Magnetic resistance type electromagnetic coil transmitting system

Abstract

The invention provides a magnetic resistance type electromagnetic coil transmitting system, which comprises a driving circuit which adopts a bridge circuit comprising a high-side switch, a low-side switch and two freewheel diodes; an energy storage element using a capacitor having an initial voltage; the driving coil is equivalent to an inductance element in the circuit; wherein the working states of the driving circuit comprise a capacitor charging state, all switches in the circuit are turned off, and the capacitor is charged to a preset value through an external booster circuit; in the charging state of the driving coil, all switches are turned on, the capacitor discharges to the driving coil, and the current of the driving coil rises and generates a magnetic field; in a freewheeling state, the capacitor finishes discharging and the voltage is zero, the switch is still switched on, and the current of the driving coil passes through a freewheeling diode for freewheeling; when the driving coil is in an energy attenuation state, the switch is switched off, the coil follow current loop is cut off, and the capacitor is recharged through the follow current diode. According to the invention, energy recovery and driving coil current rapid drop are realized, and the problem of capture effect caused by current cut-off or slow attenuation is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic emission, and in particular relates to a reluctance type electromagnetic coil emission system. Background Art

[0002] A coil-type electromagnetic transmitter refers to a transmitter that uses a magnetic field generated by an alternating current or a pulse current to drive a projectile with a coil or magnetic material. It is composed of an energy storage element, a drive circuit, a drive coil, and an armature. For a traditional reluctance type electromagnetic coil launch system, its working process is: the pulse source used to store energy forms a large current in the drive coil through the drive circuit, and the large current forms a strong magnetic field inside the drive coil. The armature is magnetized under the action of the strong magnetic field, and then pulled by the strong magnetic field to accelerate the armature. Usually, a multi-stage drive coil acceleration method is used to achieve a better acceleration effect.

[0003] However, in the process of armature acceleration in the traditional reluctance electromagnetic coil transmitting system, the armature tends to move in the direction of the lowest magnetic resistance. For the magnetic field generated by a single coil, the lowest point of magnetic resistance is located at the exact center of the driving coil. This also means that when the armature passes through the exact center of the coil, if there is still a large current inside the driving coil at this time, or the magnetic field generated by the driving coil still exists, the direction of the force on the armature will be reversed, causing the armature to decrease in speed. This effect is called the capture effect. For the capture effect, there are two solutions to the traditional reluctance electromagnetic coil transmitting system. One is to directly cut off the current. However, due to the existence of the self-inductance of the driving coil, any attempt to change the direction of the current inside the driving coil or cut off the current of the driving coil will cause a very large induced voltage, leading to problems such as burning of the switching device and strong arc erosion; the second is to reduce the remaining magnetic field energy (or current) inside the coil at a faster rate. According to the release direction of the magnetic field energy, it can be divided into two methods: releasing the energy in the form of Joule heat and recovering the energy. Regardless of the method, there is a problem of slow magnetic field energy release speed (coil current drop speed), resulting in the capture effect still causing a certain deceleration effect. Summary of the invention

[0004] The present invention aims at the deficiencies in the prior art and provides a reluctance type electromagnetic coil transmitting system.

[0005] The present invention provides a reluctance type electromagnetic coil transmitting system, comprising:

[0006] The driving circuit adopts a bridge circuit including a high-side switch, a low-side switch and two freewheeling diodes;

[0007] Energy storage element, using a capacitor with an initial voltage;

[0008] The driving coil is equivalent to the inductor element in the circuit;

[0009] Wherein, the working state of the driving circuit includes:

[0010] In the capacitor charging state, all switches in the circuit are turned off, and the capacitor is charged to a preset value through an external boost circuit;

[0011] The drive coil is in the charging state, all switches are turned on, the capacitor discharges to the drive coil, the drive coil current increases and generates a magnetic field;

[0012] In the freewheeling state, the capacitor is discharged and the voltage is 0, the switch is still on, and the drive coil current flows through the freewheeling diode;

[0013] The drive coil enters the energy decay state, the switch is turned off, the coil freewheeling loop is cut off, and the capacitor is recharged through the freewheeling diode.

[0014] Optionally, in the driving coil charging state, the circuit equation satisfies:

[0015]

[0016] Among them, L is the equivalent inductance of the driving coil; C is the capacitance; R L is the resistance of the driving coil; R C is the capacitor equivalent series resistance; U C (t) is the capacitor voltage; t is time.

