JP2008199871A - Method and device for controlling synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for controlling a synchronous motor capable of rapidly reaching an efficient operating state at starting. <P>SOLUTION: The synchronous motor is started by non-self-controlled operation (Step 101), and an instantaneous current vector phase value and its low pass processing value are calculated from obtained phase current values (Steps 102-104). Then, when the instantaneous current vector phase value crosses the low pass processing value from small one to large one toward a current vector phase when control is executed in self-controlled operation (Step 105), and the control from the non-self-controlled operation to the self controlled operation is switched (Step 106). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a synchronous motor control method and control apparatus, and more particularly, to a motor control method and a motor control apparatus for controlling operation of a synchronous motor including a plurality of phase motor coils without using a rotor position sensor.

  As a conventional technique, there is a synchronous motor control device disclosed in Patent Document 1 below. In this motor control device, when the motor is started, first, the motor is started by performing operation control (so-called other control operation control) that applies a rotating magnetic field from the outside regardless of the rotor rotation position, and then the rotor rotation position estimation detection result is obtained. Based on this, operation control (so-called self-regulated operation control) for controlling the inverter and supplying an output voltage or current is performed.

When other control operation is performed, the rotational position estimation detection result of the rotor satisfies a predetermined condition so that stable position estimation detection can be performed, and self-control is performed based on inductance, current, and magnetic flux amount. When it is determined that the operation is possible, the control is switched from the other control operation control to the self operation control.
Japanese Patent No. 3551912

  However, in the motor control device of the above prior art, when the motor is started, switching from other braking operation control to autonomous driving control is performed. However, the actual state of the motor at the time of switching (vibration in the rotational direction of the rotor, etc.) The actual state of the rotor is not known.

  Therefore, there is a large variation in the torque of the load driven by the motor when switching the operation control, and the rotational position of the rotor is oscillating greatly (it seems to have a vibrational variation in the direction of rotation while rotating). In such a case, there is a problem that a step-out or a control delay occurs, and an efficient driving state by the self-control operation cannot be quickly reached.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a control method and a control device for a synchronous motor that can quickly reach an efficient operating state at the time of startup.

In order to achieve the above object, in the control method of the invention according to claim 1,
Synchronous operation for controlling the operation of a synchronous motor (12) for driving a load (11) by outputting a voltage command to be applied to a stator coil composed of a plurality of phases without using a position sensor for detecting the position of the rotor. A method for controlling a motor,
Other braking operation step (101) for starting the operation of the synchronous motor by other braking operation in which a voltage is applied to the stator coil by a predetermined voltage amplitude / frequency command regardless of the position of the rotor;
After the other control operation step (101), a voltage is applied to the stator coil by a voltage amplitude / voltage phase command based on the estimated position of the rotor, and the operation of the synchronous motor is continued by the self-control operation that controls the current vector flowing through the stator coil. Self-control operation step (107);
An operation switching step for switching operation control from other control operation to self-control operation when it is detected that the phase of the current vector is progressing in the direction of increasing the phase angle with respect to the magnetic pole axis of the rotor during other control operation. (102 to 106).

  During the self-limiting operation control, the current vector of the stator coil is controlled so that the synchronous motor (12) is operated more efficiently than during the other control operation control. The phase angle of the current vector with respect to the magnetic pole axis of the rotor is greater than that during the other control control. growing.

  Therefore, even if the load (11) torque driven by the synchronous motor (12) has a large fluctuation and the rotor has a vibration fluctuation in the rotational direction, the phase of the current vector is relative to the magnetic pole axis of the rotor. When it is detected that the phase angle is increasing, the operation control is switched from self-control operation to self-control operation in which the phase angle of the current vector is further increased. Control switching can be performed.

  In this way, when the synchronous motor (12) is started, the control can be smoothly switched from the other control operation to the self-control operation, and an efficient operation state can be quickly reached.

  In the control method according to the second aspect of the present invention, in the operation switching steps (102 to 106), a low-pass processing value obtained by low-pass processing the phase angle of the current vector is calculated, and the phase angle of the current vector becomes the low-pass processing value. On the other hand, when it is equal to or higher, the operation control is switched from the other control operation to the self-control operation.

  According to this, when the torque of the synchronous motor (12) is not insufficient with respect to the required average torque, the operation control can be switched from the other control operation to the self-control operation. Therefore, it is possible to prevent the synchronous motor (12) from stopping due to a step-out at the time of control switching or taking time to shift to an efficient operating state.

  In the control method according to the third aspect of the present invention, in the operation switching steps (102 to 106), when the phase angle of the current vector exceeds the low-pass processing value, the operation control is switched from the other control operation to the self-control operation. It is characterized by that.

  According to this, when the torque of the synchronous motor (12) is not excessive or insufficient with respect to the required average torque, the operation control can be switched from the other control operation to the self-control operation. Therefore, it is possible not only to prevent the synchronous motor (12) from stepping out and stopping at the time of control switching due to torque shortage or taking time to shift to an efficient operating state, but also due to excessive torque. It can be prevented that overshoot or the like occurs and time is required to shift to an efficient operation state.

  In the control method according to the fourth aspect of the present invention, in the operation switching steps (102 to 106), the current is determined based on at least one of the component in the magnetic pole axis direction and the component in the direction orthogonal to the magnetic pole axis of the current vector. It is characterized by detecting the progress state of the phase of the vector.

  In general, the phase of the current vector with reference to the magnetic pole axis of the rotor is obtained from the magnetic pole axis component and the magnetic pole axis orthogonal component of the current vector obtained by rotating coordinate conversion of the acquired current information. Therefore, if the progress state of the phase of the current vector is detected based on at least one of the component of the current vector in the magnetic pole axis direction and the component in the direction orthogonal to the magnetic pole axis, it is possible to simplify the arithmetic processing.

