Coil current control device and method and magnetic suspension system

Abstract

The invention relates to a coil current control device and method and a magnetic suspension system. The device comprises a current adjusting circuit which is used for adjusting the magnitude and the direction of current flowing through a coil to be controlled. And a sampling module. The voltage dividing module is connected with the coil to be controlled in series and connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm in series, and the voltage drop of the two ends of the voltage dividing module is preset voltage; the control module is connected with the control end of the current adjusting circuit and the two ends of the sampling module and used for obtaining the sampling voltage of the two ends of the sampling module and controlling the working state of the current adjusting circuit according to the sampling voltage and the target current of the coil to be controlled so as to adjust the current of the coil to be controlled to the target current, the adjustable range of the current value on the coil to be controlled is related to the preset voltage. And the current on the coil can be conveniently and more accurately controlled.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a coil current control device and method, and a magnetic levitation system. Background Technology

[0002] With the development of science and technology, many systems or devices have emerged that utilize the magnetic force generated by magnetic fields as their principle. For example, the magnetically levitated artificial heart uses the magnetic force generated by the magnetic field to enable it to levitate and rotate, thus having the advantages of requiring less mechanical support, no lubrication, and no friction, and is widely used. Devices like these that utilize magnetic force all involve the control of magnetic force, which essentially involves controlling the current and direction of the coil.

[0003] In traditional technology, coil control circuits, such as H-bridge circuits, are used to control the current and direction of the coil.

[0004] However, the coil control circuit in traditional technology is not precise enough in controlling the coil current. Summary of the Invention

[0005] Therefore, it is necessary to provide a coil current control device and method, and a magnetic levitation system that can more accurately control the coil current, in order to address the above-mentioned technical problems.

[0006] In a first aspect, this application provides a coil current control device, comprising:

[0007] A current regulating circuit includes a first bridge arm and a second bridge arm. The first end of the first bridge arm and the first end of the second bridge arm are connected and receive a power signal. The second end of the first bridge arm and the second end of the second bridge arm are connected and grounded. A coil to be controlled is connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm. The current regulating circuit is used to regulate the magnitude and direction of the current flowing through the coil to be controlled.

[0008] A sampling module is connected in series with the coil to be controlled, and is connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm;

[0009] A voltage divider module is connected in series with the coil to be controlled, and is connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm, wherein the voltage drop across the voltage divider module is a preset voltage;

[0010] A control module is connected to the control terminal of the current regulation circuit and both ends of the sampling module, respectively. It is used to acquire the sampling voltage at both ends of the sampling module, and control the working state of the current regulation circuit according to the sampling voltage and the target current of the coil to be controlled so as to adjust the current of the coil to be controlled to the target current. The adjustable range of the current value on the coil to be controlled is related to the preset voltage.

[0011] In one embodiment, the voltage divider module includes a first diode and a second diode, wherein the anode of the first diode is connected to the cathode of the second diode as a first terminal of the voltage divider module, and the cathode of the first diode is connected to the anode of the second diode as a second terminal of the voltage divider module.

[0012] In one embodiment, the voltage divider module includes: a variable resistor unit;

[0013] The control module is connected to the variable resistor unit and is used to dynamically adjust the resistance value of the variable resistor unit during the process of adjusting the current value on the coil to be controlled, so that the voltage drop across the variable resistor unit is the preset voltage.

[0014] In one embodiment, the coil current control device further includes a short-circuit module connected in parallel with the voltage divider module, used to short-circuit the two ends of the voltage divider module when it is turned on, so that the voltage drop across the voltage divider module is zero.

[0015] In one embodiment, the control module includes:

[0016] A current sensing amplifier is connected to both ends of the sampling module to obtain the sampling voltage value at both ends of the sampling module, determine the actual current value on the sampling module based on the sampling voltage value at both ends of the sampling module, and amplify and output the actual current value.

[0017] A controller, connected to the current sensing amplifier, is used to acquire the actual current value and the target current value, and output a control signal based on the deviation between the actual current value and the target current value;

[0018] A driving unit, connected to the controller, is used to output a corresponding driving signal to the control terminal of the current regulating circuit according to the control signal to control the working state of the current regulating circuit, so as to regulate the current value on the coil to be controlled.

[0019] In one embodiment, the control module further includes: an amplifier, a first voltage divider resistor, and a second voltage divider resistor. The first terminal of the first voltage divider resistor is connected to a power supply signal. The second terminal of the first voltage divider resistor is connected to the first terminal of the second voltage divider resistor and the positive input terminal of the amplifier, respectively. The second terminal of the second voltage divider resistor is grounded. The output terminal of the amplifier is connected to the current sensing amplifier and the negative input terminal of the amplifier, respectively.

