Drive circuit for a mass flow controller

Abstract

An example solenoid drive controller for a mass flow controller is provided. The solenoid drive circuit can include a switching voltage control circuit to receive power from a power supply and provide a predetermined voltage across a switch and a solenoid current control circuit including a switch or transistor, where a feedback signal from a current monitor facilitates adjusting a constant output of a valve coil current based on the feedback signal.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 786,054, filed April 9, 2025, entitled “DRIVING CIRCUIT FOR MASS FLOWCONTROLLERS”. The entire contents of U.S. Provisional Patent Application Serial No. 63 / 786,054 are expressly incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to solenoid drive circuits where power dissipation is critical, and more specifically, to solenoid drive circuits for mass flow controllers that regulate flow in response to feedback signals. Background Technology

[0004] A mass flow controller receives the flow rate of one or more gases / fluids, measures the flow rate, and controls the flow rate via a control valve. Summary of the Invention

[0005] The disclosed example mass flow controller includes a solenoid drive circuit responsive to a feedback signal, substantially as shown in and described in connection with at least one of the accompanying drawings, as set forth more fully in the claims. Attached Figure Description

[0006] These and other features, aspects, and advantages of this disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings, in which similar characters throughout the drawings denote similar parts, wherein:

[0007] Figure 1 These are views of example valves and mass flow controllers based on various aspects of this disclosure.

[0008] Figure 2 Examples of solenoid drive circuits according to various aspects of this disclosure are shown.

[0009] Figure 3 An example of a solenoid drive circuit for a mass flow controller according to various aspects of this disclosure is shown.

[0010] Figure 4 Another example of a solenoid drive circuit for a mass flow controller according to various aspects of this disclosure is shown.

[0011] Figure 5 Another example of a solenoid drive circuit for a mass flow controller according to various aspects of this disclosure is shown.

[0012] Figure 6 Another example of a solenoid drive circuit for a mass flow controller according to various aspects of this disclosure is shown.

[0013] The accompanying drawings are not necessarily drawn to scale. Where appropriate, similar or identical reference numerals are used to refer to similar or identical parts. Detailed Implementation

[0014] To facilitate an understanding of the principles of the claimed technology and to present its best operating mode as currently understood, reference will now be made to the embodiments shown in the accompanying drawings, and they will be described using specific language. However, it should be understood that this is not intended to limit the scope of the claimed technology, and such changes and further modifications in the illustrated apparatus, as well as such further applications of the principles of the claimed technology shown therein, are contemplated by those skilled in the art to which the claimed technology pertains.

[0015] Mass flow controllers are used in applications such as semiconductor manufacturing, biological processing, thin film processing, and chemical processing to deliver fluids / gases in precise ratios. In the example of semiconductor manufacturing, gases can be precisely delivered to different areas of a wafer. In addition to cost-effectiveness, such manufacturing applications benefit from faster response times, repeatability of results, and consistency of results. A typical mass flow controller includes inlet and outlet pressure sensors, and a mass flow control valve for controlling the delivery of the fluid flow. Precise valve control can provide improved delivery of such fluids.

[0016] Some example solenoid drive circuits operate under constant current control. Such circuits may include an adjustable voltage source that powers the valve coil. The current through the valve coil can be controlled by an operational amplifier. The current level can be set by a fixed reference voltage source compared to the voltage drop across one or more resistors connected in series with the valve solenoid coil. One or more circuit components can cause adjustment of the voltage source to maintain both voltages at a desired level.

[0017] Therefore, as disclosed herein, an improved solenoid drive circuit for a mass flow controller responds to a control circuit, as provided with respect to the representative figures.

[0018] In a disclosed example, a solenoid drive circuit for a mass flow controller includes: a switching voltage control circuit including a first amplifier, the drive circuit being configured to receive power from a power source and provide a predetermined voltage across a switch, wherein the first amplifier regulates the voltage flowing through the switch from the power source based on a reference voltage; and a solenoid current control circuit including a switch, a second amplifier, and a current monitor, wherein a feedback circuit receives a feedback signal from the current monitor to regulate a constant current output to the coil based on the feedback signal, thereby powering the movement of the solenoid plunger.

