CN115913004B - Braking circuit, system and braking method of magnetic suspension molecular pump controller - Google Patents
Braking circuit, system and braking method of magnetic suspension molecular pump controller Download PDFInfo
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Abstract
The application discloses a brake circuit, a brake system and a brake method of a magnetic suspension molecular pump controller, comprising the following steps: the device comprises a voltage dividing module, a reference module, a comparison module, a driving module and a control module; the voltage dividing module obtains divided voltage according to the power voltage and transmits the divided value to the comparison module; the reference module is used for providing a reference voltage and transmitting the reference voltage to the comparison module; the comparison module is used for transmitting signals to the driving module according to the results of the divided voltage and the reference voltage; the driving module is used for controlling the opening of the control module; the control module is used for controlling whether to discharge to the braking load. According to the brake circuit, the brake system and the brake method of the magnetic suspension molecular pump controller, rotational kinetic energy is converted into other capacities such as heat energy through the design of the circuit and the brake load. The volume of the motor and the use cost of the electric element are reduced, other functions of the magnetic suspension molecular pump are not affected when the system works, and the structure is simple.
Description
Technical Field
The application relates to the field of molecular pump braking circuits, in particular to a braking circuit, a braking system and a braking method of a magnetic suspension molecular pump controller.
Background
The magnetic suspension molecular pump is a product which is operated by a turbine at a high speed to obtain vacuum. The structure mainly comprises a magnetic suspension molecular pump and a controller. The controller comprises a power supply, a suspension system, a driving module, a management system and a braking system (such as CN212429266U, CN 112566461A).
The turbine of the magnetic suspension molecular pump is driven to rotate by a direct current motor, and the rotating speed is set to be 50-1500 Hz. Because the rotational inertia of the turbine is large and is limited by the strength and rigidity of the turbine blades, the starting process from low speed to high speed of the turbomolecular pump is slower, and the turbomolecular pump is also slower in braking in a high speed state.
The turbine rotating at high speed has larger rotational kinetic energy, and the turbine can stop rotating only after the rotational kinetic energy is converted into other energy according to the energy conservation theorem. In a state without a brake system and in a relatively vacuum environment, the energy loss is small, and it usually takes several hours to stop the rotation.
The motor is typically braked mechanically and electrically.
First, mechanical braking is accomplished by a mechanical structure that generates friction by pressure by contacting a rotating object to accomplish the braking process. For example, in the form of an electromagnetic band-type brake, the pressure generated by a spring is used for pressing a brake pad and a brake roller to form braking friction force so as to finish braking.
Second, the electric reverse braking is to change the phase sequence of the motor stator winding while the motor cuts off the power supply for normal operation, so that the motor has a reverse trend to generate larger braking torque. The electric energy consumption braking is that when the motor cuts off the AC power supply, any two phases of the stator winding are added into the DC power supply to generate a static magnetic field, and the static magnetic field is cut by the inertial rotation of the rotor to generate braking torque. The electric regenerative feedback brake mainly utilizes an electronic circuit to feed back the rotational kinetic energy of the motor to a power grid.
For the second mode, as shown in fig. 1, converting kinetic energy of a turbine into electric energy is a technical mode. In the braking process of the magnetic suspension molecular pump, a rotor magnetic field cuts a stator winding coil, and the stator winding coil generates induced electromotive force and feeds electric energy back to a power supply network through reverse diodes connected in parallel with the IGBT. The magnitude of the induced electromotive force is according to the formula e=blvsin θ, where B is the magnetic induction intensity, L is the conductor length, V is the cutting speed, and θ is the angle between the conductor and the moving speed. The magnitude of the induced electromotive force is proportional to the rotation speed. The VCC voltage rises above the supply voltage due to the large moment of inertia.
For the second mode, the above mode has the disadvantage of not being independent and of being costly, since none of the above systems is suitable for magnetic levitation molecular pumps. Therefore, designing a simple, reliable and independent brake circuit and system becomes a technical problem to be solved urgently.
Disclosure of Invention
The application mainly aims to provide a brake circuit of a magnetic suspension molecular pump controller so as to solve the technical problems in the background art.
