Discharge unit

Abstract

The invention relates to a discharge unit. 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 activating a discharge path for the power converter based on the voltage difference.

Description

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

[0002] Power converters often include inductive elements for energy storage. Sometimes, an inductive element stores energy that cannot be delivered to the load or safely discharged as current through a low-impedance node. In such cases, if the inductive element forces current into a high-impedance node, it will cause the voltage to rise until some destructive breakdown mechanism occurs. Therefore, a method for safely discharging the inductive element is needed.

[0003] The power converter can be used as part of a gate drive unit (GDU) of an inverter in electric vehicle applications. Each GDU requires its own power converter, and the inductive components of the power converter itself require a safe discharge device.

[0004] Overview

[0005] It is desirable to provide an improved discharge unit for a power converter.

[0006] As vehicle electrification increases, it is desirable to design efficient and cost-effective electric vehicle systems by improving voltage discharge methods in power converters.

[0007] 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 being configured to: sense a voltage difference across the inductive element; and activate a discharge path for the power converter based on the voltage difference.

[0008] Optionally, the inductive element is coupled between a first node providing the first voltage and a second node providing the second voltage.

[0009] Optionally, the inductive element includes at least one of an inductor and a transformer.

[0010] Optionally, a voltage sensing unit is included for sensing a voltage difference across the inductive element.

[0011] Optionally, the inductive element is coupled between a first node providing the first voltage and a second node providing the second voltage.

[0012] 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.

[0013] Optionally, the voltage sensing unit is configured to compare the voltage difference with a threshold voltage; and the discharge unit is configured to activate the discharge path based on the comparison of the voltage difference with the threshold voltage, thereby activating the discharge path based on the voltage difference.

[0014] Optionally, the threshold voltage is a preset value.

[0015] Optionally, the voltage sensing unit includes at least one series of one or more Zener diodes, such that the threshold voltage is proportional to the number of the Zener diodes.

[0016] Optionally, the voltage sensing unit is configured to activate the discharge path of the power converter when the voltage difference is greater than a threshold voltage, thereby activating the discharge path based on a comparison of the voltage difference with the threshold voltage.

[0017] Optionally, the voltage sensing unit includes at least one string of one or more Zener diodes, the threshold voltage is proportional to the number of Zener diodes, so that when the voltage difference is greater than the threshold voltage, the conduction current is conducted through the at least one string of one or more Zener diodes.

[0018] Optionally, the voltage sensing unit comprises a resistive element such that an activation voltage is generated when a conduction current is conducted through the one or more Zener diodes of the at least one string.

[0019] Optionally, the discharge unit is configured to disable a discharge path of the power converter based on the voltage difference.

[0020] 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.

[0021] Optionally, the voltage sensing unit is configured to disable the discharge path of 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 and the threshold voltage.

[0022] Optionally, the voltage sensing unit includes at least one string of one or more Zener diodes, and the threshold voltage is proportional to the number of Zener diodes, so that when the voltage difference is less than the threshold voltage, the conduction current is not conducted through the at least one string of one or more Zener diodes.

[0023] Optionally, the voltage sensing unit includes a resistive element such that no activation voltage is generated when the conduction current is not conducted through the one or more Zener diodes of the at least one string.

[0024] Optionally, the discharge path includes a first current source.

[0025] Optionally, a voltage sensing unit is included for sensing a voltage difference across the inductive element.

[0026] Optionally, the voltage sensing unit is configured to compare the voltage difference with a threshold voltage; and the discharge unit is configured to activate the discharge path based on the comparison of the voltage difference with the threshold voltage, thereby activating the discharge path based on the voltage difference.

[0027] Optionally, the voltage sensing unit is configured to activate a discharge path for the power converter when the voltage difference is greater than a threshold voltage, thereby activating the discharge path based on a comparison of the voltage difference and 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.

[0028] Optionally, the voltage sensing unit includes at least one string of one or more Zener diodes, the threshold voltage is proportional to the number of Zener diodes, so that when the voltage difference is greater than the threshold voltage, current is conducted through the at least one string of one or more Zener diodes.

[0029] Optionally, the voltage sensing unit comprises a resistive element such that an activation voltage is generated when current is conducted through the one or more Zener diodes of the at least one string.

[0030] Optionally, the first current source is activated by an activation voltage.

[0031] Optionally, the first current source comprises a first transistor and a second transistor, both comprising a control terminal coupled to the resistance element such that when the activation voltage is generated, both the first transistor and the second transistor are turned on.

[0032] Optionally, when both the first and second transistors are turned on, they conduct a first current.

[0033] Optionally, the discharge path includes a clamping switch coupled to the first current source.

[0034] Optionally, a voltage sensing unit is included for sensing a voltage difference across the inductive element.

[0035] Optionally, the voltage sensing unit is configured to compare the voltage difference with a threshold voltage; and the discharge unit is configured to activate the discharge path based on the comparison of the voltage difference with the threshold voltage, thereby activating the discharge path based on the voltage difference.

[0036] Optionally, the voltage sensing unit is configured to activate a discharge path for the power converter when the voltage difference is greater than a threshold voltage, thereby activating the discharge path based on a comparison of the voltage difference and the threshold voltage; and the discharge unit is configured to close the clamp switch when the voltage difference is greater than the threshold voltage.

[0037] Optionally, when the voltage difference is greater than a threshold voltage, the inductor unit is discharged via the clamp switch.

[0038] Optionally, the clamp switch is configured to operate at a threshold voltage.

[0039] Optionally, the voltage sensing unit is configured to activate the first current source when the voltage difference is greater than a threshold voltage.

[0040] Optionally, the voltage sensing unit includes at least one string of one or more Zener diodes, the threshold voltage is proportional to the number of Zener diodes, so that when the voltage difference is greater than the threshold voltage, current is conducted through the at least one string of one or more Zener diodes.

[0041] Optionally, the voltage sensing unit comprises a resistive element such that an activation voltage is generated when current is conducted through the one or more Zener diodes of the at least one string.

[0042] Optionally, the first current source is activated by an activation voltage.

[0043] Optionally, the first current source comprises a first transistor and a second transistor, both comprising a control terminal coupled to the resistance element such that when the activation voltage is generated, both the first transistor and the second transistor are turned on.

