TW201631878A - High frequency magnetizing device - Google Patents

Abstract

A high frequency magnetization device comprises a rectifying circuit, a magnetizing circuit, an output switch and a magnetizing yoke. When the high frequency magnetization device is operated in a charging mode, the magnetizing circuit that is composed of power transistors, diodes and capacitors converts a DC voltage rectified by the rectifying circuit to a high magnetizing voltage. Subsequent to the charging mode, the high frequency magnetization device operates in a magnetizing mode. The output switch is alternately turned on and off by a high frequency signal to transfer energy stored in the magnetizing circuit to the magnetizing yoke for magnetizing a target object, whereby the high frequency magnetization device is able to generate the high magnetizing voltage without using a bulky transformer, inductors and large capacitors.

Description

High frequency magnetizing device

The invention relates to a high frequency magnetizing device, in particular to a high frequency (several kHz) magnetizing circuit for increasing the output voltage with respect to the mains voltage frequency to provide a large current required for magnetization.

Generally referred to as magnetic materials can be divided into soft magnetic, hard magnetic. The so-called soft and hard magnetic are distinguished by the coercive hardness remaining after the magnetization of the material. Generally speaking, hard magnetic means that it is not easy to magnetize and is not easy to demagnetize, and soft magnetic is the opposite. Hard magnetic types commonly found in the industry include alloy magnets, ceramic magnets, and rare earth magnets. Soft magnetic is made of silicon steel sheet, soft ferrite magnet (such as manganese-zinc ferrite magnet, nickel-zinc ferrite magnet), and rare earth magnet with neodymium iron boron as the highest performance permanent magnet material. Rare earth magnets have strong coercive force and are not easily demagnetized. Although their temperature stability is poor, with the advancement of materials technology, the current temperature has reached 240 °C.

In the application of the above magnetic materials, motors, generators, household electrical appliances, industrial production equipment, and electromechanical systems can all be seen as playing a crucial role. In order to magnetize the magnetic material, an additional magnetizing means is used to magnetize the magnetic material through a magnetizing yoke. 8 is a schematic diagram of a conventional capacitive magnetization device. The AC mains AC input is first boosted to a desired discharge capacitor voltage via a low frequency transformer 81. The boosted voltage is coupled to a capacitor bank C via a full bridge rectifier circuit 82. Charging, the figure is only represented by the symbol of a single capacitor. The capacitor group C is a capacitor string composed of multiple capacitors in parallel. The typical withstand voltage of the capacitor group C is about several thousand volts. After the charging of the capacitor group C is completed, a capacitor group switch SCR1 connected between the capacitor group C and the full bridge rectifier circuit 82 is turned off, and the energy stored in the capacitor group C is transmitted through a voltage controlled rectifier switch SCR2. The inductive magnetic yoke coil 83 is discharged, generating a strong magnetic field to magnetize the magnetic material. The circuit operation of the conventional capacitive magnetizing device shown in FIG. 8 can be roughly divided into the following three stages:

1. Capacitor charging phase: Turning on the capacitor bank switch SCR1, the AC mains AC input is boosted via the low frequency transformer 81, and the AC bridge wave is converted into a full wave through the full bridge rectifier circuit 82, and then the capacitor group C is Charging. After the charging is completed, the capacitor group switch SCR1 is turned off (OFF).

2. Magnetization phase: The pulse-controlled trigger switch SCR2 is turned on, so that the energy on the capacitor group C is discharged to the magnetizing yoke coil 83 through the step-controlled rectifier switch SCR2, and a strong magnetic field is generated to magnetize the magnetized material. This magnetization process lasts for hundreds of ms.

Third, the flywheel diode conduction phase: When the magnetizing yoke coil 83 starts to discharge, the current begins to drop, the equivalent inductance L of the magnetizing yoke coil and the voltage of the capacitor group C are the same polarity, and the flywheel diode Dw is reverse biased at this time. State; when SCR2 is turned off, if the current of the magnetizing yoke has not dropped to zero, according to the law of cold times, the polarity of the equivalent inductance L of the magnetizing yoke coil is in the opposite state, and the flywheel diode Dw is in a forward bias state. To provide a magnetizing current freewheeling path until the magnetizing current drops to zero.

The conventional capacitive magnetizing device is boosted by the low frequency transformer 81, charges the capacitor group C via the full bridge rectifier circuit 82, and discharges the energy stored in the capacitor group C to the charging yoke load. However, since it needs to be boosted by the low-frequency transformer 81, the capacitor group C is composed of a plurality of large-film capacitors connected in series and in parallel. The overall capacitive magnetization device has many problems such as high weight, large volume, and large production cost.

