Solid state multi-channel protection circuit

Abstract

A solid state multi-channel protection circuit includes a microcontroller, a current sensor, a plurality of temperature sensors, and first and second multiplexers that selectively connect the current sensor to one of a plurality of solid state devices and each of the plurality of temperature sensors to the microcontroller. The microcontroller selectively controls the second multiplexer to receive a temperature output associated with one of the plurality of solid state devices and selectively controls the first multiplexer to receive a current output related to a measured current associated with the same solid state device, wherein the microcontroller provides overcurrent protection and over-temperature protection based on the received temperature output and the received current output.

Description

[0001] Cross-referencing related applications

[0002] This application claims the benefit and priority of U.S. Provisional Application No. 63 / 212,142, filed June 18, 2021, entitled “SOLID-STATE MULTI-CHANNELPROTECTION CIRCUIT”, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to electrical protection circuits, and more particularly to solid-state protection circuits. Background Technology

[0004] In the automotive industry, as in other industries, electrical systems are becoming increasingly complex and ubiquitous. These systems increasingly rely on power semiconductor devices that can be used in power applications. To provide the required functionality, “smart” power semiconductor devices (such as “smart FETs”) are utilized. These “smart” power semiconductor devices include embedded components (such as charge pumps, current and temperature sensors) and self-protection features to prevent overheating, undervoltage, and overload current. While these devices are robust, one drawback is their limited current (A) carrying capacity. For example, in some automotive applications, these smart FET devices have a maximum current carrying capacity of 15A-18A before entering self-protection mode. Furthermore, connecting smart FETs in parallel is not recommended and therefore cannot be used as a solution for the maximum current carrying capacity of smart FETs. In addition, additional components (such as charge pumps, current and temperature sensors, and self-protection features) increase the cost associated with smart FETs.

[0005] Therefore, it would be beneficial to develop power semiconductor devices that can overcome the shortcomings of traditional smart FET devices while still providing the required robust performance (e.g., self-protection against overheating, undervoltage, and overload current). Summary of the Invention

[0006] The solid-state multichannel protection circuit includes a microcontroller, a current sensor, multiple temperature sensors, and first and second multiplexers. The first and second multiplexers selectively connect the current sensor to one of the multiple solid-state devices and each of the multiple temperature sensors to the microcontroller. The microcontroller selectively controls a second multiplexer to receive a temperature output associated with one of the multiple solid-state devices and selectively controls a first multiplexer to receive a current output associated with a measured current of the same solid-state device. The microcontroller provides overload current protection and overheat protection based on the received temperature output and the received current output.

[0007] According to another aspect, a solid-state multichannel protection circuit includes a microcontroller, a voltage sensor, and a first multiplexer. The voltage sensor is configured to generate a voltage output related to a measured voltage to the microcontroller. The first multiplexer is configured to selectively connect the voltage sensor to one of a plurality of solid-state devices, wherein the voltage sensor generates a voltage output with respect to the selectively connected solid-state device. The microcontroller selectively controls the first multiplexer to receive a voltage output related to a measured voltage output associated with the same solid-state device, wherein the microcontroller provides undervoltage protection based on the received voltage output.

[0008] According to another aspect, a method for providing multi-channel circuit protection includes: controlling a first multiplexer to select a temperature sensor associated with one of a plurality of solid-state devices, and receiving a temperature signal associated with the selected solid-state device at a microcontroller. The method further includes: controlling a second multiplexer to connect a current sensor to the selected solid-state device, wherein the current sensor generates a current output with respect to the selectively connected solid-state device. The microcontroller receives the current output associated with the selected solid-state device and provides overload current and overheat protection based on the received temperature signal and the received current output. Attached Figure Description

[0009] Figure 1 This is a circuit diagram of a solid-state multichannel protection circuit according to some embodiments.

