Method and apparatus for regulating an electric machine

Abstract

The invention relates to a method (100) for regulating an electric machine (204), which has a harmonic regulator (200), which comprises an input stage (210), a regulator (220) and an output stage (230), which method has the following steps: determining (110) at least two measured variables (id, iq); determining (120) a cosine measured component and a sine measured component (idcos_m, idsin_m, iqcos_m, iqsin_m); determining (130) a cosine control variable and a sine control variable (idcos_s, idsin_s, iqcos_s, iqsin_s); determining (140) at least two control variables (ud, uq); actuating (150) the electric machine (204) in dependence on the determined control variables (ud, uq).

Description

Technical Field

[0001] This invention relates to a method and apparatus for regulating an electric motor. The invention also relates to an electric drive system having corresponding apparatus, a heat pump having an electric drive system, a computer program, and a computer-readable storage medium. Background Technology

[0002] Publication DE102009000930A1 discloses a method and apparatus for reducing torque ripple in a permanent magnet motor system. The motor system includes a permanent magnet motor coupled to an inverter. The method described in this publication includes a step of modifying operating control signals to generate operating control signals with reduced ripple. These modified operating control signals are provided to the inverter to control the permanent magnet motor.

[0003] Due to design characteristics or in the event of a fault, an electric drive system consisting of a motor and power electronics does not exhibit a smooth torque variation process, but rather a torque variation process with harmonics. Similarly, radial force excitation occurs on the motor rotor. If the motor drives an uneven load, such as a compressor used in a heat pump, additional harmonic vibrations occur due to the rotor speed. These harmonic vibrations, the torque variation process, and the radial force excitation superimpose each other, causing housing vibration and thus acoustic radiation.

[0004] To reduce the mechanical load on the various components of the drive system, and also to reduce noise, these effects should be minimized. Therefore, the control of the motor is modified to generate a harmonic current that counteracts the interference.

[0005] Rotating field motors (such as squirrel-cage induction motors or permanent magnet synchronous motors) do not have an ideal sinusoidal flux distribution in the air gap due to their structure. During operation, this results in non-uniform torque with harmonics when regulated with sinusoidal current. In addition to the resulting torsional vibrations in the drivetrain, the aforementioned non-uniformity also leads to radial force excitation between the stator and rotor, which manifests directly as housing vibrations and thus as noise vibration and vibration (NVH). This problem is exacerbated by external oscillating load torques, such as those caused by compressors, as in heat pumps. Overall, the structural characteristics of electric drive systems can therefore sometimes cause undesirable, perceptible vibrations and / or acoustically discernible noise emissions in the drivetrain and electrical grid. It is known to regulate induction motors using field-oriented control (FOR). This regulation is essentially designed to regulate the fundamental frequency of the current, which is achieved by using a d / q transformation to convert the fundamental frequency into constant parameters id, iq in a co-rotating dq coordinate system. The constant parameters are then adjusted in the coordinate system, and the resulting control parameters du, uq are subsequently transformed back to the time domain and used as the fundamental frequency for controlling the voltage of the motor. It is impossible to influence or reduce harmonics in this way.

[0006] To minimize harmonics, two basic approaches are possible. The first possibility is to selectively compensate for external interference variables, which may lead to inadequate performance in actual operation due to operation-related (e.g., temperature-related) parameters or manufacturing-induced tolerances.

[0007] While alternative, feedback-based concepts are more robust to parameter deviations, they are only applicable to single-parameter systems (control parameter and measurement parameter) in known variations. However, in the case of field-oriented regulation in the d / q coordinate system, the induction motor has two independent control voltages u. d / u q And therefore it has two control parameters. Summary of the Invention

[0008] A method for regulating a motor is provided, the motor having a harmonic regulator, the harmonic regulator including an input stage, a regulator, and an output stage. The method includes the following steps:

[0009] Determine at least two measurement parameters;

[0010] Based on the detected measurement parameters, the cosine and sine measurement components of a predetermined frequency are obtained using the input stage.

[0011] Based on the cosine measurement component and the sine measurement component, the cosine control parameter and the sine control parameter are obtained using the regulator and the regulator's predetermined adjustment matrix.

[0012] Based on the obtained cosine and sine control parameters, at least two control parameters are obtained using the output stage.

[0013] The motor is controlled according to the obtained control parameters.

