Isolated converter and control method thereof

Abstract

The application relates to an isolated converter, a transformer is connected between a primary circuit and a secondary circuit, so that the primary circuit and the secondary circuit are isolated from each other, a primary controller is connected to the primary circuit, the primary circuit is sampled to generate a primary sampling signal, the primary controller provides a primary drive carrier, and a primary drive signal is generated according to the primary drive carrier to control the primary circuit, a secondary controller is connected to the secondary circuit, the secondary controller provides a secondary drive carrier, and a secondary drive signal is generated according to the secondary drive carrier to control the secondary circuit, a first communication channel is connected between the primary controller and the secondary controller, so that the primary sampling signal is transmitted to the secondary controller, and a second communication channel is connected between the primary controller and the secondary controller, so that the secondary drive signal is transmitted to the primary controller or the primary drive signal is transmitted to the secondary controller, so that synchronization between the primary drive carrier and the secondary drive carrier is realized.

Description

Technical Field

[0001] This case relates to converters, and more particularly to an isolated converter and its control method. Background Technology

[0002] High-frequency isolated converters are applied to solid-state transformers, which have broad application prospects in DC power consumption or power generation fields such as data centers, electric vehicle charging and swapping stations, photovoltaics, or energy storage. Each phase circuit in a solid-state transformer consists of multiple isolated converters connected in series at the input and in parallel at the output. Each isolated converter is composed of an AC / DC conversion unit and an isolated DC / DC conversion unit.

[0003] In the aforementioned application scenarios, DC / DC conversion units require electrical isolation. High-frequency isolation transformers utilize insulating plates to isolate the primary and secondary circuits. Therefore, the primary and secondary controllers typically communicate via wired connections. Traditional isolated converters contain four communication channels, each constructed from optical fibers. The primary and secondary controllers use two communication channels to exchange sampled values ​​or commands, while the secondary controller uses two channels to transmit drive signals from the primary circuit to the primary circuit. Thus, each traditional isolated converter requires four communication channels, meaning four optical fibers are needed for communication. As the number of isolated converters in each phase of a solid-state transformer increases, the number of optical fibers required for the overall system rises significantly, increasing the cost of traditional isolated converters. Furthermore, the likelihood of high-frequency electromagnetic interference increases dramatically, reducing the converter's anti-interference capability, hindering modularization, and reducing overall scalability.

[0004] Therefore, it is necessary to develop an isolated converter and its control method to solve the problems faced by the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide an isolated converter comprising two communication channels. The first communication channel transmits the primary-side sampling signal provided by the primary-side controller to the secondary-side controller. The second communication channel transmits information from the secondary-side drive carrier provided by the secondary-side controller to the primary-side controller, or vice versa, thereby achieving synchronization between the primary-side and secondary-side drive carriers. Therefore, the isolated converter of this invention eliminates the need for separate communication channels between the primary-side controller and the secondary-side circuit, as well as between the secondary-side controller and the primary-side circuit, thus reducing the cost of the isolated converter and improving system anti-interference and scalability.

[0006] To achieve the above objectives, one embodiment of this invention provides an isolated converter comprising a primary-side circuit, a secondary-side circuit, a transformer, a primary-side controller, a secondary-side controller, a first communication channel, and a second communication channel. The primary-side circuit includes a first port and a second port. The transformer is connected between the primary-side circuit and the secondary-side circuit, isolating them from each other. The second port of the primary-side circuit is connected to the primary winding of the transformer. The primary-side controller is connected to the primary-side circuit, samples the primary-side circuit to generate a primary-side sampling signal, provides a primary-side drive carrier, and generates a primary-side drive signal based on the primary-side drive carrier to control the primary-side circuit. The secondary-side controller is connected to the secondary-side circuit, provides a secondary-side drive carrier, and generates a secondary-side drive signal based on the secondary-side drive carrier to control the secondary-side circuit. The first communication channel is connected between the primary-side controller and the secondary-side controller to transmit the primary-side sampling signal to the secondary-side controller. The second communication channel is connected between the primary-side controller and the secondary-side controller to transmit information on the secondary-side drive carrier to the primary-side controller or vice versa, so as to achieve synchronization between the primary-side drive carrier and the secondary-side drive carrier.

[0007] To achieve the above objectives, another embodiment of this invention provides a control method applied to an isolated converter. The isolated transformer includes a primary circuit, a secondary circuit, and a transformer. The primary circuit includes a first port and a second port. The transformer is connected between the primary circuit and the secondary circuit, isolating them from each other. The second port of the primary circuit is connected to the primary winding of the transformer. The control method includes the following steps: First, a primary-side controller is set up to sample the primary circuit to generate a primary-side sampling signal. The primary-side controller provides a primary-side drive carrier and generates a primary-side drive signal based on the primary-side drive carrier to control the primary circuit. Next, a secondary-side controller is set up to provide a secondary-side drive carrier and generates a secondary-side drive signal based on the secondary-side drive carrier to control the secondary circuit. Then, a first communication channel is set up between the primary-side controller and the secondary-side controller to transmit the primary-side sampling signal to the secondary-side controller. Next, a second communication channel is set up between the primary-side controller and the secondary-side controller to transmit information on the secondary-side drive carrier to the primary-side controller or vice versa, so as to achieve synchronization between the primary-side drive carrier and the secondary-side drive carrier. Attached Figure Description

[0008] Figure 1 This is the circuit architecture diagram of the isolated converter in this case;

[0009] Figure 2 for Figure 1 The diagram shows the drive carrier waveform of a first embodiment of the isolated converter.

