Toshiba VF-A7 Avoiding over-voltage trip, Adjusting the output voltage and voltage compensation

6.13.5 Avoiding over-voltage trip

 ：Over-voltage stall protection

 ：Over-voltage stall protection level (high response)

 ：Over-voltage stall protection level

・Function

The functions automatically keep constant or increase the output frequency to prevent tripping due to over-voltage in the DC bus during deceleration or constant-speed run. When the over-voltage stall protection is active, it may take longer than the deceleration time.

Maximum frequency

Output frequency

Set deceleration time

DC voltage

～

～

[Parameter setting]

If DC voltage rise and reach the level set up by , output frequency will be controlled in order to control this rise. If DC voltage rise more and reach the level set up by , this control operation is performed with high response.

Real deceleration time (differ from regenerative power)

←Over voltage stall protection level (high response) : 

←Over voltage stall protection level : 

Title	Function	Adjustment range		Default setting
	Over-voltage stall protection	: Enabled, : Disabled,		
		: Enabled (forced quick deceleration)
	Over-voltage stall protection level	～ [%]	(*2)	
	(high response)
 Over-voltage stall protection level (*1)		～ [%]	(*2)	

(*1)  serves also as the level of dynamic (regenerative) braking operation.(Refer to 6.13.4)

(*2) 100% (200V class = 200×√2 [V], 400V class = 400×√2 [V])

6.13.6 Adjusting the output voltage and voltage compensation

 ：Voltage of base frequency(output voltage adjustment)

 ：Selection of base frequency voltage(voltage compensation)

・Function

Voltage of base frequency (output voltage adjustment)

This parameter set the base frequency  voltage. And this parameter can make it so that no voltage exceeding the  value is put out. (This function is active when  is set  or .)

Selection of base frequency voltage (voltage compensation)

The function keeps the V/f ratio constant for prevention of torque drop at low speeds even when the input voltage drop.

○Voltage compensation... The V/f ratio is kept constant even at input voltage fluctuation.

○Voltage limitation ... The output voltage is limited to . If the voltage compensation fun ction is disabled, no limitation is imposed to the output voltage.

[Parameter setting]

Title	Function	Adjustment range	Default setting
	Base frequency voltage #1	～ [V]	 [V]
	(output voltage adjustment)		/ [V]
		: without voltage compensation(limitless output voltage)
	Base frequency voltage	: with voltage compensation(limitless output voltage)	
	(voltage compensation)	: without voltage compensation(limited output voltage)

: with voltage compensation(limited output voltage)

☆If  is set at  or , the output voltage varies with the input voltage.

☆The output voltage does not exceed the input voltage, even if the base frequency voltage () is set above the input voltage.

F-29