A compressor control method based on load torque dynamic compensation

Abstract

The application discloses a compressor control method based on load torque dynamic compensation, comprising the following steps: (1) collecting motor current to calculate electromagnetic torque; (2) using electromagnetic torque, load torque estimated value and motor mechanical constant to estimate motor speed; (3) using motor speed estimated value and motor speed actual value to estimate load torque; (4) compensating compressor torque current through load torque estimated value. The application integrates speed self-adaptive estimation and load torque estimation, automatically tunes frequency component of disturbance load, can accurately estimate load torque fluctuation, and implements compensation on load torque, thereby effectively inhibiting vibration of the compressor system. The application is suitable for compressor torque compensation in a sensorless working mode, does not need to test load torque change characteristic curve, and can still work well after the compressor or load changes, has clear physical meaning and is easy to realize, and has certain universality and high engineering application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the drive control of a compressor, in particular to a compressor control method based on dynamic compensation of load torque. BACKGROUND

[0002] Permanent magnet synchronous motor has high working efficiency, high power density, high operating efficiency, excellent control performance and other characteristics, and is widely used in household appliances, automobiles and other fields. In air conditioner compressor application, the load torque is usually fluctuating in a mechanical rotation cycle. The real-time change of the load torque will cause the fluctuation of the compressor speed. This periodic mechanical jitter will significantly increase the noise of the air conditioner compressor system, affect the user experience, and the continuous vibration of the system will also endanger the safety of the equipment. Therefore, a torque compensation algorithm is very needed in this application to compensate for the load torque, so as to reduce the vibration and noise of the equipment.

[0003] The existing compensation scheme generally uses the periodic change characteristics of the load torque to reconstruct the load torque using a sine function. In actual implementation, a set of compensation curves is usually built in, or the amplitude and phase of the sine function are adjusted online to find the optimal compensation effect. However, in fact, the load torque is not strictly sinusoidal, and if the load changes, the curve needs to be re-determined, which requires a large amount of design work. Finally, even if this type of compensation scheme can improve the compressor vibration to some extent, the compensation accuracy and vibration suppression effect are limited. Another type of compensation scheme estimates the load torque through the mechanical model of the compressor system combined with a digital filter, but since the frequency of the compressor operation is dynamically changing, and the mechanical jitter also contains rich harmonic vibration frequencies, the frequency processing of the digital filter becomes more difficult, often leading to very sensitive filter coefficients. In practical applications, the correlation coefficients need to be repeatedly tried and adjusted to stabilize the system, which lacks universality and robustness.

[0004] Therefore, it is urgent to solve the above problems. SUMMARY

[0005] The present application provides a compressor control method based on dynamic compensation of load torque, which can accurately compensate for alternating load torque, thereby significantly improving the vibration phenomenon of the system.

[0006] Technical scheme: In order to achieve the above purpose, the present application discloses a compressor control method based on dynamic compensation of load torque, comprising the following steps:

[0007] (1) Real-time acquisition of motor current, calculation of electromagnetic torque;

[0008] (2), using electromagnetic torque, load torque estimated value and motor mechanical constant estimated motor speed, obtain motor speed estimated value;

[0009] (3), using motor speed estimated value and motor speed actual value, estimate load torque estimate value;

[0010] (4), based on load torque estimated value, calculate torque current compensation value, realize the compensation of compressor torque current.

[0011] Further, in step (1), the calculation method of electromagnetic torque is as follows:

[0012]

[0013] Wherein, Te is electromagnetic torque, λ f is rotor flux, id is excitation current, iq is torque current, Ld is direct axis inductance, Lq is cross axis inductance.

[0014] Further, step (2) includes the following contents:

[0015] The relationship between electromagnetic torque, load torque estimated value, motor mechanical constant and motor speed estimated value is constructed:

[0016]

[0017] Wherein, Tl is load torque estimated value, J is the moment of inertia of compressor system, B is friction coefficient, is the motor speed estimated value;

[0018] The motor speed estimated value is obtained

[0019]

[0020] Wherein, s is the differential operator.

