A switching converter has a first converter output for connection to a user load and a second converter output for connection to the user load. A first direct current rail power negative terminal has a first positive output and a first negative output connected to the second converter output. A second direct current rail power negative terminal has a second negative output and a second positive output connected to the first positive output. A first switch has a first positive terminal connected to the first positive output, a first negative terminal and a first control terminal. A second switch has a second positive terminal connected to the first negative terminal, a second negative terminal connected to the second negative output, and a second control terminal. A pulse width modulator has a first modulator output connected to the first control terminal, and a second modulator output connected to the second control terminal. An inductance is connected between the first converter output and the first negative terminal. A comparator controls the first pulse width modulator based on a voltage difference between a current measurement voltage that varies based on current through the inductance and a first set point voltage.

An inverter, an inverter system, and a method. The inverter includes an inverter circuit and a controller. When at least one of the following conditions is met, the controller adjusts at least one of parameters including an operating frequency, operating voltage, and operating current of the inverter, to increase a loss of the inverter, where the at least one condition is as follows: an output power of the inverter circuit is lower than a preset power, output current of the inverter circuit is lower than a preset current, operating temperature of the inverter is lower than a preset temperature, or operating humidity of the inverter is higher than a preset humidity. When any one of the foregoing conditions is met, the inverter may increase the operating temperature of the inverter or reduce the operating humidity of the inverter by increasing the loss of the inverter, thereby ensuring inverter operation.

The present invention has steps of determining a minimum number of levels (L_duty) required to output a target modulation ratio (d_ref) (S2), determining the total number (N_volt) of voltage orders to be controlled among a voltage fundamental wave and harmonics of power converter (S3), comparing the minimum number of levels (L_duty) and the total number (N_volt) of voltage orders to be controlled and fixing a larger one as the number of switching times N in a quarter cycle for the target modulation ratio (S4-S6); when (N_volt) is fixed, determining shape of an output voltage (S7), and based on the target modulation ratio and the number of switching times N in the quarter cycle, determining switching phases for N times, and deriving the pulse pattern for one cycle by which each output voltage level according to the target modulation ratio, the output voltage shape and the phase is determined (S8, S9).

A series-parallel switched capacitor voltage converter includes inductive branch, a first branch and a second branch, the inductive branch is connected between the first branch and the second branch. By controlling turning on and off of the switches of the first branch, the second branch and inductive branch, charges on capacitors of one branch are completely transferred to another branch via the inductive branch within a period of time after all main switches of the first branch and the second branch are turned off, and a voltage difference between both terminals of each of the main switches becomes zero, then each of the main switches is started to be turned on, the voltage difference of each of the main switches is zero at an instant when the main switches are turned on.

A switched capacitor converter includes an auxiliary circuit and two branches, the auxiliary circuit is connected between the two branches, the auxiliary circuit transfers an electric charge or electric charges on one branch to another branch of the two branches during a dead time when all primary power transistors of the two branches are turned off, so as to realize the primary power transistors are turned on at a zero voltage and reduce a switching loss. Therefore, the switched capacitor converter reduces the switching loss and improves efficiency.

A cascade switched capacitor converter includes an auxiliary circuit, a first branch and a second branch, the auxiliary circuit is connected between the first branch and the second branch, all power transistors of the first branch and the second branch are primary power transistors, and the auxiliary circuit transfers a charge or electric charges on one of the first branch and the second branch to another of the first branch and the second branch during a dead time when the primary power transistors are turned off, so as to the primary power transistors turn on at zero voltage and reduce a switching loss.

A control circuit controls a switching element including a gate and a source corresponding to the gate. The control circuit includes an inductor, a circuit element, and a resistor. The inductor is connected between the gate and the source of the switching element. The circuit element is connected in series to the inductor between the gate and the source. The circuit element allows an electric current to flow therethrough in response to generation of electromotive force in the inductor. The resistor is connected in parallel to the inductor and the circuit element between the gate and the source.

A power quality compensation system and a power quality compensation method are provided. The power quality compensation apparatus includes an input filter, a power electronic converter, a controller configured to control the power electronic converter, and a plurality of inductors connected to the power electronic converter. The power quality compensation method includes receiving signals from one or more sensors configured to detect voltage and current from an input side and an output side of the power quality compensation system, calculating reference signals, and using model predictive control to track the reference signals.

A common-mode voltage injection control method and apparatus for an inverter. For the method and apparatus, a common-mode voltage for a DPWM mode is calculated based on three-phase port voltages and an output power command; a common-mode voltage for an MPC modulation mode is calculated based on the direct current bus voltage, the three-phase port voltages, and the output power command; a modulation proportion is determined based on a maximum phase voltage peak value of the three-phase port voltages, the direct current bus voltage, and a power factor of the output power command; and a common-mode injection voltage is generated based on the common-mode voltage for the DPWM mode, the modulation proportion, and the common-mode voltage for the MPC modulation mode.

A switched-mode power supply includes a first switch transistor. A drain of the first switch transistor receives an input voltage on a direct current input bus of the switched-mode power supply, and a source is connected to a reference ground. The power supply circuit includes a junction field-effect transistor (JFET), where a drain of the JFET receives the input voltage, a gate is connected to the reference ground, and a source outputs a supply voltage or a supply current. During each switch cycle, the first switch transistor is controlled to be turned off or a drain voltage is controlled to be greater than or equal to a first threshold voltage when the first switch transistor is turned on, such that the supply voltage or the supply current satisfies a drive voltage of the first switch transistor and an operating voltage of a to-be-powered circuit of the switched-mode power supply.