Self-adaptive dead zone compensation strategy for vector control of mining permanent magnet driving motor

Abstract

The invention belongs to the technical field of coal mine intelligent driving control, and provides a self-adaptive dead zone compensation strategy for vector control of a mining permanent magnet driving motor in order to solve the problem that current polarity needs to be detected when dead zone compensation is carried out at present. The method comprises the following steps: sampling three-phase stator current, sequentially carrying out Clark transformation and Park transformation on the sampled three-phase stator current to obtain quadrature-direct axis current under a d-q axis synchronous rotating coordinate system, then establishing a disturbance voltage online observer according to flux linkage increment operation, and when the disturbance voltage is judged to be dead-zone disturbance voltage, carrying out adaptive dead-zone compensation on the dead-zone disturbance voltage to obtain the disturbance voltage online observer. According to the mining driving motor control method, accurate detection of the current polarity is avoided, the reliability of the control system is improved, further, the optimal voltage vector is selected through the constructed evaluation function, and the motor is controlled after SVPWM modulation, so that the control of the mining driving motor is more accurate.

Description

Technical Field

[0001] The invention belongs to the technical field of intelligent drive control for coal mines, and in particular relates to an adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mines. Background Art

[0002] Mining battery powered vehicles are widely and deeply used in mines, playing an important role in improving transportation efficiency, ensuring safe production, and promoting green mine construction. Mining permanent magnet drive motors have become the first choice for mining battery powered vehicle motors due to their simple structure, small size, and high power density. The inverter circuit with power switching devices as the core is responsible for driving the mining permanent magnet drive motor, and uses PWM modulation technology to control the power switching devices. In order to ensure the safety of the inverter and avoid the short circuit caused by the simultaneous conduction of the upper and lower switches of the same bridge arm of the inverter, a certain dead time needs to be set in the control signal of the upper and lower bridge arms of PWM. However, due to the addition of dead time, the phase current will be distorted, the harmonic content will increase, and the torque will pulsate, which is not conducive to the high-quality control of the motor. Therefore, in order to suppress the impact of the addition of dead time and improve the control performance of the motor system, it is necessary to compensate for the dead time effect of the inverter.

[0003] At present, the dead zone compensation algorithm of permanent magnet drive motor for mining mainly eliminates the influence of dead zone based on the polarity of current and the magnitude of error voltage generated. However, the detection of current polarity is difficult. Once the judgment is wrong, not only can the system not be compensated, but it may cause worse effects. In addition, the disturbance voltage generated by the dead zone effect is difficult to estimate. Therefore, in view of the above problems, it is necessary to design an algorithm that does not need to detect the current polarity, can observe the disturbance voltage online and accurately compensate for the dead zone effect. Summary of the invention

[0004] In order to solve at least one of the above technical problems existing in the prior art, the present invention provides an adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining.

[0005] The present invention is implemented by the following technical solution: an adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining, comprising the following steps:

[0006] S1: collect the three-phase stator current of the permanent magnet drive motor for mining in real time, and obtain the AC and DC axis current after coordinate transformation;

[0007] S2: establishing a disturbance voltage online observer, and judging whether the disturbance voltage is a dead zone disturbance voltage based on the disturbance voltage online observer. When the disturbance voltage is a dead zone disturbance voltage, executing step S3, otherwise the disturbance voltage online observer continuously observes the dead zone error voltage caused by the disturbance voltage;

[0008] S3: Establishing an adaptive dead zone compensation algorithm to perform voltage compensation according to the dead zone error voltage.

[0009] Preferably, step S1 further includes:

[0010] Obtain the three-phase stator current and the mechanical angular frequency of the permanent magnet drive motor for mining in the natural coordinate system;

[0011] Performing Clarke transformation based on the three-phase stator current in the natural coordinate system to obtain current data in a stationary coordinate system;

[0012] Obtaining a rotor position signal based on the mechanical angular frequency of the mining permanent magnet drive motor;

[0013] Park transformation is performed based on the current data in the stationary coordinate system and the rotor position signal to obtain the AC and DC axis currents.

