High voltage circuit and method for controlling a contactor in an electric vehicle

Abstract

A control circuit and method for controlling a contactor in a vehicle. The control circuit includes a driver circuit having an output coupled to a control terminal of a contactor, the driver circuit having a power input and a control input. A Boolean logic gate has an input coupled to a safety disable control signal, a second input, and an output coupled to the control input of the driver circuit. A hold circuit has a first input coupled to a propulsion loss signal, a second input coupled to a pulse width modulated (PWM) control signal, and an output coupled to the second input of the Boolean logic gate. Based on the output of the propulsion loss detection circuit, the output of an output latch circuit is maintained at a previous Boolean logic state of the output of the output latch circuit or based on the PWM control signal.

Description

Technical Field

[0001] The present invention generally relates to a control circuit system for a contactor, and more particularly to a control circuit system for a contactor in an electric vehicle. Background Technology

[0002] Current technology in electric vehicles requires systems with two or more switching elements, commonly referred to as "contaminants." These contactors open or close as needed by the high-voltage electrical circuits responsible for vehicle propulsion. Historically, these contactors have been controlled by electronic modules using different combinations of high-side drivers (HSDs) or low-side drivers (LSDs), such as ON / OFF HSDs, pulse-width modulation (PWM) LSDs, PWM HSDs, ON / OFF LSDs, single HSDs, or single LSDs. Regardless of the HSD-LSD combination used, a common characteristic is that the drivers are directly controlled by the system's main microcontroller. In the event of loss of the main microcontroller, the nature of this circuitry is to immediately disable the contactor drivers and move the system to a safe state, which includes disconnecting contactor 7.

[0003] Figure 1 illustrates a conventional control device and / or control module 1 for controlling one or more contactors positioned between a high-voltage source and a high-voltage load, where the high-voltage load is the propulsion system of an electric vehicle or a hybrid electric vehicle. The control device 1 includes a driver circuit 3, illustrated as a high-side driver circuit, which generates a control signal 5 connected to the control terminal of the contactor 7. The driver circuit 3 is powered by the battery supply voltage Vbatt. A safety gate, implemented in this case as an AND gate, receives a thrust loss signal 207, a safety disable signal 209, and a pulse width modulation (PWM) control signal 205 as inputs from a microcontroller (not shown) operatively associated with the control device 1. The thrust loss signal 207 is generated by a device other than the main microcontroller controlling the contactor 7 and can be enabled (asserted) in response to the detection of thrust loss in the vehicle or an unexpected reset of the main microcontroller. A safety disable signal 209, generated by a redundant secondary monitoring device / microcontroller or the main microcontroller controlling the contactor, is used to control the driver circuit 3 and immediately disconnect the contactor 7, thereby electrically isolating the high-voltage source from the high-voltage load. This can occur in the event of a microcontroller power failure or otherwise loss of control over the contactor 7. The PWM control signal 205 is provided by the main microcontroller during normal operation.

[0004] Disconnecting contactor 7 in response to a fault avoids further hazards typically assessed as up to Automotive Safety Integrity Level D (ASIL-D). However, there are fault scenarios where uncommanded and / or accidental disconnection of contactor 7 could lead to an unsafe condition in an electric vehicle or hybrid electric vehicle. Specifically, disconnecting contactor 7 could result in an unexpected loss of propulsion, which could be dangerous at high speeds. Depending on the specific circumstances considered by the vehicle manufacturer in its Hazard Analysis and Risk Assessment (HARA), this scenario could be assessed as up to ASIL-D. Therefore, in electric vehicles, the safety objective of “avoiding unexpected loss of propulsion” can be found. This safety objective of avoiding unexpected loss of propulsion may conflict with other safety objectives of the electric vehicle's control system that require immediate disconnection of contactor 7 in the event of a fault. Summary of the Invention

[0005] Exemplary embodiments of this disclosure overcome the drawbacks of existing electric vehicle control systems by reconciling the potential danger of unintended propulsion loss with the need to disconnect contactor 7 in response to system failure. In one exemplary embodiment, a control circuit for a contactor in an electric vehicle is disclosed, comprising: a driver circuit having an output coupled to a control terminal of at least one contactor, the driver circuit having a power input and a control input; and a Boolean logic gate having an input coupled to a safety disable control signal, a second input, and an output coupled to the control input of the driver circuit. A holding circuit has a first input coupled to a propulsion loss signal, a second input coupled to a PWM control signal, and an output coupled to the second input of the Boolean logic gate.

