Power converter and method of controlling the same

Abstract

The present application provides a power converter, which includes a plurality of power units and a plurality of slave controllers. Each power unit includes an input capacitor, and input terminals of all the power units are connected in series with each other, and output terminals of all the power units are connected in parallel with each other. The plurality of slave controllers are electrically connected to the plurality of power units respectively, and each slave controller is used to control the operation of a switching device in a corresponding power unit. Each slave controller is used to receive a voltage of an input capacitor of a corresponding power unit, an input reference voltage and an output voltage of the power converter, and in any power unit and the corresponding slave controller, when an input difference between the input reference voltage and the voltage of the input capacitor is less than a first set value, the slave controller controls the operating frequency of the switching device in the corresponding power unit to jump to a preset frequency.

Description

Technical Field

[0001] This case concerns power converters, and more particularly a power converter and its control method. Background Technology

[0002] In high-voltage DC / DC converter applications, ISOP (input-series-output-parallel) converters are commonly used. An ISOP converter consists of multiple DC / DC modules, with their inputs connected in series and their outputs connected in parallel. The challenge in using ISOP converters lies in achieving equal input voltage control among the multiple DC / DC modules.

[0003] ISOP converters utilize the system's power loop to regulate the power of each DC / DC module, thereby achieving input voltage equalization. When the system operates under heavy load, the power loop has strong regulation capabilities, making it easy to achieve input voltage equalization; however, when the system operates under light load, the power loop's regulation capabilities are limited, making it difficult to achieve input voltage equalization.

[0004] Furthermore, to improve converter efficiency, DC / DC modules often employ LLC resonant topology. When the converter operates under heavy load, DC / DC modules using LLC resonant topology operate in frequency modulation mode. However, when the system operates under light load, the DC / DC module operates in burst mode. In this case, the parasitic parameters of the DC / DC module itself cannot be ignored, leading to oscillations in the gain curve, resulting in non-monotonicity and control instability.

[0005] Therefore, when the converter switches between light load and heavy load conditions, it will encounter two difficulties: (1) it is difficult to achieve input voltage equalization by adjusting the power loop under light load; and (2) switching between frequency modulation mode and hiccup mode will bring instability to the converter. Furthermore, when the operating conditions are switched, if any DC / DC module experiences input overvoltage, it will damage the device and cause the converter to fail.

[0006] Therefore, developing a power converter and its control method that can improve upon the existing technologies is an urgent need at present. Summary of the Invention

[0007] The purpose of this invention is to provide a power converter and its control method, which can adjust the operating frequency of any power unit of the power converter in a timely manner when the voltage of the input capacitor is too high, so that the voltage of the input capacitor is reduced rapidly, thereby avoiding damage to the device and affecting the operation of the power converter due to input capacitor overvoltage.

[0008] To achieve the above objectives, this invention provides a power converter comprising multiple power units and multiple slave controllers. Each power unit includes an input capacitor, and the input terminals of all power units are connected in series, while the output terminals of all power units are connected in parallel. Multiple slave controllers are electrically connected to the multiple power units, and each slave controller controls the operation of the switching devices in its corresponding power unit. Each slave controller receives the voltage of the input capacitor of the corresponding power unit, an input reference voltage, and the output voltage of the power converter. In any power unit and its corresponding slave controller, when the input difference between the input reference voltage and the voltage of the input capacitor is less than a first preset value, the slave controller controls the operating frequency of the switching devices in the corresponding power unit to switch to a preset frequency.

[0009] In some embodiments, each slave controller includes a calculator and a determiner; in any power unit and its corresponding slave controller, the calculator receives the voltage of the input capacitor and an input reference voltage, and compares the input reference voltage with the voltage of the input capacitor to obtain an input difference; the determiner receives the input difference and compares the input difference with a first set value and a second set value, wherein the first set value is less than the second set value.