[0017] Optionally, in the freewheeling state, the circuit equation satisfies:

[0018]

[0019] Where, L is the equivalent inductance of the driving coil; I1(t) and I2(t) are currents in different paths; I L (t) is the driving coil current; R L is the resistance of the driving coil; t is the time.

[0020] Optionally, in the energy decay state of the driving coil, the circuit equation satisfies:

[0021]

[0022] Where, L is the equivalent inductance of the driving coil; R L is the resistance of the driving coil; R C is the capacitor equivalent series resistance; I L (t) is the driving coil current; C is the capacitance; t is the time.

[0023] Optionally, the heat loss power P of the driving circuit satisfies:

[0024] P=(I L (t)) 2 (R L +R C ).

[0025] Optionally, it also includes:

[0026] Construct a cascadeable circuit structure, connect multiple bridge drive circuits, and use large capacitors in parallel to supply energy.

[0027] Optionally, in the cascadeable circuit structure, the circuit equation of the first loop is:

[0028]

[0029] The circuit equation for the second loop is:

[0030]

[0031] Among them, R L1 is the resistance of the driving coil in the first loop; R IGBT is the equivalent resistance of IGBT; L1 is the equivalent inductance of the driving coil in the first loop; I1 is the current of the first loop; I2 is the current of the second loop; M 12 is the mutual inductance between the two coils; S1 represents the circuit state of the first loop. When S1=0, the first loop is in the freewheeling state; when S1=1, the first loop is in the coil charging state; when S1=-1, the first loop is in the energy recovery state; V0 is the actual voltage across the capacitor; V Dio is the conduction voltage drop of the diode; S2 represents the circuit state of the second loop. When S2=0, the second loop is in the freewheeling state; when S2=1, the second loop is in the coil charging state; when S2=-1, the second loop is in the energy recovery state; t represents time; U P1 is the induced voltage generated by the projectile on the driving coil of the first circuit; U P2 It is the induced voltage generated by the projectile on the driving coil of the second circuit.

[0032] The present invention provides a reluctance type electromagnetic coil transmitting system, including a driving circuit, using a bridge circuit including a high-side switch, a low-side switch and two freewheeling diodes; an energy storage element, using a capacitor with an initial voltage; a driving coil, which is equivalent to an inductor element in the circuit; wherein the working state of the driving circuit includes: a capacitor charging state, in which all switches in the circuit are turned off, and the capacitor is charged to a preset value through an external boost circuit; a driving coil charging state, in which all switches are turned on, the capacitor discharges to the driving coil, the driving coil current rises and generates a magnetic field; a freewheeling state, in which the capacitor is discharged and the voltage is 0, the switch is still turned on, and the driving coil current is freewheeling through the freewheeling diode; a driving coil energy decay state, in which the switch is turned off, the coil freewheeling loop is cut off, and the capacitor is recharged through the freewheeling diode. The present invention realizes energy recovery and rapid decrease of the driving coil current by adopting a bridge circuit structure and optimizing the working state control, effectively solving the capture effect problem caused by current cut-off or slow decay in the traditional system, and improving the acceleration efficiency of the armature. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A schematic structural diagram of a reluctance type electromagnetic coil transmitting system provided by an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of the structure of a bridge drive circuit provided by an embodiment of the present invention;

[0036] Figure 3 A schematic diagram of the structure of a two-stage cascade bridge drive circuit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] like Figure 1 As shown, this embodiment provides a reluctance type electromagnetic coil transmitting system, comprising:

[0040] The driving circuit 10 adopts a bridge circuit including a high-side switch, a low-side switch and two freewheeling diodes.

[0041] The energy storage element 20 uses a capacitor having an initial voltage.

[0042] The driving coil 30 is equivalent to an inductor element in the circuit.

[0043] like Figure 2 As shown in the figure, a bridge circuit is used to achieve energy recovery and rapid drop of the driving coil current. Figure 1 As shown in the figure, the circuit includes two switches, two freewheeling diodes, an inductor equivalent to the driving coil, and a capacitor that acts as an energy storage element. The remaining resistors are loop resistors.

[0044] When the working state of the driving circuit is the capacitor charging state, all switches in the circuit are turned off, and the capacitor is charged through an external boost circuit until the voltage of the capacitor reaches a preset value.

[0045] When the driving circuit is in the state of charging the driving coil, all switches in the circuit are turned on, the capacitor discharges to the driving coil, the current in the driving coil rises rapidly, and a magnetic field is generated inside it, pulling the armature forward. At this time, the circuit equation satisfies:

[0046]

[0047] Among them, L is the equivalent inductance of the driving coil; C is the capacitance; R L is the resistance of the driving coil; R C is the capacitor equivalent series resistance; U C (t) is the capacitor voltage; t is time.

