JP2014079034A - Motor control device and refrigeration machine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device which can stably switch energization methods even when a load torque is fluctuated, and a refrigeration machine using the motor control device.SOLUTION: The motor control device has: a power conversion circuit which converts DC power into AC power; a controller which outputs a drive signal which drives the power conversion circuit; an electric motor driven by the power conversion circuit; and a load connected to the electric motor. The motor control device switches energization methods of the power conversion circuit between a 120-degree energization method and a 180-degree energization method. The total sum of the current flowing to the electric motor at the time when the energization method is switched to the 180-degree energization method from the 120-degree energization method is the same total sum of the current or larger which was flowing to the electric motor during the 120-degree energization.

Description

  The present invention relates to a motor control device and a refrigerator using the same.

  As background art of this technical field, for example, there is JP 2008-172948 A (Patent Document 1). In this publication, “when switching from one drive system to the other drive system, the rotational speed control PWM duty / modulation rate calculation unit and the energization switching control / voltage / current phase difference calculation / voltage phase calculation unit are: In one drive system, control is performed so that the current phase with respect to the rotor position of the brushless motor immediately before switching is equal to the current phase immediately after switching. "

JP 2008-172948 A

  In Patent Document 1, when switching from one driving method to the other driving method, the current phase with respect to the rotor position of the brushless motor immediately before switching in one driving method is equal to the current phase immediately after switching. The mechanism to control is described. However, the brushless motor control device disclosed in Patent Document 1 does not consider fluctuations in the load torque of the brushless motor.

  Therefore, an object of the present invention is to provide a motor control device capable of stably switching the energization method even when the load torque varies when the energization method is switched, and a refrigerator using the same. .

In order to solve the above problems, for example, the configuration described in the claims is adopted.
The present application includes a plurality of means for solving the above-described problems. For example, when switching from the 120-degree energization method to the 180-degree energization method, the current flowing in the motor at the time of switching to 180-degree energization is described. The sum total is characterized by being the same as or increasing with the sum of the currents flowing to the motor during 120-degree energization.

ADVANTAGE OF THE INVENTION According to this invention, the motor control apparatus which can switch an electricity supply system stably even if there exists a fluctuation | variation of load torque, and a refrigerator using the same can be provided.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is an example of the block diagram of a motor control apparatus. It is an example of the figure which shows the relationship of a coordinate axis. It is an example of the relationship diagram of a control axis and a three-phase axis. It is an example of a block diagram of a power converter circuit. It is an example of the block diagram of a mechanism part (compression mechanism part). It is an example of the change of the load torque with respect to the position of a rotor. It is an example of a 120-degree energization switching method. It is an example of the block diagram of an open phase voltage detection means. It is a schematic diagram in the case of applying a voltage to the two phases of the motor. It is an example of the electromotive force characteristic figure of a non-energized phase. It is an example of the open phase electromotive voltage characteristic with respect to a rotation angle position. It is an example of the relationship diagram of the open phase electromotive force voltage with respect to a rotation angle position, and a reference voltage. It is an example of a reference level switch. It is an example of the block diagram of a voltage command value calculating means. It is an example of the block diagram of the position estimation means 41 for 180 degrees. It is an example of a speed controller. It is an example of a current controller. It is an example of the current waveform at the time of switching the energization method (without countermeasures). It is an example of a block diagram of an initial value calculating means. It is an example of a starting sequence. It is an example of a switching system of a 180 degree energization system. It is an example of the relationship between the voltage command value and drive signal by another system. It is an example of a structure of a 120 degree position estimation means. It is an example of the relationship diagram of an electricity supply mode and an electrical angle phase. It is an example of the relationship figure of an electrical angle phase and energization mode. It is an example of the measurement result of an electric current detection value. This is an example when the load torque at the time of switching the energization method is small. This is an example when the load torque at the time of switching the energization method is large. It is an example when the initial value is changed when the energization method is switched. It is an example of the block diagram which shows a refrigerator. It is an example of a speed calculation result. It is an example of another block diagram of a voltage command value calculating means. It is an example of a verification means. 3 is an example of a configuration diagram of an energization method switching determination unit 30. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  In this embodiment, an example of the motor control device 1 when a compression mechanism is used as the mechanism will be described.

<Overall configuration>
FIG. 1 is an example of a configuration diagram of a motor control device in the present embodiment. The motor control device 1 is roughly divided into a power conversion circuit 5 that outputs AC power, a motor (electric motor) 6 that is driven by the power conversion circuit 5, and a load that is mechanically or magnetically connected to the motor 6. And a control unit 2 that directly or indirectly detects a current flowing through the motor 6 or a position or speed of the motor 6 and calculates a voltage command value to be applied to the motor 6. The load 500 is, for example, a compression mechanism unit.

FIG. 4 is an example of a configuration diagram of the power conversion circuit. The power conversion circuit 5 includes an inverter 21, a DC voltage source 20, and a gate driver circuit 23. The inverter 21 is configured by a switching element 22 (for example, a semiconductor switching element such as IGBT or MOS-FET). These switching elements 22 are connected in series and constitute upper and lower arms of the U phase, the V phase, and the W phase. The connection point of the upper and lower arms of each phase is wired to the motor 6.
The switching element 22 performs a switching operation according to the pulsed gate signals (24a to 24f) output from the gate driver circuit 23 based on the drive signal generated by the control unit 2. By switching the DC voltage source 20 and outputting the voltage, a three-phase AC voltage having an arbitrary frequency can be applied to the motor 6, thereby driving the motor at a variable speed.

  The drive signal generated by the control unit 2 and the gate signal generated (amplified) by the gate driver circuit 23 are different in signal voltage level (for example, 5V and 15V) and the like. . However, even if the gate driver circuit 23 is treated as an ideal circuit in the present embodiment, the effect is not affected. Therefore, the drive signal and the gate signal that appear thereafter are treated as the same meaning unless otherwise specified.

  When the shunt resistor 25 is added to the DC side of the power conversion circuit 5, it can be used for an overcurrent protection circuit for protecting the switching element 22 when an excessive current flows, a single shunt current detection method described later, and the like. Thereby, the effect of improving safety and reducing the number of parts can be obtained.

<Energization method>
Next, a method for generating a drive signal for switching the power conversion circuit 5 will be described together with an energization method.

  In FIG. 1, a PWM signal generator 33 selects a 120-degree energization method or a 180-degree energization method in accordance with an energization method switching command, and generates a drive signal corresponding to the input voltage command value. The creation of the voltage command value will be described later.

  In the 120-degree energization method, a switching operation is performed on two phases of the three-phase upper and lower arms of the power conversion circuit 5. Since switching is performed for a period of 120 degrees in a phase of 180 degrees in terms of electrical angle, this is called a 120-degree energization method. From the waveform of the voltage applied to the motor 6, it is also called square wave drive.

  There are several switching methods. For example, one of the methods shown in FIG. 7 may be used. FIG. 7 conceptually shows the drive signals of the upper and lower arms in one electrical angle cycle. In the drawing, Gp means an upper arm drive signal, and Gn means a lower arm drive signal.

  In order to determine the voltage to be applied to the motor 6, it is necessary to consider three points: the magnitude of the voltage, the waveform of the voltage, and the phase of the voltage with respect to the rotor position of the motor 6. The determination method will be described later.

  In the 180-degree energization method, basically, the three-phase upper and lower arms of the power conversion circuit 5 are all switched. FIG. 21 shows a drive signal generation method using a standard triangular wave comparison method. FIG. 21 shows a voltage command value at an electrical angle of 360 degrees and a triangular wave carrier signal for generating a drive signal. The two are compared, and the upper arm drive signal Gp and the lower arm drive signal Gn are generated as shown in the figure, depending on the magnitude relationship.

  The 180-degree energization method is called 180-degree energization because both the upper and lower arms perform switching over one electrical angle cycle. This method is also called sine wave driving because a voltage on a sine wave is applied to the motor.

  Since the switching elements of the upper and lower arms may be short-circuited due to the delay of the gate driver circuit 23 and the switching elements themselves, in reality, the dead time (several microseconds to several tens of microseconds) when both the upper and lower arms are switched off. (About seconds) is added to obtain the final drive signal. The dead time has no effect on the effect, so an ideal drive signal is shown. Of course, it is good also as a structure which added the dead time.