  In the control method according to the fifth aspect of the present invention, the load (11) driven by the synchronous motor (12) is a compression mechanism (11) for compressing the refrigerant circulating during the heat pump cycle. It is said.

  In the compression mechanism (11) that compresses the refrigerant of the heat pump cycle, the load torque is likely to fluctuate greatly depending on the state of the refrigerant in the cycle and the suction compression / discharge cycle, and vibration fluctuations are likely to occur in the rotor in the rotational direction. Therefore, according to the present invention, when the synchronous motor (12) for driving the compression mechanism (11) is started, the control is smoothly switched from the other control operation to the self-control operation, and the efficient operation state is quickly reached. The effect that can be done is extremely large.

In the control method of the invention according to claim 6,
The self-control operation step (107)
A steady state in which a voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil continues to match the steady state target current phase determined based on the motor efficiency or its related value or the motor torque or its related value. A steady operation step (107C) for operation;
In order to shift the phase of the current vector from the phase of the current vector flowing in the stator coil to the steady operation target current phase at the time when the operation control switching to the self-controlled operation is performed in the operation switching step (102 to 106), the steady operation step The transition operation step (107A) to be executed before (107C),
In the transition operation step (107A), a transition operation target current phase is set, and a transition operation is performed in which a voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil matches the transition operation target current phase. And
The transition operation step (107A) is characterized in that the transition operation target current phase is set so as to change stepwise toward the steady operation target current phase.

  According to this, it is possible to continuously change the motor control state in the transition operation from the time point when the operation control switching to the self-controlled operation is performed to the time point when reaching the steady operation.

In the control method of the invention according to claim 7,
The self-control operation step (107)
A steady state in which a voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil continues to match the steady state target current phase determined based on the motor efficiency or its related value or the motor torque or its related value. A steady operation step (107C) for operation;
In order to shift the phase of the current vector from the phase of the current vector flowing in the stator coil to the steady operation target current phase at the time when the operation control switching to the self-controlled operation is performed in the operation switching step (102 to 106), the steady operation step A transition operation step (107B) executed before (107C),
In the transition operation step (107B), a transition operation target current phase is set, and a transition operation is performed in which a voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil matches the transition operation target current phase. And
The transition operation step (107B) is characterized in that the steady operation target current phase is set as the transition operation target current phase from the beginning of the transition operation.

  According to this, since the torque error caused by the estimated rotor position error can be suppressed, it is possible to switch the control from the other control operation control to the self-control operation control under the condition that the torque is hardly insufficient.

In the control device of the invention according to claim 8,
Synchronous operation for controlling the operation of a synchronous motor (12) for driving a load (11) by outputting a voltage command to be applied to a stator coil composed of a plurality of phases without using a position sensor for detecting the position of the rotor. A motor control device,
Other braking operation control means (22) for operating the synchronous motor (12) by other braking operation control for outputting a predetermined voltage amplitude / frequency command regardless of the position of the rotor and applying a voltage to the stator coil;
Self-running operation control means for driving the synchronous motor (12) by self-running control for outputting a voltage amplitude / voltage phase command based on the estimated position of the rotor, applying a voltage to the stator coil, and controlling a current vector flowing through the stator coil (23)
After starting the operation of the synchronous motor (12) by other braking operation by the other braking operation control means (22), the phase of the current vector is in a state of progressing in the direction of increasing the phase angle with respect to the magnetic pole axis of the rotor. When the control signal is detected, the operation control switching means (24) switches the operation control of the synchronous motor (12) from the other control operation control by the other control operation control means (22) to the self operation control by the self operation control means (23). 25).

  According to this, the control method of the invention described in claim 1 can be performed.

  In the control device according to the ninth aspect, the operation control switching means (24, 25) calculates a low-pass processing value obtained by low-pass processing the phase angle of the current vector, and the phase angle of the current vector is calculated by the low-pass processing value. However, when it is equal to or higher than the above, the operation control is switched from the other control operation control by the other operation control means (22) to the self operation control by the self operation control means (23).

  According to this, the control method of the invention of claim 2 can be performed.

  In the control device according to the tenth aspect of the present invention, the operation control switching means (24, 25) may be controlled by the other control operation control means (22) when the phase angle of the current vector exceeds the low-pass processing value. The operation control is switched from the braking operation control to the autonomous driving control by the autonomous driving control means (23).

  According to this, the control method of the invention according to claim 3 can be performed.

  In the control device of the invention according to claim 11, the operation control switching means (24, 25) is based on at least one of a component of the current vector in the magnetic pole axis direction and a component in the direction orthogonal to the magnetic pole axis. It is characterized by detecting the progress state of the phase of the current vector.

  According to this, the control method of the invention of claim 4 can be performed.

  In the control device according to the twelfth aspect of the invention, the load (11) driven by the synchronous motor (12) is a compression mechanism (11) for compressing the refrigerant circulating during the heat pump cycle. It is said.

  According to this, the control method of the invention described in claim 5 can be performed.

In the control device of the invention according to claim 13,
The self-control operation control means (23)
A voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil continues to match the steady operation target current phase determined based on the motor efficiency or its related value or the motor torque or its related value. Steady operation control means (107C) for performing steady operation;
Transition operation for performing a transition operation for shifting the phase of the current vector from the phase of the current vector flowing in the stator coil to the steady operation target current phase at the time when the operation control switching means (24, 25) switches the operation control to the self-controlled operation. Control means (107A),
The transition operation control means (107A) sets a transition operation target current phase, and performs a transition operation by applying a voltage to the stator coil so that the phase of the current vector flowing in the stator coil matches the transition operation target current phase. Because
The transition operation control means (107A) is characterized in that the transition operation target current phase is set so as to change stepwise toward the steady operation target current phase.

  According to this, the control method of the invention described in claim 6 can be performed.

