Overvoltage protection circuit and method of overvoltage protection

Abstract

In electronic systems such as electric vehicles, destructive overvoltages can occur very rapidly without warning, requiring a fast response to protect the system. In some embodiments described herein, hardware-based protection circuitry can be used to protect electronic systems from overvoltages. The protection circuitry may include a dissipative resistor, a switch for connecting the resistor to a bus in the electronic system, and hardware control circuitry configured to monitor the bus voltage amplitude. If the control circuitry detects that the bus voltage amplitude exceeds an overvoltage threshold, it may cause the switch to connect the resistor to the bus to dissipate energy in the bus. Then, after a minimum time, if the bus voltage amplitude has dropped below the overvoltage threshold, the hardware control circuitry may cause the switch to disconnect the resistor from the bus.

Description

Technical Field

[0001] This disclosure generally relates to the protection of electronic systems, such as those in electric vehicles, from overvoltage. Background Technology

[0002] Overvoltage occurs when the voltage in an electronic system exceeds its design value. This can damage components of the electronic system. For example, in electric vehicles, the back electromotive force (back EMF) generated by the vehicle's electric motor can cause damaging overvoltages in some cases. Summary of the Invention

[0003] Electric vehicles may include a traction battery and an electric motor connected by a high-voltage bus. During operation, electricity can flow between the battery and the electric motor via the bus. For example, during propulsion, the battery can supply power to the electric motor, while during regenerative braking, the electric motor can act as a generator and provide power to recharge the battery. However, in certain situations, the electric motor can generate a back EMF sufficient to cause a considerable overvoltage in the bus. For example, if the vehicle is moving at a high speed and the battery fails or is otherwise disconnected, a back EMF can generate an overvoltage. As another example, if the vehicle is being towed at too high a speed, a back EMF can generate an overvoltage. In this case, the bus voltage can rise rapidly to a level that can damage the power electronics connected to the bus. In these situations, known overvoltage protection systems may not respond quickly enough to mitigate the damage. Known overvoltage protection systems may also not account for the repeated overvoltages caused by persistent back EMF, resulting in the bus voltage oscillating between overvoltage and normal operating levels.

[0004] In some embodiments described herein, hardware-based protection circuitry can be used to protect electronic systems, such as those in electric vehicles, from overvoltage. Hardware-based protection circuitry (e.g., compared to software control) can provide faster response times, and in some embodiments, it can implement time delays (e.g., via timing circuitry) to prevent voltage oscillations. An example is given below. The protection circuitry includes a dissipative resistor, a switch, and hardware control circuitry. The switch can be engaged to connect the dissipative resistor to the bus of the electronic system to dissipate energy in the bus—e.g., reduce overvoltage in the bus. The hardware control circuitry monitors the magnitude of the bus voltage in the bus. If the magnitude of the bus voltage exceeds an overvoltage threshold, the hardware control circuitry outputs a signal to cause the switch to connect the resistor to the bus. The hardware control circuitry then holds this signal high for at least a minimum time to ensure that the switch maintains the connection between the resistor and the bus for at least a minimum time, regardless of whether the magnitude of the bus voltage drops below the overvoltage threshold before the minimum time has elapsed. Once the minimum time has elapsed, if the magnitude of the bus voltage has dropped below the overvoltage threshold, the hardware control circuitry can cause the switch to disconnect the resistor from the bus. The time delay before disconnecting the resistor provides a technical benefit in that it helps prevent bus voltage oscillations if the source of overvoltage persists. For example, in an electric vehicle where the overvoltage could be caused by a reverse EMF resulting from excessively high motor speeds during battery failure or traction, connecting the resistor to the bus loads the motor and thus slows it down. Keeping the resistor connected to the bus allows the motor to slow down sufficiently below the overvoltage speed, providing a margin to avoid bus voltage oscillations. This time delay method can also provide time for potential secondary overvoltage protection, such as engaging the vehicle's parking brake.

[0005] In one aspect, a protection circuit is provided for protecting an electronic system from overvoltage. The protection circuit may include a dissipative resistor, a switch, and hardware control circuitry. The switch is operable to selectively electrically connect the dissipative resistor to a bus of the electronic system. The hardware control circuitry may be configured to monitor the magnitude of the bus voltage. In response to detecting that the magnitude of the bus voltage is greater than an overvoltage threshold, the hardware control circuitry may be further configured to output a first signal at a first level to cause the switch to electrically connect the dissipative resistor to the bus to dissipate energy in the bus, and to maintain the first signal at the first level for at least a minimum time so that the switch continues to electrically connect the dissipative resistor to the bus for at least a minimum time, regardless of whether the magnitude of the bus voltage drops below the overvoltage threshold before the minimum time has elapsed. In response that the minimum time has elapsed and the magnitude of the bus voltage is below the overvoltage threshold, the hardware control circuitry may be further configured to output a first signal at a second level to cause the switch to electrically disconnect the dissipative resistor from the bus.

[0006] In some implementations, the hardware control circuitry may include a comparator and a timing circuit. The comparator may be configured to receive a transition voltage corresponding to the bus voltage and a reference voltage corresponding to an overvoltage threshold. In response to detecting that the amplitude of the transition voltage is greater than the amplitude of the reference voltage, the comparator may be further configured to transmit an overvoltage signal to the timing circuit. In response to detecting that the amplitude of the transition voltage is less than the amplitude of the reference voltage, the comparator may be further configured to terminate the transmission of the overvoltage signal to the timing circuit. In response to receiving an overvoltage signal, the timing circuitry may be configured to output a first signal at a first level to cause a switch to electrically connect a dissipation resistor to the bus to dissipate energy in the bus, and to maintain the first signal at the first level for at least a minimum time so that the switch continues to electrically connect the dissipation resistor to the bus for at least a minimum time. In response that the minimum time has elapsed and no overvoltage signal has been received, the timing circuitry may be further configured to output the first signal at a second level to cause the switch to electrically disconnect the bus from the dissipation resistor.

[0007] In some implementations, the comparator may include an operational amplifier.

[0008] In some implementations, the hardware control circuitry may further include a voltage divider configured to provide a reference voltage to the comparator.

[0009] In some implementations, the hardware control circuitry may further include a voltage transducer. The voltage transducer may be configured to measure the bus voltage. The voltage transducer may be further configured to determine a conversion voltage from the bus voltage and provide the conversion voltage to a comparator.

[0010] In some implementations, the voltage transducer may include a Hall effect sensor.

[0011] In some implementations, the hardware control circuitry may further include logic gates and resistor-connected sensors. The logic gates may include multiple inputs, each configured to receive a corresponding signal. In response to each of the multiple inputs receiving a first-level signal, the logic gate may be configured to cause a switch to electrically connect the dissipative resistor to a bus. In response to at least one of the multiple inputs not receiving a first-level signal, the logic gate may be further configured to cause the switch to electrically disconnect the bus from the dissipative resistor. In response to receiving an overvoltage signal from the comparator, a timing circuit may be configured to output a first signal at a first-level to a first input of the multiple inputs of the logic gate and hold the first signal at the first-level for at least a minimum time. In response to the minimum time having elapsed and no overvoltage signal being received, the timing circuit may be configured to output the first signal at a second-level to the first input of the multiple inputs. The resistor-connected sensor may be configured to monitor the electrical connection between the dissipative resistor and the switch. In response to detecting that the dissipative resistor is electrically connected to the switch, the resistor-connected sensor may be further configured to output a second signal at a first-level to a second input of the multiple inputs of the logic gate. In response to the detection that the dissipative resistor is not electrically connected to the switch, the resistor-connected sensor can be further configured to output a second signal at a second level to a second input of a plurality of inputs.

