Electromagnetic switch control device

Abstract

The present invention provides an electromagnetic switch control device, wherein a control unit predicts the near future value of the operating coil current and controls it to be not less than a holding current threshold value, thereby stabilizing the contact pressure. The electromagnetic switch control device (1) uses an electromagnetic force corresponding to the current of the operating coil (16, 17) to open and close (13), and has a PWM control unit (21-23) that performs PWM pulse width modulation control on the current value (A) flowing in the operating coil (16, 17). The PWM control unit (21-23) uses the terminal voltage (V) of the operating coil (16, 17) to estimate the near future predicted current value flowing in the operating coil (16, 17), and performs PWM control based on it. The predicted current value (Y) is estimated using the impedance (Z) of the operating coil (16, 17). The impedance uses a constant obtained by approximating a variable obtained from the terminal voltage (V1, V2) and the current value (A1, A2) of the operating coil (16, 17) in a specified period from the recent past to the present. The impedance is updated at every predetermined period.

Description

Technical Field

[0001] The present invention relates to an electromagnetic switch control device, and more particularly to an electromagnetic switch control device for controlling the switching of an electromagnetic switch inserted between a power source and a load to switch a conductive path. Background Art

[0002] As shown in Patent Document 1, there is known an operating coil driving device that calculates the impedance of an operating coil (inductive load) of an electromagnetic switch and controls the operating coil to supply an appropriate current when the electromagnetic switch is switched.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2017 / 159070 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In a power supply system that uses a battery pack consisting of multiple single cells connected in series and parallel as a power source, when pulse control is performed on an electromagnetic switch (inductive load) connected to the battery pack and a load on one side of the system, a holding current needs to flow to keep the electromagnetic switch in a closed (hereinafter also referred to as "on") state.

[0008] In addition, when the contact resistance of the electrical contacts (hereinafter also referred to as "contact parts" or simply "contacts") in the electromagnetic switch increases, heat deteriorates when the closed circuit is energized. Thus, when the charge and discharge current of the battery pack flows in a state where the contact resistance of the contacts (hereinafter also referred to as "contact resistance") increases, there is a risk that the electromagnetic switch will be welded due to the heat of the contact parts, thereby causing failure.

[0009] In order to avoid such failures, it is necessary to control the operation to be able to work continuously and safely. In addition, although it is a closed-circuit power-on control, the operating coil current is insufficient to produce an unstable lower limit value of the electromagnetic force that allows the contacts to be reliably adsorbed and maintained (hereinafter also referred to as the "minimum holding current" or simply "holding current"), and the contact pressure is insufficient, so an arc may be generated at the contact, causing the contact to be gradually damaged and the contact resistance to increase. In order to avoid this situation, it is necessary to ensure sufficient contact pressure by providing the operating coil current stably as required.

[0010] In addition, when the supply voltage drops due to an overload exceeding the supply capacity of the power supply system, or when the battery is over-discharged, or when these factors act together, the operating coil current of the electromagnetic switch decreases and becomes insufficient. This situation causes the increase in contact resistance as described above. In order to avoid this situation, it is necessary to prevent the operating coil current from decreasing.

[0011] Therefore, if the control unit can detect in advance that the operating coil current is below the control lower limit (hereinafter also referred to as the "holding current threshold" or simply "holding current"), it is effective to control it to be not lower than the holding current threshold of the operating coil based on the detection result. For example, in order to make the operating coil current A not lower than the holding current, if PWM control is used, the on-duty (duty cycle) of the switching element is controlled. In other words, the control is made so that the on / off duty cycle is close to 100%, that is, the on time is longer than the off time.

[0012] However, the technology described in Patent Document 1 cannot predict the near future value of the operating coil current. Therefore, there is a problem that the control unit cannot detect in advance so as not to fall below the holding current threshold of the operating coil and cannot prevent the operating coil current from decreasing. The present invention is made to solve such a problem, and its purpose is to provide an electromagnetic switch control device that can stabilize the contact pressure by predicting the near future value of the operating coil current in advance by the control unit and controlling it to not fall below the holding current threshold.

[0013] Technical solutions to solve problems

[0014] In order to solve the above-mentioned problems, the present invention is an electromagnetic switch control device, which allows a current with a current value of a duty cycle under PWM control to flow through an operating coil and causes electric contacts to be opened and closed by an electromagnetic force corresponding to the current value, and comprises: a current value prediction unit, which uses the terminal voltage value of the operating coil to estimate the predicted current value in the near future; a control range judgment unit, which judges whether the estimated predicted current value is outside the range that can maintain the current of the operating coil; and a PWM control unit, which controls to change the duty cycle based on the predicted current value when the judgment result of the control range judgment unit is outside the range.

[0015] Effects of the Invention

[0016] Provided is an electromagnetic switch control device capable of stabilizing contact pressure by predicting a near-future value of an operating coil current and controlling the current so as not to be lower than a holding current threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a circuit diagram showing a schematic configuration of a battery-type power supply system using an electromagnetic switch control device (hereinafter also referred to as “this device”) according to an embodiment of the present invention.

[0018] Figure 2 It is simply explained Figure 1 The timing diagram of the PWM control in the present device shows the switching timings of (a) the main switch 7-1, (b) the main switch 7-2, and (c) the sub-switch 8.

[0019] Figure 3 is a more detailed representation Figure 1 The circuit diagram of this device.

