CN109617396B - Circuit structure and method for realizing long life of electromagnetic forming system based on dual power supply - Google Patents

Abstract

The circuit structure and the method for realizing the long service life of the electromagnetic forming system based on the double power supplies comprise a driving coil and a discharge switch; a capacitive power source for providing energy to the drive coil; the rectifier diode and the charging switch are used for charging the capacitor power supply; a thyristor switch for switching the capacitive power supply; a current detection element for detecting a current of the driving coil; the capacitance power supply comprises a positive capacitance power supply and a negative capacitance power supply; the charging switch comprises a first charging switch and a second charging switch; the rectifier diode comprises a first rectifier diode and a second rectifier diode; the thyristor switch comprises a first thyristor switch and a second thyristor switch. The invention mainly adopts the double power supplies to eliminate the back pressure of the capacitance power supply, reduce the Joule heat dissipated on the driving coil and recover most energy as the energy required by the next electromagnetic forming, thereby realizing the long-life electromagnetic forming system and improving the efficiency of the electromagnetic forming system.

Description

Circuit structure and method for realizing long life of electromagnetic forming system based on dual power supply

technical field

The invention belongs to the field of metal forming manufacturing, in particular to a circuit structure and method for realizing long life of an electromagnetic forming system based on dual power sources, and is mainly used for improving the discharge life of the electromagnetic forming system.

Background technique

Lightweight is an important technical means to achieve energy saving and emission reduction in aerospace, automobile industry and other fields. The main way to achieve lightweight is to use lightweight alloy materials. High-performance aluminum alloys, titanium alloys, and magnesium alloys have become the preferred materials to achieve lightweighting in modern aerospace and automotive industries. Electromagnetic forming is a high-speed pulse forming technology. It can greatly improve the formability of metal materials and is one of the effective means to solve the difficulty of forming lightweight alloys.

In electromagnetic forming, the driving coil is discharged through the capacitor power supply, and a strong pulse current is generated in the driving coil, and at the same time, an induced eddy current is generated in the metal workpiece; the mutual electromagnetic force between the excitation current and the induced current drives the metal workpiece to accelerate and accelerate. Plastic deformation occurs. Obviously, the capacitive power supply and the driving coil are the most important components of electromagnetic forming. In the existing electromagnetic forming technology, a capacitor power source is used as the power source to supply power to the driving coil, and the discharge current is generally a decaying sine wave, and the voltage on the capacitor power source is also a decaying cosine wave. This form of discharge will lead to the following problems: the back pressure of the capacitor power supply is as high as more than 80%, which greatly shortens the life of the capacitor power supply; the drive coil absorbs most of the Joule heat of the power conversion drive coil, resulting in a serious temperature rise of the drive coil, extremely The service life of the capacitive power supply is greatly shortened; at the same time, because most of the energy is dissipated by the drive coil in the form of Joule heat, the efficiency of the entire electromagnetic forming system is low. For example, the patent "An Electromagnetic Forming Device and Method (CN 103817197 B)" discloses an electromagnetic forming device and method. The forming coil is driven to move with the deformation of the workpiece by the driving coil, so that the forming coil is always close to the workpiece, which is the electromagnetic wave of the workpiece. Forming provides continuous electromagnetic force with conformal distribution, which can effectively increase the forming depth of the workpiece and improve the mold fit of the workpiece. However, the pulse current provided by the pulse power supply in this invention is a decaying sine wave, which leads to a short service life of the pulse power supply, and at the same time, severe Joule heating will also lead to the service life of the driving coil and the forming coil. The paper "Analysis and reduction of coiltemperature rise in electromagnetic forming (Journal of Materials ProcessingTechnology 225 (2015) 185–194)" proposes a new circuit to reduce the temperature rise of the drive coil, which uses a freewheeling loop in series with a freewheeling resistor. Transfer part of the Joule heat to the freewheeling resistor to reduce the temperature rise of the coil and improve the life of the drive coil. However, in this method, although the freewheeling loop can reduce the back pressure of the capacitor power supply, it cannot be completely avoided, and it still has a certain impact on the life of the capacitor power supply; at the same time, the energy is dissipated in the freewheeling resistance in the form of Joule heat. Therefore, the electromagnetic forming efficiency is not high.

