Control method of electronic water pump

Abstract

The invention relates to the field of electronic water pumps, in particular to an electronic water pump control method which comprises the steps that a first rotating speed is established in advance, and the first rotating speed is specifically the rotating speed of a motor of an electronic water pump when cooling liquid in a semi-fluid state can only be whipped by an impeller of the electronic water pump but cannot be sucked; waiting to receive a starting signal; generating a selection instruction according to the received environment temperature information; starting the electronic water pump; and if the generated selection instruction is the first instruction, setting the first rotating speed as the working rotating speed of the electronic water pump. When the rotation of the rotor is changed into clockwise rotation and the position of the N pole of the rotor is changed from the position between the A-phase winding and the B-phase winding to the position between the B-phase winding and the C-phase winding, the N pole of the rotor does not continuously rotate towards the direction of the first position, so that the clockwise rotation amplitude of the rotor is reduced; therefore, the rotor does not violently swing or oscillate, and the phenomena of shutdown or galloping and the like are avoided.

Description

Technical Field

[0001] The invention relates to the field of electronic water pumps, and in particular to a control method for an electronic water pump. Background Art

[0002] New energy vehicles are provided with a cooling system for dissipating heat from heat sources; specifically, the three-electric system in the new energy vehicle serves as a heat source, and the cooling system includes an electronic water pump, a water tank, pipes for the circulation of coolant, and a controller for controlling the electronic water pump, wherein the water tank, the electronic water pump and the pipes constitute a cooling channel, wherein a part of the cooling channel is located at the position of the three-electric system; the water tank is used to store coolant, and under the control of the controller, the electronic water pump draws coolant, so that the coolant passes through the pipe electronic water pump and the three-electric system, and finally flows into the water tank, and when the coolant flows to the pipe at the position of the three-electric system, the coolant forms a heat exchange with the three-electric system, thereby achieving the purpose of cooling the three-electric system.

[0003] New energy vehicles are being used more and more widely in low-temperature areas. As a result, the reliability of the cooling system has become a top priority under low-temperature conditions (for example, minus 50°C).

[0004] Specifically, the coolant is affected by low temperature, and the medium state of the coolant changes from liquid to semi-fluid state. When observing the semi-fluid coolant from a human perspective, the semi-fluid coolant forms a jelly-like phenomenon;

[0005] The electronic water pump includes a motor and an impeller. The impeller does work on the coolant in a semi-fluid state, which can easily cause a sudden load change on the impeller. Under low temperature conditions, due to the sudden load change on the impeller, the motor will shut down or run away after a violent vibration, resulting in low reliability of the cooling system.

[0006] Therefore, under low temperature conditions, how to improve the reliability of the cooling system of new energy vehicles has become a technical problem to be solved. Summary of the invention

[0007] In order to solve the technical problem of how to improve the reliability of a cooling system of a new energy vehicle under low temperature conditions, the present invention provides a control method for an electronic water pump.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] According to one aspect of the present invention, there is provided a method for controlling an electronic water pump, comprising:

[0010] Pre-establishing a first rotation speed, wherein the first rotation speed is specifically a rotation speed of the motor of the electronic water pump when the coolant in a semi-fluid state can only be stirred by the impeller of the electronic water pump but cannot be sucked;

[0011] Waiting to receive a start signal;

[0012] generating a selection instruction according to the received ambient temperature information;

[0013] Start the electronic water pump;

[0014] If the generated selection instruction is the first instruction, the first speed is set as the operating speed of the electronic water pump.

[0015] Furthermore, the step of generating a selection instruction according to the received ambient temperature information is specifically as follows:

[0016] Pre-establishing a phase transition temperature, wherein the phase transition temperature is specifically a critical temperature at which the coolant changes from a liquid state to a semi-fluid state;

[0017] Under the condition that the ambient temperature is equal to or lower than the phase change temperature, generating a first instruction;

[0018] Under the condition that the ambient temperature is higher than the phase change temperature, a second instruction is generated.

[0019] Furthermore, it also includes:

[0020] Pre-set multiple detection cycles;

[0021] Presetting a first current threshold, wherein the first current threshold is specifically a three-phase current of the motor when the coolant in a semi-fluid state can only be stirred by the impeller but cannot be drawn;

[0022] The three-phase current of the motor of the electronic water pump received;

[0023] In any detection cycle, and before increasing the operating speed of the electronic water pump, whether the three-phase currents meet the first current threshold is determined to obtain a stability determination result;

[0024] In any detection cycle, and before increasing the operating speed of the electronic water pump, it is determined whether the current trend of the three-phase current is a downward trend, and a trend determination result is obtained;

[0025] According to the stability judgment result and the trend judgment result, the whipping state of the coolant is obtained;

[0026] Under the condition that the stability judgment result is yes and the trend judgment result is yes, the whipping state of the coolant is obtained as a result of completed whipping; otherwise, the whipping state of the coolant is obtained as a result of incomplete whipping.

[0027] Further, the first current threshold includes a maximum value and a minimum value;

[0028] If the maximum values ​​of the three-phase currents are respectively less than the maximum values ​​of the first current threshold, and the minimum values ​​of the three-phase currents are respectively greater than the minimum values ​​of the first current threshold, the stability judgment result is yes, otherwise, the stability judgment result is no;

[0029] In any cycle, if the maximum value of the three-phase current at a later moment forms a sudden high state relative to the maximum value of the three-phase current at the previous moment, and / or the minimum value of the three-phase current at a later moment forms a sudden low state relative to the minimum value of the three-phase current at the previous moment, then the trend judgment result is no, otherwise, the trend judgment result is yes.

[0030] Furthermore, it also includes:

[0031] Presetting a second current threshold, wherein the second current threshold is a three-phase current when the operating speed of the electronic water pump is limited to the rated speed under normal temperature conditions and the electronic water pump performs work on the coolant;

[0032] Under the condition that the whipping state of the coolant is whipping completion, a characteristic judgment result is obtained by comparing the three-phase current of any detection cycle with the second current threshold;

[0033] The coolant state judgment result is obtained based on the characteristic judgment results of multiple consecutive detection cycles.

[0034] Further, the extreme value difference and the integral sum of the second current threshold are calculated and obtained;

[0035] Pre-set the ratio threshold of the extreme value difference and the ratio threshold of the integral sum;

[0036] Calculate and obtain the extreme value difference and integral sum of the three-phase currents in any detection cycle;

[0037] In any detection cycle, a first ratio of the extreme value difference of the three-phase current to the extreme value difference of the second current threshold is calculated and obtained. If the first ratio meets the ratio threshold of the extreme value difference, the calculation result of the first ratio is yes, otherwise, the calculation result of the first ratio is no;

[0038] In any detection cycle, a second ratio of the integral sum of the three-phase currents to the integral sum of the second current threshold is calculated and obtained, if the second ratio meets the ratio threshold of the integral sum, the calculation result of the second ratio is yes, otherwise, the calculation result of the second ratio is no;

[0039] If the calculation result of the first ratio is yes and the calculation result of the second ratio is yes, the feature judgment result is yes, otherwise, the feature judgment result is no;

[0040] Under the condition that the characteristic judgment results of multiple consecutive detection cycles are respectively yes, the state judgment result of the coolant is liquid, otherwise, the state judgment result of the coolant is semi-fluid.

[0041] Furthermore, it also includes:

[0042] A third current threshold is established in advance, wherein the third current threshold is specifically a three-phase current of the motor when the coolant in a semi-fluid state can be stirred by the impeller and can be drawn;

[0043] Pre-establish speed increments;

[0044] When the coolant is in a semi-fluid state, perform the following steps to increase the operating speed of the electronic water pump;

[0045] In the step of increasing the speed, in each process of increasing the working speed of the electronic water pump, the difference between the working speed after the increase and the working speed before the increase is limited to the speed increment;

[0046] a current judgment step, in each process of increasing the working speed of the electronic water pump, calculating and obtaining the maximum value of the three-phase current, and comparing the maximum value of the three-phase current with the third current threshold to obtain a current increase judgment result, and if the current increase judgment result is yes, terminating the current increase in the working speed of the electronic water pump, and maintaining the current working speed of the electronic water pump for a preset time, and executing the speed increase step if the current increase judgment result is no;

[0047] a speed reducing step, after a preset time is satisfied, reducing the operating speed of the electronic water pump so that the operating speed of the electronic water pump after the reduction is limited to the first speed;

[0048] After executing the rotation speed reducing step, the rotation speed increasing step and the current judging step are repeatedly executed until the state judgment result of the coolant is liquid.

[0049] Further, a current ratio threshold is pre-established;

[0050] Obtaining a critical current value in the third current threshold, wherein the critical current value is a current value of the rotor when a sudden load torque change occurs;

[0051] A third ratio of the maximum value of the three-phase current to the critical current value is calculated and obtained. If the third ratio meets the current ratio threshold, the current increase judgment result is yes, otherwise, the current increase judgment result is no.

[0052] Further, under the condition that the state of the coolant is judged to be liquid, or under the condition that the second instruction is generated, the rated speed of the motor of the electronic water pump is set as the operating speed of the electronic water pump.

[0053] Furthermore, when the beating state of the coolant is obtained as an unfinished state, the current operating speed of the electronic water pump is maintained.