[0006] In one embodiment, the holding circuit includes a thrust loss detection circuit having an output and an input coupled to the first input of the holding circuit. The holding circuit also includes an output latch circuit having a first input coupled to the output of the thrust loss detection circuit and an output coupled to the second input of the Boolean logic gate. In one aspect, the thrust loss detection circuit includes a monostable multivibrator circuit that generates a pulse output having a predetermined duration, the pulse output being a response to a trigger edge of the thrust loss signal. In another aspect, the monostable multivibrator circuit includes a retriggable monostable multivibrator circuit.

[0007] In one embodiment, the propulsion loss detection circuit includes at least two discrete electrical or electronic components coupled to the monostable multivibrator circuit, and the predetermined duration is based on the characteristic values ​​of the at least two discrete electrical or electronic components.

[0008] The output latch circuit includes a multiplexer circuit having a first selection input coupled to the output of the thrust loss detection circuit, a second selection input of the logic complement of the output of the thrust loss detection circuit coupled to the output of the multiplexer circuit, a first data input coupled to the output of the multiplexer circuit, and a second data input coupled to the PWM control signal, wherein the output of the multiplexer circuit is the output of the output latch circuit. When the first selection input is in a first logic state, the first data input of the multiplexer circuit is coupled to its output, and when the second selection input is in the first logic state, the output of the multiplexer circuit is based on the PWM control signal. Based on the output of the thrust loss detection circuit, the output of the output latch circuit maintains either a previous Boolean logic state of the output of the output latch circuit or based on the PWM control signal.

[0009] In one exemplary embodiment, the holding circuit includes a second latch circuit having a first input corresponding to the first input of the holding circuit, a second input coupled to the first control signal, and an output corresponding to the output of the holding circuit. The output of the second latch is held in a first Boolean logic state in response to the thrust loss signal and is in a second Boolean logic state in response to the first control signal. In one aspect, the second latch circuit includes a D-type flip-flop circuit having a set input and a data input coupled to a power supply voltage, a clock input coupled to the thrust loss signal, and a reset input coupled to the first control signal.

[0010] The contactor is connected between the high-voltage source and the high-voltage load in the electric vehicle.

[0011] In another embodiment, a method for controlling a contactor disposed between a high-voltage source and a high-voltage load in an electric vehicle is disclosed. The method includes: sensing whether a throttle loss signal indicates a throttle loss event is occurring; generating a first control signal in response to the throttle loss signal; and generating a latched output signal for controlling the contactor based on a logic state of the first control signal and a logic state of a PWM control signal.

[0012] The first control signal includes a pulse having a predetermined pulse width, and generating the first control signal includes generating the pulse in response to a trigger edge of the thrust loss signal.

[0013] Generating the latched output signal includes latching the latched output signal when the first control signal is in a first Boolean logic state, and generating the PWM control signal as the latched output signal when the first control signal is in a second Boolean logic state. Generating the latched output signal also includes multiplexing the latched output signal at the latched output signal level when the first control signal is in the first Boolean logic state, and multiplexing the PWM control signal when the first control signal is in the second Boolean logic state.

[0014] Generating the first control signal includes generating the first control signal as a latched control signal, wherein the latched control signal changes its logic state when the control input signal is in a first logic state and does not change when the control input signal is in a second logic state. Attached Figure Description

[0015] The aspects of the invention will now be explained in detail with reference to the accompanying drawings and exemplary embodiments, in which:

[0016] Figure 1 is a simplified block diagram of a conventional control device for controlling a contactor located between a high-voltage source and a high-voltage load.