In the control device of the invention according to claim 14,
The self-control operation control means (23)
A voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil continues to match the steady operation target current phase determined based on the motor efficiency or its related value or the motor torque or its related value. Steady operation control means (107C) for performing steady operation;
Transition operation for performing a transition operation for shifting the phase of the current vector from the phase of the current vector flowing in the stator coil to the steady operation target current phase at the time when the operation control switching means (24, 25) switches the operation control to the self-controlled operation. Control means (107B),
The transition operation control means (107B) sets the transition operation target current phase, and performs the transition operation by applying a voltage to the stator coil so that the phase of the current vector flowing in the stator coil matches the transition operation target current phase. Because
The transition operation control means (107B) is characterized in that the steady operation target current phase is set as the transition operation target current phase from the beginning of the transition operation.

  According to this, the control method of the invention described in claim 7 can be performed.

  In addition, the code | symbol in the parenthesis attached | subjected to each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a control device 20 for a synchronous motor 12 of an electric compressor 10 which is a position sensorless operation control device for a synchronous motor in a first embodiment to which the present invention is applied.

  The electric compressor 10 is a compressor disposed during a heat pump cycle such as a heat pump type hot water supply device or a vehicle air conditioner using carbon dioxide or the like as a refrigerant, and the compression mechanism 11 is driven by a built-in synchronous motor 12. Thus, it is an electric compressor that compresses a gas-phase refrigerant (for example, compresses it to a critical pressure or more if it is a carbon dioxide refrigerant) and discharges it.

  As shown in FIG. 1, the electric compressor 10 rotates a compression mechanism 11 as a load by a synchronous motor 12 and compresses and discharges a refrigerant. The synchronous motor 12 of this embodiment uses a magnet. This is a synchronous motor having a four-pole three-phase coil that rotationally drives an embedded rotor.

  Then, a DC voltage is input to the inverter circuit 16 from the DC power supply generation unit 14 via the bus 15, and the inverter circuit 16 receives each phase (U, V) of the stator coil of the synchronous motor 12 based on a command signal from the control device 20. , W phase) is applied with a voltage via the wiring 17, and the rotor is driven to rotate.

  The DC power supply generation unit 14 may be a DC power supply, or may be one that inputs an AC voltage from an external power supply to an AC / DC converter circuit or the like and converts it into a DC voltage.

  Further, as shown in FIG. 1, the inverter circuit 16 has a known structure composed of a plurality of arms in which switching elements and diodes are connected in antiparallel.

  The control device 20 includes a control input / output unit 21, an other control unit 22, a self-control unit 23, a control switching condition calculation unit 24, and a control switching unit 25. Here, the other control unit 22 corresponds to the other operation control unit in the present embodiment, the self control unit 23 corresponds to the self operation control unit, and the control switching condition calculation unit 24 and the control switching unit 25 perform operation control switching. Corresponds to means.

  The control input / output unit 21 is a connection unit that manages input / output of signals between the inverter power supply component (in this example, the inverter circuit 16 and the wiring 17) and the substantial motor control unit of the control device 20. As shown in FIG. 1, the input / output of the information signal performed via the control input / output unit 21 includes the input of detected current value information in one phase or a plurality of phases (two phases in this example) of the wiring 17, and an inverter circuit. There are input of voltage information from 16, output of voltage command information to the inverter circuit 16, and the like.

  The other control unit 22 outputs a predetermined voltage amplitude / operation frequency command to the inverter circuit 16 via the control input / output unit 21, and applies the voltage to the stator coil regardless of the rotor position. A function of braking and starting the synchronous motor 12 is provided.

  On the other hand, the self-control unit 23 estimates the position of the rotor using the actual state quantities (measured state quantities such as voltage, current, and rotation speed) of the synchronous motor 12 input via the control input / output unit 21. A voltage amplitude / voltage phase command based on the calculated estimated position of the rotor is output to the inverter circuit 16 via the control input / output unit 21, and a voltage is applied to the stator coil by vector control reflecting the estimated position of the rotor. The synchronous motor 12 is provided with a function of self-limiting operation.

  Further, the self-limiting control unit 23 performs the calculation of the rotor position even when the other control operation control is performed by the other control control unit 22, and estimates rotor position information (electrical in this example) used for coordinate conversion described later. The angle θe) is output to the control switching condition calculation unit 24.

  The control switching condition calculation unit 24 detects (acquires) the actual state quantity of the synchronous motor 12 input via the control input / output unit 21 (in this example, the phase current value detected by the current detection means provided in the wiring 17). Based on these detection results (acquisition results), the control switching determination from the other control operation control to the self-control operation control is performed, and the determination result information is output to the control switching unit 25. The control switching between the other control operation control by the control control unit 22 and the self control operation control by the self control control unit 23 is performed.

  Next, a control operation performed by the control device 20 when starting the synchronous motor 12 will be described. FIG. 2 is a flowchart showing a schematic control operation of the control device 20 during motor start control. 3 and 4 are diagrams for defining coordinate axes in motor control. FIG. 3 shows the relationship between the position of each phase (U, V, W phase) of the stator coil and the fixed coordinates composed of the α and β axes. FIG. 4 shows the rotor based on the α and β axes. It shows a rotation coordinate composed of a d axis that is a magnetic pole axis and a q axis that is orthogonal to the d axis.

  As shown in FIG. 2, the control device 20 first outputs a predetermined voltage amplitude / operation frequency command from the other control unit 22 and starts the other operation (step 101). When the other system operation is started in step 101, the other system operation is continued up to a predetermined condition. The control executed here is so-called voltage open control (starting control).

  When step 101 is executed and the other control operation is started and a predetermined condition is reached, the operation shifts to the control switching determination operation.

