Methods and apparatus for controlling switch gate logic in a power converter

Abstract

A cycloconverter configured for use with a power converter is provided and comprises a bidirectional switch comprising a first gate and a second gate is configured such that in an off mode of the bidirectional switch a polarity and a magnitude of a blocking voltage imposed across the bidirectional switch determines a driving sequence of the first gate and the second gate.

Description

METHODS AND APPARATUS FOR CONTROLLING SWITCH GATE LOGIC IN A POWER CONVERTER BACKGROUND Field of the Disclosure

[0001] Embodiments of the present disclosure relate generally to power conversion and, in particular, to methods and apparatus for driving bidirectional switches (BDS) using blocking voltage detection logic.Description of the Related Art

[0002] Conventional BDS are known and can be made by connecting a pair of conventional unidirectional power transistors together - either in a common-Source or common-Drain connection configuration (common-Emitter or common-Collector). Typically, BDS have two Gates that require a correct driving logic to achieve optimal performance from the BDS, e.g., to make use of all four (4) states of the BDS. For example, Gate drive signals can be derived based on two different pieces of information. For example, the gate drive signals can be derived using input pulse width modulation (PWM) switch state information, e.g., Low = Off and High=On and / or using a polarity of a blocking voltage across a bidirectional switch while the bidirectional switch is in an off state (e.g., an AC mains voltage polarity). With respect to using a polarity of a blocking voltage across a bidirectional switch, however, a degree of uncertainty regarding accurately determining the correct blocking voltage polarity can be introduced when the actual blocking voltage is very low, which occurs at an AC mains voltage zero cross point.

[0003] Conventional approaches for driving the two individual Gates of a bidirectional switch apply both of the two individual Gates with the same input switch state signal. Such approaches, however, only use the on and off state of the bidirectional switch and does not make use of the two diode states of the bidirectional switch. Also, such approaches are not able to provide an over-voltage clamping function and require additional external clamp diodes to protect the bidirectional switch from over-voltage events resulting from the switching of an inductive load current. Moreover, by needlessly cycling both bidirectional switch Gates on and off results in a Gate drive power consumption that is twice as large asonly cycling a single bidirectional switch Gate on and off (e.g., the necessary bidirectional switch Gate).

[0004] Thus, there is a need for improved methods and apparatus for driving bidirectional switches (BDS) using blocking voltage detection logic.SUMMARY

[0005] In accordance with at least some embodiments, there is provided a cycloconverter comprising a bidirectional switch comprising a first gate and a second gate is configured such that in an off mode of the bidirectional switch a polarity and a magnitude of a blocking voltage imposed across the bidirectional switch determines a driving sequence of the first gate and the second gate.

[0006] In accordance with at least some embodiments, there is provided a method for controlling switching of a bidirectional switch. The method comprising determining a polarity of a blocking voltage imposed across the bidirectional switch in an off mode of the bidirectional switch and based on the polarity and a magnitude of the blocking voltage controlling a driving sequence of a first gate and a second gate of the bidirectional switch.

[0007] Various advantages, aspects, and novel features of the present disclosure may be appreciated from a review of the following detailed description of the present disclosure, along with the accompanying figures in which like reference numerals refer to like parts throughout.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0009] Figure 1 is a schematic diagram of a power conversion system comprising a switched mode power converter in accordance with embodiments of the present disclosure;

[0010] Figure 2 is a schematic diagram of a power conversion system comprising a switched mode power converter in accordance with embodiments of the present disclosure;

[0011] Figure 3 is a schematic diagram of a bidirectional switch and corresponding timing graphs in accordance with embodiments of the present disclosure;

[0012] Figure 4 is a schematic diagram of switching sequence for the bidirectional switch in a normal switching mode and a safe switching mode in accordance with embodiments of the present disclosure; and

[0013] Figure 5 is a flowchart of a method for controlling switching of the bidirectional switch in accordance with embodiments of the present disclosure.DETAILED DESCRIPTION

[0014] Embodiments of the present disclosure are directed to methods and apparatus for driving bidirectional switches (BDS) using blocking voltage detection logic. For example, a cycloconverter configured for use with a power converter can comprise a bidirectional switch comprising a first gate and a second gate is configured such that in an off mode of the bidirectional switch a polarity of a blocking voltage imposed across the bidirectional switch determines a driving sequence of the first gate and the second gate. The methods and apparatus provided herein use the on and off state of the bidirectional switch and make use of the two diode states of the bidirectional switch. Also, the methods and apparatus provided herein provide an over-voltage clamping function and do not require additional external clamp diodes to protect the bidirectional switch from over-voltage events resulting from the switching of an inductive load current. Moreover, since the methods and apparatus provided herein only cycle a single bidirectional switch Gate on and off (e.g., the necessary bidirectional switch Gate), Gate drive power consumption is greatly reduced when compared to conventional approaches.