[0017] Figure 2 This is a simplified block diagram of a control device for controlling a contactor disposed between a high-voltage source and a high-voltage load, according to an exemplary embodiment.

[0018] Figure 3 According to an exemplary embodiment Figure 2 A schematic diagram of the holding circuit of the control device: and

[0019] Figure 4 According to another exemplary embodiment Figure 2 A schematic diagram of the holding circuit of the control device. Detailed Implementation

[0020] The following description of exemplary embodiments is merely illustrative in nature and is in no way intended to limit the invention, its application, or its uses. In the drawings and throughout the detailed description, the same reference numerals are used to identify the same or similar elements. For clarity, unless otherwise stated, the elements are not shown to scale.

[0021] The exemplary embodiments generally relate to coordinating the response of a contactor in a high-voltage system for electric vehicles to disconnect due to a fault (such as a microcontroller failure) and the danger of loss of propulsion caused by the disconnection of the contactor when the vehicle is traveling at high speed. Generally, the exemplary embodiments provide an electronic solution capable of maintaining the contactor's previous state for a time period to avoid unexpected loss of propulsion in the system without affecting the normal operation of the contactor in emergency situations. This advantageously results in delaying any unexpected loss of propulsion, allowing the system, among other things, to alert the vehicle driver to the loss of propulsion before it actually occurs.

[0022] Figure 2 The diagram illustrates a control device or system 200 according to an exemplary embodiment. The control device 200 may form at least a portion of a control module for an electric vehicle. The control device 200 provides a control signal 202 that controls the state of a contactor 7. In this embodiment, the contactor 7 is positioned between a high-voltage source 9 (a group of batteries, the combination of which provides a high voltage) and a high-voltage load 11 (such as the propulsion system of an electric vehicle). The contactor 7 may be one of a plurality of contactors used in association with the high-voltage source 9 and / or the high-voltage load 11; in this case, the contactor 7 may represent a plurality of contactors 7.

[0023] The control device 200 includes a driver circuit 3 for generating control signals 202. In the illustrated embodiment, the driver circuit 3 is a high-side driver circuit; however, it should be understood that the driver circuit 3 can have any of many different topologies, as discussed above. The diagnostic block 13 provides feedback to other modules within the vehicle control system regarding the control of the contactor 7.

[0024] The control device 200 further includes a holding circuit 204 that receives a PWM control signal 205 generated and transmitted by the microcontroller 206 of the electric vehicle, and a thrust loss signal 207 generated during a fault or impending fault, such as in response to the detection of a thrust loss or impending thrust loss in the electric vehicle or hybrid electric vehicle. In the illustrated embodiment, the thrust loss signal 207 is generated by a device other than the microcontroller 206 and can be enabled in response to an unexpected reset of the microcontroller 206. The holding circuit 204 generates an output signal applied to safety logic 208, which is implemented as an AND gate. The safety logic 208 also receives a safety disable signal 209 for disabling contactor 7. In this embodiment, the safety disable signal 209 is generated by a separate (relative to microcontroller 206) monitoring device, monitor timer circuit, or other secondary monitoring device (not shown). The safety disable signal 209 controls the driver circuit 3 and immediately disconnects contactor 7, thereby electrically isolating the high-voltage source 9 from the high-voltage load 11.

[0025] Microcontroller 206 includes one or more processor cores and volatile and non-volatile memory that can store program code as instructions that, when executed by the one or more processor cores, cause microcontroller 206 to perform certain operations, in this case, including controlling one or more contactors 7. Control of the contactors 7 can form part of microcontroller 26 controlling a high-voltage load 11 (e.g., a vehicle's propulsion system). It should be understood that microcontroller 206 can include any number of different microcontroller architectures. Memory can be embedded in microcontroller 206, external to microcontroller 206, or both. In alternative embodiments, microcontroller 206 is implemented as a field-programmable gate array (FPGA) or a state machine-based circuit.