  First, the control switching condition calculation unit 24 acquires the U-phase current value iu and the V-phase current value iv, which are actual state quantities actually measured in the wiring 17, via the control input / output unit 21 (step 102).

When step 102 is executed, the control switching condition calculation unit 24 calculates an instantaneous current vector phase based on the U-phase current value iu and the V-phase current value iv that are detected values detected in step 102 (step 103). Specifically, the obtained U-phase current value iu and V-phase current value iv are coordinate-transformed, and the d-axis current id that is the d-axis component of the current vector i that flows through the stator coil and the q-axis current iq that is the q-axis component. And the current phase (current vector phase angle) θc is calculated from the relationship shown in FIG.
(Equation 1)
θc = tan ⁻¹ (iq / id)
When the instantaneous value of the current phase θc is calculated in step 103, a low-pass filter value of the current phase is calculated from this value (step 104). Here, in addition to the instantaneous current phase value calculated in step 103, the instantaneous current phase value calculated over the immediately preceding multiple times is low-pass processed to remove high frequency components, and the average current phase at that time is calculated.

  When step 104 is executed, it is determined whether or not the instantaneous current phase value (angle) calculated in step 103 crosses the low-pass filter value (angle), which is the low-pass processing value calculated in step 104, from the smaller to the larger ( Step 105). That is, it is determined whether or not the instantaneous current phase value has passed the low-pass processing value.

  If it is determined in step 105 that the instantaneous current phase value does not cross the low-pass processing value from the smaller value to the larger value, the process returns to step 102 to newly acquire the U-phase current value iu and the V-phase current value iv. To do.

  If it is determined in step 105 that the instantaneous current phase value has crossed the low-pass processing value from a smaller value to a larger value, the control switching condition calculation unit 24 sends a signal indicating that the control switching condition is satisfied to the control switching unit 25. Then, the control switching unit 25 switches the control from the other control operation control by the other control control unit 22 to the self control operation control by the self control control unit 23 (step 106).

  Thereafter, efficient self-sustained operation control in which a voltage is applied to the stator coil by a voltage amplitude / voltage phase command based on the estimated position of the rotor is continued (step 107). The control executed here is so-called position sensorless control.

  Here, step 101 is the other control operation step in this embodiment, and step 107 is the self-control operation step in this embodiment. Steps 102 to 106 are operation switching steps in this embodiment.

  According to the above-described configuration and control operation, during other braking operation, the phase of the current vector i advances in the direction of increasing the phase angle with respect to the d-axis that is the magnetic pole axis of the rotor, and the instantaneous current phase value is the low-pass processing value. When crossing from small to large, the control can be switched from other control operation to self-control operation.

  During other control, when the torque fluctuation of the compression mechanism 11 driven by the synchronous motor 12 is large, the rotational position of the rotor vibrates (vibrates in the rotational direction while the rotor rotates), and FIG. As shown in FIG. 4, the phase of the current vector also vibrates in the A direction and the B direction (changes in a vibrational manner) like the vector indicated by the broken line.

  Then, at the moment (immediately after) the current vector i fluctuates in the A direction in which the phase angle increases and passes the low-pass filter value (for example, the vector at the position indicated by the solid line), the control is switched from the other control operation to the self control operation. It is.

  At the time of self-control operation control, the current vector of the stator coil is controlled, for example, as shown by a two-dot chain line in FIG. 6 so that the synchronous motor 12 is operated more efficiently than at the time of other control operation control. The phase angle is larger than that during other control.

  Therefore, the direction in which the phase of the instantaneous current vector increases the phase angle with respect to the d-axis even when the load torque driven by the synchronous motor 12 has a large variation and the rotor has a vibrational variation in the rotational direction. The operation control can be switched from the other control operation to the self-controlled operation in which the phase angle of the current vector is further increased when the low-pass processing value is crossed from the smaller one to the larger one.

  As a result, when the synchronous motor 12 is started, the control can be smoothly switched by continuous movement from the other control operation to the self-control operation, and an efficient operation state can be quickly reached.

  When the torque fluctuation of the load is large, the rotor is rotating in the passive control mode, and the current phase is oscillating, the current amplitude is reduced, etc. If an attempt is made to shift from other control to self-control by approaching the condition where the estimated positions are equal, vibration may not be suppressed in a region where the current amplitude is small, and the step-out may occur.

  Therefore, as in this embodiment, it is desirable to perform control switching from other control operation to self-control operation under the condition before the current amplitude is reduced, and the control change can be smoothly performed by continuous movement from other control operation to self-control operation. What you can do is extremely effective.

  Moreover, immediately after the phase of the instantaneous current vector exceeds the low-pass filter value, that is, immediately after the phase angle of the current vector becomes equal to or greater than the low-pass processing value, the operation control can be switched from the other control operation to the self-control operation. it can.

  Therefore, when the torque of the synchronous motor 12 is not substantially excessive or deficient with respect to the required average torque, the operation control can be switched from the other operation to the self operation. As a result, it is possible to prevent the synchronous motor 12 from stepping out and stopping at the time of control switching due to torque shortage, or taking time to shift to an efficient operating state, and overshoot or the like occurs due to excessive torque. Thus, it is possible to prevent the time required for shifting to an efficient operation state.

  Further, although the U-phase current value iu and the V-phase current value iv are employed as the actual state quantities of the synchronous motor 12 acquired for the control switching determination, at least one of the phases of the stator coil (this In the example, it is necessary to detect the phase current flowing in the U phase and the V phase). Therefore, it is not necessary to provide a dedicated sensor for detecting the phase current value for control switching determination.

  The control switching determination is performed by detecting a point where the instantaneous current phase crosses the low-pass filter value. Therefore, it is possible to easily and accurately determine control switching.

