Overview This design uses a DC-DC converter as its core to convert 220V AC mains power to +60V/20A. The power supply design employs power factor correction technology to improve active power. In particular, the design includes a microcomputer control interface to work synchronously with the servo system and implements power-on timing control, ensuring that the +60V voltage lags behind the lower voltage output. Multiple filtering measures and a twisted-pair output method effectively reduce output voltage ripple and improve power output quality. It also features comprehensive self-protection and monitoring functions, enhancing the safety and reliability of the power supply. Power Supply Design System Structure: The 220V AC voltage is rectified and filtered to obtain approximately 320V DC voltage, which is applied to the input of the power module. The maximum output voltage of a single DC-DC module is typically +48V; to obtain a +60V DC output voltage, the modules must be connected in series. The design employs two PH600S280-28 DC-DC modules (adjusted to +30V output), connected in series to obtain a +60V output voltage, as shown in Figure 1. Fast recovery diodes D1 and D2 are used as protection devices in this series configuration. D1 and D2 must have a reverse withstand voltage greater than twice the rated output voltage of the power supply, a current rating greater than twice the rated output current, and a forward voltage drop as low as possible. Since the power system is constructed using two power modules connected in series, completing the design within a limited package presents certain challenges. Some module series solutions use two separate packages, i.e., designing two independent 30V power supplies and then connecting them externally to form a +60V power system. This design, through efficient space allocation, installs one DC-DC module in each of the upper and lower covers of the power supply, using a metal casing for heat dissipation. The compact design and installation techniques encapsulate the entire power system within a small space, significantly reducing the overall size and weight of the power supply. With a cross-sectional area of ​​only 6×9 inches², this achieves a small-volume, high-power integrated power system design. Power Factor Correction Measures The bridge rectifier and large capacitor filter circuit of the switching power supply cause the overall load to behave capacitively, resulting in a phase difference between the current and voltage of the 220V AC input. This leads to a low power factor, reduced active power, and high-order harmonic pollution of the power grid. Therefore, power factor correction (PFC) measures are necessary. Considering cost control, circuit size, and ease of application, we adopt a passive power factor correction method. Passive PFC has a simple structure. Based on the overall load characteristics of the power supply, a power inductor with suitable parameters is connected in series before the large filter capacitor; here, a 10mH/8A toroidal core inductor is used. This forces a balance of the overall load characteristics of the power supply, ensuring a power factor of no less than 0.8. Passive PFC uses passive components such as inductors, is reliable and inexpensive, and requires no modification to the original electrical design, making it a commonly used PFC method. Design Features and Key Technologies Microcomputer Control and Detection Interface: The microcomputer control function ensures that the +60V/20A power supply only starts outputting when the computer sends an enable signal and the servo system is operating; otherwise, the power supply has no output. This method of synchronous operation between the power supply and the servo system offers advantages such as power saving, low heat generation, and flexible control. Among a series of power supplies in a certain equipment power system, the +60V/20A power supply has the highest power consumption but the lowest heat generation and temperature rise, fully demonstrating the superiority of using a computer control interface in the power supply design. The power supply also provides a microcomputer detection interface for +60V for real-time detection in a switching mode, as shown in Figure 3. The +60V voltage serves as the input drive for the detection optocoupler, and the optocoupler output is connected to the microcomputer digital I/O port as the detection port. Under normal circumstances, the detection port is at a low level. Once the +60V output disappears or drops significantly, the optocoupler output level will jump from low to high, providing power to the microcomputer I/O port. Power-On Sequence Control Power-on sequence issues exist in DC motor control systems. Generally, the drive voltage powers on quickly, while the control circuit voltage requires time to establish its control level. Without power-on sequence control, at the moment of power-on, the high voltage powers on faster than the low voltage, resulting in a lag in control level establishment. This can lead to the servo system losing control at the moment of power-on, causing the motor to experience brief periods of uncontrolled rotation, especially in bipolar control systems. Traditional solutions involve manually controlling the power-on sequence using high and low voltage switches or designing a power-on sequence control circuit within the control system. These methods inevitably increase circuit complexity, cost, and reliability. A simple and effective solution is to address this issue in the motor drive power supply. The working principle is as follows: the CNT terminal is the module enable control terminal, which controls the module's operating state and acts as a control switch for the output voltage. An optocoupler is typically used to control the state of the CNT terminal. Adding just one optocoupler solves the power-on sequence problem. As shown in Figure 2, the optocoupler input is controlled by the +5V operating voltage of the motor control circuit. This ensures that the +60V power output lags behind the low-voltage +5V, achieving power-on timing control and fundamentally solving the aforementioned problem. Power Supply Protection and Electromagnetic Compatibility Measures The module includes overcurrent, overvoltage, and overheat protection functions, adjustable within ±10% of the rated output voltage using an external potentiometer. In the power system design, we employ TVS surge absorbers at key locations such as the high-voltage input after 220V rectification and the +60V output to protect against voltage transients and surge impacts. This bypass absorption method protects the power system while reducing electromagnetic interference and improving system reliability and lifespan. Our experimentally measured +60V output voltage ripple is between 800mV and 1000mV, which is significantly high. By employing polyester capacitor filtering at the power system's adjustment and output terminals, and utilizing twisted-pair cabling internally, the output ripple of the +60V power system is ultimately controlled within 200mV to 400mV, meeting the requirement of +60V/20A power supply ripple voltage ≤600mV. Conclusion The dedicated servo drive power supply for DC motors is no longer merely a traditional switching power supply; it directly participates in the control of the DC motor. Its unique microcomputer interface control and power-on sequence control functions are particularly suitable for DC motor drive systems, offering significant technical advantages over traditional general-purpose high-power power supplies. Its multi-functional technical features align with the development direction of motor drive power supply systems. This dedicated power supply has been officially delivered and successfully applied to a certain type of astronomical navigation equipment, demonstrating practical functionality, convenient control, and stable and reliable operation.