Another object of the present application is to provide a brake system for a magnetic levitation molecular pump controller.
The application further aims to provide a braking method of the magnetic suspension molecular pump.
In order to achieve the above purpose, the technical scheme adopted by the application is as follows:
a braking system of a magnetic suspension molecular pump controller, wherein back electromotive force generated by the braking system is called power supply voltage, and the braking system is used for controlling whether to discharge to a braking load according to the power supply voltage;
the braking system includes: the device comprises a voltage dividing module, a reference module, a comparison module, a driving module and a control module;
the output end of the power supply is communicated with the input end of the voltage dividing module, and the output end of the voltage dividing module and the output end of the reference module are connected with the input end of the comparison module; the output end of the comparison module is connected with the input end of the driving module, the output end of the driving module is connected with the input end of the control module, and the output end of the control module is connected with the input end of the braking load;
the voltage dividing module obtains divided voltage according to the power voltage and transmits the divided value to the comparison module;
the reference module is used for providing a reference voltage and transmitting the reference voltage to the comparison module;
the comparison module is used for transmitting signals to the driving module according to the results of the divided voltage and the reference voltage;
the driving module is used for controlling the opening of the control module;
the control module is used for controlling whether to discharge to the braking load.
Further designed, the working method of the braking system is as follows:
in the first case, the magnetic levitation molecular pump is started or works normally: the reference voltage provided by the reference module is larger than the voltage division value generated by the voltage division module, and the output level of the comparison module is high; the high level output by the comparison module is converted into low level after passing through the driving module, the control module is disconnected, the braking load connected with the power supply is disconnected with the negative electrode of the power supply, the braking load does not work, and the divided voltage is unchanged because the counter electromotive force does not exist;
second case: after the magnetic suspension molecular pump is braked, the braking system circulates in the discharging-charging process;
the power supply voltage is increased due to the back electromotive force generated by the rotating magnetic field cutting coil, the partial pressure value generated by the partial pressure module is increased continuously, and when the partial pressure voltage exceeds the upper limit threshold value, the discharging process is carried out: the comparison module outputs a low level; the low level output by the comparison module is converted into high level through the driving module, the control module is closed, a load connected with a power supply is connected with a power supply cathode, the braking load works, the generated electric energy is released, and the power supply voltage is continuously reduced; when the divided voltage is reduced to a lower limit threshold value, ending the discharging process;
ending the discharging process and entering the charging process: the control module is disconnected, a braking load connected with a power supply is disconnected with a negative electrode of the power supply, and the braking load does not work; and when the divided voltage is larger than the upper limit threshold again, the discharging process is carried out again, and the discharging-charging process is repeated.
Further, the braking load is an energy storage element or an energy consumption element.
A brake circuit of a magnetic levitation molecular pump controller, comprising: resistors R3-R10, diodes D1-D2, capacitors C5 and C7-C8, a comparator U1, a driver U2 and a field effect transistor Q1;
the resistors R4, R7 and R10 form a voltage dividing module;
the diodes D1-D2 and C5 form a reference module, and meanwhile, the diode D2 and the capacitor C5 also provide a power supply system for the U2;
the comparator U1, the resistors R6 and R9 form a comparison module;
the driver U2 and the resistor R8 form a driving module;
the field effect tube Q1 and the resistor R3 form a control module of a braking load;
the capacitor C7 and the resistor R10 form a discharge delay system;
the resistor R5 and the capacitor C8 form a power supply filter network.