  Moreover, the load which the synchronous motor 12 of the electric compressor 10 drives is the compression mechanism 11 for compressing the refrigerant | coolant which circulates during a heat pump cycle. In the compression mechanism that compresses the refrigerant, the load torque is likely to fluctuate greatly depending on the state of the refrigerant in the cycle and the suction compression / discharge cycle. Therefore, in this embodiment, when the synchronous motor 12 that drives the compression mechanism 11 is started, the control can be smoothly switched from the other control operation control to the self-control operation control, and an efficient operation state can be quickly reached. Very large.

  Here, an operation example of operation control switching in the synchronous motor activation control of the present embodiment will be described with reference to FIG. FIG. 7 is a graph showing the relationship between the instantaneous value of the current vector phase and the low-pass filter value when the operation control is switched. Note that the calculation of the low-pass filter value is stopped after the control switching, and is fixed to the value at the time of the control switching.

  As shown in FIG. 7, the synchronous motor 12 is started by other braking operation control and is operated up to a predetermined condition. After reaching the predetermined condition, the instantaneous value of the current vector phase is compared with the low-pass filter value. First, the instantaneous value crosses the low-pass filter value from the smaller one to the larger one (the instantaneous value line in FIG. When it is detected that the low-pass filter value line has been crossed), the control is smoothly switched from the other control operation control to the self-control operation control.

  As shown in FIG. 7, the direction in which the instantaneous value of the current vector crosses the low-pass filter value is the same as the direction of transition to the current phase at the time of self-sustained operation control after control switching (current phase operation direction, see FIG. 6). Because of the direction, the control can be smoothly switched from the other control operation control to the self control operation control. Thereafter, an efficient driving state by the self-control operation control is continued.

  Here, with reference to FIG. 8, the self-limiting operation control operation of Step 107 which is the self-control operation control step in this embodiment will be described.

  As shown in FIG. 8, when control switching is performed in step 106, self-sustained operation control is executed in step 107. In step 107, voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil continues to match the steady operation target current phase determined based on the motor efficiency or its related value or the motor torque or its related value. In order to shift the phase of the current vector from the phase of the current vector flowing in the stator coil at the time when the operation control switching is performed to the steady operation target current phase, the steady operation step (step 107C) for performing the steady operation of applying The transition operation step (step 107A) is performed before the steady operation step 107C.

  Here, the steady operation does not mean an operation in which the applied voltage is always constant, but an operation in which the self-limiting operation control (position sensorless operation control) is stably continued based on the estimated position of the rotor. The transition operation is an operation for shifting the current vector immediately after the control switching from the other control operation to the self-control operation is performed to the steady operation of the self-control operation. An operation is performed in which a voltage is applied to the stator coil so that the phase of the current vector flowing through the coil matches the transition operation target current phase.

  The steady operation target current phase is determined based on the motor efficiency or its related value or the motor torque or its related value, but the related value of the motor efficiency includes, for example, iron loss, copper loss, The related value of the motor torque includes a current command value.

  When the control in step 107 is started, first, calculation of the motor state quantity at the start of the self-control operation (that is, at the time of control switching) is performed (step 1071). Specifically, state quantity information such as the rotational speed, current, voltage, and current phase is calculated based on the acquired actual current value and the like.

  Next, the instantaneous current phase calculated in step 1071 is set as the transition operation target current phase (substituted in the transition operation target current phase) (step 1072), and the phase of the current vector flowing in the stator coil in this transition operation target current phase A voltage is applied to the stator coil so that the two match.

  Then, it is determined whether or not the transition operation target current phase has reached the steady operation target current phase (step 1073), and when it is determined that the transition operation target current phase has not reached the steady operation target current phase, The transition operation target current phase is updated by increasing a predetermined angle until the steady operation target current phase is reached (step 1074), and the transition operation is continued.

  If it is determined in step 1073 that the transition operation target current phase has reached the steady operation target current phase, the transition operation is performed when the current phase reaches the transition operation target current phase (which is also the steady operation target current phase at this time). The steady operation control is executed to apply a voltage to the stator coil so that the state where the phase of the current vector flowing through the stator coil coincides with the steady operation target current phase continues (step 107C).

  Step group 107A shown in FIG. 8 is a transition operation step in the present embodiment and corresponds to a transition operation control means in the motor control device, and step 107C is a steady operation step in the present embodiment, and the motor control device. Corresponds to the steady operation control means.

  In the transition operation step 107A, the transition operation target current phase is set so as to gradually change stepwise toward the steady operation target current phase. Therefore, the transition operation target current phase is steady from the time point when the operation control is switched to the self-regulation operation. In the transition operation up to the point of operation, the motor control state can be changed continuously, that is, smoothly.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS.

  The second embodiment is different from the first embodiment described above in the operation of the transition operation control in the self-control operation control. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 9, in this embodiment, when the motor state quantity at the start of the self-control operation is calculated in Step 1071, the steady operation target current phase is set as the transition operation target current phase (the transition operation target current phase is changed to the transition operation target current phase). (Step 1076). Then, the control state quantity at the start of steady operation is calculated from the state quantity calculated in step 1071 and the steady operation target current phase used in step 1076 (step 1077). Specifically, when the current vector phase at the start of the self-control operation (at the start of the transition operation) is advanced to the current vector phase at the time of starting the steady operation (that is, when the steady operation target current phase is set), the motor at both time points The magnitude of the current value at the start of steady operation (the absolute value of the current vector) is calculated so that the torque is substantially the same.

  Then, the control state quantity at the start of steady operation calculated in step 1077 so that the phase of the current vector flowing in the stator coil matches the transition operation target current phase set in step 1076 (that is, the steady operation target current phase). Then, a voltage is applied to the stator coil.

  The above is the transition operation step 107B in the present embodiment, and when the transition operation step 107B is executed, the voltage is applied to the stator coil so that the state in which the phase of the current vector flowing in the stator coil matches the steady operation target current phase continues. The applied steady operation control is executed (step 107C).

