A controller internal pre-charge circuit protection method, circuit and electronic device

Abstract

This invention relates to the field of power electronics technology, specifically to a method, circuit, and electronic device for protecting the pre-charge circuit inside a controller. The method first compares the signal output voltage with a first and second reference voltage, and compares the bus voltage with a third and fourth reference voltage. When the signal output voltage is between the first and second reference voltages, and the bus voltage is between the third and fourth reference voltages, the power output voltage is compared with a fifth and sixth reference voltage. When the power output voltage is between the fifth and sixth reference voltages, the main contactor is activated; otherwise, the main contactor does not activate, and a battery power output terminal abnormality warning is issued. This effectively prevents the pre-charge circuit from being impacted when starting with a high-current load due to a power output circuit fault, thus protecting the pre-charge circuit and other circuits inside the controller.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, specifically to a method, circuit, and electronic device for protecting the internal pre-charge circuit of a controller. Background Technology

[0002] In the internal circuitry of a battery-powered power controller, a pre-charging circuit is typically included to achieve soft-start. Before the battery power output circuit is activated, the battery signal output circuit slowly charges the large-capacity capacitor at the system's backend through the pre-charging circuit, bringing the capacitor voltage close to the power supply voltage. When battery power is required, the capacitor and battery simultaneously supply power at the instant the main contactor closes, thereby reducing the impact on the battery power output circuit and achieving soft-start.

[0003] However, when the battery malfunctions but does not send a fault signal to the MCU, the MCU will normally control the main contactor to close. At this time, the battery signal output terminal, the pre-charge circuit, and the load terminal form a loop. When a large current load occurs at the load terminal, it will cause the battery signal output terminal to output a large current, resulting in damage to the pre-charge circuit. Summary of the Invention

[0004] To address the technical problem that battery power output failures can easily lead to burnout of the pre-charge circuit, this application provides a method, circuit, and electronic device for protecting the internal pre-charge circuit of a controller. The method includes the following steps: Obtain the signal output voltage at the battery signal output terminal, the power output voltage at the battery power output terminal, and the bus voltage; The signal output voltage is compared with the first reference voltage and the second reference voltage, and the bus voltage is compared with the third reference voltage and the fourth reference voltage; When the signal output voltage is between the first reference voltage and the second reference voltage, and the bus voltage is between the third reference voltage and the fourth reference voltage, the power output voltage is compared with the fifth reference voltage and the sixth reference voltage. When the power output voltage is between the fifth and sixth reference voltages, the main contactor is activated; otherwise, the main contactor is not activated and a battery power output terminal abnormality warning is issued.

[0005] The above method achieves accurate monitoring of the pre-charging circuit and power bus functional status by judging the multi-level threshold of the battery signal output voltage, bus voltage and battery power output voltage. Only after ensuring that all key voltage parameters are within the normal operating range is the main contactor coil allowed to engage, thereby effectively avoiding the impact on the pre-charging circuit when starting with a large current load due to a power output circuit fault, and realizing the protection of the pre-charging circuit and other circuits inside the controller.

[0006] Furthermore, the above method also includes issuing a battery signal output voltage too high warning when the signal output voltage is greater than the second reference voltage and the bus voltage is greater than the fourth reference voltage.

[0007] Furthermore, the above method also includes issuing a pre-charging circuit fault warning when the signal output voltage is greater than the second reference voltage and the bus voltage is less than or equal to the third reference voltage.

[0008] Furthermore, the above method also includes issuing a low battery output voltage warning when the signal output voltage is less than the first reference voltage and the bus voltage is less than the third reference voltage.

[0009] This precise fault cause analysis and alerts for different combinations of abnormal voltages can greatly shorten the time maintenance personnel spend troubleshooting, and further improve the convenience and reliability of system maintenance.