Further, the connection relation among the voltage dividing module, the reference module, the comparison module, the driving module, the control module, the discharging delay system and the power supply filter network is as follows:
the second end of the resistor R4 is connected with the first end of the resistor R7, and the second end of the resistor R7 is connected with the first end of the resistor R10;
the anode of the diode D1 is connected with the cathode of the diode D2;
pin 1 of U1 (IN-), the first end of capacitor C7, the first end of resistor R10, the second end of resistor R7 remain connected; pin 2 (GND) of U1, the second end of capacitor C5, the second end of capacitor C7, the second end of resistor R10, and the anode of diode D2 remain connected; pin 3 of U1 (in+), the second terminal of resistor R6, the first terminal of resistor R9 remain connected; the pin 4 (OUT) of the U1 is connected with the second end of the resistor R9; the pin 5 (VCC) of U1 is connected with the cathode of the diode D1;
the first end of the resistor R6 is connected with the first end of the resistor R5, the first end of the capacitor C5, the anode of the diode D1 and the cathode of the diode D2;
pin 1 (VDD) of driver U2, the second terminal of resistor R5, the first terminal of capacitor C8 remain connected; the pin 2 (GND) of the U2 is connected with the second end of the capacitor C8, the anode of the diode D2, the second end of the capacitor C5, the second end of the capacitor C6, the second end of the capacitor C7 and the second end of the resistor R10; the pin 3 (IN+) of the U2 is connected with the first end of the capacitor C8 and the second end of the resistor R5; the pin 4 (IN-) of U2 is connected with the second end of the resistor R9 and the pin 4 (OUT) of U1; the pin 5 (OUT) of the U2 is connected with the first end of the resistor R8;
the grid electrode of the field effect tube Q1 is connected with the second end of the resistor R8, the drain electrode of the field effect tube Q1 is connected with the resistor R3, and the source electrode of the field effect tube Q1 is grounded.
Further, the method further comprises the following steps: capacitors C1-C4, C6 and resistors R1-R2;
the capacitors C1-C4 form a magnetic suspension molecular pump power supply filtering energy storage circuit; the capacitors C1-C4 are connected in parallel, and the first ends of the capacitors C1-C4 are connected with the first end of the resistor R3, the second end of the resistor R2 and the first end of the resistor R4; the second ends of the capacitors C1-C4 are grounded (i.e., are kept connected with the second ends of the capacitors C5-C8);
the resistors R1 and R2, the diodes D1-D2 and the capacitor C6 provide a power supply system for the U1;
the second end of the resistor R1 is connected with the first end of the resistor R2, and the second end of the resistor R2 is connected with the first end of the resistor R4; the first end of the resistor R1 is connected with the negative electrode of the D1, the No. 5 pin of the U1 and the first end of the capacitor C6; the anode of the diode D2 and the second end of the capacitor C6 are connected with the pin 2 of the U1; the pin 2 (GND) of U1 is connected to the second end of the capacitor C6, and the pin 5 (VCC) of U1 is connected to the first end of the capacitor C6.
A braking system of a magnetic suspension molecular pump controller adopts the braking circuit to control whether a power supply is communicated with a braking load or not, and the braking is realized through the communication between the braking load and the power supply.
The braking method of the magnetic suspension molecular pump adopts the braking system to brake, and the braking is a process of alternately repeating the discharging time t2 and the charging time t 1;
1) The discharging process comprises the following steps:
when the value of the power supply voltage after passing through the voltage dividing module exceeds a set upper limit threshold UTH, the comparison module outputs a low level; the driving module outputs high level to the control module after reversing the driving module, and the charges on the magnetic suspension molecular pump power supply filtering energy storage circuit are released through a braking load, so that the power supply voltage is reduced;
according to the calculation formula:
wherein t2 is discharge time, and R3 is discharge loop resistance R3; C1+C2+C3+C4 is an energy storage capacitor;
2) And (3) charging:
when the value of the power supply voltage after passing through the voltage dividing module is lower than the lower limit threshold UTL, the comparison module outputs high level, the power control device is driven to be disconnected by reversing the power supply voltage to low level through the driving module, and the system starts to charge.
According to the calculation formula:
wherein t1 is charging time, V1 is a capacitor charging maximum voltage value of C1-C4, C1+C2+C3+C4 is an energy storage capacitor, ln () is a logarithm of e as a base;
r represents a capacitive reactance, and the capacitive reactance,
wherein f is the rotation frequency of the magnetic suspension molecular pump, and C is the sum of the energy storage capacitors C1+C2+C3+C4.
Further, UTH, UTL are calculated using the following formula:
uref is a reference voltage, that is, a voltage across the diode D2, and Uoh and Uol are high and low levels output from the comparator U1.