SUMMARY OF THE INVENTION

The invention provides a circuit structure and a method for realizing long life of an electromagnetic forming system based on dual power supplies, mainly by using dual power supplies to eliminate the back pressure of the capacitive power supply, reduce the Joule heat dissipated on the driving coil, and recover most of the energy as the next electromagnetic shaping The energy required for the electromagnetic forming system can be realized with a long life, and the efficiency of the electromagnetic forming system can be improved.

The technical scheme adopted in the present invention is:

The circuit structure for realizing the long-life of the electromagnetic forming system based on the dual power supply, including the driving coil and the discharge switch, the circuit structure also includes:

Capacitive power supply for powering the drive coil;

Rectifier diode and charging switch for charging the capacitor power supply;

Thyristor switch for switching capacitor power supply;

A current detection element for detecting the current of the drive coil;

The capacitor power supply includes a positive capacitor power supply and a negative capacitor power supply;

The charging switch includes a first charging switch and a second charging switch;

The rectifier diode includes a first rectifier diode and a second rectifier diode;

The thyristor switch includes a first thyristor switch and a second thyristor switch;

One end of the first AC power supply is connected to one end of the first charging switch, the other end of the first charging switch is connected to one end of the first rectifier diode, the other end of the first rectifier diode is connected to one end of the first thyristor switch, and the other end of the first thyristor switch is connected to the forward capacitor power supply One end, the other end of the forward capacitor power supply is connected to the other side of the first AC power supply;

The other end of the first rectifier diode is connected to one end of the discharge switch, the other end of the discharge switch is connected to one end of the drive coil, the other end of the drive coil is connected to one end of the current detection element, and the other end of the current detection element is connected to the other side of the first AC power supply;

The other end of the first rectifier diode is connected to one end of the negative capacitor power supply, the other end of the negative capacitor power supply is connected to one end of the second thyristor switch, and the other end of the second thyristor switch is connected to the other side of the first AC power supply;

The other end of the first rectifier diode is connected to one side of the second AC power source, the other side of the second AC power source is connected to the other end of the second charging switch, one end of the second charging switch is connected to the other end of the second rectifier diode, and one end of the second rectifier diode is connected to the first the other side of the AC power source.

A method for realizing long life of electromagnetic forming system based on dual power supply, comprising the following steps:

S1: Disconnect the discharge switch, the second thyristor switch, and the second charging switch, close the first thyristor switch, close the first charging switch, and use the first rectifier diode to charge the forward capacitor power supply;

S2: When the voltage value of the forward capacitor power supply is U0, turn off the first charging switch to complete the charging of the forward capacitor power supply; close the discharge switch, and the forward capacitor power supply discharges the driving coil to generate a pulse current, and the current detection element is used to measure the current in the driving coil. pulse current;

S3: When the pulse current reaches the first current peak value and di/dt=0, close the second thyristor switch, and then open the first thyristor switch, at this time, the driving coil supplies energy to the negative capacitor power supply;

S4: continue to measure the pulse current, when the pulse current reaches the end of the first half-wave, i=0, turn off the discharge switch to complete the first forward discharge process;

S5: close the second charging switch, and use the second rectifier diode to charge the negative capacitor power supply;

S6: when the voltage value of the negative capacitor power supply is -U0, disconnect the second charging switch to complete the charging of the negative capacitor power supply;

S7: close the discharge switch, the negative capacitor power supply discharges the driving coil to generate a pulse current, and the current detection element is used to measure the pulse current in the driving coil;

S8: When the pulse current reaches the first current peak value and di/dt=0, close the first thyristor switch, and then open the second thyristor switch, at this time, the driving coil supplies energy to the forward capacitor power supply;

S9: continue to measure the pulse current, when the pulse current reaches the end of the first half-wave, i=0, turn off the discharge switch to complete the first negative discharge process;

The above-mentioned positive and negative discharge processes are repeated to achieve long life of the electromagnetic forming system.