[0020] Figure 4 Yes Description Figure 1 and Figure 3 The timing diagram of the changes in voltage and current of the operating coil based on PWM control in the present device respectively shows (a) supply voltage Vcc, (b) terminal voltage V of the operating coil, (c) current value A of the operating coil, and (d) duty cycle of PWM control.

[0021] Figure 5 Yes Description Figure 1 and Figure 3 Flow chart of the processing flow when controlling the operating coil in this device, Figure 5 (a) indicates the pulling process, Figure 5 (b) represents the voltage / current measurement and duty cycle update process, Figure 5 (c) shows the process of obtaining the resistance R value and the inductance L value (hereinafter referred to as "RL"). DETAILED DESCRIPTION

[0022] Hereinafter, an example in which the present device is applied to a battery-type power supply system will be described using the drawings. Figure 1 This is a circuit diagram showing the schematic structure of a battery-type power supply system (hereinafter also referred to as "this system") using this device. Figure 1 As shown, the system is composed of an electric motor 1, an inverter 2, a device 3, a battery pack 6, main contactors (hereinafter also referred to as "main switches" or "electromagnetic switches") 7-1, 7-2 (the two are collectively referred to as 7), a pre-charging relay (hereinafter also referred to as "auxiliary switches" or "electromagnetic switches") 8, and a pre-charging resistor 9.

[0023] The battery pack 6 is configured so that the required voltage is obtained as a whole by connecting two battery modules 5 in series. The battery module 5 is configured so that half of the required voltage is obtained by connecting four single cells 4 of secondary batteries in series. In addition, the battery modules 5 and single cells 4 constituting the battery pack 6 are shown as examples here in which all the battery modules 5 and single cells 4 are connected in series with polarity added, but they can also be connected in series, in parallel, or in combination as appropriate according to the application.

[0024] As described above, in the 8 cells 4 constituting the battery pack 6 in which all cells are connected in series with polarity added, 9 voltage measurement lines 12 are led out from the respective power supply terminals. The 9 voltage measurement lines 12 are connected to the device 3 having a microcomputer (microcomputer), and are configured to monitor the state of charge and discharge and other management items. In addition, it can also be a method of appropriately connecting the 8 cells 4 in series or in parallel. Furthermore, there are also cases where the voltage measurement lines 12 of the connection method corresponding to various different monitoring purposes and management standards are connected to the device 3, but illustrations and descriptions of them are omitted.

[0025] The motor 1 is a load of the inverter 2. The inverter 2 is a load of the battery pack 6. The battery pack 6 and the inverter 2 are connected via two main switches (electromagnetic switches) 7 and a sub-switch (electromagnetic switch) 8, a total of three electromagnetic switches. The three electromagnetic switches 7 and 8 can be controlled by the device 3 to have a conductive state of either a closed circuit or an open circuit (on / off).

[0026] The main switch 7-1 is inserted into the circuit on the positive side of the battery pack 6, and has a function of instantaneously switching most of the current. The main switch 7-2 is inserted into the circuit on the negative side of the battery pack 6, and has a function of instantaneously switching the total current. On the other hand, the sub-switch 8 is inserted into the circuit on the positive side like the main switch 7-1, and has a function of switching a small current limited to a certain degree. The sub-switch 8 is turned on / off controlled at an appropriate timing set by the GPIO (General-purpose input / output) described later.

[0027] The current of the auxiliary switch 8 is limited to a small degree, which is determined by the resistance value of the pre-charge resistor 9 connected in series with the auxiliary switch 8. The auxiliary switch 8 connected in series with the pre-charge resistor 9 is connected in parallel with the main switch 7-1 as a relay for preventing inrush current. The present device 3 monitors the charge and discharge status of each individual battery 4 constituting the battery pack 6. In addition, the present device 3 is used as Figure 2 As described later, the main switch 7 and the sub-switch 8 inserted between the battery pack 6 and the inverter 2 are switched at appropriate timings.

[0028] The electromagnetic switch control device (this device) 3 is a control device that flows a current value A of a duty ratio (hereinafter also referred to as "duty ratio") controlled by PWM through the operating coils 16 and 17 of the electromagnetic switch 7, and opens and closes the electric contact 13 of the electromagnetic switch 7 by an electromagnetic force corresponding to the current value A. The device 3 is configured to include a current value prediction unit 19, a control range determination unit 20, and a PWM control unit 21.

[0029] The current value prediction unit 19 uses the terminal voltages V1 and V2 (collectively referred to as V) of the operating coils 16 and 17 to estimate the predicted current value Y in the near future. The control range judgment unit 20 determines whether the estimated predicted current value Y is outside the range in which the current of the operating coils 16 and 17 is maintained, that is, the electromagnetic force that can be exerted to maintain the contact 13 in the adsorption state is maintained.

[0030] When the judgment result of the control range judgment unit 20 is outside the maintainable range, the PWM control unit 21 controls to change the duty ratio based on the predicted current value Y. Since the device 3 is configured in this way, the PWM control unit 21 predicts the near future value X of the operating coil current A and controls it to be not less than the holding current threshold value W, so that the contact pressure of the contact 13 can be stabilized.

[0031] Figure 2 It is simply explained Figure 1 The timing diagram of the PWM control in the present device shows the switching timing of (a) the main switch 7-1, (b) the main switch 7-2, and (c) the auxiliary switch 8. Figure 2 As shown, when the battery pack 6 is connected to the inverter 2, the device 3 connects the sub-switch 8 before the main switch 7-1 to prevent inrush current, thereby limiting the inrush current by the pre-charging resistor 9 so that it does not exceed the allowable current of the main switch 7. In addition, the device 3 closes (turns on) each contact 13 by energizing the operating coils 16, 17, and 18 with the electromagnetic switch power supply (contactor power supply) 10, and when the power supply is stopped (turned off), the contacts are released by a spring not shown.

