JPH02114829A - Control circuit for flywheel power storage unit - Google Patents

Abstract

PURPOSE:To prevent unstable operation of a control circuit system even upon droppage of actual rotation by varying the gain of a voltage loop for performing regeneration of power source for an induction motor having a flywheel corresponding to the actual rotation of the induction motor. CONSTITUTION:A variable gain circuit 15 is arranged between a subtractor 10 and on adder 12. The variable gain circuit 15 functions to vary the gain(AV) of e voltage loop corresponding to the actual speed WM, i.e., actual rotation, of an induction motor 6. In other words, the gain AV of the voltage loop is increased as the actual rotation increases. Consequently, the gain AV of the voltage loop is maintained constant regardless of a speed command W1. By such arrangement, power source can be regenerated quite stably without causing vibration in the control circuit system even upon droppage of rotation of the induction motor.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is directed to an induction motor I! The present invention relates to a control circuit for a flywheel power storage device based on i(IM).

[Prior Art] FIG. 3 is a diagram showing a control circuit for a flywheel power storage device using a conventional induction motor. In the control circuit as shown in FIG. 3, an AC voltage input from an AC power source 1 is converted into a DC voltage by a rectifier diode 2. This DC voltage is subjected to pulse width modulation (PWM) to control the induction motor (1M) 6 as described later. A flywheel 7 is attached to the induction motor 6. Rectifier diode 2
is converted to DC voltage by capacitor 3 (C3[F
l), that is, the actual DC bus voltage vDc
is converted into an alternating current voltage through the DC/AC converter 5 and supplied to the load 8. The subtracter 10 takes the difference voltage between the command value VDC of the DC bus voltage and the actual DC bus voltage VDC, and this difference voltage is multiplied by G by the amplifier 11, and its output is used as the slip frequency command W3.

On the other hand, a speed detector (TG
) 9 to detect the actual speed WM of the induction motor 6. The adder 12 sums the actual speed wM and the edge frequency command W5, and outputs the sum as the pulse width modulation (PWM) speed command W1.
shall be. This speed command W1 is obtained through the V/F pattern (voltage command for frequency) voltage command v(,) through the circuit 3. This voltage command A PWM pattern of the output element 4 to be driven is generated.

Now, if a power outage occurs in the AC power supply 1 on the input side and power is no longer supplied, if the load 8 of the output I continues to be connected, the actual DC bus voltage VDC will begin to decrease. Then, the actual DC bus voltage VDC is the command value V1) of the DC water bus voltage. Since it becomes smaller than
The helical frequency command W9, which is the output of the amplifier 11, is negative (-), so the speed command W1 is equal to the actual speed W.
Since it is smaller than M, it becomes a deceleration command. Therefore, P
Since the WM pattern generator 14 generates a deceleration pattern, the induction motor 6 starts decelerating. However, since a flywheel (PL) 7 is attached to the induction motor 6, the flywheel 7 converts the energy into mechanical energy or electrical energy, resulting in the actual DC bus voltage.
. .

Actual DC bus voltage■. . prevent it from descending.

As described above, in the event of a power outage, etc., the AC power supply 1 on the input side
Even if power is no longer supplied, the rotational energy of the flywheel 7 attached to the induction motor 6 is converted into electrical energy and regenerated to the actual DC bus voltage VDC, so that the actual DC bus voltage VDC increases. It prevents a voltage drop and continues to supply power to the load 8 on the output side.

FIG. 4 is an explanatory diagram showing the operation of the voltage loop in the control circuit of the flywheel power storage device using the induction motor of FIG. 3. FIG. In the block diagram not shown in FIG. 4, in the case of the induction motor 6, the motor torque TM can be expressed as follows.

Further, there is a relationship between motor power WM - TM Wl.

The motor power WM minus the load power WL is the amount stored in the capacitor 3 as the actual DC bus voltage VDC.

If we integrate this and divide by C1, we get the actual DC bus voltage VD.
C is obtained. When the gain (transfer function) AV of a voltage loop that goes around such a voltage loop is found, it becomes as follows.

Here, since the motor voltage vO is constant in the high speed range (region where the speed command w1 is large) in the V/F pattern circuit 13, the gain AV of the voltage loop 1 is proportional to -.

