JP4667066B2 - Magnetizer power supply - Google Patents

Description

  The present invention provides a rectified output of a double-wave rectifier circuit that rectifies an AC output voltage on the secondary side of a step-up transformer to a charging capacitor that supplies a magnetizing current to a magnetizing coil in response to ON control of a magnetizing switching element. The present invention relates to a power supply for a magnetizer that is charged with a voltage.

  FIG. 7 shows a conventional typical circuit of this type. The phase control circuit 7 controls the phase of the commercial power supply voltage, and the step-up voltage of the step-up transformer 8 with the input power adjusted thereby is rectified by two waves. The two-wave rectifier circuit 2, the charging capacitor C3 charged with the rectified output voltage, and a series circuit composed of the SCR1 and the magnetizing coil L1 connected in parallel to the charging capacitor and the switching element for magnetization. The As a result, the SCR 1 is turned on by an ignition pulse to supply a magnetizing current to the magnetizing coil L1, and the flywheel is driven by the back electromotive force generated in the magnetizing coil L1 when the charging voltage of the charging capacitor C3 becomes substantially zero. A circulating current is passed through the diode D9.

On the other hand, according to Patent Document 1, the DC power source is connected to the first and second forward switching elements and the third and fourth forward directions in which the freewheeling diodes are connected in antiparallel. A power supply apparatus is provided with a switching circuit composed of switching elements to form a resonance type inverter on the primary side of the step-up transformer and a resonance type inverter due to the leakage inductance of the transformer, and to charge the capacitor with a rectified output on the secondary side. It is disclosed.
JP 2002-272135 A

  According to the circuit of FIG. 7, a desired charging voltage can be obtained by the phase control of the phase control circuit 7, but when the ripple voltage or a plurality of magnetizers are operated, it is affected by fluctuations in the commercial power supply. Therefore, in order to make the charging voltage constant at all times, it is conceivable to provide a voltage stabilizing circuit by normal feedback control between the rectifier circuit 2 and the charging capacitor C3. Difficult in terms of circuit configuration complexity. Further, the switching element of the phase control circuit 7 becomes expensive because the current value per pulse increases corresponding to the commercial power supply frequency. Furthermore, in order to shorten production tact, even if it is going to speed up charge, it is restrict | limited by the frequency of a commercial power source.

  On the other hand, when the resonant inverter disclosed in Patent Document 1 is used for charging the charging capacitor of the above-mentioned magnetizer, the production tact time is shortened or the step-up transformer is reduced by charging with the high-frequency rectified voltage. When the magnet is magnetized with high current and high accuracy, it is necessary to stabilize the charging voltage of the charging capacitor. However, as described above, when trying to stabilize by normal feedback control, the power loss becomes large, and when trying to charge at high speed by a high frequency resonant inverter, transiently every magnetization due to delay of feedback control. The possibility of excessive charging voltage remains.

  In view of these points, the present invention charges a charging capacitor, which is a magnetizing current source on the secondary side, at a high speed and is charged on the premise that a resonant inverter is provided on the primary side of the step-up transformer. An object of the present invention is to provide a power supply for a magnetizer capable of stabilizing a voltage with high accuracy by suppressing power loss.

