Difference between revisions of "STM32MotorControl:SDK discontinuous PWM"
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Contents
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):
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]
CCR1,CCR2,CCR3 – applied PWM duty on U,V,W
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.
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.
5.1 Example 1: two-phase versus three-phase modulation[edit]
Dynamically moving from 3-phase modulation to 2-phase modulation:
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.
{{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 ==== |
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| − | 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]] |
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