Solenoid coil drive circuit

Abstract

The electromagnetic coil drive circuit (3) comprises: a first switch element (41) which is arranged between a first power line (36) on a high potential side and a second power line (37) on a low potential side via an electromagnetic coil (5); a first drive circuit (341) which drives the first switch element (41) using a first voltage applied between the first power line (36) and the second power line (37); a second switch element (42) which is arranged between the first power line (36) and the third power line (38) on a low potential side via an electromagnetic coil (5); a second drive circuit (342) which drives the second switch element (42) using a second voltage applied between the first power line (36) and the third power line (38); and a step-down circuit (32) which generates a second voltage by stepping down the first voltage using the first voltage.

Description

Technical Field

[0001] The present invention relates to an electromagnetic coil drive circuit for driving an electromagnetic coil such as an electromagnetic solenoid or an operating coil of an electromagnetic contactor. Background Art

[0002] Conventionally, the following technology is known, that is, when the movable iron core is adsorbed to the fixed iron core during the adsorption action, and when the state of the movable iron core adsorbed to the fixed iron core is maintained during the adsorption holding, the excitation current flowing in the operating coil that drives the movable iron core of the electromagnetic contactor is different. For example, in the following patent document 1, regarding the pulse signal applied to the switching element that controls the excitation current flowing in the operating coil, the ratio of the on time is relatively increased during the adsorption action, and the ratio of the on time is relatively reduced during the adsorption holding, thereby changing the excitation current to the operating coil.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2004-186052 Summary of the invention

[0004] However, in Patent Document 1, in order to change the excitation current flowing through the operating coil during the adsorption action and adsorption holding of the movable iron core, a pulse width modulation (PWM) technology is required to control the pulse width of the pulse signal according to the magnitude of the excitation current. Therefore, there is a problem of increasing the complexity and scale of the circuit, and increasing the manufacturing cost and power consumption.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain an electromagnetic coil drive circuit capable of suppressing the complexity and size of the circuit and achieving reductions in manufacturing cost and power consumption.

[0006] In order to solve the above-mentioned problems and achieve the purpose, the electromagnetic coil drive circuit involved in the present invention has a first and a second switching element, a first and a second driving circuit, and a step-down circuit. The first switching element is arranged between the first power line on the high potential side and the second power line on the low potential side via the electromagnetic coil, and is arranged at a lower potential side than the electromagnetic coil. The first driving circuit drives the first switching element using the first voltage applied between the first power line and the second power line. The second switching element is arranged between the first power line and the third power line on the low potential side via the electromagnetic coil, and is arranged at a lower potential side than the electromagnetic coil. The second driving circuit drives the second switching element using the second voltage applied between the first power line and the third power line. The step-down circuit uses the first voltage to generate a second voltage after stepping down the first voltage.

[0007] Effects of the Invention

[0008] According to the electromagnetic coil drive circuit according to the present invention, there is an effect that it is possible to suppress the complexity and size of the circuit, and to achieve reductions in manufacturing cost and power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a diagram showing an example of the electromagnetic coil drive circuit according to the first embodiment.

[0010] Figure 2 This is a diagram showing a configuration example of an electromagnetic coil drive circuit according to the first embodiment.

[0011] Figure 3 This is a timing chart used in describing the operation of the electromagnetic coil drive circuit according to the first embodiment.

[0012] Figure 4 This is a diagram showing a configuration example of an electromagnetic coil and an inductor according to the second embodiment.

[0013] Figure 5 Yes means Figure 4 A cross-sectional view of a cross section of the electromagnetic coil and inductor is shown.

[0014] Figure 6 This is a diagram showing a configuration example of an electromagnetic coil drive circuit according to the third embodiment. DETAILED DESCRIPTION

[0015] Hereinafter, an electromagnetic coil drive circuit according to Embodiment 1 of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following Embodiment 1. In the following, electrical connection and physical connection are not distinguished and are simply referred to as "connection".

[0016] Implementation method 1.

[0017] Figure 1 FIG. 2 is a diagram showing an example of an electromagnetic coil drive circuit according to Embodiment 1. Figure 1 , an AC power source 1 , a full-wave rectifying circuit 2 , an electromagnetic coil driving circuit 3 , an electromagnetic coil 5 , and a driven portion 6 having a fixed iron core 61 and a movable iron core 62 are shown.

