Inductive Load Driver

Abstract

To provide an inductive load drive device that at relatively low costs, performs circuit protection against disconnection and the like during driving an inductive load.SOLUTION: A inductive load drive device electrically connected between one or more inductive loads and a power supply to drive the one or more inductive loads includes: one or more drive circuit units that have power supply terminals, ground terminals, and output terminals electrically connected to the inductive loads and include semiconductor switching elements for driving the one or more inductive loads; a first circuit element having one end electrically connected to a ground terminal and the other end electrically connected to the ground; and a second circuit element having one end electrically connected between a power supply terminal and the power supply and the other end electrically connected to the ground without intervention of the first circuit element. Electrical resistance of the second circuit element with respect to a current flow from the ground to the power supply terminal is smaller than that of the first circuit element with respect to a current flow from the ground to the ground terminal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an inductive load driver. [Background technology]

[0002] 2. Description of the Related Art An inductive load driver is known that is electrically connected between an inductive load and a power source to drive the inductive load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-036239 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of inductive load driver, a protection circuit element is generally provided to protect against surge voltages that occur when the switching element is turned off during normal operation. In addition to these surge voltages during normal operation, a surge voltage can occur due to back electromotive force when the power supply path from the power source is interrupted due to a wire break or other reason while the inductive load is being driven. Therefore, it is useful to provide circuit protection to prevent such surge voltages from occurring. However, prior art has not been able to provide such circuit protection at a relatively low cost.

[0005] Therefore, in one aspect, an object of the present disclosure is to provide an inductive load driving device that provides circuit protection against disconnection or the like while driving an inductive load at a relatively low cost. [Means for solving the problem]

[0006] In one aspect, there is provided an inductive load driver electrically connected between one or more inductive loads and a power source to drive the one or more inductive loads, the inductive load driver comprising: one or more drive circuit units each having a power supply terminal electrically connected to a high potential side of the power supply, a ground terminal electrically connected to ground, and an output terminal electrically connected to the inductive load, the drive circuit unit including a semiconductor switching element for driving one or more of the inductive loads; a first circuit element having one end electrically connected to the ground terminal and the other end electrically connected to ground; a second circuit element having one end electrically connected between the power supply terminal and the power supply and the other end electrically connected to ground without passing through the first circuit element; An inductive load driver is provided, wherein the electrical resistance of the second circuit element to the flow of current from ground to the power supply terminal is smaller than the electrical resistance of the first circuit element to the flow of current from ground to the ground terminal. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, in an inductive load driving device, it is possible to achieve circuit protection against disconnection or the like while driving an inductive load at a relatively low cost. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram illustrating an example of an inductive load driving device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram schematically illustrating an example of an internal circuit configuration of one drive circuit unit. [Figure 3] 3 is an explanatory diagram of a current flow when the power supply is normal in the inductive load driving device of the present embodiment. FIG. [Figure 4] 4 is an explanatory diagram of a current flow in the inductive load driving device of the present embodiment when a power supply fails. FIG. [Figure 5] FIG. 10 is an explanatory diagram of a protection function according to a comparative example. [Figure 6] FIG. 10 is a schematic configuration diagram showing an example of an inductive load driving device according to a first modified example. [Figure 7] FIG. 10 is a schematic configuration diagram showing an example of an inductive load driving device according to a second modified example. [Figure 8] FIG. 10 is a schematic configuration diagram showing an example of an inductive load driving device according to a third modified example. [Figure 9] FIG. 10 is a schematic configuration diagram showing an example of an inductive load driving device according to a fourth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not intended to limit the scope of the invention. In addition, shapes and the like in the drawings may be partially exaggerated for the sake of explanation.

[0010] FIG. 1 is a schematic diagram showing an example of an inductive load driving device 1 according to this embodiment.

[0011] The inductive load driver 1 is electrically connected between one or more inductive loads 2 and a power source 3, and controls the one or more inductive loads 2. The inductive load driver 1 may be in the form of, for example, an ECU (Electronic Control Unit) or the like.

