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Introduction
The radar transmitter has high requirements for the stability of its high voltage power supply. When designing a high voltage power supply, it usually needs to go through two or more levels of voltage regulation from the ordinary power supply system to meet output requirements, and it also needs to consider power isolation, volume, heat dissipation, reliability, and other issues.
Module power supplies have obvious advantages over discrete component power supplies in terms of flexibility, efficiency, and reliability. Using module power supplies can design the first stage of voltage regulation for an effective high voltage power supply while considering power isolation, volume, heat dissipation, reliability, and other requirements, shortening the time spent on development or design changes, and saving manpower and technical costs. This allows the design to focus on the main circuit of the high voltage power supply, improving design efficiency.
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Analysis of Module Power Supply Characteristics
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Advantages
(1)Diverse varieties: There are AC/DC, DC/DC, EMI modules, etc.
(2)Simple design: Power modules only require a few discrete components to obtain power. Module power supplies are generally equipped with standardized front-ends, highly integrated power modules, and other components, significantly simplifying design applications.
(3)Shortened development cycle: Module power supplies usually come with various input and output options. Users can also stack or cross-stack them to create modular power supplies, achieving multiple input and output paths, greatly reducing development time. Certain module power supplies can be specially ordered for unique needs.
(4)Flexible changes: If product design needs to change, simply switch or parallel another suitable power module.
(5)Convenient heat dissipation: The module power supply casing has a structure that integrates a heat sink, radiator, and outer casing. This achieves conduction cooling for the module power supply, bringing the temperature of the power supply close to the minimum value. Moreover, the module power supply looks aesthetically pleasing.
(6)High quality and reliability: Module power supplies are generally produced with full automation and high-tech production techniques, ensuring stable and reliable quality.
2
Disadvantages
(1)Generalized design of module power supplies: In some special cases where space is small and heat dissipation is inconvenient, the required high power density module power supply models are few, making selection difficult.
(2)Higher price of module power supplies: They occupy a certain amount of space and weight. Therefore, during design, the power supply of module power supplies should meet the requirements, and the number of modules should not be excessive to reduce space and weight costs.
3
Application range of module power supplies in high voltage power supply
The main circuit of the high voltage circuit consists of the control circuit and the high voltage generation circuit. The AC power input and the required low voltage DC control power supply, as well as filtering or power factor compensation, can all use module power supplies.
2
Requirements for the use of module power supplies in high voltage power supply
The high voltage power supply for vacuum electronic devices in radar transmitters needs to be specially designed, with high stability requirements. When designing a high voltage power supply, it usually needs to go through two or more levels of voltage regulation from the ordinary power supply system to meet output requirements. Additionally, it needs to consider power isolation, volume, heat dissipation, reliability, and other issues.
The range of module power supplies used in high voltage power supplies includes: filtering power conversion circuits, control parts (low voltage), while the high voltage part generally does not use commercially available high voltage module power supplies but requires special designs based on the parameters required by the transmitter. A block diagram of a certain type of high voltage power supply is shown in Figure 1.
1
Analysis of power input and control circuit
The power input of the high voltage power supply consists of two parts: one part is AC power, usually generated by a vehicle-mounted or airborne generator. Typically at 400 Hz or 50 Hz, voltage is selected around 115 V or 220 V. Medium and small power high voltage power supplies choose single-phase power supply, while large power high voltage power supplies choose three-phase power supply. The other part is low voltage DC power supply, mainly used for the control part of the high voltage power supply, such as ±5 V, ±15 V, ±27 V, etc. The current is generally small, and the power is not high.
In actual systems, the high voltage power supply obtains power from the system. AC power provides the power source, while low voltage DC power provides control use. For grounding safety, the system typically connects the digital ground, analog ground, cable shielding layer, and chassis ground. In some cases, the return line of low voltage DC power may be directly connected to the shielding layer or ground. The PWM control part of the high voltage power supply must compare with the high voltage feedback voltage, and the required low voltage DC power often needs to be powered separately to ensure isolation, and its return line cannot be grounded. In this case, the system’s low voltage DC power supply cannot meet the requirements, and the high voltage power supply cannot use this power supply from the system, but must use suitable DC/DC module power supplies within the high voltage power supply to generate the required isolated low voltage DC power supply.
