Abstract: There is provided an integrated control method for eliminating a low frequency ripple in a power conversion system for a fuel cell, more particularly, a control method of a power conversion system capable of eliminating a low frequency ripple, controlling a DC link voltage, and controlling an output power and a system using the same control method. A power conversion system (PCS) that converts an output of a DC power supply received from an external power supply includes a converter that converts a voltage of the input power supply; an inverter that converts an output voltage of the converter into an AC voltage; and a converter control module that outputs a PWM signal for controlling a switch of the converter, and after receiving a power instruction value, the converter control module generates the PWM signal for controlling the converter based on the power instruction value.

Abstract: The invention relates to a method for operating an inverter comprising a step-up device which is upstream-connected by means of an intermediate circuit and is connectable to a direct-current source with a variable reference sampling current wherein said inverter and the step-up device are provided with an efficiency optimizing working area, respectively. When the variable reference sampling current is raised and the step-up device approaches a pulse duty factor value, the intermediate circuit voltage is reduced and the variable reference sampling current is stabilized, said intermediate circuit voltage is re-raised. When the direct-current source is in a permanent operational state, the inverter and the step-up device operate in the efficiency optimizing working area thereof, respectively.

Abstract: A power supply and methods are provided. In one implementation, the power supply includes a switching converter with power feedback circuit to output constant power to keep lamp at constant brightness. The power feedback circuits include a current feedback circuit and a voltage feedback circuit. The power supply further includes a controller operable to adjust on time or duty cycle of main switch to keep the output power constant.

Abstract: The invention relates to a power converter comprising, in particular, a rectifier comprising at least one switching leg provided with two transistors (T1-T6) connected in series. The transistors (T1-T6) are of the normally ON field-effect type, for example JFETs, and are each controlled by a gate control device (CT1-CT6). Each gate control device comprises, in particular: an output (OUT1) connected to the gate (G) of the controlled transistor, a voltage rectifier element connected between the output of the control device and an input (in1, in3) of the converter, a capacitor (C11) connected between the source (S) of the transistor and a point situated between the output of the control device and the voltage rectifier element.

Abstract: The DC power supply apparatus includes a switching operation control part that is provided between a current detection part to detect a current flowing through a primary coil of a transformer and a control part to control the operation of a switching part and controls the operation of the switching part according to an output voltage so that consumption power in a low-load state can be further reduced.

Abstract: To provide a hybrid power supply device capable of properly controlling an operation of an engine generator and also preventing the device from increasing in size. The power supply device including an engine generator 11 and a capacitor 15 comprises: a DC bus La having the engine generator 11 and the capacitor 15 connected in parallel and supplying electric power to an outside; a step-up converter 13 provided between the DC bus La and the engine generator 11; and a control section 17 controlling the step-up converter 13 and regulating electric power supplied from the engine generator 11 to the DC bus La. Since both of the engine generator 11 and the capacitor 15 can supply electric power to the outside, the engine generator 11 can be downsized.

Abstract: A regulated power supply apparatus is provided. The apparatus includes an input power converting circuit for generating a rectified voltage signal, an output power converting circuit comprising a plurality of switching elements, the output power converting circuit coupled to receive the rectified voltage signal, an output power storing element coupled with the output power converting circuit, and an output power bidirectional regulating circuit comprising an integrated circuit coupled with the output power converting circuit, the bidirectional regulating circuit including control signals for operating the switching elements to store power on the output power storing element and to deliver power to an output load from the output power storing element. An integrated circuit controlled regulator circuit is provided for controlling a plurality of switches a boost and buck converter. A method of regulating power supply is also provided.

Abstract: In a first aspect, a digital control circuit is provided for use with a switch-mode power converter that receives an input signal at a first input node and a control signal at a second input node, and that provides an output signal at a first output node and a current signal at a second output node. The digital control circuit generates a programmable current reference signal based on a difference between the output signal and a voltage reference signal, calculates a time instant when the current signal substantially equals the programmable reference current signal, and generates the control signal based on the calculated time instant. Numerous other aspects are also provided.

Abstract: An HVAC/R system is configured with power storage for power back-up to maintain substantially uninterrupted power in the case of a main power failure. The power back-up system has a DC power source configured to be recharged, and provides power to the HVAC/R components.