[0026] Holding circuit 204 receives thrust loss signal 207 and PWM control signal 205 from microcontroller 206, and generates an output signal at the output of holding circuit 204 that delays the propagation of thrust loss signal 207 to safety logic 208. In this exemplary embodiment, the delay amount is predetermined and configured to alert the vehicle driver to an impending interruption of vehicle propulsion, allowing the driver to take appropriate action before the interruption occurs, thereby avoiding a potentially dangerous situation.

[0027] Figure 3An embodiment of a holding circuit 204 according to an exemplary embodiment is illustrated. The holding circuit 204 includes a thrust loss detection circuit 220 that detects the trigger edge of a digital thrust loss signal 207 and generates a pulse as an output signal 222 and a logical complement (inverse) output signal 224. The thrust loss detection circuit 220 operates as a monostable multivibrator and / or "one-shot," generating a pulse in response to the trigger edge of its input. The illustrated embodiment of the thrust loss detection circuit 220 uses a retriggable monostable multivibrator having part number 74HC4538 and manufactured, for example, by Texas Instruments (part number CD74HC4538). In this embodiment, the duration of the generated pulse is based on a time constant calculated through the product of the resistance (characteristic value) of resistor 226 and the capacitance (characteristic value) of capacitor 228, and specifically based on 0.7 of this product. It should be understood that the duration of the pulse generated by the thrust loss detection circuit 220 can be varied based on system requirements by changing the capacitance and / or resistance of capacitor 228 and resistor 226, respectively. It should be further understood that the thrust loss detection circuit 220 can have different implementations and utilize different parts and electrical or electronic components.

[0028] Continue to refer to Figure 3The holding circuit 204 further includes an output latch circuit 230, which is configured to maintain its current latched state upon receiving a pulse generated from the thrust loss detection circuit 220, and to output a signal based on a PWM control signal 205 generated by the microcontroller 206 when no pulse is generated from the thrust loss detection circuit 220. The illustrated embodiment of the output latch circuit 230 is a multiplexer circuit, wherein either the output of the output latch circuit 230 is selected and fed back and passed to an output, or the PWM control signal 205 is selected and passed to the output of the output latch circuit 230. The selection of the fed-back output signal or the PWM control signal 205 is made by output signals 222, 224 generated by the thrust loss detection circuit 220. In this embodiment, a specific embodiment of the output latch circuit 230 includes two AND gates 232, 234 and a OR gate 236. AND gate 232 receives the output signal 222 generated by the thrust loss detection circuit 220 and the output of the output latch circuit 230 as its inputs. AND gate 234 receives the output signal 224 generated by the thrust loss detection circuit 220 and the PWM control signal 205 at its inputs. The outputs of AND gates 232 and 234 are connected to the input of OR gate 236. The output of OR gate 236 drives the output of the output latch circuit 230.

[0029] As can be seen, when the pulse generated at output signal 222 by the thrust loss detection circuit 220 is enabled (i.e., becomes logic high or "1"), the output of output latch circuit 230 is fed back and propagates through AND gate 232 and OR gate 236. This keeps output latch circuit 230 in a latched state, where the output remains in its current state. During this time, output signal 224 is disabled (de-asserted) (i.e., becomes logic low or "0"), which causes AND gate 234 to output a logic low or "0", thus having no effect on the output of OR gate 236.

[0030] Conversely, when no pulse appears on output signal 222 (i.e., it is in a logic low or "0" state), the output of AND gate 232 is in a logic low or "0" state, so that it has no effect on the output of OR gate 236. During this period when there is no pulse generated by the thrust loss detection circuit 220, output signal 224 is driven to a logic high or "1" value, which allows PWM control signal 205 to propagate through AND gate 234 and OR gate 236 to the output of output latch circuit 230. Therefore, when thrust loss signal 207 is enabled, holding circuit 204 maintains its current output for a predetermined time period. Only after the predetermined time period has elapsed can microcontroller 206 control the state of contactor 7 via PWM control signal 205.