  Step group 107B shown in FIG. 9 is a transition operation step in the present embodiment and corresponds to a transition operation control means in the motor control device, and step 107C is a steady operation step in the present embodiment, and the motor control device. Corresponds to the steady operation control means.

  In the transition operation step 107B, the steady operation target current phase is set as the transition operation target current phase from the beginning of the transition operation, and the torque error due to the rotor estimated position error can be suppressed. It is possible to switch the control from the other control operation to the self-control operation control under a condition that is difficult.

  In the method of setting the transition operation target current phase so as to gradually change stepwise toward the steady operation target current phase as in the first embodiment described above, if a rotor estimated position error is generated, A large error (large variation) may occur in the motor torque. That is, a large torque shortage may occur.

  On the other hand, in this embodiment, when control switching is performed, at the start of the transition operation, the state (the magnitude of the current value, etc.) calculated based on the steady operation target current phase and the steady operation target current phase is instantaneously The target value is switched to change the motor state quickly.

  FIG. 10 is a block diagram showing the relationship of the speed control system. In FIG. 10, a torque equation 112 represents the transfer characteristic from the current command to the torque, and a motor transfer characteristic 113 represents the transfer characteristic from the torque to the actual speed.

  In the speed control system shown in FIG. 10, the speed controller (controller such as PI control) 111 performs control so that the actual speed follows the speed command from the host control unit or the like. And the current phase θc is controlled so as to satisfy the torque characteristics.

For example, when the torque is τ, the current command is ia, the current phase is θc, and the torque constant is Kt, the torque formula is expressed by the following formula 2.
(Equation 2)
τ≈Kt × ia × sin θc
Here, since the right side of the torque equation is represented only by magnet torque and the reactance torque term is omitted, in Equation 1, both sides are connected by “≈”.

  From this equation, it can be seen that if the current phase θc has an error in the vicinity of 0 degrees, a large error is likely to occur in the torque. Since the current phase θc is directly connected to (directly related to) the rotor estimated position error, the rotor estimated position error leads to a large torque error. On the other hand, when the current phase θc is set to about 90 degrees, as is apparent from the above torque equation, the torque error caused by the rotor estimated position error can be reduced, and control switching is performed under the condition that the torque is not insufficient. Can be performed.

  As shown in FIG. 11, when control switching is performed from other braking operation control to autonomous driving control, the target value of the current phase (transition operation target current phase) is instantaneously changed to the target current phase during steady operation at the switching point. Switch (change). Along with this, the current phase rapidly increases (advances) as shown by the thick solid line, and more gradually than when the transition operation target current phase is gradually increased and the current phase is gradually increased as shown by the broken line. Thus, it is possible to shift to a steady operation by a short transition operation.

  As described above, the current phase θc after the control switching is quickly shifted to the final target current phase (at the time of steady operation), and the state where the current phase θc is in the vicinity of 0 degrees is reduced as much as possible. Even if there is, it is possible to perform control switching that is unlikely to cause torque shortage.

  For example, if the current phase θc is 10 degrees and the control is switched in that state, if the estimated rotor position error is 10 degrees, the torque has an error of about 17%, and a large torque shortage occurs after the control switching. there is a possibility.

  On the other hand, for example, when the current phase θc is 90 degrees, even if the rotor estimated position error is 10 degrees, the torque error can be suppressed to about 2%. Thereby, it is possible to switch the control under the condition that the torque shortage hardly occurs.

  Thus, even if the estimated rotor position information has an error, the torque error is suppressed, and the possibility of control switching failure can be reduced.

(Other embodiments)
In each of the above embodiments, as shown in FIG. 4, the case where the rotation direction of the rotor is set to the counterclockwise direction has been described, but it is needless to say that the rotation direction of the rotor may be a clockwise direction. is there.

  As shown in FIG. 12, even when the rotation direction of the rotor is clockwise, the phase of the current vector i is increased in the A direction to increase the phase angle with respect to the d axis, which is the magnetic pole axis of the rotor, during other braking operation. When the instantaneous current phase value crosses the low-pass processing value from the smaller one to the larger one, that is, the instantaneous current vector swings in the A direction (the same direction as the rotor rotation direction) increasing the phase angle. When the value is overtaken, control switching from other control operation to self-control operation may be performed.

  Further, in each of the above embodiments, during other control operation, the phase of the current vector i proceeds in the direction of increasing the phase angle with respect to the d-axis, and the instantaneous current phase value crosses the low-pass processing value from the smaller one to the larger one. However, immediately after the phase angle of the current vector i becomes equal to or greater than the low-pass processing value, the control is switched from the other control operation to the self-control operation, but the phase angle of the current vector i becomes the low-pass processing value. On the other hand, when the state is equal to or greater than that (for example, when the instantaneous value line shown in FIG. 7 is an area rising above the low-pass filter value line), the control is switched from the other control operation to the self-control operation. May be.

  According to this, when the torque of the synchronous motor 12 is not insufficient with respect to the required average torque, the operation control can be switched from the other control operation to the self-control operation. Therefore, it is possible to prevent the synchronous motor 12 from stopping due to a step-out at the time of control switching or taking time to shift to an efficient operating state.

  Further, during other braking operation, the phase of the current vector i is in the direction of increasing the phase angle with respect to the magnetic pole axis of the rotor (for example, the region where the instantaneous value line shown in FIG. 7 is rising). When this is detected, the driving control may be switched from the other driving to the autonomous driving.

  According to this, the control switching can be performed when the phase of the current vector i is in the direction of transition to the current phase during the self-control operation control after the control switching, and the control switching is smoothly performed by continuous movement. be able to.