[0010] On the other hand, the present invention also provides internal pre-charge circuit protection for the controller, including: The battery includes a signal output terminal and a power output terminal; The main contactor is used to control the on / off state of the circuit busbar; The voltage sampling module is used to acquire the signal output voltage at the battery's signal output terminal, the power output voltage at the battery's power output terminal, and the bus voltage. The MCU unit is used to compare the signal output voltage with a first reference voltage and a second reference voltage, and to compare the bus voltage with a third reference voltage and a fourth reference voltage. When the signal output voltage is between the first reference voltage and the second reference voltage, and the bus voltage is between the third reference voltage and the fourth reference voltage, the pre-charging circuit is deemed to be functioning normally. The power output voltage is then compared with the fifth reference voltage and the sixth reference voltage. When the power output voltage is between the fifth reference voltage and the sixth reference voltage, the battery power output terminal is deemed to be functioning normally, and the main contactor is controlled to engage.

[0011] The circuit provided by this invention can quickly analyze the power circuit status based on the signal output voltage Vdc1 and the bus voltage Vbus. When the power circuit has an abnormal fault and no fault information is received from the battery, the MCU unit can autonomously select whether to execute the main contactor coil energizing action based on the power circuit status. This achieves protection of the pre-charging circuit when the battery's power output terminal outputs a fault. Together with the battery's own system protection measures, this forms a double insurance for the controller's internal circuit, improving the circuit's safety.

[0012] As a further improvement, in the above circuit, the MCU unit is also used to issue a signal output voltage too high warning for the battery when the signal output voltage is greater than the second reference voltage and the bus voltage is greater than the fourth reference voltage.

[0013] As a further improvement, in the above circuit, the MCU unit is also used to issue a pre-charge circuit fault warning when the signal output voltage is greater than the second reference voltage and the bus voltage is less than or equal to the third reference voltage.

[0014] As a further improvement, in the above circuit, the MCU unit is also used to issue a low battery signal output voltage warning when the signal output voltage is less than the first reference voltage and the bus voltage is less than the third reference voltage.

[0015] As a further improvement, in the above circuit, the MCU unit is also used to issue an abnormality prompt at the battery power output terminal when the power output voltage is less than the fifth reference voltage or greater than the sixth reference voltage.

[0016] Through the above fault diagnosis process, the MCU unit can analyze the power circuit status based on the signal output voltage Vdc1 and the bus voltage Vbus, identify different fault types and issue corresponding prompts, quickly narrowing down the fault investigation scope, thereby helping maintenance personnel to quickly troubleshoot and improve maintenance efficiency.

[0017] The present invention also provides an electronic device, including the aforementioned pre-charge circuit protection circuit inside the controller. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the circuit provided by the present invention.

[0019] Figure 2 This is an overall flowchart of the method provided by the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] With the popularization of electrification technology, battery-powered systems are increasingly used in electric vehicles, industrial equipment, and other fields. In such systems, the battery and the motor controller (or power controller) are the two core components, and the reliability of their coordinated operation is directly related to the safety and stability of the entire system.

[0022] To ensure stable and efficient inverter operation, a large-capacity bus capacitor must be connected in parallel on its DC input side (i.e., the DC bus). This serves two purposes: firstly, to provide temporary, instantaneous high current during motor startup; and secondly, to buffer the inrush current generated during power switching or motor braking. Simultaneously, a pre-charge circuit is incorporated in the main power circuit between the battery and the controller to complement this large capacitor. Before the main contactor engages, a current-limiting resistor pre-charges the large-capacity bus capacitor downstream of the controller, preventing damage from the surge current generated by the instantaneous charging of the capacitor when the main contactor closes. The typical workflow is as follows: After system power-on, the battery's signal power output circuit (e.g., DC1+) first supplies power to the control unit (MCU). Subsequently, the MCU controls a pre-charge relay, allowing the battery current to pre-charge the bus capacitor through a current-limiting resistor. When the voltage detection circuit detects that the voltage (Vbus) across the bus capacitor is close to the battery voltage, it indicates that pre-charging is complete. The MCU then issues a command to engage the main power contactor, thus smoothly establishing the entire power supply circuit.

