KR20020040563A - Motor driving apparatus - Google Patents

Abstract

PURPOSE: To provide a small vibration, small nose, and high efficiency motor driver which drives a motor automatically at optimum setting with respect to changes in the operation conditions. CONSTITUTION: This motor driver has a model memory means which stores a model of an induced voltage corresponding to a rotor position of a motor, a rotor position estimating means which detects the terminal voltage of the motor and estimates the rotor position according to the detected voltage and the model value, a model correction means which corrects the model according to the value of the terminal voltage and the zero-cross point of the induced voltage, a current application width setting means which sets the current application angle for the motor, so as to secure a current application width for the detection of the zero-cross point by the model correction means, and a current application control means which controls a switching device. The rotor position is estimated and detected accurately to control the drive of the motor, while the optimum model is constructed consistently, while following the changes in the induced voltage constant, etc., caused by the changing in the motor operation conditions.

Description

Motor Drive Unit {MOTOR DRIVING APPARATUS}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position sensorless motor drive apparatus using an inverter for driving a motor used in an air conditioner or the like at an arbitrary frequency.

In general, a motor driving apparatus for driving a motor such as a compressor at an arbitrary frequency in an air conditioner includes a plurality of switching elements and an inverter composed of three-phase bridges of a reflux diode connected in parallel to each switching element. have. In particular, the position of the magnetic pole of the rotor of the motor (hereinafter referred to as the "rotator position") is detected without providing a position sensor such as an encoder (such as a "position sensorless" method) for a motor connected to an inverter. Motor drive devices are widely used.

For example, as a position sensorless method, a period in which a current is zero is formed by forming a non-energized state by turning off both the upper switching element and the lower switching element for each phase. The position of the rotor is detected by comparing the induced voltage induced by the magnetic pole of the rotor detected with the predetermined set value with the comparison result. The applied voltage is switched by the detected rotor position to rotate the motor. This is a so-called " 120 degree energization " type, and the phase current flowing through the motor has a square wave shape. As such a method, there is a means disclosed in Japanese Patent Laid-Open No. 2-32790, Japanese Patent Laid-Open No. 59-25038, and the like.

In addition, a method of reading the value of the induced voltage detected in the period when the current becomes zero by A / D conversion and estimating the rotor position by the change of the induced voltage period has been proposed. As such a method, there is a means disclosed in Japanese Patent Laid-Open No. 7-123773.

In addition, as a means of realizing wide-angle energization, the rotor position is estimated without detecting the zero cross of the induced voltage to drive a DC brushless motor to realize wide-angle energization of 120 degrees or more. A high-efficiency, low-vibration motor drive device, which detects a device voltage during a dead time period of a switching element of the same phase with a voltage output circuit, and the current code change detection section determines a timing at which the phase current code changes from the terminal voltage. Means have been proposed in which the applied voltage control circuit inputs the phase applied voltage command to the switching element modulation circuit by the phase current code change timing detected and outputted from the current code change detection section and the phase of the applied voltage (Japanese Patent Application No. 10). -195396: Motor Control Units).

In these conventional motor driving apparatuses, in the 120-degree conduction-type motor driving apparatus, since the current waveform becomes a square wave having a conduction angle of 120 degrees, the current fluctuates greatly every 60 degrees from the electric angle, Noise, ie, the cogging component, is becoming very loud. In addition, in order to maximize the motor efficiency, it is necessary to drive with a current having the same shape as the induced voltage of the motor. Since the current has a square wave shape, the efficiency can not be maximized.

In addition, in the motor driving apparatus which directly A / D converts the terminal voltage of the motor in the non-energization period and estimates the rotor position based on the value, the phase switching point of the phase was determined using the change rate with respect to the time of the terminal voltage. . For this reason, it is difficult to drive a conduction angle at a wide angle of 120 degrees or more, because a wide conduction period sufficient to detect a change in the terminal voltage with time is required. In addition, when the value of the induced voltage generated by the magnetic force of the motor does not become a primary shape such as a straight line, a large error occurs in the estimated rotor position, the efficiency is greatly reduced, and the vibration and noise are also increased. In particular, depending on the type of motor having a large reluctance component, the waveform of the induced voltage is not linear but has a high order component that becomes a cogging component. When the timing was determined, the phase error became large and the driving performance was lowered. Moreover, the motor constants (inductance, resistance, etc.) changed depending on the motor operating conditions, for example, temperature, and the estimated value of the rotor position had an error from the error.