[0048] When the working state of the driving circuit is the freewheeling state, when the capacitor is discharged, the capacitor voltage is 0 and the two switches are still in the on state, the current in the driving coil will be freewheeling through the two freewheeling diodes. At this time, the circuit equation satisfies:

[0049]

[0050] Where, L is the equivalent inductance of the driving coil; I1(t) and I2(t) are currents in different paths; I L (t) is the driving coil current; R L is the resistance of the driving coil; t is the time.

[0051] When the working state of the driving circuit is the energy decay state of the driving coil, the two switches are turned off, the original freewheeling loop of the coil will be cut off, and the capacitor will be recharged through the freewheeling diode. At this time, the circuit equation satisfies:

[0052]

[0053] Where, L is the equivalent inductance of the driving coil; R L is the resistance of the driving coil; R C is the capacitor equivalent series resistance; I L (t) is the driving coil current; C is the capacitance; t is the time.

[0054] In the above four states, the heat loss power P of the drive circuit satisfies:

[0055] P=(I L (t)) 2 (R L +R C ).

[0056] The speed at which the energy of the drive coil decays is related to the damping coefficient in the circuit. The damping coefficient ζ is:

[0057]

[0058] The smaller the damping, the slower the decay rate, and the larger the damping, the faster the decay rate.

[0059] From the above analysis, it can be seen that the heat loss power and damping coefficient of the drive circuit are both related to the equivalent impedance in the loop. When the armature is already in severe magnetic saturation, the tension on the armature is approximately proportional to the current, while the relationship between heat loss and current is a square relationship. Normally, the current will reach hundreds of amperes, which means that although increasing the force on the armature by increasing the current can indeed improve the acceleration effect, the overall launch efficiency of the system will be significantly reduced. Therefore, in order to ensure the overall launch efficiency of the system, while ensuring that the armature is still in severe magnetic saturation, the resistance of the drive coil can be appropriately increased. The specific method is to reduce the wire diameter of the drive coil and increase the number of turns of the drive coil.

[0060] In addition, the damping coefficient is also related to the capacitance value of the capacitor, so multiple large capacitors can be connected in parallel to increase the capacitance value, thereby ensuring the rapid attenuation of the drive coil energy. Multiple capacitors connected in parallel can not only reduce the equivalent series resistance (ESR) inside a single capacitor, but also reduce its equivalent series inductance, thereby improving the discharge capacity of the capacitor itself.

[0061] like Figure 3 As shown, a simple two-stage cascade circuit is shown. Figure 3The circuit in the figure connects two bridge drive circuits that were originally powered by a single capacitor, and replaces the single capacitor with a large capacitor formed by connecting the two original capacitors in parallel. In the two-stage cascade bridge drive circuit, the circuit is divided into the first loop and the second loop. S11 and S12, S21 and S22 are all IGBTs. Let the state of S11 and S12 be S1. When S1=1, the coil is energized; S1=0, the coil continues to flow; S1=-1, energy is recovered. The state of S21 and S22 is the same. The current direction of I1 and I2 is from left to right. Among them,

[0062] The circuit equation for the first loop is:

[0063]

[0064] The circuit equation for the second loop is:

[0065]

[0066] Among them, R L1 is the resistance of the driving coil in the first loop; R IGBT is the equivalent resistance of the IGBT; L1 is the equivalent inductance of the driving coil in the first loop; I1 is the current of the first loop; I2 is the current of the first loop; L1 is the equivalent inductance of the driving coil in the first loop; L2 is the equivalent inductance of the driving coil in the second loop; M 12 is the mutual inductance between the two coils; S1 represents the circuit state of the first loop. When S1=0, the first loop is in the freewheeling state; when S1=1, the first loop is in the coil charging state; when S1=-1, the first loop is in the energy recovery state; V0 is the actual voltage across the capacitor; V Dio is the conduction voltage drop of the diode; S2 represents the circuit state of the second loop. When S2=0, the second loop is in the freewheeling state; when S2=1, the second loop is in the coil charging state; when S2=-1, the second loop is in the energy recovery state; t represents time; U P1 is the induced voltage generated by the projectile on the driving coil of the first circuit; U P2 is the induced voltage generated by the projectile on the driving coil of the second circuit. is the inductor voltage; is the mutual inductance between the two coils.

