Hitachi SJ700-2 instruction manual Sensorless vector, 0 Hz domain control, Zero LV lmit

Related code A001: Frequency source setting

A044/A244: V/F characteristic curve selection, 1st/2nd motors

F001: Output frequency setting

b040: Torque limit selection

b041 to b044: Torque limit (1) to (4)

H002/H202: Motor data selection, 1st/2nd motors

H003/H203: Motor capacity, 1st/2nd motors

H004/H204: Motor poles setting, 1st/2nd motors

H005/H205: Motor speed constant, 1st/2nd motors

H020/H220: Motor constant R1, 1st/2nd motors

H021/H221: Motor constant R2, 1st/2nd motors

H022/H222: Motor constant L, 1st/2nd motors

H023/H223: Motor constant Io, 1st/2nd motors

H024/H224: Motor constant J, 1st/2nd motors

H050/H250: PI proportional gain, 1st/2nd motors

H051/H251: PI integral gain, 1st/2nd motors

H052/H252: P proportional gain setting, 1st/2nd motors

H060/H260: Zero LV lmit, 1st/2nd motors

H061/H261: Zero LV starting boost current, 1st/2nd motors

Chapter 4 Explanation of Functions

4.2.97 Sensorless vector, 0 Hz domain control

The 0Hz domain sensorless vector (SLV) control function incorporates Hitachi’s own torque control system and enables high-torque operation in the 0Hz range (0 to 3 Hz). This control function is best suited for driving a lifting machine, e.g., crane or hoist, that requires sufficient torque when starting at a low frequency.

To use this function, specify "04" for the V/F characteristic curve selection (A044/A244).

Before using this function, be sure to optimize constant settings for the motor with reference to Section 4.2.91, "Motor constant selection."

The parameters related to the 0Hz-range sensorless vector control are as follows:

1) The Zero LV lmit for 1st/2nd motors (H060/H260) is the parameter that specifies the output current for the constant-current control in the 0 Hz range (about 3.0 Hz or less). The parameter value is expressed as a ratio of the output current to the inverter's rated current.

2)The Zero LV starting boost current (H061/H261) is the parameter to specify the current for boosting at motor start-up with a frequency in the 0 Hz range. The parameter value is expressed as a ratio of the boost current to the inverter's rated current. The value of the boost current is added to the current value specified by "H060/H260" only at starting.

Item	Function code	Range of data	Description
Zero LV lmit	H060/H260	0.0 to 100.0 (%)	Current limiter for the low-speed range
Zero LV starting boost current	H061/H261	0. to 50. (%)	Quantity of boost current at starting

When using this function, observe the following precautions:

1)Be sure to use an inverter of which the capacity is one class higher than the motor to be driven.

2)If you use the inverter to drive a motor of which the capacity is two classes lower than the maximum applicable capacity of the inverter, you may not be able to obtain adequate motor characteristics.

3)If you cannot obtain desired characteristics from the motor driven under the 0Hz-range sensorless vector control, readjust the motor constants according to the symptom as described in the table below.

Operation	Symptom	Adjustment method	Adjustment item
status
	Momentary speed	Increase the motor constant R2 step by step from the	H021/H221/H031
Powering	variation is negative.	set value up to 1.2 times as high as the set value.
	Momentary speed	Reduce the motor constant R2 step by step from the set	H021/H221/H031
	variation is positive.	value down to 0.8 times as high as the set value.
	Torque is insufficient at	Increase the motor constant R1 step by step from the	H020/H220/H030
Regenerating	low frequencies	set value up to 1.2 times as high as the set value.
		Increase the motor constant I0 step by step from the set
	(several Hz)		H023/H223/H033
		value up to 1.2 times as high as the set value.
Starting	The motor generates an	Reduce the motor constant J from the set value.	H024/H224/H034
	impact when it starts.
Decelerating	The motor runs	Reduce the speed response setting.	H005/H205
	unsteadily.	Reduce the motor constant J from the set value.	H024/H224/H034
Immediately	Overcurrent or	Reduce the motor constant I0 step by step from the set	H023/H223/H033
after	overvoltage protection	value down to 0.8 times as high as the set value.
		Specify "00" (always on) or "01" (always off) for the AVR	A081
deceleration	function operates.
		function select (A081).
Low-frequency	Motor rotation is	Increase the motor constant J from the set value.	H024/H224/H034
operation	inconsistent.

Note 1: Always set the carrier frequency (b083) to 2.1 kHz or more. If the carrier frequency is less than 2.1 kHz, the inverter cannot operate the motor normally.

Note 2: Adjust the torque limit (b041 to b044) so that the value "α" calculated by the expression below does not exceed 200%. Otherwise, the motor may be burnt out.

α= "torque limit" x (inverter capacity)/(motor capacity)

(Example) When the inverter capacity is 0.75 kW and the motor capacity is 0.4 kW, the torque limit value is calculated as follows on the assumption that the value "α" should be 200%: Torque limit (b041 to b044) = α x (motor capacity)/(inverter capacity) = 200% x (0.4 kW)/(0.75 kW) = 106%

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