[0044] Optionally, when both the first and second transistors are turned on, they conduct a first current.

[0045] Optionally, the clamp switch is a third transistor comprising a control terminal coupled to the first and second transistors.

[0046] Optionally, the clamp switch is configured to be turned on when it receives the first current.

[0047] Optionally, the discharge unit is configured to disable a discharge path of the power converter based on the voltage difference.

[0048] Optionally, a voltage sensing unit is included for sensing a voltage difference across the inductive element.

[0049] 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.

[0050] 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, thereby disabling the discharge path based on a comparison of the voltage difference with the threshold voltage; and the voltage sensing unit is configured to disable the first current source if the voltage difference is less than the threshold voltage.

[0051] Optionally, the voltage sensing unit includes at least one string of one or more Zener diodes, and the threshold voltage is proportional to the number of Zener diodes, so that when the voltage difference is greater than the threshold voltage, current is not conducted through the at least one string of one or more Zener diodes.

[0052] Optionally, the voltage sensing unit includes a resistive element such that no activation voltage is generated when current is not conducted through the one or more Zener diodes of the at least one string.

[0053] Optionally, when the activation voltage is not generated, the first current source is disabled.

[0054] Optionally, the first current source includes a first transistor and a second transistor, both of which include a control terminal coupled to the resistance element, so that when the activation voltage is generated, the first transistor and the second transistor are both turned on, and when the activation voltage is not generated, the first transistor and the second transistor are both turned off.

[0055] Optionally, when both the first and second transistors are turned on, they conduct the first current, and when both the first and second transistors are turned off, they do not conduct the first current.

[0056] Optionally, the discharge path includes a clamp switch coupled to the first current source.

[0057] Optionally, the discharge unit is configured to turn off the clamp switch when the voltage difference is less than a threshold voltage.

[0058] Optionally, the discharge unit includes a second current source coupled to the clamp switch.

[0059] Optionally, the second current source is configured to turn off the clamp switch when the voltage difference is less than a threshold voltage.

[0060] Optionally, the second current source comprises a resistance element.

[0061] Optionally, the discharge unit comprises an isolation device.

[0062] Optionally, the isolation device is coupled to a second node providing a second voltage; and the isolation device is configured to block a conduction path between the first node and the second node when the second node is coupled to ground.

[0063] Optionally, the power converter includes a power switch coupled to ground, the switch being configured to operate in an on state or an off state.

[0064] 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 further coupled to the second node providing the second voltage.

[0065] Optionally, the discharge unit comprises an isolation device.

[0066] Optionally, an isolation device is coupled to the second node.

[0067] Optionally, the isolation device is configured to block a conduction path between the first node and the second node when the power switch is in an on-state and thus the second node is coupled to ground.

[0068] According to a second aspect of the present disclosure, there is provided an apparatus comprising: a power converter including an inductive element; and a discharge unit for the power converter, the discharge unit being configured to: sense a voltage difference across the inductive element; and activate a discharge path for the power converter based on the voltage difference.

[0069] Optionally, the device is a gate drive unit for a traction inverter.

[0070] Optionally, a chip is included, and the power converter and the discharge unit are implemented on the chip.

[0071] It will be appreciated that the apparatus of the second aspect may include the features set out in relation to the first aspect, and may be combined with other features described herein.

[0072] According to a third aspect of the present disclosure, there is provided a method of discharging a power converter including an inductive element, the method comprising: sensing a voltage difference across the inductive element; and activating a discharge path for the power converter based on the voltage difference.

[0073] It will be appreciated that the method of the third aspect may comprise using and / or providing features as set out in the first and / or second aspects, and may be combined with other features as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The present description is described in more detail below, by way of example only, and with reference to the accompanying drawings, in which:

[0075] Figure 1 is a diagram of a flyback power converter according to the prior art;

[0076] Figure 2 is a diagram of an example embodiment of a discharge unit for a power converter according to the present disclosure;

[0077] Figure 3 is a diagram of another example embodiment of a discharge unit for a power converter according to the present disclosure;

[0078] Figure 4(a) is a graph that can be compared with Figure 3 FIG4( b ) is a first exemplary embodiment of a voltage sensing unit for use with a discharge unit of FIG4( b ). Figure 3FIG4( c ) is a diagram of a second exemplary embodiment of a voltage sensing unit used together with a discharge unit of FIG4 ; FIG4( c ) is a diagram of a second exemplary embodiment of a voltage sensing unit when the voltage sensing unit senses a voltage difference less than a threshold voltage;

[0079] Figure 5 is a diagram of another example embodiment of a discharge unit for a power converter according to the present disclosure;

[0080] Figure 6(a) is coupled to Figure 5 FIG6 (b) is a first exemplary embodiment of a voltage sensing unit of a first current source used with a discharge unit of FIG6 (b) is coupled to a Figure 5 a second exemplary embodiment of a voltage sensing unit of a first current source used in conjunction with a discharge unit;

[0081] Figure 7 is a diagram of another example embodiment of a discharge unit for a power converter according to the present disclosure;

[0082] FIG8( a ) is a diagram of an example embodiment of activating a voltage sensing unit for a discharge path of a power converter; FIG8( b ) is a diagram of an example embodiment of deactivating a voltage sensing unit for a discharge path of a power converter;

[0083] Figure 9 is a diagram of another example embodiment of a discharge unit for a power converter according to the present disclosure;

[0084] Figure 10 is a diagram of another example embodiment of a discharge unit for a power converter according to the present disclosure;

[0085] Figure 11 is a diagram of another example embodiment of a discharge unit for a power converter according to the present disclosure;

[0086] Figure 12 yes Figure 11 A graphical representation of how the discharge unit operates;

[0087] Figure 13 is a diagram of another example embodiment of a discharge unit for a power converter according to the present disclosure;

[0088] FIG. 14( a ) is a first exemplary embodiment of an isolation device that may be used with any discharge unit of the present disclosure; FIG. 14( b ) is a second exemplary embodiment of an isolation device that may be used with any discharge unit of the present disclosure;

[0089] Figure 15 Is shown using Figure 13 A graph showing simulation results of a discharge unit as a part of a gate driving unit;

[0090] Figure 16 is a diagram of a device including any discharge cell of the present disclosure; and

[0091] Figure 17 is a flow chart illustrating a method of discharging a power converter according to the present disclosure. Detailed description

[0092] For power converters with inductive elements, such as those where the inductive element stores energy that cannot be safely delivered to the load or safely discharged through a low-impedance node, the inductive element will force current through a high-impedance node, causing the voltage in the circuit to rise until a destructive breakdown mechanism occurs. This can occur in many cases, for example, when a low-side switch is driving an inductive load without any recirculation path to release the energy when the low-side switch turns off.

[0093] One type of power converter in which this unsafe discharge event can occur is the flyback converter.

[0094] Figure 1 FIG. 1 is a diagram of a flyback converter 100 according to the prior art. The flyback converter 100 includes a low-side switch LS coupled between a ground GND and a node SW. The flyback converter 100 also includes an inductive element 110. In this example embodiment of the prior art, the inductive element 110 includes an inductor L coupled to a transformer T. LK .

[0095] In normal operation mode, when the low-side switch LS is in the on state, the primary winding of the transformer T is charged. When the low-side switch LS is in the off state, the energy stored in the primary winding is transferred to the secondary winding of the transformer T.

[0096] Any energy that cannot be transferred between the primary and secondary windings is represented by the leakage inductance L coupled to the primary winding of the transformer T. LK Each time the low-side switch LS is turned off, the LK The energy in the SW has nowhere to go. This causes the node SW to soar to a high voltage that is at least high enough for the low-side switch LS and the flyback controller ( Figure 1 A common solution is to place a voltage clamp 120 across the primary of the transformer T to clamp the voltage at the node SW to a safe value higher than the input voltage Vin of the flyback converter 100. Then, when the low-side switch LS is turned off, the energy in the leakage inductance can be safely released. Figure 1In the illustrated flyback converter 100, a combination of a Zener diode and a Schottky diode is used to implement the voltage clamp 120. In other embodiments, an external resistor-capacitor snubber may be used.

[0097] These solutions can be applied to other types of power converters. LK Known solutions for the energy saving require off-chip components, which increase the cost and size of the circuit.

[0098] For example, Figure 1 The power converter of the flyback converter shown can be used as part of the gate driver unit of an inverter. The high voltage gate driver unit (GDU) drives the switches of the inverter in electric vehicle applications. Each GDU requires a specific voltage to drive the gate of the insulated gate bipolar transistor (IGBT) or silicon carbide (SiC) power switch. These specific voltages are not available in the system but are generated by a power converter such as a flyback converter. Due to the galvanic isolation requirements needed in automotive systems, at least each high-side switch of the inverter needs to have a separate flyback converter for each GDU. The most common configuration for electric vehicles is a distributed architecture, where there is one GDU and its separate flyback converter for each switch of the inverter. This architecture requires the addition of 12 external voltage clamps on the GDU board. For example, for a 400V / 100kW traction inverter, the additional area required for these off-chip voltage clamps is about 50mm 2 .

[0099] One of the driving requirements for the race to electrify transportation is to design traction inverters with the highest power density (more compact) and reduce cost. Therefore, there is a need for an improved means of safely discharging the inductive elements of a power converter to reduce the cost and area of the circuitry involved.

[0100] Figure 2 FIG2 is a diagram illustrating an exemplary 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. For example, the inductive element 204 may include at least one of an inductor or a transformer. This is not an exhaustive list of possible components.

[0101] The discharge unit 200 is configured to sense the voltage difference V across the energy storage element 204. 差 The voltage difference is the difference between the first voltage V1 and the second voltage V2. The discharge unit 200 is further configured to 差The discharge path DP for the power converter 202 is activated.

[0102] Figure 3 FIG. 2 is a diagram of another exemplary embodiment of a discharge unit 200 for a power converter 202 according to a second embodiment of the present disclosure. Figure 2 The power converters are identical and therefore retain the same label and the parts are considered to have the same Figure 2 The discharge unit 200 has the same function and meaning as Figure 2 The discharge cell in is the same as in , but with the addition of feature 210. Therefore, the same labels are retained and the component is considered to have the same Figure 2 The discharge unit 200 has the same function and meaning.

[0103] The discharge unit 200 includes a sensor for sensing the voltage difference V across the inductor 204. 差 The voltage sensing unit 210 includes an energy storage element 204 coupled between a first node N1 providing a first voltage V1 and a second node N2 providing a second voltage V2.

[0104] The voltage sensing unit 210 is configured to receive a first voltage V1 and a second voltage V2. The voltage difference V sensed by the voltage sensing unit 210 is 差 is the difference between the first voltage V1 and the second voltage V2. The voltage sensing unit 210 is further configured to compare the voltage difference V 差 With the threshold voltage V 阈值 According to the comparison, the discharge unit 210 is configured to activate the discharge path DP for the power converter 200. 差 Greater than the threshold voltage V 阈值 In other words, when V 差 (=V2-V1)>V 阈值 , the discharge path DP is active. The discharge unit 210 is further configured to be based on the voltage difference V 差 To disable the discharge path DP for the power converter 200. 差 Less than the threshold voltage V 阈值 In other words, when V 差 (=V2-V1) <V 阈值 , the discharge path DP is ineffective.

[0105] Threshold voltage V 阈值 It can be a preset value. For example, the threshold voltage V 阈值 It can be set to be equal to the maximum breakdown voltage of the components in the discharge unit 200 and the power converter 202. 阈值 It can be set by the voltage sensing unit 210.

[0106] FIG4( a) is a first exemplary embodiment of a voltage sensing unit 210 that can be used with any discharge unit 200 of the present disclosure. The arrows pointing to nodes N1 and N2 in the figure show the coupling points of the voltage sensing unit 210 to nodes N1 and N2. It should be understood that other couplings are possible according to the understanding of those skilled in the art. In this first exemplary embodiment of the voltage sensing unit 210, the voltage sensing unit 210 includes a string of 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 string. In other words, V 阈值 ∝n, where n is the total number of Zener diodes in the string.

[0107] FIG4( b ) is a second exemplary embodiment of a voltage sensing unit 210 that can be used with any discharge unit 200 of the present disclosure. The arrows pointing to nodes N1 and N2 in the figure show the coupling points of the voltage sensing unit 210 to the nodes N1 and N2. It should be understood that other couplings are possible according to the understanding of those skilled in the art. In this second exemplary embodiment of the voltage sensing unit 210, the voltage sensing unit 210 includes a first string of one or more Zener diodes Z to Z. n and one or more Zener diodes Z' to Z of the second string m In one example embodiment, the one or more Zener diodes of the first string and the one or more Zener diodes of the second string have the same total number of Zener diodes. In other words, n=m. The threshold voltage V 阈值 In this case it will be proportional to the number n=m of Zener diodes in one string. In other words, V 阈值 ∝n, where n is the total number of Zener diodes in one string, and n=m. In another example embodiment, the one or more Zener diodes of the first string and the one or more Zener diodes of the second string do not have the same total number of Zener diodes. In other words, n is not equal to m. The threshold voltage V 阈值 In this case it will be proportional to the sum of the Zener diodes in each string. In other words, V 阈值 ∝(n+m), where n is the total number of Zener diodes in the first string and m is the total number of Zener diodes in the second string. The voltage sensing unit 210 further includes a resistive element R coupled between the one or more Zener diodes of the first string and the one or more Zener diodes of the second string. The resistive element may be, for example, a resistor.

[0108] When the voltage difference V 差 Greater than the threshold voltage V 阈值 When the conduction current I cis conducted through the one or more Zener diodes of the first string and the one or more Zener diodes of the second string and through the resistive element R, so that an activation voltage V a The voltage sensing unit 210 is shown as a combination of a (integrated) Zener diode and a resistor. 差 (=V2-V1) has reached the threshold voltage V 阈值 When the voltage sensing unit 210 has a conduction current I c function.

[0109] FIG4( c ) is an alternative schematic diagram of an example embodiment of the voltage sensing unit 210 of FIG4( b ), relating to an operational configuration when current is not conducted through the voltage sensing unit 210 . The voltage sensing unit 210 is identical to the voltage sensing unit of FIG4( b ), and therefore retains the same labels, and the components are considered to have the same functions and meanings as in FIG4( b ). The arrows pointing to nodes N1 and N2 in the figure illustrate the coupling points of the voltage sensing unit 210 to the nodes N1 and N2 . It should be understood that other couplings are possible, as understood by those skilled in the art. When the voltage difference V 差 Less than the threshold voltage V 阈值 When the conduction current I c The current is not conducted through the one or more Zener diodes of the first string or the one or more Zener diodes of the second string. Therefore, no activation voltage V is generated on the resistor element R. a .

[0110] Figure 5 FIG. 2 is a diagram of another exemplary embodiment of a discharge unit 200 for a power converter 202 according to a third embodiment of the present disclosure. Figure 3 The power converters are identical and therefore retain the same label and the parts are considered to have the same Figure 3 The discharge unit 200 has the same function and meaning as Figure 3 The discharge cell in is the same as in , but with the addition of feature 220. Therefore, the same labels are retained and the component is considered to have the same Figure 3 The discharge path DP includes a first current source 220 coupled to the voltage sensing unit 210.

[0111] The voltage sensing unit 210 is configured to detect the voltage difference V 差 Greater than the threshold voltage V 阈值 The first current source 220 is activated at the same time, so that when the first current source 220 is activated, the discharge path DP for the power converter 200 is also activated.

[0112] FIG6( a) is a first example embodiment of a voltage sensing unit 210 coupled to a first current source 220. The example embodiment of this figure can be used with any discharge unit 200 disclosed herein. The arrows pointing to nodes N1 and N2 in the figure illustrate the coupling points of the voltage sensing unit 210 to the nodes N1 and N2. It should be understood that other couplings are possible according to the understanding of those skilled in the art. The voltage sensing unit 210 includes a first string of one or more Zener diodes Z to Z n and one or more Zener diodes Z' to Zm' of the second string. In one example embodiment, the one or more Zener diodes of the first string and the one or more Zener diodes of the second string have the same total number of Zener diodes. In other words, n=m. The threshold voltage Vthreshold in this case will be proportional to the number n=m of Zener diodes in one of the strings. In other words, V 阈值 ∝n×V 齐纳 , where n is the total number of Zener diodes in one string, and n=m. Voltage V 齐纳 is the breakdown voltage of each Zener diode. In another example embodiment, the one or more Zener diodes of the first string and the one or more Zener diodes of the second string do not have the same total number of Zener diodes. In other words, n is not equal to m. The threshold voltage V 阈值 In this case it will be proportional to the sum of the Zener diodes in each string. In other words, V 阈值 ∝(n+m)×V 齐纳 , where n is the total number of Zener diodes in the first string and m is the total number of Zener diodes in the second string. Voltage V 齐纳 is the breakdown voltage of each Zener diode. The voltage sensing unit 210 further includes a resistance element R coupled between the one or more Zener diodes of the first string and the one or more Zener diodes of the second string. The resistance element may be, for example, a resistor.

[0113] When the voltage difference V 差 Greater than the threshold voltage V 阈值 When the conduction current I c is conducted through the one or more Zener diodes of the first string and the one or more Zener diodes of the second string and through the resistive element R, so that an activation voltage V a Then by activating the voltage V a The first current source 200 is activated. The voltage sensing unit 210 is activated only when V 差 (=V2-V1) has reached the threshold voltage V 阈值 When the conduction current I c Therefore, the first current source is only 差 (=V2-V1) has reached the threshold voltage V 阈值 is activated.

[0114] FIG6( b) is a second example embodiment of a voltage sensing unit 210 coupled to a first current source 220. The example embodiment of this figure can be used with any discharge unit 200 disclosed herein. The arrows pointing to nodes N1 and N2 in the figure illustrate the coupling points of the voltage sensing unit 210 to nodes N1 and N2. It should be understood that other couplings are possible, as understood by those skilled in the art. The voltage sensing unit 210 shown in this figure is the same as the voltage sensing unit 210 shown in FIG6( a), and therefore the same reference numerals are retained, and the components are considered to have the same functions and meanings as in FIG6( a).

[0115] 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 and the second transistor T2 are coupled in series. The first transistor T1 and the second transistor T2 are both coupled to the resistance element R of the voltage sensing unit 210 via their control terminals.

[0116] When the activation voltage V a When the voltage difference V 差 Less than the threshold voltage V 阈值 And no activation voltage V is generated a When , the first transistor T1 and the second transistor T2 are turned off.

[0117] Figure 7 FIG. 2 is a diagram of another exemplary embodiment of a discharge unit 200 for a power converter 202 according to a fourth embodiment of the present disclosure. Figure 5 The power converters are identical and therefore retain the same label and the parts are considered to have the same Figure 5 The discharge unit 200 has the same function and meaning as Figure 5 The discharge cell in is the same as in , but with the addition of the feature SW. Therefore, the same labels are maintained and the components are considered to have the same Figure 5 The discharge path DP includes a clamp switch SW coupled to the first current source 220.

[0118] The voltage sensing unit 210 is configured to detect the voltage difference V 差 =(V2-V1) greater than the threshold voltage V 阈值 When the voltage difference V 差 Greater than the threshold voltage V 阈值When the voltage sensing unit 210 is configured to close the clamp switch SW, thereby activating the discharge path DP. Once the clamp switch SW is closed, the inductor unit 204 is discharged through the clamp switch SW. The clamp switch SW is configured to be at the threshold voltage V 阈值 When the clamp switch is closed (ON), it operates at a voltage equal to the threshold voltage V 阈值 The voltage sensing unit 210 is configured to discharge the inductor element when the voltage difference V 差 Greater than the threshold voltage V 阈值 When the first current source 220 is activated, the clamp switch SW is closed and the inductive element 204 is discharged via the clamp switch SW.

[0119] The discharge unit 200 is further configured to be based on the voltage difference V 差 To disable the discharge path DP for the power converter 200. The discharge unit 200 is configured to 差 Less than the threshold voltage V 阈值 The clamp switch SW is turned off at this time, thereby disabling the discharge path DP for the power converter 200.

[0120] The voltage sensing unit 210 is configured to detect the voltage difference V 差 Less than the threshold voltage V 阈值 The discharge path DP is disabled. When the voltage difference V 差 Less than the threshold voltage V 阈值 , the voltage sensing unit 210 is configured to disable the first current source 220. The clamp switch SW is coupled to the first current source 220. Therefore, when the first current source 220 is disabled, the clamp switch is turned off.

[0121] In summary, the clamp switch SW is used to clamp the voltage generated by the inductive element that attempts to release the stored magnetic energy. It does this by providing a safe discharge path for the current while clamping the voltage to a safe value.

[0122] FIG8( a) is a diagram illustrating an example embodiment of a voltage sensing unit 210 activating a discharge path DP for a power converter 200. Arrows pointing to nodes N1 and N2 in the figure illustrate the coupling points of the voltage sensing unit 210 to the nodes N1 and N2. It should be understood that other couplings are possible, as would be understood by one skilled in the art. Another arrow pointing to the inductive element 204 illustrates the coupling point of the discharge path DP to the power converter 200. It should be understood that other couplings are possible, as would be understood by one skilled in the art.

[0123] The voltage sensing unit 210 includes a first string of one or more Zener diodes Z to Z nand one or more Zener diodes Z' to Zm' of the second string. In one example embodiment, the one or more Zener diodes of the first string and the one or more Zener diodes of the second string have the same total number of Zener diodes. In other words, n=m. The threshold voltage V 阈值 In this case it will be proportional to the number n=m of Zener diodes in one string. In other words, V 阈值 ∝n×V 齐纳 , where n is the total number of Zener diodes in one string, and n=m. Voltage V 齐纳 is the breakdown voltage of each Zener diode. In another example embodiment, the one or more Zener diodes of the first string and the one or more Zener diodes of the second string do not have the same total number of Zener diodes. In other words, n is not equal to m. The threshold voltage V 阈值 In this case it will be proportional to the sum of the Zener diodes in each string. In other words, V 阈值 ∝(n+m)×V 齐纳 , where n is the total number of Zener diodes in the first string and m is the total number of Zener diodes in the second string. Voltage V 齐纳 is the breakdown voltage of each Zener diode. The voltage sensing unit 210 further includes a resistance element R coupled between one or more Zener diodes of the first string and one or more Zener diodes of the second string. The resistance element may be, for example, a resistor. When the voltage difference V 差 Greater than the threshold voltage V 阈值 When the conduction current I c is conducted through the one or more Zener diodes of the first string and the one or more Zener diodes of the second string and through the resistive element R, so that an activation voltage V a The voltage sensing unit 210 is shown as a combination of a (integrated) Zener diode and a resistor. 差 (=V2-V1) has reached the threshold voltage V 阈值 When the voltage sensing unit 210 has a conduction current I c function.

[0124] The discharge path DP includes a first current source coupled to the clamp switch SW.

[0125] The first current source 220 includes a first transistor T1 including a control terminal and a second transistor T2 including a control terminal. The first transistor T1 and the second transistor T2 are coupled in series. The first transistor T1 and the second transistor T2 are both coupled to the resistance element R of the voltage sensing unit 210 via their control terminals. When the activation voltage V is generated a When , both the first transistor T1 and the second transistor T2 are turned on, and both of them conduct the first current I1.

[0126] In this example embodiment, the clamp switch SW is a third transistor including 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) when it receives the first current I1. The clamp switch SW is also configured to be closed when the threshold voltage V 阈值 When the voltage difference V 差 =(V2-V1) reaches the threshold voltage, conduction current I c The current starts to flow through the voltage sensing unit 210 and generates the activation voltage V required to activate the first current source 220. a If the clamp switch SW is properly sized, the control terminal of SW will be at the threshold voltage V 阈值 2 is driven to allow the clamp switch SW to operate in saturation while discharging the inductive element 204.

[0127] The components of the voltage sensing unit 210 , the first current source 220 , and the clamp switch SW are selected to be able to withstand the appropriate voltages they will be utilized with.

[0128] FIG8( b ) is an alternative schematic diagram of the voltage sensing unit 210 of FIG8( a ), in which the voltage sensing unit 210 is deactivating the discharge path DP for the power converter 200 . Arrows pointing to nodes N1 and N2 in the figure illustrate the coupling points of the voltage sensing unit 210 to the nodes N1 and N2 . It should be understood that other couplings are possible, as understood by those skilled in the art. Another arrow pointing to the inductive element 204 illustrates the coupling point of the discharge path DP to the power converter 200 . It should be understood that other couplings are possible, as understood by those skilled in the art. The voltage sensing unit 210 in this figure is identical to the voltage sensing unit 210 of FIG8( a ) and, therefore, retains the same reference numbers, and the components are considered to have the same functionality and meaning as in FIG8( 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 identical to those in FIG8( a ) and, therefore, retain the same reference numbers, and the components are considered to have the same functionality and meaning as in FIG8( a ).

[0129] When the voltage difference V 差 Less than the threshold voltage V 阈值 When the conduction current I c The first string of one or more Zener diodes and the second string of one or more Zener diodes are not conducted. Therefore, no activation voltage V is generated on the resistance element R. a The voltage sensing unit 210 only works when V 差 (=V2-V1) has reached the threshold voltage V 阈值 When the conduction current I cfunction. Therefore, when V 差 When the voltage is less than the threshold, no current I is conducted c .

[0130] When no activation voltage V is generated a , the first current source 220 is disabled. Therefore, when the activation voltage V a When the first transistor T1 and the second transistor T2 are both turned off, they do not conduct the first current I1. Once the inductor 204 is discharged, the voltage difference V 差 will fall back below the threshold voltage V 阈值 This causes the first current source 220 to be deactivated and the clamp switch SW to be turned off.

[0131] Figure 9 FIG. 2 is a diagram of another exemplary embodiment of a discharge unit 200 for a power converter 202 according to a fifth embodiment of the present disclosure. Figure 7 The power converters are identical and therefore retain the same label and the parts are considered to have the same Figure 5 The discharge unit 200 has the same function and meaning as Figure 7 The discharge cell is the same as that of the 230th, but with the addition of features 230 and 232. Therefore, the same label is retained and the component is considered to have the same Figure 7 The discharge unit 200 has the same function and meaning as the discharge unit 200. The discharge unit 200 further includes a second current source 230 coupled to the clamp switch SW.

[0132] The second current source 230 is configured to 差 =(V2-V1) is less than the threshold voltage V 阈值 The clamp switch SW is turned off when the voltage difference V is reached. The second current source 230 includes a resistive element 232. The resistive element 232 can be implemented as a resistor. This is the easiest implementation because it allows the second current source 230 to always be active without requiring an additional signal. The resistive element 232 can be implemented in any manner that provides a current strong enough to generate a voltage difference V 差 Less than the threshold voltage V 阈值 Once the inductive element 204 discharges, the voltage difference V 差 It will fall back below the threshold voltage V 阈值 This will deactivate the first current source 220 and the second current source will keep the clamp switch SW open (off). The clamp switch SW will naturally enter a disabled state, accepting no quiescent current and not requiring any control signal to operate.

[0133] Figure 10FIG. 2 is a diagram of another exemplary embodiment of a discharge unit 200 for a power converter 202 according to a sixth embodiment of the present disclosure. Figure 2 The power converters are identical to those of the 1000 series, so the same labels are retained and the components are considered to have the same functionality. Figure 2 The discharge cell in is the same as in , but with the addition of feature 240. Therefore, the same labels are retained and the component is considered to have the same Figure 2 It should be understood that the additional feature 240 can be additionally applied to any discharge unit 200 described in the present disclosure.

[0134] The discharge unit 200 includes an isolation device 240. The isolation device 240 is coupled to a second node N2 providing a second voltage V2. The isolation device 240 is configured to block a conduction path between the first node N1 and the second node N2 when the second node N2 is coupled to the ground.

[0135] Figure 11 is an illustration of another exemplary embodiment of a discharge unit 200 for a power converter 202 according to the seventh embodiment of the present disclosure. The discharge unit 200 is considered to be the same as any other exemplary embodiment of a discharge unit in the present disclosure. Therefore, the same labels are retained, and the components are considered to have the same meaning and function as already described. It should be understood that any features of the exemplary embodiments described in the present disclosure can be applied to any discharge unit 200 presented in the present disclosure.

[0136] 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. It should be understood that first node N1 and second node N2 are equivalent to first node N1 and second node N2 of other embodiments of power converter 202, and first voltage VIN and second voltage VSW are equivalent to first voltage V1 and second voltage V2 of 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 state or an off state. When power switch LS is in the on state, inductive element 204 is charging. When power switch LS is in the off state, inductive element 204 is discharging.

[0137] Discharge unit 200 includes an isolation device 240. The isolation device is also coupled to second node N2. The isolation device can be, for example, a passive diode. The isolation device 240 is configured to block the conduction path between first node N1 and second node N2 when second node N2 is coupled to ground, for example, when power switch LS is in the on state.

[0138] The voltage sensing unit 210 senses the difference between the second voltage VSW and the first voltage VIN and compares it with the threshold voltage V 阈值 When the difference (VSW-VIN) is greater than the threshold voltage V 阈值 When the difference (VSW-VIN) is less than the threshold voltage V 阈值 When , the first current source 220 is disabled and the clamp switch SW is turned off, so that the discharge path DP is also disabled.

[0139] exist Figure 11 In the exemplary embodiment of FIG. 2 , the discharge unit 200 is shown as an on-chip solution applied to a power converter 202. The clamp switch SW is a transistor. Figure 11 The power converter 202 in FIG. 2 is shown as a flyback converter, but it can be any type of DC power converter. For example, it can be a boost converter.

[0140] Figure 12 It is shown for Figure 11 FIG. 2 is a timing diagram showing how the voltage sensing unit 200 of the power converter 202 operates.

[0141] The top graph, SIG 1, shows the waveform of the control signal that controls the operation of power switch LS. Before point A, SIG 1 is high, and power switch LS is in the on state. Therefore, inductive element 204 is being charged. After point A, SIG 1 is low, and power switch LS is in the off state.

[0142] The middle graph SIG 2 shows the voltage VSW at the second node N2 compared to the voltage VIN at the first node N1. Before point A, the voltage difference V between VSW and VIN is 差 Below the threshold voltage V 阈值 , so the discharge path DP is disabled. At point A, when the power switch LS enters the off state, the voltage across the second node N2 increases by an amount ΔVactive_clamp, which is higher than the voltage across the first node N1. Therefore, the voltage difference V 差 Greater than the threshold voltage V 阈值 And the discharge path DP is activated.

[0143] The bottom graph, SIG 3, shows the current through inductive element 204. Prior to point A, when power switch LS is closed, inductive element 204 is charging, and thus current SIG 3 is increasing. At point A, inductive element 204 begins to discharge through the activated discharge path P. Consequently, current SIG 3 decreases. This current decrease is equal to the sum of I_Vsw_sense (I_Vsw_sense), I_on (I_on), and I_clamp (I_clamp). These are the currents flowing through voltage sensing unit 210, first current source 220, and clamp switch SW.

[0144] When SIG2 is below the selected threshold voltage V 阈值 When the first current source 220 is not active, the second current source 230 maintains the voltage across the control terminal of the clamp switch SW at zero, so that the current through the clamp switch I_CLAMP is equal to zero. The discharge unit 200 does not interfere with the normal operation of the power converter 202 and consumes no current at all.

[0145] When the power switch LS is turned off, the leakage inductance of the inductive element 204 keeps forcing the current into the second node N2. Therefore, the voltage at this node will start to rise. 阈值 At , the voltage sensing unit 210 will activate the first current source 220. If the negative feedback is properly implemented, the control terminal of the clamp switch SW will be kept at the threshold voltage V 阈值 At , the clamp switch SW is saturated, wherein the drain-source voltage is equal to ΔVactiveClamp, and the clamp switch SW will be able to dissipate the energy stored in the inductive element 204 while the voltage at the second node N2 is maintained at the desired clamping voltage.

[0146] Figure 13 is another exemplary embodiment of a discharge unit 200 for a power converter 202 according to the eighth embodiment of the present disclosure. The discharge unit 200 of this figure is considered to be any discharge unit described in the present disclosure, and therefore the same reference numerals are retained, and the components are considered to have the same meanings and functions as those already described. It should be understood that any features of the exemplary embodiments previously described in the present disclosure can be applied to any discharge unit 200 of the present disclosure.

[0147] In this example embodiment, the inductive element 204 of the power converter 202 is depicted as an inductor. The isolation device 240 is implemented as a passive diode D. However, when the power switch LS is turned on and when the second node N2 is coupled to the ground GND, the isolation device 240 can be any element capable of blocking conduction from the first node N1 to the second node N2.

[0148] The isolation device 240 may also be an active diode. Figures 14(a) and 14(b) illustrate example embodiments of an active diode that may be used as part of the isolation device 240 in any of the discharge cells 200 of the present disclosure.

[0149] FIG14( a) is a first exemplary embodiment of an isolation device 240 that can be used with any discharge unit 200 of the present disclosure, as understood by those skilled in the art. The first exemplary embodiment of the isolation device 240 shown in FIG14( a) includes a first transistor 1400, a second transistor 1402, a first diode 1404, and a second diode 1406. The first transistor 1400 and the second transistor 1402 each include a source terminal and a drain terminal. The first transistor 1400 and the second transistor 1402 are coupled in series such that they are coupled together via their 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.

[0150] FIG14( b ) illustrates a second exemplary embodiment of an isolation device 240 that can be used with any of the discharge units 200 disclosed herein, as understood by those skilled in the art. The second exemplary embodiment of the isolation device 240 shown in FIG14( 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 to the first transistor 1410 in parallel 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, and the resistor 1416 is coupled to the source terminal of the first transistor 1410.

[0151] return Figure 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 can be any embodiment described herein. The voltage sensing unit 210 has a voltage difference V between the voltage VSW at the second node N2 and the voltage VIN at the first node N1. 差 The function of conducting current when the threshold voltage has been reached and thus the first current source 220 is activated with negative feedback which keeps the voltage at the second node N2 from drifting.

[0152] The second current source 230 is implemented as a resistor because it is the easiest to implement, as it allows the second current source 230 to always be active without the need for additional signals. However, it can be implemented in any other way that provides a sufficiently strong current to hold the control terminal of the clamp switch SW at zero when the discharge path needs to remain inactive. For example, the second current source can be implemented using a transistor.

[0153] Once the inductive element 204 is discharged, the voltage difference between VSW and VIN will fall back below the threshold voltage, which will cause the first current source 220 to be deactivated and the second current source 230 to hold the control terminal of the clamp switch SW at zero. Therefore, the clamp switch SW will naturally enter a disabled state, not accepting quiescent current and not requiring any control signal to operate.

[0154] Therefore, the voltage across the clamp switch SW is defined as:

[0155] Δv active clamp = Vzb + Vreg + Vzt + VD

[0156] Wherein, Vzb is the threshold voltage of the Zener diode of the first string in the voltage sensing unit 210, Vzt is the threshold voltage of the Zener diode of the second string, and Vreg is the activation voltage (which is equal to V a ) and VD is the voltage across the isolation device 240. Note that the activation voltage can also be defined based on the first transistor M (T1) and the second transistor P (T2) of the first current source 220. The activation voltage is also equal to VSGp + VGSm, which are the control terminal voltages of the first transistor M and the second transistor P. The voltage sensing unit 210 can be implemented as any combination of different components to generate a desired threshold voltage. Any combination of Zener diodes, resistors, and diode-connected transistors can be used to define the threshold voltage.

[0157] Those skilled in the art will be able to identify and analyze the built-in negative feedback, which prevents the voltage VSW at the second node N2 from deviating from ΔVactiveclamp. When the voltage at the second node N2 reaches ΔVactiveclamp, conduction current through the voltage sensing block 210 will begin to flow and generate the activation voltage Vreg required to activate I_on. If the clamp switch SW is properly sized, its control terminal will be driven at the correct voltage to allow the clamp switch SW to operate in saturation with a drain-source voltage equal to (ΔVactiveclamp - VD), while discharging the inductive element 204. If the voltage at the second node N2 rises above ΔVactiveclamp, the current through the voltage sensing block 210 will increase, which will cause Vreg to increase, and therefore the current of the first current source 220 to increase. This will cause the control terminal voltage of the clamp switch SW to increase, and the current through the clamp switch I_clamp will increase, which will have the offsetting effect of lowering the voltage at the second node N2.

[0158] As will be understood by those skilled in the art, preferably the components of the disclosed circuits are selected to withstand the appropriate operating voltages of the system.

[0159] In the specific case of a high voltage gate drive unit (GDU), the discharge unit 200 of the present disclosure allows both the controller of the power converter (in this case a flyback controller) and the voltage clamp (discharge unit) to be integrated onto the GDU die, thereby reducing the cost and area of the GDU board.

[0160] Figure 15 Is shown using Figure 13 Graph of simulation results for the discharge unit 200 as part of a gate drive unit (GDU). The simulation was run over all process and temperature corners of the discharge unit 200 and the power converter 200 (implemented as a flyback converter) for the case when a 1 uH (microhenry) inductive element 204 is charged to approximately 2 A.

[0161] When the power switch LS is turned off, the discharge unit 204 responds to clamp the second node N2 and allows a discharge path (I_On and I_Vsw_Sense not shown here) to be implemented.

[0162] For the particular process used in these simulations, the ΔV active clamping extends from a minimum of approximately 16V to a maximum of approximately 21.6V at the knee point. These minimum and maximum limits need to be selected such that the lower limit does not interfere with the normal operation of the power converter, and the upper limit needs to be kept below the voltage (that the device and components must withstand) that causes reliability issues for the device and components. This spread can also be reduced by carefully selecting the components used in the voltage sensing unit 210 and good layout practices. In cases where the ΔV active clamping needs to be very precise, a fine-tuning strategy can be applied in the voltage sensing unit 210.

[0163] In the specific case of an isolated high voltage GDU for a traction inverter, the discharge unit 200 of the present disclosure is estimated to be only about 6% of the die area of the primary side of the isolated GDU.

[0164] Figure 16 is a diagram of an apparatus 400 according to a ninth embodiment of the present disclosure. The apparatus 400 includes a power converter 202 and a discharge unit 200 for the power converter 202, wherein the power converter 202 includes an inductor 204. The discharge unit 200 can be one of any of the embodiments described in the present disclosure. The apparatus 400 also includes a chip 410. The discharge unit 200 and the power converter 202 are implemented on the chip 410. The discharge unit 200 is configured to sense a voltage difference V across the inductor 204. 差 , and based on the voltage difference V 差 The discharge path DP for the power converter 202 is activated.

[0165] The apparatus 400 may be, for example, a gate drive unit for a traction inverter.

[0166] Figure 17 is a flowchart illustrating a method of discharging a power converter including an inductive element according to a tenth embodiment of the present disclosure.

[0167] At step 510, a voltage difference across an inductive element is sensed. Then, at step 520, a discharge path for the power converter is activated based on the voltage difference.

[0168] It should be understood that the power converter of the present disclosure may be a flyback converter for a gate drive unit. According to the understanding of those skilled in the art, other embodiments may relate to power converters for other applications and for other input voltages.

[0169] Various improvements and modifications can be made without departing from the scope of the present disclosure.

[0170] It will be appreciated by those skilled in the art that variations of the disclosed arrangements are possible without departing from the present disclosure. Therefore, the above description of specific embodiments is made by way of example only and not for limiting purposes. It will be clear to those skilled in the art that minor modifications may be made without significantly changing the described operation.

Claims

1. A discharge unit for a power converter including an inductive element, the discharge unit being configured to: sensing a voltage difference across the inductive element; and A discharge path of the power converter is activated based on the voltage difference. 2 . The discharge unit according to claim 1 , comprising a voltage sensing unit for sensing the voltage difference across the inductor element.

3. The discharge unit according to claim 2, wherein: The inductor element is coupled between a first node providing a first voltage and a second node providing a second voltage.

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

5. The discharge unit according to claim 2, wherein: The voltage sensing unit is configured to compare the voltage difference with a threshold voltage; and The discharge unit is configured to activate the discharge path based on a comparison of the voltage difference and the threshold voltage, thereby activating the discharge path based on the voltage difference. The discharge unit according to claim 2 , wherein: The discharge unit is configured to disable the discharge path of the power converter based on the voltage difference.

7. The discharge unit according to claim 6, wherein: 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 a comparison of the voltage difference and the threshold voltage, thereby disabling the discharge path based on the voltage difference.

8. The discharge unit according to claim 7, wherein: The voltage sensing unit is configured to disable the discharge path of the power converter when the voltage difference is less than the threshold voltage, thereby disabling the discharge path based on a comparison of the voltage difference and the threshold voltage.

9. The discharge unit according to claim 2, wherein: The discharge path includes a first current source.

10. The discharge unit according to claim 9, wherein: the voltage sensing unit being configured to activate the discharge path of the power converter when the voltage difference is greater than the threshold voltage, thereby activating the discharge path based on a comparison of the voltage difference and the threshold voltage; as well as The discharge unit is configured to close the clamp switch when the voltage difference is greater than the threshold voltage.

11. The discharge unit according to claim 10, wherein: When the voltage difference is greater than the threshold voltage, the inductor unit is discharged via the clamp switch.

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

13. The discharge unit according to claim 12, wherein: 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 a comparison of the voltage difference and the threshold voltage, thereby disabling the discharge path based on the voltage difference.

14. The discharge unit according to claim 13, wherein: the voltage sensing unit being configured to disable the discharge path of the power converter when the voltage difference is less than the threshold voltage, thereby disabling the discharge path based on a comparison of the voltage difference and the threshold voltage; as well as The voltage sensing unit is configured to disable the first current source if the voltage difference is less than the threshold voltage.

15. The discharge unit according to claim 14, wherein The discharge unit includes: a second current source coupled to the clamp switch, whereby: The second current source is configured to turn off the clamp switch when the voltage difference is less than the threshold voltage.

16. An apparatus comprising: a power converter, the power converter comprising an inductive element; and A discharge unit for the power converter, the discharge unit being configured to: sensing a voltage difference across the inductive element; and A discharge path of the power converter is activated based on the voltage difference.

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

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