[0020] In one embodiment, the current sensing amplifier includes a first input terminal, a second input terminal, an output terminal, and a reference terminal. The first input terminal and the second input terminal are respectively connected to the two ends of the sampling module. The output terminal is connected to the controller, and the reference terminal is connected to the output terminal of the amplifier. The current sensing amplifier is used to receive a reference potential input from the reference terminal; to increase or decrease the amplitude of the sampling voltage value based on the reference potential to obtain a calculated voltage value; and to determine the actual current value on the sampling module based on the calculated voltage value and the resistance value of the sampling module.

[0021] In one embodiment, the first voltage divider resistor is equal to the second voltage divider resistor.

[0022] In one embodiment, the first bridge arm includes a first transistor and a second transistor, the first end of the first transistor serves as the first end of the first bridge arm, the second end of the first transistor and the first end of the second transistor are connected as the midpoint of the first bridge arm, and the second end of the second transistor serves as the second end of the first bridge arm.

[0023] The second bridge arm includes a third transistor and a fourth transistor. The first end of the third transistor serves as the first end of the second bridge arm. The second end of the third transistor and the first end of the fourth transistor are connected to form the midpoint of the second bridge arm. The second end of the fourth transistor serves as the second end of the second bridge arm.

[0024] The control module is connected to the control terminals of the first transistor, the second transistor, the third transistor, and the fourth transistor respectively, and is used to control the conduction state of the first transistor, the second transistor, the third transistor, and the fourth transistor respectively, so as to control the working state of the current regulation circuit.

[0025] Secondly, this application also provides a magnetic levitation system, comprising:

[0026] A housing having an internal cavity for receiving space;

[0027] An impeller assembly includes a rotor and a stator, the rotor including a permanent magnet and the stator including a levitation coil for generating a magnetic field to drive the permanent magnet to levitate within the receiving cavity;

[0028] The sensor module is used to collect the actual distance data between the rotor and the housing;

[0029] In the aforementioned coil current control device, the suspended coil serves as the coil to be controlled.

[0030] The control module is connected to the sensor module and is used to determine the target current value based on the actual distance data and the target distance data.

[0031] The aforementioned coil current control device and method, and magnetic levitation system. This device, by incorporating a current regulation circuit, can adjust the magnitude and direction of the current in the coil to be controlled. A sampling module is connected in series with the coil to be controlled, ensuring that the current value of the sampling module is consistent with that of the coil. This allows for complete sampling of the current flowing through the coil at various times, resulting in a more complete and accurate current value, facilitating subsequent feedback adjustment. A voltage divider module, also connected in series with the coil to be controlled, with a preset voltage drop across its terminals, reduces the voltage on the coil to be controlled, thereby reducing the current in the coil. This means that even with a constant output current from the current regulation circuit, the voltage divider module can lower the current in the coil, thus widening the adjustable range of the current value. The adjustable lower limit of the current value is lower, which is beneficial for precise adjustment of the current in the coil. By setting the control module, the sampling voltage across the sampling module can be obtained. Based on the sampling voltage and the target current of the coil to be controlled, the operating state of the current regulation circuit is controlled to adjust the current of the coil to the target current. This achieves feedback regulation of the current on the coil to be controlled, allowing the current on the coil to be adjusted to the target current. Furthermore, due to the effect of the voltage divider module, the adjustable range of the current value on the coil to be controlled is larger. Since the voltage drop across the voltage divider module is a preset voltage, the control module does not need to consider the influence of the voltage divider module's voltage on the current magnitude when adjusting the current on the coil to be controlled. Therefore, the control module can more conveniently control the current on the coil to be controlled. In summary, the device of this application can conveniently and more accurately control the current on the coil. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the circuit structure of the related technology in one embodiment;

[0034] Figure 2 This is a schematic diagram of the control flow of related technologies in one embodiment;

[0035] Figure 3 This is a waveform diagram of a signal sampled in a related technology in one embodiment;

[0036] Figure 4 This is a waveform diagram of a signal sampled in a related art in another embodiment;

[0037] Figure 5 This is a structural diagram of the coil current control device in one embodiment;

[0038] Figure 6 This is a second structural diagram of the coil current control device in one embodiment;

[0039] Figure 7 This is the third structural diagram of the coil current control device in one embodiment;

[0040] Figure 8 This is the fourth structural diagram of the coil current control device in one embodiment;

[0041] Figure 9 This is a waveform diagram comparing different sampling methods in one embodiment;

[0042] Figure 10 This is the fifth structural diagram of the coil current control device in one embodiment;

[0043] Figure 11 This is the sixth structural diagram of the coil current control device in one embodiment;

[0044] Figure 12 This is a structural diagram of a magnetic levitation system in one embodiment.

[0045] Explanation of reference numerals in the attached figures:

[0046] 10-Current regulation circuit, 11-First bridge arm, 12-Second bridge arm, 20-Sampling module, 30-Voltage divider module, 31-Variable resistor unit, 40-Control module, 41-Current detection amplifier, 42-Controller, 43-Drive unit, 80-Short-circuit module, 50-Housing, 61-Rotor, 62-Stator, 70-Sensor module. Detailed Implementation

[0047] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0049] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

[0050] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0051] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. Furthermore, in the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if there is transmission of electrical signals or data between the connected objects.

