Electromagnetic clutch current closed-loop control circuit and method

Abstract

This invention belongs to the field of servo control technology, and specifically relates to an electromagnetic clutch current closed-loop control circuit and method. It includes: a voltage conversion circuit, a current sampling circuit, a current monitoring circuit, a coil control circuit, and a control module. The control module includes a current comparison module, a PI controller, and a PWM generation module. Both the current sampling circuit and the current monitoring circuit sequentially include a differential acquisition circuit and a low-pass filter. The input terminal of the voltage conversion circuit receives a variable DC voltage. By using PWM chopping control to control the switching transistor's on / off state, the output current is adjusted, simplifying operation and improving the overall adaptability of the circuit function.

Description

Technical Field

[0001] This invention belongs to the field of servo control technology, and in particular relates to an electromagnetic clutch current closed-loop control circuit and method. Background Technology

[0002] Electric servos used for aircraft control surface actuation are a key component of flight control systems, and their performance directly affects the operation of the entire system. With the development of flight control systems, the switching of electric servo operating modes requires the use of electromagnetic clutch state control. Therefore, electromagnetic clutch control involves mode switching within the flight control system, and the performance of the control circuit affects the safety of the system. Simultaneously, the aviation industry is moving towards lower costs and faster technological updates, and standardized and universal designs will significantly reduce design time. Traditional clutch control circuits have reset and holding power supplies, resulting in high hardware costs. Furthermore, the resistance of the clutch coil changes with temperature, altering the load current and necessitating a power supply system designed for maximum current, placing excessive demands on it. Moreover, different reset and holding voltages need to be designed for different clutch loads, leading to low design reusability and longer development and verification cycles. Summary of the Invention

[0003] Purpose of the invention: To propose a low-cost, high-efficiency, and high-reliability closed-loop control circuit and method for electromagnetic clutch current.

[0004] Technical solution:

[0005] An electromagnetic clutch current closed-loop control circuit includes: a voltage conversion circuit, a current sampling circuit, a current monitoring circuit, a coil control circuit, and a control module. The control module includes a current comparison module, a PI controller, and a PWM generation module. The current sampling circuit and the current monitoring circuit each include a differential acquisition circuit and a low-pass filter. The input terminal of the voltage conversion circuit receives a variable DC voltage.

[0006] The coil control circuit includes a first transistor 1, a sampling resistor 2, a clutch coil 3, a monitoring resistor 4, a second transistor 5, and a freewheeling diode 6. The gate of the first transistor 1 is connected to the first output terminal of the current comparison of the control module; the output terminal of the voltage conversion circuit is connected to the drain of the first transistor 1; one end of the sampling resistor 2 is connected to the source of the first transistor 1 and the positive differential input terminal of the current sampling circuit, and the other end of the sampling resistor 2 is connected to one end of the clutch coil 3, the negative terminal of the freewheeling diode 6, and the negative differential input terminal of the current sampling circuit; one end of the monitoring resistor 4 is connected to the other end of the clutch coil 3, the positive terminal of the freewheeling diode 6, and the positive differential input terminal of the current monitoring circuit, and the other end of the monitoring resistor 4 is connected to the drain of the second transistor 5 and the negative differential input terminal of the current monitoring circuit.

[0007] The source of the second transistor 5 is grounded; the gate of the second transistor 5 is connected to the output of the PWM generation module of the control module; the output of the current sampling circuit is connected to the first input of the current comparison module; the output of the current monitoring circuit is connected to the second input of the current comparison module; the third input of the current comparison module is used to receive the enable signal; the current command is input to the PI controller after the difference between the current command and the output of the current sampling circuit; the second output of the current comparison module is connected to the enable input of the PWM generation module.

[0008] Preferably, the voltage conversion circuit specifically uses a DC / DC module to convert the 18V~32V variable DC voltage input into a stable 28V DC voltage to supply the clutch coil.

[0009] Preferably, the first transistor 1 and the second transistor 5 are insulated-gate field-effect transistors.

[0010] Preferably, the low-pass filter is an active first-order low-pass filter.

[0011] Preferably, the period of the PWM wave generated by the PWM generation module is parameterized according to the resistance and inductance values ​​of the clutch coil 3.

