Current sampling method and apparatus for electric motor driver, and electric vehicle

Abstract

Disclosed in the embodiments of the present invention are a current sampling method and apparatus for an electric motor driver, and an electric vehicle. The method comprises: on the basis of an on-off state of each transistor in phase control branches under a preset condition, calculating an equivalent conduction current of each transistor; on the basis of a transistor voltage drop and the equivalent conduction current of each transistor, calculating a conduction internal resistance of each transistor; and on the basis of the transistor voltage drop and the conduction internal resistance of each transistor, obtaining an actual conduction current of each transistor. In the present solution, an actual conduction current of a transistor that is obtained by means of sampling changes as the temperature of the transistor changes, so as to eliminate the phenomenon of inconsistency between a sampled current and the actual conduction current due to a means of sampling a current on the basis of a transistor voltage drop of the transistor being affected by temperature, thereby improving the precision of control of a controller over the sampled current; and at a safe temperature, an output torque of the controller is no longer affected by temperature, thereby alleviating the problem of power reduction caused by an increase in the temperature of the transistor during the riding of an electric vehicle.

Description

Current sampling method and device for motor driver and electric vehicle Technical Field

[0001] The embodiments of the present invention relate to the field of power electronics technology, and in particular to a current sampling method and device for a motor driver and an electric vehicle. Background Art

[0002] Currently, for cost-effectiveness considerations, motor drivers usually use the MOS tube voltage drop ratio method to collect the MOS tube conduction current, thereby feeding back the motor phase current.

[0003] However, due to the temperature characteristics of the MOS tube itself, its internal resistance changes, so that the sampling current changes with the temperature of the MOS tube, resulting in a large deviation between the sampling current and the actual conduction current, affecting the control accuracy of the motor driver.

[0004] Summary of the Invention

[0005] Embodiments of the present invention provide a current sampling method and device for a motor driver and an electric vehicle to solve the problem that the on-current obtained based on MOS tube voltage drop sampling is affected by temperature, resulting in excessive sampling deviation.

[0006] According to one aspect of the present invention, a current sampling method for a motor driver is provided. The motor driver includes a multi-phase control branch, each phase control branch includes an upper bridge arm and a lower bridge arm, and the upper bridge arm and the lower bridge arm each include a transistor. The current sampling method for the motor driver includes:

[0007] Calculate the equivalent on-state current of each transistor according to the on-off state of the transistor in each phase control branch under preset conditions;

[0008] Calculate the on-resistance of the transistor based on the transistor voltage drop and equivalent on-current;

[0009] The actual on-state current of the transistor is obtained based on the transistor voltage drop and on-state internal resistance.

[0010] Optionally, the motor driver includes a three-phase control branch, and the preset conditions include:

[0011] The transistors in the upper bridge arm of one phase control branch are turned on, and the transistors in the lower bridge arms of the other two phase control branches are turned on; or,

[0012] The transistors in the upper bridge arms of the two-phase control branches are turned on, and the transistors in the lower bridge arm of the other phase control branch are turned on.

[0013] Optionally, the on-state internal resistance of the transistor is calculated based on the transistor voltage drop and the equivalent on-state current of the transistor, including:

[0014] Collect the bus voltage and the phase voltage of each phase control branch respectively, and calculate the tube voltage drop of each transistor based on the bus voltage and the phase voltage;

[0015] Calculate the on-state internal resistance of the transistor at the current temperature based on the tube voltage drop and the equivalent on-state current.

[0016] Optionally, after obtaining the on-state internal resistance of the transistor, the current sampling method of the motor driver further includes:

[0017] The current temperature of the transistor is determined based on the corresponding relationship between the on-state internal resistance and the temperature.

[0018] Optionally, calculating the equivalent on-current of each transistor according to the on-off state of the transistor in each phase control branch under preset conditions includes:

[0019] Collect the bus current of the motor driver;

[0020] Combined with the on-off state of the transistors in each phase control branch under preset conditions, the equivalent on-current is calculated according to the bus current.

[0021] Optionally, the lower bridge arm is grounded through a sampling resistor, and the bus current is obtained in the following ways:

[0022] Get the voltage on the sampling resistor;

[0023] The bus current is calculated based on the voltage on the sampling resistor and the resistance of the sampling resistor.