[0052] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0053] As described in the background section, existing coil control circuits suffer from insufficient precision in controlling the coil current. The inventors have discovered that the root cause of this problem lies in the fact that existing coil control circuits, such as... Figure 1 As shown, the design uses four transistors (Q1~Q4) to form an H-bridge circuit. The coil L1 to be controlled is connected in series between the midpoints of the two arms of the H-bridge circuit. One end of the sampling resistor R1 is connected to the H-bridge circuit, and the other end is connected to GND. The working process of this prior art circuit is explained as follows: When a current from left to right is required to input to L1 as shown in the figure, in the first stage, transistors Q1 and Q4 are turned on, while Q2 and Q3 are turned off. The H-bridge circuit energizes the coil L1, forming the current I1 shown in the figure. In the second stage, Q1 and Q2 are turned off, while Q3 and Q4 are turned on, forming the current I2. The coil L1 enters the freewheeling stage. It can be seen that only the current I1 flows through the sampling resistor R1, while the current I2 does not flow through the sampling resistor R1 during the freewheeling stage. Therefore, the sampling resistor R1 cannot sample the current I2 flowing through the coil L1 during the freewheeling stage, resulting in incomplete and inaccurate sampling results. Furthermore, the magnitude of the current is determined by the duty cycle of the PWM (Pulse Width Modulation) signal received at the control terminals of the transistors (Q1~Q4). The direction of the current is adjusted by controlling the appropriate on / off states of the transistors (Q1~Q4).

[0054] And reference Figure 2 The control flow shown involves the controlled variable (current) being sampled and sent to a comparator. The sampled current value is compared with the target current value, and a deviation value is output. The processor then outputs a control quantity (e.g., PWM duty cycle) based on the deviation value. Specifically, when the sampled value is smaller than the target current value, the processor increases the output of the control quantity (PWM duty cycle) to increase the controlled variable (current). When the sampled current value is larger than the target value, the processor decreases the output of the PWM duty cycle to decrease the current of the controlled object. It can be seen that the accuracy of the processor's control over the controlled object depends on the accuracy of the sampled current value. As discussed above, the coil control circuit in related technologies obtains incomplete and inaccurate sampled current values, leading to insufficient precision in the control of the coil current.

[0055] The inventors also discovered that, due to the inherent characteristics of the inductor, the current value on the coil L1 to be controlled is not a rectangular wave within a PWM cycle (e.g., including the first and second stages mentioned above). Figure 3 The voltage value across the sampling resistor R1 is obtained when the PWM duty cycle is 10%. Practice has shown that using the current sampling value at this moment as the current value in a single PWM cycle has high accuracy. Figure 4 When the PWM duty cycle is 5%, the voltage value across the sampling resistor R1 within one PWM cycle is insufficient to accurately reflect the current value across the coil L1 within that cycle. The inventors discovered that when the PWM duty cycle is too small, the waveform is submerged in measurement noise, making accurate measurement impossible. In other words, when the PWM duty cycle is too small, the detected output current value of the H-bridge circuit may be inaccurate, or even detected as having no current output. Therefore, the PWM duty cycle cannot be too small, which also prevents the current value across the coil L1 from reaching a smaller value.

[0056] Based on the above reasons, the present invention provides a coil current control device and method. By setting a voltage divider module, the current on the coil to be controlled can be lower while keeping the PWM duty cycle constant, thereby widening the adjustable range of the current value on the coil to be controlled. On the one hand, the PWM duty cycle is guaranteed, so that the current value output by the current regulation circuit is accurate. On the other hand, the current value on the coil to be controlled can be smaller, and the adjustable lower limit becomes lower, which is beneficial for precise adjustment of the current on the coil to be controlled.

[0057] In one embodiment, such as Figure 5 As shown, a coil current control device is provided, including: a current regulating circuit 10, a sampling module 20, a voltage divider module 30, and a control module 40, wherein.

[0058] The current regulating circuit 10 includes a first bridge arm 11 and a second bridge arm 12. The first end of the first bridge arm 11 and the first end of the second bridge arm 12 are connected to receive a power signal. The second end of the first bridge arm 11 and the second end of the second bridge arm 12 are connected to ground. The control coil is connected in series between the midpoint of the first bridge arm 11 and the midpoint of the second bridge arm 12. The current regulating circuit 10 is used to regulate the magnitude and direction of the current flowing through the control coil.

[0059] The current regulation circuit 10 can be an H-bridge circuit, which can be referenced from [reference needed]. Figure 1 The circuit structure of the related technology shown can adjust the magnitude and direction of the current flowing through the coil to be controlled. The principle has been explained above and will not be repeated here.

[0060] The sampling module 20 is connected in series with the coil L0 to be controlled, and the two are connected in series between the midpoint of the first bridge arm 11 and the midpoint of the second bridge arm 12.

