Method for suppressing current impact of new energy vehicle

Abstract

The invention discloses a method for suppressing current impact of a new energy vehicle, which comprises the following steps that: under a normal condition, an electric driving system operates in a torque control mode, and torque control is carried out based on direct-axis voltage and quadrature-axis voltage; in the torque control mode process, whether the active current short circuit mode condition is met or not is judged; if yes, a transition state is entered, a current impact suppression strategy is started, and the direct-axis voltage and the quadrature-axis voltage are decreased progressively according to the gradient of the direct-axis voltage and the gradient of the quadrature-axis voltage respectively; judging whether the direct-axis voltage and the quadrature-axis voltage are reduced to zero or not; and if yes, quitting the transition state, and entering an active current short-circuit mode. According to the method for suppressing the current impact of the new energy vehicle, the smooth transition of the control current from the torque control mode to the active short-circuit current mode is realized by identifying the boundary from the torque mode to the active short-circuit current mode, starting the current impact suppression strategy and controlling the decreasing gradient change of the direct-axis voltage and the quadrature-axis voltage, and the impact is avoided; hardware is protected, and system failure is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and more specifically, to a method for suppressing current impact in a new energy vehicle. Background Art

[0002] Compared with traditional fuel vehicles, electric vehicles driven by AC motors and hybrid vehicles driven by AC motors and internal combustion engines can effectively reduce environmental pollution. In the electric drive systems of electric vehicles and hybrid vehicles, the motor is connected to a battery that provides power. The AC motor can both output power and recover energy. The regenerative power generated by the AC motor is collected into the battery. Among them, since the battery is a DC power source, an inverter that can convert DC power and AC power into each other is generally required between the battery and the motor, and the current circulates among the battery, the inverter, and the motor.

[0003] However, sometimes there are abnormal situations during normal control. For example, when driving at a stable high-speed current suddenly enters a fault mode, the normal torque control mode will enter the safety processing mode of active short circuit. The general control method is to enter the active short circuit mode from the torque mode. At this time, the current will jump from the torque mode to the active short circuit control mode, causing current impact, affecting the driving experience, and there is a risk of damaging the hardware. At the same time, in severe cases, it will lead to system failure.

[0004] Therefore, there is an urgent need for a method for suppressing current impact in new energy vehicles. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for suppressing current impact in a new energy vehicle to solve the above problems in the prior art, and it can achieve a smooth transition of the control current from the torque control mode to the active short circuit current mode, avoid impact, protect the hardware, and prevent system failure.

[0006] The present invention provides a method for suppressing current impact in a new energy vehicle, which includes:

[0007] Under normal circumstances, the electric drive system operates in the torque control mode, and torque control is performed based on the direct-axis voltage U d and the quadrature-axis voltage U q ;

[0008] During the torque control mode, it is judged whether the active current short circuit mode condition is satisfied;

[0009] If it is satisfied, it enters the transition state, starts the strategy for suppressing current impact, and the direct-axis voltage U d and the quadrature-axis voltage U q decrease respectively at their respective gradients;

[0010] Judge the direct-axis voltage U d and the quadrature-axis voltage U q whether it drops to zero;

[0011] If so, exit the transition state and enter the active current short-circuit mode.

[0012] For the method for suppressing current impact of a new energy vehicle as described above, preferably, in the torque control mode, the motor torque T q in the d-axis coordinate system, the direct-axis voltage U e , and the quadrature-axis voltage U d are calculated respectively by the following formulas: q :

[0013]

[0014] where T e represents the motor torque, represents the number of pole pairs, Ψ m represents the permanent magnet flux linkage, L q represents the quadrature-axis inductance, L d represents the direct-axis inductance, I d represents the direct-axis current, I q represents the quadrature-axis current, U d represents the direct-axis voltage, R s represents the stator resistance, U q is the quadrature-axis voltage, represents the electrical angular velocity.

[0015] For the method for suppressing current impact of a new energy vehicle as described above, preferably, the conditions of the active current short-circuit mode include:

[0016] The vehicle speed is higher than 60 kph, and the motor back electromotive force is at least 10% lower than the bus voltage, or a high-level fault occurs in the electric drive system.

[0017] For the method for suppressing current impact of a new energy vehicle as described above, preferably, the high-level fault includes overcurrent or overvoltage.

[0018] For the method for suppressing current impact of a new energy vehicle as described above, preferably, after entering the transition state, when the strategy for suppressing current impact is started, the direct-axis voltage U d and the quadrature-axis voltage U q decrease respectively at their respective gradients, specifically including:

[0019] The direct-axis voltage U d decreases at the first gradient ΔU d , and the quadrature-axis voltage U q decreases at the second gradient ΔU q where the first gradient ΔUd and the second gradient ΔU q are both calibration values.

