Current control device

Abstract

The present invention provides a current control device which can prevent an unexpected valve action caused by a reverse current flowing and continue to perform feedback control on a solenoid under normal feedback control.

Description

Technical Field

[0001] The present invention relates to a current control device, and more particularly to a current control device for controlling a current flowing through a solenoid as an inductive load. Background Art

[0002] The current control device of the solenoid used in the automatic transmission of vehicles, etc. measures the current value flowing through the solenoid, and controls the current by feeding back the current value to a pulse width modulation signal (hereinafter referred to as PWM signal) in a manner consistent with the desired current value. The PWM signal adjusts the on and off timing of the switching element that controls the power supply to the solenoid.

[0003] Fig. 9 A conventional example of a current control device is shown. Fig. 9 The conventional current control device 500 shown has one end of a solenoid 110 connected to a connection point of a high-side switch element 40 and a low-side switch element 50 connected in series with a battery power source (VB) 150, and the other end of the solenoid 110 is connected to a ground power source (GND) 120. The high-side switch element 40 and the low-side switch element 50 are exclusively turned on and off according to a PWM signal (PMW_IN1) 11 from a microcontroller 200 (hereinafter sometimes referred to as a microcomputer), and current is supplied to the solenoid 110. When the PWM signal 11 is at a high level, the high-side switch element 40 is turned on and the low-side switch element 50 is turned off, and current is supplied from the battery power source 150 to the solenoid 110 via the high-side switch element 40. On the other hand, when the PWM signal 11 is at a low level, the low-side switch element 50 is turned on and the high-side switch element 40 is turned off, and the current supply from the battery power source 150 is stopped. Here, when the current supplied from the battery power source 150 is cut off, since a back electromotive force is generated in the solenoid 110, a current is supplied from the ground power source (GND) 160 via the low-side switching element 50, so that the energy stored in the solenoid 110 is released. The current supplied to the solenoid 110 is supplied via the high-side switching element 40 or the low-side switching element 50 according to the polarity of the PWM signal 11, but the supplied current is controlled by adjusting the high-level time of the PWM signal 11 ÷ the PWM signal period (hereinafter referred to as the duty cycle).

[0004] Such a current control device 500 is generally provided with: an HS (high side) current measurement circuit 60, which detects and measures the current value flowing through the solenoid 110 via the high side switch element 40; an LS (low side) current measurement circuit 70, which detects and measures the current value flowing through the solenoid 110 via the low side switch element 50; a current calculation circuit 80, which calculates the average current value for a certain period required for feedback control based on the current detection results of the HS current measurement circuit 60 and the LS current measurement circuit 70 and transmits it to the microcomputer 200; and a switch control circuit 30, which receives a PWM signal ( PMW_IN1) 11, generates a PWM signal 31 for controlling the high-side switch element 40 (hereinafter, sometimes simply referred to as the PWM signal 31) and a PWM signal 32 for controlling the low-side switch element 50 (hereinafter, sometimes simply referred to as the PWM signal 32), and performs switching control of the high-side switch element 40 and the low-side switch element 50 for turning on and off (also called gate control). The high-side switch element 40, the low-side switch element 50 and the various circuits constitute a load drive circuit (synchronous rectification circuit) 10 that supplies current to the solenoid 110 as an inductive load.

[0005] Furthermore, when a plurality of solenoids are controlled by using such a current control device 500 , it is also known to provide a load drive circuit corresponding to each solenoid in the current control device 500 (for example, refer to the following Patent Document 1).

[0006] Prior art literature

[0007] Patent literature.

[0008] Patent Document 1: International Publication No. 2017 / 057682 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] When one end of the solenoid connected to the current control device is grounded to the ground power supply, current is supplied from the current control device to the solenoid. When the duty ratio of the PWM signal from the microcontroller is "0", the current value is "0", which is the minimum value. By increasing the duty ratio, the amount of current supplied to the solenoid increases. Therefore, in this current control device, the current from the solenoid to the direction opposite to the normal direction of the current control device cannot be controlled. However, in the case of abnormalities such as disconnection of the ground wire of the electronic control device or the solenoid, an unexpected reverse current may be generated.