[0061] The sampling module 20 can be a sampling resistor. The sampling module 20 is connected in series with the coil L0 to be controlled, so that the current value of the sampling module 20 and the current value of the coil L0 to be controlled are always consistent. It can completely sample the current value flowing through the coil L0 at each moment and obtain a complete and accurate current value.

[0062] The voltage divider module 30 is connected in series with the coil L0 to be controlled, and the two are connected in series between the midpoint of the first bridge arm 11 and the midpoint of the second bridge arm 12.

[0063] The voltage drop across the voltage divider module 30 is a preset voltage. The voltage divider module 30 diverts a portion of the voltage, thereby reducing the voltage across the controlled coil L0 and consequently reducing the current in L0. Furthermore, since the voltage divider module 30 operates on a constant voltage, it is unaffected by the current magnitude, facilitating the subsequent current calculation by the control module 40 based on the sampled voltage across the sampling module 20. The preset voltage can be either constant or variable. When the preset voltage is constant, subsequent calculations are more convenient; regardless of the current value, only the constant voltage needs to be substituted into the calculation, without needing to consider the impact of current variations on the preset voltage. When the preset voltage is variable, it can change dynamically. For smaller currents, the preset voltage can be set even smaller, reducing the voltage division by the voltage divider module 30, resulting in a larger sampled voltage. Based on this larger sampled voltage, the control module 40 can calculate a more accurate current. When the current is large, the preset voltage can be zero. Since the current is large, the sampling voltage is also large. The current calculated by the control module 40 based on the sampling voltage is accurate enough. There is no need for the voltage divider module to divide the voltage, which can save energy.

[0064] The control module 40 is connected to the control terminal of the current regulation circuit 10 and the two ends of the sampling module 20, respectively. It is used to obtain the sampling voltage at the two ends of the sampling module 20, and control the working state of the current regulation circuit 10 according to the sampling voltage and the target current of the coil L0 to be controlled so as to adjust the current of the coil L0 to be controlled to the target current.

[0065] The adjustable range of the current value on the coil L0 to be controlled is related to the preset voltage.

[0066] In this embodiment, the device, by setting a current adjustment circuit 10, can adjust the magnitude and direction of the current in the control coil L0. A sampling module 20 is connected in series with the control coil L0, ensuring that the sampling module 20 and the current value in the control coil L0 are consistent. This allows for complete sampling of the current flowing through the control coil L0 at various times, resulting in a more complete and accurate current value, facilitating subsequent feedback adjustment. A voltage divider module 30, also connected in series with the control coil L0, has a preset voltage drop across it, reducing the voltage in the control coil L0 and consequently reducing the current in the control coil L0. This means that while the output current of the current adjustment circuit 10 remains constant, the voltage divider module 30 can lower the current in the control coil L0, thus widening the adjustable range of the current value in the control coil L0. This allows for a smaller current value and a lower adjustable lower limit, facilitating precise adjustment of the current in the control coil L0, especially for minute currents. By setting the control module 40 to acquire the sampling voltage across the sampling module 20, and based on the sampling voltage and the target current of the coil L0 to be controlled, controlling the operating state of the current regulating circuit 10 to adjust the current of the coil L0 to the target current, feedback regulation of the current on the coil L0 is achieved, enabling the current on the coil L0 to be adjusted to the target current. Furthermore, due to the effect of the voltage divider module 30, the adjustable range of the current value on the coil L0 is larger, and the voltage drop across the voltage divider module 30 is a preset voltage. Therefore, when adjusting the current on the coil L0, the control module 40 does not need to consider the influence of the voltage divider module 30 on the current magnitude, making the control of the current on the coil L0 more convenient. In summary, the device of this application can conveniently and more accurately control the current on the coil.

[0067] In one embodiment, please see [link to previous article]. Figure 5 The first bridge arm 11 includes a first transistor Q1 and a second transistor Q2, and the second bridge arm 12 includes a third transistor Q3 and a fourth transistor Q4, wherein:

[0068] The first terminal of the first transistor Q1 serves as the first terminal of the first bridge arm 11, the second terminal of the first transistor Q1 is connected to the first terminal of the second transistor Q2 as the midpoint of the first bridge arm 11, and the second terminal of the second transistor Q2 serves as the second terminal of the first bridge arm 11.

[0069] The first end of the third transistor Q3 serves as the first end of the second bridge arm 12. The second end of the third transistor Q3 and the first end of the fourth transistor Q4 are connected to form the midpoint of the second bridge arm 12. The second end of the fourth transistor Q4 serves as the second end of the second bridge arm 12.

[0070] The first transistor Q1, the second transistor Q2, the third transistor Q3, and the fourth transistor Q4 constitute an H-bridge circuit.

[0071] The control module 40 is connected to the control terminals of the first transistor Q1, the second transistor Q2, the third transistor Q3, and the fourth transistor Q4, respectively, and is used to control the conduction state of the first transistor Q1, the second transistor Q2, the third transistor Q3, and the fourth transistor Q4, so as to control the working state of the current regulating circuit 10.