[0012] The inductive load driver 1 can be used in a variety of applications, but in this embodiment, it is used in a vehicle. That is, the inductive load driver 1 is mounted on a vehicle. The type of vehicle is arbitrary, and it may be a vehicle equipped with an engine, or may be a hybrid vehicle, an electric vehicle, or the like.

[0013] The one or more inductive loads 2 are optional and are inductive loads mounted on a vehicle in this embodiment. For example, the inductive load 2 may be a solenoid provided in an automatic transmission. Alternatively, the inductive load 2 may be a solenoid provided in an engine. The one or more inductive loads 2 may be provided in one unit (module).

[0014] 1, the one or more inductive loads 2 are three, but any number of inductive loads 2 may be electrically connected to one inductive load driving device 1. In the following, as an example, it is assumed that the number of inductive loads 2 is three.

[0015] The power supply 3 is, for example, an on-board battery. In the case of a hybrid vehicle or an electric vehicle, the power supply 3 may be a low-voltage battery. Hereinafter, the positive electrode side of the power supply 3 may be referred to as the high-potential side.

[0016] The inductive load driver 1 includes one or more driver circuits 4 .

[0017] A drive circuit unit 4 may be provided for each inductive load 2. In this embodiment, three drive circuit units 4 are provided corresponding to the three inductive loads 2. As such, in this embodiment, one inductive load 2 and one drive circuit unit 4 correspond one-to-one. Hereinafter, with respect to a certain drive circuit unit 4, the "corresponding" inductive load 2 refers to the inductive load 2 electrically connected to that drive circuit unit 4. The same applies to the "corresponding" drive circuit unit 4, and also to other elements that correspond one-to-one. For example, in the example shown in FIG. 1, one end of each of one or more inductive loads 2 is electrically connected to the corresponding drive circuit unit 4, and the other end is electrically connected to ground.

[0018] The drive circuit units 4 can operate independently of each other. Each drive circuit unit 4 controls the current flowing through the corresponding inductive load 2.

[0019] Fig. 2 is a diagram schematically illustrating an example of the internal circuit configuration of one drive circuit unit 4. Note that each of the three drive circuit units 4 shown in Fig. 1 has the same internal circuit configuration, but may have a partially different internal circuit configuration.

[0020] 2, the drive circuit unit 4 includes a power supply terminal 41 electrically connected to the high-potential side of the power supply 3, a ground terminal 42 electrically connected to the ground, and an output terminal 43 electrically connected to the inductive load 2. The drive circuit unit 4 may be in the form of an intelligent power device (IPD), an intelligent power switch, a smart switch, or the like. In this case, the drive circuit unit 4 can be realized by using an existing device.

[0021] In the example shown in FIG. 2, the drive circuit section 4 includes a semiconductor switching element 44, a logic circuit section 45, and a Zener diode D20.

[0022] The semiconductor switching element 44 is, for example, an N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) as shown in FIG. 2, but may be another type of switching element such as an IGBT (Insulated Gate Bipolar Transistor).

[0023] The semiconductor switching element 44 is electrically connected to the power supply terminal 41 and also to the corresponding inductive load 2. In the example shown in Fig. 2, the MOSFET that is the semiconductor switching element 44 has a drain terminal electrically connected to the power supply terminal 41 and a source terminal electrically connected to the corresponding inductive load 2. In this case, when the semiconductor switching element 44 is turned on, the corresponding inductive load 2 is energized.

[0024] 2, the logic circuit unit 45 is electrically connected between the power supply terminal 41 and the ground terminal 42, and is also electrically connected to the gate electrode of the semiconductor switching element 44. The logic circuit unit 45 may apply the on / off drive signal to the gate electrode of the semiconductor switching element 44 in response to a command from a higher-level processing device (not shown) (for example, a microcomputer that may be included in another control-system load 9 described later).