[0054] The above technical solution has the following advantages or beneficial effects:

[0055] According to the control method for an electronic water pump provided by the present invention, when the rotor changes to clockwise rotation and the position of the N pole of the rotor changes from a position between the A-phase winding and the B-phase winding to a position between the B-phase winding and the C-phase winding, the N pole of the rotor will not continue to rotate in the direction of the first position, so that the amplitude of the clockwise rotation of the rotor is reduced, and the rotor will not swing or oscillate violently, thereby avoiding the occurrence of shutdown or runaway. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A schematic diagram of the structure of a cooling channel provided by an embodiment of the present invention;

[0057] Figure 2-1 A schematic diagram of the torque of the rotor of the motor of the electronic water pump provided in an embodiment of the present invention;

[0058] Figure 2-2 A schematic diagram of the torque of the rotor of the motor of the electronic water pump provided in an embodiment of the present invention;

[0059] Figure 3-1 A schematic diagram of the N-pole position and power-on sequence of the rotor of the motor of the electronic water pump provided in an embodiment of the present invention;

[0060] Figure 3-2 A schematic diagram of the N-pole position and power-on sequence of the rotor of the motor of the electronic water pump provided in an embodiment of the present invention;

[0061] Figure 3-3 A schematic diagram of the N-pole position and power-on sequence of the rotor of the motor of the electronic water pump provided in an embodiment of the present invention;

[0062] Figure 3-4 A schematic diagram of the N-pole position and power-on sequence of the rotor of the motor of the electronic water pump provided in an embodiment of the present invention;

[0063] Figure 3-5 A schematic diagram of the N-pole position and power-on sequence of the rotor of the motor of the electronic water pump provided in an embodiment of the present invention;

[0064] Figure 3-6 A schematic diagram of the N-pole position and power-on sequence of the rotor of the motor of the electronic water pump provided in an embodiment of the present invention;

[0065] Figure 3-7 A schematic diagram of the N-pole position and power-on sequence of the rotor of the motor of the electronic water pump provided in an embodiment of the present invention;

[0066] Figure 4-1 A curve diagram of three-phase current and a first current threshold under low temperature conditions provided by an embodiment of the present invention;

[0067] Figure 4-2 The three-phase current under normal temperature and low temperature conditions provided in the embodiments of the present invention are curve diagrams. DETAILED DESCRIPTION

[0068] Embodiment 1:

[0069] In this embodiment, a control method for an electronic water pump is provided to solve the technical problem of how to improve the reliability of a cooling system of a new energy vehicle under low temperature conditions.

[0070] The word "low temperature" in the descriptions of low temperature, low temperature environment, low temperature scene or low temperature condition proposed in this embodiment actually refers to the temperature of the coolant being equal to or lower than the "critical temperature at which the coolant changes from a liquid state to a semi-fluid state".

[0071] The word "normal temperature" in the descriptions of normal temperature, normal temperature environment, normal temperature scene or normal temperature condition proposed in this embodiment actually refers to the temperature of the coolant being higher than the "critical temperature at which the coolant changes from a liquid state to a semi-fluid state".

[0072] In this embodiment, see Figure 1 The electronic water pump 1 is controlled by a controller 5. Unless otherwise specified, the controller 5 should be understood as the controller 5 provided in the electronic water pump itself. The controller 5 of the electronic water pump is common knowledge known to those skilled in the art and will not be described in detail here.

[0073] In the prior art new energy vehicles, see Figure 1 The electronic water pump 1, the pipeline 2, the water tank 3, etc. constitute a cooling channel, a part of which is located at the position of the heat source 4 (three-electric system) of the whole vehicle. The electronic water pump 1 is used to draw coolant and / or do work on the coolant so that the coolant can circulate in the cooling channel. When the coolant flows to the position of the three-electric system, the coolant forms heat exchange with the three-electric system of the new energy vehicle, thereby achieving the purpose of cooling the three-electric system.

[0074] During the operation of the electronic water pump 1 in the prior art, the rotor of the motor of the electronic water pump 1 has the following three torques: Figure 2-1 The rotor has electromagnetic torque T1, inertia torque T2 and load torque T3 during the rotation process; the concepts of electromagnetic torque T1, inertia torque T2 and load torque T3 are common knowledge known to those skilled in the art and will not be elaborated here.

[0075] The motor of the electronic water pump 1 in the prior art adopts a position sensorless control method; the position sensorless control method of the motor is common knowledge known to those skilled in the art and will not be described in detail here.

[0076] See also Figure 2-1 In the prior art, under normal temperature conditions, the controller 5 gives an electromagnetic torque T1 (starts the electronic water pump 1 and gives a working speed), so that when the electronic water pump 1 does work on the liquid coolant, the direction of the electromagnetic torque T1 is the same as the direction of the inertia torque T2, and is opposite to the direction of the load torque T3 respectively, and the sum of the electromagnetic torque T1 and the inertia torque T2 is the same as the load torque T3.

[0077] It should be noted that in the following text, unless otherwise specified, T1 described in the following text represents electromagnetic torque, T2 represents inertia torque, and T3 represents load torque.

[0078] In the prior art, under normal temperature conditions, when the electronic water pump 1 performs work on the liquid coolant, the relationship between the rotor position, the power-on sequence of the stator winding, and the rotor torque is as follows:

[0079] First position (initial position): see Figure 3-1 , the N pole of the rotor is located between the A-phase winding and the C-phase winding; the A-phase winding and the C-phase winding are energized, specifically A(+)→C(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0080] Second position (balance position): see Figure 3-2 , the N pole of the rotor is located between the B-phase winding and the C-phase winding; the A-phase winding and the C-phase winding are energized, specifically A(+)→C(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0081] Third position: See Figure 3-3 , the N pole of the rotor is located between the B-phase winding and the C-phase winding; the A-phase winding and the B-phase winding are energized, specifically A(+)→B(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0082] Fourth position (balance position): see Figure 3-4 , the N pole of the rotor is located between the B-phase winding and the C-phase winding; the A-phase winding and the B-phase winding are energized, specifically A(+)→B(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0083] Fifth position: See Figure 3-5, the N pole of the rotor is located between the B-phase winding and the C-phase winding; the B-phase winding and the C-phase winding are energized, specifically C(+)→B(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0084] Sixth position (balance position): see Figure 3-6 , the N pole of the rotor is located between the A-phase winding and the B-phase winding; the B-phase winding and the C-phase winding are energized, specifically C(+)→B(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0085] The seventh position: the N pole of the rotor is located between the A-phase winding and the B-phase winding (not shown in the figure); the A-phase winding and the C-phase winding are energized; C(+)→A(-); the directions of T1 and T2 are the same and opposite to the direction of T3 respectively; T1+T2=T3;

[0086] The eighth position (balanced position): the N pole of the rotor is located between the A-phase winding and the B-phase winding (not shown in the figure); the A-phase winding and the C-phase winding are energized, specifically C(+)→A(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0087] Ninth position: the N pole of the rotor is located between the A-phase winding and the B-phase winding (not shown in the figure); the A-phase winding and the B-phase winding are energized, specifically B(+)→A(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0088] The tenth position (balanced position): the N pole of the rotor is located between the A-phase winding and the C-phase winding (not shown in the figure); the A-phase winding and the B-phase winding are energized, specifically B(+)→A(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0089] Eleventh position: the N pole of the rotor is located between the A-phase winding and the C-phase winding (not shown in the figure); the B-phase winding and the C-phase winding are energized, specifically B(+)→C(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3;

[0090] The twelfth position (balanced position); the N pole of the rotor is located between the A-phase winding and the C-phase winding (not shown in the figure); the B-phase winding and the C-phase winding are energized, specifically B(+)→C(-); the directions of T1 and T2 are the same and opposite to the direction of T3, respectively, T1+T2=T3.

[0091] As the rotor continues to rotate, the N-pole position of the rotor periodically reaches the aforementioned first to twelfth positions in sequence, wherein each time the N-pole position of the rotor reaches the equilibrium position (the second, fourth, sixth, eighth, tenth, and twelfth positions), the rotor relies on its own rotational inertia to maintain counterclockwise circular rotation.

[0092] However, in the prior art, if the electronic water pump 1 works on the coolant in the semi-fluid state under low temperature conditions, the impeller of the electronic water pump 1 whips the coolant in the semi-fluid state, so that the whipped coolant in the semi-fluid state is whipped from a relatively large mass into a relatively small mass, or even whipped into a liquid coolant; gaps are formed between multiple relatively small masses of semi-fluid coolant (i.e., the second coolant defined in the following content), and the gaps are filled with air;

[0093] For the convenience of description, a relatively large mass of semi-fluid coolant is defined as a first coolant, and a relatively small mass of semi-fluid coolant is defined as a second coolant;

[0094] In the prior art, under low temperature conditions, the object that the impeller beats at the previous moment is the first coolant or the second coolant, and the object that the impeller beats at the next moment is changed to the air in the gap between the second coolants, resulting in that the load on the impeller at the previous moment is relatively large, and the load on the impeller at the next moment is relatively small (close to or reaching zero load); the load on the impeller acts on the rotor of the motor, forming a load torque T3; from the perspective of the rotor, when the load on the impeller is relatively large, the load torque T3 of the rotor is relatively large, conversely, when the load on the impeller is relatively small, the load torque T3 of the rotor is relatively small.

[0095] In the prior art, under low temperature conditions, when the electronic water pump 1 performs work on the coolant in a semi-fluid state, the relationship between the position of the rotor, the power-on sequence of the stator winding, and the torque of the rotor is specifically:

[0096] First position (initial position): see Figure 3-1 , the N pole of the rotor is located between the A-phase winding and the C-phase winding (see Figure 3-1 );A-phase winding and C-phase winding are energized, specifically A(+)→C(-);

[0097] Sixth position: See Figure 3-7 , the N pole of the rotor is located between the A-phase winding and the B-phase winding; the A-phase winding and the B-phase winding are energized, specifically A(+)→B(-).

[0098] In the prior art, under low temperature conditions, the position of the N pole of the rotor changes rapidly from "between the A-phase winding and the C-phase winding" to "the N pole of the rotor is between the A-phase winding and the B-phase winding" because the load torque T3 suddenly changes greatly; that is, at the previous moment, the object whipped by the impeller is the first coolant or the second coolant, so that the load torque T3 of the rotor is equal to the sum of the electromagnetic torque T1 and the inertia torque T2, and at the next moment, the object whipped by the impeller is the air in the gap between the second coolants, so that the load torque T3 of the rotor is much smaller than the sum of the electromagnetic torque T1 and the inertia torque T2;

[0099] In the prior art, under low temperature conditions, when the load torque T3 of the rotor is much smaller than the sum of the electromagnetic torque T1 and the inertia torque T2, the electromagnetic torque T1 and the inertia torque T2 become the power source for accelerating the rotation of the rotor, resulting in an increase in the speed of the rotor.