[0010] In some embodiments, each slave controller further includes a frequency hopping controller; in any power unit and its corresponding slave controller, when the determiner determines that the input difference is less than a first set value, the frequency hopping controller generates a preset frequency based on the output voltage, and the slave controller controls the switching devices in the corresponding power unit to operate at the preset frequency.

[0011] In some embodiments, the frequency hopping controller has multiple preset frequencies corresponding to different output voltages, and the frequency hopping controller generates the corresponding preset frequency according to the actual magnitude of the output voltage.

[0012] In some embodiments, each slave controller further includes a pulse sealing controller; in any power unit and its corresponding slave controller, when the determiner determines that the input difference is greater than a second set value, the pulse sealing controller outputs a pulse sealing command, and the slave controller controls the switching device in the corresponding power unit to stop operating.

[0013] In some embodiments, the power converter further includes an output controller, wherein the output controller is configured to receive an output signal from the power converter and calculate control reference parameters based on the difference between the output signal and an output reference signal.

[0014] In some embodiments, each slave controller further includes a voltage equalization controller and an arithmetic unit; in any power unit and its corresponding slave controller, when the determiner determines that the input difference is greater than a first set value and less than a second set value, the determiner outputs the input difference to the voltage equalization controller, the voltage equalization controller generates a comparison parameter based on the input difference, the arithmetic unit receives the comparison parameter and the control reference parameter, and calculates the specified parameter based on the comparison parameter and the control reference parameter, and the slave controller controls the switching device in the corresponding power unit to operate with the specified parameter.

[0015] In some embodiments, when the power converter operates in frequency modulation mode, the comparison parameter, control reference parameter, and specified parameter are the comparison frequency, control reference frequency, and specified frequency, respectively; when the power converter operates in hiccup mode, the comparison parameter, control reference parameter, and specified parameter are the comparison duty cycle, control reference duty cycle, and specified duty cycle, respectively.

[0016] In some embodiments, each slave controller further includes a PWM generator; in any power unit and its corresponding slave controller, the PWM generator is used to generate a control signal according to a preset frequency, a pulse blocking command or a specified parameter, and the control signal is used to control the operation of the switching devices in the corresponding power unit.

[0017] In some embodiments, the power unit includes a full-bridge DC / DC converter or a dual active-bridge bidirectional DC / DC converter.

[0018] To achieve the above objectives, this application also provides a control method for controlling a power converter. The power converter includes multiple power units and multiple slave controllers. Each power unit includes an input capacitor. The input terminals of the multiple power units are connected in series, and the output terminals of the multiple power units are connected in parallel. The multiple slave controllers are electrically connected to the multiple power units, and each slave controller is used to control the operation of the switching devices in its corresponding power unit. For any power unit, the control method includes: receiving the voltage of the input capacitor of the power unit, an input reference voltage, and the output voltage of the power converter; and when the input difference between the input reference voltage and the voltage of the input capacitor is less than a first set value, controlling the operating frequency of the switching devices in the power unit to jump to a preset frequency.

[0019] In some embodiments, for any power unit, the control method further includes: using a calculator to compare an input reference voltage with the voltage of an input capacitor to obtain an input difference; and using a determiner to compare the input difference with a first set value and a second set value, wherein the first set value is less than the second set value.

[0020] In some embodiments, for any power unit, the control method further includes: when the determiner determines that the input difference is less than a first set value, using a frequency hopping controller to generate a preset frequency based on the output voltage, and controlling the switching device in the corresponding power unit to operate at the preset frequency.

[0021] In some embodiments, the frequency hopping controller has multiple preset frequencies corresponding to different output voltages, and the frequency hopping controller generates the corresponding preset frequency according to the actual magnitude of the output voltage.

[0022] In some embodiments, for any power unit, the control method further includes: when the determiner determines that the input difference is greater than a second set value, using the pulse sealing controller to output a pulse sealing command to control the switching devices in the corresponding power unit to stop operating.