[0010] Figure 3 for Figure 1 The waveform diagram showing the correspondence between the drive signal and the count value of the drive carrier of the isolated converter is shown.

[0011] Figure 4 This is a diagram of the drive carrier waveform for a traditional isolated converter.

[0012] Figure 5 for Figure 1 The diagram shows the drive carrier waveform of a second embodiment of the isolated converter.

[0013] Figure 6 for Figure 1 The diagram shows the drive carrier waveform of the third embodiment of the isolated converter.

[0014] Figure 7 for Figure 1 The control diagram of the primary-side controller in the fourth embodiment of the isolated converter shown;

[0015] Figure 8 for Figure 1 The flowchart of the control method for the isolated converter shown; and

[0016] Figure 9 for Figure 1 The waveforms of the primary and secondary drive signals of the isolated converter are shown.

[0017] Explanation of reference numerals in the attached figures:

[0018] Vin: Input power

[0019] 1: Isolated converter

[0020] 2: Primary circuit

[0021] 21: First bridge arm

[0022] M1: First switch

[0023] M2: Second switch

[0024] A1: First connection point

[0025] 22: Second bridge arm

[0026] M3: Third Switch

[0027] M4: Fourth Switch

[0028] A2: Second connection point

[0029] C1: Resonant inductor

[0030] L1: Resonant capacitor

[0031] 3: Transformer

[0032] 4: Secondary circuit

[0033] 41: Third bridge arm

[0034] M5: Fifth Switch

[0035] M6: Sixth Switch

[0036] A3: Third connection point

[0037] 42: Fourth bridge arm

[0038] M7: Seventh Switch

[0039] M8: Eighth Switch

[0040] A4: Fourth connection point

[0041] Cout: Output capacitor

[0042] 51: Primary-side controller

[0043] 52: Secondary controller

[0044] 61: First communication channel

[0045] 62: Second communication channel

[0046] Time intervals: t1, t2, t3, t4, t41, T1, T2, T3

[0047] CP1: First primary edge count value

[0048] CP2: Second primary edge count value

[0049] CP3: Third primary edge count value

[0050] CP4: Fourth primary edge count value

[0051] CS1: First secondary edge count value

[0052] CS2: Secondary edge count value

[0053] CS3: Third secondary edge count value

[0054] CS4: Fourth secondary edge count value

[0055] 511: Subtractor

[0056] 512: Regulator

[0057] 513: Limiter

[0058] 514: Integrator

[0059] 515: Adder

[0060] S1-S4: Steps Detailed Implementation

[0061] Some typical embodiments embodying the features and advantages of this invention will be described in detail in the following description. It should be understood that this invention can have various variations in different forms, all of which do not depart from the scope of this invention, and the descriptions and drawings herein are for illustrative purposes only and not for limiting the invention.

[0062] Please see Figure 1 , Figure 1 This is a circuit architecture diagram of the isolated converter in this case. As shown in the figure, the isolated converter 1 in this case can be a DC / DC converter and is used for frequency conversion control or fixed frequency control. It receives and converts the input voltage provided by the input power supply Vin and provides the output voltage to the load (not shown). The isolated converter 1 includes a primary circuit 2, a transformer 3, a secondary circuit 4, a primary controller 51, a secondary controller 52, a first communication channel 61, and a second communication channel 62. The primary circuit 2 includes a first bridge arm 21, a second bridge arm 22, a resonant inductor L1, and a resonant capacitor C1. The first bridge arm 21 includes a first switch M1 and a second switch M2. The connection between the first switch M1 and the second switch M2 forms a first connection point A1. The second bridge arm 22 is connected in parallel to the first bridge arm 21 and includes a third switch M3 and a fourth switch M4. The connection between the third switch M3 and the fourth switch M4 forms a second connection point A2. The primary circuit 2 is connected to the input power supply Vin via a first port and to the transformer 3 via a second port. Transformer 3 is an isolation transformer connected between the primary circuit 2 and the secondary circuit 4, isolating them from each other. It includes a primary winding 31 and a secondary winding 32. The resonant inductor L1, resonant capacitor C1, and primary winding 31 are connected in series between the first connection point A1 and the second connection point A2. The secondary circuit 4 includes a third bridge arm 41, a fourth bridge arm 42, and an output capacitor Cout. The third bridge arm 41 includes a fifth switch M5 and a sixth switch M6, with the connection between them forming the third connection point A3. The fourth bridge arm 42 is connected in parallel to the third bridge arm 41 and includes a seventh switch M7 and an eighth switch M8. The connection between the seventh switch M7 and the eighth switch M8 forms the fourth connection point A4, with the secondary winding 32 connected between the third connection point A3 and the fourth connection point A4. The output capacitor Cout is connected in parallel to the fourth bridge arm 42 and the third bridge arm 41.