[0100] In the prior art, under low temperature conditions, during the process of increasing the speed of the rotor, the time for the rotor to directly rotate from the first position to the sixth position does not match the time for the controller 5 to sequentially change the power-on sequence of the stator windings, that is, the time for the rotor to directly rotate from the first position to the sixth position is less than the time for the controller 5 to sequentially change the power-on sequence of the stator windings;

[0101] In contrast, in the prior art, under normal temperature conditions, the time it takes for the rotor to rotate from the first position to the third or fourth position matches the time it takes for the controller 5 to sequentially change the power-on sequence of the stator windings, that is, the time it takes for the rotor to rotate from the first position to the third or fourth position is equal to the time it takes for the controller 5 to sequentially change the power-on sequence of the stator windings.

[0102] In the prior art, under low temperature conditions, the position of the N pole of the rotor reaches the aforementioned first, second, third, fourth, fifth and sixth positions in sequence. Especially when reaching the third and fourth positions, since the electronic water pump 1 adopts a position sensorless control method, the controller 5 collects a relatively large change in the induced electromotive force in the B-phase winding, so that the controller 5 sequentially changes the energization sequence of the stator winding. Specifically, the controller 5 energizes the A-phase winding and the C-phase winding in the first and second positions (A(+)→C(-)) to energize the A-phase winding and the B-phase winding (A(+)→B(-)).

[0103] However, in the prior art, under low temperature conditions, when the controller 5 controls the A-phase winding and the B-phase winding to be energized (A(+)→B(-)), the rotor speed is particularly fast, so that the N pole of the rotor has reached the sixth position; in this case, according to the control method without position sensor, the controller 5 will increase the current of the A-phase winding and the B-phase winding, trying to pull the N pole of the rotor back to the fourth position (see Figure 3-4) state, that is, trying to make the rotor produce a clockwise circular motion trend; from the perspective of the rotor torque, see Figure 3-7 At this moment, the N pole of the rotor is located between the A-phase winding and the B-phase winding, and the A-phase winding forms the electromagnetic pole N pole after being energized, and the B-phase winding forms the electromagnetic pole S pole after being energized. The electromagnetic pole N pole repels the rotor's N pole, and its repulsion direction is clockwise. Correspondingly, the electromagnetic pole S pole attracts the rotor's N pole, and its attraction direction is clockwise, resulting in the direction of the electromagnetic torque T1 at this time being opposite to the direction of the inertia torque T2, thereby generating a 'trend of trying to make the rotor produce a clockwise circular motion';

[0104] In the prior art, see Figure 2-2 , under low temperature conditions, when the electromagnetic torque T1 is opposite to the inertia torque T2 and the electromagnetic torque T1 is greater than the inertia torque T2, the rotor produces a clockwise circular motion;

[0105] Therefore, in the prior art, from the perspective of the overall rotation process of the rotor, under low temperature conditions, when the electronic water pump 1 does work on the coolant in a semi-fluid state, the rotor produces both counterclockwise circular motion and clockwise circular motion, and the phenomenon of "clockwise circular motion" and "counterclockwise circular motion" converting to each other repeatedly occurs, thereby forming the swing or oscillation of the rotor.

[0106] In the prior art, under low temperature conditions, when the rotor changes from counterclockwise circular motion to clockwise circular motion, the speed of the rotor is very fast, so that the time for the rotor to rotate from the sixth position to the fourth position is very short; on the one hand, due to the influence of the A-phase winding and the B-phase winding being energized and the relatively large energizing current, the electromagnetic torque T1 exceeds the inertia torque T2, so that the inertia torque T2 tends to zero torque, and the rotor stops counterclockwise circular rotation and tends to be relatively still. However, when the rotor tends to be relatively still, the rate of change of the electromotive force of the C-phase winding monitored by the control scheme without position sensor is relatively small, so the controller 5 will not change the A-phase winding and the B-phase winding. The order in which the windings are powered on is changed to the order in which the B-phase winding and the C-phase winding are powered on, so that the current situation in which the currents of the A-phase winding and the B-phase winding are relatively large is not changed; on the other hand, as the inertia torque T2 approaches zero torque, the electromagnetic torque T1 at this time is much larger than the inertia torque T2, and the load torque T3 at this time is relatively small (the load when the impeller does work on the air), so that under the acceleration of the electromagnetic torque T1, the N pole of the rotor rotates in a clockwise direction from the sixth position to the fourth position at a particularly fast speed, and when reaching the fourth position, the rotor does not stop, but continues to rotate in the direction of the first position.

[0107] Through all the above, those skilled in the art should understand that in the prior art, under low temperature conditions, the electronic water pump 1 shuts down or runs away. The actual reasons are caused by two aspects:

[0108] The first substantial reason is that under low temperature conditions, when the control method adopts the 'control method without position sensor', the medium state (semi-fluid state) of the coolant causes a sudden change in the load of the rotor during the process of the impeller stirring the semi-fluid coolant. This is the first substantial reason. The first result caused by the first substantial reason is that under low temperature conditions, during the process of the electronic water pump 1 doing work on the semi-fluid coolant, the load torque of the motor rotor suddenly changes, so that during the rotation of the rotor, the position change speed of the N pole of the rotor (i.e., the speed of the rotor) does not match the order in which the controller 5 changes the power-on sequence of the stator winding, resulting in the phenomenon that the direction of the electromagnetic torque T1 is opposite to the direction of the inertia torque T2.

[0109] The second substantial reason is that, due to the use of a position sensorless control method, when the 'phenomenon that the direction of the electromagnetic torque T1 is opposite to the direction of the inertia torque T2' occurs, the change rate of the induced electromotive force of the stator winding that is not energized detected by the controller 5 is relatively small, so that the controller 5 cannot continue to change the energization sequence of the stator winding in sequence, and can only maintain the original energization sequence, and the current of the energized stator winding gradually increases. This is the second substantial reason; the second result caused by the second substantial reason is that the inertia torque T2 tends to zero torque, and the rotor produces both counterclockwise and clockwise circular rotations, causing the rotor to swing or oscillate;

[0110] Under low temperature conditions, based on the above-mentioned substantial reasons and corresponding results, when the electronic water pump 1 works on the coolant in a semi-fluid state, the rotation speed of the rotor is increased to the limit and cannot be controlled by the controller 5, resulting in the position of the rotor relative to the stator being unable to be read by the controller 5, or the logical operation after reading is too different from the actual position, resulting in the motor vibrating violently and then shutting down or running away.

[0111] The control method of the electronic water pump 1 provided in this embodiment includes:

[0112] Pre-establishing a first rotation speed, wherein the first rotation speed is specifically the rotation speed of the motor of the electronic water pump 1 when the coolant in a semi-fluid state can only be stirred by the impeller of the electronic water pump 1 but cannot be sucked;

[0113] Waiting to receive a start signal;

[0114] generating a selection instruction according to the received ambient temperature information;

[0115] Start electronic water pump 1;

[0116] If the generated selection instruction is the first instruction, the first speed is set as the operating speed of the electronic water pump 1 .

[0117] Before the electronic water pump 1 is started under low temperature conditions, the staff should first obtain specific data of the first speed and set the first speed in a control program for execution by the controller 5 so that the controller 5 can read the first speed and perform calculations based on the first speed.

[0118] It should be understood that the first speed is obtained by experimental means, and the ambient temperature of the experiment meets the low temperature condition, that is, the ambient temperature should be equal to or less than the temperature at which the coolant changes from a liquid state to a semi-fluid state; the experimental tools include at least a sensor for detecting the speed, a flow meter for detecting the flow rate, a circulating experimental channel for the flow of the coolant, and a storage device for the coolant; the experimenter can gradually increase the speed of the electronic water pump 1 from zero speed, and observe the value of the speed sensor and the flow rate of the flow meter; when both the value of the speed and the flow rate of a non-zero flow rate can be read, it means that the coolant in the semi-fluid state has flowed in the circulating experimental channel of the coolant, and the current speed of the impeller can both stir the coolant in the semi-fluid state and absorb the coolant in the semi-fluid state;

[0119] On the contrary, when only the value of the speed sensor can be read but the flow rate of the flowmeter remains at zero, it means that the coolant in the semi-fluid state cannot flow in the coolant circulation experimental channel, and the current speed of the impeller can only stir the coolant in the semi-fluid state but cannot absorb the coolant in the semi-fluid state. At this time, the observed speed can be recorded as the first speed.

[0120] The electronic water pump 1 has a controller 5. When the electronic water pump 1 is installed on a new energy vehicle, the controller 5 of the electronic water pump 1 forms a communication connection with the ECU of the whole vehicle, wherein the ECU of the whole vehicle is used to send a start signal to the controller 5 of the electronic water pump 1.

[0121] It should be understood that the communication structure between the ECU of the vehicle and the controller 5 of the electronic water pump 1 is common knowledge known to those skilled in the art and will not be described in detail here.

[0122] Before starting the electronic water pump 1, the controller 5 generates a selection instruction based on the received ambient temperature; the selection instruction includes a first instruction and a second instruction, wherein the first instruction corresponds to a low temperature condition and the second instruction corresponds to a normal temperature condition, and the first instruction and the second instruction are respectively pre-set in a program for execution by the controller 5.

[0123] Normally, the controller 5 can obtain the ambient temperature through a temperature sensor outside the electronic water pump 1; preferably, the controller 5 has a chip, and the chip has a temperature detection circuit. Since the controller 5 is arranged on the electronic water pump 1, the position of the chip is relatively close to the position of the coolant in the pump body of the electronic water pump 1, so that the ambient temperature is obtained by using the temperature detection circuit of the chip, which can more accurately reflect the current medium state of the coolant (liquid or semi-fluid state).

[0124] Specifically, in the control method of the electronic water pump 1 of this embodiment, the steps of generating a selection instruction according to the received ambient temperature information are specifically as follows:

[0125] Pre-establishing a phase transition temperature, wherein the phase transition temperature is specifically a critical temperature at which the coolant changes from a liquid state to a semi-fluid state;

[0126] Under the condition that the ambient temperature is equal to or lower than the phase change temperature, generating a first instruction;

[0127] Under the condition that the ambient temperature is higher than the phase change temperature, a second instruction is generated.