[0023] In some embodiments, the control method further includes: using an output controller to calculate control reference parameters based on the difference between the output signal of the power converter and the output reference signal.

[0024] In some embodiments, for any power unit, the control method further includes: when the determiner determines that the input difference is greater than a first set value and less than a second set value, outputting the input difference to the voltage equalization controller; using the voltage equalization controller to generate a comparison parameter based on the input difference; and using an arithmetic unit to calculate a specified parameter based on the comparison parameter and the control reference parameter, and controlling the switching device in the corresponding power unit to operate with the specified parameter.

[0025] In some embodiments, when the power converter operates in frequency modulation mode, the comparison parameter, control reference parameter, and specified parameter are the comparison frequency, control reference frequency, and specified frequency, respectively; when the power converter operates in hiccup mode, the comparison parameter, control reference parameter, and specified parameter are the comparison duty cycle, control reference duty cycle, and specified duty cycle, respectively.

[0026] In some embodiments, for any power unit, the control method further includes: using a PWM generator to generate a control signal according to a preset frequency, a pulse blocking command, or specified parameters, and controlling the operation of the switching devices in the corresponding power unit according to the control signal. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the architecture of the power converter in a preferred embodiment of this invention.

[0028] Figure 2 An example is shown of the output controller of a power converter and the slave controller corresponding to one of the power units.

[0029] Figure 3 This is a schematic diagram illustrating the operation of the hiccup mode.

[0030] Figure 4 This is a schematic diagram of the circuit structure of a dual active bridge bidirectional DC / DC converter.

[0031] Figure 5 This is a schematic diagram of the circuit structure of a full-bridge DC / DC converter.

[0032] Figure 6 and Figure 7 This is a schematic diagram illustrating the steps of the control method in a preferred embodiment of this case.

[0033] The reference numerals in the attached figures are explained as follows:

[0034] 1: Power Converter

[0035] 10: Power Unit

[0036] 20: From the controller

[0037] Cin: Input capacitance

[0038] Vin: Voltage of the input capacitor

[0039] Vinref: Input reference voltage

[0040] ΔVin: Input difference

[0041] V1: First setting value

[0042] V2: Second setting value

[0043] fsi: Preset frequency

[0044] 211: Calculator

[0045] 212: Decision Maker

[0046] 213: Frequency Hopping Controller

[0047] Vo: Output voltage

[0048] 214: Pulse sealing controller

[0049] 30: Main Controller

[0050] 31: Output Controller

[0051] Voref: Output reference voltage

[0052] 215: Voltage Equalization Controller

[0053] 216: Arithmetic Unit

[0054] Δfsi: Comparison frequency

[0055] fs: Controls the reference frequency

[0056] Ton, Toff: Duration

[0057] Ts: Switching cycle

[0058] Tburst: Work cycle

[0059] Deff: Equivalent duty cycle

[0060] ΔDei: Duty cycle

[0061] De: Control reference duty cycle

[0062] 217: PWM Generator

[0063] Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8: Switches

[0064] L: Inductance

[0065] T: Transformer

[0066] Co: Capacitor

[0067] D1, D2: Diodes

[0068] S1, S2, S3, S4, S5, S6, S7, S8, S9, S10: Steps Detailed Implementation

[0069] Some typical embodiments that embody 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 illustrations therein are for illustrative purposes only and not intended to limit this invention.

[0070] Figure 1 This is a schematic diagram of the power converter architecture of a preferred embodiment of this invention. Figure 1As shown, the power converter 1 of this invention includes multiple power units 10 and multiple slave controllers 20. Each power unit 10 includes an input capacitor Cin, and the input terminals of all power units 10 are connected in series, while the output terminals of all power units 10 are connected in parallel. Multiple slave controllers 20 are electrically connected to multiple power units 10, that is, each slave controller 20 corresponds to one power unit 10, and each slave controller 20 is used to control the operation of the switching devices in the corresponding power unit 10. Each slave controller 20 receives the voltage Vin of the input capacitor Cin of the corresponding power unit 10, the input reference voltage Vinref, and the output voltage Vo of the power converter 1. In any power unit 10 and its corresponding slave controller 20, when the input difference ΔVin (ΔVin = Vinref - Vin) between the input reference voltage Vinref and the voltage Vin of the input capacitor Cin is less than a first set value V1, the slave controller 20 controls the operating frequency of the switching devices in the corresponding power unit 10 to jump to a preset frequency fsi.