[0019] In some examples, the circuit also includes a control circuit that provides commands to the drive circuit.

[0020] In the example, the control circuit is external to the drive circuit.

[0021] In the example, the control circuit calculates a reference voltage to maintain a predetermined switching voltage when the current changes.

[0022] In the example, the predetermined switching voltage is the minimum voltage range.

[0023] In the example, the minimum voltage range is in the range of tens of millivolts or less.

[0024] In some examples, the switch is a metal-oxide-semiconductor field-effect transistor (MOSFET), in which the voltage across the MOSFET is regulated in response to a current feedback signal.

[0025] In some examples, the voltage control reference voltage is provided by the control circuit or by the solenoid current feedback signal.

[0026] In some publicly available examples, a solenoid drive circuit for a mass flow controller includes: a switching voltage control circuit including a first amplifier, the drive circuit being configured to receive power from a power source and provide a predetermined voltage across a switch, wherein the first amplifier regulates the voltage flowing through the switch from the power source based on a reference voltage; and a solenoid current control circuit including a switch, a second amplifier, and a current monitor, wherein a feedback circuit receives a feedback signal from the current monitor to regulate a constant current output to the coil based on the feedback signal, thereby powering the movement of the solenoid plunger; and a summing device configured to calculate a reference voltage for the switching voltage control circuit in response to a change in the current received via the current feedback signal.

[0027] In some examples, the circuit also includes a current-sensing resistor configured to transmit a current value to set the reference voltage value for the switching voltage control circuit.

[0028] In the example, the summing device calculates the reference voltage for the switching voltage control circuit based on the current feedback signal from the current sensing resistor.

[0029] In some examples, the processed current feedback signal is mathematically processed, amplified, or voltage-divided.

[0030] In some examples, the circuit also includes a current reference voltage configured to transmit a voltage value to set the value of the reference voltage for the switching voltage control circuit.

[0031] In the example, the summing device calculates the reference voltage for the switching voltage control circuit based on the current feedback signal from the current-to-voltage converter device.

[0032] Figure 1 This is a view of an example mass flow and / or density measurement device 10 according to various aspects of this disclosure, in which a solenoid valve mass flow controller is employed. The illustrated mass flow measurement and control system 10 includes a process setup 12, a control or calculation unit 14 (e.g., a control circuit system), and one or more sensors 16. The device 10 is connected to a flow base 20 to guide gas / fluid from an inlet 18 to an outlet 26. A flow control valve 22 is arranged between the inlet and outlet, and the flow valve is controlled by current flowing through a solenoid 24 based on commands from the control unit 14.

[0033] A solenoid drive circuit for a mass flow controller is disclosed, designed to provide improved accuracy and efficiency compared to conventional valve drive circuits. This solution can be used with any type of mass flow controller, such as those employing thermally based sensors (e.g., sensor 16 at the fluid inlet and / or outlet). In some designs, the valve solenoid 24 is part of the controller and can be a power dissipation source and therefore a heat source.

[0034] The accuracy of the sensor described herein depends on the sensor's temperature measurement and is quite sensitive to ambient temperature, which can adversely affect the accuracy of mass flow rate measurements. For example, a thermal sensor located inside the housing of the mass flow controller (along with other power dissipation components within the housing) can cause internal temperature variations, which can directly impact device performance. Sensitive parameters may include, for example, the temperature of the solenoid coil 24 and / or Figure 2 The temperature of the MOSFET switch 58. As disclosed herein, maintaining the lowest possible temperature for each component and drive circuit ensures minimal interruptions due to power dissipation.

[0035] Therefore, reducing total power dissipation (e.g., the total power dissipation of one or more components inside the housing) helps improve the measurement accuracy of thermal sensors and leads to improved overall device performance. One contributing factor to power dissipation (and therefore temperature variation) is the valve coil driver circuitry. Reducing the power dissipation of the solenoid coil driver is one way to achieve better accuracy and improved efficiency in mass flow measurement and / or control. Reducing the power dissipation of the solenoid coil driver can also reduce the total power consumption of the entire device.