[0031] In the event of losing the microcontroller 206 Figure 3 The holding circuit 204 advantageously sets a hardware holding time limit for controlling (i.e., cutting off or disconnecting) the contactor 7. Compared to other solutions based on the RC delay of the PWM control signal 205, the contactor 7 can be cut off / disconnected if the microcontroller 206 does not return to its operating state before the pulse time expires and if other conditions do not affect the normal operation of the contactor 7, which only moves the system to a safe state after alerting the vehicle driver.

[0032] Figure 4 An embodiment of a holding circuit 204' according to a second exemplary embodiment is shown, which includes a thrust loss detection circuit 220' and an output latch circuit 230. The thrust loss detection circuit 220' operates as a latch circuit. In one embodiment, the thrust loss detection circuit 220' is a D-type flip-flop circuit 320, such as a flip-flop part 74HC74, configured to operate as a latch circuit by connecting a clock input (CLK) to the thrust loss signal 207, connecting a data input (D) and a set input (SD) to Vcc and / or a logic high or "1" state, and connecting a reset input (RD) to a control signal 240, the reset input initializing and / or reinitializing the D-type flip-flop circuit 320 to a known state. Once the flip-flop circuit 320 is triggered by the rising edge of the thrust loss signal 207, the output signals 322 and (two's complement) 324 are toggled. The trigger circuit 320 remains in its latched state until the microcontroller 206 that generates the control signal 240 drives the control signal 240 to a logic low or "0" state. At this time, the output 322 is driven to a logic low state and the output 324 is driven to a logic high state.

[0033] Figure 4 The output latch circuit 230 of the holding circuit 204' and the holding circuit 204' Figure 3The output latch circuit 230 of the holding circuit 204 has the same implementation.

[0034] In operation, when the thrust loss signal 207 is enabled (i.e., transitions from a logic low to a logic high) and the control signal 240 is at a logic high, the output signal 322 is driven to a logic high, and the (two's complement) output signal 324 is driven to a logic low. This causes the output of the output latch circuit 230 to be fed back and propagated through the AND gate 232 and the OR gate 236 to the output of the output latch circuit 230, thereby causing a delay in the thrust loss signal 207 to avoid affecting the control of the contactor 7 to disconnect it. The output of the output latch circuit 230 remains in this state until the control signal 240 resets the trigger 320 (by transitioning from a logic high to a logic low), which causes output 322 to be driven to a logic low and output 324 to be driven to a logic high. At this time, the PWM control signal 205 can propagate through the AND gate 234 and the OR gate 236 to control the contactor 7.

[0035] exist Figure 4 In the embodiment of the holding circuit 204' shown, there is no element as described in Figure 3 When the holding circuit 204 is in operation, the output of the output latch circuit 230 is latched and / or maintained in its current state for a programmed delay period, as discussed above. The holding circuit 204 has a predetermined delay duration set in hardware (capacitor 228 and resistor 226). The absence of a predetermined delay period in the operation of the holding circuit 204' is because this predetermined delay period is experienced during the timing of the control signal 240 transitioning from a logic high state to a logic low state via the microcontroller 206 relative to the rising edge of the propulsion loss signal 207. Figure 4 The holding circuit 204' requires intervention from the microcontroller 206 to take back control of the output of the holding circuit 204' (and therefore control of the contactor 7). This is convenient because the microcontroller 206 can postpone the loss of propulsion force for a longer (or varying) time period until the microcontroller 206 takes back control to actively control the state of the contactor 7.

[0036] Exemplary embodiments have been described herein in an illustrative manner, and it should be understood that the terminology used is intended to be descriptive rather than restrictive. Clearly, many modifications and variations of the invention are possible in light of the above teachings. The above description is essentially exemplary only, and therefore, changes can be made to the above description without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A control circuit for a contactor in an electric vehicle, comprising: A driver circuit having an output coupled to a control terminal of a contactor, the driver circuit having a power input and a control input; A logic gate having an input coupled to a security disable control signal, a second input, and an output coupled to the control input of the driver circuit; as well as A holding circuit having a first input coupled to a propulsion loss signal, a second input coupled to a pulse width modulation (PWM) control signal, and an output coupled to the second input of the logic gate. The holding circuit receives the thrust loss signal and the pulse width modulation control signal from the microcontroller, and generates an output signal at the output of the holding circuit that delays the propagation of the thrust loss signal to the logic gate.