[0071] In some embodiments, the input reference voltage Vinref can be a manually set value or a setting value issued by another external controller.

[0072] Therefore, when the voltage Vin of the input capacitor Cin of any power unit 10 is too high, the voltage Vin of the input capacitor Cin can be quickly reduced by adjusting the operating frequency in time, so that the input capacitors Cin of multiple power units 10 can be equalized, so as to avoid overvoltage of the input capacitor Cin, which would damage the device and affect the operation of the power converter 1.

[0073] Please see Figure 2 , Figure 2 An example is shown of the slave controller 20 corresponding to one of the power units 10 of the power converter 1. For example... Figure 2As shown, each slave controller 20 includes a calculator 211 and a determiner 212. In any power unit 10 and its corresponding slave controller 20, the calculator 211 receives the voltage Vin of the input capacitor Cin and the input reference voltage Vinref, and calculates the input difference ΔVin by comparing the input reference voltage Vinref with the voltage Vin of the input capacitor. The determiner 212 receives the input difference ΔVin and compares it with a first set value V1 and a second set value V2, wherein the first set value V1 is less than the second set value V2. In some embodiments, the first set value V1 can be a negative number of the second set value V2, i.e., V1 = -V2. Based on the relationship between the input difference ΔVin and the first set value V1 and the second set value V2, the slave controller 20 performs corresponding control on the power unit 10 (which may be, for example, but not limited to, switching control via the switch shown in the figure) to achieve voltage equalization between the input capacitors and prevent input overvoltage or undervoltage, as explained in detail below.

[0074] In some embodiments, each slave controller 20 further includes a frequency hopping controller 213. In any power unit 10 and its corresponding slave controller 20, when the determiner 212 determines that the input difference ΔVin is less than a first set value V1, the frequency hopping controller 213 generates a preset frequency fsi based on the output voltage Vo, and the slave controller 20 controls the switching devices in the corresponding power unit 10 to operate at the preset frequency fsi. In some embodiments, the frequency hopping controller 213 has multiple preset frequencies fsi corresponding to different output voltages Vo, and the frequency hopping controller 213 generates the corresponding preset frequency fsi based on the actual magnitude of the output voltage Vo. In this embodiment, the multiple preset frequencies fsi can be different values; for example, the higher the output voltage, the smaller its corresponding preset frequency fsi. In other embodiments, the multiple preset frequencies fsi can be the same value. Since the input difference ΔVin is less than the first set value V1, indicating that the input capacitor voltage Vin is too high, the control switching device operates at a relatively low preset frequency fsi (e.g., 80–400 kHz) based on the output voltage Vo. This rapidly reduces the input capacitor voltage Vin, thus preventing input capacitor overvoltage. Input voltage equalization control is then performed after the input capacitor voltage Vin returns to the normal range.

[0075] In some embodiments, each slave controller 20 further includes a pulse-sealing controller 214. In any power unit 10 and its corresponding slave controller 20, when the determiner 212 determines that the input difference ΔVin is greater than a second set value V2, the pulse-sealing controller 214 outputs a pulse-sealing command. According to the pulse-sealing command, the slave controller 20 controls the switching devices in the corresponding power unit 10 to stop operating. Since an input difference ΔVin greater than the second set value V2 indicates that the voltage Vin of the input capacitor Cin is too low, the pulse-sealing command is used to block the drive to control the switching devices to stop operating, thereby preventing input undervoltage. Input voltage equalization control is then performed after the voltage Vin of the input capacitor Cin returns to the normal range.

