Closed Loop Control System

PW O E R

RL T O & PR O ON C
Basler

T N C IO TE

®

CO NFERENCE

Closed Loop Control System

Contents
• • • • • • •

Application Diagram of a Typical System Examples What is gain? What is time constant PID Controller Why is PID Control complex?

Closed Loop Control System
- Applications -

– Thermostat for heating or air conditioning – Oven and refrigeration controls – Automotive speed controls – Aircraft autopilot systems – Electric power Generation Equipment

Contents
• • • • • • •

Application Diagram of a Typical System Examples What is gain? What is time constant PID Controller Why is PID Control complex?

Closed Loop Control System
- Diagram of a Typical System Controller AVR Required Voltage 6600V + Σ Feedback Plant Regulated Voltage 6600V Error 0V Amp Excitation Power Control

generator

Sets Required Value

Error Signal

Controlling Parameter

Regulated Output

6600V +

Σ -

PID

Controller AVR Output

Plant (Gen.)

6600V

Feedback

Contents
• • • • • • •

Application Diagram of a Typical System Examples What is gain? What is time constant PID Controller Why is PID Control complex?

Closed Loop Control System
- Examples System
Home Heating Oven Auto Speed Diesel Genset Diesel Genset

Plant
Gas Furnace Electric Element Engine Engine Alternator

Controller
Thermostat Thermostat Speed Controller Governor AVR

Measured
Temp Temp Drive Shaft Speed Shaft Speed Alternator Volts

Controlled
Gas Valve Switch Fuel injectors Fuel injectors Excitation Current

Closed Loop Control System
- Balanced Beam, Gain of 1 Input Applied Deflection = 1 cm Output Deflection = 1 cm

Balance point = 50% output Gain = input

1cm = 1cm

= 1

Contents
• • • • • • •

Application Diagram of a Typical System Examples What is gain? What is time constant PID Controller Why is PID Control complex?

Closed Loop Control System What is Gain?
- Operational Amplifier Model R2

Voltage Input

R1 Amplifier + Gain = Output Input = -R2 R1 Voltage Output

Closed Loop Control System
What is Gain?
- Operational Amplifier with a Gain of 10 R2 = 100k

Gain = -R2/R1 = -10
R1 = 10k Amplifier +

V out = -10*V in

V in

V out

Contents
• • • • • • •

Application Diagram of a Typical System Examples What is gain? What is time constant PID Controller Why is PID Control complex?

Closed Loop Control System What is Time Constant?
- Resistive Circuit no Time Constant Switch closes at t = 0 V in V out

I
+ V in

V out
0s t

Closed Loop Control System
What is Time Constant?
- R/C Circuit Network Time Constant Switch closes at t = 0 47k
V in

V out

+

V in

63 %

V out

50 µF
Time Constant, Tau= 2.35 s 0 1 2 3 4 5 6 7 9 8 Time in seconds

Time Constant : R*C = 47k*50µ = 2.35 s.

Capacitor Voltage in R/C Circuit

Contents
• • • • • • •

Application Diagram of a Typical System Examples What is gain? What is time constant PID Controller Why is PID Control complex?

Closed Loop Control System
- P.I.D. CONTROLLER -

Static precision Dynamic Precision Reaction of Proportional action Reaction of Integral action Reaction of Derivative action

Closed Loop Control System
P.I.D. CONTROLLER
- Proportional Controller Error Signal 0V 0.25 V

Required Value
5.0 V + -

Controller Σ
Error

P = 10

Output Driver

Measured Value 5.0 v 4.75 v

Proportional Response 2.5 V 0

Closed Loop Control System
P.I.D. CONTROLLER
- Integral Controller Controller
+ -

Required Value
5.0 V

Σ

Error

I = 1s

Output Driver

5.0 v

Measured Value 4.75 v

Error Signal 0V 0.25 V

Integral Response 0.25 V

0

1s

Closed Loop Control System
P.I.D. CONTROLLER
- Derivative Controller -

Controller
5.0 V + -

Σ

Error

D

Output Driver

5.0 v

Measured Value 4.75 v

Error Signal 0V 0.25 V

Derivative Response

0

Closed Loop Control System
P.I.D. CONTROLLER
- Add All Three P.I.D. -

Controller
P
Required Value + + + +

Σ

Error

-

I

Σ

Output Driver

genset

D

feedback

Closed Loop Control System
- P.I.D. Controller Example
-

Digital AVR Regulation criteria

-

- How each element of the P I D controller reacts on the system

Contents
• • • • • • •

Application Diagram of a Typical System Examples What is gain? What is time constant PID Controller Why is PID Control complex?

Closed Loop Control System
Regulation Criteria
- Step Response -

X
Measured Value

2%

Required Value

T

Closed Loop Control System
Regulation Criteria
- Load Impact -

2%

X

T

Closed Loop Control System
Proportional Control
- Step Response -

P.I.D. High Increase Low

Closed Loop Control System
Proportional Control
- Load Impact -

P.I.D.

High

Increase Low

Closed Loop Control System
Integral & Proportional Control
- Step Response -

P.I.D. Increase Increase No Int.

Closed Loop Control System
Integral & Proportional Control
- Load Impact -

P.I.D. Increase

Increase No Int.

Closed Loop Control System
Derivative & Proportional Control
- Step Response P.I.D. Increase Increase No Der.