[0063] The primary-side controller 51 is connected to the input power supply Vin and the first switch M1, second switch M2, third switch M3, and fourth switch M4 of the primary-side circuit 2 to sample the input voltage provided by the input power supply Vin and generate a primary-side sampling signal. In other words, the primary-side sampling signal includes the voltage of the first port of the primary-side circuit 2. The primary-side controller 51 also provides a primary-side drive carrier and a primary-side communication carrier. The primary-side controller 51 generates a primary-side drive signal based on the primary-side drive carrier to control the operation of the first switch M1, second switch M2, third switch M3, and fourth switch M4 of the primary-side circuit 2. The primary-side drive carrier can be a counting value. For example, a counter (not shown) in the primary-side controller 51 generates a counting value, and the counting value can exhibit a sawtooth wave pattern over time, possessing an original primary-side period. When the counter is to generate a count value with an original primary-side period of 1 / 80k, a carrier frequency of 80kHz and a chip frequency of 100MHz can be selected to make the maximum count value generated by the counter 1250, i.e., the chip frequency divided by the carrier frequency (100MHz / 80k = 1250). The count value generated by the counter counts from 0 to 1249 and is reset to zero at the peak value. One round of data transmission can be achieved in each primary-side period. The waveform of the count value will be shown later. In one embodiment, in high-frequency scenarios, the frequency of the primary-side drive carrier of the isolated converter 1 is usually higher than the frequency of the primary-side communication carrier. Therefore, the primary-side drive carrier can be generated based on the primary-side communication carrier.

[0064] The secondary-side controller 52 is connected to the load and the fifth switch M5, sixth switch M6, seventh switch M7, and eighth switch M8 of the secondary-side circuit 4 to sample the output voltage supplied to the load and generate a secondary-side sampling signal. The secondary-side controller 52 further provides a secondary-side drive carrier and a secondary-side communication carrier. The secondary-side controller 52 generates a secondary-side drive signal based on the secondary-side drive carrier to control the fifth switch M5, sixth switch M6, seventh switch M7, and eighth switch M8 of the secondary-side circuit 4, wherein the secondary-side drive carrier can be a counting value. For example, a counter (not shown) in the secondary controller 52 generates a count value, which can exhibit a sawtooth wave pattern over time with a secondary period. When the counter wants to generate a count value with a secondary period of 1 / 80k, a carrier frequency of 80kHz and a chip frequency of 100MHz can be selected, so that the maximum value of the count value generated by the counter is 1250, i.e., the chip frequency divided by the carrier frequency (100MHz / 80k = 1250). The count value generated by the counter counts from 0 to 1249 and is reset to zero at the peak value. One round of data transmission can be achieved in each secondary period. The waveform of the count value will be shown later. In one embodiment, in a high-frequency scenario, the frequency of the secondary drive carrier of the isolated converter 1 is usually higher than the frequency of the secondary communication carrier. Therefore, the secondary drive carrier can be generated based on the secondary communication carrier.

[0065] The first communication channel 61 can be a wired communication such as optical fiber or wireless communication, and is connected between the primary-side controller 51 and the secondary-side controller 52 to transmit the primary-side sampling signal provided by the primary-side controller 51 to the secondary-side controller 52. The second communication channel 62 can be a wired communication such as optical fiber or wireless communication, and is connected between the primary-side controller 51 and the secondary-side controller 52 to transmit the information on the secondary-side drive carrier provided by the secondary-side controller 52 to the primary-side controller 51, or transmit the information on the primary-side drive carrier provided by the primary-side controller 51 to the secondary-side controller 52, so as to realize the synchronization between the primary-side drive carrier and the secondary-side drive carrier, so that the switching of the primary-side circuit 2 and the secondary-side circuit 4 can operate synchronously in both frequency conversion and fixed frequency situations.

[0066] As can be seen from the above, the isolated converter 1 of this invention includes two communication channels. The first communication channel 61 transmits the primary-side sampling signal provided by the primary-side controller 51 to the secondary-side controller 52. The second communication channel 62 transmits the information on the secondary-side drive carrier provided by the secondary-side controller 52 to the primary-side controller 51, or transmits the information on the primary-side drive carrier provided by the primary-side controller 51 to the secondary-side controller 52, so as to achieve synchronization between the primary-side drive carrier and the secondary-side drive carrier. Therefore, the isolated converter 1 of this invention does not require the establishment of a communication channel between the primary-side controller 51 and the secondary-side circuit 4, or a communication channel between the secondary-side controller 52 and the primary-side circuit 2, which can reduce the cost of the isolated converter 1 and improve the system's anti-interference and scalability.

