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3 Finite State Machine of Motor Control
The state of motor control can be shown by finite state machine (FSM). The following figure is the
FSM of BLDC in this software. It concludes four states, the states can be switched to other states
under the certain conditions.
1
Trunoff
4
Mode
5
3.1 State Discription
1.
Turnoff mode expresses that the rotation speed command from A/D converts is 0, and MCU
will not output PWM wave. Under this mode, if rotation speed command from A/D converts is
not equal to zero, motor work mode changes into bootstrap mode, the target rotation speed and
actual rotation are set to the minimum rotation speed, 1000rpm.
2. Bootstrap mode indicate that under the condition of single power supply for IPM module,
bootstrap circuit finish the function of charging for upper arm IGBT of 3 phase IGBT circuit. This
method is implemented by MCU outputting bootstrap-duty PWM wave. In order to prove to
enough charging time of upper arm IGBT, the bootstrap mode last certain time. When three
phase IGBT circuit bootstrap mode is finished, the motor work mode changes into turnon mode,
otherwise the bootstrap mode is continue.
When no rotation speed command is detected or three phase motor output control timer is
disabled, the motor work mode come back turnoff mode.
3. Turnon mode points motor starts to run while MCU outputs initial-duty PWM wave. Output
pattern switching is forcibly implemented by controlling PWM duty changing amount to calculate
motor rotation angle. Passing 1500 carrier wave cycle interrupt, motor work mode changes into
Run mode, or it will continue turnon mode.
When no rotation speed command is detected or three phase motor output control timer is
disabled, the motor work mode come back turnoff mode.
4. Run mode indicates that motor works normally while MCU outputs PWM wave by inputting
certain rotation speed command. And the rotation speed command is synchronous to rotate
magnetic field frequency, so zero-crossing of induced voltage can be detected accurately to
decide to output pattern stwiching by 50us timer interrupt.
When no rotation speed command is detected or three phase motor output control timer is
RSBJEUM0001-0101 Rev. 1.01
2
Bootstrap
9
Mode
6
7
3
Trunon
10
Mode
8
Run
11
Mode
17
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