KR20080041547A - A control method for sensorless permanent magnet synchronous motor - Google Patents

Abstract

A method for controlling a sensorless PMSM(Permanent Magnet Synchronous Motor) is provided to prevent vibration from being generated when the sensorless PMSM rotates at a speed lower than a rated rotation speed. A method for controlling a sensorless PMSM(M) includes the steps of: synchronously starting two or more sensorless permanent magnet synchronous motors at a low rotation speed by applying a very low-frequency three-phase alternating current to the two or more sensorless permanent magnet synchronous motors from a single inverter for a predetermined time; and allowing the two or more sensorless permanent magnet synchronous motors to reach at rated rotation speed through by gradually increasing a frequency of power(G) to increase a rotation speed of the two or more sensorless PMSMs.

Description

CONTROL METHOD FOR SENSORLESS PERMANENT MAGNET SYNCHRONOUS MOTOR

The present invention relates to a control method of a sensorless permanent magnet synchronous motor (hereinafter referred to as PSM), specifically, to a synchronous start of two or more sensorless PMSs by a single inverter device, Continuous operation at the rated speed enables starting from the reverse rotation state, and prevents the occurrence of vibration, etc. during the rotation operation at a lower speed than the rated value, and safely stops in case of failure It relates to a control method of a sensorless PMS.

Conventionally, PSM which uses three-phase alternating current as a power source is equipped with a sensor (position detection device) for detecting the magnetic pole position of the rotor, and the magnetic pole position of the rotor is detected and detected by this sensor. According to the magnetic pole position of the rotor, current flows in each phase of the stator coil to generate a rotor magnetic field, and torque (by the interaction with the magnetic field generated from the magnetic pole) A starting method that generates torque and transmits power to the load is adopted.

The total cost of the PSM with the sensor, the control circuit, and the inverter device is considerably higher than the total cost of the induction motor and the inverter device, which are representative examples of AC motors, and there is a problem that a failure occurs in the sensor. For this reason, for example, in a PSM used in a condition of a constant rotation speed or higher, such as a blower fan, a sensorless PSM which eliminates a sensor and reduces cost is adopted. In this sensorless PMS, in order to maintain the control during continuous operation at the same level as that with the sensor, the respective data appearing in the stator coil terminals are detected, the characteristics thereof are calculated and complicatedly controlled. (See, for example, Japanese Patent Laid-Open Nos. 2001-268974 and 2002-272195).

Patent Document 1 JP 2001-268974 A

Patent Document 2 : Japanese Patent Application Laid-Open No. 2002-272195

However, when starting the sensorless PSM according to the conventional method, a separate special control device for starting is required, or it is necessary to control from the start by further complicating the control method. There was a problem that there might be a failure. In addition, there is a problem that an inverter device for supplying a power source requires one for each PMS and thus hinders cost reduction.

The present invention is a synchronous start method of two or more sensorless PMSs powered by a three-phase AC power source, and a low-speed operation is performed by applying a very low frequency three-phase AC current to the two or more PMSs from a single inverter device for a predetermined time. I) After synchronous start, the frequency of the power is gradually increased to increase the rotational speed to reach the rated rotation, and a single inverter device is used to reliably start two or more PMSs to solve the related problems. .

The present invention is a synchronous start method of two or more sensorless PMSs powered by a three-phase AC power source, and a low-speed operation is performed by applying a very low frequency three-phase AC current to the two or more PMSs from a single inverter device for a predetermined time. After starting synchronously with i), the frequency of the power supply is gradually raised to increase the rotational speed to reach the rated rotation, so that two or more PSMs can be reliably started by a single inverter device.

Alternatively, any one of two or more three-phase three-phase coils of PSMs may be applied with a direct current from a inverter device to a two-phase coil to generate a stator magnetic shaft, thereby forming a rotor stator ( V is sucked and two or more PSMs are synchronized at the same time, and then the frequency of the three-phase AC voltage is gradually increased to reach the rated rotation, so that the synchronous start is performed.

When PSM is rotating in reverse due to external factors, two or more PSMS three-phase coils are connected to each phase to generate electric braking currents between the PMSs. All the PSMs are synchronized at the same rotational speed in the reverse rotation state, the generated voltage and frequency of the PSMs at the synchronized rotational speed are detected, and the angular velocity ± the allowable angular velocity. After the synchronization with the power supply by applying the voltage and current at the frequency of the inverter to the rotating magnetic field in the forward rotation direction to reach the rated rotation with the stop state It is to be synchronized to start.