In order to achieve this object, according to the present invention, a magnetizing current is supplied to a magnetizing coil at a predetermined magnetizing period in response to an on control by a magnetizing switching signal of a magnetizing switching element. In a magnetizer power supply that charges a charging capacitor with a rectified output voltage of a double-wave rectifier circuit on the secondary side of the step-up transformer, a rectifier circuit for a commercial AC power A smoothing capacitor for smoothing the output voltage and a resonant inverter are provided, and this resonant inverter includes a series circuit in which the anode of the second switching element is connected to the cathode of the first switching element and the third switching A series circuit in which the anode of the fourth switching element is connected to the cathode of the element is connected in parallel to each other, and the first to fourth switching elements are connected to the reflux diode. De comprises a switching circuit which is connected in anti-parallel, respectively, are connected between the first and one terminal of the second between the switching element and the primary side and a resonant capacitor which resonates with the said step-up transformer leakage inductance together, the switching circuit is connected in parallel to the smoothing capacitor, and the other terminal of the primary side is connected between the third and fourth switching elements, further the capacity of the resonance capacitor, to the destination磁周period from the resonant inverter On the other hand, the first and fourth switching elements are set so as to resonate at a frequency at which the charging step voltage can be supplied to the secondary-side double-wave rectifier circuit at high speed, and during the first half cycle of one cycle of the resonant frequency. A pair of switching signals for turning on the second and third switching elements over the first half cycle of the next cycle Magnetizing in response to the switching signal output by the fast charge half the frequency of the resonant frequency, where relatively lower than the high-speed charging frequency fast charge frequency before the charging voltage of the charging capacitor reaches a predetermined voltage, And an inverter switching control means for switching to a low-speed charging frequency faster than the magnetization period, a charging voltage detecting means for detecting the charging voltage, and a detection that the charging voltage has reached a predetermined voltage. A constant voltage that interrupts the output of a pair of switching signals at a low-speed charging frequency and re-outputs a pair of switching signals at a low-speed charging frequency when it is detected that the charging voltage has fallen a predetermined amount from the predetermined voltage within the magnetization period. The control means is attached to the resonant inverter, and the charging voltage for switching from the high speed charging frequency to the low speed charging frequency is a constant voltage control method. Characterized in that it is configured to prevent the overcharging of more than a predetermined voltage is performed by the fast charging frequency due to response delay of.

  The resonant inverter includes first and fourth switching elements in which a return diode is connected in reverse parallel to a rectified output voltage smoothed by a smoothing capacitor of a rectifier circuit of a commercial AC power supply by switching control by an inverter switching control means. Is turned on and converted into a positive and negative step charging voltage of the resonance frequency, and the charging capacitor is charged via the secondary-side double-wave rectifier circuit. In the next cycle of the resonance frequency, the second and third switching elements are turned on, and the charging capacitor is charged with a negative positive step charging voltage. The charging speed is switched from a high-speed charging frequency that is half of the resonance frequency to a low-speed charging frequency during charging. When the charging voltage reaches a predetermined voltage without generating an overvoltage due to low-speed charging, generation of the step charging voltage is interrupted by the constant voltage control means, and when a predetermined amount of voltage drop occurs, recharging is performed at the low-speed charging frequency to determine the voltage. The voltage is maintained. In this case, switching from high speed charging to low speed charging is performed according to claim 3 in which the switching control means for the inverter switches to output at the low speed charging frequency in response to the output cycle number of the pair of switching signals at the high speed charging frequency. Alternatively, the inverter switching control means switches the output of the pair of switching signals at the high-speed charging frequency to the output at the low-speed charging frequency in response to the detection voltage of the charging voltage detection means.

  According to claim 2, a power regeneration type magnetizer to which the present invention is applied has a charging switching element interposed between a double-wave rectifier circuit for rectifying an AC output voltage on the secondary side of a step-up transformer and a charging capacitor. A regenerative series circuit consisting of a regenerative coil and a regenerative switching element is connected in parallel to the charging capacitor, and the charging capacitor is charged with the rectified output voltage by operating the resonant inverter and turning on the charging switching element. Then, the switching element for magnetization is turned on in the end state of this charging, and the switching element for regeneration is turned on at the time when the half cycle of the resonance current due to the magnetizing coil and the charging capacitor has elapsed from the time of this on control, The reverse voltage charged in the charging capacitor by the magnetizing coil is positively applied by the resonance current generated by the regenerative coil and the charging capacitor. It is regenerated to charge the capacitor as pressure.

  According to the first aspect of the present invention, the high-frequency resonant inverter that converts the rectified / smoothed voltage of the commercial power supply voltage is provided on the primary side of the step-up transformer, thereby reducing the size of the step-up transformer and reducing the current capacity of the switching element of the inverter. And shortening of production tact by high-speed charging, and it is possible to avoid the influence of voltage fluctuation or superimposed noise of a three-phase or single-phase commercial power supply. In addition, by switching the switching speed of the inverter, it is possible to suppress overcharging of the charging capacitor due to delay in stabilization control of the charging voltage, and constant voltage control is performed without power loss by cutting off the input of the charging step voltage. . According to the second aspect of the present invention, the magnetizing current is a resonance current generated by the magnetizing coil and the charging capacitor, and the reverse voltage charged in the charging capacitor by the magnetizing coil is regenerated at the time when the half cycle has elapsed. It can also be used as a power source for a magnetizer that is reversed by a resonance current generated by a coil for use and a charging capacitor and regenerated to the charging capacitor. In addition, by setting the regenerative resonance frequency sufficiently high, it is possible to reduce the amount of charge due to the charging step voltage of the inverter and further shorten the production tact. Switching from high speed charging to low speed charging is performed with a simple circuit configuration according to the invention of claim 3, and according to the invention of claim 4, it is performed with high accuracy according to the charging voltage.