[0036] Compared to conventional mass flow controllers, the disclosed example solenoid drive circuit for mass flow controllers offers improved accuracy and improved response time to varying flow rates. Some example precision gas / fluid distribution systems employing solenoid drive circuits for mass flow control also include control circuitry systems. For example, the control circuitry system is configured to control valves to regulate gas / fluid flow rates based on measurements from a temperature sensor that measures the temperature of the input process gas / fluid.

[0037] In some example systems, solenoid 24 may include a plunger surrounded by and responsive to an electrically activated coil. The coil is designed to move the plunger when the solenoid is energized and / or de-energized, but other suitable mechanisms for moving the plunger are considered to be within the scope of this disclosure. In operation, the current to the coil can be controlled or regulated, thereby changing the position of the plunger relative to the flow passage, and thus changing the position of control valve 22 relative to the flow passage. As disclosed herein, control of solenoid 24, valve 22, and therefore of a certain amount of gas / fluid through inlet 18, flow base 20, and outlet 26 is driven by a solenoid drive circuit.

[0038] Figure 2 An example of a solenoid drive circuit 50 is shown. As illustrated, circuit 50 includes a valve coil power supply 52 with a fixed output voltage provided by internal feedback. This current control circuit responds to local feedback, including feedback from operational amplifier 60, transistor 58 (e.g., a field-effect transistor (FET) or metal-oxide-semiconductor field-effect transistor (MOSFET) type transistor), and one or more current-sensing resistors 66. The variable parameters of the valve solenoid 56 are not part of the feedback circuit and have a reduced impact on the overall stability of the circuit.

[0039] The valve coil current control voltage source 64 is variable and provides all the necessary voltage range for valve coil control. The valve coil power supply 52 is fixed. In some examples, circuit 50 experiences additional power dissipation on transistor 58, which can be equal to the product of the drain-to-source voltage drop and / or the valve current 70. Therefore, when the valve is fully open, the current 70 (Io) can increase significantly, and the power dissipation on the circuit is at a high level.

[0040] Figure 3 An example solenoid drive circuit 100 for a mass flow controller according to aspects of this disclosure is shown. As shown, the solenoid drive circuit 100 may include a switching voltage control circuit 102, which includes a first amplifier 108. The drive circuit 100 receives power from a power source 106 and provides a constant current output to the solenoid coil 110 to drive the movement of the solenoid plunger. In some examples, the first amplifier 108 regulates the voltage at the drain of a switch 118 (e.g., a MOSFET) from the power source 106 based on a reference voltage 112.

[0041] In the example shown, the solenoid current control circuit 104 includes a switch 118, a second amplifier 116, and a current monitor 122. The solenoid current control circuit receives a feedback signal from the current monitor 122 to adjust the output from the valve coil current 123 based on the feedback signal.

[0042] As shown, circuit 100 is configured to minimize power dissipation on switch 118. In operation, first operational amplifier 108 controls the variable valve coil power supply 106 with its output, whose drain voltage is kept fixed and equal to voltage reference 112. This voltage can be preset to provide a predetermined (e.g., minimum) drain-source voltage, such as below a threshold (e.g., maximum) valve current 123 (Io). For example, for switch 118 operating as an enhancement-mode MOSFET transistor, the predetermined drain-source voltage can be within a given setting range (e.g., within tens of millivolts). This range ensures that dissipation on switch 118 is low. With this current source configuration, the valve coil is therefore part of the feedback circuitry and may result in some degree of instability. However, because the voltage control range on the drain of switch 118 is relatively small, the stability of the circuit has a limited or insignificant impact on valve performance.

[0043] Figure 4 Another example solenoid drive circuit 100A for a mass flow controller according to various aspects of this disclosure is shown. Where appropriate, similar or identical reference numerals are used to refer to similar or identical parts, such as by adding letter indicators to previously used reference numerals to indicate different parts having similar functions, properties, structures and / or arrangements.