[0015] The foregoing description of embodiments of the disclosure comprises a number of elements, devices, circuits and / or assemblies that perform variousfunctions as described. These elements, devices, circuits, and / or assemblies are exemplary implementations of means for performing their respectively described functions.

[0016] Figure 1 is a schematic diagram of a power conversion system 100 comprising a converter 102 (e.g., a switched mode power converter) in accordance with embodiments of the present disclosure. This diagram only portrays one variation of the myriad of possible system configurations. The present disclosure can function in a variety of power generation environments and systems.

[0017] The power conversion system 100 comprises a DC component 120, such as a PV module or a battery, coupled to a DC side of the converter 102. In other embodiments the DC component 120 may be any suitable type of DC components, such as another type of renewable energy source (e.g., wind farms, hydroelectric systems, and the like), other types of energy storage components, and the like.

[0018] The converter 102 comprises a capacitor 122 coupled across the DC component 120 as well as across an H-bridge 104 formed from switches S-1 , S-2, S-3 and S-4. The switches S-1 and S-2 are coupled in series to form a left leg of the H-bridge 104, and the switches S-3 and S-4 are coupled in series to form a right leg of the H-bridge 104.

[0019] The output of the H-bridge 104 is coupled across a series combination of a capacitor Cr and inductor L, which form a resonant tank, and the primary winding of a transformer 108. In other embodiments, the resonant tank may be formed by a different configuration of the capacitor Cr and the inductor Lr (e.g., the capacitor Cr and the inductor L may be coupled in parallel); in some embodiments, Lr may represent a leakage inductance from the transformer 108 rather than a physical inductor.

[0020] A series combination of the secondary winding of the transformer 108 and an inductor L is coupled across a bridge which produces a three-phase AC output, although in other embodiments the bridge may produce one or two phases of AC at its output. The bridge can be a half-bridge, full-bridge, Hex-bridge, etc. formed using switches that are arranged to enable current flow to be alternated. For example, the switches can comprise one or more semiconductor (or vacuum tube) devices, e.g., Field Effect Transistor (FET), Junction FET (JFET), Metal Oxide Semiconductor FET(MOSFET), High Electron Mobility Transistor (HEMT), etc. The switches can be used for AC-DC conversion and / or DC-AC conversion (e.g., switches that are controllable). The bridge can be a Bi-directional bridge (sometimes referred to as a cycloconverter bridge or cycloconverter for short) that uses two unidirectional switches connected in series (back-to-back, which can be referred to as Bidirectional switches) -which can conduct current in either direction (when turned on), can block a voltage of either polarity (when turned off), and can also block a voltage in both polarities (e.g., block polar voltage). For illustrative purposes, the secondary winding of the transformer 108 and the inductor L are assumed coupled across a cycloconverter 110. The cycloconverter 110 comprises three 4Q bidirectional switches Q-1 , Q-2, and Q-3 (which may be collectively referred to as switches Q) respectively in a first leg, a second leg, and a third leg coupled in parallel to one another. In accordance with embodiments of the present disclosure, each of the switches Q-1 , Q-2, and Q-3 is a native four quadrant bi-directional switch comprising one or more of the aforementioned semiconductor (or vacuum tube) devices. Alternatively or additionally, the cycloconverter 110 can comprise three monolithically formed switches (e.g., a Monolithic Bi-Directional Switch (MBDS)) - Gallium-Nitride (GaN) based on a HEMT structure. That is, the MBDS refers to the fact that this Bi-Directional Switch (BDS) can be built in a single semiconductor die. In at least some embodiments, each of the switches Q-1 , Q-2, and Q-3 comprises a pair of Gallium-Nitride (GaN) High Electron Mobility Transistors. In at least some embodiments, each of the switches Q-1 , Q-2, and Q-3 comprises a first pair of Gallium-Nitride (GaN) High Electron Mobility Transistors and a second pair of Gallium-Nitride (GaN) High Electron Mobility Transistors connected in series.

