JP5410002B2 - Lifting magnet control system - Google Patents

Description

  The present invention relates to a lifting magnet control system.

  Lifting magnets are used to lift and carry suspended loads such as iron pieces in construction work and the like, and are installed at the tip of a vehicle arm such as a hydraulic excavator. When using a lifting magnet, current is passed in a certain direction to excite the lifting magnet, and the suspended load is attracted and lifted. Then, when releasing the suspended load, the lifting magnet is demagnetized by passing a current in the opposite direction.

  FIG. 7 shows a conventional system configuration for supplying such excitation current and release current to the lifting magnet. The lifting magnet control system 100 shown in FIG. 1 includes an induction AC generator 102, a DC conversion unit 104 that converts AC power output from the induction AC generator 102 into DC power, and a DC output that is output from the DC conversion unit 104. An H bridge circuit 108 that supplies power to the magnet 106 while controlling the direction of electric power, and a large-capacity capacitor 116 for regenerating energy stored in the magnet 106 are provided. The lifting magnet control system 100 includes an automatic voltage regulator (AVR) 110 that adjusts the AC voltage output from the induction AC generator 102 by controlling the field current of the generator 102; And a power supply module 114 that generates a DC power supply voltage supplied to the bridge driver 112 that drives the H-bridge circuit 108 from an AC voltage from the induction generator 102. When the control system 100 is mounted on a vehicle, the vehicle includes a hydraulic pump driven by an engine and a hydraulic motor driven by the hydraulic pump, and the induction generator 102 is driven by the hydraulic motor. The

Patent Document 1 discloses a self-propelled working machine equipped with a lifting magnet. This self-propelled working machine includes a system similar to the lifting magnet control system 100 described above. In this self-propelled working machine, the AC voltage output from the generator is adjusted by a chopper control method using the leakage inductance of the transistor and the generator.
JP 2004-299818 A

  Recently, in construction sites and the like, it is required to make the rear end turning radius of the hydraulic excavator smaller, and also to improve the visibility from the cab. Therefore, further downsizing is desired for a lifting magnet drive system that is often mounted behind the cab of a hydraulic excavator. The present invention has been made in view of such problems, and an object of the present invention is to provide a lifting magnet drive system that is mounted on a vehicle equipped with a lifting magnet and can be further reduced in size.

In order to solve the above-described problems, a lifting magnet control system according to the present invention is a lifting magnet control system mounted on a vehicle equipped with a lifting magnet, and is supplied from a permanent magnet synchronous generator and a permanent magnet synchronous generator. DC power is converted to DC power and the DC power is provided between the positive output terminal and the negative output terminal, and a plurality of transistors are included to control the direction of the DC power. The H bridge circuit section that supplies the DC power to the lifting magnet is electrically connected between the positive output terminal and the negative output terminal, and is stored in the lifting magnet when the direction of the DC power is switched. a resistor for absorbing the energy, resistor and a switch connected elements in series, connected in parallel to the resistor and a switch element The capacitive element, the control unit that controls the conduction state in the switch element, the first wiring that connects the positive output terminal and the H bridge circuit unit to each other, and the negative output terminal and the H bridge circuit unit are connected to each other. And a switch element and a resistor are electrically connected between the first wiring and the second wiring .

  This lifting magnet control system includes a permanent magnet (PM) synchronous generator as a generator. Since the PM synchronous generator uses a permanent magnet for the field, the power generation efficiency is high, and the PM synchronous generator can be made smaller than an induction generator having the same rated output. Therefore, it can contribute to size reduction of the lifting magnet control system.

  Here, for example, if the induction generator is simply replaced with a PM synchronous generator in the conventional system shown in FIG. 7, the following problems arise. That is, in a vehicle such as a hydraulic excavator, when the engine speed increases, the hydraulic pressure increases, and the rotational speed of the generator driven by the hydraulic motor also increases. With an induction generator, the output voltage can be suppressed by decreasing the field current as the rotational speed increases, but with the PM synchronous generator, the field voltage cannot be adjusted, so the output voltage increases in proportion to the rotational speed. Resulting in. However, in the system shown in FIG. 7, the large-capacitance capacitor 116 for energy regeneration cannot withstand this voltage, and the rotational speed is limited, so that it is difficult to put it to practical use.

