阅读说明：本技术 具有不对称半导体额定值布置的功率模块和转换器 (Power module and converter with asymmetric semiconductor rating arrangement ) 是由 佘煦 I·阿格曼 于 2020-11-24 设计创作，主要内容包括：本申请涉及具有不对称半导体额定值布置的功率模块和转换器。提供用于操作整流器的系统。这些方面包括整流器,该整流器包括：桥式结构的集合,所述桥式结构配置成接收电源的输入电流,其中桥式结构的集合中的每个桥式结构包括二极管的集合和有源开关的集合,其中有源开关的集合中的每个有源开关配置成当处于PWM状态中时提供围绕二极管的集合中的每个二极管的并行通路；控制器,其配置成确定用于整流器的阈值电流,并且基于输入电流小于阈值电流来将整流器中的一个或多个有源开关操作在PWM状态中。(The present application relates to power modules and converters with asymmetric semiconductor rating arrangements. A system for operating a rectifier is provided. These aspects include a rectifier comprising: a set of bridge structures configured to receive an input current of a power supply, wherein each bridge structure of the set of bridge structures comprises a set of diodes and a set of active switches, wherein each active switch of the set of active switches is configured to provide a parallel path around each diode of the set of diodes when in a PWM state; a controller configured to determine a threshold current for the rectifier and operate one or more active switches in the rectifier in a PWM state based on the input current being less than the threshold current.)

1. A power device assembly, comprising:

one or more active switches;

one or more diodes;

wherein each of the one or more active switches is in parallel with a corresponding diode of the one or more diodes; and

wherein each active switch of the one or more active switches comprises a first current rating;

wherein each diode of the one or more diodes comprises a second current rating;

wherein the first current rating is at least one order of magnitude less than the second current rating.

2. The power device of claim 1, further comprising:

a controller configured to:

determining a threshold current for the power assembly; and

operating one or more active switches in a Pulse Width Modulation (PWM) state based on the input current being less than the threshold current.

3. The power device assembly of claim 2, wherein the controller is further configured to:

operating the one or more active switches in an off state based on the input current exceeding the threshold current.

4. The power device assembly of claim 1, further comprising a power supply comprising a three-phase power supply configured to supply three input currents to the one or more diodes and the one or more active switches.

5. The power device assembly of claim 1, wherein the one or more active switches comprise Insulated Gate Bipolar Transistors (IGBTs).

6. A system comprising

A rectifier comprising the following set:

a plurality of bridge structures configured to receive an input current of a power supply, wherein each bridge structure of the plurality of bridge structures comprises a plurality of diodes and a plurality of active switches, wherein each active switch of the plurality of active switches is configured to provide a parallel path around each diode of the plurality of diodes when in a PWM state;

a controller configured to:

determining a threshold current for the rectifier; and

operating one or more active switches in the rectifier in a PWM state based on the input current being less than the threshold current.

7. The system of claim 6, wherein the controller is further configured to:

operating the plurality of active switches in each of the rectifiers in an off state based on the input current exceeding the threshold current.

8. The system of claim 6, wherein the power source comprises a three-phase power source configured to supply three input currents to the rectifier.

9. The system of claim 6, wherein the plurality of active switches comprise Insulated Gate Bipolar Transistors (IGBTs).

10. The system of claim 9, wherein a current rating of the plurality of active switches is an order of magnitude less than a current rating of the plurality of diodes.

11. The system of claim 6, further comprising a plurality of bi-directional switches coupled to the plurality of bridge structures.

12. The system of claim 6, wherein each bidirectional switch comprises two IGBTs and two diodes.

13. The system of claim 6, wherein the plurality of bridge structures comprise half-bridge structures.

14. The system of claim 6, wherein the plurality of bridge structures comprises a full bridge structure.

15. The system of claim 6, wherein the plurality of bypass switches comprise Metal Oxide Semiconductor Field Effect Transistors (MOSFETs).

16. A system, comprising:

a rectifier comprising a first bridge structure configured to receive an input current from a power source, wherein the first bridge structure comprises:

a first diode and a second diode;

a first active switch and a second active switch, wherein the first active switch provides a first parallel path around the first diode when in a PWM state; and wherein the second active switch provides a second parallel path around the second diode when in the PWM in-state; and

a controller configured to:

determining a threshold current for the rectifier; and

operating the first active switch in the rectifier in a PWM state based on the input current being less than the threshold current.

17. The system of claim 16, wherein the controller is further configured to:

operating the first active switch in the rectifier in an off state based on the input current being less than the threshold current.

18. The system of claim 16, wherein the power source comprises a three-phase power source configured to supply three input currents to the rectifier.

19. The system of claim 16, wherein the first active switch comprises an Insulated Gate Bipolar Transistor (IGBT).

20. The system of claim 19, wherein a current rating of the first active switch is an order of magnitude less than a current rating of the first diode.

Technical Field

Exemplary embodiments relate to the field of AC-DC converters, and more particularly to power modules and converters having an asymmetric semiconductor rating (rating) arrangement.

Background

A chiller is a machine that removes heat from a liquid via a vapor compression or absorption refrigeration cycle. This liquid can then be circulated through a heat exchanger to cool equipment or another process stream (e.g., air or process water). As a by-product, refrigeration creates waste heat that must be either discharged to the environment or recovered for heating purposes for greater efficiency. In air conditioning systems, cooling water is typically distributed to heat exchangers or coils in an air handler or other type of terminal equipment that cool the air in its respective space(s). The water is then recirculated to the cooler for re-cooling. These cooling coils transfer sensible and latent heat from the air to the cooling water, thus cooling and typically dehumidifying the air stream.

Chillers utilize an Alternating Current (AC) motor to drive a compressor that is used to compress and heat the coolant used in the chiller, and this refrigerant is passed through a condenser and is later evaporated to provide cooled air in the HVAC system. For high-rise (high tier) chiller applications, low total harmonic current distortion (THD) from the inverter driving the AC motor is required.

Disclosure of Invention

Embodiments of the present disclosure are directed to an apparatus. Non-limiting examples of the apparatus include one or more active switches, one or more diodes, wherein each active switch of the one or more active switches is in parallel with a corresponding diode of the one or more diodes, wherein each active switch of the one or more active switches includes a first current rating, wherein each diode of the one or more diodes includes a second current rating, and wherein the first current rating is at least one order of magnitude less than the second current rating.

Embodiments of the present disclosure are directed to a system. A non-limiting example of the system includes a rectifier, the rectifier including: a set of bridge structures configured to receive an input current of a power supply, wherein each bridge structure of the set of bridge structures comprises a set of diodes and a set of active switches, wherein each active switch of the set of active switches is configured to provide a parallel path around each diode of the set of diodes when in a PWM state; a controller configured to determine a threshold current for the rectifier and operate one or more active switches in the rectifier in a PWM state based on the input current being less than the threshold current.

Embodiments of the present disclosure are directed to a system. Non-limiting examples of such systems include: a rectifier comprising a first bridge structure configured to receive an input current from a power source, wherein the first bridge structure comprises a first diode and a second diode, a first active switch and a second active switch, wherein the first active switch provides a first parallel path around the first diode when in a PWM state; and wherein the second active switch provides a second parallel path around the second diode when in the PWM state; and a controller configured to determine a threshold current for the rectifier and operate a first active switch in the rectifier in a PWM state based on the input current being less than the threshold current.

Additional technical features and advantages are realized through the techniques of the present disclosure. Embodiments and aspects of the present disclosure are described in detail herein and are considered a part of the claimed subject matter. For a better understanding, reference is made to the detailed description and to the accompanying drawings.

Drawings

None of the following description should be considered limiting in any way. Referring to the drawings, like elements are numbered alike:

FIG. 1 illustrates a basic block diagram of an exemplary chiller system including a variable speed motor coupled to a compressor in accordance with one or more embodiments;

FIG. 2 depicts a circuit topology of a rectifier in accordance with one or more embodiments;

FIG. 3 depicts a rectifier topology with a single phase power supply in accordance with one or more embodiments;

fig. 4a and 4b depict circuit topologies of bidirectional switches in a rectifier circuit in accordance with one or more embodiments; and

fig. 5 depicts a flow diagram of a method for operating a rectifier in accordance with one or more embodiments.

Detailed Description

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of illustration, not limitation, with reference to the figures.

The term "about" is intended to include the degree of error associated with a measurement based on the particular quantity of equipment available at the time of filing the present application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

Turning now to the technology related to aspects of the present disclosure. High-rise chiller applications typically require low total harmonic current distortion for better operation. When low total harmonic current distortion (THD) is required for these high-rise chiller applications, Vienna (Vienna) rectifiers can be utilized. The vienna rectifier has the beneficial effect of low active device count while still maintaining high current quality. However, when the current is below a certain threshold (e.g., 10%), the harmonic performance of the vienna rectifier degrades. T-rectifiers can meet harmonic current requirements across the entire current range, but at a higher overall cost.

In accordance with one or more embodiments, aspects of the present disclosure address the shortcomings of the above-described problems by providing an asymmetric semiconductor arrangement for a T-type rectifier. In particular, the Insulated Gate Bipolar Transistor (IGBT) current ratings of the half bridges in the T-rectifier are sized much smaller than the diode current ratings in the same bridge configuration. In current rectifier circuits, when current distortion becomes an issue, the IGBTs in the bridge configuration are only enabled when the load power is below a certain threshold. In this case, a small current and low cost IGBT can be selected for the bridge structure with satisfactory current harmonic performance across the entire operating range.

Referring now to the drawings, FIG. 1 illustrates a basic block diagram of an exemplary chiller system 100 including a variable speed motor 102 coupled to a compressor 104 in accordance with one or more embodiments. The compressor 104 includes a propeller/rotor that rotates and compresses the liquid coolant into a superheated refrigerant vapor for delivery to the condenser 106. In the condenser 106, the refrigerant vapor is liquefied at high pressure and rejects heat (e.g., to the outside air via a condenser fan in an air-cooled chiller application). The liquid refrigerant exiting the condenser 106 is delivered to the evaporator 108 through an expansion valve (not shown). The refrigerant passes through an expansion valve, wherein a pressure drop causes the high pressure liquid refrigerant to take a lower pressure combination of liquid and vapor. As the cooling water passes through the evaporator 108, the low pressure liquid refrigerant evaporates, absorbing heat from the water, thereby further cooling the water and evaporating the refrigerant. The low pressure refrigerant is again delivered to the compressor 104 where it is compressed to a high pressure, high temperature gas and delivered to the condenser 106 to begin the refrigeration cycle again. It is to be appreciated that while a particular refrigeration system is shown in fig. 1, the present teachings are applicable to any refrigeration or HVAC system.

Also shown in fig. 1, the chiller system 100 includes a compressor 104, which compressor 104 is driven by a variable speed motor 102 in accordance with power supplied from a power grid 120 (or mains) through an AC-DC converter (rectifier) 200 and an inverter drive (sometimes referred to as a "DC-AC motor drive") 110. The inverter drive 110 includes solid state electronics that are used to modulate the frequency of the electrical power on the line. In an embodiment, inverter drive 110 converts AC electrical power received from grid 120 from AC to Direct Current (DC) using rectifier 200, and then converts the electrical power from DC to Pulse Width Modulated (PWM) voltage at a desired frequency using inverter 110 in order to drive motor 102.

The rectifier 200 is further depicted in fig. 2. Fig. 2 depicts a circuit topology of a rectifier 200 in accordance with one or more embodiments. The rectifier 200 is configured with three bridge structures, each bridge structure including a set of bypass switches 202 and a set of diodes 204. In the illustrated example, the bridge structures are in a half-bridge configuration and each includes two active switches 202 and two diodes 204. However, in one or more embodiments, a full-bridge configuration can be utilized. Also, in one or more embodiments, the active switch 202 can be any type of switch including, but not limited to, an Insulated Gate Bipolar Transistor (IGBT) or a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). Three bridge structures are coupled to the filter circuit 230. The filter circuit 230 is coupled to a three-phase Alternating Current (AC) power source 220. The combination of the three-phase power supply 220 and the filter 230 supplies power in three different phases (typically offset by 120 degrees) to the bridge structure. The bridge structures each receive power in a different phase and then rectify the AC power signal into a DC power signal. The rectifier 200 further comprises a capacitor bridge consisting of two capacitors 222, 224, which two capacitors 222, 224 are used to smooth the DC output power signal. Rectifier 200 also includes a set of bi-directional switches 206. These bi-directional switches 206 allow the creation of an active filter that operates in parallel with a half-bridge diode rectifier. It provides an additional path for the input current through the active control of the mid-branch bi-directional switch 206. Thus, the current at the grid side 220 becomes sinusoidal with low harmonic content. Note that the three bidirectional switches 206 are interconnected at the midpoint of a capacitor bridge consisting of two capacitors 222, 224 required to ensure voltage balance. RLoad is the load on the rectifier 200.

In one or more embodiments, the rectifier 200 also includes a controller 240, the controller 240 being used to operate the active switch 202 and the bi-directional switch 206. In one or more embodiments, the rectifier 200 can operate as a standard vienna type rectifier when the active switch 202 operates in the off state. When the active switch 202 is controlled in a Pulse Width Modulation (PWM) manner, the rectifier 200 can operate as a T-type rectifier. In one or more embodiments, the controller 240Controls the operation of both the active switch 202 and the bi-directional switch 206. The controller 240 is capable of determining (or receiving) a threshold current for use in the operation of the rectifier 200. The threshold current can be determined based on where the lower current of the AC power source begins to cause current distortion. When the input current to the bridge configuration is less than or below this threshold current, the rectifier 200 operates as a T-rectifier and the active switch 202 operates in parallel with the diode 204. When the input current to the bridge configuration is greater than the threshold current, the rectifier 200 operates as a vienna rectifier and current can only flow through the diode 204 and the active switch 202 is in the off state. In one or more embodiments, the current rating of the active switches 202 in these bridge configurations of the rectifier 200 is much less than the current rating of the diodes 204. In one or more embodiments, the current rating of the active switch 202 can be less than the current rating of the diode 204ASeveral orders of magnitude. When operating in the vienna rectifier mode, harmonic distortion becomes large under light load conditions because the input current becomes discontinuous due to the unidirectional power flow characteristic. This harmonic distortion can be corrected if the active switches are enabled in the PWM mode. In this case, the active switch provides an additional current path, thereby reducing the harmonics of the input current by a large amount.

Fig. 3 depicts a rectifier topology with a single phase power supply in accordance with one or more embodiments. Rectifier 300 includes a single bridge structure that includes a set of two active switches 302 and a set of two diodes 304. In the illustrated example, the bridge structures are in a half-bridge configuration and each include two active switches 302 and two diodes 304. However, in one or more embodiments, a full-bridge configuration can be utilized. Also, in one or more embodiments, the active switch 320 can be any type of switch including, but not limited to, an Insulated Gate Bipolar Transistor (IGBT) or a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). The bridge structure is coupled to a filter circuit 330. The filter circuit 330 is coupled to a single-phase Alternating Current (AC) power source 320. The bridge structure receives power from the power supply 320 through the filter 220 and then rectifies the AC power signal to a DC power signal. The rectifier 300 further comprises a capacitor bridge consisting of two capacitors 322, 324, the two capacitors 322, 324 serving to smooth the DC output power signal. The rectifier 300 also includes a set of bidirectional switches 306. These bi-directional switches 306 allow the creation of an active filter that operates in parallel with a half-bridge diode rectifier. It provides an additional path for current through the active control of the mid-branch bi-directional switch 306. Thus, the current at the grid side 320 becomes sinusoidal with low harmonic content. Note that the three bidirectional switches 306 are interconnected at the midpoint of a capacitor bridge consisting of two capacitors 322, 324 required to ensure voltage balance. The rectifier 300 drives a DC load (DLoad).

In one or more embodiments, the rectifier 300 further includes a controller 340, the controller 340 being operable to operate the active switch 302 and the bi-directional switch 306. In one or more embodiments, the controller 340 controls the operation of both the active switch 302 and the bi-directional switch 306. The controller 340 can determine (or receive) a threshold current for use in the operation of the rectifier 300. The threshold current can be determined based on where the lower current of the AC power source begins to cause current distortion. When the input current to the bridge structure is less than or below this threshold current, the rectifier 300 operates as a T-rectifier and operates one or more of the active switches 302 to create a bypass path around the diode 304. When the input current to the bridge configuration is greater than the threshold current, the rectifier 300 operates the active switch 302 in the off state and current can flow through the diode 304 through a forward bias. In one or more embodiments, the current rating of the active switches 302 in these bridge configurations of the rectifier 300 is much less than the current rating of the diodes 304. In one or more embodiments, the current rating of the active switch 302 can be less than the current rating of the diode 304ASeveral orders of magnitude.

Fig. 4a and 4b depict circuit topologies of bidirectional switches in a rectifier circuit in accordance with one or more embodiments. Circuit topology 400a includes a bi-directional switch 402 in which IGBTs are connected in a common emitter manner. Circuit topology 400b includes a bi-directional switch 404 in which IGBTs are connected in a common collector manner. An advantage of 402 over 404 is that it simplifies the gate drive power supply design for both IGBTs in the bi-directional switch.

Fig. 5 depicts a flow diagram of a method for operating a rectifier in accordance with one or more embodiments. The method 500 includes providing a rectifier including a set of bridge structures coupled to an input current of a power source, wherein each bridge structure of the set of bridge structures includes a set of diodes and a set of active switches, wherein each active switch of the set of active switches is configured to provide a parallel path around each diode of the set of diodes when in an on state, as shown at block 502. At block 504, the method 500 includes determining, by the controller, a threshold current for the rectifier. And at block 506, the method 500 includes operating, by the controller, the one or more active switches in the rectifier in a PWM state (stage) based on the input current being less than the threshold current.

Additional processes may also be included. It is to be understood that the process depicted in fig. 5 represents an illustration, and that other processes may be added, or existing processes may be removed, modified or rearranged, without departing from the scope and spirit of the present disclosure.

While the disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the claims.