  Further, in each of the above embodiments, control switching is performed based on the progress state of the phase of the current vector i during other braking operation, but the d-axis current id and the q-axis component, which are the d-axis components of the current vector i, are used. Control switching may be performed based on at least one of a certain q-axis current iq. That is, it is possible to detect the progress of the phase of the current vector based on at least one of the d-axis current id and the q-axis current iq and perform control switching.

  As described in the above embodiments, the phase of the current vector i with respect to the magnetic pole axis of the rotor is the magnetic pole axis component (d-axis current id) of the current vector obtained by rotating coordinate conversion of the acquired current information, and It is obtained from the magnetic pole axis orthogonal component (q-axis current iq). Therefore, if the progress state of the phase of the current vector i is detected based on at least one of the d-axis current id and the q-axis current iq, the arithmetic processing can be simplified.

  When the d-axis current id is used, a low-pass filter value of the d-axis current id is calculated, and control switching may be performed when the d-axis current id is decreasing. Preferably, in addition to this, when the d-axis current value id is smaller than the low-pass filter value, more preferably, control switching may be performed immediately after the d-axis current value id becomes smaller than the low-pass filter value.

  When the q-axis current iq is used, a low-pass filter value of the q-axis current iq is calculated, and control switching may be performed when the q-axis current iq is increasing. Preferably, in addition to this, when the q-axis current iq is larger than the low-pass filter value, more preferably, control switching may be performed immediately after the q-axis current iq becomes larger than the low-pass filter value.

  In addition, at least one of the d-axis current id and the q-axis current iq may be used, and the control switching may be determined by adding the phase of the current vector i.

  Moreover, in each said embodiment, although the state quantity measured of the synchronous motor 12 acquired by step 102 was made into the phase current value which flows into a stator coil, it is not limited to this. For example, the actually measured state quantity may be a related current value of a phase current value such as a line current value that can be handled equivalently to the phase current value, or may be voltage information acquired from the inverter circuit 16 or the like. .

  In the above embodiments, the description of the type of the compression mechanism 11 driven by the synchronous motor 12 is omitted, but various types of compression mechanisms such as a rotary type, a piston type, and a scroll type can be adopted. When the rotary type compression mechanism is employed, the rotary type compression mechanism is particularly effective when the control switching of the present invention is applied because the torque fluctuation during driving is relatively large.

  Moreover, in each said embodiment, although the synchronous motor 12 was a 4 pole 3 phase motor, the number of poles and the number of phases are not limited to this.

  Moreover, in each said embodiment, although the synchronous motor 12 was a motor which drives the compression mechanism 11 of the heat pump cycle which uses a carbon dioxide as a refrigerant | coolant, it is not limited to this. The refrigerant may be a compressor motor of a heat pump cycle (refrigeration cycle) other than carbon dioxide, and the load may be a pump mechanism or the like instead of the compression mechanism. The present invention is widely applied and effective when controlling the operation of a synchronous motor without using a position sensor.

It is a block diagram which shows schematic structure of the synchronous motor 12 and the control apparatus 20 of the electric compressor 10 in 1st Embodiment. 4 is a flowchart showing a schematic control operation during motor start control of the control device 20. It is a figure which defines the relationship between the position of each phase (U, V, W phase) of a stator coil, and the fixed coordinate which consists of (alpha) and (beta) axis | shaft. It is a figure which defines the rotation coordinate which consists of d axis which is a rotor magnetic pole axis on the basis of (alpha) and (beta) axis, and q axis orthogonal to d axis. It is a figure which shows the relationship between the phase angle of the electric current vector i, d-axis current id, and q-axis current iq. It is a figure for demonstrating the state of the current vector at the time of performing control switching. It is a figure which shows the operation example of the operation control switching in synchronous motor starting control. It is a flowchart which shows the general | schematic control operation after control switching to the self-control operation | movement of the control apparatus 20 in 1st Embodiment. It is a flowchart which shows the general | schematic control operation after control switching to the self-control operation | movement of the control apparatus 20 in 2nd Embodiment. It is a block diagram which shows the relationship of a speed control system. It is a figure which shows the operation example of the operation control switching in 2nd Embodiment. It is a figure for demonstrating the state of the current vector at the time of performing control switching in other embodiment.

Explanation of symbols

10 Electric compressor 11 Compression mechanism (load)
12 Synchronous motor 16 Inverter circuit 20 Controller 22 Other control unit (Other control operation control means)
23 Self-control control part (self-control operation control means)
24 Control switching condition calculation unit (part of operation control switching means)
25 Control switching part (part of operation control switching means)

Claims (14)