  In order to make maximum use of the DC voltage source 20 of the power conversion circuit 5, there is also a drive signal generation method in which the switching element of one arm is maintained in the ON state in a section of 60 electrical angles. FIG. 22 shows an example of the relationship between the voltage command value and the drive signal by this method. In this method, there is no change in the drive signal for a certain period, and at first glance it resembles a drive signal energized at 120 degrees. However, since the voltage applied to the motor is substantially close to a sine wave, this method is also 180 degrees. This is called energization.

<Motor, coordinate axis>
In this embodiment, a permanent magnet synchronous motor having a permanent magnet in the rotor is used as the motor 6. Therefore, description will be made assuming that the position of the control shaft and the position of the rotor are basically synchronized. Actually, there may be a deviation (axis error) between the position of the control shaft and the position of the rotor in a transient state during acceleration / deceleration or load fluctuation. When an axial error occurs, the torque actually generated by the motor may decrease, or current distortion or jumping may occur.

  The rotational angle position information of the rotor is obtained by position sensorless control that outputs the estimated position of the motor from the current flowing through the motor and the motor applied voltage. At this time, as shown in FIG. 2, the position of the rotor in the main magnetic flux direction is the d axis, and the dq axis is composed of the q axis that is electrically advanced from the d axis in the rotational direction by 90 degrees (electrical angle 90 degrees). Define (rotating coordinate system). The rotation angle position θd of the rotor indicates the d-axis phase. On the other hand, a dc-qc axis (rotational coordinate system) is defined which includes a virtual rotor position on the control as a dc axis and a qc axis that is electrically advanced 90 degrees in the rotation direction therefrom. In this embodiment, the voltage and current are basically controlled on the control axis that is the rotating coordinate system, but the motor can be controlled by simply adjusting the amplitude and phase of the voltage. In the following description, the dq axis is called the real axis, the dc-qc axis is called the control axis, and the error angle that is the deviation between the real axis and the control axis is called the axis error Δθc.

  FIG. 3 shows the relationship between the three-phase axis, which is a fixed coordinate system, and the control axis. The rotation angle position (estimated magnetic pole position) θdc of the dc axis is defined with reference to the U phase. The dc axis rotates in the direction of an arc-shaped arrow (counterclockwise) in the figure. Therefore, the estimated magnetic pole position θdc can be obtained by integrating the rotation frequency (inverter frequency command value ω1, which will be described later).

<Load (compression mechanism)>
Next, a case where a compression mechanism is used as the load 500 will be described. As shown in FIG. 5, the mechanism unit 500 (compression mechanism unit) drives the piston 501 using the motor 6 as a power source. Thereby, a compression operation is performed. A crankshaft 503 is connected to the shaft 502 of the motor 6 to convert the rotational motion of the motor 6 into linear motion. As the motor 6 rotates, the piston 501 also operates to perform a series of steps such as suction, compression, and discharge. The power transmission between the motor 6 and the piston 501 is often mechanically connected as shown in FIG. 5, but depending on the configuration of lubricating oil supply and the object to be compressed or transported (for example, harmful gas), it is magnetically transmitted. By including the connected mechanism, there is an effect that safety and maintainability can be improved.

  In the process of the compression mechanism, the refrigerant is first sucked from the suction port 505 provided in the cylinder 504. Thereafter, the valve 506 is closed to perform compression, and the compressed refrigerant is discharged from the discharge port 507.

  In a series of steps, the pressure applied to the piston 501 changes. This means that the load torque changes periodically when viewed from the motor 6 that drives the piston. FIG. 6 shows an example of a change in load torque with respect to the rotation angle position θd of the rotor in one rotation of the mechanical angle. In FIG. 6, an example of a four-pole motor is shown as the motor 6, so two electrical angles correspond to one mechanical angle. For example, when the motor 6 has 6 poles, 3 electrical angles corresponds to 1 mechanical angle. Although the positional relationship between the rotor position and the piston is determined by the assembly, FIG. 6 shows a change in load torque with respect to the piston position, with the bottom dead center of the piston being 0 ° of the mechanical angle. As the compression process proceeds, the load torque increases. In the discharge process, the load torque decreases rapidly. FIG. 6 shows that the load torque fluctuates during one rotation. Since the load torque fluctuates every time it rotates, the load torque fluctuates periodically when viewed from the motor 6.

  Even if the same compression mechanism unit 500 is used, the fluctuation of the load torque varies depending on the rotation speed of the motor 6, the pressure of the suction port 505 and the discharge port 507, the pressure difference between the suction port 505 and the discharge port 507, and the like. The relationship between the opening / closing timing of the valve 506 and the position of the piston varies depending on the configuration of the valve 506. For example, when a simple valve that operates with a pressure difference between the suction port 505 and the cylinder 504 is used, the opening / closing timing of the valve varies depending on the pressure condition. That is, the piston position at which the load torque becomes maximum during one rotation also changes.

  When switching the energization method of the power conversion circuit is considered, when the fluctuation of the load torque is large as described above, the current flowing through the motor 6 may jump up due to the switching of the energization method. There is a risk that the rotational speed of the motor 6 may fluctuate. As a result, vibration and noise may occur. These phenomena are called switching shocks. Accordingly, one of the purposes of the present application is to provide a motor control device that realizes switching shockless that does not cause a current jump or speed fluctuation even when the power conversion circuit energization method is switched when the fluctuation of the load torque is large. Is to provide.

  In the present embodiment, the piston 501 of the compression mechanism unit 500 is described as an example of a reciprocating type that moves linearly. However, as another method of the compression mechanism, a rotary type that compresses by rotating the piston, a spiral type, or the like There are scroll types that consist of a swirling wing. Although the characteristic of periodic load fluctuation varies depending on the compression method, there is load fluctuation caused by the compression process in any compression method. Although these load torque fluctuation characteristics are different from each other, the motor control device provided with the means described later, the drive device using the same, the refrigerator, and the air conditioner can be similarly applied even when the compression mechanism is different. The purpose of the example can be achieved.

<Control unit>
In FIG. 1, the control unit 2 inputs an electromotive voltage (terminal voltage) of a non-energized phase (open phase) to which no voltage is applied, and outputs an estimated rotational angle position and an estimated rotational speed of the rotor for 120 degree position estimation. A means 40, a 180 degree position estimating means 41 for inputting an alternating current flowing through the motor 6 or a current flowing through the direct current side of the power conversion circuit, and outputting an estimated rotational angle position and an estimated rotational speed of the rotor; The command signal and the estimated rotational angle position and estimated rotational speed of the 120-degree position estimating means 40 and the 180-degree position estimating means 41 are input, and the estimated rotational angle position and estimated rotational speed corresponding to the energization method switching command signal are output. An energization method switching device 31, a voltage command value calculating means 34, an alternating current flowing through the motor 6 or a current flowing through the DC side of the power conversion circuit is input, and an energization method switching command signal is input. The energization mode switching determiner 30 to output a PWM signal generator 33 for outputting a drive signal to enter the energization mode switching command signal and the voltage command value, an initial value calculating means 35, and a like.

  Most of the control unit 2 is configured by a semiconductor integrated circuit (arithmetic control means) such as a microcomputer or a DSP, and is realized by software or the like.

<Current detection means>
When the current flowing through the motor 6 is used by the position estimation unit 41 for 180 degrees, the current detection unit 7 is used to flow in the U-phase and the W-phase among the three-phase AC current flowing through the motor 6 or the power conversion circuit 5. Detect current. A configuration example of the current detection means is shown in FIG. For example, it can be configured by CT (Current Transformer) or the like. When this configuration is adopted, there is an advantage that current can be detected at an arbitrary timing without worrying about the switching state of the power conversion circuit 5.

  In addition, although the alternating current of all phases may be detected, if two phases of three phases can be detected from Kirchhoff's law, the other one phase can be calculated from the detected two phases.