In view of the above problems, it is a primary object of the present invention to provide a high frequency magnetizing apparatus which can be manufactured with a relatively small weight, a relatively small volume and a low cost.

In order to achieve the above object, the high frequency magnetizing device comprises: a rectifying circuit for rectifying an AC main current into a DC voltage; a magnetizing circuit connected to the rectifying circuit, and using the DC voltage to establish a charging of N times DC voltage a magnetic output voltage, wherein N>=2; an output switch connected in series between the magnetizing circuit and a charging yoke, wherein the output switch is alternately turned on/off according to a high frequency driving signal, and the magnetizing output voltage is Transferring to the magnetizing yoke and generating a magnetizing current on the magnetizing yoke; a control circuit controlling the magnetizing circuit to establish the magnetizing output voltage, and connecting the output switch to output the high frequency driving signal, wherein the high The frequency of the frequency drive signal is at least greater than 1 kHz.

The circuit action of the high frequency magnetizing device of the present invention comprises a charging phase and a magnetizing phase, in which the DC voltage is converted and boosted to a desired magnetizing voltage value by the magnetizing circuit, and then In the magnetization phase, the output switch is switched at a high frequency to transfer the energy accumulated by the magnetizing circuit to the magnetizing yoke, generating a large output current and magnetically loading the material to be magnetized.

The high-frequency magnetizing device is mainly composed of a power transistor, a diode and a capacitor, and does not need to use a conventional transformer, an inductor and a large-capacity high-voltage capacitor, so the overall volume can be relatively reduced, and the manufacturing cost can be reduced.

Referring to FIGS. 1 and 2, the high frequency magnetization device comprises a rectifier circuit 10, a magnetization circuit 20, an output switch S3, a magnetizing yoke 30 and a control circuit 40.

The rectifier circuit 10 receives an AC mains AC and converts the AC mains AC to a DC voltage Vm. In the present embodiment, the rectifier circuit 10 is a full-wave rectification circuit having two output terminals.

The magnetizing circuit 20 is connected to the output end of the rectifying circuit 10, and uses the DC voltage to establish a magnetizing output voltage of N times the DC voltage Vm, where N>=2. The magnetizing circuit 20 includes a storage capacitor Cd, a first switch S1, a second switch S2, a first capacitor C1 to a sixth capacitor C6, and first to fourth diodes D1 to D4. In this embodiment, the first capacitor C1 and the second capacitor C2 have the same capacitance value; the third capacitor C3 and the fourth capacitor C4 have the same capacitance value; the fifth capacitor C5 and the sixth capacitor C6 have the same capacitance value.

The storage capacitor Cd is connected to the two output ends of the rectifier circuit 10; the first switch S1 is connected in series with the second switch S2, and is also connected to the two output ends of the rectifier circuit 10, the first switch S1 and the second switch S2 The first capacitor C1 and the second capacitor C2 are connected to the two output ends of the rectifier circuit 10, and the first capacitor C1 and the second capacitor C2 are used as a voltage dividing circuit. The DC voltage Vm is divided. The series node of the first switch S1 and the second switch S2 serves as a first output terminal O1, and the series node of the first capacitor C1 and the second capacitor C2 serves as a second output terminal O2, and is alternately turned on. The first switch S1 and the second switch S2 can alternately output the voltages on the first capacitor C1 and the second capacitor C2 at the two output terminals O1 and O2, so that the voltages outputted by the two output terminals O1 and O2 alternately exhibit different polarities.

The third capacitor C3 is connected in series with the fourth capacitor C4, and the series node of the two capacitors C3 and C4 is connected to the first output terminal O1. The first diode D1 is connected in series with the third diode D3, and the anode of the first pole D1 is connected in series with the cathode of the third diode D3, and then connected to the second output terminal O2. The cathode of the first diode D1 is connected to the third capacitor C3, and the anode of the third diode D3 is connected to the fourth capacitor C4. The fifth capacitor C5 is connected in series with the sixth capacitor C6. The series node of the two capacitors C5 and C6 is connected to the second output terminal O2. The two ends of the fifth capacitor C5 and the sixth capacitor C6 are respectively magnetized. The positive output terminal and the negative output terminal of the circuit 20. The anode of the second diode D2 is connected to the cathode of the first diode D1, and the cathode of the second diode D2 is connected to the positive output of the magnetizing circuit 20. The cathode of the fourth diode D4 is connected to the anode of the third diode D1, and the anode of the fourth diode D4 is connected to the negative output of the magnetizing circuit 20.