[0032] More specifically, for example, in a hybrid vehicle or a battery vehicle, connection and disconnection (ON / OFF) are supported between a DC power source and a load. Figure 2 As shown, the sub-switch 8 is controlled by GPIO in a timing manner so that it closes slightly earlier than the main switch 7-1 when closing. By precharging the inrush current when closing the DC circuit with a large current of a capacitor in the load according to this timing control, the contact of the main switch 7 can be protected.

[0033] Next, use Figure 3 The circuit structure of the present device 3 is described. Figure 3 is a more detailed representation Figure 1 The circuit diagram of the present device 3. Figure 3Starting from the present invention, the battery pack 6 as a power source and the motor and inverter 2 as a load are omitted, and the main part of the present device 3 is assumed to be mainly composed of the microcomputer control unit 11 that controls the main switch 7 and the sub-switch 8. In addition, the coil current contactor (coil switch, electromagnetic switch) 15 has the function of a main switch that controls the electromagnetic switch power supply (contactor power supply) 10 to energize all the operating coils 16 to 18 at the same time, but it is assumed to be normally connected here for description.

[0034] The control unit constituting the main part of the device 3 is composed of switch elements 38 to 40 connected to the microcomputer control unit 11 to perform on / off operations, an RC filter circuit consisting of a combination of a resistor R and a capacitor C for setting time constants T1 and T2 [seconds], and return diodes 41 and 42. In addition, the definition of the time constant T [seconds] will be described later.

[0035] The microcomputer control unit 11 includes a current value prediction unit 19, a control range determination unit 20, a PMW control unit 21 to 23, and ADCs (A / D converters) 24 to 30. The PMW control unit 21 is divided into PWM control units 22 and 23 and operates independently. In addition, these units do not necessarily have to be included in the microcomputer control unit 11, and may be dispersed.

[0036] The microcomputer control unit 11 has signal input and output. Signals are input to ADC24~30, and voltage values ​​and current values ​​are input as analog signals, and A / D conversion is performed to suit the processing of the microcomputer. Therefore, ADC24, 25, 27, 29 form an operating coil voltage measurement circuit, and ADC26, 28, 30 form an operating coil current measurement circuit. On the other hand, the PMW control units 21~23 output High / Low signals that turn on / off the switch elements 38 and 39. In addition, the GPIO of the microcomputer control unit 11 outputs a High / Low signal that turns on / off the switch element 40. The switch elements 38~40 control the energization of the operating coils 16~18 of the main switch 7 and the sub-switch 8 respectively.

[0037] As described above, the present device 3 forms a control function for properly turning on / off the circuit in a battery-type power supply system formed by a battery pack 6 composed of a plurality of secondary batteries 4 connected in series, a load receiving power supply from the battery pack, and a combination of electromagnetic switches 16 to 18 inserted in the current path. An embodiment of the present device 3 is shown as an example in which the present device 3 is used in a hybrid vehicle or a battery-powered vehicle not shown. The battery pack 6 is further connected to an operating coil voltage measurement circuit (also called "ADC") 24, 25, 27 and a voltage measurement filter circuit 31, 32, 33.

[0038] ADC24, 25, 27, 29 measures the terminal voltage V of the operating coils 16, 17, 18. In addition, the voltage measurement filter circuits 31, 32, 33, 34 are low-pass filters provided between the operating coils 16, 17, 18 and the ADCs 24, 25, 27, 29, and remove high-frequency components such as spike noise that are harmful to the voltage measurement. Through these structures, the transiently changing predicted current value Y can be calculated using the terminal voltage V of the operating coils 16, 17, the impedance Z of the operating coils 16, 17, and the time constant T1 of the voltage measurement filter circuits 31, 32, 33.

[0039] In addition, the device 3 also has an operating coil current measurement circuit (ADC) 26, 28, 30 and a current measurement filter circuit 35, 36, 37. The operating coil current measurement circuit 26, 28, 30 measures the current energized to the operating coils 16, 17. The current measurement filter circuit 35, 36, 37 is a low-pass filter provided between the operating coils 16, 17, 18 and the operating coil current measurement circuit 26, 28, 30, and removes high-frequency components such as spike noise that are harmful to current measurement.

[0040] The impedance Z can be calculated using the terminal voltage V, the time constant T1 of the voltage measurement filter circuits 31, 32, 33, the current value A, and the time constant T2 of the current measurement filter circuits 35, 36. The impedance Z is calculated based on the terminal voltage V and the current value A of the operating coils 16, 17 during the on period when the duty ratio in the PWM control is set to 100% because the closed circuit state is set. In addition, impedance Z = terminal voltage V / current value A. In addition, the terminal voltages V1, V2 and the current values ​​A1, A2 of the operating coils 16, 17 are combined and referred to as the terminal voltage V and the current value A, respectively.

[0041] The microcomputer control unit 11 turns on / off the switch element 40 according to the output signal of either High or Low from the GPIO, thereby switching the on / off state of the auxiliary switch 8. Similarly, the microcomputer control unit 11 turns on / off the switch elements 38 and 39 according to the pulse control signal output from the PWM control units 21 to 23, thereby switching the on / off state of the main switches 7-1 and 7-2. For example, when the switch elements 38 to 40 are composed of NPN transistors or the like, current flows through each of the operating coils 16 to 18 during the period when the output signal of the microcomputer control unit 11 is High.