The time delay between closing the second thyristor switch and opening the first thyristor switch is less than or equal to 100 microseconds. Too much delay will affect the effect of the device, and too small delay will increase the cost of the device. 100 microseconds is relatively easy to achieve with the current technology without affecting the effect of the device too much.

The time delay between closing the first thyristor switch and opening the second thyristor switch is less than or equal to 100 microseconds. Too much delay will affect the effect of the device, and too small delay will increase the cost of the device. 100 microseconds is relatively easy to achieve with the current technology without affecting the effect of the device too much.

A circuit structure and method for realizing long life of an electromagnetic forming system based on dual power sources of the present invention have the advantages of:

1. The voltage value of the positive capacitor power supply is always positive, and the voltage value of the negative capacitor power supply is always negative. There is no back pressure in the two sets of capacitor power supplies, which greatly improves the life of the capacitor power supply of the electromagnetic forming system;

2. In the single electromagnetic forming, the driving coil only has a half-cycle pulse current, which greatly reduces the Joule heat dissipated on the driving coil, improves the life of the driving coil, and improves the efficiency of the electromagnetic forming system.

Description of drawings

Below in conjunction with accompanying drawing and embodiment, the present invention will be further described:

Figure 1 is a schematic diagram of the circuit structure for realizing long life of the electromagnetic forming system based on dual power sources.

Figure 2 is a schematic diagram of the voltage (Up, Un) of the capacitor power supply and the current (I) of the drive coil.

1. Capacitor power supply; 11. Positive capacitor power supply; 12. Negative capacitor power supply; 2. Thyristor switch; 21. First thyristor switch; 22. Second thyristor switch; 3. Rectifier diode; 31. First rectifier diode; 32. Second rectifier diode; 4. Charging switch; 41. First charging switch; 42. Second charging switch; 5. Discharging switch; 6. Driving coil; 7. Current measuring element.

Detailed ways

The circuit structure for realizing long life of the electromagnetic forming system based on the dual power supply includes the drive coil 6 and the discharge switch 5, and the circuit structure also includes:

Capacitive power supply 1 for providing energy to drive coil 6;

A rectifier diode 3 and a charging switch 4 for charging the capacitor power supply 1;

Thyristor switch 2 for switching capacitor power supply 1;

A current detection element 7 for detecting the current of the driving coil 6; the current detection element 7 adopts a Pearson current probe.

The capacitor power supply 1 includes a positive capacitor power supply 11 and a negative capacitor power supply 12;

The positive capacitance power supply 11 and the negative capacitance power supply 12 are metallized film capacitors, the capacitance value is 10-10000μF, and the capacitance voltage is 1-50kV.

The charging switch 4 includes a first charging switch 41 and a second charging switch 42;

The rectifier diode 3 includes a first rectifier diode 31 and a second rectifier diode 32;

The thyristor switch 2 includes a first thyristor switch 21 and a second thyristor switch 22 .

One end of the first AC power source is connected to one end of the first charging switch 41 , the other end of the first charging switch 41 is connected to one end of the first rectifier diode 31 , the other end of the first rectifier diode 31 is connected to one end of the first thyristor switch 21 , and the other end of the first thyristor switch 21 is connected. One end is connected to one end of the forward capacitor power supply 11, and the other end of the forward capacitor power supply 11 is connected to the other side of the first AC power supply;

The other end of the first rectifier diode 31 is connected to one end of the discharge switch 5, the other end of the discharge switch 5 is connected to one end of the drive coil 6, the other end of the drive coil 6 is connected to one end of the current detection element 7, and the other end of the current detection element 7 is connected to the other side of the first AC power supply ;

The other end of the first rectifier diode 31 is connected to one end of the negative capacitor power supply 12, the other end of the negative capacitor power supply 12 is connected to one end of the second thyristor switch 22, and the other end of the second thyristor switch 22 is connected to the other side of the first AC power supply;

The other end of the first rectifier diode 31 is connected to one side of the second AC power source, the other end of the second AC power source is connected to the other end of the second charging switch 42, one end of the second charging switch 42 is connected to the other end of the second rectifier diode 32, and the second rectifier diode One end of 32 is connected to the other side of the first AC power source.

