Method for Determining Coolant Flow Rate of Motor Controller

Abstract

The present invention provides a method for determining the coolant flow rate of a motor controller. The determination method includes establishing a 2D table corresponding to the power loss of the motor controller, the operating voltage of the motor controller, and the operating current; obtaining the operating voltage and the operating current of the motor controller, and determining the power loss of the motor controller by means of online table lookup; and determining the coolant flow rate of the motor controller according to the determined power loss of the motor controller. The method for determining the coolant flow rate of the motor controller according to the present invention determines the coolant flow rate based on the power loss of the motor controller, which can make the coolant flow rate correspond to the power loss of the motor controller. Therefore, not only can the cooling requirement of the motor controller be met, but also the cooling water pump can be prevented from running at high power all the time, and thus a better power saving effect can be achieved, which is beneficial to improving the cruising range of new energy vehicles.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and particularly relates to a method for determining the coolant flow rate of a motor controller. Background Art

[0002] The electric drive system is one of the core components of new energy vehicles. The electric drive system consists of a motor and its controller, which to a certain extent determines the safety, economy, environmental protection, etc. of electric vehicles. In the electric drive system, the heat dissipation design plays a crucial role in the reliable operation of pure electric vehicles. If there is local overheating in the electric drive system, it is easy to cause the power devices to be damaged due to thermal fatigue, thus affecting the performance of the whole vehicle.

[0003] The internal heat source of the motor controller of new energy vehicles is mainly the loss of power semiconductor devices (IGBT, freewheeling diodes, etc.). If the coolant cannot take away the generated heat in time, it will lead to poor local heat dissipation of the controller, resulting in a high temperature rise of the controller. And the power devices are sensitive to temperature. The change of the device junction temperature will affect the turn-on and turn-off processes of the device, affect the performance of the controller, and further affect the service life of the controller and reduce the reliability of the system.

[0004] Currently, the cooling systems of new energy vehicles mostly use a fixed large flow rate to cool the electric drive system. The coolant pump has been running at high power. Although it can meet the cooling requirements of the motor controller, it will also increase the power consumption and reduce the driving range of the vehicle. Summary of the Invention

[0005] In view of this, the present invention aims to propose a method for determining the coolant flow rate of a motor controller, which has a good power-saving effect and is beneficial to improving the driving range of new energy vehicles.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] A method for determining the coolant flow rate of a motor controller, the determination method includes:

[0008] Establish a 2D table corresponding to the power loss of the motor controller, the operating voltage of the motor controller, and the operating current;

[0009] Obtain the operating voltage and operating current of the motor controller, and determine the power loss of the motor controller by looking up the table online;

[0010] Determine the coolant flow rate of the motor controller according to the determined power loss of the motor controller;

[0011] Among them, the power loss of the motor controller at least includes power module loss, DC-link capacitor loss, and bus loss. The operating voltage and operating current of the motor controller are the average voltage and average current within the operating cycle T of the motor controller, respectively.

[0012] Further, the power module loss includes IGBT loss and freewheeling diode loss, and both the IGBT loss and the freewheeling diode loss are obtained through the established simulink model corresponding to the operating voltage V DC and operating current I ph of the motor controller.

[0013] Further, the IGBT loss includes IGBT switching loss P IGBT-switch and IGBT conduction loss P IGBT-conduct , and in the established simulink model:

[0014] The IGBT switching loss P IGBT-switch satisfies:

[0015]

[0016] The IGBT conduction loss P IGBT-conduct satisfies:

[0017]

[0018] Among them, K IGBT-switch and K IGBT-conduct represent correction factors, f represents the switching frequency, E IGBT-ON represents the energy lost during one IGBT turn-on under the reference voltage and reference current, E IGBT-OFF represents the energy lost during one IGBT turn-off under the reference voltage and reference current, V Ref represents the reference voltage, I Ref represents the reference current, D represents the duty cycle, V CE represents the voltage between the collector and emitter of the IGBT, r CE represents the resistance between the collector and emitter of the IGBT.

[0019] Further, the freewheeling diode loss includes freewheeling diode switching loss P Diobe-switch and freewheeling diode conduction loss P Diobe-conduct , and in the established simulink model:

[0020] The freewheeling diode switching loss P Diobe-switch satisfies:

[0021]

[0022] The conduction loss P of the freewheeling diode Diobe-conduct Satisfies:

[0023]

[0024] Wherein, K Diobe-switch And K Diobe-conduct Represent correction factors, f represents the switching frequency, E Diobe-ON Represents the energy lost in one turn-on of the freewheeling diode under the reference voltage and reference current, E Diobe-OFF Represents the energy lost in one turn-off of the freewheeling diode under the reference voltage and reference current, V Ref Represents the reference voltage, I Ref Represents the reference current, D represents the duty cycle, V Diobe Represents the voltage across the freewheeling diode, r Diobe Represents the resistance value of the freewheeling diode.

