Fault tolerant driver circuit

Abstract

One example discloses a driver circuit comprising: a high side element coupled to receive a supply voltage and configured to be coupled to a first end of a load; a low side element coupled to ground and configured to be coupled to a second end of the load; a controller coupled to simultaneously activate both the high side element and the low side element; and a reverse current blocking element coupled between a voltage source and the high side element; wherein the reverse current blocking element is configured to allow current to flow from the voltage source to the high side element and block current to flow from the high side element to the voltage source.

Description

Technical Field

[0001] The present specification relates to systems, methods, devices, apparatus, articles of manufacture, and instructions for driving circuits. Background Art

[0002] In some applications, the actuation of the safety system may be more critical than in others. For example, the internal cell impedance of an electric vehicle battery including lithium-ion cells is very low. In the event of a short circuit, such as at the inverter or motor level, the battery current increases rapidly and creates a fire hazard and potentially irreversible damage to the contactors and / or other battery pack and vehicle components.

[0003] In-line fuses designed to limit this current surge may be too slow to prevent an overcurrent condition that stresses many or all of the battery cells in such a vehicle, and may also overstress the contactors in series with the actuator. Summary of the invention

[0004] According to an example embodiment, a driver circuit includes: a high-side element, which is coupled to receive a supply voltage and is configured to be coupled to a first end of a load; a low-side element, which is coupled to ground and is configured to be coupled to a second end of the load; a controller, which is coupled to simultaneously activate both the high-side element and the low-side element; and a reverse current blocking element, which is coupled between a voltage source and the high-side element; wherein the reverse current blocking element is configured to allow current to flow from the voltage source to the high-side element, and to block current from flowing from the high-side element to the voltage source.

[0005] In another example embodiment, the reverse current blocking element is a diode.

[0006] In another example embodiment, the reverse current blocking element is a MOSFET configured to be controlled by a controller.

[0007] In another example embodiment, the controller is configured to activate the high-side component, the low-side component, and the MOSFET simultaneously.

[0008] In another example embodiment, the high-side element is a first MOSFET; the reverse current blocking element is a second MOSFET; and the first and second MOSFETs are coupled in a back-to-back configuration.

[0009] In another example embodiment, the driver circuit is embedded in a battery management system (BMS) device.

[0010] In another example embodiment, the controller is configured to activate both the high-side component and the low-side component in response to a BMS safety command.

[0011] In another example embodiment, the load is at least one of: an actuator, a pyro-electrical fuse, an igniter, or a squib.

[0012] In another example embodiment, it additionally comprises an energy storage element coupled to the reverse current blocking element and coupled to receive a supply voltage.

[0013] In another example embodiment, the energy storage element is a capacitor.

[0014] In another example embodiment, it further comprises a charging current limiter coupled between the voltage source and the energy storage element.

[0015] In another example embodiment, the charging current limiter is configured to monitor a voltage at the energy storage element.

[0016] In another example embodiment, the charging current limiter is configured to block the charging current received from the supply voltage if the monitored voltage does not reach a predetermined voltage within a predetermined time.

[0017] In another example embodiment, the charging current limiter is configured to output an energy storage element fault signal immediately after blocking the charging current.

[0018] In another example embodiment, a driver system is provided, wherein the driver circuit is a first driver circuit, the reverse current blocking element is a first reverse current blocking element, the voltage source is a first voltage source, and the high-side element is a first high-side element; the driver system further comprises a second driver circuit, the second driver circuit having a second high-side element, the second high-side element being coupled to receive a second supply voltage and being configured to be coupled to a first end of a load; wherein the second driver circuit comprises a second reverse current blocking element, the second reverse current blocking element being configured to allow current to flow from the second voltage source to the second high-side element, and to block current from flowing from the second high-side element to the second voltage source.

[0019] In another example embodiment, the second driver circuit is coupled to the load in parallel with the first driver circuit; and the first driver circuit and the second driver circuit are configured to redundantly drive the load.

