Circuit protection method based on DC bus capacitors, for automotive controller control systems

Abstract

The present invention discloses a circuit protection method based on a DC bus capacitor, and an on-board controller control system, in which a diode is connected between a power supply filter and a positive pole or a negative pole of a DC bus capacitor, and at the same time, a switch transistor driven by an MCU is connected in anti-parallel between the positive pole and the negative pole of the diode, in which when the motor is not working, the switch transistor is in an off state; when the motor is working, if the voltage of the DC bus capacitor does not exceed a preset threshold, the switch transistor is in an off state; when it is found that the voltage of the DC bus capacitor exceeds the preset threshold, the switch transistor is turned on to release the electric field energy stored in the DC bus capacitor to the DC power supply, so that the present invention reliably avoids the resonance problem, and a simple, inexpensive and reliable solution is used to ensure the service life and reliability of the circuit of the present application.

Description

Technical Field

[0001] This application claims the priority of Chinese Patent Application No. 2022102815444, titled "Circuit Protection Method Based on DC Bus Capacitor, Vehicle-mounted Controller Control System", filed with the Patent Office of the State Intellectual Property Office of China on March 21, 2022, and all of its content is incorporated herein by reference.

[0002] The present invention belongs to the field of vehicle-mounted compressor control, specifically relates to a circuit protection method based on a DC bus capacitor, and also relates to a vehicle-mounted controller control system applied to the circuit protection method.

Background Art

[0003] In the field of vehicle-mounted compressor control, usually, the high-voltage side is powered by the vehicle-mounted battery, and the input voltage is usually DC350V, which enables the stable operation of the vehicle-mounted controller control system. Referring to FIG. 1, an AC signal may be superimposed on the high-voltage side input voltage a (i.e., the DC bus voltage) to become the high-voltage side input voltage a', which is mainly due to the fluctuation of the battery output voltage caused by other loads on the vehicle.

[0004] To solve the above technical problems, in the existing technology, in order to greatly deviate the resonance frequency of the control circuit from the frequency range of 100~100KHz required by the standard, the use of a very small-capacity bus capacitor has been proposed. Also, since this capacitor is a high-voltage ceramic capacitor with good high-frequency characteristics and excellent ripple resistance, it is not easily damaged even when used in this scenario. However, the applicant of this application has found that due to the small capacitance used in this solution, the ripple of the bus voltage becomes large, and as a result, the output capacity of the compressor is limited, it is not easy to increase the load capacity of the compressor, the application range is greatly limited, and it cannot meet the actual application needs.

[0005] Therefore, based on many years of dedicated research and development experience in the field of control, the inventor of this application decided to seek an innovative solution to the above technical problem. [Overview of the project]

[0006] In view of this, the object of the present invention is to propose a circuit protection method and an in-vehicle controller control system based on a DC bus capacitor, thereby reliably avoiding resonance problems and ensuring the service life and reliability of the circuit according to this application through a simple, inexpensive, and highly reliable solution.

[0007] In the control circuits of automotive controllers, EMI filters are primarily inductive components, and the circuit, when configured with a DC bus capacitor, generates the control circuit's natural oscillation frequency (i.e., creates an oscillator circuit). When the input voltage, superimposed with an AC signal, is close to the control circuit's natural oscillation frequency, it causes resonance between the control circuit and the input signal. This resonance gradually increases the amplitude of the oscillation signal, causing serious damage to the control circuit, particularly the DC bus capacitor within the circuit, which overheats and breaks down in a short time.

[0008] Therefore, the present invention employs the following technical solutions.

[0009] A circuit protection method based on a DC bus capacitor, wherein the circuit includes a DC bus capacitor connected to a motor drive module, an MCU is drivably connected to the motor via the motor drive module, the DC bus capacitor is connected to a DC power supply via a power filter, a diode is connected between the power filter and the positive or negative terminal of the DC bus capacitor, and a switch transistor driven by the MCU is simultaneously connected in antiparallel between the positive and negative terminals of the diode. When the motor is not operating, the switch transistor is in the off state. A circuit protection method based on a DC bus capacitor, characterized in that when the motor is operating, if the voltage of the DC bus capacitor does not exceed a preset threshold, the switch transistor is in the off state, and when it is determined that the voltage of the DC bus capacitor has exceeded a preset threshold, the switch transistor is turned on and the electric field energy stored in the DC bus capacitor is released to the DC power supply.

[0010] Preferably, the switch transistor is turned on and the motor drive module is turned off.