[0025] Furthermore, in the established Simulink model, the K IGBT-switch And the K IGBT-conduct , and the K Diobe-switch And the K Diobe-conduct Are all obtained by establishing a corresponding 2D table between the correction factor and the working voltage V DC And the working current I ph And through the method of online table lookup.

[0026] Furthermore, the IGBT switching loss P IGBT-switch In the And the freewheeling diode switching loss P Diobe-switch In the Are all obtained by establishing a corresponding 2D table between each other and the working voltage V DC And the working current I ph And through the method of online table lookup.

[0027] Furthermore, in the IGBT conduction loss P IGBT-conduct , the V CE And the r CE Are all obtained by establishing a corresponding 1D table between each other and the IGBT temperature, and through the method of online table lookup.

[0028] Furthermore, in the established Simulink model, if the motor controller is in the active short-circuit working state, the IGBT switching loss P IGBT-switch And the freewheeling diode switching loss P Diobe-switch Are 0.

[0029] Further, both the DC-link capacitor loss and the bus loss are obtained through P = R·I 2 where P represents the DC-link capacitor loss or the loss of the bus, R represents the resistance of the DC-link capacitor loss or the bus, and I represents the operating current of the DC-link capacitor loss or the bus.

[0030] Further, the determination of the coolant flow rate of the motor controller is to establish a corresponding 2D table between the power loss of the motor controller and the coolant flow rate, and determine the coolant flow rate of the motor controller by looking up the table online according to the determined power loss of the motor controller.

[0031] Compared with the prior art, the method for determining the coolant flow rate of the motor controller of the present invention has the following advantages:

[0032] The method for determining the coolant flow rate of the motor controller according to the present invention determines the coolant flow rate based on the power loss of the motor controller, which can make the coolant flow rate correspond to the power loss of the motor controller. Therefore, not only can the cooling requirement of the motor controller be met, but also the cooling water pump can be prevented from running at high power all the time, and a better power saving effect can be achieved, which is beneficial to improving the cruising range of new energy vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0034] Figure 1 is a schematic diagram of the simulink model described in the embodiment of the present invention;

[0035] Figure 2 is Figure 1 a partial enlarged view of the upper left part of

[0036] Figure 3 is Figure 1 a partial enlarged view of the lower left part of

[0037] Figure 4 is Figure 1 a partial enlarged view of the upper right part of

[0038] Figure 5 is Figure 1 a partial enlarged view of the lower right part of DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0040] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0041] This embodiment relates to a method for determining the coolant flow rate of a motor controller. In terms of the overall design, the determination method includes the following steps:

[0042] S1. Establish a 2D table corresponding to the power loss of the motor controller, the operating voltage of the motor controller, and the operating current;

[0043] S2. Obtain the operating voltage and operating current of the motor controller, and determine the power loss of the motor controller by looking up the table online;

[0044] S3. Determine the coolant flow rate of the motor controller according to the determined power loss of the motor controller.

[0045] Among them, in this embodiment, the power loss of the above-mentioned motor controller at least includes power module loss, DC-link capacitor loss, and bus loss. Moreover, in the above determination method, the operating voltage and operating current of the motor controller are specifically the average voltage and average current within the operating cycle T of the motor controller.

[0046] At this time, for the acquisition of the above average voltage and average current, generally, the number of samples N within the operating cycle T of the motor controller can be calculated, and the voltages and currents obtained from the N samples are accumulated to obtain the total voltage value and the total current value. Then, the total voltage value and the total current value are divided by the number of samples N to obtain the average voltage and the average current respectively.

[0047] In this embodiment, in detail, the above-mentioned power module loss generally includes IGBT loss and freewheeling diode loss, and in terms of specific acquisition, both the IGBT loss and the freewheeling diode loss are also obtained through the simulink model established for the IGBT loss, the freewheeling diode loss, the operating voltage V of the motor controller DC and the operating current I ph corresponding thereto.

[0048] At this time, specifically, the IGBT loss includes the IGBT switching loss P IGBT-switch and the IGBT conduction loss P IGBT-conduct , and in the established simulink model:

[0049] The IGBT switching loss P IGBT-switch satisfies:

[0050]

[0051] The IGBT conduction loss P IGBT-conduct then satisfies:

[0052]

[0053] Meanwhile, in the formulas satisfied by the IGBT switching loss P IGBT-switch and the IGBT conduction loss P IGBT-conduct where K IGBT-switch and K IGBT-conduct represent correction factors, f represents the switching frequency, E IGBT-ON represents the energy lost during one turn-on of the IGBT under the reference voltage and reference current, E IGBT-OFF represents the energy lost during one turn-off of the IGBT under the reference voltage and reference current, V Ref represents the reference voltage, I Ref represents the reference current, D represents the duty cycle, V CE represents the voltage between the collector and emitter of the IGBT, r CE represents the resistance between the collector and emitter of the IGBT.

