48results about How to "Solve the pressure equalization problem" patented technology

The invention provides a distributed energy consumption device and a module fault bypass control method. The device comprises at least two voltage-sharing energy dissipation modules, at least one one-way conduction module, at least one charging module and at least one isolation switch, wherein each voltage-sharing energy dissipation module comprises an energy storage unit, an energy consumption unit and a bypass switch which are connected in parallel; the energy storage unit comprises an energy storage capacitor and a current limiter which are connected in series; the energy dissipation unit comprises an energy dissipation resistor and a first power semiconductor device which are connected in series; the at least one one-way conduction module comprises at least one second power semiconductor device; the at least one charging module comprises at least one resistor and at least one switch which are connected in parallel; and the at least one isolation switch is connected with the voltage-sharing energy dissipation modules, the one-way conduction module and the charging module in the same direction in series. According to the modular design scheme, the voltage sharing problem of the power device is solved, and the control strategy is simplified; the design scheme that the energy storage capacitor is connected with the current limiter in series to limit the current of the bypass switch is adopted, so that the current impact of the bypass switching on is reduced, and the reliability of the fault bypass is improved.

The invention provides an N-output single-phase N+1-switch-group MMC inverter and a control method of the N-output single-phase N+1-switch-group MMC inverter. The inverter comprises a direct current power source, a capacitor bridge arm, a switch bridge arm and N loads. The capacitor bridge arm is formed by N+1 capacitors in a series connection mode, and the switch bridge arm is formed by N+1 switch groups, a first inductor and a second inductor in a series connection mode. The ith switch group of the switch bridge arm is formed by n power switch units in a series connection mode, wherein the i ranges from 1 to N+1. One end of the kth load is connected to the positive pole of the k+1th capacitor of the capacitor bridge arm, and the other end of the kth load is connected to the upper end of the k+1th switch group of the switch bridge arm, wherein the k ranges from 1 to N-1. One end of the Nth load is connected to the positive pole of the N+1th capacitor of the capacitor bridge arm, and the other end of the Nth load is connected to the lower end of the N+1th switch group of the switch bridge arm. According to the inverter, carrier phase-shifting PWM control is adopted, and N n+1-level alternating voltages can be output.

The invention provides a double-input three-phase nine-switch-block MMC rectifier and a control method thereof. The rectifier comprises two three-phase voltage sources, two sets of three-phase inductors, a first bridge arm, a second bridge arm, a third bridge arm and a rectification load. Each of the first bridge arm, the second bridge arm and the third bridge arm is formed by connecting an upper switch block, a middle switch block, a lower switch block and two inductors in series. Each switch block is formed by connecting N power switch units. The rectifier is controlled through carrier phase-shifting PWM. Two input alternating-current power supplies are converted into alternating-current input of the three-phase 2N+1 level, rectified and overlapped and provide power for the load. The voltage stress borne by each switching tube in each MMC power switch unit is only 1 / N of the voltage of a direct-current power supply, the voltage sharing problem of the switching tubes is well solved, and the double-input three-phase nine-switch-block MMC rectifier is suitable for high-voltage and large-power occasions where two three-phase alternating-current power supplies are input.

The invention provides a 2N+2 switch group MMC AC-AC converter and a control method thereof. The converter includes N inputs / outputs, a first bridge arm, a second bridge arm and a first capacitor; the input of each input / output is an AC input, and the load of each input / output is an inductive load; the first bridge Both the arm and the second bridge arm are composed of N+1 switch groups and 2 inductors in series; each switch group is composed of n power switch units in series; the sum of the AC input and the load is N; the two loads Terminal as output; N>2, n is a positive integer. The converter adopts carrier phase-shift PWM control, and each input AC power is converted into 2n+1 level AC input, which is converted into 2n+1 level AC input by AC-AC to supply power to the inductive load, and the MMC power switch unit The voltage stress of each switching tube is only 1 / n of the DC power supply voltage, which is suitable for high-voltage and high-power applications.