[0018] One example of the electromagnetic coil 5 is a solenoid coil included in a circuit breaker. Another example of the electromagnetic coil is an operating coil of an electromagnetic contactor.

[0019] The electromagnetic coil drive circuit 3 has DC input terminals T1 and T2. A rectified voltage rectified by the full-wave rectifier circuit 2 is applied between the DC input terminals T1 and T2. The full-wave rectifier circuit 2 generates a rectified voltage using an AC voltage output from an AC power supply 1. The electromagnetic coil drive circuit 3 controls the excitation current flowing in the electromagnetic coil 5 based on the rectified voltage. The details of the control of the excitation current will be described later.

[0020] When an excitation current flows through the electromagnetic coil 5, the movable iron core 62 is pulled by the electromagnetic force caused by the excitation current. As a result, the movable iron core 62 is adsorbed by the fixed iron core 61. In the first embodiment, the operation of the electromagnetic coil drive circuit 3 is different in the adsorption operation of adsorbing the movable iron core 62 to the fixed iron core 61 and the adsorption and holding operation of maintaining the state in which the movable iron core 62 is adsorbed to the fixed iron core 61. The details of each operation will be described later.

[0021] Figure 2 1 is a diagram showing a configuration example of an electromagnetic coil drive circuit according to Embodiment 1. The electromagnetic coil drive circuit 3 according to Embodiment 1 includes, as main components, a first capacitor 31, a voltage-reducing circuit 32, a second capacitor 33, a switching element drive circuit 34, a first switching element 41, and a second switching element 42. Furthermore, the electromagnetic coil drive circuit 3 includes a first diode 43, a second diode 44, a current suppressing circuit 45, and a third diode 46.

[0022] The switching element driving circuit 34 includes a first driving circuit 341, a second driving circuit 342, and a voltage detection circuit 343. The step-down circuit 32 includes a diode 321, an inductor 322, a power supply IC 323, and a voltage detection circuit 324.

[0023] One end of the first capacitor 31 is connected to the first power line 36. The other end of the first capacitor 31 is connected to the second power line 37 via the third diode 46. The anode of the third diode 46 is connected to the other end of the first capacitor 31. The cathode of the third diode 46 is connected to the second power line 37.

[0024] The first power line 36 is a power line on the high potential side connected to the DC input terminal T1. The second power line 37 is a power line on the low potential side connected to the DC input terminal T2. As described above, a rectified voltage rectified by the full-wave rectifier circuit 2 is applied between the DC input terminals T1 and T2. The rectified voltage is determined by the AC voltage output from the AC power supply 1 and the forward voltage drop of the diode provided in the full-wave rectifier circuit 2. The rectified voltage is applied between the first power line 36 and the second power line 37. If the forward voltage drop of the third diode 46 is ignored, the voltages at both ends of the first capacitor 31 are equal to the rectified voltage. In addition, in the following description, the voltage applied between the first power line 36 and the second power line 37 is sometimes referred to as the "first voltage".

[0025] In the step-down circuit 32, the cathode of the diode 321 is connected to the first power line 36. The anode of the diode 321 is connected to one end of the inductor 322. The other end of the inductor 322 is connected to the third power line 38. The third power line 38 is grounded. A power IC 323 is inserted between a connection point 325 between the anode of the diode 321 and one end of the inductor 322 and the anode of the third diode 46. A switch section 323a for opening and closing the connection between the first power line 36 and the second power line 37 is provided inside the power IC 323. The operation of the step-down circuit 32 will be described in detail later.

[0026] One end of the second capacitor 33 is connected to the first power line 36. The other end of the second capacitor 33 is connected to the third power line 38. The voltage detection circuit 324 is connected between the first power line 36 and the third power line 38 so as to measure the voltage across the second capacitor 33. In the following description, the voltage applied between the first power line 36 and the third power line 38 is sometimes referred to as "second voltage".

[0027] In addition, in the switching element driving circuit 34, one end of the first driving circuit 341 is connected to the first power line 36. The other end of the first driving circuit 341 is connected to the second power line 37. One end of the second driving circuit 342 is connected to the first power line 36. The other end of the second driving circuit 342 is connected to the third power line 38. The voltage detection circuit 343 is connected between the first power line 36 and the second power line 37 so that the voltage across the first capacitor 31 can be measured. The operation of the switching element driving circuit 34 will be described in detail later.