  On the other hand, in the above-described lifting magnet control system, the energy stored in the lifting magnet is absorbed by the resistor when the direction of the DC power is switched. As a result, the influence of an increase in the output voltage of the generator can be reduced, so that a PM synchronous generator can be used as the generator, and voltage adjusting means such as a chopper control circuit described in Patent Document 1 can be reduced. The magnet control system can be suitably downsized. Moreover, by using a PM synchronous generator, the automatic voltage regulator shown in FIG. 7 can be reduced, and the system can be further simplified.

In addition, lifting magnet control system of this is, can operate in the following manner. That is, when the exciting current is stopped and accumulated energy is generated in the lifting magnet, the current due to the accumulated energy flows to the capacitive element for a time until the control unit is made conductive by the switch element. When the switch element is turned on by the control unit, most of the current due to the stored energy is consumed by the resistor. Thus, according to the above-described lifting magnet control system, the energy accumulated in the lifting magnet can be suitably absorbed when the direction of the DC power is switched.

  In addition, the lifting magnet control system includes a current measuring unit that measures the direction and magnitude of a current flowing between a circuit portion including a resistor, a switch element, and a capacitive element, and an H bridge circuit unit, and a positive output terminal. It further includes at least one measurement unit of a potential difference measurement unit that measures a potential difference with the negative output terminal, and the control unit is based on the measurement result of at least one of the direction and magnitude of the current and the potential difference, It is good also as controlling the conduction state in a switch element. As a result, the generation timing and cancellation timing of the current due to the stored energy can be accurately known, so that the control unit makes the switch element conductive before the voltage across the capacitor element becomes excessive, and the current due to the stored energy is Can be flowed to.

  ADVANTAGE OF THE INVENTION According to this invention, the lifting magnet drive system which is mounted in the vehicle equipped with the lifting magnet and can be reduced in size can be provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a lifting magnet control system according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In the following description, a transistor includes both a bipolar transistor and a field effect transistor (FET). When the transistor is an FET, the base is read as the gate, the collector as the drain, and the emitter as the source.

  FIG. 1 is a perspective view illustrating a configuration of a lifting magnet vehicle that is a work machine on which the lifting magnet control system according to the present embodiment is mounted. As shown in FIG. 1, a lifting magnet vehicle (hereinafter referred to as a magnet vehicle) 1 is a lifting magnet (hereinafter referred to as a lifting magnet) that attracts and captures a suspended load 90 such as a steel material by a magnetic force at the tip of an arm 12 of a hydraulic excavator (base machine). , Magnet) 10 is mounted. Further, the magnet vehicle 1 includes a cab 14 for accommodating an operator who operates the position of the magnet 10, the excitation operation, and the release operation.

  A lifting magnet control system (hereinafter referred to as a magnet control system) 2 mounted on the magnet vehicle 1 includes a magnet control panel 3 that supplies power to the magnet 10 and a PM synchronous generator that supplies three-phase AC power to the magnet control panel 3. 4 and a battery (storage battery) 5 for supplying a DC power supply voltage to the magnet control panel 3. The magnet vehicle 1 is equipped with a hydraulic pump driven by the engine of the vehicle 1 and a hydraulic motor driven by the hydraulic pressure from the hydraulic pump, and the PM synchronous generator 4 is driven by the hydraulic motor. The

FIG. 2 is a block diagram showing the configuration of the magnet control system 2 according to the present embodiment. As described above, the magnet control system 2 includes the magnet control panel 3, the PM synchronous generator 4, and the battery 5. The magnet control panel 3 has a magnet drive circuit 31 and a bridge driver 32. The magnet drive circuit 31 receives the three-phase AC power supply voltages V _{AC1 to} V _AC3 from the PM synchronous generator 4, and the bridge driver 32 is a battery. 5 receives DC power supply voltage _VBAT . The magnet drive circuit 31 is a circuit that supplies power (excitation current I ₁ , release current I ₂ ) to the magnet 10, and includes an H bridge circuit unit that controls the direction of the current flowing through the magnet 10. The bridge driver 32 is a circuit that drives the H-bridge circuit unit, and the DC power supply voltage V _BAT is constant (for example, DC 24V).

