JP3764011B2 - Permanent magnet synchronous motor controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a permanent magnet synchronous motor that includes a stator having armature windings and a rotor having permanent magnets and is driven by an AC power supply.
[0002]
[Prior art]
For example, as disclosed in JP-A-4-4741 and JP-A-4-91651, this type of permanent magnet synchronous motor has been conventionally applied in various fields. The rotor does not require a field winding, and there is an advantage that a constant rotation speed can be obtained with high efficiency without causing copper loss in the rotor.
The drive operation including starting of the permanent magnet synchronous motor is performed by an AC power source having a variable voltage and a variable frequency from an inverter.
[0003]
[Problems to be solved by the invention]
As described above, since the conventional permanent magnet synchronous motor is premised on driving by an inverter, the inverter has a voltage, current, and frequency fluctuation range necessary for achieving the rated load operation from the starting operation of the permanent magnet synchronous motor. There was a problem that it had to have a capacity to cover the battery, and it was large and expensive.
The present invention has been made to solve the above-described problems, and an object thereof is to obtain a permanent magnet synchronous motor control device that can be realized with high efficiency and low cost.
[0004]
[Means for Solving the Problems]
The permanent magnet synchronous motor control device according to the present invention is a voltage that controls the voltage applied to the armature winding by applying a voltage that is adjusted in a fluctuation range smaller than the voltage of the AC power supply in series to the armature winding. Control means is provided, and by controlling the voltage applied to the armature winding by the voltage control means, the power factor of the motor viewed from the AC power supply side can be adjusted.
[0005]
The permanent magnet synchronous motor control device according to the present invention further includes power factor detection means on the AC power supply side, and is applied to the armature winding by the voltage control means so that the power factor detection value becomes a predetermined set value. The voltage to be controlled is controlled.
[0006]
Further, the permanent magnet synchronous motor control device according to the present invention inserts the AC output terminal of the three-phase inverter at the neutral point side of the armature winding of the three-phase Y connection, and supplies the AC output voltage of the three-phase inverter. By controlling, the voltage applied to the armature winding is controlled.
[0007]
The permanent magnet synchronous motor control device according to the present invention includes a first opening / closing means inserted between the AC power source and the armature winding, a load side terminal of the first opening / closing means, and the armature. A second opening / closing means for short-circuiting the three phases with the winding;
When the first opening / closing means is open and the second opening / closing means is closed, the motor is started by controlling the frequency and voltage of the AC output of the three-phase inverter. The voltage applied to the armature winding is controlled by closing the open / close means and opening the second open / close means and controlling the voltage of the AC output of the three-phase inverter at the frequency of the AC power supply. It is a thing.
[0008]
Further, the permanent magnet synchronous motor control device according to the present invention comprises switching means for configuring each phase AC output side of the three-phase inverter with a plurality of units and switching connection of these units in series or in parallel.
When starting the motor by controlling the frequency and voltage, connect the units in series.When adjusting the power factor of the motor by controlling the voltage with the frequency of the AC power supply, connect the units in parallel. It is a thing.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a circuit configuration diagram showing a permanent magnet synchronous motor and its control apparatus according to Embodiment 1 of the present invention. In the figure, reference numeral 1 denotes a commercial power source which is an AC power source having a three-phase commercial frequency, and reference numeral 2 denotes a three-phase Y-connected armature connected to the commercial power source 1 via a three-phase switch 3 as a first switching means. The windings 4 are three-phase inverters whose three-phase AC output terminals are connected to the neutral point side of the armature winding 2, and details thereof will be described later.
3A is an operation unit for operating opening and closing of the switch 3, and 5 is a three-phase switch as a second switching means for short-circuiting the three phases between the load side terminal of the switch 3 and the armature winding 2, Reference numeral 5A denotes an operation unit for operating opening / closing of the switch 5.
[0010]
Reference numeral 6 denotes a voltage detector that detects the voltage of the commercial power source 1, reference numeral 7 denotes a voltage detector that detects the voltage at the load side terminal of the switch 3, and reference numeral 8 denotes a current detector.
9 is an operation mode switch, 10 is a power factor command device, 11 is a power factor detector as power factor detection means for detecting the power factor from the outputs of the voltage detector 7 and the current detector 8, 12 is a subtractor, 13 Is a control device that controls the inverter 4 based on each input and sends an opening / closing command to the operation units 3A and 5A of the switches 3 and 5.