[0010] Figure 2 This is a flowchart illustrating a method of operating a solid-state multichannel protection circuit according to some embodiments. Detailed Implementation

[0011] This disclosure relates to a solid-state multichannel protection circuit comprising multiple solid-state devices (e.g., metal-oxide-semiconductor field-effect transistors or MOSTETs) and a circuit protection circuit system shared by the multiple solid-state devices. The advantage of this configuration is that standard solid-state devices (e.g., MOSFETs excluding integrated circuit protection circuit systems) can be connected in parallel to each other to increase current carrying capacity, and the circuit protection circuit system can be shared by multiple solid-state devices.

[0012] Figure 1This is a circuit diagram 100 of a solid-state multichannel protection circuit according to some embodiments. The solid-state multichannel protection circuit 100 includes multiple solid-state devices Q1-Q8 (e.g., MOSFETs) and a protection circuit 102 shared by the multiple solid-state devices Q1-Q8 (only solid-state devices Q1 and Q8 are shown). In some embodiments, the circuit protection circuit system 102 includes a microcontroller 104, a voltage / current (V / I) sensor 106, BTS circuits 108 and 110, a first multiplexer 112, a second multiplexer 114, a third multiplexer 116, a charge pump 118, and a switching circuit 120.

[0013] In some embodiments, charge pump 118 is shared among multiple solid-state devices Q1-Q8. In some embodiments, charge pump 118 is connected to the drain terminal of each of the multiple solid-state devices (e.g., MOSFETs) Q1-Q8. In some embodiments, multiple high-side solid-state devices are driven by charge pump 118, which is shared by the multiple solid-state devices Q1-Q8. The multiple solid-state devices Q1-Q8 are turned on / off by switching circuit 120. In some embodiments, switching circuit 120 includes multiple individual transistors (e.g., bipolar junction transistors or BJTs), each transistor being connected to the gate terminal of the multiple solid-state devices Q1-Q8. The individual transistors associated with switching circuit 120 are used to selectively turn solid-state devices Q1-Q8 on and off.

[0014] In some embodiments, the circuit protection circuitry system 102 provides shared monitoring of a plurality of solid-state devices Q1-Q8. That is, unlike each solid-state device Q1-Q8 which includes dedicated current, voltage, and / or temperature monitoring, the functionality provided by the circuit protection circuitry system 102 is shared among the plurality of solid-state devices Q1-Q8. For example, in some embodiments, the circuit protection circuitry system 102 includes a single current sensor (e.g., a V / I sensor 106 selectively controlled by microcontroller 104 to operate in either a current monitoring mode or a voltage monitoring mode), which is shared among the plurality of solid-state devices Q1-Q8 via a first multiplexer 112. Furthermore, the circuit protection circuitry may include a single voltage sensor (e.g., a V / I sensor 106 selectively controlled by microcontroller 104 to operate in a voltage monitoring mode), which is shared among the plurality of solid-state devices Q1-Q8 via a second multiplexer 114. In some embodiments, a third multiplexer 116 is configured to receive temperature input from a plurality of temperature sensors (not shown), each temperature sensor being positioned adjacent to one of the plurality of solid-state devices Q1-Q8. In this way, the microcontroller 104 provides overload current, undervoltage, and overheat protection for multiple standard solid-state devices Q1-Q8 without requiring each individual solid-state device to include a dedicated circuit protection system.

[0015] Regarding current sensing, microcontroller 104 selectively operates V / I sensor 106 in current sensing mode and selectively operates first multiplexer 112 to connect V / I sensor 106 across one of the plurality of solid-state devices Q1-Q8 (while simultaneously operating solid-state devices Q1-Q8 in "on" mode). In some embodiments, the junction resistance (e.g., RdsON) of the selected solid-state device is used to calculate the current flowing through the selected solid-state device. The junction resistance of the solid-state device may vary with the temperature of the solid-state device. Microcontroller 104 monitors the temperature of each solid-state device via third multiplexer 116. A lookup table stored by microcontroller 104 is used to determine the junction resistance of each solid-state device Q1-Q8 based on the monitored temperature associated with each solid-state device. The determined junction resistance RdsON is then combined with the voltage sensed by the V / I sensor to determine the current flowing through one of the plurality of solid-state devices Q1-Q8. Based on the measured current, the microcontroller 104 provides overload current protection (i.e., selectively “disconnecting” selected solid-state devices Q1-Q8 in response to the current exceeding a threshold). In some embodiments, the microcontroller sequentially monitors each of the currents (and temperatures) of a plurality of solid-state devices.