  FIG. 3 is a circuit diagram showing a configuration of the magnet drive circuit 31. Referring to the figure, the magnet drive circuit 31 includes a DC conversion unit 33, an H bridge circuit unit 34, an energy absorption unit 35, a control unit 36, a current measurement unit 37, and a potential difference measurement unit 38.

The DC converter 33 is a circuit portion for converting the AC power supply voltages V _{AC1 to} V _AC3 supplied from the PM synchronous generator 4 into the DC power supply voltage V _DC . The DC converter 33 has a positive output end 33i and a negative output end 33j, and provides the generated DC power supply voltage _VDC between the positive output end 33i and the negative output end 33j. Each of the positive output terminal 33i and the negative output terminal 33j is electrically connected to the positive power supply line 33g and the negative power supply line 33h, which are wirings for supplying power to the lifting magnet 10. Yes.

  The DC converter 33 of the present embodiment is configured by a bridge circuit including six diodes 33a to 33f, and performs three-phase full-wave rectification. In addition to this, the DC conversion unit may be configured by, for example, a pure bridge circuit using a thyristor or a mixed bridge circuit using a diode and a thyristor. In the case where the DC conversion unit is configured by a pure bridge circuit or a mixed bridge circuit, the thyristor is phase-controlled at a predetermined control angle by a phase control circuit (not shown).

  The H bridge circuit unit 34 is a circuit part for controlling the direction of the current supplied to the magnet 10. The H bridge circuit section 34 includes four transistors 34a to 34d and four diodes (rectifiers) electrically connected between current terminals (between the collector and the emitter or between the source and drain) of the four transistors 34a to 34d. (Elements) 34e to 34h and terminals 34i and 34j to which wires 18a and 18b for supplying current to the magnet 10 are connected.

  Specifically, one current terminal of the transistor 34a is electrically connected to the positive power supply line 33g, and the other current terminal of the transistor 34a is electrically connected to the terminal 34i. One current terminal of the transistor 34b is electrically connected to the terminal 34i, and the other current terminal of the transistor 34b is electrically connected to the negative power supply line 33h. One current terminal of the transistor 34c is electrically connected to the positive power supply line 33g, and the other current terminal of the transistor 34c is electrically connected to the terminal 34j. One current terminal of the transistor 34d is electrically connected to the terminal 34j, and the other current terminal of the transistor 34d is electrically connected to the negative power supply line 33h. The anodes of the diodes 34e to 34h are electrically connected to the other current terminals of the transistors 34a to 34d, respectively, and the cathodes of the diodes 34e to 34h are electrically connected to one of the current terminals of the transistors 34a to 34d, respectively. It is connected to the.

The bases of the transistors 34a to 34d are electrically connected to the bridge driver 32 (see FIG. 2). The conduction state between the collector and the emitter in each of the transistors 34a to 34d is a control current Sa provided from the bridge driver 32. Controlled by ~ Sd. For example, when the control current Sa to the base terminal of the transistor 34a and 34d, Sd are provided, the exciting current _{I 1} in the positive direction, the transistor 34a, the terminal 34i, the magnet 10, through the terminal 34j, and the order of the transistor 34d. The control current Sb to the base terminal of the transistor 34b and 34c, the Sc is provided, opposite the direction of release current (demagnetizing current) _{I 2} is, transistor 34c, the terminal 34j, magnet 10, the terminal 34i, and the transistor 34b sequentially flows (i.e., in the opposite direction to the exciting current I _1).

The energy absorption part 35 is a circuit part for absorbing the energy accumulated in the magnet 10 when the excitation current I ₁ to the magnet 10 is switched to the release current I ₂ . The energy absorption unit 35 includes an npn transistor 35a, a diode (rectifier element) 35b, a resistor 35c, and a capacitor (capacitor element) 35d. The diode 35b is arranged as necessary and can be omitted.