[0067] Let L = L S N2; L S is the single-turn self-inductance; M 12 =M S ·N1·N2;M S is the single-turn mutual inductance; N1·N2 is the product of the number of turns of the two coils; R=R S N2; R S is the single turn resistance.

[0068] Substituting into the circuit equation of the first loop, we get:

[0069]

[0070] Substituting into the circuit equation of the second loop, we get:

[0071]

[0072] For capacitors:

[0073] V0+R C (S1I1+S2I2)=V C ;

[0074]

[0075] V C is the capacitor voltage; for the induced voltage of the projectile in the circuit, the energy conservation relationship shows that the energy obtained by the projectile in the magnetic field is equal to the coil energy loss caused by the induced voltage. Assume that the force exerted by the unit current on the projectile in each turn of the coil is F S , this force is obviously related to the relative position of the projectile and the coil, and assuming that the length of the single-stage coil is D, we can get:

[0076]

[0077] The induced voltage is:

[0078]

[0079] in, is the current position of the projectile; is the position of the first circuit driving coil; is the position of the second circuit driving coil; v p is the current velocity of the projectile; and It reflects the relationship between the current projectile position and the two coils, and has is the coil length.

[0080] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A reluctance type electromagnetic coil transmitting system, characterized in that: include: The driving circuit adopts a bridge circuit including a high-side switch, a low-side switch and two freewheeling diodes; Energy storage element, using a capacitor with an initial voltage; The driving coil is equivalent to the inductor element in the circuit; Wherein, the working state of the driving circuit includes: In the capacitor charging state, all switches in the circuit are turned off, and the capacitor is charged to a preset value through an external boost circuit; The drive coil is in the charging state, all switches are turned on, the capacitor discharges to the drive coil, the drive coil current increases and generates a magnetic field; In the freewheeling state, the capacitor is discharged and the voltage is 0, the switch is still on, and the drive coil current flows through the freewheeling diode; The drive coil enters the energy decay state, the switch is turned off, the coil freewheeling loop is cut off, and the capacitor is recharged through the freewheeling diode.

2. The reluctance type electromagnetic coil transmitting system according to claim 1, characterized in that: In the driving coil charging state, the circuit equation satisfies: Among them, L is the equivalent inductance of the driving coil; C is the capacitance; R L is the resistance of the driving coil; R C is the capacitor equivalent series resistance; U C (t) is the capacitor voltage; t is time.

3. The reluctance type electromagnetic coil transmitting system according to claim 1, characterized in that: In the freewheeling state, the circuit equation satisfies: Where, L is the equivalent inductance of the driving coil; I1(t) and I2(t) are currents in different paths; I L (t) is the driving coil current; R L is the resistance of the driving coil; t is the time.

4. The reluctance type electromagnetic coil transmitting system according to claim 1, characterized in that: In the energy decay state of the driving coil, the circuit equation satisfies: Where, L is the equivalent inductance of the driving coil; R L is the resistance of the driving coil; R C is the capacitor equivalent series resistance; I L (t) is the driving coil current; C is the capacitance; t is the time.

5. The reluctance type electromagnetic coil transmitting system according to claim 4, characterized in that: The heat loss power P of the driving circuit satisfies: P=(I L (t)) 2 (R L +R C )。 6. The reluctance type electromagnetic coil transmitting system according to claim 1, characterized in that: Also includes: Construct a cascadeable circuit structure, connect multiple bridge drive circuits, and use large capacitors in parallel to supply energy.

7. The reluctance type electromagnetic coil transmitting system according to claim 6, characterized in that: In the cascadeable circuit structure, the circuit equation of the first loop is: The circuit equation for the second loop is: Among them, R L1 is the resistance of the driving coil in the first loop; R IGBT is the equivalent resistance of IGBT; L1 is the equivalent inductance of the driving coil in the first loop; I1 is the current of the first loop; I2 is the current of the second loop; M 12 is the mutual inductance between the two coils; S1 represents the circuit state of the first loop. When S1=0, the first loop is in the freewheeling state; when S1=1, the first loop is in the coil charging state; when S1=-1, the first loop is in the energy recovery state; V0 is the actual voltage across the capacitor; V Dio is the conduction voltage drop of the diode; S2 represents the circuit state of the second loop. When S2=0, the second loop is in the freewheeling state; when S2=1, the second loop is in the coil charging state; when S2=-1, the second loop is in the energy recovery state; t represents time; U P1 is the induced voltage generated by the projectile on the driving coil of the first circuit; U P2 It is the induced voltage generated by the projectile on the driving coil of the second circuit.

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