[0028] The first drive circuit 341 drives the first switch element 41. The second drive circuit 342 drives the second switch element 42. An example of each of the first switch element 41 and the second switch element 42 is a metal oxide semiconductor field effect transistor (MOSFET) shown in the figure. A bipolar transistor may be used instead of a MOSFET.

[0029] The first terminal, i.e., the source, of the first switching element 41 is connected to the second power supply line 37. The first terminal is a terminal on the low potential side of the first switching element 41. The second terminal, i.e., the drain, of the first switching element 41 is connected to the first power supply line 36 via the electromagnetic coil 5. The second terminal is a terminal on the high potential side of the first switching element 41. The gate, i.e., the driving terminal of the first switching element 41 is connected to the first driving circuit 341. The first diode 43 is connected to both ends of the electromagnetic coil 5.

[0030] As described above, the first switching element 41 is arranged on the lower potential side than the electromagnetic coil 5. The first switching element 41 is arranged between the first power line 36 on the high potential side and the second power line 37 on the low potential side via the electromagnetic coil 5.

[0031] The first terminal, i.e., the source, of the second switching element 42 is connected to the third power line 38 via the current suppression circuit 45. The first terminal is a terminal on the low potential side of the second switching element 42. The second terminal, i.e., the drain, of the second switching element 42 is connected to the first power line 36 via the electromagnetic coil 5 and the second diode 44. The second terminal is a terminal on the high potential side of the second switching element 42. The gate, i.e., the driving terminal of the second switching element 42 is connected to the second driving circuit 342 and the current suppression circuit 45. The anode of the second diode 44 is connected to the electromagnetic coil 5. The cathode of the second diode 44 is connected to the drain of the second switching element 42.

[0032] As described above, the second switching element 42 is arranged on the lower potential side than the electromagnetic coil 5. The second switching element 42 is arranged between the first power line 36 on the high potential side and the third power line 38 on the low potential side via the electromagnetic coil 5.

[0033] Next, the preparatory operation of the electromagnetic coil drive circuit 3 according to Embodiment 1 is described. First, the first capacitor 31 holds a first voltage substantially equal to the rectified voltage. As described above, the rectified voltage is determined by the AC voltage output from the AC power supply 1 and the forward voltage drop of the diode included in the full-wave rectifier circuit 2. In this specification, the case where the first voltage is 200 [V] is exemplified.

[0034] The first voltage is applied to the step-down circuit 32. The step-down circuit 32 uses the first voltage to generate a second voltage obtained by stepping down the first voltage. The second voltage is maintained by the second capacitor 33. If the switch section 323a of the power IC 323 is controlled to be turned on, current flows through the path of the DC input terminal T1, the second capacitor 33, the inductor 322, the power IC 323, and the DC input terminal T2. At this time, electromagnetic energy is accumulated in the inductor 322. If the switch section 323a is controlled to be turned off, the electromagnetic energy accumulated in the inductor 322 becomes an electromotive force, and current flows through the path of one end of the inductor 322, the diode 321, the second capacitor 33, and the other end of the inductor 322.

[0035] By controlling the ratio of the on time to the sum of the on time and the off time of the switch section 323a, a predetermined second voltage is maintained in the second capacitor 33. During the period when the second voltage is maintained, the on-off operation of the switch section 323a is stopped. The second voltage is monitored by the voltage detection circuit 324. If the charge of the second capacitor 33 is used, the second voltage decreases. If the second voltage decreases, the on-off operation of the switch section 323a is restored.

[0036] In addition, in this specification, the case where the second voltage is 20 [V] is exemplified, but the present invention is not limited thereto. The second voltage may be a voltage other than 20 [V] as long as it is a voltage lower than the first voltage.

[0037] Next, the operation of the electromagnetic coil drive circuit 3 according to the first embodiment will be described. Figure 3 This is a timing chart used in explaining the operation of the electromagnetic coil drive circuit according to Embodiment 1. From the top, (a) the gate voltage of the first switching element 41, (b) the drain-source voltage of the first switching element 41, (c) the gate voltage of the second switching element 42, (d) the drain-source voltage of the second switching element 42, and (e) the waveform of the excitation current flowing in the electromagnetic coil 5 are shown.