FIG. 1 to FIG. 4 illustrate a power supply for a magnetizer according to an embodiment of the present invention. The same or equivalent parts as those already described with reference to FIG. On the secondary side of the step-up transformer 8, a double-wave rectifier circuit 2 and a charging capacitor C3 charged with the rectified output voltage, a series circuit of SCR1 and a magnetizing coil L1, which are magnetization switching elements, and a charging voltage The voltage divider 9 and a discharging resistor R1 that discharges the charging voltage at the end of the operation are connected in parallel, and the magnetizing coil L1 is magnetized from the time when the charging voltage of the charging capacitor C3 becomes substantially zero. A flywheel diode D9 that circulates the residual current due to the back electromotive force generated in the circuit is connected in parallel. The SCR 1 is accompanied by a magnetization switching control means 10 for supplying a magnetization firing pulse as a magnetization switching signal with a production tact having a magnetization period of, for example, 3.5 seconds .

  On the primary side of the step-up transformer 8, for example, a rectifier circuit 1 that performs both-wave rectification of a three-phase commercial AC power source as a magnetizer power source for charging the charging capacitor C3, and a smoothing capacitor that smoothes the rectified output voltage C1 and a resonant inverter are provided. This resonant inverter includes a series circuit in which the anode of the second IGBT 2 is connected to the cathode of the first IGBT 1 as a switching element, and a series circuit in which the anode of the fourth IGBT 4 is connected to the cathode of the third IGBT 3. A smoothing capacitor C1 is connected in parallel, and is connected between a switching circuit in which return diodes D1 to D4 are connected in reverse parallel to IGBT1 to IGBT4, and between the IGBTs 1 and 2 and one terminal on the primary side of the step-up transformer 8. And the resonance capacitor C2 that resonates with the leakage inductance of the step-up transformer 8, and the other terminal on the primary side is connected between the IGBTs 3 and 4.

  In this switching circuit, as shown in FIG. 2, a pair of gate-like switching signals that are slightly wider than the half cycle corresponding to a resonance frequency of, for example, 100 kHz are applied to IGBTs 1 and 4 and IGBTs 2 and 3, respectively, at 50 kHz or 5 kHz. Switching control means 13 for inverters output at a period of, a voltage divider 9 as charging voltage detection means for dividing the charging voltage of the charging capacitor C3 and digitizing it by the A / D converter 11, and for a predetermined voltage of 2.5 kV When it was detected that the charging voltage reached 98%, the 50 kHz switching signal (FIG. 2B) was intermittently blanked to switch to the 5 kHz switching signal output (FIG. 2C), and reached the predetermined voltage. Is detected, the output of the switching signal is stopped, and after reaching a predetermined voltage, for example, When detecting the voltage drop of the corresponding 2.5V to 0.1%, and the constant voltage control means 12 to re-output the switching signal of the low-speed charging frequency 5kHz as a predetermined voltage is obtained is included. These control means 10, 12, and 13 are constituted by a microcomputer or a hardware circuit. Note that the switching from the fast charge to the slow charge has reached the number of output cycles, assuming that the switching control means 13 for inverter assumes the output cycle number of the switching signal of the fast charge frequency reaching 98% of the predetermined voltage in advance. It is also possible to switch to the slow charging frequency at the time.

