Electric starting control method, motor controller and electric compressor

Abstract

The invention provides an electric starting control method, a motor controller and an electric compressor. According to the electric starting control method, the motor adopts an IF open-loop starting mode, and IF open-loop starting is transited to non-inductive closed-loop control. In the transition process from IF open-loop starting to non-inductive closed-loop control, motor load torque is estimated based on current operation condition parameters of the motor, and initial current of non-inductive closed-loop control is determined through the motor load torque; and controlling the operation of the motor by taking the initial current as a current regulation target of the motor. According to the electric starting control method, the initial current of non-inductive closed-loop control is determined through estimation to serve as the control switching current of closed-loop control during transition from open-loop starting to non-inductive control, and the motor control effect in the transition switching process from open-loop starting to non-inductive control can be effectively improved; and the problems of switching failure caused by too small switching current, overshoot of rotating speed response caused by too large switching current and the like can be avoided.

Description

Technical Field

[0001] The present invention relates to the field of compressor control technology, and in particular to an electric start control method. In addition, the present invention also relates to a motor controller and an electric compressor. Background Art

[0002] The air-conditioning system is one of the necessary configurations in the car. With the development and popularization of new energy vehicles, as a supporting product of automobile air-conditioning, electric scroll compressors are gradually being widely used in the air-conditioning systems of new energy vehicles.

[0003] Due to the limitations of manufacturing cost, installation space and size, electric scroll compressors are mostly controlled by sensorless control methods. The sensorless control method is generally implemented by combining low-speed IF open-loop start with medium and high-speed sensorless control algorithms.

[0004] Among them, IF open-loop starting, i.e. constant current-frequency ratio starting control, is a speed open-loop and current closed-loop control method. It does not need to keep the ratio of current amplitude and frequency constant, and can select the appropriate current amplitude according to the load torque. IF control can directly control the current amplitude of the stator winding, so this control method will not cause motor overcurrent; by controlling the stator winding current, the motor has better load torque matching capability, and relying on the "torque-power angle self-balancing" characteristic, the motor has a strong ability to resist load disturbances.

[0005] However, the start-up of the compressor needs to go through three consecutive processes: IF open-loop start-up, transition between open-loop and sensorless control, and sensorless control. The current in the IF open-loop start-up phase is generally given a fixed starting current Is. During the transition between the IF open-loop start-up and the sensorless control, the starting current Is is reduced to a level that matches the load. Since the actual load of the motor after the IF start-up is stable cannot be known in advance during the IF start-up phase, it is impossible to accurately apply a matching transition current to the motor; therefore, during the transition from the IF open-loop start-up to the sensorless closed-loop control, it is easy to have a switching failure caused by too small a switching current, or a serious overshoot of the motor response speed caused by too large a switching current.

[0006] Moreover, the transition from IF open-loop control to sensorless control is mostly to gradually reduce the open-loop current according to the motor rotation angle deviation, so as to realize the current transition from open-loop control to closed-loop control; and this transition time depends on the actual load size. When the motor is under a large load condition, the transition time will be longer, which affects the starting performance of the motor and makes it difficult for the motor to enter a stable operation state as soon as possible. Summary of the invention

[0007] In view of this, the present invention aims to provide an electric starting control method to improve the control effect of a motor using IF open-loop starting during the transition process from IF open-loop starting to sensorless closed-loop control.

[0008] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0009] An electric starting control method adopts an IF open-loop starting mode to start a motor, and transitions from the IF open-loop starting mode to a sensorless closed-loop control mode; during the transition from the IF open-loop starting mode to the sensorless closed-loop control mode, the motor load torque is estimated based on the current operating condition parameters of the motor, and the initial current of the sensorless closed-loop control is determined by the motor load torque; and the operation of the motor is controlled by using the initial current as the current regulation target of the motor.

[0010] Furthermore, during the entire transition process, the value of the initial current is updated at a set interval as the operating condition parameters change.

[0011] Furthermore, the interval time is 1s to 5s.

[0012] Furthermore, the operating condition parameters include the control voltage, control current, and motor speed of the motor.

