JPH0126990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling the speed of an elevator motor by means of a thyristor.

In recent years, electric motors of elevators have been controlled by stationary Leonard devices composed of thyristors and the like. An example is shown in FIG.

FIG. 1 is a diagram showing the configuration of a conventional elevator speed control device using a non-circulating current type reversible static Leonard device. In the figure, 1 is a three-phase AC power supply that supplies three-phase AC voltages R, S, and T, 2A is a thyristor converter that supplies power during power running of the DC motor 3 in, for example, elevator ascending operation, and 2B is also an ascending operation. DC motor 3
A thyristor conversion device that sends regenerated power to the power source 1 during regenerative operation, 4 is a sheave of the hoist, 5 is a rope,
6 is the elevator car, 7 is the counterweight, 8
9 is a current regulator, 9 is a phase shifter, 10A is a switch that closes when control operation by the thyristor conversion device 2A is required, and 10B is a thyristor conversion device 2B.
10A and 10B are not both closed when a control operation is required. 11 is a speed regulator, and 12 is a flow divider. A gate pulse is applied to the thyristor conversion device 2A or 2B from the phase shifter 9 at a firing angle determined according to the output of the current regulator 8 via the switches 10A and 10B, respectively. A current corresponding to the given current command value is caused to flow through the DC motor 3. Further, the speed regulator 11 gives a current command to the current regulator 8 such that the speed of the DC motor 3 matches a speed command (not shown) given to the speed regulator 11. Furthermore, the performance of the control system is improved by current feedback from the shunt 12 and speed feedback from the DC motor 3 (not shown), and the speed control of the car 6 is performed with high precision.

By the way, in the above configuration, when the DC motor 3 shifts from powering operation to regenerative operation during elevator ascending operation, the current direction of the load is switched, so the thyristor conversion device changes to 2A according to the opening/closing operation of switches 10A and 10B. However, this switching must be performed when the load current of the DC motor 3 is zero. This means that when the load current is not zero and the components of the thyristor converter 2A are in a conductive state, when the thyristor converter 2B is fired, the two thyristor converters 2A, 2
This is because the power supply 1 is short-circuited through B and becomes inoperable.

Therefore, when the current command value becomes zero and the current feedback also becomes zero, the switch 10A is opened to cut off the gate pulse given to the thyristor conversion device 2A on the power running side, and then an appropriate amount of time has elapsed. After the thyristor converter 2A goes into the set-off state and the load current becomes zero, a gate pulse is applied to the regenerative side thyristor converter 2B via the switch 10B to operate it. If a gate pulse is applied with an abnormal phase at the start of operation of the converter 2B, an excessive rush current will flow. To prevent this phenomenon, conventionally, after opening the switch 10A to cut off the gate pulse and stopping the operation of the thyristor converter 2A on the power running side, the output of the current regulator 8, which is the phase shifter input signal, is set to the maximum level. The control delay angle is held at a value corresponding to the r limit, that is, the value at which the load current of the thyristor converter 2B is least likely to flow, and then the switch 10B is closed and the gate is applied to the regenerative side thyristor converter 2B. The method was to apply a pulse to start regenerative operation.

However, in this method, although it is only a short time that the switch 10A opens and the switch 10B closes, the regenerative side thyristor converter 2B
However, it takes 100msec to start flowing the regenerative current.
It takes 200mse, during which the speed and current deviations are accumulated, so the thyristor conversion device 2 on the regeneration side
When the motor B enters the control state, the current supplied to the DC motor 3 overshoots, giving a shock to the car 6, resulting in a significant deterioration of riding comfort. The above-mentioned phenomenon also applies to switching during descending operation of the elevator or switching from the regeneration side to the power running side.

Also, for example, as in JP-A-55-74390,
Some documents state that if the output of the thyristor conversion device at the time of switching is made to match the induced voltage of the motor at that time, the time required for switching can be improved to the same level as the circulating current type thyristor Leonard method. However, this is based on the condition that the torque constant Φ of the electric motor is constant, and a practical problem remains.

