Difference between revisions of "STM32MotorControl:SDK discontinuous PWM"

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1 Discontinuous PWM (DPWM) overview[edit]

DPWM feature allows the users to reduce the switching losses with an additional modulation technique according to their application.

This new approach is added to the current default 3-phase modulation.

It is deployed in all supported configurations:

  • 3-Shunt
  • 1-Shunt
  • ICS
  • with sensor or sensorless.

DPWM mode is available to the overall MCU families supported by STM32 MC SDK5.x

Target market:

  • Home appliances / High voltage applications: Air-conditioner fan, Air-conditioner compressor, Refrigerator compressor

2 DPWM / Two-phase description[edit]

By suppressing (0,0,0) state, two switches per cycle can be removed (here named with low side – usually high side):

STM32 MC DPWM p3 1.png
STM32 MC DPWM p3 2.png


Duty_A is enlarged of PWM_period – Duty_A to cover the whole PWM period.

In this case, as (1,1,1) state is enlarged of Duty_A:

  • Duty_B = Duty_B + Duty_A
  • Duty_C = Duty_C + Duty_A

3 Two-phase versus three-phase modulation[edit]

STM32 MC DPWM p4 1.png

CCR1,CCR2,CCR3 – applied PWM duty on U,V,W

STM32 MC DPWM p4 2.png

4 DPWM activation via STM32 MC Workbench setting[edit]

To enable the DPWM mode, select "Discontinuous PWM" parameter settings in “Firmware Drive Management / Additional Features” as shown below.

STM32 MC DPWM p5.png

5 DPWM firmware changes[edit]

When a project is generated with the DPWM, the activation of 2-phase modulation is effective at the startup stage, just after the calibration.

DPWM is enabled all-time in the 3-Shunt case, while it is not true in 1-Shunt.

In the 1-Shunt case, since the A and B stages are used for current sensing in boundary 2 or 3, it is not possible in this specific situation to work in 2-phase SVPWM. The workaround consists to automatically switch in 3-phase during these transition stages.

STM32 MC DPWM p6 1.png
STM32 MC DPWM p6 2.png


5.1 Example 1: two-phase versus three-phase modulation[edit]

Dynamically moving from 3-phase modulation to 2-phase modulation:

STM32 MC DPWM p8 1.jpg

Legend: Ch1: Current (Ia) Ch2: UL Ch3: VL Ch4: WL

5.2 Example 2: two-phase modulation: Startup in 3-Shunt mode[edit]

Here is a snapshot capture of the startup phase in DPWM mode.

STM32 MC DPWM p9.jpg



{{DISPLAYTITLE:STM32 MC SDK discontinuous PWM (new in V5.Y)}}

=== Discontinuous PWM (DPWM) overview ===

DPWM feature allows the users to reduce the switching losses with an additional modulation technique according to their application. 

This new approach is added to the current default 3-phase modulation.

It is deployed in all supported configurations:
* 3-Shunt
* 1-Shunt
* ICS
* with sensor or sensorless.

DPWM mode is available to the overall MCU families supported by STM32 MC SDK5.x

Target market:
* Home appliances / High voltage applications: Air-conditioner fan, Air-conditioner compressor, Refrigerator compressor

=== DPWM / Two-phase description ===

By suppressing (0,0,0) state, two switches per cycle can be removed (here named with low side – usually high side):
[[file:STM32_MC_DPWM_p3_1.png|left]]
[[file:STM32_MC_DPWM_p3_2.png|right]]<br clear=all>


Duty_A is enlarged of PWM_period – Duty_A to cover the whole PWM period.

In this case, as (1,1,1) state is enlarged of Duty_A:
* Duty_B = Duty_B + Duty_A
* Duty_C = Duty_C + Duty_A

=== Two-phase versus three-phase modulation ===

[[file:STM32_MC_DPWM_p4_1.png|center]]

CCR1,CCR2,CCR3 – applied PWM duty on U,V,W 

[[file:STM32_MC_DPWM_p4_2.png|center]]

=== DPWM activation via STM32 MC Workbench setting ===

To enable the DPWM mode, select "Discontinuous PWM" parameter settings in “Firmware Drive Management / Additional Features” as shown below.

[[file:STM32_MC_DPWM_p5.png|center|900px]]

=== DPWM firmware changes===

When a project is generated with the DPWM, the activation of 2-phase modulation is effective at the startup stage, just after the calibration.

DPWM is enabled all-time in the 3-Shunt case, while it is not true in 1-Shunt. 

In the 1-Shunt case, since the A and B stages are used for current sensing in boundary 2 or 3, it is not possible in this specific situation to work in 2-phase SVPWM. The workaround consists to automatically switch in 3-phase during these transition stages.
[[file:STM32_MC_DPWM_p6_1.png|left|450px]] 
[[file:STM32_MC_DPWM_p6_2.png|right|450px]]<br clear=all>


==== Example 1: two-phase versus three-phase modulation ====

Dynamically moving from 3-phase modulation to 2-phase modulation:
[[file:STM32_MC_DPWM_p8_1.jpg|center|700px]]

Legend:
Ch1: Current (Ia)
Ch2: UL
Ch3: VL
Ch4: WL

==== Example 2: two-phase modulation: Startup in 3-Shunt mode ====

Here is a snapshot capture of the startup phase in DPWM mode.
[[file:STM32_MC_DPWM_p9.jpg|center|700px]]
<noinclude>


[[Category:Motor Control]]
<noinclude>

{{PublicationRequestId|20062| 5/20/2021| JL LAGOUTTE}}<!--
Internal source: "DPWM_MCSDK5.pptx" V1.0
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==== Example 2: two-phase modulation: Startup in 3-Shunt mode ====
 
==== Example 2: two-phase modulation: Startup in 3-Shunt mode ====
   
Here a snapshot capture of startup phase in DPWM mode.
+
Here is a snapshot capture of the startup phase in DPWM mode.
 
[[file:STM32_MC_DPWM_p9.jpg|center|700px]]
 
[[file:STM32_MC_DPWM_p9.jpg|center|700px]]