[0042] On the contrary, in order to reliably turn off the main switches 7 and 8 by switching the output signal of the microcomputer control unit 11 from High to Low, it is necessary to quickly eliminate the excitation current in the reverse direction caused by the inductive component of the operating coils 16 and 18. By allowing the excitation current to escape as a return current through the return diodes 41 and 42, the excitation current that is intended to continue to flow to the operating coils 16 to 18 can be quickly eliminated.

[0043] Next, use Figure 4 and Figure 5 The duty ratio control of the current A during the on-period of the main switch 7, that is, during the energization of the operating coils 16-17, will be described. Note that the duty ratio control of the operating coil 18 of the pre-charging relay (sub-switch) 8 does not need to be performed.

[0044] Figure 4 Yes Description Figure 1 and Figure 3 The timing diagram of the changes in voltage and current of the operating coil based on PWM control in the present device respectively shows (a) supply voltage Vcc, (b) terminal voltage V of the operating coil, (c) current value A of the operating coil, and (d) duty cycle of PWM control.

[0045] Figure 4 (a) The supply voltage Vcc and Figure 4 The terminal voltage V of the operating coil of (b) is always kept ideal as shown in the left half of each figure. However, in a power supply structure using a battery, such as a battery-type power supply system (this system), if the load is larger than the supply capacity, even if there is a constant voltage guarantee scheme, a certain degree of voltage fluctuation (especially drop) must be assumed.

[0046] like Figure 4 As shown near the horizontal center of (a), when the supply voltage Vcc decreases, Figure 4 As shown near the horizontal center in (b), the near future value is predicted based on the change direction of the measured value V obtained by ADC24, 25, and 27. Figure 4 In (d), as shown in the time sequence from left to right, the microcomputer control unit 11 appropriately controls the duty ratio of the PWM control to 0 to 100% through internal calculation processing.

[0047] for Figure 4 The current value A of the operating coil shown in (c) is controlled from 0 to 100% in a manner following the duty ratio of the PWM control. However, there is a time delay, but as described later, the microcomputer control unit 11 monitors the duty ratio. Figure 4 (b) and Figure 4While the terminal voltage V shown in (c) and the current values ​​A1 and A2 (collectively referred to as A) of the operating coils 16 and 17 change, 0 to 100% control is appropriately performed through internal calculation processing.

[0048] More specifically, it is divided into Figure 4 During each period of the sequence from left to right, the following three action modes, namely <1> to <3>, are executed.

[0049] <1> Pull-in mode, that is, a mode in which the duty ratio is set to 100% output in order to reliably maintain the attracted state during the pull-in period immediately after the contact 13 is attracted (refer to Figure 5 (a)).

[0050] <2> Holding current holding mode, i.e., during the normal operation period of maintaining the adsorption state of the contact 13, the current value A of the operating coils 16 and 17 is reduced by PWM control, but the holding current W is maintained at not less than the necessary minimum (refer to Figure 5 (b)).

[0051] <3> RL update period mode, that is, in the RL update period for correcting the amount of impedance Z drift of the operating coils 16 and 17 in the electromagnetic switch 7, the PWM control duty ratio is set to 100% as in the pulling period (refer to Figure 5 (c)).

[0052] In the above-mentioned mode <1>, when the main switch 7 is turned from off to on, the duty ratio is first set to 100%, thereby causing the current value A to rise sharply to 100%. As a result, the contact 13 of the main switch 7, which is opened by the elastic force of a spring (not shown), is attracted (pulled) and turns from off to on. In addition, in the above-mentioned mode <2>, in order to maintain the on state, both the duty ratio and the current value A can be relaxed from 100% to near the closed circuit holding current lower limit value (holding lower limit value) W.

[0053] However, in this mode <2>, when the supply voltage Vcc and the terminal voltage V drop for some reason while the main switch 7 is kept on, the current value A required for keeping on drops below the lower limit value W, and it is predicted that the main switch 7 will accidentally turn off. In order to avoid such a predicted failure, in the above mode <2>, PWM control is performed so that the current value exceeds the lower limit value W.

[0054] After the PWM control to counteract such a predicted decrease, in the above-mentioned mode <3>, a period is set to update the resistance value R and the inductance L value (abbreviated as "RL") of the operating coils 16 and 17 in the electromagnetic switch 7, and the duty cycle is set to 100% again during this period, and the current value A also rises to 100%. Regarding this RL update period, use Figure 5 Described in the following text.

[0055] in addition, Figure 4 The time sequence from left to right in (d) shows the control of the duty cycle from 0 to 100%, which is determined by Figure 3 The PWM control units 21, 22, and 23 formed in the microcomputer control unit 11 shown in the figure perform calculation processing. As a result, the PWM control units 21 to 23 output ON / OFF PWM output signals having a required duty ratio and a High / Low configuration with appropriately set timing.

[0056] Figure 5 Yes Description Figure 1 and Figure 3 Flow chart of the processing flow when controlling the operating coil in this device, Figure 5 (a) indicates the pulling process, Figure 5 (b) represents the voltage / current measurement and duty cycle update process, Figure 5 (c) represents the RL acquisition process.

[0057] like Figure 5 As shown in (a), the traction process includes processing S1 of setting the PWM output signal to a duty cycle of 100%, processing S2 of measuring voltage / current, processing S3 of determining whether the transient response has ended, processing S4 of calculating the coil RL, and processing S5 of determining whether the traction time has passed.

