TWI880768B - Power supply system with hybrid primary-side and secondary-side control - Google Patents

Abstract

The present invention provides a power supply system that combines the primary-side controller and the secondary-side controller to achieve enhanced performance, efficiency, and reliability. The power supply system includes a transformer controlled by the primary-side controller during the initial startup phase. After the initial startup phase, control is transferred to the secondary-side controller. The primary-side controller features an internal switch and a zero-crossing detection circuit that monitors the operation and facilitates the transition. The transformer comprises a primary winding and a secondary winding, with the primary winding connected to the internal switch. Additionally, the invention includes a high-electron-mobility transistor triggered by a drive signal from the primary-side controller to provide greater power handling capability and reduce on-resistance. The secondary-side controller is typically a microcontroller unit-based controller that provides precise regulation and adaptive control post-startup. Furthermore, the power supply system includes an overcurrent protection circuit on the primary side and a feedback loop on the secondary side for real-time adjustments based on load conditions.

Description

Power supply system with primary side and secondary side hybrid control

The present invention generally relates to power supply systems, and more particularly, to a transformer power supply system including a primary side controller and a secondary side controller.

Transformers are widely used in various applications to efficiently convert electrical energy. They are very popular in low to medium power applications due to their simple and cost-effective design. A typical transformer consists of a transformer, a primary switch, and associated control circuitry. The primary switch controls the current flow in the transformer's primary winding, which stores energy in the magnetic field during the "on" phase. This stored energy is transferred to the secondary winding during the "off" phase and delivered to the load.

Traditional transformers typically rely on a single controller to manage the startup phase and ongoing regulation of the power supply. While this approach simplifies the design, it can limit the converter's performance in applications that require precise regulation and high efficiency under varying load conditions. In addition, the controller's internal components, such as the primary switches, may have limitations in terms of power handling capabilities and thermal management.

To address these limitations, some advanced designs incorporate secondary-side controllers that take over control after the initial startup phase. These controllers are typically based on microcontroller units (MCUs) that can implement complex control algorithms to optimize performance and efficiency. In addition, adding external switching components, such as high-electron-mobility transistors (HEMTs), can significantly increase power handling capabilities and reduce on-resistance (Ron), thereby improving the efficiency of the overall power supply system.

However, integrating these advanced features into a coherent and efficient system presents several challenges. This requires smooth switching between primary-side and secondary-side control, robust protection mechanisms to safeguard components, and efficient management of heat dissipation.

The present invention aims to overcome these challenges by providing a power supply system including a primary-side controller capable of operating in both independent and slave modes, a HEMT transistor for enhanced power handling, and a precisely regulated secondary-side controller. The invention leverages the advantages of both primary-side and secondary-side control to provide a robust, efficient, and adaptable power supply solution.

The purpose of this invention is to solve the above and other related existing technical problems.

The present invention provides a novel power supply system that enhances performance, efficiency and reliability by combining the functions of a primary-side controller and a secondary-side controller. The power supply system includes a transformer controlled by a primary-side controller during an initial startup phase, and after the startup phase, it switches to a slave mode controlled by a secondary-side controller. This hybrid control method optimizes power processing and regulation under different load conditions.

The primary-side controller operates in independent mode during the initial startup phase, ensuring that the power supply system starts up reliably and independently. After a predetermined number of clock cycles (monitored by the zero-crossing detection circuit (ZCD circuit)), the power supply system switches to slave mode and the secondary-side controller takes over the regulation and control functions. The primary-side controller includes an internal switch and a ZCD circuit. The internal switch controls the current flow in the primary winding of the transformer, while the ZCD circuit monitors the operation of the power supply system and facilitates the transition from independent mode to slave mode.

The primary winding of the transformer is connected to the internal switches of the primary side controller, while the secondary winding of the transformer is connected to the secondary side controller. This configuration allows for efficient energy storage and transfer during the operation of the power supply system. The secondary side controller (usually a microcontroller unit based controller) provides precise regulation and adaptive control after the initial startup phase. It improves system performance by implementing advanced control algorithms and real-time adjustments based on load conditions.

