B3: Speed Search - YASKAWA A1000 HHP Programming Manual

n b2-08: Magnetic Flux Compensation Value
Sets the magnetic flux compensation at start as a percentage of the no-load current value (E2-03). This function allows for the
development of more flux to facilitate starting machines that require high starting torque or motors with a large rotor time
constant.
No.
b2-08
When a Run command is issued, the DC current level injected into the motor changes linearly from the level set to b2-08 to
the level set to E2-03 within the time set to b2-03.
When b2-08 ≠ 0%, the current will flow for the time set in b2-03 (DC Injection Braking Time at Start) when DC Injection
Braking starts. The current will change linearly from the setting of b2-08 to the setting of E2-03.
The level of the DC current injected to the motor is limited to 80% of the drive rated current or to the motor rated current,
whichever value is smaller.
Note: 1. If b2-08 is set below 100%, it can take a relatively long time for flux to develop.
2. If b2-08 is set to 0%, the DC current level will be the DC Injection current set to b2-02.
3. As DC Injection can generate a fair amount of noise, b2-08 may need to be adjusted to keep noise levels acceptable.
u

b3: Speed Search

The Speed Search function allows the drive to detect the speed of a rotating motor shaft that is driven by external forces and
start the motor operation directly from the detected speed without first stopping the machine.
Example: When a momentary loss of power occurs, the drive output shuts off and the motor coasts. When power returns, the
drive can find the speed of the coasting motor and restart it directly.
Enabling Speed Search for PM motors only requires setting parameter b3-01 to 1.
The drive offers current detection and speed estimation Speed Search for induction motors. Parameter b3-24 selects the speed
search method for induction motors. Both methods and relevant parameters are explained below.
n Current Detection Speed Search (b3-24 = 0)
Current Detection Speed Search detects the motor speed by looking at motor current in IM motors. When Speed Search is
started it reduces the output frequency starting from either the maximum output frequency or the frequency reference while
increasing the output voltage using the time set in parameter L2-04. As long as the current is higher than the level set to b3-02,
the output frequency is lowered using the time constant set to b3-03. If the output current falls below b3-02, the drive assumes
that the output frequency and motor speed are the same and accelerates or decelerates to the frequency reference.
Be aware that sudden acceleration may occur when using this method of Speed Search with relatively light loads.
Figure 1.15 illustrates Current Detection Speed Search operation after a momentary power loss (L2-01 must be set to 1 or 2):
YASKAWA ELECTRIC SIEP YEAHHP 01B YASKAWA AC Drive – A1000 HHP Programming Manual
Name
Magnetic Flux Compensation Value
Output frequency
b2-08
Magnetizing Current
Reference
Figure 1.14 Magnetic Flux Compensation
Setting Range
E2-03
Time
b2-03
1.2 b: Application
Default
0 to 1000% 0%
1
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