[0025] The Zener diode D20 has a function of protecting the drive circuit unit 4 from a surge voltage caused by a back electromotive force that may occur at the output terminal 43 when the semiconductor switching element 44 turns off during normal operation (when no power supply failure, described later, occurs). In the example shown in FIG. 2, the Zener diode D20 is a protection circuit element that functions when power is normally supplied from the power supply 3 to the power supply terminal 41 (normal state). In this case, the Zener diode D20 is used to absorb surge voltages, and absorbs the surge voltage that occurs when the semiconductor switching element 44 turns off. As a result, when the semiconductor switching element 44 turns off during normal operation (when no power supply failure, described later, occurs), a high surge voltage that exceeds the Zener voltage of the Zener diode D20 does not occur between the power supply terminal 41 and the output terminal 43, thereby realizing circuit protection.

[0026] In this embodiment, the inductive load driver 1 further includes a resistive element R1, as shown in Fig. 1. The resistive element R1 is provided for each drive circuit unit 4. That is, each resistive element R1 is electrically connected between a corresponding one of the drive circuit units 4 and ground. More specifically, one end of each resistive element R1 is electrically connected to the ground terminal 42 of the corresponding one of the drive circuit units 4, and the other end is electrically connected to ground.

[0027] 1, three resistor elements R1 are provided. In this case, redundancy can be improved compared to when only one resistor element R1 is provided for three drive circuit units 4 (see FIG. 7). For example, even if one of the three resistor elements R1 fails, the drive circuit units 4 associated with the other two resistor elements R1 can be used to continue driving the corresponding two inductive loads 2.

[0028] 1, the inductive load driver 1 further includes a diode D1. The diode D1 is electrically connected in parallel with the drive circuit unit 4 and the resistor element R1 between the high potential side of the power supply 3 and ground. More specifically, one end (cathode) of the diode D1 is electrically connected between the power supply 3 and the power supply terminal 41 of the drive circuit unit 4, and the other end (anode) is electrically connected to ground.

[0029] The diode D1 cooperates with the resistor element R1 to protect the drive circuit unit 4 and the like in the event of a power failure, which will be described later. This function will be described later with reference to FIG.

[0030] In this embodiment, unlike the above-described resistive element R1, only one diode D1 is provided for three drive circuit units 4. This is because, unlike the above-described resistive element R1, the diode D1 is not an element electrically connected in series to the drive circuit unit 4 and does not affect operation when the power supply is normal, so there is little need to ensure the above-described redundancy.

[0031] Returning to FIG. 1 , the inductive load driver 1 may preferably further include a control load 9. The control load 9 may have a function of controlling each of the inductive loads 2 via each of the drive circuit units 4, for example. For example, the control load 9 may include a microcomputer and a power supply circuit.

[0032] In this case, it is easy to share the power supply path 30 from the power source 3 between the control system load 9 and the inductive load 2, and to modularize the inductive load driving device 1 including the control system load 9 and the driving circuit unit 4.

[0033] Next, with reference to FIGS. 3 and 4, the current flow in the inductive load driving device 1 of this embodiment during normal operation and the current flow when the power supply fails while the inductive load 2 is being driven will be described.

[0034] FIG. 3 is an explanatory diagram of the current flow in the inductive load driving device 1 of this embodiment when the power supply is normal, and the current flow is indicated typically by an arrow R30.

[0035] When the power supply is normal, when the semiconductor switching element 44 of the drive circuit unit 4 is turned on, a current is taken out of the power supply 3 and flows through the inductive load 2, as shown schematically by an arrow R30.

[0036] FIG. 4 is an explanatory diagram of the current flow when the power supply fails in the inductive load driving device 1 of this embodiment (when the power supply fails while the inductive load 2 is being driven), and the current flow is schematically indicated by arrows R41 to R43.

[0037] A power failure refers to a state in which current does not flow from the power supply 3 to the inductive load driver 1 due to, for example, a break in the power supply path 30 between the power supply 3 and the inductive load driver 1. In Fig. 4, such a break in the power supply path 30 is schematically shown by the switch SW1 being in an open state.

[0038] When the power supply path 30 from the power supply 3 is interrupted while the inductive load driver 1 is driving the inductive load 2, a voltage (back electromotive force) is generated that tries to keep current flowing through the inductive load 2. This back electromotive force causes current to flow from the ground toward the inductive load 2 (see the dotted arrows R41 to R43 in FIG. 4).