[0014] Preferably, in step S2, establishing an online disturbance voltage observer includes:

[0015] Given the ideal AC and DC axis voltages corresponding to the AC and DC axis currents;

[0016] Based on the AC and DC axis currents and the corresponding AC and DC axis ideal voltages, obtaining a change in induced electromotive force within a current acquisition cycle;

[0017] Based on the variation of the AC and DC axis currents, obtaining a rotor flux increment within a current acquisition cycle;

[0018] A disturbance voltage online observer is established based on the AC and DC axis currents, the induced electromotive force variation and the rotor flux increment.

[0019] Preferably, in step S3, an adaptive dead zone compensation algorithm is established, including:

[0020] Acquire the AC and DC axis current feedback value of Park transformation, and establish a dead zone error voltage expression based on the AC and DC axis current feedback value;

[0021] Discretizing the dead zone error voltage expression to obtain a discretized dead zone error voltage expression;

[0022] Set the AC and DC axis compensation current values ​​and establish the dead zone compensation formula;

[0023] An adaptive dead zone compensation algorithm is established based on the discretized dead zone error voltage expression and the dead zone compensation formula.

[0024] Preferably, the discretized dead zone error voltage expression is:

[0025]

[0026] In the formula, R s is the stator phase resistance, i d (k) and i q (k) is the preset reference value of the current in the kth cycle, i d_s (k) and i q_s (k) is the actual sampling value of the dead zone current in the kth cycle, T is the sampling frequency of the stator three-phase current of the permanent magnet drive motor for mining, L d is the d-axis stator inductance, L q is the q-axis stator inductance.

[0027] Preferably, the dead zone compensation formula in step S3 is:

[0028] u(k)=G -1 [x * (k+1)-F(k)·x(k)-H(k)]+u dq_dead (k)

[0029] In the formula, G -1 is the inverse matrix of the switching cycle and motor parameters, x * is the current state variable, F(k) is the relationship between the motor speed and the switching period in the kth cycle, H(k) is the relationship between the motor speed and the motor parameters in the kth cycle, u dq_dead (k) is the set of dead zone AC and DC axis error voltages in the kth current acquisition cycle.

[0030] Preferably, after performing voltage compensation according to the dead zone disturbance voltage in step S3, the method further includes:

[0031] Obtain the basic voltage vector and construct the evaluation function;

[0032] The basic voltage vector and the dead zone error voltage are brought into the evaluation function, the optimal voltage vector is selected, and the permanent magnet drive motor for mining is controlled to rotate according to the selection result.

[0033] Preferably, the evaluation function is:

[0034]

[0035] In the formula, u d (k) and u q (k) is the basic voltage vector, m is the adjustment coefficient, u d_dead (k) is the d-axis dead zone voltage of the kth current acquisition cycle, u q_dead (k) is the q-axis dead zone voltage of the kth current acquisition cycle.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] There is no need to detect the current polarity, and the disturbance voltage can be observed online and the dead zone effect can be accurately compensated, which avoids the need for accurate detection of the current polarity and improves the reliability of the control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 It is a schematic flow chart of an adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining according to the present invention;

[0040] Figure 2 The invention relates to a vector control model of a permanent magnet drive motor for mining, which is about an adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining;

[0041] Figure 3 It is a three-phase stator current waveform diagram output by the mining permanent magnet drive motor vector control system without adding the dead zone compensation algorithm of the present invention;

[0042] Figure 4 It is a three-phase stator current waveform diagram output by the mining permanent magnet drive motor vector control system to which the dead zone compensation algorithm is added in the present invention. DETAILED DESCRIPTION

[0043] In conjunction with the drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0044] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention. It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0045] Pulse Width Modulation (PWM) voltage source inverters are widely used in the field of motor drive control. In practical applications, a certain dead time is set in the control signal of the upper and lower bridge arms of PWM. However, due to the addition of dead time, the phase current will be distorted, the harmonic content will increase, and the torque will pulsate. Therefore, in order to solve the above problems and improve the control performance at the same time, this application provides an adaptive dead zone compensation strategy for vector control of permanent magnet drive motors for mining, which does not require current polarity detection, can observe the disturbance voltage online and accurately compensate for the dead zone effect.

[0046] like Figure 1 As shown, it is an adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining provided by an embodiment of the present application. The adaptive dead zone compensation strategy can be applied to the motor driver of the permanent magnet drive motor for mining and improve the control accuracy of the motor driver. Specifically, it includes the following steps:

[0047] S1: collect the three-phase stator current of the permanent magnet drive motor for mining in real time and process it to obtain the AC and DC axis current.

