JPS5931317B2 - AC non-commutator motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to provide an AC non-commutator motor with measures against power outages, so that when a power outage occurs during drive or regenerative operation, the motor is stopped without passing an overcurrent, It is also designed to be able to restart automatically when power is restored.

Generally speaking, a power outage includes a complete loss of power or a voltage drop to almost zero volts, such as a 95% power outage.
There are two types of power outage: a complete power outage, such as "0.5 sec", and a power drop, called a 50% instantaneous power outage, in which the power drops beyond a specified value, for example, "50% 1.0 sec".

The present invention detects a power outage by dividing it into two parts: a complete power outage and a power drop, and in the event of a complete power outage, the α phase of the thyristor is fixed at a constant value, and the main circuit current is determined based on the circuit conditions such as the DC reactor and the motor voltage. It is attenuated by the phase relationship, and when the power supply drops, the set control advance angle γ0 is set to a certain value within the range of 00 to 900, and the control delay angle α is set at each kick pulse position with the phaser input set to zero. During driving, the voltage on the power supply side is reversed from a positive value to a negative value, and during regeneration, the back electromotive force on the motor side is reversed from a negative value to a positive value, rapidly attenuating the main circuit current and causing an overcurrent. This was done to prevent this from happening.

The present invention will be specifically explained below based on the drawings.

In the drawings, Fig. 1 is a typical block diagram of an AC non-commutator motor, Fig. 2 is a control circuit diagram of the AC non-commutator motor according to an embodiment of the present invention, and Figs. 3 and 4 show its operation. FIG. 2 is a diagram showing waveform diagrams of a motor voltage and a main circuit current, and a conduction relationship of a thyristor at that time, for explaining. The AC non-commutator motor shown in Figure 1 is connected to a transformer Tr from a three-phase ΛC power supply.
l Through the DC reactor L, each set connects each phase of the power supply R, S,
This is the most common configuration in which power is supplied to the motor SM through six thyristor groups U, V, . . . Z, each consisting of three thyristors corresponding to T, corresponding to each phase of the motor. Detailed explanation will be omitted.

In addition, the control circuit shown in the second diagram has an a control function that controls the motor voltage and speed, and selectively conducts the thyristor depending on the position of the field pole to flow current to a predetermined armature winding to generate torque and rotate. Consists of γ control function. That is, the α control is a speed control mechanism that controls the phase delay angle α according to the difference between the set command value set by the speed command device 1 and the speed feedback signal, and in the illustrated example, it has a current minor loop,
Speed regulator PIN2, current regulator PII3, phase shifter TD
4 is the main component, and the other is the starting relay It consists of switch elements F6a, R7a, an inverter 8, normally closed switch elements F6b, R7bl, etc. provided between the input and output of the current regulator 3 in order to smoothly switch between drive and regeneration and minimize wasted time. In addition, the γ control distributes gate signals to the corresponding thyristors based on the position signal from the position detector, and the control advance angle γ is set depending on the driving mode. In order to determine the positive or negative current command, a torque direction discriminator 9 and a γ logic circuit 10 are used to determine whether the current command is positive or negative and issue a positive torque or reverse torque command. It is composed of an A and γ synthesis logic circuit 11 which combines the α signals of the phase shifter TD4 and calculates a logic output for a thyristor gate signal. The present invention provides a control circuit for an AC non-commutator motor having the above D, γ control function, in which when the synchronous power supply of the phase shifter TD4 disappears due to a power outage or decreases to a specified value or more, the power is reduced by the first comparator 20. The second comparator 21 detects a complete power outage, and in the case of a complete power outage, a power outage command is given to the phase shifter TD4, and TD4
At the same time, a d signal (constant DC signal) is separately input to the α, γ synthesis logic circuit 11,
In combination with the γ signal, a gate signal is given to a specific thyristor group so that the thyristors that were conducting immediately before the power outage are made to continue conducting, and the thyristors of the same phase in other loops are made to be conducting in response to the switching of the position signal, and When the power supply drops, the setting control advance angle γ.

