Govindaraj: 2014

Monday, October 13, 2014

Simulation of Closed Loop Speed Control of BLDC Motor - MATLAB/Simulink

The outputs of the “Permanent Magnet Synchronous Machine” module include:

1. stator Phase currents i_a, i_b and i_c.

2. The phase back-EMF of the windings e_a, e_b and e_c.

3. The output signals of Hall position sensors HA, HB and HC.

4. The rotor speed n(rad/sec).

5. The rotor position angle theta(rad).

6. The electromagnetic torque Te(N*m).

The parameters of the motor mainly include:

1. Stator resistance R(Ohm), inductance Ls(H).

2. Flux linkage established by magnet (V.s)

3. Voltage constant( V_peak L-L/krpm)

4. Toque constant (N.m/A_peak)

5. the back-EMF flat area(degree).

6. moment of inertia J (kg m2),Viscous damping F(N.m.s),Number of pairs of poles P, Static friction Tf(N.m)

Ideal waveform of BLDC motor

SPEED CONTROLLER

The speed controller is based on PI controller. The output of the regulator is torque set point applied to current controller block.

Speed cutoff frequency

The speed measurement first-order low-pass filter cutoff frequency (Hz). This parameter is used in speed regulation mode only.

Speed controller sampling time

The speed controller sampling time (s). The sampling time must be a multiple of the simulation time step.

Speed Ramps — Acceleration

The maximum change of speed allowed during motor acceleration (rpm/s). An excessively large positive value can cause DC bus under-voltage. This parameter is used in speed regulation mode only.

Speed Ramps — Deceleration

The maximum change of speed allowed during motor deceleration (rpm/s). An excessively large negative value can cause DC bus overvoltage. This parameter is used in speed regulation mode only.

PI Regulator — Proportional Gain

The speed controller proportional gain. This parameter is used in speed regulation mode only.

PI Regulator — Integral Gain

The speed controller integral gain. This parameter is used in speed regulation mode only.

Torque output limits — Negative

The maximum negative demanded torque applied to the motor by the current controller (N.m).

Torque output limits — Positive

The maximum positive demanded torque applied to the motor by the current controller (N.m).

BRAKING CHOPPER SECTION

RESULT ANALYSIS

FOR MOTOR SPEED AT +300RPM

Phase Current, BEMF, Speed, Torque

Three Phase BEMF

DC Bus

Hall Signal

Phase Current

Speed, Torque

FOR MOTOR SPEED AT -300RPM

Phase Current, BEMF, Speed, Torque

All Phase BEMF

DC Bus

Hall Signal

Phase Current

Speed and Torque

FOR MOTOR SPEED IN BOTH FORWARD AND REVERSE (+300 rpm & -300 rpm)

Phase current, BEMF, Speed, Torque

All Phase BEMF

DC Bus

Hall Signal

Stator Phase Current

Speed and Torque

Sunday, June 22, 2014

Comparision of Maximum Power Point Tracking Algorthim for Solar PV Application

MPPT ALGORTHIM

The purpose of this work is to obtain such an experimental comparison and to suggest which MPPT control algorithm is the most effective on the basis of MPPT efficiency, which is defined as:

where Pactual is the actual (measured) power produced by the PVarray under the control of the MPPT, and Pmax is the true maximum power the array could produce under a given temperature and irradiance. In this work, only MPPT algorithms that could presently be implemented in a low-cost MPPT were considered.

Fuzzy logic and DSP-based systems were therefore excluded, and the following MPPT algorithms were chosen for further investigation:

1. PERTURB AND OBSERVE (P&O)

2. INCREMENTAL CONDUCTANCE (INC)

3. PARASITIC CAPACITANCE (PC)

4. CONSTANT VOLTAGE (CV)

SIMULATION MATLAB