[0011] Fig.10 Another conventional example of a current control device is shown. Fig.10The conventional current control device 600 shown controls a plurality of solenoids each having one end connected to a common ground point (ground power supply). When one solenoid 110a is controlled by a PWM signal (PMW_IN1) 11a with a low duty ratio (sent from the microcomputer 200 to the load drive circuit 10a), and another solenoid 110b is controlled by a PWM signal (PMW_IN2) 11b with a relatively high duty ratio (sent from the microcomputer 200 to the load drive circuit 10b), for example, when the current control device 600 and the ground power supply 160 are disconnected, since the node 170 connected to the ground power supply 160 becomes high impedance and is easily fluctuated, the relatively large current Is from the current control device 600 to the solenoid 110b acts in a direction to reduce the potential of the node 170. Then, the current flowing through the solenoid 110b flows from the solenoid 110a through the low-side switching element 50 which is substantially continuously turned on by the low-duty PWM signal 11a, and into the node 170 of the current control device 600, thereby generating the reverse current Irev.

[0012] The solenoid may also open and close the valve due to reverse current. For example, in an intermittent solenoid that controls a lockup clutch, the reverse current may cause an unexpected lockup engagement, resulting in a shift shock.

[0013] In order to solve such a problem, in the prior art described in the above-mentioned Patent Document 1, when the current value detected flowing through the solenoid is lower than the indicated value of the current, or when a reverse current is detected, it is determined that there is a wire break abnormality at the common grounding point of the solenoids, and control is performed in the direction of stopping all the solenoids. However, this is handled as a wire break abnormality at the common grounding point of one end of each solenoid, and all the solenoids are disconnected, so there is a high possibility of causing a speed change shock.

[0014] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a current control device that can prevent an unexpected valve action caused by a reverse current flowing and can continue to perform feedback control on a solenoid under normal feedback control.

[0015] Technical means of solving problems

[0016] In order to solve the above-mentioned problems, the current control device of the present invention is characterized in that it comprises: a high-side switching element, which makes the solenoid conductive to the battery power supply, and one end of the solenoid is grounded to the ground power supply; and a low-side switching element, which is conductive to the ground power supply, and the current control device has: a switching control circuit, which controls the supply current to the solenoid by turning on one of the high-side switching element and the low-side switching element and disconnecting the other; and a time measurement circuit, which measures the conduction duration of the low-side switching element.

[0017] Effects of the Invention

[0018] According to the present invention, a high-side switch element is provided, which makes a solenoid conduct with a battery power source, and one end of the solenoid is grounded to a ground power source; and a low-side switch element is provided, which is conducted with a ground power source, and the current control device has: a switch control circuit, which controls the supply current to the solenoid by turning on one of the high-side switch element and the low-side switch element and turning off the other; and a time measurement circuit, which measures the conduction duration of the low-side switch element. And, when the conduction duration of the low-side switch element measured by the time measurement circuit reaches a predetermined time, the switch control circuit temporarily turns off the low-side switch element while turning off the high-side switch element.

[0019] That is, in order to prevent reverse current, the current supplied to the solenoid is controlled by a PWM signal with a low duty ratio. In particular, when the control is performed by a PWM signal with a duty ratio equivalent to the indicated current value of the current "0", after a certain period of time, the low-side switch element is temporarily turned off to cut off the reverse current path in advance. If a PWM signal indicating that the indicated current value is not "0" or above a certain value is received, the low-side switch element is released from the off-fixing, and the normal synchronous rectification operation is restored in which one of the high-side switch element and the low-side switch element is turned on.

[0020] Thus, the reverse current path of the solenoid can be cut off in a simpler way, and undesired valve action due to the reverse current flow can be prevented, and feedback control can be continued for the solenoid capable of normal feedback control. As a result, in the intermittent solenoid controlling the lockup clutch, for example, undesired lockup engagement can be prevented when the ground wire is disconnected, and the generation of speed change shock can be suppressed.