In addition, a motor drive device that improves efficiency and reduces vibration noise by making the conduction angle wider than 120 degrees is also used in, for example, the "brushless motor drive circuit" disclosed in Japanese Patent Application Laid-Open No. 59-15269. However, the rotational speed fluctuation occurred because the output voltage changes when the conduction angle was changed to a wide angle of 120 degrees or more.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a low vibration, low noise, and high efficiency motor driving apparatus which automatically operates with an optimal decision at all times for a change in operating conditions.

A first motor drive device according to the present invention is a motor drive device for alternatingly driving a motor by inputting a direct current power source, the plurality of switching elements, voltage detecting means for detecting a terminal voltage of the motor, and a rotor position of the motor. Model storage means for storing a model of the terminal voltage value of the motor corresponding to the rotor, rotor position estimation means for estimating the rotor position of the motor from the detected terminal voltage value and the value of the model stored in the model storage means, and estimation Power supply control means for outputting a gate signal for driving the switching element corresponding to the rotated rotor position, and energizing and driving the motor; and model correction means for correcting the model stored in the model storage means. In particular, the model correcting means corrects the model stored in the model storing means from the time difference between the detected value of the terminal voltage of the motor, the time of detecting the value of the terminal voltage and the zero cross point of the induced voltage. In this way, the rotor position is estimated and controlled based on the terminal voltage and the model, thus simplifying control and enabling wide-angle energization, and also correcting the model based on the actual state of the motor. With one setting, low vibration, low noise and high efficiency motor driving can be realized.

A second motor drive device according to the present invention is a motor drive device for alternatingly driving a motor by inputting a direct current power source, the plurality of switching elements, voltage detecting means for detecting a terminal voltage of the motor, and a rotor position of the motor. Model storage means for storing a model of the terminal voltage value of the motor corresponding to the rotor, rotor position estimation means for estimating the rotor position of the motor from the detected terminal voltage value and the value of the model stored in the model storage means, and estimation And energization control means for energizing and driving the motor by outputting a gate signal for driving the switching element corresponding to the rotated rotor position. In particular, when the energization control means changes the energization angle, smooth operation is realized when the energization angle is changed by changing the pulse width of the gate signal output to the switching element corresponding to the energization angle.

In the first and second motor drive apparatuses, it is preferable to drive at a conduction angle of 120 degrees or more and less than 180 degrees during normal operation. As a result, high efficiency, low vibration and low noise can be realized as wide-angle energization during normal operation.

Further, the first and second motor drive devices may be provided with energization width setting means for setting the energization angle as the energization control means. This conduction width setting means sets the conduction angle in such a case that the conduction angle in this case is narrower than in normal operation so that a conduction section for detecting the zero cross point of the induced voltage is ensured when the model correction means performs model correction. . This makes it possible to reliably detect the zero cross point of the induced voltage for model correction, and to always accurately identify the model.

Further, in the first and second motor drive apparatuses, the model correction means may perform model correction at the time of startup or at a predetermined cycle. In this way, by correcting the model on a regular basis, a stable motor drive device can be realized with a minimum reduction in efficiency against environmental changes in the motor drive.

Further, in the second motor drive device, when the current supply angle is changed in accordance with the setting of the current supply width setting means, the output pulse width to the switching element so that the output to the motor does not change in accordance with the change in the current supply angle. It is preferable to change the value continuously in correspondence with the conduction angle.

In the motor drive device of the present invention, the model storage means stores a model of the value of the terminal voltage of the motor in correspondence with the rotor position. In the embodiments described later, the rotor position θ expressed by the rotation angle is approximated to a nodal line, and the specific rotor positions θ1 to θ4 are nodes, and at these positions, The terminal voltage is set as parameters X1 to X4, and the parameter X is changed linearly with respect to the rotational speed ω, and the change coefficient is set as parameters FX1 to FX4, and these parameters X and parameter FX are stored as model values. Doing. However, it is not limited to these. Moreover, although the rotor position is shown by the rotation angle, you may express as a rotation time difference, of course.