[0024] Optionally, combining the on-off state of transistors in each phase control branch under preset conditions and calculating the equivalent on-current according to the bus current includes:

[0025] Combined with the on-off state of the transistors in each phase control branch under preset conditions, the equivalent on-current of the corresponding transistor is calculated according to the corresponding relationship between the on-current of the transistor and the bus current.

[0026] According to another aspect of the present invention, a current sampling device for a motor driver is provided. The motor driver includes a multi-phase control branch, each phase control branch includes an upper bridge arm and a lower bridge arm, and each upper bridge arm and lower bridge arm includes a transistor. The sampling device includes:

[0027] An equivalent on-current calculation module is used to calculate the equivalent on-current of each transistor according to the on-off state of the transistor in each phase control branch under preset conditions;

[0028] The on-resistance calculation module is used to calculate the on-resistance of the transistor based on the transistor voltage drop and equivalent on-current;

[0029] The actual on-current calculation module is used to obtain the actual on-current of the transistor based on the transistor voltage drop and on-resistance.

[0030] Optionally, the sampling device further comprises:

[0031] Voltage acquisition module, used to collect the phase voltage and bus voltage of each phase control branch;

[0032] The tube voltage drop calculation module is used to calculate the tube voltage drop of the transistor according to the voltage collected by the voltage collection module.

[0033] According to another aspect of the present invention, an electric vehicle is provided. The electric vehicle includes a motor driver and a controller. The controller is configured to execute the current sampling method for the motor driver provided in any embodiment of the present invention to collect the conduction current of the motor driver.

[0034] The technical solution provided by the embodiment of the present invention samples the bus current by adding a bus current sampling resistor. Based on the on-off state of the transistor in each phase control branch under preset conditions, the bus current sampled at this time is equivalent to the on-current flowing through the transistor. The on-resistance of the transistor at the current temperature is calculated based on the equivalent on-current and the transistor voltage drop, thereby obtaining the actual on-current of the transistor at the current temperature based on the transistor voltage drop and the on-resistance. The actual on-current of the transistor sampled by this solution changes with the temperature of the transistor, eliminating the phenomenon that the sampling current and the actual on-current are inconsistent due to the influence of temperature when sampling current based on the transistor voltage drop, thereby improving the control accuracy of the controller for the sampled current. At a safe temperature, the output torque of the controller is no longer affected by temperature, thereby improving the problem of power reduction caused by the increase of transistor temperature during riding of an electric vehicle.

[0035] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] FIG1 is a schematic structural diagram of a motor driver provided by an embodiment of the present invention;

[0038] FIG2 is a flow chart of a current sampling method for a motor driver provided by an embodiment of the present invention;

[0039] FIG3 is a flow chart of another current sampling method for a motor driver provided by an embodiment of the present invention;

[0040] FIG4 is a schematic structural diagram of another motor driver provided by an embodiment of the present invention;

[0041] FIG5 is a schematic structural diagram of another motor driver provided by an embodiment of the present invention;

[0042] FIG6 is a flow chart of another current sampling method for a motor driver provided by an embodiment of the present invention;

[0043] FIG7 is a flow chart of another current sampling method for a motor driver provided by an embodiment of the present invention;

[0044] FIG8 is a graph showing the relationship between on-state internal resistance and temperature according to an embodiment of the present invention;

[0045] FIG9 is a schematic structural diagram of a current sampling device for a motor driver provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0047] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0048] As described in the background technology, the internal resistance of the MOS tube is greatly affected by temperature. Under the same current, the voltage drop of the MOS tube will also change, resulting in a large deviation between the sampled current and the actual current. During the riding of an electric vehicle, as the temperature of the MOS tube increases, its internal resistance and tube voltage drop gradually change, causing the sampled current to gradually exceed the actual conduction current. The maximum output torque output by the motor driver based on the sampled current will gradually decrease with the increase in temperature. Under heavy load conditions, the output phase current will decrease after a period of riding, and the power will weaken, affecting the riding experience.