  Thereby, in response to the generation of the magnetizing firing pulse with a period of 3.5 seconds, the IGBTs 1 to IGBT4 are controlled by a pair of gate-shaped switching signals of 50 kHz or 5 kHz. That is, as shown in FIG. 2A, due to the smoothed rectified voltage of the smoothing capacitor C1, a resonance current flows from IGBT1 → resonance capacitor C2 → step-up transformer 8 → IGBT4 in the first half cycle of one cycle of the resonance frequency of 100 kHz. The resonance capacitor C2 is charged up to twice the rectified voltage. In the next half cycle, the charging voltage is turned off when the currents of the IGBTs 1 and 4 are zero, and flows from the resonance capacitor C2 to the return diode D1 to the smoothing capacitor C1 to the return diode D4 to the step-up transformer 8. In the first half cycle of the next cycle of the resonance frequency, the resonance current flows in the reverse direction from IGBT2 → step-up transformer 8 → resonance capacitor C2 → IGBT3, and in the next half cycle, resonance capacitor C2 → return diode D2 → The current flows from the smoothing capacitor C1 to the reflux diode D3 to the step-up transformer 8.

  The capacitance Cs of the resonance capacitor C2 is set to 0.1 μF, for example, corresponding to the leakage inductance of the step-up transformer 8 so as to obtain the resonance frequency of 100 kHz. On the other hand, a charging step voltage (twice the charging step voltage every half cycle of 5 μs) ΔVco at a resonance frequency of 10 μs per cycle is expressed by the following equation (1) on the assumption that the capacitance Co of the charging capacitor C3 is sufficiently larger than Cs. ).

ΔVco = 4 × (Cs / nCo) × (Vce−Vcr / n) (1)
Here, assuming that the capacitance Co is 3,000 μF, the predetermined voltage Vce is 2.5 kV, and the step-up ratio n of the step-up transformer 8 is a dozen times, the residual voltage Vcr for each magnetization of the charging capacitor C3 is greatly increased with respect to Vce. The charging step voltage ΔVco is set to about 10 mV on the assumption that the voltage is small.

  In short, in a normal magnetizer with a large magnetizing current, Co becomes correspondingly large and the capacity ratio Cs / Co naturally becomes extremely small, so that the charging step voltage ΔVco can be set sufficiently small with respect to the predetermined voltage Vce. Become. Further, the time required to charge 2.5 kV in 10 mV steps every 10 μs of the resonance period is 2.5 s. In addition, the time required to charge 2% of 50V with a low-speed charging cycle of 200 μs is 0.5 seconds. The time required for charging the error voltage of 2.5 V to be subject to constant voltage control in a cycle of 200 μs for low-speed charging is 25 ms. Therefore, in the case of a 20 μs cycle of high-speed charging, a charging voltage of 25 V is generated in 25 ms and may be overvoltage due to a delay in constant voltage control. However, when the charging speed is reduced to 1/10, Assuming that the response delay of the voltage control is sufficiently smaller than 25 ms, the constant voltage control can be performed within the error voltage of 2.5 V, that is, within an error of about 0.1%.

  The operation of the power supply for a magnetizer configured as described above will be described with reference to FIGS. In response to a start signal or a magnetizing ignition pulse having a period of, for example, 3.5 seconds, the IGBT1 to IGBT4 are inverter-controlled by a pair of gate-shaped switching signals having a high-speed charging frequency of 50 kHz. As a result, positive, negative, negative, and positive charging step voltages are half-wave rectified by the double-wave rectifier circuit 2 and charged to the charging capacitor C3 sequentially every half cycle of the resonance frequency of 100 kHz. At this time, since the reverse resonance voltage is alternately supplied in the same operation mode in one cycle of the resonance frequency of about 100 kHz and the next one cycle, the step-up transformer 8 is suppressed from generating residual magnetism and having a high frequency. Boost characteristics are ensured.

  When 98% of the predetermined voltage is detected, the output frequency of the pair of gate-shaped switching signals is reduced to a low-speed charging frequency of 5 kHz that effectively functions constant voltage control so that transient overcharging is not performed. Charging continues. When 100% is detected, the output of the switching signal is stopped with virtually no delay. In this state, every time a voltage drop of 0.1% with respect to a predetermined voltage of 2.5 kV is detected by the leakage resistance of the charging capacitor C3 until the start of magnetization, that is, a voltage drop of 2.5V is detected, the charging voltage is at a low charging frequency. Is replenished with high accuracy.