Insulated Gate Bipolar (Insulated Gate Bipolar) of the inverter device when operating in a state in which the rotation speed of two or more PMSs during synchronous operation is reduced and the load torque is reduced. Internal phase difference angle δ, detected at the output side of the transistor circuit and the phase of the current supplied from the inverter device is 15 ° or more ahead of the generated voltage of PSM. By increasing the size, two or more PMSs are operated without generating vibration, hunting, and degassing.

The I / T circuit detects the frequency, voltage, and current generated in response to the rotational speed of the PMS in the inverter circuit of the inverter device, and detects the voltage and current of another frequency generated from the PMS, which has generated an abnormality, in the IFT circuit. The IFT circuit detects an abnormal frequency current generated when one of two or more PSMs during operation is out of sync due to a failure, and the rotation speed decreases. The output was shut off and the rotation of the healthy PMS was safely stopped.

Example 1

The synchronous start method is one of the methods of starting a synchronous motor powered by a three-phase AC power source. As shown in FIG. 6, the synchronous generator and the driven side of the drive side ( Using both synchronous motors M of a synchronous motor as a synchronous machine, the three-phase terminals of the two motors are connected to each other in a stationary state, and excitation currents are also respectively obtained. If it is left to flow and the drive D directly connected to the synchronous generator is slowly rotated on starting, the synchronous generator rotates to supply an ultra low frequency current to the synchronous motor M. The synchronous motor M is synchronized with the synchronous generator by the action of the rotating magnetic field generated on the synchronous motor M side and the magnetic field generated by the excitation current, and then on the synchronous generator side. Ascending Rotation as Synchronized by Raising Rotation Is continued to increase to a high rated speed.

Such a synchronous start method is for starting a large capacity synchronous motor (motor), for example, a power generator motor directly connected to a pump aberration of a pumping power plant, or for starting a large capacity turbine generator. This system is commercially available as a method for smoothly starting the system without putting a large load on startup to the connected system. Detailed analysis is performed in various practical examples, and synchronization can be started by various parameters. The range is confirmed.

When the synchronous start method is to be applied to the PSM, first, the output of the PSM is 100 W to a few kW, which is very small compared to the general motor, and the resistance value R of the armature coil is a unit method. Extremely large at 0.04 to 0.2 pu (4 to 20%), and because excitation is a permanent magnet, excitation E2 of PSM is a fixed fixed value, and the supply of power is replaced by a synchronous generator. There are different points, such as becoming an inverter power source using an insulated gate bipolar transistor (IBT) circuit. Since these detailed calculations are very complicated, the rotational speed N ₁ (or the angular velocity ω ₁ ), which is a possible range of the synchronous start, was obtained by a simple calculation in which parameters with less influence were omitted from the known parameters. In addition, it is assumed that the inverter device applies the power of ω _{1 to} the PMS for a predetermined time.

1) 1C1M (starting one PSM with one inverter)

(a) circuit and current

Fig. 1 shows a state in which a voltage of an angular velocity omega ₁ (0.01 order in units of units) corresponding to a very low frequency f ₁ is supplied to the PMS in a power supply (inverter).

If Ｖ ₀ is the phase voltage at rated voltage and the current at rated is I ₀ (A) and f ₀ is the rated frequency, the voltage 때 when turning to N1min ^-1 at very low speed is

Where Lm is an inductance corresponding to the reactance of the motor.

The impedance impedance of the circuit is very small compared to RM of ω ₁ LM,

The current I ₁ (A) flowing in the circuit of FIG. 1 is

In addition, when ignoring the resistance of the power supply, RM becomes a resistance of PMS.

(b) Calculation of torque

F0 generated at the rating of the synchronizer is expressed by the following equation.

Mm ₁ ; Wave height value of fundamental magnetic flux density in the magnetic flux generated by the permanent magnet

A ₁ ; The electric load by the armature coil is expressed by A ₁ = (I ₀ · ΣＺ) / (πD) (A / m). (ΣＺ is the total number of series conductors of the three-phase coil, D is the inner diameter of the stator (m))

Ｋｗ; Coil coefficient, δ; Let cosδ co1 be the internal phase difference angle (差 角).