[0012] Preferably, the differential acquisition circuit in the current sampling circuit is implemented using an operational amplifier with a common-mode rejection ratio greater than 50V.

[0013] Preferably, the current-carrying capacity of the freewheeling diode 6, the first transistor 1, and the second transistor 5 is greater than 1.5 times the maximum current of the clutch coil 3.

[0014] An electromagnetic clutch current closed-loop control method, the method being executed by means of the aforementioned electromagnetic clutch current closed-loop control circuit, the method comprising:

[0015] Step 1: The difference between the current command signal and the current signal output by the current sampling circuit is used for closed-loop control. The modulated PWM wave is output by the PI controller to drive the second transistor 5.

[0016] Step 2: The current comparison module determines whether to enable the output of the upper and lower transistor control signals based on whether the current values ​​fed back by the monitoring circuit and the current sampling circuit are equal.

[0017] The enable signal E of the current comparator module n It contains 0 and 1, corresponding to two working modes respectively. When E n =1 and the current comparison module outputs a normally open enable signal for the upper transistor based on the current values ​​fed back by the monitoring circuit and the current sampling circuit, which controls the first transistor 1 to be normally open; at the same time, it enables the PWM output to control the second transistor 5 to be turned on.

[0018] Dangdang E n =1 and the current comparison module's current values ​​fed back from the monitoring circuit and the current sampling circuit are not equal, or E n =0. At this time, the current comparison module outputs the upper transistor turn-off enable signal to control the first transistor 1 to turn off, and at the same time enables the PWM not to output to control the second transistor 5 to turn off.

[0019] Beneficial effects:

[0020] This invention presents a simplified and practical clutch current control circuit and current loop control method. It utilizes PWM chopper control to turn the switching transistor on and off, adjusting the output current. The operation is simple, and the overall adaptability of the circuit function is improved. A current monitoring circuit is included to effectively monitor for faults in the clutch current loop. The use of upper and lower transistor control ensures reliable loop shutdown and guarantees safety. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a connection diagram of the various circuit modules involved in the present invention;

[0023] Figure 2 This is a detailed schematic diagram of the clutch control circuit.

[0024] The components in the attached diagram are indicated by numbers:

[0025] 1-First transistor, 2-Sampling resistor, 3-Clutch coil, 4-Monitoring resistor, 5-Second transistor, 6-Freewheeling diode. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0028] This invention provides a clutch current control circuit and a current loop control method for detecting the real-time current of the clutch during operation, and simultaneously adjusting the feedback current in a closed loop to make it highly dynamically follow the system current setting without overshoot. The circuit includes: a voltage conversion circuit, a current sampling circuit, a control module, a coil control circuit, and a current monitoring circuit.

[0029] A clutch control circuit and a clutch current control method are proposed.

[0030] Firstly, an electromagnetic clutch current closed-loop control circuit is proposed, which is also the implementation platform for the current loop closed-loop control method of the present invention; the electromagnetic clutch current closed-loop control circuit includes a voltage conversion circuit, a current sampling circuit, a current monitoring circuit, a coil control circuit, and a control module.

[0031] The voltage conversion circuit uses a DC / DC (Direct Current / Direct Current) module to convert a variable DC input voltage of 18V to 32V into a stable 28V DC voltage to supply the clutch coil. This ensures that the output voltage remains stable when the external power supply varies from 18V to 32V.

[0032] The coil control circuit includes a first transistor 1, a sampling resistor 2, a clutch coil 3, a monitoring resistor 4, a second transistor 5, and a freewheeling diode 6.

[0033] Both the current sampling circuit and the monitoring circuit acquire voltage signals by dividing the voltage with a sampling resistor, and then send them to the processing circuit after filtering and amplification by an active first-order low-pass filter.

[0034] In this circuit, the gate of the first transistor 1 is connected to the first output terminal of the current comparison of the control module; the output terminal of the voltage conversion circuit is connected to the drain of the first transistor 1; one end of the sampling resistor 2 is connected to the source of the first transistor 1 and the positive differential input terminal of the current sampling circuit, and the other end of the sampling resistor 2 is connected to one end of the clutch coil 3, the negative terminal of the freewheeling diode 6, and the negative differential input terminal of the current sampling circuit; one end of the monitoring resistor 4 is connected to the other end of the clutch coil 3, the positive terminal of the freewheeling diode 6, and the positive differential input terminal of the current monitoring circuit, and the other end of the monitoring resistor 4 is connected to the drain of the second transistor 5 and the negative differential input terminal of the current monitoring circuit.

