# US 2019/0173392 A1 · Reconfigurable mmc sub-module unit and control unit thereof

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- Number: US 2019/0173392 A1
- Document ID: US20190173392A1
- Status: Published application
- Kind: A1
- Application number: 16/322,457
- Filed: 2017-08-02
- Published: 2019-06-06
- Earliest claimed: 2016-08-05
- Assignees: Nr Electric Co., Ltd; Nr Engineering Co., Ltd
- Applicants: Nr Electric Co., Ltd; Nr Engineering Co., Ltd
- Inventors: Gang LI; Jianchun LI; Jie TIAN; Haiying LI; Yu LU; Yunlong DONG; Zhaoqing HU; Minglian ZHU
- Web page: https://patentgrep.com/patent/US20190173392A1

## CPC

- H02M 7/4835: {comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage}
- H02M 7/483: Converters with outputs that each can have more than two voltages levels
- H02M 1/0003: {Details of control, feedback or regulation circuits}
- H02M 1/0095: {Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck}
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)

## Abstract

A reconfigurable MMC sub-module unit and a control unit thereof are provided, the reconfigurable MMC sub-module unit is mainly formed by an MMC sub-module unit and a reconfigurable mechanism, wherein the reconfigurable mechanism is formed by switches, and the conversion of MMC sub-module unit topology is achieved through switching on and off the switches in the reconfigurable mechanism. According to the reconfigurable MMC sub-module unit and the control unit thereof, the rapid change of a topology structure for a converter can be achieved, which is suitable for the demand of the line connection of the medium-voltage power distribution network and variable topologies, and meets requirements of dynamic simulation experiment for different converter topologies in the dynamic simulation experiment, thereby reducing construction costs and duration, improving experiment efficiency, and having high flexibility and strong versatility.

## Claims

### Claim 1

A reconfigurable MMC sub-module unit, characterized in that:
the reconfigurable MMC sub-module unit comprises an MMC sub-module unit and a reconfigurable mechanism, the reconfigurable mechanism comprises change-over switches, the reconfigurable mechanism is embedded to the MMC sub-module unit through electric connection lines or copper busbar, and a topology of the MMC sub-module unit is converted by switching on or off the change-over switches in the reconfigurable mechanism;
in the case of a full-bridge sub-module with a bypass switch, the reconfigurable mechanism in the reconfigurable MMC sub-module unit is formed by three change-over switches;
the full-bridge sub-module comprises four power semiconductor elements, a bypass switch, a voltage equalizing resistor and a capacitor, the power semiconductor elements each comprises an anti-parallel diode, an emitter of a first power semiconductor element and a collector of a second power semiconductor element are connected to a upper end of the bypass switch, an emitter of a third power semiconductor element and a collector of a fourth power semiconductor element are connected to a lower end of the bypass switch, a collector of the first power semiconductor element and a collector of the third power semiconductor element are connected to a positive end of the capacitor, a emitter of the second power semiconductor element and a emitter of the fourth power semiconductor element are connected to a negative end of the capacitor, a upper end of the voltage equalizing resistor is connected to the positive end of the capacitor and the lower end of the voltage equalizing resistor is connected to the negative end of the capacitor;
the reconfigurable mechanism is embedded to the full-bridge sub-module, one end of a first change-over switch is connected to the negative end of the capacitor of the full-bridge sub-module, the other end of the first change-over switch is connected to the lower end of the bypass switch and one end of a second change-over switch; an other end of the second change-over switch is connected to a middle point of a bridge arm of the third power semiconductor element and the fourth power semiconductor element of the full-bridge sub-module, and the one end of the second change-over switch is connected to the lower end of the bypass switch and one end of the first power semiconductor element; one end of the third change-over switch is connected to the collector of the first power semiconductor element, the positive end of the capacitor and a negative end of the voltage equalizing resistor of the full-bridge sub-module, and the other end of the third change-over switch is connected to the collector of the third power semiconductor element of the full-bridge sub-module.

### Claim 2 (depends on 1)

The reconfigurable MMC sub-module unit according to claim 1, characterized in that: the reconfigurable mechanism is formed by the first change-over switch, the second change-over switch and the third change-over switch, wherein the first change-over switch is connected in parallel to the negative end of the capacitor and a low-voltage outlet of the full-bridge sub-module, the second change-over switch is connected in series to the low-voltage outlet of the full-bridge sub-module, and the third change-over switch is connected in series to the collector of the first power semiconductor element and the collector of the third power semiconductor element of the full-bridge sub-module.

### Claim 3

A control unit including a reconfigurable MMC sub-module unit, characterized in that: a secondary control and protection unit is connected to control ends of power semiconductor elements, switching elements and change-over switches of conversion structures of the reconfigurable MMC sub-module unit, respectively; switching on and off of the change-over switches are controlled by a control system to realize a change of topological structure of the sub-module unit; switching on and off of the power semiconductor elements are controlled by the control system to realize operation of converters of different topologies. and
a half-bridge sub-module topology is formed by closing a first change-over switch of the change-over switches, and turning off a second change-over switch and a third change-over switch of the change-over switches.

### Claim 4

(canceled)

### Claim 5 (depends on 3)

The control unit including a reconfigurable MMC sub-module unit according to claim 3, characterized in that: a full-bridge sub-module topology is formed by closing a second change-over switch and a third change-over switch of the change-over switches, and turning off a first change-over switch of the change-over switches.

### Claim 6 (depends on 3)

The control unit including a reconfigurable MMC sub-module unit according to claim 3, characterized in that: a quasi-full-bridge sub-module topology is formed by closing a second change-over switch and a third change-over switch of the change-over switches, turning off a first change-over switch of the change-over switches, and continuously sending a turn-on command to a third power device T3 transistor.

### Claim 7 (depends on 3)

The control unit including a reconfigurable MMC sub-module unit according to claim 3, characterized in that: a method of converting from full-bridge or quasi-full-bridge topology to half-bridge topology is to close a first change-over switch and open a second change-over switch and a third change-over switch at the same time.

### Claim 8 (depends on 1)

A reconfigurable converter formed by the reconfigurable MMC sub-module unit according to claim 1, characterized in that: the reconfigurable converter comprises several reconfigurable MMC sub-module units, a first end of the reconfigurable MMC sub-module unit is defined as a leading-out end from a midpoint of a bridge arm of the first power semiconductor element and the second power semiconductor element of the reconfigurable MMC sub-module unit, and a second end of the reconfigurable MMC sub-module unit is defined as a leading-out end from a joint of the bypass switch, the first change-over switch and the second change-over switch of the reconfigurable MMC sub-module unit, the several reconfigurable MMC sub-module units are formed into a MMC converter by cascading the first end of a reconfigurable MMC sub-module unit and the second end of an adjacent MMC sub-module unit sequentially in the same direction; by controlling the change-over switches of the reconfigurable sub-module units in the converter, a half-bridge MMC converter, a full-bridge MMC converter, a quasi-full-bridge MMC converter, or a half-bridge and full-bridge hybrid MMC converter is formed.