[0011] Preferably, after an interval of time in which the switch transistor is turned on, the voltage of the DC bus capacitor is ensured not to exceed a preset threshold, the switch transistor is turned off, and the MCU selects to send a drive signal to the motor drive module in response to a motor operation request.

[0012] Preferably, the interval time is 0.00001 to 2.5 seconds.

[0013] Preferably, the preset threshold is greater than the rated voltage of the DC power supply and less than the withstand voltage of the DC bus capacitor and motor drive module.

[0014] Preferably, the MCU is connected to a DC bus via a voltage sampling circuit and is used to detect the voltage of a DC bus capacitor in real time, compare the voltage of the DC bus capacitor with a preset threshold, and selectively transmit a switch transistor drive signal to the switch transistor based on the result of the comparison.

[0015] Preferably, the positive terminal of the diode is connected to the power filter and the negative terminal of the diode is connected to the positive terminal of the DC bus capacitor, or the negative terminal of the diode is connected to the power filter and the positive terminal of the diode is connected to the negative terminal of the DC bus capacitor.

[0016] Preferably, the capacitance of the DC bus capacitor is 2 to 100 uF, and the motor drive module includes an IPM module.

[0017] Preferably, an in-vehicle controller control system, comprising a circuit based on a DC bus capacitor, the circuit comprising a DC bus capacitor connected to a motor drive module, the MCU being drivably connected to a motor via the motor drive module, the DC bus capacitor being connected to a DC power supply via a power filter, and the circuit employing the circuit protection methods described above.

[0018] Preferably, the in-vehicle controller control system includes a high-voltage power supply and a low-voltage power supply electrically connected to the motor drive module, wherein the high-voltage power supply uses a DC power supply, and the voltage of the high-voltage power supply is 100V or higher, and the voltage of the low-voltage power supply is 50V or lower.

[0019] In this application, a diode is connected between the power filter and the positive or negative terminal of the DC bus capacitor. The addition of the diode prevents the electric field energy stored in the DC bus capacitor from being released to the inductive components in the power filter, and further blocks the oscillation circuit that occurs between the DC bus capacitor and the power filter, thus reliably avoiding the occurrence of resonance problems. Considering that the motor is an inductive load and energy feedback may occur, and that when this energy reaches the bus, the bus voltage rises and burns out the DC bus capacitor or the bus device in the motor drive module, this application simultaneously connects the positive and negative terminals of the diode to the MCU A switch transistor driven by is connected in antiparallel, and when the motor is not operating, the switch transistor is in the off state. When the motor is operating, if the voltage of the DC bus capacitor does not exceed a preset threshold, the switch transistor is in the off state. If it is found that the voltage of the DC bus capacitor exceeds a preset threshold, the switch transistor is turned on, and the electric field energy stored in the DC bus capacitor is released to the DC power supply. This effectively protects various devices connected to the bus, and the lifespan and reliability of the circuit according to this application are ensured by a simple, inexpensive, and reliable solution. [Brief explanation of the drawing]

[0020] [Figure 1] This is a signal diagram of input voltage a and input voltage a' obtained by superimposing an AC signal on input voltage a, in the background art of this application. [Figure 2] This is a schematic diagram of the circuit structure in Embodiment 1 of this application. [Figure 3] This is a schematic diagram of the circuit structure in Embodiment 2 of this application. [Figure 4] This is a control timing diagram of the circuit protection method used in Embodiment 3 of this application. [Figure 5] This is a schematic diagram showing the structure of the in-vehicle controller control system in Embodiment 3 of this application (based on the circuit structure of Embodiment 1). [Modes for carrying out the invention]

[0021] An embodiment of the present invention discloses a circuit protection method based on a DC bus capacitor. The circuit includes a DC bus capacitor connected to a motor drive module. The MCU is drivably connected to the motor via the motor drive module. The DC bus capacitor is connected to a DC power supply via a power filter. A diode is connected between the power filter and the positive or negative electrode of the DC bus capacitor. At the same time, a switch transistor driven by the MCU is connected in reverse parallel between the positive and negative electrodes of the diode. Here, when the motor is not operating, the switch transistor is in the off state. When the motor is operating and the voltage of the DC bus capacitor does not exceed a preset threshold, the switch transistor is in the off state. When it is determined that the voltage of the DC bus capacitor has exceeded the preset threshold, the switch transistor is turned on to discharge the electric field energy stored in the DC bus capacitor to the DC power supply.