[0012] In some implementations, the protection circuit may further include a control unit. The control unit may be programmed to selectively output a third signal at a first level to a third input of a plurality of inputs of the logic gate. In response to detecting a default condition, the control unit may be further programmed to output the third signal at a second level to the third input of a plurality of inputs of the logic gate.

[0013] In some implementations, the protection circuit may further include a resistor temperature sensor. The resistor temperature sensor may be configured to measure the temperature of the dissipative resistor. The resistor temperature sensor may be operationally in communication with the control unit. In response to the resistor temperature sensor detecting that the temperature of the dissipative resistor is greater than a resistor temperature threshold, the control unit may be programmed to output a third signal at a second level to the third input of a plurality of inputs of a logic gate.

[0014] In some embodiments, the protection circuit may further include a switch temperature sensor. The switch temperature sensor may be configured to measure the temperature of the switch. The switch temperature sensor may be operationally communicative with the control unit. In response to the switch temperature sensor detecting that the switch temperature is greater than a switch temperature threshold, the control unit may be programmed to output a third signal at a second level to the third input of a plurality of inputs of a logic gate.

[0015] In some implementations, the protection circuit may further include a switch error sensor. The switch error sensor may be configured to detect whether the switch has an error. The switch error sensor may be operationally communicative with the control unit. In response to the switch error sensor detecting an error in the switch, the control unit may be programmed to output a third signal at a second level to the third input of a plurality of inputs of a logic gate.

[0016] In some implementations, the protection circuitry can be configured as part of the vehicle. In this implementation, the control unit can be configured to output a braking control signal to engage the vehicle's brakes in response to a hardware control circuit causing a switch to electrically connect a dissipative resistor to a bus.

[0017] In some implementations, the control unit can communicate operationally with a switch. In this implementation, the control unit can be programmed to control the switch to electrically connect the dissipative resistor to the bus and to electrically disconnect the dissipative resistor from the bus.

[0018] In some embodiments, the protection circuit may further include a control unit that operates in communication with the switch. In this embodiment, the control unit may be programmed to control the switch to electrically connect the dissipative resistor to the bus and to electrically disconnect the dissipative resistor from the bus.

[0019] In some implementations, the control unit may be further programmed to control the switches to selectively connect and disconnect the dissipation resistors and the bus in order to control the dissipation of energy in the bus by pulse width modulation.

[0020] In some implementations, the electronic system may include a battery, and the protection circuit may be configured to receive power from the battery to operate the protection circuit.

[0021] In some embodiments, the protection circuit may further include a holding circuit. The holding circuit may be configured to store electrical power from the battery. In response to the protection circuit being disconnected from the battery, the holding circuit may be further configured to provide power to operate the protection circuit.

[0022] In some implementations, the electronic system may include an electric motor. The electric motor may generate a back electromotive force (EMF), and the protection circuit may be configured to receive power from the back EMF to operate the protection circuit.

[0023] In some implementations, the protection circuit may further include a voltage converter. The voltage converter may be configured to convert the voltage from back electromotive force to a supply voltage for the protection circuit.

[0024] In some implementations, the voltage converter may include a direct-to-direct-current (DC-DC) converter.

[0025] In some implementations, the DC-DC converter may include a buck converter.

[0026] In some implementations, the buck converter can be configured to convert the voltage from the back EMF to the supply voltage only if the voltage from the back EMF exceeds a converter threshold.

[0027] In some implementations, the electronic system may include an electric vehicle with a parking brake. In this implementation, in response to detecting that the magnitude of the bus voltage exceeds an overvoltage threshold, the protection circuit may be configured to engage the parking brake.

[0028] On the other hand, an electric vehicle is provided. An electric vehicle may include an electric motor, a traction battery, a bus for carrying power between the electric motor and the traction battery, and protection circuitry operatively connected to the bus as described herein.

[0029] On the other hand, a method for protecting an electronic system from overvoltage is provided. The method may involve monitoring the magnitude of a bus voltage on the bus of the electronic system. In response to detecting that the magnitude of the bus voltage is greater than an overvoltage threshold, the method may further involve: causing a switch to electrically connect a dissipative resistor to the bus to dissipate energy in the bus, and causing the switch to continue electrically connecting the dissipative resistor to the bus for at least a minimum time, regardless of whether the magnitude of the bus voltage drops below the overvoltage threshold before the minimum time has elapsed. In response that the minimum time has elapsed and the magnitude of the bus voltage is below the overvoltage threshold, the method may further involve: causing a switch to electrically disconnect the dissipative resistor from the bus.

[0030] Other aspects and features will become apparent to those skilled in the art upon review of the following description of illustrative embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0031] Exemplary embodiments are illustrated in the figures referenced in the accompanying drawings. The embodiments and drawings disclosed herein are intended to be illustrative rather than restrictive.

[0032] Figure 1 This is a circuit diagram illustrating a protection circuit for protecting an electronic system from overvoltage, according to one embodiment.

[0033] Figure 2 It is an explanation Figure 1 The circuit diagram of the 555 timer integrated circuit for hardware control circuit.

[0034] Figure 3 This is a flowchart of a method for protecting an electronic system from overvoltage according to one embodiment.

[0035] Figure 4This is a schematic diagram illustrating an electronic system including a protection circuit for protecting the electronic system from overvoltage, according to another embodiment.

[0036] Figure 5 It is merged Figure 4 A simplified schematic diagram of an example battery-electric vehicle's electronic system.

[0037] Figure 6 It is an explanation Figure 4 The circuit diagram of the holding circuit of the protection circuit.

[0038] Figure 7 This is a schematic diagram illustrating an electronic system including a protection circuit for protecting the electronic system from overvoltage, according to another embodiment.

[0039] Figure 8 It indicates Figure 1 The diagram shows the overvoltage response time of the protection circuit. Detailed Implementation

[0040] refer to Figure 1 A protection circuit according to one embodiment is generally shown at 100. The protection circuit 100 can be coupled to a bus 102 of an electronic system, such as an electric vehicle, to protect electronic devices connected to or a portion of the bus 102, and thus protect the electronic system from overvoltage. The protection circuit 100 includes a dissipative resistor 104, a switch 106, and hardware control circuitry 108. The switch 106 is operable by the hardware control circuitry 108 to selectively connect the dissipative resistor 104 to the bus 102 to dissipate energy in the bus 102, and thus reduce voltage or overvoltage in the bus 102. In the illustrated embodiment, the switch 106 is an insulated-gate bipolar transistor (IGBT). However, in other embodiments, other types of switches or transistors may be used instead of switch 106, or other types of switches or transistors may be used in addition to switch 106. Further, in some alternative embodiments, the protection circuit may include more than one switch and / or more than one dissipative resistor.