[0049] In response to the above problems, the present invention provides a current sampling method for a motor driver to improve the control accuracy of the sampled current. Figure 1 is a structural schematic diagram of a motor driver provided by an embodiment of the present invention. Referring to Figure 1, the motor driver includes a multi-phase control branch, each phase control branch includes an upper bridge arm and a lower bridge arm, and the upper bridge arm and the lower bridge arm both include transistors. Here, the transistor can be a MOS tube. Exemplarily, it includes a three-phase control branch, wherein the first phase control branch includes a first transistor Q1 of the upper bridge arm and a second transistor Q2 of the lower bridge arm, the second phase control branch includes a third transistor Q3 of the upper bridge arm and a fourth transistor Q4 of the lower bridge arm, and the third phase control branch includes a fifth transistor Q5 of the upper bridge arm and a sixth transistor Q6 of the lower bridge arm. The midpoint of each phase control branch is connected to the motor M. The voltage acquisition module 10 is used to collect the phase voltage Vu of the first phase control branch, the phase voltage Vv of the second phase control branch, the phase voltage Vw of the third phase control branch, the bus voltage Vbus of the upper bridge arm and the bus voltage Vr of the lower bridge arm. The controller 20 can be used to calculate the sampled current based on the voltage collected by the voltage acquisition module 10, thereby feeding back the phase current of the motor M.

[0050] FIG2 is a flow chart of a current sampling method for a motor driver provided by an embodiment of the present invention. Referring to FIG2 , the current sampling method provided by this embodiment includes:

[0051] S110 , calculating the equivalent on-current of each transistor according to the on-off state of the transistor in each phase control branch under preset conditions.

[0052] Specifically, during the conduction of each phase control branch, under certain preset conditions, the transistors in each phase control branch are in a specific conduction state, and there is a situation where the transistor's conduction current corresponds to the bus current. In this case, the equivalent conduction current flowing through each transistor can be determined based on the correspondence between the bus current and the transistor's conduction current. The equivalent conduction current is the actual conduction current flowing through the transistor.

[0053] S120. Calculate the on-state internal resistance of the transistor according to the transistor voltage drop and the equivalent on-state current of the transistor.

[0054] Specifically, after obtaining the equivalent on-current of the corresponding transistor, the on-resistance of the transistor can be calculated based on the transistor voltage drop and the equivalent on-current flowing through the transistor. Here, since the on-resistance of the transistor is calculated based on the equivalent on-current, and the equivalent on-current is obtained under preset conditions, under which the temperature of the transistor is fixed, the obtained on-resistance is essentially the on-resistance at the current temperature.

[0055] S130 , obtaining the actual on-state current of the transistor according to the transistor voltage drop and on-state internal resistance of the transistor.

[0056] Specifically, after obtaining the transistor's on-resistance, the actual on-current of the transistor at the current temperature is calculated based on the ratio of the transistor's voltage drop to its on-resistance. The actual on-current obtained here corresponds to the transistor's current temperature. That is, when the transistor's temperature changes, the calculated actual on-current follows suit, eliminating any discrepancies between the sampled current and the actual current.

[0057] The current sampling method for a motor driver provided in an embodiment of the present invention samples the bus current by adding a bus current sampling resistor. Based on the on-off state of the transistor in each phase control branch under preset conditions, the bus current sampled at this time is equivalent to the on-current flowing through the transistor. The on-resistance of the transistor at the current temperature is calculated based on the equivalent on-current and the transistor voltage drop, thereby obtaining the actual on-current of the transistor at the current temperature based on the transistor voltage drop and the on-resistance. The actual on-current of the transistor sampled in this solution varies with the temperature of the transistor, eliminating the phenomenon of inconsistency between the sampled current and the actual on-current caused by the temperature influence of the transistor voltage drop sampling method. This improves the controller's control accuracy over the sampled current. At a safe temperature, the controller's output torque is no longer affected by temperature, thereby improving the problem of power reduction caused by increased transistor temperature during electric vehicle riding.

[0058] In an optional implementation provided by an embodiment of the present invention, the equivalent on-state current of the transistor can be obtained based on the bus current. FIG3 is a flow chart of another current sampling method for a motor driver provided by an embodiment of the present invention. Referring to FIG3 , the current sampling method provided by this embodiment includes:

[0059] S1101. Collect the bus current of the motor driver.

