A discharge circuit includes: a first transistor connected to power storage; an operational amplifier for controlling an output current of the first transistor; and the current mirror circuit connected to the operational amplifier. The current mirror circuit includes a second transistor connected to a non-inverting input terminal of the operational amplifier, and a third transistor connected to the power storage.

Provided is a DC-DC converter with galvanic isolation comprising a resonant oscillator coupled to a primary winding of a galvanic isolation transformer. A rectifier is coupled to a secondary winding of the transformer to provide an output voltage. The DC-DC converter comprises a regulation loop configured to regulate an output voltage with respect to a reference voltage by controlling a current flowing in the resonant oscillator as a function of a result of a signal indicative of the comparison between the output voltage and the reference voltage. The resonant oscillator is configured to operate at a frequency, in particular tuned at sub-resonant point, in particular sub-harmonic frequency, below a resonance frequency of the resonant oscillator which maximizes a quality factor of the resonant oscillator, in particular below a resonance frequency of a LC tank circuit comprised in the resonant oscillator which maximizes a quality factor of the LC tank circuit.

A transformer and an LLC resonant converter are provided. The transformer includes first and second cores configured to include a pair of outer foots and a middle foot positioned between the outer foots, and to induce a magnetic field formation; first and second inductor winding parts configured to include a conductor surrounding a circumference of each of the pair of outer foots of the first core, and to be connected in series with each other; and first and second transformer winding parts configured to include a conductor surrounding a circumference of each of the pair of outer foots of the second core, wherein the pair of outer foots of the first core face the pair of outer foots of the second core, the middle foot of the first core faces the middle foot of the second core, and the first core and the second core are disposed to be spaced apart from each other.

The invention provides a power converter comprising: an input for receiving input power with a variable nominal mains level, wherein said variable nominal mains level falls within at least 90V to 240V; a main power switch (Q1) driven by the input power, and a control circuit (Q2, Q3) for controlling a control current of the main power switch (Q1), wherein the control circuit in (Q2, Q3) is adapted to sense the level of the input power and draw current from a control terminal of the power switch (Q1) according to the level, and said control circuit is adapted to operate in linear region and increase the drawn current along with the increase of the level throughout the variable nominal mains level of the input power, wherein the control circuit comprises: a Darlington bridge with a first transistor (Q2) and a second transistor (Q3), the first transistor (Q2) with a base terminal connected to a circuit position indicative of the voltage amplitude of the input power, the second transistor (Q3) with a base terminal connected to an emitter terminal of the first transistor (Q2) and a collector terminal connected to the control terminal of the main power switch (Q1) and a collector terminal of the first transistor (Q2); and a resistor network (R3, R7) coupled to the emitter of the second transistor (Q3) for regulating the amplification of the second transistor (Q3) and keep the second transistor (Q3) working at linear region throughout the variable nominal mains level of the input power.

A self-excitation push-pull type converter with a transformer having a closed magnetic core or iron core, which formed of a main part (52) and a local part (53). The local part reaches magnetic saturation earlier than the main part under the same increasing magnetic field excitation. When the self-excitation push-pull type converter is in a light load state, the efficiency is significantly improved, and further improved in a rated load state. As the number of turns of the coil on the magnetic saturation transformer is reduced, the working frequency of the converter increases while still keeping the loss low. The probability of generating a current peak at the moments of switching on or off is reduced, thereby further improving the efficiency and reducing output ripples.

An electric drive system includes bus rails carrying a bus voltage, an energy storage system (ESS), and a power inverter. The system includes a voltage converter connected to the bus rails and having an inductor coil, semiconductor switches, a bypass switch connected to a positive bus rail, and a capacitor. A polyphase electric machine is electrically connected to the power inverter. A controller executes a method in which operation of the converter is regulated based on power, torque, and speed values of the electric machine. The converter is selectively bypassed by closing the bypass switch under predetermined high-power/high-torque conditions, with the bus voltage adjusted until it is equal to the battery output voltage. The bypass switch is opened and the bus voltage thereafter regulated to a predetermined voltage.

An electric drive system includes bus rails carrying a bus voltage, an energy storage system (ESS), and a power inverter. The system includes a voltage converter connected to the bus rails and having an inductor coil, semiconductor switches, a bypass switch connected to a positive bus rail, and a capacitor. A polyphase electric machine is electrically connected to the power inverter. A controller executes a method in which operation of the converter is regulated based on power, torque, and speed values of the electric machine. The converter is selectively bypassed by closing the bypass switch under predetermined high-power/high-torque conditions, with the bus voltage adjusted until it is equal to the battery output voltage. The bypass switch is opened and the bus voltage thereafter regulated to a predetermined voltage.

A switching power supply apparatus includes a PFM control circuit that outputs a clock signal Set such that a switching frequency of a switching element varies in accordance with a load state. The clock signal Set determines a turn-on timing of the switching element. A reference value of a current flowing through the switching element determines a turn-off timing of the switching element. A modulation signal is applied to the turn-off timing of the switching element to modulate one of a peak value of a drain current flowing through the switching element and an on-time of the switching element. Input control is performed separately on the clock signal Set and the modulation signal. Accordingly, even when the clock signal Set and the modulation signal contribute to each other to offset each other, modulation effects are not cancelled.

A converter includes a switching circuit, a resonant circuit, a rectifying circuit, and a transformer including a primary winding, and a secondary winding. The switching circuit is configured to convert a DC input voltage to a switching signal. The resonant circuit is electrically coupled to the switching circuit and configured to receive the switching signal to provide a primary current. The primary winding is coupled to the resonant circuit. The rectifying circuit is coupled to the secondary winding and configured to rectify a secondary current outputted by the secondary winding so as to provide an output voltage. The resonant circuit includes a variable inductor to adjust the characteristic curve of the converter.

The invention provides a driver circuit for driving an LED arrangement which uses a switch mode power converter, for example a flyback ringing choke converter, which comprises a main switch (e.g. bipolar transistor) and a sub-circuit for generating a current for the control terminal of the main switch. The sub-circuit in some examples makes use of an auxiliary winding as a voltage supply, and further comprises a ramp circuit for generating a ramp voltage from the voltage supply and a voltage follower, such as a control transistor, connected between the voltage supply and the control input of the main switch. By ramping up the current of the main switch, the losses arising as a result of the current flowing to the control input of the main switch are reduced. One set of examples makes use of a flyback ringing choke converter, which enables low cost implementation and good efficiency. The driver is able to receive a wide range of input voltages, by ensuring that the power loss is kept low. In particular, by ramping up the control current of the main switch, the losses arising as a result of the current flowing are reduced.