[0041] Generally, the hardware control circuit 108 monitors the bus voltage of bus 102 and controls switch 106 to electrically connect or disconnect dissipative resistor 104 and bus 102, at least based on the bus voltage. For example, if an overvoltage is detected in bus 102—that is, if the magnitude of the bus voltage is higher than an overvoltage threshold—the hardware control circuit 108 can cause switch 106 to electrically connect dissipative resistor 104 to bus 102. In the illustrated embodiment, the hardware control circuit 108 includes a voltage divider 110, a voltage transducer 112, a comparator 114, a timing circuit 116, and a logic gate 118.

[0042] Voltage divider 110, voltage transducer 112, and comparator 114 work together to detect overvoltages in bus 102 and, if an overvoltage is detected, to signal timing circuit 116. In some embodiments, voltage divider 110, voltage transducer 112, and comparator 114 may be collectively referred to as a “monitoring circuit”.

[0043] Voltage transducer 112 measures the bus voltage of bus 102, determines a conversion voltage based on the measured bus voltage, and provides the conversion voltage to comparator 114. In some embodiments, voltage transducer 112 may include a Hall effect sensor (i.e., a current clamp) configured to provide a non-contact measurement of the bus current in bus 102. In this embodiment, voltage transducer 112 can determine the bus voltage from the bus current provided by the Hall effect sensor, and can then calculate the conversion voltage corresponding to the measured bus voltage. For example, the conversion voltage may have a value scaled relative to the bus voltage. Voltage transducer 112 then outputs this conversion voltage to comparator 114. By using non-contact measurement, this configuration of voltage transducer 112 advantageously allows for the measurement of the bus voltage without applying a load to bus 102—i.e., without consuming power. Additionally, using this configuration, comparator 114 can be isolated from high voltages on bus 102.

[0044] Voltage divider 110 defines and provides a reference voltage to comparator 114 for comparison with the transition voltage provided by voltage transducer 112. The reference voltage generally corresponds to an overvoltage threshold defining the maximum permissible value for the amplitude of the bus voltage, exceeding which overvoltage protection is required. For example, the reference voltage may have a value scaled relative to the overvoltage threshold by the same scaling factor that correlates the transition voltage with the bus voltage, such that if the amplitude of the bus voltage is greater than the overvoltage threshold, the amplitude of the transition voltage will be greater than the amplitude of the reference voltage. In the illustrated embodiment, voltage divider 110 includes a power supply terminal 120, a first voltage-dividing resistor 122, a second voltage-dividing resistor 124, and a voltage divider output 126. Voltage divider 110 receives a power supply voltage at power supply terminal 120 and generates a reference voltage at voltage divider output 126 connected to comparator 114. The reference voltage at voltage divider output 126 can be adjusted by selectively changing the resistance of the first voltage-dividing resistor 122 and the second voltage-dividing resistor 124. For example, in Figure 1 In the embodiment shown, the reference voltage V ref It can be obtained as follows:

[0045]

[0046] Where R1 is the resistance of the first voltage divider resistor 122, R2 is the resistance of the second voltage divider resistor 124, and V s This is the power supply voltage at terminal 120. Therefore, as an example, if R1 is 27000 Ω, R2 is 2200 Ω, and V... s If the voltage is 15V, then the voltage divider outputs a reference voltage V at point 126. ref It will be 1.13 V.

[0047] Comparator 114 includes a positive input terminal 128 that receives a converted voltage (corresponding to a measured bus voltage) from 112, and a negative input terminal 130 that receives a reference voltage (corresponding to an overvoltage threshold) from the voltage divider output 126 of voltage divider 110. Comparator 114 compares the converted voltage with the reference voltage to determine if an overvoltage exists in bus 102, and if an overvoltage is detected, transmits an overvoltage signal to timing circuit 116. More specifically, comparator 114 transmits the overvoltage signal to timing circuit 116 in response to detecting that the magnitude of the converted voltage is greater than the magnitude of the reference voltage. Conversely, comparator 114 terminates the transmission of the overvoltage signal to timing circuit 116 in response to detecting that the magnitude of the converted voltage is less than the magnitude of the reference voltage. In the illustrated embodiment, comparator 114 is an operational amplifier and receives the power supply voltage at power supply terminal 132.

[0048] Generally, upon receiving an overvoltage signal from comparator 114, timing circuit 116 outputs a first signal at a first level to cause switch 106 to electrically connect dissipative resistor 104 to bus 102, and holds the first signal at the first level for at least a minimum time to allow switch 106 to continue electrically connecting dissipative resistor 104 to bus 102 for at least a minimum time. Once the minimum time has elapsed, and if timing circuit 116 no longer receives an overvoltage signal from comparator 114, timing circuit 116 outputs the first signal at a second level to cause switch 106 to electrically disconnect dissipative resistor 104 from bus 102. By keeping switch 106 connected between dissipative resistor 104 and bus 102 for at least a minimum time, timing circuit 116 helps prevent bus voltage oscillations between overvoltage and normal operating levels, even if the source of overvoltage persists. The minimum time delay before disconnecting dissipative resistor 104 from bus 102, and thus potentially allowing overvoltage return, also serves as a buffer or margin, providing time to address the source of overvoltage. In some implementations, the minimum time may be, for example, about 500 milliseconds. In some implementations, the timing circuit 116 may be referred to as a "timer" or a "hysteresis timer".

[0049] exist Figure 1In the embodiment shown, the timing circuit 116 includes a 555 timer integrated circuit 200, a trigger switch 134, a timing resistor 136, a timing capacitor 138, a decoupling capacitor 140, and a power supply terminal 142. The 555 timer 200 can be, for example, from Texas Instruments. ® TLC555 LinCMOS TM Timer. The internal structure of the 555 timer 200 is shown below. Figure 2 As shown, it is related to the TLC555 LinCMOS. TM Corresponding timer. (See reference) Figure 1 and Figure 2 The 555 timer 200 includes a ground pin (GRO) 202, a trigger pin (TRI) 204, an output pin (OUT) 206, a reset pin (RES) 208, a control pin (CON) 210, a threshold pin (THR) 212, a discharge pin (DIS) 214, a power supply pin (SUP) 216, a flip-flop 220, a first comparator 222, and a second comparator 224. The flip-flop 220 is an SR flip-flop, with its R input connected to the output of the first comparator 222 and its S input connected to the output of the second comparator 224. Very generally, the ground pin 202 is a ground reference voltage, while the power supply for the 555 timer 200 is provided at the power supply pin 216. The discharge pin 214 is an open-collector output used to discharge a timing capacitor, such as a timing capacitor 138. The output pin 206 transmits the output signal of the 555 timer 200. The output signal can be transmitted as a high or low level. In the illustrated embodiment, the output signal of the 555 timer 200 is a first signal, with a high level being the first level and a low level being the second level. Trigger pin 204 is used to initiate a high-output timing interval during which the output signal is transmitted at a high level. Threshold pin 212 is used to define the end of the high-output timing interval. In the illustrated embodiment, the high-output timing interval corresponds to the minimum time for which timing circuit 116 holds the first signal at the first level in response to receiving an overvoltage signal from comparator 114. Reset pin 208 can be used to reset the high-output timing interval and / or cause the output signal to be transmitted at a low level. Reset pin 208 overrides trigger pin 204, which in turn overrides threshold pin 212. Finally, control pin 210 can be used to control the comparator threshold in the 555 timer 200 to adjust the timing characteristics of the 555 timer 200.