[0021] The other objects, structures, and effects than those described above will become clear from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a diagram showing the configuration of the first embodiment of the present invention.

[0023] Figure 2 It is a configuration diagram showing a modified example of the first embodiment of the present invention.

[0024] Figure 3 This is a diagram showing an example 1 of the operation waveforms of the first embodiment of the present invention.

[0025] Figure 4 It means to make Figure 3 FIG. 4 is a diagram showing an example of an operation waveform when the threshold time depends on the detection current value.

[0026] Figure 5 It is simply to find Figure 4 An illustration of the threshold time of .

[0027] Figure 6 This is a diagram showing an example 2 of the operation waveforms of the first embodiment of the present invention.

[0028] Figure 7 It is a diagram showing the configuration of the second embodiment of the present invention.

[0029] Figure 8 It is a diagram showing an example of an operation waveform of the second embodiment of the present invention.

[0030] Fig. 9 This is a diagram showing the structure of a conventional current control device.

[0031] Fig.10 This is a configuration diagram showing an example of a problem in a conventional current control device. DETAILED DESCRIPTION

[0032] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings. In addition, since the accompanying drawings are simplified, the technical scope of the present invention cannot be narrowly interpreted based on the description of the accompanying drawings. In addition, in the description of this specification, the same elements are given the same symbols, and repeated descriptions are omitted.

[0033] [First embodiment]

[0034] Figure 1 It is a configuration diagram of a current control device for a vehicle automatic transmission according to a first embodiment of the present invention.

[0035] The current control device 100 of the illustrated embodiment is composed of a microcomputer 200 and load drive circuits 10a and 10b that supply current to a plurality of solenoids 110a and 110b. Here, in order to simplify the drawings, the plurality of solenoids and load drive circuits are omitted as two (two groups), but the number is not limited. In addition, the load drive circuits 10a and 10b are both connected to one end of the solenoids 110a and 110b, and the solenoids 110a and 110b supply current to the connection point of the high-side switch element 40 and the low-side switch element 50 connected in series with the battery power supply (VB) 150, and the other ends of the solenoids 110a and 110b are connected (grounded) to a common ground power supply (GND) 120. The microcomputer 200 calculates the current required by the vehicle automatic transmission system to be supplied to the solenoids 110a and 110b, uses the current value as the indicated current value, and outputs PWM signals 11a and 11b to the load drive circuits 10a and 10b to control the on and off timings of the high-side switching element 40 and the low-side switching element 50.

[0036] Since the configuration and operation of the load driving circuit 10 a and the load driving circuit 10 b are basically the same, the following description will focus on the configuration and operation of the load driving circuit 10 a provided corresponding to the solenoid 110 a .

[0037] The load driving circuit 10a receives the PWM signal 11a, and generates PWM signals 31 and 32 by the switch control circuit 30 so as to turn on the high-side switch element 40 and turn off the low-side switch element 50 when the PWM signal 11a is at a high level, and supplies current from the battery power source 150 to the solenoid 110a via the high-side switch element 40. On the other hand, when the PWM signal 11a is at a low level, the PWM signals 31 and 32 are generated so as to turn off the high-side switch element 40 and turn on the low-side switch element 50, and the current supply from the battery power source 150 is cut off, and current is supplied from the ground power source (GND) 160 to the solenoid 110a via the low-side switch element 50, so that the energy stored in the solenoid 110a is released. Since the high-side switch element 40 and the low-side switch element 50 require transition time when switching from on to off and from off to on, a period (hereinafter referred to as a dead time period) is added to the PWM signals 31 and 32 to make both the high-side switch element 40 and the low-side switch element 50 off at the time of switching between on and off so that they are not turned on. Thus, the current supplied to the solenoid 110a can be increased or decreased by changing the duty ratio of the PWM signal 11a. The duty ratio of the PWM signal 11a is feedback-controlled in a manner of correcting the difference between the indicated current value calculated by the microcomputer 200 and the current value flowing through the solenoid 110a corresponding to the duty ratio of the PWM signal 11a, thereby realizing the control of the supply current to the solenoid 110a. The current value flowing through the solenoid 110a is detected by the HS current measurement circuit 60 and the LS current measurement circuit 70 for each of the high-side switch element 40 and the low-side switch element 50. In reality, based on the current detection result, the average current value for a certain period required for feedback control is obtained by the current calculation circuit 80 and transmitted to the microcomputer 200 .

