The voltage extension module does not participate in the current closed-loop control and is unrelated to the load current IL; the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 around the third operational amplifier OP3 are ordinary precision resistors, selected based on the following criteria: initial accuracy ≤1% and temperature coefficient ≤100ppm / ℃.

[0093] The load RL can be a resistive or inductive load. When the load RL is an inductive load, the first and second protection modules are used to provide a discharge path for the back electromotive force generated by the sudden change in load current. The first diode D1, the second diode D2, the third diode D3, and the fourth diode D4 are high-power Schottky diodes or high-power fast recovery diodes to improve the discharge speed. The frequency compensation module is used to compensate for the phase shift caused by the inductive load and prevent the circuit from self-excited oscillation. The value range of the compensation resistor RC is 2Ω≤RC≤10Ω.

[0094] When the driving voltage across the load RL does not need to be doubled, the voltage expansion module and the second protection module are not configured, and the lower end of the load RL is directly grounded.

[0095] The following description, in conjunction with the accompanying drawings and preferred embodiments, provides further details:

[0096] In the current embodiment, the overall principle connection diagram of the high-precision wide-voltage constant current source is as follows: Figure 3 As shown, it includes: a composite operational amplifier module 200, a negative feedback proportional module 201, a positive feedback proportional module 202, an inverting proportional module 203, a non-inverting proportional module 204, a first protection module 205, a frequency compensation module 206, a voltage extension module 207, a second protection module 208, a sampling resistor RS, a reference voltage source VR, and a load RL.

[0097] The composite operational amplifier module 200 is used to accurately correct the error signal generated by positive and negative feedback, while providing the power required by the load, including drive current and drive voltage.

[0098] The negative feedback proportional module 201 includes a first negative feedback proportional resistor R11 and a second negative feedback proportional resistor R12, which are used to set the negative feedback coefficient.

[0099] The positive feedback proportional module 202 includes a first positive feedback proportional resistor R21 and a second positive feedback proportional resistor R22, which are used to set the positive feedback coefficient.

[0100] The inverting input proportional module 203 includes an inverting input first proportional resistor R13 and an inverting input second proportional resistor R14, which are used to attenuate the negative feedback signal.

[0101] The non-inverting proportional module 204 includes a first proportional resistor R23 and a second proportional resistor R24 ​​at the non-inverting input, which are used to attenuate the positive feedback signal.

[0102] The first protection module 205 includes a first diode D1 and a second diode D2, which are used to provide a discharge path for the back electromotive force generated when the inductive load current changes suddenly.

[0103] The frequency compensation module 206 includes a frequency compensation resistor RC and a frequency compensation capacitor CC, which are used to provide frequency compensation for inductive loads and prevent self-oscillation.

[0104] The voltage expansion module 207 includes a third operational amplifier OP3, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10, which are used to double the voltage drive capability.

[0105] The second protection module 208 includes a third diode D3 and a fourth diode D4, and its function is the same as that of the first protection module 205.

[0106] The reference voltage source VR provides a reference voltage signal to the constant current source. Its positive terminal is connected to the positive common terminal P, and its negative terminal is connected to the negative common terminal N and ground.

