Abstract: Systems and methods for compensating ripple current and improved ripple compensators and switching converters capable of compensating ripple current. In one embodiment, the ripple compensator for a switching converter of the type includes a switching means and filtering means comprises means for injecting a compensating current such that the AC component of the switching current and the compensating current are in opposite phase. In addition, the compensation current is elaborated from a signal at a node between the switching means and the filtering means.

Abstract: A method for controlling a switching power converter which includes a central capacitor exchanges charge between the capacitor and plural nodes of a first terminal, and then transfers the charge between the capacitor and plural nodes of a second terminal. The charge interchanged between the capacitor and the nodes establishes the amount of power transferred during each cycle. The charge which is interchanged is controlled by selecting the electrical phase between the currents drawn from the nodes and the voltages at the nodes.

Abstract: In a DC regulated power supply realized as AC adapter or the like by a switching power supply, a reference voltage correction circuit, which estimates a voltage drop corresponding to a load current, corrects to increase an output voltage by changing a feedback reference value for regulation of the output voltage from a reference voltage source, in accordance with the load current sensed by the load current sensing circuit. Therefore, there occurs no negative effects that would be caused when output sensing wires are routed to a remote load. In addition, unlike the arrangement in which a reference-use rectifying circuit as well as a load-use rectifying circuit are provided, the arrangement of the switching power supply is not complicated. That is, in correcting a voltage drop, which occurs in power supply lines, corresponding to the load current, it is possible to easily perform a stable output voltage control unaffected by wire routing.

Abstract: An apparatus for controlling the power of an AC voltage supplying an electrical consumer (14) by phase control and for reducing harmonics caused by said phase control, particularly within a range of 4 kHz, preferably within a range of the third harmonic, comprising a first switching element (12) (TRIAC) connected in series with the consumer (14) and driven by a control device (20) for performing a phase control. A second switching element (34) connected in series with a resistor element (32) is provided in parallel to the first switching element (12). The control device (20) is adapted to drive the second switching element (34) shortly before the first switching element (12) into its conducting state for a short time period.

Abstract: Techniques are disclosed to regulate a power supply with a compensation signal generation circuit. One example regulated power supply includes a sense circuit coupled to sense an output voltage of the regulated power supply. The regulated power supply also includes a switching power converter circuit, which includes a switch coupled to be switched in response to a control signal received from the sense circuit to regulate the output voltage of the regulated power supply. The regulated power supply also includes a compensation signal generation circuit coupled to receive a switching signal representative of a switching of the switch in the switching power converter circuit. The compensation signal generation circuit is to generate a compensation signal to approximate a load current to be delivered from an output of the regulated power supply. The compensation signal is to be received by the sense circuit to modify the control signal.

Abstract: The invention recognizes that filter size can be reduced substantially as power factor is permitted to deviate below unity in systematic ways. Preferred methods of the invention provide specific, computable waveforms that permit use of a minimum filter size given a desired target power factor.

Abstract: Apparatus for conditioning power generated by an energy source includes an inverter for converting a DC input voltage from the energy source to a square wave AC output voltage, and a converter for converting the AC output voltage from the inverter to a sine wave AC output voltage.

Abstract: An unregulated isolated DC/DC converter is configured to receive an input signal and to provide an output signal. A ripple control circuit is coupled to the unregulated isolated DC/DC converter, wherein the ripple control circuit is configured to reduce an amount of low frequency ripple transferred to the output signal from the input signal.

Abstract: A power converter that can continue to operate after suffering a partial failure. The power converter includes multiple array transformers; normally-on switches connected respectively in series with the ends of each of the primary windings of the array transformers; normally-off current bypass devices connected in parallel with the series connections of the primary windings of the array transformers and the switches at the transformer ends; AC-DC converter units having AC sides respectively connected secondary windings of the array transformers; and mutually independent DC circuits respectively connected to DC sides of the AC-DC converter units. By turning on the current bypass device of the primary winding of a specified array transformer and turning off the switches at the ends of that primary winding, it is possible to isolate the specified array transformer and the AC-DC converter unit connected to it.

Abstract: A power conversion system having a DC power distribution bus includes multiple power converters connected to the DC power distribution bus with modulation frequencies synchronized so that providing phase shifts between the different modulations has the effect of compensating voltage and current ripples, e.g., reducing voltage fluctuations, across the DC bus. Power conversion may be controlled using space vector modulation implemented, for example, by any of a variety of pulse width modulation schemes. Phase shifts in which nulls of the modulation cycles of different converters do not overlap (in the time domain) may be particularly effective for DC bus voltage ripple compensation. The novel method for DC bus voltage ripple compensation may be implemented by programming a digital signal processor to control the power converters.