The beneficial effects of the application are as follows:
first, the basic concept of the present application is: the turbine rotating at high speed of the magnetic suspension molecular pump has larger rotational kinetic energy, and when braking is needed, the kinetic energy of the turbine is needed to be converted into other energy (mainly electric energy) so as to realize the rapid braking of the magnetic suspension molecular pump.
Firstly, sending a shutdown instruction and carrying out subsequent energy conversion through the shutdown instruction when the system is in the working process, and carrying out capacitor charging after the energy conversion; however, because the magnetic suspension molecular pump has larger rotational kinetic energy, the electric energy fed back in the motor braking process can not be completely absorbed by the energy storage element. At this time, a circuit system is required to realize control of the braking load. This problem was the first time the present application has been developed.
Second, a second application point of the present application is that: the working idea of the brake circuit designed by the application is as follows: after the magnetic suspension molecular pump is stopped, the electric energy fed back in the motor braking process can not be completely absorbed by the energy storage element because the magnetic suspension molecular pump has larger rotation kinetic energy; at this time, the voltage is continuously increased, and when the power supply voltage U exceeds the set upper limit value Umax, the voltage module is turned over. The power control device (i.e. the control module) is driven to work through the driving module (i.e. the driving module), and the electric charge on the capacitor is released through the braking load, so that the power supply voltage U is reduced. When the power supply voltage U exceeds the set lower limit value Umin, the voltage module is turned back to the original state, and the driving module is disconnected after passing through the logic comparison circuit. I.e. "discharge-charge" process design is the core design point.
Third, a third application point of the present application is that: based on the second point light concept, it is a core gist to embody the design circuit design and the specific control procedure.
Specifically, the control process realized by the application is as follows: during braking, the process of alternately repeating the discharging time t2 and the charging time t 1;
1) The discharging process comprises the following steps:
when the value of the power supply voltage after passing through the voltage dividing module exceeds a set upper limit threshold UTH, the comparison module outputs a low level; the driving module outputs high level to the control module after reversing the driving module, and the charges on the magnetic suspension molecular pump power supply filtering energy storage circuit are released through a braking load, so that the power supply voltage is reduced;
according to the calculation formula:
wherein t2 is discharge time, and R3 is discharge loop resistance R3; C1+C2+C3+C4 is an energy storage capacitor;
2) And (3) charging:
when the value of the power supply voltage after passing through the voltage dividing module is lower than the lower limit threshold UTL, the comparison module outputs high level, the power control device is driven to be disconnected by reversing the power supply voltage to low level through the driving module, and the system starts to charge.
According to the calculation formula:
wherein t1 is charging time, V1 is a capacitor charging maximum voltage value of C1-C4, C1+C2+C3+C4 is an energy storage capacitor, ln () is a logarithm of e as a base;
r represents a capacitive reactance, and the capacitive reactance,
wherein f is the rotation frequency of the magnetic suspension molecular pump, and C is the sum of the energy storage capacitors C1+C2+C3+C4. .
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings that are needed in the technical description of the present application will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a diagram of the background of the application.
Fig. 2 is a flowchart of the operation of a brake system of a magnetic levitation molecular pump controller according to the present application.
Fig. 3 is a modular design of a brake system of a magnetic levitation molecular pump controller according to the present application.
Fig. 4 is a schematic block diagram of a brake system of a magnetic levitation molecular pump controller according to the present application.
Fig. 5 is: when the output voltage is at the low level Uol, a current is drawn from the reference voltage Uref terminal to the output terminal.
Fig. 6 is: when the output voltage is at the high level Uoh, a current is drawn from the output to the reference voltage Uref.
FIG. 7 is a schematic diagram of hysteresis voltage.
Fig. 8 is a timing diagram of the operation of a brake system of a magnetic levitation molecular pump controller according to the present application.
Fig. 9 is a physical diagram of the present application.
Fig. 10 is a physical view (another view angle) of the present application.
Detailed Description
The present application will be further described with reference to the following detailed description, wherein the drawings are for illustrative purposes only and are shown in schematic drawings, rather than physical drawings, and are not to be construed as limiting the present application, and in order to better explain the detailed description of the application, certain components of the drawings may be omitted, enlarged or reduced in size, and not represent the actual product, and it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted, and that all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the application based on the detailed description of the present application.
