MATLAB Co-Simulation Tools for Power Supply Systems Design

Abstract

ion level. Circuit simulation software as Powersim PSIM and Orcad Pspice are the most common choice for circuit modelling. In (Basso, 2008), the design and simulation of switchmode power supplies is deeply analyzed and simulation tips in several environments are proposed. ASIC simulation and verification tools as Xilinx ISE/Modelsim or Aldec ActiveHDL are available to implement the digital controller by the VHDL or VERILOG source code. Since the interaction between subsystems is the most common source of faults, testing separately analog and digital subsystems by the means of different verification tools is a severe mistake. Matlab is a powerful simulation environment for mixed-mode systems modelling and simulation, providing several tools for system co-simulation (Pop, 2010; Kaichun et al., 2010). The Matlab suite offers co-simulation tools for PSIM, Modelsim and Active-HDL simulation environments. Ideally, modelling the power converter by a circuit implementation in PSIM environment and the digital controller by the VHDL code in Xilinx ISE or Active-HDL environment allows the designer to test the composite system in Matlab environment using co-simulation procedures. Unfortunately, the use of several co-simulation tools in the same Simulink model heavily reduces the processing speed. As an example, in this chapter the Simulink model of a multiphase dc-dc converter for VRMs applications is described. The control system is described by VHDL language and the controller model is implemented in Active-HDL environment. For the highest processing speed, an alternative modelling technique for the power section is proposed by the means of elementary library blocks, avoiding PSIM co-simulation and not affecting the accuracy of behavioural simulations. As shown by simulation results, the high accuracy relies in the opportunity to match the system behaviour both within the switching event and during long-time events such as load transients and startup. The great potential of the co-simulation procedure for mixed-mode systems is highlighted by the comparison between simulation and experimental results. Fig. 1. Power supply system architecture. 2. Multiphase dc-dc converters for VRM applications The evolution in microprocessor technology poses new challenges for power supply design. The end of 2009 marked the birth of 32nm technology for semiconductor devices, and 22nm is expected to be reached in the 2011-2012 timeframe. The next generation of computer microprocessors will operate at significantly lower voltages and higher currents than today’s generation in order to decrease the power consumption and increase the processing speed. Within several years, Intel cores are expected to operate on a 0.8V supply voltage. Highquality power is delivered to the microprocessor by a point-of-load (POL) converter, also known as voltage regulator module (VRM), which is located on the motherboard next to the load. Embedded POL converters are designed to supply a tight regulated output voltage in the 0.8 – 1.2V range. Due to integration advances and increasing clock frequencies, high current