  As another method for detecting the AC current flowing through the motor 6 or the power conversion circuit 5, for example, the current on the AC side of the power conversion circuit 5 is obtained from the DC current flowing through the shunt resistor 25 added to the DC side of the power conversion circuit 5. There is a single shunt current detection method to detect. This method utilizes the fact that a current equivalent to the alternating current of each phase of the power conversion circuit 5 flows through the shunt resistor 25 depending on the energization state of the switching elements constituting the power conversion circuit 5. Since the current flowing through the shunt resistor 25 changes with time, it is necessary to detect the current at an appropriate timing with reference to the timing at which the drive signal changes. Although not shown, there is no problem even if a single shunt current detection method is used for the current detection means 7.

<Motor terminal voltage detection means>
An example of the configuration diagram of the open phase voltage detection means is shown in FIG. When detecting the terminal voltage of the motor 6, for example, the open phase voltage detection means 60 is used. In many cases, since the terminal voltage of the motor 6 exceeds the power supply voltage (for example, 5V or 3.3V) of the control unit, voltage dividing resistors (61 and 62) are used. Thereafter, the buffer circuit 63 is inserted for the purpose of amplification by an operational amplifier or protection of the control unit. Of course, the terminal voltage of the motor 6 may be directly input to the control unit 2.

<Details of each component>
Details of each component will be described below. First, the operation of the position estimation means 40 for 120 degrees and the operation of the position estimation means 41 for 180 degrees will be described respectively, and then the operation of the voltage command value calculation means 34 will be described. Subsequently, a problem in switching between two drive states, in other words, switching between two energization methods (120-degree energization and 180-degree energization) will be described.

<120 degree energization>
FIG. 23 shows a configuration example of the 120-degree position estimating means 40 that realizes the following description.

  When the motor 6 is driven by energization at 120 degrees, two phases to be energized among the three-phase windings of the motor 6 are selected and a pulse voltage is applied to generate torque. There are six possible combinations of two phases to be energized, and these are defined as energization mode 1 to energization mode 6, respectively.

  FIG. 9 shows a schematic diagram when a voltage is applied to the two phases of the motor. FIG. 9A shows an energization mode (corresponding to an energization mode 3 described later) in which the V phase is energized to the W phase, and FIG. 9B is energized from the W phase to the V phase. It is a figure which shows the electricity supply mode of a state.

  On the other hand, the electromotive voltage that appears in the non-energized phase (the U phase in FIG. 10) when the rotational angle position of the rotor is changed by one electrical angle cycle is as shown in FIG. FIG. 10 is an example of an electromotive voltage characteristic diagram of the non-conduction phase. It can be seen that the U-phase electromotive voltage (U-phase terminal voltage) varies depending on the rotation angle position.

  In this electromotive voltage, the difference in the rate of change of magnetic flux generated between the V phase and the W phase is observed as a voltage in the U phase that is a non-conduction phase, and is different from the speed electromotive voltage. Differentiating from the speed electromotive force, it is called an open phase electromotive force.

  In FIG. 10, the open phase electromotive voltage when applying a positive pulse indicated by a solid line and the open phase electromotive voltage when applying a negative pulse indicated by a broken line are both larger than the speed induced voltage Emu. The speed electromotive voltage is an electromotive voltage that changes in proportion to the rotational speed of the rotor as the name suggests. Therefore, the magnitude relationship between the speed electromotive voltage in the low speed region and the electromotive voltage of the non-conduction phase is the relationship shown in FIG.

  Therefore, if this open-phase electromotive voltage is detected, a relatively large rotor position signal can be obtained when the rotational speed of the motor 6 ranges from near zero speed to a low speed range.

  FIG. 11 shows an open-phase electromotive voltage characteristic with respect to the rotational angle position θd of the rotor when the U phase, the V phase, and the W phase are non-energized phases, the gate signal of the switching element constituting the power converter 2, and the motor 6 The rotational angle position θd of the rotor, the energization mode, and the switching phase relationship are shown.

  FIG. 11 shows an example of the open phase electromotive force characteristics with respect to the rotation angle position. As can be seen from FIG. 11, the voltage pulses shown in FIGS. 9A and 9B are applied during the normal operation of the 120-degree conduction method. In the energization mode 3, the state shown in FIG. Two phases to be energized are switched every 60 degrees of electrical angle according to the mode rotation angle position θd. That is, the non-energized phase is also switched sequentially.

  In FIG. 11, in the states of FIGS. 9A and 9B, the energization mode corresponds to the energization mode 3 or the energization mode 6. In the energization mode 3 or the energization mode 6, since the U phase is a non-energization phase, the open-phase electromotive voltage can be detected as indicated by the thick line shown in the U-phase electromotive voltage waveform. That is, as the rotation angle position θd increases, it is possible to detect an open phase electromotive voltage that decreases in the minus direction in the energization mode 3 and increases in the plus direction in the energization mode 6.

  Similarly, in energization mode 2 and energization mode 5, a V-phase electromotive voltage waveform can be detected, and in energization mode 1 and energization mode 4, a W-phase electromotive voltage waveform can be detected.

  FIG. 12 is an example of a relationship diagram between the open phase electromotive voltage and the reference voltage with respect to the rotation angle position. FIG. 12 shows the relationship among the energization mode, the non-energization phase, the open phase electromotive voltage of the non-energization phase corresponding to the energization mode, and the reference voltage with respect to the rotation angle position θd. Each time the energization mode is switched, the open phase electromotive voltage of the non-energized phase has a waveform that repeats an increase and decrease in positive and negative, respectively. Therefore, reference voltages (Vhp, Vhn) serving as threshold values are set on the positive side and the negative side, respectively, and the rotational angle position θd can be estimated from the magnitude relationship between the reference voltage and the open-phase electromotive voltage of the non-conduction phase. A trigger signal for switching the energization mode is generated.

  In other words, the reference voltage is regarded as a value representing a predetermined phase for switching the energization mode, and when the open phase electromotive voltage of the non-energized phase that detects this is exceeded, a mode switching trigger signal is generated at that time, and the energization mode is changed in order. Switch.

  The operation for switching the energization mode is realized by the mode switching trigger generator 51. The non-energized phase potential selector 52 selects the non-energized phase according to the energized mode and detects the open phase electromotive voltage of the selected phase. doing.

  The reference level switch 53 shown in FIGS. 13 and 23 selects and outputs the positive reference voltage Vhp and the negative reference voltage Vhn by the changeover switch 113 in accordance with the energization mode command. In other words, the positive reference voltage Vhp111 is output in the energization modes 2, 4, and 6, and the negative reference voltage Vhn112 is output in the energization modes 1, 3, and 5.

  The open-phase electromotive voltage according to the energization mode and the selected positive reference voltage Vhp or negative reference voltage Vhn are input as a threshold value to the comparator 54 to compare the values, and the electromotive voltage of the non-energized phase becomes the threshold value. When it reaches, a mode switching trigger signal is generated. The energization mode switch 55 receives a mode switching trigger signal, advances the energization mode in the forward rotation direction according to the mode switching trigger signal, and outputs the energization mode.

  The phase converter 56 inputs information on the energization mode (energization mode 1 to energization mode 6) and outputs an electrical angle phase (rotation angle position θd). In 120-degree energization, the rotational angle position for each electrical angle of 60 degrees may be detected. For example, the phase having the relationship shown in FIG. 24 is output from the energization mode.

<Phase determination method in each energization mode at 120 degrees energization>
Employing the phase in the relationship of FIG. 24 is suitable for switching the energization method. Considering the purpose of this embodiment, it is preferable that the drive signal generation method is the same.

  Considering the three-phase sinusoidal voltage command value, the electrical angle is 0 degrees, 60 degrees, 120 degrees, 180 degrees, and 240 degrees, the intermediate phase voltage is zero, and the absolute values of the maximum and minimum phases are It is the same position. When these voltage command values are used in the PWM carrier signal generation method shown in FIG. 21 (that is, the same drive signal generation method as the 180-degree energization method), a drive signal for the 120-degree energization method can be obtained.

  A voltage command value, an energization method switching command signal, and an energization mode command are input to the drive method switch 45. When driving by the 120-degree energization method, the drive signal of the non-energized phase is output as inactive for both the upper and lower arms according to the energization mode. When driving by the 180-degree energization method, the drive method switch 45 may output the input voltage command value as it is. In the 120-degree energization method, a voltage is applied to the maximum phase and the minimum phase. Therefore, the non-energized phase corresponding to the energization mode is an intermediate phase. By making both the upper and lower arms of the intermediate phase inactive, a voltage similar to the complementary switching drive signal of FIG. 7 is applied to the motor.