<Example 1: braking system of magnetic suspension molecular pump controller>
The braking system of the magnetic suspension molecular pump controller is used for controlling whether the power supply voltage of back electromotive force generated by the rotating magnetic field cutting coil is communicated with a braking load or not when the magnetic suspension molecular pump is braked; comprising the following steps: the device comprises a voltage dividing module, a reference module, a comparison module, a driving module and a control module.
<1. Modular action>
1) The voltage dividing module is used for distributing the power transmission voltage of the power supply to obtain divided voltage, and then transmitting the voltage of the comparison terminal to the negative comparison terminal of the comparison module;
2) The reference module is used for providing a reference voltage for the comparison module and is used for providing an upper limit threshold value and a lower limit threshold value;
3) The comparison module compares the relation between the divided voltage and the upper threshold and the lower threshold and transmits an instruction to the driving module.
4) The driving module is used for reversing the level output by the comparing module. And simultaneously generates the input voltage required by the control module.
5) The control module is controlled by the driving module to be turned on and turned off. In the conducting process, the power supply voltage is connected with the braking load, so that the electric energy generated by the reverse electromotive force is released.
<2. Module connection relation>
A power supply (which is the electric energy generated by a turbine in the background technology, namely, a rotor magnetic field cuts a stator winding coil, and the stator winding coil generates induced electromotive force);
the power supply is connected with the input end of the voltage dividing module so that the voltage dividing module can obtain divided voltage;
the output end of the voltage dividing module and the output end of the reference module are connected with the input end of the comparison module;
the output end of the comparison module is connected with the input end of the driving module;
the output end of the driving module is connected with the input end of the control module;
the output end of the control module is connected with a braking load.
<3. Specific structure of voltage dividing module>
Referring to fig. 4, in the present application: the voltage dividing module comprises resistors R7, R4 and R10, wherein the resistor R4 is connected with the resistor R7, and the resistor R7 is connected with the resistor R10.
The series resistance value of the resistors R4, R7 and R10 is calculated according to a formula (R4 +R7 +R10), U is the power supply voltage, and Ic is the consumption current of the voltage division module:
calculating the resistance values of (R4+R7) and R10 according to a formula, wherein Uin is the divided voltage after the voltage dividing module;
<4. specific construction of reference module>
Referring to fig. 4, in the present application, the reference module includes: the device comprises a diode D1, a diode D2, a resistor R1, a resistor R2 and a capacitor C5, wherein the anode of the diode D1 is connected with the cathode of the diode D2, the output voltage Uref of the diode D2 is selected as the power supply voltage according to the voltage requirement of a driving module U2, and the series voltage of the diode D1 and the diode D2 is selected as the power supply voltage according to the voltage requirement of a comparison module U1.
<5. Specific structure of comparison module and connection relation design of comparison module and other modules>
Referring to fig. 4, the comparison module includes: comparator U1, resistors R6 and R9;
the pin 1 of U1 is connected with one end of a capacitor C7 and one end of a resistor R10; the pin 2 of U1 is connected with the other end of the capacitor C7 and the other end of the resistor R10; the pin 3 of the U1 is connected with one end of a resistor R6 and one end of a resistor R9; the pin 4 of the U1 is connected with the other end of the resistor R9; the pin 5 of U1 is connected with the negative pole of diode D1.
Referring to fig. 5, when the voltage at the output terminal of the comparator U1 is at the low level Uol, a current flows from the output terminal of D2 to the output terminal, and the current il= (Uref-Uol)/(r6+r9) flows through the feedback loop.
Referring to fig. 6, when the voltage at the output terminal of the comparator U1 is at the high level Uoh, the current flows from the output terminal of the comparator U1 to the D2 output Uref terminal, and the current ih= (Uoh-Uref) (r6+r9) flowing through the feedback loop.
The comparator has an upper threshold value UTH and a lower threshold value UTL due to the positive feedback circuit.
The circuit is initially electrified, the divided voltage Uin is smaller than the reference voltage Uref, the comparison module outputs a high level Uoh, and the forward input end of the comparator is an upper limit threshold UTH.
