Hitachi AN070827-1 User manual

Brand: Hitachi

Model: AN070827-1

Category: Split-system air conditioners

Type: User manual

Hitachi AN070827-1 is an application note for the SJ300 AC inverter. It provides instructions on how to fine-tune the closed-loop vector control for low-frequency and zero-speed operation. This can be useful in applications where precise speed control is required at low speeds or when the motor needs to be stopped completely without drifting.

The application note covers the following topics:

How to adjust the motor parameters, including the inertia parameter (J)
How to disable the speed-observing function
How to use an encoder with a higher pulse per revolution (PPR) to improve performance at lower speeds

The application note covers the following topics:

How to adjust the motor parameters, including the inertia parameter (J)
How to disable the speed-observing function
How to use an encoder with a higher pulse per revolution (PPR) to improve performance at lower speeds

AC INVERTER

Application Note:

SJ300 Fine Adjustment of

Closed-Loop Vector Control

for Low Frequency and Zero

Speed Operation

Please refer also to the relevant

Inverter Instruction Manual

AN070827-1

Hitachi America, Ltd.

1. Inverter model

SJ300

2. Control

Vector Control (V2 mode)

3. Application

General applications where operation at low speed or zero speed

operation is required.

4. Phenomenon

Actual rotation of the motor does not match the target speed, or the

rotation becomes unstable in the low frequency range (roughly less than

1 Hz). Or the motor shaft creeps even with a 0 Hz speed reference.

5. Cause of the phenomenon

V2 (closed-loop vector) control is a speed control method based on

calculating shaft speed from the pulse train input from the motor encoder.

In the case of low speed, the number of input pulses decrease and it

becomes difficult to count them within the pulse counting period.

Therefore on SJ300 V2 mode, in the absence of encoder pulses, the

process of motor speed estimation (speed observing) is done by using

information like motor current, motor parameters, etc. This process is an

estimation, and will have some errors. It sometimes results in instability

as described above in item 4.

Speed observer

Speed detection when there

are pulses from the encoder

Encoder pulse

Speed data for

speed control

Motor constants

Motor current

6. How to adjust

(1) Adjust motor parameters, inertia parameter (J) in particular, and try to

obtain optimal motor performance.

(2) Disable the speed-observing function by the following method:

c Set debug mode ON ([C091] = “01” and STR) using the standard

keypad (cannot be changed via ProDrive)

d Configure a value of “4000” into [C193] and STR (default is “0000”)

This change disables the speed observer function.

e Set debug mode OFF ([C091] = “00” and STR

(3) This phenomenon occurs at low speed. Therefore using an encoder

having a higher PPR (pulse per revolution) will improve performance at

lower speeds.

Hitachi America, Ltd.

Hitachi AN070827-1 User manual

Brand: Hitachi

Model: AN070827-1

Category: Split-system air conditioners

Type: User manual

The application note covers the following topics:

How to adjust the motor parameters, including the inertia parameter (J)
How to disable the speed-observing function
How to use an encoder with a higher pulse per revolution (PPR) to improve performance at lower speeds

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Hitachi AN070827-1 User manual

Hitachi AN070827-1 User manual

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