Abstract: Method for decreasing the existence of externally detectable revealing signals, so-called {umlaut over (R)}Ö{umlaut over (S)}, from keyboards (1), e.g. for computers, where the keyboard is fed with signals, so-called matrix signals, which are detected for detection of activity regarding the keys (2) of the keyboard, whereby said matrix signals are generated by means of signal devices. The method is especially characterized in that the matrix signals are high-frequency filtered before they are fed to the keyboard.

Abstract: A switching mode power supply and a method for outputting voltage therefrom are provided, where a transformer receives rectified alternating current (AC) voltage and transforms a voltage value or a current value, a switching transistor is connected to one end of a first coil and controls a level of power supplied to the first coil, a heat sink is positioned adjacent to the switching transistor and attenuates electromagnetic wave noise of the switching transistor; and a capacitive device is set up in an electric power line connecting the heat sink to a first side grounding end coupled with the other end of the first coil of the transformer. Accordingly the switching mode power supply can be miniaturized while effectively attenuating the electromagnetic wave noise from the switching transistor.

Abstract: The invention relates to a method for power control of an electric motor, in particular a motor for driving the suction fan of a vacuum cleaner connected to an AC mains power supply. The power control is effected by varying the phase angle of the electric alternating quantity supplied to the motor by the use of semiconductor switches. AC power supplied to the motor is switched by using different delay times for the switching in each half-period of a full AC period to suppress odd harmonics, particularly the third harmonic of the mains power line frequency. Half-periods of a full period are mirrored in the next consecutive full period in order to suppress even harmonics, particularly the second harmonic of the mains power line frequency. A set of delay times t1 and t2 are defined and selected to be used in further avoiding critical delay time areas for harmonics and minimize the generation of vibrations.

Abstract: An electronic apparatus, AC/DC conversion device and power factor correction circuit are provided. The power factor correction circuit includes an inductance, a switch, a power control chip, a first diode and a first capacitor. The inductance has a first end and a second end. The first end receives a first voltage. The switch has one end coupled to the second end of the inductance and has the other end coupled to a low voltage. The power control chip receives a spread spectrum synchronization signal, and controls turning on/off of the switch by a control signal according to the spread spectrum synchronization signal. The first diode has an anode coupled to the second end of the inductance. The first capacitor has one end coupled to a cathode of the first diode for generating a second voltage and has the other end coupled to the low voltage.

Abstract: A mechanism for reducing common-mode current in a system including a first subsystem and an isolated subsystem. The isolated subsystem may receive the common-mode current from the first subsystem via an isolation mechanism. The isolation mechanism (e.g., a transformer) may isolate the isolated subsystem from the first subsystem by blocking DC signals. The first subsystem may include a pulse generation unit and compensation circuitry. The pulse generation unit may provide a first pulse and a second pulse to the compensation circuitry. The phase and duty cycle of the pulses may be varied based on measured characteristics of the isolation mechanism. The compensation circuitry may generate a cancellation signal based on the first and second pulses. Furthermore, the compensation circuitry may provide the cancellation signal to a ground plane of the isolated subsystem to reduce the common-mode current received at the isolation subsystem.

Abstract: A motor control circuit for controlling a motor, the circuit comprising a switched mode power supply operable to drive a full bridge switching transistor arrangement and to provide a stable voltage to the motor control circuit, wherein the switching transistor arrangement is connectable to the windings of the motor to be controlled, and wherein the switching transistor arrangement comprises: a first set of transistors in an upper part of the full bridge and a second set of transistors in a lower part of the full bridge, the first set of transistors being driven by a first output of the switched mode power supply and the second set of transistors being driven by a second output of the switched mode power supply.

Abstract: An active type harmonic suppression apparatus, connected in parallel to a power feeder, supplies a compensation current for injecting into the power feeder such that a utility current of a power source is approached to a sinusoidal wave. The control circuit retrieves a load current, a utility current, an output current of the power converter, a power source voltage and a voltage of the dc power capacitor for calculating and sending a reference signal of compensation voltage to a pulse-width-modulation circuit which generates switching signals for the power converter. Furthermore, the harmonic suppression apparatus can provide a fixed or variable reactive power.