  Thus, by determining the phase in each energization mode as shown in FIG. 24, a drive signal in the 120-degree energization method can be generated using the same drive signal generation method as in the 180-degree energization method. . Since the same drive signal generation method is used, a shock at the time of switching due to the drive signal generation method can be eliminated. Therefore, this is a method suitable for switching the energization method.

  The speed converter 57 counts the time during which one energization mode is continued, for example, at the interrupt timing of the peak or valley of the triangular wave carrier signal, and calculates the speed ω1_120 from the count value by the following equation.

  Here, N_pwm is the count number counted at the crest or trough interrupt timing of the triangular wave carrier signal, and T_count_smpl is the counting period. The reason for multiplying by 6 is to obtain a speed corresponding to one electrical angle cycle.

  As described above, the open-phase electromotive voltage is different from the speed electromotive voltage, and can be detected even when the motor is stopped or rotating at an extremely low speed. Therefore, position sensorless driving is possible when the rotational speed of the motor 6 ranges from near zero speed to a low speed range. Thus, by detecting the open phase electromotive voltage of the non-energized phase, the rotor position can be accurately detected even when the motor 6 is stopped or at extremely low speed. Based on this, the rotational speed is also obtained.

  The basic operation of the 120-degree position estimating means 40 has been described above.

<180 degree energization>
However, as the rotational speed of the motor 6 increases, the speed electromotive force becomes more dominant than the open phase electromotive voltage of the non-conduction phase. That is, it is more accurate to detect the rotor position information and the rotational speed based on the speed electromotive voltage. Therefore, it is preferable to drive the motor 6 by energization at 180 degrees in the middle and high speed range.

  In order to drive the motor 6 by energization at 180 degrees, it is preferable to control by the dc-qc axis (rotational coordinate system) as described above. Although it is necessary to perform coordinate conversion from the three-phase AC axis in order to control on the rotating coordinates, there is an advantage that voltage and current can be handled as a DC amount on the rotating coordinates.

  Therefore, using the estimated magnetic pole position θdc, the three-phase AC axis motor current detection value 122 detected by the current detection means 7 is coordinate-converted to the dc-qc axis, and the d axis and q axis current detection values (Idc and Iqc) are converted. ) Similarly, using the estimated magnetic pole position θdc, the voltage command value on the dc-qc axis generated by the voltage command value generator 3 described later is coordinate-converted into a three-phase AC voltage command value.

  Next, the operation of the 180 degree position estimating means 41 will be described. FIG. 15 is an example of a configuration diagram of the 180 ° position estimating means 41. The 180 degree position estimation means 41 is mainly composed of an axis error calculator 10, a PLL controller 13, an integrator 15, and the like.

  The 180 degree position estimating means 41 of this embodiment is based on the calculated value of the axis error Δθc. The axis error calculator 10 receives a current detection value (Idc and Iqc) on the control axis and a voltage command value (Vd * and Vq *) described later, and an axis error between the real axis and the control axis by the following equation: Δθc is output.

  The PLL controller 13 outputs the inverter frequency command value ω1 so that the shaft error Δθc becomes the shaft error command value Δθ * (usually zero). The difference between the axis error command value Δθ * and the axis error Δθc is obtained by the subtractor 17a, and the result obtained by multiplying this by the proportional gain Kp_pll by the multiplier 18a is multiplied by the integral gain Ki_pll by the multiplier 18b. The adder 16a adds the calculation results obtained by integration and integration control at 15b, and outputs an inverter frequency command value ω1_180.

  The inverter frequency command value ω1_180 corresponds to the motor speed because the shaft error Δθc is zero in the steady state and the control shaft position and the rotor position are basically synchronized in the permanent magnet synchronous motor. To do.

  The rotational angle position θd (electrical angle phase) of the rotor can be obtained by integrating the speed. Therefore, the output of the integrator 15a becomes the rotation angle position θd_180.

  Next, the operation of the voltage command value calculation means 34 will be described. FIG. 14 is an example of a configuration diagram of the voltage command value calculation means 34. The voltage command value calculation means 34 includes, for example, a speed controller 14, a current controller 12, an energization method changeover switch 59, a voltage command value generator 3, a dq / 3φ converter 4, and the like. .

  The energization method is switched by an energization method switch 59. In FIG. 14, there are a plurality of energization method selector switches 59, all of which are switched to the same contact at the same timing.

  For convenience of explanation, the operation at the 180-degree energization drive will be described first. In the 180-degree energization drive, the multiple energization method changeover switch 59 in FIG.

  The voltage command value generator 3 includes a d-axis and q-axis current command values (Id * and Iq *) obtained from a speed controller 14 and a current controller 12 described later, a rotational angular speed command value ω *, or an inverter frequency described later. The command value ω1 is input to the voltage command value generator 3 and a vector calculation is performed as in the following equation to obtain a d-axis voltage command value Vd * and a q-axis voltage command value Vq *.

  Here, R is a winding resistance value of the motor 6, Ld is a d-axis inductance, Lq is a q-axis inductance, and Ke is an induced voltage constant.

  Control for driving the motor as described above is generally called vector control, and the current flowing through the motor is calculated by separating the current component into a field component and a torque component, so that the motor current phase becomes a predetermined phase. Control the phase and magnitude of There are several types of vector control configurations, for example, the configuration described in JP-A-2005-39912. Using this, for example, the configuration shown in FIG.

  The motor 6 of the present embodiment is a non-salient permanent magnet motor. That is, the d-axis and q-axis inductance values are the same. That is, the reluctance torque generated due to the difference in inductance between the d-axis and the q-axis is not considered. Therefore, the torque generated by the motor 6 is proportional to the current flowing through the q axis. Therefore, in this embodiment, the d-axis current command value Id * is set to zero. In the case of a salient pole motor (a motor having different d-axis and q-axis inductance values), reluctance torque is generated due to the difference in inductance between the d-axis and the q-axis in addition to the torque due to the q-axis current. Therefore, the same torque can be generated with a smaller q-axis current by setting the d-axis current command value Id * in consideration of the reluctance torque. In this case, an effect of improving efficiency can be obtained.

<Speed controller>
Although the q-axis current command value may be obtained from a host control system or the like, FIG. 14 shows a configuration in which the q-axis current command value is obtained using a speed controller in order to improve followability to the speed command value. .

  A configuration example of the speed controller 14 is shown in FIG. The difference between the frequency command value ω * and the inverter frequency command value ω1 is obtained by the subtractor 17b, and is multiplied by the proportional gain Kp_asr by the multiplier 18c, and the result of proportional control is multiplied by the integral gain Ki_asr by the multiplier 18d. The adder 16b adds the calculation results integrated and controlled by 15c, and outputs a q-axis current command value Iq *.

<Current controller>
FIG. 17 is an example of a configuration diagram of the current controller. Current control is performed to improve followability to the d-axis and q-axis current command values. Differences between the d-axis and q-axis current values (Id * and Iq *) and the detected d-axis and q-axis current values are obtained by subtracters (17c and 17d), respectively, and proportional gains are obtained by multipliers (18e and 18f). Multiply (Kp_dacr and Kp_qdacr) by the proportional control result and the multiplier (18g and 18h) multiply the integral gain (Ki_dacr and Ki_qacr) by the integrator (15d and 15e) and add the integral control result The second d-axis and q-axis current command values (Id ** and Iq **) are output by the adders (16c and 16d).

<Calculation of voltage command value for energization at 120 degrees>
Next, the operation during 120-degree energization driving will be described. In the 120-degree energization drive, the plurality of energization method changeover switches 59 in FIG.

  In the present embodiment, an example in which a voltage command value is output in the same manner during 120-degree energization driving and 180-degree energization driving is shown. Of course, the 120-degree energization drive can be changed to the 180-degree energization drive. For example, the current command value input to the voltage command value generator 3 can be changed between 120 degree energization driving and 180 degree energization driving. That is, the second d-axis and q-axis current command values (Id ** and Iq **) are also provided with an energization method changeover switch 59, and the current command values (Id ** and Iq **) during 120-degree energization drive. Current command values (Id * _120 and Iq * _120 *) input from a host control or the like (not shown) are used. When using the current command value input from the host control or the like, the number of multipliers and integrators is reduced, so that there is an effect that the calculation load of the control unit 2 can be reduced.