[0011]
FIG. 2 shows a detailed configuration of the inverter 4 of FIG. 1, which mainly discloses portions related to the inverter 4 and omits other portions as appropriate. In the figure, 14 is a transformer for supplying AC input from the commercial power source 1 to the inverter 4. As shown in the figure, the inverter 4 is composed of three inverter units 40, 50, 60 in each phase, and is provided on the AC output side of the inverters 41-44 using contact type or semiconductor switches. 51 to 54 and 61 to 64, the AC output can be switched in series / parallel for each phase.
[0012]
FIG. 3 is a diagram showing the internal configuration of each inverter unit 40, 50, 60 in FIG. 2. Here, an IGBT is adopted as a switching element, and the three-phase AC voltage from the transformer 14 is converted to DC by PWM control. And a converter unit for converting the direct current into an alternating voltage having a predetermined frequency and voltage. Since this is a known configuration per se, a detailed description thereof will be omitted.
[0013]
Here, before entering into a detailed description of the operation, the basic operation principle of the permanent magnet synchronous motor control device according to the present invention will be described with reference to FIG.
First, FIG. 2A shows the most simplified equivalent circuit of a permanent magnet synchronous motor. In the figure, the meaning of each symbol is as follows.
VM: Voltage generated by the rotation of the rotor of the permanent magnet. If the rotation speed is constant, the magnitude of VM is also constant. X: Reactance of the permanent magnet synchronous motor I: Armature current IX of the permanent magnet synchronous motor: Voltage V generated by product of reactance X and armature current I: terminal voltage of permanent magnet synchronous motor
FIG. 4B represents each of the above elements in a vector diagram. Here, the armature current I is assumed to be delayed by an angle θ with respect to the terminal voltage V.
By the way, when the voltage / current characteristics of the permanent magnet synchronous motor are obtained, the load size is used as a parameter, and the tendency is as shown in FIG. 4 (c). A voltage exists.
[0015]
Considering this phenomenon in the vector diagram of FIG. 4B, if the magnitude of the terminal voltage V is changed under the condition that the vector VM + the vector IX = the vector V and the magnitude of the voltage VM is constant, IX The direction and magnitude as a vector change dependently, and the phase difference θ between the terminal voltage V and the armature current I and the magnitude of the armature current I change.
[0016]
The present invention was made in view of the above phenomenon, and by controlling the voltage applied to the armature winding by adjusting the voltage of a predetermined fluctuation range to the AC power supply voltage, Improvements have been made to reduce the copper loss of the stator by reducing the current, realizing high-efficiency operation. As can be seen from FIG. 4C, the fluctuation range of the voltage to be changed in order to minimize the current may be sufficiently smaller than the value of the entire AC power supply voltage. For example, a voltage fluctuation width of about 30% is sufficient. Therefore, the capacity of the voltage control means for changing the voltage can be small.
[0017]
Next, returning to FIGS. 1 to 3, the operation of the permanent magnet synchronous motor control device according to the present invention will be described. In the first embodiment, the inverter 4 used for controlling the armature winding voltage in a predetermined range for power factor adjustment described in the above operating principle is used at the start of the motor. The start winding can be omitted.
[0018]
Hereinafter, description will be given with reference to the timing chart of FIG. First, the starting operation will be described. When the operation mode switch 9 is set to the start mode, in response to the instruction, the control device 13 sends a signal to the operation units 3A and 5A to open the switch 3 and close the switch 5. That is, the connection with the commercial power source 1 is disconnected and the three-phase input side terminal of the armature winding 2 is short-circuited. Further, an operation signal (not shown) is sent to the changeover switches 41 to 64 of the inverter 4, and the AC output side of each inverter unit 40, 50, 60 is connected in series.
[0019]
Under the above circuit connection conditions, a control signal is sent from the control device 13 to the inverter 4, the output of the inverter 4 is raised, its frequency and voltage are gradually increased, and the permanent magnet synchronous motor is stopped from the commercial power supply 1 Increase the rotational speed to the synchronous speed determined by. It is necessary to increase the voltage of the inverter 4 as the rotational speed increases (from time T0 to time T1 in FIG. 5).
[0020]
Since the rotation speed is gradually increased continuously, it is not necessary to pass a large current through the armature winding 2, and the inverter 4 may be rated for a high voltage and a small current (Vs, Is). That is, the configuration in which the inverter units 40 and the like are all connected in series in each phase is convenient for obtaining this high voltage and small current AC output.