[0038] In the switch element driving circuit 34, the voltage detection circuit 343 always monitors whether the voltage of the first capacitor 31 reaches the first voltage. The first voltage is a voltage sufficient for the attraction action of the movable iron core 62 to be attracted to the fixed iron core 61. In other words, the first voltage is a voltage that can flow the current required for the movable iron core 62 to be attracted to the fixed iron core 61 through the electromagnetic coil 5.

[0039] When receiving a power-on command to the electromagnetic coil 5 from the upper control device and the voltage of the first capacitor 31 reaches the first voltage, the switch element drive circuit 34 operates the first drive circuit 341 at time t1, applies a gate voltage to the first switch element 41, and turns on the first switch element 41. When the first switch element 41 is turned on, the drain-source voltage of the first switch element 41 decreases to near zero [V]. In addition, when the first switch element 41 is turned on, the excitation current required for the attraction action flows in the electromagnetic coil 5. As a result, the movable iron core 62 is attracted to the fixed iron core 61, and the attraction action is completed.

[0040] In addition, when the first switching element 41 is turned on, the potential of the drain of the second switching element 42 changes greatly. Therefore, a so-called reverse voltage may be applied to the second switching element 42. In order to prevent this, the second diode 44 is provided. That is, the second diode 44 acts as a diode to prevent the application of reverse voltage.

[0041] At time t2, in order to reduce the excitation current flowing in the electromagnetic coil 5, the first switch element 41 is controlled from conduction to non-conduction, and the second switch element 42 is controlled from non-conduction to conduction. That is, at time t2, the first drive circuit 341 releases the gate voltage to the first switch element 41 and sets the first switch element 41 to non-conduction. The second drive circuit 342 applies a gate voltage to the second switch element 42 to turn on the second switch element 42. As a result, a second voltage (20 [V]) lower than the first voltage (200 [V]) is applied to both ends of the electromagnetic coil 5, and the excitation current flowing in the electromagnetic coil 5 gradually decreases. And, at time t3, if the second switch element 42 is completely turned on, the adsorption holding current required to maintain the state in which the movable iron core 62 is adsorbed to the fixed iron core 61 flows in the electromagnetic coil 5.

[0042] Furthermore, if the first switch element 41 is set to non-conductive and the second switch element 42 is set to conductive in order to flow the adsorption holding current in the electromagnetic coil 5, the excitation current decreases sharply, so if an attempt is made to maintain the excitation current, a back electromotive force is generated in the electromagnetic coil 5. Due to this back electromotive force, a current greater than or equal to the rated value may flow in the step-down circuit 32. In detail, a current greater than or equal to the rated value may flow in the step-down circuit 32 through a circuit that passes through the electromagnetic coil 5 → the second diode 44 → the second switch element 42 → the inductor 322 → the diode 321 → the electromagnetic coil 5. In order to prevent this, a current suppression circuit 45 is provided. Between time t2 and time t3, the waveform of the drain-source voltage of the second switch element 42 decreases gently. This waveform is obtained by the action of the current suppression circuit 45.

[0043] An example of a component of the current suppression circuit 45 is a resistor. For example, it can be formed by inserting a resistor between the source of the second switch element 42 and the third power line 38. When current flows through the second switch element 42, the voltage generated in the resistor can reduce the on-voltage between the gate and the source of the second switch element 42. As a result, it is possible to suppress the current that is greater than or equal to a certain value from flowing through the second switch element 42. As a result, it is possible to select the components of the step-down circuit 32 without being greatly affected by the back electromotive force generated in the electromagnetic coil 5, and to configure the step-down circuit 32 with the minimum required rated components.

[0044] In addition, Figure 3 Although the timing diagram is not shown, in order to release the adsorption of the movable iron core 62 to the fixed iron core 61, it is sufficient to set the second switch element 42 to non-conduction. In addition, if the second switch element 42 is set to non-conduction, a counter electromotive force is generated in the electromagnetic coil 5 during the process of reducing the current flowing in the electromagnetic coil 5. In order to reflux the counter electromotive force, the first diode 43 is provided in the electromagnetic coil 5. That is, the first diode 43 acts as a freewheeling diode.