[0020] For the method for suppressing current impact of a new energy vehicle as described above, preferably, after entering the transition state, the starting current impact suppression strategy is adopted, and the direct-axis voltage U d and the quadrature-axis voltage U q decrease respectively at their respective gradients, and further include:

[0021] In the transition state, based on the difference between the current and the short-circuit current, the direct-axis voltage U d and the quadrature-axis voltage U q are compensated for decrease at preset time intervals.

[0022] For the method for suppressing current impact of a new energy vehicle as described above, preferably, after entering the active current short-circuit mode, the final short-circuit current of the electric drive system is calculated by the following formula:

[0023] I 短路电流 = Ψ m / L d ,

[0024] wherein, I 短路电流 represents the final short-circuit current, Ψ m represents the permanent magnet flux linkage, and L d represents the direct-axis inductance.

[0025] The present invention provides a method for suppressing current impact of a new energy vehicle. By identifying the boundary between the torque mode and the active short-circuit current mode, starting the current impact suppression strategy, and controlling the decreasing gradient change of the direct-axis voltage U d and the quadrature-axis voltage U q , a smooth transition of the control current from the torque control mode to the active short-circuit current mode is realized, impact is avoided, the hardware is protected, and system failure is prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described below in conjunction with the drawings, wherein:

[0027] Figure 1 is a flowchart of an embodiment of the method for suppressing current impact of a new energy vehicle provided by the present invention. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and in no way limits the present disclosure and its application or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, the compositions of materials, numerical expressions, and numerical values set forth in these embodiments should be construed as merely exemplary and not as limitations.

[0029] The "first", "second", and similar terms used in the present disclosure do not denote any order, quantity, or importance, but are merely used to distinguish different parts. Terms such as "including" or "comprising" mean that the elements before such terms cover the elements listed after such terms and do not exclude the possibility of also covering other elements. Terms such as "upper" and "lower" are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0030] In the present disclosure, when it is described that a specific component is located between a first component and a second component, there may or may not be an intermediate component between the specific component and the first component or the second component. When it is described that a specific component is connected to other components, the specific component may be directly connected to the other components without an intermediate component, or may not be directly connected to the other components and have an intermediate component.

[0031] All terms used in the present disclosure (including technical terms or scientific terms) have the same meaning as understood by those of ordinary skill in the art to which the present disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary, such as those, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense, unless specifically defined as such herein.

[0032] Techniques, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods, and devices should be regarded as part of the specification.

[0033] As Figure 1 shown, in the actual implementation process of the method for suppressing current impact of the new energy vehicle provided in this embodiment, it specifically includes the following steps:

[0034] Step S1: Under normal conditions, the electric drive system operates in a torque control mode and performs torque control based on the direct-axis voltage U d and the quadrature-axis voltage U q

[0035] Among them, in the torque control mode, d is calculated respectively by the following formula q Motor torque T in the d-axis coordinate system e , direct-axis voltage Ud d and quadrature-axis voltage Uq q :

[0036]

[0037] Among them, T e represents the motor torque, represents the number of pole pairs, Ψ m represents the permanent magnet flux linkage, L q represents the quadrature-axis inductance, L d represents the direct-axis inductance, I d represents the direct-axis current, I q represents the quadrature-axis current, U d represents the direct-axis voltage, R s represents the stator resistance, U q is the quadrature-axis voltage, represents the electrical angular velocity.

[0038] Step S2: During the torque control mode, determine whether the active current short-circuit mode condition is satisfied.

[0039] Among them, the active current short-circuit mode condition includes: the vehicle speed is higher than 60 kph, and the motor back electromotive force is at least 10% lower than the bus voltage, or a high-level fault occurs in the electric drive system. In the case of a high-level fault, the electric drive system needs to enter the active short-circuit current protection mode based on the system fault. Specifically, by way of example, the high-level fault includes overcurrent or overvoltage. It should be noted that the present invention does not specifically limit the type of high-level fault.

[0040] Step S3: If satisfied, enter the transition state, start the suppression current impact strategy, and the direct-axis voltage Ud d and the quadrature-axis voltage Uq q decrease respectively at their respective gradients.

[0041] Specifically, the direct-axis voltage Ud d decreases at the first gradient ΔUd d , and the quadrature-axis voltage Uq q decreases at the second gradient ΔUq q , where the first gradient ΔUd d and the second gradient ΔUq q are both calibration values. Among them, the first gradient ΔUd d and the second gradient ΔUq q can be the same or different, and the present invention does not specifically limit this.