[0076] In some embodiments, the power converter 1 further includes an output controller 31, which is used to receive an output signal, which may be an output voltage Vo or an output current. The output controller 31 calculates control reference parameters based on the difference between an output reference signal and the output signal, wherein the output reference signal may be an output reference voltage Voef or an output reference current. Figure 2 The example illustrates the case where the output signal and the output reference signal are the output voltage Vo and the output reference voltage Voref, respectively. When the output controller 31 receives the output voltage Vo, it calculates the control reference parameters based on the difference between the output reference voltage Voref and the output voltage Vo. The power converter 1 also includes a main controller 30, which communicates with multiple slave controllers 20. The output controller 31 may be part of the main controller 30, but is not limited thereto. Furthermore, each slave controller 20 also includes a voltage equalization controller 215 and an arithmetic unit 216. In any power unit 10 and its corresponding slave controller 20, when the determiner 212 determines that the input difference ΔVin is greater than a first set value V1 and less than a second set value V2, the determiner 212 outputs the input difference ΔVin to the voltage equalization controller 215, which generates comparison parameters based on the input difference ΔVin. The arithmetic unit 216 receives comparison parameters and control reference parameters, and calculates specified parameters based on these parameters. The controller 20 then controls the switching devices in the corresponding power unit 10 to operate according to these specified parameters. Since the input difference ΔVin is greater than the first set value V1 and less than the second set value V2, indicating that the voltage Vin of the input capacitor Cin is within the normal range, the corresponding switching devices are controlled to operate according to the specified parameters to enter input voltage equalization control. The type of specified parameters varies depending on the operating mode of the power converter 1, as detailed below.

[0077] The power unit 10 in this case is an isolated DC / DC converter, typically employing an LLC topology. When the load is heavy, the power converter 1 operates in frequency modulation mode. Correspondingly, the aforementioned comparison parameter, control reference parameter, and specified parameter are the comparison frequency Δfsi, control reference frequency fs, and specified frequency, respectively. When the load lightens, the switching frequency of the switching devices in the power unit 10 increases until it reaches the upper limit that the switching devices can withstand, at which point frequency modulation control of the power unit 10 ceases. At this time, the power converter 1 switches to Burst Mode, alternating between periods of operation and periods of inactivity, such as... Figure 3 As shown, Ton is the duration of operation, Toff is the duration of inactivity, Ts is the switching cycle during operation, Tburst is the operating cycle of the hiccup mode, and the equivalent duty cycle Deff = Ton / (Ton + Toff). Correspondingly, when the power converter 1 operates in hiccup mode, the aforementioned comparison parameter, control reference parameter, and specified parameter are the comparison duty cycle ΔDei, the control reference duty cycle De, and the specified duty cycle, respectively.

[0078] Furthermore, in some embodiments, such as Figure 2 As shown, each slave controller 20 also includes a PWM (pulse width modulation) generator 217. In any power unit 10 and its corresponding slave controller 20, corresponding to the relationship between the input difference ΔVin and the first set value V1 and the second set value V2, the PWM generator 217 can generate a control signal according to a preset frequency fsi, a pulse blocking command, or specified parameters. The control signal is used to control the operation of the switching devices in the corresponding power unit 10.