[0023] However, this existing technical solution has a potential safety hazard. When the controller completes the bus pre-charge and issues a command to engage the main contactor, if the battery's main power output circuit (such as DC2+) is unable to output power due to an internal fault (e.g., internal relay failure, power path breakage), but the battery does not report this fault to the controller, and its signal power output circuit (DC1+) continues to supply power normally, the controller's MCU and load system (such as the low-voltage DC / DC module) are already powered on and operating, but the main power circuit has not actually been established. This creates an abnormal power supply circuit: signal power (DC1+) → controller internal pre-charge circuit (pre-charge resistor) → vehicle load (such as DC / DC module, inverter drive circuit, etc.).

[0024] Under these abnormal operating conditions, when the load (such as a vehicle preparing to start) requires a large current, the large current that should be shared by the battery's main power circuit (DC2+) and the already charged bus capacitor will be forced to be supplied entirely by the signal power supply through the low-power current-limiting resistor in the pre-charge circuit. This resistor is designed for a brief pre-charge process and is completely unable to withstand the large current required for normal load operation. It will quickly overheat and burn out due to overcurrent, leading to internal damage to the controller and potentially causing even greater system failures.

[0025] Based on the above analysis, embodiments of the present invention provide a pre-charge circuit protection circuit inside a controller, designed to protect the pre-charge circuit when the battery itself experiences an internal fault without reporting it. (Refer to...) Figure 1 The protection circuit provided in this embodiment of the invention includes: The battery includes a signal output terminal DC1+ and a power output terminal DC2+. The pre-charging circuit is used to supply power to the pre-charging capacitor. The pre-charging circuit includes a current-limiting resistor R1 and a first diode D1 connected in series. The current-limiting resistor R1 is connected to the signal output terminal DC1+ of the battery, and the first diode D1 is connected to the power bus. The main contactor is used to control the on / off state of the power bus. The main contactor's switch is located on the power bus, and the coil is connected to the coil control circuit. The coil control circuit is used to control the coil of the main contactor to engage or disengage according to the control instructions of the MCU unit. The DC / DC module is connected to the DC2+ power output terminal of the battery to supply power to the load. The voltage sampling module is used to acquire the signal output voltage Vdc1 of the battery's signal output terminal DC1+ and the power output voltage Vdc2 of the power output terminal DC2+, as well as the bus voltage Vbus of the power supply bus, and transmits the acquired signal output voltage Vdc1, power output voltage Vdc2, and bus voltage Vbus to the MCU unit. The MCU unit is used to compare the signal output voltage Vdc1 with the first reference voltage Vref1 and the second reference voltage Vref2, and to compare the bus voltage Vbus with the third reference voltage Vref3 and the fourth reference voltage Vref4, and to determine the circuit state based on the comparison results. When Vref1≤Vdc1≤Vref2 and Vref3≤Vbus≤Vref4, the pre-charging circuit and power bus are deemed to be functioning normally, and the next step is executed; otherwise, it indicates that there is a fault in the circuit, and a corresponding fault warning is issued. When Vref1≤Vdc1≤Vref2 and Vref3≤Vbus≤Vref4, the power output voltage Vdc2 is compared with the fifth reference voltage Vref5 and the sixth reference voltage Vref6. When Vref5≤Vdc2+≤Vref6, the battery power output terminal is determined to be normal, and a control command EN is sent to the coil control circuit. The coil control circuit drives the main contactor coil to close, and the MCU unit can control the power output according to the actual load command. Otherwise, it indicates that the battery power output terminal is faulty, the main contactor coil does not close, and an abnormal battery power output terminal prompt is issued.

[0026] Through the above method, the circuit provided by the present invention can quickly analyze the power circuit status based on the signal output voltage Vdc1 and the bus voltage Vbus. When the power circuit has an abnormal fault and no fault information is received from the battery, the MCU unit can autonomously select whether to execute the main contactor coil energizing action based on the power circuit status, thereby realizing the protection of the pre-charging circuit when the battery outputs a fault. Together with the protection measures of the battery system itself, it forms a double insurance for the internal circuit of the controller, improving the safety of the circuit.

