JP5972138B2 - Electric motor control device, refrigerator using the same, and electric device - Google Patents

Description

  The present invention relates to a drive control device for an electric motor, a refrigerator using the same, and an electric device, and is particularly suitable for controlling the rotational speed and torque of the electric motor by estimating the magnetic pole position of the rotor without using a position sensor. The present invention relates to a drive control device for an electric motor, a refrigerator using the same, and an electric device.

  In the technical fields such as the home appliance field, industrial equipment field, and automobile field, for example, a drive control device using an electric motor is used for rotational speed control, torque control, positioning control, etc. for fans, pumps, compressors, conveyors, elevators, etc. It has been. In electric motors in these fields, for example, small and highly efficient synchronous motors using permanent magnets are widely used.

  In order to drive such an electric motor, information on the magnetic pole position of the rotor of the electric motor is required, and therefore a position sensor such as a resolver or a Hall IC for detecting the magnetic pole position is required. However, in recent years, a technique called “sensorless control” that performs rotation speed control and torque control of an electric motor without using such a position sensor has become widespread.

  The practical use of “sensorless control” reduces the cost required for installation of the position sensor (the cost of the position sensor itself and the cost of wiring of the position sensor), and the size of the device is reduced to the extent that the position sensor is unnecessary. It has become possible to obtain a great effect such that it can be used in a poor environment.

  It is known that a drive control device for an electric motor employing such “sensorless control” is driven by switching between a 120 ° energization method and a 180 ° energization method. This is a well-known technique as described in Japanese Patent No. 172948 (Patent Document 1). This Patent Document 1 discloses a technique for stably switching the energization method by suppressing torque fluctuation and rotation fluctuation.

  In the present invention, “sensorless control” is described as a preferred control method as an example, and is not limited to “sensorless control”, but can be applied to other motor control devices. is there.

JP 2008-172948 A

  In the technique described in Patent Document 1, the current phase during driving of the motor using the 180 ° energization method and the current phase during driving of the motor using the 120 ° energization method are the same before and after switching. It is set as the structure controlled to become.

  As specific disclosure matters in Patent Document 1, when switching from one drive system to the other drive system, the rotational speed control PWM duty / modulation rate calculation unit and energization switching control, voltage / current phase difference calculation, A configuration is disclosed in which the voltage phase calculation unit controls the current phase with respect to the rotor position of the motor immediately before switching in one drive system to be equal to the current phase immediately after switching.

  By the way, according to the study by the present inventors, it has been found that current jumps, speed fluctuations, and the like occur when switching the energization method in this way. When the current jump is large, the motor is stopped by the overcurrent protection circuit, and in the worst case, the switching element and other electric parts are damaged. In addition, as described above, when the speed fluctuation occurs, even if the motor does not stop or break, when the energization method is switched, the generated torque of the motor changes suddenly, so that the motor suddenly accelerates or decelerates. There was a phenomenon of generating vibrations and unpleasant sounds.

  An object of the present invention is to provide a drive control device for an electric motor capable of smoothly switching the energization method by suppressing the occurrence of current jumping and speed fluctuations when switching the energization method, a refrigerator using the same, and an electric device Is to provide.

  A feature of the present invention is that the voltage applied to the motor continuously changes before and after switching between the 180 ° energization method and the 120 ° energization method.

  According to the present invention, before and after switching the energization method of the power conversion circuit, the voltage applied to the electric motor continuously changes without abrupt change, so that it is possible to suppress a jump in current and a rapid speed fluctuation. . For this reason, for example, it is possible to prevent the motor from stopping or damaging the switching element or other electrical components, and the motor suddenly accelerates or decelerates and generates vibrations and unpleasant sounds. Can be prevented.