Parameters of the first AC power supply and the second AC power supply: 380V, 50Hz.

Example:

Figure 1 is a schematic diagram of the circuit structure for realizing long life of the electromagnetic forming system based on dual power sources.

Figure 2 is a schematic diagram of the voltage (Up, Un) of the capacitor power supply and the current (I) of the driving coil, where Up is the positive capacitor power supply voltage, and Un is the negative capacitor power supply voltage.

Set up the electromagnetic forming system as described in Figure 1. The driving coil, the discharge switch and the current detection element are connected in series; the positive capacitor power supply is connected in series with the first thyristor switch; the negative capacitor power supply is connected in series with the second thyristor switch; and then the three are connected in parallel together. The first charging switch and the first rectifying diode are used to charge the positive capacitive power supply; the second charging switch and the second rectifying diode are used to charge the negative capacitive power supply. In the initial state, the discharge switch, the first thyristor switch, the second thyristor switch, the first charging switch, and the second charging switch are disconnected; at time 0, the first thyristor switch is closed, the first charging switch is closed, and the first rectifier diode is used. Charge the forward capacitor power supply; at time T1, the voltage value of the forward capacitor power supply is charged to the set value U0, and the first charging switch is turned off to complete the charging of the forward capacitor power supply; at time T2, the discharge switch is closed, and the forward capacitor power supply is The discharge of the drive coil generates a pulse current, and the current detection element is used to measure the pulse current in the drive coil; at time T3, it is detected that the pulse current reaches the first current peak value (di/dt=0), the second thyristor switch is closed, and then disconnected The first thyristor switch, at this time, the drive coil supplies energy to the negative capacitor power supply; at time T4, it is detected that the pulse current reaches the end of the first half-wave (i=0), and the discharge switch is turned off to complete the first positive discharge. At this time, the voltage value of the negative capacitor power supply is -U1; at time T5, the second charging switch is closed, and the second rectifier diode is used to charge the negative capacitor power supply; at time T6, the voltage value of the negative capacitor power supply is charged to the set value. When the value is set to -U0, the second charging switch is disconnected to complete the charging of the negative capacitor power supply; at time T7, the discharge switch is closed, and the negative capacitor power supply discharges the driving coil to generate a pulse current, and the current detection element is used to measure the pulse current in the driving coil; At time T8, it is detected that the pulse current reaches the first current peak value (di/dt=0), the first thyristor switch is closed, and then the second thyristor switch is turned off. At this time, the driving coil supplies energy to the forward capacitor power supply; at time T9 When it is detected that the pulse current reaches the end of the first half-wave (i=0), the discharge switch is turned off to complete the first negative discharge process. At this time, the voltage value of the positive capacitor power supply is U1; repeat the above positive, Negative discharge process to achieve long life of electromagnetic forming system. Obviously, the voltage value of the positive capacitor power supply is always positive, and the voltage value of the negative capacitor power supply is always negative. There is no back pressure in the two sets of capacitor power supplies, which can improve the service life of the capacitor power supply. , the pulse current of the drive coil is only half-wave pulse, which can effectively reduce the temperature rise of the drive coil and provide the service life of the drive coil. Thereby a long life of the electromagnetic forming system is achieved.