[0048] Optionally, step S1 also includes: acquiring the three-phase stator current and the mechanical angular frequency of the permanent magnet drive motor for mining in a natural coordinate system; performing Clarke transformation based on the three-phase stator current in the natural coordinate system to obtain current data in a stationary coordinate system; obtaining a rotor position signal based on the mechanical angular frequency of the permanent magnet drive motor for mining; performing Park transformation based on the current data in the stationary coordinate system and the rotor position signal to obtain AC and DC axis currents.

[0049] In this embodiment, the mechanical angular frequency of the permanent magnet drive motor for mining is obtained in real time through the speed detection sensor, and the mechanical angular frequency is derived to obtain the rotor position signal of the permanent magnet drive motor for mining. At the same time, the three-phase stator current i of the permanent magnet drive motor for mining is collected in real time through the current collection device. a 、i b 、i c , and then the three-phase stator current i a 、i b 、i c Perform Clarke Transformation to obtain the current data i in the α-β stationary coordinate system α 、i β , and then according to the rotor position signal and the current data i in the stationary coordinate system α 、i β Perform Park's Transformation to obtain the direct and quadrature axis current i in the synchronous rotating coordinate system. d 、i q .

[0050] S2: Establish a disturbance voltage online observer, and determine whether the disturbance voltage is a dead zone disturbance voltage based on the disturbance voltage online observer. When the disturbance voltage is a dead zone disturbance voltage, execute step S3, otherwise the disturbance voltage online observer continues to observe the dead zone error voltage caused by the disturbance voltage.

[0051] Optionally, an ideal AC-DC axis voltage corresponding to an AC-DC axis current is given; based on the AC-DC axis current and the corresponding ideal AC-DC axis voltage, a change in induced electromotive force within a current acquisition cycle is obtained; based on the change in the AC-DC axis current, a rotor flux increment within a current acquisition cycle is obtained; and a disturbance voltage online observer is established based on the AC-DC axis current, the change in induced electromotive force and the rotor flux increment.

[0052] In this embodiment, the expression of the variation of the induced electromotive force in one current sampling period is:

[0053]

[0054] Where, T is the sampling frequency of the stator three-phase current of the permanent magnet drive motor for mining, L d is the d-axis stator inductance, L q is the q-axis stator inductance, Δi d is the d-axis current change, Δi q is the q-axis current change, R s is the stator phase resistance, is the ideal voltage on the d-axis, is the ideal voltage on the q axis.

[0055] In this embodiment, the rotor flux increment Δψ m The expression is:

[0056]

[0057] In the formula, θ e is the rotor position signal.

[0058] Combining the ideal voltage expression of the AC and DC axes and the expression of the variation of the induced electromotive force, the expression of the disturbance voltage online observer can be obtained as follows:

[0059]

[0060] In the formula, ω e is the electromagnetic speed of the motor.

[0061] S3: Establishing an adaptive dead zone compensation algorithm to perform voltage compensation according to the dead zone error voltage.

[0062] Optionally, an adaptive dead zone compensation algorithm is established, including: obtaining the AC and DC axis current feedback values ​​of the Park transform, and establishing a dead zone error voltage expression based on the AC and DC axis current feedback values; discretizing the dead zone error voltage expression to obtain a discretized dead zone error voltage expression; setting the AC and DC axis compensation current values, and establishing a dead zone compensation formula; and establishing an adaptive dead zone compensation algorithm based on the discretized dead zone error voltage expression and the dead zone compensation formula.

[0063] In this embodiment, the dead zone error voltage expression is:

[0064]

[0065] In the formula, p is the pole pair number, i is d_s with i q_s They are respectively the AC and DC axis current feedback values ​​transformed from the three-phase sampling current of the motor stator to the synchronous rotating coordinate system.

[0066] In this embodiment, assuming that the set of AC and DC axis compensation current values ​​is x(k), the dead zone compensation formula for the kth current sampling period is:

[0067] u(k)=G -1 [x * (k+1)-F(k)·x(k)-H(k)]+u dq_dead (k)

[0068] In the formula, G -1 is the inverse matrix of the switching cycle and motor parameters, x * is the current state variable, k+1 is the next moment, F(k) is the relationship between the motor speed and the switching period at moment k, H(k) is the relationship between the motor speed and the motor parameters at moment k, u dq_dead (k) is the set of AC and DC axis error voltages in the dead zone of the kth current acquisition cycle, that is, Process the data to get u dq_dead (k).