[0067] The following will further explain, based on waveform diagrams, the synchronization method of the primary-side drive carrier and the secondary-side drive carrier in both variable-frequency and fixed-frequency driving scenarios for isolated converter 1. Please refer to... Figure 2 and cooperate Figure 1 ,in Figure 2 for Figure 1 The diagram shows the drive carrier waveform of a first embodiment of the isolated converter. Figure 2The waveforms of the primary carrier (shown as the same primary carrier because the primary and secondary communication carriers are synchronized) and the secondary drive carrier are shown from top to bottom. In this embodiment, the driving frequency of the isolated converter 1 is either in the case of frequency conversion or fixed frequency, as shown in the figure. At the first time t1, the primary controller 51 records the first primary-side count value CP1 of the primary drive carrier at the first time t1, and the secondary controller 52 records the first secondary-side count value CS1 of the secondary drive carrier at the first time t1. The secondary controller 52 then sends the first secondary-side count value CS1 of the secondary drive carrier at the first time t1 to the primary controller 51 via the first communication channel 61. At the second time t2, the primary-side controller 51 receives the first secondary-side count value CS1 of the secondary-side driving carrier at the first time t1. The primary-side controller 51 subtracts the first primary-side count value CP1 of the primary-side driving carrier at the first time t1 from the first secondary-side count value CS1 of the secondary-side driving carrier at the first time t1, adds the second primary-side count value CP2 of the primary-side driving carrier at the second time t2, and divides the result by the current primary-side period of the primary-side driving carrier. The remainder obtained is the target value, where the target value is the target value of the count value that the primary-side driving carrier wants to update at the second time t2.

[0068] When the target value to be updated for the primary-side driving carrier at the second time t2 is near the peak value of the primary-side driving carrier, the primary-side controller 51 abandons the correction of the primary-side driving carrier. In this embodiment, the primary-side controller 51 further confirms whether the target value is within the first peak value range of the peak value of the primary-side driving carrier, for example, whether the target value is within the range of plus or minus one count value of the count value of the peak value of the primary-side driving carrier. When the primary-side controller 51 confirms that the target value is within the first peak value range of the peak value of the primary-side driving carrier, the primary-side controller 51 abandons updating the second primary-side count value CP2 of the primary-side driving carrier at the second time t2 to the target value; when the primary-side controller 51 confirms that the target value is not within the first peak value range of the peak value of the primary-side driving carrier, the primary-side controller 51 updates the second primary-side count value CP2 of the primary-side driving carrier at the second time t2 to the target value.

[0069] Furthermore, to prevent narrow pulses and ensure the symmetry of the positive and negative half-cycles of the drive signals output by the primary-side controller 51 and the secondary-side controller, the primary-side drive carrier and the secondary-side drive carrier of the isolated converter 1 can only correct the current primary-side period and the current secondary-side period at the peak of the corresponding drive carrier. For example... Figure 3 As shown, it is Figure 1The diagram shows the waveforms corresponding to the drive signal and the count value of the drive carrier in the isolated converter. As can be seen from the diagram, the drive carrier corrects the current primary-side period and the current secondary-side period at times T1, T2, and T3. However, in some cases, the primary-side drive carrier and the secondary-side drive carrier are not perfectly synchronized; they may have a slight phase difference. For example... Figure 4 As shown, Figure 4 The driving carrier waveform diagram of a traditional isolated converter is shown below. Figure 4 As shown by the dashed line, in a traditional isolated converter, the primary-side drive carrier is at a valley while the secondary-side drive carrier is at a peak. This may cause the update times of the primary and secondary drive carriers to be asynchronous, resulting in a phase difference between them. Figure 4 As shown, it is impossible to correct the current primary-side period and the current secondary-side period at the peak value. In order to avoid the phase difference problem caused by this, the isolated converter 1 of this case uses the following method to synchronously update the current primary-side period and the current secondary-side period of the primary-side driving carrier and the secondary-side driving carrier.

[0070] Please see Figure 5 , it is Figure 1 The diagram shows the drive carrier waveform of a second embodiment of the isolated converter. As shown, the primary-side controller 51 and the secondary-side controller 52 drive the primary-side communication carrier and the secondary-side communication carrier (i.e., ...) Figure 5 The primary controller 52 determines the third time t3 and the fourth time t4 based on the fundamental carrier. The third time t3 is the preset time when the secondary controller 52 sends the first update period to the primary controller 51. The fourth time t4 is the preset time when the primary controller 51 sets the current primary period of the primary driving carrier to the first update period, and simultaneously the secondary controller 52 sets the current secondary period of the secondary driving carrier to the first update period. The secondary controller 52 further subtracts the third time t3 from the fourth time t4, adds the third secondary count value CS3 of the secondary driving carrier at the third time t3, divides it by the current secondary period of the secondary driving carrier, and takes the remainder to obtain the fourth secondary count value CS4 of the secondary driving carrier at the fourth time t4.

[0071] In this embodiment, the secondary-side controller 52 further confirms whether to update the period. The secondary-side controller 52 confirms whether the fourth secondary-side count value CS4 of the secondary-side driving carrier at the fourth time t4 is within the second peak range of the peak value of the secondary-side driving carrier. For example, it confirms whether the fourth secondary-side count value CS4 of the secondary-side driving carrier at the fourth time t4 is within the range of four positive and negative count values ​​of the peak value of the secondary-side driving carrier. When the secondary-side controller 52 confirms that the fourth secondary-side count value CS4 of the secondary-side driving carrier at the fourth time t4 is within the second peak range of the peak value of the secondary-side driving carrier, the secondary-side controller 52 controls the first update period to be the third secondary-side period of the secondary-side driving carrier at the third time t3, that is, the fourth secondary-side count value CS4 of the secondary-side driving carrier at the fourth time t4 is not corrected. When the secondary controller 52 confirms that the fourth secondary count value CS4 of the secondary driving carrier at the fourth time t4 is not within the second peak range of the peak value of the secondary driving carrier, the secondary controller 52 sends the target period value to the primary controller 51 to control the first update period as the target period value. The target period value is formed by the change in the switching frequency of the switch in the secondary circuit 4 caused by the change in the load or operating conditions connected to the output terminal of the isolated converter 1.

