Relay Control Apparatus, Battery Pack and Electric Vehicle

Abstract

A relay control apparatus for a relay including a contact connected between a positive electrode of a battery and a load, and a coil connected between a relay power terminal and a ground in which the contact moves to a closed position when the coil is energized. The relay control apparatus includes a coil control switch which is turned on in response to a first switching signal having a voltage level that is equal to or higher than a first threshold voltage in response to a relay on-command, and a relay holding circuit configured to store emergency power using power supplied from the battery.

Claims

1. A control system for controlling power flow between a power source and a load over an electrical path, the control system comprising: a primary control circuit configured to output a first control signal for maintaining a relay positioned on the electrical path in a closed state and a second control signal for switching the relay from the closed state to an open state; a backup control circuit operably coupled to the relay and configured to: store emergency power; and upon loss of the first control signal without detection of the second control signal, automatically output a backup control signal to the relay using the stored emergency power within an amount of time that the relay is maintained in the closed state.

2. The control system of claim 1, wherein the backup control circuit is configured to: receive power from the power source; and store the received power as the emergency power.

3. The control system of claim 1, wherein the relay includes a contact and a coil, wherein the contact is configured to move between the open and closed states by a magnetic force generated by the coil, and wherein the primary control circuit is configured to control energization of the coil.

4. The control system of claim 3, wherein the relay is a normally-open relay configured to be in the open state by default and to switch to the closed state only in response to the energization of the coil, and wherein each of the first control signal and the backup control signal is sufficient to maintain the relay in the closed state.

5. The control system of claim 1, wherein the relay is configured to remain in the closed state while a voltage that is greater than or equal to a first threshold value is applied to the relay.

6. The control system of claim 5, wherein the backup control circuit includes a capacitor configured to hold an electrical charge, wherein the capacitor is configured to output the backup control signal using the stored emergency power until a voltage across the capacitor is below the first threshold voltage.

7. The control system of claim 6, wherein backup control circuit further includes an auxiliary switch configured to control charging of the capacitor using the power source.

8. The control system of claim 7, wherein the control system is configured to: receive a user input indicating to change the relay to the closed state; and in response to the user input: output the first control signal; and output an auxiliary control signal to activate the auxiliary switch to initiate charging of the capacitor.

9. The control system of claim 8, wherein the auxiliary switch is a phototransistor, and wherein the auxiliary control signal is an optical signal.

10. A battery pack comprising: the control system of claim 1; and the power source, wherein the power source is a battery.

11. A vehicle comprising: the battery pack of claim 10; and a load, wherein the load includes a motor of the vehicle.

12. A method for controlling power flow between a power source and a load over an electrical path, the method comprising: outputting, by a primary control circuit, a first control signal for maintaining a relay positioned on the electrical path in a closed state and a second control signal for switching the relay from the closed state to an open state; upon loss of the first control signal without detection of the second control signal, automatically outputting, by a backup control circuit operably coupled to the relay, a backup control signal to the relay using stored emergency power within an amount of time that the relay is maintained in the closed state.

13. The method of claim 12, further comprising: receiving power from the power source; and storing the received power as the emergency power.

14. The method of claim 12, wherein the relay includes a contact and a coil, wherein the contact is configured to move between the open and closed states by a magnetic force generated by the coil, and wherein the method further includes controlling, by the primary control circuit, energization of the coil.

15. The method of claim 14, wherein the relay is a normally-open relay that is in the open state by default and switches to the closed state only in response to the energization of the coil, and wherein each of the first control signal and the backup control signal is sufficient to maintain the relay in the closed state.

16. The method of claim 12, wherein the method further includes maintaining the relay in the closed state by applying a voltage that is greater than or equal to a first threshold value to the relay.

17. The method of claim 16, wherein the backup control circuit includes a capacitor configured to hold an electrical charge, wherein the method further includes outputting, by the capacitor, the backup control signal using the stored emergency power until a voltage across the capacitor is below the first threshold voltage.

18. The method of claim 17, wherein backup control circuit further includes an auxiliary switch, and wherein the method further includes controlling, by the auxiliary switch, charging of the capacitor using the power source.

19. The method of claim 18, further comprising: receiving a user input indicating to change the relay to the closed state; and in response to the user input: outputting the first control signal; and outputting an auxiliary control signal to activate the auxiliary switch to initiate charging of the capacitor.

20. The method of claim 19, wherein the auxiliary switch is a phototransistor, and wherein outputting the auxiliary control signal comprising outputting an optical signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings illustrate exemplary embodiments of the present disclosure, and together with the detailed description of the present disclosure as described below, serve to provide a further understanding of the technical aspects of the present disclosure, and thus the present disclosure should not be construed as being limited to the drawings.