[0050] exist Figure 1In the embodiment shown, the 555 timer 200 is configured for monostable operation. The reset pin 208 is electrically connected to the power supply pin 216 to prevent any accidental or erroneous triggering of the reset, and the control pin 210 is connected to the decoupling capacitor 140 to ensure that electrical noise does not affect the internal circuitry of the 555 timer 200. In operation of this embodiment, when the timing circuit 116 is in a lurking state before the comparator 114 has transmitted an overvoltage signal to the timing circuit 116, the output pin 206 transmits the first signal at a second level (low). When the comparator 114 transmits the overvoltage signal to the timing circuit 116, the overvoltage signal is received by the trigger switch 134, causing the trigger switch 134 to close. As a result, the trigger pin 204 is grounded, drops to a low voltage level, and initiates the high output timing interval of the 555 timer 200. During the high output timing interval, the output pin 206 transmits the first signal at a first level (high), and the timing capacitor 138 is charged through the timing resistor 136. The high-output timing interval ends when the voltage across timing capacitor 138 reaches the threshold voltage of threshold pin 212. In the illustrated embodiment, this threshold voltage is 2 / 3 of the power supply voltage at power supply pin 216. If, at the end of the high-output timing interval, comparator 114 has terminated the transmission of the overvoltage signal to timing circuit 116, causing trigger switch 134 to open, and thus trigger pin 204 to disconnect from ground and return to a high voltage level, then output pin 206 transmits the first signal at a second level (low), and timing capacitor 138 discharges through discharge pin 214 to allow subsequent triggering of 555 timer 200. Therefore, in response to receiving an overvoltage signal from comparator 114, timing circuit 116 transmits the first signal at a first level from output pin 206 for at least the minimum time of the high-output timing interval. The high-output timing interval, and thus the minimum time, can be set by adjusting the resistance of timing resistor 136 and the capacitance of timing capacitor 138. More specifically, the high-output time interval t can be obtained as follows:

[0051]

[0052] Among them, R t It is the resistor of the timing resistor 136, and C t It is the capacitance of timing capacitor 138. Therefore, as an example, if R t 50000 Ω and C t If the value is 10µF, the high output time interval t will be approximately 549 milliseconds.

[0053] exist Figure 1In the embodiment shown, timing circuit 116 outputs a first signal from output pin 206 of 555 timer 200 to input of logic gate 118, and logic gate 118 ultimately directly controls switch 106 to connect or disconnect dissipative resistor 104 and bus 102. Generally, logic gate 118 may include multiple inputs, each configured to receive a corresponding signal, wherein at least one of these inputs is configured to receive the first signal from timing circuit 116. If each of the multiple inputs receives its corresponding first-level signal, logic gate 118 causes switch 106 to electrically connect dissipative resistor 104 to bus 102. However, if at least one of the multiple inputs of logic gate 118 does not receive its corresponding first-level signal, logic gate 118 causes switch 106 to electrically disconnect dissipative resistor 104 from bus 102. In the illustrated embodiment, logic gate 118 is an AND gate and includes a first gate switch 144 configured to receive a first signal from timing circuit 116, a second gate switch 146 configured to receive a second signal from second external source 148, a third gate switch 150 configured to receive a third signal from third external source 152, and a power supply terminal 154 for receiving a power supply voltage. The second external source 148 and the third external source 152 may be controllers and / or sensors, such as those monitoring protection circuit 100 or other components of the electronic system. If each of the gate switches 144, 146, and 150 receives a signal of its corresponding first level, it will close. More specifically, in the illustrated embodiment, the first level is a high level, and each of the gate switches 144, 146, and 150 is an N-channel enhancement-mode metal-oxide-semiconductor field-effect transistor (MOSFET) that will close if it receives a high-level input signal. Therefore, if the first, second, and third signals are all received at the first level (high), door switches 144, 146, and 150 will all close, thus connecting the power supply voltage to switch 106, causing switch 106 to close, and connecting dissipation resistor 104 to bus 102. If one or more of the first, second, and / or third signals are instead received at the second level (low), the corresponding door switch will open, disconnecting the power supply voltage from switch 106, causing switch 106 to open, and disconnecting dissipation resistor 104 from bus 102.

[0054] Figure 1The hardware control circuitry 108 shown in the embodiments is merely an example, and alternative embodiments may differ. For example, some alternative embodiments may use logic gates of a different type than the AND gate. Other alternative embodiments may omit logic gate 118 entirely and connect timing circuitry 116 directly to switch 106. In yet another alternative embodiment, logic gate 118 may include more than three inputs or fewer than three inputs (e.g., if no software control is available to supplement the hardware circuitry, external source 152 and gate switch 150 may be omitted from logic gate 18). In still other alternative embodiments, the monitoring circuitry (illustrated as voltage divider 110, sensor 112, and comparator 114) may have different hardware configurations to implement the same overvoltage monitoring described herein.

[0055] refer to Figure 3 A general method for operating the protection circuit 100 to protect the electronic system, including bus 102, from overvoltage is shown at 300. At 302, a voltage divider 110, a voltage transducer 112, and a comparator 114 are used to monitor the amplitude of the bus voltage of bus 102. At 304, the comparator 114 is used to compare the amplitude of the bus voltage measured by the voltage transducer 112 with an overvoltage threshold defined by the voltage divider 110. At 306, in response to detecting that the amplitude of the bus voltage is greater than the overvoltage threshold (i.e., an overvoltage exists in bus 102), a first signal is output at a first level by a timing circuit 116 to cause a switch 106 to electrically connect a dissipation resistor 104 to bus 102 via a logic gate 118 to dissipate energy in bus 102. At 308, timing circuit 116 maintains the first signal at a first level for at least a minimum time so that switch 106 continues to electrically connect dissipative resistor 104 to bus 102 for at least a minimum time, regardless of whether the bus voltage amplitude drops below an overvoltage threshold before the minimum time has elapsed. At 310, once the minimum time has elapsed, comparator 114 indicates whether the measured bus voltage amplitude is below the overvoltage threshold. At 312, in response to the minimum time having elapsed and the detection that the bus voltage amplitude is below the overvoltage threshold, timing circuit 116 outputs the first signal at a second level to cause switch 106 to electrically disconnect dissipative resistor 104 from bus 102.

[0056] Because the protection circuit 100 is implemented entirely in hardware, it can provide a much faster response time to overvoltage events than software-based overvoltage protection systems. For example, the protection circuit 100 can trigger within 100 microseconds of an overvoltage event occurring. Without this fast response time, electronic equipment could be damaged by overvoltage.