2
Analysis of filtering and power conversion circuits
The stability of high voltage power supplies has high requirements, and the output is often multiple power supplies, so a single-stage voltage regulation often cannot meet the stability requirements of high voltage power supplies.
During power conversion, it is necessary to invert DC power into high-frequency AC power to send to the high voltage transformer. After rectifying and filtering the AC input, the use of a voltage regulation module power supply provides DC/DC conversion, becoming the first stage of voltage regulation, which is then inverted into high-frequency AC power sent to the high voltage transformer for boosting and voltage regulation, i.e., the second stage of voltage regulation. Thus, going through two or more levels of voltage regulation from the ordinary power supply system to meet output requirements.
Additionally, for the rectification and filtering of AC input, suitable AC/DC module power supplies, filtering, or power factor compensation modules can also be selected.
3
Usage requirements
The module power supplies used in the high voltage power supply of the transmitter must meet national military standard requirements.
Module power supplies must meet the corresponding requirements for installation, volume, heat dissipation, and weight of the high voltage power supply in terms of structural appearance, and must endure the system’s strict environmental stress tests.
3
Application of Module Power Supplies
1
Adjustment of output voltage
For module power supplies with TRIM or ADJ (adjustable output pin), the output voltage can be adjusted within a certain range through a resistor or potentiometer, typically ±10%.
For TRIM output pins, connect the center of the potentiometer to TRIM, and on all +S, -S pins of the module, connect the other two ends to +S, -S. If there are no +S, -S, connect the two ends to the corresponding positive and negative terminals of the main circuit (+S to +, -S to -UIN), then adjust the potentiometer.It is generally appropriate to choose a potentiometer resistance of 5-10 kΩ.
For ADJ output pins, there are input side adjustment and output side adjustment.Output side adjustment is the same as the adjustment method for TRIM pins. Input side adjustment can only raise the output voltage. At this time, connect one end of the potentiometer to the center and the other end to the ground of the input terminal.
2
Adjustment of input voltage
Generally, module power supplies have built-in filters that can meet the requirements of general power applications. If higher requirements for power systems are needed, an input filter network should be added. LC or type II networks can be used, but attention should be paid to choosing smaller inductance and larger capacitance.
To prevent transient high voltage from damaging the module power supply at the input, it is recommended that users connect transient suppression diodes at the input terminal and use them with fuses to ensure the module stays within a safe input voltage range. To reduce common mode noise, capacitance can be increased, generally choosing high-frequency capacitance of several nF.
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On/Off Circuit
The switching operation of the module power supply is performed through the REM terminal. There are generally two control methods:
(1) Connect REM to -UIN (reference ground) to turn off, requiring UREF < 0.4 V. If REM is floating or connected to +UIN, the module works, requiring UREM > 1 V.
(2) Connect REM to UIN to turn off, requiring UREM < 0.4 V. If REM is connected to +UIN, the module works, requiring UREM > 1 V. If REM is floating, it turns off, which is known as “floating off” (-R).
If control needs to be isolated from the input terminal, a photocoupler can be used to transmit control signals.
4
Combination of Module Power Supplies
(1)Parallel expansion: Connecting the output terminals of the same module in parallel can enhance output capacity. However, the output voltage of parallel modules must be adjusted to be relatively consistent to ensure current sharing while avoiding unnecessary oscillation. For modules with large output currents, lead resistance can be carefully designed to achieve current sharing effects. Modules connected in this way should not exceed 2. Additionally, if one module output fails, the entire system will not function properly.
(2)Redundant hot backup parallel: Connecting the output terminals of the same module in parallel through diodes can enhance output capacity to improve the reliability of the power supply system. In principle, if paired with corresponding output alarm circuits, the modules can be placed on removable buses. This way, faulty modules can be replaced in a timely manner. There is no limit to the number of modules connected in this way.