It is a block diagram which shows an example of an electric motor control apparatus. It is explanatory drawing of a coordinate axis. It is explanatory drawing explaining the relationship between a control axis and a three-phase axis. It is a block diagram which shows the structure of a power converter circuit. It is a block diagram which shows the structure of a mechanism part (compression mechanism part). It is explanatory drawing which shows the change of the load torque with respect to the position of a rotor. It is explanatory drawing explaining the switching system of a 120 degree | times electricity supply system. It is a block diagram which shows the structure of an open phase voltage detection means. It is a schematic diagram in the case of applying a voltage to two phases of an electric motor. It is a characteristic view of the electromotive voltage of a non-energized phase. It is a characteristic figure of the open phase electromotive voltage with respect to a rotation angle position. It is explanatory drawing explaining the relationship between the open phase induced voltage with respect to a rotation angle position, and a reference voltage. It is a block diagram which shows the structure of a reference | standard level switch. It is a block diagram which shows the structure of vector control. It is a block diagram which shows the structure of a PLL controller. It is a block diagram which shows the structure of a speed controller. It is a block diagram which shows the structure of a current controller. It is a figure which shows the current waveform at the time of energization system switching (no countermeasures). It is a figure which shows the drive signal before and behind energization system switching. It is a block diagram which shows another structure of a drive device. It is explanatory drawing explaining the switching system of a 180 degree | times energization system. It is explanatory drawing explaining another switching system of a 180 degree | times energization system. It is a block diagram which shows the structure of a 120 degree position estimation means. It is explanatory drawing which shows the relationship between an electricity supply mode and an electrical angle phase. It is explanatory drawing which shows the relationship between an electrical angle phase and electricity supply mode. It is explanatory drawing which shows the relationship between 3 phase voltage command value and an output voltage.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and application examples are included in the technical concept of the present invention. Is also included in the range. Embodiments will be described below with reference to the drawings.

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

  FIG. 1 is an example of a configuration diagram of an electric 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 driven by the power conversion circuit 5, and a mechanical or magnetic connection to the motor 6 via a connection portion 502. 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

  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 electric 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 electric motor 6, thereby driving the electric 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 invention, there is no influence on the purpose and effect of the present application. In the description, they are treated as the same meaning.

  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.

  A drive signal generation method for switching the power conversion circuit 5 will be described together with an energization method.

  The PWM signal generator 33 shown in FIG. 1 selects a 120-degree energization method or a 180-degree energization method according to the 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, 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. Such a driving method is well known.

  In order to determine the voltage to be applied to the electric motor 6, it is necessary to consider three points: the magnitude of the voltage, the voltage waveform, and the phase of the voltage with respect to the rotor position of the electric 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 an upper arm drive signal Gp and a 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 the upper and lower arms are switched over one electrical angle cycle. This method is also called sine wave driving because a voltage on a sine wave is applied to the electric 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. However, since the dead time has no influence on the purpose and effect of the present application, an ideal drive signal is shown in this specification. Of course, there is no problem even if the configuration has a 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, since there is no change in the drive signal for a certain period, at first glance, it looks like a drive signal with 120 degrees conduction, but the voltage applied to the motor is substantially close to a sine wave, so this method is also 180 degrees. This is called energization.

  In this embodiment, a permanent magnet synchronous motor having a permanent magnet in the rotor is used as the electric 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 applied voltage of the motor. At that 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 which is electrically advanced from the d axis by 90 degrees (electrical angle 90 degrees) in the rotation direction. 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, which is the rotating coordinate system, but the motor can be controlled by simply adjusting the amplitude and phase of the voltage. The relationship between these coordinate axes is shown in FIG. 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).

  In this embodiment, a case where a compression mechanism is used as the mechanism unit 500 will be described. As shown in FIG. 5, the mechanism section (compression mechanism section) 500 drives the piston 501 using the electric motor 6 as a power source. Thereby, a compression operation is performed. A crankshaft 503 is connected to the shaft 502 of the electric motor 6 to convert the rotational movement of the electric motor 6 into a linear movement. In accordance with the rotation of the electric motor 6, the piston 501 also operates to perform a series of processes such as suction, compression, and discharge. The power transmission between the electric 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 when viewed from the electric motor 6 that drives the piston, the load torque changes periodically. 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 electric motor 6 has 6 poles, 3 electrical angle periods correspond to 1 mechanical angle period. 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 electric motor 6.