Abstract: A power supply configured for converting an input AC voltage into an output DC voltage having a desired voltage level is provided. The power supply includes a front-end power converter such as a PFC converter which is configured to convert the input AC voltage into an intermediate DC voltage generated across an output capacitive unit, and a back-end power converter such as a DC-DC converter which is configured to convert the intermediate DC voltage into an output DC voltage having a desired voltage level. The power supply further includes a resonant network consisted of a filter which is made up of at least one inductive filtering element having an inductive impedance and a capacitive filtering element having a capacitive impedance. The resonant network is placed between the front-end power converter and the back-end power converter, and coupled with the output capacitive unit for filtering the current flowing into the output capacitive unit.

Abstract: Method and apparatus for providing harmonic inductive power, and more particularly for delivering current pulses providing a desired amount of pulse energy in high frequency harmonics to a load circuit for inductive heating of an article. By controlling the shape and/or frequency of such current pulses, the apparatus and method can be used to enhance the rate, intensity and/or power of inductive heating delivered by the heater coil and/or to enhance the lifetime or reduce the cost and complexity of an inductive heating power supply. Of particular significance, the apparatus and method may be used to significantly increase the power inductively delivered to a ferromagnetic or other inductively heated load, without requiring an increase of current in the heater coil. This enables new heating applications, and in some known applications, decreases the energy consumption or cooling requirements and/or increase the lifetime of the heater coil.

Abstract: An improved power converter that produces reduced-levels of common-mode voltages, or even entirely eliminates such voltages, is disclosed herein, along with a method of reducing common-mode voltages. In at least some embodiments, the improved power converter is equipped with common-mode filter inductors and a link coupling input and output ports of the power converter with one another to communicate a ground point associated with the input ports of the converter (and the source) to the load. Further, in at least some embodiments, the method includes providing common mode filter inductors as part of the converter, where the inductors are connected at least indirectly to at least one of a rectifier and an inverter of the converter, and communicating a grounded neutral from input ports of the converter to output ports of the converter by way of at least one additional linkage.

Abstract: In a DC to DC converter, first and second primary windings are magnetically coupled to a first secondary winding. Third and fourth primary windings are magnetically coupled to a second secondary winding. The first and second primary windings are magnetically coupled to the first secondary winding. The third and fourth primary windings are magnetically coupled to the second secondary winding. The first and third primary windings are coupled in series to form a first coil member. The second and fourth primary windings are coupled in series to form a second coil member. One end of the first coil member is coupled to the first positive power line. A first switching element is coupled between the first negative power line and the other end of the first coil member. A first capacitor is coupled between the first negative terminal and one end of the second coil member.

Abstract: A fixed-frequency switching regulator having a noise injection circuit. Noise is injected into the feedback loop of the switching regulator to modify the switching waveform to reduce individual frequency harmonics of the resultant Fourier Series. The reduced frequency harmonics allow the switching regulator to achieve reduced conducted emissions.

Abstract: A negative ions generating circuit design with decreasing high frequency noise includes a power indication circuit, an oscillation circuit, an amplifying circuit and a radial frequency filtering circuit. The power indicating circuit, the oscillation circuit and the amplifying circuit are used for generating negative ions. The radial frequency filtering circuit has a capacitance to be utilized for limiting the high frequency in a coil so that the high frequency will not be amplified by through the transistor of the oscillation circuit. The coil creates an inductance to limit the high frequency so as to effectively eliminate the high frequency created by the oscillation circuit.

Abstract: A noise suppressor capable of achieving reduction in size and weight of devices is provided. The noise suppressor is a circuit for suppressing normal mode noise which is transmitted through a first current-carrying wire and a second current-carrying wire, and causes a potential difference between the current-carrying wires, and the noise suppressor includes a magnetic core including one magnetic material portion and another magnetic material portion magnetically coupled to the one magnetic material portion, and forming two magnetic loops so as to share the one magnetic material portion between them, an inductor including a first coil and a second coil which are wound around the one magnetic material portion so as to have an odd number of turns in total, and are inserted into and connected to the first current-carrying wire in series; and a capacitor having one end connected to a connecting point between the first coil and the second coil and the other end connected to the second current-carrying wire.

