Charging and discharging circuit of magnetizer
By designing the charging and discharging circuit of the magnetizer, the problem of heat accumulation caused by the high-frequency operation of the magnetizer is solved, and rapid charging and discharging and accurate detection of current peak are achieved to ensure stable operation of the equipment.
Patent Information
- Application Number
- CN202510880846.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-09-26
AI Technical Summary
The magnetizer's high-frequency operation causes heat accumulation due to current fluctuations, which can lead to device damage, especially in devices with insufficient heat dissipation design.
A charging and discharging circuit for a magnetizer was designed, including a voltage-boosting circuit, a rectifier circuit, a capacitor group circuit, a dual-path discharge control circuit, and a current detection circuit. By precisely controlling the voltage and current, rapid charging and discharging can be achieved to avoid heat accumulation.
It achieves a fast charge and discharge cycle, avoids the temperature rise of power devices, ensures stable operation of equipment, and accurately detects current peak values.
Smart Images
Figure CN120710165A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of circuits, in particular to a charging and discharging circuit of a magnetizer. Background Art
[0002] The principle of capacitor pulse magnetization is to charge a capacitor with a high DC voltage and then discharge it through a coil with minimal resistance. The peak discharge pulse current can reach 15,000 amperes. The current pulse generates a strong magnetic field within the coil, which permanently magnetizes the hard magnetic material placed in the coil. During operation, capacitors in magnetizers are subject to extreme pulse current shocks, with peak currents often reaching tens of thousands of amperes. This places stringent demands on the capacitor's transient current handling capability. Because the magnetization process requires the rapid establishment of a high-intensity magnetic field, the system must release energy in a very short period of time, resulting in capacitors experiencing severe current fluctuations during each charge and discharge cycle.
[0003] To improve production efficiency, modern magnetizing equipment generally utilizes ultra-short charge and discharge cycles of less than three seconds. This high-frequency operation triggers a dual thermal effect: first, Joule heating of the capacitor's internal resistance due to the pulsed current; second, switching losses in the associated power switching devices due to the high frequency of switching. The combination of these two heat sources creates localized heat accumulation. Especially in compact equipment with inadequate heat dissipation, the surface temperature of core components can quickly exceed safety thresholds, ultimately damaging parts of the equipment. Summary of the Invention
[0004] In order to solve the above problems, the purpose of the present invention is to provide a magnetizer charging and discharging circuit that can achieve a short charging and discharging cycle, avoid temperature rise of power devices and accurately control the charging voltage of the capacitor bank.
[0005] Based on this, the present invention provides a magnetizer charging and discharging circuit, the circuit comprising: A charging and discharging circuit and a current detection circuit connected in sequence, wherein the charging and discharging circuit is used to make the magnetizing coil generate a magnetic field, and the current detection circuit is used to detect the discharge peak current in the charging and discharging circuit; The charging and discharging circuit includes: a voltage regulating and boosting circuit, a rectifier circuit, a capacitor bank circuit, a dual-path discharge control circuit, a magnetizing coil and a current transformer connected in sequence; The current detection circuit includes: an inductive resistor, a voltage comparator, a voltage follower and a discharge controller which are connected in sequence.
[0006] Wherein, the voltage regulating and boosting circuit comprises: PLC voltage output module, voltage regulation module, AC 220V input module and step-up transformer; The PLC voltage output module is connected to the voltage regulating module and the AC 220V input module respectively. The voltage regulating module and the AC 220V input module are both connected to the input end of the step-up transformer. The output end of the step-up transformer is connected to the rectifier circuit.
[0007] Wherein, the capacitor bank circuit includes: The capacitor group circuit is composed of a first number of capacitor groups connected in parallel, wherein there is a capacitor group composed of a second number of capacitors connected in sequence, and there is a capacitor group composed of a second number of capacitors and capacity switching switches connected in sequence.