The invention discloses a photovoltaic grid-connected inverter. The photovoltaic grid-connected inverter comprises a photovoltaic array, a plurality of unit bodies, three unit body series branches, an alternating current reactor, a grid-connected switch, unit body controllers and a master controller, wherein the preceding stage of each unit body is respectively connected with the photovoltaic array; the unit body series branches are connected into a power grid after being connected with the alternating current reactor and the grid-connected switch in series; and each unit body comprises one of the unit body controllers. The invention also discloses a photovoltaic grid-connected inverter control method. In the inverter and the control method disclosed by the invention, the unit bodies are connected in series instead of directly connecting power devices in series, so that the problem of voltage-sharing of devices are solved; the power level is high; the limitation of load capacity of power electronic devices is overcome; a unit phase shift wave overlapping technology is adopted, so that an output harmonic wave is small; because of the action of an energy storage battery, when illumination disappears suddenly, a system cannot be off-grid and standby suddenly; and because of adopting a unit body automatic bypass technology, the security of the system is improved.

The invention provides a six-switch-block MMC mixed converter and a control method of the six-switch-block MMC mixed converter. The converter comprises an alternating-current input power source, an alternating-current input inductor, a first direct-current power source, a first direct-current input inductor, a second direct-current power source, a second direct-current input inductor, a first bridge arm, a second bridge arm and a load. The first bridge arm and the second bridge arm are respectively formed by connecting an upper switch block, a middle switch block, a lower switch block, a first bridge arm inductor and a second bridge arm inductor in series. Each switch block is formed by connecting N power switch units in series, wherein N is a positive integer. The converter is controlled by the carrier phase-shifting PWM, the alternating-current input power source is converted into the alternating-current input of the 2N+1 levels, the direct-current input power source is converted into multiple levels which are converted into direct-currents through the converter, and then the direct-currents are output to provide power for the load. The voltage stress borne by each switching tube in an MMC power switch unit is only 1 / N that of the direct-current power voltage, the voltage equalizing problem of the switching tubes is well solved, and the six-switch-block MMC mixed converter and the control method of the six-switch-block MMC mixed converter are suitable for the application of direct access of direct-current high-voltage transmission in distributed generation.

The invention relates to a driving signal timing method of a hybrid clamping type three-level H-bridge inverter. The inverter comprises two bus capacitor banks; the two bus capacitor banks are connected in series; in a driving signal timing process, the inverter is used for outputting pulse width modulation waves; in each modulation wave period, only one bus capacitor bank of the inverter is connected to a load for charging and discharging in a plurality of carrier periods near an output voltage zero crossing point; a charging time and a discharging moment of the same bus capacitor bank are symmetric relative to the zero crossing point on a time axis; a zero crossing point of an output voltage falling section is a first zero crossing point; a zero crossing point of a voltage rising sectionis a second zero crossing point; the moment when the first bus capacitor bank is connected to the load for charging and discharging, and the moment when the second bus capacitor bank is connected tothe load for charging and discharging are located at the first zero crossing point and the second zero crossing point respectively or vice versa; and the total time for the first bus capacitor bank tobe independently connected to the load for charging and discharging is equal to the total time for the second bus capacitor bank to be independently connected to the load for charging and discharging.

The invention relates to a novel high-capacity multi-level hybrid clamping topology and a topological method. The structure is a three-phase four-bridge arm structure; one bridge arm is added based ona conventional hybrid three-phase structure and is specially used for clamping; further, the structure does not need a voltage balancing circuit and an independent DC voltage source, and can realizemidpoint potential balance under all load characteristics; the conventional clamping device is improved, namely, a diode clamping device with a three-phase four-bridge arm topology is transformed intocapacitor clamping; an active switch transistor is added as a clamping device, so that the topology realizes current bidirectional path, and solves a problem of imbalance capacitance and voltage. Thestanding voltage balance problem in power switch in series operation is solved, further, a better way for realizing high voltage energy control based on low withstand voltage power switch is provided.