[0072] The control module 40 can control the first transistor Q1 and the fourth transistor Q4 to be turned on, while the second transistor Q2 and the third transistor Q3 are turned off, so that the current direction in the controlled coil L0 is in the first direction, and the controlled coil L0 is in the energized stage. Then, the control module 40 can control the first transistor Q1 and the second transistor Q2 to be turned off, while the third transistor Q3 and the fourth transistor Q4 are turned on, and the controlled coil L0 enters the freewheeling stage. Alternatively, the control module 40 can control the first transistor Q1 and the fourth transistor Q4 to be turned off, while the second transistor Q2 and the third transistor Q3 are turned on, so that the current direction in the controlled coil L0 is in the second direction, and the controlled coil L0 is in the energized stage, with the first and second directions opposite. Then, the control module 40 can control the first transistor Q1 and the second transistor Q2 to be turned on, while the third transistor Q3 and the fourth transistor Q4 are turned off, and the controlled coil L0 enters the freewheeling stage. The control module 40 can also adjust the duty cycle of the turned-on transistors, thereby adjusting the magnitude of the current flowing through the controlled coil L0.

[0073] Since the sampling module 20 is connected in series with the coil L0 to be controlled, the sampling module 20 can sample the current value on the coil L0 to be controlled in any of the above transistors in the conducting state (including the energizing stage and the freewheeling stage). Furthermore, due to the characteristics of the inductor, the current is stable and not easily disturbed during the freewheeling discharge process after the inductor stores energy, so the sampling module 20 can sample a more accurate current value.

[0074] In this embodiment, by setting four transistors to form an H-bridge circuit, it is possible to control the magnitude and direction of the current in the coil L0 to be controlled.

[0075] In one embodiment, such as Figure 6 As shown, the voltage divider module 30 includes a first diode D1 and a second diode D2. The positive terminal of the first diode D1 is connected to the negative terminal of the second diode D2 as the first terminal of the voltage divider module 30, and the negative terminal of the first diode D1 is connected to the positive terminal of the second diode D2 as the second terminal of the voltage divider module 30.

[0076] In this configuration, the first diode D1 and the second diode D2 are connected in parallel in reverse. When the current flowing through the controlled coil L0 is in the first direction, the first diode D1 conducts while the second diode D2 is reverse-biased and cut off, resulting in voltage division by the first diode D1. When the current flowing through the controlled coil L0 is in the second direction, the second diode D2 conducts while the first diode D1 is reverse-biased and cut off, again resulting in voltage division by the second diode D2. The first and second directions are opposite. Utilizing the clamping effect of the diodes, when a diode is turned on, the voltage across it is limited to its diode voltage drop, thus achieving a constant voltage division effect.

[0077] In this embodiment, by setting the first diode D1 and the second diode D2 to form a voltage divider module 30, a constant voltage division can be performed, which can reduce the voltage on the coil L0 to be controlled, thereby reducing the current on the coil L0 to be controlled. Moreover, since the voltage divider module 30 performs a constant voltage division, it is not affected by the magnitude of the current, which makes it easier for the subsequent control module 40 to calculate the current based on the sampling voltage across the sampling module 20.

[0078] In one embodiment, such as Figure 7 As shown, the voltage divider module includes a variable resistor unit 31. The control module 40 is connected to the variable resistor unit 31 and is used to dynamically adjust the resistance value of the variable resistor unit 31 during the process of adjusting the current value on the coil L0 to be controlled, so that the voltage drop across the variable resistor unit 31 is a preset voltage.

[0079] The resistance value of the variable resistor unit 31 can be adjusted arbitrarily. The control module 40 is connected to the variable resistor unit 31. The control module 40 can dynamically adjust the resistance value of the variable resistor unit 31 according to the magnitude of the current output by the current regulating circuit 10, so that the voltage drop across the variable resistor unit 31 remains constant regardless of the magnitude of the current output by the current regulating circuit 10. This facilitates the subsequent calculation of the sampled current value. The resistance value of the variable resistor unit 31 can also be adjusted as needed, without limitation.

[0080] In this embodiment, by including a variable resistor unit in the voltage divider module, a constant voltage divider effect can be achieved.

[0081] In one embodiment, such as Figure 8 As shown, the control module includes: a current detection amplifier 41, a controller 42, and a drive unit 43, wherein:

[0082] The current sensing amplifier 41 is connected to both ends of the sampling module 20 to obtain the sampling voltage value at both ends of the sampling module 20. Based on the sampling voltage value at both ends of the sampling module 20, the actual current value on the sampling module 20 is determined, and the actual current value is amplified and output.

[0083] The current sensing amplifier 41 can be a high common-mode input, bidirectional precision current sensing amplifier 41. It can be implemented using the INA190 chip. Its positive input pin IN+ and negative input pin IN- are connected to the two ends of the sampling module 20, respectively. Its power supply pin VS is connected to the power supply signal VCC, its ground pin GND is grounded, and its REF pin is connected to the reference potential Vref.