[0016] In other embodiments, a dedicated current sensor can be used, which can be selectively connected to directly measure the current flowing through selected solid-state devices Q1-Q8. The advantage of using a V / I sensor 106 configured to measure the voltage across the solid-state devices Q1-Q8 is that the junction resistance of the solid-state devices can be used to calculate the current flowing through the device based on the measured voltage, and no additional resistors or resistor arrays are required. Furthermore, in some embodiments, the sensor for measuring the voltage across the solid-state devices (for current monitoring) can be used to provide undervoltage protection.

[0017] In some embodiments, the microcontroller 104 also combines a V / I sensor 106 (operating in voltage monitoring mode) with a second multiplexer 114 to provide undervoltage circuit protection for each of the plurality of solid-state devices Q1-Q8. However, in some embodiments, a dedicated voltage monitoring circuit (separate from the current monitoring circuit) may be combined with the second multiplexer 114. The monitored output voltage associated with each of the plurality of solid-state devices Q1-Q8 is used to detect an open-circuit load or battery short circuit when that solid-state device is in an off state. In some embodiments, the undervoltage condition is transmitted to the system via a CAN bus 122. Undervoltage monitoring requires the monitored solid-state device to be off, unlike overload current monitoring which requires the solid-state device to be on. In some embodiments, overload current detection and undervoltage detection may operate simultaneously on different solid-state devices Q1-Q8, depending on the on / off state of the respective solid-state switches Q1-Q8. Based on the measured voltage, the microcontroller 104 provides undervoltage circuit protection (i.e., selectively “disconnecting” selected solid-state devices Q1-Q8 in response to the voltage dropping below a threshold).

[0018] Figure 2 This is a flowchart illustrating a method of operating a solid-state multichannel protection circuit according to some embodiments. References Figure 1 The components shown.

[0019] At step 200, microcontroller 104 controls third multiplexer 116 to select a temperature sensor associated with one of a plurality of solid-state devices. As described above, each of the plurality of temperature sensors is positioned close to each of the plurality of solid-state devices such that the measured temperature represents the temperature of solid-state devices Q1-Q8. At step 202, microcontroller 104 receives the temperature signal associated with the selected solid-state devices Q1-Q8 via third multiplexer 116. At step 204, microcontroller 104 provides overheat protection based on the received temperature signal. For example, in some embodiments, this may include comparing the received temperature signal with a threshold. If the received temperature signal is greater than the threshold, the microcontroller may disconnect the solid-state devices Q1-Q8 associated with the received temperature signal.

[0020] At step 206, the received temperature signal associated with one of the plurality of solid-state devices Q1-Q8 is used to calculate the junction resistance associated with a particular solid-state device Q1-Q8. In some embodiments, measuring the current associated with the solid-state device to provide overload current protection requires combining the junction resistance of the solid-state device with a measured voltage across the solid-state device to calculate the current flowing through the device. The junction resistance is proportional to the temperature of the solid-state device, and therefore determining the temperature of the solid-state device can improve the accuracy of the measured current. In some embodiments, the microcontroller 104 measures the temperature of a particular solid-state device Q1-Q8 before or immediately after measuring the current through the solid-state devices Q1-Q8. In some embodiments, the microcontroller 104 includes a lookup table for associating the measured temperature with the junction resistance.