[0058] Immediately after the main switch 7 is turned on, the control unit 11 sets a draw period in which the PWM output signal is output with a duty ratio of 100% ( S1 ) in order to ensure a draw current for reliably closing the main switch 7 .

[0059] Next, in order not to be lower than the closed-circuit holding current W of the main switch 7, the average current A of the operating coils 16 and 17 is measured (S2), and at the same time, it is determined whether the transient response has ended (S3). If S3 is No, the voltage / current measurement process S2 is continued. If S3 is Yes, the coil RL calculation process S4 is performed. Next, if the result of determining whether the traction time has passed in S5 is No, the coil RL calculation process S4 is continued. If S5 is Yes, the traction process is terminated.

[0060] like Figure 5 As shown in (b), the voltage / current measurement and duty cycle update processing includes voltage / current measurement processing S6, power supply (terminal) voltage near future value calculation processing S7, coil current near future value calculation processing S8, control range judgment processing S9, PMW control duty cycle recalculation processing S10 and PMW control output duty cycle change processing S11.

[0061] In the voltage / current measurement process S6, the terminal voltage V and the current value A of the operating coils 16 and 17 are measured. In the power supply voltage near future value calculation (voltage prediction) process S7, the near future voltage value X is calculated based on the state of the terminal voltage V changing not long ago.

[0062] In coil current near future value calculation (current prediction) process S8, near future predicted current value Y flowing through operation coils 16 and 17 is estimated based on near future voltage value X. In control range determination process S9, it is determined whether the estimated predicted current value Y is lower than threshold value W.

[0063] In S9, when the predicted current value Y is lower than the threshold value W (Yes in S9), it is determined that it is out of the range in which the current of the operating coils 16 and 17 can be maintained. In other words, it is determined that it is lower than the minimum coil current value W required to stably maintain the adsorption state of the contact 13. If No in S9, the process returns to S6.

[0064] If the answer is yes in S9, the process proceeds to PMW control duty recalculation processing S10. In S10, the optimal duty is recalculated based on the predicted current value Y. Next, the process proceeds to PMW control duty change processing S11, and the optimal duty obtained in S10 is output.

[0065] like Figure 5 As shown in (C), the RL acquisition process includes a PWM control duty ratio 100% output process S12, a voltage / current measurement process S13, a transient response completion determination process S14, and a coil RL calculation process S15. Figure 5 (C) S12~S15 and Figure 5 S1 to S4 of (A) are equivalent, so their description is omitted.

[0066] in addition, Figure 5 In (C), a series of processing ends when the coil RL calculation processing S15 ends. Figure 5 In (A), the state is changed because the pull time for the electromagnetic switch 7 to change to the closed state has passed. That is, the process ends after the electromagnetic switch 7 changes from the open circuit to the closed circuit state.

[0067] When the supply voltage Vcc of the electromagnetic switch 7 changes, a response delay (also called "first-order lag") cannot be avoided in the general PWM control based on the prior art, and a failure that cannot cope with the change may occur. The cause of this first-order lag is a transient phenomenon defined by a time constant (hereinafter also called "RC time constant", "RL time constant" or simply "time constant") T acting on the DC power supply voltage E by the resistor R, capacitor C, or coil L.

[0068] Regarding such a transition phenomenon, a simple theoretical explanation is given without drawing. In addition, in the theoretical explanation, the DC supply voltage Vcc is simplified to the power supply voltage E. In addition, the power supply voltage E, the resistor R, the capacitor C, the coil L, the current I that is energized and gradually changes, and the respective terminal voltages can be numerically calculated using well-known differential equations and natural functions. However, the explanation is simplified here to show that even if the following simple definition of the time constant T is used, it can be understood to a certain extent.

[0069] The transition phenomenon defined by the time constant T refers to the phenomenon that occurs during the transition from one steady state to the next. More specifically, when a DC power source E is connected to a series circuit having a capacitor C or a coil L through a resistor R and the switch is turned on or off, the voltage and current I of each part of the circuit gradually change and stabilize in the next state.

[0070] Here, as an example, relative to the maximum voltage change amplitude E caused by the change from disconnection to connection of the DC power supply E, the steady-state current value Is transferred to the next steady state = E / R. Such a stable current value Is is set as the steady-state value Is. In addition, the time constant T is an indicator of the speed of change until stability. The smaller the time constant T, the more rapid the change, and the larger the time constant T, the slower the change.

[0071] In the present device 3, the impedance Z is a transient variable obtained from the terminal voltage V of the operating coils 16 and 17 and the current value A flowing through the operating coils 16 and 17, but can be regarded as a constant approximately obtained in a prescribed period from the recent past to the present. That is, based on the consideration of the time constant T, it can be regarded as a constant approximately obtained by impedance Z≈R=E / I.

[0072] Furthermore, the time constant T is defined as the time required to reach the steady-state value Is in the direction from OFF to ON, which is about 0.63 times. Conversely, the time constant T is defined as the time required to reach the steady-state value I in the direction from ON to OFF, which is about 0.37 times.

[0073] In addition, the time constant of the RC series circuit is T = C·R [seconds], and the time constant of the RL series circuit is T = L / R [seconds]. In addition, the power supply voltage E, the resistor R, the capacitor C, and the coil L can not only be numerically measured in real time by a measuring device or in combination with the microcomputer control unit 11, but can also be considered as known constants. However, these constants have temperature characteristics, so when implemented in a hybrid vehicle or a battery vehicle, for example, the temperature characteristics are considered for design.