[0072] However, when the switching frequency of the switch in the secondary circuit 4 is N times the communication frequency of the secondary communication carrier, and the fourth secondary count value CS4 of the secondary driving carrier at the fourth time t4 is within the second peak range of the peak value of the secondary driving carrier, the fourth secondary count value CS4 of the secondary driving carrier at the fourth time t4 is not corrected in the subsequent several consecutive cycles, causing a mismatch between the output power of the isolated converter 1 and the load connected to the output terminal of the isolated converter 1, which can easily lead to the isolated converter 1 losing control.

[0073] Since the isolated converter 1 uses proportional-integral control, meaning the switching frequency of the switches in the secondary circuit 4 does not experience sudden frequency changes, if the switching frequency is N times the communication frequency, when the fourth secondary-side count value CS4 of the secondary-side drive carrier is near the peak value of the secondary-side drive carrier at the fourth time t4, the secondary-side controller 52 can send the target period value of the secondary-side drive carrier to the primary-side controller 51 to improve the frequency controllable range, i.e., the control method described above. However, if the switching frequency of the switches in the secondary circuit 4 experiences a sudden change, or if the secondary circuit 4 performs a full-bridge or half-bridge switching, the period needs to be updated further based on the frequency change. Please refer to [link to relevant documentation]. Figure 6 , it is Figure 1The diagram shows the drive carrier waveform of the third embodiment of the isolated converter. In this embodiment, the switching frequency of the switches in the secondary circuit 4 is N times the communication frequency. As shown in the figure, the secondary controller 52 not only confirms whether the fourth secondary count value CS4 of the secondary drive carrier at the fourth time t4 is within the second peak range of the peak value of the secondary drive carrier, but also simultaneously confirms whether the switching frequency change of the switches in the secondary circuit 4 is greater than the frequency threshold. For example, it confirms whether the fourth secondary count value CS4 of the secondary drive carrier at the fourth time t4 is within the range of the positive and negative four count values ​​of the peak value of the secondary drive carrier, and simultaneously confirms whether the switching frequency change of any switch in the secondary circuit 4 is greater than the frequency threshold. When the secondary controller 52 confirms that the fourth secondary count value CS4 of the secondary drive carrier at the fourth time t4 is within the second peak range of the peak value of the secondary drive carrier, and simultaneously confirms that the switching frequency change of the switches in the secondary circuit 4 is greater than the frequency threshold, then the secondary controller 52 sends the third secondary period of the secondary drive carrier at the third time t3 to the primary controller 51, that is, it abandons sending the target period value to the primary controller 51.

[0074] When the fourth secondary-side count value CS4 of the secondary-side driving carrier at the fourth time t4 is not within the second peak range of the peak value of the secondary-side driving carrier, or when it is confirmed that the switching frequency change of any switch in the secondary-side circuit 4 is less than the frequency threshold, the secondary-side controller 52 sends a target period value to the primary-side controller 51. The target period value is formed by the change in the switching frequency of the switches in the secondary-side circuit 4 caused by a change in the load connected to the output terminal of the isolated converter 1 or a change in operating conditions. In this embodiment, the frequency threshold can be 2% of the switching frequency of the switches in the secondary-side circuit 4 at the third time t3.

[0075] When the secondary controller 52 sends the target period value to the primary controller 51, it means that the period values ​​of the primary and secondary driving carriers have changed. As the overall operating conditions of the isolated converter 1 change, such as when the load connected to the isolated converter 1 changes, the switching frequency of the isolated converter 1 will also be updated accordingly. Therefore, after the secondary controller 52 sends the target period value to the primary controller 51, the secondary controller updates the period of the secondary driving carrier to the target period value when the secondary driving carrier reaches its peak value at the fourth time t4. The primary controller 51 updates the period of the primary driving carrier to the target period value again after the fourth time t4 when the primary driving carrier reaches its peak value, that is, at the first sub-time t41.

[0076] In one embodiment, when the driving frequency of the isolated converter 1 is fixed, that is, when the isolated converter 1 operates at a fixed frequency, the secondary-side controller 52 sends the fifth secondary-side count value of the secondary-side driving carrier at the fifth time to the primary-side controller 51. The primary-side controller 51 receives the fifth secondary-side count value of the secondary-side driving carrier at the fifth time and updates the sixth primary-side count value of the primary-side driving carrier at the sixth time to the remainder of the sum of the fifth secondary-side count value of the secondary-side driving carrier at the fifth time plus the fixed delay divided by the period of the primary-side driving carrier, thereby realizing the synchronization of the primary-side driving carrier and the secondary-side driving carrier.