[0107] One end of the negative feedback first proportional resistor R11 is connected to the inverting reference input terminal INN. The other end of the negative feedback first proportional resistor R11 is simultaneously connected to one end of the negative feedback second proportional resistor R12 and one end of the inverting terminal second proportional resistor R14. The other end of the inverting terminal second proportional resistor R14 is simultaneously connected to the inverting input terminal of the composite operational amplifier module 200 and one end of the inverting terminal first proportional resistor R13. The other end of the inverting terminal first proportional resistor R13 is grounded. The other end of the negative feedback second proportional resistor R12 is simultaneously connected to the output terminal of the composite operational amplifier module 200, the anode of the first diode D1, the cathode of the second diode D2, the voltage extension module input terminal IN2, and the upper end of the sampling resistor RS. The lower end of the sampling resistor RS is simultaneously connected to the upper end of the frequency compensation capacitor CC, the upper end of the load RL, and one end of the positive feedback second proportional resistor R22. The other end of the positive feedback second proportional resistor R22 is simultaneously connected to the positive feedback first... One end of the proportional resistor R21 is connected to one end of the non-inverting proportional resistor R24; the other end of the positive feedback first proportional resistor R21 is connected to the non-inverting reference input INP; the other end of the non-inverting second proportional resistor R24 ​​is simultaneously connected to the non-inverting input of the composite operational amplifier module 200 and one end of the non-inverting first proportional resistor R23, and the other end of the non-inverting first proportional resistor R23 is grounded; the lower end of the load RL is simultaneously connected to the lower end of the frequency compensation resistor RC and the output terminal OUT2 of the voltage extension module, and the upper end of the frequency compensation resistor RC is connected to the lower end of the frequency compensation capacitor CC; the output terminal OUT2 of the voltage extension module is simultaneously connected to the anode of the third diode D3 and the cathode of the fourth diode D4; the cathodes of the first diode D1 and the third diode D3 are connected to the positive power supply +VP; the anodes of the second diode D2 and the fourth diode D4 are connected to the negative power supply -VP; a load current IL flows through the load RL.

[0108] According to Figure 3 The circuit connection shown allows the load current IL and the reference voltage source VR to form both in-phase and out-of-phase output modes.

[0109] The specific connection method for the in-phase output mode is as follows: short-circuit the in-phase reference input terminal INP and the positive common terminal P, and simultaneously short-circuit the inverting reference input terminal INN and the negative common terminal N. At this time, the load current IL and the reference voltage source VR are in phase, and the expression for the load current IL is:

[0110]

[0111] The constraint condition for the above equation to hold is:

[0112] R11=R21, R12=R22, R13=R23, R14=R24.

[0113] The specific connection method for the inverting output mode is as follows: short-circuit the non-inverting reference input terminal INP and the negative common terminal N, and simultaneously short-circuit the inverting reference input terminal INN and the positive common terminal P. At this time, the load current IL and the reference voltage source VR are out of phase, and the expression for the load current IL is:

[0114]

[0115] The constraint condition for the above equation to hold is:

[0116]

[0117] To improve the accuracy of the output current, the above-mentioned negative feedback first proportional resistor R11, negative feedback second proportional resistor R12, positive feedback first proportional resistor R21, positive feedback second proportional resistor R22, inverting terminal first proportional resistor R13, inverting terminal second proportional resistor R14, non-inverting terminal first proportional resistor R23, non-inverting terminal second proportional resistor R24 ​​and sampling resistor RS are selected as high-precision resistors; the selection criteria for high-precision resistors are: initial accuracy ≤0.1%, temperature coefficient ≤10ppm / ℃.

[0118] Figure 3 In this module, the composite operational amplifier module 200 consists of a first operational amplifier OP1, a second operational amplifier OP2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The first operational amplifier OP1 is a precision operational amplifier used for precise error correction. The selection criteria for the precision operational amplifier are: open-loop gain ≥120dB, offset voltage temperature drift ≤1μV / ℃, and offset current temperature drift ≤50pA / ℃. The second operational amplifier OP2 and its external resistors R5, R6, and R7 form a non-inverting amplifier to amplify the output voltage of the precision operational amplifier in the first stage, thereby improving the voltage drive capability. The second operational amplifier OP2 is a power operational amplifier, used to provide the power required by the load, including current and voltage.

[0119] The gain of the non-inverting amplifier can be expressed as 1 + R6 / R5, where the values ​​of the fifth resistor R5 and the sixth resistor R6 are subject to the following constraints:

[0120]

[0121] In the formula, VOP is the maximum output voltage of the first operational amplifier OP1; VPA is the output voltage of the second operational amplifier OP2. Under the above constraints, the maximum output voltage of the composite operational amplifier module is determined by the power operational amplifier in the subsequent stage, and is not limited by the maximum output voltage of the precision operational amplifier in the preceding stage.