[0128] The phase change temperature is obtained from the technical data of the coolant manufacturer when purchasing the coolant, or obtained by the experimenter conducting experiments on the purchased coolant under low temperature conditions;

[0129] In the process of obtaining the phase change temperature of the coolant through experiments, after the experimenters obtain a certain model of coolant, they set the model of coolant in a low-temperature environment. When the experimenters observe that the coolant changes from a liquid state to a semi-fluid state, the experimenters record the current temperature data of 'when the coolant changes from a liquid state to a semi-fluid state' and use the temperature data as the phase change temperature. This is very easy to achieve.

[0130] The phase change temperature is set as data in a program for execution by the controller 5 , the phase change temperature can be read by the controller 5 , and the controller 5 can perform calculations based on the phase change temperature.

[0131] When the controller 5 compares the received ambient temperature with the read phase change temperature and obtains a comparison result that the ambient temperature is equal to or lower than the phase change temperature, the controller 5 will select an instruction to generate a first instruction, which represents that the current medium state of the coolant is a semi-fluid state, or a mixture of liquid and semi-fluid states; conversely, when the comparison result that the ambient temperature is higher than the phase change temperature is obtained, the controller 5 will select an instruction to generate a second instruction, which represents that the current medium state of the coolant is liquid.

[0132] When the controller 5 simultaneously obtains the start signal and selects the instruction as the first instruction, the controller 5 starts the electronic water pump 1 , and the controller 5 sets the first speed as the operating speed of the electronic water pump 1 .

[0133] After the controller 5 starts the electronic water pump 1 according to the first instruction, the working speed of the electronic water pump 1 is limited to the first speed, so that the electronic water pump 1 can only perform a whipping action on the coolant in a semi-fluid state but cannot perform a sucking action;

[0134] When the working speed of the electronic water pump 1 is limited to the first speed, it appears that the electronic water pump 1 does not push the coolant in the semi-fluid state to flow in the cooling channel, and only the coolant in the semi-fluid state in the pump body of the electronic water pump 1 is stirred by the impeller from the first coolant to the second coolant or the liquid coolant;

[0135] In fact, under low temperature conditions, since the speed of the electronic water pump 1 after starting is limited to the first speed, from the perspective of the motor of the electronic water pump 1, under low temperature conditions, the electromagnetic torque T1 of the rotor rotating at the first speed is smaller than the electromagnetic torque T1 of the rotor rotating at the rated speed under normal temperature conditions; since the electronic torque T1 is relatively small, the inertia torque T2 of the rotor rotating at the first speed is smaller than the inertia torque T2 of the rotor rotating at the rated speed, and the load torque T3 of the rotor rotating at the first speed is smaller than the load torque T3 of the rotor rotating at the rated speed;

[0136] Therefore, under low temperature conditions, during the start-up of the electronic water pump 1, the operating speed of the electronic water pump 1 is limited to the first speed; during the process of the impeller beating the coolant in a semi-fluid state, the coolant in a semi-fluid state is gradually beaten into a second coolant, and gaps are formed between multiple second coolants. When the impeller changes from beating the coolant in a semi-fluid state to beating the air in the gaps, the load of the impeller suddenly changes, the load of the impeller decreases, resulting in a decrease in the load torque of the rotor, forming a rotor rotating at the first speed, and the load torque T3 of the rotor is much smaller than the sum of the electromagnetic torque T1 and the inertia torque T2; it should be understood that this phenomenon is essentially inevitable;

[0137] Then, when the phenomenon occurs that the load torque T3 of the rotor rotating at the first speed is much smaller than the sum of the electromagnetic torque T1 and the inertia torque T2, the electromagnetic torque T1 and the inertia torque T2 become the power source for accelerating the rotation of the rotor, resulting in an increase in the speed of the rotor.

[0138] The rotor rotates at the first speed, and during the process of increasing its speed, the time for the rotor to rotate directly from the first position to the sixth position does not match the time for the controller 5 to sequentially change the energization sequence of the stator windings;

[0139] More specifically, under low temperature conditions, the position of the N pole of the rotor reaches the aforementioned first, second, third, fourth, fifth and sixth positions in sequence, and when reaching the third and fourth positions, since the electronic water pump 1 adopts a position sensorless control method, the controller 5 collects a relatively large change in the induced electromotive force in the B-phase winding, so that the controller 5 sequentially changes the energization sequence of the stator winding, specifically, the controller 5 energizes the A-phase winding and the C-phase winding at the first and second positions (A(+)→C(-)) (see Figure 3-1 ), the A-phase winding and the B-phase winding are energized (A(+)→B(-)) (see Figure 3-3 , 3-4 , 3-7);

[0140] In this case, since the 'electromagnetic torque T1 and inertia torque T2 of the rotor rotating at the first speed' are respectively smaller than the 'electromagnetic torque T1 and inertia torque T2 of the rotor rotating at the rated speed', it is only necessary to pass a relatively small current (the current is smaller than the current passed through the A-phase winding and the B-phase winding when starting at the rated speed under low temperature conditions) through the A-phase winding and the B-phase winding in the power-on sequence of the A-phase winding and the B-phase winding, so that the rotor generates a clockwise circular motion trend, and the position of the N pole of the rotor can be changed, that is, the position of the N pole of the rotor is changed from the sixth position (see Figure 3-7 ) to the fourth position (see Figure 3-4 );

[0141] Under low temperature conditions, the time for the N pole of the rotor rotating at the first speed to change from the sixth position to the fourth position is longer than the time for the N pole of the rotor rotating at the rated speed to change from the sixth position to the fourth position; when the N pole of the rotor is located between the A-phase winding and the B-phase winding (see Figure 3-7 ), the N pole of the rotor is located between the B-phase winding and the C-phase winding (see Figure 3-4 ), since the current power-on sequence maintains the power-on sequence of the A-phase winding and the B-phase winding (A(+)→B(-)), and the current speed of the rotor is relatively slow, before the inertia torque T2 reaches zero torque, the electromagnetic pole S pole of the B-phase winding attracts the N pole of the rotor, and the electromagnetic pole N pole of the A-phase winding repels the N pole of the rotor. At this time, the direction of the electromagnetic torque T1 changes from the clockwise direction (see Figure 2-2 ), and again turns counterclockwise (see Figure 2-1 ), and the electromagnetic torque T1 that is transformed into the counterclockwise direction is the same as the direction of the current inertia torque T2 that has not reached zero torque, and causes the rotor to change from clockwise circular rotation to counterclockwise circular rotation; in other words, when the rotor changes to clockwise rotation, and the position of the N pole of the rotor changes from the position between the A-phase winding and the B-phase winding (see Figure 3-7), and then shift to a position between the B-phase winding and the C-phase winding (see Figure 3-4 ), the N pole of the rotor will not continue to move to the first position (see Figure 3-1 ) direction, so that the amplitude of the clockwise rotation of the rotor decreases;

[0142] Therefore, since the amplitude of the clockwise rotation of the rotor is reduced, the rotor will not swing or oscillate violently, thus avoiding the occurrence of shutdown or runaway.

[0143] Therefore, the control method of the electronic water pump 1 provided in this embodiment solves the technical problem of how to improve the reliability of the cooling system of the new energy vehicle under low temperature conditions.

[0144] Furthermore, on the basis of the aforementioned scheme, under low temperature conditions, since the coolant in the semi-fluid state is not absorbed by the electronic water pump 1, the coolant in the semi-fluid state cannot circulate in the cooling channel, which will cause the vehicle heat source 4 (three-electric system) of the new energy vehicle to fail due to excessive thermal decay time; therefore, under low temperature conditions, when the electronic water pump 1 works at the first speed, the electronic water pump 1 must increase the speed of the impeller to absorb the coolant in the semi-fluid state. Then, when absorbing the coolant in the semi-fluid state, how to avoid violent swinging or oscillation of the rotor, and thus avoid the occurrence of motor shutdown or runaway of the electronic water pump 1, becomes a technical problem to be solved.

[0145] In this embodiment, after the electronic water pump 1 is started and the operating speed of the electronic water pump 1 is limited to the first speed, it is first necessary to determine whether the current impeller has completed the work of stirring the coolant in a semi-fluid state.

[0146] It has been proposed in the foregoing that the impeller of the electronic water pump 1 whips the coolant in a semi-fluid state, so that the coolant is whipped from the first coolant to the second coolant, or even to the liquid coolant. The actual purpose is to accelerate the phase change speed of the coolant, specifically to make the semi-fluid coolant return to the liquid coolant faster.

[0147] If the coolant in the semi-fluid state remains the first coolant after being stirred by the impeller, or is stirred so that one part is the first coolant and the other part is the second coolant, then, on the one hand, the state of the rotor of the current motor is unstable. Specifically, the rotor can still swing or oscillate when rotating at the first speed. On the other hand, if the current working speed of the electronic water pump 1 is increased immediately, then, while the coolant in the semi-fluid state is absorbed, the stirred coolant in the semi-fluid state is pushed out of the pump body of the electronic water pump 1, and Flowing in the cooling channel, this causes the coolant in a semi-fluid state that has been flowing in the cooling channel and has been whipped to be restored to a liquid state only by absorbing the heat of the vehicle heat source 4 (three-electric system), and if the coolant after absorbing the heat of the vehicle heat source 4 still maintains a semi-fluid state, the coolant that still maintains a semi-fluid state flows into the water tank 3, waiting to be drawn by the electronic water pump 1 next time, so that the coolant that still maintains a semi-fluid state needs to be whipped by the impeller of the electronic water pump 1 again until it is restored to a liquid coolant;

[0148] Therefore, it can be known from the above contents that before the coolant in the semi-fluid state that has been whipped by the impeller is restored to the liquid state or converted into the second coolant, if a new coolant in the semi-fluid state is drawn and the coolant in the semi-fluid state that is currently whipped is pushed out of the pump body, then it is possible that the coolant in the semi-fluid state needs to be whipped a second, third or more times, resulting in low efficiency in restoring the coolant in the semi-fluid state to the liquid state.