[0008] Wherein, the dual-path discharge control circuit includes: PLC dual-circuit discharge control circuit, second discharge thyristor and third discharge thyristor; One end of the second discharge thyristor and one end of the third discharge thyristor are both connected to the capacitor group circuit, and the other two ends of the second discharge thyristor and the other two ends of the third discharge thyristor are connected to the output ends of the corresponding PLC dual-path discharge control circuit.
[0009] The capacitor group circuit is further connected to a first capacitor and a second resistor in sequence, and the second resistor is further connected to one end of the magnetizing coil.
[0010] The voltage comparator and the voltage follower are of the model UA741CP.
[0011] The output end of the voltage comparator is connected to the anode of the sixth diode, the cathode of the sixth diode is respectively connected to one end of the second capacitor and the input end of the voltage follower, and the other end of the second capacitor is grounded.
[0012] Among them, the cathode of the sixth diode is also connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the collector of the transistor, the emitter of the transistor is grounded, the base of the transistor is connected to one end of the sixth resistor, and one end of the sixth resistor is connected to the discharge controller.
[0013] The circuit further includes a fifth diode, the cathode of the fifth diode is connected to one end of the magnetizing coil, and the anode of the fifth diode is connected to one end of the current transformer.
[0014] The voltage regulating module adopts a control method of changing the pressure value in time periods, and the control curve function includes Y=0.75+4.25x.
[0015] In the present invention, a new type of voltage regulating module is used in the charge and discharge circuit, which makes the circuit control more accurate and convenient. It can use a weak control signal (a few milliamperes to tens of milliamperes) to control the current load from 0.1A to several hundred amperes, and perform contactless connection or disconnection. It works reliably, is contactless, spark-free, has a long service life, is noiseless, has a fast switching speed, is highly anti-interference, and is small in size. It is resistant to vibration, impact, explosion-proof, moisture-proof, and corrosion-resistant. The core principle of the magnetizer is to generate a high-intensity magnetic field in the coil through an excitation current, so that the hard magnetic material is permanently magnetized. According to the working principle, it is divided into two types: constant current magnetizer and pulse magnetizer. The present invention is a pulse type. The pulse type can generate an instantaneous current of up to tens of thousands of amperes. At the same time, the discharge time is very short, generally between a few milliseconds and tens of milliseconds, so it is difficult to detect. To measure the discharge current, the peak detection circuit of the present invention can accurately detect the discharge current. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0017] Figure 1 Schematic diagram of a charging and discharging circuit of a magnetizer provided in an embodiment of the present invention; Figure 2 is a schematic diagram of a charge and discharge circuit provided by an embodiment of the present invention; Figure 3 is a schematic diagram of a current detection circuit provided by an embodiment of the present invention; Figure 4 Schematic diagram of a voltage control curve of a voltage regulating module provided in an embodiment of the present invention; Figure 5 Schematic diagram of the charge and discharge curve provided by an embodiment of the present invention. DETAILED DESCRIPTION
[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.
[0019] Figure 1 Schematic diagram of a charging and discharging circuit of a magnetizer provided in an embodiment of the present invention, the circuit comprising: A charge-discharge circuit 101 and a current detection circuit 102 connected in sequence, wherein the charge-discharge circuit is used to make the magnetizing coil generate a magnetic field, and the current detection circuit is used to detect the discharge peak current in the charge-discharge circuit; The charging and discharging circuit includes: a voltage regulating and boosting circuit, a rectifier circuit, a capacitor bank circuit, a dual-path discharge control circuit, a magnetizing coil and a current transformer connected in sequence; The current detection circuit includes: an inductive resistor, a voltage comparator, a voltage follower and a discharge controller which are connected in sequence.
[0020] Figure 2 This is a schematic diagram of the charge and discharge circuit provided by the embodiment of the present invention, please refer to Figure 2 , the voltage regulating and boosting circuit comprises: PLC voltage output module, voltage regulation module, AC 220V input module and step-up transformer; The PLC voltage output module is connected to the voltage regulating module and the AC 220V input module respectively. The voltage regulating module and the AC 220V input module are both connected to the input end of the step-up transformer. The output end of the step-up transformer is connected to the rectifier circuit.