Abstract: The disclosure concerns a a motor drive apparatus, an electric actuator and an electric power steering apparatus capable of continuous torque control up to the high drive speed and high torque area, in order to enable quick acceleration and deceleration. A controller comprises a voltage saturation detecting apparatus for detecting the voltage saturation of the output voltage of an inverter circuit, based on the battery voltage, and a waveform controller that converts the drive waveform of the inverter circuit into the waveform created by superimposing harmonics of high odd-numbered order on a sinusoidal wave as a fundamental wave of the modulated wave modulated by a PWN carrier wave; and continuously changes the ratio of superimposing the high-order harmonics in response to the voltage saturation detected by a voltage saturation detecting means. This arrangement allows the controller to continuously change the drive waveform of the inverter circuit.

Abstract: A DC power source apparatus has a DC power source for supplying a DC voltage, a transformer, and a switching element connected to a primary winding of the transformer. The switching element carries out ON/OFF operations to convert the DC voltage from the DC power source into high-frequency power, which is transferred to a secondary winding of the transformer and is converted into a DC output voltage. The primary winding of the transformer consists of a first primary winding made of a plurality of winding layers and a second primary winding made of a plurality of winding layers. The first and second primary windings are connected in parallel. The first primary winding is arranged on an inner side of the secondary winding, and the second primary winding is arranged on an outer side of the secondary winding. A terminal of a winding layer farthest from the secondary winding among the winding layers of each of the first and second primary windings is connected to the switching element.

Abstract: A ripple current reduction circuit is provided that reduces the ripple current of a transformer by providing a substantially opposite or inverse ripple of an auxiliary current that can be combined with the ripple current of the transformer for cancellation or reduction of the ripple current.

Abstract: A method for determining the switching frequency of a DC-to-DC power supply for a portable radio transceiver (300) includes determining a first group of switching frequencies (301) and then determining the switching harmonics based on that group of switching frequencies (305). These switching harmonics are then compared to a group of desired radio channels (311) where it is then determined if the switching frequencies interfere with the group of desired radio channels (313). Based on these results, a second group of switching frequencies is selected if the first set of switching frequencies provides an undesired level of interference (317, 319, 321).

Abstract: A system is provided that includes a power distribution network to provide a switching current and a resonance reduction circuit to sense the switching current within a frequency range and to generate a resonance reduction signal having a current component at substantially a same frequency and substantially 180 degrees out of phase from the sensed switching current. The power distribution network may combine the switching current with the resonance reduction signal to provide a total switching current that may be provided to a processor as the powering signal.

Abstract: An RMS-to-DC converter system is disclosed. The system includes a variable gain amplifier having transfer function ripple that receives an input signal and provides an amplifier output signal, a detector that receives the amplifier output signal and provides a detector output signal, an error amplifier that receives the detector output signal and provides an error amplifier output signal having an AC component, and a feedback circuit coupled to the error amplifier output signal and to the variable gain amplifier for providing a feedback signal to the variable gain amplifier that includes an AC component for reducing transfer function ripple of the RMS-to-DC converter system.

Abstract: A control system includes a measurement device capable of gathering high frequency process parameter data, a modeling routine which uses the high frequency parameter data to develop a model of the high frequency noise and a compensation routine that employs the developed model to adjust a control signal to thereby compensate for the high frequency noise present within the process parameter. The measurement device may measure a process variable at a relatively high frequency and send a subset of the measured data (e.g., the low frequency data) to a standard controller that generates a control signal to control the measured process parameter in any known manner. The modeling routine analyzes the high frequency data and develops a mathematical model of the high frequency noise within the process variable.

Abstract: An active filtration or harmonic scrubber system for power systems that convert AC power on an AC bus to DC power that cancels or reduces harmonic current injected by nonlinear loads onto the AC bus using high-bandwidth pulse width modulation (PWM) inverters.

Abstract: A filter system for attenuating electromagnetic interference (EMI) of an autotransformer-based rectification system that utilizes the leakage inductance of the autotransformer and one or more capacitors connected on the secondary side and optionally one or more differential mode inductors and input capacitors connected on the primary side to form a differential mode EMI filter. This configuration reduces the size, weight, and cost of the differential mode EMI filter when compared with a differential filter formed by placing the inductors and capacitors on the primary side.

Abstract: Losses are reduced in electrical conductors and filters, especially those made with superconducting cables or inductors, which carry currents having both direct current (DC) and alternating current (AC) portions as in rectifier busses and power distribution systems. Superconducting cables and chokes are capable of passing direct current with practically zero losses, but they exhibit considerable AC losses. A low impedance AC bypass of the superconducting cables and chokes minimizes these losses.