[0020] In another example embodiment, the first driver circuit and the second driver circuit are configured to redundantly drive the load in response to a single shared control signal.

[0021] In another example embodiment, at this time the first driver circuit and the second driver circuit are configured to drive the load simultaneously.

[0022] In another example embodiment, the second reverse current blocking element is configured to block current from flowing from the first driver circuit to the second voltage source.

[0023] In another example embodiment, the second voltage source includes an energy storage element; and the second reverse current blocking element is configured to block current flow from the first driver circuit to the energy storage element in the second driver circuit in response to a fault condition in the energy storage element.

[0024] In another example embodiment, the first and second drivers are configured to actuate the load in any order.

[0025] In another example embodiment, the second driver is configured to actuate the load after a certain delay from when the first driver was configured to actuate the load.

[0026] In another example embodiment, there is more than one load actuated by either or both of the first and second drives.

[0027] The above discussion is not intended to represent every example embodiment or every implementation within the scope of current or future claim sets.The figures and the following detailed description also illustrate various example embodiments.

[0028] Various example embodiments may be more fully understood by considering the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A and 1B Shows an example of a drive failure scenario.

[0030] Figure 2 A first example of a fault tolerant driver circuit is shown.

[0031] Figure 3 A second example of a fault tolerant driver circuit is shown.

[0032] Although the present disclosure allows various modifications and alternative forms, the details have been shown in the drawings by way of example and will be described in detail. However, it should be understood that other embodiments beyond the specific embodiments described are also possible. All modifications, equivalents and alternative embodiments falling within the spirit and scope of the appended claims are also encompassed. DETAILED DESCRIPTION

[0033] Pyroelectric switches are an alternative method of quickly blocking current surges. In some embodiments, the pyroelectric switch circuit includes at least two switch drivers having independent circuitry, independent power supplies, and independent energy storage capacitors.

[0034] However, such dual switch drivers may include energy reservoir capacitors (CERs) that may themselves fail. For example, during simultaneous parallel switch driver actuation of the pyroelectric switches, the energy reservoir capacitor of one switch driver channel is shorted and the energy reservoir capacitor of the other switch driver channel is depleted.

[0035] Thus, instead of redundant switch drivers providing additional assurance of actuating the pyroelectric switch, a failure of one of the switch drivers (e.g., failure of its CER) can prevent the other backup switch drivers from actuating the pyroelectric switch, such as when a short circuit in one switch driver consumes driver power (e.g., actuation energy) from the backup switch driver.

[0036] Figure 1A and 1B Examples of driver failure scenarios are shown 100, 102. In both the first example driver failure scenario 100 and the second example driver failure scenario 102, a first driver circuit 104 (e.g., switch driver 1), a second driver circuit 106 (e.g., switch driver 2), and a load 108 (e.g., an actuator, a pyroelectric switch, etc.) are shown.

[0037] In the first driver circuit 104 (e.g., switch driver 1), a first high-side element 110 (e.g., high-side driver 1) is coupled to a first supply voltage 112, a first energy storage element 114 (e.g., CER-1), and a load 108. A first low-side element 116 (e.g., low-side driver 1) is coupled to a first ground 118 (e.g., VPGND1) and the load 108. Both the first high-side element 110 and the first low-side element 116 are coupled to and controlled by a first controller 120 (e.g., controller 1).

[0038] In the second driver circuit 106 (e.g., switch driver 2), a second high-side element 122 (e.g., high-side driver 2) is coupled to a second supply voltage 124, a second energy storage element 126 (e.g., CER-2), and a load 108. A second low-side element 128 (e.g., low-side driver 2) is coupled to a second ground 130 (e.g., VPGND2) and the load 108. Both the second high-side element 122 and the second low-side element 128 are coupled to and controlled by a second controller 132 (e.g., controller 2).