The present invention has been developed in view of the above points, and even if the torque constant of the motor changes due to temperature rise, etc., it is possible to shorten the time required to accurately switch the current direction, and to smoothly change the motor torque. An object of the present invention is to provide an elevator speed control device that can improve riding comfort.

Therefore, in the present invention, when switching the current direction, for example, the value of the phase shifter input signal at the time when the thyristor conversion device 2B starts the control operation is changed from the conventional r
By setting the output to the value equivalent to the optimum phase shift calculated from the value of the phase shifter input at the time when the load current becomes zero and the thyristor conversion device 2A stops the control operation, instead of setting it to a value equivalent to the limit, switching can be performed. This shortens the time required.

The present invention will be explained in detail below. First, the two thyristor conversion devices 2A and 2B in FIG.
The common phase shifter characteristics are expressed by the following equation.

α=e/2V×180+90 [deg] Here, α is the control delay angle, e is the phase shifter input voltage (e=variable range from −V to +V), and V is the reference voltage. A phase shifter having such characteristics can be easily realized, for example, by using a sawtooth wave signal with an amplitude width of 2V as shown in FIG. 2b for the power supply voltage waveform shown in FIG. 2a.

Now, for example, as shown in FIG. 4, the first thyristor conversion device 2A has six thyristors SR ₁ ,
In the case of a three-phase pure bridge circuit consisting of SR _{2 ,} SS ₁ , SS ₂ , ST 1 , and ST ₂ , when it is controlled by the input voltage e to the phase shifter 9 and the control delay angle α, for example, as shown in FIG. The waveforms of phase voltages R, S, and T shown in
Gate pulse of the phase shifter shown in figure b (G _SR1 is the gate pulse of thyristor SR ₁ , G _SR2 is the gate pulse of thyristor SR ₂
G _SS1 is the gate pulse of thyristor SS ₁ , G _SS2 is the gate pulse of thyristor SS ₂ ,
G _ST1 indicates the gate pulse of thyristor ST _{1 ,} and G _ST2 indicates the gate pulse of thyristor ST ₂ ). Assuming that the line voltage (R-S), (S-T), (T-
R) corresponds to the waveform shown by the solid line in FIG. 5c. Incidentally, when the current is flowing continuously and the control delay angle α is α=90°, the output voltage E _2A of the thyristor converter 2A has positive polarity and negative polarity as shown in FIG. voltages appear alternately, the average voltage becomes a waveform of OV, and as the control delay angle α increases, the voltage completely changes to negative polarity. Then, when the thyristor converter 2A is operated at a control delay angle α ₁ corresponding to the input voltage e ₁ of the phase shifter 9, the current command value becomes zero, the current feedback also decreases to zero, and the switch 10A opens. In this case, since the load current is zero when the switch 10A is open, the peak value of the output voltage _E2A of the thyristor converter 2A, that is, the two-dot chain line in Figure 5c (when the current flows continuously) It is assumed that the peak value P of the DC motor 3 is equal to the back electromotive force Ea of the DC motor 3.

By the way, as shown in FIG. 5b, the origin of the sawtooth wave that determines the generation timing of the gate pulse _GSR1 of the thyristor _SR1 , for example, is between the phase inversion voltage of the line voltage ST and the line voltage shown in FIG. 5c. This is the intersection point (natural commutation point) of the voltage R-S, and the control delay angle is also measured from this intersection point, but since the intersection point is 30° ahead of the maximum value of the line voltage R-S, the control delay angle If we try to express the magnitude of the line voltage at α ₁ mathematically, it becomes √2Ecos (α ₁ - 30°) (where E is the effective value of the three-phase AC line voltage), so in the end, √2Ecos (α ₁ −30°) = Ea (however, 180°≧α ₁ ≧30°) ………The relational expression (2) holds true.