[0021] The PLC voltage output module, model SM1232AQ2, is used to output an adjustable analog control voltage between 0 and 5V. This analog control voltage controls the output conduction angle of voltage regulator module Q1, adjusting the voltage on the primary winding of step-up transformer U1 and, in turn, the voltage on the secondary winding of the step-up transformer. The voltage signal boosted by the step-up transformer is converted into high-voltage pulsating direct current through a rectifier circuit consisting of diodes D1, D2, D3, and D4.
[0022] The PLC voltage output module outputs a control voltage of 0-5V, which corresponds to a conduction angle of 0-180° of the voltage regulating module. The larger the conduction angle, the greater the output voltage. The 0-5V voltage can control the voltage applied to the primary coil of the transformer from 0V to 220V.
[0023] The ratio of the primary coil to the secondary coil of the step-up transformer is 1:10, the primary voltage is 220 V, and the secondary voltage is stepped up to 2200 V. The step-up transformer is a non-standard part and is generally customized or self-wound according to requirements.
[0024] A current-limiting resistor R1 is further connected in series between the rectifier circuit and the capacitor group circuit.
[0025] The high-voltage pulsating direct current is limited by the current-limiting resistor R1 and supplies power to the nine large-capacity and high-voltage capacitors U2-U10, namely the capacitor group circuit.
[0026] Wherein, the capacitor bank circuit includes: The capacitor group circuit is composed of a first number of capacitor groups connected in parallel, wherein there is a capacitor group composed of a second number of capacitors connected in sequence, and there is a capacitor group composed of a second number of capacitors and capacity switching switches connected in sequence.
[0027] Specifically, the first number can be three, the second number can also be three, and the capacitance is 1000uF. The capacitance switch can be used to select single group operation, two groups operation, or three groups operation at the same time to meet different magnetization energy requirements.
[0028] The capacity of the energy storage capacitor is 1000uF. The single group of capacitors is connected in series, so the capacity of each group is 333uF. The three groups are connected in parallel. According to the energy storage formula W=1 / 2 (U 2 C), where the formula describes the electrical energy W stored in a capacitor under voltage U, where C is the capacitance. The more groups there are, the greater the stored energy. During operation, capacitors with different numbers of groups can store different amounts of energy to meet different magnetizing energy requirements.
[0029] Wherein, the dual-path discharge control circuit includes: PLC dual-circuit discharge control circuit, second discharge thyristor and third discharge thyristor; One end of the second discharge thyristor and one end of the third discharge thyristor are both connected to the capacitor group circuit, and the other two ends of the second discharge thyristor and the other two ends of the third discharge thyristor are connected to the output ends of the corresponding PLC dual-path discharge control circuit.
[0030] In order to ensure the reliability of discharge and improve the discharge capacity, the PLC dual-channel discharge control circuit outputs a control signal to simultaneously turn on the second discharge thyristor Q2 and the third discharge thyristor Q3 to discharge the magnetizing coil.
[0031] The capacitor group circuit is further connected to a first capacitor and a second resistor in sequence, and the second resistor is further connected to one end of the magnetizing coil.
[0032] The first capacitor C1 and the second resistor R2 function to filter out high-frequency noise in the circuit.
[0033] The circuit further includes a fifth diode, the cathode of the fifth diode is connected to one end of the magnetizing coil, and the anode of the fifth diode is connected to one end of the current transformer.
[0034] The function of the fifth diode D5 is to release the reverse induced voltage of the magnetizing coil. The function of the current transformer is to measure the discharge peak current in the main power circuit, ie, the charging and discharging circuit.
[0035] Figure 3This is a schematic diagram of a current detection circuit provided by an embodiment of the present invention. Please refer to Figure 2 .
[0036] The voltage comparator and the voltage follower are of the model UA741CP.