[0038] In addition to the above configuration, in the first embodiment, in order to measure the on (or off) control time (also referred to as on-duration time) of the high-side switch element 40 and the low-side switch element 50, a HS / LS control time measurement circuit 20 is provided for measuring the high-level period and the low-level period of the PWM signal 11a. For example, when the GND connection line of the current control device 100 is disconnected, the reverse current is inadvertently generated from the solenoid 110a to the current control device 100 side when the low-side switch element 50 is on and the current value supplied to the solenoid 110a is small. In particular, when the indicated current value of the solenoid 110a is near "0", the risk becomes high. Therefore, the high level period and the low level period of the PWM signal 11a are measured by the HS / LS control time measurement circuit 20. When the on-period of the low-side switch element 50 of the PWM signal 11a is long enough and the indicated current value is identified as "0", the low-side switch element 50 is temporarily disconnected by the switch control circuit 30 to prevent the generation of reverse current.

[0039] Here, the on-control time (on-duration time) of the low-side switch element 50 can be measured by the HS / LS control time measurement circuit 20 for control, and the off-control time (off-duration time) of the high-side switch element 40 can also be measured to detect the on-control time (on-duration time) of the low-side switch element 50.

[0040] In addition, Figure 1 In the embodiment, the HS / LS control time measurement circuit 20 is set for the PWM signal 11a (upstream of the switch control circuit 30), but as long as the on (or off) control time of the high-side switch element 40 and the low-side switch element 50 can be measured, the control moment is considered, such as Figure 2 As shown, it can also be set for the PWM signal 31 and the PWM signal 32 (between the switch control circuit 30 and the high-side switch element 40 and the low-side switch element 50). Figure 1 In the example shown, the on (or off) control time can be determined more quickly. Figure 2 In the example shown, the on (or off) control time can be measured more accurately.

[0041] Figure 3 The operation timing diagram of the function of preventing the generation of reverse current in the first embodiment is shown. In addition, for simplicity, the explicit description of the dead time period is omitted in the PWM signals 31 and 32 which are the control signals of the high-side switching element 40 and the low-side switching element 50. Figure 3 In FIG. 1 , the simplest example in which the duty ratio of the PWM signal 11 a becomes 0 when the instruction current value is “0” is first shown.

[0042] The PWM signal 11a is controlled by a cycle tPWM_CYC. According to the polarity of the PWM signal 11a, the switch control circuit 30 turns on either the high-side switch element 40 or the low-side switch element 50 (exclusively), thereby controlling the current supplied to the solenoid 110a. Here, the HS / LS control time measurement circuit 20 measures the low-level period ( tPWM_CYC) corresponding to the conduction time of the low-side switch element 50 every time the PWM signal 11a switches from a high level to a low level. Figure 3 In the embodiment of the present invention, if the low-level period of the PWM signal 11a is longer than a certain threshold time tLS_OFF, the PWM signal 32 is invalidated, and the switch control circuit 30 is used to temporarily control the high-side switch element 40 and the low-side switch element 50 to be turned off (in other words, the low-side switch element 50 is turned off when the high-side switch element 40 is turned off), so as to prevent the generation of reverse current. If the threshold time tLS_OFF for temporarily turning off the low-side switch element 50 is set to be greater than the switching cycle tPWM_CYC of the conduction and disconnection of the low-side switch element 50 and the high-side switch element 40, this function can be enabled only when the duty ratio of the PWM signal 11a indicating the current value of "0" becomes "0". The temporary state in which both the high-side switch element 40 and the low-side switch element 50 are turned off continues until the PWM signal 11a switches to a high level (i.e., until the PWM signal 11a as a control command to turn on the high-side switch element 40 is generated and the indicated current value is not "0"). Then, normal PWM control (i.e., synchronous rectification operation) according to the polarity of the PWM signal 11a is restored.