[0021] Further, in step (3), the motor speed estimated value and motor speed actual value are input into the load torque estimation model, and the load torque estimate value is obtained;

[0022] The load torque estimation model comprises a first subtracter, a second subtracter, a third subtracter, a first proportional amplifier, a second proportional amplifier, a third proportional amplifier, a first multiplier, a second multiplier, a first integrator, a second integrator, a third integrator and a first adder;

[0023] The motor speed estimation value is input to the positive input end of the first subtractor, and the motor speed actual value is input to the negative input end of the first subtractor, the first input end of the first multiplier, and the first input end of the second multiplier, respectively; the output end of the first subtractor is connected to the input end of the first proportional amplifier, the second proportional amplifier, and the third integrator, respectively; the output end of the first proportional amplifier is connected to the first input end of the first adder; the output end of the third integrator is connected to the third input end of the first adder; the output end of the second proportional amplifier is connected to the positive input end of the second subtractor; the output end of the first integrator is connected to the negative input end of the second subtractor, the second input end of the second multiplier, and the second input end of the first adder, respectively; the output end of the second subtractor is connected to the input end of the third proportional amplifier, and the output end of the third proportional amplifier is connected to the positive input end of the third subtractor; the output end of the second multiplier is connected to the input end of the second integrator, and the output end of the second integrator is connected to the negative input end of the third subtractor; the output end of the third subtractor is connected to the second input end of the first multiplier, and the output end of the first multiplier is connected to the input end of the first integrator.

[0024] The motor speed estimation value The first speed error value is obtained by subtracting the motor speed actual value from the motor speed estimation value through the first subtractor; the first proportional output is calculated by the first proportional amplifier based on the first speed error value; the second proportional output is calculated by the second proportional amplifier based on the first speed error value; the second subtractor output is obtained by subtracting the second proportional output from the first integral output through the second subtractor; the third proportional output is calculated by the third proportional amplifier based on the second subtractor output; the third subtractor output is obtained by subtracting the third proportional output from the second integral output through the third subtractor; the first multiplier output is obtained by multiplying the third subtractor output by the motor speed actual value through the first multiplier; the first integrator output is obtained by accumulating the first multiplier output through the first integrator; the second multiplier output is obtained by multiplying the first integrator output by the motor speed actual value through the second multiplier; the second integral output is obtained by accumulating the second multiplier output through the second integrator; the third integral output is calculated by the third integrator based on the first speed error value; and the sum of the first proportional output, the first integral output, and the third integral output is the load torque estimation value.

[0025] Further, in step (4), the torque current compensation value is calculated as follows:

[0026]

[0027] Wherein, Tl is the load torque estimation value, i q_comp is the torque current compensation value.

[0028] In the compressor application, due to the real-time change of the load torque, the compressor speed fluctuation is caused, so as to aggravate the vibration of the compressor and the corresponding pipeline, which not only increases the noise but also may endanger the equipment safety.

[0029] Beneficial effects: compared with the prior art, the present application has the following remarkable advantages:

[0030] 1、The present application integrates speed self-adaptive estimation and load torque estimation, automatically tunes the frequency component of the disturbance load, realizes accurate estimation of the alternating load torque of the compressor, and implements compensation for the load torque, so as to effectively suppress the vibration of the compressor system;

[0031] 2、The present application is suitable for the torque compensation of the compressor in the sensorless working mode, does not need to test the load torque change characteristic curve, can still work well after the change of the compressor or the load, has clear physical meaning and is easy to realize, has certain universality and high engineering application value. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a control principle diagram of the present application;

[0033] Figure 2 It is a schematic diagram of electromagnetic torque calculation;

[0034] Figure 3 It is a motor speed estimation principle diagram;

[0035] Figure 4 It is a load torque estimation model structure diagram. DETAILED DESCRIPTION

[0036] The technical scheme of the present application will be further described below in combination with the drawings and embodiments.

[0037] As shown in the drawings, Figures 1-4 The present application is a compressor control method based on load torque dynamic compensation, which comprises the following steps:

[0038] Step one, real-time acquisition of motor current, calculation of electromagnetic torque.

[0039] The electromagnetic torque is calculated by the following formula:

[0040]

[0041] Wherein, Te is the electromagnetic torque, λ f is the rotor flux, id is the excitation current, iq is the torque current, Ld is the direct-axis inductance, and Lq is the quadrature-axis inductance.

[0042] The conventional sensorless vector control needs to acquire motor phase currents ia, ib and ic, and observe the rotor field angle θ and speed ω, and the excitation current id and torque current iq calculation method is:

[0043]

[0044]

[0045] Step two, using the electromagnetic torque, load torque estimate value and motor mechanical constant to estimate the motor speed, obtain the motor speed estimate value.

[0046] First, the electromagnetic torque, load torque estimate value, motor mechanical constant and motor speed estimate value have the following relationship:

[0047]

[0048] Wherein, Tl is the load torque estimate value, J is the compressor system moment of inertia, B is the friction coefficient, The motor speed estimate value.

[0049] According to the above relationship, the motor speed estimate value is calculated:

[0050]

[0051] Wherein, s is the differential operator.

[0052] Step three, using the motor speed estimate value and the actual motor speed value, the load torque estimate value is calculated.

[0053] Specifically, a load torque estimation model is constructed, the motor speed estimate value and the actual motor speed value are input into the load torque estimation model, and the load torque estimate value is calculated.

[0054] The load torque estimation model includes a first subtracter, a second subtracter, a third subtracter, a first proportional amplifier, a second proportional amplifier, a third proportional amplifier, a first multiplier, a second multiplier, a first integrator, a second integrator, a third integrator and a first adder.

[0055] The motor speed estimate value is input into the positive input end of the first subtracter, and the actual motor speed value is input into the reverse input end of the first subtracter, the first input end of the first multiplier and the first input end of the second multiplier.

[0056] The output end of the first subtracter is connected to the input end of the first proportional amplifier, the second proportional amplifier and the third integrator.

[0057] The output end of the first proportional amplifier is connected to the first input end of the first adder. The output end of the third integrator is connected to the third input end of the first adder.

[0058] The output end of the second proportional amplifier is connected with the positive input end of the second subtractor; the output end of the first integrator is connected with the negative input end of the second subtractor, the second input end of the second multiplier and the second input end of the first adder respectively.

[0059] The output end of the second subtractor is connected with the input end of the third proportional amplifier, and the output end of the third proportional amplifier is connected with the positive input end of the third subtractor; the output end of the second multiplier is connected with the input end of the second integrator, and the output end of the second integrator is connected with the negative input end of the third subtractor.

[0060] The output end of the third subtractor is connected with the second input end of the first multiplier, and the output end of the first multiplier is connected with the input end of the first integrator.

[0061] The motor speed estimation value and the motor speed actual value are calculated by the first subtractor to obtain a first speed error value; the first speed error value is calculated by the first proportional amplifier to obtain a first proportional output; the first speed error value is calculated by the second proportional amplifier to obtain a second proportional output; the second proportional output and the first integral output are subtracted by the second subtractor to obtain a second subtraction output; the second subtraction output is calculated by the third proportional amplifier to obtain a third proportional output; the third proportional output and the second integral output are subtracted by the third subtractor to obtain a third subtraction output; the third subtraction output and the motor speed actual value are multiplied by the first multiplier to obtain a first multiplier output; the first multiplier output is accumulated by the first integrator to obtain a first integrator output; the first integrator output and the motor speed actual value are multiplied by the second multiplier to obtain a second multiplier output; the second multiplier output is accumulated by the second integrator to obtain a second integral output; the first speed error value is calculated by the third integrator to obtain a third integral output; the first proportional output, the first integral output and the third integral output are added by the first adder, and the sum is taken as the load torque estimation value.

[0062] Step four, based on the load torque estimation value, a torque current compensation value is calculated to realize compensation of the compressor torque current.

[0063] The conventional compressor sensorless control technology usually adopts vector control, and the reference value of the torque current is given by a speed regulator; due to the fluctuation of the compressor load, the motor speed fluctuates, and then the reference value of the torque current fluctuates; by introducing the load torque, the coupling of the loop can be eliminated.