  The transistor 35a and the resistor 35c are electrically connected between the positive power supply line 33g and the negative power supply line 33h, and are connected in series with each other. Specifically, the collector terminal of the transistor 35a is electrically connected to the positive power supply line 33g, and the emitter terminal of the transistor 35a is electrically connected to one end of the resistor 35c. The other end of the resistor 35c is electrically connected to the negative power supply line 33h. The cathode and anode of the diode 35b are electrically connected to the collector terminal and the emitter terminal of the transistor 35a, respectively. A control current Se is supplied from a control unit 36 described later to the base terminal of the transistor 35a, and the conduction state of the transistor 35a is controlled by the control current Se. The capacitor 35d is connected in parallel to the transistor 35a and the resistor 35c. As the capacitor 35d, a capacitor having a significantly smaller capacity and a higher withstand voltage is used as compared with a conventional large capacity capacitor for energy regeneration.

  The current measuring unit 37 measures the direction and magnitude of the current flowing toward the energy absorbing unit 35 through the positive power supply line 33g between the H bridge circuit unit 34 and the energy absorbing unit 35. The current measuring unit 37 provides the control unit 36 with a current signal Si indicating the direction and magnitude of the current as a measurement result. The potential difference measuring unit 38 is a circuit portion for measuring a potential difference between the positive power supply line 33g and the negative power supply line 33h. The potential difference measuring unit 38 provides the control unit 36 with a potential difference signal Sv indicating a potential difference as a measurement result. The magnet drive circuit 31 of the present embodiment includes both the current measurement unit 37 and the potential difference measurement unit 38, but the magnet drive circuit 31 includes only one of the current measurement unit 37 and the potential difference measurement unit 38. Also good.

  The control unit 36 controls the conduction state in the transistor 35a of the energy absorbing unit 35 based on the current signal Si and the potential difference signal Sv. The control unit 36 outputs a control current Se when a current from the H-bridge circuit unit 34 to the energy absorption unit 35 is generated, or when the potential difference signal Sv is equal to or greater than a predetermined value. Conduction between emitters. In addition, the control unit 36 stops the output of the control current Se when the current signal Si becomes equal to or lower than a predetermined value or when the potential difference signal Sv becomes equal to or lower than the predetermined value in a state where the transistor 35a is conductive. Thus, the collector-emitter of the transistor 35a is disconnected.

Here, the arrangement of components inside the magnet control panel 3 will be described. FIG. 4 is a side view showing the inside of the magnet control panel 3. The magnet control panel 3 has a metal case 39, and the magnet drive circuit 31 and the bridge driver 32 described above are built in the case 39. In the figure, A is a cooling fan, B is diode module (diode 33a~33f DC converter 33 in this is contained), C is the transistor 35a of the energy absorbing portion _{35, D 1,} D ₂ are IGBT Module (in which the transistors 34a to 34d of the H-bridge circuit unit 34 are housed), E is a CPU board including the bridge driver 32, F is a resistor 35c of the energy absorption unit 35, and G includes a control unit 36 A wiring board, H and I are detection circuits for detecting current and voltage to the magnet 10, and J is a terminal block. K is a space for mounting the automatic voltage regulator, and nothing is installed in this embodiment. The automatic voltage regulator is installed to adjust the output voltage of the induction generator when the PM synchronous generator 4 is replaced with the induction generator.

  Next, the operation of the magnet drive circuit 31 will be described. 5 shows (a) a voltage applied to both ends of the magnet 10, (b) an amount of current in the positive power supply line 33g between the H bridge circuit section 34 and the energy absorbing section 35, and (c) a positive power supply. It is a graph which shows a time waveform of the potential difference between the line 33g and the negative power supply line 33h, respectively. 5B, the direction of the current from the H bridge circuit unit 34 to the energy absorption unit 35 is positive.