[0077] For another embodiment where the driving frequency of the isolated converter 1 is fixed, please refer to [link to embodiment]. Figure 7 and cooperate Figure 1 ,in Figure 7 for Figure 1 The diagram shows the control diagram of the primary-side controller in the fourth embodiment of the isolated converter. In this embodiment, the driving frequency of the isolated converter 1 is fixed, that is, the isolated converter 1 operates at a fixed frequency. As shown in the figure, the primary-side controller 51 receives information on the secondary-side driving carrier transmitted by the secondary-side controller 52 via the second communication channel 62. The information on the secondary-side driving carrier includes the seventh secondary-side count value of the secondary-side driving carrier at the seventh time. The primary-side controller 51 includes a subtractor 511, a regulator 512, a limiter 513, an integrator 514, and an adder 515. Subtractor 511 subtracts the seventh secondary-side count value of the secondary-side drive carrier at the seventh time from the seventh primary-side count value of the primary-side drive carrier at the seventh time to obtain a difference. Regulator 512 adjusts this difference, limiter 513 further limits it, integrator 514 integrates the preset 100MHz time signal, and adder 515 adds the limited difference to the integrated 100MHz time signal to correct the period of the primary-side drive carrier at the eighth time. In other words, the primary-side controller 51 compares the received seventh secondary-side count value of the secondary-side drive carrier at the seventh time with the seventh primary-side count value of the primary-side drive carrier at the seventh time and corrects the period of the primary-side drive carrier to achieve synchronization between the primary-side drive carrier and the secondary-side drive carrier.

[0078] Please see Figure 8 , it is Figure 1The flowchart illustrates the control method for the isolated converter. First, step S1 is executed: the primary-side controller is set up, sampling the primary-side circuit to generate a primary-side sampling signal. The primary-side controller provides a primary-side drive carrier and generates a primary-side drive signal based on the primary-side drive carrier to control the primary-side circuit. Next, step S2 is executed: the secondary-side controller is set up, providing a secondary-side drive carrier and generating a secondary-side drive signal based on the secondary-side drive carrier to control the secondary-side circuit. Next, step S3 is executed: a first communication channel is set up between the primary-side controller and the secondary-side controller to transmit the primary-side sampling signal to the secondary-side controller. Next, step S4 is executed: a second communication channel is set up between the primary-side controller and the secondary-side controller to transmit information from the secondary-side drive carrier to the primary-side controller or vice versa, thereby achieving synchronization between the primary-side and secondary-side drive carriers.

[0079] Please see Figure 9 , it is Figure 1 The waveforms of the primary and secondary drive signals of the isolated converter are shown. The periods of the primary and secondary drive signals of the isolated converter 1 in this invention are 25µs. As shown in the figure, the synchronization error between the primary and secondary drive signals of the isolated converter 1 in this invention is within 10ns. Therefore, the primary and secondary drive signals of the isolated converter can be controlled at the same frequency. Furthermore, due to the high synchronization accuracy, it does not affect the control, and it can reduce switching losses and improve efficiency.

[0080] In summary, the isolated converter of this invention includes two communication channels. The first communication channel transmits the primary-side sampling signal provided by the primary-side controller to the secondary-side controller. The second communication channel transmits information from the secondary-side drive carrier provided by the secondary-side controller to the primary-side controller, or vice versa, to achieve synchronization between the primary-side and secondary-side drive carriers. Therefore, the isolated converter of this invention eliminates the need for separate communication channels between the primary-side controller and the secondary-side circuit, thereby reducing the cost of the isolated converter and improving system anti-interference and scalability. Furthermore, the isolated converter can achieve synchronous frequency control of the primary-side and secondary-side drive signals, and due to its high synchronization accuracy, it does not affect the control, reducing switching losses and improving efficiency.

Claims

1. An isolated converter, comprising: A primary-side circuit includes a first port and a second port; A side circuit; A transformer is connected between the primary circuit and the secondary circuit to isolate the primary circuit and the secondary circuit from each other, wherein the second port of the primary circuit is connected to a primary winding of the transformer. A primary-side controller is connected to the primary-side circuit, samples the primary-side circuit to generate a primary-side sampling signal, the primary-side controller provides a primary-side drive carrier, and generates a primary-side drive signal based on the primary-side drive carrier to control the primary-side circuit. A secondary-side controller is connected to the secondary-side circuit. The secondary-side controller provides a secondary-side drive carrier and generates a secondary-side drive signal based on the secondary-side drive carrier to control the secondary-side circuit. A first communication channel is connected between the primary-side controller and the secondary-side controller to transmit the primary-side sampling signal to the secondary-side controller; as well as A second communication channel is connected between the primary-side controller and the secondary-side controller to transmit information on the secondary-side drive carrier to the primary-side controller or to transmit information on the primary-side drive carrier to the secondary-side controller, so as to achieve synchronization between the primary-side drive carrier and the secondary-side drive carrier.

2. The isolated converter as claimed in claim 1, wherein the second communication channel transmits information on the secondary-side drive carrier to the primary-side controller.

3. The isolated converter as claimed in claim 2, wherein the primary-side sampled signal includes the voltage of the first port.