[0013] Furthermore, the motor is controlled using a DQ coordinate system, the control voltage includes a D-axis control voltage and a Q-axis control voltage, and the control current includes a D-axis feedback current and a Q-axis feedback current.

[0014] Furthermore, estimating the motor load torque based on the current operating condition parameters of the motor includes:

[0015] Obtaining the current control voltage, the control current, and the motor speed;

[0016] The current power of the motor is calculated from the control voltage and the control current, and the motor load torque is calculated based on the following formula: motor load torque=current power÷motor speed.

[0017] Further, the determining of the initial current of the sensorless closed-loop control includes:

[0018] Establishing a corresponding function or comparison table between the initial current and the motor load torque;

[0019] The initial current is determined based on the estimated motor load torque by calculating through the corresponding function or by looking up through the comparison table.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] The electric starting control method of the present invention can use a fixed starting current to start the motor during the starting process of the motor using the IF open-loop starting method; further, in the process of transitioning from the IF open-loop starting to the inductive closed-loop control, by estimating and determining 400 of the inductive closed-loop control as the control switching current of the closed-loop control during the transition from the open-loop starting to the inductive control, the motor control effect of the transition switching process from the open-loop starting to the inductive control can be effectively improved, thereby helping to avoid problems such as switching failure caused by too small a switching current, or speed response overshoot caused by too large a switching current.

[0022] In addition, as the motor's operating parameters such as speed, voltage, and current change during the transition process, the value of the initial current is estimated and updated, and the updated initial current is used as the new control target to regulate the operation of the motor, which is beneficial to further improve the control stability of the motor during the transition process.

[0023] Another object of the present invention is to provide a motor controller, comprising a processor and a memory, wherein the memory stores at least one computer program, and the computer program is loaded and executed by the processor to implement the electric starting control method as described in the present invention.

[0024] Furthermore, the operating condition parameters include a control voltage, a control current, and a motor speed of the motor; the control voltage adopts the output voltage of the motor controller, and / or the control current adopts the output current of the motor controller, and / or the motor speed is estimated and obtained by a software observer of the motor.

[0025] In addition, the present invention also proposes an electric compressor, on which the motor controller described in the present invention is provided.

[0026] The motor controller and the electric compressor of the present invention both have the technical advantages possessed by the above-mentioned electric starting control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention. The directional terms such as front and back, up and down, etc. involved therein are only used to indicate relative positional relationships and do not constitute improper limitations on the present invention. In the accompanying drawings:

[0028] Figure 1 This is a control flow diagram of the electric starting control method according to the first embodiment of the present invention;

[0029] Figure 2 A comparison table of initial current and motor load torque according to the first embodiment of the present invention;

[0030] Figure 3 A schematic diagram of a motor speed curve variation when a switching failure is caused by a switching current being too small in the prior art according to the first embodiment of the present invention;

[0031] Figure 4 A schematic diagram of a motor speed curve variation when a speed response overshoot is caused by excessive switching current in the prior art according to the first embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the initial current change, ie, the corresponding motor speed curve change under the electric starting control method described in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0034] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0035] Embodiment 1

[0036] This embodiment relates to an electric starting control method, which can improve the control effect of the transition process from IF open-loop starting to non-sensing closed-loop control of the motor using IF open-loop starting; an exemplary control process is as follows: Figure 1 shown.

[0037] In general, the electric starting control method uses the IF open-loop starting method to start the motor, and then transitions from the IF open-loop starting method to the sensorless closed-loop control method. During the transition from the IF open-loop starting method to the sensorless closed-loop control method, the motor load torque is estimated based on the current operating parameters of the motor, and the initial current of the sensorless closed-loop control is determined by the motor load torque; the initial current is used as the current control target of the motor to control the operation of the motor.

[0038] Of course, the determined initial current can be used as a fixed control target to control the current of the motor, and the motor can eventually smoothly enter a stable non-inductive closed-loop control stage. However, preferably, the value of the initial current should be updated at set intervals during the entire transition process as the operating condition parameters change in response to changes in the operating condition parameters that occur during the transition process. As the speed, voltage, current and other operating condition parameters of the motor change during the transition process, the value of the initial current is estimated and updated, and the operation of the motor is regulated using the updated initial current as the new control target, which is beneficial to further improve the control stability of the motor during the transition process.