First, at a certain time t ₀ , the PM synchronous generator 4 is driven to generate three-phase AC power supply voltages V _{AC1 to} V _AC3 . These AC power supply voltages V _{AC1 to} V _AC3 are converted into the DC power supply voltage V _DC by the DC conversion unit 33 and provided to the H bridge circuit unit 34 (see FIG. 5C). Then, at time _{t 1,} to excite the magnet 10. That is, the bridge driver 32 makes the transistors 34a and 34d of the H bridge circuit section 34 conductive. Accordingly, the transistor 34a, the magnet 10, the exciting current _{I 1} flows in the order of the transistor 34d (see Figure 5 (b)). That is, the excitation voltage V is output between the terminal 34i and the terminal 34j of the H bridge circuit unit 34 (see FIG. 5A). Thereby, the magnet 10 is excited and can attract and lift an iron piece or the like.

Subsequently, the operation moves to release iron pieces from the magnet 10. First, at time _{t 2,} to release the excitation of the magnet 10. That is, the bridge driver 32 disables the transistors 34a and 34d of the H bridge circuit unit 34. At this time, due to the energy accumulated in the magnet 10, a voltage due to the back electromotive force is generated at both ends of the magnet 10 (that is, between the terminals 34i and 34j) (Q portion in FIG. 5A). At the same time, a current (R portion in FIG. 5B) resulting from the back electromotive force flows through the diode 34f, the magnet 10, and the diode 34g.

  At this time, the current due to the accumulated energy flows to the capacitor 35d of the energy absorption unit 35 for a very short time until the control unit 36 conducts the transistor 35a of the energy absorption unit 35. As the voltage across the capacitor 35d increases, the potential difference between the positive power line 33g and the negative power line 33h increases (S portion in FIG. 5C).

When the current due to the stored energy flows through the positive power supply line 33g, the current flows from the H bridge circuit section 34 to the energy absorption section 35, so that the direction of the current in the positive power supply line 33g is reversed. The control unit 36 recognizes that the current from the H bridge circuit unit 34 to the energy absorption unit 35 is generated by the current signal Si, thereby recognizing that the current due to the stored energy flows through the positive power supply line 33g. (Point P _{1 in} FIG. 5B). Then, the control unit 36 outputs a control current Se to conduct between the collector and emitter of the transistor 35a. As a result, the current due to the stored energy flows to the resistor 35c via the transistor 35a, and is gradually attenuated while being consumed in the resistor 35c.

Alternatively, since the voltage between both ends of the capacitor 35d increases due to the current due to the stored energy flowing to the capacitor 35d, the control unit 36 determines that the potential difference between the positive power line 33g and the negative power line 33h is a predetermined value V _th1. Also by the above, it can be recognized that the current due to the stored energy is flowing through the positive power supply line 33g (that is, even if the potential difference signal Sv from the potential difference measuring unit 38 becomes a predetermined value or more) (FIG. 5). (C) point P ₂ ). In such a case, the control unit 36 may output a control current Se to make the collector-emitter of the transistor 35a conductive.

Subsequently, when the magnitude of the current (current signal Si) from the H-bridge circuit unit 34 toward the energy absorption unit 35 becomes equal to or less than the predetermined value _Ith2 (point P _{3 in} FIG. 5B), the control unit 36 stores data. Recognize that the current due to energy is sufficiently attenuated. Then, the control unit 36 stops the output of the control current Se and disconnects between the collector and the emitter of the transistor 35a. The predetermined value I _th2 is preferably a value as close as possible to 0 [A].

Alternatively, also by the potential difference between the positive power supply line 33g and the negative side power line 33h is equal to or less than a predetermined value V _th3, (i.e., by the potential difference signal Sv from the potentiometric unit 38 is equal to or less than the predetermined value )) It can be recognized that the current due to the stored energy is sufficiently attenuated (point P _{4 in} FIG. 5C). In such a case, the control unit 36 may stop the output of the control current Se and disconnect between the collector and the emitter of the transistor 35a.

Then, at time _{t 3,} to demagnetize the magnet 10. That is, the bridge driver 32 makes the transistors 34b and 34c of the H bridge circuit section 34 conductive. Thus, the transistor 34c, the magnet 10, and the order of the transistor 34b release current _{I 2} flows (see Figure 5 (b)). That is, the release (demagnetization) voltage −V is output between the terminal 34 i and the terminal 34 j of the H-bridge circuit unit 34 (see FIG. 5A). Thereby, the magnet 10 is demagnetized and the iron piece etc. which were adsorbed can be released.