[0149] Therefore, before increasing the operating speed of the electronic water pump 1, it is necessary to determine whether the current impeller has completed the work of stirring the coolant in a semi-fluid state, so as to improve the efficiency of restoring the coolant to a liquid state. How to determine whether the current impeller has completed the work of stirring the coolant in a semi-fluid state is preferably achieved by adopting the following technical solution.

[0150] In this embodiment, the control method of the electronic water pump 1 further includes:

[0151] Pre-set multiple detection cycles;

[0152] Presetting a first current threshold, wherein the first current threshold is specifically a three-phase current of the motor when the coolant in a semi-fluid state can only be stirred by the impeller but cannot be drawn;

[0153] The received three-phase current of the motor of the electronic water pump 1;

[0154] In any detection cycle, and before increasing the operating speed of the electronic water pump 1, it is determined whether the three-phase currents meet the first current threshold value to obtain a stability determination result;

[0155] In any detection cycle, and before increasing the operating speed of the electronic water pump 1, it is determined whether the current trend of the three-phase current is a downward trend, and a trend determination result is obtained;

[0156] According to the stability judgment result and the trend judgment result, the whipping state of the coolant is obtained;

[0157] Under the condition that the stability judgment result is yes and the trend judgment result is yes, the whipping state of the coolant is obtained as a result of completed whipping; otherwise, the whipping state of the coolant is obtained as a result of incomplete whipping.

[0158] Among them, the detection period is obtained by experimental means;

[0159] For example, an electronic water pump 1 is selected, and under low temperature conditions, the electronic water pump 1 is started and the start time node t0 of the electronic water pump 1 is recorded, and the working speed of the electronic water pump 1 is limited to the first speed, so that the impeller whips the coolant in a semi-fluid state at the first speed, and when the working speed of the electronic water pump 1 reaches the first speed, the first time node t1 is recorded, and when the experimenter obtains that the coolant in a semi-fluid state is whipped into a liquid state or whipped into a second coolant, the second time node t2 is recorded, and the experiment is repeated multiple times, and the first time node t1 and the second time node t2 of each experiment are recorded, and the average value of the first time node t1 and the average value of the second time node t2 are obtained, and the time length determined by the average value of the first time node t1 and the average value of the second time node t2 is used as the detection period;

[0160] For another example, select an electronic water pump 1, and still repeat the experiment under the aforementioned low temperature conditions, record multiple first time nodes t1 and second time nodes t2, and use the minimum time length determined from the first time node t1 to the second time node t2 as the detection period.

[0161] When multiple detection cycles are set, the second time node t2 of the previous detection cycle overlaps with the first time node t1 of the next detection cycle in the time direction.

[0162] After obtaining the detection period, the experimenter should set the detection period as data in the program to be executed by the controller 5, and the controller 5 can read the data of the detection period in the program for calculation.

[0163] The first current threshold is obtained experimentally;

[0164] For example: select an electronic water pump 1, start the electronic water pump 1 under low temperature conditions, and start the operating speed of the electronic water pump from zero speed, and gradually and slightly (for example, 50 or 100 rpm). The experimenter observes the flow rate of the coolant and records the three-phase current of the motor of the electronic water pump. When the flow rate of the coolant changes from zero flow rate to non-zero flow rate, stop recording the three-phase current of the motor, and record the current data obtained before 'the flow rate of the coolant changes from zero flow rate to non-zero flow rate' as the first current threshold.

[0165] When the electronic water pump 1 is arranged on the new energy vehicle and the electronic water pump 1 is started, within any detection cycle, the controller 5 receives the three-phase current of the motor, and the controller 5 compares the received three-phase current with the first current threshold value respectively; if the three-phase current does not meet the first current threshold value, it means that the current impeller is still stirring the coolant in a semi-fluid state, and the rotor of the motor still has a relatively large swing or oscillation, and the stability of the rotor of the current motor is relatively low. At this time, the judgment result of the stability is no; on the contrary, if the three-phase current meets the first current threshold value, it means that although the current impeller is still stirring the coolant in a semi-fluid state, the rotor of the motor only has a relatively small swing or oscillation, and the stability of the rotor of the current motor is relatively high. At this time, the judgment result of the stability is yes;

[0166] At the same time, in any detection cycle, the controller 5 determines whether the current trend of the three-phase current is a downward trend; when the current trend of the three-phase current is determined to be a downward trend, the generated trend judgment result is yes; conversely, when the current trend of the three-phase current is determined to be a non-downward trend, the generated trend judgment result is no;

[0167] If the stability judgment result is yes, it means that the current impeller is beating the coolant in the semi-fluid state in a stable state, and if the trend judgment result is yes, it means that the coolant in the semi-fluid state has been transformed from the first coolant to the second coolant or the liquid coolant. At this time, the beating state of the coolant is obtained as the result of completing the beating.

[0168] If the stability judgment result is yes, it means that the current impeller is beating the coolant in the semi-fluid state in a stable state, and if the trend judgment result is no, it means that the coolant in the semi-fluid state is in the process of transforming from the first coolant to the second coolant or the liquid coolant. At this time, the beating state of the coolant is the result of incomplete beating.

[0169] When the stability judgment result is no, it means that the current impeller is beating the coolant in the semi-fluid state in an unstable state. At this time, it is meaningless whether the trend judgment result is yes or no, because the impeller is beating the coolant in the semi-fluid state in an unstable state, which means that the load on the impeller is in a drastic change, and the coolant in the semi-fluid state still maintains the first coolant. At this time, the beating state of the coolant is the result of incomplete beating.

[0170] Furthermore, when the beating state of the coolant is obtained to be an unfinished state, the current operating speed of the electronic water pump 1 is maintained.

[0171] If the whipping state of the coolant is incomplete, it means that the coolant currently being whipped is still the first coolant. At this time, the coolant in the semi-fluid state needs to continue to be whipped at the first speed until the whipping state of the coolant is completed.

[0172] More specifically, as to how to compare the three-phase current with the first current threshold to obtain a stability judgment result, and how to judge the current trend of the three-phase current, it is preferably implemented by adopting the following technical solution.

[0173] In the control method of the electronic water pump of this embodiment, the first current threshold value includes a maximum value and a minimum value;

[0174] If the maximum values ​​of the three-phase currents are respectively less than the maximum values ​​of the first current threshold, and the minimum values ​​of the three-phase currents are respectively greater than the minimum values ​​of the first current threshold, the stability judgment result is yes, otherwise, the stability judgment result is no;

[0175] In any cycle, if the maximum value of the three-phase current at a later moment forms a sudden high state relative to the maximum value of the three-phase current at the previous moment, and / or the minimum value of the three-phase current at a later moment forms a sudden low state relative to the minimum value of the three-phase current at the previous moment, then the trend judgment result is no, otherwise, the trend judgment result is yes.

[0176] See also Figure 4-1 , in the process of comparing the three-phase current obtained by the controller 5 with the first current threshold, if the maximum value i1 of the three-phase current received by the controller 5 is greater than the maximum value i_max of the first current threshold, the controller 5 generates a maximum value judgment result of no; conversely, if the maximum value i1 of the three-phase current received by the controller 5 is less than the maximum value i_max of the first current threshold, the controller 5 generates a maximum value judgment result of yes;

[0177] Similarly, see Figure 4-1, if the minimum value i2 of the three-phase current received by the controller 5 is less than the minimum value i_min of the first current threshold, the controller 5 generates a minimum value judgment result of no; conversely, if the minimum value i2 of the three-phase current received by the controller 5 is greater than the minimum value i_min of the first current threshold, the controller 5 generates a minimum value judgment result of yes;

[0178] Under the condition that the maximum value judgment result is yes and the minimum value judgment result is yes, a result that satisfies the first current threshold is obtained, which indicates that although the current impeller still stirs the coolant in a semi-fluid state, the rotor of the motor has only a relatively small swing or oscillation, and the stability of the rotor of the current motor is relatively high;

[0179] Under the condition that one of the maximum value judgment result and the minimum value judgment result is negative, a result that does not meet the first current threshold is obtained, which indicates that the current impeller is still stirring the coolant in a semi-fluid state, and the rotor of the motor still has a relatively large swing or oscillation, and the stability of the rotor of the current motor is relatively low;

[0180] The stability judgment result can be obtained through the above-mentioned maximum value comparison method and minimum value comparison method, and the rest will not be repeated.

[0181] In each detection cycle, the controller 5 obtains the maximum value i1 of the three-phase current and the minimum value i2 of the three-phase current at any moment in the three-phase current respectively;

[0182] At any two adjacent moments in each detection cycle, the maximum value i1 of the three-phase current at the previous moment is compared with the maximum value i1 of the three-phase current at the next moment. If the maximum value i1 of the three-phase current at the next moment is greater than the maximum value i1 of the three-phase current at the previous moment, the state of the maximum value i1 of the three-phase current is a sudden high state. On the contrary, if the maximum value i1 of the three-phase current at the next moment is less than the maximum value i1 of the three-phase current at the previous moment, the state of the maximum value i1 of the three-phase current is a stable state.

[0183] Similarly, in two adjacent moments, the minimum value i2 of the three-phase current at the previous moment is compared with the minimum value i2 of the three-phase current at the next moment. If the minimum value i2 of the three-phase current at the next moment is less than the minimum value i2 of the three-phase current at the previous moment, the state of the minimum value i2 of the three-phase current is a sudden low state. On the contrary, if the minimum value i2 of the three-phase current at the next moment is greater than the minimum value i2 of the three-phase current at the previous moment, the state of the minimum value i2 of the three-phase current is a stable state.

[0184] In any detection cycle, under the condition that the maximum value i1 of the three-phase current is in a sudden high state and / or the minimum value i2 of the three-phase current is in a sudden low state, the current trend of the current three-phase current is obtained as a non-downward trend, indicating that the coolant in the semi-fluid state is in the process of transforming from the first coolant to the second coolant or the liquid coolant;

[0185] In any detection cycle, under the condition that the maximum value i1 of the three-phase current and the minimum value i2 of the three-phase current are respectively in the regional stable state, the current trend of the current three-phase current is a downward trend, indicating that the coolant in the semi-fluid state has been transformed from the first coolant to the second coolant or the liquid coolant;

[0186] The trend judgment result can be obtained by comparing the maximum value i1 of the three-phase current and the minimum value i2 of the three-phase current, and the rest will not be described in detail.

