Electronic water pump control device and method

Abstract

The invention relates to an electronic water pump control device which comprises a power supply module for supplying power to the whole device, and further comprises a voltage follower, an FOC controller, a pre-drive circuit and an inverter circuit which are connected in sequence, and the inverter circuit is electrically connected with a BLDC motor. The invention further provides an electronic water pump control method. The method comprises the steps that S1, a power source is turned on; s2, the given voltage and the FOC feedback voltage enter a voltage follower to be subjected to an additive operation method, then voltage loop PI operation is carried out to output a given rotating speed, the output given rotating speed and the motor feedback rotating speed are subjected to additive operation, then speed loop PI operation is carried out, and torque reference current is output to an FOC controller; s3, the FOC controller outputs Ua, Ub and Uc to a pre-drive circuit; s4, the pre-drive circuit amplifies the Ua, Ub and Uc signals and then controls the inverter circuit; and S5, the inverter circuit outputs U / V / W to drive the BLDC motor to operate. According to the invention, the problem that part of speed regulation curves fail after the system voltage is reduced and the problem that the flow becomes low due to the change of flow resistance are solved, and the system stability is improved.

Description

Technical Field

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

[0002] BLDCM (Brushless Direct Current Motor), also known as BLDC motor, is an improved motor that combines the advantages of DC motor and AC motor. Its rotor is excited by permanent magnet material, with small size, light weight, simple structure and easy maintenance. BLDC motor has a series of advantages such as simple control, high efficiency and energy saving, and has been widely used in new energy vehicle water pumps, energy storage water pumps and other fields. Most brushless water pumps adopt speed closed-loop design, but under certain specific usage requirements, the debugging range will become narrower; the speed and system flow resistance do not match and other problems will occur.

[0003] Patent Publication No.: CN118346409A mentions that the water pump is speed controlled, and does not discuss the flow and flow resistance of the water pump body, and the speed control curve of flow and voltage is closed; Patent Publication No.: CN118346407A also only discusses the demand for water pumps in the thermal management system. However, both patents have the following problems: 1. In a wide range of system voltage, a section of the speed control curve fails, that is, the water pump flow cannot be adjusted; 2. Due to the change of system flow resistance in the system, a section of the speed control curve fails. The failure of part of the speed control curve caused by these two problems makes the system unable to finely adjust the required heat dissipation requirements, reducing the stability of the system. Summary of the invention

[0004] In view of the above problems, the present invention provides an electronic water pump control device and method for solving the problem of failure of some speed regulation curves after the system voltage is reduced and the problem of low flow rate caused by change in flow resistance, thereby improving system stability.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: an electronic water pump control device, including a power supply module, a voltage follower, a FOC controller, a pre-drive circuit and an inverter circuit, the power supply module is used to power the entire device, the voltage follower, the FOC controller, the pre-drive circuit, and the inverter circuit are connected in sequence and the inverter circuit is electrically connected to the BLDC motor.

[0006] Preferably, the voltage follower comprises a voltage loop PI and a speed loop PI connected in series.

[0007] Preferably, the FOC controller includes a torque PI controller, an excitation PI controller, a coordinate transformation 4, a coordinate transformation 3, a coordinate transformation 1, a coordinate transformation 2 and a speed angle estimator which are electrically connected.

[0008] The present invention also provides an electronic water pump control method, the specific steps are as follows:

[0009] S1, power module is turned on;

[0010] S2, the voltage given by PWM calculation and the FOC feedback voltage Uq_Fdb given by the FOC controller enter the voltage follower for addition operation and then perform voltage loop PI operation to output the speed given. The output speed given and the motor feedback speed are added and then perform speed loop PI operation to output the torque reference current to the FOC controller;

[0011] S3: The FOC controller receives the torque reference current output by the voltage follower, changes the coordinates through the PI controller, and then outputs Ua, Ub, and Uc to the pre-drive circuit;

[0012] S4, the pre-drive circuit amplifies the Ua, Ub, and Uc signals and controls the inverter circuit;

[0013] S5, the inverter circuit outputs U / V / W to drive the BLDC motor to operate.