  As the simplest method, the d-axis and q-axis current command values may be set to zero, only predetermined speed command values may be given, and the voltage command value may be fixed as in the following equation.

  The dq / 3φ converter 4 receives the d-axis and q-axis voltage command values (Vd * and Vq *) output from the voltage command value generator 3 and the rotation angle position, and receives a three-phase voltage command value (Vu *). , Vv *, Vw *) are output.

  Normally, the frequency command value ω * given by the host control system or the like has a very long change period compared to the inverter frequency command value ω1, and therefore may be regarded as a constant value during one rotation of the motor. Therefore, the motor is rotated at a substantially constant frequency by the speed controller. At this time, the estimated magnetic pole position θdc obtained by integrating the inverter frequency command value ω1 increases substantially uniformly.

  The basic operation of the voltage command value calculation unit 34 has been described above.

<Energization method switching>
When the state quantity (position, speed, torque, etc.) of the motor 6 is controlled, it is suitable to use information with high sensitivity or information that changes linearly with respect to a change in the state quantity.

  As described above, the open phase electromotive voltage of the non-energized phase can be detected even when the motor is stopped or rotating at an extremely low speed. On the other hand, since the speed electromotive force is an electromotive voltage proportional to the rotational speed of the motor, the speed electromotive force increases as the rotational speed increases. Is more dominant.

  From this, when the motor position is detected and the motor state quantity (position, speed, torque, etc.) is controlled in the high speed range from when the motor is stopped, the control is performed based on the open-phase electromotive voltage 120 degrees. By combining the energization method and the 180-degree energization method that is controlled based on the speed electromotive voltage, highly accurate control can be realized.

  Here, as an example of a value for determining energization method switching, a frequency command value ω * (corresponding to a motor rotation speed command) given from a host control system or the like is used. For example, when the speed electromotive force becomes sufficiently large in advance and reaches a frequency command value that can accurately detect the speed electromotive voltage (approximately 10 to 20% of the rated speed is a guide), control is performed based on the open-phase electromotive voltage 120 degrees. Switching from the energization method to the 180-degree energization method controlled based on the speed electromotive force.

  A basic operation when starting the motor 6 will be described, and then a problem in the case of using a compression mechanism in which the load torque varies periodically will be described.

  FIG. 20 is an example of an activation sequence showing transition of each operation mode when the motor 6 is activated. The activation sequence is divided into three sections A to C.

  In section A, a predetermined voltage command value is applied at a frequency of zero by a 120-degree energization method. That is, a direct current flows. Thereby, the rotor is positioned at a certain position.

  After the positioning is completed, the period shifts to a period B, and the rotation speed command (one-dot chain line in the top graph of FIG. 20) is increased at a constant rate. By sequentially changing the energization mode by the above-described method, the motor is accelerated and the rotation speed is increased. When the rotational speed command or the rotational speed of the motor (solid line in the top graph of FIG. 20) reaches N1, the energization method is switched to the 180-degree energization method.

  When switching the energization method, there are times when current jumps or speed fluctuations occur as shown in FIG. If the current jump is large, the motor may be stopped by the overcurrent protection circuit, or the switching element 22 and other electrical components may be damaged. Even if the motor does not stop or break down, the torque generated by the motor changes suddenly when the energization method is switched, causing sudden acceleration / deceleration and the resulting vibration and unpleasant noise.

  The example of the activation sequence shown in FIG. 20 is a schematic diagram showing the relationship between the rotational speed and the energization method. Actually, each value changes according to the load (load torque) of the motor 6, the response frequency (proportional gain or integral gain) of the PLL controller 13, the current controller 12, and the speed controller 14. Therefore, the behavior when the load torque fluctuates at the time of switching the energization method will be described using FIG. 27 and FIG.

  FIG. 27 shows a case where the load torque at the time of switching the energization method is small. At this time, there is no change in the generated torque and the load torque of the motor 6 before and after switching the energization method, whereby each control system can be switched stably without being disturbed.

  FIG. 28 shows a case where the load torque is large when the energization method is switched. When the load torque changes suddenly and increases, the motor once decelerates according to the response frequency of the speed controller. In order to follow the rotational speed command, a larger current is required. In the worst case, the overcurrent protection judgment value may be exceeded and the motor may stop.

  In the present embodiment, the position estimation method is switched simultaneously with switching the energization method. Therefore, if the outputs of the 120-degree position estimating means and the 180-degree position estimating means are different, this is one of the causes of current jumping and speed fluctuation.

  The speed controller 14 outputs a q-axis current command value proportional to the torque generated by the motor 6, but the response frequency of the speed controller is limited. In the speed controller, the lowest response frequency is set so as not to be affected by the PLL controller 13 and the current controller 12 or to oscillate. Among the three controllers, the highest response frequency is restricted by the processing capability of the control unit. Therefore, there is an upper limit value for the response frequency of the speed controller. This is also one of the causes of current jumps and speed fluctuations when switching the energization method, and is also a problem.

  In order to solve such problems, when switching the energization method from the 120-degree energization method to the 180-degree energization method, switching shockless that does not cause a current jump, torque shock due to discontinuity of motor generated torque, speed fluctuation, etc. It is one of the objects to provide a motor control device that realizes the above.

  One of the causes of current jumps when switching the energization method is that the initial value (for example, the value of the integral term) of each control system (speed controller, current controller, etc.) at the time of switching the energization method is inappropriate. Is set to be unstable.

  It is assumed that the load of the motor control device of the present embodiment and the drive device, refrigerator, and air conditioner using the motor control device has some periodic load fluctuation. As shown in FIG. 6, since the compressor has a large periodic load fluctuation, there is a timing at which the load temporarily increases due to the periodic load fluctuation even if the average load torque for one cycle of the mechanical angle is small. . When this timing and the timing for switching the energization method overlap, there is a high possibility that the activation will fail. Therefore, one of the purposes is to start the motor 6 stably without failing to start even when the periodic load fluctuation is large.

  In the present embodiment, the piston 501 of the compression mechanism unit 500 is described as an example of a reciprocating type that moves linearly. However, as another method of the compression mechanism, a rotary type that compresses by rotating the piston, a spiral type, or the like There are scroll types that consist of a swirling wing. Although the characteristic of periodic load fluctuation varies depending on the compression method, there is load fluctuation caused by the compression process in any compression method. For this reason, there is a risk of start-up failure due to the overlap of the timing at which the load temporarily increases due to periodic load fluctuations and the switching timing of the energization method.

Therefore, one of the purposes is to provide a solution that can be applied to any compression method.
The variation of the load torque varies depending on the type of the compressor, and even in the same compressor, it varies depending on the operation conditions (pressure of the suction port and discharge port, the temperature of the compressor, etc.) and the rotational speed of the motor.

  For this reason, it is better to determine the initial value from actual load fluctuations than to determine the initial value of each control system at the time of switching the energization method in advance, which is one of the purposes.

  Depending on the energization method, the configuration until the voltage command value is output may be different. Therefore, it is one of the purposes to determine the initial value of each control system at the time of switching the energization method in consideration that the configuration of the voltage command value varies depending on the energization method.

  Therefore, by determining the initial value of each control system in consideration of the influence of the load torque, it becomes possible to drive stably before and after switching the energization method. Further, by paying attention to the configuration of the voltage command value, it becomes possible to drive stably.

  FIG. 26 is an example of the measurement result of the current detection value when the motor is driven at approximately 667 rpm. In the figure, the detected q-axis current value (dotted line) detected by the controller 2 and the detected q-axis current value (solid line) after the first-order lag filter processing are shown. When attention is paid to the q-axis current detection value (dotted line) in FIG. 26, both change at a period of 90 ms. This period is equal to one mechanical angle period (90 ms), and from this it can be seen that the change in current coincides with the load fluctuation. That is, it means that a change in load can be detected from a change in current.

  Note that the q-axis current detection value (dotted line) in FIG. 26 has a comb-like waveform, which is due to the change in the energization mode during driving in the 120-degree energization method.

