Circuit protection method based on DC bus capacitor, vehicle-mounted controller control system

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 priority to China Patent Application No. 2022102815444, entitled "Circuit protection method based on DC bus capacitor, on-board controller control system," filed with the Patent Office of the State Intellectual Property Administration of China on March 21, 2022, the entire contents of which are incorporated herein by reference.

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

[0003] In the field of on-board compressor control, the high-voltage side is usually powered by the on-board battery, and the input voltage is usually DC 350V, which allows the stable operation of the on-board controller control system. Referring to Figure 1, an AC signal may be superimposed on the high-voltage side input voltage a (i.e., 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] In order to solve the above technical problems, the existing technology proposes the use of a very small capacity bus capacitor to set the resonant frequency of the control circuit significantly outside the 100-100KHz frequency range required by the standard, and this capacitor is a high-voltage ceramic capacitor with good high-frequency characteristics and excellent ripple resistance, so it is not easily damaged when used in the above situation. However, the applicant has found that the small capacity used in this solution causes large ripples in the bus voltage, which limits the output capacity of the compressor, makes it difficult to increase the load capacity of the compressor, and greatly limits the scope of application, making it impossible to meet the needs of practical applications.

[0005] Therefore, the inventors of the present application have decided to seek innovative solutions to solve the above technical problems based on their many years of dedicated research and development experience in the control field. Summary of the Invention

[0006] In view of this, the object of the present invention is to propose a circuit protection method based on a DC bus capacitor, an on-board controller control system, which reliably avoids the resonance problem and ensures the service life and reliability of the circuit of the present application through a simple, inexpensive and reliable solution.

[0007] In the control circuit of the on-board controller, the EMI filter is mainly an inductive component, and the circuit configured with the DC bus capacitor generates the natural oscillation frequency of the control circuit (i.e., generates an oscillatory circuit). When the input voltage with the AC signal superimposed is close to the natural oscillation frequency of the control circuit, it causes resonance between the control circuit and the input signal, and this resonance causes the amplitude value of the oscillation signal to gradually increase, causing serious damage to the control circuit, especially the DC bus capacitor in the circuit to heat up in a short time and cause damage.

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

[0009] A circuit protection method based on a DC bus capacitor, the circuit includes a DC bus capacitor connected to a motor drive module, an MCU is drivingly connected to a motor through the motor drive module, the DC bus capacitor is connected to a DC power supply through a power filter, a diode is connected between the power filter and a positive pole or a negative pole of the 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; When the motor is not running, the switch transistor is in the off state, the switch transistor is in an off state when the voltage of the DC bus capacitor does not exceed a preset threshold when the motor is running, and turns on the switch transistor to release the electric field energy stored in the DC bus capacitor to the DC power source when it is found that the voltage of the DC bus capacitor exceeds the preset threshold.

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

[0011] Preferably, after the interval time of turning on the switch transistor, ensure that the voltage of the DC bus capacitor does not exceed a preset threshold, and turn off the switch transistor, and the MCU selects to send a driving signal to the motor driving module according to a motor operation request.

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

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

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

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

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

[0017] Preferably, an on-board controller control system includes a DC bus capacitor based circuit, the circuit including a DC bus capacitor connected to a motor drive module, an MCU drivingly connected to a motor via the motor drive module, the DC bus capacitor connected to a DC power supply via a power supply filter, and the circuit using a circuit protection method as described above.

[0018] Preferably, the vehicle controller control system includes a high-voltage side power supply and a low-voltage side power supply each electrically connected to the motor drive module, and the high-voltage side power supply uses the DC power supply, where the voltage of the high-voltage side power supply is 100V or more, and the voltage of the low-voltage side power supply is 50V or less.

[0019] In this application, a diode is connected between the power supply filter and the positive or negative pole 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 supply filter, and also blocks the oscillation circuit generated between the DC bus capacitor and the power supply filter, which ultimately ensures that the occurrence of the resonance problem is avoided. Considering that the motor is an inductive load, energy feedback may occur. When the energy reaches the bus, the bus voltage will rise and burn out the DC bus capacitor or the bus device in the motor driving module, this application also simultaneously connects a diode between the positive and negative poles of the MCU 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 the 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, thereby effectively protecting various devices connected to the bus, and a simple, inexpensive and reliable solution is provided to ensure the service life and reliability of the circuit of the present application. [Brief description of the drawings]

[0020] [Figure 1] 2 is a signal diagram of an input voltage a and an input voltage a' obtained by superimposing an AC signal on the input voltage a, in the background art of the present application. [Diagram 2] FIG. 2 is a schematic diagram of a circuit structure in Example 1 of the present application. [Diagram 3] FIG. 2 is a schematic diagram of a circuit structure in Example 2 of the present application. [Figure 4] FIG. 11 is a control timing diagram of a circuit protection method used in the third embodiment of the present application. [Diagram 5] FIG. 11 is a schematic diagram showing the structure of an in-vehicle controller control system according to a third embodiment of the present application (based on the circuit structure of the first embodiment). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 driving module, an MCU is drivingly connected to the motor through the motor driving module, the DC bus capacitor is connected to a DC power supply through a power filter, a diode is connected between the power filter and the positive pole or the negative pole of the DC bus capacitor, and at the same time, a switch transistor driven by the MCU is connected in anti-parallel between the positive pole and the negative pole of the diode, whereby 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, and 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.