[0044] like Figure 4 As shown, the solenoid drive circuit 100A includes a control circuit 105 that provides commands to the drive circuit. The control circuit 105 provides commands via one or more signals, thereby controlling the switching reference voltage circuit at 112.

[0045] The control circuit 105 can be integrated into a mass flow device (e.g., in...). Figure 1 (within the control / computing unit 14 of the device 10 shown), and / or can be outside the device (e.g., in...) Figure 1 The process setup shown is located at 12 points, or remotely from the device and process setup. In some examples, control circuitry 105 is embodied in analog and / or digital computing devices. Example control circuitry 105 may be, for example, an integrated processing system, a programmable logic controller, a general-purpose computer, a laptop computer, a tablet computer, and / or configured to interact with... Figure 1 The valve 22 communicates with any other type of processing system. For example, the control circuitry system may include a processor, memory, and storage devices. An example processor may be any general-purpose central processing unit (CPU) from any manufacturer. In some other examples, the processor may include one or more dedicated processing units, such as a RISC processor with an ARM core, a graphics processing unit, a digital signal processor, and / or a system-on-a-chip (SoC). The processor executes machine-readable instructions, which may be stored locally at the processor (e.g., in the included cache or SoC), in memory (e.g., random access memory or other volatile memory, read-only memory, or other non-volatile memory such as flash memory), and / or in storage devices. Example storage devices may be hard disk drives, solid-state drives, hybrid drives, RAID arrays, and / or any other high-capacity data storage devices.

[0046] However, this disclosure is not limited thereto, and allows the control circuit to be any type of processing and / or mathematical calculation / computation device suitable for providing fine control of the solenoid drive circuit.

[0047] In operation, the control circuit 105 is configured to calculate the reference voltage 112 and, in response to changes in current received via the current feedback signal, provide control to the amplifier 108 via the reference voltage 112 in the form of a shift connection / signal 107.

[0048] For example, control circuit 105 calculates a reference voltage 112 to maintain a predetermined switching voltage when the current changes. In the disclosed example, the predetermined switching voltage is a value within a voltage range (e.g., a minimum value), where the minimum voltage range is within tens of millivolts.

[0049] exist Figure 5 In the middle, the solenoid drive circuit 100B and Figure 4 The solenoid drive circuit 100A is similar, wherein the difference in the drain setting voltage source 112 can be adjusted by a signal derived from the current feedback circuit at 131. The voltage is calculated by one or more circuits such that the drain-source voltage is maintained at a predetermined (e.g., minimum) value, where the current (Io) is allowed to fluctuate within a range.

[0050] Circuit 100B is similar to circuit 100A; however, instead of ( Figure 4 The control circuit 105 calculates the drain-source voltage, which is automatically generated by the current-sensing resistor 131. This voltage can be divided and / or subtracted from the drain setting voltage source 112 to minimize the drain-source voltage on the switch 118. The larger the current, the larger the voltage subtracted from the drain setting voltage source, thus maintaining a small drain-source voltage. This configuration reduces power dissipation on the switch 118 even at high valve coil current levels.

[0051] In some examples, circuit 100B is configured to generate a switching reference voltage directly based on the current feedback signal or via amplifier 108 based on a processed current feedback signal (e.g., amplified, voltage-divided, etc.). Therefore, as... Figure 4 As provided, voltage measurements can be performed directly from current monitor 122 (e.g., using digital control circuitry) and / or indirectly using a control circuitry system (e.g., indirect analog, internal control). In this example, Figure 5 In the drive circuit 100B shown, the solenoid is controlled by a summing device 136, which receives signals from voltage divider resistors 132 and / or 134. Therefore, a reference voltage is calculated in response to changes in current received via feedback signal 130.