[0084] The controller 42 is connected to the current sensing amplifier 41 and is used to acquire the actual current value and the target current value. Based on the deviation between the actual current value and the target current value, the controller outputs a control signal.

[0085] The control logic executed by controller 42 can be referenced from Figure 2 As shown. Controller 42 can achieve the following: Figure 2 In addition to the steps performed by the comparative element, processor and other functional components shown, the controller 42 can also perform current sampling processing. The controller 42 includes an analog-to-digital converter (A / D) and a control signal transmission component (PWM).

[0086] The drive unit 43 is connected to the controller 42 and is used to output a corresponding drive signal to the control terminal of the current regulation circuit 10 according to the control signal to control the working state of the current regulation circuit 10, so as to adjust the current value on the coil L0 to be controlled.

[0087] The driving unit 43 can be a PWM signal generator, which can receive control signals, output PWM signals to the transistors corresponding to the current regulation circuit 10 according to the control signals, control the corresponding transistors to turn on or off, and adjust the duty cycle of the output PWM signal.

[0088] The inventors discovered that if the duty cycle of the PWM signal output by the driving unit 43 to the transistor corresponding to the current regulation circuit 10 is too small, the current value output by the current regulation circuit 10 will be inaccurate. For example, refer to... Figure 9 , Figure 9 The waveforms of the current values ​​on the controlled coil L0 are obtained through different methods when the duty cycle of the PWM signal is 2%. Waveform 1 is the most accurate waveform measured using a high-precision oscilloscope; however, high-precision oscilloscopes are more expensive and more susceptible to the influence of surrounding magnetic fields compared to the device described in this application. Waveform 2 is the waveform measured using the device described in this application. Waveform 3 is based on... Figure 1The waveforms shown are obtained using existing techniques. Waveform 2, except for the spike at the positive PWM cycle, is very similar to waveform 1. Simply removing this spike is sufficient. The spike is caused by the switching of transistors in the H-bridge circuit, the inductive reactance of the coil, the parasitic capacitance of the coil, and the stray capacitance of other components in the circuit. A spike exists momentarily after the transistors in the H-bridge circuit turn on. While waveform 3 appears similar to waveform 2 in the diagram, it is actually mostly noise except for the spike, making accurate sampling impossible.

[0089] Therefore, it can be seen that when the duty cycle of the same PWM signal is 2%, the device of this application still has current in the controlled coil L0, and the current in the controlled coil L0 can be sampled relatively accurately. However, the current in the controlled coil L0 can no longer be measured using existing technology.

[0090] In this embodiment, by setting the current detection amplifier 41, the current value flowing through the coil L0 to be controlled can be sampled. By setting the controller 42, feedback regulation can be achieved. By setting the drive unit 43, the control signal output by the controller 42 can be executed, and a PWM signal can be issued to adjust the magnitude and direction of the current output by the current regulation circuit 10.

[0091] In one embodiment, such as Figure 10 As shown, the coil current control device further includes a short-circuit module 80.

[0092] The shorting module 80 is connected in parallel with the voltage divider module 30 and is used to short-circuit the two ends of the voltage divider module 30 when it is turned on, so that the voltage drop across the voltage divider module 30 is zero.

[0093] When the short-circuit module 80 is turned on, it short-circuits both ends of the voltage divider module 30, thereby bypassing the voltage divider module 30. The voltage drop across the voltage divider module 30 is zero, and it does not have the effect of voltage division.

[0094] For example, the shorting module 80 can be a controllable switch, such as a relay, a switching transistor (e.g., a MOSFET), etc., capable of receiving control signals and turning on or off under the action of the control signals. The control signals received by the shorting module 80 can be issued by the control module 40 or by an external host computer, and are not limited here.

[0095] In this embodiment, by setting a short-circuit module, the preset voltage can be selectively adjusted to zero. For example, when the current is low, the short-circuit module does not conduct, and the voltage divider module divides the voltage, resulting in a lower current in the coil to be controlled, thereby widening the adjustable range of the current value in the coil to be controlled. When the current is high, there is no need for the voltage divider module; the control module can calculate the precise current value, so the short-circuit module conducts, the preset voltage is zero, and the voltage divider module is eliminated, saving energy.

[0096] In one embodiment, such as Figure 11 As shown, the control module also includes: amplifier U1, first voltage divider resistor R3, and second voltage divider resistor R2. The first terminal of the first voltage divider resistor R3 is connected to the power supply signal, the second terminal of the first voltage divider resistor R3 is connected to the first terminal of the second voltage divider resistor R2 and the positive input terminal of amplifier U1, the second terminal of the second voltage divider resistor R2 is grounded, and the output terminal of amplifier U1 is connected to the current detection amplifier 41 and the negative input terminal of amplifier U1.

[0097] The amplifier U1, the first voltage divider resistor R3, and the second voltage divider resistor R2 together form a voltage follower. This serves to buffer, isolate, and improve the load-carrying capacity, resulting in a very low equivalent internal resistance of the amplifier U1 and improving the stability of the signal output from the amplifier U1.