[0037] The output end of the voltage comparator is connected to the anode of the sixth diode, the cathode of the sixth diode is respectively connected to one end of the second capacitor and the input end of the voltage follower, and the other end of the second capacitor is grounded.
[0038] The principle of current peak detection is as follows: when the magnetizer discharges, an induced current is generated in the mutual inductance coil of the current transformer. This current generates a voltage proportional to the current across the third resistor R3, the sensing resistor. This voltage is applied to pin 3 of the voltage comparator U11, where it is compared with the voltage at pin 2 of the voltage comparator U11. The voltage at pin 2 of the voltage comparator U11 is the output voltage of the voltage follower U12, which is equal to the voltage across the second capacitor C2. Its initial value is 0V. Therefore, when the voltage at pin 3 of the voltage comparator U11 is greater than the voltage at pin 2, the voltage comparator U11 outputs a high level, turning on the sixth diode D6 and beginning to rapidly charge the second capacitor C2 until the voltage across the second capacitor C2 equals the input voltage at pin 3 of the voltage comparator U11. In other words, the voltage across the second capacitor C2 is equal to the peak value of the input voltage. Since U12 is a voltage follower, the voltage at its output pin 6 is the voltage across the second capacitor C2.
[0039] Among them, the cathode of the sixth diode is also connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the collector of the transistor, the emitter of the transistor is grounded, the base of the transistor is connected to one end of the sixth resistor, and one end of the sixth resistor is connected to the discharge controller.
[0040] When the current transformer starts to decrease from the highest peak current, the voltage at pin 2 (the inverting terminal of the comparator) of the voltage comparator U11 is higher than the voltage at pin 3 (the non-inverting terminal of the comparator). Pin 6 of the voltage comparator U11 outputs a low potential, the sixth diode D6 is cut off, and the voltage on the second capacitor C2 reaches its maximum value. Since there is no discharge circuit, the voltage on the capacitor is maintained.
[0041] After the main discharge circuit, i.e., the charge-discharge circuit, discharges the magnetizing coil for 120 milliseconds, the second pin of the discharge controller U14 detects the voltage value on the second capacitor C2 to convert and obtain the maximum discharge current value. After the discharge controller obtains the current peak value with a delay of 100 milliseconds, the 3rd pin of the discharge controller U14 sends a discharge control signal, and the voltage on the second capacitor C2 is discharged through the transistor Q4 to enter the next cycle.
[0042] In order to meet the three main requirements of short charge and discharge cycle, avoiding the temperature rise of power devices, especially step-up transformers, and precise control of the charging voltage of large-capacity and high-voltage capacitor banks, the voltage regulation module control voltage curve adopts the following method: Figure 4 The corresponding charge and discharge curves are shown as Figure 5 shown.
[0043] The voltage control curve of the voltage regulator module uses a time-varying voltage control method. Because the threshold voltage of the voltage regulator module is slightly above 0.7V, the control voltage starts at 0.75V and rapidly reaches the maximum voltage regulation value of 5V within 1 second using a linear function (Y = 0.75 + 4.25x). To ensure that the voltage charged to the magnetizing capacitor bank roughly matches the set target voltage, the control voltage of the voltage regulator module cannot be maintained at 5V. It is necessary to appropriately reduce the control voltage of the voltage regulator module, thereby reducing the rate of voltage rise on the magnetizing capacitor bank and ensuring rapid capture of the set target value. Figure 4 The voltage curve of the medium voltage regulation module is controlled to drop to 3.8V within 0.1 seconds and lasts for 0.6 seconds. At 1.7 seconds, the voltage on the magnetizing capacitor bank reaches the set target value of 1500V, and the input control of the voltage regulation module is stopped.
[0044] Figure 5 The mid-charge and discharge curve shows that the preset voltage is 1500V. As the voltage regulation module controls the voltage to rise, it reaches 90% of the target voltage, 1350V, in 1 second. Then the voltage regulation module controls the voltage to drop, and the voltage rise rate on the magnetizing capacitor group slows down and reaches the target value in 1.7 seconds, and then enters the magnetizing capacitor discharge stage.