While fixing it to a constant of 00 to 90 dens, for example 60,
By activating relay X22, the input and output of both speed and power regulators 2 and 3 are shorted, the input of phase shifter TD4 is zero, and the α signal is set to the hard pulse position, which prevents excessive main circuit power during a power outage. It is characterized by preventing damage to the thyristor. The operation will be explained below using waveform diagrams.

Initially, γo=60 is already being driven and γ. The operation when a complete power outage occurs during regenerative operation at -120 will be explained.
γ in Figure 3. The motor back electromotive voltage (a) seen from the power supply side of =600 through the thyristor, the waveform diagram of the motor current inlet that has been rectified into a DC model, the thyristor group to which the gate signal is input at that time, and the conduction thyristor (c) are shown, respectively. That is, γo
Since the motor is operating at 60 s, the motor back electromotive force seen through the conduction thyristor has a waveform as shown in the figure.If a power outage occurs at the time of TO, the comparator 21 mentioned earlier will be activated and the When the d signal cutoff command is input to the phase shifter TD4, the α, γ synthesis logic circuit 11 performs α, γ synthesis.
An all-d constant signal is applied to make the d-phase of all thyristors constant, and a firing signal is applied to all thyristors of the group determined by the γ control system. In the case shown in the figure, these groups are U and Z, and the ignition phases seen from the AC power supply side immediately before a power outage are the R and S phases.From these relationships, the conductive thyristors at the time of a power outage are UR and ZS, which means that the position signal is The switching continues until time T2, when intergroup commutation takes place. When the position signal, that is, the γ signal, changes at time T2, the ignition signal is transferred from the thyristors in the U group to the VR, S, and VT thyristors in the V group, but the thyristors that actually conduct conduct because the AC power supply has disappeared. Therefore, only the load commutation is performed, and only the thyristors and VR of the same phase as seen from the power supply side are connected, and the Z group remains as it is, and the thyristors of VR and ZS become conductive.
Similarly, at time T2, a commutation takes place from Z to X group, ie from ZS to XS thyristor. Of course, the motor back electromotive voltages UW, VW, and VU during this time tend to decrease the motor current, and the motor current is attenuated depending on the motor back electromotive voltage and main circuit conditions such as the DC reactor, and eventually becomes zero. In this way, the present invention reduces the motor current by sequentially commutating the load to the same phase as seen from the power supply, and in combination with the main circuit conditions, the motor current can be reduced regardless of the size of the DC reactor. It is impossible for the back electromotive voltage to act harmonically with the motor current, and the current always attenuates and becomes zero (at time t'o). γ in Figure 4. =120
When a complete power outage occurs during regenerative operation at 0, as in Figure 3, the motor back electromotive force A seen from the power supply side through the thyristor and the waveform diagram of the motor current port (shown as a DC model) at that time. The thyristor and conductive thyristor into which the gate signal is applied at that time are shown, respectively. In the case of regenerative operation at normal speed where γo is 120mm, the control delay angle α is 90mm