[0057] Now for reference Figure 4 and Figure 5An electronic system according to another embodiment is generally shown at 400 and includes a bus 402 and a protection circuit 404. The bus may be a combination of Figures 1 to 3 The described bus 102, and the protection circuit 404 may include a combination of Figure 1 The hardware protection circuit 100 is described. Figure 4 and Figure 5 In the embodiment shown, the electronic system 400 is an electric vehicle, and (as shown) Figure 5 (As shown) further includes an electric motor 406, an electric motor controller 408, a traction battery 410, a vehicle main control unit 412, a parking brake 414, and an auxiliary battery (AUX) 416. Very generally, the electric motor controller 408 controls the operation of the electric motor 406. Bus 402 electrically connects the traction battery 410 to the electric motor controller 408 and the electric motor 406 to allow power to flow between the traction battery 410 and the electric motor 406. As explained above, in some cases, the back EMF generated by the electric motor 406 can create potentially destructive overvoltages on bus 402. Protection circuitry 404 is operatively connected to bus 402 between the traction battery 410 and the electric motor controller 408 to protect bus 402 and the electronic system 400 (i.e., the vehicle) from this and other sources of overvoltage.

[0058] like Figure 4 As shown, the protection circuit 404 includes a dissipation resistor 418. Figure 4 The Chinese explanation is "R"), switch 420 ( Figure 4 (Explained as "S"), hardware control circuit 422, resistor connecting sensor 424, control unit 426 ( Figure 4 The diagram illustrates a microcontroller unit (MCU) and a holding circuit 428. Dissipative resistor 418 can be or may be similar to dissipative resistor 104, switch 420 can be or may be similar to switch 106, and hardware control circuit 422 can be or may be similar to hardware control circuit 108. Generally, dissipative resistor 418, switch 420, and hardware control circuit 422 function together in the same manner as dissipative resistor 104, switch 106, and hardware control circuit 108. That is, hardware control circuit 422 monitors the bus voltage of bus 402 and controls switch 420 to electrically connect or disconnect dissipative resistor 418 and bus 402, at least based on the bus voltage.

[0059] Resistor connection sensor 424 monitors the electrical connection between dissipative resistor 418 and switch 420 and signals to hardware control circuitry 422 whether dissipative resistor 418 is electrically connected to switch 420. For example, if dissipative resistor 418 fails, it may not be electrically connected to switch 420. More specifically, in some embodiments where hardware control circuitry 422 is hardware control circuitry 108, resistor connection sensor 424 is configured to output a second signal at a first level to second gate switch 146 of logic gate 118 in response to detecting that dissipative resistor 418 is electrically connected to switch 420, and is further configured to output a third signal at a second level to second gate switch 146 in response to detecting that dissipative resistor 418 is not electrically connected to switch 420. That is, in this embodiment, resistor connection sensor 424 may be a second external source 148. By outputting a second signal at a second level to logic gate 118 when dissipative resistor 418 is disconnected from switch 420, the resistor-connected sensor 424 prevents logic gate 118 from causing switch 420 to electrically connect dissipative resistor 418 to bus 402 in this situation. This mechanism is an important safety feature because if dissipative resistor 418 has failed and is therefore not electrically connected to switch 420, causing switch 420 to attempt to connect the (failed) dissipative resistor 418 to bus 402 could cause a short circuit between bus 402 and other parts of electronic system 400, potentially leading to a fire.

[0060] Control unit 426 generally provides additional software-based control and reporting features to protection circuit 404 to complement hardware control circuit 422. For example, in some embodiments where hardware control circuit 422 is hardware control circuit 108, control unit 426 is programmed to selectively output a third signal at a first level to third gate switch 150 of logic gate 118, and is further programmed to output a third signal at a second level to third gate switch 150 in response to detection of a default condition. That is, in this embodiment, control unit 426 may be a third external source 152. In some embodiments, control unit 426 may be, for example, a microcontroller unit (MCU), as illustrated, however control unit 426 is not necessarily an MCU. If control unit 426 is an MCU, it may be implemented by a processor executing instructions stored in the MCU's memory to provide software control that complements hardware overvoltage protection, resulting in a fast response time for hardware protection, which is supplemented by software control for enhanced complementary features, examples of which are described herein.

[0061] In some embodiments, the control unit 426 may operatively communicate with one or more sensors of other elements of the monitoring protection circuit 404. For example, in the illustrated embodiment, the protection circuit 404 includes a resistor temperature sensor 430, a switch temperature sensor 432, and a switch error sensor 434. Each of the resistor temperature sensor 430, switch temperature sensor 432, and switch error sensor 434 operatively communicates with the control unit 426. The resistor temperature sensor 430 is configured to measure the temperature of the dissipative resistor 418, and the control unit 426 is programmed to output a third signal at a second level to the third gate switch 150 of logic gate 118 in response to the resistor temperature sensor 430 detecting that the temperature of the dissipative resistor 418 is greater than a resistor temperature threshold. The switch temperature sensor 432 is configured to measure the temperature of the switch 420, and the control unit 426 is programmed to output a third signal at a second level to the third gate switch 150 in response to the switch temperature sensor 434 detecting that the temperature of the switch 420 is greater than a switch temperature threshold. Finally, the switch error sensor 434 is configured to detect whether the switch 420 has an error, and the control unit 426 is programmed to output a third signal to the third door switch 150 at a second level in response to the switch error sensor 438 detecting that the switch 420 has an error.

[0062] In some embodiments, the control unit 426 may also communicate operationally with the hardware control circuit 422 and the parking brake 414. In some such embodiments, the control unit 426 may be configured to output a braking control signal to engage the parking brake 414 in response to the hardware control circuit 422 causing the switch 420 to electrically connect the dissipation resistor 418 to the bus 402. That is, in the event of an overvoltage, in addition to the hardware control circuit 422 causing the switch 420 to electrically connect the dissipation resistor 418 to the bus 402, the control unit 426 may also engage the parking brake 414. This additional engagement of the parking brake 414 may be advantageous in situations where the source of overvoltage in the bus 402 is persistent (e.g., high-speed traction of the vehicle), because prolonged use of the dissipation resistor 418 for power dissipation may overload and cause it to fail. In alternative embodiments, the engagement of the parking brake 414 may be triggered by elements of the protection circuit 404 other than the control unit 426. For example, a signal originating from the output of a timing circuit that triggers a switch (e.g., from...). Figure 1 The signal from the output pin 206 can also engage the parking brake 414. As another example, the parking brake 414 can be triggered independently of causing switch 420 to electrically connect dissipative resistor 418 to bus 402. That is, protection circuit 404 can generally be configured to engage parking brake 414 in response to detecting that the bus voltage amplitude is greater than an overvoltage threshold.

[0063] In some embodiments, control unit 426 may also be in direct operational communication with switch 420 and may be programmed to control switch 420 to electrically connect dissipation resistor 418 to bus 402 and electrically disconnect dissipation resistor 418 from bus 402. In some such embodiments, control unit 426 may be further programmed to control switch 420 to selectively connect and disconnect dissipation resistor 418 and bus 402 to control energy dissipation in bus 402 via pulse width modulation (PWM). When there is no overvoltage in electronic system 400 due to traction or fault, such as during regenerative braking when the battery is already fully charged and the voltage generated by regenerative braking needs to be dissipated, the PWM of switch 420 can allow energy dissipation in bus 402 during normal operation. PWM can mitigate or avoid the need for a rotating auxiliary motor to dissipate power.

[0064] In some implementations, control unit 426 may also communicate operationally with vehicle main control unit 412. For example, control unit 426 may provide feedback to main control unit 412 regarding the status of protection circuit 404 or other components of electronic system 400.