[0074] In a configuration in which the above-mentioned calculation method of the RL value is recorded in advance as a map (table) inside the microcomputer control unit 11, the control duty ratio may be calculated.

[0075] In the above <2>, after the contact 13 of the electromagnetic switch 7 is connected, the duty cycle is controlled so that a certain current value A flows through the operating coils 16 and 17 in order to reduce power consumption. In the above <2>, when a sudden change in the terminal voltage V occurs, the current waveform of the coil current A is delayed relative to the waveform of the terminal voltage V because the operating coils 16 and 17 have a time constant T.

[0076] When the duty ratio is adjusted by PMW control based on the delayed current A, it is necessary to predict the delay in the control, so in the prior art, a higher current level is controlled with an unnecessary margin relative to the threshold W. As a result, there is a disadvantage of increasing the power consumption for turning on the electromagnetic switch 7. The present invention eliminates this disadvantage.

[0077] According to the present device 3 and the present method, the resistance value R and the inductance value L (RL value) of the operating coils 16 and 17 are calculated based on the transient response waveform when the contact 13 is transferred from disconnection to connection. The theory used for the calculation is the above-mentioned "time constant T is defined as the time to reach the steady-state value Is in the direction from disconnection to connection", and "the time constant T of the RL series circuit = L / R [seconds]" is used.

[0078] Based on the theory of the above-mentioned transition phenomenon, the resistance value R and the inductance value L (RL value) of the operating coils 16 and 17 can be calculated from the transient response waveform that causes the contact 13 to transition from disconnection to connection. Based on the calculated RL value, the current change is predicted from the voltage waveform of the terminal voltage V, so that even when a sharp change in the terminal voltage V occurs, the duty cycle control can be fed back without delay.

[0079] As a result, the margin with respect to the threshold value W can be reduced compared to the conventional method, so that the power consumption for turning on the electromagnetic switch 7 can be reduced. In addition, since the RL value changes with temperature, when the electromagnetic switch 7 is used in a hybrid vehicle or a battery vehicle, for example, the RL value is calculated regularly in consideration of the temperature change while the vehicle is running, thereby enabling more precise control.

[0080] [Modifications]

[0081] Next, a modified example that is more in line with reality is briefly described. In this modified example, the basic operation shown below is also the same as that of the above-mentioned device 3 and method. That is, the terminal voltage V of the operating coils 16 to 18 is measured by the operating coil voltage measurement circuits (ADC) 24, 25, 27, and 29 of the microcomputer control unit 11 via the voltage measurement filter circuits 31 to 34.

[0082] The microcomputer control unit 11 calculates the near future value X of the terminal voltage V of the operating coils 16 and 17 based on the acquired terminal voltage V. Based on the near future voltage value X and the impedance Z, the near future value Y of the current A corresponding to the current duty cycle value is predicted. When the predicted near future value Y is outside the specified control current range, the duty cycle is recalculated by the PWM control units 21 to 23, and the on / off time ratio, i.e., the duty cycle, of the switching elements 38 and 39 is switched. Up to this processing, the modified example is the same as the above-mentioned present device 3 and the present method.

[0083] In contrast, the characteristics of the modified example are as follows. First, when the current value A flowing through the operating coils 16 and 17 decreases, a process is performed to determine whether the cause is a disconnection abnormality of the return current path of the operating coils 16 and 17, such as the return diodes 41 and 42, and a process is performed to determine whether a decrease in the terminal voltage V is the cause.

[0084] If the result of these determination processes is that the cause of the decrease in the current value A is a disconnection abnormality in the return current path or a decrease in the terminal voltage V, then a process of increasing the control duty ratio is performed in order to increase the operating coil current A to a level above the holding current. After such a process of increasing the control duty ratio is performed, a process is performed to determine whether the current holding of the operating coils 16 and 17 can be performed.

[0085] When it is determined that the current of the operating coils 16 and 17 cannot be maintained as a result of the judgment, the microcomputer control unit 11 switches the duty ratio value to 100% in order to cope with the situation where the supply voltage Vcc of the electromagnetic switch 7 is significantly reduced. When it is determined that the closed circuit holding current lower limit W of the electromagnetic switch 7 cannot be maintained even if the duty ratio is set to 100%, the output of the signal to turn on the electromagnetic switches 17 and 18 is stopped. In other words, when it is lower than or expected to be lower than the threshold value W, in order to prevent a major failure in which the contact 13 of the electromagnetic switch 7 is welded due to a reduction in contact force, it is diagnosed as a supply voltage reduction abnormality and the output of the turn-on signal is stopped.

[0086] At this time, the microcomputer control unit 11 controls to immediately stop the PMW control and switch the electromagnetic switches 7 and 8 from on to off. This modification is adopted in the case of a hybrid vehicle or a battery vehicle, in which the power running or regeneration operation is stopped, thereby preventing damage to the electromagnetic switches 7 and 8. In addition, there is also a case where the electromagnetic switch 8 is excluded from the protection object.

[0087] In addition, at this time, the real cause such as over-discharge of the battery supplying the main power source Vcc for driving should be found out. If the cause is over-discharge of the battery in a battery-powered vehicle, it is not a fault, but simply fuel exhaustion in gasoline-powered vehicles. In this case, control is implemented to prioritize the prevention of a major fault such as welding of the electromagnetic switch 7 due to reduced contact force. Because of such an effect, the present invention is suitable for the purpose of monitoring the charge and discharge state of the battery in a power supply system using a battery pack as a power source.