[0187] Through the above content, it can be achieved that before increasing the working speed of the electronic water pump 1, it is determined whether the current impeller has completed the work of stirring the coolant in a semi-fluid state.

[0188] Furthermore, after obtaining the whipping state of the coolant as completed whipping and before increasing the speed of the electronic water pump 1, it is necessary to determine whether all the semi-fluid coolants in the cooling channel have been completely whipped into liquid or completely whipped into the second coolant; this is because, if all the coolants in the cooling channel have been completely whipped into liquid coolant or completely whipped into the second coolant, it means that the current medium state of the coolant has been restored to or close to the medium state of the liquid coolant. At this time, it is necessary to change the control mode of the electronic water pump 1 to a control mode that matches the normal temperature conditions; if the control mode is not changed, since the current operating speed of the electronic water pump 1 does not reach the rated speed of the motor, the current flow rate of the coolant in the cooling channel is less than the flow rate of the coolant in the cooling channel under normal temperature conditions, resulting in the medium state of the coolant being converted to the medium state equal to or close to the medium state of the coolant under normal temperature conditions. The flow rate of the coolant is relatively slow, resulting in low cooling efficiency of the cooling system.

[0189] The control method of the electronic water pump 1 of this embodiment further includes:

[0190] Presetting a second current threshold, wherein the second current threshold is a three-phase current when the operating speed of the electronic water pump 1 is limited to the rated speed under normal temperature conditions and the electronic water pump 1 performs work on the coolant;

[0191] Under the condition that the whipping state of the coolant is whipping completion, a characteristic judgment result is obtained by comparing the three-phase current of any detection cycle with the second current threshold;

[0192] The coolant state judgment result is obtained based on the characteristic judgment results of multiple consecutive detection cycles.

[0193] The second current threshold is obtained by experimental means; for example, an electronic water pump 1 is selected, and the electronic water pump 1 is started at normal temperature. The operating speed of the electronic water pump 1 is first limited to the rated speed, and work is performed on the liquid coolant. The three-phase current of the motor during the work is recorded and used as the second current threshold.

[0194] The second current threshold value should be set as data in a program for execution by the controller 5 , and the controller 5 can read the second current threshold value and perform calculation.

[0195] Under low temperature conditions, and when the whipping state of the coolant is the whipping completion condition, in any detection cycle, the controller 5 compares the received three-phase current of the motor of the electronic water pump 1 with the second current threshold value to obtain the characteristic judgment result in any detection cycle;

[0196] The characteristic judgment result is used to indicate whether the three-phase current received by the controller 5 is within a reasonable range of the second current threshold value during the detection cycle; if it is within a reasonable range, it means that the semi-fluid coolant in the current detection cycle has been whipped into liquid coolant or the second coolant; if it is not within a reasonable range, it means that the semi-fluid coolant in the current detection cycle still contains the first coolant.

[0197] In multiple consecutive detection cycles, if the characteristic judgment results obtained in each detection cycle are within a reasonable range, it means that all the coolant in the cooling channel has been completely whipped into liquid coolant or the second coolant; conversely, if in multiple consecutive detection cycles, the characteristic judgment results obtained in at least one detection cycle are not within a reasonable range, it means that the coolant in the cooling channel has not been completely whipped into liquid coolant or the second coolant.

[0198] Specifically, how to judge whether the three-phase current received by the controller 5 is within a reasonable range of the second current threshold value is preferably implemented by adopting the following technical solution;

[0199] The control method of the electronic water pump 1 of this embodiment calculates and obtains the extreme value difference and the integral sum of the second current threshold value;

[0200] Pre-set the ratio threshold of the extreme value difference and the ratio threshold of the integral sum;

[0201] Calculate and obtain the extreme value difference and integral sum of the three-phase currents in any detection cycle;

[0202] In any detection cycle, a first ratio of the extreme value difference of the three-phase current to the extreme value difference of the second current threshold is calculated and obtained. If the first ratio meets the ratio threshold of the extreme value difference, the calculation result of the first ratio is yes, otherwise, the calculation result of the first ratio is no;

[0203] In any detection cycle, a second ratio of the integral sum of the three-phase currents to the integral sum of the second current threshold is calculated and obtained, if the second ratio meets the ratio threshold of the integral sum, the calculation result of the second ratio is yes, otherwise, the calculation result of the second ratio is no;

[0204] If the calculation result of the first ratio is yes and the calculation result of the second ratio is yes, the feature judgment result is yes, otherwise, the feature judgment result is no;

[0205] Under the condition that the characteristic judgment results of multiple consecutive detection cycles are respectively yes, the state judgment result of the coolant is liquid, otherwise, the state judgment result of the coolant is semi-fluid.

[0206] Wherein, extreme value difference, integral and sum are respectively special terms known to those skilled in the art;

[0207] Furthermore, on the basis of obtaining the second current threshold, the method of calculating and obtaining the second current threshold is common knowledge known to those skilled in the art, and will not be described in detail here;

[0208] Furthermore, when the controller 5 obtains the three-phase current of any detection cycle, the method of calculating and obtaining the three-phase current is the same as the method of calculating the second current threshold value described above.

[0209] The proportional threshold of extreme value difference and the proportional threshold of integral sum should be obtained through experiments;

[0210] For example, an electronic water pump 1 is selected and used to conduct experiments under normal temperature and low temperature conditions. Under normal temperature conditions, the electronic water pump 1 is started, and the operating speed of the electronic water pump 1 is limited to the rated speed of the motor, and the electronic water pump 1 is made to work on the coolant, and the three-phase current of the motor is recorded (see Figure 4-2 In the figure, i_a represents the maximum current when the electronic water pump does work on the coolant at normal temperature, i_b represents the minimum current when the electronic water pump does work on the coolant at normal temperature, and the curve between i_a and i_b represents the curve of the three-phase current at normal temperature);

[0211] Under low temperature conditions, the electronic water pump 1 is started, and the working speed of the electronic water pump 1 is limited to the first speed, and the electronic water pump 1 can only stir the coolant in a semi-fluid state but cannot draw the coolant in a semi-fluid state, and the three-phase current of the motor is recorded (see Figure 4-2In the figure, i_A represents the maximum current when the electronic water pump works on the coolant under low temperature conditions, i_B represents the minimum current when the electronic water pump works on the coolant under low temperature conditions, and the curve between i_A and i_B represents the curve of the three-phase current under low temperature conditions);

[0212] Next, the recorded three-phase currents under normal temperature conditions are calculated to obtain the extreme value difference, integral sum and the three-phase current under normal temperature conditions respectively;

[0213] Correspondingly, the recorded three-phase currents under low temperature conditions are calculated to obtain the extreme value difference, integral sum, and the three-phase current under low temperature conditions respectively;

[0214] Then, the 'extreme value difference of the three-phase current under low temperature conditions' and the 'extreme value difference under normal temperature conditions' are compared in percentage using Formula 1 to obtain the ratio of the extreme value differences, which is used as the aforementioned ratio threshold of the extreme value differences;

[0215] Formula 1:

[0216]

[0217] Similarly, the 'integral sum of the three-phase current under low temperature conditions' and the 'integral sum under normal temperature conditions' are compared in percentage using Formula 2 to obtain the ratio of the integral sums, which is used as the aforementioned ratio threshold of the integral sums;

[0218] Formula 2:

[0219]

[0220] To facilitate understanding by those skilled in the art, in this embodiment, the ratio threshold of the extreme value difference is preferably set to 0-5%, and the ratio threshold of the integral sum is preferably set to 0-3%.

[0221] The extreme value difference and the integral sum of the second current threshold, the preset ratio threshold of the extreme value difference, and the ratio threshold of the integral sum should be respectively set in the program for execution by the controller 5. The controller 5 can read the extreme value difference and the integral sum of the second current threshold, the preset ratio threshold of the extreme value difference, and the ratio threshold of the integral sum, and use them for calculation.

[0222] In the process of actually controlling the electronic water pump using the control method of the electronic water pump of the present embodiment, under low temperature conditions, after starting the electronic water pump, in any detection cycle, the controller 5 can respectively obtain the calculation result of the first ratio and the calculation result of the second ratio in each detection cycle; wherein, under the condition that the first ratio satisfies the ratio threshold of the extreme value difference, the calculation result of the first ratio is yes, otherwise, the calculation result of the first ratio is no; and, under the condition that the second ratio satisfies the ratio threshold of the integral sum, the calculation result of the second ratio is yes, otherwise, the calculation result of the second ratio is no;

[0223] For example, if the first ratio is 6%, it does not meet the set extreme value difference ratio threshold (0-5%), and the calculation result of the first ratio is no; if the first ratio is 4%, it meets the set extreme value difference ratio threshold (0-5%), and the calculation result of the first ratio is yes;

[0224] For example: if the second ratio is 4%, it does not meet the set integral sum ratio threshold (0-3%), and the calculation result of the second ratio is no; if the second ratio is 0.5%, it meets the set extreme value difference ratio threshold (0-5%), and the calculation result of the second ratio is yes.

[0225] In multiple consecutive detection cycles, if the calculation result of the first ratio and the calculation result of the second ratio in each detection cycle are respectively yes, it means that all the coolant in the cooling channel has been completely reduced to liquid coolant or whipped into the second coolant. Conversely, if the calculation result of the first ratio or the calculation result of the second ratio in at least one of the detection cycles is no, it means that the first coolant still exists in the cooling channel.