  Even if the same compression mechanism unit 500 is used, the variation of the load torque varies depending on the rotation speed of the electric 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 application 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 electric motor 6 may jump up due to the switching of the energization method. There is a risk of fluctuations in the rotational speed of the electric motor 6. As a result, vibration and noise may occur. Therefore, one of the purposes of the present application is to provide an electric motor control device that realizes shockless switching that does not cause a current jump or speed fluctuation even when switching the energization method of the power conversion circuit 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 means to be described later can be similarly applied even when the compression mechanism is different, and in either case, the object of the present application can be achieved.

  Returning to 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 rotation angle position and an estimated rotation speed of the rotor. Position estimation means 40, 180 ° position estimation means 41 for inputting an alternating current flowing through electric motor 6 or a current flowing through the DC side of the power conversion circuit, and outputting an estimated rotational angle position and estimated rotational speed of the rotor; The system switching 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 system switching command signal are input. The energization method switching device 31 that outputs the two energization methods (120-degree energization, 180-degree energization) using the rotational angle position or rotation speed of the rotor estimated by the two position estimation means (40 and 41). The switching waiting time calculating means 30 for generating a switching timing trigger for switching the power supply method, the energization method switching means 32 for outputting the energization method switching command signal for switching the energization method, the energization method switching command signal and the voltage command value are inputted and the drive signal is inputted. The output PWM signal generator 33 and the like are configured.

  Here, the PWM signal generator 33 has a drive system switch 45 and a PWM timer 46. 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. Further, when driving by the 180-degree energization method, the drive method switch 45 outputs the input voltage command value as it is. The output of the drive system switching start 5 is sent to the PWM timer 46, which converts the drive signal into the drive signal shown in FIG.

  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.

  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. An example of the configuration 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 electric 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 12.

  An example of the configuration diagram of the open-phase voltage detection means is shown in FIG. When detecting the terminal voltage of the electric motor 6, for example, the open phase voltage detecting means 60 is used. In many cases, since the terminal voltage of the electric motor 6 exceeds the power supply voltage (for example, 5V or 3.3V) of the control unit, the 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 electric motor 6 may be directly input to the control unit 2.

  Details of each component will be described below. First, the operation when the electric motor 6 is driven by the 120-degree position estimation means 40 and the 120-degree conduction drive means 42 and the operation when the motor 6 is driven by the 180-degree position estimation means 41 and the 180-degree conduction drive means 43 will be described. Then, the problem at the time of switching two drive states, in other words, switching between the two energization methods (120-degree energization and 180-degree energization) will be described.

  FIG. 23 shows a configuration example of the 120-degree position estimating means 40 and the 120-degree energization driving means 42 for realizing the following description.

  When the electric motor 6 is driven by energization at 120 degrees, the two phases to be energized are selected from the three-phase windings of the electric motor 6, 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 electric motor. FIG. 9A shows an energization mode (corresponding to energization mode 3 to be described later) in the state of energization from the V phase to the W phase, and FIG. 9B shows the energization from the W phase to the V phase. It is a figure which shows the electricity supply mode of the state which is in 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, which is a non-conduction phase, and is different from the speed induced voltage. It is called an open phase electromotive voltage to distinguish it from a speed electromotive voltage.

  In FIG. 10, the open phase electromotive voltage at the time of applying a positive pulse indicated by a solid line and the open phase electromotive voltage at the time of applying a negative pulse indicated by a broken line are both higher 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 electric motor 6 ranges from near zero speed to a low speed range.

  FIG. 11 shows the open-phase electromotive voltage characteristics with respect to the rotational angle position θd of the rotor when the U phase, V phase, and W phase are non-energized phases, the gate signal of the switching element constituting the power converter 2, and the electric 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, the states (a) and (b) in FIG. 9 correspond to the energization mode 3 or the energization mode 6 in the energization mode. 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 shown in FIG. 23. The non-energized phase potential selector 52 selects the non-energized phase corresponding to the energized mode, and the selected phase. The open-phase electromotive voltage is detected.

  The reference level switch 53 shown in FIG. 13 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 reference positive side reference voltage Vhp or negative side reference voltage Vhn are input as threshold values to the comparator 54 in FIG. A mode switching trigger signal is generated when the electromotive voltage reaches a threshold value. The energization mode switch 55 shown in FIG. 23 receives a mode switching trigger signal, advances the energization mode in the forward rotation direction in accordance with the mode switching trigger signal, and outputs the energization mode.