The HEMT transistor configured external to the primary-side controller is connected to the transformer and triggered by the drive signal of the primary-side controller. The use of HEMT transistors significantly enhances power handling capability and reduces on-resistance, thereby improving overall efficiency and thermal management. The power supply system includes an overcurrent protection circuit configured to provide primary-side overcurrent protection (OCP). This overcurrent protection circuit disables the internal switch and HEMT transistor in overcurrent conditions, protecting components in the power supply system and ensuring reliable operation. In addition, the secondary-side controller includes a feedback loop that adjusts the operation of the primary-side controller in real time based on load conditions. This feedback mechanism ensures optimal performance and adaptability under different power demands.

In summary, the present invention provides a robust and efficient power supply solution by utilizing the combined advantages of primary-side and secondary-side control. The integration of HEMT transistors further enhances power handling and efficiency, making the power supply system suitable for a wide range of applications with different power requirements.

In order to make the above features and advantages of the present invention more clearly understood, the following is a detailed description of the preferred embodiment with the accompanying drawings.

100: Power supply system

110: Primary side controller

112: Internal switch

114:ZCD circuit

116: Overcurrent protection circuit

120: Transformer

122: Beginner Winding

124: Secondary winding

130: Secondary side controller

140:HEMT transistor

150: Feedback loop

FIG1 shows a block diagram of one embodiment of the power supply system of the present invention.

Figure 2 shows a block diagram of some components of the primary side controller of the present invention.

FIG3 shows the relationship between the zero-crossing period, slave mode, and drive signal in this embodiment.

The present invention provides a robust and efficient power supply system that achieves enhanced performance, efficiency and reliability by combining the advantages of primary-side controllers and secondary-side controllers. The system is particularly suitable for applications requiring precise regulation and high power handling capabilities. The following detailed description outlines the structure and operation of the power supply system, highlighting the innovations of the design.

Please refer to FIG. 1 and FIG. 2 simultaneously. FIG. 1 shows a block diagram of one embodiment of the power supply system of the present invention, and FIG. 2 shows a block diagram of some components of the primary side controller of the present invention. The power supply system 100 includes a primary side controller 110 and a transformer 120. The primary side controller 110 is configured to operate in an independent mode during an initial startup phase and to operate in a slave mode after the initial startup phase. The primary side controller 110 includes an internal switch 112 and a ZCD circuit 114. In addition, the primary winding 122 of the transformer 120 is electrically connected to the internal switch 112 and the secondary winding 124 of the transformer 120. Internal switch 112 is responsible for controlling the current flow in primary winding 122 of transformer 120, and ZCD circuit 114 monitors the operation of power supply system 100, particularly detecting the zero-crossing points of the voltage of transformer 120. This detection facilitates the transition from independent mode to slave mode after a predetermined clock cycle.

In this embodiment, the internal switch 112 is a power transistor, such as a MOSFET, which is integrated into the primary side controller 110. During the initial startup phase, the internal switch 112 controls the current flow of the primary winding 122 of the transformer 120. When the internal switch 112 is closed, the current flows through the primary winding 122, storing energy in the magnetic field of the transformer 120. When the internal switch 112 is opened, the stored energy is transferred to the secondary winding 124 to provide power to the load. The primary side controller 110 adjusts the cycle of the internal switch 112 to ensure that the transformer 120 can effectively transfer energy and operate stably during the initial startup phase.

In addition, in the present embodiment, the ZCD circuit 114 monitors the voltage on the winding of the transformer 120, and detects the zero crossing point of the voltage waveform. Zero crossing detection is very important for the switching action of the synchronous internal switch 112. The ZCD circuit 114 ensures that the internal switch 112 runs at the best time, maximizes the energy transfer efficiency, and minimizes the switch loss. In addition, in the present embodiment, the ZCD circuit 114 is also used to promote the conversion of the primary side controller 110 from the independent mode to the slave mode. After detecting a predetermined number of zero crossing cycles, the ZCD circuit 114 triggers the primary side controller 110 to hand over the control right to the secondary side controller 130. In this embodiment, as shown in FIG3 , the predetermined number of zero-crossing cycles (clock cycles) is set to 6.5 clock cycles. Of course, a person skilled in the art may also set the predetermined number of zero-crossing cycles to other values, such as 5 or 8.