Claims (3)

1. A method for realizing a long life of an electromagnetic forming system based on dual power sources, characterized by comprising a circuit structure, the circuit structure comprising a drive coil (6) and a discharge switch (5), the circuit structure further comprising: a capacitive power supply (1) for providing energy to the drive coil (6); a rectifier diode (3) and a charging switch (4) for charging the capacitor power supply (1); a thyristor switch (2) for switching the capacitive power supply (1); a current detection element (7) for detecting the current of the driving coil (6); The capacitive power supply (1) includes a positive capacitive power supply (11) and a negative capacitive power supply (12); The charging switch (4) includes a first charging switch (41) and a second charging switch (42); The rectifier diode (3) includes a first rectifier diode (31) and a second rectifier diode (32); The thyristor switch (2) includes a first thyristor switch (21) and a second thyristor switch (22); One end of the first AC power supply is connected to one end of the first charging switch (41), the other end of the first charging switch (41) is connected to one end of the first rectifier diode (31), and the other end of the first rectifier diode (31) is connected to the first thyristor switch ( 21) One end, the other end of the first thyristor switch (21) is connected to one end of the forward capacitor power supply (11), and the other end of the forward capacitor power supply (11) is connected to the other side of the first AC power supply; The other end of the first rectifier diode (31) is connected to one end of the discharge switch (5), the other end of the discharge switch (5) is connected to one end of the drive coil (6), the other end of the drive coil (6) is connected to one end of the current detection element (7), and the current detection The other end of the element (7) is connected to the other side of the first AC power supply; The other end of the first rectifier diode (31) is connected to one end of the negative capacitor power supply (12), the other end of the negative capacitor power supply (12) is connected to one end of the second thyristor switch (22), and the other end of the second thyristor switch (22) is connected to the first the other side of the AC power supply; The other end of the first rectifier diode (31) is connected to one side of the second AC power source, the other end of the second AC power source is connected to the other end of the second charging switch (42), and one end of the second charging switch (42) is connected to the second rectifier diode (32) ) at the other end, one end of the second rectifier diode (32) is connected to the other side of the first AC power supply; A method for realizing long life of an electromagnetic forming system, comprising the following steps: S1: Disconnect the discharge switch, the second thyristor switch, and the second charging switch, close the first thyristor switch, close the first charging switch, and use the first rectifier diode to charge the forward capacitor power supply; S2: When the voltage value of the forward capacitor power supply is U0, turn off the first charging switch to complete the charging of the forward capacitor power supply; close the discharge switch, and the forward capacitor power supply discharges the driving coil to generate a pulse current, and the current detection element is used to measure the current in the driving coil. pulse current; S3: When the pulse current reaches the first current peak value and di/dt=0, close the second thyristor switch, and then open the first thyristor switch, at this time, the driving coil supplies energy to the negative capacitor power supply; S4: continue to measure the pulse current, when the pulse current reaches the end of the first half-wave, i=0, turn off the discharge switch to complete the first forward discharge process; S5: close the second charging switch, and use the second rectifier diode to charge the negative capacitor power supply; S6: when the voltage value of the negative capacitor power supply is -U0, turn off the second charging switch to complete the charging of the negative capacitor power supply; S7: close the discharge switch, the negative capacitor power supply discharges the driving coil to generate a pulse current, and the current detection element is used to measure the pulse current in the driving coil; S8: When the pulse current reaches the first current peak value and di/dt=0, close the first thyristor switch, and then open the second thyristor switch, at this time, the driving coil supplies energy to the forward capacitor power supply; S9: continue to measure the pulse current, when the pulse current reaches the end of the first half-wave, i=0, turn off the discharge switch to complete the first negative discharge process; The above-mentioned positive and negative discharge processes are repeated to achieve long life of the electromagnetic forming system. 2 . The method according to claim 1 , wherein the time delay between closing the second thyristor switch and opening the first thyristor switch is less than or equal to 100 microseconds. 3 . 3 . The method for realizing long life of an electromagnetic forming system based on dual power sources according to claim 1 , wherein the time delay between closing the first thyristor switch and opening the second thyristor switch is less than or equal to 100 microseconds. 4 .

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