[0014] Field-oriented control is widely used for regulating motors, particularly permanent magnet excitation synchronous motors. Here, the alternating parameter (also called the fundamental frequency) of the phase current to be adjusted, preferably sinusoidal in the time domain, is mathematically transformed into a coordinate system rotating at the frequency of the alternating parameter. The frequency of the alternating parameter also determines the frequency of the magnetic field in the machine, so this coordinate system rotating at the frequency of the alternating parameter is also called a field-oriented system. During steady-state operation of the motor, constant parameters in the field-oriented system are derived from the alternating parameter in the time domain. These constant parameters can be adjusted using common methods of control techniques. The field-oriented system is also called a d / q coordinate system. Here, the d-axis of this d / q coordinate system points in the direction of the rotor flux. The q-axis is perpendicular to the d-axis. The sinusoidal phase current is represented as a stator current vector, characterized by its length and direction. This current vector rotates synchronously with the rotating stator or rotor flux of the motor. In the d / q coordinate system, the current vector can be represented by its length and direction using two mutually perpendicular components Id and Iq, which are constant parameters in steady state.

[0015] To regulate a motor that can be connected to or connected to a harmonic regulator, at least two measurement parameters of the motor are detected in the field-oriented system, preferably two components of the stator current vector in the field-oriented system. As described above, these measurement parameters include multiple harmonics or at least one harmonic, which is superimposed on the phase current through the motor. In the field-oriented system, the fundamental frequency is a constant parameter, while the harmonics are alternating parameters.

[0016] To regulate harmonics, similar to the transformation from the time domain to the field-oriented domain, a predetermined frequency component is obtained using an input stage. This predetermined frequency preferably corresponds to the frequency of a predetermined order of harmonics. Preferably, the predetermined order of the fundamental electric wave or fundamental frequency is mapped into the harmonic-oriented system via the input stage as cosine and sine measurement components, respectively, which are contained in the two components of the stator current vector in the field-oriented system. The corresponding cosine and sine measurement components are constant parameters. Parameters that are alternating parameters in the field-oriented system are constant parameters in the harmonic-oriented system during the steady-state operation of the motor. These parameters can be adjusted using tuning techniques. The predetermined frequency is preferably the nth order of the fundamental frequency of the phase current or fundamental electric wave, which provides a significant contribution to the mechanical vibration of the motor or drive system. Preferably, this is the 6th, 4th, 3rd, 2nd, and / or 1st order. Preferably, multiple, especially more than one or more than two, harmonic orders are considered simultaneously.

[0017] Here, the computational cost increases linearly with the number of orders.

[0018] Using a regulator and a predetermined regulation matrix, cosine and sine control parameters are obtained from cosine and sine measurement components. For this purpose, it is preferable to multiply the regulation matrix by a vector that depends on or originates from the cosine and sine measurement components. Preferably, the components of the regulation matrix are mapped to a model of the connected motor or electric drive system to obtain the cosine and sine control parameters. From these constant control parameters in the harmonic-oriented system, and from the cosine and sine control parameters, two control parameters are obtained via an output stage, preferably as phase voltage vectors, for further use in field-oriented regulation. In the field-oriented system, the control parameters include alternating parameters and harmonics. Finally, the method includes steps for controlling the motor based on the two control parameters. Controlling the motor preferably involves energizing a phase of the motor or applying a phase voltage to the motor windings, which is obtained by an inverse time-domain transformation from the phase voltage of the field-oriented system.

[0019] Advantageously, a method for an effective harmonic modulator is provided.

[0020] In the context of this application, the statement "a parameter of a regulating circuit includes a harmonic or fundamental frequency" means that a parameter of the regulating circuit characterizes or describes at least one harmonic or fundamental frequency. The corresponding parameter of the regulating circuit may also include other signal components, such as the fundamental frequency and one or more harmonics, and additionally includes any existing interference parameters.

[0021] In another embodiment of the invention, at least two measurement parameters characterize the current in the motor. These at least two measurement parameters are determined by measuring at least one phase current.

[0022] Advantageously, measurable parameters of the electric drive system are provided as input parameters to the harmonic regulator.

[0023] In another configuration of the invention, the detected measurement parameter is multiplied by a cosine and sine function of a predetermined frequency, preferably corresponding to the frequency of a predetermined harmonic order, via an input stage. The cosine and sine measurement components with the predetermined frequencies are obtained as the result of the multiplication. These cosine and sine measurement components here correspond to the cosine and sine components of the harmonic to be adjusted or minimized at the predetermined frequency of the measurement parameter. During multiplication, the current reference angle for the corresponding harmonic should be considered. This current reference angle is exemplarily determined by… It is found that the azimuth angle of the mechanical rotor is The number of pole pairs is N p The measured parameters are amplified by a scalar parameter ρ before being multiplied by the cosine and sine functions. The scalar parameter ρ represents a tuning parameter used to adjust the convergence rate for determining the harmonic order.