[0052] Figure 6 Another example solenoid drive circuit 100C for a mass flow controller according to various aspects of this disclosure is shown. In the example drive circuit 100C, the control of the solenoid is driven by a summing device 136A, which is known from a signal originating from valve coil current control 114A by voltage divider resistors 140 and 142. Voltage divider resistors 140 and 142 are configured to transmit voltage values ​​to set the value of switch 118. Figure 6 As shown, the automatic compensation voltage is provided by the valve coil current control reference voltage source 114A, which is similar to the voltage drop across the current sensing resistor 120.

[0053] As used herein, “and / or” means any one or more items in a list connected by “and / or”. As an example, “x and / or y” means any element in the three-element set {(x), (y), (x, y)}. In other words, “x and / or y” means “one or both of x and y”. As another example, “x, y and / or z” means any element in the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, “x, y and / or z” means “one or more of x, y and z”. As used herein, the term “exemplary” means used as a non-limiting example, instance, or illustration. As used herein, the terms “such as” and “for example” introduce a list of one or more non-limiting examples, instances, or illustrations.

[0054] While this method and / or system has been described with reference to certain embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted without departing from the scope of this method and / or system. For example, blocks and / or components of the disclosed examples can be combined, divided, rearranged, and / or otherwise modified. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from the scope of this disclosure. Therefore, this method and / or system is not limited to the specific embodiments disclosed. Rather, this method and / or system will include all embodiments that fall within the scope of the appended claims both literally and under the principle of equivalents.

Claims

1. A solenoid drive circuit for a mass flow controller, comprising: A switching voltage control circuit includes a first amplifier, and a drive circuit for receiving power from a power source and providing a predetermined voltage on a switch, wherein the first amplifier regulates the voltage flowing through the switch from the power source based on a reference voltage; and A solenoid current control circuit includes a switch, a second amplifier, and a current monitor, wherein a feedback circuit receives a feedback signal from the current monitor to adjust a constant current output to the coil based on the feedback signal, thereby providing power for the movement of the solenoid plunger.

2. The circuit of claim 1 further includes a control circuit for providing commands to the drive circuit.

3. The circuit of claim 2, wherein the control circuit is external to the drive circuit.

4. The circuit of claim 3, wherein the control circuit calculates the reference voltage to maintain a predetermined switching voltage when the current changes.

5. The circuit of claim 4, wherein the predetermined switching voltage is a minimum voltage range.

6. The circuit of claim 5, wherein the minimum voltage range is in the range of tens of millivolts or less.

7. The circuit of claim 1, wherein the switch is a metal-oxide-semiconductor field-effect transistor (MOSFET), wherein the voltage across the MOSFET is regulated in response to a current feedback signal.

8. The circuit of claim 1, wherein the voltage control reference voltage is provided by the control circuit or by the solenoid current feedback signal.

9. A solenoid drive circuit for a mass flow controller, comprising: A switching voltage control circuit includes a first amplifier, and a drive circuit for receiving power from a power source and providing a predetermined voltage on a switch, wherein the first amplifier regulates the voltage flowing through the switch from the power source based on a reference voltage; and A solenoid current control circuit includes a switch, a second amplifier, and a current monitor, wherein a feedback circuit receives a feedback signal from the current monitor to adjust a constant current output to the coil based on the feedback signal, thereby providing power for the movement of the solenoid plunger. and A summing device configured to calculate a reference voltage for a switching voltage control circuit in response to a change in current received via the current feedback signal.

10. The circuit of claim 9 further includes a current sensing resistor configured to transmit a current value to set the value of the reference voltage of the switching voltage control circuit.

11. The circuit of claim 9, wherein the summing device calculates the reference voltage of the switching voltage control circuit based on the current feedback signal from the current sensing resistor.

12. The circuit of claim 11, wherein the processed current feedback signal is mathematically processed, amplified, or voltage-divided.

13. The circuit of claim 9, further comprising a current reference voltage configured to transmit a voltage value to set the value of the reference voltage of the switching voltage control circuit.

14. The circuit of claim 9, wherein the summing device calculates the reference voltage of the switching voltage control circuit based on the current feedback signal from the current-to-voltage converter device.

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