Abstract: A method of controlling of an induction machine using an inverter is disclosed with output LC filter. The method includes determining an inverter output current vector (iA), determining an inverter output voltage vector (uA), and forming a full-order observer having a system matrix (Â) and gain vector (K). The observer produces an estimated rotor flux linkage vector ({circumflex over (?)}R), an estimated stator current vector (îs), an estimated stator voltage vector (ûs) and an estimated inverter output current vector (îA). An estimation error (iA?îA) of the inverter output current vector is determined, and a speed adaptation law is formed based on the estimation error of the inverter output current vector for determining an estimate for electrical angular speed ({circumflex over (?)}m) of the induction machine. The induction machine is controlled based on the produced estimates and a measured inverter output current.

Abstract: A power supply is filtered while the amount of in-rush current required by the capacitive charging of the filter is limited. A resistor may be placed in parallel with a relay where the parallel combination is in series with the filtering capacitor. The relay is open upon applying power to the filter and remains open while the capacitor at least partially charges to cause charging current to pass through the resistor and thereby limit in-rush current. The relay is closed thereafter to provide a short circuit around the resistor and thereby unrestrict filtering by the capacitor. Alternatively, a common mode choke is disposed between a capacitor across input nodes and a capacitor across output nodes, whereby the size of the capacitors may be reduced to limit the in-rush current due to the common mode choke. The power supply filter may be included as part of a power distribution panel.

Abstract: An apparatus for canceling an effect of power supply resonance is provided. The effect of power supply resonance is a variation in power supply voltage potential. This variation may substantially affect an output buffer by causing the output buffer's output to sag below desired values. A voltage regulating circuit is coupled to power supply lines local to the output buffer where the voltage regulating circuit is most effective in reducing voltage potential variation. An exemplary voltage regulating circuit is provided that uses charge-pumped capacitors to raise the power supply voltage potential when it falls below a desired value. A second example of a voltage regulating circuit uses charge-pumped capacitors to lower the power supply voltage potential when it rises above a desired value.

Abstract: A method in connection with a network inverter, an LCL network filter (3) being connected between the network inverter (1) and network (2), and the network inverter being arranged to operate as an active converter of harmonic components of electricity, and the method comprises the steps of forming a current reference (i1, ref) for the network inverter (1) for producing a desired voltage, selecting a harmonic electric component (v), the proportion of which needs to be changed, forming a current reference (i1, refv) altering the selected harmonic component (v), summing the generated current reference (i1, refv) altering the selected harmonic component with the current reference (i1, ref) of the network inverter to produce a summed current reference (i1, ref, tot), and controlling the network inverter with the summed current reference (i1, ref, tot) in a coordinate system bound to the virtual flux linkage of the network inverter by using DTC control.

Abstract: A method and structure for active power control of a power supply element coupled to an electronic circuit. The structure comprises a control element coupled to the electronic circuit, said control element comprising one or more of a phase detector, a counter, a level detector, a voltage controlled oscillator, and one or more transistive elements wherein the control element is operable to measure one or more oscillations of a power supply signal of the power supply element. The structure further comprises a stabilization element coupled to the control element and coupled to the circuit, comprising one or more capacitive elements, one or more transistive elements and one or more resistive elements, wherein said one or more capacitive elements, one or more transistive elements and one or more resistive elements are operable to mitigate one or more oscillations of the power supply signal of the power supply element.

Abstract: A motor control apparatus having a fundamental wave current control circuit that implements feedback control on a fundamental wave component of a motor current in a dq coordinate system rotating in synchronization with the rotation of the motor and a higher harmonic current control circuit that implements feedback control on a higher harmonic components of the motor current in a dhqh coordinate system rotating with a frequency which is an integral multiple of the frequency of the fundamental wave component of the motor current, eliminates the higher harmonic component of the motor current from the control deviation between a fundamental wave current command value and a motor current feedback value.

Abstract: A device for converting electrical energy at a high operating frequency, supplied by an electrical network having a capacitor placed between a line and an earth of the device, the capacitance of the capacitor being such that the high-frequency noise is filtered and an inductor placed parallel to the capacitor and having a low resonant frequency corresponding substantially to the frequency of the electrical supply network. The device provide filtering in order to prevent the transmission of high frequency interference from the device to the electrical network while preventing, as far as possible, leakage currents through the filter. The device is useful in the electrical network for an X-ray apparatus.