  The phase converter 56 shown in FIG. 23 inputs the information on the energization mode (energization mode 1 to energization mode 6), and outputs the electrical angle phase (rotational 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. The effect of adopting the phase of the relationship of FIG. 24 will be described later, but is a method suitable for switching the energization method.

  The speed converter 57 in FIG. 23 counts the time in one energization mode, 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 force is different from the speed electromotive force 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 electric 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, it is possible to accurately detect the rotor position even when the motor 6 is stopped or at an 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.

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

  In order to drive the electric motor 6 by energization at 180 degrees, it is preferable to control by the dc-qc axis (rotating 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 estimating 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 *) to be 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 axial error command value Δθ * and the axial error Δθc is obtained by the subtractor 17a, and the result obtained by multiplying the proportional gain Kp_pll by the multiplier 18a and the proportional control is multiplied by the integral gain Ki_pll by the multiplier 18b. The adder 16a adds the result of integration and integration control performed by 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. 14 is set to the lower contact.

  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 the winding resistance value of the electric motor 6, Ld is the d-axis inductance, Lq is the q-axis inductance, and Ke is the 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, a configuration as shown in FIG. 14 can be obtained.

  The electric motor 6 of the present embodiment is a non-salient permanent magnet electric 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 electric 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 type 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.

  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 *.

  FIG. 17 is an example of a configuration diagram of the current controller 12. Current control is performed to improve the 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). The result of the proportional control by multiplying (Kp_dacr and Kp_qdacr) and the result of the integration by integrating the integration gain (Ki_dacr and Ki_qacr) by the multiplier (18g and 18h) and the integration control by the integrator (15d and 15e) are added. And the second d-axis and q-axis current command values (Id ** and Iq **) are output.

  Next, the operation during 120-degree energization driving will be described. In the 120-degree energization drive, the multiple energization method changeover switch 59 in FIG. 14 is set to the upper contact.

  In this embodiment, an example is shown in which the operation is changed during 120-degree energization driving and 180-degree energization driving. Of course, even in the 120-degree energization drive, as with the 180-degree energization drive, there is no problem even if the speed controller 14 and the current controller 12 are added.

  In the present embodiment, the current command values (Id ** and Iq **) during 120-degree energization driving are the current command values (Id * _120 and Iq * _120 *) input from a host control or the like not shown. Use. When using the current command value input from the host control or the like, since the number of multipliers and integrators is reduced, there is an effect that the calculation load of the control unit 2 can be reduced.

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

  The dq / 3φ converter 4 inputs 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 electric motor rotates 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.

  When the state quantity (position, speed, torque, etc.) of the electric 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 voltage increases as the rotational speed increases. In the middle and high speed range, the speed electromotive voltage is higher than the open phase electromotive voltage of the non-conduction phase. Is more dominant.

  Therefore, when the motor position is detected and the state quantity (position, speed, torque, etc.) of the motor is controlled in the high speed range from when the motor is stopped, the control is performed based on the open phase electromotive voltage. 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 the 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.

  When switching the energization method, a current jump or a speed fluctuation occurred as shown in FIG. If the current jump is large, the motor may be stopped by the overcurrent protection circuit, or in the worst case, the switching element 22 or 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 vibrations and unpleasant sounds.

  To solve these problems, when switching the current-carrying method from the 120-degree current-carrying method to the 180-degree current-carrying method, shockless switching that does not cause a current jump, torque shock due to discontinuity of the motor-generated torque, speed fluctuation, etc. It is one of the objects of the present invention to provide an electric motor control device that realizes the above.

  For convenience of explanation, the means for detecting the position of the motor will be described as a configuration based on the above-described open-phase electromotive voltage as a 120-degree energization method, and as a configuration based on the above-described speed electromotive voltage in the 180-degree energization method. explain. However, as can be seen from the configuration of the present invention, which will be described later, the means or method for detecting (or estimating) the rotational angle position of the electric motor 6 in each energization method is not limited to the method described in this embodiment, and for example superimposing harmonics. The means for detecting the position of the electric motor, such as a method for detecting the rotational angle position, can also be applied using other methods.