[0021] The first cycloconverter leg comprises the 4Q switch Q-1 coupled to a capacitor C1 , the second cycloconverter leg comprises the 4Q switch Q-2 coupled to a capacitor C2, and the third cycloconverter leg comprises a 4Q switch Q-3 coupled to a capacitor C3. A first AC output phase line is coupled between the switch Q-1 and the capacitor C1 , a second AC output phase line is coupled between the switch Q-2 and the capacitor C2, and a third AC output phase line is coupled between the switch Q-3 and the capacitor C3. The converter 102 may also include additionalcircuitry not shown, such as voltage and / or current monitors, for obtaining data for power conversion, data reporting, and the like.

[0022] The converter 102 additionally comprises a controller 106 coupled to the Id- bridge switches (S-1 , S-2, S-3, and S-4) and the cycloconverter switches (Q-1 , Q-2, and Q-3) for operatively controlling the switches to generate the desired output power. In some embodiments, the converter 102 may function as a bi-directional converter.

[0023] The controller 106 comprises a CPU 184 coupled to each of support circuits183 and a memory 186. The CPU 184 may comprise one or more conventionally available microprocessors or microcontrollers. Additionally or alternatively, the CPU184 may include one or more application specific integrated circuits (ASICs). The support circuits 183 are well known circuits used to promote functionality of the CPU 184. Such circuits include, but are not limited to, a cache, power supplies, clock circuits, buses, input / output (I / O) circuits, and the like. The controller 106 may be implemented using a general purpose computer that, when executing particular software, becomes a specific purpose computer for performing various embodiments of the present disclosure.

[0024] The memory 186 is a non-transitory computer readable storage medium such as random access memory, read only memory, removable disk memory, flash memory, and various combinations of these types of memory. The memory 186 is sometimes referred to as main memory and may, in part, be used as cache memory or buffer memory. The memory 186 generally stores the OS 187 (operating system), if necessary, of the controller 106 that can be supported by the CPU capabilities. In some embodiments, the OS 187 may be one of a number of commercially available operating systems such as, but not limited to, LINUX, Real- Time Operating System (RTOS), and the like.

[0025] The memory 186 may store various forms application software (e.g., instructions), such as a conversion control module 189 for controlling power conversion by the converter 102, for example maximum power point tracking (MPPT), switching, performing the methods described herein, and the like. The memory 186 may further store a database 199 for storing various data. Thecontroller 106 further processes inputs and outputs to external communications 194 (i.e., gateway) and a grid interface 188.

[0026] Figure 2 is a schematic diagram of a power conversion system 200 comprising a converter 202 (e.g., a switched mode power converter) in accordance with embodiments of the present disclosure.

[0027] The power conversion system 200 comprises the DC component 120 coupled to a DC side of the converter 202. The converter 202 comprises the capacitor 122 coupled across the DC component 120 and the H-bridge 104, as described above with respect to the converter 102. The output of the H-bridge 104 is coupled across a series combination of the capacitor Cr and the inductor Lr, which form a resonant tank, and the primary winding of the transformer 108, as described above with respect to the converter 102. In other embodiments, the resonant tank may be formed by a different configuration of the capacitor Cr and the inductor Lr (e.g., the capacitor Cr and the inductor L may be coupled in parallel); in some embodiments, Lr may represent a leakage inductance of the transformer 108 rather than a physical inductor.

[0028] A series combination of the secondary winding of the transformer 108 and the inductor L can be coupled across a bridge as described above with respect to Figure 1. For example, the secondary winding of the transformer 108 and the inductor L can be coupled across a cycloconverter 210 which produces a single-phase AC output. For example, the cycloconverter 210 comprises two bi-directional switches Q-1 and Q-2, (collectively referred to as switches Q) respectively in a first leg and a second leg coupled in parallel to one another. In accordance with embodiments of the present disclosure, each of the switches Q-1 and Q-2 is a native four quadrant bi-directional switch comprising one or more of the aforementioned semiconductor (or vacuum tube) devices. Alternatively or additionally, the cycloconverter 210 can comprise two monolithically formed switches (e.g., a Monolithic Bi-Directional Switch (MBDS)) -Gallium-Nitride (GaN) based on a HEMT structure. In at least some embodiments, each of the switches Q-1 and Q-2 comprises a pair of Gallium-Nitride (GaN) High Electron Mobility Transistors. In at least some embodiments, each of the switches Q-1 and Q-2 comprises a first pair of Gallium-Nitride (GaN) HighElectron Mobility Transistors and a second pair of Gallium-Nitride (GaN) High Electron Mobility Transistors connected in series.

[0029] The first cycloconverter leg comprises the 4Q switch Q-1 coupled to the capacitor 01 , and the second cycloconverter leg comprises the 4Q switch Q-2 coupled to the capacitor C2. A first AC output phase line is coupled between the switch Q-1 and the capacitor C1, and a second AC output phase line is coupled between the switch Q-2 and the capacitor C2. The converter 202 may also include additional circuitry not shown, such as voltage and / or current monitors, for obtaining data for power conversion, data reporting, and the like.

[0030] The converter 202 additionally comprises a controller 206 coupled to the H- bridge switches (S-1 , S-2, S-3, and S-4), and the cycloconverter switches (Q-1 and Q-2) for operatively controlling the switches to generate the desired output power. In some embodiments, the converter 202 may function as a bi-directional converter.

[0031] The controller 206 comprises a CPU 284 coupled to each of support circuits283 and a memory 286. The CPU 284 may comprise one or more conventionally available microprocessors or microcontrollers. Additionally or alternatively, the CPU284 may include one or more application specific integrated circuits (ASICs). The support circuits 283 are well known circuits used to promote functionality of the CPU 284. Such circuits include, but are not limited to, a cache, power supplies, clock circuits, buses, input / output (I / O) circuits, and the like. The controller 206 may be implemented using a general purpose computer that, when executing particular software, becomes a specific purpose computer for performing various embodiments of the present disclosure.

[0032] The memory 286 is a non-transitory computer readable medium such as random access memory, read only memory, removable disk memory, flash memory, and various combinations of these types of memory. The memory 286 is sometimes referred to as main memory and may, in part, be used as cache memory or buffer memory. The memory 286 generally stores the OS 287 (operating system), if necessary, of the controller 206 that can be supported by the CPU capabilities. In some embodiments, the OS 287 may be one of a number of commercially available operating systems such as, but not limited to, LINUX, Real-Time Operating System (RTOS), and the like.

[0033] The memory 286 may store various forms of application software, such as a conversion control module 289 for controlling power conversion by the converter 202, for example maximum power point tracking (MPPT), switching, and the like. The memory 286 may further store a database 299 for storing various data. The controller 206 further processes inputs and outputs to external communications 194 (i.e., gateway) and the grid interface 188.

[0034] Figure 3 is a schematic diagram of a bidirectional switch and corresponding timing graphs, Figure 4 is a schematic diagram of switching sequence for the bidirectional switch in a normal switching mode and a safe switching mode, and Figure 5 is a flowchart of a method 500 for controlling switching of the bidirectional switch in accordance with embodiments of the present disclosure.

[0035] For example, the inventor has found that logic circuitry can be added into the isolated Gate drivers 302 of a bidirectional switch 300 to meet the needs of optimally driving (e.g., a driving sequence) both bidirectional switch Gates Gi and G2. In doing so, the logic abstracts the complexity of providing the optimum bidirectional switch Gates signals and makes the driving of the bidirectional switch 300 no more complex than the conventional approaches described above. For example, a relatively high voltage sense resistor 304 connects between the X-input of the isolated Gate drivers 302, and the high voltage sense resistor 304 allows the isolated Gate drivers 302 to sense the blocking voltage across the bidirectional switch 300 when the bidirectional switch 300 is driven into an off state. For example, the inventor has found that the resistor should have a value high enough to minimize unnecessary power consumption, e.g., a relatively low value of about 100,000 Ohms (100 kQ), which can result in an approximate 0.2% negative impact on microinverter efficiency, which is basically at the edge of appreciable concern. Conversely, the inventor has found that there is a need to ensure that the value of the resistor is not too high so as not to impact the accuracy that can be achieved with an X-input sensing circuitry, described below. Additionally, based on the silicon processes that are, typically, used to fabricate the gate driver, the inventor has found that a value of about 10,000,000 Ohms (10 MQ) can be used for the resistor. Accordingly, the high voltage sense resistor 304 can have a resistance of about 100kQ to about 10 MQ 1 MQ, and in at least some embodiments, the high voltage sense resistor 304 can have a resistance of about 1 MQ.

[0036] The blocking voltage across the bidirectional switch 300 when the bidirectional switch 300 is in the off state effectively provides the same information as the AC Mains voltage. For example, when the bidirectional switch 300 is in the off state, the blocking voltage can be imposed across the bidirectional switch 300. Additionally, the blocking voltage can be imposed across the high voltage sense resistor 304 to cause a current to flow through the high voltage sense resistor 304. The current flowing through the high voltage sense resistor 304 flows into (e.g., a positive current) one of the isolated Gate drivers 302 and out of (e.g., a negative current) the other isolated Gate driver. The polarity of the current flowing into (or out of) the X-input signifies a polarity of the blocking voltage imposed across the bidirectional switch 300. The magnitude of the current flowing into (or out of) the X- input signifies the magnitude of the blocking voltage imposed across bidirectional switch 300.

[0037] For example, in Fig. 3 the signals G1 and G2 have an overlap period when both Gate signals switch on and off, e.g., the Safe Mode switching period. The Safe Mode switching period can be defined with respect to the AC mains voltage. For example, if the absolute voltage is less than a predetermined value 301 , the Safe Mode switching pattern is used. The Safe Mode can have an arbitrarily chosen threshold, e.g., between + / - 3V (e.g., a lower limit of precision) to about + / - 300V (an upper limit of precision), and in at least some embodiments, + / -30V (in the range from -30V to +30V, somewhere in between the lower limit of precision and the upper limit of precision). Thus, the gate driver needs to know the magnitude of the AC voltage and how the magnitude of the AC voltage compares to the boundaries of - 30V and +30V. For example, if the AC voltage magnitude is less than -30V, the gate driver is in reverse mode and one Gate is kept permanently on while the other Gate is switched on and off. Conversely, if the AC voltage magnitude is more than +30V, the gate driver is in forward mode and the other Gate is kept on while the one Gate is switched on and off. If the AC voltage magnitude is somewhere between -30V and +30V then the gate driver is in Safe Mode and the one Gate and the other Gate are both switched on and off. So, in order to achieve all the logic, the Gate driverneeds to know both the polarity of the voltage across the bidirectional switch 300 when the bidirectional switch 300 is off and the magnitude of the voltage across the bidirectional switch 300 while it is turned off, e.g., is the voltage magnitude lower or greater than -30V and is the voltage magnitude lower or greater than +30V.

[0038] Additionally, the logic circuitry can also be included within the isolated Gate drivers 302 to measure the polarity and magnitude of the current flowing into (or out of) the X-input, and based on the information related to the polarity and magnitude of the current flowing into (or out of) the X-input, the logic circuitry can determine how to optimally drive the respective Gate of bidirectional switch 300. In at least some embodiments, the logic circuitry can be identical in both of the isolated Gate drivers 302 and makes use of the relative symmetry that is present with bidirectional switch 300, which results in the required difference between the switch Gates Gi and G2 drive signals. In at least some embodiments, the logic circuitry can be configured for use with various modes of switching, such as Safe-Mode switching and Safe+ Mode switching, each described in commonly-owned U.S. Provisional Application Serial No. 63 / 428, 789, the entire contents of which is incorporated herein by reference.

[0039] In operation, at 502, the method 500 can comprise determining a polarity of a blocking voltage imposed across the bidirectional switch in an off mode of the bidirectional switch. Next, at 504, the method 500 can comprise based on the polarity and a magnitude of the blocking voltage controlling a driving sequence of a first gate and a second gate of the bidirectional switch. For example, when the bidirectional switch 300 is in an off mode, during a period when the blocking voltage polarity is uncertain, the magnitude of the AC voltage is between a predetermined value (e.g., the boundaries of -30V and +30V), and a pulse width modulation (PWM) signal is provided to the isolated Gate drivers 302 of the bidirectional switch 300, both switch Gates G1 and G2 are cycled on and off, which can be Safe Mode Switching (or Safe+ Mode Switching), see 306 and 402 of Figures 3 and 4, respectively. In Safe Mode switching (or Safe+ Mode Switching) both switch Gates G1 and G2 are forward gates. Conversely, when the blocking voltage polarity is clearly known, the magnitude of the AC voltage is greater than the predetermined value 301 (e.g., greater than +30V), and the PWM signal is provided to the isolated Gate drivers 302 of the bidirectional switch 300, only one of the switch Gates G1 andG2 is cycled on and off and the other is kept on, which is Normal Mode Switching. For example, when the polarity of the blocking voltage is positive (308) and the magnitude of the AC voltage is greater than the predetermined value 301 , the Gate Gi can be kept on (310) and the Gate G2 can be cycled on and off (312). The Gate (e.g., the Gate G2) that is able to control the current flow through bidirectional switch 300 (e.g., cycled on and off) is designated the Forward Gate, and the Gate (e.g., the Gate G1) that is not able to control the current flow through bidirectional switch 300 (e.g., kept turned on) is designated the Reverse Gate, see 406 of Figure 4. Similarly, when the polarity of the blocking voltage is negative (314) and the magnitude of the AC voltage is less than the predetermined value 301 , the Gate G2 can be kept on (316) and the Gate G1 can be cycled on and off (318). The Gate (e.g., the Gate G1) that is able to control the current flow through bidirectional switch 300 (e.g., cycled on and off) is designated the Forward Gate, and the Gate (e.g., the Gate G2) that is not able to control the current flow through bidirectional switch 300 (e.g., kept turned on) is designated the Reverse Gate, see 404 of Figure 4.

[0040] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is defined by the claims that follow.

Claims

CLAIMS:1 . A cycloconverter configured for use with a power converter, comprising: a bidirectional switch comprising a first gate and a second gate is configured such that in an off mode of the bidirectional switch a polarity and a magnitude of a blocking voltage imposed across the bidirectional switch determines a driving sequence of the first gate and the second gate.

2. The cycloconverter of claim 1 , wherein the bidirectional switch further comprises a first isolated gate driver and a second isolated gate driver that are respectively connected to the first gate and the second gate, and wherein each of the first isolated gate driver and the second isolated gate driver comprises logic circuitry that is configured to determine the polarity of the blocking voltage and based on the polarity of the blocking voltage control the driving sequence of the first gate and the second gate.

3. The cycloconverter of claim 2, wherein the logic circuitry on the first isolated gate driver and the second isolated gate driver is identical to each other.

4. The cycloconverter of claim 2, wherein a resistor is coupled across the first isolated gate driver and the second isolated gate driver, and wherein the blocking voltage causes current to flow through the resistor and into one of the first isolated gate driver or the second isolated gate driver and out of the other one of the first isolated gate driver or the second isolated gate driver.

5. The cycloconverter as in any of claims 2 to 4, wherein the first isolated gate driver and the second isolated gate driver are configured to receive a pulse width modulation signal.

6. The cycloconverter as in any of claims 1 to 4, wherein the bidirectional switch is configured for use in at least one of a normal mode switching, a safe mode switching, or a safe+ mode switching.

7. The cyclo con verter of claim 1 , wherein in the off mode of the bidirectional switch when the polarity of the blocking voltage can be determined one of the first gate or the second gate is cycled on and off and the other one of the first gate or the second gate is kept on.

8. The cycloconverter as in any of claims 1 to 4 or 7, wherein the one of the first gate or the second gate that is cycled on and off is a forward gate and the other one of the first gate or the second gate that is kept on is a reverse gate.

9. The cyclo con verter of claim 1 , wherein in the off mode of the bidirectional switch when the polarity of the blocking voltage cannot be determined both of the first gate and the second gate is cycled on and off.

10. The cycloconverter as in any of claims 1 to 4, 7 or 9, wherein the first gate and the second gate that are cycled on are forward gates.

11. A method for controlling switching of a bidirectional switch, comprising: determining a polarity of a blocking voltage imposed across the bidirectional switch in an off mode of the bidirectional switch; and based on the polarity of the blocking voltage controlling a driving sequence of a first gate and a second gate of the bidirectional switch.

12. The method of claim 11 , wherein the bidirectional switch further comprises a first isolated gate driver and a second isolated gate driver that are respectively connected to the first gate and the second gate, and wherein each of the first isolated gate driver and the second isolated gate driver comprises logic circuitry that is configured to determine the polarity of the blocking voltage and based on thepolarity of the blocking voltage control the driving sequence of the first gate and the second gate.

13. The method of claim 12, wherein the logic circuitry on the first isolated gate driver and the second isolated gate driver is identical to each other.

14. The method of claim 12, wherein a resistor is coupled across the first isolated gate driver and the second isolated gate driver, and wherein the blocking voltage causes current to flow through the resistor and into one of the first isolated gate driver or the second isolated gate driver and out of the other one of the first isolated gate driver or the second isolated gate driver.

15. The method as in any of claims 12 to 14, wherein the first isolated gate driver and the second isolated gate driver are configured to receive a pulse width modulation signal.

16. The method of claim 11 , wherein the bidirectional switch is configured for use in at least one of a normal mode switching, a safe mode switching, or a safe+ mode switching.

17. The method of claim 11 , wherein in the off mode of the bidirectional switch when the polarity of the blocking voltage can be determined one of the first gate or the second gate is cycled on and off and the other one of the first gate or the second gate is kept on.

18. The method as in any of claims 11 to 14, 16, or 17, wherein the one of the first gate or the second gate that is cycled on and off is a forward gate and the other one of the first gate or the second gate that is kept on is a reverse gate.

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