[Problems to be Solved by the Invention] In the conventional control circuit for a flywheel power storage device using an induction motor as described above, the open loop gain of the voltage loop becomes thicker as the speed command w1 becomes smaller. Therefore, as the actual speed wM of the induction motor 6 decreases after a power outage occurs in the AC power supply 1 on the input side, the gain AV of the voltage loop increases, which causes the control circuit system to oscillate and become unstable. There was a point.

This invention was made to solve the above problems, and it is a flywheel power storage device that prevents the control circuit system from becoming unstable even if the actual rotational speed, which is the actual speed of the induction motor, decreases. The purpose is to obtain a control circuit.

[Means for Solving the Problems] A control circuit for a flywheel power storage device according to the present invention incorporates the gain of this voltage loop into a voltage loop for performing power regeneration of an induction motor having a flywheel. This configuration includes a variable gain circuit that changes according to the actual rotational speed.

[Function] In the control circuit of the flywheel power storage device according to the present invention, a variable cane circuit installed in a voltage loop for regenerating power of an induction motor having a flywheel adjusts the speed according to the actual rotation speed of the induction motor. Since the gain of the voltage loop (1) is changed, stable power regeneration without vibration can be performed even when the rotational speed of the induction motor decreases.

[Embodiment] FIG. 1 is a diagram showing a control circuit of a flywheel power storage device using an induction motor according to an embodiment of the present invention. The control circuit shown in FIG. 1 differs from the control circuit shown in FIG. 3 above in that a variable cane circuit 15 is provided between the subtracter 10 and the adder 12. , the other circuit configurations are the same.

Therefore, since the specific circuit configuration and basic operation of the control circuit according to the embodiment of the present invention shown in FIG. 1 are the same as those of the conventional example shown in FIG. 3, a detailed explanation thereof will be omitted.

FIGS. 2(a) and 2(b) are explanatory diagrams showing the operation of the variable gain circuit in the control circuit of the flywheel power storage device using the induction motor of FIG. 1, and a diagram of its operating characteristics. The variable gain circuit 15 shown in FIG. 1 works to change the gain AV of the voltage loop according to the actual speed wM of the induction motor 6, that is, the actual rotational speed.

Therefore, as shown in the operating characteristic diagram of FIG. 2(b), if the voltage loop gain A, v is increased together with the actual rotational speed, which is the actual speed WM of the induction motor 6, a Novnc: WMGI Therefore, the gain AV of the voltage loop becomes
It becomes a constant value regardless of the speed command w1.

Although the above embodiment shows an example in which the gain of the variable gain circuit 15 is varied in accordance with the actual speed WM of the induction motor 6, it may be varied in accordance with the speed command w1.

[Effects of the Invention] As described above, according to the control circuit of the flywheel power storage device of the present invention, the gain of this voltage loop is added to the voltage loop for regenerating the power of an induction motor having a flywheel. The configuration is equipped with a variable cane circuit that changes the speed according to the actual rotation speed of the motor, so even if the rotation speed of the induction motor decreases, extremely stable power regeneration is achieved without causing vibration in the control circuit system. It has the excellent effect of being able to realize the following.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a control circuit of a flywheel power storage device using an induction motor as an embodiment of the present invention, and FIG. 2(a)
and (b) is an explanatory diagram showing the operation of the variable gain circuit in the control circuit of the flywheel power storage device using an induction motor in FIG. Diagram showing the circuit,
FIG. 4 is an explanatory diagram showing the operation of the voltage loop in the control circuit of the flywheel power storage device using the induction motor of FIG. 3. FIG. In the figure, 1... AC power supply, 2... Rectifier diode, 3... Capacitor (CI[F]), 4... Output element, 5... DC/AC converter, 6... Induction Electric motor (IM), 7...Flywheel (FL), 8...Load, 9...Speed detector (TG), 1.0...Subtractor, ]1...Amplifier, 12... Adder, 13...V/
F pattern circuit, 14...PWM pattern generator, 15
...It is a variable Kane circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent: Masu Oiwa April 4, 1939

Claims (1)

[Claims] A first means for obtaining an error voltage between the command value of the DC bus voltage and the actual DC bus voltage, a second means for amplifying the error voltage by the first means, and an output of the second means and a flywheel. The third sum of the actual speed of the induction motor with
and a variable voltage/variable frequency inverter that uses the output as a command frequency and drives the induction motor. When regenerating the power of the induction motor mentioned above,
A control circuit for a flywheel power storage device, wherein the second means is constituted by a variable gain circuit that changes the amplification gain according to the actual rotational speed of the induction motor.