[0027] To more clearly illustrate the specific implementation process of this invention, the following detailed description is provided in conjunction with specific circuit parameters and operating scenarios. Assume that in a certain electronic device, the MCU unit uses an STM32F103 microcontroller, whose built-in ADC module (i.e., voltage sampling module) is used to acquire the signal output voltage Vdc1 and the bus voltage Vbus. The fifth reference voltage Vref5 is set to 8V, and the sixth reference voltage Vref6 is set to 12V. When the battery starts supplying power to the system, firstly, the signal output voltage Vdc1 is processed by a voltage divider circuit and input to the MCU's ADC sampling channel. If the value of Vdc1 is stable between Vref1 (e.g., 3V) and Vref2 (e.g., 5V), and simultaneously, the bus voltage Vbus, after being input through another sampling circuit, is within the normal range of Vref3 to Vref4 (e.g., the power output voltage of some electric vehicle batteries is between 280V and 320V, varying depending on the vehicle model), then the MCU unit will initiate the detection of the battery power output voltage Vdc2. Vdc2 is buffered by a voltage follower circuit and then connected to another ADC channel of the MCU. When the MCU detects that the voltage value of Vdc2 fluctuates between 8V and 12V, it immediately determines that the battery power output is working normally and then sends a high-level control command EN to the coil control circuit through its GPIO pin. Upon receiving the EN command, the transistor in the coil control circuit conducts, applying a working voltage to the two ends of the main contactor coil. The coil generates electromagnetic force, driving the normally open contact of the main contactor to close. At this time, the MCU unit can adjust the output voltage and current of the power supply according to the actual commands from the external load, through PWM control or other methods, to meet the power demand of the load. Conversely, if the voltage value of Vdc2 is lower than 8V or higher than 12V during the above detection process, for example, if Vdc2 suddenly drops to 5V due to damage to the battery cell, the MCU unit will determine that there is a fault in the battery's power output terminal. At this time, it will not only not issue an EN command to make the main contactor coil engage, but will also issue a warning signal that the battery power output terminal is abnormal. This effectively avoids the overcurrent damage that the main contactor may cause to the pre-charging resistor, capacitor and other components in the pre-charging circuit if the battery power output is abnormal, thus ensuring the stability and safety of the entire power supply circuit.

[0028] Furthermore, during the above judgment process, when Vdc1 < Vref1 or Vdc1 > Vref2, or when Vbus < Vref3 or Vbus > Vref4, it indicates that there is a fault in the circuit. At this time, the MCU unit will not send the EN instruction to the coil control circuit, and will not make the main contactor coil energize. At the same time, in order to facilitate the maintenance personnel to quickly locate the cause of the fault, the MCU unit of the present invention can further analyze the cause of the fault based on the signal output voltage Vdc1 and the bus voltage Vbus, and issue corresponding prompts.

[0029] Specifically, when Vdc1 > Vref2 and Vbus > Vref4, it indicates that the signal output voltage of the battery is too high, and at the same time the bus voltage also exceeds the preset upper limit. This situation may be due to overvoltage output caused by an abnormal voltage sampling circuit or a fault in the power conversion module in the battery management system. At this time, the MCU unit will control the yellow overvoltage indicator on the device panel to be always on, and display the specific text prompt "Battery overvoltage and bus overvoltage fault" on the connected display screen.

[0030] Specifically, when Vdc1 < Vref1 and Vbus < Vref3, it indicates that the battery signal output voltage is too low and the bus voltage is also lower than the preset lower limit. This is usually related to severely insufficient battery power, cell aging or poor contact of the power supply line. The MCU unit will control the blue undervoltage indicator to flash, and prompt "Battery undervoltage and bus undervoltage fault" on the display screen.

[0031] When Vdc1 > Vref2 but Vbus < Vref3, it means that there is an overvoltage problem at the battery signal output end, but the bus voltage has not reached the normal range. This abnormal combination may be a pre-charge circuit fault. The MCU unit will drive the buzzer to emit intermittent beeps (beep for 2 seconds and stop for 1 second in a cycle), and at the same time the red fault indicator and the yellow overvoltage indicator will flash alternately, and display the fault information "Battery overvoltage but bus undervoltage, please check the pre-charge circuit and load" in detail on the display screen. Through these different fault prompt combinations, the maintenance personnel can quickly narrow down the fault troubleshooting range according to the indicator status and the text description on the display screen, and improve the repair efficiency.