[0026] FIG. 1 is a reference diagram illustrating a relay control apparatus according to a first embodiment of the present disclosure.

[0027] FIG. 2 is a reference diagram illustrating a relay control apparatus 100 according to a second embodiment of the present disclosure.

[0028] FIG. 3 is a reference diagram illustrating a relay control apparatus according to a third embodiment of the present disclosure.

[0029] FIG. 4 is a reference diagram illustrating a relay control apparatus according to a fourth embodiment of the present disclosure.

DETAILED DESCRIPTION

[0030] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Prior to the description, it should be understood that the terms or words used in the specification and the appended claims should not be construed as being limited to general and dictionary meanings, but rather interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define the terms appropriately for the best explanation.

[0031] Therefore, the embodiments described herein and the illustrations shown in the drawings are just an exemplary embodiment of the present disclosure, but not intended to fully describe the technical aspects of the present disclosure, so it should be understood that a variety of other equivalents and modifications could have been made thereto at the time that the application was filed.

[0032] The terms including the ordinal number such as first, second and the like, are used to distinguish one element from another among various elements, but not intended to limit the elements.

[0033] Unless the context clearly indicates otherwise, it will be understood that the term comprises when used in this specification, specifies the presence of stated elements, but does not preclude the presence or addition of one or more other elements. Additionally, the term control unit as used herein refers to a processing unit of at least one function or operation, and may be implemented in hardware and software either alone or in combination.

[0034] In addition, throughout the specification, it will be further understood that when an element is referred to as being connected to another element, it can be directly connected to the other element or intervening elements may be present.

[0035] FIG. 1 is a reference diagram illustrating a relay control apparatus according to a first embodiment of the present disclosure, and FIG. 2 is a reference diagram illustrating a relay control apparatus 100 according to a second embodiment of the present disclosure.

[0036] Referring to FIGS. 1 and 2, an electric vehicle 1 includes a battery pack 10 and a load 15. The electric vehicle 1 may further include an auxiliary power supply 18.

[0037] The battery pack 10 may include a battery 20, a relay 30 and the relay control apparatus 100.

[0038] The battery 20 is provided to supply power to the load 15. The battery 20 includes at least one battery cell 21. The battery cell 21 may be, for example, a lithium ion battery cell. The battery cell 21 is not limited to a particular type and may include any battery cell that can be repeatedly recharged.

[0039] The relay 30 is provided to open and close a power supply path between the battery 20 and the load 15. The relay 30 may be a normally open (NO) relay. The relay 30 includes a contact 31 and a coil 32. When the coil 32 is de-energized, the contact 31 moves to an open position. When the coil 32 is energized, the contact 31 moves a closed position.

[0040] The coil 32 is connected between a relay power terminal and a ground. The relay power terminal may be an output terminal P+of the auxiliary power supply 18 or a positive electrode terminal of the battery 20. For the auxiliary power supply 18, for example, a direct current voltage source such as a lead-acid battery may be used. FIG. 1 shows the auxiliary power supply 18 using the output terminal P+for the relay power terminal by way of illustration. When a coil control switch 120 is turned on, the coil 32 is energized by the direct current voltage supplied through the relay power terminal.

[0041] The relay control apparatus 100 includes a control circuit 110, the coil control switch 120 and a relay holding circuit 131.

[0042] The coil control switch 120 is connected between one terminal of the coil 32 and the relay power terminal or between the other terminal of the coil 32 and the ground. For the coil control switch 120, an NPN transistor having a collector, an emitter and a base may be used.

[0043] FIG. 1 shows the coil control switch 120 connected between one terminal of the coil 32 and the relay power terminal, and the coil control switch 120 may be referred to as a high side switch. When the coil control switch 120 is provided as the high side switch, the collector, the emitter and the base of the coil control switch 120 may be connected to the relay power terminal, one terminal of the coil 32 and the control circuit 110, respectively.

[0044] FIG. 2 shows the coil control switch 120 connected between the other terminal of the coil 32 and the ground, and in this case, the coil control switch 120 may be referred to as a low side switch. When the coil control switch 120 is provided as the low side switch, the collector, the emitter and the base of the coil control switch 120 may be connected to the other terminal of the coil 32, the ground and the control circuit 110, respectively.

[0045] The control circuit 110 may be implemented, in hardware, including at least one of application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), microprocessors or electrical units for performing the other functions.

[0046] The control circuit 110 is configured to output a switching signal S1 to the coil control switch 120 in response to a relay on-command. The output of the switching signal S1 by the control circuit 110 may continue until a relay off-command is received. The control circuit 110 stops outputting the switching signal S1 in response to the relay off-command. The relay on-command and the relay off-command may be a signal transmitted from a user input device (not shown) provided in the electric vehicle 1. The user input device may be, for example, an ignition button of the electric vehicle 1.