[0069] in,

[0070] In this embodiment, the compensation voltage calculated by the dead zone compensation formula is added to the dead zone error expression to generate a pulse width modulated command voltage to compensate the system in real time.

[0071] Optionally, the dead-zone error voltage expression is discretized to obtain a discretized dead-zone error voltage expression.

[0072] In this embodiment, in actual motor control, the entire system must be discretized, so the dead zone error voltage expression after discretization is:

[0073]

[0074] In the formula, i d (k) and i q (k) is the preset reference value of the current in the kth cycle, i d_s (k) and i q_s (k) is the actual sampling value of the dead zone current in the kth cycle.

[0075] Optionally, after performing voltage compensation according to the dead zone disturbance voltage, it also includes: obtaining a basic voltage vector and constructing an evaluation function; bringing the basic voltage vector and the dead zone error voltage into the evaluation function, selecting the optimal voltage vector, and controlling the rotation of the mining permanent magnet drive motor according to the selection result.

[0076] Optionally, the evaluation function is:

[0077]

[0078] In the formula, u d (k) and u q (k) are the basic voltage vectors of the d-axis and q-axis, m is the adjustment coefficient, u d_dead (k) is the d-axis dead zone voltage of the kth current acquisition cycle, u q_dead (k) is the q-axis dead zone voltage of the kth current acquisition cycle.

[0079] In an embodiment of the present application, the three-phase stator current and DC bus voltage of the permanent magnet drive motor for mining are sampled in real time, and the sampled three-phase stator current is subjected to Clarke transformation and Park transformation in sequence to obtain the AC and DC axis currents in the dq axis synchronous rotating coordinate system, and then a disturbance voltage online observer is established based on the flux increment calculation. When the disturbance voltage is judged to be a dead zone disturbance voltage, the dead zone disturbance voltage is adaptively compensated for, thereby avoiding the need for accurate detection of the current polarity and improving the reliability of the control system. Furthermore, the optimal voltage vector is selected through the constructed evaluation function, and the motor is controlled after SVPWM modulation, so that the control of the mining drive motor is more precise.

[0080] To further verify the effectiveness of the embodiments of the present application, the present application is constructed as follows Figure 2 The vector control simulation model of the mining permanent magnet drive motor shown is used for simulation analysis and verification.

[0081] This application embodiment constructs a vector control model of a permanent magnet drive motor for mining. Figure 2As shown in the figure, it mainly includes a current controller, an SVPWM modulation algorithm module, and a dead zone compensation algorithm module. The model first controls the three-phase current of the permanent magnet synchronous current motor stator through the current controller to collect current data through the current sensor. At the same time, the rotary transformer transmits the rotor position angle to the signal input end in real time. After Clarke transformation and Park transformation, the current value in the three-phase rotating coordinate system is converted to the two-phase stationary coordinate system. After passing through the PI controller, the voltage control signal is input into the SVPWM modulation algorithm module; the voltage is compensated by the dead zone compensation algorithm module, and the obtained control signal is integrated with the signal obtained by the SVPWM modulation algorithm module and input into the inverter to obtain the i as, i bs and i cs waveforms, so that the error voltage compensation effect of the permanent magnet drive motor for mining can be judged by the waveform. The specific parameters of the model are shown in Table 1.

[0082] Table 1

[0083] Motor parameters Numeric unit Pole pairs 23 - Stator phase resistance 0.01 Ω Stator phase inductance 7e-6 H Moment of Inertia 0.0014 <![CDATA[kg·m 2 ]]> Permanent magnet flux amplitude 0.0036 Wb Rated speed 700 rpm DC bus voltage 100 V

[0084] like Figure 3 As shown in the figure, the stator current waveform output by the motor control system without adding the dead zone compensation algorithm is obviously distorted, the harmonic content is high, and the zero current clamping effect is obvious.

[0085] like Figure 4 As shown in the figure, after adding the dead zone compensation algorithm, the sinusoidality of the three-phase current is significantly improved and the zero current clamping phenomenon is significantly improved.

