DTI's electronic driver has been designed to provide an economical user-control interface for use with all DTI piezoelectric motors. Each driver is supplied pre-programmed and matched for the associated motor type and is software configurable to provide optimization of drive signals and integrated controls.
The electronic driver in combination with a piezo motor will enable precision motion and flow controls to be routinely established. Control is achieved through a microcontroller based 12 VDC digital system, which also allows for user generated inputs for motion control.
The driver assembly is comprised of four main sections as shown in the PCB block diagram.
Power Supply (PS), accepts a 12 VDC input through a DC power jack with a 2.0 mm center positive pin. The 12V is filtered then regulated to 5.0 VDC and filtered again to provide board operational voltage.
The Direction Controls (DCt), provides manual push button directional control signal inputs to the microcontroller (MC) for continuous operation. These are active TTL low inputs to the microcontroller. An external control signal interface has been designed to facilitate user generated signal or pulse train controls for stepping mode (PWM) operation. Future development will provide for TTL active high inputs to the microcontroller.
The Microcontroller (MC), provides software control, based upon directional control inputs. When directional control signals are received, the microcontroller generates enable and phase control output signals proportional to the control signal and current feedback to the Driver (DR). In stepper pulse mode (PWM) of operation, drive enable signal pulse width determines the amplitude of motion. A current feedback input is used by software to determine motor resonance frequency and will generate a corresponding excitation phase signal for optimal operation. A temperature sensor input can be used for operational control in applications where a temperature sensor is required.
Future implementation of an external encoder interface will provide for precision linear or rotational closed loop control. Microcontroller ports are included for device programming and a serial communications interface port for future use.
The Driver element is comprised of two gate driver ICs, FETs (to provide drive current), and step up voltage transformers. The Driver section uses the supply 12 VDC. The enabled gate driver amplifies the 5V TTL phase signals to a 12V gate drive signal that switches on the FETs. When the FETs are active, the transformer steps up the signal voltage to an appropriate level for the associated piezomotor to operate. Channel drive current is also detected within the Driver element, where it is amplified then integrated to provide an analog signal proportional to the channel drive current. This current sense feedback is use for optimal motor operational control and performance.