[0054] Similar to the IGBT loss, the freewheeling diode loss also includes the freewheeling diode switching loss P Diobe-switch and the freewheeling diode conduction loss P Diobe-conduct , and correspondingly, in the built Simulink model:

[0055] The freewheeling diode switching loss P Diobe-switch also satisfies:

[0056]

[0057] The freewheeling diode conduction loss P Diobe-conduct then satisfies:

[0058]

[0059] Meanwhile, in the formulas satisfied by the above freewheeling diode switching loss P Diobe-switch and the freewheeling diode conduction loss P Diobe-conduct where K Diobe-switch and K Diobe-conduct represent correction factors, f represents the switching frequency, E Diobe-ON represents the energy lost during one turn-on of the freewheeling diode under the reference voltage and reference current, E Diobe-OFF represents the energy lost during one turn-off of the freewheeling diode under the reference voltage and reference current, V Ref represents the reference voltage, I Ref represents the reference current, D represents the duty cycle, V Diobe represents the voltage across the freewheeling diode, r Diobe represents the resistance of the freewheeling diode.

[0060] In this embodiment, based on the above formulas and combined with Figure 1 and Figures 2 to 5 shown in, in the established Simulink model, K IGBT-switch and K IGBT-conduct , and K Diobe-switch and K Diobe-conduct can all be obtained by establishing a corresponding 2D table between the correction coefficient and the working voltage V DC and the working current I ph and through the method of online table lookup.

[0061] Similarly, for the IGBT-switch in the IGBT switching loss P and the Diobe-switch in the freewheeling diode switching loss P they are also all obtained by establishing a corresponding 2D table between each other and the working voltage V DC and the working current I ph and through the method of online table lookup.

[0062] At this time, for the corresponding 2D table between each correction coefficient and the working voltage V DC and the working current I ph it can be obtained by actual measurement and comparison. And in and, E , E IGBT-ON , E IGBT-OFF , E Diobe , V Ref , I Ref etc. can be obtained by referring to the product data manual attached to the power product, and the corresponding 2D table between these two parts and the working voltage V DC and the working current I ph is also usually obtained by actual measurement and calibration.

[0063] In this embodiment, in view of the fact that the V CE and r CE of the IGBT are easily affected by the IGBT temperature. Therefore, in the IGBT conduction loss P IGBT-conduct , V CE and r CE can also be obtained by establishing a corresponding 1D table between each other and the IGBT temperature and through the method of online table lookup. And the corresponding 1D table between V CE and r CE and the IGBT temperature can be obtained by actual measurement and calibration.

[0064] In addition, when the motor controller is in the active short - circuit state, the IGBT will turn on 3 upper or lower tubes simultaneously. At this time, there is no switching loss, but only conduction loss. Therefore, in the simulink model built in this embodiment, it is also specifically set that if the motor controller is in the active short - circuit working state, that is, when the ASC is triggered, the IGBT switching loss P IGBT-switch and the free - wheeling diode switching loss P Diobe-switch are 0.

[0065] Through the simulink model built in this embodiment, during the operation of the motor controller, the IGBT loss P loss-IGBT and the free - wheeling diode loss P loss-Diobe can be obtained from the working voltage and working current of the motor controller. Then, by adding the two, the loss of the overall power module can be obtained.

[0066] In this embodiment, for the DC - link capacitor loss and the bus loss, both are specifically obtained through the formula P = R·I 2 . In this formula, P represents the DC - link capacitor loss or the bus loss, R represents the DC - link capacitor loss or the bus resistance, and I represents the working current of the DC - link capacitor or the bus. Among them, the DC - link capacitor loss and the bus resistance can be obtained through actual measurement or from the product description, while the working current of the DC - link capacitor or the bus can be obtained through acquisition.

[0067] In this embodiment, as described above, by separately obtaining the power module loss, as well as the DC - link capacitor loss and the bus loss, the power loss of the motor controller can be obtained. At this time, according to the power loss of the motor controller, the corresponding coolant flow rate can be obtained.

[0068] Moreover, as a preferred implementation form, in the determination of the coolant flow rate, similar to the above - described obtaining method, in this embodiment, the determination of the coolant flow rate can also be designed to establish a corresponding 2D table between the power loss of the motor controller and the coolant flow rate, and determine the coolant flow rate of the motor controller by looking up the table online according to the determined power loss of the motor controller. At this time, the corresponding 2D table between the power loss of the motor controller and the coolant flow rate can still be obtained through actual measurement and calibration.