Abstract: Control systems, methods and power conversion systems are presented for reducing common mode voltages in AC motor loads driven by inverter PWM control using switching sequences with only active vectors where a first vector of each switching sequence differs by one phase switching state from a last vector of a switching sequence of an adjacent sector, along with enhanced deadtime compensation and reflected wave reduction techniques in providing pulse width modulated switching signals to a switching inverter.

Abstract: The present invention is directed to largely improve the efficiency at the time of light load of a power supply apparatus using a power factor correction (PFC) controller. A PFC controller is provided with a voltage-current converter. The voltage-current converter converts voltage of a signal output from an error amplifier for detecting voltage level of output voltage to an arbitrary current value and outputs the current value as a correction current. The voltage-current converter outputs a correction current of a large current value when the error amplifier detects that the load is light, and the PFC controller performs control to decrease the output voltage.

Abstract: A control circuit for use in a power converter with an unregulated dormant mode of operation is disclosed. In one aspect a power converter includes a drive signal generator that is coupled to generate a drive signal to control switching of a power switch coupled to the control circuit to regulate a flow of energy to an output of the power converter in response to an energy requirement of one or more loads coupled to the output of the power converter. A regulator circuit is coupled to charge a capacitor. The capacitor determines a time period. The regulator circuit is coupled to not charge the capacitor if the energy requirement of the one or more loads coupled to the output of the power converter falls below a threshold. The regulator is coupled to again charge the capacitor after the time period has elapsed.

Abstract: A method of testing power converter current sensors is disclosed. The method may include receiving a current sensor test request and receiving measured currents from current measurements from the at least one current sensor, based on the test request. The method may further include comparing the measured current of the sensor with a stored profile and determining whether a fault exists in each current sensor being tested. The method may also include providing a user with a test report.

Abstract: A current controller device using a vector control algorithm for controlling conversion of DC power into AC power is provided. The controller device has an open loop control loop gain and produces a first and a second voltage demand signals based on a first and a second current demand signals, a first and a second current feedback signals, a first and a second voltage feedback signals. The open loop control loop gain depends on frequencies of the first and second current feedback signals. A first and a second filters are provided at a first and a second current feedback inputs respectively. The first and second filters each have a filter characteristics to reduce the frequencies of the first and second current feedback signals at which the open loop control loop gain is greater than unity and has a phase less than or equal to minus 180°.

Abstract: An AC to DC converter system is disclosed in which a conversion circuit for converting an AC input signal to a DC output signal is operably coupled with an enabling circuit designed for sensing and output parameter indicative of the presence or absence of a load at the DC output. The system is designed so that the conversion circuit operates in an inactive standby state when there is no load, and in an active state for supplying DC power when a load is present. The enabling circuit is configured to operate using low power.

Abstract: A power control system includes a switching power converter and a controller, and the controller responds to a time-varying voltage source signal by generating a switch control signal having a period that varies in accordance with at least one of the following: (i) the period of the switch control signal trends inversely to estimated power delivered to a load coupled to the switching power converter, (ii) the period of the switch control signal trends inversely to instantaneous voltage levels of the voltage source signal, and (iii) the period of the switch control signal trends directly with a line voltage level of the time-varying voltage source signal. In at least one embodiment, the controller achieves an efficient correlation between the switching period with associated switching losses and the instantaneous power transferred to the switching power converter while providing power factor correction (PFC).

Abstract: A power supply and methods are provided. The power supply includes a bi-forward converter and a feed forward circuit. The bi-forward converter is operable to convert an input voltage into an output voltage. The feed forward circuit is operable to detect a peak voltage associated with the input voltage, and the bi-forward converter is further operable to adjust the output voltage responsive to the peak voltage detected by the feed forward circuit.

Abstract: A controller for a switched mode power supply (SMPS) is provided. The SMPS is equipped with a transformer having a primary side winding, a secondary winding, and an auxiliary winding. The controller includes a detection circuit for detecting a transition from a first output load condition to a second output load condition of the SMPS and a control circuit coupled to the detection circuit and being configured to output one or more control signals in response to the detected output load transition. Depending on the embodiment, the one or more control signals include a first control signal for turning on a power switch to cause a current flow in a primary winding of the SMPS and/or one or more second control signals for turning off one or more functional circuit blocks in the controller.