4. The isolated converter as described in claim 2, wherein, At a first moment, the primary-side controller records a first primary-side count value of the primary-side driving carrier at the first moment, and the secondary-side controller records a first secondary-side count value of the secondary-side driving carrier at the first moment. The secondary-side controller sends the first secondary-side count value of the secondary-side driving carrier at the first moment to the primary-side controller. At a second moment, the primary-side controller receives the first secondary-side count value of the secondary-side driving carrier at the first moment, subtracts the first primary-side count value of the primary-side driving carrier at the first moment from the first secondary-side count value of the secondary-side driving carrier at the first moment, adds the second primary-side count value of the primary-side driving carrier at the second moment, and divides the result by a current primary-side period of the primary-side driving carrier, and uses the remainder as a target value.

5. The isolated converter as claimed in claim 4, wherein when the target value is within a first peak value range of the peak value of the primary-side driving carrier, the primary-side controller abandons updating the second primary-side count value of the primary-side driving carrier at the second time to the target value; otherwise, the primary-side controller updates the second primary-side count value of the primary-side driving carrier at the second time to the target value.

6. The isolated converter as described in claim 2, wherein the primary-side controller provides a primary-side communication carrier, the secondary-side controller provides a secondary-side communication carrier, the primary-side communication carrier and the secondary-side communication carrier are synchronized, a third time and a fourth time are determined based on the primary-side communication carrier and the secondary-side communication carrier, the secondary-side controller subtracts the third time from the fourth time and adds a third secondary-side count value of the secondary-side driving carrier at the third time, then divides by a current secondary-side period of the secondary-side driving carrier and takes the remainder to obtain a fourth secondary-side count value of the secondary-side driving carrier at the fourth time, wherein the third time is a preset time when the secondary-side controller sends a first update period to the primary-side controller, and the fourth time is a preset time when the primary-side controller sets a current primary-side period of the primary-side driving carrier to the first update period, and simultaneously the secondary-side controller sets the current secondary-side period of the secondary-side driving carrier to the first update period.

7. The isolated converter as claimed in claim 6, wherein when the fourth secondary-side count value of the secondary-side driving carrier at the fourth time point is within a second peak value range of the peak value of the secondary-side driving carrier, the first update period is a third secondary-side period of the secondary-side driving carrier at the third time point; otherwise, the first update period is a target period value.

8. The isolated converter as claimed in claim 7, wherein when the fourth secondary-side count value of the secondary-side driving carrier at the fourth time point is within a second peak value range of the peak value of the secondary-side driving carrier and the switching frequency change is greater than a frequency threshold, the secondary-side controller sends the third secondary-side period of the secondary-side driving carrier at the third time point to the primary-side controller; otherwise, the secondary-side controller sends the target period value to the primary-side controller.

9. The isolated converter as claimed in claim 8, wherein the frequency of the secondary-side drive carrier is an integer multiple of the frequency of the secondary-side communication carrier.

10. The isolated converter as described in claim 7 or 8, wherein after the secondary-side controller sends the target period value to the primary-side controller, the secondary-side controller updates the period of the secondary-side driving carrier to the target period value after the fourth time when the secondary-side driving carrier reaches its peak value, and the primary-side controller updates the period of the primary-side driving carrier to the target period value after the fourth time when the primary-side driving carrier reaches its peak value.

11. The isolated converter as claimed in claim 2, wherein the isolated converter operates at a fixed frequency, and at a fifth time, the secondary-side controller sends a fifth secondary-side count value of the secondary-side driving carrier at the fifth time to the primary-side controller; at a sixth time, the primary-side controller receives the fifth secondary-side count value of the secondary-side driving carrier at the fifth time, and updates the sixth primary-side count value of the primary-side driving carrier at the sixth time to the remainder of the sum of the fifth secondary-side count value of the secondary-side driving carrier at the fifth time plus a fixed delay divided by the period of the primary-side driving carrier.

12. The isolated converter as claimed in claim 2, wherein the isolated converter operates at a fixed frequency, and at a seventh time, the secondary-side controller sends a seventh secondary-side count value of the secondary-side driving carrier at the seventh time to the primary-side controller, and at an eighth time, the primary-side controller compares the received seventh secondary-side count value of the secondary-side driving carrier at the seventh time with a seventh primary-side count value of the primary-side driving carrier at the seventh time and corrects the period of the primary-side driving carrier.

13. A control method applied to an isolation transformer, the isolation transformer comprising a primary circuit, a secondary circuit, and a transformer, the primary circuit comprising a first port and a second port, the transformer being connected between the primary circuit and the secondary circuit to isolate the primary circuit from the secondary circuit, the second port of the primary circuit being connected to a primary winding of the transformer, wherein the control method comprises: Step (a) Set up a primary-side controller, sample the primary-side circuit to generate a primary-side sampling signal, the primary-side controller provides a primary-side drive carrier, and generates a primary-side drive signal according to the primary-side drive carrier to control the primary-side circuit. Step (b) sets up a secondary side controller that provides a secondary side drive carrier and generates a secondary side drive signal based on the secondary side drive carrier to control the secondary side circuit; Step (c) Set up a first communication channel between the primary-side controller and the secondary-side controller to transmit the primary-side sampling signal to the secondary-side controller; as well as Step (d) sets up a second communication channel between the primary side controller and the secondary side controller to transmit information on the secondary side drive carrier to the primary side controller or to transmit information on the primary side drive carrier to the secondary side controller, so as to achieve synchronization between the primary side drive carrier and the secondary side drive carrier.