[0047] The switching signal S1 may be a signal having a voltage level that is equal to or higher than a first threshold voltage. The first threshold voltage may be the minimum voltage necessary to form the base current which induces the turn on of the coil control switch 120. When the switching signal S1 is applied to the base of the coil control switch 120, the coil control switch 120 is turned on. When the coil control switch 120 is turned on, the coil 32 is energized and the contact 31 moves to the closed position.

[0048] The relay holding circuit 131 is configured to store emergency power using the power supplied from the battery 20. The emergency power stored in the relay holding circuit 131 is used to delay the transition of the relay 30 from the closed state to the open state. The relay holding circuit 131 includes a voltage divider 140, a capacitor 150 and an auxiliary switch 160. The relay holding circuit 131 may further include at least one of a diode 180, a diode 190 or a discharge resistor 170.

[0049] The voltage divider 140 is connected between the positive electrode of the battery 20 and the ground. The negative electrode of the battery 20 may be connected to the ground. The voltage divider 140 may be a series circuit of a resistor 141 having a first resistance value and a resistor 142 having a second resistance value. The voltage divider 140 is configured to generate an output voltage that is a fraction of the voltage across the battery 20 divided at a predetermined ratio. For example, when the first resistance value is 9 times larger than the second resistance value, 9/10 of the battery voltage is applied across the resistor 141, and 1/10 of the battery voltage is applied across the resistor 142. The output voltage of the voltage divider 140 refers to the voltage across the resistor 142.

[0050] The capacitor 150 is charged by the battery 20 to store emergency power. One terminal of the capacitor 150 is connected to the ground, and the other terminal of the capacitor 150 is connected to an output node 143 of the voltage divider 140 through the auxiliary switch 160. The output node 143 of the voltage divider 140 may be a connection node of the resistor 141 and the resistor 142. When the voltage of the emergency power stored in the capacitor 150 is higher than the first threshold voltage, the capacitor 150 outputs the switching signal S1 together with the control circuit 110 or instead of the control circuit 110 using the emergency power stored in the capacitor 150 until the voltage across the capacitor 150 is reduced below the first threshold voltage.

[0051] The auxiliary switch 160 is connected between the voltage divider 140 and the other terminal of the capacitor 150, and opens and closes the power supply path between the output node 143 of the voltage divider 140 and the capacitor 150. For a first protection switch, an NPN transistor having a collector, an emitter and a base may be used. The collector, the emitter and the base of the auxiliary switch 160 may be connected to the output node 143 of the voltage divider 140, the other terminal of the capacitor 150 and the control circuit 110, respectively.

[0052] The control circuit 110 is configured to output a switching signal S2 to the base of the auxiliary switch 160 independently of the switching signal S1. The control circuit 110 may output the switching signal S2 having a predetermined duty ratio (for example, 39%) for a predetermined time in response to the relay on-command. The switching signal S2 is a signal having a voltage level that is equal to or higher than a second threshold voltage. The second threshold voltage may be the minimum voltage necessary to form the base current which induces the turn on of the first protection switch. When the switching signal S2 is applied to the base of the auxiliary switch 160, the first protection switch is turned on.

[0053] The diode 180 is connected between the control circuit 110 and the coil control switch 120. An anode of the diode 180 may be connected to the control circuit 110, and a cathode of the diode 180 may be connected to the base of the coil control switch 120. The diode 180 serves as a delivery path of the switching signal S1 from the control circuit 110 to the coil control switch 120.

[0054] The diode 190 is connected between the capacitor 150 and the coil control switch 120. An anode of the diode 190 may be connected to the other terminal of the capacitor 150, and a cathode of the diode 190 may be connected to the base of the coil control switch 120. The diode 190 serves as a delivery path of the switching signal S1 from the capacitor 150 to the coil control switch 120.

[0055] The discharge resistor 170 is connected between the base and the emitter of the coil control switch 120. The discharge resistor 170 is provided to discharge the capacitor 150. The duration of the output switching signal S1 of the capacitor 150 relies on a time constant which is equal to the product of the multiplication of the voltage of the capacitor 150, the resistance value of the discharge resistor 170 and the capacitance of the capacitor 150.

[0056] FIG. 3 is a reference diagram illustrating a relay control apparatus according to a third embodiment of the present disclosure. Although FIG. 3 shows the coil control switch 120 used as the high side switch (see FIG. 1) for convenience of description, the coil control switch 120 may be used as the low side switch (sec FIG. 2).

[0057] A relay holding circuit 133 of the relay control apparatus 100 according to the third embodiment of the present disclosure is identical to the first embodiment except that the control circuit 110 does not output the switching signal S2, and instead, outputs the switching signal S1 to store emergency power in the capacitor 150, a light emitting diode 181 is used as the diode 180, a photo transistor 161 is used as the auxiliary switch 160, and a signal delivery path between the control circuit 110 and the photo transistor 161 is removed. The following description is made based on difference(s) between this embodiment and the first embodiment.