[0043] Here, although it is the threshold time tLS_OFF during the low level period of the PWM signal 11a, it is not ideal to disconnect the low-side switch element 50 during the period when a large current is supplied from the low-side switch element 50 to the solenoid 110a, so it is necessary to wait until the current is reduced to a certain extent. This is because the low-side switch element 50 is usually formed by a MOSFET (Metal oxide semiconductor field effect transistor), and even if it is disconnected as a switch element, the current will flow through the parasitic diode of the MOSFET, so unexpected heat will be generated. In addition, according to the structure of the current measurement circuit, the current value flowing therein cannot be measured, and an error is generated in the measured current value. The current value supplied to the solenoid 110a when the low-side switch element 50 is turned on depends on the on-resistance of the low-side switch element 50, the impedance of the solenoid 110a, and the energy accumulated in the solenoid 110a during the conduction period of the high-side switch element 40.

[0044] If the on-resistance of the low-side switch element 50 is Ron, the inductance of the solenoid 110a is Ls, the resistance value is Rs, and the peak current value when the high-side switch element 50 is turned on is I p k, the current I supplied to the solenoid 110a after a time t has passed since the low-side switching element 50 was switched on can be approximated by the following equation (1).

[0045] [Formula 1]

[0046] I=Ipk*exp(-(Rs+Ron)*t / Ls)···(1)

[0047] In addition, if the current value after the time t has passed is defined as Igoal, the time t is expressed by the following equation (2).

[0048] [Formula 2]

[0049] t=Ls / (Rs+Ron)*In(Ipk / IgoaI)···(2)

[0050] Here, Ls, Rs, Ron are known, and Ipk is as follows Figure 4 As shown, if at the moment when the PWM signal 11a switches to a low level, the current value supplied to the solenoid 110a by the HS current measurement circuit 60 and the LS current measurement circuit 70 when the low-side switch element 50 is turned on is obtained, then tLS_OFF for the desired Igoal can be obtained. Igoal is preferably a value in which the stress (current value) generated by turning off the low-side switch element 50 is below the allowable range of the device circuit device (i.e., the load drive circuit 10a of the current control device 100) and the error in the accuracy of the measured current value is negligible. In other words, the threshold time tLS_OFF (tLS_OFF obtained for the Igoal) for temporarily turning off the low-side switch element 50 is preferably set to a time such that the stress (current value) generated by cutting off the current flowing from the low-side switch element 50 to the solenoid 100a is reduced to a current value below the allowable range of the device circuit device (i.e., the load drive circuit 10a of the current control device 100). In addition, regarding the calculation of ln() in the above-mentioned formula (2), as shown in Figure 5 As shown, this can be easily achieved by dividing the Ipk obtained for each PWM cycle into several current ranges and obtaining it by a first-order approximation method. In addition, for greater simplicity, the Ipk can also be calculated by assuming (fixing) a maximum current value (=battery voltage / (Rs+Ron)) with a duty cycle of 100% of the PWM signal 11a.

[0051] In addition, in the above Figure 3In the figure, it is assumed that the duty cycle of the PWM signal 11a indicating the current value of "0" becomes "0", but in fact, there is a situation where a small duty cycle other than "0" is maintained (i.e., a situation where the PWM signal 11a is generated as a control instruction to turn on the high-side switching element 40). Figure 6 The operation timing diagram of the function of preventing the reverse current from being generated when the duty ratio of the PWM signal 11a indicating the current value of "0" is not "0" (when the indicated current value is "0" but the duty ratio is kept at a small level not equal to "0"). Figure 6 , the input and output in the switch control circuit 30, that is, the time delay (here, tPWMLH_TH) of the PWM signals 31 and 32 relative to the PWM signal 11a for ensuring the determination time is clearly shown.