[0039] The switch driver circuits 104, 106 are configured to drive the load 108 simultaneously and in parallel (e.g., to regulate an actuation current across an igniter). In some example embodiments, the first and second driver circuits 104, 106 supplement the power received from the power sources 112, 124 with the charge stored in their energy storage elements 114 (e.g., CER-1) 126 (e.g., CER-2) to further assist in driving the load 108 (e.g., to ignite / actuate a battery management safety squib).

[0040] In both the first example drive failure scenario 100 and the second example drive failure scenario 102, a short circuit 134 in the second energy storage element 126 (eg, CER-2) is shown. In response to this short circuit 134, Figure 1A A first current consumption path 136 is shown, and Figure 1B A second current consumption path 138 is shown.

[0041] For example, in Figure 1A In the embodiment of the present invention, the short circuit 134 disables the second driver circuit 106 by consuming not only the charge stored in the second energy storage element 126 (eg, CER- 2 ) but also the charge received from the second supply voltage 124 .

[0042] In addition, Figure 1B , short circuit 134 also significantly reduces the ability of first driver circuit 104 to drive load 108 (e.g., ignition / actuation battery management safety squib) by consuming charge stored in first energy storage element 114 (e.g., CER-1) and charge received from first supply voltage 112.

[0043] A fault-tolerant driver circuit is now discussed that prevents a fault in a driver circuit from consuming current from other driver circuits coupled to a driven load, such as an actuator, a pyroelectric fuse igniter, a squib, or any other load. The discussed fault-tolerant driver circuit is particularly useful for applications where more than one driver circuit is coupled in parallel to a load and is activated simultaneously in response to a single shared control signal, but may or may not actually be driven simultaneously or after some delay, thereby creating a risk that one or more of the driver circuits may fail and such failure prevents proper actuation of the load.

[0044] A fault-tolerant driver circuit includes a reverse current protection element that enables the driver circuit to prevent a fault in the driver circuit from propagating to other parallel-connected driver circuits.

[0045] Thus, in the event of a short circuit in one or more of the driver circuits, a set of fault-tolerant driver circuits can redundantly drive a load device (e.g., a pyroelectric igniter or anything) using independent energy storage devices / energy sources without compromising the independence of the two energy storage devices / energy sources.

[0046] Figure 2 A first example of a fault-tolerant driver circuit is shown 200. The first example fault-tolerant driver circuit 200 includes a first driver circuit 204 (e.g., switch driver 1) and a second driver circuit 206 (e.g., switch driver 2) coupled in parallel to a load 208 (e.g., an actuator, a squib, an igniter, a pyroelectric switch, etc.).

[0047] The first driver circuit 204 (e.g., switch driver 1) includes a first high-side element 210 (e.g., high-side driver 1), which is coupled to a first reverse current blocking element 211 and a first end of the load 208. The first reverse current blocking element 211 is coupled to a first energy storage element 214 (e.g., CER-1) and a first charging current limiter 215. The first charging current limiter 215 is coupled to a first supply voltage 212. The first driver circuit 204 (e.g., switch driver 1) also includes a first low-side element 216 (e.g., low-side driver 1) coupled between a first ground 218 (e.g., VPGND1) and a second end of the load 208. The first controller 220 (e.g., controller 1) is configured to control the first high-side element 210, the first reverse current blocking element 211, and the first low-side element 216.

[0048] The second driver circuit 206 (e.g., switch driver 2) includes a second high-side element 222 (e.g., high-side driver 2) coupled to a second reverse current blocking element 223 and a first end of the load 208. The second reverse current blocking element 223 is coupled to a second energy storage element 226 (e.g., CER-2) and a second charging current limiter 227. The second charging current limiter 227 is coupled to a second supply voltage 224. The second driver circuit 206 (e.g., switch driver 2) also includes a second low-side element 228 (e.g., low-side driver 2) coupled between a second ground 230 (e.g., VPGND2) and a second end of the load 208. The second controller 232 (e.g., controller 2) is configured to control the second high-side element 222, the second reverse current blocking element 223, and the second low-side element 228.