[0024] Advantageously, an efficient method for extracting the cosine and sine components of harmonics is provided.

[0025] In another configuration of the invention, by means of an adjuster, the difference between the corresponding cosine measurement component and the sine measurement component and the pre-given cosine target component and the sine target component is multiplied by a predetermined adjustment matrix to obtain the cosine control parameter and the sine control parameter.

[0026] Before multiplying with the adjustment matrix, the pre-defined cosine and sine target components are first subtracted from the corresponding cosine and sine measurement components. The resulting coefficient vector Θ c,y and Θ s,y The preferred combination is a complex vector Θ y =Θ s,y +jΘ c,y This leads to a simplified description of the subsequent operations. For a motor, for example, using two currents i as measurement parameters... d and i q get:

[0027]

[0028] Since the target value is subtracted from the measured value, harmonics can be adjusted or minimized using multiplication. Preferably, a target harmonic value is thus pre-defined, which results in a reduction or increase in current harmonics. Therefore, the drive system can be optimized in a targeted manner in terms of noise generation or control, or in terms of reducing mechanical load (extending service life).

[0029] When considering the steady-state transmission performance of the motor or (preferably) the transmission path of the electric drive system, the following applies: Θ y =G(jω) d )Θ u .

[0030] For harmonic modulators (HC), this scheme is preferred: G HC (jω d ) = G -1 (jω d This corresponds to the preferred static and / or multivariate inversion of the equations for the motor or transmission path. Harmonic frequencies are preferentially determined using the term ω. d =mω el =mN p ω mech Find the mechanical angular frequency ω. mech =2πf mech Or, the electric angular frequency is ω el =N p ω mech Preferably, for the motor:

[0031]

[0032] This complex representation of the inverse transfer function of the adjustment matrix can preferably be presented in real-valued form as a predetermined adjustment matrix, as follows:

[0033]

[0034] This real-valued representation is preferably used to obtain cosine control parameters and sine control parameters by means of a computing unit, where m describes the m-th order of the harmonic, R describes the ohmic resistance, ωel describes the fundamental frequency, Ld describes the inductance in the d direction, and Lq describes the inductance in the Q direction.

[0035] Here, the predetermined adjustment matrix is ​​multiplied by the difference between the corresponding cosine and sine measurement components and the pre-defined cosine and sine target components. Thus, the cosine and sine control parameters are obtained and pre-defined as parameters Θ. u The changes over time.

[0036] Advantageously, an efficient method is provided for obtaining cosine and sine control parameters.

[0037] In another configuration of the invention, the obtained cosine and sine control parameters are multiplied by a predetermined frequency cosine and sine function, respectively, using an output stage to obtain control parameters. The control parameters are obtained as the result of multiplication. Preferably, the obtained cosine and sine control parameters are integrated, preferably numerically, before multiplication. The resulting control parameters are then superimposed on the motor's voltage space vector for control.

[0038] Advantageously, an efficient method for obtaining control parameters is provided.

[0039] In another configuration of the invention, the method steps are implemented based on the current rotor angle of the motor. For this purpose, the rotor angle is determined based on the detected measurement parameters. The rotor angle of the motor is required for motor adjustment. If no rotor angle measurement is set, the rotor angle (preferably also the rotational speed) is determined from the currently determined physical parameters, preferably the measurement parameters. Preferably, a PLL (Phase-locked loop), EKF (Extended Kalman Filter), or other estimation methods are used for this purpose. In determining the rotor angle, measurement parameters also used for the adjustment matrix, the phase voltages of the motor, and / or existing model parameters of the motor, such as Ld, Lq, m, and R, are particularly considered.

[0040] Preferably, for the PLL method, the back EMF voltage is calculated based on the phase current and phase voltage using a model. In the d / q coordinate system, the back EMF voltage is zero in the d direction. The back EMF voltage in the d direction is adjusted to zero using a PI controller, where the control parameter for this is the angular velocity ω.

[0041] Alternatively, the Kalman filtering method is preferred. A linear time-varying model is obtained by linearization around the current operating point and subsequent discretization, which is then taken into account in the extended Kalman filter. The method includes step prediction and correction.