[0065] In the illustrated embodiment, the protection circuit 404 is configured to receive operating power from the auxiliary battery 416, from the bus 402, or from both power sources. The power received by the protection circuit 404 from the bus 402 may be or includes power generated by the motor 406 on the bus 402 in the form of anti-EMF. Regardless of the source, the power supplied to the protection circuit 404 first passes through the holding circuit 428.

[0066] Now for reference Figure 4 and Figure 6 In the illustrated embodiment, the holding circuit 428 includes a bus input terminal 430, a battery input terminal 432, a voltage converter 434, a holding capacitor 436, and a power output terminal 438. The bus input terminal 430 is configured to receive power from the bus 402, such as from the anti-EMF on the bus 402. The battery input terminal 432 is configured to receive power from the auxiliary battery 416. The power output terminal 438 is configured to provide power to other components of the protection circuit 404.

[0067] Voltage converter 434 is configured to convert a voltage received at bus input terminal 430 into a power supply voltage for powering protection circuit 404, which can be very high if the received voltage is caused by a reverse EMF (e.g., overvoltage). In the illustrated embodiment, bus 402 carries direct current (DC), and therefore voltage converter 434 is a DC-DC converter. More specifically, voltage converter 434 is a buck converter and is configured to convert a voltage received at bus input terminal 430 (e.g., from a reverse EMF) into a power supply voltage for protection circuit 404 only if the voltage received at bus input terminal 430 (e.g., from a reverse EMF) exceeds a converter threshold. Voltage converter 434 can be, for example, MORNSUN. ® The PV40-29BxxR3 series DC / DC converters have a threshold voltage of, for example, 200V.

[0068] Holding capacitor 436 is configured to store power received by holding circuit 428 from auxiliary battery 416 and / or from bus 402. In the event of loss of power input to holding circuit 428, holding capacitor 436 can temporarily provide power to operate protection circuit 404. Thus, for example, if holding circuit 428 is receiving power from auxiliary battery 416, some of the power will be stored in holding capacitor 436. Subsequently, if holding circuit 428 becomes disconnected from auxiliary battery 416, holding circuit 428 will respond by providing the stored power from holding capacitor 436 to operate protection circuit 404. In some embodiments, holding circuit 428 may be able to supply power to protection circuit for up to 4 milliseconds after power disconnection. This feature is particularly advantageous in high-speed fault scenarios such as when the electric vehicle (i.e., electronic system 400) is moving at high speed and the vehicle batteries (i.e., auxiliary battery 416 and traction battery 410) suddenly become disconnected. In this case, motor 406 will generate considerable back EMF and overvoltage that need to be dissipated immediately. The auxiliary battery cannot power the protection circuit 404 to dissipate overvoltage because it has become disconnected. Electronic devices connected to the bus may be damaged by overvoltage before the anti-EMF at input terminal 430 provides the necessary power to power the protection circuit 404. However, the holding circuit 428 advantageously retains the power supply to the protection circuit 404. Therefore, the stored power from the holding circuit 428 powers the protection circuit 404 to dissipate energy from the anti-EMF.

[0069] refer to Figure 4The protection circuit 404 also includes voltage converters 440 and 442. Voltage converter 440 receives power from the power output terminal 438 of the holding circuit and converts the voltage to a value suitable for the components of the hardware control circuit 422 (e.g., 5 V or 15 V). Similarly, voltage converter 442 receives power from the power output terminal 438 of the holding circuit and converts the voltage to a value suitable for the control unit 426 (e.g., 3.3 V).

[0070] Note that the holding circuit 428, which has two power input terminals (from bus 402 via bus input terminal 430 and from auxiliary battery 416 via battery input terminal 432) and a voltage converter 440, can be used with... Figure 1 The hardware control circuitry 108 is provided in combination, without Figure 4 Other components illustrated in the implementation (e.g., MCU, etc.). Figure 1 The components of the hardware control circuit 108 require power to operate, and this power can be provided by bus 402 (via reverse EMF during traction) or auxiliary battery 416 (when overvoltage protection is required during vehicle operation), wherein holding circuit 428 holds power and voltage converter 440 steps down the voltage to the level required to power the components of the hardware control circuit.

[0071] It should also be noted that, in the illustrated embodiment, the power supply for the hardware protection circuit can come from the reverse EMF (via bus input terminal 430) or from the auxiliary battery 416 (via battery input terminal 432). Having both power supplies is not necessary in all embodiments, but the advantage of having both is that overvoltage protection can be implemented both when the vehicle is running and when it is not running. When the vehicle is running, the auxiliary battery 416 provides power to the overvoltage protection circuit in fault scenarios (the power is maintained as explained above). When the vehicle is not running, there is no power from the auxiliary battery 416, but overvoltage scenarios may still occur, such as when the vehicle is towed. In this case, the reverse EMF generated by towing can itself provide power to the hardware protection circuit. Therefore, overvoltage protection is implemented both when the vehicle is running and when it is not running.

[0072] Now for reference Figure 7 An electronic system according to another embodiment is generally shown at 700 and includes a bus 702, an auxiliary battery 704, a controller area network (CAN) bus 706, and a protection circuit 708. The protection circuit 708 includes protection circuitry for... Figure 7 The description includes all components that are directly or indirectly involved in providing overvoltage protection; these constitute the majority of the components explained. Very generally, the protection circuit 708 is similar to... Figure 4Protection circuit 404 is included. Protection circuit 708 is operatively connected to bus 702 to protect bus 702 and electronic system 700 from overvoltage. Protection circuit 708 includes dissipation resistor 710. Figure 7 Marked as "R" in the middle), switch 712 ( Figure 7 (marked as "S"), voltage transducer 714, response circuit 716, timing circuit 718, AND gate 720, resistor-connected sensor 722, control unit 724 ( Figure 7 The components are described in the text as MCU, holding circuit 726, resistor temperature sensor 728, switch temperature sensor 730, and switch error sensor 732.

[0073] Dissipative resistor 710 can be similar to dissipative resistor 418 in protection circuit 404 or dissipative resistor 104 in protection circuit 100. Similarly, switch 712 can be similar to switch 420 or switch 106. Voltage transducer 714 can be similar to voltage transducer 112. Response circuit 716 can correspond to voltage divider 110 and comparator 114. Timing circuit 718 can be similar to timing circuit 116. AND gate 720 can be similar to logic gate 118. In general, the dissipative resistor 710, switch 712, voltage transducer 714, response circuit 716, timing circuit 718, and AND gate 720 of protection circuit 708 can function together in the same way as the dissipative resistor 104, switch 106, voltage transducer 112, voltage divider 110, comparator 114, timing circuit 116, and logic gate 118 of protection circuit 100. That is, the voltage transducer 714, the response circuit 716, the timing circuit 718, and the AND gate 720 monitor the bus voltage of the bus 702, and control the switch 712 to electrically connect or disconnect the dissipation resistor 710 and the bus 702, at least based on the bus voltage.