  When the SCR 1 is ignited, a magnetizing current of about 10 kA, for example, due to resonance with the charging capacitor C3 is supplied to the magnetizing coil L1, and after reaching the peak current, the SCR 1 is extinguished by the reverse voltage and the flywheel diode D9 Discharge occurs through. Magnets are sequentially conveyed into the magnetizing coil L1 at a production tact of 3.5 seconds, and a magnetizing ignition pulse is output each time the charging capacitor C3 is charged to 2.5 kV with high accuracy.

  In this way, the AC voltage is rectified by the rectifier circuit 1 and smoothed by the smoothing capacitor C1 to be quickly charged with high resolution by a high-frequency minute voltage step obtained by converting the DC voltage that avoids the influence of voltage fluctuation and superimposed noise. By stabilizing and controlling the charging voltage, a magnet having a uniform holding force can be manufactured with a short production tact. In addition, the high-frequency inverter reduces the size of the core of the step-up transformer 8 and suppresses the amount of IGBT current per pulse or switching loss, thereby reducing the cost of the switching element and improving the charging efficiency.

  The resonant inverter type power supply of the present invention is also applied to a magnetizer having the following configuration according to Japanese Patent Application No. 2004-365862 by the applicant of the present application. That is, as shown in FIG. 5, a double-wave rectifier circuit 2 that rectifies the boosted AC output of the boost transformer 8, a charging capacitor C3 that is charged with the rectified output voltage, and a parallel connection to the charging capacitor, And a series circuit composed of a magnetic SCR1 and a magnetizing coil L1, and a charging SCR3 is connected between the both-wave rectifier circuit 2 and the charging capacitor C3, and on the output side thereof, a regenerative coil is connected to the charging capacitor C3. A series circuit for regeneration composed of L2 and SCR2 for regeneration is connected in parallel. The SCRs 1 to 3 are turned on by on-control as well-known switching elements, and are automatically turned off when the conduction current falls below a predetermined level.

  As a result, as shown in FIG. 6, the magnetizing SCR1 is turned on by the ignition pulse P1 by the attached switching control circuit 5, so that the magnetizing coil L1 is magnetized by the charging voltage of the charging capacitor C3. Magnetic current is supplied. This magnetizing current is supplied as a resonance current between the magnetizing coil L1 and the charging capacitor C3, and the SCR 1 is extinguished when a half period T1 in which the magnetizing current at the resonance frequency becomes substantially zero has elapsed. During this time, the charging voltage of the charging capacitor C3 is gradually discharged and charged with the reverse voltage generated in the magnetizing coil L1 when the peak current is reached, and the charging capacitor as a reverse voltage with power loss of the magnetizing coil L1, etc. Held at C3. Next, when the regenerative SCR 2 is turned on by the ignition pulse P2, the charging capacitor C3 has a predetermined amount of attenuation due to resonance with the regenerative coil L2, and a positive voltage is applied during the half cycle T2. Therefore, the reverse voltage once charged in the charging capacitor C3 by the reverse voltage of the magnetizing coil L1 is inverted again by the regenerative coil L2 and regenerated to the positive voltage, and reaches the half cycle T2 of the resonance frequency to reach the regenerative current. SCR2 is extinguished at a time when becomes zero, and the regenerative voltage is held in the charging capacitor C3.

  That is, during the damped oscillation of the resonance frequency caused by the charging voltage, the first half wave is used as the magnetizing current, and the remaining vibration energy is regenerated. After each regenerative operation, the inverter switching control means 13 and the constant voltage control means 12 are activated by the ignition pulse P3, and the charging SCR 3 is turned on by a pair of gate-like switching signals wider than a half cycle of the inverter resonance frequency. By being controlled, charging is performed so that the regenerative voltage is supplemented by the two-wave rectifier circuit 2 in the ON state during the charging period T3. The charging SCR 3 becomes non-conductive by not generating a step charging voltage or a switching signal during magnetization and regenerative operation. In the case of this embodiment, high-speed charging at the regenerative resonance frequency is possible, and the charge amount by the inverter can be reduced according to the regenerative voltage, so that the production tact can be further shortened.