[0086] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An adaptive dead zone compensation strategy for vector control of permanent magnet drive motor for mining, characterized in that: The steps include: S1: collect the three-phase stator current of the permanent magnet drive motor for mining in real time, and obtain the AC and DC axis current after coordinate transformation; S2: establishing a disturbance voltage online observer, and judging whether the disturbance voltage is a dead zone disturbance voltage based on the disturbance voltage online observer. When the disturbance voltage is a dead zone disturbance voltage, executing step S3, otherwise the disturbance voltage online observer continuously observes the dead zone error voltage caused by the disturbance voltage; S3: Establishing an adaptive dead zone compensation algorithm to perform voltage compensation according to the dead zone error voltage.

2. The adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining according to claim 1 is characterized in that: Step S1 also includes: Obtain the three-phase stator current and the mechanical angular frequency of the permanent magnet drive motor for mining in the natural coordinate system; Performing Clarke transformation based on the three-phase stator current in the natural coordinate system to obtain current data in a stationary coordinate system; Obtaining a rotor position signal based on the mechanical angular frequency of the mining permanent magnet drive motor; Park transformation is performed based on the current data in the stationary coordinate system and the rotor position signal to obtain the AC and DC axis currents.

3. The adaptive dead zone compensation strategy for vector control of permanent magnet drive motor for mining according to claim 1 is characterized in that: In step S2, a disturbance voltage online observer is established, including: Given the ideal AC and DC axis voltages corresponding to the AC and DC axis currents; Based on the AC and DC axis currents and the corresponding AC and DC axis ideal voltages, obtaining a change in induced electromotive force within a current acquisition cycle; Based on the variation of the AC and DC axis currents, obtaining a rotor flux increment within a current acquisition cycle; A disturbance voltage online observer is established based on the AC and DC axis currents, the induced electromotive force variation and the rotor flux increment.

4. The adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining according to claim 1 is characterized in that: In step S3, an adaptive dead zone compensation algorithm is established, including: Acquire the AC and DC axis current feedback value of Park transformation, and establish a dead zone error voltage expression based on the AC and DC axis current feedback value; Discretizing the dead zone error voltage expression to obtain a discretized dead zone error voltage expression; Set the AC and DC axis compensation current values ​​and establish the dead zone compensation formula; An adaptive dead zone compensation algorithm is established based on the discretized dead zone error voltage expression and the dead zone compensation formula.

5. The adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining according to claim 4 is characterized in that: The discretized dead zone error voltage expression is: In the formula, R s is the stator phase resistance, i d (k) and i q (k) is the preset reference value of the current in the kth cycle, i d_s (k) and i q_s (k) is the actual sampling value of the dead zone current in the kth cycle, T is the sampling frequency of the stator three-phase current of the permanent magnet drive motor for mining, L d is the d-axis stator inductance, L q is the q-axis stator inductance.

6. The adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining according to claim 4 is characterized in that: The dead zone compensation formula in step S3 is: u(k)=G -1 [x * (k+1)-F(k)·x(k)-H(k)]+u dq_dead (k) In the formula, G -1 is the inverse matrix of the switching cycle and motor parameters, x * is the current state variable, F(k) is the relationship between the motor speed and the switching period in the kth cycle, H(k) is the relationship between the motor speed and the motor parameters in the kth cycle, u dq_dead (k) is the set of dead zone AC and DC axis error voltages in the kth current acquisition cycle.

7. The adaptive dead zone compensation strategy for vector control of a permanent magnet drive motor for mining according to claim 1 is characterized in that: After performing voltage compensation according to the dead zone disturbance voltage in step S3, the method further includes: Obtain the basic voltage vector and construct the evaluation function; The basic voltage vector and the dead zone error voltage are brought into the evaluation function, the optimal voltage vector is selected, and the permanent magnet drive motor for mining is controlled to rotate according to the selection result.

8. The adaptive dead zone compensation strategy for vector control of permanent magnet drive motor for mining according to claim 7 is characterized in that: The evaluation function is: In the formula, u d (k) and u q (k) is the basic voltage vector, m is the adjustment coefficient, u d_dead (k) is the d-axis dead zone voltage of the kth current acquisition cycle, u q_dead (k) is the q-axis dead zone voltage of the kth current acquisition cycle.

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