Abstract: A microsource is provided, which includes an inverter, an energy storage device, and a controller. The controller calculates a maximum frequency change for the inverter based on a first comparison between a first power set point and a measured power from the inverter. The first power set point is defined based on a charge level of the energy storage device. A minimum frequency change for the inverter is calculated based on a second comparison between a second power set point and the measured power from the inverter. An operating frequency for the inverter is calculated based on a third comparison between a power set point and a measured power flow. A requested frequency for the inverter is calculated by combining the maximum frequency change, the minimum frequency change, and the operating frequency. The requested frequency is integrated to determine a phase angle of a voltage of the inverter to control a frequency of an output power of the inverter.

Abstract: A portable power supply for controlling laboratory experiments, the power supply includes input terminals that receive control signals and power terminals that supply power to laboratory devices. The power supply enables power levels of standard laboratory equipment to be automatically controlled.

Abstract: In one embodiment, a method of verifying a component coupled to an output of a power supply includes measuring a frequency response from a control input of the power supply to the output of the power supply. The method also includes comparing the frequency response to a predetermined metric based on the measuring. The component is determined to be valid if the frequency response falls within the predetermined metric.

Abstract: Embodiments of an apparatus to increase the power efficiency of an electric motor load have been presented. In one embodiment, the apparatus includes a parameter detection circuit coupled to the electric motor load to detect one or more parameters of the electric motor load. Furthermore, the apparatus may include a power management controller coupled to the parameter detection circuit to receive the one or more parameters and to scale a voltage supply to the electric motor load in response to the parameters.

Abstract: A lower limit value setting unit (52) variably sets a lower limit value (Vth) of a target voltage (Vh*) in a range of a voltage that is higher than the maximum value of voltages (Vb1, Vb2) of power storage devices and is not affected by a dead time provided for converters, based on temperatures (Tb1, Tb2) and required electric powers (Pb1*, Pb2*). A maximum value selection unit (53) sets the maximum value among the voltages (Vb1, Vb2) of the power storage devices and required voltages (Vm1*, Vm2*) of motor-generators, as the target voltage. A target voltage limiting unit (54) compares the target voltage with the lower limit value (Vth), and if the target voltage is lower than the lower limit value (Vth), the target voltage limiting unit (54) sets the lower limit value (Vth) as the target voltage (Vh*).

Abstract: The control apparatus for controlling a voltage transforming apparatus having a transformer, power switching elements disposed in a primary side, and synchronous-rectifying switching elements disposed in a secondary side includes a judging circuit making a judgment as to whether or not an output current of the voltage transforming apparatus is smaller than a specified current on the basis of a primary-side current of the transformer and an inhibition circuit inhibiting the synchronous-rectifying switching elements from performing their synchronous-rectifying control operation when the judging circuit judges that the output current is smaller than the specified current. The judging circuit makes the judgment with compensating for a variation of a relationship between the primary side-current and the output current due to variation of duty ratio of the power switching elements, and variation of at least one of the DC output voltage and the DC input voltage of the voltage transforming apparatus.

Abstract: The present invention relates to an apparatus and a method for converting power from a power input to a DC output current or voltage, where a first feedback circuit a traditional feedback. The converter type is a resonant DC-DC converter. The scope of the invention is to reach a high effective and fast responding switch mode power supply. This can be achieved with an apparatus or method comprising a second feedback circuit leading a signal from a serial resonance capacitor(s) to a reference input terminal at the control circuit, which second feedback circuit contains a signal depending on the actual change in charge of the resonant capacitor(s). This means that at high load, a very powerful signal will be transmitted through the second feedback at the control circuit that will change the operation of the circuit into a charge mode operation.

Abstract: One embodiment of the invention includes a PV array and an electrolyzer operatively connected together and each operatively connected to a utility power grid so that electricity produced by the PV array is selectively delivered to the utility power grid and the electrolyzer. The resulting process increases the efficiency of the solar-hydrogen production process, and results in lower-cost renewable hydrogen.

Abstract: Apparatuses and methods for optimizing power generation of a solar array are disclosed. The bus voltage is regulated with a regulator controlled through one or more reference signals. When the power bus is being used by electrical systems that are tolerant of a higher variable voltage range, the bus voltage can be temporarily set higher by a commanded reference signal to allow additional solar array power to supply to the power bus. The peak power point may be identified through an established relationship with the solar array performance as a function of temperature, season and/or the age of the solar array. In addition, a reference signal controlled by one or more temperature sensors on the solar array may also modify the bus voltage set-point. Improved solar array power may be extracted from spacecraft beginning-of-life to end-of-life operations due to low insertion loss of a direct energy transfer scheme.