[0052] and Figure 3 The same as the case of PWM signal 11a, PWM signal 11a is controlled by period tPWM_CYC, and according to the polarity of PWM signal 11a, one of high-side switch element 40 and low-side switch element 50 (exclusively) is turned on through switch control circuit 30, thereby controlling the current supplied to solenoid 110a. Here, as described above, each time PWM signal 11a is switched from high level to low level through HS / LS control time measurement circuit 20, the low level period corresponding to the conduction time of low-side switch element 50 is measured, but as in this example, when the indicated current value is "0" and the duty cycle of PWM signal 11a is not "0", PWM signal 11a changes to high level at each period tPWM_CYC. Therefore, PWM signal 11a (at Figure 2 In the example shown, the high-level period of the PWM signal 31 (i.e., the on-time duration of the high-side switch element 40) is measured. If the high-level period is less than the determination threshold tPWMLH_TH that can be judged as the high-level period indicating that the current value is equivalent to "0", the measurement of the low-level period (i.e., the on-time duration of the low-side switch element 50) is not initialized (or terminated) but directly continued. That is, in this case, the PWM signal 11a (at Figure 2In the case of the example shown, the judgment threshold value tPWMLH_TH of the high-level period (conduction duration of the high-side switch element 40) of the PWM signal 31 is set according to the conduction period of the high-side switch element 40 when the current value supplied to the solenoid 110a is controlled to be "0". In addition, if the above-mentioned low-level period is longer than a certain threshold time tLS_OFF, the PWM signal 32 is invalidated, and the switch control circuit 30 is controlled to temporarily turn off both the high-side switch element 40 and the low-side switch element 50 (in other words, the low-side switch element 50 is controlled to be turned off in the state where the high-side switch element 40 is turned off), thereby preventing the generation of reverse current.

[0053] In this case, if the threshold time tLS_OFF is set to a value obtained by adding tPWMLH_TH to the cycle tPWPW_CYC and the time delay of the PWM signals 31 and 32 relative to the PWM signal 11a (here tPWMLH_TH), the function can be enabled only when the indicated current value becomes "0". The temporary state in which both the high-side switch element 40 and the low-side switch element 50 are OFF continues until a signal that becomes greater than the determination threshold tPWMLH_TH during the high level period of the PWM signal 11a is input (that is, until the PWM signal 11a that generates a control instruction to turn on the high-side switch element 40 is greater than the determination threshold tPWMLH_TH and the indicated current value is not "0"). Thus, even when the duty ratio of the PWM signal 11a is not "0" when the indicated current value is "0", the generation of reverse current can be prevented in advance.

[0054] In addition, the above example is limited to the case where the indicated current value is "0", but by adjusting the judgment threshold tPWMLH_TH during the high level period of the PWM signal 11a, it becomes a compromise with the measurement current accuracy. Even if the indicated current value is not "0", the generation of reverse current can be prevented in advance.

[0055] As described above, according to the present embodiment, the current control device includes: the high-side switch element 40 that conducts the solenoid with the battery power source, one end of the solenoid is grounded to the ground power source; and the low-side switch element 50 that conducts with the ground power source 160, and the current control device includes: the switch control circuit 30 that controls the supply current to the solenoids 110a and 110b by turning on one of the high-side switch element 40 and the low-side switch element 50 and turning off the other; and the HS / LS control time measurement circuit (time measurement circuit) 20 that measures the on-duration time of the low-side switch element 50. Then, when the on-duration time of the low-side switch element 50 measured by the HS / LS control time measurement circuit (time measurement circuit) 20 reaches a predetermined time, the switch control circuit 30 temporarily turns off the low-side switch element 50 while the high-side switch element 40 is turned off.

