ee 459/559: control and applications of power electronics
TRANSCRIPT
EE 459/559: Control and Applications of Power Electronics
Luis HerreraDept. of Electrical Engineering
University at Buffalo
Spring 2021
Lecture 3: (State Space) Control of Power Electronics
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Outline
Why do we need control?
State feedback control for stabilization
Integral control for reference tracking
Inner/outer loop control for power electronics
3
State Space Average Model of a Buck Converter
4
Open Loop vs Closed Loop Performance
Compare the performance of the converter when operating as open loop and closed loop control
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Analysis of Closed Loop Behavior
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Outline
Why do we need control?
State feedback control for stabilization
Integral control for reference tracking
Inner/outer loop control for power electronics
7
State Feedback Problem Formulation
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Cayley Hamilton Theorem
9
Controllability Definition
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Controllability Matrix and Rank
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Example 1: Controllability and State Feedback
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Example 1: Controllability and State Feedback
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Example 1: Controllability and State Feedback
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Example 1: Controllability and State Feedback
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Outline
Why do we need control?
State feedback control for stabilization
Integral control for reference tracking
Inner/outer loop control for power electronics
16
State Feedback and Reference Tracking
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Problem Definition
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Integral Control
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Integrator + State Feedback
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Integrator + State Feedback: Steady State
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Boost Converter Example: Voltage Tracking
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Boost Converter Example: Voltage Tracking Diagram
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Boost Converter Example: Voltage Tracking Design
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Boost Converter Example: Voltage Tracking Results
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Outline
Why do we need control?
State feedback control for stabilization
Integral control for reference tracking
Inner/outer loop control for power electronics
Power Electronics + Machines + Control
Control techniques are able to command the power electronics and machines to regulate necessary variables such as:
o Voltage, current
o Active and reactive power
o Torque and speed
o …
In many applications, the control structure to accomplish this is generally as follows
Motivation from Physical Systems
One of the reasons this control structure has appeared is the time scales that exists in these systems:
o Current has a faster decay ratio (small inductance)
o Voltage/speed is slower (larger capacitance/inertia)
Some examples can be seen in electric machines and dc/dc converters
The inner loop quickly regulates the current while the outer loop controls the speed/torque
https://www.tesla.com/models?redirect=no
Assumptions for Inner/Outer Loop Control
Example: Buck Converter
Example: Buck Converter - Simplification
Example: Buck Converter – Inner Loop
Example: Buck Converter – Outer Loop
Example: Buck Converter – Combined Controller
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Next Topic
Three phase AC/DC and DC/AC converters
o abc to dq transformation
o Space vector PWM
o Phase Lock Loop (PLL)
o Controller Design Overview