14. The control method of claim 13, wherein the second communication channel transmits the information on the secondary-side drive carrier to the primary-side controller.

15. The control method of claim 14, wherein the primary-side sampling signal includes the voltage of the first port.

16. The control method of claim 14, wherein step (d) further comprises: Step (d1) In a first time moment, the primary-side controller records a first primary-side count value of the primary-side driving carrier at that first time moment, the secondary-side controller records a first secondary-side count value of the secondary-side driving carrier at that first time moment, and the secondary-side controller sends the first secondary-side count value of the secondary-side driving carrier at that first time moment to the primary-side controller; and In step (d2), at a second time point, the primary-side controller receives the first secondary-side count value of the secondary-side driving carrier at the first time point, subtracts the first primary-side count value of the primary-side driving carrier at the first time point from the first secondary-side count value of the secondary-side driving carrier at the first time point, adds the second primary-side count value of the primary-side driving carrier at the second time point, and divides the result by the current primary-side period of the primary-side driving carrier as a target value.

17. The control method of claim 16, wherein step (d2) further comprises: Step (d21) confirms whether the target value is within a first peak range of the peak value of the primary-side driving carrier; Step (d22): If it is confirmed that the target value is within the first peak value range of the peak value of the primary-side driving carrier, then the primary-side controller abandons updating the second primary-side count value of the primary-side driving carrier at the second time moment to the target value; and If step (d22) confirms that the target value is not within the first peak range of the peak value of the primary side driving carrier, the primary side controller updates the second primary side count value of the primary side driving carrier at the second time moment to the target value.

18. The control method of claim 14, wherein step (d) further comprises: Step (d3): The primary-side controller provides a primary-side communication carrier, and the secondary-side controller provides a secondary-side communication carrier; the primary-side communication carrier and the secondary-side communication carrier are synchronized; and Step (d4) determines a third time and a fourth time based on the primary-side communication carrier and the secondary-side communication carrier. The secondary-side controller subtracts the third time from the fourth time, adds a third secondary-side count value of the secondary-side driving carrier at the third time, divides it by a current secondary-side period of the secondary-side driving carrier, and takes the remainder to obtain a fourth secondary-side count value of the secondary-side driving carrier at the fourth time. The third time is a preset time when the secondary-side controller sends a first update period to the primary-side controller. The fourth time is a preset time when the primary-side controller sets a current primary-side period of the primary-side driving carrier to the first update period, and the secondary-side controller sets the current secondary-side period of the secondary-side driving carrier to the first update period.

19. The control method of claim 18, wherein step (d4) further comprises: Step (d41) confirms whether the fourth secondary side count value of the secondary side driving carrier at the fourth time point is within a second peak range of the peak value of the secondary side driving carrier; Step (d42): When it is confirmed that the fourth sub-side count value of the sub-side driving carrier at the fourth time point is within the range of the second peak value of the peak value of the sub-side driving carrier, the first update period is a third sub-side period of the sub-side driving carrier at the third time point. as well as Step (d42): When it is confirmed that the fourth secondary side count value of the secondary side driving carrier at the fourth time point is not within the range of the second peak value of the peak value of the secondary side driving carrier, the first update period is a target period value.

20. The control method of claim 19, wherein the frequency of the secondary driving carrier is an integer multiple of the frequency of the secondary communication carrier.

21. The control method as described in claim 18 or 19, wherein after the secondary-side controller sends the target period value to the primary-side controller, the secondary-side controller updates the period of the secondary-side driving carrier to the target period value after the fourth time when the secondary-side driving carrier reaches its peak value, and the primary-side controller updates the period of the primary-side driving carrier to the target period value after the fourth time when the primary-side driving carrier reaches its peak value.

22. The control method of claim 14, wherein the isolated converter operates at a fixed frequency, and step (d) further comprises: In step (d5), at a fifth time point, the secondary-side controller sends a fifth secondary-side count value of the secondary-side drive carrier at that fifth time point to the primary-side controller; and In step (d6), at a sixth time, the primary-side controller receives the fifth secondary-side count value of the secondary-side driving carrier at the fifth time, and updates the sixth primary-side count value of the primary-side driving carrier at the sixth time to the remainder of the sum of the fifth secondary-side count value of the secondary-side driving carrier at the fifth time plus a fixed delay divided by the period of the primary-side driving carrier.

23. The control method of claim 14, wherein the isolated converter operates at a fixed frequency, and step (d) further comprises: Step (d7) at a seventh time, the secondary-side controller sends a seventh secondary-side count value of the secondary-side drive carrier at that seventh time to the primary-side controller; and In step (d8), at an eighth time, the primary-side controller compares the seventh secondary-side count value of the secondary-side driving carrier received at the seventh time with the seventh primary-side count value of the primary-side driving carrier at the seventh time and corrects the period of the primary-side driving carrier.

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