It is a figure which shows the circuit structure of the magnetizer power supply by embodiment of this invention. It is a figure explaining the operation | movement timing and operation | movement waveform of the same apparatus. It is a figure explaining the charge process of the charge capacitor of the same magnetizer power supply. The magnetizing operation of the magnetizer power source will be described. FIG. A shows the voltage waveform of the charging capacitor, and FIG. B shows the current waveform of the magnetizing coil. It is a figure which shows the structure of another magnetizer to which this invention is applied. It is a figure explaining operation | movement of the magnetizer by FIG. It is a figure which shows the structure of the magnetization circuit of the conventional magnetizer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rectification circuit of commercial AC power supply 2 Double-wave rectification circuit of boosting voltage 8 Boosting transformer 9 Voltage divider of charging voltage C1 Smoothing capacitor C2 Resonance capacitor C3 Charging capacitor L1 Magnetizing coil L2 Regenerative coil SCR1 Magnetizing SCR
SCR2 Regenerative SCR
SCR3 SCR for charging

Claims (4)

In response to the on-control by the magnetizing switching signal of the magnetizing switching element, the charging capacitor that supplies the magnetizing current with a predetermined magnetizing period to the magnetizing coil is connected to the double-side rectifier circuit on the secondary side of the step-up transformer. In the power supply for a magnetizer that is charged by the rectified output voltage,
On the primary side of the step-up transformer, a rectifier circuit for a commercial AC power supply, a smoothing capacitor for smoothing the rectified output voltage, and a resonant inverter are provided, and the resonant inverter is connected to the cathode of the first switching element. A series circuit in which the anode of the second switching element is connected and a series circuit in which the anode of the fourth switching element is connected to the cathode of the third switching element are connected in parallel to each other, and the first to fourth switching elements are connected to each other. A switching circuit in which return diodes are connected in antiparallel, a resonance capacitor connected between the first and second switching elements and between one terminal on the primary side and resonating with a leakage inductance of the step-up transformer; provided with a, the switching circuit is connected in parallel to the smoothing capacitor, and the primary side Square of terminals, the third and fourth of said connected between the switching element, further capacity of the resonance capacitor, both waves of the secondary side charging step voltage at high speed against the wear磁周period from the resonant inverter Set to resonate at a frequency that can be supplied to the rectifier circuit ,
The first and fourth switching elements are turned on during the first half cycle of the resonance frequency , and the second and third switching elements are turned on over the first half cycle of the subsequent period. relatively the fast charging frequency before in response to a pair of switching signals to the magnetizing switching signal output in the fast charging frequency of half the resonant frequency, the charging voltage of the time the charging capacitor reaches a predetermined voltage An inverter switching control means for switching to a low charge frequency that is lower and faster than the magnetization period; a charge voltage detection means for detecting the charge voltage; and when the charge voltage is detected to have reached the predetermined voltage the interrupt the output of the pair of the switching signal according to the slow charging frequency, and the charge voltage in said deposition磁周life from the predetermined voltage And constant voltage control means for re-output pair of the switching signal by the low-speed charging frequency as that was quantified drop is detected, comes to the resonant inverter,
The charging voltage to be switched to the low-speed charging frequency is set so as to suppress overcharging exceeding the predetermined voltage by the high-speed charging frequency due to a response delay of the constant voltage control means. Characteristic power supply for magnetizer. A regenerative coil composed of a regenerative coil and a regenerative switching element is disposed between the charging capacitor and a both-wave rectifier circuit that rectifies the AC output voltage on the secondary side of the step-up transformer and the rechargeable capacitor. Connect the series circuit in parallel,
The charging capacitor is charged with the rectified output voltage by the operation of the resonance type inverter and the on-control of the charging switching element, and then the magnetizing switching element is on-controlled at the end of the charging. The regenerative switching element is turned on at the time when a half cycle of a resonance current caused by the magnetizing coil and the charging capacitor passes, and a reverse voltage charged in the charging capacitor by the magnetizing coil is changed to the regenerative coil. 2. The magnetizing power source according to claim 1, wherein the charging capacitor is regenerated as a positive voltage by a resonance current generated by the charging capacitor.   3. The power supply for a magnetizer according to claim 1, wherein the inverter switching control means switches to the output at the low speed charging frequency in response to the output cycle number of the pair of switching signals at the high speed charging frequency.   3. The inverter switching control means switches the output of a pair of switching signals at a high speed charging frequency to an output at a low speed charging frequency in response to a detection voltage of the charging voltage detection means. Power supply for the magnetizer.

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