In this embodiment, an important aspect of the communication between the primary-side controller 110 and the secondary-side controller 130 is the electrical connection between the pin ZCD of the primary-side controller 110 and one of the pins of the secondary-side controller. The electrical connection between the pin ZCD and the secondary-side controller 130 enables the secondary-side controller 130 to monitor zero-crossing events and operate synchronously with the primary-side controller 110.

In the present embodiment, the transformer 120 itself is controlled by the primary side controller 110 during the initial startup phase. The primary side controller 110 independently manages the operation of the transformer 120, ensuring that the power supply system 100 starts correctly and stabilizes the power output. The ZCD circuit 114 ensures that the transition to slave mode occurs smoothly and in a timely manner. Once the initial startup phase is completed, control of the power supply system 100 is transferred to the secondary side controller 130. In the present embodiment, the secondary side controller 130 is typically a controller based on a microcontroller unit, taking over the regulation and control functions, providing more sophisticated and accurate power management. The microcontroller unit-based controller is able to implement advanced control algorithms such as pulse width modulation (PWM) and peak current mode control, and make real-time adjustments based on feedback from load conditions. This capability significantly improves the performance and adaptability of the power supply system 100, enabling it to maintain optimal efficiency under various operating conditions.

In the present embodiment, the power supply system 100 further includes a HEMT transistor 140, which provides excellent electrical characteristics, such as high electron mobility and low on-resistance. The HEMT transistor 140 is connected to the transformer 120 and is triggered by a drive signal from the primary side controller 110. In the present embodiment, the drive signal is issued by the drive pin DRV of the primary side controller 110. The drive signal coordinates the switching action of the HEMT transistor 140 with the operation of the internal switch 112 to ensure synchronous and efficient energy transfer. By controlling the gate voltage of the HEMT transistor 140, the drive signal achieves precise regulation of the conduction state of the HEMT to optimize its performance. Using HEMT transistor 140 provides several advantages. It significantly enhances the power handling capability of power supply system 100, being able to manage higher currents and lower on-resistance. Lower on-resistance translates into lower conduction losses in the switch on state, improving the overall efficiency of power supply system 100. In addition, HEMT transistor 140 facilitates better thermal management by distributing the heat generated by internal switch 112 and HEMT transistor 140, thereby reducing thermal stress on individual components and enhancing the reliability and life of power supply system 100.

Please continue to refer to FIG. 1 and FIG. 2 . In one embodiment, the primary-side controller 110 of the power supply system 100 further includes an over-current protection circuit 116 configured to provide primary-side over-current protection. When the power supply system 100 is in operation, the over-current protection circuit 116 continuously monitors the current flow on the primary side of the system. In the case of over-current, after the over-current protection circuit 116 detects the over-current condition, the over-current protection circuit 116 instructs the primary-side controller 110 to send a signal to disable the internal switch 112. At the same time, the driving signal sent to the HEMT transistor 140 is also cut off, thereby turning off the HEMT transistor 140. This coordinated deactivation ensures that the entire power path can be shut down quickly and safely, preventing damage to the components of the power supply system 100 and the loads connected thereto, thereby ensuring the safety and reliability of the power supply system 100. This feature is important for maintaining the safety and reliability of the power supply system 100 in the event of unexpected load conditions or failures that may occur.