[0226] It should be understood that the electronic water pump 1 does work on the coolant. From the perspective of the cooling channel, the flow direction of the coolant in the cooling channel is a unidirectional flow direction. After the electronic water pump 1 does work on the coolant, the coolant worked by the electronic water pump 1 flows along the direction from the electronic water pump 1 to the heat source 4 of the whole vehicle (three-electric system). Therefore, the second coolant can be restored to a liquid coolant after absorbing the heat of the heat source 4 of the whole vehicle. However, the first coolant cannot be completely restored to a liquid coolant after absorbing the heat of the heat source 4 of the whole vehicle, that is, it still has the first coolant, or a mixture of the first coolant and the second coolant, or a mixture of the first coolant, the second coolant and the liquid coolant; the first coolant, or the mixture of the first coolant and the second coolant, flows into the water tank 3 along the direction from the heat source 4 of the whole vehicle to the water tank 3; along In the direction from the water tank 3 to the electronic water pump 1, the first coolant, or the mixture of the first coolant and the second coolant, reaches the position of the electronic water pump 1 again and is whipped by the electronic water pump 1, which affects the aforementioned 'phase change speed of the coolant', and requires the coolant in the semi-fluid state to be whipped a second, third or more times, resulting in low efficiency in restoring the coolant in the semi-fluid state to the coolant in the liquid state; at the same time, since there is still the first coolant, or the mixture of the first coolant and the second coolant, the whipping time of the impeller of the electronic water pump 1 on the semi-fluid state will be extended, and since the speed of the impeller of the electronic water pump 1 when whipping the semi-fluid state coolant is not the rated speed, the flow rate of the coolant in the cooling channel (regardless of the medium state of the coolant) is low, which reduces the heat dissipation efficiency of the cooling channel to the heat source 4 of the whole vehicle.

[0227] Furthermore, after obtaining the state judgment result of the coolant in the cooling channel, if the state judgment result of the coolant is a semi-fluid state, it means that there is still coolant in a semi-fluid state in the current cooling channel. At the same time, it also means that the coolant to be drawn is most likely a semi-fluid state coolant. In this case, the operating speed of the electronic water pump 1 needs to be increased.

[0228] In the process of increasing the working speed of the electronic water pump 1, in order to avoid the swing or oscillation of the rotor of the motor, the following technical solution is preferably adopted;

[0229] The control method of the electronic water pump 1 of this embodiment further includes:

[0230] A third current threshold is established in advance, wherein the third current threshold is specifically a three-phase current of the motor when the coolant in a semi-fluid state can be stirred by the impeller and can be drawn;

[0231] Pre-establish speed increments;

[0232] When the coolant state is judged to be in a semi-fluid state, the following steps are performed to increase the operating speed of the electronic water pump 1;

[0233] In the step of increasing the speed, each time the working speed of the electronic water pump 1 is increased, the difference between the working speed after the increase and the working speed before the increase is limited to the speed increment;

[0234] The current judgment step, in each process of increasing the working speed of the electronic water pump 1, calculates and obtains the maximum value of the three-phase current, and compares the maximum value of the three-phase current with the third current threshold to obtain a current increase judgment result. If the current increase judgment result is yes, the current increase in the working speed of the electronic water pump 1 is terminated, and the current working speed of the electronic water pump 1 is maintained for a preset time. If the current increase judgment result is no, the speed increase step is executed;

[0235] A speed reducing step, after a preset time is satisfied, reducing the operating speed of the electronic water pump 1 so that the operating speed of the electronic water pump 1 after the reduction is limited to the first speed;

[0236] After executing the rotation speed reducing step, the rotation speed increasing step and the current judging step are repeatedly executed until the state judgment result of the coolant is liquid.

[0237] The third current threshold value should be obtained by experimental means; for example, an electronic water pump 1 is selected, and the electronic water pump 1 is started under low temperature conditions, and the working speed of the electronic water pump 1 is first limited to the first speed; then, according to the technical solutions proposed in the above content, the state judgment result of the coolant is obtained; under the condition that the coolant is judged to be in a semi-fluid state, the working speed of the electronic water pump 1 is changed so that the working speed after the change is greater than the working speed before the change;

[0238] During the experiment, each time the working speed of the electronic water pump 1 is changed, the speed increment of the working speed should be relatively small; during the experiment, or in the control method of the electronic water pump 1 of the present embodiment, the speed increment can be set according to experience, for example, from the perspective of speed, the speed increment includes but is not limited to 10 rpm to 100 rpm, or, from the perspective of proportion, the speed increment includes but is not limited to 0.1% to N%, where N depends on the upper limit of the working speed; for the convenience of understanding by those skilled in the art, N% can be set to 10% to 25% for reference, so that the speed increment can be set to a minimum threshold of 0.1% to 10%, or to a maximum threshold of 0.1% to 25%, or to a speed increment greater than the minimum threshold and less than the maximum threshold;

[0239] During the experiment, after changing the working speed of the electronic water pump 1, if the experimenter observes that the coolant in the semi-fluid state in the cooling channel flows, the three-phase current of the motor of the current electronic water pump 1 should be recorded;

[0240] The experiment is repeated, and the three-phase current of the motor is measured when multiple semi-fluid state coolants begin to flow. The average value of the three-phase current can be taken as the third current threshold, and the minimum value and / or maximum value of the three-phase current can also be taken as the third current threshold.

[0241] The method for obtaining the rotation speed increment has been proposed in the aforementioned experimental content of the third current threshold, and will not be repeated here.

[0242] In actual applications, when the aforementioned coolant is judged to be in a semi-fluid state, it means that the coolant to be drawn is still in a semi-fluid state. At this time, the working speed of the electronic water pump 1 is increased, and the working speed after each increase is the sum of the previous working speed and the speed increment.

[0243] In the process of increasing the working speed of the electronic water pump 1, on the one hand, the impeller continues to stir the coolant and pushes the already stirred coolant (liquid coolant or second coolant) out from the outlet of the pump body of the electronic water pump 1, and on the other hand, the impeller draws the coolant in a semi-fluid state at the inlet of the pump body into the pump body of the electronic water pump 1, and the semi-fluid coolant drawn into the pump body is stirred by the impeller; from the perspective of the semi-fluid coolant drawn into the pump body, the semi-fluid coolant gradually changes from the first coolant to the second coolant, or even to the liquid coolant during the process of being stirred by the impeller;

[0244] After the operating speed of the electronic water pump 1 is increased, the three-phase current of the motor rises (increases) in an oscillating manner. This is because, after the operating speed of the electronic water pump 1 is increased, the kinetic energy of the impeller doing work on the sucked-in coolant in a semi-fluid state is greater than the kinetic energy of the impeller doing work on the coolant in a semi-fluid state when the impeller rotates at the first speed, resulting in an increase in the reaction force of the semi-fluid coolant on the impeller, which increases the load on the impeller. In addition, since the medium state of the semi-fluid coolant has not been changed at this time, the load on the impeller fluctuates, and the fluctuation variation is random.

[0245] After increasing the operating speed of the electronic water pump 1, and in the process of the impeller stirring the coolant in a semi-fluid state, in order to avoid the swing or oscillation of the motor rotor, the controller 5 calculates the received three-phase current of the motor, obtains the maximum value of the three-phase current, and compares the maximum value of the three-phase current with the third current threshold to obtain a current increase judgment result.

[0246] Specifically, the current boost judgment result is obtained through the following technical solution:

[0247] Pre-establishing a current ratio threshold;

[0248] Obtaining a critical current value in the third current threshold, wherein the critical current value is a current value of the rotor when a sudden change in load torque T3 occurs;

[0249] A third ratio of the maximum value of the three-phase current to the critical current value is calculated and obtained. If the third ratio meets the current ratio threshold, the current increase judgment result is yes, otherwise, the current increase judgment result is no.

[0250] Among them, the critical current value should be obtained through experiments; for example, in the aforementioned experiment to obtain the third current threshold, the experimenter compares the recorded three-phase current data with the state of the rotor, and obtains multiple three-phase current values ​​​​that match the rotor when swinging or oscillating in the three-phase current data, and uses the minimum value of the multiple three-phase current values ​​as a reference to set the critical current value to be less than the minimum value of the three-phase current value.

[0251] The current ratio threshold should be obtained through experiments; for example, in the aforementioned experiment to obtain the critical current value, after obtaining the critical current value, the experimenter compares the recorded three-phase current data with the rotor state, obtains multiple three-phase current data that match the rotor when there is no swing or oscillation, and compares any three-phase current data with the critical current value to obtain multiple ratios. The average value of multiple ratios or the maximum value of multiple ratios can be selected as the current ratio threshold.

[0252] To facilitate understanding by those skilled in the art, in this embodiment, the current ratio threshold is set to 90% to 95%; it should be understood that in other embodiments, the current ratio threshold may also be set to other thresholds.

[0253] The current ratio threshold value and the critical current value should be set as data in a program for execution by the controller 5 , and the controller 5 can read the current ratio threshold value and the critical current value and perform calculations.

[0254] Take the current ratio threshold value set to 90%~95% as an example; if the third ratio is between 90% and 95%, for example, the third ratio is 93%, then the result of the third ratio meeting the current ratio threshold value is obtained, which means that the three-phase current received by the current controller 5 is close to, but not exceeded, the current when the rotor has a sudden load torque change. At this time, the current increase judgment result is yes; conversely, if the third ratio is less than 90%, for example, the third ratio is 67%, then it means that the three-phase current received by the current controller 5 is not close to the current when the rotor has a sudden load torque change. At this time, the current increase judgment result is no.

[0255] It should be understood that if the third ratio is greater than 95%, for example, the third ratio is 97%, due to the lag in detection and calculation, when the third ratio is 97%, the rotor of the motor may have already swung or oscillated; at this time, the controller 5 should directly change the operating speed of the electronic water pump 1 to the first speed, that is, no control action is taken to maintain the current speed, nor is any control action taken to increase the rotation.

[0256] If the current increase judgment result is yes, it means that the three-phase current received by the controller 5 is close to, but has not yet reached, the current value corresponding to the swing or oscillation phenomenon of the motor rotor. At this time, the controller 5 stops increasing the working speed of the electronic water pump 1 and maintains the current working speed. The purpose is to allow the electronic water pump 1 to continue to stir the coolant in a semi-fluid state and avoid the swing or oscillation phenomenon of the motor rotor.