[0058] Referring to FIG. 3, when the control circuit 110 outputs the switching signal S1, in the same way as the first embodiment, the coil control switch 120 is turned on by the switching signal S1. At the same time, the forward voltage by the switching signal S1 is applied across the diode 181, and an optical signal 182 is outputted from the diode 181. When the optical signal 182 is received at the base of the photo transistor 161, the photo transistor 161 is turned on. When the photo transistor 161 is turned on, a charging path from the voltage divider 140 to the capacitor 150 is provided.

[0059] According to the third embodiment, energization of the coil 32 and charging of the capacitor 150 is simultaneously carried out by the output of the switching signal S1 by the control circuit 110. As a result, it is possible to reduce the power consumption required to output the switching signal S2 and reduce the circuit complexity.

[0060] FIG. 3 is a reference diagram illustrating a relay control apparatus according to a fourth embodiment of the present disclosure. Although FIG. 4 shows the coil control switch 120 used as the high side switch (see FIG. 1) for convenience of description, the coil control switch 120 may be used as the low side switch (see FIG. 2).

[0061] A relay holding circuit 134 of the relay control apparatus 100 according to the fourth embodiment is identical to the first embodiment except that the relay holding circuit 134 is configured to output the switching signal S1 instead of the control circuit 110 only when an abnormal loss of the switching signal S1 from the control circuit 110 occurs. The following description is made based on difference(s) between this embodiment and the first embodiment.

[0062] Referring to FIG. 4, the relay holding circuit 134 of the relay control apparatus 100 according to the fourth embodiment further includes an auxiliary switch 201 and a pull-down resistor 202.

[0063] For the auxiliary switch 201, a PNP transistor having a collector, an emitter and a base may be used. The collector, the emitter and the base of the auxiliary switch 201 may be connected to the other terminal of the capacitor 150, the base of the coil control switch 120 and the control circuit 110, respectively.

[0064] The pull-down resistor 202 is connected between the base of the auxiliary switch 201 and the ground.

[0065] During normal operation, the control circuit 110 outputs a switching signal S3 having a voltage level that is equal to or higher than a third threshold voltage to the base of the auxiliary switch 201. The third threshold voltage may be the minimum voltage necessary to shut off the base current which induces the turn on of the auxiliary switch 201. When the switching signal S3 is applied to the base of the auxiliary switch 201, the auxiliary switch 201 is turned off.

[0066] Accordingly, when the control circuit 110 normally stops outputting the switching signal S1, the capacitor 150 is electrically separated from the coil control switch 120 by the switching signal S3, and thus the relay 30 may immediately move from the closed state to the open state.

[0067] In contrast, in case that the control circuit 110 is malfunctioning (for example, power off), the switching signal S1 and the switching signal S2 as well as the switching signal S3 is not outputted from the control circuit 110. In this case, the voltage of 0 V is applied to the base of the auxiliary switch 201 connected to the ground through the pull-down resistor 202, and the auxiliary switch 201 is turned on. As a result, in case that the output of the switching signal S1 by the control circuit 110 is suddenly stopped due to the malfunction of the control circuit 110 while the relay 30 is being controlled into the closed state, the coil 32 temporarily stays energized by the switching signal S1 immediately outputted from the relay holding circuit 134, and the transition of the relay 30 from the closed state to the open state is delayed.

[0068] When the control circuit 110 normally stops outputting the switching signal S1 in response to the relay off-command, the relay control apparatus 100 according to the fourth embodiment may block the signal path from the relay holding circuit 131 to the coil control switch 120 to avoid unnecessary delay in the transition of the relay 30 from the closed state to the open state.

[0069] While the present disclosure has been hereinabove described with regard to a limited number of embodiments and drawings, the present disclosure is not limited thereto and it is obvious to those skilled in the art that a variety of modifications and changes may be made thereto within the technical aspects of the present disclosure and the scope of the appended claims and equivalents thereof.

[0070] Additionally, as many substitutions, modifications and changes may be made to the present disclosure described hereinabove by those skilled in the art without departing from the technical aspects of the present disclosure, the present disclosure is not limited by the above-described embodiments and the accompanying drawings, and all or some of the embodiments may be selectively combined to allow various modifications.

Description of Reference Numerals

[0071] 1: Electric vehicle [0072] 10: Battery pack [0073] 15: Load [0074] 20: Battery [0075] 30: Relay [0076] 100: Relay control apparatus [0077] 110: Control circuit [0078] 120: Coil control switch [0079] 131, 132, 133, 134: Relay holding circuit