  One of the causes such as a current jump that occurs when the above-described energization method is switched is a discontinuity in the voltage applied from the inverter to the electric motor. The 120-degree energization method energizes only two phases of the three phases, while the 180-degree energization method energizes all three phases. For example, if the phase that was not switching when driving with the 120-degree energization method is switched to the drive with the 180-degree energization method and suddenly switched, the line voltage applied to the motor changes greatly and becomes discontinuous. As a result, the current jumps and the electric motor generated torque becomes discontinuous.

  Therefore, before and after switching of the energization method, switching can be performed without switching shock if the relationship between the line voltages applied to the electric motor is kept continuous. In order to determine the voltage to be applied to the electric motor 6, it is necessary to consider three points: the magnitude of the voltage, the voltage waveform, and the phase of the voltage with respect to the rotor position of the electric motor 6. Considering these, the continuity of the voltage applied to the electric motor 6 is maintained.

  Furthermore, considering the purpose of the present application (switching the energization method to shockless), the drive signal generation method should be the same. Hereinafter, a specific implementation method will be described.

  FIG. 19 shows drive signals before and after switching the energization method. For simplification, the change in the drive signal is shown on the assumption that there is no speed fluctuation and load torque fluctuation before and after the switching of the energization method, that is, a situation where a constant voltage command is output. FIG. 19 shows an example of switching the energization method from the 120-degree energization method to the 180-degree energization method, but conversely, switching from the 180-degree energization method to the 120-degree energization method can also be realized in the same manner as below. The object of the present application can be achieved.

  First, the drive signal of the present application when driving by the 120-degree energization method will be described.

  When driven by the 120-degree energization method, the rotation angle position is detected every 60 electrical angles, and as shown in FIG. 25, the electrical angles are 30 degrees, 90 degrees, 150 degrees, 210 degrees, The energization pattern (drive signal pattern) changes at six timings of 270 degrees.

  That is, in the 120-degree energization method, there are only six energization patterns. Therefore, although the actual rotational angle position of the rotor changes continuously, the electrical angle used for determining the energization pattern does not necessarily need to be changed continuously. Conditions for changing the energization mode (the conditions depend on the position estimation method. For example, in the configuration of position estimation based on the open-phase electromotive voltage, whether or not the open-phase voltage exceeds the threshold value is a determination condition). Then, the electrical angle may be changed to a value that is a predetermined energization mode every 60 degrees.

  Therefore, the phase θd in each energization mode related to the output voltage phase is determined as shown in FIG. For example, in the energization mode 3, when the open phase electromotive voltage (the U phase is the open phase in the energization mode 3) exceeds the threshold value (when the reference voltage (Vhn) that is the threshold value in the energization mode 3 falls below), The rotation angle position exceeds the position of 30 degrees in electrical angle. Before that, the rotational angle position of the rotor in the energization mode 3 is any one of -30 degrees (330 degrees) to 30 degrees in electrical angle, but the period of the energization mode 3 is 0 degrees.

  The effect of determining the phase θd as shown in FIG. 24 will be described. FIG. 26 shows the relationship between the three-phase voltage command value and the output voltage. The one-dot chain line in FIG. 26 is a three-phase sine wave voltage command value that is the basis of the signal. Considering this three-phase sinusoidal voltage command value, the electrical angle is 0 degree, 60 degree, 120 degree, 180 degree, 240 degree, the intermediate phase voltage is zero, the absolute value of the maximum phase and the minimum phase Are the same positions.

  Therefore, by determining the phase θd as shown in FIG. 24, the voltage command value of each phase becomes a stepped voltage command value as shown in FIG. 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.

  Here, paying attention to the drive signals of the maximum phase and the minimum phase of FIG. 26, the same voltage as that of the drive signal of the complementary switching system of FIG. 7 is applied to the motor. The non-energized phase is uniquely determined by the energization mode.

  Therefore, a voltage command value, an energization method switch command signal, and an energization mode command are input to the drive method switch 45. When driven by the 120-degree energization method, the non-energized phase drive signal (intermediate phase drive signal in FIG. 26) is output as inactive (indicated by dotted lines in the figure) according to the energization mode. To do.