The rotor position estimating means is means for estimating the rotor position, and estimates the rotor position from the terminal voltage of the motor detected by the voltage detecting means and the value of the model. By estimating and controlling the rotor position from the model, it is unnecessary to always determine the rotor position in real time, simplifying the control and contributing to the speed of the process. Note that a reference position is required for the value of the terminal voltage, and in the embodiment, half of the voltage of the DC portion detected by the DC portion voltage detecting means is used as the reference potential.

In addition, the model correcting means is a means for correcting the value of the model according to the actual situation while driving, the time difference between the time when the terminal voltage is detected and the zero cross point of the induced voltage means the rotor position expressed in rotation time, That is, at that time, it is an estimate of the rotor position. In this way, the model is corrected from the set values of the terminal voltage and the rotor position so that the model corresponds to the actual situation of the motor. In the embodiment, as described above, the rotor position is expressed by the rotation angle. In this case, the determined value of the rotor position is detected in real time from the terminal voltage at zero cross point of the induced voltage in the non-energized section, From the temporal relative position to the zero cross point of the position and the rotational speed, it is estimated as the rotor position θ in the angular representation. This model correction requires a wide non-energization section as long as the zero cross point can be detected, and model correction is difficult when driving wide-angle energization for the purpose of high efficiency driving. For example, model correction is performed in a driving state of 120 degree energization. It goes without saying that the detection of the zero cross point is unnecessary for the estimation of the rotor position.

1 is a block diagram showing the configuration of an embodiment of a motor drive device of the present invention;

FIG. 2 is a diagram showing waveform examples of terminal voltages (including organic voltages) of a motor according to the present embodiment; FIG.

3 is a view showing an example of a model of a terminal voltage in this embodiment;

4 is a diagram showing an example of a change in a parameter of a model of the terminal voltage corresponding to the rotational speed in the present embodiment;

Fig. 5 is a diagram showing a waveform example of terminal voltage at the time of energization in the present embodiment;

6 is a view showing an example of a model correcting operation of the model correcting means in the present embodiment;

FIG. 7 is a diagram showing a waveform example of a driving voltage at the time of energization in the present embodiment; FIG.

8 is a diagram showing a waveform example of terminal voltage at the time of energizing in the present embodiment;

9 is a flowchart showing a model correcting operation of the model correcting means in the present embodiment;

Fig. 10 is a view showing the transition of the duty rate during the switching operation of the energizing angle in this embodiment.

* Description of the symbols for the main parts of the drawings *

1: AC power source 3: Motor drive device

4 motor 5a to 5f switching element

6a to 6f: reflux diodes 7a to 7c: voltage detection means

10 DC voltage detection means

EMBODIMENT OF THE INVENTION Hereinafter, the preferred embodiment of the motor drive apparatus which concerns on this invention with reference to an accompanying drawing is described.

1 is a block diagram showing the configuration of a motor drive apparatus according to the present invention.

In Fig. 1, the DC voltage obtained by rectifying the input from the AC power supply 1 to the DC in the rectifier circuit 2 is a pair of switching elements 5a to 5f and reflux diodes 6a to 6f in the motor driving device 3. The motor 4, which is a brushless DC motor, is driven by being converted into an alternating voltage of three phases by means of an inverter composed of:

In the motor drive device 3, the voltage detecting means 7a to 7c detect the terminal voltage of the motor 4. The rotor position estimating means 8 estimates the rotor position of the motor 4 using the terminal voltage of the motor 4 detected by the voltage detecting means 7a to 7b. The energization control means 9 outputs a signal for driving the switching elements 5a to 5f corresponding to the drive signal for driving the motor 4 by the estimated rotor position information.

In addition, the energization control means 9 switches the switching element 5a so that the rotor speed becomes the target speed from the information of the deviation of the rotor speed of the motor 4 estimated from the estimated rotor position and the target speed imparted from the outside. The energization of ˜5f) is controlled. The model storage means 11 stores model values as information defining a model representing the relationship between the rotor position and the motor terminal voltage.

