US Patent 7520308 Drive unit for controlling reciprocating electromagnets

A drive unit for use with a vibration welder having first and second electromagnets, each having first and second terminals, and being operable to reciprocate a vibration platen, includes phase U, V, and W drive circuitry and control circuitry. The phase U drive circuitry is coupled to the first terminal of the first electromagnet. The phase V drive circuitry is coupled to the first terminal of the second electromagnet. The phase W drive circuitry is coupled to the second terminals of the first and second electromagnets. The control circuitry is operable to control the phase U, V, and W drive circuitry to generate a first drive signal for energizing the first electromagnet and a second drive signal for energizing the second electromagnet.