Jan 19, 2016
DC/AC Converter ControlTorque and Flux Control
• Converter circuit
+ Motor
• Control design– Design sliding surface for torque and flux
– Lyapunov function
denote
S1
S4 S2
S5S3
S6
(U_m)
-(U_m)
ia
ic
ib
va
vb
vc
Motor
Torque & Flux Control (approach 2)
• Cascade Control– From torque and flux equations:
where
– Desired can be calculated– Sliding mode to provide desired current
Cascade Sliding Mode Control
• Idea: Utilize extra degree of freedom
• Sliding surface design L R
S1
S4 S2
S5S3
S6
(U_dc)
-(U_dc)
n
ia
ic
ib
va
vb
vc
Ea
Eb
Ec
Lyapunov Approach• Select control logic based on Lyapunov
function such that sliding mode is enforced
• Advantage: simple
ControlLogic
Decoupling Approach to Enforce Sliding Mode
• Idea: to decouple motions in
• Method: non-singular transformation:
• Advantage: allows frequency analysis performed for each surface individually
ControlLogic
Vn Control• Objective: optimality
by changing• Example: switching
frequency reduction
ont offt
Slidling Surface
Experimental Setup
• Controller: TMS320F2812 DSP• Switching devices: 2MBI100NC-12 IGBT• 3 phase RL load• 50 V DC supply
DSP Board
Full Bridge Converter
PWM Signal
DC Voltage
Current Measurements
Load
The first waveforms show the current tracking (and ), the second ones show tracking as a sinusoidal function by the average value of (after filtering out a high frequency component of discontinuous function ).