[0049] The switch driver circuits 204, 206 are configured to drive the load 208 in parallel (e.g., regulate the current sent to an actuator, squib, igniter, pyroelectric switch, etc.). In some example embodiments, the first and second driver circuits 204, 206 supplement the power received from the power sources 212, 224 with the charge stored in their energy storage elements 214 (e.g., CER-1) 226 (e.g., CER-2) to further help drive the load 208.

[0050] The first reverse current blocking element 211 is configured to allow current to flow from the first voltage source 212 to the first high-side element 210, and to block current from flowing from the first high-side element 210 to the first voltage source 212. Similarly, the second reverse current blocking element 223 is configured to allow current to flow from the second voltage source 224 to the second high-side element 222, and to block current from flowing from the second high-side element 222 to the second voltage source 224.

[0051] Thus, if any of the second supply voltage 224 and / or the second energy storage element 226 (e.g., CER-2) fails (e.g., shorts 234), the second reverse current blocking element 223 prevents the forward current 236 from the first driver circuit 204 from becoming a reverse current 238 in the second driver circuit 206, because any such reverse current 238 is now blocked by the second reverse current blocking element 223. The first reverse current blocking element 211 in the first driver circuit 204 operates in the same manner. Thus, the reverse current blocking elements 211, 223 prevent a fault in one driver circuit from draining current from the other driver circuit.

[0052] The first example fault-tolerant driver circuit 200 better ensures that the load 208 is actuated if one or more of the redundant driver circuits 204, 206 fails (e.g., if the energy reservoir capacitor (CER-1 or CER-2) is shorted to ground). This is particularly useful when both the first and second switch driver circuits 204, 206 obtain their actuation energy primarily from the first and second independent energy reservoir capacitors (CER-1, CER-2).

[0053] The reverse current blocking elements 211, 223 in this first example fault-tolerant driver circuit 200 are additional MOSFETs connected in a back-to-back configuration to the first high-side element 210, which is also a MOSFET. The back-to-back transistor topology consists of connecting the sources of the two transistors together to control the current flow forward and backward. This topology prevents unwanted current from flowing through the transistor body diode by adding transistors installed in reverse phase in series. The gate control command is common to the two transistors, so that the current can follow two directions and generate a limited voltage drop or no flow at all.

[0054] The reverse current protection elements 211 , 223 prevent the stray energy reservoir capacitors ( CER- 1 , CER- 2 ) from rapidly discharging via a short circuit in either of the driver circuits 204 , 206 during actuation of the load 208 .

[0055] If any of the energy storage elements 214, 226 (e.g., CER-1, CER-2) is shorted to ground, the charging current limiters 215, 227 prevent the supply voltages 212, 224 from collapsing. This is particularly useful when the supply voltages 212, 224 (VSUPP1, VSUPP2) are connected to a common main supply voltage arrangement.

[0056] In some example embodiments, the charging current limiters 215, 227 monitor the voltage (e.g., VCER1, VCER2) at the energy storage elements 214, 226 (e.g., CER-1, CER-2), respectively. The charging current limiters 215, 227 are configured to block the charging current sent from their respective power supply voltages 212, 224 to the energy storage elements 214, 226 if the monitored voltage (e.g., VCER1, VCER2) does not reach a predetermined voltage within a predetermined charging time. This can be an early indication that one or both of the energy storage elements 214, 226 (e.g., CER-1, CER-2) are defective (e.g., short circuit), and an energy storage element fault signal can be output to indicate this.

[0057] Figure 3 A second example fault tolerant driver circuit 300 is shown. The second example fault tolerant driver circuit 300 is substantially similar to the first example fault tolerant driver circuit 200 except that the first reverse current blocking element 211 is replaced by a first reverse current blocking element 302 and the second reverse current blocking element 223 is replaced by a second reverse current blocking element 304.

[0058] The reverse current blocking elements 302 , 304 in this second example fault tolerant driver circuit 300 are diodes connected in series with the first high-side element 210 .