[0074] Resistor-connected sensor 722 can be similar to resistor-connected sensor 424, control unit 724 can be similar to control unit 426, holding circuit 726 can be similar to holding circuit 428, resistor temperature sensor 728 can be similar to resistor temperature sensor 430, switch temperature sensor 730 can be similar to switch temperature sensor 432, and switch error sensor 732 can be similar to switch error sensor 434. Generally, the resistor-connected sensor 722, control unit 724, holding circuit 726, resistor temperature sensor 728, switch temperature sensor 730, and switch error sensor 732 of protection circuit 708 can function together with the dissipation resistor 710, switch 712, voltage transducer 714, response circuit 716, timing circuit 718, and AND gate 720 of protection circuit 708 in the same way that the resistor-connected sensor 424, control unit 426, holding circuit 428, resistor temperature sensor 430, switch temperature sensor 432, and switch error sensor 434 of protection circuit 404 function together with the dissipation resistor 418, switch 420, and hardware control circuit 422 of protection circuit 404.

[0075] Protection circuit 708 also includes voltage converters 734, 736, and 738, isolation circuit 740, and isolation circuits 742, 744, and 746. Voltage converters 734, 736, and 738 can generally be similar to voltage converters 440 and 442 of protection circuit 404. In the illustrated embodiment, voltage converters 734, 736, and 738 are DC-DC buck converters (i.e., step-down converters) that reduce the voltage received from holding circuit 726 to a level suitable for other components of protection circuit 708. For example, in the illustrated embodiment, holding circuit 726 outputs a 24 V voltage to voltage converters 734 and 736. Voltage converter 734 steps down this input voltage to an output voltage of 15 V, which is used to power components such as response circuit 716, AND gate 720, and switch 712. Voltage converter 736 steps down the input voltage to a 5 V output voltage, which is in turn stepped down by voltage converter 738 to a 3.3 V output voltage. A 3.3V output voltage is used to power, for example, control unit 724. Isolation circuit 740 receives the 5V output voltage from voltage converter 736 and provides an isolated 5V output signal for use by resistor temperature sensor 728 and switch temperature sensor 730. Isolation circuits 742, 744, and 746 isolate high-voltage input signals from circuitry that could be damaged by such high voltage.

[0076] The protection circuit 708 also includes an input level shifter circuit 748 and an output level shifter circuit 750, a resistor current clamp 752, and a control unit address bus 754. The input level shifter circuit 748 and the output level shifter circuit 750 are signal conditioning integrated circuits that provide isolation suitable for level shifting of the control unit 724. More specifically, the input level shifter circuit 748 scales the input voltage to a range of 0 to 3.3 V, while the output level shifter circuit 750 boosts a 3.3 V signal to 15 V and 24 V signals. The resistor current clamp 752 is a non-contact ammeter that monitors the current in the dissipative resistor 710. In embodiments including more than one control unit, the control unit address bus 754 provides an address for the control unit 724.

[0077] In operation, the hardware overvoltage protection consists of a response circuit 716, a timing circuit 718, an AND gate 720, a switch 712, and a dissipation resistor 710, in accordance with the previously described, for example, [specifications related to overvoltage protection]. Figure 1 The control unit 724 is provided in the same manner. The control unit 724 includes a processor that executes instructions stored in memory to provide supplemental software control, including preventing switch 712 from connecting dissipating resistor 710 to bus 702 based on default conditions (e.g., by driving the third door switch 150 of AND gate 720 low). Examples of default conditions could be a failure of dissipating resistor 710 or switch 712, such as dissipating resistor 710 overheating (from resistor temperature sensor 728) or switch 712 overheating (from switch temperature sensor 730) or switch 712 having an error (from switch error sensor 732), as examples. The software control of control unit 724 can also execute the PWM described above and / or control the vehicle parking brake in overvoltage conditions. Figure 7 Not shown in the image; see Figure 4 and Figure 5 The engagement of the circuit 726 is described above. The circuit 726 provides power to the protection circuit in the manner described above (from the auxiliary battery 704 or the inverse EMF of the bus 702), wherein the DC-DC buck converter (i.e., voltage converters 734, 736 and 738) provides appropriate DC power to the components of the protection circuit.

[0078] Example: Response to simulated overvoltage scenarios

[0079] Experimental tests were conducted to evaluate the overvoltage protection of protection circuit 100 (see...). Figure 1 and Figure 2 Test the protection circuit (i.e., Figure 1The protection circuit 100 is connected to the DC bus connecting the motor and the high-voltage battery. The motor has a maximum speed rated at 5200 revolutions per minute (RPM). The battery provides power at 715 V. A power resistor with a resistance of 1.960 Ω is used as a dissipation resistor (i.e., Figure 1 The dissipation resistor 104 in the circuit is connected to the IGBT switch of the test protection circuit (i.e., Figure 1 (Switch 106 in the circuit). An overvoltage threshold of 870 V is set in the test protection circuit. To simulate an overvoltage scenario, the motor is run at maximum speed, and then the battery is disconnected.

[0080] To monitor the response of the test protection circuit to a simulated overvoltage scenario, an oscilloscope is connected to the DC bus, and a current clamp is connected to the IGBT of the test protection circuit. The oscilloscope measures the voltage on the DC bus, while the current clamp measures the current through the dissipation resistor connected to the IGBT.

[0081] Measurements of the DC bus voltage and dissipation resistor current as a function of time during a simulated overvoltage scenario are shown in the figure. Figure 8 middle.

[0082] exist Figure 8 As can be seen, when the battery is disconnected while the motor is rotating at 5200 RPM, the DC bus voltage increases to 893 V. The voltage change rate is 400 kV / s.

[0083] The test protection circuit is triggered at a DC bus voltage of 872 V and controls the DC bus voltage. The test protection circuit is triggered within 100 microseconds of a simulated overvoltage event.

[0084] Once the overvoltage threshold is exceeded, the measured dissipation resistor current can be used to evaluate the end-to-end response time of the test protection circuit. With a dissipation resistor resistance of 1.960 Ω, a peak power of 406 kW is achieved after the IGBT is triggered.

[0085] in conclusion

[0086] Protection circuits such as those described herein can be used to protect electronic systems, such as those in electric vehicles, from overvoltages and may be preferable to other overvoltage protection systems. For example, the protection circuits described herein can provide a fast response time to overvoltages and can implement time delays to prevent voltage oscillations.

[0087] Although specific embodiments have been described and illustrated, such embodiments should be considered illustrative only and not as limiting the invention as interpreted in accordance with the appended claims.

Claims

1. A protection circuit for protecting an electronic system from overvoltage, the protection circuit comprising: Dissipation resistor; A switch operable to selectively connect the dissipation resistor to the bus of the electronic system; as well as The hardware control circuit is configured as follows: Monitor the amplitude of the bus voltage on the bus; In response to detecting that the amplitude of the bus voltage is greater than an overvoltage threshold, a first signal is output at a first level to cause the switch to electrically connect the dissipation resistor to the bus to dissipate energy in the bus, and the first signal is maintained at the first level for at least a minimum time so that the switch continues to electrically connect the dissipation resistor to the bus for at least the minimum time, regardless of whether the amplitude of the bus voltage drops below the overvoltage threshold before the minimum time has elapsed; as well as In response to the minimum time having elapsed and the amplitude of the bus voltage being below the overvoltage threshold, the first signal is output at a second level to cause the switch to electrically disconnect the dissipation resistor from the bus.