[0098] The current sensing amplifier 41 includes a first input terminal, a second input terminal, an output terminal, and a reference terminal. The first and second input terminals are respectively connected to the two ends of the sampling module 20. The output terminal is connected to the controller 42, and the reference terminal is connected to the amplifier's output terminal. The current sensing amplifier 41 is used to receive the reference potential input at the reference terminal. The amplitude of the sampled voltage value is increased or decreased based on the reference potential to obtain the calculated voltage value. The actual current value on the sampling module 20 is determined based on the calculated voltage value and the resistance value of the sampling module 20.

[0099] The current sensing amplifier 41 requires a reference potential. After acquiring the sampling voltage value across the sampling module 20, it needs to be increased or decreased based on the reference potential to obtain the calculated voltage value. Then, using a preset algorithm in the current sensing amplifier 41, the actual current value on the sampling module 20 can be calculated based on the calculated voltage value and the resistance value of the sampling module 20, and the actual current value is amplified and output.

[0100] In this configuration, the first voltage-dividing resistor is equal to the second voltage-dividing resistor. Therefore, the amplifier's output potential is half the power supply signal, meaning the reference potential is also half the power supply signal.

[0101] In this embodiment, the control module 40 also includes a voltage follower, which can improve the stability of the detection result output by the current sensing amplifier 41.

[0102] In one embodiment, such as Figure 12 As shown, a magnetic levitation system is provided, including: a housing 50, an impeller assembly, and a coil current control device (not shown) from any of the above embodiments, wherein:

[0103] The housing 50 has an internal cavity for receiving the cavity.

[0104] The impeller assembly includes a rotor 61 and a stator 62. The rotor 61 includes a permanent magnet, and the stator 62 includes a levitation coil for generating a magnetic field to drive the permanent magnet to levitate within the receiving cavity.

[0105] The levitation coil, as the coil to be controlled, is connected in series between the midpoint of the first bridge arm 11 and the midpoint of the second bridge arm 12. Since the coil current control device of this application can acquire and accurately control current, especially small currents, and the levitation coil has this requirement, the coil current control device of this application can achieve precise control of the current on the levitation coil, thereby achieving precise control of the magnetic field generated by the levitation coil, and further achieving precise control of the distance at which the rotor 61 levitates within the cavity. Improving the control accuracy of the current on the levitation coil can greatly reduce vibration caused by overshoot, thereby reducing noise, and correspondingly reducing overshoot and thus reducing system energy consumption. Because the control accuracy of the current on the levitation coil is improved, the current on the levitation coil can be quickly adjusted to the correct position, and the adjustment is more precise. Specifically, the beneficial technical effects of this application are explained as follows: Using the device of this application, the current value on the levitation coil can be accurately acquired. If the acquired current value on the levitation coil is inaccurate, it will lead to inaccurate control of the current on the levitation coil by the control module 40. For example, in practice, in a magnetic levitation system, a current of 50mA needs to be applied to the levitation coil. At this time, the actual PWM output of the control module 40 has already made the current of the levitation coil reach 50mA. However, if the current acquisition is inaccurate (as mentioned above)... Figure 1In the existing technical solution, the current acquisition result shows that the current on the levitation coil is 20mA. Therefore, the control module 40 will continue to increase the PWM value to make the acquired current value reach the target current value. However, when the acquired current value reaches the target current value, the actual current value of the levitation coil is already higher than the target current value, for example, it has reached 80mA, so the overshoot situation mentioned above occurs. Furthermore, in a magnetic levitation system, for example, only 10mA of current (i.e., the target current) needs to be added at a certain moment to achieve the operating purpose, but due to inaccurate control, the actual current is loaded to 30mA, resulting in overshoot. This causes the levitation object to move a greater distance, generating more noise and operational instability, and producing higher energy consumption. High energy consumption is a key problem that needs to be solved in magnetic levitation systems, as it may lead to excessively high equipment temperature, affect blood circulation indicators, and even cause the magnetic levitation system to malfunction.

[0106] In this embodiment, the coil current control device of this application is used to control the current of the suspension coil in the magnetic levitation system, which can make the magnetic levitation system have lower noise, lower energy consumption, and more reliable performance.

[0107] In one embodiment, please see [link to previous article]. Figure 12 The magnetic levitation system also includes a sensor module 70. The sensor module 70 is used to collect the actual distance data between the rotor 61 and the housing 50.

[0108] The control module 40 is connected to the sensor module 70 and is used to determine the target current value based on the actual distance data and the target distance data.

[0109] The control module 40 determines how much the current on the suspension coil needs to be adjusted so that the actual distance data reaches the target distance data based on the actual distance data and the target distance data. Therefore, it determines the target current value based on the actual distance data and the target distance data, and then controls the current on the suspension coil to be the target current value.

[0110] In this embodiment, by setting a sensor module, the position of the rotor inside the housing can be obtained, which makes it easier for the control module to determine the target current value of the suspension coil.