After demagnetization is complete, the non-delivery of the transistors 34b and 34c of the H-bridge circuit portion 34 at time _{t 4.} At this time, due to the energy accumulated in the magnet 10, a voltage due to the back electromotive force is generated at both ends of the magnet 10 (that is, between the terminals 34i and 34j) (T portion in FIG. 5A). At the same time, a current (the U portion in FIG. 5B) resulting from the counter electromotive force flows through the diode 34h, the magnet 10, and the diode 34e. The current due to the stored energy is absorbed by the energy absorbing unit 35 in the same manner as the above-described operation.

  The effect which the magnet control system 2 concerning this embodiment shows is explained. The magnet control system 2 includes a PM synchronous generator 4 as a generator. Since the PM synchronous generator 4 uses a permanent magnet for the field, the power generation efficiency is high, and the PM synchronous generator 4 can be configured smaller than an induction generator having the same rated output. For example, the external dimensions of a certain induction generator (YD-18502 manufactured by Seiko Co., Ltd.) that generates a rated output of 20 kVA at a rated rotational speed of 1800 rpm are 567 mm and a diameter of 380 mm. The external dimensions of a certain PM synchronous generator (YH553725a manufactured by Fuji Electric Motor), which generates a rated output of 20 kVA at a rated rotational speed of 2000 rpm, are remarkably small, with the body portion having a length of 461 mm and a diameter of 272 mm. Therefore, by using the PM synchronous generator 4 as a generator, it is possible to contribute to miniaturization of the magnet control system 2.

  Moreover, if the induction generator is simply replaced with a PM synchronous generator in the conventional system, the following problem occurs. That is, in a vehicle such as a hydraulic excavator, when the engine speed increases, the hydraulic pressure increases, and the rotational speed of the generator driven by the hydraulic motor also increases. With an induction generator, the output voltage can be suppressed by decreasing the field current as the rotational speed increases, but with the PM synchronous generator, the field voltage cannot be adjusted, so the output voltage increases in proportion to the rotational speed. Resulting in.

  Here, FIGS. 6A and 6B are graphs showing examples of general output voltage characteristics of the PM synchronous generator and the induction generator, respectively. In FIGS. 6A and 6B, the horizontal axis represents the rotational speed [rpm] of the generator. As shown in FIG. 6B, the output voltage of the induction generator can be limited to a predetermined value (about 220 V in the figure) by an automatic voltage regulator or the like. On the other hand, as shown in FIG. 6A, the output voltage of the PM synchronous generator rises in proportion to the increase in the rotational speed.

  Conventionally, the energy stored in the magnet is generally regenerated using the capacitor 116 shown in FIG. A capacitor having a relatively large capacity is used as the capacitor 116. However, if the withstand voltage of the large capacity capacitor is increased, the cost is increased and the size is increased. In addition, when this large-capacity capacitor cannot withstand the output voltage of the generator, the rotational speed of the generator is limited, and as a result, the engine rotational speed of the vehicle is limited, making it difficult to put to practical use. .

  On the other hand, in the magnet control system 2 of this embodiment, the stored energy is absorbed by the resistor 35c. Thereby, since the influence by the increase in the output voltage of PM synchronous generator 4 can be reduced, it becomes possible to employ | adopt PM synchronous generator as a generator and the magnet control system 2 can be reduced in size suitably. Moreover, since the automatic voltage regulator can be reduced by using the PM synchronous generator 4 as a generator, the system can be further simplified.

  Further, since the PM synchronous generator uses a permanent magnet for the field, the power generation efficiency is higher than that of the induction generator that requires a field current. Therefore, the fuel efficiency of the magnet vehicle 1 is improved. In addition, since a larger hydraulic pressure can be allocated to the operation of the arm 12, the operation of the arm 12 can be accelerated. Thereby, the operator of the lifting magnet 10 can perform work more efficiently.