As shown in fig. 5, as the voltage increases, the comparator outputs a low level UoL when the negative input voltage Uin of the comparator > the positive input ULT of the comparator U1.
As shown in fig. 6, when the negative input terminal voltage Uin < the positive input terminal UTH of the comparator U1, the comparator U1 outputs a high level Uoh.
As shown in fig. 7, the following formula is derived:
hysteresis voltage Δv=uth-UTL.
△V＝(Uref+Ih×R6)-(Uref-IL×R6)
△V＝(Ih+IL)×R6
Substituting Ih, IL into the formula gives:
△V＝(Uoh-Uol)×R6/(R6+R9)
the power supply voltage value difference DeltaU= [ DeltaVx (R4+R7+R10) ]/R10;
<6. specific structure of driving module and connection relation design of driving module and other modules>
The driving module is composed of a high-speed low-side gate driver.
Referring to fig. 4, the driving module includes: a driver U2 and a resistor R8; the pin 1 of the U2 is connected with one end of a resistor R5 and one end of a capacitor C8; the pin 2 of the U2 is connected with the other end of the capacitor C8; the pin 3 of the U2 is connected with one end of a capacitor C8 and one end of a resistor R5; the other end of the resistor R9 is connected with the pin 4 of the U2, and one end of the resistor R8 is connected with the pin 5 of the U2.
<7. Specific construction of control module and connection relation design of control module and other modules>
The control module adopts an N-type field effect transistor to control the discharge of the system.
The control module comprises: the field effect transistor Q1 and the resistors R3 and R8, the grid electrode of the field effect transistor Q1 is connected with the resistor R8, the drain electrode of the field effect transistor Q1 is connected with the resistor R3, and the source electrode of the field effect transistor Q1 is grounded.
<8. Circuit workflow>
As shown in fig. 8, the braking system is divided into a discharging part and a charging part during braking.
1) The discharging process comprises the following steps:
when the value of the power supply voltage after passing through the voltage dividing module exceeds the set upper limit UTH, the comparison module outputs a low level. The power control device is driven to work by reversing to a high level through the driving module, and the charge on the capacitor is released through the braking load, so that the power supply voltage is reduced.
According to the calculation formula:
wherein t2 is discharge time, R3 is discharge loop resistance R3, and the larger the resistance is, the slower the discharge time is, and the longer the deceleration time is; C1+C2+C3+C4 is an energy storage capacitor; ln () is the base logarithm of e.
2) And (3) charging:
when the value of the power supply voltage after passing through the voltage dividing module is lower than the set value UTL, the comparison module outputs high level, the power control device is driven to be disconnected by reversing the power supply voltage into low level through the driving module, and the system starts to charge.
According to the calculation formula:
wherein t1 is charging time, V1 is a capacitor charging maximum voltage value of C1-C4, C1+C2+C3+C4 is an energy storage capacitor, ln () is a logarithm of e as a base;
r represents a capacitive reactance, and the capacitive reactance,
wherein f is the rotation frequency of the magnetic suspension molecular pump, and C is the sum of the energy storage capacitors C1+C2+C3+C4.
<Example 2: braking method of magnetic suspension molecular pump>
First case: when the power supply is in a stop state, the power supply voltage is input voltage, the voltage generated by the voltage dividing module is smaller than an upper limit threshold value, the comparison module outputs a high level, the comparison module outputs a low level after passing through the driving module, the control module does not work, and the braking load is not connected.
Second case: during normal operation, as the motor is controlled to work in a time-sharing switching manner by T1, T2, T3, T4, T5 and T6, counter electromotive force generated by the rotating magnetic field cutting coil is absorbed by the motor coil, power voltage is input voltage, voltage generated by the voltage dividing module is smaller than an upper limit threshold value, the comparing module outputs high level, the high level is output after passing through the driving module, the control module is disconnected, a braking load connected with a power supply is disconnected with a power supply cathode, and the braking load does not work.