[0045] Furthermore, when the first switching element 41 is turned on, the third diode 46 is provided so as not to discharge the charge of the first capacitor 31. That is, the third diode 46 operates as a discharge prevention diode that prevents the discharge of the charge of the first capacitor 31. Thus, power can be smoothly supplied to the step-down circuit 32.

[0046] As described above, the electromagnetic coil drive circuit involved in the first embodiment has the first and second switching elements, the first and second drive circuits, and the step-down circuit. The first switching element is arranged between the first power line on the high potential side and the second power line on the low potential side via the electromagnetic coil, and is arranged on the lower potential side than the electromagnetic coil. The first drive circuit drives the first switching element using the first voltage applied between the first power line and the second power line. The second switching element is arranged between the first power line and the third power line on the low potential side via the electromagnetic coil, and is arranged on the lower potential side than the electromagnetic coil. The second drive circuit drives the second switching element using the second voltage applied between the first power line and the third power line. The step-down circuit uses the first voltage to generate the second voltage after stepping down the first voltage. It is clear from these technologies that the method of the first embodiment does not use the PWM technology as in the prior art. Therefore, there is no need to control a microcomputer and a complex control circuit. This can suppress the complexity and large-scale of the circuit, and achieve a reduction in manufacturing cost and power consumption.

[0047] In addition, the electromagnetic coil driving circuit according to Embodiment 1 drives the first switch element through the first driving circuit to attract the movable iron core of the electromagnetic coil when the driving of the electromagnetic coil starts. In addition, after attracting the movable iron core, the electromagnetic coil driving circuit stops driving the first driving circuit and drives the second switch element through the second driving circuit to maintain the attraction of the movable iron core.

[0048] Through the above-mentioned action, a back electromotive force is generated in the electromagnetic coil. Therefore, the electromagnetic coil drive circuit involved in the first embodiment can have a current suppression circuit between the terminal on the low potential side of the second switching element, that is, the first terminal and the third power line. The current suppression circuit operates to suppress the current generated by the back electromotive force of the electromagnetic coil from entering the step-down circuit. Thus, the step-down circuit can be formed by the minimum required rated components.

[0049] In addition, a diode may be provided whose positive electrode is connected to the other end of the first capacitor and whose negative electrode is connected to the second power supply line. The diode acts as a discharge prevention diode that prevents the discharge of the charge of the first capacitor. Thus, since the discharge of the charge of the first capacitor is prevented, the voltage required for the operation of the step-down circuit is maintained in the first capacitor. Thus, the power supply to the step-down circuit can be smoothly performed.

[0050] When the driving force of the movable iron core 62 is small, it is possible to reduce the exciting current flowing through the electromagnetic coil 5. In such a case, at least one of the first diode 43, the second diode 44, and the third diode 46 can be omitted.

[0051] Implementation method 2.

[0052] Figure 4 This is a diagram showing a configuration example of an electromagnetic coil and an inductor according to the second embodiment. Figure 5 Yes means Figure 4 2 is a cross-sectional view of a cross section of the electromagnetic coil and the inductor shown in FIG. In the first embodiment, the electromagnetic coil 5 and the inductor 322 are formed by separate components. When the electromagnetic coil drive circuit 3 is used at a high power supply voltage such as AC440V, a voltage obtained by adding the input voltage and the surge voltage generated by the back electromotive force of the electromagnetic coil 5 is applied to the inductor 322. Therefore, it is necessary to use an inductor 322 with a rated performance higher than the added voltage. If the inductor is selected from commercially available inductors, the outer shape becomes larger and the manufacturing cost also increases.

[0053] Therefore, in Embodiment 2, if Figure 4 As shown in FIG. 1 , a winding 350 is wound around the outer periphery of the electromagnetic coil 5 to form an inductor 322, thereby forming an inductor component 50 in which the electromagnetic coil 5 and the inductor 322 are set as the same component. Figure 5As shown, the inductor component 50 includes a bobbin 51 , a yoke 52 , a fixed iron core 53 , a movable iron core 54 , and a shaft 55 .