[0021]
When the rotation speed of the permanent magnet synchronous motor reaches the rated value (time T1 in FIG. 5), the operation mode switch 9 is switched to the operation mode, thereby opening the switch 5 and operating the changeover switch 41 of the inverter 4 and the like. Thus, the inverter unit 40 and the like are connected in parallel. A state in which the voltage and phase of the armature winding 2 detected by the voltage detector 7 and the voltage and phase of the commercial power source 1 detected by the voltage detector 6 are matched with each other within a predetermined allowable range. Then, the switch 3 is closed and the armature winding 2 is connected to the commercial power source 1. Thereafter, the operation of the load machine driven by the permanent magnet synchronous motor is started. For example, when the pulverizer is a load machine, an object to be crushed is input to reach the rated load (time T2 in FIG. 5).
[0022]
In the example shown in FIG. 5, after the rated load continues from time T2, the load decreases from time T3. As the load decreases, the power factor changes as shown in FIG. The power factor detector 11 detects this change in power factor from the detection outputs of the voltage detector 7 and the current detector 8. Then, the deviation between the detected power factor value and the high power factor value set by the power factor commander 10 is obtained by the subtractor 12, and the feedback control makes the controller 13 so that the deviation becomes zero. The output voltage of the inverter 4 is controlled so that the rate approaches 1. As a result, as shown in FIG. 5 (d), after time T3, the inverter 4 outputs the voltage in the direction of decreasing the voltage of the armature winding 2, the power factor is increased, and the armature winding current is increased. It decreases (FIG. 5 (e)).
That is, highly efficient operation is always realized.
[0023]
The output of the inverter 4 in this operation mode is rated for low voltage and large current (Vp, Ip), but in this mode, the inverter unit 40 and the like are all connected in parallel in each phase, so there is no problem.
That is, in the first embodiment, high efficiency operation is realized by controlling the power factor, and the inverter 4 required for this is constituted by a plurality of inverter units, and the start which uses high voltage and small current is performed. In this mode, these inverter units are connected in series, and in the operation mode (power factor control is performed) where low voltage and large current are used, these inverter units are connected in parallel. It is possible to apply a low-priced inverter that is limited to the above.
[0024]
Embodiment 2. FIG.
In the first embodiment, the inverter 4 is used for both the starting operation of the permanent magnet synchronous motor and the power factor control operation in the operation mode. However, the starting winding is provided in the rotor of the permanent magnet synchronous motor. In this case, the inverter can be designed only for power factor control in the operation mode. In this case, the changeover switch 41 and the like are not required, and the configuration is simplified and the configuration of the inverter unit is also necessary. It can be optimized according to the rating.
Of course, although there is a starting winding and self-starting can be performed with the commercial power supply 1, if a large starting current is not desired to flow, the same configuration as in the first embodiment may be used.
[0025]
Further, in the first embodiment, the inverter unit is configured to be switched in series and parallel with three phases for each phase, but the voltage required at the start, the current specification, and the voltage required at the power factor control in the operation mode, Of course, various numbers such as two or four for each phase may be selected according to the current specification, and in this case, the same effect as described above can be obtained.
[0026]
Further, the inverter unit of the first embodiment is an IGBT that transforms and insulates from the commercial power source 1 through the transformer 14 and introduces AC power, and converts the three-phase AC to DC as shown in FIG. It is composed of a PWM converter, a DC link unit using a capacitor, a PWM converter using an IGBT that converts direct current to single-phase alternating current, and a reactor for preventing a short circuit between units when connected in parallel. As long as it is a converter that can be used for both connection and parallel connection and can control the frequency and voltage, it may have a configuration different from that shown in FIG.
Further, the input of the inverter is not necessarily introduced from the commercial power supply 1, but another power supply may be used.
[0027]
Furthermore, the voltage control means for controlling the voltage applied to the armature winding by adding or subtracting a voltage having a predetermined fluctuation range to the voltage of the commercial power supply is not limited to the inverter, and includes, for example, a voltage changing means. You may make it comprise with a transformer.
[0028]
【The invention's effect】
As described above, the permanent magnet synchronous motor control device according to the present invention applies to the armature winding by applying a voltage that is increased or decreased in a fluctuation range smaller than the voltage of the AC power supply in series to the armature winding. A voltage control means for controlling the voltage is provided, and the voltage applied to the armature winding is controlled by the voltage control means, so that the power factor of the motor viewed from the AC power supply side can be adjusted. The power factor can be adjusted by the capacity voltage control means, and high-efficiency operation can be realized economically.