One end of the output switch S3 is connected to the positive output end of the magnetizing circuit 20, and the other end of the output switch S3 is connected to one end of the magnetizing yoke 30. The other end of the magnetizing yoke 30 is connected to the negative output terminal of the magnetizing circuit 20. A flywheel diode Dw may be reconnected between the positive and negative output terminals of the magnetizing circuit 20 in parallel with the magnetizing yoke 30.

The control circuit 40 includes a microcontroller that is connected to the first switch S1, the second switch S2, and the charging switch S3 via the drive circuit 42 to control its opening and closing.

The circuit operation of the present invention will be described in detail below, including a charging phase and a magnetizing phase. In this charging phase, the output switch S3 remains off (OFF), and the circuit can be subdivided into the following four periods:

The first time period: Please refer to FIG. 3A, after the AC mains AC is converted by the rectifying circuit 10, a DC voltage Vm can be established on the storage capacitor Cd, and the DC voltage Vm is divided by the first capacitor C1 and the second capacitor C2 connected in series. Pressing, the voltage on each capacitor is 0.5Vm, the first switch S1 is controlled to be turned on (ON) by the microcontroller 51, and the second switch S2 is controlled to be turned off (OFF), at this time across the first capacitor C1. The voltage (0.5Vm) causes the third diode D3 to be turned on in the forward bias state, the fourth diode D4 is reverse biased off, and the fourth capacitor C4 is charged and the charging voltage is the first capacitor C1. The voltage on it (0.5Vm). Further, the first diode D1 and the second diode D2 are in a reverse bias voltage cut-off state. The current path for this first time period is shown by the dashed arrow symbol in Figure 3A.

The second period: as shown in FIG. 3B, the first switch S1 is controlled to be turned off by the microcontroller 51, and the second switch S2 is turned on, and the voltage across the second capacitor C2 (0.5 Vm) causes the diode D1 to be turned off. Turning on in the forward bias state, the third diode D3 is turned off in the reverse bias state, and the voltage on the second capacitor C2 charges the third capacitor C3, and the charged voltage is equal to the voltage on the second capacitor C2 ( 0.5Vm). The second diode D2 and the fourth diode D4 are in a reverse bias voltage cut-off state. The current path for the second working period is indicated by the dashed arrow.

The third period: as shown in FIG. 3C, the first switch S1 is controlled to be turned on again, and the second switch S2 is turned off, and the voltage (0.5Vm) and the third capacitor C3 established on the first capacitor C1 in the previous working period are The upper voltage (0.5Vm) forms a series potential, so that the first diode D1 is turned off at the reverse bias voltage and the second diode D2 is turned on. At this time, the voltage on the fifth capacitor C5 is the sum of the voltages of the first capacitor C1 and the third capacitor C3, so it is Vm. Further, the third diode D3 and the fourth diode D4 are in a reverse bias voltage cutoff state.

The fourth period: as shown in FIG. 3D, the first switch S1 is again controlled to be turned off, and the second switch S2 is re-triggered, and the voltage across the second capacitor C2 (0.5 Vm) and the voltage on the fourth capacitor C4 (0.5 Vm) is formed in series, so that the third diode D3 is turned off in the reverse bias voltage, and the fourth diode D4 is turned on in the forward bias voltage. At this time, the voltage of the sixth capacitor C6 is the sum of the voltages of the second capacitor C2 and the fourth capacitor C4, so it is Vm. Further, the first and second diodes D1 and D2 are in a reverse bias voltage cutoff state.

After the above four working phases, that is, after the first and second switches S1 and S2 are rotated twice, the voltages of the fifth capacitor C5 and the sixth capacitor C6 are respectively obtained twice as long as the first capacitor C1 and the second capacitor C2. The voltage of the magnetizing output voltage Vo provided by the magnetizing circuit 20 is the sum of the voltages of the fifth capacitor C5 and the sixth capacitor C6. Therefore, the magnetizing output voltage Vo=2Vm is compared with the voltage on the storage capacitor Cd. Vm can get a boosting effect.