[0035] The source of the second transistor 5 is grounded; the gate of the second transistor 5 is connected to the output of the PWM generation module of the control module; the output of the current sampling circuit is connected to the first input of the current comparison module; the output of the current monitoring circuit is connected to the second input of the current comparison module; the third input of the current comparison module is used to receive the enable signal; the current command is input to the PI controller after the difference between the current command and the output of the current sampling circuit; the second output of the current comparison module is connected to the enable input of the PWM generation module.

[0036] The control module performs closed-loop control by subtracting the current command signal from the current actual feedback current signal. The modulated PWM (Pulse-Width Modulation) wave is output through the PI (Proportional Integral) controller to the MOSFET drive circuit, which ultimately realizes the PWM modulation control of the lower MOSFET of the coil control circuit, thereby controlling the magnitude of the current in the coil.

[0037] At the same time, the control module also outputs a series of upper tube control signals, which are amplified by the drive circuit and input to the upper tube of the clutch coil control circuit to prevent the clutch circuit from being accidentally grounded and to ensure that the clutch is effectively disengaged.

[0038] Meanwhile, the current comparison module determines whether to enable the output of the upper and lower transistor control signals based on whether the current values ​​fed back by the monitoring circuit and the current sampling circuit are equal.

[0039] Enable signal E n It contains 0 and 1, corresponding to two working modes respectively. When E n When E = 1, and the current comparison module provides the same current value as the monitoring circuit and the current sampling circuit, both the upper and lower transistors operate normally. The upper transistor is normally open for control, and the lower transistor is controlled via PWM output. n =1 and the current comparison module's current values ​​fed back from the monitoring circuit and the current sampling circuit are not equal, or E n =0, at this time the upper and lower transistors are not working, there is no PWM output, and the upper transistor is turned off.

[0040] The voltage conversion circuit is a DC / DC module, which converts a variable DC input voltage of 18V to 32V into 28V for use in subsequent circuits. The coil control circuit includes an insulated-gate field-effect transistor (IGFET) 1, a sampling resistor 2, a clutch coil 3, a sampling resistor 4, an IGFET 5, and a freewheeling diode 6. IGFETs 1 and 5 are switching transistors; when both are on, the clutch coil has current; when either is off, there is no current in the clutch. Using both transistors simultaneously prevents accidental grounding of the clutch coil circuit and ensures effective clutch disengagement. Resistor 2 is a sampling resistor, which collects the clutch coil current through a current sampling circuit for closed-loop control. Resistor 4 is a monitoring resistor, which collects the clutch coil current through a current monitoring circuit for monitoring by the control module. The current acquisition circuit and current monitoring circuit include a differential acquisition circuit and a low-pass filter. The differential acquisition circuit acquires the differential voltage across the sampling resistor, and the low-pass filter filters out high-frequency interference signals. Diode 6 is a freewheeling diode, which provides a freewheeling path for the clutch coil when the clutch circuit is off.

[0041] The core control function of this closed-loop control method is in the control module, which includes a PI controller used to process the current command I... cmd The difference between the measured current and the current sampled is used to output a modulated PWM signal via a PI controller, achieving closed-loop control of the coil current. Simultaneously, the control module integrates the enable signal E. n The current comparison result controls the switching on or off of transistors 1 and 5, implementing the logic as an enable signal E. n If either current comparison result is invalid, transistors 1 and 5 will be turned off simultaneously. The control module function can be implemented through processor software or programmable logic.

[0042] The principle behind the clutch current control method is as follows: the control module receives the clutch current command value, and uses a PI controller to implement closed-loop negative feedback control between the current command value and the actual current value of the clutch, thereby outputting a PWM wave to precisely control the circuit current. This method ensures that the current on the clutch load remains unaffected when the clutch coil resistance and inductance values ​​drift.

[0043] In a preferred embodiment, Figure 1 This is a block diagram of the clutch current control circuit according to an embodiment of the present invention.

[0044] like Figure 1 As shown in the block diagram of the clutch current control circuit of this embodiment of the invention, all arrows represented by solid lines represent the direction of current and power flow, i.e., electrical connection; all arrows represented by dashed lines represent the direction of signal flow, i.e. signal connection.