It is set to a value that provides the optimum power supply voltage that corresponds to the motor back electromotive voltage of 800 and that operates the braking torque most efficiently, as shown in the figure. If a power outage occurs at this point, the power supply voltage becomes zero V, and therefore the motor current increases rapidly. That is, when a power outage occurs, the power supply voltage disappears and the motor back electromotive voltage is short-circuited at the power supply via the DC reactor, resulting in T shown in the figure. In the case of a power outage at that point, the motor current continues to increase until T2 when the polarity of the back electromotive force is reversed, and then the polarity is reversed, so it decreases every time the position signal changes due to the motor voltage waveform. Although there is a slight delay in the decrease, it eventually reaches zero. That is, when regenerative operation is in progress, a storage command is sent to the a memory circuit 12 at the same time as a complete power outage to store the conduction thyristor immediately before the power outage, and output a constant α phase signal to give a gate signal only to this phase. During this time, in order to make the operation more reliable, a d signal stop command is input to the phase shifter 4 as in the case of driving, and the function of the phase shifter 4 is stopped. This means that from TO at the time of a power outage to time T2 when the polarity of the back electromotive force is reversed, no gate signal is given to the other thyristors US, UT, ZR, and ZT in the same group due to the action of the memory circuit 12. UR. The state in which only the thyristor of l5ZS is made conductive and the motor back electromotive voltage between TO and T2 is short-circuited by the transformer Trl and the DC reactor L is as follows.
This is intended to prevent the motor current from increasing by limiting it to only one phase of the DC reactor L. The steady-state effective value of this current is determined by dividing the motor back electromotive voltage by the motor winding impedance, DC reactor, and power supply impedance. The memory circuit 12 is not necessarily required. That is, as in the case of driving, a d signal is given to all thyristors at a constant rate, and U,
It is also possible to fire all the thyristors in the Z group, and in this case, the motor current will be lower than when the power supply impedance of each phase of the three-phase AC and the DC reactor are connected as loads, and the d memory circuit 12 is operated. Approximately 3 times as much. In this way, the regenerative power reaches its maximum at time T2 when the polarity of the motor back electromotive force is reversed, and then decreases. However, this maximum current is determined by the main circuit conditions, and if necessary, it can be triggered to stop the operation of the overcurrent protection device. It is sufficient to issue a disconnection command from the comparator 21, which is necessary when restarting upon power restoration. On the other hand, the γ control system controls γ by the operation of the comparator 20. A fixed command is issued and γ. The γo signal of the logic circuit 10 is switched from 120 during regeneration to a constant value of 900, for example 600, and the same thyristors UR and ZS continue to be conductive even after reaching time T2 during commutation.
It does not change until time T3, which is 600 phases later, and during this period, the motor back electromotive force is in the opposite phase to the regenerative current and tends to suppress the current. At time T3, the position signal switches and commutation occurs from the U group to the V group, that is, from the UR thyristor to the same phase thyristor VR seen from the AC power supply, R and ZS become conductive.
The regenerative current is reduced by the back electromotive voltage VW, and at the time T4, the position signal is similarly switched, the thyristor XS is fired, and the back electromotive voltage VU works to suppress the current, and finally becomes zero (at the time t'o). In this way, in order to prevent excessive current from flowing during a power outage during regenerative operation, the conduction thyristor immediately before the power outage is memorized and a gate signal is given only to that phase, and after the motor back electromotive voltage is reversed, the position signal is sent in the same way as when driving. Commutation is performed based on the load commutation at each switching, and the motor current is sequentially reduced by the back electromotive voltage. Incidentally, one of the simplest types of d memory circuit 12 is a flip-flop. Note that this d memory circuit 12 is stored at the time of the first position signal switching after a complete power outage (T
2), and at this point all thyristors are uniformly d
It is obvious that if a signal is given, it becomes unnecessary.

