Toshiba VF-S9 Types of PI control interfaces, Setting PI control, P-gain adjustment parameter

Feedback input data

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2) Types of PI control interfaces

Process quantity input data (frequency) and feedback input data can be combined as follows for the PI con- trol of the VF-S9:

Process quantity input data (frequency setting)

Setting method		Frequency setting mode
(1)	Internal potentiometer setting		External analog input
(2)	Panel input setting		(1)II(DC:4 ∼ 20mA)
			(2)VIA(DC:0 ∼ 10V)
(3)	Internal preset-speed setting

(4)External analog setting VIB (DC: 0-10V)

Note: When PI control is selected ( = "1"), frequency priority selection ( ) is disabled. In this case, therefore, since II or VIA is reserved for feedback signal input only, frequency setting by switching to VIB cannot be executed.

3) Setting PI control

Set " " in the extended parameter (PI control).

	(1)		Set parameters	(acceleration time) and			(deceleration time) to their minimum values (0.1
			sec).
		(2) To limit the output frequency, set parameters					(upper limit frequency) and (lower limit fre-
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			quency). If process quantities are set from the operation panel, however, the process quantity setting
			range will be limited by the settings of and .
	4) Adjusting the PI control gain level
		Adjust the PI control gain level according to the process quantities, the feedback signals and the object to be
		controlled.
		The following parameters are provided for gain adjustment:
		Parameter			Setting range			Default setting
			(P-gain)		0.01 ∼	100.0		0.30
			(I-gain)		0.01 ∼	100.0		0.20

(P-gain adjustment parameter)

This parameter adjusts the proportional gain level during PI control. A correction value proportional to the particular deviation (the difference between the set frequency and the feedback value) is obtained by multiplying this deviation by the parameter setting.

A larger P-gain adjustment value gives faster response. Too large an adjustment value, however, re- sults in an unstable event such as hunting.

Process quantity setting value

Fast response

Slow response

Time

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