As shown in FIG. 4, when the magnetization output voltage Vo=2Vm is established, the charging phase is terminated, and then the magnetization phase is entered. In the magnetization phase, the present invention sets the output switch S3 to be turned on and off with a high frequency drive signal of several kHz. The frequency of the drive signal is a high frequency relative to the AC mains, and the frequency is selected depending on the material to be magnetized. The characteristics are the same as the time of turning on and off in the same cycle, and the fifth and sixth capacitors C5 and C6 of the magnetizing circuit 20 start to discharge according to the alternate on/off of the output switch S3. When the output switch S3 is turned ON, the fifth and sixth capacitors C5 and C6 start to discharge, and the magnetizing current Iout flowing through the magnetizing yoke 30 gradually increases as the capacitor discharge time increases. The coil yoke 30 is inductive and has the characteristics of current freewheeling, so that the alternating current on/off control of the output switch S3 can increase the magnetizing current Iout in the form of energy accumulation, and gradually increase the magnetic material. The current value of the magnetic filling.

Please refer to FIG. 5 to FIG. 7 for the simulation test waveform diagram of the DC voltage Vm from 150 volts, 200 volts, and 300 volts. The horizontal axis of each graph represents time (t), and the output switch S3 is driven at a frequency of 3 kHz. Vpulse high frequency switching, capacitors C1, C2, C5, C6 are 1000uF, and capacitors C3 and C4 are 470uF. It can be seen from the respective figures that the magnetizing current Iout increases as the DC voltage Vm increases. The output voltage Vo continues to be periodically discharged due to the fifth and sixth capacitors C5 and C6, so that the magnetizing current Iout is climbed to a maximum value in a stepwise manner. As shown in Fig. 7, under the condition that the DC voltage Vm is 300 volts, the peak value of the magnetization output voltage Vo is about 600 volts, and the peak value of the magnetizing current Iout has reached 400 amps, which is in line with the magnetic material. Use of padding.

The bridge type rectifier circuit 10 first rectifies the AC mains C to a DC voltage Vm, and then combines the switches S1~S3, the diodes D1~D4 and the capacitors C1~C6 formed by the power crystal, through the microprocessor. Controlling the opening and closing operations of the different switches S1~S3 and the forward and reverse bias voltage operating characteristics of the diodes D1~D4, so that the capacitors C1~C6 pass through the switches S1~S3 and the diodes D1~D4. At the end, the appropriate series is combined and combined at a speed of several kHz, and the rectified DC voltage Vm is boosted to a desired magnetization voltage value Vo in a high frequency manner.

Compared with the conventional capacitive magnetizing device, the present invention has at least the following advantages:

1. The invention comprises a switch composed of a power transistor, a diode and a capacitor, and a magnetizing circuit can replace the traditional bulky transformer. The circuit also has the function of voltage boosting, and can utilize a smaller circuit volume and weight. Meet the demand for magnetization.

2. The magnetizing device of the present invention does not need to use an inductor for passing a large current, so the present invention does not generate a large magnetizing current after high frequency control even if a high frequency switching control of several kHz is used in the magnetizing device. The magnetic saturation of the inductor core may be encountered.

3. The present invention discards the conventional high-voltage large-capacity group one-discharge type magnetization mode (the typical value of the capacitor group is withstand voltage of 1kV and above 10,000uF), and the high-frequency boost control is used to make the magnetization circuit only need to withstand hundreds of volts. The relatively small capacitors Cd and C1~C6 are used as energy storage components for the magnetization process. For example, the capacitors Cd, C1, C2, C5, and C6 used in the test examples of FIG. 4 to FIG. 7 are 1000 uF, and C3 and C4 are 470 uF during magnetization. The capacitor is repeatedly charged and discharged at a frequency of several kHz, and a large magnetizing current is designed in accordance with the equivalent inductive freewheeling characteristic of the magnetizing yoke coil.

10‧‧‧Rectifier circuit
20‧‧‧Magnetic circuit
30‧‧‧Magnetic yoke
40‧‧‧Control circuit
81‧‧‧Low frequency transformer
82‧‧‧Full bridge rectifier circuit
83‧‧‧Magnetic yoke coil

Figure 1 is a block diagram of a circuit of a high frequency magnetizing device of the present invention. Figure 2 is a detailed circuit diagram of the high frequency magnetizing device of the present invention. 3A to 3D are circuit diagrams showing the circuit of the magnetizing output voltage Vo generated by the high frequency magnetizing device of the present invention. Fig. 4 is a waveform diagram of the drive signal Vpulse and the output current Iout of the output switch of the present invention. Figure 5: Test waveform diagram of the present invention simulated with a 150 volt DC voltage Vm. Figure 6: Test waveform diagram of the present invention simulated with a 200 volt DC voltage Vm. Figure 7: Test waveform diagram of the present invention simulated with a 300 volt DC voltage Vm. Figure 8: Circuit diagram of a conventional capacitive magnetization device.