[0029]
The permanent magnet synchronous motor control device according to the present invention further includes power factor detection means on the AC power supply side, and is applied to the armature winding by the voltage control means so that the power factor detection value becomes a predetermined set value. Since the voltage to be controlled is controlled, a highly efficient driving operation is always achieved by so-called feedback control.
[0030]
Further, the permanent magnet synchronous motor control device according to the present invention inserts the AC output terminal of the three-phase inverter at the neutral point side of the armature winding of the three-phase Y connection, and supplies the AC output voltage of the three-phase inverter. Since the voltage applied to the armature winding is controlled by the control, the voltage control for adjusting the power factor is smoothly performed.
[0031]
The permanent magnet synchronous motor control device according to the present invention includes a first opening / closing means inserted between the AC power source and the armature winding, a load side terminal of the first opening / closing means, and the armature. A second opening / closing means for short-circuiting the three phases with the winding;
When the first opening / closing means is open and the second opening / closing means is closed, the motor is started by controlling the frequency and voltage of the AC output of the three-phase inverter. The voltage applied to the armature winding is controlled by closing the open / close means and opening the second open / close means and controlling the voltage of the AC output of the three-phase inverter at the frequency of the AC power supply. As a result, the same three-phase inverter can be used both when starting the motor and during operation where voltage control for power factor adjustment is performed, thus enabling high-efficiency operation at low cost without requiring a start winding. .
[0032]
Further, the permanent magnet synchronous motor control device according to the present invention comprises switching means for configuring each phase AC output side of the three-phase inverter with a plurality of units and switching connection of these units in series or in parallel.
When starting the motor by controlling the frequency and voltage, connect the units in series.When adjusting the power factor of the motor by controlling the voltage with the frequency of the AC power supply, connect the units in parallel. As a result, the substantial capacity of the three-phase inverter can be reduced to further increase the economy.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram showing a permanent magnet synchronous motor and a control device thereof according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing a detailed configuration centering on an inverter 4 of FIG. 1;
FIG. 3 is a diagram showing an internal configuration of the inverter unit 40 and the like of FIG.
FIG. 4 is a diagram for explaining the operating principle of the present invention.
5 is a timing chart for explaining the operation of the permanent magnet synchronous motor control device of FIG. 1; FIG.
[Explanation of symbols]
1 commercial power source, 2 armature winding, 3, 5 switch, 4 inverter,
6, 7 Voltage detector, 8 Current detector, 9 Operation mode switch,
10 power factor commander, 11 power factor detector, 12 subtractor, 13 controller,
40, 50, 60 Inverter unit, 41-64 selector switch.

Claims (5)

In a control device for a permanent magnet synchronous motor provided with a stator having an armature winding and a rotor having a permanent magnet and driven by an AC power supply,
Voltage control means is provided for controlling the voltage applied to the armature winding by applying in series to the armature winding a voltage that is adjusted with a fluctuation range smaller than the voltage of the AC power supply , and this voltage control means By controlling the voltage applied to the armature winding by means of the above, it is possible to adjust the power factor of the motor as viewed from the AC power supply side. The power factor detection means is provided on the AC power supply side, and the voltage applied to the armature winding is controlled by the voltage control means so that the power factor detection value becomes a predetermined set value. The permanent magnet synchronous motor control device according to 1. By inserting the AC output terminal of the three-phase inverter to the neutral point side of the armature winding of the three-phase Y connection, and controlling the AC output voltage of the three-phase inverter, the voltage applied to the armature winding The permanent magnet synchronous motor control device according to claim 1, wherein the permanent magnet synchronous motor control device is controlled. A first opening / closing means inserted between the AC power source and the armature winding, and a second opening / closing means for short-circuiting the three phases between the load side terminal of the first opening / closing means and the armature winding With means,
When the first opening / closing means is open and the second opening / closing means is closed, the motor is started by controlling the frequency and voltage of the AC output of the three-phase inverter. The voltage applied to the armature winding is controlled by closing the open / close means and opening the second open / close means and controlling the voltage of the AC output of the three-phase inverter at the frequency of the AC power supply. 4. The permanent magnet synchronous motor control device according to claim 3, wherein Each phase AC output side of the three-phase inverter is composed of a plurality of units and includes switching means for switching the units connected in series or in parallel.
When starting the motor by controlling the frequency and voltage, connect the units in series.When adjusting the power factor of the motor by controlling the voltage with the frequency of the AC power supply, connect the units in parallel. The permanent magnet synchronous motor control device according to claim 4, wherein the permanent magnet synchronous motor control device is provided.

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