[0014] Preferably, the specific steps of step S3 are as follows:

[0015] S301, coordinate transformation 1, Ia and Ib output by the inverter circuit undergo coordinate transformation 1, and output Iα and Iβ;

[0016] S302, coordinate transformation 2, coordinate transformation is performed on Iα and Iβ outputted from coordinate transformation 1 to output Iq_Fdb and Id_Fdb;

[0017] S303, a speed / angle estimator calculates Iα, Iβ output by coordinate transformation 1 and Uα, Uβ output by coordinate transformation 3 and outputs a speed S_Fdb and an angle θ;

[0018] S304, the torque reference current Iq_Ref output by the voltage follower and the IQ_Fdb output by the coordinate transformation 2 are added and then the output Uq is calculated by the torque PI controller;

[0019] S305, Id_Ref and Id_Fdb output by coordinate transformation 2 are added and then output Ud is calculated by the excitation PI controller, wherein Id_Ref is a fixed value of 0;

[0020] S306, Uq, Ud and the output angle θ of the speed / angle estimator are input to coordinate transformation 3;

[0021] S307, coordinate transformation 3 outputs Uα and Uβ to coordinate transformation 4, and coordinate transformation 4 receives and transforms the outputs Ua, Ub, and Uc to the pre-driving circuit.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention solves the problem of failure of some speed regulation curves after the system voltage is reduced and the problem of lower flow rate caused by the change of flow resistance, so that the PWM duty cycle (20% to 80%) can be adjusted, thereby improving the stability of the system. At the same time, when the system flow resistance is reduced, the speed of the water pump can be increased, thereby increasing the output flow rate;

[0024] 2. The traditional solution is based on a speed closed loop. When the system voltage changes, the speed is adjusted to a certain value and the speed remains unchanged. However, the present invention uses a voltage loop PI, and the output speed setting can follow the system voltage. That is, when the system voltage increases, the output of the voltage loop PI increases, and when the system voltage decreases, the output of the voltage loop PI decreases, so that the speed regulation curve can follow the system voltage change;

[0025] 3. In the present invention, the FOC feedback voltage and flow resistance follow each other. When the flow resistance increases, the FOC feedback voltage increases, and when the flow resistance decreases, the FOC feedback voltage decreases. That is, the speed output to the speed loop PI through the voltage loop PI automatically adjusts following the flow resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the control device of the present invention;

[0027] Figure 2 It is a schematic diagram of the voltage follower structure in the present invention;

[0028] Figure 3 It is a schematic diagram of the structure of the FOC controller in the present invention;

[0029] Figure 4 It is a schematic diagram of control curves under different system voltages / different flow resistances in the present invention. DETAILED DESCRIPTION

[0030] The following will be combined Figure 1-4 The present invention is described in detail. The exemplary embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0031] An electronic water pump control device and method, comprising a power module, a voltage follower, a FOC controller, a pre-drive circuit and an inverter circuit, wherein the power module is used to supply power to the entire device, the voltage follower, the FOC controller, the pre-drive circuit and the inverter circuit are connected in sequence, and the inverter circuit is electrically connected to a BLDC motor.

[0032] Specifically, the voltage follower includes a voltage loop PI and a speed loop PI connected in series, and the FOC controller includes an electrically connected torque PI controller, an excitation PI controller, a coordinate transformation 4, a coordinate transformation 3, a coordinate transformation 1, a coordinate transformation 2 and a speed angle estimator.

[0033] The voltage given by PWM calculation and the FOC feedback voltage Uq_Fdb given by the FOC controller enter the voltage follower for addition operation and then perform voltage loop PI operation to output the speed given. The output speed given and the motor feedback speed are added and then perform speed loop PI operation to output the torque reference current to the FOC controller.

[0034] The FOC feedback voltage is the percentage of the output voltage and the system voltage. The traditional solution is based on a speed closed loop. When the system voltage changes, the speed remains unchanged. However, this solution uses the voltage loop PI, and the output speed setting can follow the system voltage. That is, when the system voltage increases, the output of the voltage loop PI increases, and when the system voltage decreases, the output of the voltage loop PI decreases, so that the speed control curve can follow the bus voltage change.