[0060] S1102 , calculating the equivalent on-current according to the bus current in combination with the on-off state of the transistors in each phase control branch under preset conditions.

[0061] Specifically, the lower bridge arm is grounded through a sampling resistor R, and the bus current can be collected through the sampling resistor R. The bus current is calculated based on the voltage across the sampling resistor R and the resistance value of the sampling resistor R. The bus current can be expressed as: Ibus = Vr / Rbus, where Ibus is the bus current, Vr is the voltage across the sampling resistor R, and Rbus is the resistance value of the sampling resistor R.

[0062] Optionally, the sampling resistor R may be a constantan wire resistor that is less affected by temperature and has a fixed resistance value. The temperature change has a negligible effect on the sampling result of the bus current Ibus.

[0063] In this embodiment, the specific steps of calculating the equivalent on-state current are:

[0064] Combined with the on-off state of the transistor in each phase control branch under preset conditions, the equivalent on-current of the corresponding transistor is calculated according to the corresponding relationship between the on-current of the transistor and the bus current Ibus.

[0065] Specifically, the correspondence between the bus current Ibus and the conduction current of the transistor is affected by the on-off state of each transistor. Taking the three-phase control branch as an example, the preset conditions are: the transistor in the upper bridge arm of one phase control branch is turned on, and the transistors in the lower bridge arms of the other two phase control branches are turned on; or, the transistors in the upper bridge arms of two phase control branches are turned on, and the transistors in the lower bridge arm of the other phase control branch are turned on. Among them, when one phase in the upper bridge arm is turned on and the lower bridge arms of the other two phases are turned on, the current flowing through the bus at this time is the turn-on current of the upper bridge arm. When two phases in the upper bridge arm are turned on and the lower bridge arm of the other phase is turned on, the current flowing through the bus at this time is the turn-on current of the lower bridge arm.

[0066] FIG4 is a schematic diagram of the structure of another motor driver provided by an embodiment of the present invention. Referring to FIG4 , when the first transistor Q1 of the upper bridge arm is turned on, the third transistor Q3 and the fifth transistor Q5 are turned off, and the fourth transistor Q4 and the sixth transistor Q6 of the lower bridge arm are turned on, and the second transistor Q2 is turned off, the turn-on current of the upper bridge arm flows from the positive electrode of the capacitor C through the first transistor Q1 to the motor M, and the turn-on current of the lower bridge arm flows from the motor M through the fourth transistor Q4 and the sixth transistor Q6 to the negative electrode of the capacitor C. At this time, the equivalent turn-on current I1 of the first transistor Q1 = Ibus, and the equivalent turn-on current I4 of the fourth transistor Q4 and the equivalent turn-on current I6 of the sixth transistor Q6 satisfy the following relationship: I4 = I6 = I1 / 2.

[0067] FIG5 is a schematic diagram of the structure of another motor driver provided by an embodiment of the present invention. Referring to FIG5 , when the first transistor Q1 and the third transistor Q3 of the upper bridge arm are turned on, the fifth transistor Q5 is turned off, and the sixth transistor Q6 of the lower bridge arm is turned on, and the fourth transistor Q4 and the second transistor Q2 are turned off, the turn-on current of the upper bridge arm flows from the positive electrode of the capacitor C through the first transistor Q1 and the third transistor Q3 to the motor M, respectively, and the turn-on current of the lower bridge arm flows from the motor M through the sixth transistor Q6 to the negative electrode of the capacitor C. At this time, the equivalent turn-on current I6 of the sixth transistor Q6 = Ibus, and the equivalent turn-on current I1 of the first transistor Q1 and the equivalent turn-on current I3 of the third transistor Q3 satisfy: I1 = I3 = I6 / 2.

[0068] In this embodiment, by determining the on-off state of each transistor under preset conditions, the equivalent on-current I1 of the first transistor Q1, the equivalent on-current I2 of the second transistor Q2, the equivalent on-current I3 of the third transistor Q3, the equivalent on-current I4 of the fourth transistor Q4, the equivalent on-current I5 of the fifth transistor Q5, and the equivalent on-current I6 of the sixth transistor Q6 can be obtained respectively.

[0069] S120. Calculate the on-state internal resistance of the transistor according to the transistor voltage drop and the equivalent on-state current of the transistor.