  In addition, when driving by the 180-degree energization method, the drive method switch 45 may output the input voltage command value as it is.

  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.

  Based on the drive signal generation method in the present application, drive signals before and after switching the energization method in FIG. 19 will be described in detail.

  If you look at the voltage command value that is the basis of the drive signal or the equivalent applied voltage value that is obtained by integrating the drive signal, at the timing when the energization mode (energization phase) at 120 degrees energization changes, the voltage The maximum or minimum phase is switched.

  If the 120-degree energization method is switched from the 120-degree energization method at the timing (30 degrees, 90 degrees, 150 degrees, 210 degrees, and 270 degrees) when the energization mode (energization phase) at 120 degrees energization changes, 120 degrees When energized, the intermediate phase that was OFF starts switching at the same switching duty as the maximum phase.

  In the case where the electric motor 6 has a Y-connection as shown in FIG. 9, for example, consider switching from 120-degree energization to 180-degree energization at an electrical angle of 270 degrees (denoted as -90 degrees in FIG. 11). At 120 degrees energization, a voltage is applied from the U phase to the W phase in mode 2. However, when switching to 180 degrees energization, a parallel circuit of the U phase and the V phase applies to the W phase.

  That is, the voltage applied to the electric motor before and after switching the energization method becomes discontinuous. In other words, the magnitude and phase of the magnetic flux generated in the stator windings suddenly change, and the generated torque of the electric motor becomes discontinuous, which causes speed fluctuations and vibrations and noises resulting therefrom.

  Therefore, in the method of the present invention, the timing for switching to 180-degree energization is the timing when the voltage command value for the intermediate phase becomes zero. In other words, when switching from 120-degree energization to 180-degree energization, the ratio of the upper arm to the lower arm is approximately the same (about 50%) in the drive signal of the phase in which the upper and lower arms are not switched in the previous energization mode. ). By doing so, the voltage applied to the electric motor before and after switching the energization method can be made continuous. That is, switching can be performed without switching shock.

  Next, a method for determining the timing when the intermediate phase voltage command value becomes zero will be described.

  As described above, in the 120-degree energization method, the rotational angle position is detected every 60 degrees of electrical angle, or the position is estimated every 60 degrees, and the electrical angle is 30 degrees, 90 degrees, 150 degrees, 210 degrees. The energization pattern (drive signal pattern) changes at six timings of 270 degrees and 330 degrees.

  On the other hand, as shown in FIG. 26, the timing at which the intermediate phase becomes zero is six timings in which the electrical angle is 0 degree, 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees. That is, after the condition for changing the energization mode is satisfied, if the energization method is switched after waiting for a period of 30 degrees in electrical angle, the energization method switching at the timing when the intermediate phase becomes zero can be realized. Can achieve the purpose.

  The switching waiting time calculating means 30 is a switching timing for switching between the two energization methods (120-degree energization and 180-degree energization) using the rotational angle position or rotational speed of the rotor estimated by the two position estimation means (40 and 41). Outputs a trigger. The energization method switching means 32 inputs a switching timing trigger and outputs an energization method switching command signal.

  The operation of the switching waiting time calculation unit 30 will be described by taking as an example the operation when switching from the 120-degree energization method to the 180-degree energization method.

  First, the energization method switching request is determined based on, for example, whether a command from a host system (not shown) or a speed command value exceeds a predetermined value.

  Assume that there is a request for switching the energization method at the timing indicated by the arrow at the top in FIG. Thereafter, from the time when the energization mode is changed, the switching waiting time calculation means 30 measures the elapsed time, and when a period of 30 degrees in electrical angle has elapsed, outputs a switching timing trigger, and the energization method switching means 32 causes the energization method to be changed. Outputs a switching command signal.

  The elapsed time measurement uses, for example, the count number (N_pwm) counted at the interrupt timing of the peak or valley of the triangular wave carrier signal during the energization mode in which the energization method switching request is made. Since N_pwm is a period corresponding to an electrical angle of 60 degrees, the switching waiting time calculation means 30 similarly counts up at the peak or valley interrupt timing of the triangular wave carrier signal, and when the count value reaches half of N_pwm, If a switching timing trigger is output, it can be seen that a period of 30 degrees in electrical angle has elapsed.