The rotor position estimating means 8 includes the terminal voltage detected by the voltage detecting means 7a to 7c, the voltage of the DC portion detected by the DC voltage detecting means 10, and the motor stored in the model storing means 11. The rotor position of the motor is estimated using the model value of the terminal voltage. In addition, the model correcting means 12 periodically outputs a conduction angle necessary for detecting the zero cross of the induced voltage of the motor to the conduction width setting means 13 to correct the model stored in the model storage means 11. Further, the energization angle setting means 13 controls the energization control means 9 to realize the energization angle necessary for model correction input from the model correction means 12. The model correcting means 12 corrects the model by using the information of the zero cross point of the induced voltage and the terminal voltage value of the motor.

The operation of the rotor position estimating means 8 will be described below.

Fig. 2 is a waveform diagram showing an example of terminal voltages of one phase at the time of energization of a motor. In the non-energized state in which the PWM output of the one phase is stopped, the induced voltage of the one phase is shown as the terminal voltage at the timing when the PWM signal of the other phase is on.

In a motor drive device of a general brushless motor, the intersection point of this induced voltage with the virtual neutral point position of the motor or 1/2 of the DC voltage VDC is detected as the zero cross point, and the zero cross point is determined by the rotor position. As the reference point, the rotor position is always determined to perform current operation or the like. On the other hand, in the motor drive apparatus of this embodiment, the rotor position is estimated and controlled. That is, after detecting the terminal voltage by A / D conversion, the rotor position of the motor is estimated and determined by comparing the value with the model value of the induced voltage stored in the model storage means 11.

For example, suppose that the terminal voltage detected at time A point is VA as shown in FIG. It is assumed that a model as shown in Fig. 3 is set as a model of the induced voltage value obtained from the terminal voltage of the motor stored in the model storage means 11 now. In this embodiment, the model giving the induced voltage corresponding to the rotor position θ is defined by the model value of the rotor position θ and the parameter X as described below. It is assumed that the value of the induced voltage is approximated in three straight lines corresponding to the rotor rotation angle, that is, the rotor position θ, and the rotation angle of the rotor as shown in Fig. 4 is shown in the parameters X1, X2, X3 and X4 of the model. Assume that it changes linearly in correspondence to ω. If the rotation angle ω of the motor is RA, the parameters X1 to X4 are expressed by the following equation using the other parameters FX1 to FX4 corresponding to these from the terminal voltage VA and the rotational speed ω (= RA).

X1 = FX1 × RA

X2 = FX2 × RA

X3 = FX3 × RA

X4 = FX4 × RA

In this case, the rotor position θ is obtained by the following equation corresponding to the value of the terminal voltage VA.

For VA <X2,

θ = θ2-(θ2-θ1) × (X2-VA) / (X2-X1)

For X2 <VA <X3,

θ = θ2 + (θ3-θ2) × (VA-X2) / (X3-X2)

For VA> X3

θ = θ3 + (θ4-θ3) × (VA-X3) / (X4-X3)

In this way, the rotor position θ is estimated from the detected terminal voltage VA and the rotational speed ω.

Next, the operation of the model correction means 12 will be described.

It is assumed that the waveform of the terminal voltage when the motor drive device of the present embodiment is driving the motor at a certain rotational speed RB is as shown in FIG. In the case of Fig. 5, the terminal voltage before and after the zero cross point and the rotor position thereof are observed while observing the zero cross point of the induced voltage. In this case, the parameters X1, X2, X3 and X4 are determined using the terminal voltages observed for each rotor position θ1, θ2, θ3 and θ4 in the model. Then, the parameters FX1, FX2, FX3, and FX4 are determined from the determined X1, X2, X3, X4 and the rotational speed RB in that case by the following equation.

FX1 = X1 / RB

FX2 = X2 / RB

FX3 = X3 / RB

FX4 = X4 / RB

For example, as shown in Fig. 6, when the terminal voltage value for the rotor position θ4 when the value of the rotational speed ω is RB changes from the previous detection value X4 'to the current detection value X4, X4 The model parameters related to are corrected from the straight line shown by "4 before correction" to the straight line shown by "4 after correction". In other words, the parameter relating to X4 is corrected from FX4 '(= X4' / RB) to FX4 (= X4 / RB). The corrected parameters are stored in the model storage means 11.

