JP2007060783A - Motor drive control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a discrepancy in rotational phase detection caused by a parameter error. <P>SOLUTION: Torque is estimated from power and the number of revolutions, when an actual motor current is large with respect to a motor current that corresponds to the torque, and when a voltage applied to the motor is lower than a maximum voltage that can be outputted, a current lead angle value to the motor is made small, and when the voltage applied to the motor is equal to the maximum voltage that can be outputted, and the actual motor current is smaller than the current that can be outputted, the current lead angle value to the motor is increased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor drive control device that drives a motor as a driving force such as a compressor of an air conditioner with high efficiency.

  Conventionally, in this type of motor driving device, an induction motor that can be driven only by applying an AC voltage is changed to a so-called IPM structure in which a permanent magnet is built in a rotor, thereby increasing efficiency by utilizing reluctance torque. ing. In addition, the IPM motor can efficiently perform field-weakening driving by advancing the current phase, and can be driven even when the generated voltage is higher than the power supply voltage, thereby realizing a wide operating range. be able to. In order to use this IPM motor as a drive source for a hermetic compressor of an air conditioner, it is necessary to appropriately perform the rotational phase of the permanent magnet without using a detector.

  As a method for detecting the rotational phase without a detector, conventionally, a method has been adopted in which the energization of the motor stator is paused for a short period and the induced voltage of the motor rotation appearing at the terminal is detected. However, when field weakening driving is performed, even if a non-energization period is provided, current continues to flow due to the inductance of the motor, making it difficult to perform large field weakening.

On the other hand, a method has been proposed in which the energization of the motor is made sinusoidal without providing a non-energization period, and the rotational phase of the permanent magnet rotor is estimated from the relationship between the voltage and current at that time. . For example, in Non-Patent Document 1, there is a driving method in which the rotational phase can be detected by comparing the relationship between the voltage and current on the rotating coordinate axis with the model and driving so as to reduce the error from the model. is there. Further, in Patent Document 1, there is a technique using a relationship between voltage and current on a fixed coordinate axis.
Japanese Patent No. 3419725 Takeshita, Nomura, Matsui "Sensorless brushless DC motor control based on current estimation error" IEICE Transactions D, Vol. 115-D, no. 4 April 1, 1995 420-427

However, in the above-described conventional configuration, if the deviation between the actual voltage and current information is eliminated using the parameters of the individual motors as models, the rotational phase can be detected properly. It is a necessary condition that the motor parameters can be accurately grasped. If the motor parameters used in the model deviate from the actual parameters, an error will occur in the detected rotational phase. The effect of the detected rotational phase error increases as the effective ratio of the current and the induced voltage increases. That is, the effect of error becomes very large when field weakening control is performed. For this reason, it is necessary to allow for the limit (hereinafter referred to as the maximum advance value) for advancing the current phase in anticipation of the parameter variation of each motor.
However, if the maximum advance value is lowered, the maximum speed that can be driven is lowered, and the drive range is narrowed. In order to secure the driving range in such a situation, it is necessary to take a technique that requires a reduction in efficiency and an increase in the cost of parts, such as increasing the power supply voltage for driving or lowering the power generation constant of the motor. Had no problem.

The present invention solves the above-described conventional problems, and provides a motor drive control device that can secure a maximum advance value and ensure a wide operating range even if the parameters of individual motors vary somewhat. The purpose is to do.

  In order to solve the conventional problem, the motor drive control device of the present invention detects the input power to the motor, calculates the torque from the input power and the rotation speed, and actually calculates the torque from the motor current corresponding to the calculated torque. When the motor current is large and the motor voltage has a margin, an operation is performed to reduce the advance setting value in the drive control.

  As a result, it is detected that the actual advance angle has increased due to the parameter deviation between the actual motor and the model, and the advance angle can be reduced. It is possible to avoid a state where the vehicle cannot be operated and to secure a wide operating range.

  In addition, when the actual motor current is not larger than the motor current corresponding to the estimated estimated torque and there is no margin in the motor voltage, the advance angle setting value in the drive control is increased. is there.

  As a result, it is detected that the actual advance angle has become smaller due to the parameter deviation between the actual motor and the model, and the advance angle can be increased. In this way, it is possible to avoid a state in which driving becomes impossible, and a wide driving range can be secured.

  The motor drive control device of the present invention can maintain a large field-weakening effect even if the motor parameters fluctuate, and can ensure a wide operating range.

  In the first invention, the input power to the motor is detected, the torque is estimated from the power and the rotational speed, the actual motor current is larger than the motor current corresponding to the torque, and the motor is applied to the motor. If the current voltage is lower than the maximum voltage that can be output, by operating to reduce the current advance value to the motor, the excessive advance angle caused by the parameter deviation is eliminated and stable. Weak field control is possible. Thereby, even if there is a parameter shift, a wide operation range can be secured.

  The second invention can be applied particularly when the deviation is the reverse of the case of the first invention. The input power to the motor is detected, the torque is estimated from the power and the rotational speed, and the actual motor. When the current is not large with respect to the motor current corresponding to the torque and the voltage applied to the motor is higher than the maximum voltage that can be output, the current advance value to the motor is increased. By operating in this way, the state of insufficient advance due to parameter deviation is resolved, and a wide operating range can be secured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a characteristic diagram showing the operation principle of the motor drive control device according to the embodiment of the present invention.