[0088] Next, the gist of the present invention will be described in accordance with the scope of claims.

[0089] [1] The electromagnetic switch control device (this device) 3 is a control device that causes the current value A of the duty ratio controlled by PWM to flow through the operating coils 16 and 17, and uses the electromagnetic force corresponding to the current value A to open and close the contact 13 of the electromagnetic switch 7. This device 3 includes a current value prediction unit 19, a control range determination unit 20, and PWM control units 21 to 23.

[0090] The current value prediction unit 19 uses the terminal voltage V of the operating coils 16 and 17 to estimate the predicted current value Y in the near future. The control range determination unit 20 determines whether the estimated predicted current value Y is outside the range in which the current of the operating coils 16 and 17 can be maintained, that is, the electromagnetic force that can maintain the contact 13 in the adsorption state can be exerted and maintained.

[0091] When the judgment result based on the predicted current value Y by the control range judgment unit 20 is outside the maintainable range, the PWM control unit 21 controls to change the duty ratio based on the predicted current value Y. The present device 3 is configured in this way, so that the PWM control unit 21 predicts the near future value Y of the operating coil current A and controls it to be not less than the holding current threshold value W, which can stabilize the contact pressure of the contact 13.

[0092] [2] In the present device 3, the predicted current value Y is preferably estimated using the impedance Z of the operating coils 16 and 17. That is, the microcomputer control unit 11 calculates the near future value X of the terminal voltage V of the operating coils 16 and 17 based on the acquired terminal voltage V. Based on the near future voltage value X and the impedance Z, the near future value Y of the current A corresponding to the current duty cycle value is predicted.

[0093] [3] In the present device 3, the impedance Z can be regarded as a constant approximated in a specified period from the recent past to the present, which is a transient variable obtained by the terminal voltage V of the operating coils 16 and 17 and the current value A flowing through the operating coils 16 and 17. More specifically, based on the consideration of the time constant T, it can be regarded as a constant approximated by impedance Z≈R=E / I.

[0094] The time constant T is defined as the time to reach the steady-state value Is in the direction from off to on. Conversely, the time constant T is defined as the time to reach the steady-state value I in the direction from on to off. Even the impedance Z calculated as a transient variable based on the theory of such a transition phenomenon can be approximated as a constant as long as it is divided into a specified period from the recent past to the present. Thus, the predicted current value Y can be estimated using the impedance Z of the operating coils 16 and 17.

[0095] [4] The constants approximating the impedance Z are preferably updated at each prescribed period in order to estimate the predicted current value Y in the near future from the present. The coil L, resistor R or capacitor C forming the impedance Z can be numerically measured in real time by a meter or in combination with the microcomputer control unit 11, and can also be considered as known constants. However, these constants have temperature characteristics, so when implemented in hybrid vehicles or battery vehicles, for example, they are designed in consideration of temperature characteristics. That is, the constants approximating the impedance Z, which are not constant, are preferably updated at each prescribed period.

[0096] [5] The device 3 preferably forms a control function for appropriately turning on / off the circuit in a combination of a battery-type power supply system formed by a battery pack 6 composed of a plurality of secondary batteries 4 connected in series or in parallel, a load receiving power supply from the battery pack, and electromagnetic switches 16 to 18 inserted in the current path. A voltage measurement function similar to ADCs 24, 25, 27 and voltage measurement filter circuits 31, 32, 33 is also connected to the battery pack 6.

[0097] ADC24, 25, 27 measures the terminal voltage V of the operating coils 16, 17. In addition, the voltage measurement filter circuits 31, 32, 33 are provided between the operating coils 16, 17 and the operating coil voltage measurement circuits (ADC) 24, 25, 27. The predicted current value Y is preferably calculated using the terminal voltage V of the operating coils 16, 17, the impedance Z of the operating coils 16, 17, and the time constant T1 of the voltage measurement filter circuits 31, 32, 33.

[0098] [6] The battery pack 6 is preferably also connected to the operating coil current measurement circuit (ADC) 26, 28 and the current measurement filter circuit 35, 36. The operating coil current measurement circuit 26, 28 measures the current flowing through the operating coil 16, 17. The current measurement filter circuit 35, 36 is provided between the operating coil 16, 17 and the operating coil current measurement circuit 26, 28.

[0099] The impedance Z is preferably calculated using the terminal voltage V, the time constant T1 of the voltage measurement filter circuits 31 , 32 , and 33 , the current value A, and the time constant T2 of the current measurement filter circuits 21 to 23 .

[0100] [7] The impedance Z is preferably calculated from the terminal voltage V and the current value A of the operating coils 16 and 17 during the on-period when the duty ratio in the PWM control is set to 100% in order to close the electrical contact 13. In this regard, in the above-mentioned <3> RL update period mode, the RL update period for correcting the amount of impedance Z drift of the operating coils 16 and 17 in the electromagnetic switch 7 is different from the mode in which the PWM control duty ratio is set to 100% in the same manner as the pull period (see Figure 5 The same as described in (c)).

[0101] [8] The electromagnetic switch control method (this method) is a control method in which the PWM control unit 21-23 performs PWM control on the current value A flowing through the operating coils 16 and 17 of the electromagnetic switch 7, and uses the electromagnetic force corresponding to the energization duty ratio controlled by PWM to open and close the electrical contact 13. The method includes a voltage / current measurement process S6, a current prediction process S8, and a PWM control process S9-S11. In the voltage / current measurement process S6, the terminal voltage V and the current value A of the operating coils 16 and 17 are measured.