Synchronous operation for controlling the operation of a synchronous motor (12) for driving a load (11) by outputting a voltage command to be applied to a stator coil composed of a plurality of phases without using a position sensor for detecting the position of the rotor. A method for controlling a motor,
Other braking operation step (101) for starting the operation of the synchronous motor by other braking operation in which a voltage is applied to the stator coil according to a predetermined voltage amplitude / frequency command regardless of the position of the rotor;
After the other braking operation step (101), a voltage is applied to the stator coil by a voltage amplitude / voltage phase command based on the estimated position of the rotor, and the synchronous motor is controlled by a self-limiting operation that controls a current vector flowing through the stator coil. A self-control operation step (107) for continuing the operation of
During the other control operation, when it is detected that the phase of the current vector is progressing in the direction of increasing the phase angle with respect to the magnetic pole axis of the rotor, the operation control from the other control operation to the self-control operation is performed. And a driving switching step (102 to 106) for switching the motor.   In the operation switching step (102 to 106), a low-pass processing value obtained by low-pass processing the phase angle of the current vector is calculated, and when the phase angle of the current vector is equal to or greater than the low-pass processing value, the other The synchronous motor control method according to claim 1, wherein the operation control is switched from the braking operation to the autonomous driving.   3. In the operation switching step (102 to 106), when the phase angle of the current vector exceeds the low-pass processing value, the operation control is switched from the other control operation to the self-control operation. The control method of the synchronous motor of description.   In the operation switching step (102 to 106), the progress state of the phase of the current vector is detected based on at least one of the component in the magnetic pole axis direction and the component in the direction orthogonal to the magnetic pole axis of the current vector. The method for controlling a synchronous motor according to any one of claims 1 to 3, wherein:   The method of controlling a synchronous motor according to any one of claims 1 to 4, wherein the load (11) is a compression mechanism (11) for compressing a refrigerant circulating during a heat pump cycle. The self-control operation step (107) includes:
A voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil continues to match the steady operation target current phase determined based on the motor efficiency or its related value or the motor torque or its related value. A steady operation step (107C) for performing steady operation;
In order to shift the phase of the current vector from the phase of the current vector flowing through the stator coil to the steady operation target current phase at the time when the operation control switching to the self-controlled operation is performed in the operation switching step (102 to 106). , And a transition operation step (107A) executed before the steady operation step (107C),
In the transition operation step (107A), a transition operation target current phase is set, and a transition operation is performed in which a voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil matches the transition operation target current phase. What to do,
6. The transition operation step (107A), wherein the transition operation target current phase is set so as to change stepwise toward the steady operation target current phase. The control method of the synchronous motor as described in 2. The self-control operation step (107) includes:
A voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil continues to match the steady operation target current phase determined based on the motor efficiency or its related value or the motor torque or its related value. A steady operation step (107C) for performing steady operation;
In order to shift the phase of the current vector from the phase of the current vector flowing through the stator coil to the steady operation target current phase at the time when the operation control switching to the self-controlled operation is performed in the operation switching step (102 to 106). And a transition operation step (107B) executed before the steady operation step (107C),
In the transition operation step (107B), a transition operation target current phase is set, and a transition operation is performed in which a voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil matches the transition operation target current phase. What to do,
6. The transition operation step (107B), wherein the steady operation target current phase is set as the transition operation target current phase from the beginning of the transition operation. The control method of the synchronous motor of description. Synchronous operation for controlling the operation of a synchronous motor (12) for driving a load (11) by outputting a voltage command to be applied to a stator coil composed of a plurality of phases without using a position sensor for detecting the position of the rotor. A motor control device,
Other braking operation control means (22) for driving the synchronous motor (12) by other braking operation control for outputting a predetermined voltage amplitude / frequency command and applying a voltage to the stator coil regardless of the position of the rotor; ,
The synchronous motor (12) is operated by a self-running control that outputs a voltage amplitude / voltage phase command based on the estimated position of the rotor, applies a voltage to the stator coil, and controls a current vector flowing through the stator coil. Self-control operation control means (23);
After the operation of the synchronous motor (12) is started by the other braking operation by the other braking operation control means (22), the phase of the current vector proceeds in a direction to increase the phase angle with respect to the magnetic pole axis of the rotor. When it is detected that the motor is in a state, the operation control of the synchronous motor (12) is changed from the other-branch operation control by the other-branch operation control means (22) to the self-regulatory operation control by the self-regulatory operation control means (23). A control device for a synchronous motor, comprising: an operation control switching means (24, 25) for switching.   The operation control switching means (24, 25) calculates a low-pass processing value obtained by low-pass processing the phase angle of the current vector, and when the phase angle of the current vector is equal to or greater than the low-pass processing value, The synchronous motor control device according to claim 8, wherein the operation control is switched from the other operation control by the other operation control means (22) to the self operation operation control by the self operation control means (23).   When the phase angle of the current vector exceeds the low-pass processing value, the operation control switching means (24, 25) is changed from the other control operation control by the other control operation control means (22) to the self-control operation control means ( The synchronous motor control device according to claim 9, wherein the operation control is switched to the self-controlled operation control according to 23).   The operation control switching means (24, 25) detects the progress state of the phase of the current vector based on at least one of the component in the magnetic pole axis direction and the component in the direction perpendicular to the magnetic pole axis of the current vector. 11. The synchronous motor control device according to claim 8, wherein the control device is a synchronous motor control device.   The synchronous motor control device according to any one of claims 8 to 11, wherein the load (11) is a compression mechanism (11) for compressing a refrigerant circulating during a heat pump cycle. The self-control operation control means (23)
A voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil continues to match the steady operation target current phase determined based on the motor efficiency or its related value or the motor torque or its related value. A steady operation control means (107C) for performing steady operation,
Transition operation for shifting the phase of the current vector from the phase of the current vector flowing in the stator coil to the steady operation target current phase at the time when the operation control switching means (24, 25) switches the operation control to the self-controlled operation. Transition operation control means (107A) for performing
The transition operation control means (107A) sets a transition operation target current phase, applies a voltage to the stator coil so that the phase of the current vector flowing in the stator coil matches the transition operation target current phase, and To perform transitional operation,
13. The transition operation control means (107A) sets the transition operation target current phase so as to change stepwise toward the steady operation target current phase. A control device for a synchronous motor according to claim 1. The self-control operation control means (23)
A voltage is applied to the stator coil so that the phase of the current vector flowing in the stator coil continues to match the steady operation target current phase determined based on the motor efficiency or its related value or the motor torque or its related value. A steady operation control means (107C) for performing steady operation,
Transition operation for shifting the phase of the current vector from the phase of the current vector flowing in the stator coil to the steady operation target current phase at the time when the operation control switching means (24, 25) switches the operation control to the self-controlled operation. Transition operation control means (107B) for performing
The transition operation control means (107B) sets a transition operation target current phase, applies a voltage to the stator coil so that the phase of the current vector flowing through the stator coil matches the transition operation target current phase, and To perform transitional operation,
The transition operation control means (107B) sets the steady operation target current phase as the transition operation target current phase from the beginning of the transition operation. The control apparatus of the synchronous motor as described in 2.

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