[0079] Additionally, the power unit 10 may include, for example, Figure 4 The dual active bridge bidirectional DC / DC converter shown Figure 5 The example shown is a full-bridge DC / DC converter, but it is not limited to this. For example... Figure 4As shown, the dual active bridge bidirectional DC / DC converter includes a primary circuit, an inductor L, a transformer T, a secondary circuit, and an output capacitor Co. The primary circuit includes switching devices Q1 to Q4. Switching devices Q1 and Q2 are connected in series and then in parallel with the input capacitor Cin. Switching devices Q3 and Q4 are connected in series and then in parallel with the input capacitor Cin. The inductor L is connected in series with the primary winding of the transformer T and then between the connection points of switching devices Q1 and Q2 and the connection points of switching devices Q3 and Q4. The secondary circuit includes switching devices Q5 to Q8. Switching devices Q5 and Q6 are connected in series and then in parallel with the output capacitor Co. Switching devices Q7 and Q8 are connected in series and then in parallel with the output capacitor Co. The secondary winding of the transformer T is connected between the connection points of switching devices Q5 and Q6 and the connection points of switching devices Q7 and Q8. The controller 20 is used to control the operation of switching devices Q1 to Q8. Figure 5 As shown, the full-bridge DC / DC converter includes a primary circuit, a transformer, a secondary circuit, an inductor L, and an output capacitor Co. The primary circuit includes switching devices Q1 to Q4. Switching devices Q1 and Q2 are connected in series and then in parallel with the input capacitor Cin. Switching devices Q3 and Q4 are connected in series and then in parallel with the input capacitor Cin. The primary winding of the transformer is connected in series between the connection points of switching devices Q1 and Q2 and the connection points of switching devices Q3 and Q4. The secondary circuit includes diodes D1 and D2. The anode of diode D1 is connected to the first terminal of the secondary winding of the transformer, the anode of diode D2 is connected to the second terminal of the secondary winding of the transformer, and the cathode of diode D2 is connected to the cathode of diode D1. Inductor L is connected between the cathode of diode D1 and one end of the output capacitor Co. The center point of the secondary winding of the transformer is connected to the other end of the output capacitor Co. The controller 20 is used to control the operation of switching devices Q1 to Q4.

[0080] Figure 6 This is a schematic diagram illustrating the steps of a control method according to a preferred embodiment of this invention. This control method is used to control the aforementioned power converter 1. For any power unit 10, as follows: Figure 6 As shown, the control method includes steps S1 and S2. In step S1, the voltage Vin of the input capacitor Cin of the power unit 10, the input reference voltage Vinref, and the output voltage Vo of the power converter 1 are received. In step S2, when the input difference ΔVin between the input reference voltage Vinref and the voltage Vin of the input capacitor Cin is less than a first set value V1, the operating frequency of the switching device in the corresponding power unit 10 is controlled to jump to a preset frequency fsi. Therefore, when the voltage Vin of the input capacitor of any power unit 10 is too high, the voltage Vin of the input capacitor Cin can be rapidly reduced by adjusting the operating frequency in time, thereby avoiding input overvoltage that could damage the device and affect system operation.

[0081] In some embodiments, the control method further includes Figure 7 The steps are shown. (As indicated) Figure 7 As shown, firstly, in step S3, the input reference voltage Vinref is compared with the voltage Vin of the input capacitor using calculator 211 to obtain the input difference ΔVin. Next, in step S4, the input difference ΔVin is compared with the first set value V1 and the second set value V2 using determiner 212. Then, based on the relationship between the input difference ΔVin and the first and second set values ​​V1 and V2, corresponding control is applied to the power unit 10 to achieve input voltage equalization and prevent input overvoltage or undervoltage, as explained below.

[0082] When the determiner 212 determines that the input difference ΔVin is less than the first set value V1, step S5 is executed: the frequency hopping controller 213 generates a preset frequency fsi based on the output voltage Vo, and controls the switching device in the corresponding power unit 10 to operate at the preset frequency fsi.

[0083] When the arbiter 212 determines that the input difference ΔVin is greater than the second set value V2, step S6 is executed: the pulse sealing controller 214 outputs a pulse sealing command, and controls the switching device in the corresponding power unit 10 to stop operating according to the pulse sealing command.