[0056] That is, in order to prevent reverse current, the current supplied to the solenoids 110a and 110b is controlled by the PWM signals 11a and 11b with low duty ratios. In particular, when the PWM signals 11a and 11b with duty ratios corresponding to the indicated current value of the current "0" are used for control, the low-side switch element 50 is temporarily turned off after a certain period of time, and the reverse current path is cut off in advance. If the PWM signals 11a and 11b indicating that the indicated current value is not "0" or more than a certain value are received, the low-side switch element 50 is released from the off-fixing, and the normal synchronous rectification operation is restored in which one of the high-side switch element 40 and the low-side switch element 50 is turned on.

[0057] Thus, the reverse current path of the solenoid can be cut off in a simpler way, and undesired valve action caused by the reverse current flow can be prevented, and feedback control can be continued for the solenoid capable of normal feedback control. As a result, for the intermittent solenoid controlling the lockup clutch, for example, undesired lockup engagement can be prevented when the ground wire is disconnected, and the generation of speed change shock can be suppressed.

[0058] [Second embodiment]

[0059] The first embodiment described above is to prevent the generation of reverse current when the indicated current value is "0" or a small indicated current value, but even if one solenoid 110a is controlled by a certain indicated current, when the other solenoid 110b is operated with a very large current, a reverse current is sometimes generated when the low-side switch element 50 of the solenoid 110a is in the on state. The reverse current is controlled by feedback control of the current supplied to the solenoid, but such control usually requires more than several cycles in units of PWM cycles. Therefore, when a reverse current exceeding a certain determination threshold is detected, a function may be added to invalidate the PWM signal 32 at that moment, temporarily disconnect the low-side switch element 50, and cut off the reverse current. This function can be combined with the above-mentioned Figure 3 , Figure 6 As shown in the operation timing diagram, a function of preventing the generation of a reverse current at an indicated current value of "0" or a small indicated current value is provided in parallel.

[0060] Figure 7 It is a configuration diagram of a current control device for a vehicle automatic transmission according to a second embodiment of the present invention.

[0061] This second embodiment, relative to the above-mentioned first embodiment, adds a comparator 71 and a reverse current time measurement circuit 72. The comparator 71 detects a reverse current above a certain current threshold value Irev_th based on the current value of the LS current measurement circuit 70 to the solenoid 110a. The reverse current time measurement circuit 72 measures the time (duration) of the reverse current generation, and inputs the measurement result to the switch control circuit 30 for the switch control (also called gate control) of the conduction and disconnection of the high-side switch element 40 and the low-side switch element 50.

[0062] That is, Figure 8 As shown in the action timing diagram, the comparator 71 and the reverse current time measurement circuit 72 detect the reverse current above a certain current threshold Irev_th above a certain time threshold tDET_Irev. Thus, if it is detected that the current in the low-side switch element 50 in the opposite direction to the normal direction flows above the determination threshold (prescribed current), the PWM signal 32 is invalidated at this moment, and the low-side switch element 50 is temporarily disconnected by the switch control circuit 30 to cut off the reverse current.

[0063] in addition, Figure 7 The configuration shown is an example, and other configurations may be used as long as it can be detected that a current exceeding a predetermined current flows in the low-side switching element 50 in a direction opposite to the normal direction.

[0064] Thus, according to the second embodiment, the current control device includes the LS current measurement circuit 70, which measures the current value supplied to the solenoid 110a, and has the following function: when the LS current measurement circuit 70 detects that the current in the opposite direction to the normal direction flows more than a predetermined current, the switch control circuit 30 temporarily turns off the low-side switch element 50 while turning off the high-side switch element 40. That is, when a certain reverse current is detected when the low-side switch element 50 is turned on, the low-side switch element 50 is turned off to further cut off the reverse current path.

[0065] As a result, similar to the first embodiment, the intermittent solenoid controlling the lockup clutch can prevent unexpected lockup engagement when, for example, the ground wire is disconnected, and can suppress the occurrence of speed change shock.