In the third situation, after the magnetic suspension molecular pump brakes, the power supply voltage is increased due to the back electromotive force generated by the rotating magnetic field cutting coil, the voltage division value after passing through the voltage division network is increased, when the voltage exceeds a set upper limit threshold value, the comparison module outputs a low level, the voltage is converted into a high level through the driving module, the control module is closed, the load connected with the power supply is connected with the negative electrode of the power supply, the braking load works, the generated electric energy is released, and the power supply voltage is reduced.
When the system is in the working process, a shutdown instruction is sent first and the subsequent energy conversion is carried out through the shutdown instruction, after the energy conversion, the capacitor is charged, because the rotational kinetic energy of the magnetic suspension molecular pump is large, the electric energy fed back in the motor braking process can not be absorbed by the energy storage element, so that the voltage is continuously increased, and when the power supply voltage U exceeds the set upper limit value Umax, the voltage module is turned over, as shown in fig. 4. The power control device is driven to work through the driving module, and the electric charge on the capacitor is released through the braking load, so that the power supply voltage U is reduced. When the voltage is lower than the set value lower limit value Umin, the voltage module is turned back to the original state, and the control module is disconnected after passing through the comparison module and the driving module.
In the present application: the negative electrode of the diode D2 is connected with the positive electrode of the diode D1, the negative electrode of the diode D1 is connected with a resistor R1, the other end of the resistor R1 is connected with a resistor R2, and the other end of the resistor R2 is connected to a power supply voltage. The diode D2 is connected with the capacitor C5 in parallel to form a low-pass filter circuit, and the diode D1 and the diode D2 are connected in series and then connected with the capacitor C6 in parallel to form the low-pass filter circuit. The resistor R10 is connected with the resistor R7, the other end of the resistor R7 is connected with the resistor R4, the other end of the resistor R4 is connected with the power supply voltage, and the resistor R10 is connected with the capacitor C7 in parallel to form a low-pass filter circuit. The capacitor C1 is connected in parallel with the capacitor C2 and the capacitor C3 is connected in parallel with the capacitor C4 to form a power supply energy storage circuit. The resistor R5 is connected with the capacitor C8 to form a low-pass filter circuit.
Capacitance C5 is calculated according to the formula:
C5＝1/[2π(R1+R2)F]
capacitance C6 is calculated according to the formula:
C6＝1/[2π(R1+R2)F]
capacitance C7 is calculated according to the formula:
C7＝1/[2π(R4+R7)F]
capacitance C8 is calculated according to the formula:
C8＝1/[2π(R1+R2+R5)F]
wherein the cut-off frequency of the F low pass filter.
Symbol and physical meaning correspondence table
The foregoing has shown and described the basic principles and main features of the present application and the advantages of the present application. It will be understood by those skilled in the art that the present application is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present application, and various changes and modifications may be made without departing from the spirit and scope of the application, which is defined in the appended claims. The scope of the application is defined by the appended claims and equivalents thereof.
Claims (4)
1. A brake circuit for a magnetic levitation molecular pump controller, comprising: resistors R1-R10, diodes D1-D2, capacitors C1-C8, a comparator U1, a driver U2 and a field effect transistor Q1;
the resistors R4, R7 and R10 form a voltage dividing module;
the diodes D1-D2 and C5 form a reference module, and meanwhile, the diode D2 and the capacitor C5 also provide a power supply system for the U2;
the comparator U1, the resistors R6 and R9 form a comparison module;
the driver U2 and the resistor R8 form a driving module;
the field effect tube Q1 and the resistor R3 form a control module of a braking load;
the capacitor C7 and the resistor R10 form a discharge delay system;
the resistor R5 and the capacitor C8 form a power supply filter network;
the connection relation among the voltage dividing module, the reference module, the comparison module, the driving module, the control module, the discharging delay system and the power supply filter network is as follows:
the second end of the resistor R4 is connected with the first end of the resistor R7, and the second end of the resistor R7 is connected with the first end of the resistor R10;
the anode of the diode D1 is connected with the cathode of the diode D2;