In FIG. 1, the upper graph is a graph showing the relationship between the current advance angle and the motor current, and the lower graph is a graph showing the relationship between the current advance angle and the motor voltage. When the load torque is the same and the rotational speed is the same, increasing the current advance angle tends to increase the motor current and decrease the motor voltage. Further, when the load torque increases, both the motor current and the motor voltage tend to increase.

  Here, it is assumed that the current advance angle is set as β0 and driving. At this time, a current flows as indicated by a solid line arrow, and a necessary voltage can be output. Consider a case where the current increases in this state. The increase in current can be considered when the load torque is increased or when the current advance angle is shifted to β1. On the other hand, if the efficiency of the drive circuit and the motor does not change so much, the torque is approximately proportional to the result obtained by dividing the input power by the rotation speed, so it is possible to check whether the torque has increased. Further, when the current advance angle is advanced, the motor voltage is lowered, so that it is possible to distinguish between an increase in torque or a deviation in current advance angle. As a result, when the current increase is caused by the current advance angle deviation, the motor current can be reduced by returning the current advance angle.

  Next, a detection method when the parameter is shifted in the reverse direction will be described using the graph of FIG. Here, even when driving with the current advance angle set at β0, if there is a case where the current is small and the voltage exceeds the voltage that can be output, from the upper graph in FIG. It can be seen that either it has decreased or the current advance angle is insufficient. On the other hand, it can be seen from the lower graph of FIG. 2 that the voltage is insufficient because either the torque is increased or the current advance angle is insufficient. In other words, both are satisfied when the current advance angle is insufficient. Therefore, it can be understood that the current advance angle may be increased.

  After all, by using the operation principle shown in FIGS. 1 and 2, it is possible to eliminate the current advance angle shift due to the current phase detection shift. That is, it is possible to eliminate the influence due to the deviation of the motor parameters and to realize a wide operating range.

  FIG. 8 is a flowchart showing a control sequence for realizing the above principle. In the determination circuit 901, the control circuit checks whether or not high-speed driving is being performed. When high-speed driving is being performed, that is, when field-weakening control is not used, the entire process is terminated. calculate. Next, it progresses to the process 903 and estimates a torque from the obtained input electric power and the present rotation speed. Further, the process proceeds to decision 904 to check whether the estimated torque is within the reference value. If it is within the reference value, the process proceeds to process 905, and if not within the reference value, the entire process is terminated. In process 905, a motor current is estimated from the estimated torque using a motor model. Next, the process proceeds to decision 906, where the actual motor current is compared with the estimated value. If the actual motor current is large, the process proceeds to decision 907, and if the actual motor current is small, the process proceeds to decision 909. In decision 907, if the current applied voltage to the motor is smaller than the limit value, the process proceeds to process 908, and if not, the entire process is terminated. In process 908, the current advance angle setting value is slightly reduced, and the entire process is terminated. On the other hand, in the determination 909, it is checked whether or not the current applied voltage to the motor is substantially equal to the limit value. If it is the limit value, the process proceeds to the process 910. . In process 910, the current current advance setting value is slightly increased, and the entire process is terminated. 1 corresponds to the determination 906, determination 907, and processing 908 in the processing based on the principle of FIG. 1, and the processing based on the principle in FIG. 2 corresponds to the determination 906, determination 909, and processing 910. Is applicable.

Next, a circuit configuration necessary for drive control will be described with reference to FIG. FIG. 3 is a circuit block diagram showing a circuit configuration in the case of driving using a single-phase AC power source for home use or the like. The power factor improving reactor 5 and the smoothing capacitor 6 are passed from the single-phase power source 1 through the rectifier diode bridge 4. This constitutes a substantially DC power source. After the DC power supply, it is connected to the motor 3 via the three-phase bridge circuit 2. In the control circuit 300, the three-phase bridge circuit 2 is subjected to pulse width modulation control to generate a three-phase pseudo AC, and the motor 3 is driven and controlled. To do. In the control circuit 300, the current of the motor 3 is detected by the current detectors 11 a and 11 b, and the voltage applied to the motor 3 is detected by the voltage detector 14, and the pulse width modulation amount in the three-phase bridge circuit 2 is detected. The applied voltage is calculated from As a result, the motor 3 can be driven substantially appropriately. On the other hand, when the input current is detected by the current detector 313 and the product sum from time to time with the detection result of the voltage detector 14 of the DC power supply is obtained, the average input power can be obtained. Here, the input power and the motor output have the following relationship.

Input power = Circuit efficiency x Motor efficiency x Motor rotation speed x Motor torque Here, the circuit efficiency and the motor efficiency do not change so much even if the control is slightly shifted, so the approximate value of the motor torque is estimated from the input power. Is possible. Accordingly, the principle described with reference to FIGS. 1 and 2 can be realized by employing the circuit configuration of FIG. The control circuit 300 is constituted by a microcomputer, and control is realized by sequence control based on a program.