[0070] S130 , obtaining the actual on-state current of the transistor according to the transistor voltage drop and on-state internal resistance of the transistor.

[0071] This solution makes full use of the characteristics of the drive circuit. It samples the bus current Ibus by adding a bus current sampling resistor R, and according to the on-off state of the transistor in each phase control branch under preset conditions, the bus current Ibus sampled at this time is equivalent to the on-current flowing through the transistor. The on-resistance of the transistor at the current temperature is calculated based on the equivalent on-current and the tube voltage drop of the transistor, so as to compensate for the defect that the on-resistance of the transistor varies greatly due to temperature.

[0072] Optionally, in other embodiments, a sampling resistor may be connected to the drain terminals of the second transistor Q2, the fourth transistor Q4 and the sixth transistor Q6 of the lower bridge arm respectively, and the equivalent on-state current of the transistor may be collected through the sampling resistor.

[0073] Optionally, FIG6 is a flowchart of another current sampling method for a motor driver provided in an embodiment of the present invention. Referring to FIG6 , the current sampling method provided in this embodiment includes:

[0074] S110 , calculating the equivalent on-current of each transistor according to the on-off state of the transistor in each phase control branch under preset conditions.

[0075] S1201. Collect the bus voltage and the phase voltage of each phase control branch respectively, and calculate the tube voltage drop of each transistor according to the bus voltage and the phase voltage.

[0076] S1202. Calculate the on-state internal resistance of the transistor at the current temperature based on the transistor voltage drop and the equivalent on-state current.

[0077] Specifically, in conjunction with the structure of the motor driver shown in FIG1 , the bus voltage includes the positive electrode voltage Vbus of the capacitor C and the voltage Vr across the current sampling resistor R. The phase voltages of the control branches include: the phase voltage Vu of the first phase control branch, the phase voltage Vv of the second phase control branch, and the phase voltage Vw of the third phase control branch. Thus, the tube voltage drop of each transistor can be obtained: the tube voltage drop of the first transistor Q1 is Vbus-Vu, the tube voltage drop of the third transistor Q3 is Vbus-Vv, the tube voltage drop of the fifth transistor Q5 is Vbus-Vw, the tube voltage drop of the second transistor Q2 is Vu-Vr, the tube voltage drop of the fourth transistor Q4 is Vv-Vr, and the tube voltage drop of the sixth transistor Q6 is Vw-Vr.

[0078] Based on the equivalent on-current obtained in step S110 and combined with the calculated transistor voltage drop, the on-resistance of the transistor at the current temperature can be calculated. Here, at the current temperature corresponding to the equivalent on-current, the on-resistance R1 of the first transistor Q1 is equal to (Vbus-Vu) / I1, the on-resistance R3 of the third transistor Q3 is equal to (Vbus-Vv) / I3, the on-resistance R5 of the fifth transistor Q5 is equal to (Vbus-Vw) / I5, the on-resistance R2 of the second transistor Q2 is equal to (Vu-Vr) / I2, the on-resistance R4 of the fourth transistor Q4 is equal to (Vv-Vr) / I4, and the on-resistance R6 of the sixth transistor Q6 is equal to (Vw-Vr) / I6.

[0079] S130 , obtaining the actual on-state current of the transistor according to the transistor voltage drop and on-state internal resistance of the transistor.

[0080] The actual on-state current flowing through the transistor can be obtained by using the transistor voltage drop and the on-state internal resistance at the current temperature. Specifically, the actual on-state current I1' of the first transistor Q1 is equal to (Vbus-Vu) / R1, the actual on-state current I3' of the third transistor Q3 is equal to (Vbus-Vv) / R3, the actual on-state current I5' of the fifth transistor Q5 is equal to (Vbus-Vw) / R5, the actual on-state current I2' of the second transistor Q2 is equal to (Vu-Vr) / R2, the actual on-state current I4' of the fourth transistor Q4 is equal to (Vv-Vr) / R4, and the actual on-state current I6' of the sixth transistor Q6 is equal to (Vw-Vr) / R6.

[0081] It should be understood that the equivalent on-current of the transistor obtained based on the bus current is actually the actual on-current of the transistor. However, since the equivalent on-current can only be obtained under preset conditions, the actual on-current of the transistor is further calculated by the tube voltage drop and internal resistance, so that the controller can feedback the corresponding phase current based on the calculated actual on-current.