[0035] The FOC feedback voltage and flow resistance follow each other. When the flow resistance increases, the FOC feedback voltage increases, and when the flow resistance decreases, the FOC feedback voltage decreases. That is, the speed output to the speed loop PI through the voltage loop PI automatically adjusts following the flow resistance.

[0036] The speed loop PI limits the upper limit Speed_Max and the lower limit Speed_Min of the speed, which can limit the minimum flow rate and the maximum flow rate of the water pump and increase the speed stability of the entire system.

[0037] The present invention also provides an electronic water pump control method, the specific steps are as follows:

[0038] S1, power module is turned on;

[0039] S2, the voltage given by PWM calculation and the FOC feedback voltage Uq_Fdb given by the FOC controller enter the voltage follower for addition operation and then perform voltage loop PI operation to output the speed given. The output speed given and the motor feedback speed are added and then perform speed loop PI operation to output the torque reference current to the FOC controller;

[0040] S3, the FOC controller receives the torque reference current output by the voltage follower and outputs Ua, Ub, and Uc to the pre-drive circuit after coordinate change through the PI controller. The details are as follows:

[0041] S301, coordinate transformation 1, Ia and Ib output by the inverter circuit undergo coordinate transformation 1, and output Iα and Iβ;

[0042] S302, coordinate transformation 2, coordinate transformation is performed on Iα and Iβ outputted from coordinate transformation 1 to output Iq_Fdb and Id_Fdb;

[0043] S303, a speed / angle estimator calculates Iα, Iβ output by coordinate transformation 1 and Uα, Uβ output by coordinate transformation 3 and outputs a speed S_Fdb and an angle θ;

[0044] S304, the torque reference current Iq_Ref output by the voltage follower and the IQ_Fdb output by the coordinate transformation 2 are added and then the output Uq is calculated by the torque PI controller;

[0045] S305, Id_Ref and Id_Fdb output by coordinate transformation 2 are added and then output Ud is calculated by the excitation PI controller, wherein Id_Ref is a fixed value of 0;

[0046] S306, Uq, Ud and the output angle θ of the speed / angle estimator are input to coordinate transformation 3;

[0047] S307, coordinate transformation 3 outputs Uα and Uβ to coordinate transformation 4, and coordinate transformation 4 receives and transforms the outputs Ua, Ub, and Uc to the pre-driving circuit;

[0048] S4, the pre-drive circuit amplifies the Ua, Ub, and Uc signals and controls the inverter circuit;

[0049] S5, the inverter circuit outputs U / V / W to drive the BLDC motor to run.

[0050] During the implementation process, Figure 4 , further explain problem 1, according to the motor voltage balance equation Where Vbus is the power supply voltage, is the inherent characteristic of the motor, I is the controller output current, and R is the internal resistance of the motor.

[0051] When the power supply voltage (system voltage) Vbus decreases, the maximum speed of the motor will decrease from Max2 to Max1. The speed regulation curve is shown in Table 1. As can be seen from Table 1, after using the control method and control device of this solution, when the system voltage is reduced to a low voltage, the speed can be adjusted within the range of 20% to 80% of the PWM duty cycle. Figure 4As shown, in the traditional scheme, the speed regulation curve of the system voltage at the rated voltage is shown by the line from a to b to c, which is a continuously rising oblique straight line, that is, the speed can be adjusted between 20% and 80% of the PWM duty cycle, but when the voltage becomes lower, the speed regulation curve is as shown by the line from a to b to d, where b to d is a horizontal straight line, that is, the speed is not adjustable when the PWM duty cycle is 60%-80%. After adopting the control method and control device of the present scheme, when the system voltage is the rated voltage, the speed regulation curve is also shown by the line from a to b to c, but when the voltage becomes lower, the speed regulation curve is as shown by the line from a to d, that is, the speed is still adjustable when the PWM duty cycle is 60%-80%.