[0042] Furthermore, the present invention relates to a computer program comprising instructions that, when executed by a computer, cause the computer to perform the steps of the method described herein.

[0043] Furthermore, the present invention relates to a computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the steps of the method described herein.

[0044] Furthermore, the present invention relates to a device for regulating a motor, comprising a calculation unit and a harmonic regulator, wherein the harmonic regulator includes an input stage, a regulator, and an output stage. The device is configured to perform the steps of the described method.

[0045] Advantageously, a device for effective harmonic regulation of an electric motor is provided.

[0046] Furthermore, the present invention relates to an electric drive system having a motor and the described device. Such an electric drive system is, for example, used to drive a compressor of a heat pump. With the aid of the described method and device, optimized operation in terms of mechanical load and / or noise generation of the drive system is achieved.

[0047] Furthermore, the present invention relates to a heat pump having the described electric drive system, wherein the heat pump includes a compressor (640) and, in particular, a condenser (610), a throttle valve (620), or an evaporator (630). Thus, it is advantageous to provide a heat pump including a device by means of which the motor is effectively regulated.

[0048] It should be understood that the features, characteristics, and advantages of the method according to the invention can be accordingly applied to or utilized in devices or electric drive systems and heat pumps, and vice versa.

[0049] Other features and advantages of embodiments of the present invention will become apparent from the following description with reference to the accompanying drawings. Attached Figure Description

[0050] The invention will be further described below with reference to some accompanying drawings, for which:

[0051] Figure 1 A schematic diagram of the adjustment structure of a harmonic modulator;

[0052] Figure 2 A schematic control structure for replacing harmonic modulators;

[0053] Figure 3 A schematic flowchart illustrating the method for adjusting the motor;

[0054] Figure 4 A schematic diagram of a device for adjusting a motor;

[0055] Figure 5 A heat pump with an electrically driven system, presented schematically. Detailed Implementation

[0056] Figure 1A schematic adjustment structure of a harmonic regulator 200 is shown, wherein the harmonic regulator 200 includes an input stage 210, a regulator 220, and an output stage 230. The obtained measurement parameters id and iq are fed to the input stage 210. These measurement parameters preferably characterize the current in the motor. Based on the detected measurement parameters id and iq, cosine and sine measurement components of a predetermined frequency, idcos_m, idsin_m, iqcos_m, and iqsin_m, are obtained using the input stage 210. Preferably, the measurement parameters are multiplied for this purpose by the cosine and sine functions cos and sin of the predetermined frequency using multipliers 211 and 212. Based on the cosine and sine measurement components idcos_m, idsin_m, iqcos_m, iqsin_m, the cosine control parameters idcos_s, idsin_s, iqcos_s, iqsin_s are obtained using regulator 220 and a predetermined regulation matrix 224 of regulator 220. Based on the obtained cosine and sine control parameters idcos_s, idsin_s, iqcos_s, iqsin_s, at least two control parameters ud, uq are obtained using output stage 230. Preferably, the cosine and sine control parameters idcos_s, idsin_s, iqcos_s, iqsin_s are multiplied by multipliers 231, 232 with predetermined frequency cosine and sine functions cos, sin. The motor 204 is controlled according to the obtained control parameters ud and uq, preferably by means of an inverter 203.

[0057] Figure 2 A schematic alternative adjustment structure to the harmonic modulator 200 is shown. As a counterpart to... Figure 1 In addition, regulator 220 includes two differentiators 221 and 222 to form the differences between the corresponding cosine and sine measurement components idcos_m, idsin_m, iqcos_m, iqsin_m and the pre-given cosine and sine target components idcos_so, idsin_so, iqcos_so, iqsin_so. Figure 2 These differences are multiplied by a predetermined adjustment matrix to obtain the cosine control parameters and the sine control parameters idcos_s, idsin_s, iqcos_s, iqsin_s. Using output stage 230, the obtained cosine control parameters idcos_s, idsin_s, iqcos_s, iqsin_s are first fed to integrators 233 and 234, and then multiplied by predetermined frequency cosine and sine functions (cos, sin) respectively to obtain the two control parameters ud and uq.

[0058] Figure 3A flowchart illustrating a schematic representation of a method 400 for adjusting motor 204 is shown. In step 110, at least two measurement parameters id and iq are obtained. In step 120, cosine and sine measurement components of a predetermined frequency are obtained: idcos_m, idsin_m, iqcos_m, iqsin_m. In step 130, cosine and sine control parameters idcos_s, idsin_s, iqcos_s, iqsin_s are obtained. In step 140, at least two control parameters ud and uq are obtained, and motor 204 is manipulated in step 150 using these control parameters.

