JPS6152190A - Variable frequency power source system - Google Patents

Abstract

PURPOSE:To perform an energy-saving, a reduction of a cost by following via a variable frequency source (V power source) at load increase request time, and following via a mechanical control mechanism at load reduction request time, thereby eliminating the regenerative brake. CONSTITUTION:The fact that, when the output frequency of a V power source 2 is altered to vary the control responding speed and the opening theta of a vane 6, and the control responding speed is compared, the vane control is fast at wind amount reducing time and slow at wind amount increasing time is aimed to increase the frequency of the power source 2 to first respond when the load (wind amount) increases and to respond to reduce the opening theta of the vane 6 and to then reducing the frequency at load decreasing time, the frequency is then decreased to return the opening theta of the frequency to the original position, thereby accelerating the increasing response of the wind amount.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a variable frequency power supply system lζ that increases or decreases the output frequency of a variable frequency power supply that controls the rotational speed of an electric motor according to the load.

[Conventional technology]

Figure 1 is a diagram showing a conventional variable frequency power supply (hereinafter abbreviated as V power supply) system. An electric motor whose rotational speed is controlled, (4) is a fan, (5) is a coupler that connects this fan and electric motor (3),
(7) is the drive unit a of the vane (6), (a) is the drive unit f
control input to fi (7), (control input to September tv power supply (2), (IW is the wind duct (lla), (Ilb) is the entrance and exit of the wind duct, respectively, (θ) is the vane ( 6). Figure 2 also shows the vane opening (θ) in Figure 1 and the electric motor (loaded wind f of 3J) passing through air passage a21.
It is a Q-θ characteristic curve showing the relationship of fi (Q).

Next, the operation will be explained. ■Power source (2) is commercial power source (
The ta force received from υ is the desired ′iJ:1. 'The m force converted into a frequency corresponding to the rotation speed of the M machine (3) is supplied to the electric motor (3) to control the rotation speed.
) to drive the fan (4). The fan (4th one is the inlet Dia of the air passage (b)) sucks air from the outlet (llb).
) sends out wind fR(Q). A vane (6) is installed in the wind duct (2), and depending on its opening (θ), the wind a (
Q) can be changed. Also, wind ffi (Q)
In addition to the vane (6), changing the output frequency (F) of the power source (2) and changing the rotation speed (N) of the electric motor wax, that is, the fan (4) according to equation (1) The wind 1 (Q) and the rotation speed (N) are in a proportional relationship as shown in equation (2).

(P: Ultimate of electric motor (6)) Q QCN ・・・・・・・・・・・・・・・・・・
...... Equation (2) Wind ff1 (Q) and vane (6
) The relationship between the opening degree (θ) is as shown in Figure 2,
When the air volume (Q) obtained when the vane opening degree (θ) is 90° (total 8) is taken as 100%, the air volume is curved with almost no change when θ is around 90°.

During operation with normal VrIl source < February ζ, the required amount of load (thickness Q) is given as the control input ('l), and vw
The requirement is satisfied by changing the output frequency (F) of the L source (2).

(θ) receives a signal fixed to a predetermined value near 90°, and is fixed at that constant opening degree. This is because, from the point of view of energy saving, if the vane opening degree (θ) is made smaller, the energy saving effect will be reduced, so θ is set close to 90°.

Since the conventional variable frequency power supply system is configured as described above, the load (wind ff1Q) reduction request control input (
When there is
If regenerative braking is additionally installed in order to speed up the reduction response speed in 2), it will be expensive, and even if regenerative braking is added, the reduction response speed will not be sufficiently high if the inertia (GD2) of the shaft system is large. There were drawbacks such as.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and the output frequency (F
) to control the response speed and the opening degree of the vane (6) (θ
), if we compare the response speed of controlling the latter, the latter is
Focusing on the fact that it is faster when the wind j1 (Q) decreases and slower when the wind j1 (Q) increases, when the load (wind iQ) increases, 1ζ responds by increasing ■power supply frequency CF), and when the load decreases, the First, the response is made to reduce the vane opening (θ), and then the frequency (F) is decreased to reduce the vane opening (θ).
By restoring θ9 to the original value, an inexpensive variable frequency WL source system is provided that can quickly respond to increases and decreases in wind Jl (Q).

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Third
In the figure, QO is a control device, and @ and α1 are control signals from the control device aQ to the v power supply (2)% drive device (7), respectively.