[0102] In the current prediction process S8, the near future predicted current value Y flowing through the operating coils 16 and 17 is estimated. In the PWM control processes S9 to S11, if it is determined that the estimated predicted current value Y is outside the range in which the current of the operating coils 16 and 17 can be maintained, the duty ratio is changed based on the predicted current value Y.

[0103] In order to control the current value A flowing through the operating coils 16 and 17 of the electromagnetic switch 7 by such a process, the present method predicts the near future value Y of the operating coil current A by the PWM control unit 21 by the current prediction process S8, and controls by the PWM control processes S9 to S11 so that the estimated predicted current value Y is not less than the holding current threshold value W, so that the contact pressure of the contact 13 can be stabilized. In addition, the operating coil current A can be reduced to the necessary minimum, the control becomes precise, and the control cycle is correspondingly slowed down.

[0104] The present invention is not limited to the use of battery monitoring in a power supply system using a battery pack as a power source, but can be applied to any other use as long as the switching control of the connection between a power source and a load is performed.

[0105] Description of Reference Numerals

[0106] 1 Electric motor

[0107] 2 Inverter

[0108] 3 Electromagnetic switch control device (this device)

[0109] 4 single battery

[0110] 5 Battery Module

[0111] 6 Battery Pack

[0112] 7 Main contactor (main switch, electromagnetic switch)

[0113] 8 Pre-charge relay (auxiliary switch)

[0114] 9 Pre-charge resistor

[0115] 10 Electromagnetic switch power supply (contactor power supply)

[0116] 11 Microcomputer control unit

[0117] 12 Voltage measurement line

[0118] 13 Contacts

[0119] 14 Switching elements

[0120] 15 Coil current contactor (coil switch, electromagnetic switch)

[0121] 16, 17, 18 Operating coils

[0122] 19 Current value prediction unit

[0123] 20 Control range judgment unit

[0124] 21 PMW control

[0125] 24, 25, 27, 29 Operating coil voltage measurement circuit (ADC)

[0126] 26, 28, 30 Operating coil current measurement circuit

[0127] 31, 32, 33, 34 Filter circuit for voltage measurement (ADC)

[0128] 35, 36, 37 Current measurement filter circuit

[0129] 41, 42 Reflux diode

[0130] A terminal voltage value

[0131] T1 (time constant of current measurement filter circuits 31, 32, 33)

[0132] T2 (time constant of current measurement filter circuits 35 and 36)

[0133] W Holding current (lower limit) threshold

[0134] X Predicted voltage value in the near future

[0135] Y Predicted current value in the near future

[0136] Z impedance.

Claims

1. An electromagnetic switch control device, wherein a current having a current value of a duty cycle controlled by PWM flows through an operating coil and an electric contact is opened and closed by an electromagnetic force corresponding to the current value, the electromagnetic switch control device comprising: a current value prediction unit that estimates a predicted current value after a predetermined period from the present time using the terminal voltage value of the operating coil; a control range determination unit for determining whether the estimated predicted current value is outside a range capable of maintaining the current of the operating coil; and a PWM control unit that, when the determination result of the control range determination unit is outside the range, performs control so as to change the duty ratio based on the predicted current value, The electromagnetic switch control device is used to connect to a battery pack consisting of a plurality of secondary batteries connected in series or in parallel. The battery pack is also connected to: An operating coil voltage measuring circuit for measuring a terminal voltage value of the operating coil; and A voltage measurement filter circuit is provided between the operating coil and the operating coil voltage measurement circuit. The predicted current value is calculated using the terminal voltage value of the operating coil, the impedance of the operating coil, and the time constant of the voltage measurement filter circuit.

2. The electromagnetic switch control device according to claim 1, characterized in that: The impedance is a constant obtained by approximating a transient variable obtained from the terminal voltage value of the operating coil and the current value of the current flowing through the operating coil in a set period up to the present.

3. The electromagnetic switch control device according to claim 2, characterized in that: The constant for approximating the impedance is updated every predetermined period in order to estimate the predicted current value from the present time to a predetermined period after the present time.

4. The electromagnetic switch control device according to claim 1, characterized in that: The battery pack is also connected to: An operating coil current measurement circuit for measuring the current of the operating coil; and A current measurement filter circuit is provided between the operating coil and the operating coil current measurement circuit. The impedance is calculated using the terminal voltage value, the time constant of the voltage measurement filter circuit, the current value, and the time constant of the current measurement filter circuit.

5. The electromagnetic switch control device according to claim 4, characterized in that: The impedance is calculated from the terminal voltage value and the current value of the operating coil during an on-period in which a duty ratio in the PWM control is 100% in order to bring the electrical contacts into a closed state.

6. A method for controlling an electromagnetic switch, wherein a PWM control unit performs PWM control on a current value flowing in an operating coil of the electromagnetic switch, and an electric contact is opened and closed by an electromagnetic force corresponding to the current of the PWM-controlled duty cycle, the method for controlling an electromagnetic switch being characterized by comprising: A voltage and current measurement process of measuring a terminal voltage value and a current value of the operating coil via a voltage measurement filter circuit and a current measurement filter circuit; Current prediction processing for estimating a predicted current value flowing in the operating coil after a specified period from the present time using the terminal voltage value of the operating coil, the impedance of the operating coil and the time constant of the voltage measurement filter circuit; and The PWM control process performs control to change the duty ratio based on the predicted current value when it is determined that the estimated predicted current value is outside a range in which the current of the operation coil can be maintained.

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