[0021] At step 208, microcontroller 104 controls first multiplexer 112 to connect V / I sensor 106 to selected solid-state devices Q1-Q8. In some embodiments, overload current protection is provided only to the on or off solid-state devices Q1-Q8. In some embodiments, the microcontroller will only control first multiplexer 112 to connect V / I sensor 106 to selected solid-state devices Q1-Q8 that are currently on. In some embodiments, microcontroller 104 communicates with switching circuit 120 to determine the on / off state of each of the plurality of solid-state devices Q1-Q8. In some embodiments, V / I sensor 106 is a current sensor configured to measure the current through the selected solid-state devices Q1-Q8. In other embodiments, V / I sensor 106 is a voltage sensor configured to measure the voltage across the selected solid-state devices Q1-Q8. As described above, Figure 1 One of the benefits of the multi-channel protection circuit shown is that a single V / I sensor 106 can be used to provide overload current and / or undervoltage protection monitoring for multiple solid-state devices Q1-Q8.

[0022] At step 210, assuming the V / I sensor 106 is a voltage sensor, the microcontroller 104 receives the voltage measured by the V / I sensor 106 across the junction of the selected solid-state device. Based on the junction resistance (calculated at step 206 based on the measured temperature of the solid-state device) and the voltage measurement across the junction of the selected solid-state device, the current through the solid-state device is determined.

[0023] At step 212, the microcontroller 104 provides overload current protection based on a measured current flowing through the solid-state device. In some embodiments, this includes comparing the measured current to a threshold. If the measured current is greater than the threshold, the microcontroller 104 instructs the switching circuit 120 to disconnect the corresponding solid-state switch. In some embodiments, the microcontroller 104 requires the measured current to exceed the threshold for a defined time period. In some embodiments, the defined time period depends on the magnitude of the measured current. For example, a large measured current exceeding the threshold may only require a short time period to trigger an overload current condition. Conversely, a small measured current exceeding the threshold may require a longer time period to trigger overload current protection.

[0024] At step 214, microcontroller 104 controls second multiplexer 114 to connect V / I sensor 106 to measure the output voltage of one of a plurality of solid-state devices Q1-Q8. In some embodiments, V / I sensor 106 is used to measure both the voltage across the selected solid-state device Q1-Q8 (for overload current protection) and the output voltage associated with the selected solid-state device (for undervoltage protection). Overload current protection is provided when the selected solid-state device Q1-Q8 is on or conducting. Conversely, undervoltage protection is provided when the selected solid-state device Q1-Q8 is off or not conducting.

[0025] At step 216, microcontroller 104 receives the voltage measured by V / I sensors 106 at the output of the selected solid-state devices Q1-Q8. At step 218, microcontroller 104 compares the measured output voltage with a threshold. If the measured voltage is less than the threshold, this indicates an undervoltage condition (e.g., an open-circuit load or short-circuit condition). In some embodiments, in response to a detected undervoltage condition, microcontroller 104 transmits the detected condition to the system via CAN bus 122.

[0026] While the invention has been described with reference to one or more exemplary embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted for elements therein without departing from the scope of the invention. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the invention without departing from its essential scope. Therefore, the invention is not limited to the one or more specific embodiments disclosed, but rather encompasses all embodiments falling within the scope of the appended claims.

Claims

1. A solid-state multi-channel protection circuit, comprising: microcontroller; A voltage / current sensor configured to generate a current output related to a measured current to the microcontroller, and configured to generate a voltage output related to a measured voltage to the microcontroller; A first multiplexer is configured to selectively connect the voltage / current sensor to one of a plurality of solid-state devices operating in an on-state, wherein the voltage / current sensor generates the current output with respect to the selectively connected solid-state device; Multiple temperature sensors, each of which is configured to provide a temperature output related to the measured temperature, are located in the vicinity of one of the multiple solid-state devices; A second multiplexer is configured to selectively provide the microcontroller with the temperature output measured by each of the plurality of temperature sensors; as well as A third multiplexer is configured to selectively connect the voltage / current sensor to one of the plurality of solid-state devices, wherein the voltage / current sensor generates a voltage output with respect to the selectively connected solid-state device operating in an off state; The microcontroller selectively controls the second multiplexer to receive a temperature output associated with one of the plurality of solid-state devices, and selectively controls the first multiplexer to receive a current output associated with a measured current of the same solid-state device operating in the ON state. The microcontroller provides overload current protection and overheat protection based on the received temperature output and the received current output. The microcontroller selectively controls the third multiplexer to receive a voltage output associated with one of the plurality of solid-state devices operating in the OFF state. The microcontroller provides undervoltage protection based on the received voltage output.