Further, FIG. 4 is an example of a logic diagram of the control device 00, and 041
is the load judger, (to) is the output signal of the load judger α~, (
NOT) is a negative logic and outputs a logical signal opposite to the input, and aS and QQ are selectors 1 and 2, respectively.

Next, the operation will be explained.

The load determiner (14) outputs an output signal (to) when the control signal (9) waits for a load reduction request 1ζ, controls the selector 2 QQ by the output signal (to), and the control signal (9) outputs a load increase request. When there is no request or change, the output signal (TO) is not output, so it is inverted by a NOT circuit (NOT) to produce an output signal aη, and the selector 14 is controlled by the output signal Q?).

Selector 1 (to) outputs control input (9) as control signal (2) when there is a signal in output signal αη, and outputs control input (9) as control signal (2) when there is no signal in output signal αη.
9) and outputs it as a control signal (2).

On the other hand, selector 2 (LQ) outputs the control input (8) as a control signal (13) when there is no signal in the output signal (to), and the vane opening degree (θ) is fixed, and a signal is output in the output signal qQ. At this time, the control input (9) outputs a signal suitable for the vane opening degree (θ) required for the load air volume as the control signal Q3.

Since the control device αQ including the load determiner rs and the selector 1.2 operates as described above, the load air volume control signal (9)
If is an increase request, the output signal of load judger a4 (to)
Since the inverting circuit (NOT) outputs the output signal Q71 without any output, the control signal (9) is applied to the V power supply (2) via selector 1 (G) to increase its output frequency (F) to follow the load. . On the other hand, if the control signal (9) is a decrease request,
Load judger H outputs an output signal of 0, and selector 2 Q
A necessary control signal aa is generated by fli and applied to the drive device (7), and the opening degree (θ) of the vane (6) is changed to follow the load. The output signal Qlj of the load judger 1 outputs an output for the time required to follow the vane (6), and then disappears, resulting in a state where there is no load change. Therefore, once the follow-up to the load reduction request is completed, the control At the same time that the input (9) is applied to the V IZ source (2) to lower the output frequency (F), the control signal @ becomes the control signal (8) and returns to the original fixed value.

In the above embodiment, the fan (4) is rotated by an electric motor (3) and the air (air volume) is controlled by the vane (6), but the fan (4) may be any other rotating machine.
The air may be any other fluid, and the vane (6) may be any other mechanical control mechanism, with the same effects as in the embodiments described above.

〔Effect of the invention〕

As described above, according to the present invention, when the load is requested to increase, the V power supply follows the request, and when the load decrease is requested, the mechanical control mechanism such as a vane follows the groove bottom.
It is possible to sufficiently follow the load increase/decrease request without increasing the capacity of the power supply to increase the follow-up speed, and when the load increase request is made, the vane opening (θ) can be adjusted in all questions compared to the case where the vane etc. are used to follow the load increase request. Since the angle can be selected close to 90°, a large amount of energy can be saved, and there is no need for regenerative braking to stop the speed following the reduction request, which has the effect of making it possible to reduce the cost.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional variable frequency (V) II power supply system, FIG. 2 is a diagram showing the relationship between base opening and Mffi, and FIG. 3 is a configuration diagram of a V power supply system according to an embodiment of the present invention. FIG. 4 is an example of a logic diagram of the control device αQ. In the figure, (2) is a variable frequency (V) power supply, (3) is an electric motor, (4th is a rotating machine, (6) is a mechanical control mechanism,
(θ) is the opening degree, (7) is the drive device, 00 is the control device, (
8) is a control input that sets the opening degree (θ) to a predetermined value, (9) is a control input that provides a load request, α is a load judger, u, ae
are selectors 1 and 2, respectively. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] An electric motor whose rotation speed is controlled by a variable frequency power source, a rotating machine driven by the electric motor to transfer a load fluid, a mechanical control mechanism that regulates the amount of load fluid transferred by the rotating machine, and a mechanical control mechanism for regulating the amount of load fluid transferred by the rotating machine. and a load determiner that determines whether the control signal is an increase request or a decrease request, and when the load determiner determines that the load is an increase request, the output frequency of the variable frequency power source is increased to follow the load determiner. If the determination is a reduction request, the mechanical control mechanism follows the request, and then the output frequency of the variable frequency power source is lowered and the control position of the mechanical control mechanism is controlled to return to the desired position. variable frequency power supply system.