[0032] Once the fault type in the pre-charging circuit or power bus is determined through the above steps, the MCU unit will send the fault type to the external host computer monitoring system via the UART serial port. After receiving the fault information, the host computer will display the corresponding fault code and text description on the display interface. Simultaneously, the MCU unit will store the fault information in its internal Flash memory. Even if the device is powered off and restarted, the fault record will not be lost, facilitating subsequent fault analysis and tracing. Furthermore, in a fault state, the MCU unit will also control the pre-charging relay to remain open, preventing the pre-charging circuit from reactivating before the fault is resolved, further ensuring circuit safety.

[0033] The present invention also provides an electronic device including the aforementioned pre-charge circuit protection circuit within the controller. The electronic device can be an electric vehicle or other battery-powered electronic devices.

[0034] On the other hand, reference Figure 2 This invention also provides a method for protecting the internal pre-charge circuit of a controller, comprising the following steps: S1. Obtain the signal output voltage Vdc1 at the battery signal output terminal, the power output voltage Vdc2 at the battery power output terminal, and the bus voltage Vbus. S2. Compare the signal output voltage Vdc1 with the first reference voltage Vref1 and the second reference voltage Vref2, and compare the bus voltage Vbus with the third reference voltage Vref3 and the fourth reference voltage Vref4. S3. When Vref1≤Vdc1≤Vref2 and Vref3≤Vbus≤Vref4, the pre-charging circuit and power bus are deemed to be functioning normally, and the power output voltage Vdc2 is compared with the fifth reference voltage Vref5 and the sixth reference voltage Vref6. S4. When Vref5≤Vdc2≤Vref6, the battery power output terminal is determined to be normal, and a control command EN is sent to the coil control circuit to control the main contactor coil to engage. Otherwise, the main contactor will not engage and an abnormal battery power output terminal prompt will be issued.

[0035] Through the above steps, this method can accurately monitor the functional states of the pre-charge circuit and the power supply bus by performing multi-level threshold judgments on the voltage at the battery signal output terminal, the bus voltage, and the voltage at the battery power output terminal. When the signal output voltage Vdc1 at the battery signal output terminal and the bus voltage Vbus are not within the normal range, that is, when Vdc1 < Vref1, Vdc1 > Vref2, or Vbus < Vref3, Vbus > Vref4, it indicates that there is a fault in the circuit. In this state, no response is made to the load command, and the main contactor is not allowed to close. Only after ensuring that all key voltage parameters are within the normal operating range is the main contactor coil allowed to close, thus effectively avoiding the impact on the pre-charge circuit when starting a large-current load due to a fault in the power output circuit, protecting the pre-charge circuit and other circuits inside the controller, and significantly improving the safety and stability of the system operation.

[0036] Furthermore, when the signal output voltage Vdc1 and the bus voltage Vbus are not within the normal range, in order to facilitate maintenance personnel to troubleshoot faults in a timely manner and improve maintenance efficiency, the method of the present invention can also analyze the cause of the fault based on the specific magnitudes of the signal output voltage Vdc1 and the bus voltage Vbus and issue corresponding prompts.

[0037] Specifically, when Vdc1 > Vref2 and Vbus > Vref4, it indicates that the signal output voltage of the battery is too high and the bus voltage also exceeds the preset upper limit. At this time, the controller can determine that it is a battery overvoltage fault and immediately issue a "battery overvoltage" prompt signal through a preset alarm module, such as lighting a red fault indicator light and accompanied by a buzzer sound, to remind maintenance personnel to check the output status of the battery pack and the relevant voltage regulation circuit; When Vdc1 < Vref1 and Vbus < Vref3, it indicates that the battery power output voltage is too low and the bus voltage has not reached the normal operating lower limit. The controller will determine that it is a battery undervoltage fault. At this time, the alarm module will issue a "battery undervoltage" prompt, such as lighting a yellow fault indicator light, and at the same time, the specific fault code can be displayed on the display screen of the device to help maintenance personnel quickly locate the source of the problem; If the situation of Vdc1 > Vref2 while Vbus < Vref3 occurs, this abnormal combination of voltage parameters usually means that the battery output voltage is too high, but the bus voltage fails to increase accordingly. It may be due to problems such as damage to the pre-charge resistor in the pre-charge circuit, poor contact of the pre-charge relay contacts, or a serious short circuit on the bus side. The controller will analyze this and issue a fault prompt of "abnormal pre-charge circuit" so that maintenance personnel can focus on checking the component status of the pre-charge loop; Similarly, when Vdc1 < Vref1 and Vbus > Vref4, it indicates that the battery output voltage is insufficient while the bus voltage is abnormally high. This situation may be due to abnormal energy feedback on the bus side or a fault in the voltage sampling circuit, and the controller will also issue a corresponding "abnormal increase in bus voltage" prompt signal.