Substituting the numerical value applied in the case of PMS of several hundred W class into Equation (4) above, the approximate value of F ₀ can be obtained.

While for I ₁ it is calculated with respect to two kinds of specific PMSM (output of 200W and 150W).

200 W; Resistance value of 1 phase Rm = 7Ω

150 W; Resistance value of 1 phase Rm = 20Ω

The phase voltage of the above formula (3) has a terminal voltage of 200 kV,

_{ω 1 / ω 0 = 0.005,} 0.01, 0.02, 0.03, is obtained for I ₁ for each 0.06 (pu).

발생 Generated torque of 200 W machine

Since the rated current I ₀ = 1.0 (A) of the 200W machine, the surface area S = 0.01 (m2) of the rotor, the rated rotational speed N ₀ = 1300min ^-1 , and the rotor radius r = 0.033m, use equation (5) above. To calculate the force F ₁ and the generated torque T of the entire PMS.

발생 150W generator torque

Current rating of 150W group I ₁ = 0.7 (A), specific surface area S = 0.008 (㎡), the rated rotational speed of the rotor N 0 ₌ 1300min ^-1, once Using electron radius r = 0.0285m, similarly F ₁ and T Can be estimated.

3) DVD ² Energy and torque required

The rotating body has a flywheel effect of GD ² (㎏㎡), the energy E ₀ when the holding and rotating at a rotational speed of N 0 _(min ^-1) is,

GD ² it is assumed that use of the load of the fan (fan) of PMSM GD ² is very large, and the same group than 150W 200W group PMSM.

WD ² = 0.124 [kg㎡]

therefore,

The energy E retained at the rotational speed of ω ₁ / ω ₀ is

On the other hand, when a three-phase current flows through the stator coil (low frequency of ω ₁ / ω ₀ ) and a slow rotating magnetic field is generated, the magnetic field is separated from the N and S magnetic fields magnetized on the surface of the rotor. If a force is generated between them and the first N and S poles are not synchronized, synchronization is impossible.

When the rotor magnetic pole is configured as an 8-pole configuration, the mechanical angle θ ₁ per pole is

If the torque required to move the rotor θ ₁ that Tm, the energy W required there is,

If said (10) = (12),

therefore,

Compare the required torque T found in Tm and 필요한 for a 200W machine.

From this calculation result, it is found that if the value of (ω ₁ / ω ₀ ) is a speed of about 0.03 pu or less (that is, 3%) or less, synchronization is difficult.

Similarly, the 150 W machine is also calculated.

From this calculation result, it turns out that synchronization is difficult even when the value of ω ₁ / ω ₀ is about 0.01 pu (that is, 1%).

4) Conditions for Synchronous Start

According to the above calculation results, as a condition that can be synchronized, a certain low frequency voltage (corresponding to ω ₁ ) is applied to the PMS from the power supply, and the torque and energy supplied to the PSM by the current flowing out within a certain period of time. It is found that the rotor energy required to reach ω ₁ by including the WD ² can be exceeded and supplied with a margin.

In the group 200W, Keeping ω ₁ to ω ₁ is fixed within 0.03pu (i.e., 3%), it can be synchronized.

On the other hand, ω ₁ of the 150 W machine is 0.01 pu (that is, 1%) or less, and since the synchronization range is narrow and stable synchronization is difficult, in this case, stable starting is possible by increasing the power supply voltage k.

Therefore, in order to achieve stable synchronization, methods such as reducing the resistance value of the PSM or increasing the power supply voltage within an allowable range are considered, but these must be viewed as [motor price + inverter price] = total cost. It is important to decide whether to increase the size of the PSM and lower the resistance value or to provide a margin in the inverter device.

The above example is the case of 1C1M (starting one PMS with one inverter device), and in case of 1CM (starting two or more PMSs with one inverter device), there is a need for more margin because the synchronization problem between the two cars is added. Done.

According to the start-up method shown in the above 1) to 4), the sensor is not required for the PSM (sensorless), and the voltage and current at the output frequency of the three-phase inverter device are kept at low frequency (several% or less). 3% or less) is applied to the PSM for a predetermined time for several seconds, and as shown in FIG. 2, two or more PSMs can be synchronized to a power source. It can be raised as it is synchronized up to the rated rotational speed of.