  By determining by the count value, even when the speed of switching the energization method changes, it is possible to accurately measure a period of 30 degrees in electrical angle.

  The operation of the switching waiting time calculating unit 30 will be described by taking an example of the operation when switching from the 180 degree energization method to the 120 degree energization method.

  The rotation angle position of the rotor estimated by the 180-degree position estimating means 41 is input to the switching waiting time calculating means 30. When the electrical angle reaches 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees after the energization system switching request is issued, a switching timing trigger is output, and the energization system switching means 32 is energized. Outputs system switching command signal.

  In the 180-degree energization method, the phase θd changes continuously, so the determination may be made based on the phase. Even in the 120-degree energization method, it is possible to make a determination based on the phase. In the position estimation of the 120-degree energization method described above, the position at every electrical angle of 60 degrees is detected based on whether or not the open-phase voltage exceeds the threshold reference voltage, but the non-energized phase shown in FIG. As can be seen from the example of the electromotive voltage characteristic diagram of FIG. For example, the phase may be continuously changed even in the 120-degree energization method by linearly approximating the electromotive voltage characteristics of the non-energized phase or expressing it as a function with respect to the phase. In that case, the method of judging based on the phase as described above is more suitable. For example, when the number of timers of the control unit 2 is limited, the number of timers can be saved by judging by the phase, and the timers can be assigned to other functions.

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

  FIG. 20 is an example of a configuration diagram illustrating a refrigerator using the motor control device according to the second embodiment.

  In addition, description is abbreviate | omitted about the part which has the same code | symbol shown by Example 1 already demonstrated, and the part which has the same function.

  As illustrated in FIG. 20, the refrigerator 301 includes a heat exchanger 302, a blower 303, a compressor 304, a compressor driving electric motor 305, and the like. In addition, the refrigerator control device 306 includes an internal control device 307 and an electric motor control device 1 that control a blower, an internal light, and the like based on various sensor information.

  In the refrigerator, due to technological innovations such as vacuum heat insulating materials, the amount of heat leakage from which the heat in the refrigerator leaks to the outside air is very small. Therefore, in order to reduce the power consumption of the motor control device 1 that drives the compressor, the power consumption during steady state (startup) and the power consumption during consumption (power consumption) are important. It becomes.

  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 compressor driving motor 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.

  When position sensorless control based on the speed electromotive force is employed, the speed electromotive force becomes small at low speeds, making position estimation difficult. 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. At low speed, for example, position feedback is not performed, and driving is performed by a method called synchronous operation in which a voltage command value is determined from a predetermined current command value and speed command value.

  Since the position cannot be detected during the synchronous operation, only the current that directly contributes to the torque cannot be applied, and a wasteful current flows. Therefore, in order to obtain a torque necessary for starting the compressor driving electric motor of the refrigerator, it is necessary to pass a current having a margin.

  Therefore, in order to reduce the power consumption, it is necessary to detect the position even in the extremely low speed region including the zero speed and to provide only the current that directly contributes to the torque. That is, it is one of the objects of the present application to provide an electric motor control device capable of reducing the amount of power consumption by starting up with the minimum necessary current, and a refrigerator and an air conditioner using the electric motor control device. Furthermore, it is an object of the present application to provide an electric motor control device that can drive an electric motor without a position sensor in a wide speed range, and a refrigerator and an air conditioner using the electric motor control device. Furthermore, it is one of the objects of the present application to provide an electric motor control device capable of reducing the arrangement space by reducing the maximum current capacity of the power conversion circuit 5, and a refrigerator and an air conditioner using the electric motor control device. is there.

  An example of the configuration diagram of the motor control device in the present embodiment is FIG.

  When switching the energization method, a current jump or a speed fluctuation occurred as shown in FIG. If the current jump is large, the motor may be stopped by the overcurrent protection circuit, or in the worst case, the switching element 22 or other electrical components may be damaged. The power converter circuit 5 is most fragile, and it is necessary to increase the capacity of the power converter circuit 5 in order to prevent the power converter circuit 5 from being broken even by a current jump. . 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 vibrations and unpleasant sounds.