[0039] 4, in the event of a power failure while the inductive load 2 is being driven, there are three possible paths for current to flow from ground to the inductive load 2: a path through the control system load 9 in the reverse direction (see R41), a path through the diode D1 (see R42), and a path through the resistor R1 and the drive circuit unit 4 in the reverse direction (see R43).The path through the diode D1 includes a path through the inductive load 2 via the power supply terminal 41 (a path through which current flows through the drive circuit unit 4 in the same direction as when the power supply is normal).

[0040] Therefore, in a configuration in which the drive circuit unit 4 is included in a current path that can flow from ground to the inductive load 2 in the event of a power failure while the inductive load 2 is being driven, if a power failure occurs while the inductive load 2 is being driven, a relatively high voltage (surge voltage due to back electromotive force) will be generated across both ends of the drive circuit unit 4 (i.e., power supply terminals 41), which may damage the drive circuit unit 4. Similarly, in a configuration in which the control system load 9 is included in a current path that can flow from ground to the inductive load 2 in the event of a power failure while the inductive load 2 is being driven, a relatively high voltage (surge voltage due to back electromotive force) will be generated across both ends of the control system load 9, which may damage the control system load 9.

[0041] In this embodiment, a current path through diode D1, which has significantly lower electrical resistance than other paths, is provided as a current path that can flow from ground to inductive load 2 in the event of a power failure while inductive load 2 is being driven. Therefore, even if a power failure occurs while inductive load 2 is being driven, most of the current flowing from ground to inductive load 2 will flow through the path through diode D1. In other words, it is possible to prevent a surge voltage due to a back electromotive force that can occur across the drive circuit unit 4, etc., in the event of a power failure while inductive load 2 is being driven. In this way, even if a current flows through the current path through diode D1 in the event of a power failure while inductive load 2 is being driven, the resulting current flowing through drive circuit unit 4 will flow in the same direction as the current when the power supply is normal, and will not damage drive circuit unit 4.

[0042] In this way, according to this embodiment, it is possible to prevent a surge voltage due to a back electromotive force that may occur when the power supply fails while the inductive load 2 is being driven, and it is possible to appropriately protect the drive circuit unit 4.

[0043] Similarly, when the inductive load driving device 1 includes a control load 9, the control load 9 can be appropriately protected by the same principle according to this embodiment.

[0044] Fig. 5 is an explanatory diagram of a protection function according to a comparative example. In Fig. 5, components that may be similar to those in the above-described embodiment are given the same reference numerals, and descriptions thereof may be omitted.

[0045] In this comparative example, as shown in FIG. 5, in contrast to the present embodiment shown in FIG. 1, three diodes D10 are provided instead of the resistor element R1.

[0046] The three diodes D10 function to block current flowing from the ground to the drive circuit section 4 when the power supply fails while the inductive load 2 is being driven.

[0047] Even in this comparative example, the three diodes D10 can prevent a surge voltage caused by a back electromotive force that may occur across both ends of the drive circuit unit 4 in the event of a power failure while the inductive load 2 is being driven, thereby appropriately protecting the drive circuit unit 4.

[0048] However, this comparative example is disadvantageous from the viewpoint of cost because it uses a relatively large number of relatively expensive diodes (in this case, a total of three diodes D10).

[0049] In contrast, according to this embodiment, as described above, the three resistor elements R1, which replace the three diodes D10 of the comparative example, can achieve the same function as the three diodes D10 of the comparative example. Note that resistor elements are significantly cheaper than diodes.

[0050] In this way, according to this embodiment, in the inductive load driving device 1, the driving circuit section 4 can be appropriately protected against disconnection or the like while the inductive load 2 is being driven, at a relatively low cost.

[0051] 1, in this comparative example, three diodes D11 are provided instead of the diode D1. In this case, a current path that passes through the three diodes D11 and has significantly lower electrical resistance than other paths is formed as a current path that can flow from ground to the inductive load 2 in the event of a power failure while the inductive load 2 is being driven.