[0052] Table 1

[0053] PWM Duty Cycle Less than 10% 10％N20％ 20％N80％ More than 80% Traditional / This solution rated voltage (speed) 0 Min abc Max2 Traditional solution low voltage (speed) 0 Min abd Max1 This solution has low voltage (speed) 0 Min ad Max1

[0054] pass Figure 4 The same can be said for question 2. In the traditional speed closed loop, the maximum speed max1 is a fixed value. Under different flow resistances (regardless of rated flow resistance or low flow resistance), the speed control curve is shown as the line from a to b to d in the figure. When the PWM duty cycle is between 60% and 80%, the speed control curve fails in the b to d segment and cannot be adjusted. The speed is equal to Max1. After adopting our control method and control device, under rated flow resistance, the speed control curve is shown as the line from a to d. When the rated flow resistance is reduced, that is, under low flow resistance, the speed control curve is shown as the line from a to b to c in the figure, that is, the speed will increase from d to c, and the speed will change from Max1 to Max2, that is, the expected flow rate can be increased. The same control curve is shown in Table 2 below. It can be seen from Table 2 that when the flow resistance is reduced, the speed of the water pump can be increased, thereby increasing the output flow rate.

[0055] Table 2

[0056] PWM Duty Cycle Less than 10% 10％～20％ 20％～80％ More than 80% Traditional solutions with different flow resistance (speed) 0 Min abd Max1 Rated flow resistance (speed) of this solution 0 Min ad Max1 This solution has low flow resistance (speed) 0 Min abc Max2

[0057] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An electronic water pump control device, characterized in that: It includes a power module, a voltage follower, a FOC controller, a pre-drive circuit and an inverter circuit. The power module is used to power the entire device. The voltage follower, the FOC controller, the pre-drive circuit and the inverter circuit are connected in sequence, and the inverter circuit is electrically connected to the BLDC motor.

2. The electronic water pump control device according to claim 1, characterized in that: The voltage follower includes a voltage loop PI and a speed loop PI which are connected in series.

3. The electronic water pump control device according to claim 1, characterized in that: The FOC controller includes a torque PI controller, an excitation PI controller, a coordinate transformation 4, a coordinate transformation 3, a coordinate transformation 1, a coordinate transformation 2 and a rotation speed angle estimator which are electrically connected.

4. An electronic water pump control method, characterized in that: The specific steps are as follows: S1, turn on the power; S2, the voltage given by PWM calculation and the FOC feedback voltage Uq_Fdb given by the FOC controller enter the voltage follower for addition operation and then perform voltage loop PI operation to output the speed given. The output speed given and the motor feedback speed are added and then perform speed loop PI operation to output the torque reference current to the FOC controller; S3, the FOC controller receives the torque reference current output by the voltage follower, performs coordinate change through the PI controller, and then outputs Ua, Ub, and Uc to the pre-drive circuit; S4, the pre-drive circuit amplifies the Ua, Ub, and Uc signals and controls the inverter circuit; S5, the inverter circuit outputs U / V / W to drive the BLDC motor to operate.

5. The electronic water pump control method according to claim 4, characterized in that: The specific steps of step S3 are as follows: S301, coordinate transformation 1, Ia and Ib output by the inverter circuit undergo coordinate transformation 1, and output Iα and Iβ; S302, coordinate transformation 2, coordinate transformation is performed on Iα and Iβ outputted from coordinate transformation 1 to output Iq_Fdb and Id_Fdb; S303, a speed / angle estimator calculates Iα, Iβ output by coordinate transformation 1 and Uα, Uβ output by coordinate transformation 3 and outputs a speed S_Fdb and an angle θ; S304, the torque reference current Iq_Ref output by the voltage follower and the IQ_Fdb output by the coordinate transformation 2 are added and then the output Uq is calculated by the torque PI controller; S305, Id_Ref and Id_Fdb output by coordinate transformation 2 are added and then output Ud is calculated by the excitation PI controller, wherein Id_Ref is a fixed value of 0; S306, Uq, Ud and the output angle θ of the speed / angle estimator are input to coordinate transformation 3; S307, coordinate transformation 3 outputs Uα and Uβ to coordinate transformation 4, and coordinate transformation 4 receives and transforms the outputs Ua, Ub, and Uc to the pre-driving circuit.

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