2. The solid-state multi-channel protection circuit as described in claim 1, characterized in that, The voltage / current sensor is selectively controlled by the microcontroller to operate in a first mode to measure current and in a second mode to measure voltage.

3. The solid-state multi-channel protection circuit as described in claim 2, characterized in that, In the first mode, the voltage / current sensor is selectively connected to measure the voltage across one of the plurality of solid-state devices.

4. The solid-state multi-channel protection circuit as described in claim 3, characterized in that, The microcontroller includes a lookup table that associates the measured temperature with the junction resistance of the solid-state devices, wherein the junction resistance is used by the controller to calculate the current based on the measured voltage across one of the plurality of solid-state devices and the junction resistance associated with the measured temperature.

5. The solid-state multi-channel protection circuit as described in claim 2, characterized in that, In the second mode, the voltage / current sensor is selectively connected to measure the output voltage associated with one of the plurality of solid-state devices.

6. The solid-state multi-channel protection circuit as described in claim 1, characterized in that, It further includes a charge pump, which is connected to be shared by each of the plurality of solid-state devices.

7. The solid-state multi-channel protection circuit as described in claim 1, characterized in that, The multiple solid-state devices are connected in parallel with each other.

8. The solid-state multi-channel protection circuit as described in claim 1, characterized in that, Further includes: A switching circuit is connected to each of the plurality of solid-state devices, wherein the switching circuit is configured to selectively control the on / off state of the plurality of solid-state devices; The microcontroller communicates with the switching circuit to selectively control the on / off state of the plurality of solid-state devices.

9. The solid-state multi-channel protection circuit as described in claim 8, characterized in that, When the microcontroller receives a current output associated with the solid-state device, it controls the solid-state device to be turned on.

10. A method for providing multi-channel circuit protection, the method comprising: Control the first multiplexer to select a temperature sensor associated with one of a plurality of solid-state devices; The microcontroller receives the temperature signal associated with the selected solid-state device. A second multiplexer is controlled to connect a voltage / current sensor to the selected solid-state device operating in the ON state, wherein the voltage / current sensor generates a current output with respect to the selectively connected solid-state device; The microcontroller receives a current output associated with the selected solid-state device operating in the ON state; A third multiplexer is controlled to connect the voltage / current sensor to the output of one of the plurality of solid-state devices operating in a disconnected state, wherein the voltage / current sensor generates a voltage output with respect to the selectively connected solid-state device; as well as Overload current protection is provided based on the current output of the solid-state device, undervoltage protection is provided based on the voltage output of the selected solid-state device operating in the off state, and overheat protection is provided based on the received temperature signal and the received current output.

11. The method as described in claim 10, characterized in that, The current sensor in the voltage / current sensor is configured to measure the voltage across the solid-state device when it is in the ON state.

12. The method as described in claim 10, characterized in that, Further includes: The junction resistance associated with the selected solid-state device is calculated based on the received temperature signal; as well as The current flowing through the selected solid-state device is calculated based on the measured voltage across the solid-state device and the junction resistance.

13. The method as described in claim 10, characterized in that, Further includes: Before the current sensor generates a current output, a control switching circuit is used to selectively turn on the selected solid-state device.

14. The method as described in claim 10, characterized in that, The voltage / current sensor is selectively controlled by the microcontroller to operate in a first mode to measure current and in a second mode to measure voltage.

15. The method as described in claim 10, characterized in that, Further includes: If the output voltage of the selected solid-state device is less than a threshold, the detected undervoltage condition is transmitted.

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