  When the q-axis current detection value (dotted line) in FIG. 26 is compared with the example of the change in the load torque shown in FIG. 6, the waveforms of both are similar. When the process of the compression mechanism of the present embodiment is described in the current waveform of FIG. 26, the period during which the current increases corresponds to the compression process, and the period during which the current decreases thereafter corresponds to the discharge and suction processes. This is because in the compression process, a large load torque is required to compress the refrigerant, and for this purpose, a q-axis current is supplied to increase the torque of the motor.

<Energization method switching judgment device>
The initial value calculation means 35, which is one of means for realizing the above object, will be described.

  An example of a configuration diagram of the initial value calculating means 35 is shown in FIG. The initial value calculation means 35 includes a primary delay filter 73, an initial value calculation means 74, and the like. The initial value calculation means 35 inputs an energization method switching command and a q-axis current detection value, and outputs initial values of each control system.

<Initial value calculation method>
The initial value calculation means 74 receives the input q-axis current detection value (Iqc) and the q-axis current detection value after the first-order lag filter processing when the energization method switching command is input, that is, at the timing of switching the energization method. (Iqc_fil) is compared, and the larger value is output as the initial value of the speed controller 14 and the current controller 12.

  The load torque waveforms in FIGS. 27 and 28 show the average load torque indicated by a dotted line. The q-axis current detection value (Iqc_fil) after the first-order lag filter processing corresponds to this average load torque.

  In the case of FIG. 27, consider a case where the initial values output from the initial value calculation means 74 are input to the initial values of the speed controller 14 and the current controller 12. At this time, since the q-axis current detection value (Iqc_fil) after the first-order lag filter processing is larger than the q-axis current detection value (Iqc), the q-axis current detection value (Iqc_fil) after the first-order lag filter processing. ) Is the initial value. If it carries out like this, the rotational speed of a motor will go up from the continuous line shown in FIG. However, it can be said that there is no adverse effect in consideration of the fact that the rotational speed command is rising, the load torque increases after a while, and the like.

  On the other hand, consider the case of FIG. In this case, since the q-axis current detection value (Iqc) is larger than the q-axis current detection value (Iqc_fil) after the first-order lag filter processing, the q-axis current detection value (Iqc) is set as the initial value. Thus, the example at the time of changing the initial value of the speed controller 14 and the current controller 12 at the time of energization system switching is shown in FIG. As can be seen from FIG. 29, by changing the initial values of the speed controller 14 and the current controller 12, the voltage command value becomes discontinuous at the timing when the energization method is switched. However, since the motor torque corresponding to the load torque can be generated, the rotational speed of the motor once decelerated at the time of switching the energization method in FIG. 27 is not decelerated, and there is no current jump or speed fluctuation, and the motor is driven stably. Will be able to.

  As described above, by setting the initial value of the controller when switching from the 120-degree energization method to the 180-degree energization method, the sum of the currents flowing to the motor at the time of shifting to 180-degree energization is 120 degrees energization. It will be the same as or increased with the sum of the currents flowing in the electric motor, so that it can be driven stably.

<Method for determining cutoff frequency of first-order lag filter>
The primary delay filter 73 desirably outputs a q-axis current value corresponding to a steady load torque. The reason is as follows. For example, in FIG. 26, the energization method is switched at 45 ms. At this time, the q-axis current detection value (Iqc_fil) after the first-order lag filter processing is larger than the q-axis current detection value (Iqc). However, since it is clear that the load torque increases immediately after switching the energization method, the q-axis current corresponding to the steady load torque is used as the initial value of the speed controller 14 and the current controller 12 when the energization method is switched. The value is an appropriate value.

  In order to output a q-axis current value corresponding to a steady load torque, the cutoff frequency of the primary delay filter 73 is preferably low. If the cut-off frequency is lowered, there is a problem that it takes a longer time to converge. Therefore, as an upper limit of the cutoff frequency of the primary delay filter 73, 1/4 of the main fluctuation component of the load fluctuation or 1/4 of the target (command) frequency at the time of switching the energization method is used as a guide. Alternatively, the response frequency of the speed controller 14 or 1/4 of the PLL controller is used as a guide.

  The step response of the first-order lag filter is as follows.

  Here, y (t) is the output of the primary delay filter, e is the natural logarithm, t is the elapsed time, τ is the time constant of the primary delay filter, and fc is the cutoff frequency of the primary delay filter.

  From Equation 5, the output of the filter is 0.632 when the time constant elapses, and becomes 0.98 or more when the time 5 times the time constant elapses. It can be considered that there is no influence of step input after 5 times the time constant. That is, the cut-off frequency of the first-order lag filter only needs to have a difference of 5 times or more of the frequency whose influence is desired to be removed. Therefore, as described above, 1/4 of the main fluctuation component of the load fluctuation or 1/4 of the target (command) frequency when switching the energization method is used as a guide. Alternatively, the response frequency of the speed controller 14 or 1/4 of the PLL controller may be used as a guide.

  However, the cutoff frequency of the first-order lag filter 73 is not necessarily set to the same value as the above-mentioned standard. This is because the load of the motor control device of the present application and the drive device, refrigerator, and air conditioner using the motor control device is premised on having some periodic load fluctuation. When there is a load fluctuation, a speed fluctuation is generated due to restrictions of the control unit 2 or the like. Therefore, when determining the cutoff frequency of the first-order lag filter 73, it is necessary to consider the speed fluctuation.

  For example, when there is one load fluctuation in one mechanical angle cycle (cycle in which the rotor makes one rotation), the cutoff frequency of the first-order lag filter 73 is set in the range from the minimum frequency to the maximum frequency in one mechanical angle cycle. The effect of the present application can be obtained.

  In the 120-degree energization method, the speed calculation is performed every 60 degrees, so that it is driven near the energization method switching, the minimum time or the maximum time of each energization mode during one rotation of the mechanical angle is obtained in advance, and the frequency calculated therefrom is calculated. The cutoff frequency may be set.

  As described above, by using the initial value calculation means 35, it is possible to provide a motor control device that realizes switching shockless in which current jumps, torque shock due to discontinuity of motor generated torque, speed fluctuation, and the like do not occur. .

  Since the initial value calculating means 35 described in the present embodiment is composed of a first-order lag filter 73 and an initial value calculating means 74 composed of a magnitude comparator, there is an effect that it can be realized very easily.

  The suction pressure Ps and the discharge pressure Pd in one step of the compressor of the motor 6 vary depending on the state of the system (for example, the refrigeration cycle) connected to the compressor, but load torque fluctuations in one step occur. Therefore, the q-axis current value corresponding to the steady load torque is obtained by the first order lag filter, compared with the q-axis current detection value, and the larger one is set as the initial value of the controller. It can be applied to the motor control apparatus.

  Needless to say, the present invention can be applied not only to the compressor but also to a motor control device having a load torque characteristic that fluctuates periodically, and a driving device, a refrigerator, and an air conditioner using the motor control device.

  In this embodiment, an example of a refrigerator and an air conditioner using a motor control device will be described.

  In addition, description is abbreviate | omitted about the part which has the same function as the structure to which the same code | symbol shown in Example 1 was attached | subjected.

  FIG. 30 is an example of a configuration diagram illustrating a refrigerator as an example of a refrigerator and an air conditioner using the motor control device according to the second embodiment.

  As shown in FIG. 30, the refrigerator 301 includes a heat exchanger 302, a blower 303, a compressor 304, a compressor driving motor 305, and the like. The refrigerator control device 306 includes an internal control device 307 and a motor control device 1 that control a blower, an internal light, and the like based on various sensor information.

  In a refrigerator, the amount of heat leakage from which heat in the refrigerator leaks to the outside air due to a vacuum heat insulating material or the like is very small. Therefore, once the interior is cooled, a small cooling power (ability to cool the interior) is sufficient thereafter. That is, the compressor 304 is operated at a low rotational speed. On the other hand, if you want to cool the interior quickly by turning on the power for the first time, or if you want to cool the interior quickly because hot food is put in the interior, increase the rotation speed of the compressor 304 and increase the cooling power. It is necessary to secure. That is, in the refrigerator, there is a problem that the variation range of the steady load torque is large in addition to the load fluctuation when the compressor 304 rotates.