[0022] In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces drawings used in the description of the embodiments or the prior art, and it should be understood that the drawings in the following description are only some embodiments described in the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative efforts.

[0023] Example 1: As shown in FIG. 2, this example proposes a protection circuit based on a DC bus capacitor, in which the DC bus capacitor 11 is connected to a DC power supply 13 through a power supply filter 12, and in order to avoid the occurrence of an oscillation circuit between the DC bus capacitor 11 and the power supply filter 12, a diode 14 is connected between the power supply filter 12 and the positive or negative pole of the DC bus capacitor 11 to block the oscillation circuit, thereby avoiding the occurrence of resonance problems; preferably, in this embodiment, the negative pole of the diode 14 is connected to the power supply filter 12, and the positive pole of the diode 14 is connected to the negative pole of the DC bus capacitor 11.

[0024] More preferably, in this embodiment, a switch transistor driven by MCU1 (English abbreviation of Microcontroller Unit) is connected in inverse parallel between the positive and negative electrodes of diode 14, and specifically, in this embodiment, to facilitate the mounting layout, diode 14 and the switch transistor are preferably packaged as a single unit.

[0025] Preferably, in this embodiment, the power supply filter 12 is an EMI (Electric Magnetic Interference) power supply filter, which may be any well-known power supply filter, and specifically, preferably, in this embodiment, the EMI power supply filter includes a common mode choke and a differential mode inductor.

[0026] Preferably, in this embodiment, the switch transistor uses any one of an IGBT15 (an abbreviation of Insulated Gate Bipolar Transistor), a MOS (an abbreviation of MOSFET), and an NPN transistor. Specifically, preferably, in this embodiment, the switch transistor uses an IGBT15, and the IGBT15 and the diode 14 are integrated and packaged as a single unit, where the gate of the IGBT15 is connected to the drive signal of the MCU1, its collector is connected to the negative electrode of the diode 14, and its emitter is connected to the positive electrode of the diode 14, the MCU1 is connected to the IGBT15 via an IGBT drive circuit 2a (which may be of any 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 poles of the DC bus capacitor 11, and at the same time, the MCU 1 sends a driving signal to the IPM module 4, where the IPM module 4 belongs to a bus device connected to the bus as a driving module for the motor 3.

[0028] Example 2: Another technical solution of this Example 2 is similar to that of Example 1, and the difference is that, as shown in FIG. 3, in this Example 2, the positive pole of the diode 14 is connected to the power supply filter 12, the negative pole of the diode 14 is connected to the positive pole of the DC bus capacitor 11, the drive signal of the MCU 1 is connected to the gate of the IGBT 15, its collector is connected to the negative pole of the diode 14, and its emitter is connected to the positive pole of the diode 14.

[0029] Example 3: Further referring to FIG. 4 and shown in FIG. 5 in combination, Example 3 further proposes a circuit protection method for the protection circuit based on the DC bus capacitor 11 according to Example 1 or Example 2, in which the circuit protection method includes: when the motor 3 is not working, turning the IGBT 15 into an off state; when the motor 3 is working, turning the IGBT 15 into an off state if the voltage of the DC bus capacitor 11 does not exceed a preset threshold; when it is found that the voltage of the DC bus capacitor 11 exceeds the preset threshold, the MCU 1 turns on the IGBT 15 via the IGBT driving circuit 2a, and releases the electric field energy stored in the bus capacitor 11 to the DC power source 13; in order to immediately protect the IPM module 4, preferably, turning on the IGBT 15 and turning off the IPM module 4 at the same time.

[0030] Preferably, in order to facilitate the normal operation of the motor 3, in this embodiment, after the interval time of turning on the IGBT 15, ensure that the voltage of the DC bus capacitor 11 does not exceed the preset threshold, and turn off the IGBT 15; the MCU 1 selects to send a driving signal to the IPM module 4 according to the operating requirements of the motor 3; here, preferably, in order to achieve effective protection for 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 value of the DC bus capacitor 11 and the IPM module 4; more preferably, the MCU 1 is connected to the DC bus through a voltage sampling circuit 2b, and is used to detect the voltage of the DC bus capacitor 11 in real time, and compare and judge the voltage of the DC bus capacitor 11 with the preset threshold, and selectively send an IGBT driving signal to the IGBT 15 according to the result of the comparison and judgment.

[0031] When the present application is specifically implemented, an appropriate interval time can be selected while ensuring that the voltage of the DC bus capacitor 11 does not exceed a preset threshold value, and in this embodiment, it is not limited to the only one, and specifically, in this embodiment, the interval time is preferably 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 supply filter 12 and the DC bus capacitor 11, and an IGBT 15 driven by the MCU 1 is connected in inverse parallel between the positive and negative poles of the diode 14, thereby ensuring an effective protection effect for the DC bus capacitor 11 in the circuit, and eliminating the need to specifically limit the capacitance of the DC bus capacitor 11, which can be specifically selected according to actual application needs and has a wide range of application. Preferably, in this embodiment, the capacitance of the DC bus capacitor 11 is 2 to 100 uF, more preferably 2 to 50 uF.