[0045] To avoid an overlap in the time domains of the voltage regulation module being turned on and the magnetizing capacitor bank being discharged, which would cause the secondary coil of the step-up transformer to short-circuit and the primary coil current to be excessive, thus causing the power system to trip, the system does not discharge the magnetizing capacitor bank until the voltage reaches the target value. Instead, it delays the discharge by 0.2 seconds.
[0046] The discharge operation is microsecond-level, and the discharge can be completed in 1.9 seconds. Similarly, to avoid the overlap between the voltage regulator module connection and the magnetizing capacitor bank discharge time domain, the magnetizing capacitor bank starts the next charge and discharge cycle 0.2 seconds after discharge, that is, 2.1 seconds.
[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.
Claims
1. A magnetizer charging and discharging circuit, characterized in that: include: A charging and discharging circuit and a current detection circuit connected in sequence, wherein the charging and discharging circuit is used to make the magnetizing coil generate a magnetic field, and the current detection circuit is used to detect the discharge peak current in the charging and discharging circuit; The charging and discharging circuit includes: a voltage regulating and boosting circuit, a rectifier circuit, a capacitor bank circuit, a dual-path discharge control circuit, a magnetizing coil and a current transformer connected in sequence; The current detection circuit includes: an inductive resistor, a voltage comparator, a voltage follower and a discharge controller which are connected in sequence.
2. The magnetizer charging and discharging circuit according to claim 1, wherein: The voltage regulating and boosting circuit comprises: PLC voltage output module, voltage regulation module, AC 220V input module and step-up transformer; The PLC voltage output module is connected to the voltage regulating module and the AC 220V input module respectively. The voltage regulating module and the AC 220V input module are both connected to the input end of the step-up transformer. The output end of the step-up transformer is connected to the rectifier circuit.
3. The magnetizer charging and discharging circuit according to claim 1, wherein: The capacitor bank circuit comprises: The capacitor group circuit is composed of a first number of capacitor groups connected in parallel, wherein there is a capacitor group composed of a second number of capacitors connected in sequence, and there is a capacitor group composed of a second number of capacitors and capacity switching switches connected in sequence.
4. The magnetizer charging and discharging circuit according to claim 1, wherein: The dual-path discharge control circuit comprises: PLC dual-circuit discharge control circuit, second discharge thyristor and third discharge thyristor; One end of the second discharge thyristor and one end of the third discharge thyristor are both connected to the capacitor group circuit, and the other two ends of the second discharge thyristor and the other two ends of the third discharge thyristor are connected to the output ends of the corresponding PLC dual-path discharge control circuit.
5. The magnetizer charging and discharging circuit according to claim 1, wherein: The capacitor group circuit is further connected to a first capacitor and a second resistor in sequence, and the second resistor is further connected to one end of the magnetizing coil.
6. The magnetizer charging and discharging circuit according to claim 1, wherein: The models of the voltage comparator and the voltage follower are UA741CP.
7. The magnetizer charging and discharging circuit according to claim 1, wherein: The output end of the voltage comparator is connected to the anode of the sixth diode, the cathode of the sixth diode is respectively connected to one end of the second capacitor and the input end of the voltage follower, and the other end of the second capacitor is grounded.
8. The magnetizer charging and discharging circuit according to claim 7, wherein: The cathode of the sixth diode is also connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the collector of the transistor, the emitter of the transistor is grounded, the base of the transistor is connected to one end of the sixth resistor, and one end of the sixth resistor is connected to the discharge controller.
9. The magnetizer charging and discharging circuit according to claim 1, wherein: The circuit further includes a fifth diode, wherein a cathode of the fifth diode is connected to one end of the magnetizing coil, and an anode of the fifth diode is connected to one end of the current transformer.
10. The magnetizer charging and discharging circuit according to claim 1, wherein: The voltage regulating module adopts a control method of changing the pressure value in time periods, and the control curve function includes Y=0.75+4.25x.