  The circuit configuration of FIG. 4 is a simplification of the circuit configuration of FIG. When the voltage of the AC power supply 1 is almost constant, the voltage of the DC portion is also constant. Therefore, by detecting the input current with the current detector 413, the input power can be obtained by proportional calculation.

  The circuit configuration of FIG. 5 is obtained by adding a circuit for improving the input power factor from the single-phase AC power source 1. When the AC power supply 1 is short-circuited by the switch 530 via the reactor 505, current is stored in the reactor 505, and when the switch 530 is turned off, current is supplied to the smoothing capacitor 6 via the rectifier diode bridge 4. Since the reactor 5 includes an operation for storing current, it is possible to obtain a DC voltage higher than the maximum voltage of the AC power supply 1. Even with such a circuit configuration, the input power can be detected by the current detector 313 and the voltage detector 14, and the control described with reference to FIGS. Can be realized.

  The circuit configuration of FIG. 6 aims at the same effect as that of FIG. The temporary short circuit of the AC power supply 1 via the reactor 605 is performed using the switch 13 after the rectification operation by the rectifier diode bridge 4. As in the case of FIG. 5, the input power can be detected by the current detector 313 and the voltage detector 14, so that the control described in FIGS. 1 and 2 can be realized and a wide operation range is realized. can do.

  The circuit configuration of FIG. 7 shows a configuration that can be applied when operating from a DC power supply. By detecting the DC voltage with the voltage detector 14 and detecting the current from the DC power source with the current detector 20, the input power can be detected, and the control described in FIGS. 1 and 2 can be realized. It becomes possible and a wide operation range can be realized.

  In addition, in order to detect the current of the motor, a method has been described in which a current detector is provided for each phase of the motor (in the case of three phases, two can be measured) and the current is directly detected. When driving with pulse width modulation in a bridge circuit, a method has been proposed in which current detection means is provided on the DC side and the motor is driven by detecting the current of each phase in a time-sharing manner. (See Japanese Patent Application Laid-Open No. 2003-111480).

  Furthermore, there is a method in which the input power to the motor can be directly calculated by multiplying the instantaneous values of the current and voltage to the motor momentarily.

As described above, the motor drive control device according to the present invention can compensate that the motor parameter fluctuates and it becomes difficult to detect the rotational phase during field-weakening control. Can be secured, and the variable variable range of the air conditioner can be expanded without increasing the size of the drive circuit.

The characteristic view which shows the cancellation principle when the electric current advance angle has advanced too much in the motor drive control device in the embodiment of the present invention The characteristic view which shows the cancellation principle when the electric current advance angle is too late in the motor drive control device in the embodiment of the present invention Whole circuit block diagram in embodiment of this invention First overall circuit configuration diagram in an embodiment of the present invention Second overall circuit configuration diagram in the embodiment of the present invention Third overall circuit configuration diagram in the embodiment of the present invention Fourth overall circuit configuration diagram in the embodiment of the present invention The flowchart which shows the control sequence in embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Three-phase bridge circuit 3 Motor 11a, 11b, 13, 20 Current detector 14 Voltage detector 300,400,500,600,800 Control circuit

Claims (8)

DC power supply or circuit means for converting AC power into motor drive AC power is detected, input power to the motor is detected, torque is estimated from the power and rotation speed, and the actual motor current is If the motor current corresponding to the torque is large and the voltage applied to the motor is lower than the maximum voltage that can be output, operate to decrease the current advance value to the motor. The motor drive control apparatus characterized by the above-mentioned. If the estimated torque is less than a certain value and the voltage applied to the motor is the same as the maximum voltage that can be output, if the actual motor current is smaller than the current that can be output, increase the current advance value to the motor. The motor drive control device according to claim 1, wherein the motor drive control device is operated as follows. The motor drive control device according to claim 1, wherein an input current value of the AC power supply is used as input power to the motor. It has a rectifier circuit that converts AC power from an AC power source into DC, and obtains the efficiency and power factor of the rectifier circuit, the efficiency of the AC converter circuit for each input power and rotation speed, and the motor efficiency in advance. The motor drive control device according to claim 1, wherein the motor torque is estimated from the efficiency and power factor of the rectifier circuit, the efficiency of the AC conversion circuit, the efficiency of the motor, and the rotational speed of the motor. 2. The motor drive control device according to claim 1, further comprising: a smoothing circuit at an output of the rectifying circuit, and detecting input power using an input current to the smoothing circuit and a voltage of the smoothing circuit. 2. The motor drive control according to claim 1, wherein a method of detecting a reference of a current-carrying current phase to a motor is based on estimation of a rotation phase using a voltage applied to the motor, a motor current, and a motor parameter. apparatus. The motor drive control device according to claim 6, wherein input power to the motor is calculated from a voltage applied to the motor and a motor current. As a rectifier circuit that converts AC power from an AC power source into DC, use an input power factor correction circuit by inserting an inductance into the power inflow path and shorting the series circuit of the AC power output terminal and the inductance for a short time. The motor drive control device according to claim 1, wherein the motor drive control device is a motor drive control device.

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