[0022] To more clearly explain the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the following description of the embodiments or the prior art will be briefly introduced. Of course, the drawings in the following description are only some embodiments described in the present invention. Those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0023] Embodiment 1: As shown in FIG. 2, this embodiment proposes a protection circuit based on a DC bus capacitor. The DC bus capacitor 11 is connected to a DC power supply 13 via a power filter 12. To avoid the generation of an oscillation circuit between the DC bus capacitor 11 and the power filter 12, a diode 14 for blocking the oscillation circuit is connected between the power filter 12 and the positive or negative electrode of the DC bus capacitor 11, thereby avoiding the occurrence of a resonance problem. Preferably, in this embodiment, the negative electrode of the diode 14 is connected to the power filter 12, and the positive electrode of the diode 14 is connected to the negative electrode of the DC bus capacitor 11.

[0024] More preferably, in the present embodiment, a switch transistor driven by an MCU1 (English abbreviation for Microcontroller Unit) is connected in reverse parallel between the positive and negative electrodes of the diode 14. Specifically preferably, in order to facilitate the mounting layout, in the present embodiment, the diode 14 and the switch transistor are integrally packaged.

[0025] Preferably, in the present embodiment, the power filter 12 uses an EMI (English abbreviation for Electric Magnetic Interference) power filter, and any well-known power filter may be used. Specifically preferably, in the present embodiment, the EMI power filter includes a common mode choke and a differential mode inductor.

[0026] Preferably, in the present embodiment, the switch transistor uses any one of an IGBT15 (English abbreviation for Insulated Gate Bipolar Transistor), a MOS (abbreviation for MOSFET) transistor, and an NPN transistor. Specifically preferably, in the present embodiment, the switch transistor uses an IGBT15, and the IGBT15 and the diode 14 are integrated and packaged as a unit. Here, a driving signal of the MCU1 is connected to the gate of the IGBT15, its collector is connected to the negative electrode of the diode 14, its emitter is connected to the positive electrode of the diode 14, and the MCU1 is connected to the IGBT15 via an IGBT driving circuit 2a (which may have any well-known structure). The MCU1 is connected to the DC bus via a voltage sampling circuit 2b and can be used to detect the voltage of the DC bus capacitor 11 in real time in combination with the +HV_Detect signal input shown in FIG. 5.

[0027] Preferably, in this embodiment, an IPM (Intelligent Power Module) module 4 for driving the motor 3 is connected between the positive and negative terminals of the DC bus capacitor 11, and at the same time, the MCU 1 transmits a drive signal to the IPM module 4, where the IPM module 4 belongs to the bus device connected to the bus as the drive module for the motor 3.

[0028] Example 2: Another technical solution in Example 2 is the same as in Example 1, with the difference being as shown in Figure 3. In Example 2, the positive terminal of diode 14 is connected to power filter 12, the negative terminal of diode 14 is connected to the positive terminal of DC bus capacitor 11, the gate of IGBT 15 is connected to the drive signal of MCU 1, its collector is connected to the negative terminal of diode 14, and its emitter is connected to the positive terminal of diode 14.

[0029] Example 3: Further referring to Figure 4 and in conjunction with Figure 5, this Example 3 further proposes a circuit protection method for a protection circuit based on a DC bus capacitor 11 according to Example 1 or Example 2, the circuit protection method includes: turning off the IGBT 15 when the motor 3 is not operating; turning off the IGBT 15 when the motor 3 is operating and the voltage of the DC bus capacitor 11 does not exceed a preset threshold; and when it is determined that the voltage of the DC bus capacitor 11 exceeds a preset threshold, the MCU 1 turns on the IGBT 15 via the IGBT drive circuit 2a and releases the electric field energy stored in the bus capacitor 11 to the DC power supply 13, and preferably, in order to immediately protect the IPM module 4, the IGBT 15 is turned on and the IPM module 4 is turned off at the same time.

[0030] Preferably, in order to facilitate the normal operation of the motor 3, in this embodiment, after an interval of time in which the IGBT 15 is turned on, it is ensured that the voltage of the DC bus capacitor 11 does not exceed a preset threshold, the IGBT 15 is turned off, and the MCU 1 selects to send a drive signal to the IPM module 4 according to the operating requirements of the motor 3. Here, preferably, in order to achieve effective protection to each bus device connected to the bus, in this embodiment, the preset threshold is greater than the rated voltage of the DC power supply 13 and less than the withstand voltage values ​​of the DC bus capacitor 11 and the IPM module 4. More preferably, the MCU 1 is connected to the DC bus via a voltage sampling circuit 2b and is used to detect the voltage of the DC bus capacitor 11 in real time, compare and determine the voltage of the DC bus capacitor 11 with the preset threshold, and selectively send an IGBT drive signal to the IGBT 15 based on the result of the comparison and determination.