[0257] Furthermore, in the process of the controller 5 maintaining the current working speed, if the controller 5 maintains the current working speed for a relatively long time, the rotor load torque T3 is prone to sudden changes, thereby causing the rotor to swing or oscillate; this is because the coolant in the semi-fluid state whipped by the impeller has not yet been whipped into a liquid coolant or a second coolant, and the coolant in the semi-fluid state that is currently whipped is pushed out from the outlet of the pump body by the impeller doing work at a later moment, and at the same time, the coolant in the semi-fluid state at the inlet of the pump body is drawn into the pump body and whipped by the impeller. Since the current working speed of the electronic water pump 1 is greater than the first speed, the rotor load torque T3 is prone to sudden changes;

[0258] In order to avoid a sudden change in the load torque T3 of the rotor, the controller 5 should reduce the working speed of the electronic water pump 1 when the time for maintaining the current working speed meets the preset time, so that the working speed of the electronic water pump 1 after the reduction is the first speed;

[0259] In order to avoid the phenomenon of sudden change of the load torque T3 of the rotor, the above-mentioned preset time should be obtained through experiments; for example, select an electronic water pump 1 and a type of coolant, start the electronic water pump 1 under low temperature conditions, first limit the working speed of the electronic water pump 1 to a first speed, then increase the working speed of the electronic water pump 1 according to the speed increment, and when the above-mentioned current judgment result is yes, maintain the current working speed of the electronic water pump 1 through the controller 5. At this time, the controller 5 starts timing until the rotor of the motor of the electronic water pump 1 swings or oscillates, terminates the timing, and obtains the timing time length, and sets the preset time to be less than the timing time length.

[0260] If the current increase judgment result is no, it means that the three-phase current received by the controller 5 is far from reaching the current value corresponding to the swing or oscillation of the motor rotor. At this time, the controller 5 should continue to increase the working speed of the electronic water pump 1, that is, on the basis of the previous increase in the working speed of the electronic water pump 1, the controller 5 once again increases the working speed of the electronic water pump 1, and the working speed after the second increase is the sum of the working speed increased last time and the speed increment.

[0261] Regardless of whether the current increase judgment result is yes or no, the speed increase step and the current judgment step need to be repeatedly executed respectively, but the number of steps executed is different according to the current increase judgment result;

[0262] Specifically, under the condition that the result of the current increase judgment is yes, the steps of reducing the speed, judging whether the whipping state of the coolant is completed, judging the medium state of all the coolants in the cooling channel, increasing the speed, and judging the current are respectively performed;

[0263] Under the condition that the result of the current increase judgment is no, the speed increase step and the current judgment step are respectively executed.

[0264] Further, under the condition that the state of the coolant is determined to be liquid, or under the condition that the second instruction is generated, the rated speed of the motor of the electronic water pump 1 is set as the operating speed of the electronic water pump 1;

[0265] In the process of repeatedly executing the speed increasing step and the current judging step, if the coolant state judgment result is liquid, the repetitive execution of the speed increasing step and the current judging step is terminated; at this time, it means that all the coolant in the cooling channel is already in liquid coolant or second coolant, and the controller 5 should limit the working speed of the electronic water pump 1 to the rated speed of the motor. When the electronic water pump 1 works at the rated speed, the heat dissipation efficiency of the coolant to the heat source 4 of the whole vehicle is changed from the heat dissipation efficiency under low temperature conditions to the heat dissipation efficiency matching the normal temperature conditions, which solves the technical problem of 'after the medium state of the coolant is changed to the medium state equal to or close to the medium state of the coolant under normal temperature conditions, the cooling efficiency of the cooling system is low due to the relatively slow flow rate of the coolant'.

[0266] When the controller 5 generates the second instruction, it means that the current temperature environment is higher than the phase change temperature of the coolant, and the current coolant remains in liquid state. Therefore, there is no need to limit the operating speed of the electronic water pump 1 to the first speed according to the control method of the first instruction. Instead, the operating speed of the electronic water pump 1 can be directly limited to the rated speed of the motor according to the control method of the second instruction.

[0267] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A control method for an electronic water pump, characterized in that: include: Pre-establishing a first rotation speed, wherein the first rotation speed is specifically a rotation speed of the motor of the electronic water pump when the coolant in a semi-fluid state can only be stirred by the impeller of the electronic water pump but cannot be sucked; Waiting to receive a start signal; generating a selection instruction according to the received ambient temperature information; Start the electronic water pump; If the generated selection instruction is the first instruction, the first speed is set as the operating speed of the electronic water pump.

2. The control method of the electronic water pump according to claim 1, characterized in that: The step of generating a selection instruction according to the received ambient temperature information is specifically as follows: Pre-establishing a phase transition temperature, wherein the phase transition temperature is specifically a critical temperature at which the coolant changes from a liquid state to a semi-fluid state; Under the condition that the ambient temperature is equal to or lower than the phase change temperature, generating a first instruction; Under the condition that the ambient temperature is higher than the phase change temperature, a second instruction is generated.

3. The control method of the electronic water pump according to claim 2, characterized in that: Also includes: Pre-set multiple detection cycles; Presetting a first current threshold, wherein the first current threshold is specifically a three-phase current of the motor when the coolant in a semi-fluid state can only be stirred by the impeller but cannot be drawn; The three-phase current of the motor of the electronic water pump received; In any detection cycle, and before increasing the operating speed of the electronic water pump, whether the three-phase currents meet the first current threshold is determined to obtain a stability determination result; In any detection cycle, and before increasing the operating speed of the electronic water pump, it is determined whether the current trend of the three-phase current is a downward trend, and a trend determination result is obtained; According to the stability judgment result and the trend judgment result, the whipping state of the coolant is obtained; Under the condition that the stability judgment result is yes and the trend judgment result is yes, the whipping state of the coolant is obtained as a result of completed whipping; otherwise, the whipping state of the coolant is obtained as a result of incomplete whipping.

4. The control method of the electronic water pump according to claim 3, characterized in that: The first current threshold includes a maximum value and a minimum value; If the maximum values ​​of the three-phase currents are respectively less than the maximum values ​​of the first current threshold, and the minimum values ​​of the three-phase currents are respectively greater than the minimum values ​​of the first current threshold, the stability judgment result is yes, otherwise, the stability judgment result is no; In any cycle, if the maximum value of the three-phase current at a later moment forms a sudden high state relative to the maximum value of the three-phase current at the previous moment, and / or the minimum value of the three-phase current at a later moment forms a sudden low state relative to the minimum value of the three-phase current at the previous moment, then the trend judgment result is no, otherwise, the trend judgment result is yes.

5. The control method of the electronic water pump according to claim 3, characterized in that: Also includes: Presetting a second current threshold, wherein the second current threshold is a three-phase current when the operating speed of the electronic water pump is limited to the rated speed under normal temperature conditions and the electronic water pump performs work on the coolant; Under the condition that the whipping state of the coolant is whipping completion, a characteristic judgment result is obtained by comparing the three-phase current of any detection cycle with the second current threshold; The coolant state judgment result is obtained based on the characteristic judgment results of multiple consecutive detection cycles.

6. The control method of the electronic water pump according to claim 5, characterized in that: Calculate and obtain the extreme value difference and the integral sum of the second current threshold; Pre-set the ratio threshold of the extreme value difference and the ratio threshold of the integral sum; Calculate and obtain the extreme value difference and integral sum of the three-phase currents in any detection cycle; In any detection cycle, a first ratio of the extreme value difference of the three-phase current to the extreme value difference of the second current threshold is calculated and obtained. If the first ratio meets the ratio threshold of the extreme value difference, the calculation result of the first ratio is yes, otherwise, the calculation result of the first ratio is no; In any detection cycle, a second ratio of the integral sum of the three-phase currents to the integral sum of the second current threshold is calculated and obtained, if the second ratio meets the ratio threshold of the integral sum, the calculation result of the second ratio is yes, otherwise, the calculation result of the second ratio is no; If the calculation result of the first ratio is yes and the calculation result of the second ratio is yes, the feature judgment result is yes, otherwise, the feature judgment result is no; Under the condition that the characteristic judgment results of multiple consecutive detection cycles are respectively yes, the state judgment result of the coolant is liquid, otherwise, the state judgment result of the coolant is semi-fluid.

7. The control method of the electronic water pump according to claim 6, characterized in that: Also includes: A third current threshold is established in advance, wherein the third current threshold is specifically a three-phase current of the motor when the coolant in a semi-fluid state can be stirred by the impeller and can be drawn; Pre-establish speed increments; When the coolant is in a semi-fluid state, perform the following steps to increase the operating speed of the electronic water pump; In the step of increasing the speed, in each process of increasing the working speed of the electronic water pump, the difference between the working speed after the increase and the working speed before the increase is limited to the speed increment; a current judgment step, in each process of increasing the working speed of the electronic water pump, calculating and obtaining the maximum value of the three-phase current, and comparing the maximum value of the three-phase current with the third current threshold to obtain a current increase judgment result, and if the current increase judgment result is yes, terminating the current increase in the working speed of the electronic water pump, and maintaining the current working speed of the electronic water pump for a preset time, and executing the speed increase step if the current increase judgment result is no; a speed reducing step, after a preset time is satisfied, reducing the operating speed of the electronic water pump so that the operating speed of the electronic water pump after the reduction is limited to the first speed; After executing the rotation speed reducing step, the rotation speed increasing step and the current judging step are repeatedly executed until the state judgment result of the coolant is liquid.

8. The control method of the electronic water pump according to claim 7, characterized in that: Pre-establishing a current ratio threshold; Obtaining a critical current value in the third current threshold, wherein the critical current value is a current value of the rotor when a sudden load torque change occurs; A third ratio of the maximum value of the three-phase current to the critical current value is calculated and obtained. If the third ratio meets the current ratio threshold, the current increase judgment result is yes, otherwise, the current increase judgment result is no.

9. The control method of the electronic water pump according to claim 8, characterized in that: Under the condition that the state of the coolant is determined to be liquid, or under the condition that the second instruction is generated, the rated speed of the motor of the electronic water pump is set as the operating speed of the electronic water pump.

10. The control method of the electronic water pump according to claim 4, characterized in that: When the beating state of the coolant is obtained as an unfinished state, the current operating speed of the electronic water pump is maintained.

Images