  Further, as in the present embodiment, the magnet control system 2 includes a switch element (transistor 35a) connected in series with the resistor 35c, a capacitor 35d connected in parallel to the resistor 35c and the transistor 35a, It is preferable to further include a control unit 36 that controls the conduction state of the transistor 35a. Thereby, when the direction of direct-current power switches, the energy accumulate | stored in the lifting magnet 10 can be absorbed suitably.

  Further, as in the present embodiment, the magnet control system 2 includes at least one of the current measurement unit 37 and the potential difference measurement unit 38, and the control unit 36 determines the direction of the current measured by the current measurement unit 37. It is preferable to control the conduction state of the transistor 35a based on the measurement result of at least one of the difference in magnitude, the magnitude, and the potential difference detected by the potential difference measurement unit 38. As a result, the generation timing and the cancellation timing of the current due to the stored energy can be known with high accuracy. Therefore, before the voltage at both ends of the capacitor 35d becomes excessive, the control unit 36 conducts the transistor 35a to resist the current due to the stored energy. Can flow to the vessel 35c.

  The lifting magnet control system according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, in the above embodiment, a three-phase AC generator is exemplified as the generator. However, as the generator of the present invention, various generators can be applied regardless of the number of phases as long as it is a PM synchronous generator. .

It is a perspective view which shows the structure of a magnet vehicle. It is a block diagram which shows the structure of a magnet control system. It is a circuit diagram which shows the structure of a magnet drive circuit. It is a side view which shows the inside of a magnet control board. (A) the voltage applied to both ends of the magnet, (b) the amount of current in the positive power supply line between the H bridge circuit section and the energy absorption section, and (c) the positive power supply line and the negative power supply line It is a graph which shows each time waveform of the potential difference between. (A) It is a graph which shows an example of the general output voltage characteristic of PM synchronous generator. (B) It is a graph which shows an example of the general output voltage characteristic of an induction generator. It is a figure which shows the conventional system structure for supplying an exciting current and a release current to a magnet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lifting magnet vehicle, 2 ... Lifting magnet control system, 3 ... Magnet control panel, 4 ... PM synchronous generator, 5 ... Battery, 10 ... Lifting magnet, 12 ... Arm, 14 ... Driver's cab, 31 ... Magnet drive circuit, 32 ... Bridge driver, 33 ... DC conversion unit, 34 ... Bridge circuit unit, 35 ... Energy absorption unit, 36 ... Control unit, 37 ... Current measurement unit, 38 ... Potential difference measurement unit, 39 ... Housing, 90 ... Suspended load, I ₁ ... excitation current, I ₂ ... release current, V _{AC1 to} V _AC3 ... three-phase AC power supply voltage, V _BAT ... DC power supply voltage.

Claims (2)

A lifting magnet control system mounted on a vehicle equipped with a lifting magnet,
A permanent magnet synchronous generator,
A DC converter that converts AC power supplied from the permanent magnet synchronous generator into DC power and provides the DC power between a positive output end and a negative output end;
An H-bridge circuit unit configured to include a plurality of transistors and control the direction of the DC power to supply the DC power to the lifting magnet;
A resistor that is electrically connected between the positive output end and the negative output end and absorbs energy stored in the lifting magnet when the direction of the DC power is switched ;
A switch element connected in series with the resistor;
A capacitive element connected in parallel to the resistor and the switch element;
A control unit for controlling a conduction state in the switch element;
A first wiring that connects the positive output end and the H-bridge circuit section to each other;
A second wiring for connecting the negative output end and the H-bridge circuit section to each other ;
The lifting magnet control system, wherein the switch element and the resistor are electrically connected between the first wiring and the second wiring . A current measuring unit for measuring the direction and magnitude of a current flowing between the circuit portion including the resistor, the switch element, and the capacitive element and the H-bridge circuit unit; and the positive output terminal and the negative side It further comprises at least one measurement unit of a potential difference measurement unit that measures a potential difference with the output terminal,
2. The lifting magnet according to claim 1 , wherein the control unit controls a conduction state of the switch element based on a measurement result of at least one of the direction and magnitude of the current and the potential difference. Control system.

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