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DC motor servo drive Power Supply Design

Print View , by: iSee ,Total views: 47 ,Word Count: 1351 ,Date: Wed, 26 Aug 2009 Time: 4:02 PM

The design for DC-DC converter as the core, to achieve 220V electricity to +60 V/20A power conversion. Power supply design used in power factor correction technology to improve the active power; in particular power supply design of the computer control interface, and synchronous servo system work, and realized the power sequencing to ensure that the relatively low voltage of +60 V power output lag. Multiple filtering measures and twisted pair output mode, effectively reduce the output voltage ripple, improving power output quality; have the best self-protection and surveillance detection capabilities, improve power supply security and reliability.

Power Design


220V AC voltage by the rectified and filtered DC voltage to be 320V or so, add to the power module input. A single DC-DC modules, the maximum output voltage of typically +48 V, to get +60 V DC output voltage, the module must be used in series approach has been. Design uses two PH600S280-28DC-DC module (raised to +30 V output), through the series to be +60 V output voltage, as shown in Figure 1.

DC motor servo drive Power Supply Design

Figure 1 module in-line mode

Fast recovery diode D1, D2 for the series in the way of protection devices, demand D1, D2 reverse voltage is greater than twice the power supply rated output voltage and current is greater than twice the power supply rated output current, voltage drop is the wizard should be small. Because it is using two power supply modules in series constitute the power system, in a limited package, it will be difficult to complete the design, some modules in series program uses two packages to complete the design, namely the design of two separate 30V power supply, further External series constitutes a +60 V power supply system. This design through the rational allocation of space in the upper and lower lid of each power supply to install a DC-DC modules, thermal metal shell as a means of compact design and installation of technology to the entire power system is packaged in a smaller space so that the whole power supply size, weight greatly reduced cross-sectional area of only 6 × 9 inch 2, to achieve a small volume of high-power integrated power system design.

Power factor correction measures

Bridge rectifier switching power supply, large capacitor filter circuit so that the overall performance of the capacitive load, so that 220V AC input current and voltage phase angle difference, resulting in low power factor, active power down and produce high-order harmonic pollution in power, it must be taken to Power Factor Correction (PFC) measures. Based on cost control, and application convenience of the circuit size and other factors to consider, we have adopted a passive power factor correction measures. Passive PFC simple structure, the overall load characteristics for the power performance of large capacitors in the filter parameter before the series with a suitable power inductors, where the ring used 10mH/8A core inductor. Force balance the overall load characteristics of power supply to ensure power factor of not less than 0.8. Passive PFC inductor and other passive components used, reliable low-cost, and no need to modify the original electrical design, is the commonly used method of PFC.

Design features and key technologies

Computer control and monitoring interfaces

(2)+60V/20A、,。 This power supply and servo system working the way synchronization, with energy-saving, low heat, control, flexibility, and so a series of advantages. In a series of power system equipment, power supply, +60 V/20A maximum power consumption, but the minimum heat, temperature minimum, fully proved that the power used in the design advantages of computer-controlled interface.

DC motor servo drive Power Supply Design

Figure 2 Computer Control interface

Internal power supply provides +60 V for the detection of the computer interface, the way to switch the amount of real-time detection, shown in Figure 3. +60 V input voltage as a detection optocoupler drive optocoupler output as a test port and the computer digital I / O port connections. Under normal circumstances test port is low, once the +60 V output disappear or greatly reduced, optocoupler's output level from low to high transition occurs provided to the microcomputer I / O port.

DC motor servo drive Power Supply Design

Figure 3 Detection of Interface Computer

Power Sequencing

DC motor control system, power-on timing problems that exist, under normal circumstances drive voltage power faster, while the control circuit voltage level after power control of the establishment of take some time. Without such a power-on sequence control and power in the system the moment, high speed than the low-voltage power to control the establishment level is lagging behind, resulting in the instantaneous power control servo system, a short time out of control motor rotation, especially in the bipolar control mode. The traditional solution through the creation of high and low voltage power switch to manually control the timing, or in the control system designed to power up sequencing control circuit, and this will inevitably increase the complexity of the circuit, resulting in the reliability of the circuit at the same time reducing costs. In the motor drive power supply to solve this problem, measures simple and effective, the working principle of: CNT-side as a module enable control terminal, you can control the module's working state, as the output voltage control switch. Commonly used to control the CNT side optocoupler state. Just to increase one optocouplers, power-on timing problems can be solved. Figure 2 shows, the optocoupler input Duanyou motor control circuit operating voltage +5 V control, so that +60 V power output inevitably lag behind the low-voltage +5 V, realized the power sequence control function, a fundamental solution to the aforementioned problems.

Power protection and electromagnetic compatibility measures

Within the module overcurrent, overvoltage, thermal protection, using an external potentiometer at rated output voltage within ± 10% adjustment. In the power system design, we have rectified the 220V high voltage input, +60 V output and other key parts used TVS transient voltage surge absorber and surge protection shocks suppression measures in order to bypass absorption of ways to protect the power supply systems, while reducing electromagnetic interference, to improve power system reliability and service life.

We experiment measured the +60 V output voltage ripple in the 800mV ~ 1000mV, obviously too large. Power system by adjusting the output terminal and the use of polyester capacitor filter, the alignment of power within the use of twisted-pair mode of filtering measures so that ultimately makes the +60 V power supply system's output ripple control 200mV ~ 400mV, met +60 V/20A power supply ripple voltage ≤ 600mV of the use requirements.


Dedicated servo DC motor drive power, has not just the traditional sense of the switching power supply, which directly involved in the control of DC motor, its unique computer interface, control and power sequencing is particularly suitable for DC motor drive system, a relatively traditional general-purpose power supply has a clear technological advantage, the technical characteristics of its multi-line motor-driven power system development. The dedicated power has been officially delivered successfully used in celestial navigation equipment, a certain model, functional and practical, easy to control, work stable and reliable.

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