According to the above procedure, the model stored in the model storage means 11 can be corrected from the observed value of the terminal voltage and the rotor position from the zero cross point of the induced voltage. In response to the fluctuation, it is always possible to realize accurate estimation of the rotor position.

Next, operation | movement of the electricity supply width setting means 13 is demonstrated.

As described above, the model correcting means 12 corrects the model stored in the model storing means 11 by the observed terminal voltage. In this case, since the phase reference value at that time is required, a zero cross point of the induced voltage is required. For this reason, in the operation of calibrating the model, a non-energized section should be secured as long as the zero cross point can be detected. On the other hand, it is desired to operate at a wide angle as much as possible for the improvement of efficiency, the reduction of vibration, and the noise at the time of operation (normal operation) which does not perform model correction. As a result, it is necessary to drive at 120 degree energization during the model correction operation, and to operate at wide angle energization of 120 degrees or more during normal operation.

In order to realize this, in the motor drive device of the present embodiment, the energization width setting means 13 is set so as to realize wide angle energization during normal operation and 120 degree energization during model correction operation. The energization width setting means 13 is a wide-angle energization method as shown in Fig. 7B during normal operation according to the energization method as shown in Fig. 7 according to such a setting, and also during model correction operation. The energization of the switching element is controlled by the energization method as shown in Fig. 7A. In that case, the terminal voltage of the motor is as shown in Fig. 8, and the rotor position of the motor is estimated by the terminal voltage of each non-energized section.

This model correction process is performed at a fixed cycle, for example, at the time of motor start or every minute. Therefore, it is possible to accurately estimate the rotor position of the motor in response to changes in the induced voltage constant of the motor caused by changes in the environment such as temperature rise of the motor. This makes it possible to reliably drive the motor with high efficiency, low vibration and low noise even when the operating environment changes.

The above model correction operation will be described according to the flowchart.

9 is a flowchart showing a model correction operation. First, the terminal voltage (organic voltage) of the motor 4 is detected via the voltage detecting means 7a to 7c (step 1), and the detected terminal voltage is stored in the memory (step 2). Next, the rotor position of the motor 4 is estimated based on the model stored in the model storage means 11 using the detected terminal voltage (step 3). Thereafter, the operation branches to two operations according to the current operation mode (step 4). The operation mode includes a "zero cross point detection mode" indicating the operation of model correction and a "wide-angle energization mode" indicating normal operation. In the zero cross point detection mode, a zero cross point of the induced voltage is detected, and model correction is performed based on it. On the other hand, since it is not necessary to detect the zero cross point of the induced voltage during normal operation, driving is performed by wide-angle energization which is advantageous in terms of efficiency and vibration noise (wide-angle energization mode). The switching of these two operation modes is controlled by timing, and switching from the normal wide-angle energization mode to the zero cross point detection mode at regular intervals is performed.

If the current mode is the zero cross point detection mode, it is determined whether or not the zero cross point has already been detected (step 5). If the zero cross point is not detected, only the energization angle is set (step 7) without performing the correcting operation (step 6), and the flow proceeds to the next execution. In step 7, the energization angle is set to energize at 120 degrees in order to enable detection of the zero cross point. When the zero cross point is detected by repeating the above processes (steps 1 to 7), the time difference between the terminal voltage (organic voltage) value already detected and stored in the memory, the time when the terminal voltage is detected, and the detection time of the zero cross point. The model correction is performed using the information (step 6). Model correction is performed by correcting the parameters FX1, FX2, FX3, and FX4 as described above.

On the other hand, in the case where the current mode is the wide angle mode, in step 8, the energization angle is set so as to conduct electricity at an optimum conduction angle, for example, 150 degree energization, in terms of efficiency and vibration noise.