Example 2

Next, a second embodiment of the synchronous start method will be described. As shown in Fig. 3, a DC current is first flowed into a two-phase coil (between ＵＶ in the drawing) of the three-phase coil, and the stator magnetic axis (not rotating) generated thereby causes the current to flow. The magnetic poles are sucked by the rotor and synchronized with each other, and then the phase is shifted between the pulses and the pulses as in a normal inverter device to raise the frequency.

Also in this case, in order to fit the first magnetic pole to the magnetic axis, a certain time Δt (until the rotor vibrates and synchronizes with natural vibration and stabilizes) is required for several seconds.

Will Figure 3 is about one PMSM, by this method, if applied to the two or more X units PMSM startup, the synchronization condition, but it is somewhat rigid, review the resistance of the PMSM · GD ² · applied voltage, etc. Clear synchronization can be achieved. Which of the first and second embodiments should be determined by examining the overall balance including the control method and the number of units.

When starting the PMSM at 1CXM (X vs. from the same drive device), simultaneously (同時) first element of which determines the right or wrong of the boot is an armature resistance of the PMSM, and then the GD ^2, the power source voltage as described above, This affects That is, when two or more PSMs are simultaneously started, the starting currents (synchronizing currents) are maintained by slowly maintaining the resistance and the voltages and frequencies (low voltages and low frequencies) supplied by the inverter device and their holding periods. Flows into the PCM, and in the case of two units, it is important to start the two units simultaneously and completely synchronize them. When this synchronization is completely performed, in the process of increasing the power supply frequency to increase the rotational speed of the PSM, the synchronizing force acts on each other, which stabilizes and rises. The operation control after this ascending process and reaching the rated rotational speed can be performed stably by switching to the closed loop control by detecting the voltage and frequency of the PMS. Further, since two or more PSMs can be reliably started by a single inverter device, the total price can be greatly reduced by including the price of the sensorless PMSs.

Example 3

In the case where the sensorless PMS is used, for example, a large air conditioner or the like, the load directly connected to the PMS is a blower fan, and a power supply for stopping a set of some PMS (two or more PMs operated by a single inverter device) is stopped. When it is turned off, the pressure is applied to the stopped blower fan under the influence of the positive pressure environment produced by the other blower fan in operation, thereby turning to reverse rotation as opposed to normal. The rotation speed may reach 40% of the rated rotation speed.

The present invention proposes a method for reliably starting up in synchronization with a single inverter power supply reliably even in the case of two or more sensorless PSMs in such a reverse rotation situation.

Where two blowing fans are from separate power supplies (each inverter device), rotate at different rotation speeds (eg, -N ₃ min ^{-1 on} one side, -N ₄ min ^{-1 on the other} ), and 1C1M Is connected between the coils of each phase of both PSMs. Power generation braking is generated by a current flowing between both PSMs generated by reverse rotation, and two PMSs generate two PSMs, respectively. to the same rotary speed as the substantially intermediate -N ₅ min ^-1 in synchronization with the rotation (同期) state, that is, can be set to a state where it can see the two PMSM with a single PMSM.

In this state, the voltage and frequency generated from the PMS are detected and the two PMSs are synchronized at the same time by applying a corresponding voltage from the IFT circuit, thereby rotating the rotation from -N ₅ min ^-1 (reverse rotation) to Omin ^-1 (stop). ) To N ₀ min ^-1 (rated speed).

More specifically, in the case of two PMSs (a) and (b) (1C1M), the three-phase terminals of both PSMs are connected to the output terminals from the IFT circuit, respectively. Therefore, if the output of the IFT circuit is cut off to stop this set for some reason, the PMS (a) (b) will be N ₀ min ^-1 (rated speed)-Omin ^-1 (stop)-reverse rotation, but positive Since the mechanism is electrically connected, the synchronous state is maintained even in the case of reverse rotation, and the gear is turned at the same rotational speed of -N ₅ min ^-1 . If there is no positive connection between the case of the PMSM drive alone (單獨), PMSM (a) (b) are each (各) respectively by the difference in characteristics such as fan ^{_{-N 3 min -1, -N 4 min}} - ^{In the} case of electrical connection, the braking current flows, so the electric braking torque is applied, and -N _{5 which} is halfway between -N ₃ min ^-1 and -N ₄ min ^-1 . It rotates in synchronization with the rotation speed of min <^-1> .