[0064] The torque current compensation value of the application is calculated by the load torque estimation value, superimposed on the torque current reference value, and the torque current compensation value is calculated by the load torque estimation value.

[0065]

[0066] The calculation method of the torque current compensation value is as follows:

[0067] wherein Tl is the load torque, i q_comp is the torque current compensation value.

Claims

1. A compressor control method based on dynamic load torque compensation, characterized in that, Includes the following steps: (1) Real-time acquisition of motor current and calculation of electromagnetic torque; (2) Estimate the motor speed by using electromagnetic torque, feedback load torque estimate and motor mechanical constant; (3) Input the estimated value of motor speed and the actual value of motor speed into the load torque estimation model, calculate the estimated value of load torque and feed it forward to step (2); the load torque estimation model includes a first subtractor, a second subtractor, a third subtractor, a first proportional amplifier, a second proportional amplifier, a third proportional amplifier, a first multiplier, a second multiplier, a first integrator, a second integrator, a third integrator and a first adder; The estimated motor speed and the actual motor speed are subtracted by the first subtractor to obtain the first speed error value; The first speed error value is used to calculate the first proportional output through the first proportional amplifier; The first speed error value is used to calculate the second proportional output through the second proportional amplifier; the second proportional output and the first integral output are subtracted by the second subtractor to obtain the second subtracted output; the second subtracted output is used to calculate the third proportional output through the third proportional amplifier; the third proportional output and the second integral output are subtracted by the third subtractor to obtain the third subtracted output; the third subtracted output is multiplied by the actual motor speed value by the first multiplier to obtain the first multiplier output; the first multiplier output is accumulated by the first integrator to obtain the first integrator output; the first integrator output is multiplied by the actual motor speed value by the second multiplier to obtain the second multiplier output; the second multiplier output is accumulated by the second integrator to obtain the second integral output; the first speed error value is used to calculate the third integral output through the third integrator; the first proportional output, the first integral output, and the third integral output are added by the first adder, and their sum is used as the estimated load torque value. (4) The torque current compensation value is calculated based on the load torque estimation value to achieve compensation for the compressor torque current.

2. The compressor control method based on dynamic load torque compensation according to claim 1, characterized in that, In step (1), the electromagnetic torque is calculated as follows: Where Te is the electromagnetic torque, λ f Ld is the rotor flux linkage, id is the excitation current, iq is the torque current, Ld is the direct-axis inductance, and Lq is the quadrature-axis inductance.

3. The compressor control method based on dynamic load torque compensation according to claim 2, characterized in that, Step (2) includes the following: Construct the relationships between the estimated electromagnetic torque, load torque, motor mechanical constants, and motor speed: Where Tl is the estimated load torque, J is the compressor system moment of inertia, and B is the coefficient of friction. This is an estimated value for the motor speed; Obtain the estimated motor speed. Where s is the differential operator.

4. The compressor control method based on dynamic load torque compensation according to claim 3, characterized in that, In step (3), the estimated motor speed is input to the positive input of the first subtractor, and the actual motor speed is input to the negative input of the first subtractor, the first input of the first multiplier, and the first input of the second multiplier. The output of the first subtractor is connected to the inputs of the first proportional amplifier, the second proportional amplifier, and the third integrator. The output of the first proportional amplifier is connected to the first input of the first adder. The output of the third integrator is connected to the third input of the first adder. The output of the second proportional amplifier is connected to the positive input of the second subtractor. The output of the first integrator is connected to the negative input of the second subtractor, the second input of the second multiplier, and the second input of the first adder. The output of the second subtractor is connected to the input of the third proportional amplifier, and the output of the third proportional amplifier is connected to the positive input of the third subtractor. The output of the second multiplier is connected to the input of the second integrator, and the output of the second integrator is connected to the negative input of the third subtractor. The output of the third subtractor is connected to the second input of the first multiplier, and the output of the first multiplier is connected to the input of the first integrator.

5. The compressor control method based on dynamic load torque compensation according to claim 4, characterized in that, In step (4), the calculation method for the torque current compensation value is as follows: Where Tl is the estimated load torque, i q_comp This is the torque current compensation value.

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