[0054] A through hole is provided in the central portion of the bobbin 51. A winding 56 for constituting the electromagnetic coil 5 is wound on the bobbin 51. The yoke 52 is arranged on the outer side of the bobbin 51. A through hole is provided in the central portion of the fixed iron core 53. The fixed iron core 53 is provided in the through hole of the bobbin 51. The movable iron core 54 is provided in the through hole of the bobbin 51 and is movably provided in the through hole of the bobbin 51. The shaft 55 is retained by the movable iron core 54 and is movably passed through the through hole of the fixed iron core 53. The inductor 322 is provided between the electromagnetic coil 5 and the yoke 52, and is composed of a winding 350 wound on the outer side of the electromagnetic coil 5.

[0055] As described above, according to the electromagnetic coil drive circuit involved in the second embodiment, the inductance of the step-down circuit is formed by winding the winding around the outer periphery of the electromagnetic coil. As a result, the electromagnetic coil and the inductance can be formed as an inductance component, thereby reducing the number of components and manufacturing costs. In addition, the electromagnetic coil and the inductance can be formed as an inductance component, and the electromagnetic coil drive circuit can be miniaturized compared to the case where the equivalent components are selected from commercial products.

[0056] Implementation method 3.

[0057] In the third embodiment, a case will be described in which the circuit configuration of the first embodiment can be simplified by using the inductor 322 described in the second embodiment. Figure 6 This is a diagram showing a configuration example of an electromagnetic coil drive circuit according to the third embodiment.

[0058] The electromagnetic coil drive circuit 3A according to the third embodiment is Figure 1 In the structure of the electromagnetic coil drive circuit 3 involved in the embodiment 1 shown, the switch element drive circuit 34 is replaced by the switch element drive circuit 34A. In the switch element drive circuit 34A, the second drive circuit 342 is deleted. As a result, the second switch element 42 is also deleted. Therefore, the high potential side of the current suppression circuit 45 is connected to the cathode of the second diode 44, and the low potential side of the current suppression circuit 45 is connected to the third power supply line 38. Other structures are the same as Figure 1 The structures shown are the same or equivalent, and the same reference numerals are given to the same or equivalent structural parts, and repeated description is omitted.

[0059] In the electromagnetic coil drive circuit 3A according to the third embodiment, when the first switching element 41 is rendered non-conductive, the attraction and holding current flows through the current suppressing circuit 45. The current suppressing circuit 45 operates to suppress the current generated by the back electromotive force of the electromagnetic coil 5 from entering the inductor 322 of the step-down circuit 32.

[0060] In the structure of the third embodiment, when the inductor 322 of the structure involved in the second embodiment is used, a winding having a large short-time current tolerance is used as the winding 350 of the inductor 322. Figure 6 As shown in the structure, the second switch element 42 and the second drive circuit 342 can be reduced. In addition, the current suppression circuit 45 can meet the required performance even if it is composed of simple circuit elements such as resistors. In addition, the winding 350 constituting the inductor 322 uses a winding with a large withstand voltage, thereby enabling the electromagnetic coil drive circuit 3A to be used at a high power supply voltage such as AC440V.

[0061] As described above, according to the electromagnetic coil drive circuit involved in the third embodiment, the step-down circuit has an inductance formed by winding a winding around the outer periphery of the electromagnetic coil, and the current suppression circuit operates to suppress the current generated by the back electromotive force of the electromagnetic coil from entering the inductance of the step-down circuit. In this structure, if a winding with a large short-time current tolerance and a large withstand voltage tolerance is used for the winding wound around the outer periphery of the electromagnetic coil, the second switching element 42 and the second drive circuit 342 can be reduced. As a result, the electromagnetic coil drive circuit can be further miniaturized.

[0062] Furthermore, the configuration described in the above embodiment is an example of the content of the present invention, and can be combined with other known technologies. Part of the configuration can be omitted or changed without departing from the gist of the present invention.

[0063] Description of the label

[0064] 1 AC power supply, 2 full-wave rectifier circuit, 3, 3A electromagnetic coil drive circuit, 5 electromagnetic coil, 6 driven part, 31 first capacitor, 32 step-down circuit, 33 second capacitor, 34, 34A switching element drive circuit, 36 first power line, 37 second power line, 38 third power line, 41 first switching element, 42 second switching element, 43 first diode, 44 second diode, 45 current suppression circuit, 46 third diode, 50 inductor, 51 bobbin, 52 yoke, 53, 61 fixed iron core, 54, 62 movable iron core, 55 shaft, 56, 350 winding, 321 diode, 322 inductor, 323 power supply IC, 323a switch part, 324, 343 voltage detection circuit, 325 connection point, 341 first drive circuit, 342 Second drive circuit, T1, T2 DC input terminals.