Therefore, the generated voltage and frequency (PMS M acting as a generator) at that time are detected from the power supply base, and the inverter device has three phases of the reverse rotating magnetic field corresponding to the voltage V ₅ . By applying a voltage and a frequency, a predetermined current flows to synchronize with the power supply, and after that, the two phases of the power supply can be switched to form a positive rotational magnetic field, thereby shifting to the state of Omin ^-1 .

In the above process, the sensorless PMS can be started up from the state of reverse rotation. This is a major feature of enabling not only one PMS but also a large number of PMSs.

The synchronization phenomenon at the time of reverse rotation is almost similar to the synchronization phenomenon at start-up from Omin- ¹ . As shown in Fig. 4, when the forward rotation direction is set clockwise, the reverse rotation direction becomes counterclockwise, and in the case of two PMSs, as described above, a reverse rotation magnetic field is formed in which -N ₅ min ^-1 is synchronized. The frequency f ₅ induced by the stator coil

_{f 5 = PN 5/120 (} ㎐) (P is the number of poles (極數))

Become,

ω ₅ = 2πf ₅

Therefore, for the angular velocity ω ₅ obtained from the frequency detected by the coil terminal, it is found that the power supply applied by the inverter device can be synchronized as long as the angular velocity ω ₅ ± (0 to ω ₁ ) is in the reverse rotation magnetic field. ω ₁ is the synchronization allowable angular velocity. In practice, it is important to apply an angular velocity of ω ₅ ± Δω ₁ (Δω ₁ <ω ₁ ) to make synchronization easier and more reliable. The applied voltage is, of course, a voltage capable of flowing the current required for synchronization described in 1) (see the vector in FIG. 5).

Fig. 4B shows the direction of the current which generates the reverse rotation magnetic field of the output of the inverter device during synchronization. Therefore, after synchronization is to return the rotational speed soon replaced by the V, W phase (相) as shown in (c) of Figure 4 to change to the forward rotating magnetic field ranging from -N ₅ min ^-1 Omin ^-1. Even in a large number of PMSs, the above process can be performed easily and reliably. Starting from Omin ^-1 applies the synchronous start method described in 1).

Example 4

In this embodiment, a control method as a stabilization countermeasure at a rotational speed of 70% or less of the rated rotational speed will be described.

When the rotational speed is lower than the rated rotational speed, particularly in the case of a load such as a blower fan, the load torque is reduced in proportion to the square of the rotational speed. Therefore, the current required by the PMS is also reduced in proportion to the torque. This means that the internal phase difference angle δ of the PSMs becomes small. When two or more PSMs are connected to one inverter power supply in the case of 1 CSM, the amount of each blower fan load is reduced with the current value greatly reduced. Vibration caused by the difference in the internal phase difference angle due to the difference in the characteristics of the phenomenon occurs, a phenomenon that can not operate stable. Therefore, the voltage, frequency, and current values of two or more PMSs in synchronous operation are detected on the output side of the inverter gate's ISL (Insulated Gate Bipolar Transistor) circuit, and the phase of the current supplied from the inverter device is 15 ° or more than the generated voltage of the PMS. The current is increased by increasing the internal phase difference angle δ in the preceding phase, so that two or more PSMs are operated without generating vibration, hunting, and outage. will be.

In general, in rated operation (rated rotation speed), in order to operate PMS most efficiently, linear current current ID = 0 control (control in which the phase of the motor generating voltage and current are in phase) is adopted. There is much to do. In this case, since the current becomes the minimum value, in the case of two or more parallel operations, as described above, when operating at a lower rotational speed, the possibility of vibration or hunting increases. In order to improve this, if the phase angle of the current is moved ahead of the generated voltage, the internal phase difference angle δ becomes δ + Δδ and the current value also increases, so that the amount produced by the difference in load characteristics The entry and exit of the active current of the PMS (two units) is reduced by an increase in the I ² R loss or the like, thereby suppressing vibration or hunting. The above-mentioned phase angle is 15 degrees or more, Preferably it is 20 degrees or more, and a stable suppression effect can be expected.

Example 5

In this embodiment, a method of safely stopping a PSM in case of a failure is described.