On the other hand, six thyristors SR ₁ ', shown in FIG.
When the back electromotive force of the DC motor 3 is Ea in the second thyristor conversion device 2B consisting of a three-phase pure bridge circuit of SR ₂ ′, SS ₁ ′, SS _{2 ′} , ST _{1 ′} , and ST 2 ′,
If the control delay angle at which the current becomes zero at the start of operation when the thyristor conversion device 2B starts control is α ₂ , then
The peak value Q of the output voltage at the time of ignition of the thyristor converter 2B shown in FIG. ), and if this relationship is expressed as a cos function, as in the case of equation (2), for example, the control delay angle α ₂ that generates the gate pulse G _SR1 ′ of the thyristor SR ₁ ′ is the 7th As shown in Figure c, it can be expressed as √2Ecos (α ₂ −30°) = −Ea (180°≧α ₂ ≧30°) (3).

Then, to summarize equations (2) and (3), √2Ecos (α ₁ -30°) + √2Ecos (α ₂ -30°) = 0 ∴cos (α ₁ -30°) + cos (α ₂ -30゜)=0 ......(4)

This equation (4) is converted into the following trigonometric formula: cosθ+cosβ=2cos(θ+β)/2・cos(θ−β)/
If we rearrange using 2, (α ₁ + α ₂ −60°) / 2 = 90° → α ₁ + α ₂ = 240°...
…(5) (α ₁ − α ₂ )/2 = 90° → α ₁ − α ₂ = 180° ………(6) Therefore, it can be seen that either of these relationships should hold, but α ₁ and α ₂ are both 180°≧
Equation (6) is impossible due to the conditions of α ₁ ≧30° and 180°≧α ₂ ≧30°, and the relationship between control delay angles α ₁ and α ₂ is derived from equation (5).

Here, the following two relational expressions are obtained from equation (1), assuming that the phase shifter inputs for the control delay angles α ₁ and α ₂ are e ₁ and e ₂ , respectively. α ₁ = e ₁ /2V×180° + 90° ………(7) α ₂ = e ₂ /2V×180゜＋90゜ ………(8) Substituting α ₁ and α ₂ into equation (5) to find e ₂ gives e ₁ /2V×180゜+90゜+e ₂ /2V×180゜+90゜=240゜e ₂ =2/3V−e ₁ ......The following relationship (9) is established.

Therefore, if the input voltage to the phase shifter 9 when the switch 10B is closed is selected to be a voltage _e2 that satisfies the relationship in equation (9), the current direction can be switched most smoothly. become. An example of a circuit configuration that satisfies the relationship of equation (9) is shown in FIG.

In the figure, SW is open while the current regulator 8 is operating;
In the process of switching the current direction, switch 1
A switch that closes on the condition that 0A and 10B are open, 13 is a phase shifter input calculation device consisting of a differential amplifier with high gain characteristics consisting of resistors r9 and r10 and an operational amplifier OP2, R1 and R2
14 is a phase shifter input holding device consisting of a resistor with the same resistance value, 14 is a sample and hold circuit that holds the value of the phase shifter input signal, which is an input signal, by a hold signal SWa at the same time as the switch SW closes, 15 is 1/ The 3V voltage source and other parts that are the same as in FIG. 1 are indicated by the same symbols, and the configuration of omitted parts is the same as in FIG. 1. Note that the current regulator 8 has resistors r1 to
r4, capacitor C1, and operational amplifier OP1 constitute a so-called P1 regulator.