[0031] When specifically implementing this application, it is ensured that the voltage of the DC bus capacitor 11 does not exceed a preset threshold, and an appropriate interval time can be selected. In this embodiment, the interval time is not limited to but is specifically preferred to be 0.00001 to 2.5 seconds, more preferably 0.0001 to 1 second, even more preferably 0.0001 to 0.5 seconds, and even more preferably 0.0001 to 0.3 seconds, thereby further ensuring the accuracy of the protection process.

[0032] In this embodiment, a diode 14 is provided between the power filter 12 and the DC bus capacitor 11, and an IGBT 15 driven by the MCU 1 is connected in antiparallel between the positive and negative terminals of the diode 14. This ensures an effective protective effect on the DC bus capacitor 11 in the circuit, eliminates the need to particularly limit the capacitance of the DC bus capacitor 11, and allows for specific selection according to actual application needs, resulting in a wide range of applications. Preferably, in this embodiment, the capacitance of the DC bus capacitor 11 is 2 to 100 uF, more preferably 2 to 50 uF.

[0033] Furthermore, referring to Figure 5, this embodiment further proposes an in-vehicle controller control system 10 including a circuit based on a DC bus capacitor 11, the circuit including a DC bus capacitor 11 connected to an IPM module 4, the MCU 1 being drivably connected to a motor 3 (belonging to an in-vehicle compressor motor) via the IPM module 4, the DC bus capacitor 11 being connected to a DC power supply 13 via an EMI power filter 12, the circuit using the circuit used in Embodiment 1 or 2, and using one or more of the circuit protection methods described in Embodiment 3.

[0034] Preferably, in this embodiment, the in-vehicle controller control system 10 includes a high-voltage side power supply (HVDC Power) and a low-voltage side power supply (LVDC Power) electrically connected to the IPM module 4, wherein the high-voltage side power supply (HVDC Power) uses the DC power supply 13 described in Example 1 or 2, the EMI power filter 12 is used as a high-voltage side power filter, and the low-voltage side power supply (LVDC Power) also uses a DC type power supply, where the voltage of the high-voltage side power supply (HVDC Power) is 100V or higher, and the voltage of the low-voltage side power supply (LVDC Power) is 50V or lower.

[0035] Referring further to Figure 5, in this embodiment, the voltage +HV of the high-voltage side power supply HVDC Power is 350V and is connected to the IPM module 4. At the same time, the low-voltage side power supply LVDC Power is connected to the SMPS (Switching Mode Power Supply) via the low-voltage side EMI power filter 21, and outputs a low-voltage power supply of +15V to the IPM module 4 via the SMPS. The MCU 1 inputs an IGBT-control signal to the IGBT 15 via the IGBT drive circuit 2a, and the drive signal transmitted from the MCU 1 to the IPM module 4 specifically includes 6 PWMs, i.e., PWM drive signals from 6 switch transistors, and the IPM module 4 outputs U, V, and W phase voltage drive signals to the motor 3.

[0036] To further illustrate the technical solution of this application, since the voltage +HV of the high-voltage side power supply HVDC Power is 350V, the following device model numbers and related parameters are specifically selected in this embodiment.

[0037] DC bus capacitor 11: Manufacturer is muRata, model number is FHA50Y206KS, capacitance is 20uF, and voltage rating is 630V.

[0038] EMI power filter 12: Includes a common mode choke CMC and a differential mode inductor DMI, where the common mode choke CMC has an inductance of 1270uH and a rated current of 25A, and the differential mode inductor DMI has an inductance of 3.3uH and a rated current of 26A.

[0039] Diode 14 and IGBT 15 integrated package: Manufacturer is ROHM, model number RGS00TS65E, rated current is 50A, and withstand voltage is 650V.

[0040] The withstand voltage of IPM module 4 is 650V, the preset threshold is 550V, and the interval time is 1s, or 1 second.

[0041] It should be noted that the other structural solutions disclosed in Figure 4 of the specification of this application are well-known in the field of automotive compressor control and are not considered innovative in this application, and therefore should not be interpreted broadly.

[0042] In other embodiments, when the voltage +HV of the high-voltage side power supply HVDC Power is 750V, a preset threshold can be set to 900V, and two DC bus capacitor units connected in series can be installed simultaneously. Since the withstand voltage of each bus capacitor unit is 630V, the withstand voltage of the DC bus capacitor units becomes 1260V, and an IPM module with a withstand voltage of 1200V can be used. These are general technical choices that can be implemented by those skilled in the art based on the contents of this application and are not intended to particularly limit this application.

[0043] The present invention is not limited to the details of the exemplary embodiments described above, and it will be obvious to those skilled in the art that the invention can be realized in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in any respect, and the scope of the invention is limited not by the above description but by the appended claims; thus, all variations falling within the meaning and scope of equivalent elements of the claims are intended to be included in the invention. Any reference number assigned to the claims should not be considered to limit the scope of those claims.

[0044] Furthermore, as can be understood, although this specification is described according to embodiments, each embodiment does not consist of only one distinct technical solution, and such description in this specification is merely for the purpose of clarifying the explanation, and those skilled in the art should view this specification as a whole, and the technical solutions of each embodiment can also be appropriately combined to form other embodiments that will be understood by those skilled in the art.

Claims

1. An in-vehicle controller control system comprising a circuit based on a DC bus capacitor, the circuit comprising a DC bus capacitor connected to a motor drive module, the MCU being drivably connected to a motor via the motor drive module, and the DC bus capacitor being connected to a DC power supply via a power filter. The in-vehicle controller control system includes a high-voltage power supply and a low-voltage power supply electrically connected to the motor drive module, the high-voltage power supply uses a DC power supply, the voltage of the high-voltage power supply is 100V or higher, and the voltage of the low-voltage power supply is 50V or lower. A diode is connected between the power filter and the positive or negative terminal of the DC bus capacitor, and simultaneously, a switch transistor driven by the MCU is connected in antiparallel between the positive and negative terminals of the diode. The MCU is connected to a DC bus via a voltage sampling circuit and is used to detect the voltage of a DC bus capacitor in real time, compare the voltage of the DC bus capacitor with a preset threshold, and selectively transmit a switch transistor drive signal to the switch transistor based on the result of the comparison. The positive terminal of the diode is connected to the power filter, and the negative terminal of the diode is connected to the positive terminal of the DC bus capacitor, or the negative terminal of the diode is connected to the power filter, and the positive terminal of the diode is connected to the negative terminal of the DC bus capacitor. When the motor is not operating, the switch transistor is in the off state. An in-vehicle controller control system based on a DC bus capacitor, characterized in that when the motor is operating, the switch transistor is in the off state if the voltage of the DC bus capacitor does not exceed a preset threshold, and when it is determined that the voltage of the DC bus capacitor has exceeded a preset threshold, the switch transistor is turned on and the electric field energy stored in the DC bus capacitor is released to the DC power supply.

2. The in-vehicle controller control system according to claim 1, characterized in that the switch transistor is turned on and the motor drive module is turned off.

3. The in-vehicle controller control system according to claim 2, characterized in that, after an interval of time in which the switch transistor is turned on, the voltage of the DC bus capacitor does not exceed a preset threshold, the switch transistor is turned off, and the MCU selects to transmit a drive signal to the motor drive module in response to a motor operation request.

4. The in-vehicle controller control system according to claim 3, characterized in that the interval time is 0.00001 to 2.5 seconds.

5. The in-vehicle controller control system according to claim 1, characterized in that the preset threshold is greater than the rated voltage of the DC power supply and less than the withstand voltage value of the DC bus capacitor and the motor drive module.

6. The in-vehicle controller control system according to claim 1, characterized in that the capacitance of the DC bus capacitor is 2 to 100 uF, and the motor drive module includes an IPM module.

7. The in-vehicle controller control system according to claim 6, characterized in that the switch transistor is an IGBT, the MCU is connected to the IGBT via an IGBT drive circuit, and the MCU is connected to the DC bus via a voltage sampling circuit.

8. The in-vehicle controller control system according to claim 7, characterized in that the low-voltage side power supply is connected to the SMPS via a low-voltage side EMI power filter, the low-voltage side power supply outputs to the IPM module via the SMPS, and the MCU inputs an IGBT-control signal to the IGBT via the IGBT drive circuit.

9. The in-vehicle controller control system according to claim 7, characterized in that the IGBT and the diode are packaged together as a single unit.

Images