[0082] This solution calculates the transistor's on-state internal resistance at the current temperature based on the sampled equivalent on-state current and the transistor's voltage drop. This calculation then uses the transistor's voltage drop and on-state internal resistance to determine the transistor's actual on-state current at the current temperature. Because the transistor's actual on-state current varies with its temperature, this eliminates the discrepancy between the sampled current and the actual on-state current caused by temperature fluctuations in the current sampling method based on the transistor's voltage drop. This improves the accuracy of controlling the transistor's actual on-state current.

[0083] Alternatively, in another optional implementation provided by the embodiment of the present invention, the temperature of the transistor may also be obtained during the current sampling process. FIG7 is a flow chart of another current sampling method for a motor driver provided by an embodiment of the present invention. Referring to FIG7 , the current sampling method provided by this embodiment includes:

[0084] S110 , calculating the equivalent on-current of each transistor according to the on-off state of the transistor in each phase control branch under preset conditions.

[0085] S120. Calculate the on-state internal resistance of the transistor according to the transistor voltage drop and the equivalent on-state current of the transistor.

[0086] S210 : Determine the current temperature of the transistor according to the corresponding relationship between the on-state internal resistance and the temperature.

[0087] S130 , obtaining the actual on-state current of the transistor according to the transistor voltage drop and on-state internal resistance of the transistor.

[0088] Specifically, the on-resistance of the transistor changes with temperature. Once the on-resistance of the transistor is determined, the current temperature of the transistor can be quickly obtained based on the corresponding relationship between the on-resistance and temperature. Since the temperature is obtained based on the on-resistance of the transistor, compared with the method of using a thermistor to collect temperature, this solution has higher collection accuracy and can quickly and accurately reflect the temperature of the transistor.

[0089] Figure 8 is a graph showing the relationship between on-resistance and temperature, provided by an embodiment of the present invention. Referring to Figure 8 , the horizontal axis represents the junction temperature of the transistor, and the vertical axis represents the normalized value of the transistor's source-drain on-resistance. The relationship between the transistor's on-resistance and junction temperature can be obtained by recording the actual on-resistance at different temperatures, thereby generating a corresponding functional relationship. This functional relationship can be stored in the controller. After obtaining the on-resistance, the functional relationship can be directly called to obtain the current temperature of the transistor.

[0090] Optionally, an embodiment of the present invention further provides a current sampling device for a motor driver, which is used to perform the current sampling method for a motor driver provided in any embodiment of the present invention. FIG9 is a schematic structural diagram of a current sampling device for a motor driver provided in an embodiment of the present invention. Referring to FIG9 , the current sampling device for a motor driver includes:

[0091] The equivalent on-current calculation module 11 is used to calculate the equivalent on-current of each transistor according to the on-off state of the transistor in each phase control branch under preset conditions.

[0092] The on-resistance calculation module 12 is used to calculate the on-resistance of the transistor according to the transistor voltage drop and the equivalent on-current of the transistor.

[0093] The actual on-current calculation module 13 is used to obtain the actual on-current of the transistor according to the transistor voltage drop and on-resistance of the transistor.

[0094] Optionally, the sampling device further includes a voltage acquisition module 10 and a transistor voltage drop calculation module. The voltage acquisition module 10 is configured to acquire the phase voltage and bus voltage of each phase control branch, and the transistor voltage drop calculation module is configured to calculate the transistor voltage drop of the transistor based on the voltages acquired by the voltage acquisition module. Referring to FIG1 , the equivalent on-state current calculation module 11, the on-state internal resistance calculation module 12, the actual on-state current calculation module 13, and the transistor voltage drop calculation module can be integrated into a controller 20. The controller 20 is connected to the voltage sampling module 10 and is configured to calculate the actual on-state current based on the received voltage.

[0095] The current sampling device of the motor driver provided in the embodiment of the present invention and the current sampling method of the motor driver provided in any embodiment of the present invention belong to the same inventive concept and have the same beneficial effects, which will not be described in detail here.