[0059] Unless a specific order is explicitly stated, the various instructions and / or operational steps discussed in the above figures may be performed in any order. Also, those skilled in the art will recognize that although some example instruction sets / steps have been discussed, the materials in this specification may be combined in a variety of ways to produce other examples and should be understood within the context provided in this detailed description.

[0060] In some example embodiments, these instructions / steps are implemented as functions and software instructions. In other embodiments, the instructions can be implemented using logic gates, dedicated chips, firmware, and other hardware forms.

[0061] It will be readily appreciated that the components of the embodiments as described herein as a whole and illustrated in the accompanying drawings may be arranged and designed in a variety of different configurations. Therefore, the detailed description of the various embodiments as represented in the figures is not intended to limit the scope of the present disclosure, but is merely representative of the various embodiments. Although various aspects of the embodiments are presented in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0062] The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the present invention. The described embodiments should be considered in all respects to be illustrative only and not restrictive. Therefore, the scope of the present invention is indicated by the appended claims rather than by this detailed description. All changes falling within the equivalent meaning and scope of the claims should be included within their scope.

[0063] References throughout this specification to features, advantages, or similar language do not imply that all features and advantages that may be realized using the present invention should be or are in any single embodiment of the present invention. Rather, language referring to features and advantages should be understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of features and advantages and similar language throughout this specification may (but need not) refer to the same embodiment.

[0064] In addition, the described features, advantages and characteristics of the present invention may be combined in one or more embodiments in any suitable manner. Those skilled in the relevant art will recognize that, in view of the description herein, the present invention may be practiced without one or more of the specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be identified in certain embodiments that may not be present in all embodiments of the present invention.

[0065] Reference throughout this specification to "one embodiment," "an embodiment," or similar language means that a particular feature, structure, or characteristic described in connection with the indicated embodiment is included in at least one embodiment of the present invention. Thus, the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may (but do not necessarily) all refer to the same embodiment.

Claims

1. A driver circuit, characterized in that: include: a high-side component coupled to receive a supply voltage and configured to be coupled to a first terminal of a load; a low-side element coupled to ground and configured to be coupled to a second end of the load; a controller coupled to simultaneously activate both the high-side component and the low-side component; as well as a reverse current blocking element coupled between a voltage source and the high-side element; The reverse current blocking element is configured to allow current to flow from the voltage source to the high-side element, and to block current from flowing from the high-side element to the voltage source.

2. The driver circuit according to claim 1: It is characterized in that The reverse current blocking element is a diode.

3. The driver circuit according to claim 1: It is characterized in that The reverse current blocking element is a MOSFET configured to be controlled by the controller.

4. The driver circuit according to claim 3: It is characterized in that The controller is configured to activate the high-side component, the low-side component, and the MOSFET simultaneously.

5. A driver circuit according to any preceding claim: It is characterized in that The high-side component is a first MOSFET; wherein the reverse current blocking element is a second MOSFET; and Wherein the first and second MOSFETs are coupled in a back-to-back configuration.

6. A driver circuit according to any preceding claim: It is characterized in that The driver circuit is embedded in a battery management system (BMS) device.

7. The driver circuit according to claim 6: It is characterized in that The controller is configured to activate both the high-side component and the low-side component in response to a BMS safety command.

8. A driver circuit according to any preceding claim: It is characterized in that The load is at least one of: an actuator, a pyroelectric fuse, an igniter, or a squib.

9. A driver circuit according to any preceding claim, characterised in that: Additionally included is an energy storage element coupled to the reverse current blocking element and coupled to receive the supply voltage.

10. A drive system, characterized in that: include: A driver circuit according to any preceding claim, wherein the driver circuit is a first driver circuit, the reverse current blocking element is a first reverse current blocking element, the voltage source is a first voltage source, and the high-side element is a first high-side element; The driver system additionally includes a second driver circuit having a second high-side element coupled to receive a second supply voltage and configured to be coupled to the first end of the load; The second driver circuit includes a second reverse current blocking element, which is configured to allow current to flow from a second voltage source to the second high-side element and to block current from flowing from the second high-side element to the second voltage source.

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