[0066] In addition, the present invention is not limited to the above-mentioned embodiments, but also includes various deformation modes. For example, the above-mentioned embodiments are detailed descriptions for easily understanding the present invention, and are not necessarily limited to having all the structures described. In addition, a part of the structure of one embodiment may be replaced with the structure of other embodiments, and the structure of other embodiments may be added to the structure of one embodiment.

[0067] In addition, the control lines and signal lines are shown as those considered necessary for explanation, and not all control lines and signal lines are necessarily shown on the product.

[0068] Explanation of symbols

[0069] 10, 10a, 10b Load driving circuit

[0070] 11, 11a, 11b PWM signal

[0071] 20 HS / LS control time measurement circuit (time measurement circuit)

[0072] 30 Switch control circuit

[0073] 31 PWM signal for high-side switching element control

[0074] 32 PWM signal for controlling low-side switching element

[0075] 40 High-side switching element

[0076] 50 Low-side switching element

[0077] 60 HS current measurement circuit

[0078] 70 LS current measurement circuit

[0079] 71 Comparator

[0080] 72 Reverse current time measurement circuit

[0081] 80 Current calculation circuit

[0082] 100 Current control device

[0083] 110, 110a, 110b Solenoid

[0084] 120 Solenoid Ground Power Supply

[0085] 150 Battery Power

[0086] 160 Current control device ground power supply

[0087] 170 Current control device ground connection node

[0088] 200 Microcontroller (microcomputer).

Claims

1. A current control device, characterized in that: have: a high-side switching element that conducts a solenoid to a battery power source, one end of the solenoid being grounded to a ground power source; and The low-side switching element is connected to the ground supply. The current control device has: a switch control circuit for controlling a supply current to the solenoid by turning on one of the high-side switch element and the low-side switch element and turning off the other; as well as a time measurement circuit which determines the on-time duration of the low-side switching element, When the on-duration time of the low-side switching element reaches a predetermined time, the low-side switching element is temporarily turned off in a state where the high-side switching element is turned off.

2. The current control device according to claim 1, characterized in that: When a control command to turn on the high-side switch element is generated during the measurement of the on-time duration of the low-side switch element, if the on-time duration of the high-side switch element is less than a predetermined time, the measurement of the on-time duration of the low-side switch element is not interrupted but continued.

3. The current control device according to claim 2, characterized in that: The predetermined time as a determination threshold of the on-duration time of the high-side switching element is set based on the on-period of the high-side switching element when the current value supplied to the solenoid is controlled to be zero.

4. The current control device according to claim 1, characterized in that: After the low-side switching element is temporarily turned off, both the high-side switching element and the low-side switching element remain in the off state until a control instruction to turn on the high-side switching element is generated.

5. The current control device according to claim 1, characterized in that: When a control command to turn on the high-side switching element is generated after the low-side switching element is temporarily turned off, if the on-continuation time of the high-side switching element is less than a predetermined time, both the high-side switching element and the low-side switching element remain turned off.

6. The current control device according to claim 5, characterized in that: The predetermined time as a determination threshold of the on-duration time of the high-side switching element is set based on the on-period of the high-side switching element when the current value supplied to the solenoid is controlled to be zero.

7. The current control device according to claim 1, characterized in that: The on-duration time of the low-side switching element, which is a threshold value for temporarily turning off the low-side switching element, is set to be equal to or longer than the on-off switching cycle of the low-side switching element and the high-side switching element.

8. The current control device according to claim 1, characterized in that: The on-duration time of the low-side switching element, which is a threshold for temporarily turning off the low-side switching element, is set to a current value at which stress caused by cutting off the current flowing from the low-side switching element to the solenoid decreases to a current value below the permissible range of the current control device.

9. The current control device according to claim 1, characterized in that: The low-side switching element is a MOSFET.

10. The current control device according to claim 1, characterized in that: The solenoid is an intermittent solenoid that controls the lock-up clutch.

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