[0039] The above interval time can be flexibly set within a reasonable range. In this embodiment, the interval time is set to 1s to 5s. Setting the update interval time of the initial current within the range of 1s (seconds) to 5s (seconds) is suitable for the actual operating condition parameter changes of the motor, and can avoid excessive burden on the control unit due to excessive update frequency. It can be set to 1s, 2s, 3s, 4.5s, etc. In this embodiment, if Figure 5 As shown in , the interval time used is 2s.

[0040] There are of course multiple options for the above-mentioned operating condition parameters. In this embodiment, the operating condition parameters include the motor control voltage, control current, and motor speed. The operating condition parameters mainly use the motor control voltage, control current, and motor speed, which is not only convenient for directly obtaining relevant data through the motor controller, but also based on the above three operating condition data, the motor power and motor load torque can be quickly calculated, providing good conditions for determining the initial current.

[0041] Specifically, the motor of this embodiment is controlled by the DQ coordinate system, the above-mentioned control voltage includes the D-axis control voltage and the Q-axis control voltage, and the control current includes the D-axis feedback current and the Q-axis feedback current. The DQ coordinate system is used to perform control calculations on the motor, which is conducive to simplifying the calculations. The DQ-axis voltage equation is a very important equation in motor control, which describes the voltage component of the motor in the DQ coordinate system. The DQ coordinate system is a special coordinate system that can convert a three-phase AC signal into two orthogonal components, namely the D-axis component and the Q-axis component; this conversion can simplify the calculation and implementation of motor control.

[0042] Still Figure 1 As shown, the above-mentioned situation of estimating the motor load torque based on the current operating condition parameters of the motor can be implemented by referring to the following specific steps:

[0043] Step 1: Get the current control voltage, control current, and motor speed;

[0044] Step 2: Calculate the current power of the motor from the control voltage and control current, and calculate the motor load torque based on the following formula:

[0045] Motor load torque = current power ÷ motor speed.

[0046] After completing the calculation of the motor load torque, the current required for the motor load torque can be calculated according to the motor's own parameters. Preferably, the specific steps for determining the initial current of the inductive closed-loop control in this embodiment are:

[0047] Step 1: Establish a corresponding function or comparison table between the initial current and the motor load torque;

[0048] Step 2: Based on the estimated motor load torque, determine the initial current by calculating the corresponding function or checking the reference table.

[0049] Figure 2 A comparison table of the initial current of the motor and the motor load torque of the present embodiment is provided, through which the magnitude of the initial current required to control the motor can be quickly determined according to the motor load torque.

[0050] pass Figure 3 , Figure 4 and Figure 5 It can be seen from the comparison that in the transition process from IF open-loop start to non-inductive closed-loop control, the traditional start-up control method is used. Since the given fixed start-up switching current Is may not be suitable for the current motor speed and motor load torque, when the switching current is too small, the following may occur: Figure 3 As shown in the figure, when the switching current is too large, the following may occur: Figure 4 The situations shown in the figure; in these two situations, the response speed of the motor is either difficult to reach the target control speed, or the control process performance is unstable and the control effect is poor.

[0051] When the electric starting control method of the present invention is adopted, Figure 5 As shown, the determined initial current conforms to the actual situation of the current motor speed and motor load torque, the motor response speed has high follow-up performance to the control speed, and can smoothly and stably switch to the motor's non-sensing closed-loop control state. The entire startup process is smooth, which not only reduces the probability of switching failure due to too small switching current, but also reduces the serious overshoot of the motor speed due to excessive switching current. In the electric starting control method of this embodiment, by making the given value of the motor rotor position gradually approach the estimated value of the rotor position during the switching process from speed open-loop control to speed closed-loop control, the speed open-loop and closed-loop control switching process is smoothly controlled during the motor startup process, the motor current will not change suddenly, the motor speed is stable, the motor vibration is greatly reduced, the switching success rate is improved, and the switching process is not affected by the load characteristics, with strong versatility and a wide range of applications.

