Gradient amplifier with compensation for dead time and forward voltage

US10024937B2 · kind B2 · utility

Assignee

• KONINIKLIJKE PHILIPS N.V. · NL

Inventors

• Thomas Scheel · Stolberg, DE
• Christian Hattrup · Würselen, DE

Key dates

• Filing date: Sep 20, 2012
• Grant date: Jul 17, 2018
• Expiry date: Nov 12, 2035

Classification

• Technology area (CPC H): Electricity
• CPC primary: H03F3/2173
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Non-linearities of a gradient amplifier (1) for powering a gradient coil (16) are caused by the finite dead time of the amplifier and/or by a forward voltage drop. The gradient amplifier (1) includes a controllable full bridge (8) and an output filter (9). The full bridge (8) is controlled to provide a desired coil current (ic), including receiving a desired duty cycle (aeff) of the gradient amplifier (1), measuring an input current (ifilt) and an output voltage (ucfilt) of the output filter (9), evaluating an modulator duty cycle (amod), and providing the modulator duty cycle (amod) for controlling the full bridge (8). The gradient amplifier (1) powers a gradient coil (16) including at least two half bridges (10), each having at least two power switches (11) connected in series. An output filter (9) connected to a tapped center points of the half bridges (10) between two the power switches (11). A controller provides a desired duty cycle (aeff) of the gradient amplifier (1), a compensation block (5) for providing an modulator duty cycle (amod). A modulator (6) controls the power switches (11) according to the modulator duty cycle (amod).