[0084] When the determiner 212 determines that the input difference ΔVin is greater than the first set value V1 and less than the second set value V2, step S7 is executed: the input difference ΔVin is output to the voltage equalization controller 215. Next, in step S8, the output controller 31 calculates the control reference parameters based on the difference between the output reference voltage Voef and the output voltage Vo, and the voltage equalization controller 215 generates comparison parameters based on the input difference ΔVin. Then, in step S9, the arithmetic unit 216 calculates the comparison parameters and the control reference parameters to obtain specified parameters, and controls the switching devices in the corresponding power unit 10 to operate with the specified parameters.

[0085] In some embodiments, such as Figure 7 As shown, the control method also includes step S10: using the PWM generator 217 to generate a control signal according to a preset frequency fsi, a pulse blocking command or specified parameters, and controlling the switching device in the corresponding power unit 10 to operate according to the control signal.

[0086] In summary, this invention provides a power converter and its control method, which controls the power units accordingly based on the relationship between the input difference and the set value to achieve input voltage equalization and prevent input overvoltage or undervoltage. Specifically, when the voltage of the input capacitor of any power unit of the power converter is too high, the operating frequency can be adjusted in time to rapidly reduce the voltage of the input capacitor, thereby avoiding overvoltage damage to the device and affecting the operation of the power converter. Furthermore, when the voltage of the input capacitor of any power unit is too low, the drive can be blocked to control the switching device to stop operating, thereby preventing input undervoltage. Moreover, when the voltage of the input capacitor of any power unit is within the normal range, the switching device is controlled to operate with specified parameters to achieve input voltage equalization control. Furthermore, since the type of specified parameters varies depending on the operating mode of the power converter, input voltage equalization control can be achieved under both light and heavy load conditions.

[0087] It should be noted that the above are merely preferred embodiments for illustrating this case, and this case is not limited to the described embodiments. The scope of this case is determined by the appended claims. Furthermore, this case can be modified in various ways by those skilled in the art, but all modifications shall not depart from the protection sought by the appended claims.

Claims

1. A power converter, comprising: Multiple power units, each including an input capacitor, wherein the input terminals of the multiple power units are connected in series and the output terminals of the multiple power units are connected in parallel; and Multiple slave controllers are electrically connected to the multiple power units. Each slave controller controls the operation of the switching devices in its corresponding power unit. Each slave controller receives the voltage of the input capacitor, the input reference voltage, and the output voltage of the power converter for its corresponding power unit. In any power unit and its corresponding slave controller, when the input difference between the input reference voltage and the voltage of the input capacitor is less than a first set value, the slave controller controls the operating frequency of the switching devices in the corresponding power unit to switch to a preset frequency. Each slave controller further includes a frequency hopping controller; in any power unit and its corresponding slave controller, when the input difference is less than the first set value, the frequency hopping controller generates the preset frequency based on the output voltage, and the slave controller controls the switching devices in the corresponding power unit to operate at the preset frequency. The frequency hopping controller has multiple preset frequencies corresponding to different output voltages. The frequency hopping controller generates the corresponding preset frequency according to the actual magnitude of the output voltage. Each of the slave controllers further includes a pulse sealing controller; in any power unit and the corresponding slave controller, when the input difference is greater than a second set value, the pulse sealing controller outputs a pulse sealing command, and the slave controller controls the switching device in the corresponding power unit to stop operating, wherein the first set value is less than the second set value.

2. The power converter of claim 1, wherein each slave controller includes a calculator and a determiner; in any power unit and the corresponding slave controller, the calculator receives the voltage of the input capacitor and the input reference voltage, and compares the input reference voltage with the voltage of the input capacitor to obtain the input difference; the determiner receives the input difference and compares the input difference with the first set value and the second set value.

3. The power converter according to claim 2 further includes an output controller, wherein the output controller is configured to receive the output signal of the power converter and calculate control reference parameters based on the difference between the output signal and the output reference signal.