[0052] To summarize, the electric starting control method of the present embodiment can use a fixed starting current to start the motor during the starting process of the motor using the IF open-loop starting method; further, in the process of transitioning from the IF open-loop starting to the sensorless closed-loop control, the initial current of the sensorless closed-loop control is estimated and determined as the control switching current of the closed-loop control during the transition from the open-loop starting to the sensorless control. This can effectively improve the motor control effect during the transition switching process from the open-loop starting to the sensorless control, and is beneficial for avoiding problems such as switching failure caused by too small a switching current, or speed response overshoot caused by too large a switching current.

[0053] Embodiment 2

[0054] The present embodiment relates to a motor controller and an electric compressor.

[0055] The motor controller of this embodiment includes a processor and a memory. The memory stores at least one computer program. The computer program is loaded and executed by the processor to implement the electric starting control method provided in the first embodiment.

[0056] In addition, the above-mentioned operating condition parameters include the control voltage, control current, and motor speed of the motor; based on the fact that the control voltage and control current are both output by the motor controller and the motor speed can be obtained by the motor controller in real time, preferably, the control voltage can use the output voltage of the motor controller, the control current can use the output current of the motor controller, and the motor speed is estimated and obtained by the software observer. The software observer mentioned here can be a separately set calculation and processing functional element, or it can be a software program functional module directly set in the motor controller, which reconstructs the motor model based on the motor feedback current and control voltage signals as references through existing mature calculation methods, thereby calculating accurate observation values ​​of the motor angle and motor speed, and then providing the numerical value of the motor speed required by the electric starting control method to the processor for use.

[0057] The electric compressor of this embodiment adopts the above-mentioned motor controller, thereby greatly improving the start-up control effect of the electric compressor.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electric starting control method, which starts a motor by using an IF open-loop starting method, and transitions from the IF open-loop starting method to a non-sensing closed-loop control method; characterized in that: During the transition process from the IF open-loop start-up to the sensorless closed-loop control, the motor load torque is estimated based on the current operating condition parameters of the motor, and the initial current of the sensorless closed-loop control is determined by the motor load torque; The operation of the motor is controlled by taking the initial current as a current control target of the motor.

2. The electric starting control method according to claim 1, characterized in that: During the entire transition process, the value of the initial current is updated at a set interval as the operating condition parameters change.

3. The electric starting control method according to claim 2, characterized in that: The interval time is 1s to 5s.

4. The electric starting control method according to claim 1, characterized in that: The operating condition parameters include the control voltage, control current, and motor speed of the motor.

5. The electric starting control method according to claim 4, characterized in that: The motor is controlled by a DQ coordinate system, the control voltage includes a D-axis control voltage and a Q-axis control voltage, and the control current includes a D-axis feedback current and a Q-axis feedback current.

6. The electric starting control method according to claim 4, characterized in that: The estimating the motor load torque based on the current operating condition parameters of the motor includes: Obtaining the current control voltage, the control current, and the motor speed; The current power of the motor is calculated from the control voltage and the control current, and the motor load torque is calculated based on the following formula: Motor load torque = current power ÷ motor speed.

7. The electric starting control method according to any one of claims 1 to 6, characterized in that: Determining the initial current of the sensorless closed-loop control includes: Establishing a corresponding function or comparison table between the initial current and the motor load torque; The initial current is determined based on the estimated motor load torque by calculating through the corresponding function or by looking up through the comparison table.

8. A motor controller, characterized in that: The method comprises a processor and a memory, wherein at least one computer program is stored in the memory, and the computer program is loaded and executed by the processor to implement the electric starting control method according to any one of claims 1 to 7.

9. The motor controller according to claim 8, characterized in that: The operating condition parameters include the control voltage, control current, and motor speed of the motor; The control voltage adopts the output voltage of the motor controller, and / or the control current adopts the output current of the motor controller, and / or the motor speed is estimated and acquired by a software observer.

10. An electric compressor, characterized in that: The electric compressor is provided with the motor controller according to claim 8 or 9.

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