2. The protection circuit according to claim 1, wherein, The hardware control circuit includes a comparator and a timing circuit; The comparator is configured to: Receive a conversion voltage corresponding to the bus voltage; receive a reference voltage corresponding to the overvoltage threshold; and transmit an overvoltage signal to the timing circuit in response to detecting that the amplitude of the conversion voltage is greater than the amplitude of the reference voltage. And in response to detecting that the amplitude of the switching voltage is less than the amplitude of the reference voltage, the transmission of the overvoltage signal to the timing circuit is terminated; and The timing circuit is configured as follows: In response to receiving the overvoltage signal, the first signal is output at the first level to cause the switch to electrically connect the dissipation resistor to the bus to dissipate energy in the bus, and the first signal is maintained at the first level for at least the minimum time so that the switch continues to electrically connect the dissipation resistor to the bus for at least the minimum time; And in response to the minimum time having elapsed and no overvoltage signal being received, the first signal is output at the second level to cause the switch to electrically disconnect the bus from the dissipation resistor.

3. The protection circuit according to claim 2, wherein, The comparator includes an operational amplifier.

4. The protection circuit according to claim 2 or 3, wherein, The hardware control circuitry further includes a voltage divider configured to provide the reference voltage to the comparator.

5. The protection circuit according to claim 2, 3 or 4, wherein, The hardware control circuit further includes a voltage transducer, which is configured to: Measure the bus voltage; The conversion voltage is determined from the bus voltage; The converted voltage is provided to the comparator.

6. The protection circuit according to claim 5, wherein, The voltage transducer includes a Hall effect sensor.

7. The protection circuit according to any one of claims 2 to 6, wherein: The hardware control circuit includes logic gates and resistors connected to the sensor; The logic gate includes multiple input terminals, each of which is configured to receive a corresponding signal; The logic gate is configured as follows: In response to each of the plurality of input terminals receiving a signal of the first level, the switch electrically connects the dissipation resistor to the bus; And in response to a signal that at least one of the plurality of input terminals does not receive the first level, the switch electrically disconnects the bus from the dissipation resistor; The timing circuit is configured as follows: In response to receiving the overvoltage signal from the comparator, the first signal is output to the first input of the plurality of inputs of the logic gate at the first level, and the first signal is held at the first level for at least the minimum time. And in response to the minimum time having elapsed and no overvoltage signal being received, the first signal is output at the second level to the first input terminal of the plurality of input terminals; and The resistor-connected sensor is configured as follows: Monitor the electrical connection between the dissipation resistor and the switch; in response to detecting that the dissipation resistor is electrically connected to the switch, output a second signal at the first level to the second input of the plurality of inputs of the logic gate; And in response to detecting that the dissipation resistor is not electrically connected to the switch, output the second signal at the second level to the second input terminal of the plurality of input terminals.

8. The protection circuit of claim 7, further comprising a control unit, the control unit being programmed to at least: Selectively outputting a third signal at the first level to the third input of the plurality of inputs of the logic gate; and In response to the detection of a default condition, the third signal is output at the second level to the third input of the plurality of inputs of the logic gate.

9. The protection circuit of claim 8, further comprising a resistor temperature sensor configured to measure the temperature of the dissipative resistor, wherein, The resistor temperature sensor communicates with the control unit, and the control unit is programmed to output the third signal at the second level to the third input of the plurality of inputs of the logic gate in response to the resistor temperature sensor detecting that the temperature of the dissipative resistor is greater than a resistor temperature threshold.

10. The protection circuit according to claim 8 or 9, further comprising a switch temperature sensor configured to measure the temperature of the switch, wherein, The switch temperature sensor communicates operationally with the control unit, wherein the control unit is programmed to output the third signal at the second level to the third input of the plurality of inputs of the logic gate in response to the switch temperature sensor detecting that the temperature of the switch is greater than a switch temperature threshold.

11. The protection circuit according to claim 8, 9, or 10, further comprising a switch error sensor configured to detect whether the switch has an erroneous switch, wherein, The switch error sensor communicates operationally with the control unit, wherein the control unit is programmed to output the third signal at the second level to the third input of the plurality of inputs of the logic gate in response to the switch error sensor detecting an error in the switch.

12. The protection circuit according to any one of claims 8 to 11, wherein: The protection circuit is configured as part of the vehicle; and The control unit is configured to, in response to the hardware control circuitry, cause the switch to electrically connect the dissipative resistor to the bus, and output a braking control signal to engage the vehicle's brakes.

13. The protection circuit according to any one of claims 8 to 12, wherein, The control unit communicates with the switch and is programmed to at least: Control the switch to electrically connect the dissipation resistor to the bus; and Control the switch to electrically disconnect the dissipation resistor from the bus.

14. The protection circuit according to any one of claims 1 to 7, further comprising a control unit, the control unit being operationally communicated with the switch and programmed to at least: Control the switch to electrically connect the dissipation resistor to the bus; and Control the switch to electrically disconnect the dissipation resistor from the bus.

15. The protection circuit according to claim 13 or 14, wherein, The control unit is further programmed to at least control the switch to selectively connect and disconnect the dissipation resistor and the bus, so as to control the dissipation of energy in the bus by pulse width modulation.

16. The protection circuit according to any one of claims 1 to 15, wherein: The electronic system includes a battery; and The protection circuit is configured to receive power from the battery to operate the protection circuit.

17. The protection circuit of claim 16, further comprising a holding circuit, the holding circuit being configured to: Stores the power from the battery; and Power is supplied to operate the protection circuit in response to disconnection from the battery.

18. The protection circuit according to any one of claims 1 to 17, wherein: The electronic system includes an electric motor; The electric motor generates a back electromotive force; and The protection circuit is configured to receive power from the back electromotive force to operate the protection circuit.

19. The protection circuit of claim 18, further comprising a voltage converter configured to convert the voltage from the back electromotive force into a power supply voltage for the protection circuit.

20. The protection circuit according to claim 19, wherein, The voltage converter includes a DC-DC converter.

21. The protection circuit according to claim 20, wherein, The DC-DC converter includes a buck converter.

22. The protection circuit according to claim 21, wherein, The buck converter is configured to convert the voltage from the back electromotive force into the power supply voltage only when the voltage from the back electromotive force exceeds a converter threshold.

23. The protection circuit according to any one of claims 1 to 22, wherein: The electronic system includes an electric vehicle, and the electric vehicle includes a parking brake; and The protection circuit is configured to engage the parking brake in response to detecting that the amplitude of the bus voltage is greater than the overvoltage threshold.

24. An electric vehicle, comprising: Electric motor; Traction battery; A bus used to carry power between the electric motor and the traction battery; as well as A protection circuit operatively connected to the bus according to any one of claims 1 to 23.

25. A method for protecting an electronic system from overvoltage, the method comprising: Monitor the amplitude of the bus voltage of the electronic system's bus; In response to detecting that the amplitude of the bus voltage is greater than an overvoltage threshold, the switch electrically connects a dissipation resistor to the bus to dissipate energy in the bus, and the switch continues to electrically connect the dissipation resistor to the bus for at least a minimum time, regardless of whether the amplitude of the bus voltage drops below the overvoltage threshold before the minimum time has elapsed; as well as In response to the minimum time having elapsed and the magnitude of the bus voltage being below the overvoltage threshold, the switch disconnects the dissipation resistor from the bus.

Images