The conduction width setting means 13 is interlocked with the model correction means 12. In other words, when the model correction means 12 performs the model correction operation (at the time of the zero cross point detection mode operation), the current supply width setting means 13 can detect the zero cross point of the induced voltage. When the model correction means 12 performs normal operation (at the time of the wide-angle electricity supply mode operation | movement), it sets to the electricity supply angle for power supply for wide angle electricity supply. At the time of switching this energization angle, an energization angle is changed continuously as shown in FIG.

When switching the energizing angle, the rotational speed of the motor fluctuates because the average value of the output voltage changes to the energizing angle. To prevent this, the energization control means 9 continuously changes the duty ratio of the output pulses at the same time as the continuous switching of the energization angles, as shown in FIG. This prevents fluctuations in the output voltage and realizes stable motor rotational speed control. For example, when the conduction angle changes from 120 degrees to Ø, the duty ratio of this output pulse is changed from the duty ratio d2 when the conduction angle is 120 degrees to the duty ratio d1 obtained by the following equation.

d1 = d2 × 120 / Ø

As a result, there is no variation in the output voltage and a stable motor drive device can be realized.

The energization control means 9 may be realized by a dedicated hard circuit or by software executed by a microcomputer.

While the present invention has been described in terms of specific embodiments, many other variations, modifications, and uses are apparent to those skilled in the art. Accordingly, the invention is not limited to the specific disclosure herein but may be limited only by the appended claims.

According to the present invention, it is possible to realize a low vibration, low noise, and high efficiency motor drive device which automatically operates with an optimum decision at all times in response to a change in the operating conditions.

Claims (9)

In a motor drive device for alternatingly driving a motor with a DC power source as input, A plurality of switching elements, Voltage detecting means for detecting a terminal voltage of the motor; Model storage means for storing a model of the terminal voltage value of the motor corresponding to the rotor position of the motor; Rotor position estimation means for estimating the rotor position of the motor from the detected terminal voltage value and the value of the model stored in the model storage means; Energization control means for energizing and driving the motor by outputting a gate signal for driving the switching element corresponding to the estimated rotor position; Model correction means for correcting the model stored in the model storage means, And the model correcting means corrects the model stored in the model storage means from the time difference between the detected value of the terminal voltage of the motor, the time at which the terminal voltage is detected, and the zero cross point of the induced voltage. . The motor drive device according to claim 1, wherein the motor driving device is driven at a conduction angle of 120 degrees or more and less than 180 degrees during normal operation. 3. The power supply width setting means according to claim 2, further comprising a power supply width setting means for setting the power supply angle to the power supply control means, wherein the power supply width setting means sets the current supply angle in the case where the model correction means performs the model correction. A motor driving apparatus, wherein the motor driving device is set so as to have a narrower angle than in normal operation so as to secure a non-energized section capable of detecting a zero cross point. 2. The motor drive device according to claim 1, wherein the model correction means executes model correction at startup or at a predetermined cycle. In a motor drive device for alternatingly driving a motor with a DC power source as input, A plurality of switching elements, Voltage detecting means for detecting a terminal voltage of the motor; Model storage means for storing a model of the value of the terminal voltage of the motor corresponding to the rotor position of the motor; Rotor position estimation means for estimating the rotor position of the motor from the detected terminal voltage value and the value of the model stored in the model storage means; And an energization control means for energizing and driving the motor by outputting a gate signal for driving the switching element corresponding to the estimated rotor position, And wherein the energization control means changes the pulse width of the gate signal output to the switching element corresponding to the energization angle when the energization angle is changed. 6. The motor drive device according to claim 5, wherein the motor driving device is driven at a conduction angle of 120 degrees or more and less than 180 degrees during normal operation. 7. The power supply width setting means according to claim 6, further comprising a power supply width setting means for setting the power supply angle to the power supply control means. When the model correction means performs model correction, the current supply angle in that case can detect the zero cross point of the induced voltage. Motor driving device, characterized in that to be set to a narrower angle than during normal operation so that the non-energized section is secured. 6. The motor drive apparatus according to claim 5, wherein the model correction means executes model correction at startup or at predetermined intervals. 6. The motor driving apparatus according to claim 5, wherein the energization control means continuously changes the output pulse width to the switching element so that the output to the motor does not change in accordance with the change of the energization angle. .