The I / T circuit of the inverter device detects the voltage and current of the frequency generated corresponding to the rotational speed of the PMSM, and one of the two or more PMSs in synchronous operation is out of synchronization due to a failure, etc. Current is detected at the IFT circuit to cut off the output of the inverter device. On the other hand, the rotation of the healthy PMS is safely stopped.

For example, during operation of two PMSs, if one of them escapes from the synchronous speed due to bearing damage or the like, and the rotation speed decreases toward the stop, the PSM is a voltage having a frequency corresponding to the rotation speed. And the current flows to the IWT circuit of the inverter device and the other one as a current of different frequency, so that this current is detected at the output side of the IWT circuit and the output of the inverter device can be stopped to safely stop the set. It becomes what there is. In addition, when one of the above-mentioned fault breakers completely stops at an early stage, a large current flows from the IFT circuit, so that it can be stopped by an Over Current Relay (OCR) circuit.

The control method of the present invention is highly reliable and easy to construct in an environment using two or more sensorless PMSs, and can be widely used with advantages of cost reduction.

According to the present invention, since a simple inverter method allows two or more sensorless PMSs to be controlled from synchronous start to continuous operation with a single inverter device, significant cost reduction can be achieved. It produces an effect.

It produces the effect that a sensorless PMS including two or more can be started from a reverse rotation state.

This prevents the occurrence of vibration and the like at the time of rotation lower than the rated rotation of the sensorless PMS, thereby producing the effect of achieving stable and quiet low speed operation.

This makes it possible to detect and control an abnormal (abnormal) state of rotation in the failure of the sensorless PMS and to perform a stop or the like in safety.

BRIEF DESCRIPTION OF THE DRAWINGS The example of the equivalent circuit at the time of starting in CI1M.

2 is a circuit example of 1 CMW.

Fig. 3 is a principle diagram of a synchronous start method of the second embodiment.

4 is a principle diagram of synchronization in reverse rotation.

5 is a vector diagram of a voltage applied in reverse rotation.

6 is a principle diagram of a synchronous start method.

Claims (5)

Synchronous start-up of two or more sensorless permanent magnet synchronous motors (PMSMs) powered by three-phase alternating current power sources. After applying a three-phase alternating current for a certain time and synchronizing at low rotation, the frequency of the power supply is gradually raised to increase the rotational speed so as to reach the rated rotation. Synchronous start-up method of sensorless permanent magnet electric motor using power. The method of claim 1, One of two or more three-phase each three-phase coils of PSMs sucks rotor magnetic poles by applying a direct current to the two-phase coil from the inverter device to create a stator magnetic shaft. And synchronizing two or more PMS at the same time and gradually increasing the frequency of the three-phase alternating voltage to reach the rated rotation. The three-phase coils of two or more PSMs are connected to each phase, and electric braking current is generated between the PSMs to synchronize all PSMs at the same rotational speed in the reverse rotation state, and the synchronization thereof is performed. After detecting the generated voltage and frequency of PMS at the rotational speed and synchronizing with the power supply by applying the voltage and current of the frequency of the angular speed ± the allowable angular speed from the inverter device, the rotating magnetic field in the positive rotation direction ( A method of synchronizing a sensorless permanent magnet synchronous motor from a reverse rotation in which the rated rotation is attained by switching to i) and stopping at a stop state. Insulated Gate Bipolar (Insulated Gate Bipolar) of the inverter device when operating in a state in which the rotation speed of two or more PMSs during synchronous operation is reduced and the load torque is reduced. The phase difference of the internal phase is detected at the output side of the transistor circuit and the phase of the current supplied from the inverter device is 15 ° or more ahead of the generated voltage of the PMS. A method of operating a sensorless permanent magnet synchronous motor in which two or more PMSs are operated without causing vibration, hunting, and out-gassing by increasing δ. The I / T circuit detects the frequency, voltage, and current generated in response to the rotational speed of the PMS in the inverter circuit of the inverter device, and detects the voltage and current of another frequency generated from the PMS, which has generated an abnormality, in the IFT circuit. The IFT circuit detects an abnormal frequency current generated when one of two or more PSMs during operation is out of sync due to a failure, and the rotation speed decreases. A method for stopping a sensorless permanent magnet synchronous motor that cuts off output and safely stops rotation of a healthy PMS.