With the above configuration, if we consider a case where the current direction is switched while the thyristor converter 2A is in operation, the hold signal SWa will be activated at the same time as the switch 10A is opened and the switch SW is closed.
Therefore, the phase shifter input e ₁ at that time is held in the phase shifter input holding device 14, and the output thereof, that is, the potential at point b is also held at e ₁ . Therefore, resistors R1, R2,
The phase shifter input arithmetic unit 13 is operated by the voltage source 15. If the potential at point a is ea, then ea+e ₁ /2=1/3V (10) That is, ea=2/3V-, which is the same as the equation (9) above. An input signal is given to the current regulator 8 via the switch SW so that e ₁ is obtained. Then, after a certain period of time, switch 10
B is closed and the operation of the thyristor converter 2B is started. At this time, the phase shifter input e ₂ is expressed by equation (10).
It can be seen that this corresponds to ea, and therefore formula (9) is satisfied. Also, when switch 10B is closed, the switch
SW is opened, hold signal SWa is released,
The phase shifter input holding device 14 consisting of a sample and hold circuit starts sampling again. Therefore, according to this configuration, when the current direction is switched, the output voltage of the current regulator 8 becomes the optimum value based on the torque constant of the motor at that time immediately after the switch, so speed control is stopped. Not only is the time required for this process reduced to about 1/10 compared to conventional methods, but there is no problem with motor torque fluctuations. Although the above description has been made regarding the case of switching from driving to regenerative braking, it is clear that the same means can be applied to the reverse case as well.

As described above, according to the present invention, the initial setting value of the firing phase of the thyristor converter that newly operates when the current direction is switched is set to the input signal of the phase shifter that changes according to the torque constant of the electric motor before switching. Since the configuration allows optimal settings to be made based on the current direction, the stop time of speed control due to switching of current direction can be significantly shortened compared to conventional methods, there is almost no current overshoot when switching, and sudden torque changes of the motor can be avoided. It is possible to reduce the impact on the car caused by the car and improve riding comfort.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an elevator speed control device, Fig. 2 a and b are explanatory diagrams showing characteristics of a phase shifter, and Fig. 3 is an elevator speed control device which is an embodiment of the present invention. A block diagram showing the main parts of
FIG. 4 is a circuit diagram of the thyristor conversion devices 2A and 2B, FIG. 5 is an explanatory diagram for explaining the operation of the thyristor conversion device 2A, and FIG. 6 is a control delay angle α=
The output voltage waveform diagram of the thyristor conversion device 2A at 90°, FIG. 7, is an explanatory diagram for explaining the operation of the thyristor conversion device 2B. 2A, 2B...Thyristor conversion device, 3...DC motor, 9...Phase shifter, 10A, 10B, SW
... Switch, e ₁ , e ₂ ... Input signal voltage to phase shifter 9, 13 ... Phase shifter input calculation device, 14 ... Phase shifter input holding device.

Claims (1)

[Claims] 1. A non-circulating current type reversible stationary Leonard device having a first thyristor converting device and a second thyristor converting device is used, and the first thyristor converting device and the second thyristor converting device are A first control device that controls a DC motor for driving an elevator by changing the ignition phase of the device using a phase shifter, and interrupts the gate pulse of the first thyristor conversion device when switching the direction of the load current of the DC motor. and a second pulse cutoff device that releases the cutoff of the gate pulse of the second thyristor conversion device after a predetermined period of time has elapsed after the operation of the pulse cutoff device. An input signal e ₁ to the phase shifter that determines the firing phase of the first thyristor conversion device at the time when the first pulse cutoff device operates (provided that −v≦e ₁
≦v) and a phase shifter input holding device that holds and outputs
At the time when the second pulse cutoff device releases the cutoff of the gate pulse, the initial input signal _e2 to the phase shifter is changed to _e2.
Equipped with a phase shifter input calculation device that calculates from the relational expression =2/3v-e ₁ , the phase shifter receives a reference sawtooth wave signal and input signals (including e ₁ and e ₂ ) that determine the gate pulse generation timing. A speed control device for an elevator, characterized in that firing phases of the first thyristor converting device and the second thyristor converting device are determined by comparison with the first thyristor converting device and the second thyristor converting device.