That is, the motor back electromotive voltage after time T2 is reversed and the circuit conditions are the same as during driving. The operation at the time of a complete power outage has been explained above, and next, the operation at the time of a power drop will be explained.

In the case of drive operation, if the speed is normal, the set control advance angle γ.

is set at 60 when γ is large or low, but when a momentary power outage occurs and the comparator 20 is activated, the above γ. is reset to a predetermined value between 00 and 900, and relay Xl22 is activated, and current regulator PII3,
Short-circuit each input and output of the speed regulator PIN2, and connect the phase shifter TD4.
With the input at zero and the d phase at the kick pulse position, the power supply voltage Vs
(the voltage applied to the motor via the thyristor) is controlled to the negative maximum value, and the relationship between the power supply voltage Vs and the motor back electromotive voltage VM is selected so that Vs<VM, and the motor current is rapidly attenuated to zero. do. Further, during regenerative operation, α is set to an appropriate value of 90 to 1800, which corresponds to the motor voltage and applies an appropriate braking torque, while γ.

corresponds to the motor speed, i.e. 12 at normal speed.
At 0 speed and low speed, 180 glyphs are determined, and regeneration is performed under the condition that IVsI<IVMI, where both the power supply voltage and the motor back electromotive force VM are negative, and VM is greater than Vs.
In this state, if a power outage occurs and the AC power supply voltage drops,
The comparator 20 is activated, a γo fixing command is issued, and the setting control advance angle γ is set. is switched to an appropriate value from 00 to 900 as in the case of driving operation, and the motor back electromotive voltage VM
is converted from a negative value to a positive value, and the braking current based on the voltage VM is rapidly attenuated to zero. Of course γ. Simultaneously with the switching, the relay Xl22 operates to convert the input of the phase shifter TD4 to zero and the α phase to the negative maximum value (kick pulse position), contributing to the attenuation of the current, as in the case of driving. In addition, if you want to restore the power in a short time and continue the operation as before the power outage without stopping the motor, you can keep the starting relay XS5 in the closed state and the comparators 20 and 21
operation is stopped, the output short-circuit switch 22b of the speed regulator PT82 is opened, and the output of the speed regulator PIN2 returns to the value corresponding to the difference between the set command value and the speed feedback amount at the time of power restoration.
The operation will be restarted based on the command from the speed command device 1. As described above, the present invention enables the motor to be stopped during a power outage such as a momentary power outage during either drive or regeneration operation without causing abnormal current to flow, and when it is desired to continue operation when power is restored. Generally speaking, when the synchronous power supply drops significantly (for example, 4001 or less), the phase shifter of the d control system is designed to continue as it is.
, malfunctions often occur, and if there is no conventional protection against instantaneous power outages, malfunctions of the α signal, especially during regenerative operation, may occur due to the power supply voltage harmonically adding to the motor back electromotive force depending on the timing. It is conceivable that a large current will flow through the main circuit, causing a quick fuse to blow, a protective device to activate, and even damage to the thyristor, but these concerns can be completely eliminated.
In addition, a particular feature of the present invention is that even in the event of a complete power outage in which the power supply voltage disappears, a constant d signal is applied to a specific phase or all phases as seen from the power supply side, and the thyristors are sequentially turned on by load commutation. This has the excellent advantage that the value of the DC reactor in the main circuit is not subject to any substantial restrictions.

[Brief explanation of the drawing]

In the drawings, Fig. 1 is a basic block diagram of an AC non-commutator motor, Fig. 2 is a circuit diagram of an embodiment, and Figs. 3 and 4 show back electromotive force and motor current during power outage during drive and regenerative operation, respectively. FIG. 12...α memory circuit, 20, 21...
Comparator, 22... Relay Xl. 22a・
...Relay X1 normally open contact, 22b...
Normally closed contact of relay X1.

Claims (1)

[Claims] 1. The control delay angle α is adjusted according to the difference between the speed command value and the speed feedback amount.
In an AC non-commutated motor that has an α control function that controls A power outage is detected separately into two types: a power drop and a complete power outage, and in the case of a power drop, the control delay angle α is
to the kick pulse position, set the control lead angle γ_0 in the range of 0° to 90°, and in the case of a complete power outage, give an α signal cut-off command to the α control system phase shifter to control the phase shifter function. During regenerative operation, the phase of the conducting thyristor seen from the AC power supply side immediately before the power failure is memorized and a signal is given to this specific phase, and during drive operation, a signal is given to all phases at the same time to identify the α phase. , and a set control advance angle γ_0 is set in the range of 0° to 90°, α and γ are combined, and a gate signal of a thyristor is supplied. 2. An AC non-commutator motor having the configuration according to claim 1, characterized in that the operation of the overcurrent protection device is stopped in the event of a complete power outage during regenerative operation.