In addition, to further enhance the performance of the power supply system 100, the power supply system 100 further includes a feedback loop 150, which is electrically connected to the secondary-side controller 130. The secondary-side controller 130 makes real-time adjustments to the operation of the primary-side controller based on the load conditions fed back by the feedback loop 150. In detail, the feedback loop 150 continuously monitors the output voltage and current of the power supply system 100. By comparing the actual output value with the desired set point, the secondary-side controller 130 can make real-time adjustments to the switching pattern and duty cycle. These adjustments ensure that the power supply can maintain stable output and optimal performance when load conditions change dynamically.

The feedback loop 150 enables the power supply system 100 to smoothly adapt to different load conditions. Whether the load increases or decreases, the secondary side controller 130 can react quickly and adjust the control parameters. This feedback mechanism ensures that the power supply system 100 can adapt to different power demands and maintain stable and efficient operation. The secondary side controller 130 generates a control signal to regulate the operation of the transformer in slave mode, ensuring accurate regulation of the output voltage and current.

In the above-described embodiment, the secondary-side controller 130 generates control signals based on the feedback from the feedback loop 150. These control signals are transmitted to the primary-side controller 110 to regulate the operation of the internal switch 112 and the HEMT transistor 140. A typical mechanism for transmitting these control signals generally involves the use of an optocoupler or similar isolation device to ensure electrical isolation between the primary and secondary sides. For example, an optocoupler (not shown) includes an LED and a phototransistor, wherein the LED is located on the secondary side and the phototransistor is located on the primary side. The control signals generated by the secondary-side controller 130 are sent to the LED of the optocoupler, which then converts these control signals into light signals. After the light emitted by the LED is detected by the primary-side phototransistor, the phototransistor converts the optical signal back into an electrical signal and then transmits it to the primary-side controller 110.

In summary, the present invention provides a power supply system that integrates the advantages of primary-side and secondary-side control and adds HEMT transistors to enhance power handling and efficiency. The design of the power supply system includes a smooth transition from independent mode to slave mode, a strong protection mechanism and instant adaptive control. These features make the power supply system suitable for a wide range of applications, providing a reliable, efficient and adaptable modern power supply solution.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone with common knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of the patent application attached hereto.

100: Power supply system

110: Primary side controller

120: Transformer

122: Beginner Winding

124: Secondary winding

130: Secondary side controller

140:HEMT transistor

150: Feedback loop

Claims (7)

A power supply system comprises: A transformer comprising a primary winding and a secondary winding; A primary side controller disposed on a primary side of the transformer, the primary side controller operating in an independent mode in an initial startup phase, and operating in a slave mode after the initial startup phase, wherein the primary side controller comprises: An internal switch electrically connected to the primary winding; and A zero-crossing detection circuit disposed to monitor the operation of the power supply system; A secondary side controller disposed on a secondary side of the transformer, taking over the control of the power supply system after the initial startup phase; A high electron mobility transistor is arranged outside the primary side controller and electrically connected to the transformer, and the high electron mobility transistor is triggered by a driving signal of the primary side controller to enhance power handling capability and reduce on-resistance; wherein the transformer is controlled by the primary side controller during the initial startup phase; wherein the primary side controller switches from the independent mode to the slave mode after the zero crossing detection circuit detects a predetermined number of clock cycles. A power supply system as described in claim 1, wherein the primary-side controller switches from independent mode to slave mode after the zero-crossing detection circuit detects 6.5 clock cycles. A power supply system as described in claim 1, wherein the secondary-side controller is a controller based on a microcontroller unit configured to provide precise regulation and adaptive control of the power supply system. A power supply system as described in claim 1, wherein the drive signal is issued by a drive pin of the primary side controller to control the high electron mobility transistor. A power supply system as described in claim 1, wherein the primary side controller includes an over-current protection circuit, which is configured to provide over-current protection for the primary side. A power supply system as described in claim 5, wherein the overcurrent protection circuit is configured to disable the internal switch or the high electron mobility transistor when an overcurrent condition is detected on the primary side. The power supply system of claim 1 further comprises a feedback loop electrically connected to the secondary-side controller to provide real-time adjustment of the operation of the primary-side controller based on a load condition.

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