gonespa
Member level 1
Hi,
I am trying to make a custom BLDC motor controller work. It uses the six-step conmutation schema as well as hall sensor-based feedback.
It uses a IR2110 gate driver (one for each phase). Since it does not spin my motor (1 pole per step = just 6 poles) I started to measure the waveforms at the MOSFETS.
I attached the waveform I cannot understand, it corresponds to the voltage at the SOURCE of the low-side MOSFET of one of the phases (RED), the voltage at the DRAIN of the same mosfet (GREEN) as well as the mathematical Red - Green calculated waveform (PINK) so, pink its drain to source voltage. The Powersource connected to the circuit is providing 15,5 Volts.
The circuit is not connected to the motor itself (it is not powering the motor itself) but it is connected to the hall sensors. In order to test I spun it manually so that the controller is switching between the six steps.
In the attached waveform you can see 4 of the 6 steps. The center part corresponds to the two steps in which that particular phase is being PWM'd (Due to the resolution it looks weird, but there is a PWM of about 90 or 85% to the low MOSFET, since the controller is configured to do synchronous rectification). That one is ok. The problem I have is the other two phases. They correspond to a step in which both high and low MOSFET are off. As you can see there is a (substantial) time in which, apparently, the low MOSFET is conducting, at least partially, even if the MOSFETs are commanded to stay closed.
I can´t understand if this is a normal situation in a BLDC motor controller when a phase is floating, or if it is indicating there is a problem somewhere.
The IR2110 connections schematic is this one:
Can someone lay some light into this?. This is the waveforms:
I am trying to make a custom BLDC motor controller work. It uses the six-step conmutation schema as well as hall sensor-based feedback.
It uses a IR2110 gate driver (one for each phase). Since it does not spin my motor (1 pole per step = just 6 poles) I started to measure the waveforms at the MOSFETS.
I attached the waveform I cannot understand, it corresponds to the voltage at the SOURCE of the low-side MOSFET of one of the phases (RED), the voltage at the DRAIN of the same mosfet (GREEN) as well as the mathematical Red - Green calculated waveform (PINK) so, pink its drain to source voltage. The Powersource connected to the circuit is providing 15,5 Volts.
The circuit is not connected to the motor itself (it is not powering the motor itself) but it is connected to the hall sensors. In order to test I spun it manually so that the controller is switching between the six steps.
In the attached waveform you can see 4 of the 6 steps. The center part corresponds to the two steps in which that particular phase is being PWM'd (Due to the resolution it looks weird, but there is a PWM of about 90 or 85% to the low MOSFET, since the controller is configured to do synchronous rectification). That one is ok. The problem I have is the other two phases. They correspond to a step in which both high and low MOSFET are off. As you can see there is a (substantial) time in which, apparently, the low MOSFET is conducting, at least partially, even if the MOSFETs are commanded to stay closed.
I can´t understand if this is a normal situation in a BLDC motor controller when a phase is floating, or if it is indicating there is a problem somewhere.
The IR2110 connections schematic is this one:
Can someone lay some light into this?. This is the waveforms:
