Use about 3.3v, about 30Khz, and a PWM wave input with a duty ratio of about 0.7 to control the electromagnet current through the drive circuit and chopper circuit, but the current keeps changing, and the voltage output from the HO pin of the drive circuit is always Increase, is there a problem with the circuit principle, or the component parameters are wrong?
Maisie Posted on August 13, 2020
Some opinions: 1. The internal resistance of the electromagnet should be about tens of ohms. 2. The current limiting resistance of the driving MOS tube is generally several tens of ohms. 3. The high-side MOS tube drive circuit and the charge pump have no reasonable charging circuit during the working process of the electromagnet. The voltage on C5 will gradually decrease, causing the internal resistance of Q2 to gradually increase, and the current on the electromagnet will gradually decrease. cycle. 4. The low-side MOS tube drive circuit should be driven directly. 5. The negative pole of the 24V power supply should be grounded.
Lukas Posted on August 13, 2020
6. The 50mH inductor and the drive frequency of 30KHz are too large. 7. The driving mode should be low-side normally open and high-side PWM control current.
Ruben Posted on August 13, 2020
When the two MOSFETs are turned off, the two diodes D5 and D7 are used as freewheeling diodes to power the electromagnet. Is my understanding correct?