[0122] To minimize the impact of the power operational amplifier's bias current and its temperature drift on the accuracy of the output current, the value of the seventh resistor R7 should meet the following constraints:

[0123]

[0124] Compared with the prior art, the originality of this invention lies in the design of the inverting input proportional module 203 and the non-inverting input proportional module 204, which are used to attenuate the negative feedback signal and the positive feedback signal, respectively, to meet the common-mode voltage input range of the first operational amplifier OP1. To achieve the above objective, the values ​​of the first negative feedback proportional resistor R11, the second negative feedback proportional resistor R12, the first inverting input proportional resistor R13, and the second inverting input proportional resistor R14 should satisfy the following constraints:

[0125]

[0126] In the formula, Vn is the maximum common-mode voltage of the inverting input terminal of the first operational amplifier OP1, VPA is the output voltage of the second operational amplifier OP2, and VRN is the voltage signal of the inverting reference input terminal INN.

[0127] The values ​​of the first proportional resistor R21, the second proportional resistor R22, the first proportional resistor R23 at the non-inverting input, and the second proportional resistor R24 ​​at the non-inverting input should meet the following constraints:

[0128]

[0129] In the formula, Vp is the maximum common-mode voltage at the non-inverting input of the first operational amplifier OP1, VL is the voltage between the upper end of the load RL and ground, and VRP is the voltage signal at the non-inverting reference input INP.

[0130] like Figure 1 As shown, the voltage expansion module 207 consists of a third operational amplifier OP3, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10, forming an inverting amplifier. The third operational amplifier OP3 is of the same model and specifications as the second operational amplifier OP2. Since the output voltage OUT2 of this inverting amplifier is always equal in amplitude but opposite in phase to the output voltage VPA of the composite operational amplifier module 200, the driving voltage across the load RL can be doubled (the voltage across the sampling resistor RS is usually negligible). To achieve this, the gain of the inverting amplifier should satisfy -(R9 / R8) = -1. Furthermore, to maximize the gain accuracy of the inverting amplifier, the value of the tenth resistor R10 should meet the following constraints:

[0131]

[0132] Under the above constraints, the bias current and temperature drift of the third operational amplifier OP3 can be ignored.

[0133] From the expressions for the load current IL in the non-inverting and inverting output modes above, it can be seen that the voltage extension module does not participate in the current closed-loop control and is unrelated to the load current IL. Therefore, the external resistors R8-R10 of the third operational amplifier OP3 can be ordinary precision resistors, with the selection criteria being: initial accuracy ≤1% and temperature coefficient ≤100ppm / ℃.

[0134] To meet the supply voltage ranges of the precision operational amplifier and the power operational amplifier respectively, and to maximize the voltage drive capability of the constant current source, the first operational amplifier OP1 is powered by a positive signal power supply +VS and a negative signal power supply -VS, while the second operational amplifier OP2 and the third operational amplifier OP3 are powered by a positive power supply +VP and a negative power supply -VP. Compared with the prior art, the advantages of this invention are that the amplitude of the signal power supply can be less than or equal to the amplitude of the power supply, so that the output voltage range is no longer limited by the maximum supply range of the preceding precision operational amplifier. At the same time, a low-ripple power supply can be used for the signal power supply, further improving the error correction accuracy of the precision operational amplifier.

[0135] like Figure 3 As shown, the load RL can be a resistive load or an inductive load. For example, a voice coil motor is an inductive load, which can be equivalent to a resistor and an inductor connected in series.

[0136] When the load RL is inductive, the first protection module 205 and the second protection module 208 are essential to provide a discharge path for the back electromotive force generated by sudden changes in load current, thereby improving circuit reliability. The first diode D1, second diode D2, third diode D3, and fourth diode D4 constituting the above protection modules can be high-power Schottky diodes or high-power fast recovery diodes to improve discharge speed. The frequency compensation module 206 is used to compensate for the phase shift caused by the inductive load and prevent circuit self-oscillation. The compensation resistor RC has a value range of 2Ω ≤ RC ≤ 10Ω, and the compensation capacitor CC has a value range of 47nF ≤ CC ≤ 100nF.

[0137] like Figure 4 As shown, the schematic diagram of specific embodiment 2 provided by the present invention includes: a composite operational amplifier module 200, a negative feedback proportional module 201, a positive feedback proportional module 202, an inverting input proportional module 203, a non-inverting input proportional module 204, a first protection module 205, a frequency compensation module 206, a sampling resistor RS, a reference voltage source VR, and a load RL.

[0138] and Figure 1 In comparison, the main difference is, such as Figure 2 As shown, the voltage extension module and the second protection module are not included, and the lower end of the load RL is directly grounded. Apart from the differences mentioned above, Figure 2 and Figure 1 They are exactly the same, so I will not repeat myself.

[0139] because Figure 2 Excluding the voltage extension module, under the same device parameters, the output voltage range of Specific Embodiment 2 is about half that of Specific Embodiment 1, but is still much higher than the prior art.

[0140] In addition, it should be noted that, Figure 1 and Figure 2 Only the content directly related to this invention is given; other content that is necessary in practical applications but belongs to the publicly known technology is not given.

[0141] like Figure 5 , Figure 6 As shown, Figure 5 and Figure 6 The simulation results show the comparison between the present invention and the prior art. The key component parameters used in the simulation are as follows: RS = 0.2Ω, the offset voltage temperature drift of the precision operational amplifier is 0.2μV / ℃, the offset voltage temperature drift of the power operational amplifier is 40μV / ℃, the precision operational amplifier is powered by the maximum power supply voltage ±15V, and the power operational amplifier is powered by the maximum power supply voltage ±40V.

[0142] Figure 5 This is a comparison of the output voltage range of the present invention and existing technologies. The results show that... Figure 1 The maximum output voltage range of the prior art shown is approximately ±10.7V, while Figure 3 and Figure 4 The maximum output voltage range of the present invention reaches approximately ±71V and ±35.7V respectively, which is approximately 6.6 times that of the prior art, showing significant effect.

[0143] Figure 6 This section compares the impact of offset voltage variations on the accuracy of this invention and existing technologies. In practical applications, a 100°C temperature change corresponds to approximately 20μV and 4mV offset voltage changes for precision operational amplifiers and power operational amplifiers, respectively. Simulation results show that a 100°C temperature change... Figure 2 The output current variation of the prior art shown is approximately 22mA, while Figure 3 The output current variation of the present invention is only 0.5mA, and the accuracy is improved by more than 40 times, which is a significant effect.

[0144] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0145] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A high-precision wide-voltage constant current source suitable for voice coil motor drives on a three-dimensional platform, characterized in that: It includes a composite operational amplifier module, a negative feedback proportional module, a positive feedback proportional module, an inverting input proportional module, a non-inverting input proportional module, a first protection module, a frequency compensation module, a voltage extension module, a second protection module, a sampling resistor, a reference voltage source, and a load; The composite operational amplifier module corrects the error signals generated by the positive feedback proportional module and the negative feedback proportional module, and outputs the drive current and drive voltage to the load; the negative feedback proportional module is used to set the negative feedback coefficient and generate the negative feedback signal, and the positive feedback proportional module is used to set the positive feedback coefficient and generate the positive feedback signal. The inverting input proportional module is used to attenuate the negative feedback signal, and the non-inverting input proportional module is used to attenuate the positive feedback signal. The voltage extension module enhances the driving capability of the drive voltage output by the composite operational amplifier module; the first protection module provides a discharge path for the back electromotive force generated when the current of the load and sampling resistor changes suddenly; the frequency compensation module provides frequency compensation for the load to prevent self-oscillation. The second protection module provides a discharge path for the back electromotive force generated when the voltage extension module and the load experience sudden current changes; The load operates based on the received drive current and drive voltage; The reference voltage source provides a reference voltage signal for the wide voltage constant current source.