[0059] Figure 4 A schematic diagram of a device 300 for regulating motor 204 is shown. Motor 204 is controlled by an inverter 203. Device 300 includes a harmonic regulator 200 and a computing unit 310 for controlling and implementing the structure of the harmonic regulator 200. The device is configured to implement the above-described method steps and thus operate and regulate motor 204.

[0060] Figure 5 A heat pump 600 is shown as schematically illustrated, comprising an electric drive system 500. The drive system 500 includes a motor 204 controlled by an inverter 203 and a device 300 for regulating the motor 204, as shown in... Figure 4 As described herein. A motor-driven compressor 640 drives the heat pump. Preferably, the heat pump includes a condenser 610, a throttling valve 620, and / or an evaporator 630.

Claims

1. A method (100) for regulating a motor (204), the motor having a harmonic regulator (200), the harmonic regulator comprising an input stage (210), a regulator (220), and an output stage (230), wherein, The motor (204) is configured as a rotating field motor, and the method comprises the following steps: In the field orientation system, two measurement parameters (id, iq) are detected and obtained (110), wherein the two measurement parameters (id, iq) represent the current in the motor (204), and the two measurement parameters (id, iq) are two components of the stator current vector in the d / q coordinate system; Based on the detected measurement parameters (id, iq), the cosine measurement component and sine measurement component (idcos_m, idsin_m, iqcos_m, iqsin_m) of a predetermined frequency are obtained (120) by means of the input stage (210), wherein the predetermined frequency corresponds to the frequency of a predetermined order harmonic. Based on the cosine measurement components and sine measurement components (idcos_m, idsin_m, iqcos_m, iqsin_m), the cosine control parameters (idcos_s, idsin_s, iqcos_s, iqsin_s) are obtained (130) using the regulator (220) and the predetermined regulation matrix (224) of the regulator (220). Based on the obtained cosine control parameters and sine control parameters (idcos_s, idsin_s, iqcos_s, iqsin_s), two control parameters (ud, uq) are obtained (140) by means of the output stage (230), wherein the two control parameters (ud, uq) are two independent control voltages of the motor (204) under the field orientation adjustment in the d / q coordinate system; The motor (204) is controlled (150) according to the obtained control parameters (ud, uq).

2. The method (100) according to claim 1, wherein, Using the input stage (210), the detected measurement parameters (id, iq) are multiplied by the cosine function and sine function (cos, sin) of the predetermined frequency, respectively, to obtain the cosine measurement component and sine measurement component (idcos_m, idsin_m, iqcos_m, iqsin_m) with the predetermined frequency.

3. The method (100) according to claim 1 or 2, wherein, Using the regulator (220), the difference between the corresponding cosine measurement component and sine measurement component (idcos_m, idsin_m, iqcos_m, iqsin_m) and the pre-given cosine target component and sine target component (idcos_so, idsin_so, iqcos_so, iqsin_so) is multiplied by a pre-determined adjustment matrix to obtain the cosine control parameter and sine control parameter (idcos_s, idsin_s, iqcos_s, iqsin_s).

4. The method (100) according to claim 1 or 2, wherein, Using the output stage, the obtained cosine control parameters and sine control parameters (idcos_s, idsin_s, iqcos_s, iqsin_s) are multiplied by the predetermined frequency cosine function and sine function (cos, sin) respectively to obtain the control parameters (ud, uq).

5. The method according to claim 1 or 2, wherein, The method steps are implemented based on the current rotor angle of the motor, and the rotor angle is obtained based on the detected measurement parameters (id, iq).

6. A computer program product comprising instructions that, when implemented by a computer, cause the computer to perform the steps of the method / method (100) according to any one of claims 1 to 5.

7. A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the steps of the method / method (100) according to any one of claims 1 to 5.

8. A device (300) for regulating a motor (204), said device having a computing unit (310) and a harmonic regulator (200), wherein, The harmonic modulator includes an input stage (210), a modulator (220), and an output stage (230), wherein the device is configured to implement the steps of the method according to any one of claims 1 to 5.

9. An electric drive system (500) having a motor (204) and the device (300) according to claim 8.

10. A heat pump (600) having an electric drive system (500) according to claim 9, wherein, The heat pump includes a compressor (640).

11. The heat pump (600) according to claim 10, wherein, The heat pump includes a condenser (610), a throttle valve (620), and / or an evaporator (630).

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