> Chopping frequency generally refers to DC chopping DC chopping is to convert a fixed DC voltage into a variable DC voltage, also known as DC/DC conversion.
There are two working modes of the chopper, one is the pulse width modulation mode, Ts (period) remains unchanged, and the Ton is changed (generally, Ton is the time for each switch to be turned on), the other is the frequency modulation mode, the Ton remains unchanged, Change Ts (prone to interference).
**> 1. The frequency of the general buck-boost chopper circuit is 2kHz~100kHz. A higher chopping frequency is beneficial to reduce the size of the inductor and capacitor, but it will increase the conversion loss of the switching tube. Therefore, the general high-power converter chopping The wave frequency is lower, mostly 2-8kHz above tens of kilowatts. The chopping frequency needs to be greater than 2 times the working frequency
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> The understanding of the chopping frequency [combined with the stepping motor]: the pulse frequency of the stepping motor determines the speed of the stepping motor, but since the winding is an inductive coil, the power supply voltage When the speed is low, the average current flowing through the winding of the stepping motor will be very large. In order to limit the current, a chopper circuit is adopted, that is, when the current rises to a certain value, the power supply of the winding is disconnected, and the current will drop. , and then turn on when it drops to a certain value. During this winding energization period, multiple turns on and off are the frequency of the chopper. It must be much higher than the pulse frequency sent to the driver by the single-chip microcomputer, which is also mentioned above. : ""The chopping frequency needs to be greater than 2 times the operating frequency""
Additional:
A little understanding about lvr:
Low voltage reset detection [LVR]: When the VDD voltage is lower than the selected LVR voltage for a certain period of time (120us~480us), the system will generate a low voltage reset action, and the IO is at the initial stage Input state, OSC base oscillates. When the system enters the power saving mode, the LVR is invalid at this time, and there is no power consumption problem.
When the LVR is reset, when VDD>0.9V, the value in ram remains unchanged, and when the power supply voltage is higher than the LVR voltage again, the system restarts without reconfiguring the parameters saved in ram, but if VDD<0.9V, the system The value in ram is not guaranteed.MCU deadlock reset problem: the capacitance of the reset terminal of the microcontroller should not be too large.