[0096] Optionally, an embodiment of the present invention further provides an electric vehicle, which includes but is not limited to a two-wheeled electric vehicle and a three-wheeled electric vehicle. The electric vehicle includes a motor driver and a controller. The controller is used to execute the current sampling method of the motor driver provided in any embodiment of the present invention to collect the on-current of the motor driver (i.e., the actual on-current of the transistor) to feed back the phase current of the motor. Therefore, the electric vehicle also has the beneficial effects provided by any of the above embodiments, which will not be repeated here.

[0097] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0098] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A current sampling method for a motor driver, the motor driver comprising a multi-phase control branch, each phase of the control branch comprising an upper bridge arm and a lower bridge arm, and the upper bridge arm and the lower bridge arm each comprising a transistor, characterized in that, The current sampling method of the motor driver includes: Calculating the equivalent conduction current of each transistor according to the on - off state of the transistors in each phase control branch under preset conditions; Calculating the on - resistance of the transistor according to the voltage drop across the transistor and the equivalent conduction current; Obtaining the actual conduction current of the transistor according to the voltage drop across the transistor and the on - resistance.

2. The current sampling method of the motor driver according to claim 1, wherein The motor driver includes three - phase control branches, and the preset conditions include: The transistor in the upper arm of one phase control branch is conducting, and the transistors in the lower arms of the other two phase control branches are conducting; or, The transistors in the upper arms of two phase control branches are conducting, and the transistor in the lower arm of the other one phase control branch is conducting.

3. The current sampling method of the motor driver according to claim 1, wherein The calculating the on - resistance of the transistor according to the voltage drop across the transistor and the equivalent conduction current includes: Collecting the bus voltage and the phase voltage of each phase control branch respectively, and calculating the voltage drop across each transistor according to the bus voltage and the phase voltage; Calculating the on - resistance of the transistor at the current temperature according to the voltage drop and the equivalent conduction current.

4. The current sampling method of the motor driver according to claim 1, characterized in that, After obtaining the on - resistance of the transistor, the current sampling method of the motor driver further includes: Determining the current temperature of the transistor according to the corresponding relationship between the on - resistance and the temperature.

5. The current sampling method of the motor driver according to claim 1, characterized in that, The calculating the equivalent conduction current of each transistor according to the on - off state of the transistors in each phase control branch under preset conditions includes: Collecting the bus current of the motor driver; Combining the on - off state of the transistors in each phase control branch under the preset conditions, and calculating the equivalent conduction current according to the bus current.

6. The current sampling method of the motor driver according to claim 5, wherein The lower arm is grounded through a sampling resistor, and the method for obtaining the bus current includes: Obtaining the voltage across the sampling resistor; Calculating the bus current according to the voltage across the sampling resistor and the resistance value of the sampling resistor.

7. The current sampling method of the motor driver according to claim 5, characterized in that, The combining the on - off state of the transistors in each phase control branch under the preset conditions and calculating the equivalent conduction current according to the bus current includes: Combining the on - off state of the transistors in each phase control branch under preset conditions, and calculating the equivalent conduction current of the corresponding transistor according to the corresponding relationship between the conduction current of the transistor and the bus current.

8. A current sampling device for a motor driver, the motor driver comprising a multi-phase control branch, each phase of the control branch including an upper bridge arm and a lower bridge arm, the upper bridge arm and the lower bridge arm each including a transistor, characterized in that, The sampling device includes: An equivalent conduction current calculation module, configured to calculate the equivalent conduction current of each transistor according to the on - off state of the transistors in each phase control branch under preset conditions; An on - resistance calculation module, configured to calculate the on - resistance of the transistor according to the voltage drop across the transistor and the equivalent conduction current; An actual conduction current calculation module, configured to obtain the actual conduction current of the transistor according to the voltage drop across the transistor and the on - resistance.

9. The current sampling device of the motor driver according to claim 8, wherein It further includes: A voltage acquisition module, configured to collect the phase voltage and the bus voltage of each phase control branch; A voltage - drop calculation module, configured to calculate the voltage drop across the transistor according to the voltages collected by the voltage acquisition module.

10. An electric vehicle, characterized in that, It includes a motor driver and a controller, and the controller is used to execute the current sampling method of the motor driver described in any one of claims 1-7 to collect the conduction current of the motor driver.

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