3.22EjemploDRM007 Co..
3.22EjemploDRM007 Co..
3.22EjemploDRM007 Co..
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Software Design <strong>Co</strong>nsiderations<br />
Data Flow<br />
As an example, the algorithm for 50% of duty cycle on phase A and the<br />
two MOSFET commutation scheme is:<br />
• In the microcontroller CONFIG register the PWM write once<br />
register is configured as:<br />
– Center aligned PWM<br />
– Independent mode<br />
– TOPNEG enabled<br />
• The required duty cycle is directly loaded into the PVAL register<br />
for the TOP transistor.<br />
• The value loaded into the PVAL register for the BOT transistor is<br />
calculated as:<br />
#define DEADTIME 0x10<br />
PMOD = 0x100;<br />
PVAL1 = 0x80;<br />
PVAL2 = PVAL1 – DEADTIME;<br />
The output signal for one PWM cycle is shown in Figure 5-7.<br />
SOFTWARE<br />
DEADTIME<br />
INSERTION<br />
PWM1<br />
TOP MOSFET<br />
TOPNEG ENABLED<br />
PWM2<br />
BOTTOM MOSFET<br />
BOTNEG DISABLED<br />
1 CYCLE PWM<br />
Note: The PWMMC is configured with independent mode<br />
and center aligned operation<br />
Figure 5-7. Software Deadtime Insertion<br />
BLDC Motor <strong>Co</strong>ntrol Board for Industrial and Appliance Applications<br />
DRM007<br />
MOTOROLA Software Design <strong>Co</strong>nsiderations 85
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