(3)Series expansion: Connecting the output terminals of the same module in series can double the output voltage and increase power accordingly, while series output terminals must connect diodes for protection.
4
Installation and Maintenance of Module Power Supplies
Due to the many categories, series, and specifications of module power supplies, their functional characteristics and physical properties vary. Therefore, there are different considerations for installation, use, and maintenance.
It is necessary to pay attention to the following aspects:
(1)After unpacking the package: Check whether the labels on each terminal correspond to the instructions that come with it, and whether they meet the requirements specified in the purchase contract. If there are discrepancies, contact the purchasing unit immediately to discuss a solution.
(2)The first step in installation: The metal casing of the module power supply must be reliably grounded to ensure safety, but do not mistakenly connect the casing to the neutral line.
(3)Before powering on after installation: Check the connections at each terminal again to ensure that input and output, AC and DC, single-phase and multi-phase, positive and negative, voltage and current values are all correct, eliminating the possibility of incorrect or reversed connections.
(4)For high power supplies: There are generally two or more “+” and “-” output terminals. In fact, this is to facilitate user wiring; they are internally connected together and belong to one output electrode.
(5)Module power supplies should not operate under full load for long periods: The utilization rate of linear power supplies should be controlled within 60%; for switching power supplies, it should be controlled within 80%. Otherwise, it may cause early failure of the module power supply.
(6)There is a fixed resistor between the terminals (ADJ): Users must provide a potentiometer with the corresponding resistance value to replace the fixed resistor. However, it should be noted that when the adjustable terminals are in an open circuit state, loading is strictly prohibited.
(7)For adequate heat dissipation, module power supplies should be installed in areas with good air circulation: For modules requiring heat sinks, the back panel must be evenly coated with thermal silicone grease and tightly attached to the heat sink, and securely fastened. Generally, it is required that linear power supplies operate at a current of 4 A or more, or switching power supplies operate at a current of 7 A or more, should be equipped with forced air cooling. Additionally, no other items should be placed on the module power supply casing.
(8)Module power supplies are generally suitable for resistive loads: If they need to be used with capacitive or inductive loads, prior arrangements must be made during ordering.
(9) The high voltage power supply of the transmitter generally does not use commercially available high voltage module power supplies, but is specially designed for high voltage circuits. If high voltage module power supplies are used, they must not be touched within 10 minutes after power off in case of high voltage danger.
(10)Module power supply selection principles: Generally, for higher power, switching power supplies are preferred; for lower power, linear power supplies are selected.
(11) Module power supplies are rarely damaged; if the high voltage power supply is abnormal, such as not powering on, power off, and check whether the input and output terminals of the module power supply installed in the high voltage power supply are open or short-circuited. If these phenomena occur, it indicates that the module power supply is damaged, and it can be replaced. Module power supplies are usually sealed by the manufacturer and should not be forcibly disassembled.
* The content of this article is sourced from the China Electric Power Alliance and the internet, with deletions and modifications. Copyright belongs to the original author. The data and graphic information involved are for reference only and do not represent the position of this public account. If there is any infringement, please contact us for deletion.
About the Exhibition
2025 World Power Industry Expo is an international trade service platform based in Guangzhou, radiating Asia and influencing the world. After more than ten years of development, it has become a well-known one-stop procurement and trading event in the power supply industry, providing opportunities for power chain enterprises to launch new products, promote brands, develop channels, and secure orders, as well as an annual event for trade negotiations, investment, and financing connections among power industry chain personnel, facilitating deep connections in the supply chain transaction links and promoting order fulfillment, project cooperation, and investment connections.
Exhibition Information
Exhibition Date: August 8-10, 2025
Exhibition Location: Guangzhou·Canton Fair Exhibition Center
Contact Us
Contact Unit: Guangdong Hongwei International Exhibition Group Co., Ltd.
Contact Phone: 4006-258-268
Contact Address: 7th Floor (Whole Floor), Poly World Trade Center, No. 1000, Xinguang East Road, Haizhu District, Guangzhou