Abstract: A photovoltaic inverter that can respond to changes in temperature and the amount of sunlight and that can automatically start up is provided, which has a simple configuration and is inexpensive. The photovoltaic inverter has a first voltage detection means for detecting an output voltage of a photovoltaic panel; a current detection means, a control means and a driving means. It further has a model voltage storage means for storing a model voltage table of inverter start-up kick voltages produced based on variation values of an amount of sunlight, a model voltage read-out means, a second voltage detection means for detecting an inverter start-up kick voltage, and an inverter start-up control means.

Abstract: A reverse current control system for first power converter having a synchronous rectifier and an output inductance includes a reverse current module. The reverse current module monitors a first voltage that is based on an output voltage of the output inductance and a second voltage that is based on an input voltage of the output inductance. The reverse current module anticipates a reverse current condition based on the first and second voltages. When the reverse current condition exists, the reverse current module prevents current from flowing in reverse through the power converter.

Abstract: A control signal generating circuit (1) comprises a comparator (10) for comparing an output voltage VO with a reference voltage outputted from a reference voltage source (11), a flipflop (12) set by the output of the comparator (10), and a pulse control circuit (13) which receives an input voltage VIN, a reference voltage VREF2, and the inverted output of the flipflop (12), sets the on time in accordance with the ratio between the input voltage VIN and the reference voltage VREF2, and resets the flipflop (12) when the on time elapses after the output pulse of the flipflop (12) rises. The output pulse of the flipflop (12) is outputted as a control signal into a driver logic circuit (2). The driver logic circuit (2) performs on/off control of NMOSs (3, 4) according to the control signal. Thus, a switching regulator capable of operating at high speed can be realized.

Abstract: A power factor correction circuit with buck and boost conversions has a rectifying circuit, a buck circuit and a boost circuit. When an input AC voltage of the power factor correction circuit is a relative low voltage, the AC voltage is converted to low level voltage by the buck circuit and then converted to an intermediate voltage with a desired level by the boost circuit. When the input AC voltage is a relative high voltage, the boost circuit is turned off. The input AC voltage is rectified and bucked to the intermediate voltage with a desired level.

Abstract: Single-phase full bridge boost converter systems and methods are provided. One system includes a direct-quatrature (D-Q) control system configured to generate a control voltage (vcon) including direct-phase and quadrature-phase voltage components. The system also includes a comparator configured to compare vcon to a carrier waveform voltage, generate switching commands based on the comparison, and transmit the switching commands to a current switch. Another system includes a boost converter including multiple switches coupled to a load and an AC voltage source. The switches are configured to provide charging current to the load in response to receiving switching commands. A D-Q control system configured to receive and delay an ia value, and issue switching commands based on the ia and delayed ia value is also included.

Abstract: Each of power supply units in a power supply system according to the present invention includes a power supply module, a voltage increase/decrease circuit for increasing the voltage across the power supply module and outputting the increased voltage to a load, and a control circuit. The control circuit calculates the power of the power supply module on the basis of the voltage across the power supply module and current flowing in the power supply module, outputs the power calculation result to a control circuit of another power supply unit, and generates and outputs a control signal to the voltage increase/decrease circuit on the basis of a target output voltage of the voltage increase/decrease circuit, the power calculation result, and a power calculation result obtained from a control circuit of a third power supply unit.

Abstract: A control unit controls cascaded PFC and LLC converters, the LLC converter having an input coupled to an output, of the PFC converter and providing an output voltage that decreases with increasing switching frequency. The control unit produces a sawtooth waveform with a linear ramp for controlling the LLC converter switching frequency, and hence its output voltage, in dependence upon a feedback signal. It also produces for the PFC converter a PWM signal with a frequency that is the same as or an integer fraction of the LLC converter switching frequency, by comparing two thresholds with the linear ramp in respective different cycles of the sawtooth waveform to turn on and off a switch of the PFC converter during these different cycles. Logic circuits prevent PFC converter switch transitions from occurring simultaneously with switching transitions of the LLC converter.

Abstract: A converter ECU (2) obtains allowable power total value including at least one of discharge allowable power total value ?Wout of discharge allowable power Wout1, Wout2 and charge allowable power total value ?Win of charge allowable power Win1, Win2. Then, the converter ECU (2) determines which of the allowable power total value and an actual power value is greater, If the actual power value is smaller than the allowable power total value, the converter ECU (2) controls a converter (8-1) such that an input/output voltage value Vh attains a prescribed target voltage value, and at the same time controls a converter (8-2) such that a battery current value Ib2 attains a prescribed target current value.

Abstract: According to one or more aspects of DC-to-DC voltage conversion as taught herein, a DC-to-DC converter selectively operates in a first mode wherein an included linear pass output circuit supplies the output power from the DC-to-DC converter, in a second mode wherein an included charge pump output circuit supplies the output power, and in a third mode wherein the linear pass and charge pump output circuits operate in parallel to supply the output power. With this third mode, also referred to as a “dual” mode, wherein the linear pass and charge pump output circuits operate in parallel, the DC-to-DC converter keeps the more efficient output circuit on after it has begun switching to operation with the less efficient output circuit. Such switchover may be performed dynamically in response to changing operating conditions. Detected operating conditions may include input voltages, output voltages, and output load conditions.

Abstract: For the purpose of providing a resonant switching power supply device having a wide output voltage variable range by changing its switching frequency, the resonance circuit thereof comprises a switching transformer, a first resonance section connected in series with the switching transformer, and a second resonance section connected in parallel with the switching transformer, wherein the resonance frequency characteristic in the case that the DC load current is large is formed using the series-connected devices of the first resonance section, and the resonance frequency characteristic in the case that the DC load current is small is formed using the first resonance section, the second resonance capacitor of the second resonance section and the switching transformer.

Abstract: A portable electrofusion machine includes: a power supply circuit having a triac configured to have a proper regulation for dropping a commercial voltage to a voltage adapted for a fitting; and a printer unit integrated with the electrofusion unit, for printing information regarding a work result of the fitting. According to the above construction, since the electrofusion machine does not use a transformer occupying 40% of a total weight of the machine, the mobility and portability are enhanced. Also, since the size of the machine is reduced, it is advantageous to deal with the machine on the spot.

Abstract: The present invention relates to a converter and a driving method thereof. The converter uses an input voltage to generate an output voltage by a main switch's switching and applies power to a load, senses the current flowing to the main switch to generate a sense voltage, uses a first voltage corresponding to the current applied to the load and a sawtooth waveform signal having a first frequency to control a group frequency of the burst mode, controls the main switch's turn-on timing, and uses the first voltage and the sense voltage to determine whether to turn off the main switch, thereby controlling the main switch's switching. The converter determines the start and end of the period for switching according to the result of comparing the first voltage and the sawtooth waveform signal. Therefore, a converter for having a constant group frequency, preventing audible noise, and preventing output voltage ripple, and a driving method thereof, are provided.

Abstract: A switching power source device is provided which comprises a drive controller 40 connected between an error amplifier 26 and changeover circuit 37. A second comparator 52 of drive controller 40 compares an output voltage or an equivalent signal thereto from error amplifier 26 with a numerical value from a sweep circuit 57 and produces an output to changeover circuit 37 to stop the on-operation of a switching element 4 and restrict an undesirable rise in output voltage during the light load period when the numerical value exceeds the output voltage or an equivalent signal thereto from error amplifier 26.

Abstract: The present invention provides a synchronous switching control circuit for variable switching frequency power converters. It comprises a first circuit to generate a first signal in response to an input synchronous signal of a power converter. A second circuit is coupled to the first circuit to generate a second signal in accordance with the frequency of the first signal. Only when the first signal is operated in a specific frequency range, the synchronous operation is allowed. An oscillation circuit is connected to the first circuit and the second circuit to receive the first signal and the second signal to generate an oscillation signal. The oscillation signal is utilized to enable the switching signal of the power converter. The switching signal is thus synchronized with the input synchronous signal in response to the enable of the second signal. Otherwise, the switching signal will be free running.

Abstract: A power supply control circuit includes: a conducting part configured to be controllable in its a conducting amount for conducting a power supply current to a load circuit; a current change ratio detecting part detecting a change rate of the power supply current supplied to the load circuit; and a control part controlling the conducting amount of the conducting part according to the change rate of the power supply current detected by the current change detecting part, wherein: the control part carries out feedback control of reducing an increasing rate of the conducting part as the power supply current change rate is larger.