the pin 1 of the U1, the first end of the capacitor C7, the first end of the resistor R10 and the second end of the resistor R7 are connected; the pin 2 of the U1, the second end of the capacitor C5, the second end of the capacitor C7, the second end of the resistor R10 and the anode of the diode D2 are connected; the pin 3 of the U1, the second end of the resistor R6 and the first end of the resistor R9 are connected; the pin 4 of the U1 is connected with the second end of the resistor R9; the pin 5 of the U1 is connected with the cathode of the diode D1; the pins 1 to 5 of U1 are respectively: IN-, GND, IN+, OUT+, VCC;
the first end of the resistor R6 is connected with the first end of the resistor R5, the first end of the capacitor C5, the anode of the diode D1 and the cathode of the diode D2;
the pin 1 of the driver U2, the second end of the resistor R5 and the first end of the capacitor C8 are connected; the pin 2 of the U2 is connected with the second end of the capacitor C8, the anode of the diode D2, the second end of the capacitor C5, the second end of the capacitor C6, the second end of the capacitor C7 and the second end of the resistor R10; the pin 3 of the U2 is connected with the first end of the capacitor C8 and the second end of the resistor R5; the pin 4 of the U2 is connected with the second end of the resistor R9 and the pin 4 of the U1; the pin 5 of the U2 is connected with the first end of the resistor R8; the pins 1 to 5 of U2 are respectively: VDD, GND, IN +, IN-, OUT;
the grid electrode of the field effect tube Q1 is connected with the second end of the resistor R8, the drain electrode of the field effect tube Q1 is connected with the resistor R3, and the source electrode of the field effect tube Q1 is grounded;
the capacitors C1-C4 form a magnetic suspension molecular pump power supply filtering energy storage circuit; the capacitors C1-C4 are connected in parallel, and the first ends of the capacitors C1-C4 are connected with the first end of the resistor R3, the second end of the resistor R2 and the first end of the resistor R4; the second ends of the capacitors C1-C4 are connected with the ground, namely the second ends of the capacitors C5-C8;
the resistors R1 and R2, the diodes D1-D2 and the capacitor C6 provide a power supply system for the U1;
the second end of the resistor R1 is connected with the first end of the resistor R2, and the second end of the resistor R2 is connected with the first end of the resistor R4; the first end of the resistor R1 is connected with the negative electrode of the D1, the No. 5 pin of the U1 and the first end of the capacitor C6; the anode of the diode D2 and the second end of the capacitor C6 are connected with the pin 2 of the U1; the No. 2 pin of U1 is connected with the second end of electric capacity C6, and the No. 5 pin of U1 is connected with the first end of electric capacity C6.
2. A brake system of a magnetic levitation molecular pump controller, characterized in that a brake circuit according to claim 1 is used.
3. A braking method of a magnetic suspension molecular pump, characterized in that the braking system as claimed in claim 2 is adopted for braking, and the process of alternately repeating the discharging time t2 and the charging time t1 is adopted for braking;
1) The discharging process comprises the following steps:
when the value of the power supply voltage after passing through the voltage dividing module exceeds a set upper limit threshold UTH, the comparison module outputs a low level; the driving module outputs high level to the control module after reversing the driving module, and the charges on the magnetic suspension molecular pump power supply filtering energy storage circuit are released through a braking load, so that the power supply voltage is reduced;
according to the calculation formula:
wherein t2 is discharge time, and R3 is discharge loop resistance R3; C1+C2+C3+C4 is an energy storage capacitor;
2) And (3) charging:
when the value of the power supply voltage after passing through the voltage dividing module is lower than the lower limit threshold UTL, the comparison module outputs high level, the power control device is driven to be disconnected by the low level after being reversed by the driving module, and the system starts to charge;
according to the calculation formula:
wherein t1 is charging time, V1 is a capacitor charging maximum voltage value of C1-C4, and C1, C2, C3 and C4 are energy storage capacitors;
r represents a capacitive reactance, and the capacitive reactance,
wherein f is the rotation frequency of the magnetic suspension molecular pump, and C is the sum of energy storage capacitors C1, C2, C3 and C4.
4. A method of braking a magnetic molecular pump according to claim 3, wherein UTH, UTL are calculated using the formula:
uref is a reference voltage, that is, a voltage across the diode D2, and Uoh and Uol are high and low levels output from the comparator U1.
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