Synchronous rectification method for reducing power dissipation in motor drivers in PWM mode
US5309078A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 11, 1991 |
| Grant date | May 3, 1994 |
| Priority date | — |
| Expiry date | Jul 11, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M7/53875
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Pulse Width Modulation (PWM) techniques, often used to reduce the power dissipation in polyphase motors, chop the current in the coils of the motor at their peak current levels, to achieve maximum torque, to allow rapid accelerations, and to reduce the power dissipated in the chip to a level proportional to the duty cycle. During the time the current is switched off, the current which has been established in the coils of the motor is allowed to be dissipated. Accordingly, when the switching transistors of the active coils are turned off during PWM mode chopping, a non-rectifying ground return path is provided for flyback energy in the active driving coil. This non-rectifying ground return path is provided by switching transistors in parallel with flyback diodes, operated in a form of synchronous rectification. This gives an alternate current path for the coil current to reduce the voltage drop across the diodes, and thereby reduce the power dissipation and heat in the chip.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.