2. The high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 1, characterized in that: The negative feedback proportional module includes a first negative feedback proportional resistor R11 and a second negative feedback proportional resistor R12, which are connected in series; the positive feedback proportional module includes a first positive feedback proportional resistor R21 and a second positive feedback proportional resistor R22, which are connected in series. The inverting input proportional module includes a first proportional resistor R13 and a second proportional resistor R14 at the inverting input; the non-inverting input proportional module includes a first proportional resistor R23 and a second proportional resistor R24 ​​at the non-inverting input; the first protection module includes a first diode D1 and a second diode D2; and the frequency compensation module includes a frequency compensation resistor RC and a frequency compensation capacitor CC, wherein: One end of the negative feedback first proportional resistor R11 is connected to the inverting reference input terminal INN. The other end of the negative feedback first proportional resistor R11 is simultaneously connected to one end of the negative feedback second proportional resistor R12 and one end of the inverting terminal second proportional resistor R14. The other end of the inverting terminal second proportional resistor R14 is simultaneously connected to the inverting input terminal of the composite operational amplifier module and one end of the inverting terminal first proportional resistor R13. The other end of the inverting terminal first proportional resistor R13 is grounded. The other end of the negative feedback second proportional resistor R12 is simultaneously connected to the output terminal of the composite operational amplifier module, the anode of the first diode D1, the cathode of the second diode D2, and the upper end of the sampling resistor RS. The lower end of the sampling resistor RS is simultaneously connected to the frequency compensation resistor. The upper end of capacitor CC, the upper end of load RL, and one end of the positive feedback second proportional resistor R22 are connected; the other end of the positive feedback second proportional resistor R22 is simultaneously connected to one end of the positive feedback first proportional resistor R21 and one end of the non-inverting second proportional resistor R24; the other end of the positive feedback first proportional resistor R21 is connected to the non-inverting reference input INP; the other end of the non-inverting second proportional resistor R24 ​​is simultaneously connected to the non-inverting input of the composite operational amplifier module and one end of the non-inverting first proportional resistor R23, the other end of the non-inverting first proportional resistor R23 is grounded, the lower end of frequency compensation capacitor CC is connected to the upper end of frequency compensation resistor RC, and the lower end of frequency compensation resistor RC and the lower end of load RL are simultaneously grounded.

3. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 2, characterized in that: The composite operational amplifier module includes a first operational amplifier OP1, a second operational amplifier OP2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The first operational amplifier OP1 is used to achieve precision error correction. The second operational amplifier OP2 and its peripheral fifth resistor R5, sixth resistor R6, and seventh resistor R7 constitute a non-inverting amplifier, which is used to amplify the output voltage of the first operational amplifier OP1 to improve the voltage drive capability. The second operational amplifier, OP2, is a power operational amplifier used to provide the power required by the load, namely the drive current and drive voltage.

4. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 2, characterized in that: The voltage expansion module includes a third operational amplifier OP3, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10, which are arranged around the third operational amplifier OP3 to form an inverting amplifier. The third operational amplifier OP3 is the same model as the second operational amplifier OP2. The output voltage OUT2 of the inverting amplifier is equal in amplitude and opposite in phase to the output voltage VPA of the composite operational amplifier module.

5. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 2, characterized in that: The output modes of the motor drive current include in-phase output mode and out-of-phase output mode; The reference voltage source includes a positive common terminal P and a negative common terminal N. When the non-inverting reference input terminal INP and the positive common terminal P are shorted, and the inverting reference input terminal INN and the negative common terminal N are shorted at the same time, the output mode is the non-inverting output mode. When the non-inverting reference input terminal INP and the negative common terminal N are shorted, and the inverting reference input terminal INN and the positive common terminal P are shorted at the same time, the output mode is the inverting output mode.

6. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 5, characterized in that: In non-in-phase output mode, the load current IL and the reference voltage source VR are in phase, and the load current IL is: The constraints for the in-phase output mode are as follows: R11=R21, R12=R22, R13=R23, R14=R24 In inverted output mode, the load current IL and the reference voltage source VR are out of phase, and the load current IL is: The constraints for the inverted output mode are as follows: The negative feedback first proportional resistor R11, negative feedback second proportional resistor R12, positive feedback first proportional resistor R21, positive feedback second proportional resistor R22, inverting terminal first proportional resistor R13, inverting terminal second proportional resistor R14, non-inverting terminal first proportional resistor R23, non-inverting terminal second proportional resistor R24, and sampling resistor RS are all high-precision resistors. The selection criteria for high-precision resistors are: initial accuracy ≤ 0.1% and temperature coefficient ≤ 10ppm / ℃.

7. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 3, characterized in that: The gain of the non-inverting amplifier is 1 + R6 / R5, and the values ​​of the fifth resistor R5 and the sixth resistor R6 are subject to the following constraints: VPA·R5 ≤VOP R5+R6 In the formula, VOP is the maximum output voltage of the first operational amplifier OP1; VPA is the output voltage of the second operational amplifier OP2; under the constraints of the values ​​of the fifth resistor R5 and the sixth resistor R6, the maximum output voltage of the composite operational amplifier module is determined by the power operational amplifier in the subsequent stage and is not limited by the maximum output voltage of the precision operational amplifier in the preceding stage.

8. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 7, characterized in that: The constraint condition for the value of the seventh resistor R7 is: To reduce the impact of power operational amplifier bias current and temperature drift on the accuracy of the output current, the values ​​of the fifth resistor R5 and the sixth resistor R6 are determined based on the constraints.

9. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 6, characterized in that: The inverting input proportional module and the non-inverting input proportional module are used to attenuate the negative feedback signal and the positive feedback signal, respectively. The values ​​of the first negative feedback proportional resistor R11, the second negative feedback proportional resistor R12, the first inverting input proportional resistor R13, and the second inverting input proportional resistor R14 are subject to the following constraints: In the formula, Vn is the maximum common-mode voltage of the inverting input terminal of the first operational amplifier OP1, VPA is the output voltage of the second operational amplifier OP2, and VRN is the voltage signal of the inverting reference input terminal INN. The constraints for the values ​​of the first proportional resistor R21, the second proportional resistor R22, the first proportional resistor R23 at the non-inverting input, and the second proportional resistor R24 ​​at the non-inverting input are as follows: In the formula, Vp is the maximum common-mode voltage at the non-inverting input of the first operational amplifier OP1, VL is the voltage between the upper end of the load RL and ground, and VRP is the voltage signal at the non-inverting reference input INP.

10. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 4, characterized in that: The output voltage OUT2 of the inverting amplifier has the same amplitude and opposite phase to the output voltage VPA of the composite operational amplifier module. The driving voltage across the load RL is doubled, and the gain of the inverting amplifier satisfies -(R9 / R8) = -1. The value of the tenth resistor R10 satisfies the constraint condition. Under the constraint of the tenth resistor R10, the bias current and temperature drift of the third operational amplifier OP3 are ignored.

11. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 4, characterized in that: The voltage extension module does not participate in the current closed-loop control and is unrelated to the load current IL; the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 around the third operational amplifier OP3 are ordinary precision resistors, selected based on the following criteria: initial accuracy ≤1% and temperature coefficient ≤100ppm / ℃.

12. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 4, characterized in that: The load RL is selected as a resistive load or an inductive load. When the load RL is an inductive load, the first protection module and the second protection module are used to provide a discharge path for the back electromotive force generated by the sudden change in load current. The first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 are selected as high-power Schottky diodes or high-power fast recovery diodes to improve the discharge speed. The frequency compensation module is used to compensate for the phase shift caused by the inductive load and prevent the circuit from self-excited oscillation. The value range of the compensation resistor RC is 2Ω≤RC≤10Ω.

13. A high-precision wide-voltage constant current source suitable for voice coil motor driving on a three-dimensional platform according to claim 4, characterized in that: When the driving voltage across the load RL does not need to be doubled, the voltage expansion module and the second protection module are not configured, and the lower end of the load RL is directly grounded.

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