[0069] The method for determining the coolant flow rate of the motor controller in this embodiment, which determines the coolant flow rate based on the power loss of the motor controller, can make the coolant flow rate correspond to the power loss of the motor controller. Thus, it can not only meet the cooling requirements of the motor controller, but also avoid the cooling water pump running at high power all the time, having a good power - saving effect, being beneficial to improving the cruising range of new - energy vehicles, and having good practicability.

[0070] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, 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 method for determining the coolant flow rate of a motor controller, characterized in that The determination method includes: Establishing a corresponding 2D table between the power loss of the motor controller, the operating voltage of the motor controller, and the operating current; Obtaining the operating voltage and operating current of the motor controller, and determining the power loss of the motor controller by means of online table lookup; Determining the coolant flow rate of the motor controller according to the determined power loss of the motor controller; Wherein, the power loss of the motor controller at least includes power module loss, DC-link capacitor loss, and bus loss, and the operating voltage and operating current of the motor controller are respectively the average voltage and average current within the operating cycle T of the motor controller; The power module losses include IGBT losses and freewheeling diode losses, and both the IGBT losses and the freewheeling diode losses are obtained through the established simulink model corresponding to the operating voltage V DC and the operating current I ph of the motor controller; The determination of the coolant flow rate of the motor controller is to establish a corresponding 2D table between the power loss of the motor controller and the coolant flow rate, and determine the coolant flow rate of the motor controller by means of online table lookup according to the determined power loss of the motor controller.

2. The method for determining the coolant flow rate of the motor controller according to claim 1, wherein: The IGBT losses include the IGBT switching loss P IGBT-switch and the IGBT conduction loss P IGBT-conduct , and in the established Simulink model: The IGBT switching loss P IGBT-switch Satisfies: The IGBT conduction loss P IGBT-conduct satisfies: Among them, K IGBT-switch and K IGBT-conduct represent correction factors, f represents the switching frequency, E IGBT-ON represents the energy lost during one turn-on of the IGBT under the reference voltage and reference current, E IGBT-OFF represents the energy lost during one turn-off of the IGBT under the reference voltage and reference current, V Ref represents the reference voltage, I Ref represents the reference current, D represents the duty cycle, V CE represents the voltage between the collector and emitter of the IGBT, r CE represents the resistance between the collector and emitter of the IGBT, I ph_IGBT represents the operating current of the IGBT.

3. The method for determining the coolant flow rate of the motor controller according to claim 2, wherein: The freewheeling diode loss includes the freewheeling diode switching loss P Diobe-switch and the freewheeling diode conduction loss P Diobe-conduct , and in the established Simulink model: The freewheeling diode switching loss P Diobe-switch satisfies: The conduction loss P of the freewheeling diode Diobe-conduct satisfies: Among them, K Diobe-switch and K Diobe-conduct represent correction factors, f represents the switching frequency, E Diobe-ON represents the energy loss of the freewheeling diode when it is turned on once under the reference voltage and reference current, E Diobe-OFF represents the energy loss of the freewheeling diode when it is turned off once under the reference voltage and reference current, V Ref represents the reference voltage, I Ref represents the reference current, D represents the duty cycle, V Diobe represents the voltage across the freewheeling diode, r Diobe represents the resistance value of the freewheeling diode, I ph_Diobe represents the operating current of the freewheeling diode.

4. The method for determining the coolant flow rate of the motor controller according to claim 3, wherein: In the established Simulink model, the K IGBT-switch and the K IGBT-conduct , and the K Diobe-switch and the K Diobe-conduct are all obtained by establishing a correction coefficient corresponding to the working voltage V DC and the working current I ph through a 2D table and obtaining it by online table lookup.

5. The method for determining the coolant flow rate of the motor controller according to claim 3, wherein: The IGBT switching loss P IGBT-switch in and the freewheeling diode switching loss P Diobe-switch in are both obtained by establishing a corresponding 2D table between each other and the operating voltage V DC and the operating current I ph and through the method of online table lookup.

6. The method for determining the coolant flow rate of the motor controller according to claim 3, wherein: The IGBT conduction loss P IGBT-conduct Among them, the V CE and the r CE are both obtained by establishing a corresponding 1D table between each other and the IGBT temperature and by looking up the table online.

7. The method for determining the coolant flow rate of the motor controller according to claim 3, wherein: In the established Simulink model, if the motor controller is in the active short - circuit working state, the IGBT switching loss P IGBT-switch and the free - wheeling diode switching loss P Diobe-switch are 0.

8. The method for determining the coolant flow rate of the motor controller according to claim 1, characterized in that: The DC-link capacitor loss and the bus loss are both obtained through P = R·I 2 where P represents the DC-link capacitor loss or the bus loss, R represents the resistance of the DC-link capacitor or the bus, and I represents the operating current of the DC-link capacitor or the bus.

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