[0052] Therefore, even in this comparative example, the three diodes D11 can prevent a surge voltage caused by a back electromotive force that may occur across the control system load 9 in the event of a power failure while the inductive load 2 is being driven, thereby appropriately protecting the control system load 9.

[0053] However, this comparative example is disadvantageous from the viewpoint of cost because it uses a relatively large number of relatively expensive diodes (in this case, a total of three diodes D11).

[0054] In contrast to this, according to this embodiment, as described above, the same function as the three diodes D11 of the comparative example can be realized by using one diode D1 instead of the three diodes D11 of the comparative example.

[0055] In this way, according to this embodiment, in the inductive load driving device 1, the control load 9 can be appropriately protected against disconnection or the like while the inductive load 2 is being driven, at a relatively low cost.

[0056] Next, various modified examples that may be realized instead of the above-described embodiment will be described with reference to Figure 6 onwards. Note that in Figure 6 onwards, components that may be similar to those in the above-described embodiment may be given the same reference numerals and descriptions thereof may be omitted.

[0057] FIG. 6 is a schematic diagram showing an example of an inductive load driving device 1A according to a first modified example.

[0058] The inductive load driving device 1A according to this modification differs from the inductive load driving device 1 according to the above-described embodiment in that the three resistance elements R1 are replaced with a diode D2.

[0059] In this case, the diode D2 is electrically connected between the ground and the drive circuit unit 4 with its cathode connected to the ground. Similar to the three resistive elements R1 in the above-described embodiment, the diode D2 has the function of blocking current that would flow in the reverse direction through the drive circuit unit 4 from the ground toward the inductive load 2 in the event of a power failure while the inductive load 2 is being driven.

[0060] According to the first modified example, although it is disadvantageous compared to the above-described embodiment in that it uses a diode D2 instead of three resistive elements R1, it can achieve the effect of protecting the drive circuit unit 4 and the control system load 9 from breakage during driving of the inductive load 2, at a lower cost than the comparative example shown in Figure 5, as with the above-described embodiment.

[0061] FIG. 7 is a schematic diagram showing an example of an inductive load driving device 1B according to a second modified example.

[0062] The inductive load driving device 1B according to this modification differs from the inductive load driving device 1 according to the above-described embodiment in that the three resistance elements R1 are replaced with a single resistance element R2.

[0063] In this case, the resistive element R2, like the three resistive elements R1 in the above-mentioned embodiment, has the function of working together with the diode D1 to eliminate current that attempts to flow in the reverse direction through the drive circuit section 4 from ground toward the inductive load 2 in the event of a power failure while the inductive load 2 is being driven.

[0064] As with the above-described embodiment, the second modified example also provides the effect of protecting the drive circuit unit 4 and the control load 9 from disconnection or the like during driving of the inductive load 2 at a lower cost than the comparative example shown in Fig. 5. Furthermore, compared to the above-described embodiment, the reduced number of resistive elements provides an advantage in terms of cost.

[0065] FIG. 8 is a schematic configuration diagram showing an example of an inductive load driving device 1C according to a third modified example.

[0066] The inductive load driving device 1C according to this modification differs from the inductive load driving device 1 according to the above-described embodiment in that the three resistor elements R1 are replaced with three diodes D3.

[0067] In this case, the three diodes D3 are electrically connected in parallel to one another between the power supply 3 and ground, and in series to their corresponding drive circuit units 4. In this case, the three diodes D3 are electrically connected between the ground and the drive circuit unit 4 with their cathodes connected to the ground. Similar to the three resistive elements R1 in the above-described embodiment, the three diodes D3 have the function of blocking current that would flow in the reverse direction through the drive circuit unit 4 from the ground toward the inductive load 2 in the event of a power supply failure while the inductive load 2 is being driven.

