TWI849842B - Control device applied to power conversion apparatus - Google Patents

Abstract

A control device, which is applied to a power conversion apparatus. The control device includes a power module, a short-circuit protection circuit and a temperature compensation protection circuit. The power module is used to execute a switch function. The short-circuit protection circuit is connected to the power module, the short-circuit protection circuit is used to convey a saturation current generated by the power module. The temperature compensation protection circuit is connected to the short-circuit protection circuit and the power module, the temperature compensation protection circuit is used to generate a compensation current, and the compensation current is provided to the short-circuit protection circuit. A current amount of the compensation current varies in response to a temperature of the power module.

Description

Control device for power conversion equipment

The present disclosure relates to a control device applied to a power conversion device, and in particular to a control device for temperature compensation of a short-circuit protection circuit of a power module.

Power conversion equipment can be used as a conversion medium between power supply (grid) and renewable energy (or load). In response to power supply equipment or load equipment with different power specifications, power conversion equipment can convert power into specific power and specific forms of electricity. The power module in the power conversion equipment includes power semiconductor components, which have the function of switching switches. Power semiconductor components have different materials, which enable power modules to have higher switching speeds. For example, power semiconductor components of silicon carbide (SiC) can operate at a switching speed of 10kHz~100kHz to adapt to equipment with power specifications of 1kW to 10MW. Power semiconductor components of gallium nitride (GaN) can operate at a higher switching speed of 100kHz~10MHz to adapt to equipment with power specifications of 100W to 10kW.

However, parasitic effects of power semiconductor components may cause switching losses and reduce the performance of power conversion equipment. More serious parasitic effects are caused by parasitic capacitance between conductors inside the component. The parasitic capacitance inside power semiconductor components includes: gate-source parasitic capacitance, gate-drain parasitic capacitance and drain-source parasitic capacitance of metal oxide semiconductor transistors (MOS transistors). Among them, the gate-drain parasitic capacitance is called Miller capacitance, and the parasitic effect caused by Miller capacitance is called Miller effect.

Due to the Miller effect, the gate-source voltage of the transistor remains at a constant voltage value within a time period (called the "Miller platform") and no longer rises. The duration of the Miller effect (i.e., the duration of the Miller platform) will increase the conduction time of the power semiconductor element, thereby increasing the switching loss of the power semiconductor element and reducing the conversion efficiency of the power conversion device. In addition, when the power conversion device has a higher switching speed, the Miller effect may deteriorate and significantly increase the glitch voltage of the gate-source voltage.

On the other hand, when a short circuit occurs in the power module, the power module may generate saturated current and damage the power module itself or other components of the power conversion equipment. The short-circuit protection circuit can provide a transmission path to guide the saturated current to achieve the effect of short-circuit protection. However, the power module may operate at different temperatures. When the temperature of the power module varies greatly, the protection mechanism of the short-circuit protection circuit may be triggered too late, reducing the effectiveness of the short-circuit protection.

In order to solve the technical problems caused by the Miller effect, it is necessary to improve the control device of the power conversion equipment to effectively suppress the Miller effect and accurately control the gate voltage of the power semiconductor element. In addition, in order to solve the technical problems caused by the short-circuit saturation current, it is necessary to improve the short-circuit protection circuit of the power conversion equipment to have a temperature compensation mechanism.

According to one aspect of the present disclosure, a control device for power conversion equipment is provided, including a power module, a short-circuit protection circuit and a temperature compensation protection circuit. The power module is used to perform the function of a switching switch. The short-circuit protection circuit is connected to the power module, and the short-circuit protection circuit is used to transmit the saturated current generated by the power module. The temperature compensation protection circuit is connected to the short-circuit protection circuit and the power module, and the temperature compensation protection circuit is used to generate a compensation current, and the compensation current is provided to the short-circuit protection circuit. The current amount of the compensation current changes according to the temperature of the power module.

Other aspects and advantages of the present disclosure may be seen by reading the following drawings, detailed descriptions and claims.

1000a, 1000b: Control device

2000: Power conversion equipment

2100: Power supply

2200: Energy storage element

2300: Load

100: Miller switch control circuit

200:Adjustable power supply

300: Temperature compensation protection circuit

310:Sensor

320: Processor

330: Current source

400: Control chip

410: Current source

420: Comparator

500:Drive circuit

600,620: Power module

700: Control circuit

710~760: Control unit

11,13,51,43: Input port

12,41,42,52: output port

31,61: First end

32,62: Second end

33: The third end

34: The fourth end

53: High potential end

54: Low potential end

63: Control terminal

64: Sensing end

C22,C3: Capacitor

Rg,R _desat : Resistance

D3,D _desat : diode

I1: Compensation current

I0: current

Im1: Miller current

V1+, V2+: constant voltage

GND0, GND1, GND2: ground terminals

temp1: temperature

Q1,Q2,Q5,Q6: Transistors

d5: Drain

s5: Source

Vds5: drain-source voltage

V _ref : reference voltage

V _fault : Indication voltage

Figure 1 is a circuit diagram of a control device for a power conversion device as a comparative example.

Figure 2 is a circuit diagram of a control device for a power conversion device according to an embodiment of the present disclosure.

Figure 3 is a circuit diagram of the temperature compensation protection circuit in the control device of Figure 2.

Figure 4A is a block diagram of a power conversion device according to an embodiment of the present disclosure.

FIG. 4B is a schematic diagram of an embodiment of the power conversion device of FIG. 4A.

The technical terms in this specification refer to the customary terms in this technical field. If this specification explains or defines some terms, the interpretation of these terms shall be based on the explanation or definition in this specification. Each embodiment disclosed in this disclosure has one or more technical features. Under the premise of possible implementation, a person with ordinary knowledge in this technical field can selectively implement some or all of the technical features in any embodiment, or selectively combine some or all of the technical features in these embodiments.

FIG. 1 is a circuit diagram of a control device 1000a of a comparative example power conversion device. As shown in FIG. 1, the control device 1000a includes a Miller switch control circuit 100, a control chip 400, a drive circuit 500, and a power module 600. The control chip 400 controls the drive circuit 500 so that the drive circuit 500 drives the power module 600 to perform the function of switching the switch. The Miller switch control circuit 100 is used to control the Miller clamping voltage of the power module 600.

More specifically, the high potential terminal 53 of the driving circuit 500 is connected to the constant voltage V1+. The low potential terminal 54 of the driving circuit 500 is connected to the Miller switch control circuit 100. The input terminal 51 of the driving circuit 500 is connected to the output terminal 41 of the control chip 400, and the driving circuit 500 is controlled by the control chip 400 via the input terminal 51. The output terminal 52 of the driving circuit 500 is connected to the control terminal 63 of the power module 600 via the resistor _Rg , and the driving circuit 500 drives the power module 600 via the output terminal 52.

The power module 600 acts as a power switch, which has a switching function. When the power conversion device provides power to devices with different power specifications, the power module 600 performs the switching in response to the different powers. The control end 63 of the power module 600 receives the driving voltage of the driving circuit 500. In response to the driving voltage, the power module 600 is in a turned-on state or a turned-off state. When the power module 600 is turned on, the first end 61 of the power module 600 can be connected to the second end 62. The power module 600 may include a power semiconductor element. In one example, the power semiconductor element of the power module 600 is, for example, a transistor (not shown in FIG. 1). The drain of the transistor is connected to the first terminal 61, the source of the transistor is connected to the second terminal 62, and the gate of the transistor is connected to the control terminal 63.

The control terminal 63 of the power module 600 is connected to the transistor Q6, and the transistor Q6 is connected to the ground terminal GND0. That is, the transistor Q6 is arranged between the control terminal 63 of the power module 600 and the ground terminal GND0. The transistor Q6 acts as a Miller switch to provide a bypass transmission path for the Miller current Im1. The source of the transistor Q6 is connected to the output terminal 52 of the driving circuit 500 via the resistor Rg, and the drain of the transistor Q6 is connected to the ground terminal GND0. The gate of the transistor Q6 is connected to the output terminal 12 of the Miller switch control circuit 100, and the input terminal 13 of the Miller switch control circuit 100 is connected to the capacitor C3 and the second terminal 62 of the power module 600. Miller switch control circuit 100 is used to control the on-time of transistor Q6, that is, Miller switch drive time t _miller (also called “Miller clamping time”). In addition, Miller switch control circuit 100 is used to control the Miller clamping voltage V _miller of the transistor of power module 600.

The first terminal 61 of the power module 600 is connected to the output terminal 42 of the control chip 400 via the resistor R _desat and the diode D _desat . The second terminal 62 of the power module 600 is connected to the resistor R _desat via the capacitor C3. When a short circuit occurs in the power module 600, the transmission path formed by the resistor R _desat and the diode D _desat can guide the saturated current generated by the power module 600 to achieve the short circuit protection effect of the power module 600. That is, the resistor R _desat and the diode D _desat serve as the short circuit protection circuit of the power module 600.

FIG. 2 is a circuit diagram of a control device 1000b of a power conversion device according to an embodiment of the present disclosure. As shown in FIG. 2, the control device 1000b includes a Miller switch control circuit 100, a temperature compensation protection circuit 300, a control chip 400, a drive circuit 500, and a power module 600. That is, the control device 1000b of the embodiment of FIG. 2 is similar to the control device 1000a of the comparative example of FIG. 1, and the difference is that the control device 1000b of FIG. 2 further includes a temperature compensation protection circuit 300.

The driving circuit 500 includes a transistor Q1 and a transistor Q2. The transistor Q1 and the transistor Q2 form an inverter. The gates of the transistors Q1 and Q2 are connected to the input terminal 51 of the driving circuit 500, and the drains of the transistors Q1 and Q2 are connected to the output terminal 52 of the driving circuit 500. The input terminal 51 of the driving circuit 500 is connected to the input terminal 11 of the Miller switch control circuit 100 and the output terminal 41 of the control chip 400. The output terminal 52 of the driving circuit 500 is connected to the control terminal 63 of the power module 600 via the resistor _Rg .

The resistor R _desat and the diode D _desat serve as a short circuit protection circuit of the power module 600, and the temperature compensation protection circuit 300 can perform temperature compensation for the resistor R _desat and the diode D _desat . The temperature compensation protection circuit 300 includes a first terminal 31, a second terminal 32, a third terminal 33, and a fourth terminal 34. The first terminal 31 of the temperature compensation protection circuit 300 is connected to the first terminal 61 of the power module 600 via the resistor R _desat and the diode D _desat , and the first terminal 31 is connected to the second terminal 62 of the power module 600 via the capacitor C3. The second terminal 32 of the temperature compensation protection circuit 300 is connected to the sensing terminal 64 of the power module 600. The third terminal 33 of the temperature compensation protection circuit 300 is connected to the input terminal 43 of the control chip 400. The fourth terminal 34 of the temperature compensation protection circuit 300 is connected to the output terminal 42 of the control chip 400.

In operation, the temperature compensation protection circuit 300 senses the temperature of the power module 600 via the sensing terminal 64 of the power module 600. In response to different temperatures of the power module 600, the temperature compensation protection circuit 300 provides a corresponding compensation current to the transmission path formed by the resistor R _desat and the diode D _desat to achieve the effect of temperature compensation.

FIG. 3 is a circuit diagram of the temperature compensation protection circuit 300 in the control device 1000b of FIG. 2. Please refer to FIG. 2 and FIG. 3 at the same time. The third terminal 33 of the temperature compensation protection circuit 300 is connected to the input terminal 43 of the control chip 400, and the third terminal 33 is connected to the third constant voltage V2+. The output terminal 42 of the control chip 400 is connected to the ground terminal GND2 via the capacitor C22. The transmission path of the resistor R _desat and the diode D _desat can provide short-circuit protection for the power module 600. When a short circuit occurs in the power module 600, the transistor Q5 of the power module 600 may generate a saturation current. The resistor R _desat and the diode D _desat can provide a transmission path for the saturation current of the transistor Q5. The temperature compensation protection circuit 300 can generate a corresponding compensation current I1 in response to the temperature change of the power module 600. The compensation current I1 is provided to the transmission path formed by the resistor R _desat and the diode D _desat to achieve the effect of temperature compensation.

The temperature compensation protection circuit 300 includes a sensor 310, a processor 320, a current source 330, and a diode D3. The first terminal 61 of the power module 600 is connected to the diode D3 of the temperature compensation protection circuit 300 via the resistor R _desat and the diode D _desat , and is connected to the output terminal 42 of the control chip 400 via the diode D3. The sensing terminal 64 of the power module 600 is connected to the sensor 310. The sensor 310 is, for example, a temperature sensor, and the sensor 310 is used to sense the temperature temp1 of the power module 600.

The temperature temp1 of the power module 600 varies in a range of, for example, 25 degrees Celsius to 175 degrees Celsius. When operating in a range of 25 degrees Celsius to 175 degrees Celsius, the drain-source voltage Vds5 of the transistor Q5 of the power module 600 has different voltage values, and the drain-source current Ids5 of the transistor Q5 has different current amounts. The drain-source voltage Vds5 is the voltage difference between the drain d5 and the source s5 of the transistor Q5.

In this embodiment, the preset operating condition of the temperature compensation protection circuit 300 is: when the temperature temp1 of the power module 600 is approximately equal to 175 degrees, the current of the compensation current I1 provided by the temperature compensation protection circuit 300 is zero. Based on the above preset operating condition, the resistance value R_desat of the resistor R _desat can be obtained according to formula (1):

"V _ref " in formula (1) is the reference voltage V _ref of the control chip 400. "V_D3" in formula (1) is the forward bias of the diode D3. "V_D_desat" in formula (1) is the forward bias of the diode D _desat . "Vds5 (175°)" in formula (1) is the voltage value of the drain-source voltage Vds5 when the temperature temp1 is approximately equal to 175 degrees. "I0" in formula (1) is the current amount of the current I0 provided by the current source 410 inside the control chip 400. That is, the resistance value R_desat of the resistor R _desat is related to the temperature temp1 of the power module 600 and the voltage difference between the drain d5 and the source s5 of the transistor Q5.

The sensor 310 is connected to the sensing end 64 of the power module 600 via the second end 32 of the temperature compensation protection circuit 300 to sense the temperature temp1 of the power module 600. In response to the temperature temp1 of the power module 600, the sensor 310 provides a corresponding control signal to the processor 320. In addition, the processor 320 provides a corresponding control signal to the current source 330. In this embodiment, the current source 330 is a voltage-controlled current source (abbreviated as "voltage-controlled current source"), and the control signal generated by the processor 320 is a voltage control signal, which changes with the temperature temp1 of the power module 600. The current source 330 is used to generate a compensation current I1. The current of the compensation current I1 changes in response to the voltage control signal of the processor 320, as shown in equation (2):

"Vds5(temp1)" in formula (2) is the voltage value of the drain-source voltage Vds5 of the transistor Q5 when it operates at the temperature temp1. The compensation current I1 provided by the current source 330 can be used as the current compensation of the short-circuit protection circuit formed by the resistor R _desat and the diode D _desat . The current source 330 changes the current of the compensation current I1 in response to the change of the temperature temp1 to achieve the effect of temperature compensation. In addition, the diode D3 of the temperature compensation protection circuit 300 can block the reverse current that may be generated on the transmission path of the resistor R _desat and the diode D _desat .

According to the temperature temp1 of the power module 600 sensed by the sensor 310, the processor 320 can generate a corresponding voltage control signal according to a table lookup, thereby controlling the current source 330 to generate an appropriate compensation current I1. Accordingly, when the temperature temp1 of the power module 600 varies in a larger range, the temperature compensation protection circuit 300 can still accurately provide an appropriate compensation current I1. In addition, the comparator 420 of the control chip 400 compares the voltage value of the output terminal 42 with the reference voltage V _ref , and the comparator 420 generates an indication voltage V _fault according to the comparison result.

FIG. 4A is a block diagram of a power conversion device 2000 of an embodiment of the present disclosure. The power conversion device 2000 includes a power source 2100, a power module 620, an energy storage element 2200, a load 2300, and a control circuit 700. The control circuit 700 may include the Miller switch control circuit 100 and the temperature compensation protection circuit 300 of the embodiment of FIG. 2 (not shown in FIG. 4A). The power source 2100 is, for example, a large fixed grid device. The energy storage element 2200 is, for example, a small (even portable) battery device. The power module 620 is disposed between the power source 2100 and the energy storage element 2200, and the power module 620 serves as a switching switch. In response to the different power specifications of the power source 2100, the energy storage element 2200 and the load 2300, the power module 620 converts the power provided by the power source 2100 to generate specific power and specific form of power and provide it to the energy storage element 2200.

The control circuit 700 is connected to the power module 620. The power semiconductor elements in the power module 620 may be short-circuited or malfunctioned due to the Miller effect. Accordingly, the control circuit 700 performs Miller clamp control on the power semiconductor elements in the power module 620. For example, the control circuit 700 controls the gate-source voltage of the power semiconductor elements in the power module 620 to an appropriate Miller clamp voltage V _miller , and controls the Miller switch to operate at an appropriate Miller switch driving time t _miller .

Next, please refer to FIG. 4B, which is a schematic diagram of an embodiment of the power conversion device 2000 of FIG. 4A. The power module 620 of this embodiment includes six power switch elements, and correspondingly, the control circuit 700 includes six control units 710~760. Each power switch element of the power module 620 has the function of switching switches, and each power switch element of the power module 620 is controlled by a corresponding one of the control units 710~760 of the control circuit 700. For example, the control units 710 and 720 of the control circuit 700 respectively control a group of power switch elements of the power module 620, and the group of power switch elements serves as the upper arm element and the lower arm element of the power module 620. Similarly, control units 730 and 740 of control circuit 700 respectively control another set of power switch elements of power module 620, and control units 750 and 760 of control circuit 700 respectively control another set of power switch elements of power module 620.

Although the present invention has been disclosed in detail above with preferred embodiments and examples, it is understood that these examples are intended to be illustrative rather than restrictive. It is expected that a person with ordinary knowledge in the relevant technical field can think of various modifications and combinations, and the various modifications and combinations fall within the spirit of the present invention and the scope of the attached patent application.

300: Temperature compensation protection circuit

310:Sensor

320: Processor

330: Current source

400: Control chip

410: Current source

420: Comparator

600: Power module

13,43: Input port

42: Output terminal

31,61: First end

32: Second end

33: The third end

34: The fourth end

64: Sensing end

C22,C3: Capacitor

R _desat : resistance

D3,D _desat : diode

I1: Compensation current

I0: current

V2+: constant voltage

GND2: ground terminal

temp1: temperature

Q5: Transistor

d5: Drain

s5: Source

Vds5: drain-source voltage

V _ref : reference voltage

V _fault : Indication voltage

Claims (8)

A control device for power conversion equipment includes: a power module for performing a switching function; a short-circuit protection circuit connected to the power module, the short-circuit protection circuit forming a transmission path to guide a saturated current generated when the power module is short-circuited; and a temperature compensation protection circuit connected to the short-circuit protection circuit and the power module, the temperature compensation protection circuit is used to generate a compensation current, the current of which is in response to a temperature of the power module. The temperature compensation protection circuit includes: a sensor connected to a sensing end of the power module for sensing the temperature of the power module; a processor connected to the sensor for generating a voltage control signal in a table lookup manner according to the temperature of the power module; and a current source connected to the processor and the short-circuit protection circuit for generating the compensation current to provide to the short-circuit protection circuit, and changing the current amount of the compensation current in response to the voltage control signal. A control device as described in claim 1, wherein the power module has a first end, and the short-circuit protection circuit includes: a first diode connected to the first end of the power module; and a resistor connected to an anode of the first diode. A control device as described in claim 2, wherein the power module includes a transistor having a source and a drain, the drain being connected to a cathode of the first diode, wherein the resistance value of the resistor is related to the temperature of the power module and the voltage difference between the drain and the source. A control device as described in claim 2, wherein the temperature compensation protection circuit includes: a second diode having an anode and a cathode, the cathode being connected to the resistor, wherein the second diode is used to block a reverse current generated by the resistor and the first diode. A control device as described in claim 4, wherein the temperature compensation protection circuit includes a current source, and the control device further includes: a control chip having an input terminal, the input terminal being connected to the current source of the temperature compensation protection circuit. A control device as described in claim 5, wherein the current source of the temperature compensation protection circuit is connected to the cathode of the second diode and the resistor of the short-circuit protection circuit. A control device as described in claim 5, wherein the control chip has an output terminal, and the output terminal is connected to the resistor of the short-circuit protection circuit via the second diode of the temperature compensation protection circuit. A control device as described in claim 5, wherein the power module has a control end, and the control device further comprises: a driving circuit connected to the control chip and the control end of the power module, the driving circuit is used to control the voltage of the control end of the power module to drive the power module.

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