  Since the interior of the compressor used in the refrigerator and the air conditioner is at a high temperature and a high pressure, it is difficult to install a position sensor or the like that detects the rotational angle position of the compressor driving motor. When the motor for driving the compressor is driven, the rotational angle position information of the rotor is obtained by position sensorless control that outputs the estimated position of the motor from the current flowing through the motor and the applied voltage of the motor.

  As described above, since the speed electromotive force is small at low speed, position estimation becomes difficult. On the other hand, the open-phase electromotive voltage can be detected even when the motor is stopped or rotating at an extremely low speed, unlike the speed electromotive voltage. Therefore, when the rotational speed of the motor 6 is in the low speed range from near zero speed, position sensorless control based on the open phase electromotive force is performed. Here, the term “low speed” means a speed at which the speed electromotive voltage is about 10% or less of the DC voltage source 20 of the power conversion circuit 5.

  In this embodiment, a 120-degree energization method of position estimation based on the open phase electromotive voltage is used. When driving by the 120-degree energization method, the speed of the motor is obtained by the speed converter 57 in FIG. As can be seen from Equation 3, when the motor rotation speed increases, the count number (N_pwm) counted at the peak or valley interrupt timing of the triangular wave carrier signal decreases.

  For example, FIG. 31 shows an example of a calculation result of the speed ω1_120 when the PWM carrier frequency is 2 kHz and the elapsed time of the energization mode is counted at each peak timing of the triangular wave carrier signal. When the count number is about 20 counts, the speed difference of 1 count is about 1 Hz, whereas when the count number is about 5 counts, the speed difference of 1 count becomes several tens of Hz. That is, if the speed difference due to one count is excessive with respect to the actual speed fluctuation, the control system is disturbed, and the speed controller 14 and the PLL controller 13 may be vibrated or oscillate. In particular, when the response frequency of speed control by proportional-integral control is high, there is a problem that the speed of the motor 6 becomes unstable.

  Therefore, even if the speed control by the proportional integral control that is generally used is not performed, the load torque can be applied even in the application destination that follows the speed command value given from the host controller and the steady load torque greatly varies. One of the objects is to provide a motor control device capable of generating a desired torque according to the above, and a refrigerator and an air conditioner using the motor control device.

  Many examples of the configuration diagram of the motor control device in the present embodiment are the same as those in the first embodiment, but the configuration of the voltage command value calculation means 34 is different. FIG. 32 is an example of a configuration diagram of the voltage command value calculation means 34a in the present embodiment. A characteristic point different from the first embodiment is that the q-axis current detection value is input to the delay element 75 and the q-axis current command value at the time of 120-degree energization driving is output. That is, during 120-degree energization driving, there is no speed controller based on proportional-integral control or the like.

  When the load of the motor 6 is large, the q-axis current detection value is large, and when the load is small, the q-axis current detection value is small. Therefore, using the characteristics of the motor 6, in the configuration of this embodiment, the q-axis current detection value is input to the delay element 75 to obtain the q-axis current command value (Iq * _120). As a configuration example of the delay element 75, for example, there is a configuration of the following equation.

  Here, T_120 is a time constant, and s is a Laplace operator.

  The delay element may be constituted by, for example, a moving average.

  The initial value calculation means 35 in the present embodiment will be described.

  The example of the configuration diagram of the initial value calculating means 35 is the same as the configuration shown in FIG. 19, but the input values are different. The q-axis current detection value and the q-axis current command value (Iq * _120) are input to the initial value calculation means 35 of the present embodiment.

  The initial value calculation means 74 receives the input q-axis current detection value (Iqc_fil) after the first-order lag filter processing and the q-axis current command value when the energization method switching command is input, that is, at the timing of switching the energization method. (Iq * _120) is compared, and the larger value is output as the initial value of the speed controller 14 and the current controller 12.

  The q-axis current command value (Iq * _120) is also a result of inputting the q-axis current detection value to the delay element 75. For example, the filter time constant is equivalent to the electric time constant of the motor 6. This is because the applied current of the motor 6 changes according to the electrical time constant. That is, it changes according to the load torque fluctuation. On the other hand, the time constant of the q-axis current detection value (Iqc_fil) after the first-order lag filter processing is, for example, 100 ms in order to detect a steady load, and the time for obtaining the q-axis current command value (Iq * _120). Make it longer than a constant. Therefore, the values to be obtained are different between the two. The purpose of the present application is to detect and compare the q-axis current value corresponding to the steady load torque and the q-axis current value corresponding to the instantaneous load torque because the calculated values are different. Can be achieved.

  In this way, by using the voltage command value calculation means 34a, even when a speed calculation error is large, the q-axis current command value is output using the q-axis current detection value, so that the speed control by the speed controller can be performed. Can be controlled according to the speed command value, and the motor 6 can be stably started even when the steady load torque fluctuates greatly.

According to the method of this embodiment, there is no need to worry about speed calculation accuracy during 120-degree energization drive.
That is, this method is suitable for a case where the PWM carrier frequency must be driven to a certain speed while being low.

  On the other hand, when the PWM carrier frequency is high, the count value for speed calculation may exceed the storage area, that is, overflow, but there is no problem if the configuration of this embodiment is used, and the storage area is reduced. There is also an effect that can be done.

  In the voltage command value calculation means 34a of the present embodiment, the configuration without the current controller has been described, but there is no problem even if the current controller is added, and the same effect can be obtained.

  In the present embodiment, a method suitable for a configuration in which the control method is switched during acceleration in the motor control device having the speed controller 14 described above, and a drive device, a refrigerator, and an air conditioner using the speed controller 14 will be described.

  As described above, the speed controller 14 outputs a q-axis current command value proportional to the torque generated by the motor 6, but the response frequency of the speed controller is limited. In the speed controller, the lowest response frequency is set so as not to be affected by the PLL controller 13 and the current controller 12 or to oscillate. Among the three controllers, the highest response frequency is restricted by the processing capability of the control unit. Therefore, as a matter of course, the response frequency of the speed controller has an upper limit value. This is also one of the causes of current jumps and speed fluctuations when switching the energization method, and is also a problem.

  When the response frequency is low, there is a problem that even if the initial value is set to an appropriate value, the speed is reduced due to an increase in load torque due to subsequent load fluctuations.

  Therefore, in this embodiment, even in a configuration in which the response frequency of the speed controller is restricted, a motor control device capable of switching the control method during acceleration, and a drive device, a refrigerator using the same, Providing an air conditioner is one of the purposes.

  Description will be made by paying attention to the operation of the speed controller 14 shown in FIGS. In order to accelerate the motor 6, that is, increase the generated torque, the q-axis current command value proportional to the motor torque may be increased.

  In order to increase the q-axis current command value, the input of the speed controller may be positive. That is, it is sufficient that the rotational angular velocity command value ω * is larger than the inverter frequency command value ω1.

  On the other hand, as described above, when the rotational speed of the motor 6 increases, it becomes more accurate to detect the rotor position information and the rotational speed based on the speed electromotive voltage. Therefore, it is preferable to switch to a configuration based on the speed electromotive force at a predetermined rotational speed or higher.

  Therefore, the energization method switching determination of the energization method switching determiner is as follows.

  Here, ω_judge is a frequency at which the energization method switching determination is started. When the rotation frequency (inverter frequency command value ω1) is less than the energization method switching determination start frequency ω_judge, the effect of shortening the processing time can be obtained by not performing the energization method switching determination.

  An example of a configuration diagram of the energization method switching determination unit 30 in the present embodiment is shown in FIG.

  Even when there is a restriction on the response frequency of the speed controller (when the response of the speed controller cannot be increased so much), the q Since the shaft current command value can be maintained in the increasing direction, the acceleration can be continued.

  In the present embodiment, the configuration for switching from the 120-degree energization method to the 180-degree energization method has been described. However, the content of the present embodiment is not limited to this configuration, and a motor control device having speed control means and a drive using the same In the apparatus, the refrigerator, and the air conditioner, the present invention can be applied to a configuration in which the control method is switched while the motor 6 is accelerated, and the same effect can be obtained. For example, position feedback is not performed, and driving is performed up to a predetermined rotational speed by a technique called synchronous operation in which a voltage command value is determined from a predetermined current command value and speed command value, and then the control method is switched to a control method having speed control means. The present invention can be applied without problems to achieve the object of the present embodiment.