[0068] According to the third modified example, although it is disadvantageous in terms of cost compared to the above-described embodiment in that three diodes D3 are used instead of three resistor elements R1, it is possible to obtain the effect of protecting the drive circuit unit 4 and the control system load 9 from breakage during driving of the inductive load 2, at a lower cost than the comparative example shown in Figure 5, as with the above-described embodiment.

[0069] Furthermore, compared to the first modification, the third modification employs three diodes D3 instead of the diode D2, which is disadvantageous in terms of cost, but it can enhance redundancy. For example, even if one of the three diodes D3 fails, the drive circuits 4 associated with the other two diodes D3 can continue to drive the corresponding two inductive loads 2.

[0070] FIG. 9 is a schematic configuration diagram showing an example of an inductive load driving device 1D according to a fourth modified example.

[0071] An inductive load driving device 1D according to this modification differs from the inductive load driving device 1 according to the above-described embodiment in that the diode D1 is replaced with a diode D4.

[0072] Like diode D1, diode D4 is electrically connected in parallel to drive circuit unit 4 between the high-potential side of power supply 3 and ground. However, in this modification, diode D4 is provided at a position away from drive circuit unit 4. Like diode D1, diode D4 works in cooperation with three resistance elements R1 to eliminate current that attempts to flow in the reverse direction through drive circuit unit 4 from ground toward inductive load 2 when power supply fails while inductive load 2 is being driven.

[0073] The fourth modification can also achieve the same effects as those of the above-described embodiment. It is also possible to combine this modification with any of the first to fourth modifications. For example, when this modification is combined with the first modification (FIG. 6), the three resistor elements R1 are replaced with diodes D2.

[0074] Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments. Furthermore, among the effects of each embodiment, the effects related to the dependent claims are additional effects that are distinct from the generic concept (independent claim).

[0075] For example, in the above-described embodiment, one drive circuit unit 4 is provided for one inductive load 2, but one drive circuit unit 4 may be provided for two or more inductive loads 2. [Explanation of symbols]

[0076] 1, 1A, 1B, 1C, 1D... inductive load driver, 2... inductive load, 3... power supply, 4... drive circuit section, 41... power supply terminal, 42... ground terminal, 43... output terminal, 9... control system load (electrical load of control system), R1, R2... resistor element (first circuit element), D1, D4... diode (D2 element), D2, D3... diode (first circuit element), D20... Zener diode (protection circuit element)

Claims

1. An inductive load driver electrically connected between one or more inductive loads and a power source, and configured to drive the one or more inductive loads, one or more drive circuit units each having a power supply terminal electrically connected to a high potential side of the power supply, a ground terminal electrically connected to ground, and an output terminal electrically connected to the inductive load, the drive circuit unit including a semiconductor switching element for driving the one or more inductive loads; a first circuit element having one end electrically connected to the ground terminal and the other end electrically connected to ground; a second circuit element having one end electrically connected between the power supply terminal and the power supply and the other end electrically connected to ground without passing through the first circuit element; an electrical resistance of the second circuit element with respect to a second current flowing from ground to the power supply terminal is smaller than an electrical resistance of the first circuit element with respect to a first current flowing from ground to the ground terminal; the drive circuit unit includes a logic circuit unit that generates a drive signal for controlling the on / off of the semiconductor switching element; the logic circuit unit is connected between the power supply terminal and the ground terminal, The inductive load driver, wherein the first current flows through the logic circuit unit.

2. the first circuit element is a resistor element or a diode whose cathode side is electrically connected to ground, 2. The inductive load driving device according to claim 1, wherein the second circuit element is a diode having an anode electrically connected to ground.

3. 3. The inductive load driving device according to claim 2, wherein only one second circuit element is provided for each of the plurality of inductive loads.

4. Each of the one or more drive circuit units the logic circuit unit that drives the semiconductor switching element; 4. The inductive load driving device according to claim 1, further comprising a protection circuit element for protecting said driving circuit unit by absorbing a surge voltage when said semiconductor switching element is turned off.

5. 2. The inductive load driving device according to claim 1, further comprising an electrical load of a control system electrically connected in parallel with one or more of the driving circuit units and the first circuit element between the high potential side of the power supply and ground.

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