1178 results about "Three-phase" patented technology

Embodiments of this invention discloses a split-phase output power adjustment system, adjustment method, and storage medium in a low voltage transformer area. The system includes adjustment power supplies, split-phase power adjustment modules, sub-controllers, a main controller. The adjustment power supplies connected to the split-phase power adjustment modules, and total power P of the adjustment power supplies complying with a relationship as follows: P=Pt=PG1+PG2+ . . . . PGn; wherein Pt is power required to comply with three-phase current unbalance adjustment of a distribution transformer, PG1, PG2, . . . PGn is power generated by each of the adjustment power supplies to compensate three-phase current unbalance in a transformer area; wherein the split-phase power adjustment modules are connected to lines of three phases A, B, and C and a neutral line N in the transformer area; wherein the sub-controllers are connected to the adjustment power supplies, and the sub-controllers communicate with the main controller to control power generated by each of the adjustment power supplies, so as to compensate the unbalanced three-phase current in the transformer area. Coordinated adjustment of multiple distributed power supplies realizes precise control of three-phase imbalance in the transformer area, which reduces line loss and improves power quality.

The invention relates to the technical field of power generation, power transformation or power distribution, and discloses a control method for preventing overload of an energy storage system transformer, which comprises the following steps: monitoring the three-phase total power and the power of each phase of a power grid side ammeter in real time, and calculating the three-phase unbalance degree based on the three-phase total power when the three-phase unbalance phenomenon occurs; when the three-phase unbalance degree is greater than a preset unbalance degree threshold value, dynamically adjusting the charging power of the energy storage converter according to a starting threshold value, a charging limiting threshold value and a charging forbidding threshold value by adopting a multi-threshold value dynamic adjustment mechanism; the phase with the maximum deviation between the power of each phase and the average power of the three phases is calculated as an overload phase, load reduction is performed on the overload phase based on a load increasing and decreasing strategy, load increasing is performed on a non-overload phase, and the adjusted three-phase power is obtained; a power distribution instruction is calculated in real time in combination with a dynamic response mechanism, and the three-phase unbalance degree does not exceed a safety threshold value in cooperation with total power control. The problems of easy overload, three-phase imbalance and slow response of a transformer in the prior art are solved, and the purposes of accurate load control, high system stability and high response speed are achieved.

The present application discloses a three-phase-power-based power supply circuit and a method for same to simultaneously realize power factor correction and dynamic voltage boosting / reduction. The circuit comprises an information collection module and a power supply circuit unit, wherein the power supply circuit unit comprises three circuit groups formed by connecting to three phases of three-phase power and a control center used for controlling the working states of the three circuit groups. Each circuit group comprises an input rectification module, an inductor, a capacitor, a switch and a controller thereof, a transformer, and an output half-wave rectification module. Output ends of the three circuit groups comprised in the power supply circuit unit are connected in parallel or in series, thereby solving the ripple problem, and also improving the electric energy conversion rate. The power supply circuit can control the charging and discharging time of an inductor by performing high-frequency adjustment on the magnitude of an input current peak and further adjusting the frequency and duty ratio of a switch, such that the dynamic adjustment of voltage boosting and voltage reduction is realized while realizing power factor correction, the load requirements are met, costs can be effectively saved on, the energy loss is low, and the electric energy conversion rate is high.

The invention provides a low-modulation-ratio topological high-reliability high-voltage direct-hanging energy storage system and method.The system comprises three phases of energy storage unit chains, each phase of energy storage unit chain is formed by cascading a plurality of energy storage units, and the connecting ends of the three phases of energy storage unit chains are sequentially connected with an alternating current side filter inductor in series and then connected with a power grid; the energy storage unit comprises an H-bridge power unit, a bus capacitor, a direct current side filter inductor, a battery side pre-charging device, a direct current side contactor and a battery cluster; the direct current side positive electrode of the H-bridge power unit is sequentially connected with the direct current side contactor, the battery side pre-charging device, the battery cluster and the direct current side filter inductor in series and then is connected with the direct current side negative electrode of the H-bridge power unit, and the alternating current side positive electrode of the H-bridge power unit is sequentially connected in series. According to the invention, the high-voltage direct-hanging energy storage system can fully utilize the DC voltage redundancy to realize the frequency doubling current suppression of the battery cluster by utilizing the low modulation ratio characteristic, and the ripple current pulsation amplitude of the battery meets the national standard requirement under the condition that the device cost is not increased.

The invention relates to a charging cable (1) for charging an electric vehicle, the charging cable comprising at least five electrical conductors, including three phase conductors (L1, L2, L3) and one neutral conductor (N), the cable extending between a first end (E1) and a second end (E2), characterized in that the phase conductors have at least two different cross-sections, including a first cross-section and a second cross-section smaller than the first cross-section, and in that the first phase conductor (L1) has the first cross-section as its cross-section, the second phase conductors (L2) and the third phase conductors (L3) have the second cross-section as their cross-section, and the neutral conductor (N) has the first cross-section as its cross-section. Figure 2

The invention discloses a distributed grounding line selection method and system based on phase current abrupt change, and the method comprises the steps: obtaining three-phase current of a line, and calculating a phase current abrupt change real-time value, a phase current abrupt change derivative and a phase current abrupt change effective value in the three-phase current; judging whether the phase current break variable derivative and the phase current break variable effective value meet a preset phase current break variable starting condition or not in a continuous first time period; if the preset phase current abrupt change starting condition is met, whether the phase current abrupt change line selection action in a continuous second time period meets a preset phase current abrupt change line selection action condition or not is judged; and if a preset phase current break variable line selection action condition is met, determining that the line has a single-phase earth fault and the fault phase in the line is the phase with the maximum current break variable in the three phases. And a single-phase earth fault line can be quickly positioned.

The low-power fast wake-up band-gap reference voltage circuit operates in three phases: dormant, wake-up, and steady-state phases. The circuit enters wake-up subsequent to receipt of an enable signal which causes a one-shot timer to generate a slew enable signal pulse having a predetermined period. To a band-gap voltage reference circuitry comprising an operational amplifier, there is connected, at the wake-up phase, a boost circuitry, operative under the control of the slew enable signal that connects one or more of the one or more boost circuits to a band-gap voltage reference. Thereby, during the brief wake-up phase, more current is consumed to accelerate the response of the circuit. Upon completion of the wake-up phase the boost circuitry is disconnected under the control of the slew enable signal and for as long as the enable signal is active, the circuit is operative in a low-power mode.

The invention discloses an MMC sub-module fault processing method, device and equipment and a storage medium, and the method comprises the steps: obtaining the capacitor voltage value of a sub-module of an MMC and the bridge arm current value of the sub-module, the MMC comprises six bridge arms of three phases, each bridge arm comprises a plurality of sub-modules, the capacitor of each sub-module is connected with an equivalent series resistor in series, and further, the equivalent series resistor is connected with the capacitor voltage value of the sub-module of the MMC; the resistance value of an equivalent series resistor in the sub-module is monitored through the capacitor voltage value and the bridge arm current value, if the resistance value of the equivalent series resistor is higher than a preset resistance value, it is determined that the capacitor of the sub-module fails, fault-tolerant control is carried out on the sub-module through a voltage-sharing and circulating current suppression algorithm, a three-phase switching signal is output, and the three-phase switching signal acts on the MMC. Therefore, the circulating current fundamental frequency component and the double frequency component caused by fault-tolerant control after the fault can be eliminated through the circulating current suppression strategy, the effect of circulating current suppression is achieved, and the stability of system fault operation is improved.

An energy self-balancing flexible direct-current converter valve, a control method, and a direct-current system, which relate to the technical field of power transmission and distribution networks. The converter valve comprises three phase units, and each phase unit comprises an upper leg and a lower leg. The upper legs and the lower legs each comprise a plurality of full-bridge energy self-balancing submodules and a plurality of half-bridge energy self-balancing submodules. Each of the full / half-bridge energy self-balancing submodules is an optimized MMC submodule comprising an energy self-balancing circuit. The energy self-balancing circuit is composed of a power electronic switch and an energy dissipation resistor connected in series, and is used for dissipating surplus energy when an overvoltage early warning occurs for the capacitor voltage of the submodule. The present application, without affecting the operational logic of conventional converter valves and at low costs, can solve the technical problem of surplus power not being dissipated promptly due to faults occurring in a direct-current power transmission system in a new energy islanded ultra-long-distance direct-current delivery scenario. Meanwhile, temporary energy stored in the capacitors of the optimized MMC submodules can be fully utilized, reducing the waste generated by surplus power dissipated as heat.

The invention provides a platform area power grid tail end voltage flexible regulation and control method and system. The method comprises the steps that a sampling module measures common coupling point voltage at the tail end of a platform area power grid; the impedance calculation unit obtains load end impedance; the current calculation unit calculates the current of the common coupling point through the voltage of the common coupling point and the impedance of the load end; the current resolving unit is used for resolving the common coupling point current into negative-sequence current and zero-sequence current; the compensation current unit calculates a compensation current component required for maintaining the stability of the voltage at the tail end of the transformer area power grid through the negative-sequence current and the zero-sequence current; the PWM unit generates a compensation current control signal; and the IGBT module outputs compensation current to the common coupling point. When three phases are unbalanced, the first disturbance generation circuit accurately injects a disturbance signal to effectively regulate and control the voltage at the tail end of a power grid in a transformer area; and the second disturbance generation circuit analyzes the stability of the tail end of the station area power grid by using coordinate transformation and a PI controller.

The invention provides a power fluctuation suppression method and system based on two-phase virtual phase current regulation and control. The method comprises the steps that S1, a grid-connected current model and a direct-current bus power fluctuation model are constructed; a two-phase virtual phase current regulation and control technology is introduced into the grid-connected current model; the DC bus power fluctuation model corresponds to the grid-connected current model; s2, optimizing a direct current bus power fluctuation model; and S3, solving the optimized direct current bus power fluctuation model to complete the complete suppression of the power fluctuation. On the basis of the single-phase VPCR technology, one of the phases without voltage drop in the three phases is additionally selected as an auxiliary compensation phase, optimization calculation of a two-phase virtual phase current gain coefficient is carried out through a particle swarm optimization algorithm, it is proved from the theoretical level that the two-phase VPCR technology can achieve minimization and zero of direct-current side power fluctuation, and the method is suitable for large-scale popularization and application. The traditional engineering requirements are met, and the design defect of the gain coefficient of the single-phase VPCR technology is improved.

Disclosed in the present invention is a state of charge (SOC) balancing method for an energy storage MMC based on capacitor voltage correction, comprising the following steps: acquiring important parameters such as the SOCs of energy storage units and current directions of bridge arms in an energy storage MMC; calculating SOC average values of phase units, of the bridge arms, and of three phases of energy storage units; calculating the inter-phase SOC imbalance degree, the inter-bridge arm SOC imbalance degree, and the inter-submodule SOC imbalance degree, obtaining an inter-phase power deviation, an inter-bridge arm power deviation, and an inter-submodule voltage deviation by means of a proportional controller, and calculating a submodule energy storage power reference value and submodule corrected capacitor voltages; calculating the duty cycle of a switching device in a bidirectional DC / DC converter; and sorting the submodule corrected capacitor voltages, and on the basis of the charging / discharging state of submodule capacitors, determining submodules to be connected. The present invention can realize SOC balancing of energy storage MMCs, and reduces the number of bidirectional DC / DC converter controllers, thereby improving the SOC balancing efficiency and the capacity utilization rate of energy storage units.

The invention discloses a power supply circuit and electrical equipment. The power supply circuit comprises a three-phase power supply and three rectification and inversion modules, wherein each rectification and inversion module comprises a first input end, a second input end and an output end; the first input ends of the three rectification inversion modules are respectively connected to three phase lines in a three-phase power supply in a one-to-one correspondence manner; second input ends of the three rectification inversion modules are connected to a neutral line in the three-phase power supply; the output ends of the three rectification inversion modules are respectively connected to three loads in a one-to-one correspondence manner; and the rectifying and inverting module is used for sequentially rectifying and inverting the input voltage and then supplying power to corresponding loads. According to the invention, the three-phase power supply is divided into three independent single-phase power supply paths for three loads, single-phase rectification is carried out on each phase independently, the voltage level is reduced, a low-voltage-level device can be selected, and the cost is reduced; the three-phase load is balanced, the harmonic dispersion is realized, and the harmonic pollution is reduced; fault area isolation is realized, and maintenance difficulty and maintenance cost are reduced.

The invention relates to the field of voltage data processing, in particular to a voltage data processing method and device for zero point detection and a direct current brushless motor. The method comprises the following steps: respectively monitoring and acquiring voltage values of U, V and W phases; if the voltage value of one preset period is accumulated in each phase, generating a first change diagram, and calculating a first deviation value according to the generated first change diagram; translating a curve graph in the first change graph to obtain a second change graph, and calculating a second deviation value according to the second change graph; obtaining a preset number of first change diagrams corresponding to the preset periods of which accumulation is completed, and calculating a third deviation value according to the obtained first change diagrams; obtaining a fourth deviation value according to the first deviation value, the second deviation value and the third deviation value; and in the next preset period of the preset period T, correcting the latest acquired voltage values of the three phases according to the fourth deviation value to obtain corrected voltage values of the three phases. According to the invention, the problem of insufficient accuracy of voltage data is solved.

The invention relates to a closing buffer of a vacuum circuit breaker. The closing buffer comprises phase columns, a cross beam, a spring operating mechanism and a bracket, the three phase columns are arranged at the top end of the cross beam in parallel, and the top end of the support is connected to the lower surface of the cross beam and used for supporting the cross beam. The spring operating mechanism is mounted on the lower surface of the cross beam, and the spring operating mechanism is linked with the vacuum arc extinguish chamber in the phase column through a transmission module; through specially designed guiding and spring contact force values, functional requirements of guiding and contact pressure providing are realized. A closing buffer is additionally arranged in the spring contact, damping of a rigid closing point is increased through the buffer, energy of collision bounce of the rigid closing point is absorbed, and therefore bounce is restrained.

The invention relates to a three-phase imbalance treatment method and a micro-energy regulator, and belongs to the technical field of power supply systems. The method comprises the steps that when a three-phase imbalance phenomenon occurs, the three-phase imbalance degree is obtained according to the maximum power deviation between phases and the total power of the three phases; when the three-phase unbalance degree is greater than a preset unbalance degree, calculating the single-phase power deviation of each phase according to the three-phase average power and the single-phase power of each phase; comparing the three-phase total power with a preset transformer area load rate, and when the three-phase total power is greater than the preset transformer area load rate, storing energy and discharging; if yes, the single-phase power deviation needs to be updated according to corresponding design requirements; for energy storage, the total discharge power or the total power absorption power of each phase is determined according to the updated single-phase power deviation, proportional gain and integral gain; and discharging or absorbing electricity for each phase until the total discharging power or the total electricity absorbing power of each phase is met. According to the invention, the phenomenon of heavy load or return of the transformer area can be reduced.

An electric machine includes a stator core defining slots having a number of radial positions. A winding is disposed in the core and has three phases, each of the phases having at least two parallel paths including hurdle-shaped conductors interconnected to form at least two continuous circuits between a terminal and a neutral. Each of the hurdle-shaped conductors have first and second uprights disposed in a different one of the slots and a bridge connecting between the uprights and extending circumferentially over an end surface of the core, wherein the bridges are stacked one on top of the other such that the winding has upper and lower layers. The bridges have variable thickness such that a number of bridges, at each of the upper and lower layers, extending over one of the slots exceeds the number of radial positions of that slot.

The invention relates to a composite voltage regulation device and a control method and device thereof, a first incoming line connection port is connected with the head end of the primary side of a parallel transformer, three phases of the tail end of the primary side of the parallel transformer are connected to form a neutral point, each phase of the secondary side of the parallel transformer comprises a plurality of secondary windings, each secondary winding comprises three taps, and the taps are connected with the primary side of the parallel transformer. The taps are connected to the secondary side of the series transformer through a voltage regulating mechanism and an on-load voltage regulating switch in sequence, and the two ends of the primary side of the series transformer are connected with a second incoming line connecting port and the head end of the primary side of the parallel transformer respectively; and the control protection device is used for controlling the conduction state of the voltage regulating mechanism and / or the connection relation between the on-load tap changer and each gear of the secondary side of the series transformer based on the real-time power at the wire inlet of the composite voltage regulating device and the received power flow transfer instruction. According to the scheme, the requirements of the power flow adjustment precision and the power flow adjustment range are met through online adjustment, and then the dynamic voltage adjustment requirement of the power distribution network is met.

The invention discloses a power information cooperative modulation method based on a buck DC converter, and relates to the technical field of power information cooperative modulation. According to the method, power information cooperative modulation is carried out by combining the structural characteristics of the three-phase interleaving buck type direct-current converter, the amplitude and phase characteristics of output voltage ripples are changed by adjusting the carrier phase offset according to the inherent phase relation that three phases of the three-phase interleaving buck type direct-current converter are interleaved by 120 degrees, and modulation of information coding is achieved. Unification of the phase shift keying switching frequency is realized, the performance of power transmission and information interaction is improved, and the ripple amplitude fluctuation range is relatively small. When a plurality of converters operate in parallel, the ripple amplitude of the converter in a non-communication state approaches zero, so that interference on information demodulation of the converter at a communication end can be avoided, an orthogonal switching frequency switching strategy does not need to be adopted, the system complexity is effectively reduced, and the applicability is improved.

The invention discloses a power regulation method and device and energy storage equipment, which are applied to a transformer area, the transformer area comprises three phase lines A, B and C and at least one energy storage equipment, each energy storage equipment is respectively connected with the three phase lines, the energy storage equipment is used for regulating and controlling the voltage of the phase lines, and for each phase line connected with any energy storage equipment, the voltage of each phase line is regulated and controlled. The method comprises the steps of determining a voltage deviation value of a phase line based on a first voltage value and a reference voltage value of the phase line at a current sampling moment; obtaining a first output power and a power adjustment step length of the energy storage device at a previous sampling moment, wherein the power adjustment step length is a power adjustment value used when the first output power is generated at the previous sampling moment; and determining second output power of the energy storage equipment at the current sampling moment based on the power adjustment step length, the first output power and the voltage deviation value. The technical problem of how to adjust the energy storage system to stabilize the voltage of the transformer area when the voltage of the transformer area is in an unstable state is solved.

The invention relates to the technical field of power monitoring, in particular to a concentrator with an electrical equipment state monitoring function. Obtaining an unbalance degree according to the state characteristic values among the three phases; clustering is carried out according to the unbalance degree of all historical moments, and distribution intensity is obtained according to interval characteristics of different moments in a moment cluster; obtaining a data similarity according to the unbalance degree in the time cluster; obtaining reference credibility according to the moment quantity characteristics, the distribution intensity and the data similarity in the moment cluster; according to the difference characteristic of the unbalance degree corresponding to the current moment and the reference moment cluster and the reference credibility of the reference moment cluster, obtaining the abnormity degree; and obtaining an anomaly trend value according to the anomaly degree of the adjacent historical time period of the current moment. The early warning index of the current moment is obtained according to the abnormity degree and the abnormity trend value, and early warning is carried out, so that the monitoring accuracy of the concentrator on the power utilization state of the electrical equipment is improved.

The invention provides a braking rotating device with a power generation function, a self-powered rotating system, a control method and a wire cup, and the braking rotating device comprises a stator part which comprises three groups of coils arranged at intervals in the circumferential direction; the rotor part rotates coaxially with the stator part and comprises a plurality of magnets which are arranged at intervals in the circumferential direction and have alternately changed polarities; the self-power-generation brake part generates power based on rotation of the rotor part relative to the stator part and performs brake control on the rotor part based on a received brake signal, the self-power-generation brake part comprises a three-phase rectifier bridge circuit, and three phase current ends of the three-phase rectifier bridge circuit are respectively connected with the three groups of coils; at least one phase of the three-phase rectifier bridge circuit is provided with a switching device, at least one phase of the three-phase rectifier bridge circuit is not provided with a switching device, and when an enabling end of the switching device receives a brake signal, a phase current end of the phase where the switching device is located and a common anode or a common cathode of the three-phase rectifier bridge circuit are conducted.

The invention relates to the technical field of high-voltage cascade energy storage systems, and discloses a high-voltage cascade energy storage system based on nested power modules and a control method thereof.The high-voltage cascade energy storage system comprises three phases of chain type energy storage bridge arms connected with three phase lines of a power grid respectively, and each phase of chain type energy storage bridge arm comprises a plurality of cascaded nested power modules; each nested power module comprises a plurality of direct-current chain type energy storage units and an H-bridge circuit, the plurality of direct-current chain type energy storage units are connected in parallel and then are connected with the direct-current side of the H-bridge circuit, and the alternating-current side of the H-bridge circuit is connected with an alternating-current switch; the direct current chain type energy storage unit comprises a plurality of energy storage modules, an electric reactor and a direct current switch, the plurality of energy storage modules are cascaded and then are sequentially connected with the electric reactor and the direct current switch, each energy storage module comprises a battery pack and a half-bridge circuit connected with the battery pack, and the half-bridge circuit is used for charge state balance control of the battery pack. According to the invention, any battery pack can be bypassed after a fault, and the operation reliability of the high-voltage cascade energy storage system is improved.

The invention discloses a switch reluctance motor five-level power converter capable of simplifying the number of switch tubes, which belongs to the technical field of switch reluctance motor control and comprises an energy storage capacitor module, a switch tube module of each of three phases and common phases, a transverse switch tube module and a diode module. A common phase is added under the traditional three-phase condition, each phase and the common phase are connected with an inductor to simplify a bridge arm, a full-bridge structure is used for replacing an asymmetric half-bridge, the use of diodes is reduced, meanwhile, the number of switching tubes of each phase is reduced, and five-level output of the circuit is achieved through the common phase; meanwhile, a six-module IGBT can be used as a three-phase switch tube, a double-module IGBT can be used as a common phase, and a diode module can be used as a switch tube led out from the midpoint of the capacitor, so that the number of required single modules is greatly reduced, the control method can be simplified, the reliability is higher, and the switching loss is smaller.

A power storage system includes: a battery including a first power storage, a second power storage, and a first switch unit; a three-phase motor in which coils of three phases are connected at a neutral point, the three-phase motor being driven by electric power supplied from the battery; an inverter connected on an electric power transmission path between the battery and the three-phase motor; a DC power supply circuit connected to a first connection portion positioned on an electric power transmission path between the inverter and the battery; a capacitor provided on the electric power transmission path between the battery and the three-phase motor; and a branch circuit that branches off from the DC power supply circuit on a positive electrode side and is connected to a coil of any one phase among the coils of three phases. The first switch unit includes a semiconductor switch.

The invention discloses a modular alternating support current converter without a bridge arm inductor and a modulation method thereof, and relates to the technical field of power electronics. According to the modular alternate support converter, a new modular alternate support converter topology is provided by reconstructing an operation mode of a traditional MMC, and the modular alternate support converter comprises three phase units; each phase unit comprises an upper bridge arm and a lower bridge arm which are connected in series; each bridge arm comprises N submodules which are connected in series; two ends of each phase unit serve as positive and negative poles of a direct-current end; the midpoint of the phase unit is connected with an AC filter inductor as a connecting end of three-phase power; the anode of the DC end is provided with a DC filter inductor. According to the modularized alternating supporting converter, a filter inductor does not need to be additionally arranged on a bridge arm, the modularized alternating supporting converter has the large capacity reduction amplitude and power density, the size is small, the power density is high in the corresponding alternating operation mode, the engineering implementation difficulty is low due to the full-modularized design, and good economical efficiency is achieved.

The invention relates to a single-loop control method for a static synchronous phase modifier, which belongs to the technical field of power systems, and comprises the following steps of: comparing a maximum voltage difference value in three phases with a preset voltage threshold value to obtain a voltage difference value after amplitude limiting, and obtaining a first virtual reactance by using the voltage difference value after amplitude limiting and a preset current amplitude limiting threshold value; performing proportional integral control on the difference between the maximum current value in the three phases and the current amplitude limiting threshold to obtain a second virtual reactance; virtual impedance is calculated according to the first virtual reactance and the second virtual reactance; the product of the virtual impedance and the current of each phase is used as the current amplitude limiting voltage of the corresponding phase; the modulation wave of the corresponding phase is generated by using the internal potential and the current amplitude limiting voltage of each phase, so that the voltage single-loop control and the fault current amplitude limiting of the static synchronous phase modifier are realized, the broadband oscillation risk and the overcurrent risk of the converter are effectively reduced, and the safety and the reliability of static synchronous phase modifier equipment are improved.

A power system architecture configured to power a transport refrigeration system (20) based on a determined an AC power requirement. The system (20) includes a generator power converter (164) configured to receive the generator three phase AC power (163) from an AC generator (162), and provide a generator DC power (165). The system (20) also includes a grid power converter (184) configured to receive the grid three phase AC power from a grid power source (182), and provide a grid DC power (185), an energy storage device (152), the energy storage device (152) operable to provide a DC power (157) and connected to a variable DC bus, and a power management system (190) operably connected to direct power (195) the TRU (26) based on at least the AC power requirement.

Common mode voltage discharge shields are disposed over end turns of stator windings for a three phase electric traction motor within an electric vehicle. The common mode voltage discharge shields are capacitively coupled to the end turns to a ground strap, providing a low impedance path for common mode voltages accumulating at a neutral for electric traction motor as a result of high frequency switching of the motor drive voltage to produce desired torque. An insulating layer separates the common mode voltage discharge shields from the end turns. Accumulation of the common mode voltage in excess of a bearing breakdown voltage, and the associated potential for discharge through bearings between the stator and rotor and electrical discharge machining, is reduced or eliminated.

To provide a modular multilevel cascade converter in which power duty in each phase can be intentionally unbalanced without causing a flow of a reverse phase current.SOLUTION: A modular multilevel cascade converter in which one phase module is formed by connecting in series, between both ends of a cell capacitor, a plurality of bridge cells each formed by bridge connecting a plurality of semiconductor switching elements, and three phases of the module are included and are connected to a three-phase AC system, comprises a control unit that calculates a zero-phase voltage on the basis of a system-side phase voltage detection signal and output power command values of the respective phases (calculator 44), superimposes the calculated zero-phase voltage on a phase voltage detection signal (adder 58), adds a phase voltage on which the zero-phase voltage has been superimposed on a phase voltage outputted as a result of current control based on a current command value by an adder 59 to obtain output voltage command values of the respective phases, and generates a gate signal of each semiconductor switching element in each bridge cell on the basis of the output voltage command value of each phase.SELECTED DRAWING: Figure 5