In MPLAB® PowerSmart™ Digital Control Library Designer, release 0.9.14.676 labels of user extension function hooks changed, causing the compiler to fail when new control code is generated. This firmware release ensures compatibility with the latest version of this code generating tool.
When you download this version of the firmware, please also update your version of PowerSmart™ Digital Control Library Designer to version 0.9.14 or higher: MPLAB® PowerSmart™ Digital Control Library Designer v0.9.14
This is the initial release of the adaptive gain control code example demonstrating the enhancement of a basic digital voltage mode control implementation regulating the output voltage of a synchronous buck converter. Adaptive gain control is a special version of a feed forward implementation modulating the feedback loops gain at runtime based on the voltage across the main inductor. This implementation responds to changes of the input voltage as well as the output voltage, effectively stabilizing the open loop gain of the closed loop system across all operating conditions.
This example is based on the basic voltage mode code examples for the synchronous buck converter on the Digital Power Starter Kit 3. The firmware remains almost identical with the exception of the Adaptive Gain Control configuration in file app_power_config.c and the additional user-function v_loop_AGCFactorUpdate in the Assembler library extension file v_loop_agc.s.
This code example runs automatically after power has been applied to the development board. In this initial version the on-board LED of the dsPIC33CK Digital Power Plug-In Module is toggled with a interval period of 300 ms, when the controller is running at maximum speed of 100 MIPS. After startup, PWM generator #1 is generating a 500 kHz complementary waveform at the PWM1H/PWM1L outputs. The output voltage feedback is read through ADC input #13 and processed through the digital control loop in the respective interrupt service routine. The control loop also calls and extension algorithm, which reads the most recent input voltage through ADC input #12 and calculates the most recent voltage across the main inductor (VL). The ratio of the instantaneous VL versus the nominal VL at nominal operating conditions of VIN = 9V and VOUT = 3.3V is converted into a modulation factor k(AGC), which gets multiplied with the error delay line of the compensation filter. At the end of the control loop execution the result is written to the PWM duty cycle register, eventually regulating the output voltage to the nominal 3.3 V output voltage.
During operation the most recent values of input voltage, output voltage, output current and temperature are displayed on the on-board LCD. The screens can be switched by pressing the User button for more than 1 second.
Digital Power Starter Kit 3, Revision 3.0 (Part-No. 330017-3) Visit www.microchip.com/330017-3 for more information