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

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

[0035] Referring further to FIG. 5 , specifically and preferably, in this embodiment, the voltage +HV of the high-voltage power supply HVDC Power is 350V and is connected to the IPM module 4, and at the same time, the low-voltage power supply LVDC Power is connected to an SMPS (English abbreviation for Switching Mode Power Supply) via a low-voltage EMI power supply 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 by six 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 the present application, since the voltage +HV of the high-voltage side power source HVDC Power is 350V, the following device model numbers and related parameters are specifically selected in this embodiment:

[0037] DC bus capacitor 11: Manufacturer: muRata, model number: FHA50Y206KS, capacity: 20uF, withstand voltage: 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 is RGS00TS65E, rated current is 50A, and withstand voltage is 650V.

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

[0041] It should be noted that other structural solutions disclosed in FIG. 4 of the specification of the present application are well known in the field of on-board compressor control and are not considered as innovations of the present application and therefore should not be interpreted as being overly broad.

[0042] In another embodiment, when the voltage +HV of the high-voltage side power source HVDC Power is 750 V, the preset threshold is set to 900 V, and two DC bus capacitor units connected in series can be installed simultaneously, and each bus capacitor unit has a withstand voltage value of 630 V, so that the DC bus capacitor unit has a withstand voltage value of 1260 V, and an IPM module with a withstand voltage value of 1200 V is used. These are general technical choices that a person skilled in the art can make based on the contents described in this application, and are not intended to particularly limit the present application.

[0043] The present invention is not limited to the details of the above exemplary embodiments, and it is obvious to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the present invention. The embodiments are therefore to be considered in all respects as illustrative and non-limiting, and the scope of the present invention is limited by the appended claims, not by the above description, and all modifications that come within the meaning and range of equivalent elements of the claims are intended to be embraced by the present invention. Any reference numerals in the claims should not be considered as limiting the scope of the claims.

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

Claims

1. A circuit protection method based on a DC bus capacitor, the circuit includes a DC bus capacitor connected to a motor drive module, an MCU is drivingly connected to a motor through the motor drive module, the DC bus capacitor is connected to a DC power supply through a power filter, a diode is connected between the power filter and a positive pole or a negative pole of the DC bus capacitor, and at the same time, a switch transistor driven by the MCU is connected in inverse parallel between the positive pole and the negative pole of the diode; When the motor is not running, the switch transistor is in the off state, the switch transistor is in an off state when the voltage of the DC bus capacitor does not exceed a preset threshold when the motor is running, and turns on the switch transistor to release the electric field energy stored in the DC bus capacitor to the DC power source when it is found that the voltage of the DC bus capacitor exceeds the preset threshold.

2. 2. The circuit protection method of claim 1, further comprising turning on the switch transistor and turning off the motor drive module.

3. 3. The circuit protection method as claimed in claim 2, characterized in that after the interval time of turning on the switch transistor, ensure that the voltage of the DC bus capacitor does not exceed a preset threshold, and turn off the switch transistor; and the MCU selects to send a drive signal to the motor drive module according to a motor operation request.

4. 4. The circuit protection method according to claim 3, wherein the interval time is 0.00001 to 2.5 seconds.

5. 2. The circuit protection method according to claim 1, wherein the preset threshold is greater than a rated voltage of the DC power source and less than a withstand voltage value of a DC bus capacitor and a motor driving module.

6. 2. The circuit protection method according to claim 1, wherein the MCU is connected to the DC bus through a voltage sampling circuit, and is used for detecting the voltage of a DC bus capacitor in real time, comparing the voltage of the DC bus capacitor with a preset threshold value, and selectively sending a switch transistor driving signal to the switch transistor according to a result of the comparison.

7. 2. The circuit protection method of claim 1, wherein the positive terminal of the diode is connected to the power supply 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 supply filter and the positive terminal of the diode is connected to the negative terminal of the DC bus capacitor.

8. 2. The circuit protection method as claimed in claim 1, wherein the DC bus capacitor has a capacitance of 2-100uF, and the motor driving module includes an IPM module.

9. 9. An in-vehicle controller control system comprising a DC bus capacitor based circuit, the circuit comprising a DC bus capacitor connected to a motor drive module, an MCU drivingly connected to a motor via the motor drive module, the DC bus capacitor connected to a DC power supply via a power supply filter, the circuit using a circuit protection method according to any one of claims 1 to 8.

10. The vehicle-mounted controller control system according to claim 9, further comprising a high-voltage side power supply and a low-voltage side power supply each electrically connected to the motor drive module, the high-voltage side power supply using the DC power supply, the voltage of the high-voltage side power supply being 100V or more, and the voltage of the low-voltage side power supply being 50V or less.

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