[0045] like Figure 1As shown, the externally supplied variable DC voltage input of 18V to 32V enters the coil control circuit after passing through a voltage conversion circuit. This voltage conversion circuit converts the 18V to 32V DC voltage into a stable 28V DC voltage. The current output from the coil control circuit is sampled by a current sampling circuit and a current monitoring circuit. The current value obtained by the current sampling circuit enters the control module, which then integrates the enable control signal E. n and current command I cmd The circuit outputs control signals for the upper MOSFET and PWM signals for the lower MOSFET. These control signals, through the MOSFET driver circuit, ultimately drive the MOSFETs in the coil control circuit. The coil current, collected by the current monitoring circuit, is used for real-time current monitoring.

[0046] Compared with current clutch control circuits, this invention has the following innovative features:

[0047] 1. The clutch coil current is controlled in a closed loop, and the current remains constant, unaffected by changes in the clutch coil resistance and inductance.

[0048] 2. The clutch current closed-loop feedback and current monitoring are designed separately, which can avoid the problem of not being able to effectively identify fault modes such as parameter deviation in the closed-loop control circuit, and improve the integrity of monitoring.

[0049] 3. The simultaneous disconnection of the upper and lower MOSFETs of the clutch coil can ensure the reliable shutdown of the current circuit and the reliable disengagement of the clutch.

[0050] 4. Compatible with GJB181B, meeting a wide range of DC voltage input from 18V to 32V;

[0051] 5. The PWM modulation control circuit is simple to design, small in size, light in weight, and has low power consumption.

[0052] The control module will adjust according to the reference current I. cmd The feedback current sampled by the current sampling circuit is processed and calculated to generate a PWM signal, which is then amplified by the drive circuit and enters the coil control circuit. The PWM signal input terminal of the drive circuit is connected to the signal output terminal of the processor circuit, and the signal input terminal of the coil control circuit is connected to the output terminal of the drive circuit.

[0053] At the same time, the control module responds to the enable signal E n The value of E is used to determine whether the upper MOSFET control signal enables output and whether the lower MOSFET outputs a PWM signal. n When E = 1, it means the upper MOSFET control signal is enabled. At this time, the upper MOSFET operates normally, and the lower MOSFET has PWM output; when E... nWhen the value is 0, it means the upper MOSFET control signal is disabled. In this case, the upper MOSFET does not work, and the lower MOSFET has no PWM output. The upper MOSFET control signal input terminal of the drive circuit is connected to the output terminal of the processor circuit, and the signal input terminal of the coil control circuit is connected to the output terminal of the drive circuit.

[0054] To further explain the working principle of this invention in detail, the following is combined with... Figure 2 Please provide an explanation.

[0055] like Figure 2 As shown, the voltage conversion circuit uses a DC / DC module to convert a variable DC voltage input of 18V to 32V into a stable 28V DC voltage to supply the clutch coil. The positive terminal of the 18V to 32V DC voltage input is connected to the voltage input terminal of the DC / DC module, and the negative terminal is grounded. The voltage output terminal of the DC / DC module is connected to the coil control circuit.

[0056] The coil control circuit consists of clutch coil 3, high-side sampling resistor 2, low-side sampling resistor 4, high-side switching MOSFET 1, low-side switching MOSFET 5, and freewheeling diode 6. High-side sampling resistor 2 collects the current of the clutch coil control circuit for closed-loop control. Low-side resistor 4 collects the clutch coil current for current monitoring. When the clutch coil needs to be turned off, high-side switching MOSFET 1 and low-side switching MOSFET 5 are turned off simultaneously to ensure reliable shutdown of the clutch control circuit.

[0057] The high end of the clutch coil 3 is sequentially connected to the high end sampling resistor 2 and the high end switching MOSFET 1, and the low end of the clutch coil 3 is sequentially connected to the low end sampling resistor 4 and the low end switching MOSFET 5 to form a current loop. The freewheeling diode 6 is connected in parallel with the clutch coil to form a freewheeling loop.