[0038] Through this precise analysis of the fault causes and prompts for different abnormal voltage combinations, the time for maintenance personnel to troubleshoot faults can be greatly shortened, further improving the maintenance convenience and reliability of the system.

[0039] Finally, the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A controller internal pre-charge circuit protection method, characterized by, Includes the following steps: Obtain the signal output voltage at the battery signal output terminal, the power output voltage at the battery power output terminal, and the bus voltage; The signal output voltage is compared with the first reference voltage and the second reference voltage, and the bus voltage is compared with the third reference voltage and the fourth reference voltage; When the signal output voltage is between the first reference voltage and the second reference voltage, and the bus voltage is between the third reference voltage and the fourth reference voltage, the power output voltage is compared with the fifth reference voltage and the sixth reference voltage. When the power output voltage is between the fifth and sixth reference voltages, the main contactor is activated; otherwise, the main contactor is not activated and a battery power output terminal abnormality warning is issued.

2. The method of claim 1, wherein, The method further includes: When the signal output voltage is greater than the second reference voltage and the bus voltage is greater than the fourth reference voltage, a signal output voltage too high warning is issued for the battery.

3. The method of claim 1, wherein, The method further includes: When the signal output voltage is greater than the second reference voltage and the bus voltage is less than or equal to the third reference voltage, a pre-charging circuit fault warning is issued.

4. The method according to claim 1, characterized in that, The method further includes: When the signal output voltage is less than the first reference voltage and the bus voltage is less than the third reference voltage, a low battery output voltage warning is issued.

5. A pre-charge circuit protection circuit inside a controller, characterized in that, include: The battery includes a signal output terminal and a power output terminal; The main contactor is used to control the on / off state of the circuit busbar; The voltage sampling module is used to acquire the signal output voltage at the battery's signal output terminal, the power output voltage at the battery's power output terminal, and the bus voltage. The MCU unit is used to compare the signal output voltage with a first reference voltage and a second reference voltage, and to compare the bus voltage with a third reference voltage and a fourth reference voltage. When the signal output voltage is between the first reference voltage and the second reference voltage, and the bus voltage is between the third reference voltage and the fourth reference voltage, the pre-charging circuit is deemed to be functioning normally. The power output voltage is then compared with the fifth reference voltage and the sixth reference voltage. When the power output voltage is between the fifth reference voltage and the sixth reference voltage, the battery power output terminal is deemed to be functioning normally, and the main contactor is controlled to engage.

6. The circuit according to claim 5, characterized in that, The MCU unit is also used to issue a signal output voltage too high warning for the battery when the signal output voltage is greater than the second reference voltage and the bus voltage is greater than the fourth reference voltage.

7. The circuit according to claim 5, characterized in that, The MCU unit is also used to issue a pre-charge circuit fault warning when the signal output voltage is greater than the second reference voltage and the bus voltage is less than or equal to the third reference voltage.

8. The circuit according to claim 5, characterized in that, The MCU unit is also used to issue a low battery signal output voltage warning when the signal output voltage is lower than the first reference voltage and the bus voltage is lower than the third reference voltage.

9. The circuit according to claim 5, characterized in that, The MCU unit is also used to issue an abnormal prompt at the battery power output terminal when the power output voltage is less than the fifth reference voltage or greater than the sixth reference voltage.

10. An electronic device, characterized in that, Includes the internal pre-charge circuit protection circuit of the controller as described in any one of claims 5-9.

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