[0042] Further, in an embodiment of the present invention, in the transition state, based on the difference between the current current and the short-circuit current, the direct-axis voltage U d and the quadrature-axis voltage U q are compensated by decreasing at preset time intervals. In this way, the direct-axis voltage U d and the quadrature-axis voltage U q can be adjusted in real time according to the difference between the current current and the short-circuit current.

[0043] Step S4: Determine whether the direct-axis voltage U d and the quadrature-axis voltage U q drop to zero.

[0044] Step S5: If so, exit the transition state and enter the active current short-circuit mode.

[0045] Specifically, after entering the active current short-circuit mode, the final short-circuit current of the electric drive system is calculated by the following formula:

[0046] I 短路电流 = Ψ m / L d ,

[0047] where, I 短路电流 represents the final short-circuit current, Ψ m represents the permanent magnet flux linkage, and L d represents the direct-axis inductance.

[0048] The method for suppressing current impact of a new energy vehicle provided by the embodiment of the present invention starts a current impact suppression strategy by identifying the boundary between the torque mode and the active short-circuit current mode, controls the decreasing gradient change of the direct-axis voltage U d and the quadrature-axis voltage U q , realizes the smooth transition of the control current from the torque control mode to the active short-circuit current mode, avoids impact, protects the hardware, and prevents system failure.

[0049] So far, the embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details well known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0050] Although some specific embodiments of the present disclosure have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for the purpose of illustration and not for the purpose of limiting the scope of the present disclosure. Those skilled in the art should understand that the above embodiments can be modified or some technical features can be equivalently replaced without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A method for suppressing current impact in new energy vehicles, characterized in that: include: Under normal circumstances, the electric drive system operates in torque control mode, based on the direct axis voltage U d and the quadrature axis voltage U q Perform torque control; During the torque control mode, determining whether the active current short-circuit mode condition is met; If the condition is satisfied, the system will enter the transition state and start the current impact suppression strategy. The direct axis voltage U d and the quadrature axis voltage U q Decrease with their respective gradients; Determine the direct axis voltage U d and the quadrature axis voltage U q whether it drops to zero; If so, exit the transition state and enter the active current short-circuit mode.

2. The method for suppressing current impact of new energy vehicles according to claim 1, characterized in that: In the torque control mode, d is calculated by the following formulas: q Motor torque T in axis coordinate system e , direct axis voltage U d and the quadrature axis voltage U q : ， Among them, T e represents the motor torque, represents the pole pair number, Ψ m represents the permanent magnet flux, L q Indicates the quadrature-axis inductance, L d represents the direct-axis inductance, I d Indicates the direct axis current, I q Indicates the quadrature axis current, U d represents the direct axis voltage, R s Indicates stator resistance, U q is the quadrature axis voltage, Represents electrical angular velocity.

3. The method for suppressing current impact of new energy vehicles according to claim 1, characterized in that: The active current short-circuit mode conditions include: The vehicle speed is higher than 60kph and the motor back EMF is at least 10% lower than the bus voltage, or a high-level fault occurs in the electric drive system.

4. The method for suppressing current impact of new energy vehicles according to claim 3, characterized in that: The high-level faults include over-current or over-voltage.

5. The method for suppressing current impact of new energy vehicles according to claim 1, characterized in that: After entering the transition state, the current impact suppression strategy is started, and the direct axis voltage U d and the quadrature axis voltage U q They are decreased with their respective gradients, including: Direct axis voltage U d With the first gradient ΔU d Decreasing, quadrature axis voltage U q With the second gradient ΔU q Decreasing, wherein the first gradient ΔU d and the second gradient ΔU q All are calibrated values.

6. The method for suppressing current impact of new energy vehicles according to claim 5, characterized in that: After entering the transition state, the current impact suppression strategy is started, and the direct axis voltage U d and the quadrature axis voltage U q They are decreased with their respective gradients, and also include: In the transition state, based on the difference between the current current and the short-circuit current, the direct-axis voltage U d and the quadrature axis voltage U q Make diminishing compensation.

7. The method for suppressing current impact of new energy vehicles according to claim 1, characterized in that: After entering the active current short-circuit mode, the final short-circuit current of the electric drive system is calculated by the following formula: I 短路电流 =Ψ m / L d , Among them, I 短路电流 represents the final short-circuit current, Ψ m represents the permanent magnet flux, L d Represents the direct-axis inductance.

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