IALB-Institute of Electrical Drives, Power Electronics and Components 5 Pulse Pattern Generation Figure 5. 1 shows the block diagram of gating of a four-quadrant-controller Two Point element Figure 5-1: Block diagram of a gate control The simplest approximation of a non-linear two-point-element is the comparator shown below Figure 5-2: Comparator with offset U2=0 applies to an ideal two-point-element triangular reference voltage two sampling information are available in one peio '4 AO The next two illustrations 5.3 and 5. 4 show the pulse-pattern-generation with tw different reference voltages. In opposite to saw-tooth shaped reference voltage, with
IALB – Institute of Electrical Drives, Power Electronics and Components - 15 - 5 Pulse Pattern Generation Figure 5.1 shows the block diagram of gating of a four-quadrant-controller. SET Two Point Element Figure 5-1: Block diagram of a gate control The simplest approximation of a non-linear two-point-element is the comparator shown below. Figure 5-2: Comparator with offset U2 = 0 applies to an ideal two-point-element. The next two illustrations 5.3 and 5.4 show the pulse-pattern-generation with two different reference voltages. In opposite to saw-tooth shaped reference voltage, with triangular reference voltage two sampling information are available in one period
AlLB-Institute of Electrical Drives, Power Electronics and Components 41 2To Figure 5-3: Pulse pattern generation with saw-tooth-shaped reference voltage p2T。 Figure 5-4: Pulse pattern generation with triangular-shaped reference voltage Period To holds t1+t2=To= constant
IALB – Institute of Electrical Drives, Power Electronics and Components - 16 - D D D D Figure 5-3: Pulse pattern generation with saw-tooth-shaped reference voltage set D D D D Figure 5-4: Pulse pattern generation with triangular-shaped reference voltage Period T0 holds: t1 + t2 = T0 = constant
IALB-Institute of Electrical Drives, Power Electronics and Components Moreover the frequency holds: Lset << f o 5.1 Two-Step Control of 4-Quadrant-Actuator In two-step control a pulse pattern is developed through the comparison between set and actual value. This control is only reliable with a energy store in the load circuit So for the inductive loads the load current is applied as controlled variable in two-point-control The following example shows the two-point current control. The set value iL set is iven as sinusoidal ii et sin(or) Figure 5.5 shows the block diagram of a two-point closed-loop control u U L Figure 5-5: PT1-element with two-point-controller The next illustration shows the current response and the pulse pattern caused by the control
IALB – Institute of Electrical Drives, Power Electronics and Components - 17 - Moreover the frequency holds: ( ) ( ) 10 20 1 0 0 0 ≈ K << = Lset Lset f U f T f U f 5.1 Two-Step Control of 4-Quadrant-Actuator In two-step control a pulse pattern is developed through the comparison between set and actual value. This control is only reliable with a energy store in the load circuit. So for the inductive loads the load current is applied as controlled variable in two-point-control. The following example shows the two-point current control. The set value iL set is given as sinusoidal. i ( )t Lset = sin ω Figure 5.5 shows the block diagram of a two-point closed-loop control: set s Two-point-Element with hysteresis Figure 5-5: PT1-element with two-point-controller The next illustration shows the current response and the pulse pattern caused by the control
IALB-Institute of Electrical Drives, Power Electronics and Components IL set te Figure 5-6: Current response and pulse pattern Differential equation of R-L-load(u, =+UD) Ri=u L di V Standardization of Up, ILo +==出1 L The switching time is as following VI +E In I v,-Lsoll -E +e T1N1- =In
IALB – Institute of Electrical Drives, Power Electronics and Components - 18 - set set D set D Figure 5-6: Current response and pulse pattern Differential equation of R-L-load ( ) L U D u = ± : { 1 0 0 0 D L0 1 1 Standardization of U , I V U u RI U I i dt I i d R L R u i dt di R L Ri u dt di L D L V L D L L Lset Lset T L L L L L L + = = ± ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ↓ + = + = 123 The switching time is as following: t T V i I V i I t T V i I V i I Lsoll L Lsoll L Lsoll L Lsoll L 1 1 1 0 1 0 2 1 1 0 1 0 = − + − − = + + − − ln ln ε ε ε ε
B-Institute of Electrical Drives, Power Electronics and Components The average load voltage is as below: LU l1+l2 V19 +E‖ Up 4+L2 -m+E|z+2 LO The following illustration presents the response characteristic of two-point-control real V Figure 5-7: Response characteristic The mean gain vm is calculated as below The frequency holds
IALB – Institute of Electrical Drives, Power Electronics and Components - 19 - The average load voltage is as below: L UD t t t t u 1 2 1 2 + − = ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + − ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − − ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − − ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + − ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − + = + − = ε ε ε ε ε ε ε ε 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 1 2 1 2 ln ln L Lset L Lset L Lset L Lset L Lset L Lset L Lset L Lset D L I i V I i V I i V I i V I i V I i V I i V I i V t t t t U u The following illustration presents the response characteristic of two-point-control. S set Figure 5-7: Response characteristic The mean gain Vm is calculated as below: V V V m = − ≈ 1 1 1 1 ε The frequency holds: