Refine
Document Type
- Conference Proceeding (9)
- Contribution to a Periodical (1)
- Report (1)
Is part of the Bibliography
- no (11)
Keywords
- Elektrische Antriebssysteme (5)
- Leistungselektronik (5)
- bandwidth (3)
- Automatisierungstechnik (2)
- FPGA (2)
- GaN power semiconductors (2)
- servo drives (2)
- Automation and Motion (1)
- Electrical Drives (1)
- Electrical drives (1)
Institute
Position measuring devices with sinusoidal measuring signals are widely used in position-controlled servo drives in industrial automation, e.g., for machine tools or semiconductor production machines. Usually, the feedback signal for the speed or velocity controller is calculated from the measured position. Therefore, position measuring errors affect these control loops. This study presents an analytic error model that considers non-ideal sinusoidal measuring signals with basic deviations (amplitude differences, offset errors, and phase shift) as well as signal harmonics. The model was used to systematically investigate the influence of signal quality and the number of signal periods from position measuring devices on speed ripple, across a wide range of speeds. A test stand with a high-resolution reference angle measuring device was used to confirm the results.
A hybrid current and acceleration control is presented and shown to improve the load disturbance behavior of servo drives significantly without additional sensor effort. The feedback signal of the acceleration control loop is calculated from the position data of the motor encoder. Hence, position measuring errors influence this control loop and lead to speed ripple. Therefore, the presented design of the acceleration control loop considers both load sensitivity and position measuring errors.
Increased productivity in industrial processes can be achieved by dynamic and accurate positioning of servo drives. Therefore, improvement of servo drive dynamics using latest technologies in the key components such as inverter, control system and position measuring device are investigated. Using Gallium Nitride (GaN) or Silicon Carbide (SiC) semiconductors for motor inverters enables energy efficient operation up to pulse width modulation (PWM) frequencies of 500 kHz. This allows motor filters with small component sizes. As a result, high motor efficiency, low torque ripple, high control bandwidth and almost ideal sinusoidal output voltages are achieved. Experiments on a 200 kHz Gallium Nitride inverter with sine wave motor filter show a current control loop bandwidth of 3.2 kHz and almost ideal sinusoidal phase voltages. The achieved bandwidths of the speed and position control loops are 318 Hz and 106 Hz, respectively.
A calculation method for a robust servo controller design depending on the sampling time and the processing dead time was developed for mechanically stiff drives. With a test stand for high dynamic and high positioning accuracy, the theoretical calculations for the high bandwidth improvements are verified. The test stand includes a voice coil motor and a power electronic with Gallium Nitride (GaN) power semiconductors for switching frequencies of more than 100kHz.
A discrete-time design method for a robust current controller of a servo drive has been developed. It takes the sampling time, the processing dead time and the dynamic behavior of the A/D converter into account. The theoretical calculations are verified using a test stand for high dynamics. The test stand includes a voice coil motor and power electronics with Gallium Nitride (GaN) power semiconductors for switching frequencies of more than 100 kHz. The bandwidth of the current control loop can be improved from typically 1 kHz to 1.5 kHz with insulated-gate bipolar transistor (IGBT) power semiconductors in state-of-the-art motion control systems to 10 kHz and more.
The dynamic behavior and position stability of servo drives are influenced by many parameters. One major influencing parameter is the pulse width modulation (PWM) frequency. With inverters based on wide bandgap semiconductors, the PWM frequency can be increased. This enables a substantial increase in the current control bandwidth. The paper focuses on the influence of the PWM frequency on the dynamics of control loops and position stability, which are derived from theoretical correlations. The theory is verified using a test bench for high dynamic and position stability. The test bench is equipped with a voice coil motor and power electronic with gallium nitride (GaN) power semiconductors for switching frequencies of 100kHz and over. The achieved position stability, measured with a laser-based comparator at the tool center point, is lower than "+-1nm" with a standard deviation of "0.16nm" at a PWM frequency of "f_PWM=100kHz".