The invention provides an N input single-phase N+1 switching group MMC rectifier and a control method of the N input single-phase N+1 switching group MMC rectifier. The rectifier comprises N alternating-current inputting power supplies, N alternating-current inductors, a capacitance bridge arm, a switching bridge arm and a rectification load. The capacitance bridge arm is formed by connecting N+1 capacitors in series and the switching bridge arm is formed by connecting N+1 switching groups, a first inductor and a second inductor in series. The ith switching group of the switching bridge arm is formed by connecting n power switching units in series, wherein i is selected between 1 and N+1. The two ends of the kth alternating-current power supply serve as inputting of the kth circuit, wherein k is selected between 1 and N. The N input single-phase N+1 switching group MMC rectifier is controlled through carrier phase-shifting PWM, the N input alternating current power supplies are converted into alternating current inputting of N circuits of n+1 levels and after currents are rectified and overlapped, the load is powered. The voltage stress borne by each switching tube in an MMC power switching unit is only one nth of the voltage of the direct-current power supplies and the problem of voltage sharing of the switching tubes is solved. The N input single-phase N+1 switching group MMC rectifier is applicable to multiple-alternating-current-power-supply-inputting, high-voltage and large-power occasions.

The invention provides an N input single-phase 2N+2 switching group MMC rectifier and a control method of the N input single-phase 2N+2 switching group MMC rectifier. The rectifier comprises N alternating-current inputting power supplies, N alternating-current inductors, a first bridge arm, a second bridge arm and a rectification output end load. Each of the first bridge arm and the second bridge arm is formed by connecting N+1 switching groups and two inductors in series. The ith switches in the first bridge arm and the second bridge arm are formed by connecting N power switching units in series and i is selected between 1 and N+1. The two ends of the kth alternating-current power supply serve as the kth circuit input, wherein k is selected between 1 and N and N is larger than two. The rectifier is controlled through carrier phase-shifting PWM, the N inputting alternating-current power supplies are converted into alternating-current inputting of N circuits of 2n+1 levels and after currents are rectified and overlapped, the load is powered. In an MMC power switching unit, the voltage stress borne by each switching tube is only one nth of the voltage of the direct-current power supplies and the problem of voltage sharing of the switching tubes is well solved. The N input single-phase 2N+2 switching group MMC rectifier is applicable to multiple-alternating-current-power-supply-inputting, high-voltage and large-power occasions.

The invention provides a three-phase nine-switch group MMC AC-AC converter and a control method thereof. The converter of the present invention includes a three-phase AC input power supply, an AC input inductance group, a first bridge arm, a second bridge arm, a third bridge arm, a first capacitor and a three-phase load; the first bridge arm, the second bridge arm The arm and the third bridge arm are each formed by connecting an upper switch group, a first inductor, a middle switch group, a second inductor, and a lower switch group in series; each switch group is formed by connecting N power switch units in series. The converter adopts carrier phase-shift PWM control, and the three-phase AC input power is converted into an AC input with a line voltage of 2N+1 level, which is transformed by AC-AC into an AC output with a line voltage of 2N+1 level to supply power to the load. In addition, the voltage stress of each switch tube in the MMC power switch unit is only 1 / N of the DC power supply voltage, which solves the problem of voltage equalization of the switch tubes and is suitable for high-voltage and high-power applications.

The invention provides a double-input single-phase six-switch-block MMC rectifier and a control method thereof. The rectifier comprises a first alternating-current input power supply, a second alternating-current input power supply, a first inductor, a second inductor, a first bridge arm, a second bridge arm and a rectification load. Each of the first bridge arm and the second bridge arm is formed by connecting an upper switch block, a middle switch block, a lower switch block ,a third inductor and a fourth inductor in series. The upper switch blocks, the middle switch blocks and the lower switch blocks of the first bridge arm and the second bridge arm are formed by connecting N power switch units in series. The rectifier is controlled through carrier phase-shifting PWM, and the two input alternating-current power supplies are converted into two circuits of alternating current input of the 2N+1 level, rectified and overlapped and provide power for the load. In addition, the voltage stress borne by each switching tube in each MMC power switch unit is only 1 / N of the voltage of a direct-current power supply, the voltage sharing problem of the switching tubes is well solved, and the double-input single-phase six-switch-block MMC rectifier is suitable for high-voltage and large-power occasions where two single-phase alternating-current power supplies are input.