  Therefore, in the low speed region, driving is performed by a 120-degree energization method based on the open-phase electromotive voltage, and in the medium-high speed region, 180-degree energization method driving is performed based on the speed electromotive voltage. Thereby, it is possible to drive without a position sensor even in a low speed region. When driven without a position sensor, a maximum torque corresponding to the rotational angle position of the electric motor can be generated. In other words, it can be driven with the minimum necessary current. Thereby, power consumption can be reduced. Furthermore, the arrangement space can be reduced by reducing the capacity of the power conversion circuit 5.

  When switching the energization method, if the energization method is switched after waiting for a period of 30 degrees in electrical angle by the switching waiting time calculation means 30, the energization method switching at the timing when the intermediate phase becomes zero can be realized, Current jump can be suppressed. Thereby, the arrangement space can be reduced by reducing the capacity of the power conversion circuit 5.

  In addition, the motor control apparatus according to the present embodiment is used in many technical fields such as home appliances field, industrial equipment field, automobile field, etc., for example, operation of electric devices such as fans, pumps, compressors, conveyors, elevators, etc. The present invention can also be applied to control an electric motor that drives an object.

  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 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 other methods can be applied in the same manner, and the object of the present application can be achieved.

  In the above embodiment, the position sensorless control is described as a premise. Therefore, although the position estimation method has been described, for example, the object of the present application can be achieved even when switching from 120-degree energization driving to 180-degree energization driving using a Hall sensor that can obtain a position every 60 degrees of electrical angle.

DESCRIPTION OF SYMBOLS 1 ... Electric motor control apparatus, 2 ... Control part, 3 ... Voltage command value preparation device, 5 ... Power conversion circuit, 6 ... Electric motor, 7 ... Current detection means, 30 ... Switching waiting time calculation means, 31 ... Energization system switch, 32... Energization method switching means, 40... 120 degree position estimating means, 41... 180 degree position estimating means, 51... Switching trigger generator, 52 .. non-energizing phase potential selector, 53. Comparator, 55 ... energization mode switch, 60 ... open phase voltage detection means, 301 ... refrigerator, 500 ... compression mechanism, 503 ... crankshaft.

Claims (4)

A power conversion circuit for converting DC power into AC power, an electric motor driven by the power conversion circuit, a mechanical unit mechanically or magnetically connected to the electric motor, and an energization method of the power conversion circuit are 120. In an electric motor control device comprising a control means for switching between a degree energization method and a 180 degree energization method,
The control means includes
When switching from the 120-degree energization method to the 180-degree energization method, a switching period of 30 degrees in electrical angle has elapsed since the energization mode of the 120-degree energization method was changed after the energization method switching request was made. A switching waiting time calculating means for obtaining a switching timing for detecting and switching to the 180-degree energization method;
An energization method switching means for switching from the 120-degree energization method to the 180-degree energization method based on the switching timing obtained by the switching wait time calculating means;
Further, the switching waiting time calculating means uses a triangular wave carrier signal for generating a drive signal for switching the power conversion circuit, and according to the count number counted at the peak or valley interrupt timing of the triangular wave carrier signal, A motor control device comprising a switching timing output function for outputting the switching timing when it is detected that the electrical angle of the motor has changed by 30 degrees . In the electric motor control device according to claim 1 ,
The switching timing output function uses the triangular wave carrier signal for generating a drive signal for switching the upper and lower arms of the power conversion circuit according to the 180-degree energization method, and the electrical angle during a period corresponding to 60 degrees Counts up at the peak or trough interrupt timing of the triangular wave carrier signal from the time when the energization mode of the 120-degree energization method changes with respect to the count number (N_pwm) counted at the peak or trough interrupt timing of the triangular wave carrier signal The motor control device outputs the switching timing when the count value reaches a half of the count number (N_pwm) (corresponding to 30 degrees in electrical angle). The refrigerator which controls the electric motor which drives the compressor of a refrigerating cycle using the electric motor control apparatus of Claim 1 or Claim 2. An electric device that controls an electric motor that drives an operation target of the electric device by using the electric motor control device according to claim 1.

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