[0058] The current sampling circuit includes sampling resistor 2, a differential acquisition circuit, and a low-pass filter; the current monitoring circuit includes monitoring resistor 4, a differential acquisition circuit, and a low-pass filter. Both the current sampling circuit and the monitoring circuit acquire voltage signals through voltage division using sampling resistors, and then send them to the control module after filtering and amplification by an active first-order low-pass filter.

[0059] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A closed-loop control circuit for electromagnetic clutch current, characterized in that, include: The circuit includes a voltage conversion circuit, a current sampling circuit, a current monitoring circuit, a coil control circuit, and a control module. The control module includes a current comparison module, a PI controller, and a PWM generation module. Both the current sampling circuit and the current monitoring circuit include a differential acquisition circuit and a low-pass filter, respectively. The input terminal of the voltage conversion circuit receives a variable DC voltage. The coil control circuit includes a first transistor (1), a sampling resistor (2), a clutch coil (3), a monitoring resistor (4), a second transistor (5), and a freewheeling diode (6). The gate of the first transistor (1) is connected to the first output terminal of the current comparison of the control module; the output terminal of the voltage conversion circuit is connected to the drain of the first transistor (1); one end of the sampling resistor (2) is connected to the source of the first transistor (1) and the positive differential input terminal of the current sampling circuit, and the other end of the sampling resistor (2) is connected to one end of the clutch coil (3), the negative terminal of the freewheeling diode (6), and the negative differential input terminal of the current sampling circuit; one end of the monitoring resistor (4) is connected to the other end of the clutch coil (3), the positive terminal of the freewheeling diode (6), and the positive differential input terminal of the current monitoring circuit, and the other end of the monitoring resistor (4) is connected to the drain of the second transistor (5) and the negative differential input terminal of the current monitoring circuit. The source of the second transistor (5) is grounded; the gate of the second transistor (5) is connected to the output of the PWM generation module of the control module; the output of the current sampling circuit is connected to the first input of the current comparison module; the output of the current monitoring circuit is connected to the second input of the current comparison module; the third input of the current comparison module is used to receive the enable signal; the current command is input to the PI controller after the difference between the current command and the output of the current sampling circuit; the second output of the current comparison module is connected to the enable input of the PWM generation module.

2. The circuit according to claim 1, characterized in that, The voltage conversion circuit specifically uses a DC / DC module to convert the 18V~32V variable DC voltage input into a stable 28V DC voltage to supply the clutch coil.

3. The circuit according to claim 1, characterized in that, The first transistor (1) and the second transistor (5) are insulated gate field-effect transistors.

4. The circuit according to claim 1, characterized in that, The low-pass filter is an active first-order low-pass filter.

5. The circuit according to claim 1, characterized in that, The period of the PWM wave generated by the PWM generation module is parameterized according to the resistance and inductance values ​​of the clutch coil (3).

6. The circuit according to claim 1, characterized in that, The differential acquisition circuit in the current sampling circuit is implemented using an operational amplifier with a common-mode rejection ratio greater than 50V.

7. The circuit according to claim 1, characterized in that, The current carrying capacity of the freewheeling diode (6), the first transistor (1), and the second transistor (5) is greater than 1.5 times the maximum current of the clutch coil (3).

8. A closed-loop control method for electromagnetic clutch current, characterized in that, The method is executed by means of the electromagnetic clutch current closed-loop control circuit according to any one of claims 1-7, and the method includes: Step 1: The current command signal and the current signal output by the current sampling circuit are subtracted to perform closed-loop control. The modulated PWM wave is output by the PI controller to drive the second transistor (5). Step 2: The current comparison module determines whether to enable the output of the upper and lower transistor control signals based on whether the current values ​​fed back by the monitoring circuit and the current sampling circuit are equal. The enable signal E of the current comparator module n It contains 0 and 1, corresponding to two working modes respectively. When E n =1 and the current comparison module outputs the normally open enable signal of the upper transistor according to the current value fed back by the monitoring circuit and the current sampling circuit, which controls the first transistor (1) to be normally open; at the same time, it enables the PWM output to control the second transistor (5) to be turned on; Dangdang E n =1 and the current comparison module's current values ​​fed back from the monitoring circuit and the current sampling circuit are not equal, or E n =0. At this time, the current comparison module outputs the upper transistor turn-off enable signal to control the first transistor (1) to turn off, and at the same time enables the PWM not to output to control the second transistor (5) to turn off.

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