10‧‧‧Rectifier circuit

20‧‧‧Magnetic circuit

30‧‧‧Magnetic yoke

40‧‧‧Control circuit

Claims (9)

A high frequency magnetizing device comprises: a rectifying circuit for rectifying an alternating current main current into a direct current voltage; a magnetizing circuit connected to the rectifying circuit, and using the direct current voltage to establish a magnetizing output voltage of a N times DC voltage, Wherein N>=2; an output switch connected in series between the magnetizing circuit and a charging yoke, wherein the output switch is alternately turned on/off according to a high frequency driving signal, and the magnetizing output voltage is transferred to the magnetizing The yoke generates a magnetizing current on the magnetizing yoke; a control circuit controls the magnetizing circuit to establish the magnetizing output voltage, and connects the output switch to output the high frequency driving signal, wherein the high frequency driving signal The frequency is at least greater than 1 kHz. The high frequency type magnetizing apparatus according to claim 1 includes a charging phase and a magnetizing phase, wherein the charging circuit establishes the magnetizing output voltage, and the output switch maintains the cutoff; In the magnetic phase, the output switch is alternately turned on/off according to the high frequency driving signal. The high frequency type magnetizing device according to claim 1 or 2, wherein the magnetizing circuit comprises: a storage capacitor connected to the two output ends of the rectifier circuit; a first switch and a second switch, the first switch After being connected in series with the second switch, the energy storage capacitor is connected in parallel, wherein the first node of the first switch and the second switch is a first output terminal; a first capacitor and a second capacitor, the first capacitor and the second capacitor The capacitor is connected in series and is connected in parallel with the storage capacitor, wherein the series connection of the first capacitor and the second capacitor is a second output terminal; a third capacitor and a fourth capacitor, the third capacitor and the fourth capacitor are connected in series The node is connected to the first output end; a first diode and a third diode, the first diode and the third diode are connected in series, and the anode of the first pole and the third The anode of the pole body is connected to the second output terminal, the cathode of the first diode is connected to the third capacitor, the anode of the third diode is connected to the fourth capacitor, and a fifth capacitor and a sixth capacitor are used. a series connection of a fifth capacitor and a sixth capacitor is connected to the second output, wherein The two ends of the fifth capacitor and the sixth capacitor are respectively connected as a positive output terminal and a negative output terminal of the magnetizing circuit; a second diode body having a positive electrode connected to the negative electrode of the first diode body, the first The negative pole of the diode is connected to the positive output of the magnetizing circuit; the fourth diode has a negative pole connected to the anode of the third diode, and the anode of the fourth diode is connected to the negative output of the magnetizing circuit end. The high frequency type magnetizing apparatus according to claim 3, wherein the charging phase includes a first working period to a fourth working period, wherein: in the first working period, the first switch is turned on, and the second switch is turned off, The voltage on the first capacitor charges the fourth capacitor and the charging voltage is equal to the voltage on the first capacitor; in the second operating period, the second switch is turned on, the first switch is turned off, and the voltage on the second capacitor Charging the third capacitor and charging a voltage equal to the voltage on the second capacitor; in the third working period, the first switch is turned on, the second switch is turned off, and the first capacitor is connected in series with the third capacitor Charging the fifth capacitor, the voltage on the fifth capacitor is the sum of the voltages of the first capacitor and the third capacitor; in the fourth working period, the second switch is turned on, the first switch is turned off, and the second capacitor and the fourth capacitor are turned off Forming a series and collectively charging the sixth capacitor, the voltage on the sixth capacitor is the sum of the voltages of the first capacitor and the third capacitor. The high frequency type magnetizing apparatus according to claim 4, wherein the output switch is alternately turned on/off at the same time in the magnetizing phase. The high frequency type magnetizing device according to claim 5, wherein the positive and negative output ends of the magnetizing circuit are connected to a flywheel diode, and the flywheel diode is connected in parallel with the magnetizing yoke. The high frequency magnetizing device of claim 6, wherein the first capacitor and the second capacitor have the same capacitance value; the third capacitor and the fourth capacitor have the same capacitance value; the fifth capacitor has the same capacitance as the sixth capacitor Capacitance value. The high frequency magnetization device of claim 7, wherein the first switch, the second switch, and the third switch are power transistors. The high frequency type magnetizing device according to claim 8, wherein the rectifying circuit is a full bridge rectifying circuit.