Claims

1. An electromagnetic coil driving circuit, which drives an electromagnetic coil, The electromagnetic coil drive circuit is characterized by having: a first switching element disposed between a first power line on a high potential side and a second power line on a low potential side via the electromagnetic coil and disposed on a lower potential side than the electromagnetic coil; a first driving circuit for driving the first switching element using a first voltage applied between the first power line and the second power line; a second switching element disposed between the first power line and a third power line on the low potential side via the electromagnetic coil and disposed on the lower potential side than the electromagnetic coil; a second driving circuit for driving the second switching element using a second voltage applied between the first power line and the third power line; a step-down circuit that uses the first voltage to generate the second voltage by stepping down the first voltage; and a current suppressing circuit connected between the first terminal, which is a terminal on the low potential side of the second switching element, and the third power supply line, and suppressing a current greater than or equal to a certain value from flowing from the electromagnetic coil to the step-down circuit; The current suppression circuit operates so as to suppress the current generated by the back electromotive force of the electromagnetic coil from entering the voltage-dropping circuit.

2. An electromagnetic coil driving circuit, which drives the electromagnetic coil, The electromagnetic coil drive circuit is characterized by having: a first switching element disposed between a first power line on a high potential side and a second power line on a low potential side via the electromagnetic coil and disposed on a lower potential side than the electromagnetic coil; a first driving circuit for driving the first switching element using a first voltage applied between the first power line and the second power line; a second switching element disposed between the first power line and a third power line on the low potential side via the electromagnetic coil and disposed on the lower potential side than the electromagnetic coil; a second driving circuit for driving the second switching element using a second voltage applied between the first power line and the third power line; a step-down circuit that uses the first voltage to generate the second voltage by stepping down the first voltage; a first capacitor, one end of which is connected to the first power line; and The diode has an anode connected to the other end of the first capacitor and a cathode connected to the second power line.

3. An electromagnetic coil driving circuit, which drives the electromagnetic coil, The electromagnetic coil drive circuit is characterized by having: a first switching element disposed between a first power line on a high potential side and a second power line on a low potential side via the electromagnetic coil and disposed on a lower potential side than the electromagnetic coil; a first driving circuit for driving the first switching element using a first voltage applied between the first power line and the second power line; a second switching element disposed between the first power line and a third power line on the low potential side via the electromagnetic coil and disposed on the lower potential side than the electromagnetic coil; a second driving circuit for driving the second switching element using a second voltage applied between the first power line and the third power line; and a step-down circuit that uses the first voltage to generate the second voltage by stepping down the first voltage, The step-down circuit comprises an inductor, The inductor is formed by winding a winding around the outer circumference of the electromagnetic coil.

4. The electromagnetic coil driving circuit according to any one of claims 1 to 3, characterized in that: have: When the driving of the electromagnetic coil starts, the first switch element is driven by the first driving circuit to adsorb the movable iron core of the electromagnetic coil. After the movable iron core is adsorbed, the driving by the first driving circuit is stopped, and the second switch element is driven by the second driving circuit to maintain the adsorption of the movable iron core.

5. An electromagnetic coil driving circuit, which drives the electromagnetic coil. The electromagnetic coil drive circuit is characterized by having: a first switching element disposed between a first power line on a high potential side and a second power line on a low potential side via the electromagnetic coil and disposed on a lower potential side than the electromagnetic coil; a first driving circuit for driving the first switching element using a first voltage applied between the first power line and the second power line; a step-down circuit having an inductor formed by winding a winding around the outer circumference of the electromagnetic coil, and generating a second voltage by stepping down the first voltage using the first voltage; and A current suppression circuit is disposed between the first power line and a third power line on a low potential side via the electromagnetic coil, and operates to suppress a current generated by a back electromotive force of the electromagnetic coil from entering the inductance of the step-down circuit.

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