4. The power converter according to claim 3, wherein each slave controller further comprises a voltage equalization controller and an arithmetic unit; in any power unit and the corresponding slave controller, when the determiner determines that the input difference is greater than the first set value and less than the second set value, the determiner outputs the input difference to the voltage equalization controller, the voltage equalization controller generates a comparison parameter based on the input difference, the arithmetic unit receives the comparison parameter and the control reference parameter, and calculates a specified parameter based on the comparison parameter and the control reference parameter, and the slave controller controls the switching device in the corresponding power unit to operate with the specified parameter.

5. The power converter according to claim 4, wherein when the power converter operates in frequency modulation mode, the comparison parameter, the control reference parameter, and the specified parameter are respectively the comparison frequency, the control reference frequency, and the specified frequency; and when the power converter operates in hiccup mode, the comparison parameter, the control reference parameter, and the specified parameter are respectively the comparison duty cycle, the control reference duty cycle, and the specified duty cycle.

6. The power converter according to claim 4, wherein each slave controller further comprises a PWM generator; in any power unit and the corresponding slave controller, the PWM generator is used to generate a control signal according to the preset frequency, the pulse blocking command or the specified parameter, the control signal being used to control the operation of the switching device in the corresponding power unit.

7. The power converter of claim 1, wherein the power unit comprises a full-bridge DC / DC converter or a dual active-bridge bidirectional DC / DC converter.

8. A control method for controlling a power converter, wherein the power converter includes a plurality of power units and a plurality of slave controllers; each power unit includes an input capacitor, the input terminals of the plurality of power units are connected in series, and the output terminals of the plurality of power units are connected in parallel; the plurality of slave controllers are electrically connected to the plurality of power units respectively, and each slave controller is used to control the operation of a switching device in the corresponding power unit; for any power unit, the control method includes: The voltage of the input capacitor of the power unit, the input reference voltage, and the output voltage of the power converter are received. When the input difference between the input reference voltage and the voltage of the input capacitor is less than a first set value, the operating frequency of the switching device in the power unit is controlled to jump to a preset frequency. When the input difference is less than the first set value, a frequency hopping controller generates a preset frequency based on the output voltage, and controls the switching device in the corresponding power unit to operate at the preset frequency. The frequency hopping controller has multiple preset frequencies corresponding to different output voltages, and generates the corresponding preset frequency based on the actual magnitude of the output voltage. When the input difference is greater than a second set value, the pulse sealing controller outputs a pulse sealing command to control the switching device in the corresponding power unit to stop operating, wherein the first set value is less than the second set value.

9. The control method according to claim 8, wherein for any of the power units, the control method further comprises: The input difference is obtained by comparing the input reference voltage with the voltage of the input capacitor using a calculator; and The input difference is compared with the first set value and the second set value using a decision maker.

10. The control method according to claim 9, wherein the control method further comprises: The control reference parameters are obtained by calculating the difference between the output signal of the power converter and the output reference signal using the output controller.

11. The control method according to claim 10, wherein for any of the power units, the control method further comprises: When the determiner determines that the input difference is greater than the first set value and less than the second set value, the input difference is output to the pressure equalization controller; The voltage equalization controller generates comparison parameters based on the input difference; and The arithmetic unit calculates the specified parameters based on the comparison parameters and the control reference parameters, and controls the switching devices in the corresponding power unit to operate with the specified parameters.

12. The control method according to claim 11, wherein when the power converter operates in frequency modulation mode, the comparison parameter, the control reference parameter, and the specified parameter are respectively the comparison frequency, the control reference frequency, and the specified frequency; and when the power converter operates in hiccup mode, the comparison parameter, the control reference parameter, and the specified parameter are respectively the comparison duty cycle, the control reference duty cycle, and the specified duty cycle.

13. The control method according to claim 11, wherein for any of the power units, the control method further comprises: A PWM generator is used to generate a control signal based on the preset frequency, the pulse blocking command, or the specified parameters, and the switching device in the corresponding power unit is controlled according to the control signal.

Images