ANALYSIS AND COMPENSATOR DESIGN OF MAGNET CORRECTION POWER SUPPLY

Yong-Seng Wong# , Kuo-Bin Liu, Jhao-Cyuan Huang NSRRC, Hsinchu 30076, Taiwan

.Abstract

This paper presents a new method for the analysis and design of compensators for magnet correction (MC) power supply. The system has to need controllers to satisfy required gain and phase margin specifications and compensator by adding to circuit controller and switch. The gain-phase margin tester method can transform of the controller and find solutions on the figure. According to circuit frequency response and transfer function by theory analysis and simulation design new method compensators to improved anti-disturbance and stability of the system.

INTRODUCTION The MCOR 30 series is a multi-channel corrector magnet driver system, capable of providing precision bi-polar output currents with minimal zero-crossover distortion. The light source must keep a high precise current at operation steady state. Therefore, a number of correction magnets are required for the APS machine to correct the beam [1]. However, MCOR 30 has been limited for the frequency to be stability when valid the machine output current load. Design a compensator to observe the circuit gain margin and phase margin. MCOR 30 frequency setting at 24.5kHz and the cross frequency is 5kHz. The experiments and plots presented here are all done in Simplis software, and experiments result measurements are obtains from the various output current data.

CORRECTION POWER SUPPLY OPERATION THEORY

Figure1 has show the machine control block. The power modules are controlled using -10V to +10V analog command signals sent to different amplifier, the signal will be compare feedback signal from output current. Therefore, error amplifier can provided a PWM signal to control the switch and produce a high precision bi-polar current source. Bi-polar correction power supply equivalent circuit construction as shown Figure 2. The correction power supply regulates the DC output current by controlling the pulse width of an half bridge power N-MOSFET array. For positive output current, Q1 and Q4 switch are turn on and input energy will be charge energy and linear increase current for output load. When Q1 turn off the output current decay thought the Q4 and d3 turn on. For negative current is same to the mode [2].

Use to 4-terminal Kelvin connection Magnet shunt resistors will had been a high precision output current. These are 10 milliohm shunts have an absolute tolerance

of 0.1%, it can make sure output current noise under 100uArms at the high load conditions (30A).

Figure 1: Correction power supply block diagram.

Figure 2: Correction power supply equivalent circuit.

DESIGN PROCEDURE FOR COMPENSATOR

All of the switch power supply must be design a compensator in the frequency domain generally is to satisfy specifications on steady-state accuracy and phase margin. Measurement of the system stability with frequency response is normally and easily method. The frequency response closed loop control function block as shown figure3. The feedback voltage through the output voltage divided resistance into the adder signal. Both of the feedback signal and refer voltage signal to sum, it will be compared a pulse width modulation (PWM) signal into power switch transfer with error amplifier and compensator. Closed loop control function gain margin and phase margin can be written as (1),(2). Among, ω is the cross frequency with correction power supply[3]~[5].

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THPO014 Proceedings of IPAC2011, San Sebastián, Spain

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07 Accelerator Technology

T11 Power Supplies