Discharge unit

Abstract

To provide an improved discharge unit for a power converter comprising an inductive element.SOLUTION: A discharge unit is configured to: sense a voltage difference across an inductive element; and activate a discharge path for a power converter based on the voltage difference.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a discharge unit, and more particularly to a discharge unit for a power converter including an inductive element. [Background technology]

[0002] Power converters often contain inductive elements for storing energy. There are situations where the inductive element stores energy that cannot be transferred as current to a load or safely discharged through a low-impedance node. In such a situation, if the inductive element were to force current through a high-impedance node, the voltage would rise until some damaging breakdown occurred. Therefore, a safe means of discharging the inductive element is required.

[0003] The power converter may be utilized as part of a gate driver unit (GDU) for an inverter in electric vehicle applications. Each GDU requires a power converter with its own inductive element, which requires a safe discharge means. Summary of the Invention [Problem to be solved by the invention]

[0004] It would be desirable to provide an improved discharge unit for a power converter.

[0005] As the electrification of automobiles continues to grow, there is a need to improve the method of discharging voltage in power converters to design efficient and cost-effective electric vehicle systems. [Means for solving the problem]

[0006] According to a first aspect of the present disclosure, there is provided a discharge unit for a power converter including an inductive element, the discharge unit configured to sense a voltage difference across the inductive element and enable a discharge path for the power converter based on the voltage difference.

[0007] Optionally, the inductive element is coupled between a first node providing a first voltage and a second node providing a second voltage.

[0008] Optionally, the inductive element includes at least one inductor and a transformer.

[0009] Optionally, a voltage sensing unit for sensing a voltage difference across the inductive element.

[0010] Optionally, the inductive element is coupled between a first node providing a first voltage and a second node providing a second voltage.

[0011] Optionally, the voltage sensing unit is configured to receive a first voltage and a second voltage, and the voltage difference is a difference between the first voltage and the second voltage.

[0012] Optionally, the voltage sensing unit is configured to compare the voltage difference with a threshold voltage, and the discharge unit is configured to enable the discharge path based on the comparison of the voltage difference with the threshold voltage, thereby enabling the discharge path based on the voltage difference.

[0013] Optionally, the threshold voltage is a preset value.

[0014] Optionally, the voltage sensing unit includes at least one series arrangement of one or more Zener diodes, such that the threshold voltage is proportional to the number of Zener diodes.

[0015] Optionally, the voltage sensing unit is configured to enable a discharge path for the power converter when the voltage difference is greater than a threshold voltage, whereby the discharge path is enabled based on a comparison of the voltage difference with the threshold voltage.

[0016] Optionally, the voltage sensing unit includes at least one series configuration of one or more Zener diodes, and the threshold voltage is proportional to the number of Zener diodes such that when a voltage difference is greater than the threshold voltage, a conduction current is conducted through the at least one series configuration of the one or more Zener diodes.

[0017] Optionally, the voltage sensing unit includes a resistive element such that an operating voltage is generated when a conduction current is conducted through at least one series arrangement of one or more Zener diodes.

[0018] Optionally, the discharge unit is configured to disable a discharge path for the power converter based on the voltage difference.

[0019] Optionally, the voltage sensing unit is configured to compare the voltage difference with a threshold voltage, and the discharge unit is configured to disable the discharge path based on the comparison of the voltage difference with the threshold voltage, thereby disabling the discharge path based on the voltage difference.

[0020] Optionally, the voltage sensing unit is configured to disable the discharge path for the power converter when the voltage difference is less than a threshold voltage, thereby disabling the discharge path based on a comparison of the voltage difference with the threshold voltage.

[0021] Optionally, the voltage sensing unit includes at least one series configuration of one or more Zener diodes, and the threshold voltage is proportional to the number of Zener diodes such that no conduction current is conducted through the at least one series configuration of the one or more Zener diodes when the voltage difference is less than the threshold voltage.

[0022] Optionally, the voltage sensing unit includes a resistive element such that no operating voltage is generated when the conduction current is not conducted through at least one series arrangement of one or more Zener diodes.

[0023] Optionally, the discharge path includes a first current source.

[0024] Optionally, a voltage sensing unit for sensing a voltage difference across the inductive element.

[0025] Optionally, the voltage sensing unit is configured to compare the voltage difference with a threshold voltage, and the discharge unit is configured to configure the discharge path based on the comparison of the voltage difference with the threshold voltage, thereby enabling the discharge path based on the voltage difference.

[0026] Optionally, the voltage sensing unit is configured to enable a discharge path for the power converter when the voltage difference is greater than a threshold voltage, whereby the discharge path is enabled based on a comparison of the voltage difference with the threshold voltage, and the voltage sensing unit is configured to activate the first current source when the voltage difference is greater than the threshold voltage.

[0027] Optionally, the voltage sensing unit includes at least one series configuration of one or more Zener diodes, and the threshold voltage is proportional to the number of Zener diodes such that when a voltage difference is greater than the threshold voltage, current is conducted through the at least one series configuration of the one or more Zener diodes.

[0028] Optionally, the voltage sensing unit includes a resistive element such that an operating voltage is generated when current is conducted through at least one series arrangement of one or more Zener diodes.

[0029] Optionally, the first current source is activated by an operating voltage.

[0030] Optionally, the first current source includes a first transistor and a second transistor, both of which include a control terminal coupled to the resistive element such that both of the first transistor and the second transistor are turned on when an operating voltage is generated.

[0031] Optionally, when both the first transistor and the second transistor are turned on, the first transistor and the second transistor conduct a first current.

[0032] Optionally, the discharge path includes a clamp switch coupled to the first current source.

[0033] Optionally, a voltage sensing unit for sensing a voltage difference across the inductive element.

[0034] Optionally, the voltage sensing unit is configured to compare the voltage difference with a threshold voltage, and the discharge unit is configured to enable the discharge path based on the comparison of the voltage difference with the threshold voltage, thereby enabling the discharge path based on the voltage difference.

[0035] Optionally, the voltage sensing unit is configured to enable a discharge path for the power converter when the voltage difference is greater than a threshold voltage, whereby the discharge path is enabled based on a comparison of the voltage difference with the threshold voltage, and the discharge unit is configured to close the clamp switch when the voltage difference is greater than the threshold voltage.

[0036] Optionally, the inductive element is discharged via a clamp switch when the voltage difference is greater than a threshold voltage.

[0037] Optionally, the clamp switch is configured to operate at a threshold voltage.

[0038] Optionally, the voltage sensing unit is configured to activate the first current source when the voltage difference is greater than a threshold voltage.

[0039] Optionally, the voltage sensing unit includes at least one series configuration of one or more Zener diodes, and the threshold voltage is proportional to the number of Zener diodes such that when a voltage difference is greater than the threshold voltage, current is conducted through the at least one series configuration of the one or more Zener diodes.

[0040] Optionally, the voltage sensing unit includes a resistive element such that an operating voltage is generated when current is conducted through at least one series arrangement of one or more Zener diodes.

[0041] Optionally, the first current source is activated by an operating voltage.

[0042] Optionally, the first current source includes a first transistor and a second transistor, both of which include a control terminal coupled to the resistive element such that both of the first transistor and the second transistor are turned on when an operating voltage is generated.

[0043] Optionally, when both the first transistor and the second transistor are turned on, the first transistor and the second transistor conduct a first current.

[0044] Optionally, the clamp switch is a third transistor including a control terminal coupled to the first transistor and the second transistor.

[0045] Optionally, the clamp switch is configured to turn on upon receiving the first current.

[0046] Optionally, the voltage discharge unit is configured to disable a discharge path for the power converter based on the voltage difference.

[0047] Optionally, a voltage sensing unit for sensing a voltage difference across the inductive element.

[0048] Optionally, the voltage sensing unit is configured to compare the voltage difference with a threshold voltage, and the discharge unit is configured to disable the discharge path based on the comparison of the voltage difference with the threshold voltage, thereby disabling the discharge path based on the voltage difference.

[0049] Optionally, the voltage sensing unit is configured to disable a discharge path for the power converter when the voltage difference is less than a threshold voltage, whereby the discharge path is disabled based on a comparison of the voltage difference with the threshold voltage, and the voltage sensing unit is configured to deactivate the first current source when the voltage difference is less than the threshold voltage.

[0050] Optionally, the voltage sensing unit includes at least one series configuration of one or more Zener diodes, and the threshold voltage is proportional to the number of Zener diodes such that no current is conducted through the at least one series configuration of the one or more Zener diodes when the voltage difference is greater than the threshold voltage.

[0051] Optionally, the voltage sensing unit includes a resistive element such that no operating voltage is generated when current is not conducted through at least one series arrangement of one or more Zener diodes.

[0052] Optionally, the first current source is in an inactive state since no operating voltage is generated.

[0053] Optionally, the first current source includes a first transistor and a second transistor, both of which include a control terminal coupled to the resistive element such that both the first transistor and the second transistor are on when an operating voltage is generated, and such that both the first transistor and the second transistor are off when no operating voltage is generated.

[0054] Optionally, when both the first transistor and the second transistor are on, the first transistor and the second transistor conduct the first current, and when both the first transistor and the second transistor are off, the first transistor and the second transistor do not conduct the first current.

[0055] Optionally, the discharge path includes a clamp switch coupled to the first current source.

[0056] Optionally, the voltage discharge unit is configured to open the clamp switch when the voltage difference is less than a threshold voltage.

[0057] Optionally, the discharge unit includes a second current source coupled to the clamp switch.

[0058] Optionally, the second current source is configured to open the clamp switch when the voltage difference is less than a threshold voltage.

[0059] Optionally, the second current source includes a resistive element.

[0060] Optionally, the discharge unit includes an insulating device.

[0061] Optionally, the isolation device is coupled to a second node providing a second voltage, the isolation device being configured to interrupt the conductive path between the first node and the second node when the second node is coupled to ground.

[0062] Optionally, the power converter includes a power switch coupled to ground, the power switch configured to operate in an on state or an off state.

[0063] Optionally, the inductive element is coupled between a first node providing the first voltage and a second node providing the second voltage, and the power switch is coupled to the second node providing the second voltage.

[0064] Optionally, the discharge unit includes an insulating device.

[0065] Optionally, the isolation device is coupled to the second node.

[0066] Optionally, the isolation device is configured to interrupt a conductive path between the first node and the second node when the power switch is in an on state, thereby coupling the second node to ground.

[0067] According to a second aspect of the present disclosure, there is provided an apparatus including a power converter including an inductive element and a discharge unit for the power converter, the discharge unit configured to sense a voltage difference across the inductive element and enable a discharge path for the power converter based on the voltage difference.

[0068] Optionally, the apparatus is a gate driver unit for a traction inverter.

[0069] Optionally, a chip is included, with the power converter and discharge unit being mounted on the chip.

[0070] It should be noted that the apparatus according to the second aspect may include the features described in relation to the first aspect and may incorporate other features described herein.

[0071] According to a third aspect of the present disclosure, there is provided a method for discharging a power converter including an inductive element, the method comprising sensing a voltage difference across the inductive element and enabling a discharge path for the power converter based on the voltage difference.

[0072] It is noted that the method according to the third aspect may include using and / or providing features described in relation to the first and / or second aspect, and may incorporate other features described herein. [Brief explanation of the drawings]

[0073] The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a diagram of a prior art flyback power converter. [Figure 2] 1 is a diagram of an embodiment of a discharge unit for a power converter according to the present disclosure. [Figure 3]FIG. 10 is a diagram of another embodiment of a discharge unit for a power converter according to the present disclosure. [Figure 4(a)] 4 is a diagram of a first embodiment of a voltage sensing unit that can be used in the discharge unit of FIG. 3. [Figure 4(b)] 4 is a diagram of a second embodiment of a voltage sensing unit that can be used in the discharge unit of FIG. 3. [Figure 4(c)] 10 is a diagram of a second embodiment of a voltage sensing unit when the voltage sensing unit senses that the voltage difference is less than a threshold voltage. FIG. [Figure 5] FIG. 10 is a diagram of another embodiment of a discharge unit for a power converter according to the present disclosure. [Figure 6(a)] 6 is a diagram of a first embodiment of a voltage sensing unit coupled to a first current source that may be used in the discharge unit of FIG. 5. [Figure 6(b)] 6 is a diagram of a second embodiment of a voltage sensing unit coupled to a first current source that may be used in the discharge unit of FIG. 5. [Figure 7] FIG. 10 is a diagram of another embodiment of a discharge unit for a power converter according to the present disclosure. [Figure 8(a)] FIG. 10 is a diagram of an embodiment of a voltage sensing unit that enables a discharge path for a power converter. [Figure 8(b)] FIG. 10 is a diagram of an embodiment of a voltage sensing unit that disables a discharge path for a power converter. [Figure 9] FIG. 10 is a diagram of another embodiment of a discharge unit for a power converter according to the present disclosure. [Figure 10] FIG. 10 is a diagram of another embodiment of a discharge unit for a power converter according to the present disclosure. [Figure 11] FIG. 10 is a diagram of another embodiment of a discharge unit for a power converter according to the present disclosure. [Figure 12] FIG. 12 illustrates how the discharge unit of FIG. 11 operates. [Figure 13] FIG. 10 is a diagram of another embodiment of a discharge unit for a power converter according to the present disclosure. [Figure 14(a)]1 is a diagram of a first embodiment of an insulating device that can be used with any discharge unit of the present disclosure. [Figure 14(b)] FIG. 10 is a diagram of a second embodiment of an insulating device that may be used with any discharge unit of the present disclosure. [Figure 15] 14 is a graph showing a simulation result when the discharge unit of FIG. 13 is used as a part of a gate driver unit. [Figure 16] FIG. 1 is a diagram of an apparatus including any of the discharge units of the present disclosure. [Figure 17] 1 is a flowchart illustrating a method for discharging a power converter in accordance with the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0074] In a power converter with an inductive element that stores energy that cannot be safely delivered to a load or safely discharged through a low-impedance node, the inductive element will force current through a high-impedance node, increasing the voltage in the circuit until a breakdown mechanism occurs. There are many situations in which this can occur, such as when a low-side switch drives an inductive load without a recirculation path for the energy to discharge when the low-side switch is turned off.

[0075] One type of power converter in which such an unsafe discharge event can occur is the flyback converter.

[0076] 1 shows a prior art flyback converter 100. The flyback converter 100 includes a low-side switch LS coupled between ground GND and a node SW. The flyback converter 100 further includes an inductive element 110. In this prior art embodiment, the inductive element 110 includes an inductor L coupled to a transformer T. LK Includes.

[0077] In normal operation mode, when the low-side switch LS is turned on, the primary winding of the transformer T is charged. When the low-side switch LS is turned off, the energy stored in the primary winding is transferred to the secondary winding of the transformer T.

[0078] The energy that cannot be transferred between the primary and secondary windings is transferred through the leakage inductance L coupled to the primary winding of the transformer T. LK Each time the low-side switch LS is turned off, L LK The energy stored in the leakage inductance has nowhere to go. As a result, node SW will jump to a high voltage that is destructive to at least the low-side switch LS and the semiconductor chip (not shown in FIG. 1) hosting the flyback controller. A common solution is to place a voltage clamp 120 on the primary side of transformer T to clamp the voltage at node SW to a safe value above the input voltage Vin of the flyback converter 100. This allows the energy on the leakage inductance to be safely discharged when the low-side switch LS turns off. In the flyback converter 100 shown in FIG. 1, the voltage clamp 120 is implemented using a combination of Zener and Schottky diodes. In other embodiments, an external resistor / capacitor snubber can be used.

[0079] These solutions can also be applied to other types of power converters. LK Known solutions in the prior art for safely discharging the energy of a device require external components that increase the cost and size of the circuit.

[0080] A power converter, such as the flyback converter shown in Figure 1, can be used as part of a gate driver unit for an inverter. High-voltage gate driver units (GDUs) drive the inverter switches in electric vehicle applications. Each GDU requires a specific voltage to drive the gates of the insulated gate bipolar transistor (IGBT) or silicon carbide (SiC) power switches. These specific voltages are not available in the system and are instead generated by a power converter, such as a flyback converter. Due to galvanic isolation requirements in onboard systems, each GDU requires a separate flyback converter, at least for the inverter's high-side switches. The most common configuration used in electric vehicles is a distributed architecture. Here, each switch in the inverter has a GDU with its own separate flyback converter. This architecture requires the addition of 12 external voltage clamps to the GDU board. For example, for a 400V / 100kW traction inverter, the extra area required for these external voltage clamps is approximately 50mm. 2 is.

[0081] One of the driving requirements in the race towards electrification of transportation is to design traction inverters with the highest power density (more compact) and reduced cost. Therefore, improved means of safely discharging the inductive elements of the power converter are needed to reduce cost and circuit area.

[0082] 2 illustrates one embodiment of a discharge unit 200 for a power converter 202 according to a first embodiment of the present disclosure. The power converter 202 includes an inductive element 204. The inductive element 204 is coupled between a first node N1 providing a first voltage V1 and a second node N2 providing a second voltage V2. The inductive element 204 may include, for example, at least one of an inductor or a transformer. This is not an exhaustive list of elements that may be used.

[0083] The discharge unit 200 generates a voltage difference V across the energy storage element 204. diff The voltage difference is the difference between the first voltage V1 and the second voltage V2. The discharge unit 200 is configured to sense the voltage difference V diff is configured to enable a discharge path DP for the power converter 202 based on

[0084] 3 shows another embodiment of a discharge unit 200 for a power converter 202 according to the second embodiment of the present disclosure. The power converter 202 is the same as the power converter of FIG. 2. Therefore, the same reference numerals are used, and its components have the same functions and meanings as those of FIG. 2. The discharge unit 200 is the same as that of FIG. 2, except for the addition of feature 210. Therefore, the same reference numerals are used, and its components have the same functions and meanings as those of the discharge unit 200 of FIG. 2.

[0085] The discharge unit 200 generates a voltage difference V across the inductive element 204. diff The energy storage element 204 includes a voltage sensing unit 210 for sensing a voltage V. The energy storage element 204 is coupled between a first node N1 providing a first voltage V1 and a second node N2 providing a second voltage V2.

[0086] The voltage sensing unit 210 is configured to receive the first voltage V1 and the second voltage V2. The voltage difference V2 sensed by the voltage sensing unit 210 is diff is the difference between the first voltage V1 and the second voltage V2. The voltage sensing unit 210 detects the voltage difference V diff and threshold voltage V thresh Depending on the result of the comparison, the discharge unit 210 is configured to enable a discharge path DP for the power converter 200. diff The discharge path DP is enabled when V is greater than the threshold voltage. diff (=V2-V1)>V thresh The discharge path DP is enabled when the voltage difference V diffand further configured to disable a discharge path DP for the power converter 200 based on the voltage difference V diff The discharge path DP is disabled when V is less than the threshold voltage. diff (=V2-V1) <V thresh When the condition is satisfied, the discharge path DP is invalid.

[0087] Threshold voltage V thresh may be a preset value. For example, the threshold voltage V thresh may be set to be equal to the maximum breakdown voltage of the components in the discharge unit 200 and the power converter 202. thresh can be set by the voltage sensing unit 210.

[0088] 4(a) illustrates a first embodiment of a voltage sensing unit 210 that can be used with any of the discharge units 200 of the present disclosure. The arrows pointing to nodes N1 and N2 in the figure indicate the coupling points of the voltage sensing unit 210 to the nodes N1 and N2. It should be noted that other couplings are possible according to the understanding of those skilled in the art. In this first embodiment of the voltage sensing unit 210, the voltage sensing unit 210 includes one or more Zener diodes Z to Z. n In this embodiment, the threshold voltage is proportional to the number of Zener diodes in the series configuration. That is, if n represents the number of Zener diodes in the series configuration, then V thresh ∝n.

[0089] 4(b) illustrates a second embodiment of a voltage sensing unit 210 that may be used with any of the discharge units 200 of the present disclosure. The arrows pointing to nodes N1 and N2 in the figure indicate the coupling points of the voltage sensing unit 210 to the nodes N1 and N2. It should be noted that other couplings are possible according to the understanding of those skilled in the art. In this second embodiment of the voltage sensing unit 210, the voltage sensing unit 210 includes one or more Zener diodes Z to Z. n and one or more Zener diodes Z' to Z mand a second series configuration of one or more Zener diodes, n=m. In one embodiment, the total number of Zener diodes in the first series configuration and the second series configuration of one or more Zener diodes is the same. That is, n=m. In this case, the threshold voltage V thresh is proportional to the number of Zener diodes in a series configuration (n=m). That is, if n represents the total number of Zener diodes in a series configuration and n=m, then V thresh In another embodiment, the total number of Zener diodes in the first series configuration of one or more Zener diodes and the second series configuration of one or more Zener diodes are not the same. That is, n is not equal to m. In this case, the threshold voltage V thresh is proportional to the total number of Zener diodes in each series configuration. That is, if n represents the total number of Zener diodes in the first series configuration and m represents the total number of Zener diodes in the second series configuration, then V thresh ∝(n+m). The voltage sensing unit 210 further includes a resistive element R coupled between the first series configuration of one or more Zener diodes and the second series configuration of one or more Zener diodes. The resistive element may be, for example, a resistor.

[0090] Voltage difference V diff is the threshold voltage V thresh If it is greater than c is applied to the first and second series configurations of one or more Zener diodes to generate an operating voltage V a is conducted across the resistive element R so that V is generated. The voltage sensing unit 210 is shown as a combination of an (integrated) Zener diode and a resistor. The voltage sensing unit 210 diff (=V2-V1) is the threshold voltage V thresh Only when the current I c It has the function of flowing water.

[0091] FIG. 4(c) is a schematic diagram of an alternative embodiment of the voltage sensing unit 210 of FIG. 4(b), illustrating an operational configuration where no current is conducted through the voltage sensing unit 210. The voltage sensing unit 210 is the same as the voltage sensing unit of FIG. 4(b). Accordingly, the same reference numerals are used and the components have the same functions and meanings as those in FIG. 4(b). The arrows pointing to nodes N1 and N2 in the diagram indicate the coupling points of the voltage sensing unit 210 to nodes N1 and N2. It should be noted that other couplings are possible according to the understanding of one skilled in the art. The voltage difference V diff is the threshold voltage V thresh If it is smaller than c is not conducted through the first series configuration of one or more Zener diodes or the second series configuration of one or more Zener diodes. This prevents the operating voltage V across the resistive element R. a is not generated.

[0092] 5 shows another embodiment of a discharge unit 200 for a power converter 202 according to a third embodiment of the present disclosure. The power converter 202 is the same as the power converter of FIG. 3. Therefore, the same reference numerals are used, and its components have the same functions and meanings as those of FIG. 3. The discharge unit 200 is the same as that of FIG. 3, except for the addition of a feature 220. Therefore, the same reference numerals are used, and its components have the same functions and meanings as those of the discharge unit 200 of FIG. 3. The discharge path DP includes a first current source 220 coupled to a voltage sensing unit 210.

[0093] The voltage sensing unit 210 detects the voltage difference V diff is the threshold voltage V thresh , activating first current source 220 when first current source 220 is greater than . This enables a discharge path DP for power converter 200 when first current source 220 is activated.

[0094] 6(a) shows a first embodiment of a voltage sensing unit 210 coupled to a first current source 220. The embodiment in this figure can be used with any of the discharge units 200 of the present disclosure. The arrows pointing to nodes N1 and N2 in the figure indicate the coupling points of the voltage sensing unit 210 to the nodes N1 and N2. It should be noted that other couplings are possible according to the understanding of those skilled in the art. The voltage sensing unit 210 is coupled to one or more Zener diodes Z to Z. n and one or more Zener diodes Z' to Z m and a second series configuration of one or more Zener diodes, n=m. In one embodiment, the total number of Zener diodes in the first series configuration and the second series configuration of one or more Zener diodes is the same. That is, n=m. In this case, the threshold voltage V thresh is proportional to the number of Zener diodes in a series configuration (n=m). That is, if n represents the total number of Zener diodes in a series configuration and n=m, then V thresh ∝n×V zener Voltage V zener is the breakdown voltage of each Zener diode. In another embodiment, the total number of Zener diodes in the first series configuration of one or more Zener diodes and the second series configuration of one or more Zener diodes are not the same. That is, n is not equal to m. In this case, the threshold voltage V thresh is proportional to the total number of Zener diodes in each series configuration. That is, if n represents the total number of Zener diodes in the first series configuration and m represents the total number of Zener diodes in the second series configuration, then V thresh ∝(n+m)×V zener Voltage V zener is the breakdown voltage of each Zener diode. The voltage sensing unit 210 further includes a resistive element R coupled between the first series configuration of one or more Zener diodes and the second series configuration of one or more Zener diodes. The resistive element may be, for example, a resistor.

[0095] Voltage difference V diff is the threshold voltage V thresh If it is greater thanc is applied to the first and second series configurations of one or more Zener diodes to generate an operating voltage V a The first current source 220 then conducts across the resistive element R so that the operating voltage V a The voltage sensing unit 210 is activated by V diff (=V2-V1) is the threshold voltage V thresh Only when the current I c This allows V diff (=V2-V1) is the threshold voltage V thresh The first current source is activated only when

[0096] FIG. 6(b) shows a second embodiment of the voltage sensing unit 210 coupled to the first current source 220. The embodiment in this figure can be used with any of the discharge units 200 of the present disclosure. The arrows pointing to nodes N1 and N2 in the figure indicate the coupling points of the voltage sensing unit 210 to the nodes N1 and N2. Note that other couplings are possible according to the understanding of those skilled in the art. The voltage sensing unit 210 in this figure is the same as that in FIG. 6(a). Therefore, the same reference numerals are used, and the components have the same functions and meanings as those in FIG. 6(a).

[0097] The first current source 220 includes a first transistor T1 having a control terminal and a second transistor T2 having a control terminal. The first transistor T1 is coupled in series with the second transistor T2. The first transistor T1 and the second transistor T2 are coupled to the resistive element R of the voltage sensing unit 210 via their respective control terminals.

[0098] Operating voltage V a When the voltage difference V diff is the threshold voltage V thresh is smaller than the operating voltage V ais not generated, the first transistor T1 and the second transistor T2 are turned off.

[0099] FIG. 7 shows another embodiment of a discharge unit 200 for a power converter 202 according to a fourth embodiment of the present disclosure. The power converter 202 is the same as the power converter of FIG. 5 . Accordingly, the same reference numerals are used, and its components have the same functions and meanings as those of FIG. 5 . The discharge unit 200 is the same as that of FIG. 5 , except for the addition of a feature SW. Accordingly, the same reference numerals are used, and its components have the same functions and meanings as those of the discharge unit 200 of FIG. 5 . The discharge path DP includes a clamp switch SW coupled to a first current source 220.

[0100] The voltage sensing unit 210 detects the voltage difference V diff = (V2-V1) is the threshold voltage V thresh The voltage sensing unit 210 is configured to enable a discharge path DP for the power converter 200 when the voltage difference V diff is the threshold voltage V thresh , which enables the discharge path DP. When the clamp switch SW is closed, the inductive element 204 is discharged through the clamp switch SW. The clamp switch SW is configured to close when the voltage V thresh This allows the clamp switch to operate at a threshold voltage V thresh The inductive element is discharged at a maximum voltage of V. diff is the threshold voltage V thresh When first current source 220 is activated, clamp switch SW is closed and inductive element 204 is discharged through clamp switch SW.

[0101] The discharge unit 200 also detects a voltage difference V diffThe discharge unit 200 is configured to disable the discharge path DP for the power converter 200 based on the voltage difference V diff is the threshold voltage V thresh , which may disable the discharge path DP for power converter 200.

[0102] The voltage sensing unit 210 detects the voltage difference V diff is the threshold voltage V thresh The voltage sensing unit 210 is also configured to disable the discharge path DP when the voltage difference V diff is the threshold voltage V thresh , configured to deactivate first current source 220 when V is less than 1. A clamp switch SW is coupled to first current source 220 such that the clamp switch is opened when first current source 220 is deactivated.

[0103] In summary, the clamp switch SW acts to clamp the voltage resulting from the inductive element attempting to discharge stored magnetic energy. It does this by providing a safe discharge path for the current while keeping the voltage clamped to a safe value.

[0104] 8(a) illustrates one embodiment of a voltage sensing unit 210 enabling a discharge path DP for power converter 200. The arrows pointing to nodes N1 and N2 in the figure indicate the coupling points of voltage sensing unit 210 to nodes N1 and N2. It should be noted that other couplings are possible according to the understanding of one skilled in the art. Another arrow pointing to inductive element 204 indicates the coupling point of discharge path DP to power converter 200. It should be noted that other couplings are possible according to the understanding of one skilled in the art.

[0105] The voltage sensing unit 210 includes one or more Zener diodes Z to Z n and one or more Zener diodes Z' to Z mand a second series configuration of one or more Zener diodes, n=m. In one embodiment, the total number of Zener diodes in the first series configuration and the second series configuration of one or more Zener diodes is the same. That is, n=m. In this case, the threshold voltage V thresh is proportional to the number of Zener diodes in a series configuration (n=m). That is, if n represents the total number of Zener diodes in a series configuration and n=m, then V thresh ∝n×V zener Voltage V zener is the breakdown voltage of each Zener diode. In another embodiment, the total number of Zener diodes in the first series configuration of one or more Zener diodes and the second series configuration of one or more Zener diodes are not the same. That is, n is not equal to m. In this case, the threshold voltage V thresh is proportional to the total number of Zener diodes in each series configuration. That is, if n represents the total number of Zener diodes in the first series configuration and m represents the total number of Zener diodes in the second series configuration, then V thresh ∝(n+m)×V zener Voltage V zener is the breakdown voltage of each Zener diode. The voltage sensing unit 210 further includes a resistive element R coupled between the first series configuration of one or more Zener diodes and the second series configuration of one or more Zener diodes. The resistive element may be, for example, a resistor. The voltage difference V diff is the threshold voltage V thresh If it is greater than c is applied to the first and second series configurations of one or more Zener diodes to generate an operating voltage V a is conducted across the resistive element R so that V is generated. The voltage sensing unit 210 is shown as a combination of an (integrated) Zener diode and a resistor. The voltage sensing unit 210 diff (=V2-V1) is the threshold voltage V thresh Only when the current I c It has the function of flowing water.

[0106] The discharge path DP includes a first current source coupled to the clamp switch SW.

[0107] The first current source 220 includes a first transistor T1 having a control terminal and a second transistor T2 having a control terminal. The first transistor T1 is coupled in series with the second transistor T2. The first transistor T1 and the second transistor T2 are coupled to the resistive element R of the voltage sensing unit 210 via their respective control terminals. The operating voltage V a is generated, the first transistor T1 and the second transistor T2 turn on and together conduct a first current I1.

[0108] In this embodiment, the clamp switch SW is a third transistor having a control terminal. The control terminal of the clamp switch SW is coupled to the first transistor and the second transistor. The clamp switch SW is configured to be turned on (closed) upon receiving the first current I1. The clamp switch SW is connected to a third transistor having a threshold voltage V thresh The voltage difference V diff = (V2-V1) reaches the threshold voltage, the conduction current I c begins to flow through the voltage sensing unit 210, and the operating voltage V required to activate the first current source 220 a When the clamp switch SW is appropriately sized, the control terminal of the clamp switch SW generates a threshold voltage V thresh This allows the clamp switch SW to operate in saturation while discharging the inductive element 204.

[0109] The components of the voltage sensing unit 210, the first current source 220, and the clamp switch SW are selected so that they can withstand the appropriate voltages at which they will be utilized.

[0110] FIG. 8(b) is an alternative schematic diagram of the voltage sensing unit 210 of FIG. 8(a). Here, the voltage sensing unit 210 disables the discharge path DP for the power converter 200. The arrows pointing to nodes N1 and N2 in the diagram indicate the coupling points of the voltage sensing unit 210 to nodes N1 and N2. Note that other couplings are possible according to the understanding of one skilled in the art. Another arrow pointing to the inductive element 204 indicates the coupling point of the discharge path DP to the power converter 200. Note that other couplings are possible according to the understanding of one skilled in the art. The voltage sensing unit 210 in this diagram is the same as that in FIG. 8(a). Accordingly, the same reference numerals are used, and the components have the same functions and meanings as those in FIG. 8(a). The discharge path DP includes a first current source 220 coupled to a clamp switch SW. The first current source 220 and the clamp switch SW are the same as those in FIG. 8(a). Therefore, the same reference numerals are used and the components have the same functions and meanings as those in FIG. 8(a).

[0111] Voltage difference V diff is the threshold voltage V thresh If it is smaller than c is not conducted through the first and second series configurations of one or more Zener diodes. This prevents the operating voltage V from being applied across the resistive element R. a The voltage sensing unit 210 detects V diff (=V2-V1) is the threshold voltage V thresh Only when the current I c This allows V diff is less than the threshold voltage, the current I c is not conducted.

[0112] Operating voltage V a , is not generated, the first current source 220 is in an inactive state. This causes the first transistor T1 and the second transistor T2 to supply the operating voltage V aWhen both the first transistor T1 and the second transistor T2 are off, they do not conduct the first current I1. When the inductive element 204 is discharged, the voltage difference V diff is the threshold voltage V thresh This deactivates the first current source 220 and turns off the clamp switch SW.

[0113] FIG. 9 shows another embodiment of a discharge unit 200 for a power converter 202 according to a fifth embodiment of the present disclosure. The power converter 202 is the same as the power converter of FIG. 7. Accordingly, the same reference numerals are used, and its components have the same functions and meanings as those of FIG. 5. The discharge unit 200 is the same as that of FIG. 7, except for the addition of features 230 and 232. Accordingly, the same reference numerals are used, and its components have the same functions and meanings as those of the discharge unit 200 of FIG. 7. The discharge unit 200 further includes a second current source 230 coupled to the clamp switch SW.

[0114] The second current source 230 generates a voltage difference V diff = (V2-V1) is the threshold voltage V thresh The second current source 230 includes a resistive element 232. The resistive element 232 may be implemented as a resistor. This is the simplest implementation that requires no additional signals and keeps the second current source 230 always active. The resistive element 232 is configured to open the clamp switch SW when the voltage difference V diff is the threshold voltage V thresh The inductive element 204 may be implemented in any manner that provides a current strong enough to keep the clamp switch off (open) when the voltage difference V diff is the threshold voltage V thresh This deactivates the first current source 220 and the second current source keeps the clamp switch SW open (off). The clamp switch SW is naturally inactive, draws no quiescent current, and does not require a control signal to operate.

[0115] FIG. 10 shows another embodiment of a discharge unit 200 for a power converter 202 according to the sixth embodiment of the present disclosure. The power converter 202 is the same as the power converter of FIG. 2. Therefore, the same reference numerals are used and the components have the same functions. The discharge unit 200 is the same as that of FIG. 2 except for the addition of feature 240. Therefore, the same reference numerals are used and the components have the same functions and meanings as the discharge unit 200 of FIG. 2. It should be noted that this additional feature 240 may also be applied to any of the discharge units 200 described in the present disclosure.

[0116] The discharge unit 200 includes an isolation device 240. The isolation device 240 is coupled to a second node N2 that provides a second voltage V2. The isolation device 240 is configured to interrupt the conductive path between the first node N1 and the second node N2 when the second node N2 is coupled to ground.

[0117] 11 shows another embodiment of a discharge unit 200 for a power converter 202 according to the seventh embodiment of the present disclosure. The discharge unit 200 has the same meaning as any of the other embodiments of the discharge unit in the present disclosure. Therefore, the same reference numerals are used, and the components have the same meaning and function as those described above. It should be noted that any of the features of the embodiments described in the present disclosure may also be applied to the discharge unit 200 described in the present disclosure.

[0118] Power converter 202 includes an inductive element 204 and a power switch LS coupled to ground GND. Inductive element 204 is coupled between a first node N1 providing a first voltage VIN and a second node N2 providing a second voltage VSW. Note that first node N1 and second node N2 are equivalent to first node N1 and second node N2 in other embodiments of power converter 202, and first voltage VIN and second voltage VSW are equivalent to first voltage V1 and second voltage V2 in other embodiments of power converter 202. Power switch LS is also coupled to second node N2 providing second voltage VSW. Power switch LS is configured to operate in an on or off state. When power switch LS is in an on state, inductive element 204 is charged. When power switch LS is in an off state, inductive element 204 is discharged.

[0119] The discharge unit 200 includes an isolation device 240. The isolation device is also coupled to a second node N2. The isolation device may be, for example, a passive diode. The isolation device 240 is configured to interrupt the conduction path between the first node N1 and the second node N2 when the second node N1 is coupled to ground, for example, when the power switch LS is in an on state.

[0120] The voltage sensing unit 210 senses the difference between the second voltage VSW and the first voltage VIN, and compares the result with a threshold voltage V thresh The difference (VSW-VIN) is the threshold voltage V thresh When the difference (VSW-VIN) is greater than the threshold voltage V, the first current source 220 is activated (clamp_on) and the clamp switch SW is closed (on). This causes the inductive element 204 to be discharged through the discharge path DP. thresh When Vcc is less than 1 V, the first current source 220 is deactivated and the clamp switch SW is opened (turned off), thereby disabling the discharge path DP.

[0121] In the embodiment of Figure 11, the discharge unit 200 is shown as an on-chip solution applied to a power converter 202. The clamp switch SW is a transistor. The power converter 202 in Figure 11 is shown as a flyback converter, but it can be any type of DC power converter, for example, a boost converter.

[0122] FIG. 12 is a timing graph illustrating how the voltage sensing unit 200 for the power converter 202 shown in FIG. 11 operates.

[0123] SIG1 in the upper plot shows the waveform of the control signal that controls the operation of power switch LS. Before point A, the SIG1 waveform is high, and power switch LS is set to the on state, thus charging inductive element 204. After point A, the SIG1 waveform is low, and power switch LS is set to the off state.

[0124] In the center plot, SIG2 indicates the voltage VSW at the second node N2 compared to the voltage V at the first node N1. Before point A, the voltage difference V between VSW and V diff is the threshold voltage V thresh This disables the discharge path DP. At point A, when the power switch LS is turned off, the voltage at the second node N2 rises by ΔV active clamp above the voltage at the first node N1. This causes the voltage difference V diff is the threshold voltage V thresh becomes larger than the discharge path DP.

[0125] SIG3 in the lower plot represents the current through inductive element 204. Prior to point A, inductive element 204 charges when power switch LS is closed. This causes current SIG3 to increase. At point A, inductive element 204 begins to discharge through effective discharge path P. Thus, current SIG3 decreases by an amount equal to the sum of I_Vsw_sense, I_on, and I_clamp. These are the currents flowing through voltage sense unit 210, first current source 220, and clamp switch SW.

[0126] SIG2 is at a predetermined threshold voltage V thresh , the first current source 220 is deactivated. The second current source 230 keeps the voltage at the control terminal of the clamp switch SW at zero. This causes the current I_clamp through the clamp switch to equal zero. The discharge unit 200 does not draw any current without interfering with the normal operation of the power converter 202.

[0127] When the power switch LS turns off, the leakage inductance of the inductive element 204 continues to force current to flow through the second node N2. Therefore, the voltage at this node begins to rise. thresh , the voltage sensing unit 210 activates the first current source 220. When negative feedback is properly implemented, the control terminal of the clamp switch SW is at a threshold voltage V thresh This causes clamp switch SW to saturate with a drain-source voltage equal to ΔV active clamp, allowing clamp switch SW to dissipate the energy stored in inductive element 204 while the voltage at second node N2 is held at the desired clamp voltage.

[0128] 13 shows another embodiment of a discharge unit 200 for a power converter 202 according to the eighth embodiment of the present disclosure. The discharge unit 200 in this figure is any of the discharge units 200 described in the present disclosure. Therefore, the same reference numerals are used, and the components have the same meanings and functions as those described above. It should be noted that any of the features of the embodiments described in the present disclosure may be applied to the discharge unit 200 described in the present disclosure.

[0129] In this embodiment, the inductive element 204 of the power converter 202 is shown as an inductor. The isolation device 240 is implemented as a passive diode D. However, the isolation device 240 may be any element capable of blocking conduction from the first node N1 to the second node N2 when the second node N2 is coupled to ground GND when the power switch LS is on.

[0130] The isolation device 240 may also be an active diode. Figures 14(a) and 14(b) show embodiments of an active diode that may be used as part of the isolation device 240 in any of the discharge units 200 of the present disclosure.

[0131] FIG. 14(a) illustrates a first embodiment of an isolation device 240 that may be used with any of the discharge units 200 of the present disclosure, according to the understanding of one skilled in the art. The first embodiment of the isolation device 240 illustrated in FIG. 14(a) includes a first transistor 1400, a second transistor 1402, a first diode 1404, and a second diode 1406. Both the first transistor 1400 and the second transistor 1402 include source and drain terminals. The first transistor 1400 and the second transistor 1402 are coupled in a series configuration such that they are coupled via their respective source terminals. The first diode 1404 is coupled in parallel across the source and drain terminals of the first transistor 1400, and the second diode 1406 is coupled in parallel across the source and drain terminals of the second transistor 1402.

[0132] FIG. 14(b) illustrates a second embodiment of an isolation device 240 that may be used with any of the discharge units 200 of the present disclosure, according to the understanding of one skilled in the art. The second embodiment of the isolation device 240 illustrated in FIG. 14(b) includes a first transistor 1410, a first diode 1412, a second diode 1414, and a resistor 1416. The first transistor 1410 includes a source terminal, a drain terminal, and a control terminal. The first diode 1412 is coupled in parallel to the first transistor 1410 across the drain and source terminals of the first transistor 1410. The second diode 1414 is coupled in series to the control terminal of the first transistor 1410. The resistor 1416 is coupled to the source terminal of the first transistor 1410.

[0133] 13, the voltage sensing unit 210 is shown as a combination of an (integrated) Zener diode and a resistor. However, the voltage sensing unit 210 may be any of the embodiments described herein. The voltage sensing unit 210 senses a voltage difference V between the voltage V SW at the second node N2 and the voltage V IN at the first node N1. diff has the function of conducting current only when the voltage at the second node N2 reaches a threshold voltage. As a result, the first current source 220 is enabled with negative feedback that prevents the voltage at the second node N2 from drifting.

[0134] The second current source 230 is implemented as a resistor because this is the simplest implementation that requires no additional signal and leaves the second current source 230 always active. However, it can be implemented in any way that provides a current strong enough to keep the control terminal of the clamp switch SW at zero when the discharge path needs to remain disabled. For example, the second current source can be implemented using a transistor.

[0135] When inductive element 204 is discharged, the voltage difference between VSW and V drops below the threshold voltage, which causes first current source 220 to become inactive and second current source 230 to hold the control terminal of clamp switch SW at zero, causing clamp switch SW to be naturally disabled, drawing no quiescent current, and requiring no control signal for operation.

[0136] Therefore, the voltage at the clamp switch SW is defined as follows: ΔV active clamp = Vzb + Vreg + Vzt + VD where Vzb represents the threshold voltage for the first series configuration of Zener diodes in the voltage sensing unit 210, Vzt represents the threshold voltage for the second series configuration of Zener diodes, and Vreg represents the operating voltage (V a where V represents the voltage across the isolation device 240 (equivalent to VSGp+VGSm), and VD represents the voltage across the isolation device 240. Note that the operating voltage can also be defined in terms of the first transistor M (T1) and the second transistor P (T2) of the first current source 220. The operating voltage is also equal to VSGp+VGSm, which are the control terminal voltages of the first transistor M and the second transistor DP. The voltage sensing unit 210 is implemented as any combination of a series of different components to generate the desired threshold voltage. Any combination of Zener diodes, resistors, and diode-connected transistors can be used to define the threshold voltage.

[0137] Those skilled in the art will recognize and analyze the built-in negative feedback that prevents the voltage VSW at the second node N2 from flowing away from the ΔV active clamp. When the voltage at the second node N2 reaches the ΔV active clamp, a conduction current begins to flow through the voltage sensing unit 210, generating the operating voltage Vreg necessary to enable I_on. When the clamp switch SW is appropriately sized, its control terminal is driven with an appropriate voltage. This allows the clamp switch SW to operate in saturation at a drain-to-source voltage equal to (ΔV active clamp - VD) while discharging the inductive element 204. When the voltage at the second node N2 exceeds the ΔV active clamp, the current through the voltage sensing block 210 increases. This increases Vreg, which increases the current through the first current source 220. This increases the voltage at the control terminal of the clamp switch SW, increasing the current through the clamp switch I_clamp. This creates a counteracting effect that reduces the voltage at the second node N2.

[0138] Preferably, the components of the circuits of the present disclosure are selected to withstand the appropriate operating voltages of the system, according to the understanding of one skilled in the art.

[0139] Particularly for high voltage gate driver units (GDUs), the discharge unit 200 of the present disclosure allows the power converter controller (in this case, a flyback controller) and voltage clamp (discharge unit) to be integrated on the GDU die, reducing the cost and area of ​​the GDU board.

[0140] Figure 15 is a graph showing simulation results when the discharge unit 200 of Figure 13 is used as part of a gate driver unit (GDU). Simulations were performed over all process and temperature conditions for the discharge unit 200 and power converter 200 (implemented as a flyback converter) when a 1 uH inductive element 204 was charged to approximately 2 A.

[0141] When the power switch LS is turned off, the discharge unit 204 reacts by clamping the second node N2 to ensure a discharge path (I_on and I_Vsw_sense are not shown here).

[0142] For the particular process used in these simulations, the ΔV active clamp varies over a range from a minimum of approximately 16 V to a maximum of approximately 21.6 V. These minimum and maximum values ​​must be bounded so as not to interfere with normal operation of the power converter, and bounded so as not to exceed voltages that affect device and component reliability. This variability can be reduced by appropriate selection of components used in voltage sense unit 210 and good layout design. If high accuracy in the ΔV active clamp is required, trimming techniques can be applied to voltage sense unit 210.

[0143] In the specific case of an isolated high voltage GDU for a traction inverter, the discharge unit 200 of the present disclosure was estimated to be only about 6% of the die area of ​​the primary side of the isolated GDU.

[0144] 16 shows an apparatus 400 according to a ninth embodiment of the present disclosure. The apparatus 400 includes a power converter 202 having an inductive element 204 and a discharge unit 200 for the power converter 202. The discharge unit 200 can be any of the embodiments described in the present disclosure. The apparatus 400 further includes a chip 410. The discharge unit 200 and the power converter 202 are mounted on the chip 410. The discharge unit 200 generates a voltage difference V across the inductive element 204. diff and detects the voltage difference V diff is configured to enable a discharge path DP for the power converter 202 based on

[0145] The device 400 may be, for example, a gate driver unit for a traction inverter.

[0146] FIG. 17 is a flowchart illustrating a method for discharging a power converter including an inductive element according to a tenth embodiment of the present disclosure.

[0147] In step 510, a voltage difference across the inductive element is sensed, and then in step 520, a discharge path for the power converter is enabled based on the voltage difference.

[0148] It should be noted that the power converter of the present disclosure may be a flyback converter for a gate driver unit. Further embodiments may relate to power converters for other applications and other input voltages according to the understanding of those skilled in the art.

[0149] Additionally, various improvements and modifications may be made without departing from the scope of the present disclosure.

[0150] Those skilled in the art will appreciate that variations of the disclosed arrangements are possible without departing from the present disclosure. Thus, the above description of specific embodiments is for purposes of illustration and not limitation. Those skilled in the art will appreciate that minor variations can be made without significantly altering the operation of the above.

Claims

1. 1. A discharge unit for a power converter including an inductive element, comprising: sensing a voltage difference across the inductive element; configured to enable a discharge path for the power converter based on the voltage difference. Discharge unit.

2. The discharge unit of claim 1 , comprising a voltage sensing unit for sensing the voltage difference across the inductive element.

3. 3. The discharge unit of claim 2, wherein the inductive element is coupled between a first node providing a first voltage and a second node providing a second voltage.

4. the voltage sensing unit is configured to receive the first voltage and the second voltage; the voltage difference is the difference between the first voltage and the second voltage; The discharge unit according to claim 3 .

5. the voltage sensing unit is configured to compare the voltage difference with a threshold voltage; the discharge unit is configured to enable the discharge path based on a comparison between the voltage difference and the threshold voltage, whereby the discharge path is enabled based on the voltage difference; The discharge unit according to claim 2 .

6. The discharge unit of claim 2 , wherein the discharge unit is configured to disable the discharge path for the power converter based on the voltage difference.

7. the voltage sensing unit is configured to compare the voltage difference with a threshold voltage; the discharge unit is configured to disable the discharge path based on a comparison between the voltage difference and the threshold voltage, whereby the discharge path is disabled based on the voltage difference; The discharge unit according to claim 6.

8. 8. The discharge unit of claim 7, wherein the voltage sensing unit is configured to disable the discharge path for the power converter when the voltage difference is less than the threshold voltage, whereby the discharge path is disabled based on a comparison of the voltage difference with the threshold voltage.

9. The discharge unit of claim 2 , wherein the discharge path includes a first current source.

10. the voltage sensing unit is configured to enable the discharge path for the power converter when the voltage difference is greater than a threshold voltage, whereby the discharge path is enabled based on a comparison of the voltage difference and the threshold voltage; the discharge unit is configured to close a clamp switch when the voltage difference is greater than the threshold voltage. The discharge unit according to claim 9.

11. The discharge unit of claim 10 , wherein the inductive element is discharged through the clamp switch when the voltage difference is greater than the threshold voltage.

12. The discharge unit of claim 9 , wherein the voltage discharge unit is configured to disable the discharge path for the power converter based on the voltage difference.

13. the voltage sensing unit is configured to compare the voltage difference with a threshold voltage; the discharge unit is configured to disable the discharge path based on a comparison between the voltage difference and the threshold voltage, whereby the discharge path is disabled based on the voltage difference; The discharge unit according to claim 12.

14. the voltage sensing unit is configured to disable the discharge path for the power converter when the voltage difference is less than the threshold voltage, whereby the discharge path is disabled based on a comparison of the voltage difference and the threshold voltage; the voltage sensing unit is configured to deactivate the first current source when the voltage difference is less than the threshold voltage; The discharge unit according to claim 13.

15. the discharge unit includes a second current source coupled to the clamp switch; the second current source is configured to open the clamp switch when the voltage difference is less than the threshold voltage. The discharge unit according to claim 14.

16. a power converter including an inductive element; a discharge unit for the power converter, sensing a voltage difference across the inductive element; a discharge unit configured to enable a discharge path for the power converter based on the voltage difference; An apparatus comprising:

17. 1. A method of discharging a power converter including an inductive element, comprising: sensing a voltage difference across the inductive element; enabling a discharge path for the power converter based on the voltage difference; A method comprising:

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