  Most of the motor control devices according to each embodiment, and the drive units, refrigerators, and air conditioner control units 2 using the motor control devices are configured by semiconductor integrated circuits (arithmetic control means) such as microcomputers and DSPs. It is often realized by software. Therefore, there is a problem that it is difficult to verify whether the control unit 2 is correctly configured. Therefore, in this embodiment, a method for verifying whether the configuration related to each embodiment is operating correctly will be described. FIG. 33 shows an example of verification means.

  In addition, description is abbreviate | omitted about the part which has the same function as the structure which attached | subjected the same code | symbol shown in Examples 1-3.

  Hereinafter, the verification unit 90 will be described. The values that need to be measured are either the three-phase current of the AC output of the motor or power conversion circuit, or the current flowing through the shunt resistor 25 on the DC side of the power conversion circuit 5, the drive signal (gate signal), or the motor Or the output voltage of the power conversion circuit and the magnetic pole position of the motor 6.

  The three-phase current can be measured by CT91 (91a, 91b, 91c), for example. The current flowing through the shunt resistor 25 is obtained by measuring the voltage across the shunt resistor with the voltage detector 92 and dividing it by the value of the shunt resistor. The drive signal (gate signal) can be measured by a potential difference from the reference potential of the control unit 2 or the gate driver circuit 23. The output voltage can be measured by measuring the voltage between the N side of the DC voltage source 20 and each terminal with a voltmeter 93 (93a, 93b, 93c). Alternatively, the line voltage of each phase may be measured and calculated therefrom. The magnetic pole position of the motor 6 can be measured, for example, by attaching a magnetic pole position sensor 94 using an encoder or the like.

  The three-phase current value or the current flowing through the shunt resistor and the magnetic pole position are input to the 3φ / dq coordinate converter 95 to obtain the q-axis current detection value. The 3φ / dq coordinate converter 95 can coordinate-convert the current on the three-phase axis into the current on the dq axis using, for example, Equation 9, and obtain the q-axis current detection value.

  Here, θd is the magnetic pole position of the motor 6.

  The detected q-axis current detection value is input to the initial value calculation means 96. Similar to the initial value calculation means 35, the initial value calculation means 96 includes a first-order lag filter 73, an initial value calculation means 74, and the like.

  The detected q-axis current detection value is compared with the q-axis current detection value obtained by subjecting it to the first-order lag filter process, and the larger value is determined. At the same time, it is determined from the drive signal (gate signal) input by the voltage determination means 97, the motor terminal voltage, or the output voltage waveform of the power conversion circuit, whether the 120-degree energization method or the 180-degree energization method. The determination of the energization method may be made with reference to FIGS. 7, 21, and 22, for example.

  When the energization method changes, the voltage output from the power conversion circuit 5 is detected, and the initial value is set based on either the q-axis current detection value or the q-axis current detection value that has been subjected to first-order lag filtering. Determine if you did.

  For example, a q-axis current detection value and a q-axis current detection value obtained by performing a first-order lag filtering process are input to the calculation (equation 1) of the voltage command value generator 3, and the voltage command value calculated based on which is input. It is only necessary to judge whether is closer. This is because the other parameters of Equation 1 are known.

  For example, when the load fluctuation range is small and the difference between the q-axis current detection value and the q-axis current detection value obtained by performing the first-order lag filtering process is not sufficiently large, the signal of CT91 or the voltage detector 92 is sent to the control unit 2 When entering, a test signal is intentionally input so that a difference from the value obtained by the first-order lag filter processing is obtained.

  As described above, the configuration related to the present invention is realized by software or the like by measuring the three-phase current or the current flowing through the shunt resistor and the drive signal (gate signal), the motor terminal voltage or the output voltage of the power conversion circuit. Even in this case, it is possible to verify whether it is operating correctly.

  In the present embodiment, the method of detecting the magnetic pole position of the motor 6 has been described, but information on the magnetic pole position is not essential. This is because the q-axis current value is equal to or proportional to the amplitude of the three-phase alternating current. Therefore, for example, even when the current flowing through the shunt resistor 25 is observed, a waveform substantially the same as the q-axis current detection value in FIG. 20 can be obtained. Therefore, even if the current flowing through the shunt resistor 25 is input to the current determination means 96, the configuration related to the present invention can be verified. When the current flowing through the shunt resistor 25 is used, the input value of the verification means 90 can be reduced, so that the effects such as the number of parts, reduction of the board area, and improvement of reliability can be obtained.

In addition, this invention is not limited to an above-described Example, Various modifications are included.
For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units, processing procedures, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor.

  Although the motor has been described as a permanent magnet motor, other electric motors (for example, induction machines, synchronous machines, switched reluctance motors, synchronous reluctance motors, etc.) may be used. At that time, the calculation method in the voltage command value generator varies depending on the electric motor, but the other methods can be applied in the same manner, and the object can be achieved.

  As the means for detecting the position of the motor, the configuration based on the open phase electromotive voltage is described as the 120-degree energization method, and the configuration based on the speed electromotive voltage is described in the 180-degree energization method. However, as can be seen from the configuration of the present invention, the means or method for detecting (or estimating) the rotational angle position of the motor 6 in each energization method is not limited to the method described in the above embodiment. For example, the method for detecting the position of the motor, such as the method for detecting the speed electromotive voltage in the open phase in the 120-degree energization method, or the method for detecting the rotational angle position by superimposing the harmonics in the 180-degree energization method is another method. Even if is used, the purpose can be achieved.

DESCRIPTION OF SYMBOLS 1 Motor control apparatus 2 Control part 3 Voltage command value preparation device 5 Power conversion circuit 6 Motor (electric motor)
7 Current detection means 10 Axis error computing unit 30 Energization method switching determination unit 31 Energization method switch 40 Position estimation unit for 120 degrees 41 Position estimation unit for 180 degrees 51 Switching trigger generator 52 Non-conduction phase potential selector 53 Reference level switching 54 Comparator 55 Energization mode switch 60 Open phase voltage detection means 301 Refrigerator 500 Load (compression mechanism)
502 shaft

Claims (6)

A power conversion circuit that converts DC power into AC power; a controller that outputs a drive signal that drives the power conversion circuit; an electric motor that is driven by the power conversion circuit; and a load that is connected to the electric motor. In the motor control device that switches the energization method of the power conversion circuit between the 120-degree energization method and the 180-degree energization method,
When switching from the 120-degree energization method to the 180-degree energization method, the sum of the currents flowing to the motor at the time of shifting to 180-degree energization is the same or increased as the sum of the currents flowing to the motor during the 120-degree energization A motor control device characterized by that. A power conversion circuit that converts DC power into AC power; a controller that outputs a drive signal that drives the power conversion circuit; an electric motor that is driven by the power conversion circuit; and a load that is connected to the electric motor. In the motor control device that selects two phases to be energized among the three-phase windings of the electric motor, applies a pulsed voltage, and estimates the phase and speed based on the non-energized phase electromotive voltage.
A motor control device that outputs a q-axis current command value or a q-axis voltage command value based on a value obtained by adding a delay element to a current detection value on the qc axis. In claim 1 or 2,
A speed controller for adjusting the speed of the electric motor, and a voltage command value creator for obtaining a voltage to be applied to the motor,
When switching the energization method between the 120-degree energization method and the 180-degree energization method, the current value proportional to the torque of the motor is compared with the second current value obtained by adding a delay element to the current, and the larger one A motor control device characterized in that a value is set to an initial value of either the speed controller or the voltage command value generator. In claim 1 or 2,
When switching the energization method between the 120-degree energization method and the 180-degree energization method, a pulse width for driving the power conversion circuit calculated based on a current value proportional to the torque of the motor and a delay element are given to the current The pulse width for driving the power conversion circuit calculated based on the second current value is compared, and the larger pulse width is set to the initial pulse when the energization method is switched between the 120-degree energization method and the 180-degree energization method. A motor control device that outputs as a width. In claim 1 or 2,
A motor control device characterized in that the energization method is switched between a 120-degree energization method and a 180-degree energization method at a frequency higher than a predetermined value, and the energization method is switched during a period when the rotational frequency of the electric motor is lower than a target frequency.   A refrigerator comprising the motor control device according to claim 1.