2. The control circuit according to claim 1, wherein the holding circuit includes a thrust loss detection circuit and an output latch circuit, the thrust loss detection circuit having an output and an input coupled to the first input of the holding circuit, and the output latch circuit having a first input coupled to the output of the thrust loss detection circuit and an output coupled to the second input of the logic gate.

3. The control circuit according to claim 2, wherein the thrust loss detection circuit includes a monostable multivibrator circuit, the monostable multivibrator circuit generating a pulse output having a predetermined duration, the pulse output being a response to the trigger edge of the thrust loss signal.

4. The control circuit according to claim 3, wherein the monostable multivibrator circuit includes a retriggable monostable multivibrator circuit.

5. The control circuit of claim 3, wherein the propulsion loss detection circuit comprises at least two discrete electrical or electronic components coupled to the monostable multivibrator circuit, and the predetermined duration is based on the characteristic values ​​of the at least two discrete electrical or electronic components.

6. The control circuit according to claim 2, wherein the output latch circuit includes a multiplexer circuit having a first selection input coupled to the output of the thrust loss detection circuit, a second selection input of the logic complement of the output of the thrust loss detection circuit coupled to the output of the multiplexer circuit, a first data input coupled to the output of the multiplexer circuit, and a second data input coupled to the PWM control signal, wherein the output of the multiplexer circuit includes the output of the output latch circuit.

7. The control circuit of claim 6, wherein when the first selection input is in the first logic state, the first data input of the multiplexer circuit is coupled to its output, and when the second selection input is in the first logic state, the output of the multiplexer circuit includes the PWM control signal.

8. The control circuit of claim 2, wherein, based on the output of the thrust loss detection circuit, the output of the output latch circuit is maintained at a previous logic state of the output of the output latch circuit or based on the PWM control signal.

9. The control circuit of claim 2, wherein the thrust loss detection circuit includes a second latch circuit having a first input corresponding to the first input of the holding circuit, a second input coupled to a control signal, and an output corresponding to the output of the thrust loss detection circuit, wherein the output of the second latch circuit is held in a first logic state in response to the thrust loss signal and is in a second logic state in response to the control signal.

10. The control circuit of claim 9, wherein the second latch circuit comprises a D-type flip-flop circuit having a setting input and a data input coupled to a power supply voltage, a clock input coupled to the propulsion loss signal, and a reset input coupled to the control signal.

11. The control circuit according to claim 1, wherein the contactor is connected between a high-voltage source and a high-voltage load in the electric vehicle.

12. A method for controlling a contactor disposed between a high-voltage source and a high-voltage load in an electric vehicle, comprising: Whether the sensing thrust loss signal indicates that a thrust loss event is occurring; A first control signal is generated in response to the propulsion loss signal; as well as Based on the logic state of the first control signal and the logic state of the pulse width modulation (PWM) control signal, a latched output signal for controlling the contactor is generated, which delays the propagation of the thrust loss signal to the logic gate.

13. The method of claim 12, wherein the first control signal comprises a pulse having a predetermined pulse width, and generating the first control signal comprises generating the pulse in response to a trigger edge of the thrust loss signal.

14. The method of claim 12, wherein generating the latched output signal comprises latching the latched output signal when the first control signal is in a first logic state, and generating the PWM control signal as the latched output signal when the first control signal is in a second logic state.

15. The method of claim 12, wherein generating the latched output signal comprises multiplexing the latched output signal at the latched output signal when the first control signal is in a first logic state, and multiplexing the PWM control signal when the first control signal is in a second logic state.

16. The method of claim 15, wherein generating the first control signal comprises generating the first control signal as a latched control signal, the latched control signal changing its logic state when the control input signal is in a first logic state and not changing when the control input signal is in a second logic state.

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