[0111] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0112] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A coil current control device, characterized in that, include: A current regulating circuit includes a first bridge arm and a second bridge arm. The first end of the first bridge arm and the first end of the second bridge arm are connected and receive a power signal. The second end of the first bridge arm and the second end of the second bridge arm are connected and grounded. A coil to be controlled is connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm. The current regulating circuit is used to regulate the magnitude and direction of the current flowing through the coil to be controlled. A sampling module is connected in series with the coil to be controlled, and is connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm; A voltage divider module is connected in series with the coil to be controlled, and is connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm, wherein the voltage drop across the voltage divider module is a preset voltage; A control module is connected to the control terminal of the current regulation circuit and both ends of the sampling module, respectively. It is used to acquire the sampling voltage at both ends of the sampling module, and control the working state of the current regulation circuit according to the sampling voltage and the target current of the coil to be controlled so as to adjust the current of the coil to be controlled to the target current. The adjustable range of the current value on the coil to be controlled is related to the preset voltage.

2. The coil current control device according to claim 1, characterized in that, The voltage divider module includes a first diode and a second diode. The positive terminal of the first diode is connected to the negative terminal of the second diode as the first end of the voltage divider module, and the negative terminal of the first diode is connected to the positive terminal of the second diode as the second end of the voltage divider module.

3. The coil current control device according to claim 1, characterized in that, The voltage divider module includes: a variable resistor unit; The control module is connected to the variable resistor unit and is used to dynamically adjust the resistance value of the variable resistor unit during the process of adjusting the current value on the coil to be controlled, so that the voltage drop across the variable resistor unit is the preset voltage.

4. The coil current control device according to claim 1, characterized in that, The coil current control device further includes: A short-circuit module, which is connected in parallel with the voltage divider module, is used to short-circuit the two ends of the voltage divider module when it is turned on, so that the voltage drop across the voltage divider module is zero.

5. The coil current control device according to claim 1, characterized in that, The control module includes: A current sensing amplifier is connected to both ends of the sampling module to obtain the sampling voltage value at both ends of the sampling module, determine the actual current value on the sampling module based on the sampling voltage value at both ends of the sampling module, and amplify and output the actual current value. A controller, connected to the current sensing amplifier, is used to acquire the actual current value and the target current value, and output a control signal based on the deviation between the actual current value and the target current value; A driving unit, connected to the controller, is used to output a corresponding driving signal to the control terminal of the current regulating circuit according to the control signal to control the working state of the current regulating circuit, so as to regulate the current value on the coil to be controlled.

6. The coil current control device according to claim 5, characterized in that, The control module further includes: an amplifier, a first voltage divider resistor, and a second voltage divider resistor. The first end of the first voltage divider resistor is connected to a power signal. The second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor and the positive input terminal of the amplifier. The second end of the second voltage divider resistor is grounded. The output terminal of the amplifier is connected to the current detection amplifier and the negative input terminal of the amplifier.

7. The coil current control device according to claim 6, characterized in that, The current sensing amplifier includes a first input terminal, a second input terminal, an output terminal, and a reference terminal. The first input terminal and the second input terminal are respectively connected to the two ends of the sampling module. The output terminal is connected to the controller, and the reference terminal is connected to the output terminal of the amplifier. The current sensing amplifier is used to receive the reference potential input at the reference terminal. The amplitude of the sampled voltage value is increased or decreased based on the reference potential to obtain the calculated voltage value; Based on the calculated voltage value and the resistance value of the sampling module, the actual current value on the sampling module is determined.

8. The coil current control device according to claim 6, characterized in that, The first voltage divider resistor is equal to the second voltage divider resistor.

9. The coil current control device according to claim 1, characterized in that, The first bridge arm includes a first transistor and a second transistor. The first end of the first transistor serves as the first end of the first bridge arm. The second end of the first transistor and the first end of the second transistor are connected to form the midpoint of the first bridge arm. The second end of the second transistor serves as the second end of the first bridge arm. The second bridge arm includes a third transistor and a fourth transistor. The first end of the third transistor serves as the first end of the second bridge arm. The second end of the third transistor and the first end of the fourth transistor are connected to form the midpoint of the second bridge arm. The second end of the fourth transistor serves as the second end of the second bridge arm. The control module is connected to the control terminals of the first transistor, the second transistor, the third transistor, and the fourth transistor respectively, and is used to control the conduction state of the first transistor, the second transistor, the third transistor, and the fourth transistor respectively, so as to control the working state of the current regulation circuit.

10. A magnetic levitation system, characterized in that, include: A housing having an internal cavity for receiving space; An impeller assembly includes a rotor and a stator, the rotor including a permanent magnet and the stator including a levitation coil for generating a magnetic field to drive the permanent magnet to levitate within the receiving cavity; The sensor module is used to collect the actual distance data between the rotor and the housing; The coil current control device according to any one of claims 1-9, wherein the levitation coil is the coil to be controlled; The control module is connected to the sensor module and is used to determine the target current value based on the actual distance data and the target distance data.

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