Abstract: A converter with a damping mechanism for preventing resonances that includes a rectifier, an inverter and an intermediate circuit which connects the rectifier to the inverter. The intermediate circuit includes a first conductor connected to a first potential, a second conductor connected to a second potential that is different than said first potential and a current-compensated choke looped into the first conductor and the second conductor. The current-compensated choke includes a first winding and a second winding, wherein a first current flowing from the rectifier to the inverter flows through the first winding and a second current flowing back from the inverter to the rectifier flows through the second winding.

Abstract: A dual bridge matrix converter has a line-side converter with controllable switches that receives AC power and provides unidirectional power to high and low DC link lines, and a load-side converter which receives the power from the DC link lines and provides AC power to output lines. A clamp circuit is connected across the DC link lines and includes a series connected diode and a capacitor. Negative DC link current will be conducted through the clamp diode to charge the clamp capacitor to avoid voltage spikes on the DC link lines. A controllable switch may be connected in parallel with the clamp diode and is turned on when the voltage across the clamp capacitor is above a threshold that is greater than the normal peak-to-peak AC input voltage. The switch is turned off when the voltage across the clamp capacitor is lower than the threshold voltage.

Abstract: In a PWM space vector modulation inverter motor drive system, PWM cycles are modified to permit motor phase currents to be reconstructed as observable on the DC bus link. The PWM cycles are modified near sector boundaries so that measurements taken at the DC bus link correspond to actual motor phase currents. With this technique, a single DC bus current measure can be used to reconstruct all motor phase currents, while also providing fault protection.

Abstract: A parallel resonant circuit for removing noise and harmonic frequencies from the AC power source is connected directly in parallel to a power source with no intervening electrical components. The parallel resonant circuit is comprised of at least one inductor for drawing an inductive current that is substantially equal to but one hundred and eight degrees out of phase with at least one capacitor that draws a capacitive current. The capacitors and the inductors of the parallel resonant circuit are connected in parallel and may be tuned to the fundamental frequency of the power line.

Abstract: An 18-pulse converter is constructed using two, high zero-sequence impedance, phase-shifting autotransformers to parallel two 3-phase bridge converters. A third 3-phase bridge converter is directly connected to the power source. Depending on the DC filtering technique, the kVA rating of each autotransformer is 15 to 22% that of the DC load kW. The method facilitates paralleling of 3-phase bridge converters to reduce system AC line current harmonics, and is suitable for 18, 24, 36, and higher pulse numbers. The minimum number of individual autotransformers required is (n?1), where n is the number of 3-phase bridge converters. Due to the high zero-sequence impedance of the autotransformers, only a small DC load is needed to limit the DC output voltage. AC line reactance may be included in series with each converter, or in the 3-phase AC power source, to further reduce AC line current harmonics.

Abstract: An active EMI filter senses current in a ground line as a voltage across a capacitor coupled to the ground line. The EMI filter senses common mode voltage and determines a difference between the common mode voltage and noise to provide an output to the ground line to reduce the difference.

Abstract: Techniques for reducing noise generated by a circuit include a common mode filter and a differential mode filter. The common mode filter includes an input for sensing a common mode signal between a power source and the circuit, an output, and active circuitry for producing an offset signal on the output. The differential mode filter includes an input, an output, and active circuitry for sensing a differential mode signal and producing variations in resistance between the input and output to offset the differential signal.

Abstract: A method for eliminating noise interference and acoustic noise by a printed circuit board ground plane layout is disclosed. The method is applied to a circuit system having multiple outputs, wherein the circuit system has a first power converting module, a second power converting module and a printed circuit board. The first power converting module and the second power converting module respectively includes a first ground pin group and a second ground pin group. The method includes the steps of (a) connecting each ground pin of the first ground pin group to a respective solder point and connecting each solder point to a first node, and connecting each ground pin of the second ground pin group to a respective solder point and connecting each solder point to a second node, and (b) connecting the first node and the second node to a common node and connecting the common node to a solder point of a common ground terminal on the printed circuit board ground plane.

Abstract: A switched mode power supply which uses a shieldless transformer (11) in the dc to dc converter. Common mode switching noise is reduced by connecting two capacitors (17, 18) in series between the transformer primary (12) and secondary (13) circuits and connecting an inductor (19) between the junction of the two capacitors (17, 18) and chassis earth. The values of the capacitors (17, 18) and inductor (19) are selected such that the capacitors (17, 18) present a low impedance to noise signals and the inductor (19) presents a high impedance to noise signals.