Abstract: A power-factor improving circuit applicable to a switching power source apparatus includes a rectifier having a diode bridge, a step-up reactor, a switching element, an output diode, a smoothing capacitor, a controller, and a variable reference voltage generator. If an error voltage from a conductance amplifier exceeds a second reference voltage, a comparator provides a high-level switching signal to turn on a switching element and bypass a resistor. As a result, a first reference voltage supplied to the conductance amplifier is switched from a low reference voltage to a high reference voltage. This results in adjusting an output voltage (Vout) to a low value.

Abstract: The present invention relates to an LED array driving apparatus and a backlight driving apparatus using the same which enables regulation of analogue and PWM dimming for each channel and LED of a backlight, thereby allowing uniform luminance and color in all regions of backlight. The invention converts power with a constant voltage regulator to provide PWM pulse type power to the LED array having a plurality of LEDs connected in series. It regulates the on/off interval of the constant voltage regulator via a PWM dimmer to adjust the duty ratio of the PWM pulse. Further, it regulates the level of the driving current detected at the LED array via the feedback controller and analogue dimmer to apply to the constant voltage regulator by feedback process, thus regulating the amplitude of the PWM pulse.

Abstract: Provided is a DC-DC converter circuit which is stably operated without being affected by a size of an output capacitor (111) and a cost thereof. When a switching element is turned on so that a charge current that was flowing into an output capacitor flows into the switching element, the current is converted into a voltage to be added to an output voltage, and a resultant voltage is fed back to a control system.

Abstract: Provided is a constant voltage control apparatus capable of reducing feedback lines. In the constant voltage control apparatus, a first amplifier amplifies an output voltage applied to a pair of output terminals. A second amplifier amplifies a voltage drop between one of the output terminals and a load terminal connected thereto. A third amplifier amplifies output voltages from the first and second amplifiers, respectively. Comparing means receive an output voltage from the third amplifier and a reference voltage, and output an output voltage which makes a sum of the output voltage and the reference voltage of the third amplifier become zero. A triac drive unit amplifies the output voltage from the comparing means to control a triac installed on a power line that is connected with the first output terminal.

Abstract: When a switch (20) that is in series with the inductive load (10) is turned on, the rise behavior of the current (I) is first of all detected until a nominal value (Iref) is reached, and a pulse duty factor (Te/Ta) of a pulse width modulator device (30) is determined from said rise behavior. Immediately after the nominal value (Iref) of the current (I) has been reached, the switch (20) is driven in a conventional manner by the pulse width modulator device (30), using the pulse duty factor (Te/Ta) that has been determined, in order to finely adjust the pulse duty factor (Te/Ta). The invention largely avoids overshoots during control and the adjustment time is thus considerably shorter than in conventional drive circuits.

Abstract: A power supply for power factor correction and a driving method thereof wherein a ripple current of a power factor correction circuit (PFC) can be reduced to enhance a power factor and an efficiency. In the power supply, a power factor correction circuit corrects a power factor of a AC voltage supplied from an AC voltage source using a switching device to convert it to a DC voltage. A DC to DC converter converts said DC voltage from the power factor correction circuit into a desired DC voltage. A controller controls the switching device in accordance with an input voltage inputted to the power factor correction circuit to vary an output voltage of the power factor correction circuit.

Abstract: The present invention provides an inverter controller comprising a drive circuit that generates a plurality of switch drive signals for inverter applications. In some exemplary embodiments, the drive circuit operates by reversing the command level of an error signal. In other embodiments, the drive circuit operates by using a half period of a sawtooth signal. In still other embodiments, the drive circuit operates by using a double period opposite shifting pulses method. The present invention also provides a PWM signal generator circuit that generates periodic PWM switch drive signals symmetrical to the minimum or maximum of a sawtooth waveform.

Abstract: A power supply generates alternating current and direct current from a constant-voltage source. A multi-phase pulse width modulation voltage source inverter is connected across the source to output multi-phase alternating current. At least one waveform generator is bridged in parallel with the inverter, with each waveform generator outputting zero-sequence waveform current compensated to maintain the multi-phase current within a predetermined tolerance from a desired set point. A rectifier receives the waveform current and generates direct current.